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COVERING MAINTENANCE SOLUTIONS FOR THE INDUSTRY

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First Quantum Minerals brings largest acid plant on-line in Zambia Page 7

IN THIS ISSUE > > > >

Low commodity prices – impact on the sulfuric acid market PAGE 10

Hydrogen incidents in sulfuric acid plants PAGE 31

Pitfalls of using published stainless steel, ductile iron corrosion data for acid plant design PAGE 41

Address Service Requested Keystone Publishing P.O. Box 3502 Covington, LA 70434

PRST STD U.S. PSTG PAID GPI

Sulfuric Acid

COVERING MAINTENANCE SOLUTIONS FOR THE INDUSTRY

Sulfuric Acid T

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www.H 2S0 4Today.com

Fall/Winter 2015

First Quantum Minerals brings largest acid plant on-line in Zambia Page 7

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Vol. 21 No. 2 IN THIS ISSUE > > > >

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Covering Maintenance Solutions for the Industry

FROM THE PUBLISHER

Pitfalls of using published stainless steel, ductile iron corrosion data for acid plant design PAGE 42

Address Service Requested Keystone Publishing P.O. Box 3502 Covington, LA 70434

PRST STD U.S. PSTG PAID GPI

ON THE COVER …

First Quantum Minerals brings largest acid plant on-line in Zambia

DEPARTMENTS 4

Fall/Winter 2015

Low commodity prices – impact on the sulfuric acid market PAGE 10 Hydrogen incidents in sulfuric acid plants PAGE 31

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Industry Insights News items about the sulfuric acid and related industries

18 People on the Move 20 News Bits 28 Product News 40 Lessons Learned

Case histories from the sulfuric acid industry 52

Faces & Places Covering sulfuric acid industry events

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Calendar of Events

Dear Friends,

I’m sad to report we recently lost one of our sulfuric acid family members. Jon Quarles, retired from Acid Piping Technology in 2014 after 47 years in the sulfuric acid industry, passed away on June 24 at the age of 72. He was a gentle and caring family man and colleague, and will be sorely missed by many in the industry. Rest in peace my friend.

As we move forward, we hope that this issue of Sulfuric Acid Today will provide you with some innovative technologies or assistance with your profession. In this issue are several articles regarding the latest technology available to the sulfuric acid industry. Be sure to read such articles as “Low commodity prices—impact on the sulfuric acid market” (page 10), “WESPs: Answering a critical need for gas cleaning efficiency” (page 12), “Solutions for common problems in sulfur spraying” (page 14), “Case studies in next generation furnace designs for sulfuric acid plants” (page 16), “Safety at the forefront of every sulfuric acid project” (page 22), “NOX! Here today, here to stay” (page 24), “Clark Solutions: reflecting on over 20 years in the industry” (page 26), “Direct optical gas monitoring systems: just looking, not touching” (page 30), “Hydrogen incidents in sulfuric acid plants–why now and what can we do?” (page 31), “Sulfuric acid plant training for managers, engineers and operators” (page 38), “Pitfalls of using published stainless steel and ductile iron corrosion

EDITOR April Kabbash EDITOR April Smith MARKETING ASSISTANT Connor Chapman DESIGN & LAYOUT

Mailing Address: P.O. Box 3502 Covington, LA 70434 Phone: (985) 893-8692 Fax: (985) 893-8693 E-Mail: kathy@h2so4today.com www.h2so4today.com SUBSCRIPTIONS U.S. Plant Personnel —‑Complimentary U.S. Subscription —‑ $39 per year (2 issues) Internat’l Subscription —‑$59 per year (2 issues) Subscribe Online: www.h2so4today.com

Sincerely, Kathy Hayward

FEATURES & GUEST COLUMNS

PUBLISHED BY Keystone Publishing L.L.C. PUBLISHER Kathy Hayward

data for sulfuric acid plant design” (page 41), “Maintaining your anodic protection systems” (page 44), “PFA Teflon®-lined butterfly valves eliminate the need for spray shields, allow for easy automated operation” (page 45) and “Successful filtration by improved pumping systems” (page 46).

Jon Quarles 1942-2015 I would like to welcome our new and returning Sulfuric Acid Today advertisers, including Acid Piping Technology Inc., Beltran Technologies, CECO Filters, Central Maintenance & Welding, Chemetics Inc., Clark Solutions, Corrosion Service, El Dorado Metals Inc., Haldor Topsøe A/S, Kimre, Koch Knight LLC, KSB AMRI Inc., OPSIS, MECS Inc., NORAM Engineering & Constructors, Optimus, Outotec, Powell Fabrication & Manufacturing, Roberts Company, Siemens, Southwest Refractory of Texas, Spraying Systems Co., Southern Environmental Inc., STEULER-KCH GmbH, VIP International and Weir Minerals Lewis Pumps.

We are currently compiling information for our Spring/ Summer 2016 issue. If you have any suggestions for articles or other information you would like included, please feel free to contact me via e-mail at kathy@h2so4today.com. I look forward to hearing from you.

10 12 14 16 22 24 26 30 31 38 41 44 45 46 48 49 50

Low commodity prices—impact on the sulfuric acid market WESPs: Answering a critical need for gas cleaning efficiency Solutions for common problems in sulfur spraying Case studies in next generation furnace designs for sulfuric acid plants Safety at the forefront of every sulfuric acid project NOx! Here today, here to stay Clark Solutions: reflecting on over 20 years in the industry Direct optical gas monitoring systems: just looking, not touching Hydrogen incidents in sulfuric acid plants–why now and what can we do?

Sulfuric acid plant training for managers, engineers and operators Pitfalls of using published stainless steel and ductile iron corrosion data for sulfuric acid plant design Maintaining your anodic protection systems PFA Teflon®-lined butterfly valves eliminate the need for spray shields, allow for easy automated operation Successful filtration by improved pumping systems SYMPHOS 2015 draws industry experts world wide Phosphate fertilizer, sulfuric acid professionals gather for annual conference Sulfuric Acid Today hosts Sulfuric Acid Roundtable in Central Florida

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INDUSTRY INSIGHTS WASTE HEAT RECOVERY BOILERS SUPERHEATERS ECONOMIZERS

Sulfuric acid plant slated to open early next year

TORONTO—Tsumeb, Namibia, residents have for the past year been waiting eagerly for the completion of the N$2.7 billion sulfuric acid plant being built at the Tsumeb smelter in Namibia, which is scheduled to open early next year. Once in full operation, the high-tech plant will help reduce toxic emissions from copper smelting. Alina Garises, spokesperson for Dundee Precious Metals Tsumeb, said, “The hot commissioning of the innovative high-tech sulfuric acid plant is now in full swing and the official opening is scheduled for early next year. The plant is designed to capture off-gases that are rich in sulfur dioxide from copper smelting and to convert them into sulfuric acid.” Garises said the acid will be sold as a commercial product predominantly to Namibia’s uranium mines for use in ore-leaching.

Based on an expected throughput of 240,000-310,000 tons of copper concentrate yearly, the acid plant will produce approximately 270,000-340,000 tons of sulfuric acid per annum. “We have taken a giant leap forward in our continuing effort to upgrade the Tsumeb smelter and turn it into a world-class operation,” said Dundee Precious Metals Tsumeb Vice-President and General Manager, Hans Nolte. The Namibian government and Dundee Precious Metals Tsumeb have been working in partnership to expedite the construction and operation of the facility.

Engineering firm Outotec completed construction of the state-of-the-art facility and Dundee Precious Metals Tsumeb entered into a memorandum of understanding with Protea Chemicals Namibia to assist with the marketing and sales of the sulfuric acid that will be produced at the smelter.

For more information, please visit www.dundeeprecious.com.

Op�mus delivered its rst sulfuric acid plant waste heat recovery system in 1996. Across the power and process industries, we’ve produced more heat recovery boilers, HRSGs, superheaters, and economizers than any ac�ve company in the USA. Op�mus and its Chanute Manufacturing plant have a long‐standing rep‐ uta�on for high‐quality workmanship and on‐�me performance. Cus‐ tomers trust our unique manufacturing exper�se and have condence in our quality control and comprehensive project execu�on.   

50 years of manufacturing experience 99% life�me on‐�me delivery performance 20 years experience in Sulfuric Acid waste heat recovery equipment

Ph: 918‐491‐9191 www.op�mus‐tulsa.com Email: info@op�mus‐tulsa.com

PAGE 4

Potash Ridge acquires Valleyfield Fertilizer

TORONTO—Potash Ridge Corp. recently acquired all of the issued and outstanding common shares of Valleyfield Fertilizer Corp., a privately owned corporation registered in Quebec.

Over the last two years under the leadership of Jay Hussey, Valleyfield has advanced development of a sulfate of potash (SOP) project in Quebec utilizing the Mannheim Process. Under the terms of the transaction, Hussey has agreed to become an employee of Potash Ridge and continue to work on the development of the Valleyfield Project, other potential Mannheim opportunities already identified and other activities.

A fully-serviced property has been chosen to develop the Valleyfield Project.

The property is close to sources of the input sulfuric acid as well as being nearby to markets for the by-product hydrochloric acid. A memorandum of understanding has been signed for the offtake of the hydrochloric acid.

Potash Ridge’s President and Chief Executive Officer, Guy Bentinck, said, “Acquiring Valleyfield brings a new dimension to the corporation’s strategy of becoming a premier producer of SOP. While we remain committed to the development of Blawn Mountain in Utah, the Valleyfield Project will allow Potash Ridge to become a producer of SOP in an accelerated timeline and at a very manageable capital cost. The Valleyfield Project is also strategically located to supply SOP to currently underserved markets in North America.”

For more information, please visit www.potashridge.com.

MAA growth subject of new report

NEW YORK, NY—Persistence Market Research Pvt. Ltd. is releasing a new report titled, “Methacrylic Acid Market: Global Industry Analysis and Forecast 2014-2020”. Methacrylic acid (MAA) is a colorless, viscous organic compound with an unpleasant odor. It is a carboxylic acid which is water soluble and mixable with organic solvents. MAA is industrially manufactured on a large scale as a precursor to its esters, specifically polymethyl methacrylate (PMMA) and methyl methacrylate (MMA). MAA is used in an extensive range of applications, most notably in the production of polymers with trade names such as Plexiglas and Lucite.

The global market for MAA is anticipated to be driven by the growth in end-user industries such as construction, automobiles and electronics, where MAA is significantly consumed in light panels, windows, TV display panels, coatings and emulsions among other applications. In addition, technological advancement, coupled with a wide range of broadening applications of MAA, is also expected to contribute toward the growth of the market.

Among the applications, electronics are anticipated to be the fastest growing segment, with rising disposable incomes in developing and emerging economies being one of the major factors driving the demand for electronic equipment and further demand for MAA. Moreover, energy efficient and light weight properties of MAA have contributed significantly to its improving demand in various industries such as transportation and automotive.

Demand for light weight vehicles with lower emissions and better efficiency has witnessed a noticeable boost due to stringent regulatory laws executed in Western Europe and North America.

For more information, please visit www.persistencemarketresearch.com.

Sulfuric Acid Today • Fall/Winter 2015

Rentech to merge with CVR

SUGAR LAND, TEXAS—Sugar Landbased CVR Partners, LP, will combine with Rentech Nitrogen Partners, LP, to create a North American nitrogen fertilizer leader, the companies announced recently. The combination excludes Rentech Nitrogen’s Pasadena facility, which will be retained by current holders of Rentech Nitrogen, or sold separately for their benefit. Total consideration for Rentech Nitrogen excluding the Pasadena facility is $533 million. Rentech Nitrogen shareholders will receive 1.04 units of CVR Partners and $2.57 cash for each unit held. Rentech Nitrogen, a master limited partnership of Rentech Inc., will own 40.5 million units, or 35.6 percent of the combined company.

“We believe this combination with CVR Partners is a compelling opportunity to create value for Rentech Nitrogen’s unitholders. The transaction is structured to provide our unitholders with significant value, as well as the chance to participate in future value creation in a combined partnership that is well-positioned for success,” said Keith Forman, chief executive officer of Rentech Nitrogen. CVR Partners, owned

by Carl Icahn-controlled CVR Energy Inc., will refinance Rentech Nitrogen’s net debt of about $307 million. The deal is expected to close by the end of 2015 and no later than May 2016, the companies said.

Rentech Nitrogen expects to increase its ammonia production by 50 tons per day, and reduce energy input for each ton of ammonia produced by 1.3 MMBTU beginning in the second half of 2016, following the completion of the new ammonia converter project that is currently underway.

For more information, please visit www.rentechnitrogen.com.

PQ and Eco Services agree to merge

MALVERN, Pa.—Specialty inorganic performance chemicals producer PQ has agreed to merge its operations with Eco Services Operations. Planned to be operated under the PQ Corp. name, the combined company will be a major inorganic specialty materials and catalysts producer.

It will be headed by PQ President and CEO George Biltz.

Existing shareholders and equity holders of PQ and Eco Services will remain with the combined business. “The merger brings together two leaders in the inorganic chemicals industry with complementary profiles and exciting growth opportunities,” Biltz said. “Eco Services’ leading position in the North American sulfuric acid market is well-suited to the expertise and skills of our management team members.”

With this transaction, PQ will gain access to a complementary business line, which will create an inorganic chemicals company with capabilities across catalysts, Sulfuric Acid Today • Fall/Winter 2015

Department

INDUSTRY INSIGHTS performance chemicals, potters and eco services. Subject to regulatory approvals, the transaction is expected to be concluded during the fourth quarter.

Eco Services is engaged in sulfuric acid recycling services, and manufactures virgin acid products for various applications, including mining, water treatment and other chemical processes.

Eco-Services operates six large-scale manufacturing facilities, and has a workforce of more than 500.

PQ is a global leader in providing customer solutions through its expertise, innovation and manufacture of specialty inorganic performance materials, highend specialty catalysts and specialty glass materials.

For more information, please visit www.eco-services.com or www.pqcorp.com.

Consortium focuses on raw materials

ESSEN, Germany—Over 100 companies, research and educational institutions from all over Europe have come together under the patronage of the European Union to form EIT Raw Materials.

The consortium has the ambitious vision of turning the challenge of raw materials dependence into a strategic strength for Europe. Its mission is to improve the sustainability, growth and competitiveness of natural resources projects in Europe, while making them more environmentally friendly and socially acceptable. This includes primary deposits, secondary raw material resources (e.g. waste dumps) and new recycling processes, as well as the substitution of critical raw materials.

From the outset, DMT, a global specialist service provider at all levels of the raw materials cycle, is bringing its varied expertise and experience to the table as one of the consortium’s core partners.

“We are especially committed to the introduction of innovative and sustainable products, processes and services,” said Norbert Benecke, DMT’s project manager for the EIT Raw Materials. “This unique cooperation of so many leading companies, research institutes and universities from the natural resources sector in a network of excellence also offers us new possibilities and opportunities to enhance our own innovative strength, market presence and competitiveness.”

DMT and some of its partners in the consortium are already involved in further innovation projects in the framework of the EU-program Horizon2020. This focuses, for example, on the development of new methods for in-situ mining of metals.

Upcoming steps will include participation in a coordination center for the development of natural resource projects specifically in Eastern and South Eastern Europe, as well as innovative technology projects in cooperation with major European mining companies.

For more information, visit www.eitrawmaterials.eu. q PAGE 5

Cover Story

Bringing service to the source with largest acid facility

When you mine copper ore from a very productive source, you also need an efficient way to smelt all that ore and clean the off-gases from that smelting process. The Kansanshi mine in Zambia, the largest copper mine in Africa, is just such a source. But the nearest smelters were 180 kilometers away, in the county’s Copperbelt region. That is, until a new copper smelter, complete with the world’s largest single-train metallurgical gas cleaning and sulfuric acid facility, was built on site.

The Kansanshi mine, which is 80 percent owned by Kansanshi Mining PLC (KMP), a subsidiary of First Quantum Minerals Ltd. (FQM), has undergone several expansions since it began operating in 2005. But adding the new smelter together with a combined gas cleaning/acid manufacturing facility at the mine source makes for a complete and fully integrated operation, turning copper concentrate into anode copper.

First incorporated in 1983, FQM acquired its 80 percent interest in the Kansanshi mine in August of 2001.

Besides its assets in Zambia, the mining and metals company holds assets in Spain, Mauritania, Australia, Finland, Turkey, Panama, Peru and Argentina. Today, FQM is an established and growing company producing copper, nickel, gold, zinc and platinum group elements.

Engineering on the Kansanshi smelter project began in 2011, with the contract for the gas cleaning/sulfuric acid manufacturing facility awarded to Outotec in March 2012. Smelting began in March 2015 with introduction of copper concentrate to the smelter and off-gas to the acid plant. The smelter’s yearly capacity is greater than 300,000 metric tons anode copper. The acid plant’s maximum capacity is 4,400 MTPD. Prior to the new acid plant, the sulfuric acid necessary for leaching oxide copper had been either produced on site via sulfur burning plants, or purchased from smelters in Zambia’s Copperbelt region.

Now with the new plant, the Kansanshi operation is no longer constrained by limited acid capacity or fluctuating acid prices.

Fig. 1: Schematic of independent scrubber pump systems.

Leaving the scrubber, the gas is directed through a droplet separator to remove large entrained droplets. A wet ID-fan provides the necessary suction through the scrubber. This fan’s speed is adjusted to control the gas pressure at the quench tower inlet.

Construction of the Kansanshi new single-train 4,400 MTPD double absorption sulfuric acid plant.

from Peirce-Smith converters (PSCs). The treatment technologies differ based on each gas type’s distinct impurities. Isasmelt™ furnace gas contains condensable metal fumes, such as arsenic, selenium, lead or halides. Converter gas, however, contains mostly mechanically entrained solids. The initial impurity removal step is tailored to the composition of the off-gas, ensuring efficient and reliable gas cleaning at low operating and maintenance cost. Another feature of this approach is that copper-containing dust can be easily separated from the PSC scrubber and recycled back to the smelter facilities. Following the initial separate gas cleaning processes, the gases are then combined for further gas cleaning.

The experience of Outotec with similar plants was one of the key reasons FQM selected Outotec to engineer and supply the project, as per FQM officials.

Outotec’s well proven gas-cleaning technology using high efficiency scrubbers

Gas cleaning: a dual system

The design philosophy for the Kansanshi gas cleaning plant is to remove the impurities directly at the source of occurrence, rather than after mixing all of the off-gas sources. To that end, the core wet gas cleaning unit is specialized to treat two types of off-gas generated from the Kansanshi smelting operation: One type from an Isasmelt™ furnace and the other Sulfuric Acid Today • Fall/Winter 2015

The brick lined towers are equipped with Outotec’s Film Distributor (FIDI™) to minimize acid entrainment and are constructed with Edmeston SX® material.

on the Peirce-Smith converters and overall experience executing projects of this size were also important contributing factors.

Cleaning Isasmelt™ off-gas (primary cleaning)

The gas from the Isasmelt™ furnace is cooled in a waste heat boiler and evaporative gas cooler, and then cleaned in a hot-ESP before entering a brick lined quench tower. In the quench tower, the gas is adiabatically cooled to below 80 degrees C and then directed to a variable throat scrubber to remove solids and condensed fumes by applying a high pressure drop at the variable throat. The variable throat is adjustable to keep a fixed pressure drop under all operating conditions and also to be able to adjust the pressure drop based on the required scrubbing efficiency. This scrubber is made entirely of high alloyed stainless steel.

Both quench tower and variable throat scrubbing stages are equipped with two operating and one standby weak acid circulating pump. The piping is arranged such that the operating pumps discharge into independent spray systems, so that they are fully redundant, while a single such circuit is sufficient for the cooling duty. Additionally, the quench tower has an independent emergency water system.

The emergency water is supplied from a gravity head tank, so in case of a power failure, sufficient cooling is maintained while smelting is stopped to protect the downstream FRP equipment. Fig. 1 shows the independent pump systems.

Cleaning PCS off-gas (primary cleaning)

Off-gas from each individual PeirceSmith Converter is cooled first in an evaporative spray chamber and then directed into a high efficiency scrubber with integrated upper quench section. The quench section is brick lined, while the lower variable throat scrubber section is made of high alloyed stainless steel, similar to the smelter scrubber.

Downstream of the scrubber, the gas route is identical to the smelter gas cleaning. The scrubber is followed by a droplet separator and a wet ID-fan. The PSCScrubber systems are equipped with settling tanks to allow copper dust from PSC off-gas to be recovered in a downstream filter plant.

Cleaning common gas (secondary cleaning)

After receiving their separate treatments, the PSC off-gas and the Isasmelt™ furnace off-gas are combined before entering two parallel packed gas cooling towers (PGCT), operated with weak acid to reduce the moisture content and remove halides. The circulating weak acid for each packed tower is cooled by two parallel plate heat exchangers, with a third heat exchanger installed as standby. Fig. 2 shows a schematic of the common gas cleaning system.

The gas is then finally cleaned by four trains of wet-ESPs, each with two ESPs in series. The casing and collection tubes are made of plastic, while all other internals are made of high alloyed stainless steel. No lead or leaded materials are applied. The clean gas is then directed into the drying tower of the sulfuric acid plant.

PAGE 7

Cover Story

The acid plant offers more flexibility

The 3+1 double absorption acid plant design accommodates the fluctuating SO2 concentrations and varying gas flows typically occurring in Kansanshi’s smelting operation.

While the smelter is a constant strong gas source operating between 50-100 percent of its design load, the batch-operated Peirce-Smith Converters have two major modes: slag blow with weaker SO2 off-gas and copper blow with a stronger offgas. During a blowing cycle, the converters roll in and out several times for charging, skimming, adding reverts, etc. The Kansanshi acid plant is designed to treat the off-gas from the Isasmelt™ furnace plus up to two blowing PSCs. Regarding flow rates, the acid plant is designed for minimum operation with one PSC on slag blow at 110,000 Nm3/h (dry) with about 4.5 percent SO2 by volume. The maximum design case is with the Isasmelt™ furnace on full load plus two PSCs on copper blow, resulting in up to 320,000 Nm3/h (dry) with a SO2 concentration of 13.0 percent SO2 by volume.

Acid plant’s catalytic section

Given variations in gas concentrations and flow, the catalytic section features two process gas coolers for the rejection of excess heat at times where the feed SO2 concentration is high. At low SO2 concentrations where no excess heat is to be rejected, all gas heat is kept within the catalytic section and consequently those gas coolers are bypassed. Fig. 3 shows the basic arrangement.

The two hot heat exchangers (hot and hot re-heat) are integrated inside the SO2 converter to ensure uniform and radial gas distribution to all beds at all operating conditions and also to keep the catalyst at striking temperature during extended idle time or temporary shutdown of the plant. Both internal heat exchangers and the fully welded converter are made of stainless steel. Fig. 4 shows a section of the converter.

PAGE 8

Acid plant’s strong acid section

Fig. 4: SO2 converter with integrated heat exchangers.

The design philosophy for the Kansanshi gas cleaning plant is to remove the impurities directly at the source of occurrence, rather than after mixing all of the off-gas sources. Pictured is the wet gas cleaning section.

Fig. 2: Common gas cleaning system.

All external heat exchangers (cold heat and cold re-heat) are of the radially symmetric disc and doughnut type and made of carbon steel. The cold re-heat exchanger employs Outotec’s horizontal stainless steel part (CORD™). This increases the temperature of the gas originating from the intermediate absorber by approximately 20 degrees C, which promotes conditions that help minimize corrosion.

This ensures that no iron sulfate formation and subsequent plugging of the gas path can occur, which may occur due to potential carry over from the intermediate absorber.

Gas inlet temperatures to each bed are controlled by the addition of cold bypass gas and are kept constant at all operating conditions. With the large size of the plant vessels, the risk of uneven gas distribution and vary-

ing gas temperatures must be avoided. To ensure adequate gas mixing was achieved, Outotec’s design phase included extensive CFD modeling to simulate gas mixing devices.

In a typical scenario, the first bed inlet temperature might contain a mixture of hot SO2 gas leaving the hot heat exchanger (~460 degrees C) and the cold bypass (~100 degrees C). These gases must be mixed within a very short time to arrive at a uniform entry temperature to bed 1 catalyst of 400 degrees C. The location of the gas mixing device is depicted in Fig. 4.

The mixing device is shown in Fig. 5 along with the results of the CFD modeling showing that a good control temperature (400 +/- 5 degrees C) was achieved.

Treating off-gas from a single PSC on slag blow, with only ~4.5 SO2 percent by vol-

Fig: 3: Catalytic section of Kansanshi sulfuric acid plant.

ume, the plant would operate below the autothermal point and hence require energy input from the preheater. However, since this situation only occurs for a relatively short time, the acid plant can maintain acceptable catalyst temperatures, utilizing the thermal mass of the plant without using the preheater.

Two electrically driven SO2 blowers operate in parallel. The blowers are equipped with inlet guide vanes for flow control.

Also, a recycle line is installed from the blower discharge to the inlet of the drying tower so that the blowers can remain operating without rapidly cooling the catalyst during short periods where no gas is offered from the smelter. The recycle line also keeps the plant ready to receive off-gas at any time, rather than struggling with frequent stopping and starting of the large blower motors.

The strong acid section employs Outotec’s flowsheet where both the intermediate and final absorber acid circuits are operated with a common pump tank, while the drying tower is equipped with a separate pump tank. The brick lined towers are equipped with Outotec’s Film Distributor (FIDI™) to minimize acid entrainment. The distributors are made of Outotec’s proprietary Edmeston SX® material. The acid temperature to the absorbers is controlled by means of an acid bypass around the coolers.

During periods where very low SO2 concentration gas is processed for a longer time or while preheating, the water balance of the plant cannot be kept when producing 98.5 percent H2SO4.

Increased flexibility is provided, therefore, by optionally exporting drying tower acid to the product acid tanks.

All acid coolers are shell and tube type with anodic protection. The absorber coolers operate in co-current flow while drying tower and product coolers are in counter current arrangement.

All strong acid piping is made from Outotec’s Edmeston SX® material.

Final product acid is stored in four 7,500-tonne storage tanks located south of the acid plant and then transferred a distance of 1.9 km to the existing Kansanshi mine storage tanks where it is used for leaching operations.

Training operations staff

Fig. 5: Bed 1 by-pass mixing device (top) and CFD model showing proper temperatures achieved.

Virtually all the operators had previous experience as operators in sulfuric acid plants either in KMP’s own sulfur burning acid plants or from acid plants in the Zambian Copperbelt.

However, many of the operators had experience only with sulfur burning acid plants and were unfamiliar with metallurgical acid plants, particularly with the gas cleaning systems.

Operator training began in October 2014, well in advance of the start-up. Training began with classroom sessions and presentations prepared by supervisory staff. After each classroom session a visit was

Sulfuric Acid Today • Fall/Winter 2015

Optimization through integration

Because smelters and acid plants are typically designed separately by different groups, their operations are often only loosely linked. KMP and Outotec recognized that the operation of the overall plant could be optimized by tightly integrating the sections. The key objectives of the integration were: • Steady pressure control at the inlet of the gas cleaning plant, so that gas sources starting and stopping don’t cause off-gas flow fluctuations for the other sources.

• Automation of dilution air control based on the calculated off-gas flows and compositions, to achieve steady SO2 concentration at the acid plant converter.

• Automation of the starting and stopping of off-gas from each source, to minimize fugitive emissions.

• Ensuring the controlled shutdown of gas sources when acid plant upset conditions occur, minimizing the chance of fugitive emissions.

Where possible, gas sources should stop prior to an acid plant trip, to avoid fugitive emissions.

Steady wet gas cleaning pressure control was achieved by implementing feed-forward control for each off-gas source.

Feed-forward control is particularly important for the PSCs, which frequently start and stop generating off-gas. Control of SO2 blower throughput (via IGVs and recycle line) and wet ID-fan throughput are automatically linked so that as the flow increases/decreases through the wet ID-fan, the SO2 blowers automatically adjust with-

Gas cleaning section of Isasmelt™ off-gas.

out waiting for a change in gas cleaning pressure.

Dilution air is controlled automatically based on calculated dry flowrates and SO2 content of each gas source. The dry flowrates are calculated using wet ID-fan power consumptions and off-gas temperatures. The SO2 contents are calculated based on the concentrate composition and converter blowing rate (with different factors for slag and copper blows). Based on the input off-gas, the required dilution air flowrate is calculated. In addition to the automatic wet gas cleaning pressure control, and the sophisticated dilution air control system, sequences were implemented to enable easy starting and stopping of each off-gas source.

The sequences allow an off-gas source to start (if the acid plant is ready for additional off-gas) or stop without operating intervention. The acid plant control room operator simply gives permission for each source to operate, and monitors the plant.

Typically the acid plant control system (software and safety systems) protects the acid plant during upset conditions by tripping the SO2 blowers and/or wet ID-fans. For example, if the offgas temperature leaving a wet gas scrubber is excessively high, the wet ID-fan will trip to prevent damage to the gas cleaning plant.

Tripping the SO2 blowers and/or wet ID-fans creates an emergen-

Sulfuric Acid Today • Fall/Winter 2015

Packed gas cooling towers with plate type weak acid coolers.

cy situation at the furnaces, as the generation of off-gas must cease immediately. In many situations the upset acid plant condition (which would lead to a SO2 blower or ID-fan trip) can be avoided by stopping the off-gas flow.

Although stopping the off-gas flow leads to short term production losses, avoiding emergency situations and keeping equipment running (i.e. avoiding trips) leads to faster restart times, and avoids the possibility of fugitive emissions. To ensure that the off-gas source is stopped before acid plant equipment trips, an extra control system alarm was implemented for critical parameters.

For example, for a scrubber exit temperature, the following alarm levels were configured: • High Alarm: trips an operator warning.

• High High Alarm: automatically stops the off-gas source. As the off-gas source is stopped before a loss of suction from the acid plant, a normal controlled shutdown can be performed, rather than an emergency shutdown.

• High High High Alarm: trips the wet ID-fan.

Successes and challenges

In contrast to many plants of its size, hot commissioning of the overall smelting operation took

just two months. FQM officials credit excellent construction and equipment quality along with a well-trained workforce. Having the acid plant on site, cleaning gas at the source, was also instrumental to a quick start-up.

Having a tightly integrated smelting/gas-cleaning/acid system on site also ensures compliance with SO2 emissions mitigation. In the unlikely event that the acid plant becomes unavailable, the smelter off-gas sources shut down automatically before any SO2 emissions occur. In fact the overall smelter/acid plant operation has proven to be reliable enough that Kansanshi has mothballed its sulfur burning acid plants, relying only on the acid produced in the new plant to feed their oxide leach operation.

Naturally, the project was not without its challenges, principally time constraints and distance. An aggressive schedule meant pre-ordering materials, such as stainless steel, before equipment design was complete.

Fortunately, Outotec’s longstanding relationships with its manufacturing partners enabled a reduction in project duration of about three months.

Another hurdle involved moving equipment and supplies some 2,700 kilometers from the main supply harbor. The long travel distance was a major impact to the timetable, and costs were high because of transport restric-

tions. To offset these expenses, Outotec and FQM collaborated on optimizing the dimensions of prefabricated items to minimize the overall installed cost.

And then the usual technical issues came up during testing and commissioning. Fortunately none of these problems delayed commissioning or halted production later. Some of these include:

During cold commissioning with water, the header of the distributor pipe inside a packed gas cooling tower came apart. The failure was attributed to excessive water flow, due to oversized circulation pumps. The distributer was repaired and a valve adjusted on the pumps to restrict flow with reliable results. Parts of the distributer will be changed in the future, but the function of the cooling towers is not affected.

In testing wet-id fans and their associated droplet separators, the vanes of the droplet separator detached from their central hub. The failure was caused by a flow rate that was much higher than the design was meant to handle. The flow was generated because the ID fan’s pressure drop was significantly lower in the test because the gas was taken through a nearby man hole rather than through the normal gas path. The normal gas route was isolated from the gas cleaning system because of preheating the brick work in the PSC. After identifying the cause, the flow was reduced to within actual operating conditions and the droplet separators worked normally.

During hot commissioning, distribution caps on cold bypass discharge nozzles caused excessive pressure drop in the cold bypass, restricting the cold gas flow, which resulted in an elevated bed 4 inlet temperature.

The temperature to bed 4 could not be lowered even though the bypass was fully open. The solution identified is to open up the distribution caps to allow more gas flow.

Since hot commissioning last March, acid production at Kansanshi has been steadily increasing. Moving forward, the focus is to maintain optimal working order and continue with operating improvements. q PAGE 9

Cover Story

made to the plant to view the equipment and system presented.

In many cases the system was still under construction, which gave the operators an opportunity to see inside the equipment. Testing of the operators’ comprehension and knowledge was done after each section to ensure that the key principles were understood.

Acid plant operators were also extensively involved during the commissioning of the acid plant as part of their hands on training.

Feature

MARKET OUTLOOK

Low commodity prices—impact on the sulfuric acid market By: Fiona Boyd, Principal for Sulphur and Sulphuric Acid, Argus Media

Global crude oil prices came under sustained downward pressure beginning in mid-June 2014. Lower crude prices translated into healthy demand for refined products because of lower costs for consumers. The strong refinery utilization rates that accompanied the crude price drop have supported sulfur production. In 2014, 47 percent of sulfur supply, or 26.6 million tons, came from refining. The strong sulfur production did not translate into lower prices, however, because of stable demand for sulfuric acid production for primarily phosphate fertilizer production and, secondly, base metals production.

But by August 2015, signs of weakness in both sectors emerged that are expected to have an impact on both the sulfur and sulfuric acid markets.

In the case of phosphate fertilizers, the outlook for the market turned increasingly bearish by mid-September, primarily because of macroeconomic factors. In India, the largest import market for diammonium phosphate (DAP), the weakening of its local currency, the rupee, as well as lower than anticipated rainfall and high stocks of finished product slowed buying. In Brazil, the largest importer of monoammonium phosphate (MAP), the weakening of its local currency, the real, as well as credit issues limiting farmer purchasing power, stalled import demand. In the United States, low crop prices have led to questions regarding fall demand for products such as DAP and MAP. Given the cloudy outlook for phosphate fertilizers, Chinese producers began to pull back from purchasing

Argus to host only fertilizer conference held in Africa for 2016 LONDON – The seventh Argus FMB Africa Fertilizer Conference will be held February 24-26, 2016 in Marrakech, Morocco. The 2015 event in Addis Ababa, Ethiopia attracted 400 delegates in 55 countries with a record number of delegates from Africa. The Argus Africa Fertilizer conference will participants the opportunity to meet the market -- from leading producers to major buyers and distributors, and all categories of essential service providers. Hear the latest market developments from industry experts and analysts during two mornings of insightful discussions. The exhibition space features the latest technology, equipment, logistics and service providers from around the world. This year’s event will focus on bulk blending versus processing, multi-nutrient application and soil mapping in Africa.

This is the only fertilizer conference held in Africa in 2016. Participants will have opportunity to meet professionals from across the fertilizer supply chain, the chance to meet fertilizer producers and traders from over 20 African countries, 20+ hours of networking, opening cocktail reception and gala dinner, 20+ expert speakers and 3 days of discussions with senior decision makers.

For further information about the 2016 Argus FMB Fertilizer Africa conference, please visit www. argusmedia.com. q

PAGE 10

sulfur. China is the largest consumer of sulfur and its buying patterns strongly influence price direction in the traded market. As an indication, by the second week of September, Chinese buyers had secured granular sulfur metric tons in the $130-135/t cost-in-freight (cfr) range compared with prices as high as the $170s/t cfr in March. In response, Middle East producers slashed prices for September.

prices dipped to around $2.25 per pound, near a six-year low. In order to adjust its business amid the weak market conditions, Freeport announced it would modify operations in a number of regions, including Chile, the largest import market for sulfuric acid. Freeport specifically noted it would reduce mining and stacking rates by around 50 percent at its El Abra facility, which consumes as much as 900,000 tons

Short-term focus is on phosphate demand levels in the key markets of India, Brazil and the United States. This is occurring at a time when sulfur production is growing as new supply capacity comes on stream, therefore increasing availability.

While the decline in oil prices has impacted spending plans of energy companies, it has not yet resulted in a significant downward revision to the sulfur production forecast as many projects that will add supply are still progressing.

For example, Kuwait state-owned KPC did not shelve plans for its new Al Zour refinery, despite seeking lower prices related to bids from contractors. In addition, a large proportion of future supply will be from natural gas processing and large-scale projects, such as Shah in Abu Dhabi, are commencing operations after years of delay. That being said, the emergence of the surplus is dependent on the successful ramp-up of the projects forecast to add supply and utilization of that capacity after ramp-up.

If demand for phosphate fertilizers, the largest consumer of sulfuric acid, is suppressed amid stable sulfur supply, continued downward pressure on prices can be expected.

This in turn will result in lower raw material costs for sulfuric acid producers. As an indication, Argus estimates around 239 million tons of sulfuric acid were produced on a global basis in 2014 of which around 147 million tons, or 62 percent, were produced through the burning of elemental sulfur.

Meanwhile, bearish conditions in the base metals sector could translate to further downward pressure on sulfur prices and demand, as well as prices for traded sulfuric acid, which is primarily produced as by-product through metals smelting. In 2014, around 72 million tons, or 31 percent, of sulfuric acid were produced as an involuntary and generally unwanted by-product of the smelting industry.

Copper prices reached near six-year lows in August and companies began to announce adjustments in operations in order to reflect the climate of lower commodity prices. In late August, Freeport McMoRan announced revised capital and operating plans resulting in lower production and operating levels. The company-reported LME copper prices averaged $3.11 per pound in 2014 and $2.69 per pound in the six month period ending June 30, 2015. In the third quarter,

per year. While an equal 50 percent reduction in sulfuric acid consumption is not expected, it is understood Freeport will reduce its consumption of sulfuric acid at El Abra by several hundred thousand tonnes. In the United States, where Freeport consumes sulfuric acid as well as producing it through smelting and sulfur burning, a significant reduction in consumption is also anticipated. Meanwhile, in September, Glencore announced it would suspend copper production at its Katanga and Mopani operations in Africa for 18 months.

At present, the impact on the sulfuric acid market has not been material, but length has been overhanging the Chilean market because of March flooding that impacted operations and a slower-than-anticipated ramp up of the new Antucoya sulfuric acid-consuming project. This resulted in cargos being diverted away from Chile to Brazil and the United States. This meant smelter acid producers in northwest Europe, the primary offshore suppliers to Brazil and the United States, were facing competition to place volume. While an immediate crash in prices did not occur, indications of lower sulfuric acid consumption in markets such as Chile and the United States limits any chance of upward price movement. For now, production of sulfuric acid through base metals smelting seems less affected than acid-consuming operations.

In summary, sulfur production is stable and trending up. Meanwhile, the outlook for the primary consuming markets of phosphate fertilizers and base metals is less certain. In the end, both the sulfur and sulfuric acid markets will find a way to balance themselves largely because of the inelastic nature of the products as what is traded is mostly involuntary production.

Argus Media publishes weekly global reports on sulfur and sulfuric acid as well as reports on fertilizer-related products including nitrogen, ammonia, potash and phosphate.

North American-specific publications for both fertilizers and the sulfur/sulfuric acid markets are also available. For more information on Argus and its portfolio of fertilizer publications, please visit www.argusmedia.com/fertilizer. Argus also offers consulting services, including single-client studies and a presentation service for sulfur and sulfuric acid supported by our proprietary supply and demand model. q Sulfuric Acid Today • Fall/Winter 2015

Feature

WESPs: Answering a critical need for gas cleaning efficiency

Advanced wet electrostatic precipitators maximize gas-cleaning performance for sulfuric acid plants By: Michael Beltran, President and CEO, Beltran Technologies, Inc.

History and technology have created an enduring link between two of the world’s core industries: sulfuric acid production and metals extraction and refining.

This is mainly due to the fact that metallurgical processing remains the primary source of the sulfurous emissions from which industrial-grade sulfuric acid is derived. Pyrometallurgical smelting and refining operations emit particulates, fumes and sulfur dioxide, which must be treated before discharging to the atmosphere. The most common method of controlling these emissions is the use of a downstream metallurgical sulfuric acid plant. Purified sulfuric acid is the desired by-product.

Despite the lingering effects of a global economic recession, including fluctuations in commodity prices and markets, analysts expect continued demand for highquality sulfuric acid—the world’s most widely used industrial chemical. Sulfuric acid plays a critical role in hundreds of industrial processes, especially agricultural fertilizer manufacturing, which consumes 70 percent of H2SO4 production worldwide.

Sulfur provides both a direct nutritive value for plants, and serves as a soil amendment.

It also facilitates a plant’s use of the three other major soil nutrients: nitrogen, phosphorus and potassium.

On the other hand, the metals industries—ferrous and nonferrous—have been undergoing a major retrenchment over the last several years as a result of declining demand. Yet, experts anticipate that continued global demand for mined resources, especially in developing nations, will eventually be sustained by such forces as sheer population growth, increasing urbanization, rising incomes and heightened expectations.

A third factor affecting sulfuric acid production and markets is the growing worldwide concern for environmental quality, including demands for more effective gas cleaning and air pollution control equipment in the metallurgical industries.

Environmental concerns are taking on increasing prominence as major metals and mining companies venture into ever more remote corners of the globe. Indeed, much of the world’s new exploration and development is occurring within the borders of less-developed nations. Often, they are driven by the increasing scarcity of higher grade ore deposits in traditional, more easily accessible mining regions. In addition, many legacy mineral deposits lay deeper underground and contain more complex mineralogy, making them more difficult and expensive to find, extract and process.

PAGE 12

However, as metallurgical activity ventures more into remote, less-developed regions, states within those regions are demanding more from mining and processing companies in the areas of transparency, financial accountability and corporate responsibility—with particular emphasis on sustainable development and environmental protection. This means increasingly stringent air pollution regulations, which will require substantial new investments in modern pollution control equipment and techniques.

For metallurgical operations such as roasters, smelters and refineries, companies caught in a tight market are striving to achieve greater performance efficiencies and control costs, while satisfying more stringent environmental regulations.

Advanced gas cleaning and emission control strategies continue to evolve in response to increasingly stringent environmental mandates worldwide, as well as to the increasing complexity, toxicity and corrosiveness of industrial exhaust and process gas streams. Innovations and investments in emission control systems are also driven by the relentless need for plant operators to achieve ever greater operating efficiency, control costs and stay ahead of the regulatory compliance curve.

To reduce contaminants before entering the sulfuric acid plant, owners have relied on several gas cleaning techniques, such as scrubbers, cyclones and fabric filters. These systems can control large particulates, but are usually energy-inefficient or impractical to use on fine particulates,

WESPs efficiently capture acid mists and other fine particulates from a multi-mineral refining operation in Peru.

When emissions of sulfur dioxide exceed five to seven percent of gas-stream volumes, a common and cost-effective solution is the incorporation of downstream sulfuric acid manufacturing plants, whose non-discretionary by-product is purified sulfuric acid. However, an efficient sulfuric acid manufacturing process requires the maximum possible removal from input gas streams of fine particulates, acid mists, condensable organic compounds and other contaminants. This is necessary for protecting sensitive acid plant components such as catalyst beds from corrosion, fouling and plugging, as well as for preventing the formation of a “black” or contaminated acid end-product. Proper gas cleaning also results in reduced corrosion damage, plus lower costs of maintenance, operations and equipment replacement.

acid mists, oily residues or condensed organic compounds. Therefore, many operators rely on modern wet electrostatic precipitators (WESPs), which can clean complex gaseous emissions of particulates and acid mists down to submicron scale (PM 2.5) with up to 99.9 percent efficiency, and very low energy drain. However, WESPs can vary greatly in design, materials, gas flow rates and durability, as well as collection efficiency. It is thus important for engineers to recognize the key differences among these various systems.

Advanced WESPs are designed around a multistage system of ionizing rods with star-shaped discharge points.

These are encased within square or hexagonal tubes that are lined with grounded collection surfaces. The unique electrode geometry generates a corona field 4-5

times stronger than that of conventional wet or dry ESPs. The multistage charging configuration also avoids corona quenching due to high particle densities, and assures maximum corona field strength with a minimum of energy load.

As flue gas travels through the tubular array, the intense corona induces a powerful negative charge, propelling even submicron-size particulates and sulfuric acid droplets toward the collection surfaces, where they adhere as cleaned gas is passed through. The surfaces are cleansed of residues by recirculating water sprays, which can be deployed intermittently or continuously, as the need arises.

With virtually no physical or mechanical obstruction of gas streams, there is very little pressure drop through the WESP, and throughput velocities can be extremely high. This enables plant engineers to use smaller-scale, less costly equipment for specific gas volumes and still achieve superior collection efficiencies. The use of smaller, simpler equipment, combined with modular unit designs, also makes WESP equipment extremely adaptable to a wide range of existing industrial equipment, with minimum reconfiguration and lower space requirements.

The cool, saturated environment in the WESP makes the system highly effective on condensable or oily compounds, while the continuous aqueous flushing process prevents re-entrainment of particles, sticky residue build-ups and particle resistivity. By eliminating the need for mechanical or acoustical rappers, the cleansing process also minimizes energy and maintenance costs.

Other critical features to look for in WESP equipment are sophisticated electronic controls linked to a close-coupled gas flow management system; these components can squeeze even more efficiency out of the system by optimizing such operating parameters as gas velocity, saturation, temperature, corona intensity, etc.

Versatile and adaptable to a wide range of operating conditions, modern WESPs are currently producing excellent results worldwide for a host of industrial applications, including sulfuric acid plants, mining and metallurgy, power generation, petroleum refining, pulp and paper, cement, chemicals, industrial boilers and more.

Michael R. Beltran is President and CEO of Brooklyn, N.Y.-based Beltran Technologies, Inc. For more information, please email beltran@earthlink.net or visit www. beltrantechnologies.com. q Sulfuric Acid Today • Fall/Winter 2015

World-class Technology for Worldwide Markets We deliver a wide range of products and services, from engineering studies through to full EPC projects for the Sulphuric Acid Industry

Products & Services: Acid Plants ▪ ▪ ▪ ▪ ▪

Sulphur Burning Metallurgical Spent Acid Regeneration Acid Purification & Concentration Wet Gas

Proprietary Equipment ▪ ▪ ▪ ▪ ▪ ▪ ▪

Converter Gas-Gas Exchanger Acid Tower (brick lined and alloy) Acid Cooler Furnace SARAMET® piping & acid distributor Venturi Scrubber

Technical Services ▪ ▪ ▪ ▪ ▪ ▪

Turnaround inspection Operations troubleshooting Process optimization Feasibility studies CFD (Fluent) analysis FEA (Ansys) study

Chemetics Inc. (headquarters)

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Suite 200 – 2930 Virtual Way Vancouver, BC, Canada, V5M 0A5 Tel: +1.604.734.1200 Fax: +1.604.734.0340 email: chemetics.info@jacobs.com

2001 Clements Road Pickering, ON, Canada, L1W 4C2 Tel: +1.905.619.5200 Fax: +1.905.619.5345 email: chemetics.equipment@jacobs.com

www.jacobs.com/chemetics

Chemetics Inc., a Jacobs company

Feature

Solutions for common problems in sulfur spraying (8 lpm) to reduce the flow rate.

Note the streaky spray pattern, condensed coverage and larger droplets at the lower pressure as compared to the upper picture.

When comparing the two photos of the FloMax air atomizing nozzles, the change is more subtle and no visual difference can be detected. The performance is more consistent even at the lower flow rate and pressure.

Problem #1: Achieving proper atomization Solution: Understand drop size The reason atomization is so important in sulfur burning is that it has a direct impact on the rate of heat transfer between the combustion gas and the sulfur.

Spray nozzles used on sulfur guns are often selected based on flow rate. A better approach is to select spray nozzles based on drop size and performance. Here’s why: • A single droplet with a diameter of 500 microns has roughly the same volume as 121 droplets with diameters of 100 microns.

• However, the surface area coverage of the smaller droplets is approximately 484 percent larger.

• This increased surface area increases the rate of heat transfer.

• The smaller droplets decrease the likelihood of sulfur impingement on furnace walls and baffles and the chance of sulfur carryover.

Optimizing sulfur spraying is dependent on many variables including atomization, drop size, residence time, gun placement and operating conditions in the furnace. Computational Fluid Dynamics (CFD) modeling is a powerful tool that can determine the optimal drop size for full evaporation and complete vaporization prior to installation to minimize production disruptions.

In addition to ensuring proper atomization will be achieved, CFD can also determine the best placement for the guns to avoid sulfur wall contact and carryover to downstream equipment.

Problem #3: Plugged nozzles

CFD model shows the difference in wall impingement when using hydraulic nozzles (top) and air atomizing nozzles (bottom).

range. Spray performance needs to be consistent during start-up, low flow operation and peak flow operation.

Pressure is changed to obtain different flow rates.

However, when pressure is changed, spray performance changes as well. For example, when using hydraulic nozzles, a decrease in pressure results in an increase in drop size and contraction of the spray pattern and coverage, and leads to incomplete evaporation or vaporization. There are a few options for solving this problem:

• •

•

Use nozzles with a high turndown ratio.

Use multiple sulfur guns and control flow rate by turning guns on or off and/ or adjusting the operating pressure of the individual nozzles on the guns.

Consider changing from hydraulic to air atomizing nozzles. While pressure adjustments still affect performance, the changes are more subtle. This is because the atomizing air pressure can be adjusted along with the feed pressure in order to help

maintain more consistent performance across a wider range of flow rates.

Refer to the four images below. The upper left image shows a BA WhirlJet® hydraulic nozzle spraying at 5 gpm (19 lpm) and the upper right shows a FloMax® air atomizing nozzle spraying at 5 gpm (19 lpm) which represents normal operating conditions. As production decreases, there is a need to decrease the flow rate in the furnace which is sometimes accomplished by lowering pressure. The image on the lower left shows the same BA hydraulic nozzle lowered to spraying 2 gpm

Problem #2: Maintaining consistent spray performance Solutions: Use nozzles with a high turndown ratio or consider air atomizing nozzles Another common problem challenging sulfur producers is maintaining consistent performance over a wide operating PAGE 14

The difference between hydraulic nozzles and air-atomizing nozzles under different levels of pressure is easy to see.

Solutions: Evaluate air atomizing nozzles, hydraulic nozzles with clean-out ports and/or purge with steam or air

Plugged nozzles are another frequent and disruptive problem, not unique to sulfur spraying.

Whenever there is a set orifice size, there is potential for something to build up or lodge within that orifice. Installing properly sized strainers upstream of the nozzle is important and can often eliminate plugging.

Plugging can also be caused by contaminants, such as carsul, in the sulfur, or molten sulfur may solidify inside the nozzle when operating at lower flow rates or when sulfur guns are removed. The solidification is caused by the loss of velocity that is present when operating at higher pressures.

Possible remedies to these plugging problems are to use a sulfur gun that has a cleanout port, or purge with steam or air. Another approach is to use air-atomizing nozzles. The atomizing air pressure continually moves any low flow sulfur through the gun and minimizes plugging. Simply using hydraulic nozzles with larger orifices can result in performance problems as larger orifices require less pressure drop. The outcome is larger droplets and turndown is limited.

For more information on optimizing sulfur spraying, visit www.spray.com or contact your local Spraying Systems Co. representative. In the U.S. and Canada, call (800) 95-SPRAY. In other regions, call (630) 665-5000. q

Sulfuric Acid Today • Fall/Winter 2015

Put your skills to the test!

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Some people spend their lives avoiding problems, but at Topsoe we seek them out – just so we can solve them! You can check out our recent solutions at Sulphur 2015 in Toronto (Stand 19), but here’s a problem you can help us solve today, and maybe win a set of noisecancelling headphones.

Sulfur-Solvers Challenge: Count the number of hexagon-like shapes. Then scan the code or go to topsoe.com/sulfur2015 to check your answer and enter the draw.

www.topsoe.com

Feature

Case studies in next generation furnace designs for sulfuric acid plants By: Brian Lamb and Matthew De Mars, MECS, Inc.

Introduction

As owners continue to push plants harder, energy conservation goals continue to be more aggressive and regulators continue to require tighter operating windows, today’s sulfuric acid plant manufacturers need new innovative ways to get more out of their existing assets. In this context, “more” can mean many things: debottlenecking, lower energy consumption, lower emission rates, etc. This article examines how next generation furnace designs for sulfuric acid plants are supporting these growing needs.

Targeting the furnace to achieve these results is not a trivial matter. A sulfuric acid plant furnace is a complex and critical unit with a variety of operational and maintenance challenges of its own: the need to ensure complete combustion of various compounds, pressure drop constraints, temperature and excess O2 control and more. These needs vary depending upon the type of furnace (sulfur burning vs. spent acid decomposition) as well as other factors such as production goals, emission targets, etc. To meet the goals of the owner requires a deep understanding of all furnace types and what tools, technologies and operating parameters can be manipulated to achieve the relevant targets.

To cause real improvements to plant operations by manipulating the furnace means facing these challenges head on. Specifically, this article discusses several cases of innovative furnace designs, the real impact of these next generation technologies and the relevance of these results to production, energy and emissions targets. Examples include VectorWall™ technology for improved flow charac-

Fig. 1: MECS® VectorWall™ ceramic furnace internals are hexagonal blocks that stack together without mortar and are fully supported on all six surfaces (above). Vector tiles can be fit into each hexagonal block in order to create custom flow patterns inside the furnace (below).

PAGE 16

teristics, advanced CFD modeling, staged combustion designs and control techniques.

Many of the solutions discussed in this article leverage proprietary MECS® VectorWall™ ceramic furnace internals, which are constructed from a series of hexagonal blocks that stack together without mortar and remain fully supported on all six surfaces, as shown in Fig. 1.

Each individual block can be fitted with a vector tile in order to create custom flow patterns inside the furnace.

Flow fields can be manipulated using this technology in order to create the desired combustion environment and to ultimately help facility owners meet their various objectives.

Fig. 4: Velocity plot for optimized baffle configuration.

In 2015, a chemical spent sulfuric acid facility endeavored to release more capacity while reducing stack NOx emissions. The facility owner partnered with MECS, Inc. (MECS) to conduct the proper analysis and deliver products and engineering services that would facilitate these goals.

Prior to the revamp, stack NOX levels were 120-150 mg/Nm3 at an acid production rate of 900 tonnes/day. In order to reach 100 mg/Nm3 at 1,076 tonnes/day, MECS recommended that the facility owner retrofit the furnace to a staged combustion design and utilize oxygen enrichment.

The challenges of implementing this recommendation were a limited footprint and a limited budget. Thus, a staged combustion design using two separate furnaces (one reduc-

ing and one oxidizing) was not feasible.

To investigate how to achieve these targets using the existing furnace, MECS partnered with John Zink Hamworthy Combustion to perform advanced combustion and CFD modeling. Advanced combustion modeling was critical to the success of this project. Sub-optimized baffle configurations could lead to incomplete combustion, NOX formation and even equipment damage.

Fig. 2 shows O2 content at the furnace exit for two different baffle configurations. Low O2 readings at the furnace exit are an indication of inadequate combustion air which can result in incomplete combustion and even sulfur precipitation in the furnace. In some cases, facility owners will control fuel gas rates off of oxygen readings to ensure proper combustion. In such cases, uniform O2 distribution is critical to ensure that the furnace is operating at the desired control point and that O2 readings are representative of the true bulk flow.

Fig. 3 shows SO2 content at the furnace exit for two different baffle configurations. SO2 content at the furnace exit is important because it influences the chemical reactions in the converter and the overall conversion achieved by the process. Excessive SO2 leaving the furnace could

Fig. 2: O2 at the furnace exit for sub-optimized (above) and optimized (below) baffle configurations.

Fig. 3: SO2 at the furnace exit for sub-optimized (above) and optimized (below) baffle configurations.

Case 1: Staged combustion with O2 enrichment for low NOX

Sulfuric Acid Today • Fall/Winter 2015

Fig. 5: VectorWall™ configuration.

Feature

create temperature control or even emissions problems for the plant. Low SO2 also affects the overall plant heat balance and overall sulfuric acid production.

The analysis indicated that the staged combustion revamp could be accomplished with the existing furnace by utilizing MECS® VectorWall™ ceramic furnace internals. Specifically, it was found that a partially blocked first wall was needed to force the staged air down into the furnace and that vector tiles were needed on the lower portion of the wall to create a mixing vortex (see Fig. 4).

The field results were excellent; the customer achieved the production and emissions goals and the modeling work was validated with real data. The facility owner was satisfied that by implementing staged combustion with oxygen enrichment and by utilizing MECS® VectorWall™ ce-

Table 1 Emissions and Production Results Daily Averages

Production Rate mtpd

Tail Gas NOx mg/Nm3

BEFORE Revamp

900

150

AFTER Revamp

1082

49

ramic furnace internals, they were able to achieve their emissions and capacity objectives.

Case 2: Mechanical stability

In late 2013, a sulfuric acid production facility undertook a major furnace replacement project. Due to timing and footprint constraints, the new 1.1 million pound furnace was to be fully bricked prior to the plant shutdown and then lifted into place during the plant turnaround.

To execute such an ambitious plan, proper planning, analysis and mechanical stability of the furnace were key. To meet these needs, the facility owner used MECS® HexWall™ ceramic furnace internals in place of conventional baffles.

Conventional baffles are made out of brick and mortar and are susceptible to cracking. It is not uncommon for facility owners to rebuild conventional baffle walls on a regular basis. Additionally, the stability of a conventional brick baffle wall can vary

Fig. 8: MECS® HexWall™ installation keyed into the furnace lining (left) and held together without mortar using a tongue and groove design (right).

substantially depending on the skill of the installer. Fig. 7 shows a collapsed brick baffle wall.

By contrast, MECS® HexWall™ ceramic furnace internals are keyed into the brick lining of the furnace and stacked together without mortar. The resulting furnace baffle walls are both sturdy and flexible, much like a well-built bridge.

The advantage to the facility owner is a sturdier structure that can be erected in a fraction of the time it would take to build a conventional baffle wall, along with reduced installation costs and avoided future maintenance and repair work. Fig. 8 illustrates how the HexWall™ is keyed into the furnace lining and stacked together without mortar.

In this case, the facility owner was able to execute an aggressive turnaround plan that not only preserved the mechanical integrity of the new furnace, but even enhanced it. Additionally, the HexWall™ was installed in approximately 1/3 of the time it would have taken to install conventional brick baffle walls.

Next generation designs

Fig. 6: Actual VectorWall™ installation with optimized baffle configuration.

Fig. 7: Collapsed baffle wall with conventional brick and mortar design.

As field data from real cases continues to corroborate furnace CFD modeling, the question becomes: what next? As furnace mixing technology continues to advance, well-designed furnaces become capable of doing more (or the same) with less.

Sulfur burning furnaces can be designed with fewer baffle walls to reduce installation costs as well as pressure drop,

as shown in Fig. 10.

Residence time distributions can be narrowed for steadier and more predictable furnace performance. Fig. 11 compares the residence time distribution associated with a conventional brick baffle design to the residence time distribution associated with a VectorWall™ design. For an ideal plug flow reactor, the residence time distribution would be a single vertical line at a time that corresponded to the design point for the furnace. Broader residence time distributions indicate sub-optimal mixing, hence failure to fully utilize the entire furnace volume to its point of maximum efficiency.

The narrower residence time distribution in the VectorWall™ design indicates that a higher percentage of particles pass through the furnace in an amount of time that is closer to the design point than would have been the case with a conventional design. Thus, next generation designs can integrate VectorWall™ technology in a way that reduces furnace sizes. Table 2 shows the capital savings on a U.S. Gulf Coast basis for a 10 percent reduction in furnace size for a typical sulfur burning furnace.

Fig. 10: Pressure drop for three baffle walls vs. one VectorWall™.

Table 2 Capital Savings for a 10% Reduction in Furnace Size (US Golf Coast Pricing Basis)

Fig. 9: Fully bricked furnace with MECS® HexWall™ being lifted into place.

Sulfuric Acid Today • Fall/Winter 2015

Price Using Conventional Baffle Design ($1000)

Price Using VectorWall™ Design ($1000)

Steel Shell (Materials Only)

115

105

Brick Lining and Baffle/VectorWall™ Installation (Including Materials and Labor)

1150

900

VectorWall™

0

150

Total

1265

1155

PAGE 17

Feature

PEOPLE ON THE MOVE Roberts is a full service provider of engineering, construction, fabrication and plant services.

For more information, contact Ross Miller at (863) 532-5317 or ross.miller@ robertscompany.com.

Ross Miller joins Roberts

Fig. 11: Residence time distribution for three baffle walls vs. one VectorWall™.

Conclusion

The need for next generation furnace technology is great. It is driven by tightening budgets, environmental regulations and tighter operating windows, as well as broadening production aspirations, turnaround scopes, and technology availability.

Proper furnace design is not a trivial matter. However, customers can benefit from MECS process and mechanical expertise, together with the input of industry experts like John Zink Hamworthy Combustion and Blasch

Precision Ceramics, to study creative solutions with tools like combustion modeling, CFD analysis and general sulfuric acid plant design capabilities and know-how. When analyzed by the right team of experts, facility owners can realize improvements that meet and even exceed their goals.

WINTERVILLE, NC— Ross Miller joined Roberts as Manager of Business Development for the Roberts Florida Office in Mulberry, Fla. Miller is responsible for business development and sales for the Florida market. He comes to Roberts with 24 years of experience in industrial sales, primarily in phosphate and power. Miller is a veteran of the United States Marine Corps.

Sauereisen expands administrative department

PITTSBURGH, PA—Sauereisen, Inc., a manufacturer of specialty cements and corrosion-resistant materials, recently announced the hiring of Shannon Schlumberger as receptionist/ administrative assistant.

Schlumberger, of Oakmont, graduated Cum Laude from Plymouth State University in New Hampshire, with a Bachelor’s degree in Art. She was most recently employed by Thermo-Twin Windows, where she utilized her skills as an install administrator, sched-

Acknowledgements:

MECS would like to acknowledge

Blasch Precision Ceramics and John Zink Hamworth Combustion for their contributions to this article.

Ross Miller, Manager of Business Development, Roberts Florida Office

uler and customer service representative.

Established in 1899, Sauereisen Inc. is one of the world’s leading manufacturers of specialty cements and corrosion-resistant coatings. The company has a network of technical sales representatives in major cities throughout the world. With manufacturing and warehouse facilities in the United States, Europe and the Pacific Rim, Sauereisen provides global product distribution.

For more information, visit www.sauereisen.com. q

Shannon Schlumberger, Receptionist/Administrative Assistant, Sauereisen

q

SO Monitoring 24/7 2

with Fast Response Time and Low Maintenance Cut Costs by Installing Opsis ► ► ► ► ► ►

Non-extractive measurements of SO2 and SO3 PPM to % levels Low maintenance Multi-path and multi-gas flexibility Increased productivity EN 15267 accredited by TÜV

Scan the QR code to watch our video about SO2 monitoring in a sulphuric acid plant, or go directly to www.opsis.se.

Read more on www.opsis.se • E-mail: info@opsis.se • Phone: +46 46 72 25 00 PAGE 18

For more information contact OPSIS or find your local distributor on opsis.se

Sulfuric Acid Today • Fall/Winter 2015

Partners, Professionals, Problem-Solvers...Check.

When it comes to exceeding the qualifications to perform your plant’s turnaround or outage, CMW tops the list: Safety: CMW’s MOD rate for 2015 is 0.61. Results exhibit the difference between talk and action. CMW has a company wide behavior-based training system that drives safety at every level of the organization. With over 100 turnarounds under our belt, we are proud of our dedication to keeping our employees safe.

Scheduling: CMW has a dedicated scheduling/planning division with decades of experience in developing project master schedules that have consistently removed hours, if not days, of wasted time and resources. From work scope outlines to complete project tracking through Microsoft Project and/or Primavera, CMW will deliver the master schedule that makes a difference.

Fabrication: CMW’s ASME code shop has the S and U stamps along with the NBIC R stamp for all your fabrication requirements. Our 100,000 square foot facility has produced hundreds of sulfuric pieces of equipment such as converters, heat exchangers, pressure vessels, acid towers, ducts, expansions joints, and much more for whatever your specific requirements may be.

Field Installation: CMW has an impeccable reputation for expert quality workmanship and finishing on time and on budget. Our field crews are some of the best in the business and our close to 50 years of making sure your plant is back on line provides the confidence you need in making your contractor decision.

Maintenance: CMW believes in full service for your sulfuric acid plant. Our maintenance crews ensure that your plant operates at peak efficiency on a daily basis while also providing the best preparation for all outage related work.

Check us out at www.cmw.cc For detailed capabilities, scan the QR Code or go to: http://www.cmw.cc/additionalinfo.aspx

Toll-free in the USA: (877) 704-7411 International: (813) 737-1402

FLORIDA OFFICE 2620 East Keysville Road • Lithia, FL 33547 813-737-1402

ALABAMA OFFICE 2090 Schillinger Road • Ste A • Mobile, AL 36695 251-378-5471

De ep pa arrttm me en ntt D

NEWS BITS

NORAM delivers acid cooler

Measuring sulfuric acid, oleum strength using sonic velocity meters

VASTRA FROLUNDA, Sweden—NORAM Engineering & Constructors Ltd. has delivered a replacement acid cooler to a U.S. customer on a tight time schedule and on budget. The acid cooler supplied was constructed in NORAM SX™ material and was manufactured at NORAM’s fabrication shop, Axton Inc., in Vancouver, Canada.

NORAM SX™ is an austenitic stainless steel material specially developed for use in hot concentrated sulfuric acid. NORAM SX™ products include acid towers, acid pump tanks, acid piping, acid distributors, thermowells, orifice plates, shell plates, thimbles, etc., as well as Sandvik SX welding consumables. These products are available worldwide.

For more information, please visit www.noramintl.com or www.noram-eng.com. q

NORAM SX™ alloy sulfuric acid cooler.

BARLEBEN, Germany— Monitoring the sulfuric acid and oleum strength (percent by weight) inline, directly in the process, enhances safety and efficiency of production plants. The measuring results are available online and in real time. Due to the physical properties of sulfuric acid and oleum, the most suitable measuring method for determining the acid strength is sonic velocity measurement.

The LiquiSonic® analyzer

by SensoTech measures precisely with only one single sensor the sulfuric acid and oleum strength in the relevant concentration ranges.

Applications of the analyzer include, for example, acid production, alkylation, oil refining, syngas drying, fertilizer manufacturing, miner-

The LiquiSonic® analyzer of SensoTech monitors precisely the sulfuric acid and oleum strength and provides the data online and in real time.

al processing or etching and pickling baths. The LiquiSonic® technology is based on sonic velocity measurement, providing clear and stable measuring results with an accuracy of up to 0.03 percent by weight. If the measuring values exceed or fall below critical process thresholds,

a signal will be sent immediately, ensuring timely countermeasures can be initiated. The real-time information significantly increases work environment safety and product quality and reduces costs caused by acid waste and failed production.

Made of Hastelloy

C-2000, the LiquiSonic® sensor is absolutely resistant to corrosion.

The robust construction requires neither gaskets nor moving parts, so the sensor is maintenancefree with long-term stability. The installation is done directly into the existing pipe or vessel.

The measurement results are updated every second, and for process automation the real-time data can be transferred to process control systems via 4-20 mA signal, digital outputs, fieldbus or Ethernet. The LiquiSonic ® controller displays and saves the measuring values. The analyzer is delivered as a plug & play system, so a simple and fast commissioning is guaranteed.

For more information, please visit www.sensotech.com. q

Our Reliable Services Are Fit For A King As one of the most important industrial chemicals, it’s no wonder sulfuric acid has been crowned the “King of Chemicals.”

Roberts provides construction solutions, resources and support for facility owners and managers in the sulfuric acid industry. We pride ourselves on relationships built around dependability, responsiveness, results and trust.

Roberts – providing services fit for the king of chemicals since 1977.

For more information, visit www.robertscompany.com

Fabrication + Construction + Maintenance Services PAGE 20

Sulfuric Acid Today • Fall/Winter 2015

INDUSTRIAL LININGS AND EQUIPMENT FOR SULPHURIC ACID PLANTS ENGINEERING + PRODUCTION + INSTALLATION REFRACTORY LININGS AND CORROSION PROTECTION SYSTEMS FOR: SULPHUR FURNACE SPENT ACID FURNACE FLUID BED ROASTERS ABSORPTION TOWERS PUMP TANKS SULPHUR PITS GAS CLEANING VESSELS CONVERTERS ACID RESISTANT LININGS

STEULER-KCH GMBH Berggarten 1 56427 Siershahn | Germany

Sulphuric Acid Today.indd 1

Phone.:+49 2623 600-0 Fax:+49 2623 600-513 E-Mail:info@steuler-kch.de www.steuler-kch.com 27.08.2015 15:37:49

Deeapta F urrtem e n t

Safety at the forefront of every sulfuric acid project

While keeping your sulfuric acid plant up and running smoothly is a top priority, this must always be done with an eye toward safety. Roberts recognizes the important role safety plays in day-to-day operations and strives to make it a part of the company’s everyday culture.

Plant work is inherently dangerous.

Since the company’s inception in 1977, employees have always been Roberts’ most important asset. But a safe workplace doesn’t just happen; it’s the result of rigorous planning, continuous training, implementation of policy and management’s commitment, in combination with safe work behaviors championed by all employees. Roberts’ safety data, recognitions and consistent superior EMR rating are a reflection of efforts towards achieving the highest level of safety standards.

“Roberts understands that no matter how well we perform, your project will not be considered a success if someone gets hurt on the job,” says company president John Roberts.

“We are committed to getting every employee involved in safety and promoting a culture that strives to prevent accidents and injuries.”

As the single source for complete project solutions in the sulfuric acid industry, Roberts remains poised to provide fabrication, construction and plant maintenance that is cost effective and on-time, while remaining committed to achieving the highest industry standards of quality and safety.

Combined, these efforts accomplish our goal of building long-term customer relationships that keep your operations in motion.

For more information, visit www.robertscompany.com. q

Roberts’ five-year record reflects the company’s commitment to safety.

Roberts’ headquarters and fabrication shop 1 in Winterville, NC.

Roberts prepares newly fabricated pipe spools for transportation and installation.

Roberts fabricated and field-erected this new converter.

Roberts’ fabrication shop 2 in Winterville, NC.

Powell Sulfuric Acid Dilution System The Powell Sulfuric Acid Dilution Systems are engineered to continuously dilute 93% or 98% sulfuric acid to any lower strength. The systems are automatic and include pumps and cooling water systems for the safe, accurate dilution of the concentrated acid. Systems are available for all flow rates and diluted acid strengths.

Features • Automatic Dilution • PLC Based Control System • Adjustable Batch Amounts or Flow Rates • Strong Acid and Water Supply Pumps • Skid Mounted, Fully Assembled

740 E. Monroe Road, St. Louis, MI 48880 Ph: 888.800.2310 www.powellfab.com email: info@powellfab.com PAGE 22

Sulfuric Acid Today • Fall/Winter 2015

Feature

NOx! Here today, here to stay By: Darwin Passman, CSP/HR Safety Director, VIP International

NOX is an unwanted by product created in three areas of a sulfuric acid plant. The first and primary place NOX is created is the furnace. Higher operating temperatures coupled with increased oxygen enrichment and longer residence time form nitrogen oxides. This type of formation is referred to as thermal NOX and represents the majority of nitrogen oxides formed in the gas. Nitrogen oxides may also be present in the fuel or feedstock used in the furnace. This type of NOX is referred to as chemical NOX. A third source of NOX, specific to smelters, results from the operation of wet electrostatic precipitators (WESPs). Electrical arcing in the WESPs causes the formation of nitrogen oxides.

The nitrogen oxides react with sulfuric acid to form the compound nitrosylsulfuric acid (HNOSO 4). NOX, in the gas stream, is readily absorbed by the submicron acid mist particles due to the high surface area to volume ratio. Therefore, most of the nitrosylsulfuric acid is con-

centrated in the acid draining from the mist eliminators. The mist eliminators are saturated with this NOX laden acid and sulfates. This acid is readily soluble in sulfuric acid at low temperatures and accumulates in the acidic sulfates of cold exchangers and the false bottom of the stack.

Exposure to NOX is most prevalent during a turnaround. Once the plant has been purged and cooled down the system is de-energized and prepared for inspections and repairs. Inspection entry points are opened on the dry side as well as the wet side. Due to the natural draft of the plant, ambient air is drawn into the entry points.

The humidity in the ambient air is absorbed by the nitrosylsulfuric initiating a reaction that releases NOX primarily as nitrogen dioxide (NO2). NO2 (unlike sulfur dioxide) does not have adequate warning properties at low but toxic concentrations; monitors with electrochemical NO2 sensors must be used

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Anodic protection solutions for: • Sulfuric Acid Storage Tanks • Sulfuric Acid Coolers • Sulfuric Acid Piping

PAGE 24

1.800.676.4984 acid@corrosionservice.com www.corrosionservice.com

for detection and quantification of NO2.

It’s worthy to note atmospheric testing of any confined space must follow the OSHA procedure for testing in the following order: OSHA Exposure limits: 1. Percent Oxygen 19.5-23.5% 2. Lower Explosive Limit 0.0-10.0 % 3. Toxics: carbon monoxide, sulfur dioxide, hydrogen sulfide or nitrogen dioxide.

Initially there may be a low or no reading of NOX. The nitrosylsulfuric is relatively stable until it begins to absorb moisture. Once exposed to moisture the reaction begins to release NOX and produces heat. The reaction increases, as the acid gets hotter and absorbs more moisture. As a result of this delayed process we often see NOX levels start out low at the beginning of a turnaround and increase as time progresses. Areas of significant exposure are from sulfate buildup in the cold exchangers, stack and other areas of sulfate buildup. The gas outlet section of the Interpass absorption tower and final tower, including the tubesheet and mist eliminators, are primary sources of NOX exposure.

—The OSHA Permissible Exposure Limit (PEL) for nitrogen dioxide is 5 ppm.

—The Cal OSHA (PEL) is 1 ppm.

—The Immediately Dangerous to Life and Health exposure (IDLH) is 20 ppm.

It is important to note that nitrogen dioxide interferes with the sulfur dioxide electrochemical sensor on the atmospheric monitor. For example, if the nitrogen dioxide level is 25 ppm and the sulfur dioxide level is 0 ppm the electrochemical sensor for sulfur dioxide will read -25 ppm or negative 25 ppm. Sulfur dioxide does not interfere with the NO2 electrochemical sensor.

When attempting to mitigate NOX exposure consider the following: —Vessels being entered for inspection or work —The actual work being performed —Isolating NOX laden equipment —Hydrogen buildup

Since NOX emissions increase when nitrosylsulfuric acid is exposed to moisture, a plan to minimize that exposure during turnaround should be created to

VIP International uses two NOx scrubbers and one SO2 scrubber to mitigate toxic atmospheric exposure.

decrease emissions. Removal of material (sulfates or mist eliminators) at the beginning of the turnaround will decrease the NOX exposure. Also, isolation of specific equipment that is NOX laden will keep the rest of the equipment free of contamination but may also increase the risk of hydrogen build up in a dead zone area.

Once the material is removed, the NOX can be treated with a process that breaks it down to free nitrogen (N2) and weak sulfuric acid (H 2SO 4).

When working in a potential NOX environment, proactive monitoring is the first step to minimizing exposure. If NOX is present ventilation is a possible remedy for removal while working in the vessel.

If an immediate source of NOX is in the vessel, ventilation may increase the exposure risk by injecting humid air. If NOX is present and work must be performed IDLH protocol must be followed. This requires training, experience and the equipment to safely enter and work in an IDLH atmosphere. The goal in any IDLH entry is to reduce the atmospheric conditions to non-IDLH as quickly and safely as possible.

If NOX is here to stay, mitigate exposure when possible, educate the work force and provide training in the safe handling and atmospheric exposure during a turnaround.

For more information on mitigating toxic atmospheric exposure during an outage, contact Darwin Passman of VIP International at (225) 753-8575 or darwin@vipinc.com. q Sulfuric Acid Today • Fall/Winter 2015

Feature

INDUSTRY PROFILE

Clark Solutions: reflecting on over 20 years in the industry

Clark Solutions was founded in 1991 in São Paulo, Brazil after company founder, Nelson Clark, began working as an engineer for Monsanto Enviro-Chem Brazil.

Today, the company is still headquartered in São Paulo, with two manufacturing shops in Barueri and research facilities in Barueri and Guaianazes.

Clark Solutions specializes in manufacturing thermal and mechanical separation equipment, such as mechanical separators, gas-liquid separators, tower packing and internals and both liquid and gas distributors. For the sulfuric acid industry in particular, the company focus is mist elimination in the drying and absorbing towers and mass transfer in the cooling, drying and absorbing towers. Clark Solutions is also one of the top suppliers of compact three-phase separators for the oil and gas industries, particularly for offshore platforms, where compact size and sturdy designs are critical features and selection criteria.

The company’s history with sulfuric acid began in 1988 when Nelson Clark was hired by Monsanto in Brazil as a co-op student while studying chemical engineering at Escola Politécnica da Universidade de São Paulo. Shortly thereafter, Clark was hired as an engineer at Monsanto’s EnviroChem Division. Early in 1991, Monsanto offered Clark’s new company the opportunity to represent Monsanto’s products in Brazil and a few more countries. Later that year, Monsanto also introduced Clark Solutions to Otto H. York Company, who Clark also started representing.

In 1995, the company built its first mist eliminator manufacturing facility in Barueri

São Paulo. Among other products produced at the facility was the complete wire mesh product line licensed from Otto H. York.

Since that time, the company has sold many thousands of mist elimination devices that it has manufactured using its own or licensed technology. Later, Clark added mass transfer products to its lines, particularly tower packing and liquid distributors.

Clark Solutions has always been a family company whose sole focus is providing the best products and services to the market. Customers and employees always come before profits, as it is the people who will grant a long life in business.

In 2003, the company started a joint venture with Koch Otto-York to manufacture mist elimination and gas-liquid separation devices. In 2015, the two companies found their objectives were diverging and amicably dissolved the venture.

Clark Solutions is one of the largest mist eliminator manufacturers in the southern hemisphere with a team of qualified engineers and a state-of-theart research laboratory. The research lab includes two 6-inch diameter and one 16-inch diameter pilot tower for mist elimination and tower packing characterization, and an eight-meter diameter setup to develop and test liquid distributors. The company also works with the São Paulo University Chemical Engineering Department on a variety of programs including cross training of students, continuous education programs for Clark’s engineering team and support of students on mechanical separations research. These activities allow Clark Solutions to produce and develop state-of-the-art products including

Fig. 1: Dry pressure drop plot for 18 candles.

a line of candles, which the company has been refining for decades.

Today, every aspect of candle manufacture is fully computer controlled. Every candle has a serial number, is pressure drop tested and its metallic materials go through PMI testing, along with several other performance tests developed at Clark. Each single candle is dry pressure drop tested–to up to 6,000 m3/hr air flow–during manufacturing and later when finished. Pressure drop data, including pressure drop for each candle individually as well as the complete set of candles supplied to a job is used to verify integrity and correlate performance.

Fig. 1 shows the results of multiple candle testing for a specific job.

Also, upon request, the candles can be thermally scanned to further verify the bed

COMPANY NEWS

Corrosion Technology Systems, Inc. receives agent of the year award

PITTSBURGH, PA—Corrosion Technology Systems (CTS) has represented Sauereisen corrosion-resistant materials in New Jersey, Delaware, Maryland, Eastern Pennsylvania, New York and Connecticut since 1992, and recently won Sauereisen’s Agent of the Year award. Their activities in market development and technical product service continue to provide growth opportunities for Sauereisen.

This award is presented annually to the sales agency that best meets sales objectives through specification development and expansion of new business opportunities in a defined marketplace.

PAGE 26

Corrosion Technology Systems recently received Sauereisen’s 2014 Agent of the Year Award. Pictured are, from left, Sauereisen President J. Eric Sauereisen, Kevin Grega and Jon Lattin of CTS and Sauereisen Eastern Regional Manager Tony Oswald, Jr.

Corrosion Technology Systems’ efforts in the past year have exceeded expec-

tations. They have continued to expand sales to the wastewater industry with the promotion of Sauereisen’s SewerGard Systems.

Sauereisen is one of the world’s leading manufacturers of specialty cements and corrosion-resistant materials.

The company has a network of technical sales representatives in major cities throughout the world. With manufacturing and warehouse facilities in the United States, Europe and the Pacific Rim, Sauereisen provides global product distribution.

For more information, please visit www.sauereisen.com. q

Nelson Clark, president and CEO of Clark Solutions, recently chose New Orleans to celebrate his 50th wedding anniversary where he enjoyed the city’s wonderful food, music and culture.

homogeneity. The lab in Barueri counts with cascade impactors that can measure and verify candle performance. This service is also available for on-site evaluation of candle performance.

Computers enable winding in parallel or angled patterns, to vary the density and the tension of the fiber at any moment and stop the winding when reaching precise targets. It is a very sophisticated system that enables candle design for very narrow pressure drop windows or precisely defined efficiencies. Clark Solutions’ products have a very long record of success and performance. Candle installations have been in continuous service in metallurgical gas plants for more than 15 years. Recently, even in a situation of a superheater failure, the company’s interpass tower supplied candles were capable of collecting huge amounts of mist generated without compromising the cold side of the cold IP heat exchangers.

Through the years, the company has focused almost exclusively in Brazil. Recently, however, Clark has decided to expand its scope and offer products, starting with mist eliminator solutions, to other countries and markets.

To support its growth, the company is now building a new manufacturing shop in Embu das Artes, a small city located 20 kilometers from São Paulo. This plant will also integrate Clark’s multiple research facilities. Other recent initiatives include targeting sulfuric acid applications in countries outside of Brazil focusing on Latin America, Africa and the Middle East. The company also plans to open branches in South America, likely Chile or Peru, as well as the United States, by the end of 2016.

For more information, visit www.clarksolutions.com.br. q Sulfuric Acid Today • Fall/Winter 2015

Beltran Sulfuric Acid Today Full Page Rev2 9/16/14 6:46 AM Page 1

Beltran Wet Electrostatic Precipitators:

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Beltran’s advanced WESP technology captures fine particulates, acid mists and condensed organics with maximum efficiency and lower cost.

Save on equipment, operating and energy costs with Beltran gas-cleaning WESP systems, proven worldwide for collection efficiency and reliable performance.

Our custom-engineered WESP designs remove even hard-to-capture submicron particulates, sulfuric acid mists and condensed organics.

Beltran WESPs are currently producing excellent results for sulfuric acid plants and other applications worldwide, including mining and metallurgy, spent acid recovery, power generation, boilers, incinerators and more.

• Unique electrode design and multistage systems capture flue-gas components with up to 99.9% efficiency.

• Low pressure drop supports higher gas velocities and volumes with smaller equipment and lower costs.

• Aqueous flushing system prevents particle re-entrainment, residue build-up, resistivity.

• Cool, saturated WESP is more effective on condensable, oily, sticky contaminants.

• Contaminant-free feedstock gas assures quality end-product for acid plants.

SCAN HERE with your Smart Phone for more info from Beltran

Beltran Wet Electrostatic Precipitators: The ideal gas cleaning solution for sulfuric acid plants.

BELTRAN TECHNOLOGIES, INC.

Beltran Technologies, Inc. 1133 East 35th Street, Brooklyn, NY 11210 718.338.3311 • Fax: 718.253.9028 info@beltrantechnologies.com www.beltrantechnologies.com

ENGINEERING THE FUTURE IN EMISSION CONTROL TECHNOLOGY! 50 YEARS OF EXPERIENCE. MORE THAN 1000 INSTALLATIONS WORLDWIDE.

Department

PRODUCT NEWS

CORD™ heat exchanger supports trouble-free operations at Boliden Rönnskär

Boliden, a Swedish mining and smelting company focused on the production of copper, zinc, lead, gold and silver, runs one of the world’s most efficient copper smelters at Rönnskär, a site 800 kilometers north of Stockholm.

The smelter produces more than 200,000 tonnes of copper per year and 2,000 tonnes of sulfuric acid per day as a byproduct from ore concentrates and electronic scrap from nearby mines.

As has been the case at numerous other sulfuric acid plants, the cold reheat gas-to-gas heat exchanger at Rönnskär has required more and more service since its installation in 2000. In 2009 it needed a major overhaul to secure performance for the upcoming years. Initially, the heat exchanger had been oversized to cover a potential expansion of the sulfuric acid plant. This reserve was eaten up by the damaged tubes that needed to be blinded

to keep the heat exchangers functioning.

In 2012 it became evident that a replacement of the unit was necessary and could not be postponed. Outotec’s new CORD heat exchanger solution was chosen to replace the unit in order to eliminate this source of continuous and intensive maintenance.

Reliable new Outotec CORD heat exchanger is non-corrosive The patented CORD heat exchanger design is based on a two-section concept.

This concept was originally introduced

by Outotec in the late 1950s and has undergone numerous developments since.

The CORD heat exchanger features a stainless steel horizontal heat exchanger section.

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From design to installation in six months The order was placed in November 2012. As the installation had to be secured for the planned shutdown in May 2013, a precise project schedule was established to accomplish the short delivery time of just six months. Outotec’s delivery scope also included the installation design work, while an Outotec representative acted as design manager for all CORD-related work in close cooperation with the project

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The new CORD design consists of a vertical and a horizontal heat exchanger section, both of which operate under noncorrosive conditions. The small horizontal cold end is manufactured in stainless steel, whereas the main vertical section can be built out of standard-grade steel.

The horizontal section is designed to provide a gas temperature increase of approximately 20 degrees C. This approach ensures that the horizontal section is operated only at temperatures at which the stainless steel is corrosion resistant and the acid condensates do not cause any accumulation of deposits or tube leakages due to corrosion. At the same time, the vertical section is operated totally above the acid dew point, preventing corrosion in this section.

Other features of the CORD design include: —Vertical tube sheets at the cold end to prevent the tube/tube sheet joint area from being exposed continuously to sulfuric acid condensates and enabling easy drainage of the horizontal section.

—Gas flow at the cold-end entry has been optimized thanks to a new inlet cross section design and concentric tube bundle positioning, supporting homogeneous gas flow through the bundle for efficient heat exchange and separation of acid condensates and carryover from the absorption tower.

The vertical heat exchanger section is made from standard-grade steel.

CORD heat exchanger in place at Boliden Rönnskär.

manager from Boliden. In addition, further services in other areas of the acid and smelter plant were performed by Outotec, including the delivery and installation of an SX acid cooler.

As recommended by Outotec, Boliden installed a droplet separator upstream to minimize the acid condensate carryover from the duct walls into the heat exchanger and prevent droplets entering the heat exchanger’s inlet from the gas flow.

The total weight of the new CORD heat exchanger is 258,000 kilos, less than 9 percent of which is stainless steel.

This minimizes the investment costs for this reliable and long-lasting solution and explains the CORD acronym: Cost Optimized Reliable Design.

The equipment was fabricated at a European supplier’s workshop and was transported within seven days to the site. It then took just 10 days for the replacement of the new heat exchanger and tie-in to the plant, which was well within the available stop time. To save erection time and minimize any risk of interfering with the shutdown schedule, the new heat exchanger was erected on a new foundation, enabling the existing heat exchanger to be demolished independently from the shutdown schedule.

“The CORD heat exchanger works perfectly so far,” says Anders Markström, process engineer at the sulfuric acid plant. “The first scheduled inspection after one year of operation revealed no corrosion at all, and even manufacturing markings on the internals were still visible.

Outotec supplied a good solution for this challenging application.”

For more information, please visit www.outotec.com. q Sulfuric Acid Today • Fall/Winter 2015

Thermal and Mechanical Separation Solutions

Feature

Direct optical gas monitoring systems: just looking, not touching

By: Carl Kamme, Sales Director Americas, Opsis AB

How do you pick a gas monitoring system that behaves in a courteous manner?

One that just looks at the gas and does not touch it? Direct optical systems that read gases such as SO2, SO3, CO, CO2, NOx, HF and many other parameters, do just that.

A harsh environment set by corrosive gases, high dust levels and high temperatures limits the number of available options when selecting a suitable system for the purpose of recording concentrations of gaseous components. Sample extractionbased systems that employ a probe and then a conditioning unit that transports sample gas to the monitor will need more maintenance and will not be as reliable as a system that is just looking at the gas. A remote sensing system based on optical open path technology, such as ultraviolet (UV) DOAS and infrared (IR) FTIR, will just look, and not touch the gas.

The principle of operation is simple, as shown in Fig. 1. An intense and parallel light beam from a continuous Xenon arc lamp is generated in the emitter, which is attached on one side of the channel. A channel in this case may be a stack, duct or other process channel where gases are flowing. As the light goes through the gas mix, the various molecules will absorb certain portions of the spectrum. The light is collected in the receiver which is attached on the opposite side of the channel. From there a fiber optic cable guides the signal to the analyzer.

There a fast scanning detection technology reads out the spectral information at a rate of several thousand data points per second.

This generates a high resolution fingerprint which is processed in the computer that calculates the results.

The emitter and receiver units connect on standard ports and are looking through 1½” openings that are separated by quartz glass windows from the gas stream. The windows are kept clear by a small flow of instrument air.

These systems will also provide a path integrated value across the volume. This improves the accuracy provided in terms of how representative the measurement is of the actual gas flowing in the channel.

There are several advantages with this type of set up. The analyzer spectrometer can be kept in a protected environment apart from the outside dust and heat. This is the key to a successful installation that can be relied on for a long period of time.

Having a fiber optic cable as the connection between the measure location and the analyzer allows multiplexing between multiple optical monitoring paths.

PAGE 30

system to monitor emissions from the main stack that contains residual gases from the converters and the copper smelter.

The Cruise Ship Fig. 2: A continuous sequence of SO2 data [0-2.5 percent vol.] recorded during one week at one of the converter outlets.

Fig. 1: Layout of an optical UV-DOAS or FTIR system.

In some cases, one system can monitor up to eight channels located at different spots throughout the plant, although that depends on the set of gaseous parameters that are monitored.

In any case, when the rapid scanning detector has digitized the light signal, all the data is kept in digital form. This allows the system to operate with essentially no drift over extended periods of time. TUV in Germany has certified the system in accordance with EN15267 for yearly calibrations. This makes it reliable and will minimize the amount of maintenance and related cost needed to operate it.

The applications

A number of industries are using these systems, including sulfuric acid production plants, cement plants, power (coal and gas) plants, waste to energy plants and large cruise ships which have systems that measure stack emissions.

The systems are also employed for measurements in the ambient air, as monitors of air quality and industrial plant perimeter fence line monitors. In this case the long open path technology provides great area coverage using optical path lengths up to 1,000 yards.

In the sulfuric acid plant, the UVDOAS is used to monitor SO2 at many locations throughout the plant. One analyzer can make measurements of high range (0-20 percent vol.), midrange (0-1 percent vol.) as well as low concentrations (0-20 PPM). In this case one system can multiplex several optical paths at different locations. The stack measurement may include other components such as NOx, CO and CO2.

Gas temperature is essentially of no issue, since the system is only looking at the gas, and not trying to extract anything.

Some positive pressure can also be handled (1bar (G)).

The IR-FTIR can measure one of the trickiest components there is, SO3. Using the same non-extractive approach with an

optical path shooting through the duct, this system can provide continuous readings of SO3 concentrations down to 0-1 percent vol. But, since the infrared range is more demanding when transmitted through a fiber optic, the analyzer has to be built in a climate controlled enclosure very close to the monitoring location, and it will not allow any multiplexing.

Mount Isa Mines, Queensland, Australia

There are many interesting and challenging monitoring applications out there. Mount Isa Mines in Australia is a producer of several types of metals and also sulfuric acid. In the production of copper they process the ore in converters to remove sulfur, where it is heated and oxygenated. The converted off-gas is totally raw and unfiltered. The temperature of the gas is high, the concentration of dust is significant and the sulfur dioxide is at percent levels. A continuous real-time reading of the SO2 in the off-gas provides the operator with important information about the process.

To implement a monitoring system at this location is a challenge. The gas conditions are harsh, and the conditions change quickly. It is critical that there is no delay in the feedback to the operator. Real time data provides invaluable information regarding the status of the process (Fig. 2).

Mount Isa has installed a UV-DOAS system to do the job. They have one system that monitors the SO2 in the off-gas from four different converters. This system has been doing a good job since its installation in 1989. Since then, Mount Isa has added more systems. They use another UV-DOAS

Fig. 3: Royal Carribean’s Liberty of the Seas

Royal Caribbean’s Liberty of the Seas is a large cruise ship (Fig.3). It measures 1,050 feet from bow to stern, and has a gross weight of 160,000 tons. It provides up to 4,000 vacationers with an impressive variety of entertainment on board. They also have a UV-DOAS system.

The international maritime organization (IMO) has designated the east coast of the United States as a sulfur emission control area (SECA). Ships can either use expensive, low sulfur fuel, or clean their emission gases and remove most of the sulfur. Liberty of the Seas, based in Port Everglades in Miami, is complying with the standards. To demonstrate compliance, they use a UV-DOAS system to monitor SO2 and CO2 emissions (Fig. 4).

They need the most reliable monitoring solution available on board since they depend on it to report to the authorities that it is in compliance with the sulfur emission limit. The system carries approval

by Germanischer Lloyd (GL-DNV). Many ships, cruisers and freighters, have opted for the optical UV-DOAS system.

Fig. 4: The UV-DOAS light source on one of Liberty of the Seas’ emission stacks.

In summary

As with any piece of equipment, you do not want to be called upon in an untimely fashion to fix things that have gone wrong.

It causes process downtime and costs money. Further, a low, known, long-term cost of ownership builds confidence in the equipment. Optical UV DOAS and FTIR systems have those qualities. Just looking, not touching.

For more information, please contact Carl J. Kamme, Sales Director Americas, at +46 46 72 25 85, email carl.kamme@ opsis.se or visit www.opsis.se. q Sulfuric Acid Today • Fall/Winter 2015

Feature

Hydrogen incidents in sulfuric acid plants — why now and what can we do?

By: Leonard J. Friedman & Dr. Samantha J. Friedman, Acid Engineering & Consulting, Inc.

Introduction

Contact sulfuric acid plants in their current form with vanadium catalyst have been operating since the 1920’s with few if any reported hydrogen incidents. In the last 15 years there have been over 30 major hydrogen incidents around the world, where hydrogen built up in the sulfuric acid plant stagnant areas has detonated, causing major damage to plant equipment and requiring extensive downtime for repairs. To date, fortunately, no major personnel injuries or environmental damage has resulted.

The question is: Why now, and not in the 100 years before? What has changed? What are we doing differently in the design and/or operation and maintenance of sulfuric acid plants today?

And of course, the most important question is: What can we do to reduce the potential for or prevent a hydrogen incident in sulfuric acid plants?

An industry group was formed a few years ago, including representatives from consultants, design engineering contractors and operating companies, to study and analyze the hydrogen incidents around the world to determine the cause and suggest ways to mitigate the potential for hydrogen incidents. The main function of the hydrogen study group is to get the word out about hydrogen and suggest ways to reduce the potential for hydrogen incidents.

This article looks at the changes to the design and/or operation and maintenance of sulfuric acid plants that has led to the significant increase in hydrogen incidents. It also provides recommendations to both designers and operators of ways to reduce the potential for hydrogen incidents

Where does hydrogen come from

The reaction of metals with sulfuric acid produces metal sulfate and hydrogen by the following reaction: M (metal) + H2SO4 (sulfuric acid) = MSO4 (metal sulfate) + H2 (hydrogen). The metals normally found in a sulfuric acid plant are carbon steel, various types of stainless steel and/or cast and ductile iron. The amount of hydrogen produced and the rate of hydrogen production is a function of the metal and its corrosion rate in sulfuric acid (the concentration and temperature of the sulfuric acid, the acid velocity, etc.), and the surface area of metal exposed to the sulfuric acid. The metals: carbon steel, stainless steel and cast iron, have relatively low corrosion rates when exposed to high concentration sulfuric acid in the range of 90 percent to 99.9 percent at normal temperatures and velocities. The corrosion rates increase significantly as the sulfuric acid concentration is reduced, and the temperature and/or velocity are increased. That is why the gas in the plant is dry, and gas cooling is by dry air quench or indirect exchangers; economizers, boilers, superheaters, gas-gas or air cooled exchangers, etc. A leak in any of the gas cooling devices results in moisture (water) entering the gas stream causing dilute sulfuric acid to condense in the cooler places in the plant – normally the economizer or cold gas heat exchanger. The resulting low concentration sulfuric acid condensate increases the corrosion rate of the metal in the exchanger causing hydrogen generation.

Another source of hydrogen is the shell and tube or plate type sulfuric acid coolers. The coolers normally operate with sulfuric acid at 93 percent to 99.9 percent concentration with cooling water providing the cooling medium. If there is a leak in the acid cooler tube or plate and the acid pressure is above the water pressure, acid will Sulfuric Acid Today • Fall/Winter 2015

Acid cooler damage from hydrogen explosion.

leak into the cooling water where it will be detected by the pH/conductivity instruments in the cooling water exiting the cooler, and action will be taken to shut down the plant, drain the water then acid from the cooler and repair the leaking tube. On the other hand, if the water pressure is above the acid pressure during normal operation or when the plant is shut down, the water flowing into the acid will dilute the acid causing rapid corrosion of the metal and hydrogen generation.

Moisture or steam/water leaking into the gas stream and condensing as dilute sulfuric acid or water leaking into the sulfuric acid in the acid cooler diluting the acid, results in generation of significant quantities of hydrogen.

That hydrogen builds up in stagnant areas of the plant and detonates—normally when the plant is shut down to correct the leak problem. The energy required to ignite the hydrogen is very low, so as soon as the hydrogen builds into the explosive range (about 3 percent to 96 percent) the hydrogen will explode. Prior to the 1990’s there were no reported hydrogen incidents (explosions). However, in the last fifteen years or so there have been over 30 hydrogen explosions in double absorption sulfuric acid plants, most caused by leaks in shell and tube or plate type sulfuric acid coolers, with steam system (economizer, boiler and superheater) leaks a distant second, and all when the plant was being or just shut down to repair the leaking device, or when the device is being cleaned.

Why Now? Sulfuric acid plant design prior to the 1920’s Before the mid-1920’s, essentially all sulfuric acid was produced by the nitration or Chamber process (first introduced in 1746). In the Chamber process nitrogen oxide compounds are used to enhance the gas phase oxidation reaction of sulfur dioxide with oxygen and water vapor. The reactions are complex with the formation of the intermediate nitrosylsulfuric acid (HOSO2ONO or HSO3NO2 or SO5NH), followed by the decomposition of nitrosylsulfuric acid by water in dilute acid (acid less than 80 percent H2SO4) to form sulfuric acid and nitrogen oxide (NO). The nitrogen oxide is regenerated by oxygen or air in the burner gas to nitrogen dioxide (NO2), and the combination of nitrogen compounds (NO & NO2 or N2O3) are recycled to the sulfur dioxide oxidation step. Large lead chambers, some as large as 500,000 ft3 for each 20 STPD acid production, were used for the oxidation step, providing reaction time and for the removal of the heat of reaction (hence the process name “Chamber”). Gay-Lussac and Glover towers (named after the people who developed them) were used to react the nitrosylsulfuric acid produced in the Chambers with water in dilute (<80 percent) acid and to regenerate the nitrogen compounds. Product acid from the Glover tower is 60 Baume (77.67 percent) sulfuric acid. The acid could be concentrated by heating to 66 Baume (93.19 percent). Note: Today

nitrosylsulfuric acid is formed in a contact acid plant by the reaction of sulfur dioxide with nitrogen oxides formed in the furnace and collected with the concentrated sulfuric acid mist in the absorption tower high efficiency mist eliminator. Brown nitrogen oxide gas is released when the high efficiency mist eliminator is opened and water Tower’s side outlet (right) creates stagnant area for hydrogen build-up. or moisture in the air dilutes the nitrosylsulfuric acid, decomposing it to sulfuric acid and nitrogen oxides.

Chamber process materials of construction were lead and acid brick with little if any metals exposed to sulfuric acid, so little chance for hydrogen. In addition, the continuous movement of gas in the plant from the draft up the GayLussac tower to the stack provided little if any stagnant areas for hydrogen or other compounds to build up. The stack gas leaving the Gay-Lussac tower normally contained about 1,000 PPM SO2 and about 12-18 percent of the nitrogen entering the plant as NO, NO2, and N2O4. There were no metals to corrode, so hydrogen was not a problem (little if any generated), or even considered in the plant design or operation.

No hydrogen incidents were recorded in over 200 years of Chamber process operation.

The contact process 1900 to 1970

The early contact plants (before 1900 to middle 1920’s), producing about twenty tons per day in a single train, bear little resemblance to today’s plant. Early plants used platinum catalyst and required extensive gas cleaning systems ahead of the converter to minimize poisoning of the platinum catalyst (from halogens, arsenic, etc.). With the development of vanadium catalyst in the early 1900’s (1899 through 1928) the contact process was on its way. A breakthrough in 1927 by Chemico with the development of the pressurized sulfur furnace with spray sulfur guns, combined with the use of vanadium catalyst, produced a flow sheet very similar to today’s design. Contact plants from the late 1920’s to the early 1970’s were single absorption and gradually increased in capacity from a few hundred tons per day to about 1,500-2,000 tons per day.

Why not before 1970’s

Although there were some differences in plant design and equipment, the basic equipment arrangement, design, and materials were similar for all plants through the 1930’s to early 1970’s, until the clean air act of 1971 forced changes. The early plants were all single absorption with acid brick lined acid towers, and metals in the plant cast iron or cast ductile iron. Acid coolers were stacks of cast iron “AX” sections with the water flowing outside (open PAGE 31

Feature

atmosphere side) of the cast iron. Acid piping was cast iron or cast ductile iron. One sulfuric acid plant designer/operator (Allied-General Chemical) owned a foundry, beat to a different drummer, and from the 1950’s on used cast iron towers with acid reservoir in the tower base, stainless steel acid coolers (non-anodically protected) and stainless steel piping, with no hydrogen incidents.

Hydrogen explosions in a plant requires the production of hydrogen and an area for the hydrogen to build up. The following is required for a hydrogen explosion: 1. Hydrogen generation—sulfuric acid corrosion of exposed metal.

2. Stagnant area(s) in the plant for the hydrogen to build up.

3. Corrosive sulfuric acid—water or steam into the gas or acid system to dilute the sulfuric acid to increase the corrosion rate of the metal, increasing hydrogen production.

4. Increased surface of exposed metal that increases the amount of hydrogen produced.

The plant design prior to the early 1970’s did not have the conditions (used corrosion resistant materials) for the generation of significant amounts of hydrogen, or stagnant areas of the plant for any hydrogen generated to build up.

No hydrogen incidents (explosions) were reported during the period (1930’s to early 1970’s) in single absorption sulfuric acid plants. In fact, no hydrogen incidents in single absorption plants to date have been reported. Note: There may have been hydrogen incidents in the early period and in recent years that were kept secret (confidential) by plant operators at the request of their lawyers and insurance companies. However, it is hard to believe that a hydrogen incident that damages the plant and equipment, shutting the plant down for 3 to 6 months, with costs to repair the plant, and the cost of lost production could be kept secret and would not be noticed anywhere in the world.

The single absorption sulfur burning plant design included a main blower either before or after a drying tower, an acid brick-lined drying tower with ceramic packing, cast

Converter damage

Economizer ruptured tube

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iron acid distributor and entrainment separator (metal or Teflon mesh pad, quartz pebbles or ceramic saddle packing) above the main tower packing with a top gas outlet.

The tower with a top gas outlet did not have a stagnant area and the system had little metal surface for the generation of hydrogen. The gas then flowed to the sulfur furnace and furnace boiler. Leaks in a boiler tube would add significant water into the gas stream, but at high temperatures, low sulfur trioxide (SO3) levels, and high oxygen concentration, any hydrogen produced in the boiler was rapidly oxidized to water in the furnace and converter. Major water leaks (rupture of a boiler tube) would produce minor amounts of hydrogen when the plant was shut-down (limited SO3 and sulfuric acid produced to corrode the metal), that would be drafted to the converter and oxidized to water. Hydrogen in the gas to the converter during plant operation would be oxidized by the oxygen in the gas, the high temperature and the vanadium oxidizing catalyst to water. Gas cooling around the converter included: converter boiler, superheater (internal or external), and air heaters (internal or external). Again, any water leak into the gas stream during plant operation would produce some hydrogen that would oxidize in the converter, and during plant shut-down, the draft through the plant would pass the hydrogen over the catalyst to be oxidized to water. The key to minimizing hydrogen effects on plant shutdown is the draft through the plant to the stack and the lack of a stagnant area in the acid towers.

The gas leaving the converter system would flow through an economizer to cool the gas before entering the absorption tower. The economizer, being the coolest surface in the gas stream, would condense any sulfuric acid from a water leak in the steam system into the gas. Initial condensation in the economizer would be Oleum and not be corrosive to carbon steel. Additional water would reduce the sulfuric acid concentration and become more and more corrosive to the steel. The economizer was constructed of a carbon steel casing with carbon steel tubes covered with cast iron gill rings, providing the surface for heat transfer and low corrosion cast iron to minimize corrosion if there were a water leak in the plant systems. Little hydrogen was generated in the cast iron gill ring economizer—low corrosion rate for cast iron over a wide range of sulfuric acid concentrations. Any hydrogen generated due to a water leak in the plant would flow with the gas from the economizer to the absorption tower. The absorption tower was an acid brick lined vessel with ceramic packing, cast iron acid distributor and entrainment separator similar to the dry tower.

The gas outlet from the absorption tower flowed from the top of the tower to the stack. The stack was either mounted on top of the tower or to the side. The warm gas flowing up the tall stack to the cooler atmospheric air created a buoyant force, “draft” through the entire plant. Air-gas flowed from the inlet to the plant at the dry tower through the entire gas system and absorption tower up the stack to the atmosphere. When the plant was down and the equipment was warm or hot, the flow of gas (draft) would purge the plant of any hydrogen up the stack to the atmosphere.

The acid system included the acid brick lined drying and absorption towers, acid brick lined acid pump tanks, and cast iron (or cast ductile iron) acid piping, all with very low corrosion rates. Acid coolers were cast iron AX Sections consisting of extended surface stacks with the acid flowing inside the “S” shaped sections and water running down the outside. Any acid leak would flow to the water and to the water collection pit. The arrangement of the AX sections prevented water from entering the acid side and producing hydrogen.

Spent acid regeneration and metallurgical plant designs were similar to the sulfur-burning plant design but had the sulfur furnace and steam system equipment replaced by gas-gas heat exchangers that used the heat generated in cooling the converter SO2 to SO3 oxidation reaction gas to heat the cool gas from the drying tower and blower to converter catalyst inlet temperatures. With that exception, equipment and materials were the same as the sulfur burning plant, with even less chance for acid corrosion and hydrogen generation since most if not all of the steaming equipment is eliminated.

Reason for no hydrogen incidents before early 1970’s

The reason there were no reported hydrogen incidents before the early 1970’s was due to a number of factors: minimum surface for acid corrosion; corrosion resistant materials; no stagnant areas for hydrogen to build-up; and a draft through the plant on plant shut-down.

1. The design of the drying and absorption towers had the exit gas flowing from a top center outlet, with no stagnant area for hydrogen build-up.

2. The single absorption plant design with warm-hot gas flowing from the top of the absorption tower to the stack created a draft through the plant on plant shutdown that purged the plant of any hydrogen produced.

3. The plant equipment provided little surface for hydrogen generation.

a. The acid cooler has acid inside the cast iron AX section stacks and water running on the outside, so any leak would be from acid to water and not into the gas stream or acid. No acid side corrosion or hydrogen generation to the plant system. b. Towers, pump tanks and other equipment were acid brick lined. No corrosion or hydrogen generation. c. Economizer steel tubes were covered with cast iron gill rings (extended surface) with no steel exposed (except casing and vessel bottom). Minimal corrosion surface and hydrogen generation.

d. Acid piping and tower acid distributors were cast iron or cast ductile iron. Minimal corrosion and hydrogen generation.

Changes 1970’s to 1990’s – Clean Air Act and double absorption

In December 1971 the U.S. EPA enacted the clean air act with regulations for sulfuric acid plants. The regulations limited emissions for new sulfuric acid plants to 4 lbs. SO2/ton of acid produced and sulfuric acid mist to 0.15 lbs. H2SO4/ton. Existing sulfuric acid plants were regulated by the individual states (final approval by EPA) to meet a normal emission limit of 10 lbs. SO2/ton before 1975. In all cases (except for a few grandfathered plants) the single absorption process alone was no longer adequate. Essentially all new sulfuric acid plants were double absorption, a process originally developed in the early 1900’s to protect platinum catalyst from various poisons, and later rediscovered and patented by Bayer in the late 1960’s. The Bayer double absorption process was licensed to and used by all of the designers around the world (Monsanto, Parsons, Chemico, Lurgi, Hugo Peterson, ChemiBau, etc., and their licensees).

Original single absorption plants were either converted to double absorption or added a sodium or ammonia based scrubbing system to meet the new regulations.

Sulfuric Acid Today • Fall/Winter 2015

Many existing single absorption sulfuric acid plants met the new SO2 emission regulations with the addition of ammonia or sodium based SO2 scrubbing systems. The scrubbing systems were constructed of fiber reinforced plastic (FRP) towers and FRP or stainless steel (corrosion resistant to sodium and ammonia scrubbing solutions) tower internals (packing, trays, supports. etc.), and piping.

Scrubber stacks were mounted on top of the scrubbing tower to elevations of 100 feet to 200 feet above grade. The potential for hydrogen generation did not increase with the addition of scrubbing systems, and draft through the plant continued.

No reported hydrogen incidents have occurred in single absorption-scrubbing plants to date.

Double absorption – over 30 hydrogen incidents

Essentially all new sulfuric acid plants used the double absorption process along with many of the existing sulfuric acid plants that were converted to double absorption. All had an absorption tower with gas-gas heat exchangers in the center of the process that created a cold trap, minimizing the plant draft to the stack. In addition, plants with a blower ahead of the drying tower were required to have a tight close valve to prevent back flow of furnace SO2 gas to atmosphere via the dry tower and blower, preventing a draft through the plant. The intermediate absorption tower mist eliminator was of two types: Two stage mesh pads by Otto York Co. and Begg Cousland; or high efficiency Brownian Motion candles from ICI-Begg Cousland, Koch and MECS, with top center outlets from the tower.

Candle damage

The change from stacks of cast iron AX sections to anodically protected shell and tube acid coolers in the early 1970’s was a major change in the potential for an acid cooler tube leak to generate large quantities of hydrogen. In addition, the energy crisis in 1973 increased the value of the energy recovered from the sulfur-burning sulfuric acid plant.

Recovering heat from the gas in the economizer ahead of the absorption towers became economical. The old wives tale of one designer that the gas to the absorbers could not be cooled in the economizer below 400 degrees F was discarded and the gas to the absorbers was cooled to 300–330 degrees F with no effect on economizer acid condensation.

The heat exchange surface area required for the additional cooling increased significantly (as the gas to boiler feed water delta T decreased), and the cast iron gill ring design could not be used. The economizer heat exchange surface became extended surface carbon steel finned tubes.

Design changes 1970’s to 1990’s

The major changes to the sulfuric acid plant design in the period from the early 1970’s to early 1990’s were: 1. Interstage absorption system addition. Interstage absorption systems increased SO2 conversion efficiency Sulfuric Acid Today • Fall/Winter 2015

2.

3.

4.

5.

6.

7.

to the required 99.7 percent or 4 lbs. SO2/ton, but added a cold place in the middle of the plant that essentially stopped the draft through the plant on shutdown.

Plants with the blower before the dry tower required a tight close valve at the blower discharge (ahead of the dry tower) to prevent back flow of hot SO2 gas from the furnace through the dry tower and blower to atmosphere on blower shutdown, preventing a draft through the plant.

Acid coolers were changed from stacks of cast iron AX sections to stainless steel shell and tube exchangers, providing the potential for generating large quantities of hydrogen from an acid cooler tube leak.

Economizer design changed from cast iron gill ring covered tubes to carbon steel finned tubes to provide sufficient heat transfer surface area for the required additional energy recovery.

Economizer designs continued the use of vertical down inlet gas flow over the coils and vertically up exit gas flow, limiting exposed metal to the leaking tube coil and the bottom surface of the economizer, reducing exposed surface corrosion and hydrogen generation. Some designers used horizontal economizers in a few installations, providing increased metal surface for corrosion and hydrogen generation.

Plant size increased from about 1,500 STPD to about 3,000 STPD. HAZOP analysis during the period did not include consideration for hydrogen generation or explosion, as there were no reported hydrogen incidents until 1990.

Why only one hydrogen incident from 1970’s to 1990’s?

With the design changes outlined above (double absorption process eliminating draft through the plant, shell and tube or plate type acid cooler generating hydrogen on a tube or plate leak and carbon steel extended surface economizer providing greater surface for hydrogen generation) it is surprising there was only one reported hydrogen explosion incident—Farmland No. 3 plant in 1990.

The Farmland No. 3 plant was a 1960’s single absorption unit converted first to ammonia scrubbing (1975), then to double absorption (1980’s) to meet Florida state SO2 emission standards for existing sulfuric acid plants. The double absorption design included a horizontal economizer connected to the bottom (3rd) stage of the existing converter at the converter outlet elevation, and an absorption tower with candle mist eliminator and side mounted gas outlet. A leak in the economizer coils allowed weak sulfuric acid to cover the economizer bottom and bottom coils, along with the bottom (floor) of the converter. This provided a large extended surface for hydrogen generation. The hydrogen flowed to the absorption tower and collected in the stagnant area in the top section of the tower. About one hour after the plant was shut down and economizer drains were opened the hydrogen that collected in the top section of the absorption tower exploded. An investigation indicated the horizontal economizer allowed weak acid to corrode the floor and lower coils of the economizer, and the bottom of the converter, providing a large surface area for corrosion and hydrogen generation.

The side gas outlet from the interstage tower provided a stagnant area for hydrogen to build up.

The Farmland hydrogen incident was presented by John Friedman of Farmland in 1991 to the local Florida section AIChE group at a monthly meeting in Lakeland with over 200 attendees representing most of the Florida fertilizer-sulfuric acid industry. The group’s response to the Farmland incident was typical, “We have been operating sulfuric acid plants for many years and this has not hap-

pened to me or others I am aware of, so why worry.” The subject of hydrogen generation or explosion was still not considered in a HAZOP (hazard and operability analysis), MOC (management of change) or PSD (prevention of significant deterioration) review.

Shell and tube acid coolers— development

Shell and tube acid coolers have been used for many years (since the mid 1950’s-early 1960’s) in Allied-General Chemical (now Chemtrade) plants. The coolers are constructed of 304 stainless steel and operate in 99+ percent absorber acid and cold (<120 degrees F) 93 percent drying acid. The Allied-General Chemical spent acid regeneration plants were originally single absorption with top gas outlets to the stack, and later converted to add-on double absorption with top outlet high efficiency candle mist eliminator vessels. Non-anodically protected stainless steel shell and tube acid coolers are still being used in many of these plants. The key to successful operation is operation of the absorber cooler at acid concentrations above 99 percent, and dry tower coolers at acid concentrations above 93 percent at acid temperatures below 120 degrees F. The coolers are mounted in an elevated position, above the pump tank or tower acid reservoir, and free drain on acid/water shutdown. No hydrogen incidents have occurred in over 55 years. Other attempts with non-anodically protected shell and tube acid coolers at other operating conditions were not successful, with useful life less than one year.

In the late 1960’s–early 1970’s Canadian Industries Ltd. (CIL) technical group, supporting the operation of the pyrite roasting sulfuric acid plant at the INCO Copper Cliff, Canada copper/nickel smelter, worked on the development of shell and tube acid coolers to replace the normal cast iron AX section acid coolers for a new plant to be added to the site. They first tried non-anodically protected shell and tube stainless steel exchangers (as used by Allied-General Chemical) and found a life of less than 6 months. The literature indicated anodic protection of metals as a means of corrosion protection, and they tried the Continental Oil developed Anatrol System, supplied by Magna Corporation.

Bench scale and pilot tests were made. The group added anodic protection to the 316 stainless steel shell and tube acid coolers and found a range of voltage potential that would hold the corrosion protective oxide film in place. Other modifications resulting from early failures, included a no tube in baffle window design, and expanded acid nozzles to reduce velocity and turbulence. The early coolers were mounted vertically in the acid flow from the pump to the tower. Extended life with near zero corrosion resulted, and the Chemetics division of CIL was formed to fabricate and market the new anodic protected shell and tube sulfuric acid cooler to the industry.

Economizer baffle damage from hydrogen explosion.

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Single absorption scrubbing–no reported hydrogen incidents

Feature

To minimize corrosion of the exchangers a number of design and operating rules were required by CIL-Chemetics for the guarantees and proper operation: 1. The acid pressure must be maintained above the water pressure at all times during normal operation and on shutdown, to prevent water from a leaking tube entering and diluting the acid causing low acid concentration corrosion of the stainless steel tubes.

2. During operation, high water velocity must be maintained to minimize water side fouling. Minimizing tube wall temperature, and acid tube wall temperature induced corrosion. Control acid temperature by acid side bypass, not water flow, to minimize acid temperature and velocity.

3. Must continuously monitor exit water pH/conductivity to rapidly detect a tube leak.

4. On a tube leak, must rapidly drain the water side first, then acid side of the exchanger to maintain the acid pressure above the water pressure.

5. Note: There was no mention in the cooler operating manual or any acknowledgement of acid leak corrosion producing hydrogen.

Initially the anodically protected shell and tube acid coolers were mounted vertically from the pump discharge to the tower inlet. Some were arranged horizontally above the acid pump tank. In both cases on shutdown the acid would drain from the cooler and acid piping back to the pump tank, and cooling water would drain back to the cooling tower basin, leaving the cooler and piping (water and acid) empty with no hydrogen generation. During the initial years of operation there were sporadic acid tube leaks, and a gun was developed to rapidly inject a plug in leaking tubes. Some plants indicated difficulty plugging tube leaks, or changing cathodes once every 2-3 years in vertical and elevated acid coolers. In response to operator’s requests, most designers changed the cooler arrangement to locate the coolers at grade in a curbed area. Most installed a cooler drain pump to pump out acid from the cooler and piping on a tube leak or a shut down for maintenance. Water was drained to the ground in the curbed area to a pit.

The reasons for only one hydrogen explosion during the period 1970’s to 1990’s in double absorption plants are as follows: 1. Interstage Tower Stagnant Areas: There were essentially no stagnant areas in the interstage tower.

a. The interstage tower exit gas mist eliminator used by all but one designer was a pad type mounted in a reduced diameter stainless steel section at the top of the tower with center top gas outlet. No stagnant area. b. One designer used high efficiency candles in the interstage tower with a top center outlet. Although the upper section of the tower was large with dished head and full tower diameter, the center top gas outlet provided minimum stagnant area for hydrogen build-up (except the Farmland tower that had a side gas outlet that provided a large stagnant area for hydrogen to build-up).

2. Operation and Maintenance Practice: With the relatively new double absorption process (from mid1970’s), good operation and maintenance practices were followed and included:

a. Economizer and cold heat exchanger drains were checked regularly, once per shift and later once per day, to check for acid condensation – water leaks. This was especially needed in plants with a high efficiency mist eliminator in the interstage tower that removed even the fine acid mist so a water leak did not produce a visible stack.

PAGE 34

Acid tower dome

b. Proper shell and tube acid cooler operating procedures were closely followed.

i. Water side leak detection pH and conductivity meters were monitored and checked regularly for proper operation to rapidly detect an acid cooler tube leak. Manual operator pH/ conductivity tests were made once per shift to once per day to confirm instrument readings.

ii. Water side pressure drop was monitored regularly to ensure maximum water flow at all times.

iii. When there was a tube leak, the water was shut off and drained before the acid pump was shut down and acid was drained by the acid cooler drain pump. In order to maintain acid pressure above the water pressure.

3. Plant Purge—Removing one Protection: The draft to the stack on plant shut-down was eliminated by the interstage system and prevented by the blower discharge valve in blower before dry tower plants. Plants with a blower after the dry tower had a short time, about 3-5 minutes, gas purge from the turbine driven main blower rolling to a stop on shutdown.

Why now: changes 1990’s to date— over 30 incidents in 15 years

There have been over 30 reported major hydrogen explosion incidents around the world since the late 1990’s, all in double absorption sulfuric acid plants. All except one resulted in the explosion taking place in the top of the interstage tower alone or along with the dry tower, or in a few cases, the interstage tower exit duct. Essentially all tower explosions have been in towers with candle mist eliminators with side tower gas outlets (stagnant areas) or in the high point of the interstage tower exit duct. In one case, the explosion occurred in the stagnant area in the top channel of a converter internal heat exchanger. Hydrogen generated in more than half of the incidents was from an acid cooler leak, two were from horizontal economizers, one from a heat recovery system boiler and concentration control, and

the remainder from standard steam system – boiler, superheater and economizer leaks/corrosion.

Changes in the last 15 to 20 years that increased the potential for hydrogen generation and explosion.

1. Acid plant capacity increased from 3,000 STPD to about 6,000 STPD. Equipment increased in size.

2. Interstage stagnant area: The designers replaced pad type entrainment separators and mist eliminators in the interstage tower and many dry towers with either impaction candles or high efficiency candles. All towers now had a large diameter section on top of the tower. The change was made to increase acid particle removal efficiency, and for safety during maintenance of the entrainment separator/mist eliminator. It is safer to stand on a tubesheet to work on or replace a mist eliminator candle, than on an acid wetted slippery 4” or 6” stainless steel beam 8’-10’ above the acid distributor to repair or replace a pad mist eliminator.

a. Many designers relocated the center top gas outlet to the side of the tower upper section. The side outlet saves a duct elbow, some duct length, and opens the tower dome for easier candle removalreplacement. This change provided a large stagnant area in the tower upper section for hydrogen to build up.

3. Acid cooler: Shell and tube acid coolers grew in size along with plant size. Most remained anodically protected, but some designers installed non-anodically protected shell and tube coolers using austenitic silicon stainless steel (18Cr-18Ni-5Si-2 percent Cu, an alloy used for many years in nitric acid service) marketed under the trade names, Saramet® and Sandvik SX® (and recently ZeCor®).

a. Essentially all acid coolers were located at grade.

Most designers included an acid drain pump, others provided a drain connection for a pump out truck. b. Acid and water side vents and drains remained small, the same size (3/4”, 1” & 2”) as the original small heat exchangers, significantly increasing acid cooler water and acid drain time. c. Operator and Maintenance Practice: Long term leak free operation of acid coolers results in a loss of proper operation monitoring, and shutdown and draining procedures. Operator and maintenance attention to the acid cooling system was reduced by the long term leak free operation of the acid cooler. Monitoring of instrumentation (water pH and conductivity, water delta P, Anatrol meters and alarms, etc.), was replaced by computer system control by exception mode of operation, and operator attention moved to more pressing operation and monitoring duties.

4. Economizer: Safety concerns with opening economizer and cold heat exchanger drains blowing hot SO3 gas and acid, along with extended periods of steam system and economizer leak free operation, resulted in operators extending the time between checking drains for acid condensate, from once per shift or day, to weekly or monthly, or not at all. When not operated regularly, the drains would plug with sulfate and debris and be useless for early detection of water leaks in the plant.

Some designers installed horizontal economizers (economic decision), without considering or understanding the additional exposed surface for acid condensate corrosion and hydrogen risk.

5. Heat recovery system: In the late 1980’s Monsanto Enviro-Chem recognized/noted the corrosion free operation of austenitic stainless steel at high temperature in Sulfuric Acid Today • Fall/Winter 2015

Sulfuric Acid Today • Fall/Winter 2015

The hydrogen incident history of plants with alloy equipment (over 25 years) indicates (except for acid coolers) they are not a significant contributor to hydrogen generation or explosions, even in the all alloy HRS system with one hydrogen explosion in 25 years of operating plants.

7. Purge gas–no draft through plant: A draft through the plant on shutdown purges hydrogen from the plant equipment and is a significant contributor to minimizing hydrogen build-up and the potential for a hydrogen explosion. Single absorption plants alone or with a tail gas scrubbing system have not had a reported hydrogen incident from the 1920’s to date, and the purge or draft through the plant on shutdown is a significant reason. All of the hydrogen explosion incidents have occurred in double absorption plants where the draft or purge on shutdown is minimum or eliminated.

What can we do?

“Don’t guess at the solution, tell me what happened and why and the solution will be obvious,” were the words my first boss drummed into me 51 years ago (to a just out of school nuclear and chemical engineer) working in the technical group of a nuclear power reactor fuel reprocessing plant where much of the equipment was located behind five feet of high density concrete. With radiation and nuclear criticality issues, it was not a place for guessing solutions to problems.

The above review of hydrogen incidents follows those well proven words. The review in the previous sections outlines what has changed in sulfuric acid plant design and operation in the last 15-20 years that resulted in over 30 hydrogen incidents (explosions) around the world in double absorption sulfuric acid plants, and not in the first 80 years of single absorption sulfuric acid plant operation, or the first 20-30 years of double absorption plant operation.

The knowledge, analysis and insight of the hydrogen study group combined with the above analysis of Why Now, leads to the following Acid Engineering & Consulting, Inc. (AE&C) recommendations of design and/or operating changes to minimize or eliminate the potential for a hydrogen incident-explosion in sulfuric acid plants. Many of the suggestions are the result of public presentations by members of the hydrogen study group.

1. Eliminate Stagnant Areas for Hydrogen to Build up

a. Use top outlet absorption and dry tower gas exit to eliminate stagnant areas. b. Consider adding automated high point vents to purge hydrogen on economizer and acid cooler leaks.

c. Use single absorption with sodium or ammonia based scrubbing process—no stagnant areas and purge-draft through plant.

2. Reduce Potential for Corrosion - Hydrogen Generation

a. Reduce surface area for corrosion—economizer. i. Use vertical down inlet gas and vertical up exit gas to minimize exposed metal (limited to leaking coil and vessel bottom). ii. Avoid use of horizontal economizer arrangement.

b. Detect steam system water leaks early—cold exchanger and economizer. i. Use large (3”-4”) cold exchanger and economizer drains to detect water leaks, design to be rodded out. ii. Check cold exchanger and economizer drains regularly—once per day minimum for early detection of water leaks. Install drains designed for operator safety when opening and closing.

c. Acid cooler installation to minimize potential for

corrosion and hydrogen generation. i. Install acid coolers above the acid pump tank either vertical or horizontal, so they free drain on acid circulation shutdown. Install system (interlock, etc.) to drain water (to ground or back to cooling tower basin) on acid cooler and acid pump shutdown. ii. If acid coolers are located at grade, shut down and drain cooling water before stopping the acid flow.

1. Install interlock system to trip cooling water flow and drain water (to the ground in curbed area) on cooler leak shutdown and on acid pump shutdown.

2. Install an acid cooler acid drain pump to rapidly remove acid from the cooler to the acid pump tank, acid storage tank, or other safe location.

3. Use large vent and drain connections to facilitate rapid draining of water and acid.

Use 1” minimum vents and 3” minimum drains on the water and acid side of the exchanger iii. Monitor acid cooler instrumentation (pH/conductivity, etc.) both online and with once daily (minimum) manual operator checks to ensure instruments are working correctly and to detect water leaks early.

3. Purge hydrogen from the plant on shutdown. Purging hydrogen from the plant on shutdown is a contributor to minimizing hydrogen build-up and hydrogen explosions.

a.

Plants with tower side gas outlets should modify the tower outlet to a top outlet to eliminate stagnant areas in the tower, and/or:

b.

Operate the main blower at low speed to purge the plant of hydrogen until the water and acid are drained from the acid cooler or economizer.

c.

Single absorption plants with or without sodium or ammonia tail gas scrubbing draft to the stack and purge hydrogen from the plant. The plant draft-purge is a contributing reason there have been no reported hydrogen incidents/explosions in single absorption plants in the last 100 years of plant operation.

d.

Double absorption plants do not draft on shutdown due to the cold trap (interstage absorption system), and the tight close valve in plants with the main blower ahead of the dry tower. A purge of the plant by the main blower should be done in plants with side tower gas outlets until the water and acid are drained from the cooler and economizer, also a good idea in plants with top gas outlets.

e.

Consider adding automated high point vents to purge hydrogen on economizer and acid cooler leaks.

4. Operation and maintenance: Continued operator training for both normal operation, and handling of upsets and shutdowns (moving the plant to a safe down position, and preparation for maintenance) is necessary to ensure operators are prepared for unusual plant upsets or acid or steam leaks that may occur infrequently.

a.

Acid coolers: Long term leak free operation of acid coolers results in a loss of proper operation monitoring, and shutdown and draining procedures. Operator and maintenance attention to the acid cooling system was reduced by the long term leak free operation of the acid cooler.

Monitoring of instrumentation (water pH and conductivity, water delta P, Anatrol meters and

PAGE 35

Feature

acid at concentrations above 99 percent used since the 1950’s in Allied-General Chemical plants, and patented that use as the basis of its heat recovery system (HRS).

From the early 1990’s, Monsanto has installed many heat recovery systems operating with more than 99 percent sulfuric acid at temperatures above 400 degrees F, using 310 (austenitic) stainless steel, with a steam boiler used to cool the hot acid. The boiler operates with the water pressure well above the acid pressure. A boiler leak flows water to acid, diluting the acid, corroding the boiler and circulating pump, and stopping the acid flow.

The acid cooler/boiler is located above the acid pump tank. When the acid flow is stopped, the elevated cooler/boiler drains the acid to the pump tank, while interlocks vent the steam and drain the boiler feed water. The circulating pump failure and acid cooler-boiler located above the pump tank minimizes corrosion and hydrogen generation. The design purposely constructs the circulating pump of materials to fail if the acid is diluted, and the elevated cooler/boiler drains the acid from the boiler and circulating piping on circulating pump failure (stopped acid flow). The change to elevated cooler/ boiler, and failure prone circulating pump was done to stop circulating corrosive hot dilute sulfuric acid and reduce overall HRS system corrosion, not to reduce hydrogen generation, although it had that effect.

The HRS tower uses high efficiency candles and a side tower gas outlet, so one would expect more than the 1-2 hydrogen explosion incidents. The elevated acid cooler-boiler is the key to avoiding large amounts of hydrogen generation and additional incidents. The HRS system equipment is constructed of 310 stainless steel providing a large surface for weak acid corrosion and hydrogen generation. However, the failure of the acid circulating pump, stopping acid circulation on dilution of the acid and the elevated boiler/ acid cooler minimizes hydrogen generation.

6. Alloy equipment (converters, towers, pump tanks, acid piping, acid coolers, etc.): During the 1990’s, sulfuric acid plant equipment gradually changed from acid brick lined and cast iron to stainless steel. Stainless steel has been used for sulfuric acid plant equipment since the 1950’s by Allied-General Chemical, but not widely used by others due to its cost being more than twice the standard materials of construction of acid brick, carbon steel, and cast iron.

The major change to stainless steel started in 1970 with the development of the anodic protected shell and tube acid cooler that gradually took over acid cooler service by the mid 1970’s. A stainless steel converter design was proposed by Chemetics in 1979-1980 using an updated central tube design developed in the early 1950’s by Chemico, Dorr Oliver, etc., substituting stainless steel for carbon steel and cast iron used in the earlier designs. For a replacement converter the stainless steel converter, although higher in cost, could be built remotely and lifted into place to replace a carbon steel cast iron converter in about one-third the time, saving plant down time. Alloy (stainless steel) towers and pump tanks of Saramet® and Sandvik SX® followed for the same reason–built remotely and lifted into place to replace old equipment, saving down time.

By the mid 1990’s, new plants were being built with alloy converters, towers and pump tanks. All of the alloy equipment went through a long learning curve (over 15 years) of various failures (scale of converter, and corrosion of towers and pump tanks). Eventually the cause of the problems became known and solutions were found.

F eFaeta utru er e

alarms, etc.), was replaced by computer system control by exception mode of operation, and operator attention moved to more pressing operation and monitoring duties.

i.

Monitor acid cooler instrumentation (pH/conductivity, Anatrol system and alarms, dilution water flow, etc.) both online and with once daily (minimum) manual operator checks to ensure instruments are working correctly and to detect water leaks early.

ii.

When an acid cooler leak is detected:

1. Shut off the sulfur or SO2 gas feed and reduce the main blower to a minimum flow setting to purge the plant.

2. Then shutoff the cooling water and drain the water side of the acid cooler to the curbed area or sump.

3. After the water side is drained, stop the acid circulating pump and drain the acid from the cooler using the drain pump if provided, or if not, by hose to a portable pump to a safe location or area.

4. Continue the gas purge by the main blower until the leaking acid cooler is drained (water and acid).

5. When the acid cooler is drained (water and acid), stop the main blower plant purge. b.

Economizers—Cold Heat Exchangers: Safety concerns with opening economizer and cold

heat exchanger drains blowing hot SO3 gas and acid, along with extended periods of steam system and economizer leak free operation, resulted in operators extending the time between checking drains for acid condensate, from once per shift or day, to weekly or monthly, or not at all.

When not operated regularly, the drains would plug with sulfate and debris and be useless for early detection of water leaks in the plant. i. Check economizer and cold heat exchanger drains once per shift or at a minimum of once per day to detect water leaks into the gas system early. ii. When a water leak is detected and the leaking equipment (boiler, superheater, economizer) is located: 1. Shut off the sulfur or SO2 gas feed and reduce the main blower to a minimum flow setting to purge the plant. Continue the gas purge by the main blower until the acid condensate in the economizer or cold exchanger is drained.

2. When the acid condensate is drained from the economizer and cold exchanger, adjust the main blower flow to purge the plant in preparation for cool down to repair the steam/water leak.

Summary

The intent of this presentation was to answer the questions: 1) Why now? and 2) What can we do to minimize and/or prevent hydrogen incidents/explosions in sulfuric acid plants. The recommendations are the result of the

analysis of the incidents, the changes in the design and operation of sulfuric acid plants in the last 100 years, and the changes that resulted in the over 30 hydrogen explosions in double absorption plants in the last 15 years. The work of the hydrogen study group provided significant knowledge and analysis of the many hydrogen incidents around the world and formed a basis of this review.

The recommendations presented should be used together with the suggestions of the hydrogen study group, and others, in a HAZOP of existing and new sulfuric acid plants.

Acknowledgements & References 1. Hydrogen Study Group – Meetings, Discussions, Pictures and Presentations

a. Leonard J. Friedman - Acid Engineering & Consulting

b. Richard Davis – Davis & Associates Consulting

c. James Dougherty – Mosaic Co.

d. George Wang – Eco Services e. Hannes Storch, Karl-Heinz Daum & Collin Bartlett – Outotec f. Rene Dijkstra & Michael Fenton – ChemeticsJacobs g. Bruce Garrett – MECS Inc. (New) & Steven Puricelli – Independent (formally representing MECS) h. Daniel Freeman – SNC-Lavalin 2. CIL-Chemetics Sulfuric Acid Cooler Operating Manual 3. Manufacture of Sulfuric Acid by F.D. Miles, 1925 4. Sulfuric Acid Manufacture – by A.M. Fairlie, 1936 5. Manufacture of Sulfuric Acid – by W.W. Duecker & J.R. West, 1959 6. Papers & Presentations by J.B. Rinckhoff & L.J. Friedman, 1973 to date q

Process Technical Services Experience: • A team of experienced staff with background spanning from process design, mechanical design, operations, maintenance, equipment fabrication and process controls • Supported by Chemetics engineering capabilities in all disciplines including R&D Features and Benefits: • Feasibility and Debottlenecking Studies – Study process and equipment limits for production and emissions – Identify capital investments and the costs of alternatives to achieve new capabilities • Operations Support and Process Optimisation – Evaluate current and identify opportunities for improvement – Determine root causes of equipment and process underperformance • Process Development and Laboratory Services Chemetics core value of relationship building allows us to provide continuous support from the initial concept to project design, execution and beyond.

Innovative solutions for your Sulphuric Acid Plant needs Chemetics Inc.

Chemetics Inc.

www.jacobs.com/chemetics

Chemetics Inc., a Jacobs company

(headquarters) Vancouver, British Columbia, Canada Tel: +1.604.734.1200 Fax: +1.604.734.0340 email: chemetics.info@jacobs.com

PAGE 36

(fabrication facility) Pickering, Ontario, Canada Tel: +1.905.619.5200 Fax: +1.905.619.5345 email: chemetics.equipment@jacobs.com

Sulfuric Acid Today • Fall/Winter 2015

Feature

Sulfuric acid plant training for managers, engineers and operators

By: Andrés Mahecha-Botero, Ph.D., P.Eng. and C. Guy Cooper, P.Eng., NORAM Engineering and Constructors Ltd., Vancouver

Operating, maintaining and upgrading a sulfuric acid plant are challenging tasks.

They require knowledge about many disciplines that is difficult to convey to newcomers to the industry. Moreover, experience from senior engineers and operators is difficult to transfer within the organization. NORAM offers a systematic training course that utilizes knowledge management techniques to train managers, engineers and operators based on the core knowledge already existing within plant personnel, and enhanced by state-of-the art know-how on sulfuric acid manufacturing.

A site meeting is held prior to preparing the course material so that the training seminar is customized to the plant’s specific flow sheet and equipment.

A big part of the core know-how of the key disciplines associated with sulfuric acid manufacture in a particular plant is often buried within the plant manuals, operating procedures and plant standards, making it challenging to learn. For this reason, a significant part of the learning occurs through many years of operating experience and discussions with senior personnel.

NORAM’s acid plant training can improve and speed-up this process, and also foster discussions on specific areas of interest. The following issues are typically addressed:

Understanding of fundamentals:

It is important to understand a number of fundamental concepts associated with process engineering, mechanical engineering, materials engineering and instrumentation and control.

These important concepts are key to understanding unit operations, equipment and procedures. For this reason, unlike other training programs, a significant part of the course is dedicated to presenting the principles required to appreciate adequate operating practices. Key objectives of the training course include: — Explain the process chemistry.

— Provide gas cleaning and acid plant operating theories.

— Explain designs and the subsequent operating basis.

— Explain how the overall plant works.

Senior experienced plant personnel may leave the company:

It is important to ensure that the knowhow developed by an individual over decades of work does not leave the company when the person retires. The training program is designed to capture existing know-how and transfer it to a wide range of people, sharing this institutional knowledge.

PAGE 38

Fig. 1: A typical slide about the main process steps in a sulfuric acid plant.

Fig. 4: Prevention of plant problems, focusing on the importance of stick tests.

Training of new personnel: Newcomers to the acid plant may not appreciate the complexity of the acid plant operation, and the severity of the consequences of a possible error in operation.

The training program allows newcomers to understand important aspects of sulfuric acid to become productive faster. Key objectives of the training course include: — Explain what happens if there are process deviations.

— Explain importance of taking measurements.

— Consequences of not running a unit operation correctly.

ensure the best outcome now and in the future. Key objectives of the training course include: — Explain different equipment available in the market.

— Discuss equipment replacement strategies.

Training of project people:

Project managers and engineers often make important decisions that can affect plant performance. The training program ensures that people dedicated to projects benefit from the experience of others to

Differences of opinion: Each person typically has different opinions about certain aspects of the plant operation. In some cases, this can be problematic, since the plant may be operated differently from shift to shift.

Moreover, some erroneous opinions can lead to problems in the plant. The acid plant training is useful to standardize the know-how within the plant. Fig. 8 shows a typical in-class discussion starter.

Fig. 7: Equipment operation considerations.

Discussion of current plant issues:

The course also gives the opportunity to brainstorm about the possible causes and solutions to specific plant issues.

Acid Plants Training Groups

Fig. 2: Plant operation slide.

Fig. 6: A slide presents different types of equipment.

NORAM’s specialists focus on developing the training material for a specific plant by taking input from senior plant people. Open discussions are essential to ensure the best possible learning outcome.

Typical training lasts about 20 hours, and classroom sizes can be customized to fit a particular scheduling need by the

Fig. 8: Root cause analysis of plant issues.

client. NORAM’s instructors specialize in acid plant design, project execution and often also teach at the undergraduate and graduate level. Fig. 9 shows a typical NORAM class of 20 to 30 people from all backgrounds and levels of seniority.

Fig. 9: A typical NORAM training session.

Fig. 3: Strategies for prevention of plant problems. The importance of pressure surveys is discussed.

Fig. 5: Equipment considerations, including advantages and disadvantages, are discussed.

NORAM Engineering and Constructors Limited performs engineering studies and training as well as supplies improved equipment at attractive prices for sulfuric acid plants. For more information, email sulfuric@noram-eng.com, or call (604) 681-2030. q Sulfuric Acid Today • Fall/Winter 2015

Department

LESSONS LEARNED: Case histories from the Sulfuric Acid Industry

Cooling water leak into boiler feed water

Steam generating boilers are commonly used in sulfuric acid plants, for process gas cooling, waste heat recovery and steam usage at various locations. The steam—typically in the 450 to 900 psig range—drives turbines, and upon pressure reduction meets other heating needs in the plant. Upon extracting the useful energy, most of the steam is condensed and returned as feed water to the boiler.

As with any industrial boiler, the feed water must be kept clean with low mineral content to avoid boiler tube and turbine rotor deposits.

In one acid plant, a cooling water leak occurred in a steam condenser for the turbine generator. As the steam-side of the condenser is operated in almost full vacuum, and the cooling water side at approximately 40 psig, the leak path was cooling water into steam condensate. This was a slow leak, and continued for months without proper action. As cooling water is full of minerals, at approximately seven times the raw water concentration, even a small leak can overwhelm the pristine steam condensate system. The result was a series of boiler tube ruptures caused by

overheated tubes, stemming from waterside hardness deposits. These boiler tube ruptures caused a lot of plant outages, and to minimize further down time, the plant employed drastic short term measures.

This included an inhibited acid wash of the water tube boiler, followed by hydroblast cleaning of each tube, to remove the majority of the hardness deposits. The condenser was also repaired to prevent further leaks and damage. The short-term repair required two weeks of unplanned outage, and allowed the plant to operate until a scheduled turnaround when more permanent maintenance could be done.

The boiler and condenser were subsequently re-tubed.

In another acid plant, a similar cooling water leak occurred at the turbine generator condenser, and again continued for months without proper action. In this case, the boiler tubes were not damaged, but minerals carried over to steam turbines for the main gas blower and the electrical generator. Both turbine rotors were coated with heavy mineral deposits, knocking them out of balance. The plant was shut down for a week to remove, clean and repair the main gas blower rotor.

The turbine generator was shut down for three weeks for rotor maintenance. The condenser leak was temporarily repaired.

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PAGE 40

This allowed the plant to operate until a scheduled turnaround when the condenser could be re-tubed.

Lesson learned: Take immediate action upon detection of conductivity or hardness increase in the boiler feed water system. Fix cooling water leaks as soon as possible.

Leaking converter isolation valves

Many acid plant converter systems are equipped with a startup preheater system to heat the converter beds prior to introducing SO2, known as a “cold startup.”

This typically consists of a fuel gas or oil combustion furnace system, a gas heat exchanger and associated ducting with isolation valves to the converter beds. The isolation valves need to perform well, from a wide open position during heat up, to modulation during the introduction of SO2, to a completely closed “tight shut off” position during normal operation. In some cases, this valve is exposed to a high process gas temperature of about 1,000 degrees F during the heat up phase, which makes the functionality of the valve very challenging.

In some configurations of double absorption plants, tight shut off during normal operation is especially critical for the isolation valve to the final converter bed. This isolation valve keeps a strong 10 percent SO2 gas on the high pressure side from leaking into the low strength 0.5 percent SO2 gas on the low pressure side, with a differential pressure of 150 inches of water column. As the final bed typically converts 97 percent of the 0.5 percent SO2, emitting 0.015 percent (150 ppm) SO2 to the atmosphere, a small leak in this isolation valve can significantly impact the SO2 emission. Coupled with a severe mechanical service during heat up, distortion and binding of the shaft/bearing can become a significant issue, if the valve is not constructed robustly.

Such was the case for a 3/1 double absorption acid plant, until the proper valve and maintenance method were found after several trials. In some startups, the isolation valves became so distorted, bound and inoperable that slip blinds needed installation and removal at hot condition, a nasty job for the maintenance workers.

This plant corrected the problem with a set of heavy duty butterfly isolation valves of stainless steel construction, including a warehouse spare. (A knife-gate valve, another widely accepted option, was considered, but was found more costly in this application.) It was also found necessary to lubricate and stroke the valve routinely, to keep the shaft and bearing from binding in this severe service.

Lesson learned: Choose the correct robust valve, and maintain it properly with routine lubing and stroking. Always keep a warehouse spare.

Charring of tail gas scrubber packing

Many acid plants are equipped with a tail gas scrubber to meet SO2 emission requirements mandated by various agencies including the EPA, state and local air quality districts. Many of these scrubbers utilize aqueous alkali reagents such as caustic, soda ash or ammonia, with the circulating alkali sulfite/bisulfite liquor pH ranging from acidic to basic. The scrubbers are therefore constructed with plastic and stainless steel to withstand corrosion. If the scrubber utilizes packed beds, polypropylene packing has been the top choice to withstand corrosion at a relatively low cost.

Under normal operating conditions, the polypropylene packing performs well in withstanding the corrosive nature of SO2 scrubbing with alkali sulfite and bisulfite liquor. It is susceptible, however, to an abnormal condition of a sulfonation reaction if a large quantity of SO3 is present, especially if the packing runs dry.

A single absorption acid plant experienced such an incident. This plant was equipped with a steam-turbine-driven main gas blower, a SO3 absorbing tower circulating strong acid with a motor driven pump and a SO2 caustic scrubber circulating sodium sulfite/bisulfite liquor with motor driven pumps. A power outage caused the absorbing tower and scrubber circulating pumps to cut out. The steamdriven main gas blower, however, kept running, directing unabsorbed SO3 gas to the scrubber for about 10 minutes. Upon return of power, the circulating pumps were restarted, and the operators noticed an abnormal pH in the scrubber liquor.

Upon shut down and inspection, the polypropylene packing was found charred by the SO3 with dry packing. This caused a plant outage to replace the damaged packing.

Upon investigation, it was found the main gas blower was not properly interlocked to shut down on power outage. Operators were not trained about the effect of SO3 gas in the scrubber.

To prevent further incidents, operator training was updated and the main gas blower was interlocked on power outage.

Additional interlocks were installed to shut down the main gas blower on low absorbing tower circulation and high scrubber temperature.

Lesson learned: Conduct a proper process hazards analysis, incorporate safety interlocks and update operator training. q Sulfuric Acid Today • Fall/Winter 2015

By: Joseph M. Salamone, Senior Vice President, Huntleigh Securities Corp.

This article addresses the problems of using published metal corrosion data in sulfuric acid plant design and presents the remedies to these problems. Published corrosion data is generally unreliable for comparing the corrosion resistance of high alloy steels to irons like gray iron, ductile iron and Mondi® for use in sulfuric acid plant design for the following reasons: • Laboratory data does not detail experimental procedures.

• Using the same laboratory methods to test both high alloy stainless steels and iron is inadequate because these two classes of metals exhibit very different corrosion resistance behaviors in acid.

• Corrosion tests are poorly designed.

• Corrosion data are incorrectly analyzed.

• Corrosion data are not systematically analyzed for errors.

Passivation process

The key difference between irons and high alloy stainless steels is the rate of passivation. Passivation is the main mechanism creating corrosion resistance of metals. When high chromium metal alloys contact sulfuric acid, the chromium and other high alloying elements in stainless steel react with acid to form a thin film of protective alloy oxides on the surface of the metal. This oxide layer is highly resistant to further corrosion, protecting the base metal. For stainless steels and other high alloys, the process of passivation occurs very rapidly, typically within minutes of the high alloy stainless steels coming in contact with sulfuric acid.

Because iron lacks the necessary chromium content or other high alloying elements to form a corrosion resistant, passive oxide layer, ductile and cast irons exhibit a completely different passivation mechanism and behavior in sulfuric acid than stainless steel alloys. The passivation process of irons in strong sulfuric acid takes weeks rather than minutes or hours to complete because passivation of iron does not involve the formation of a corrosion resistant chromium alloy oxide layer.

The large difference in passivation periods between high alloys and irons is what accounts for many of the problems with reported sulfuric acid corrosion data.

This article will demonstrate that when the long passivation period of irons is not addressed in the experiment design, its Sulfuric Acid Today • Fall/Winter 2015

Fig. 1: High alloy stainless steel corrosion in sulfuric acid.

oversight completely negates generating any meaningful corrosion data for irons like gray iron, ductile iron and specialty irons developed specifically for sulfuric acid service, like Mondi® ductile iron.

If the experiment design, procedures and accuracy of measurements are adequate and replicate the service conditions in an acid plant, the resulting laboratory data of the corrosion behavior of stainless steels in sulfuric acid is accurate and useful to discriminate between the corrosion resistances of the different high alloy metals and irons tested for acid plant design.

The long-term steady corrosion rate of stainless steel is achieved very quickly because complete passivation of high

alloy stainless steel occurs in the first few minutes or hours after contact with sulfuric acid. A stainless steel alloy’s passive state is part of an acid plants’ steady state condition.

Fig. 1 presents a typical example of the corrosion weight loss behavior of stainless steel alloys in strong sulfuric acid.

The red flat line in Fig. 1 illustrates the constant daily weight loss of stainless steel in sulfuric acid that is quickly and fully passivated upon immersion in acid.

Because of stainless steel alloys’ constant daily corrosion rates over the complete acid immersion period, the cumulative weight loss data yields a straightline plot passing through the coordinates’ origin. The blue line in Fig. 1 illustrates high

Fig. 2: Corrosion over time of iron in sulfuric acid.

alloy stainless steel’s cumulative weight loss over time. The period during the acid immersion over which the stainless steel alloy was passive is shown in the bottom of Fig. 1 in yellow and comprises the length of the experiment.

The long-term, steady state corrosion rates of stainless steel in sulfuric acid can be accurately calculated using average corrosion rates of short-term immersion acid tests because their cumulative weight loss plot is completely linear. The stainless steel alloy’s average corrosion rate of 7 mpy in Fig. 1 is calculated by dividing its cumulative weight loss by its acid immersion period, its density and the exposed surface area of the sample, yielding a rate identical to its long-term corrosion rate.

The long-term, steady state corrosion rate of passivated metals is the key information necessary to determine a plant’s operating corrosion allowances to calculate the economics and safety of a plant design using different alloys with varying degrees of corrosion resistance.

Sulfuric acid plant operators and engineers are very familiar with the slow passivation process of iron. During the first month of new sulfur burning acid plant start-ups, acid plants typically produce sulfuric acid with an iron content in the range of 200-350 ppm. In some cases during the first few weeks of operating new plants, the acid iron content can reach up to 500 ppm.

A month or so after plant start-up, steady state conditions and iron passivation are achieved, and the iron content in the acid produced settles into the typical operating range of 20-40 ppm in most sulfur burning sulfuric acid plants.

Similar increases of the iron content in plant acid are experienced the first few weeks after acid piping has been replaced in a sulfuric acid plant. After a few weeks of operation, the iron content in the acid settles back down to its normal operating range of 20-40 ppm.

Fig. 2 presents a typical example of the corrosion weight loss behavior of iron in strong sulfuric acid. Because the daily corrosion rate of non-passivated iron varies over time, the measured cumulative weight loss of the iron samples is non-linear. As the daily corrosion rate drops off during passivation, the blue cumulative weight loss curve bends down, reflecting the slowing down of the daily corrosion rates during PAGE 41

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Pitfalls of using published stainless steel and ductile iron corrosion data for sulfuric acid plant design

Feature

passivation. After the iron samples are completely passivated in acid, their daily corrosion rates reach a constant steady state where the cumulative weight loss over time becomes linear.

The slope of the cumulative weigh loss curve at any point in time is equal to the instantaneous corrosion rate at that specific point in time. Because the cumulative weight loss curve of iron is nonlinear, calculating the average corrosion rate over the acid immersion period by dividing the cumulative weight loss by its acid immersion period, the density of iron and the surface area of the sample yields an average corrosion rate much higher than the corrosion rate of fully passivated iron.

The ten-day average corrosion rate calculation is illustrated in Fig. 3, where the cumulative weight loss of iron over the first ten days of acid immersion is divided by its ten-day period yielding an average corrosion rate of 240 mpy. For reference; the slope of the steady state corrosion rate of 10 mpy is also presented in Fig. 3, which illustrates the problem of calculating the corrosion rate of iron before it has completely been passivated.

The calculated average corrosion rate of iron over the initial ten days is 240 mpy, which is more than one magnitude higher than its fully passive, steady state corrosion rate of 10 mpy.

The higher calculated average corrosion rate of iron over the acid immersion period occurs because the cumulative weight loss in the rate calculation is inclusive of the weight loss from the transient, high initial corrosion of the bare iron. The rapid initial weight loss of bare iron is being averaged into the corrosion rate calculations, leading to consistently high readings of the average corrosion rate over the acid immersion period relative to the actual long-term corrosion rate of passivated iron.

Extending the acid immersion period

Given such poor test results and to try to generate more accurate data, the general inclination is to extend the acid immersion test period using the same flawed test procedure. Although extending the immersion period improves the experimental results, the improvement in accuracy may not be sufficient to achieve design quality data. Unfortunately, unless the experiment is extended for very, very long acid immersion periods, the calculated average corrosion rate of iron can still be in error by several orders of magnitude.

Fig. 4 clearly illustrates how the calculated average corrosion rate of iron from extended acid immersion tests can remain inaccurate and unreliable for plant design. The magnitude of the errors PAGE 42

is evident from comparing the ten-day average corrosion rate of 240 mpy and the extended forty-day average corrosion rate of 98 mpy to the actual long-term, steady state corrosion rate of 10 mpy of passivated iron of this example.

Although the forty-day test results are significantly better than the ten-day

test, the forty-day test also fails to yield a valid result. The calculated forty-day average corrosion rate of iron is 98 mpy, a rate ten times higher than the passivated ironâ&#x20AC;&#x2122;s real corrosion rate of 10 mpy in the example of Fig. 4.

It is clear from Fig. 4 that unless laboratory corrosion weight loss studies are

Fig. 3: Average corrosion rate of iron in sulfuric acid.

Fig. 4: Comparison of calculated average corrosion rates of iron in sulfuric acid.

conducted for very extended acid immersion periods, average corrosion rate calculations will be very poor approximations of the long-term steady state corrosion rate of passivated iron in sulfuric acid.

A false sense of confidence

What is so insidious about testing the corrosion resistance of iron is that many of the laboratory test results are readily reproducible and measured with high precision, leading to a false sense of confidence in the results. This false sense of confidence leads to a trap that ensnares many engineers designing acid plants and brings up the often ignored art of proper experiment design.

This is a case where reliance on the reproducibility of the laboratory corrosion test results as a proxy for the accuracy of the test procedure completely fails to corroborate the accuracy of the results.

Random errors tend to be both positive and negative without bias. By repeating an experiment multiple times and calculating the average result of the experimental trails yields a result with a high degree of accuracy because most of the positive and negative errors will cancel themselves out. In comparison, a systematic error introduces a bias into the experimental results which cannot eliminated or reduced by averaging the results of the multiple experimental trials.

The reality is that no matter how meticulous a researcher is, if the experimentâ&#x20AC;&#x2122;s design does not account for the correct passivation period of iron, the test results will lack accuracy because of the systematic error rather than the non-reproducible random errors.

Reproducibility and precision should not be confused with accuracy when selecting materials based on experimental data. The laboratory data generated by this flawed experimental method is unreliable for plant design even though the lab results are readily reproducible with high precision.

Error analysis of poor experiment design

Fig. 5: Propagation of errors of the calculated average corrosion rate of iron in acid.

Let us look at the magnitude of the errors of the experimentally calculated average corrosion rates of iron compared to the actual long-term corrosion rate of fully passivated iron. Fig. 5 presents the propagation of corrosion rate errors over time of a typical iron in sulfuric acid.

The difference between the average and actual daily corrosion rates of iron is the error indicated by the vertical purple arrow. This error varies over time and is illustrated by the curved green line. After achieving passivation of iron, the error curve measures the absolute error between the long-term corrosion rate of passivated iron and the calculated average corrosion Sulfuric Acid Today â&#x20AC;˘ Fall/Winter 2015

Sulfuric Acid Today • Fall/Winter 2015

Fig. 6: Ratio of errors of the calculated average corrosion rate of iron in acid.

as to how a corrosion study was conducted before its data can be considered for use in acid plant design or just for the simple selection of materials of construction.

Correct experimental testing design

To correctly measure the corrosion rate of passivated iron, you must eliminate from the rate calculations the initial weight loss prior to passivation. The simplest method is not to take weight loss readings until the samples have passivated in the acid bath (and in acid velocity tests), and then sequentially remove the metal samples over time to determine the corrosion rate of passivated iron.

To measure the passivation period, simply take iron content readings of the waste acid as it is being replenished during the corrosion weight loss experiments.

Once the iron content readings of the acid bath become constant, you can determine the period required for full passivation of iron, and you can begin the sequential removal of test coupons from the acid bath.

This test procedure allows you to measure linear differential changes of weight over time, yielding an accurate measure of the long-term corrosion rate of passivated iron. This experimental procedure completely excludes from the corrosion calculation the initial weight loss of the iron sample, correcting the deficiency of most published corrosion data of iron in sulfuric acid. Fig. 7 illustrates the results of a correctly designed experiment.

The final step of the experiment is performing a linear least-squares curve fit and analysis of the data. Fig. 7 illustrates that the calculated least-squares slope of the linear portion of the weight loss curve represents the actual long-term corrosion rate of fully passivated iron.

In contrast to Fig. 1, where the linear plot of the cumulative weight loss of stainless steels runs though the origin, the linear least-squares y-intercept for the corrosion data of irons lies above the origin because of the higher non-linear daily corrosion rate of iron during the passivation period.

The y-intercept in Fig. 7 represents the

incremental loss of iron directly attributed to the transient, higher initial corrosion rate of iron not being fully passivated throughout the experiment’s test period.

This incremental loss of iron caused by the lack of passivation is the weight loss that throws off the calculations of the average corrosion rate of iron over the experimental acid immersion period. This incremental weight loss error, attributed to the initial corrosion period when iron is not passivated, causes short-term laboratory results to greatly over-estimate the longterm corrosion rate of passivated iron in sulfuric acid.

To develop precise corrosion data, a simple error analysis should be used to determine the time interval required between sample coupon removals. Since the measure of time is extremely accurate relative to the length of the immersion period, it is easy to determine that the largest source of experimental error comes from weighing the samples prior to immersion, and after removal from the bath and cleaning the sample for final weighing.

A simple analysis shows that the major error is plus or minus double the precision of the weight balance because of the initial and final weighing of the samples and these errors are additive in nature. Data precision percentage is measured as: Data Precision in Percent = 2 x (+Weighing Error)/(Weight Loss of the Sample).

By re-arranging the equation we can determine the target weight loss required for the desired precision of the experiment: Weight Loss of the Sample = 2 x (+Weighing Error)/(Data Precision in Percent).

From the error analysis equation, you can calculate that to achieve a 5 percent precision of the data, the measured weight loss due to corrosion should be 40 times the accuracy of the weight balance. To achieve a maximum data error of only 2 percent requires the measured weight loss of the iron samples to be 100 times the precision of the weighing balance.

Having set the precision of the experimental data and calculated the target weight loss, you can back out the time interval between sample coupon removals by dividing the target weight loss by the expected corrosion rate. After a few experiments, you can refine the calculation of the time interval between coupon removals based on the corrosion rate calculated by the experimental results.

High alloy bias

Fig. 7: Experimental sulfuric acid iron corrosion test.

The cast iron/ductile iron industry generally does not perform corrosion tests of iron in sulfuric acid. Most of the published corrosion data of iron in sulfuric acid has been generated in the laboratories of stainless steel companies or metal alloy producers.

PAGE 43

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rate over the acid immersion period.

It is clear from Fig. 5 that even after the passivation period of iron is completed, the error alone in calculating the average corrosion rate is orders of magnitude greater than the actual steady state corrosion rate of passivated iron that the laboratory tests are trying to measure. During steady state corrosion, the magnitude of the errors from calculating the average corrosion rates dominate the computation for an extended period of time well beyond the completion of iron’s passivation period.

To complete any error analysis, it is always good engineering practice to also look at the behavior of the errors on a relative basis. Fig. 6 presents the errors as the ratio of the calculated average corrosion rate of iron divided by the corrosion rate of fully passivated iron. Because the errors presented by the calculated average rates of corrosion are so large, it was necessary to present the errors in ratio rather than percentage form.

From Fig. 6 it is clear the errors from average corrosion rates are high multiples of the steady state corrosion rate of fully passivated iron. In this example, the oneday average corrosion rate of unpassivated iron in sulfuric acid calculates to 350 mpy and when compared to the 10 mpy rate of passivated iron, it yields an error ratio of 35 to 1. This is the first point of the error curve plotted in Fig. 6. In other words, the one-day calculated average corrosion rate of iron over-estimates the actual passivated iron’s corrosion rate by a factor of thirty-five.

Particularly notable are the results of a one-day acid immersion test because there are published data of one-day corrosion tests studies from reputable alloy companies comparing ductile iron to stainless steel and other high alloys. Not surprisingly, the experimental errors in those 24 hour acid immersion studies make the corrosion resistance of ductile iron appear much worse, ranging from 200400 mpy. The experimental error makes the results of the studies highly biased, heavily favoring stainless steel alloys over ductile iron as the material of choice for acid service. Even for experimental acid immersion periods of 60 days or more, the error is approximately seven times the actual steady state corrosion rate of passivated iron, a 600 percent error.

As well meaning as most of these studies are, their results and conclusions about the corrosion resistance of irons in sulfuric acid are in error and are completely unreliable. Any published data showing the corrosion of gray or ductile irons in strong sulfuric to be of really high magnitude relative to high alloy stainless steels should be viewed with extreme caution, especially the results of short-term laboratory tests.

Very specific inquiries should be made

Feature

Not accounting for the long passivation period of iron heavily skews sulfuric acid corrosion resistance data leading to extremely misleading calculations of corrosion allowances and hence the economics of ductile iron or Mondi® iron relative to the high alloy metals.

Some individuals may incorrectly believe that data flawed in this manner may at least be of some value in relative comparisons of the corrosion resistance of irons to high alloy metals. This is completely incorrect, and there is no commercial value at all in these relative comparisons.

There are no known theoretical or empirical studies showing how to correlate the initial corrosion rate of an unpassivated metal to its long-term corrosion rate in a passivated state. Therefore, it is absurd to compare the transient, high initial corrosion rate of unpassivated iron to the long-term, steady state corrosion rate of passivated, high alloy stainless steels.

In comparative studies of material properties, it is generally desirable to seek consistency of lab procedures across the materials being tested. The diligent pursuit of consistent experimental data about the corrosion resistance of irons causes conscientious experimentalists to use the identical laboratory procedures developed to test the corrosion resistance of high alloy stainless steels.

Unfortunately, by standardizing the laboratory procedures developed for testing the corrosion resistance of high alloy stainless steels without adapting them to accommodate the characteristic long passivation period of irons, the results of some of these studies have become part of a knowledge base of unreliable corrosion data of iron in concentrated sulfuric acid.

Using NACE corrosion testing standard procedures In December 1995, with publication 5A195, NACE adopted Dr. Silverman’s spinning electrode method as the NACE standard for corrosion velocity tests of metals, supplanting NACE 1970 standard TM0270, “Method of Conducting Controlled Velocity Laboratory Corrosion Tests.”

Instead of being based on the traditional weight loss measurement method of corrosion testing as the preceding NACE 1970-TM0270, the spinning electrode testing method is based on the precise measurement of the galvanic current resulting from the corroding metal test samples.

As scientifically and technically elegant as NACE 5A195 is, this publication and its predecessor do not address the corrosion passivation period of the metals

being tested and its effect on the test results. For the unwary experimentalist using either of the NACE corrosion testing standards, these uncorrected test procedures lead to unreliable results when testing the corrosion resistance of irons in sulfuric acid.

The NACE standard focuses on laboratory procedures and equipment, excluding any discussion about the experiment design needing to eliminate the systematic error introduced into the experimental concentrated sulfuric acid corrosion data by the long passivation periods of metals like irons.

The NACE standard corrosion testing procedures must be used with caution because they are designed for short-term testing of passivated high alloy metals.

Dr. Silverman at Monsanto unsuccessfully tried for four years to adapt his spinning electrode corrosion testing method to make short-duration experimental measurements of the long-term corrosion rate of passivated iron in sulfuric acid.

Summary

Although procedurally simple, and as straightforward as corrosion testing of alloys in sulfuric acid seems to be, accurate testing of the corrosion resistance of irons requires a more sophisticated experiment design and data analysis than is generally

found in most published literature focused on testing high alloy metals.

Generating reliable lab data of the long-term corrosion behavior of both fully passivated irons and high alloy stainless steels for sulfuric acid plant design requires experiments that account for the different passivation periods of the metals tested.

Otherwise, the test results overestimate the corrosion rate of irons and fail to imitate their long-term corrosion behavior under typical acid plant operating conditions.

Under normal sulfuric acid plant conditions, the actual corrosion resistance of iron compares very favorably to many expensive high alloy stainless steels.

Conclusion

Given the much higher price of high alloy stainless steels, the economics of using standard ductile iron and specialty corrosion resistant irons like Mondi® are extremely attractive for most acid plant service conditions.

Joseph Salamone worked for five years for Monsanto Enviro-Chem Acid Plants Technology group where he developed the acid resistant alloy Mondi®. He was responsible for developing new technology, and commercializing new plant designs, processes and equipment. For more information, please contact Joe Salamone at joes@hntlgh.com. q

Maintaining Your Anodic Protection Systems By: Kris Stanuch, Corrosion Service Co. Ltd.

Anodic protection (AP) systems installed on sulfuric acid tanks, coolers, and piping are relatively maintenance free in day to day operation, effectively preventing vessel corrosion and maintaining acid purity. However, the lack of regular interaction with these systems often leads to long term maintenance procedures being neglected and the eventual degradation of operating performance.

Basic AP hardware consists of a DC current source, auxiliary cathodes, reference electrodes and signal conditioning electronics. This hardware configuration is largely unchanged since the first AP system for sulfuric acid was installed in the 1950’s, however the hardware and control methods used have continued to evolve as technology has improved. Modern systems now include remote monitoring hardware and services in their system configuration as part of a more simplified maintenance plan.

Long term AP system maintenance costs include replacement of reference electrodes and cathodes. The reference electrodes have a life expectancy of 2-5 years with the typical mode of failure being contamination of the sensing element. Cathodes are not consumed in an AP system, and have a life expectancy of over 10 years, however failure could occur, usually due to acid impingement or accidental mechanical damage during tank shutdown PAGE 44

periods. While these components are easily inspected and replaced, they can often remain damaged without the operator knowing that a replacement is necessary.

Due to component failure not always being noticeable, it is recommended that operators schedule annual onsite visits with a qualified specialist in order to validate operation of their systems, review maintenance procedures, train personnel, as well as provide recommendations for optimal operation, data collection, and implementation of new technologies. Iron levels of the acid could also be monitored and reviewed, since a proper operating anodic protection greatly reduces iron concentration.

Remote monitoring systems and services are inexpensive, and should also be considered to streamline site maintenance requirements. This ensures peace of mind with the knowledge that a qualified professional is always watching to ensure the continuous operation of all electrochemical corrosion systems. With continuous monitoring and data collection, operating efficiency and return on investment is maximized by early detection and correction of periodic system problems.

For more information contact Corrosion Service Co. Ltd. at (416) 630-2600 or e-mail acid@corrosionservice.com q Sulfuric Acid Today • Fall/Winter 2015

Problem:

A leading sulfuric regeneration acid plant along the Gulf Coast has had safety related concerns resulting from the difficult operation of gate valves after as little as six months in service. Sulfate/iron deposits have built up on the gate and stem, making it difficult to operate the valves. Furthermore, this deposit build-up on the stem can score and damage the stem packing when cycling the valve, creating a leak path to the environment. As a result of this leakage, spray shields have been retrofitted to the gate valves and plant personnel who operate the valves must wear acid suits for personal protection.

Solution:

Starting in 1998, the Amri Acris fully PFA Teflon®-lined butterfly valve was introduced to the plant.

The valve is specifically designed for highly corrosive applications as all wetted parts are PFA Teflon®.

Acris valve design

The Acris valve provides tight shut off upstream/downstream (allowing zero leakage) and a three step sealing system, including a spring energized safety seal, which eliminates shaft leakage. Since the valve is a quarter-turn design, there is no

stem or shaft that penetrates the packing area during cycling, eliminating the problem of the sulfate/ iron deposits in the rising stem gate valves. The sealing concept of the Acris valve is based on the use of a spherically shaped disc that mates with a spherically shaped liner in the shaft hub areas. This eliminates any change in shape and essentially creates a perfect 360-degree seal between the disc and liner. In addition, the PFA liner has a full width, 360-degree resilient back-up liner that energizes the PFA liner to create a tight seal against the shaft and disc. The spring-energized safety seal is totally independent from the spherically-mated parts and provides an additional level of shaft sealing that self-compensates for temperature change and wear.

Results:

Over the past 17 years, more and more Acris valves have been used throughout the plant because of the advantageous sealing and long life

Acris butterfly valves used for pump isolation without spray shields.

provided by this design. The need for spray shields and the wearing of acid suits has been eliminated when operating these valves in service. In addition, when an automated package is required, it is simply a matter of removing the manual gear and installing a quarter-turn actuator on top of the valve and connecting the air-lines and/or control devices.

Amri actuators are designed for di-

rect mount without the need for a bracket and coupling. This enables plant personnel to easily operate the valves from a remote location.

This is a huge advantage over gate valves that become difficult to operate manually after as little as six months in service, and also require changing the stem type from a threaded design to a sliding design in order to automate pneumatically.

In addition to these advantages, the Acris valve provides the ability for a customer to remove the downstream piping under full pressure when using a Lug body design.

There are also no periodic maintenance requirements after installation—there is no stem packing to adjust and nothing to lubricate. The Acris valve provides a long, maintenance free life.

For more information, contact KSB-Amri Inc. at (713) 682-0000, or info@amrivalves.com. q ®Teflon is a registered trademark of The Chemours Company FC, LLC.

Mercad Equipment Inc. is your universal source for new equipment, spare parts, tube plugging kits, inspections and emergency support of anodically protected sulphuric acid equipment.

Our Products and Services Include: • Design and Fabrication of Sulphuric Acid Coolers, Gas to Gas Heat Exchangers, Super Cathodes and Reference Electrodes • Specializing in Anodic protection for acid coolers, piping and storage tanks • Anodically protected shell and tube sulphuric acid coolers with innovative technology • Open concept PLC-controlled Anodic protection systems with non-proprietary components used for acid coolers, storage tanks, and stainless steel piping • Supplying of spare parts, refurbished equipment and an inventory of rescue units of Anodic protection equipment • Inspection of acid coolers, storage tanks and piping, combined with our Eddy Current Testing for Complete Turnkey Turnaround Crew Services • Inspection and servicing of Anodic protection equipment • Consultation, classroom training and troubleshooting • Over 50 years of combined experience in the H2SO4 industry

Phone: 416.444.4880 Fax: 416.261.2106 Email: admin@mercad.com Web: www.mercad.com

H2So4Ad-Sept2012.indd 1

Sulfuric Acid Today • Fall/Winter 2015

26/09/12 4:11 PM

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D eFpe tu m Faa erta tr uern et

PFA Teflon®-lined butterfly valves eliminate the need for spray shields, allow for easy automated operation

Feature

Successful filtration by improved pumping systems By: Jan Hermans, Sulphurnet-Liquid Sulphur Processing, and George Georgiev, Weir Minerals Lewis Pumps-Liquid Sulphur Pumps

Successful sulfur filtration in a sulfur burner plant begins with understanding the process. Sulfur purification is an important step within the sulfur burner plant.

The quality of the sulfur is important to ensure a useful lifespan of the catalyst bed. In achieving this useful life, the filtration step becomes critical to the overall process. A liquid sulfur filter requires a driving force to create a flow that can overcome the resistance built up in the filter. The driving force is provided by the liquid sulfur pump.

In the sulfur pumping system, the objective is to transfer the liquid sulfur from a dirty sulfur pit or tank via the filter system, to a required final destination, e.g. a clean liquid sulfur storage tank or pumping pit.

The required flow rate is equal to the driving force divided by the resistance.

The driving force is the total pressure drop required

to achieve a liquid flow. The resistance is an addition of various energy losses in the system.

The head loss is made up of three parts:

PAGE 46

George Georgiev

Fig. 2: Typical pump performance curve indicating head verses flow.

the predicted condition is valid for only a short period of time. In filtration, the pressure differential (dP) over the filter varies. Initially, the dP will be low, but it will increase as the filter cake is formed. The dP will reach the predicted flow, but, due to the increasing cake resistance, remains only for a very short period at this point. In the field, the filtration process continues until the maximum head pressure is reached. At this point, the flow is reduced to a minimum.

This is illustrated in Fig. 3 where the red arrow shows the flow changes with increasing resistance.

The initial flow rate is shown by the purple arrow which represents the minimum head pressure. As the filter cake increases, the resistance of the system increases. The red arrow displays the flow vs. head pressure over time.

The blue arrow represents where the filtration process has stopped at the point where the maximum pump head pressure is achieved. The design or predicted flow rate will be valid only for a very short time (green arrow).

How do these dynamics affect the system? The pump performance curve in Fig. 4 provides details relating to pressure drop, energy consumption and pump efficiency.

Fig. 4 shows the curves for the various parameters.

The system is designed for a flow rate of 25 m3/hr and head pressure of 44.5 meters water column. The 44.5 meters is the sum of the static head, friction head and the head losses through the filter. The system designer will select a rated flow and head required for the pumps used

Fig. 1: Illustration of head losses.

1. Static pressure: The elevation of the filter system. This is a constant value.

2. Pressure differential of the filter: Losses caused by the resistance of the filter cake. It is variable through the filtration process.

3. Friction head (or dynamic head loss): The friction loss that occurs in pipe flow due to viscous effects generated by the surface of the pipe. This is a constant value.

Head loss can be expressed by the pump performance curve shown in Fig. 2.

In the Fig. 2 curve, the pump design flow and the predicted flow are represented by the green lines. However, in a liquid sulfur filtration process using a centrifugal pump,

Jan Hermans

Fig. 3: Curve showing increasing resistance through the system.

Fig. 4: Pump performance curve.

in the system based on a certain head loss through the filter. When the pump is operated and the filter is new, the head loss through the filter is low. The pump will run out on its performance curve to a flow rate corresponding to the resistance head of the system. As the filter cake grows and the resistance head in the filter increases, the pump moves back toward the left side of its performance curve and the flow decreases with the increase in the system head required. This will continue until the flow of the pump is reduced to a certain pre-determined rate that corresponds to an increase in the resistance head through the filter where cleaning is then required.

The pumps are not being â&#x20AC;&#x153;runâ&#x20AC;? in the design condition; therefore the system is not working very efficiently.

The curve represented in Fig. 4 confirms that the pump is sized for a predicted flow which is only present for a very short time. The pump is running out of range, which is a principle of over sizing. This leads not only to a waste of energy consumption, but also lends to possible damage of internal parts of the pump. Another issue that arises when the pump is running out of range is that the cake formation is affected, which can lead to valuable sulfur remaining in the filter cake and foreign particles passing through the filter.

An optimization of the filtration process can be achieved by altering the process set-up. Improvements can be made by selecting a method of flow control for the centrifugal pumps. Flow control by speed regulation of pumps is one of the best methods of varying the output of centrifugal pumps. This can be done with a variable frequency drive (VFD).

Fig. 5 indicates that the flow can be the same as the pressure changes by using a VFD. In the example, a flow of 25 m3/hr can be maintained when changing the speed to 1750, 1650 or 1550 RPM.

When using a VFD, the flow can be measured downstream of the pump and feedback given to the DCS system that adjusts the motor frequency. In this way, the pump starts to act more like a positive displacement pump, as shown in Fig. 6.

Sulfuric Acid Today â&#x20AC;˘ Fall/Winter 2015

Fig. 5: Pump performance & resistance curves at different speeds.

The pump provides a constant flow over the entire filtration cycle. Increasing cake thickness adds resistance to the system and increases the rotation speed of the impeller, providing a constant flow.

This system not only changes the energy consumption, but it also has a positive contribution on the output of the liquid sulfur filter system. Due to the constant flow, the by-pass of particles is reduced, providing a longer operation time of the catalyst. In addition, the produced filter cake holds lower sulfur content. Calculations show that an annual savings of $200,000 can be achieved for a 500 million ton per day sulfur melting facility (assuming

Sulfuric Acid Today â&#x20AC;˘ Fall/Winter 2015

sulfur prices of $100/ton).

Procurement cost relating to the pump systems are a small amount of the total investment of a sulfur melting plant. The quality of a pump system is a decisive factor in the overall functionality of the filtration process plant and the associated running costs. Flow control by speed regulation of the pumps is todayâ&#x20AC;&#x2122;s best method for varying the output of the liquid sulfur filtration process. Some of the benefits gained by controlling the flow include: energy cost savings, reliability improvements, reduced maintenance, less loss of sulfur in filter cake, and longer life of the catalyst bed in the convertor.

When selecting a centrifugal pump for filter sulfur service, the pump manufacturer will determine the non-

â&#x20AC;&#x201A; PAGE 47

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Fig. 6: Flow pattern: using a VSD-driven centrifugal pump.

overloading power required by the pump as shown by the performance curve. A motor power rating is selected that exceeds this value plus some additional power to cover any process upsets. This means that the motors are sized correctly to cover the right side of the curve when the power requirements are high. When the resistance head increases and the pump moves back toward the left side of the curve, the power the pump requires decreases, leading to greater inefficiencies in the operating system.

By using a VFD to control the operating speed of a motor, the flow generated by the pump can be controlled.

The Affinity Laws for centrifugal pumps will apply to the changes in operating speeds. The flow will vary directly with the change in speed, the head will increase as a square of the speed change and power required by the pump will change as a cube of the speed change. For example, by increasing the speed of the pump-motor unit by 2 percent, the flow will increase 2 percent, the head being generated will increase by 4 percent and the power required will increase by 8 percent. Changing the running speed of a centrifugal pump produces a constant flow rate while increasing the head produced by the pumps. The pump is able to overcome the changes in the resistance head of the sulfur filter and is also able to overcome the head required for the rest of the system. The motor must be sized correctly to handle the power requirements of the pumps and must be rated for use with a VFD.

For more information, contact Jan Hermans at jan@ sulphurnet.com or George Georgiev at george.georgiev@ weirminerals.com. q

Department

CONFERENCE REVIEW

SYMPHOS 2015 draws industry experts world wide

The last two SYMPHOS events, held in 2011 and 2013, proved so valuable that the Office Cherifen des Phosphates (OCP Group) hosted its conference for a third time this year. The 2015 edition of SYMPHOS, which stands for International Symposium on Innovation and Technology in the Phosphate Industry, took place May 18-20 in Marrakesh, Morocco.

OCP Group, one of the world’s largest phosphate producers, organized over 150 presentations that delved into new technologies and developed technological innovations. The nearly 1,500 professionals in attendance represented multiple industry interests including: the mining industry, phosphates beneficiation, chemical processing, sulfur and sulfuric acid production, am-

Soufiyane El Kassi of OCP and SYMPHOS Steering Committee member welcomed participants to the 2015 SYMPHOS in Marrakesh, Morocco.

Robert Tucker, president of Innovation Resource, gave a keynote presentation on the topic of innovation for the 2015 SYMPHOS in Marrakech, Morocco.

monia, fertilizers, biotechnology, phosphate materials and corrosion protection systems, food safety issues and environmental stakes related to industrial exploitation and development of innovative processes.

Welcoming participants to the conference was SYMPHOS Steering Committee member Soufiyane El Kassi of OCP. The opening ceremony was kicked off with a presentation about innovation in the industry given by Robert Tucker, president of Innovation Resource.

The sulfuric acid session was moderated by Iliass Elfali, OCP’s director of the Safi Site and Thierry Marin of DuPont. Presentations at the sulfuric acid session included: —“New sulfur melting technology installed in Kazakhstan and the USA,” by Mark Gilbreath, Devco, USA. —“Revamp and upgrade possibilities in sulphuric acid plants,” by Jan Albrecht, Outotec GmbH & Co. KG, Germany.

—“Latest developments on DuPont MECS® sulphuric acid catalyst,” by Tom Brouwers,

EMEA Product Manager, Sulphuric Acid Plants and Catalysts, MECS, Belgium.

—“Effect of inferior and aging catalyst,”

by Casper Vittrup Frandsen, Haldor Topsøe A/S, Denmark.

—“Convertible lump sum EPS contracting model—How to get the plant you need now and still enjoy it in 20 years,” by Michael Fenton, Senior Business Development Manager, Chemetics Inc., Canada.

—“Process heat recovery and digitalization in sulphuric acid plants,” by Michael Kemmerich, Outotec GmbH & Co. KG, Germany.

—“Commercialization of MECS® SolvR™ regenerative SO2 recovery technology,” by

Members from DuPont Sustainable Solutions enjoyed the gala dinner at this year’s SYMPHOS in Marrakech, Morocco. Pictured, from left, are Ken Kershaw, Garrett Palmquist, Pascal Du Bois d’Enghien, Giovanni Marchesi, Thierry Marin, André Kotlarevsky, Richard Martinez, Youssef Riahi, Tom Brouwers, and Patrick Speltincx.

Garret Palmquist, Business Development Manager, MECS, Belgium.

—“Increasing production capacity through sustainable cleaning,” by Henning Urch, BASF SE, Formulation Technologies, Germany.

The attendees of SYMPHOS 2015 were also treated to a gala dinner consisting of local food and entertainment from bands, singers and dancers.

For more information, please visit the event’s website, www.symphos.com. q

The sulfuric acid session at 2015 SYMPHOS consisted of topics such as catalyst, innovations in technology, capital improvement, sulfur melting technology, process heat recovery and SO2 recovery technology. Pictured from left are Garrett Palmquist of DuPont, Iliass Elfali of OCP, Tom Brouwers of DuPont, Casper Vittrup Frandsen of Haldor Topsøe A/S, Michael Fenton of Chemetics, Jan Albrecht of Outotec and Thierry Marin of DuPont.

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Innovative solutions for your Sulphuric Acid Plant needs Chemetics Inc.

Chemetics Inc.

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Chemetics Inc., a Jacobs company

(headquarters) Vancouver, British Columbia, Canada Tel: +1.604.734.1200 Fax: +1.604.734.0340 email: chemetics.info@jacobs.com

PAGE 48

(fabrication facility) Pickering, Ontario, Canada Tel: +1.905.619.5200 Fax: +1.905.619.5345 email: chemetics.equipment@jacobs.com

Sulfuric Acid Today • Fall/Winter 2015

Department

CONFERENCE REVIEW

Phosphate fertilizer, sulfuric acid professionals gather for annual conference

Each year for the last 38 years, members of the AIChE Central Florida Section and colleagues from around the world have gathered at Clearwater Beach, Fla., to share their ideas concerning chemical process technology, specifically the production of phosphoric acid, phosphate fertilizers and sulfuric acid. The 39th International Phosphate Fertilizer & Sulfuric Acid Technology Conference took place June 5-6 at the Sheraton Sand Key Resort.

As part of the conference, this year’s 18th annual Sulfuric Acid Workshop, chaired by Rick Davis of Davis & Associates Consulting and Jim Dougherty of Mosaic, reviewed various aspects of turnaround planning. Davis and Dougherty shared their knowledge and experience on this topic with attendees. Other workshop presentations included: —“The best data wins,” by Dan Freeman of SNC Lavalin.

—“Turnaround planning requires a team effort,” by Rick Davis of Davis & Associates.

—“Mosaic’s turnaround procedures,” by Bryan Dhue of Mosaic Co. —“Keys to successful turnaround planning,” by Ian Legg of Central Maintenance & Welding.

—“Turnaround waste strategy,” by Ann Wortman of Mosaic Co.

On Saturday, attendees chose between two parallel sessions focusing on issues related to the phosphate technology and sulfuric acid industries. Topics covered in the sulfuric acid session included: —“How to buy a vessel,” presented by Kevin Lambrych of Ashland.

—“Strategies for reducing start-up emis-

The 18th annual Sulfuric Acid Workshop gathered professionals from around the world to review various aspects of turnaround planning.

Chuck Munro of Spraying Systems Co. presented his paper, “Understanding spray technology to optimize sulfur burning,” during the sulfuric acid session of the 2015 AIChE Clearwater Conference.

Sulfuric Acid Today • Fall/Winter 2015

sions from sulfuric acid plants,” presented by Kim Nikolaisen, Andres MahechaBotero and Guy Cooper of NORAM Engineering & Constructors Ltd..

—“From nano-scale studies of the working sulfuric acid catalysts to improved industrial scale sulfuric acid production,” presented by Kurt Christensen, Filippo Cavalca, Pablo Beato and Stig Helveg of Haldor Topsøe A/S. —“Best practices for specifying and purchasing composite piping systems,” presented by Kira Townsend of RPS Composites, Inc. —“Hydrogen incidents: Why now—what can we do?” presented by Leonard J. Friedman of Acid Engineering & Consulting, Inc. —“Small project optimization in sulfuric acid plants: Achieving the best ROI,” presented by Kirk Bailey of MECS/DuPont.

—“Shell & tube strong sulphuric acid coolers,” presented by Frans Kudeda of OUTOTEC-Edmeston Product Center.

—“Understanding spray technology to optimize sulfur burning,” presented by Chuck Munro of Spraying Systems Co. As usual, the Clearwater Conference was about more than just presentations.

Hospitality suites and dinners provided ample time for casual networking, while attendees’ family’s enjoyed a breakfast for spouses sponsored by Engineers’ Wives Club of Polk County and a fun-filled children’s science party conducted by The Museum of Science and Industry.

Dates for the 2016 conference have been set for June 10-11, 2016. For more information, visit the event’s website at www. aiche-cf.org. q

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Rick Davis of Davis & Associates Consulting co-chaired the Sulfuric Acid Workshop.

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Presenters for the Sulfuric Acid Workshop delved into the various aspects of turnaround planning. Pictured are, from left, Ann Wortman of Mosaic Co., Ian Legg of Central Maintenance & Welding, Dan Freeman of SNC Lavalin, Bryan Dhue of Mosaic Co. and Rick Davis of Davis & Associates Consulting.

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Department

CONFERENCE REVIEW

Sulfuric Acid Today hosts Sulfuric Acid Roundtable in Central Florida For more than two decades, the Sulfuric Acid Roundtable has provided a forum for professionals in the industry to share knowledge and gain inspiration. This year’s conference, which took place over two-and-a-half days in March, was no different. It offered participants the same focus on industry issues that was provided at the first conference back in 1991, also in Central Florida.

The Streamsong Resort in Bowling Green, Fla., provided the venue this year, and approximately 180 attendees took part in technical presentations and panel discussions relating to pertinent industry issues.

The conference attracted representatives from 30 sulfuric acid producing companies working in sulfuric acid, acid regeneration, metallurgical and phosphate. Also participating were representatives from approximately 28 company suppliers that provide equipment and services to the industry. These supplying companies co-sponsor and co-host the roundtable together with Sulfuric Acid Today magazine.

Industry topics were explored via presentations from supplying companies as well as panel discussions that included producing plant presentations on topics that coincided with the panel topic. Participants were also able to peruse some 22 display booths detailing supplier products and services.

Outside of the conference room, attendees enjoyed a variety of activities where they could relax and enjoy the venue.

Among the first day’s offerings were a golf tournament, a bass fishing tournament and clay skeet shooting. That evening, guests were treated to a welcome Cajun dinner prepared onsite by VIP International and sponsored by VIP International and Weir Minerals Lewis Pumps Other evening activities included a Casino night with dinner with door prizes.

Participants were given the option to cash in tickets for chances to win door prizes that were generously donated by the conference co-sponsors.

On the final day of the conference, participants took a bus tour of Mosaic’s New Wales Plant. At the close of the event, Sulfuric Acid Today publisher Kathy Hayward recognized co-sponsors with an award for their participation.

Presentations

During the roundtable, company suppliers to the sulfuric acid industry gave the following presentations: —Keynote Address: “Outlook for the global and North American sulfuric acid markets,”

by Fiona Boyd of Argus Media.

—“Small project optimization: Achieving the best ROI,” by Ron Cloud of DuPont/ MECS. —“Digitalization in sulfuric acid plants– PAGE 50

Attendees of the 2015 Sulfuric Acid Roundtable enjoyed recreational activities on the first day of the event. This group participated in a bass fishing tournament. Anglers are, left to right, Blaine Sandberg of Frisch Engineered Products Inc., Howard Tenney of Tenney & Co., Bill Choate of J.R. Simplot, Steve Metzger of J.R. Simplot, Kirk Bailey of DuPont MECS, Don Harcus of J.R. Simplot, David Collins of Southern Co., Roland Guenther of Steuler-KCH GmbH, Dan Belland of Agrium-Redwater and Jim Washburn.

Over 180 professionals attended the 2015 Sulfuric Acid Roundtable at the Streamsong Resort in Central Florida.

Fiona Boyd of Argus Media kicked off the meeting with her keynote presentation about the global sulfuric acid market.

New to this year’s roundtable was a bus tour of Mosaic’s New Wales Plant, which consists of five sulfuric acid plants and is located only 20 miles from the Streamsong Resort.

Integral to the Sulfuric Acid Roundtable are producing plant discussions and presentations concerning maintenance. Chris Cancilla, right, shares his company’s experience with materials of construction for the gas cooling tower. Other panelists are, from left, Rakesh Panchal of Agrium-Redwater, Don Janezic of DuPont and Peter Morenc of Eco Services.

Carl Kamme of Opsis.

—“Hydrogen incidents–Why now and what can we do,” by Len Friedman of Acid Engineering & Consulting.

—“Mosaic New Wales facility overview,”

by Jim Dougherty of Mosaic.

Panel discussions Participants to the 2015 Sulfuric Acid Roundtable were able to peruse booths during the two-and-a-half day event. Pictured are Robert Maciel of Chemetics, left, and Cliff Harrison of AREVA Resources Canada.

chances & opportunities,” by Stefan Brauner of Outotec.

—“Maximize your maintenance outage for a longer production campaign,” by Jack Harris of VIP International.

—“The design parameters for sulfuric acid plant equipment,” by John Orlando of NORAM Engineering & Constructors.

—“Understanding your anodic protection system,” by Michael Kursin of Chemetics.

—“Installation of a ZeCor™ acid cooler,”

by Will White of Potash Corp of Aurora.

—“Take control: Optimize main blower performance in sulfuric acid plants,” by Jacque Schultz of Siemens.

—“Aspects of sulfuric acid mist precipitator design, materials and maintenance,” by

Co-sponsors of the event prepared informative presentations for participants.

Jack Harris of VIP International shared some video of his company’s findings from equipment inspections.

Michael Beltran of Beltran Technologies.

—“HRS power generation carries mosaic New Wales into the 21st Century,” by Jim Dougherty of Mosaic and Tim Loete of MECS. —“Repairing brick lined absorption tower using injection materials,” by Matthias Walschburger of Koch Knight LLC. —“Catalyst management, monitoring and troubleshooting to ensure maximum performance,” by Patrick Polk of Haldor Topsøe.

—“Performance criteria for optimizing sulfur gun operation,” by Chuck Munro of Spraying Systems —“Optical systems for continuous measurements of gases in industrial processes,” by

Topics explored during producing plant panel discussions were: —Weak and strong acid pumps and sulfur pumps.

—Heat exchangers.

—Acid towers (packing, mist elimination, distributors, pressure drop, mist carryover and replacement).

—Converter (replacement, maintenance and catalyst screening and disposal).

—Steam systems (boilers, economizers and superheaters) —Rotating equipment (blowers, compressors, balancing, vibration analysis and predictive maintenance) —Acid resistant linings, bricks, mortars, furnace refractory and sulfur pit maintenance.

—Safety issues and incident reviews.

—On-line condition monitoring, on-line corrosion monitoring, and on-line gas leak repairs.

For more information regarding the 2017 Sulfuric Acid Roundtable, visit the event’s website at www.h2so4today.com. q Sulfuric Acid Today • Fall/Winter 2015

Department

CONFERENCE REVIEW

DuPont, MECS hosts Best Practices Workshops Once again, DuPont Sustainable Solutions Clean Technologies hosted its annual Best Practices Workshop, which consisted of two concurrent events: the STRATCO® Alkylation Technology Workshop and the MECS® Sulfuric Acid Regeneration (SAR) Technology Workshop. The event was held at the elegant Château Élan Winery and Resort in Braselton, Ga., from September 13-18, 2015.

The combined workshops drew over 145 participants worldwide for focused learning, information sharing and networking. Attendees represented multiple work disciplines, including operations personnel, process and mechanical engineers, engineering supervisors and technology specialists.

The MECS® SAR Technology Workshop attracted over 60 participants, which included 14 operating companies and 17 plant sites from various countries including China, Japan, Korea, Thailand, the United Kingdom and the United States.

Attendees delved into a range of topics during the many interactive presentations, including: SAR process overview; SAR plant start-up; NOx and niter in sulfuric acid plant operation; SAR and alkylation interactions; sulfuric acid safety; sulfuric acid storage tanks; decomposition furnace—best practices for operation and maintenance; instrumentation; understanding and mitigating hydrogen formation; mist eliminators—operation, maintenance and troubleshooting; gas cleaning systems—best practices for operations and maintenance; plant operational analysis; converter systems; and strong acid systems.

Mini-tech talks were also offered during this year’s workshop. Topics included: acid pumps—design theory, operating parameters and maintenance best practices; acid coolers and plant heat exchangers; and a mechanical maintenance demonstration—gasket performance at elevated temperatures.

Outside of scheduled presentation time, attendees were able to engage with multiple exhibitors displaying products such as gaskets, pumps, checkerwalls, an operator training stimulator and process critical equipment.

The MECS® Operator Training Simulator (OTS) was a big draw, as participants could play out authentic scenarios of a sulfuric acid plant. During the simulation, participants were given the opportunity to first familiarize themselves with the plant layout, and then presented with three hazard scenarios to recognize, verify and troubleshoot. Specifically, they were asked to identify a furnace oxygen analyzer failure, a HIP leak and oleum in the IPAT.

Attendees could also explore the MECS® LMS (Learning Management System), which was a test of sulfuric acid knowledge spanning beginner concepts to more advanced topics. With good humor and a touch of friendly competition, attendees answered 20 questions about sulfuric acid plants and were graded on their responses.

Taking a respite from business activities, Sulfuric Acid Today • Fall/Winter 2015

attendees enjoyed some relaxation time where they could take in the venue and network with peers. These events included evening dinners, rounds of golf and a tour of the Château Élan Winery. q

X

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Bruce Garrett, left, and Kirk Bailey of MECS Inc. welcome participants to the 2015 MECS® Sulfuric Acid Regeneration Technology Workshop at Château Élan in Braselton, Ga.

ACRIS PFA lined butterfly valve Spouses attending the 2015 MECS® Sulfuric Acid Regeneration Technology Workshop were able to participate in a wine blending challenge at the Château Élan Winery. Enjoying the fruits of their labor are, from left, Darwin Passman of VIP International, Donna Passman, Jack Harris and Becky Harris of VIP International, Rick Ullrich of DuPont, Suzanne Ullrich, Scott Hogenmiller of W.L. Gore & Associates, Diane Hogenmiller, Mick Cooke of Weir Minerals Lewis Pumps and Carol Cooke.

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Brian Lamb of MECS Inc., top, monitors a participant’s choices during the Operator Training Simulator challenge.

Walter Weiss of DuPont MECS Inc. facilitates the decomposition furnace segment of the workshop. The presentation covered the best practices for operation and maintenance.

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PAGE 51

Faces & Places

Members of DuPont Sustainable Solutions toured Marrakech’s Medina during the SYMPHOS 2015 conference. Pictured in the front row, from left, are Patrick Speltincx, Yacine Salihy and Garrett Palmquist; second row: Giovanni Marchesi, Pascal Du Bois d’Enghien and Ken Kershaw; third row: Youssef Riahi, Thierry Marin and Richard Martinez.

Guille McCreary of Mosaic Co., left, proudly displays the door prize she won from Michael Beltran of Beltran Technologies at the 2015 Sulfuric Acid Roundtable at the Streamsong Resort in Central Florida.

El Dorado Chemical participated in the 2015 Sulfuric Acid Roundtable in Central Florida. Pictured, from left, are Jason Arnold, Shane Gibbons and Bob McKinney.

Visiting in DuPont MECS’ booth at the 2015 Sulfuric Acid Roundtable at the Streamsong Resort in Central Florida, are, from left, Owen Masters of Feryl Inc., John Horne of MECS, Charlie Fast of Mosaic Co. and Jonathan Meyer of PotashCorp.

Enjoying the evening at the Weir Minerals Lewis Pumps’ annual dinner at Crabby Bills, held in conjunction with the AIChE Clearwater Conference, are, from left, Collin Bartlett of Outotec, Michael Fenton of Chemetics and Hannes Storch of Outotec.

Rene Dijkstra of Chemetics, right, presents his company’s door prize to Chris Pearson of Mosaic Co. at the 2015 Sulfuric Acid Roundtable at the Streamsong Resort in Central Florida.

David Bailey of CMW, left, congratulates Eric Hermelbracht of Mosaic Co. for winning CMW’s door prize at the 2015 Sulfuric Acid Roundtable at the Streamsong Resort in Central Florida.

Ed Knoll of Acid Piping Technology, left, visits with Doug Strait of W.L. Gore in Gore’s booth during the 2015 Sulfuric Acid Roundtable at the Streamsong Resort in Central Florida.

Enjoying the Gala Dinner held in conjunction with SYMPHOS 2015 in Marrakech, Morocco, are, from left, Younes Hanine and Ahmed Hanine of Mazagan Industrial Consulting.

Jacque Shultz, right, presented Daryl Platz of Wisconsin Public Service with Siemens’ door prize at the 2015 Sulfuric Acid Roundtable in Central Florida.

Enjoying a dinner held at the Streamsong Clubhouse in conjunction with the 2015 Sulfuric Acid Roundtable, are, from left, Dan Hill of Teck Resources, Hoss Maddry of VIP International and Ann Maddry.

Enjoying the DuPont MECS hospitality suite during the 2015 AIChE Clearwater Conference, are, from left, Howard Tenney of Tenney & Co., Mike Wittie of Martin Resources and Steve Ziebold of DuPont MECS.

The 2015 Sulfuric Acid Roundtable included 28 companies that helped to sponsor the event. Sulfuric Acid Today presented each with an award for their participation and dedication to the sulfuric acid industry. Co-sponsoring companies for the event included: Acid Engineering & Consulting, Acid Piping Technology, Advance Products & Systems, Andronaco Industries, Beltran Technologies, Central Maintenance & Welding, Chattanooga Boiler & Tank, Chemetics, Conco Industrial Services, DuPont MECS, FLEXIM, Haldor Topsøe, Kimre, Koch Knight, Magneco/Metrel, Mercad Equipment, NORAM Engineering & Constructors, OPSIS, Outotec, Powel Fabrication & Manufacturing, Siemens Energy, Spraying Systems, STEULER-KCH, Roberts Company, Turbine Diagnostic Services, VIP International, Weir Minerals Lewis Pumps and W.L. Gore Sealants.

Catching up with one another at the 2015 AIChE Clearwater Conference in Clearwater, Fla., are, from left, Rick Davis of Davis & Associates Consulting, Nelson Clark of Clark Solutions and George Wang of Eco Services.

Faces & Places

Jim Dougherty, left, and Bill Merritt, both of Mosaic Co., enjoyed catching up with one another at the Streamsong Clubhouse during the 2015 Sulfuric Acid Roundtable.

Kirk Bailey of DuPont MECS, right, visits with Cornerstone Chemical Co. attendees Russ DuRocher, left, and Jose Rivera, center, at the 2015 MECS® Sulfuric Acid Regeneration Technology Workshop at Château Élan in Braselton, Ga.

Kimre hosted a hospitality suite in conjunction with the 2015 AIChE Clearwater Conference in Clearwater, Fla. Pictured in their company’s booth, are, from left, Robert Klinewski, Mary Keenan, Stephanie Gornail, Noel Booker, Linda Kravitz and Frank Power.

Members of Weir Mineral Lewis Pumps presented their door prize to Mark Ibsen of Rentech Nitrogen, center. Also pictured are, from left, Dolon Silimon, Ken Black, Ricky Jaswal and Mick Cooke.

Eid Dahdal of Tampa Electric, center, visits with Matt Thayer, left, and Matthias Walschburger, both of Koch-Knight, in their booth at the 2015 Sulfuric Acid Roundtable in Central Florida.

Patrick Polk of Haldor Topsøe, left, presented David Simmons of FreeportMcMoRan his company’s door prize at the 2015 Sulfuric Acid Roundtable in Central Florida.

Participants from Mosaic’s Florida operations enjoyed the Cajun Dinner at the 2015 Sulfuric Acid Roundtable at the Streamsong Resort. Pictured are, from left, Chris Pearson, Gary Kundinger, Vance Singletary, Keith Willis and Eric Hermelbracht.

DuPont MECS hosted a family night dinner in conjunction with the 2015 AIChE Clearwater Conference. Pictured are the family members of Rick Davis of Davis & Associates Consulting.

Front row, from left: Marisa Davis, Josiah Davis and Melina Davis; second row: Stefanie Davis, Tara Davis and Charlotte Davis; third row, Rick Davis, Ariana Davis, Chris Davis, Rick Davis and Jordan Davis.

Enjoying the evening at the Weir Minerals Lewis Pumps’ annual dinner at Crabby Bills, held in conjunction with the AIChE Clearwater Conference, are, from left, Skip Unger of Acid Piping Technology, Margie Unger, Robbie Hutcheson and Steve (Hutch) Hutcheson of Mid-State Machine and Fabricating.

VIP International and Weir Minerals Lewis Pumps hosted the Cajun Dinner at the 2015 Sulfuric Acid Roundtable at the Streamsong Resort. Stan Miller of VIP International, left, dishes out some delicious jambalaya that was prepared on-site by VIP International.

Enjoying the Cajun Dinner at the 2015 Sulfuric Acid Roundtable at the Streamsong Resort are, from left, Guy Cooper of NORAM Engineering & Constructors, Don Harcus of J.R. Simplot and Steve Metzger of J.R. Simplot.

Participants from Chemtrade visited the STEULER-KCH booth during the hospitality social at the 2015 Sulfuric Acid Roundtable at the Streamsong Resort. Pictured, from left, are Brett Edwards of Chemtrade, Roland Gunther of STEULER, Roger Allison of Chemtrade, Mattias Born of STEULER and Lane Benford of Chemtrade.

Enjoying the welcome Cajun Dinner at the 2015 Sulfuric Acid Roundtable in Central Florida are, from left, Jim Gosney of Lucite International, George Froats, Dean Williams and Mark Konecheck, all of Langeloth Metallurgical and Doug Strait of W.L. Gore Sealants.

Department

CALENDAR OF EVENTS planned for attendees and their families.

For more information or to register, please visit www.aiche-cf.org.

Plans underway for Australasia sulfuric acid workshop

COVINGTON, La.—Sulfuric Acid Today is hosting its eighth biennial Australasia Sulfuric Acid Workshop, which will take place April 4-7, 2016. It will be held at The Ville Resort in Townsville, Queensland, Australia.

The 2014 Workshop attracted more than 70 participants from around the world, and 2016 is shaping up to be an even bigger event. As in years past, sulfuric acid insiders will gather to attend presentations given by event co-sponsors on a variety of topics relevant to the industry.

Panel discussions and co-sponsor booths will provide more opportunities for information sharing, and social events will ensure that participants get to enjoy the beautiful area while building relationships that promote beneficial business exchanges in the future. This year’s workshop is offering an off-shore fishing tournament near Shark Shoal, which is one of the largest shoal patches in the area. The workshop will also offer a bus tour of the Sun Metals Zinc Refinery, located 15 km south of the city of Townsville.

The Australasia Sulfuric Acid Workshop is offered in even years in Australia and alternates with the Sulfuric Acid

Paris will host Phosphates 2016

The Sulfuric Acid Workshop will be held at The Ville Resort in Townsville, Queensland, Australia, April 4-7, 2016.

Roundtable, which is offered in odd years in the United States.

For more information, please visit www.h2so4today.com or email kathy@ h2so4today.com.

slated for June 10-11, 2016.

This year, there will be two sessions on Friday afternoon. The first will be a sulfuric acid session, chaired by Rick Davis of Davis & Associates Consulting, Inc. and Jim Dougherty of Mosaic Co. The second session will be a workshop on Florida PE Laws and Rules. PDH certification is available for participants who attend the full session, supply their P.E. number on or before June 10, 2016, and have attendance verified by proctors.

In addition to its technical sessions, the Clearwater conference is known for the beautiful Sand Key backdrop, good food, ample social time with family and colleagues and a lot of fun. This year should be no different, with a variety of activities

AIChE Clearwater Conference slated for June

CLEARWATER, Fla.—For each of the last 39 years, members of the AIChE Central Florida Section and colleagues from all over the world have gathered at Clearwater Beach to share their ideas concerning chemical process technology, specifically the production of phosphoric acid, phosphate fertilizers and sulfuric acid. This year’s conference is

2016

Australasia H SO W O R K S H O P 2

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S U L F U R I C A C I D T O D AY

The Ville Resort - Casino April 4-7, 2016

LONDON–CRU is delighted to host the ninth Phosphates International Conference and Exhibition, the premier annual event for the fertilizer, food and industrial phosphates market. Scheduled for March 1315, 2016 at Marriott Rive Gauche in Paris, France, the event is sure to attract industry decision makers from around the world.

With over 420 participants from 36 countries attending the Tampa event in 2015, the conference continues to be the ideal forum for senior decision makers from all elements of the phosphates industry to learn which market and technology factors will influence the industry. Phosphates 2016 will provide delegates with key insights and in-depth market information about raw materials, intermediates and finished products.

Don’t miss this essential industry event, providing producers, traders, consumers and technology/equipment providers with an annual meeting point to network, negotiate business contracts and share industry knowledge.

For more information or to register, please visit www.crugroup.com. q

2016 Aus trala Worksho sia Sulfuric Acid p will off er: — Global s u

lf 2015 and uric acid market revie w of outlook for — Informa tive Co-Spo 2016 nsor prese — Insightfu nta l — Mainten producing plant pres tions an c e p an e l entations dis — Safety p anel and in cussions cident revie — Co-Spon ws s — Network or exhibits ing opportu nities

Townsville, Queensland Australia Sponsored By:

Sulfuric Acid T

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Industry’s Premier Event for Networking & Sharing Best Practices™ Register On-Line Today! www.acidworkshop.com PAGE 54

Sulfuric Acid Today • Fall/Winter 2015

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