Fall/Winter 2023 by Sulfuric Acid Today

COVERING BEST PRACTICES FOR THE INDUSTRY

Sulfuric Acid T

w w w. H 2 S 0 4 To d a y.co m

F a l l / W i n te r 2 0 2 3

Sulfuric acid production at farmer-owned Ravensdown PAGE 7

IN THIS ISSUE > > > > Market Outlook: The turning point in 3Q23 PAGE 10 Mosaic South Pierce upgrades decades-old drying tower PAGE 14 New CIRAMET PLUS™ for most challenging service: seawater acid coolers PAGE 34

YOUR PATHWAY TO A CLEANER FUTURE Driving sustainability and carbon neutrality, MECS specializes in sulfuric acid and environmental technology processes for non-ferrous metal, fertilizer and chemical industries. As a world leader in optimized solutions for carbonless energy generation, smelter air pollution control, oleum & sulfur trioxide production for e-grade acid in support of semiconductor manufacturing, high-efficiency mist elimination for green hydrogen processes, and much more, we are on the leading edge of technology advances for a cleaner tomorrow. Contact our experts today.

MECS.ElessentCT.com

Sulfuric Acid

COVERING BEST PRACTICES FOR THE INDUSTRY

Sulfuric Acid T

w w w. H 2 S 0 4 To d a y.co m

F a l l / W i n te r 2 0 2 3

Sulfuric acid production at farmer-owned Ravensdown PAGE 7

Vol. 29 No. 2

Covering Best Practices for the Industry

Fall/Winter 2023

IN THIS ISSUE > > > > Market Outlook: The turning point in 3Q23 PAGE 10 Mosaic South Pierce upgrades decades-old drying tower PAGE 14

FROM THE PUBLISHER

New CIRAMET PLUS™ for most challenging service: seawater acid coolers PAGE 34

On the Cover… Ravensdown, a leading fertilizer 7 manufacturer in New Zealand, shares its rich history and expertise to help farmers reduce environmental impacts and optimize value from the land. Departments 4 Industry Insights News items about the sulfuric acid and related industries 12 Safety Sector Sharing common safety concerns 18 Lessons Learned Case histories from the sulfuric acid industry 20 Contractors’ Corner Perspectives for fabrication, planning & scheduling 28 Product News Latest sulfuric acid technology

37 & 38 40

Welcome to the Fall/Winter 2023 issue of Sulfuric Acid

your plant should use expansion joints (page 30); Weir Lewis

the latest products and technology for those in the industry,

lic vibrations in vertical chemical pumps (page 32); Chemetics

Today magazine. We have dedicated ourselves to covering and hope you find this issue both helpful and informative.

In this issue, we have several informative articles regard-

ing state-of-the-art technology and projects. Our cover story focuses on how Ravensdown uses its expertise and technology

to help farmers reduce environmental impacts and optimize value from the land (page 7); Acuity Commodities explains

SUBSCRIPTIONS U.S. Plant Personnel —‑Complimentary Subscribe Online: www.h2so4today.com

sulfuric acid coolers (page 34); Clark Solutions shares a case

history of a furnace gas backflow with sulfur (page 36); and Ramco provides simple, consistent safety solutions (page 37).

I would like to welcome our new and returning Sulfu-

on effect on other commodity markets, including sulfur

BASF, Beltran Technologies, Central Maintenance & Weld-

ing the global phosphate fertilizer market which had a knock-

and sulfuric acid (page 10); Mosaic recently replaced a 40-year-old brick lined drying tower at its South

Pierce facility in Mulberry, Fla. with a new MECS ZeCor®-Z drying tower (page 14); Hindustan Zinc

recently awarded Beltran Technologies the design,

engineering, and construction of four more wet elec-

trostatic precipitators (WESPs) for their sulfuric acid

Piping Technology Inc., Acuity Commodities, Alphatherm,

ing, CG Thermal, Chemetics, Christy Catalytics, Clark Solutions, Elessent MECS Technologies, INTEREP, Knight Mate-

rial Technologies, Lac-Mac GORE-TEX, Mercad, NORAM Engineering & Constructors, RAMCO, Southwest Refractory of Texas, Spraying Systems Co., STEULER-KCH, Sulphurnet, VIP International, and Weir Minerals Lewis Pumps.

We are currently compiling information for our Spring/

plants (page 16); CG Thermal shares how to minimize

Summer 2024 issue. If you have any suggestions for articles

design (page 22); NORAM shares the upgrades and

to contact me via email at kathy@h2so4today.com. I look for-

maintenance downtime with innovative exchanger

advancements to sulfuric acid equipment through the years (page 24); Christy Catalytics explains the advantages of ceramic support balls compared to quartz

or other information you would like included, please feel free ward to hearing from you. Sincerely,

Kathy Hayward

FEATURES & GUEST COLUMNS 10

The turning point in 3Q23

Mosaic South Pierce upgrades decades-old drying tower

Hindustan Zinc selects WESPs for downstream acid production

Minimize maintenance downtime with innovative design

Upgrades to sulfuric acid equipment: Advancements through the years

PROX-SVERS® vs quartz rock for sulfuric acid conversion reactor

Which expansion joint should you use: how to pay less attention to

–––––––––––––––––––––––––––––––

Mailing Address: P.O. Box 3502 Covington, LA 70434 Phone: (985) 807-3868 E-Mail: kathy@h2so4today.com www.h2so4today.com

the critical components of their anodically protected seawater

ric Acid Today advertisers and contributors, including: Acid

rock (page 26); INTEREP delves into when and where

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announces the CIRAMET® family of special steels for use in

that from July 2022 to July 2023, there was a lull overhang-

Conference Review Faces & Places

PUBLISHED BY Keystone Publishing L.L.C. ––––––––––––––––––––––––––––––– PUBLISHER Kathy Hayward ––––––––––––––––––––––––––––––– EDITOR April Kabbash ––––––––––––––––––––––––––––––– EDITOR April Smith ––––––––––––––––––––––––––––––– MARKETING ASSISTANT Tim Bowers ––––––––––––––––––––––––––––––– DESIGN & LAYOUT

Pumps explains common concerns of mechanical and hydrau-

your expansion joints 32

Mechanical and hydraulic vibrations in vertical chemical pumps

New CIRAMET PLUS™ for most challenging service: seawater acid coolers

Ramco provides simple, consistent safety solutions

Plant shutdown: sulfur burner backflow

Department

INDUSTRY INSIGHTS WASTE HEAT RECOVERY BOILERS SUPERHEATERS ECONOMIZERS

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PAGE 4

Chemetics awarded contract for sulfuric acid plant for the Nolans’ neodymium praseodymium project NORTH SYDNEY, Australia—Chemetics, the technology and solutions provider for sulfuric acid and other specialty chemical facilities of Worley, has been awarded a contract to install its CORE-SO2 sulfuric acid technology at Arafura Rare Earths Ltd.’s Nolans Project in Australia. Located 135 km north of Alice Springs in Australia’s Northern Territory, this greenfield mine will extract and process neodymium and praseodymium (NdPr). These rare earth elements are used to create ultra-strong permanent magnets for a range of applications, such as household electronics and high-performance motors for electric vehicles. This sulfuric acid plant will achieve significant sustainability improvements over similar capacity plants, thanks to its ability to idle while keeping the catalyst warm for extended periods of time, and high turnaround capability. It will be able to operate with 95 percent reduced sulfur dioxide (SO2) emissions, when compared to traditional double contact double absorption (DCDA) plants. The high-pressure steam production within the CORE-SO2 process will further reduce greenhouse gas emissions by enabling the generation of CO2-free electrical power. This will eliminate the need for a diesel or natural gas start-up burner. Additionally, CORE-SO2 is 60 percent smaller than traditional sulfuric acid plants, leading to significant construction advantages. The plant requires fewer pieces of equipment, which allows for increased use of modularization. This will minimize construction and assembly work for the remote mine site, leading to safer and more cost-effective project delivery. For more information, please visit www.worley.com.

Ohio Lumex to sell and service Breen sulfuric acid dewpoint monitoring technologies ST. LOUIS, MO.—Mississippi Lime Company (MLC), a leading global supplier of high-calcium lime products and technical solutions, has completed an agreement to transfer customer and technical services for its Breen Energy Solutions subsidiary to Ohio Lumex. Breen Energy Solutions has patented technologies to detect, measure and control sulfuric acid vapor (SO3 / H2SO4) and other condensable acid gasses. The Breen

AbSensor (ABS) probe was designed for use by electric generating utilities to detect the level of sulfuric acid and ammonium bisulfate vapor within the flue gas duct, ensuring that acid gas mitigation technologies are effective. The Breen-SA probe was designed to detect changes in sulfuric acid dewpoint in the process gas of sulfuric acid plants. Ohio Lumex is a global emissions and process monitoring leader specializing in biogas analysis, including mercury analyzers, continuous emissions monitors, sampling systems and sorbent traps. Per the terms of the agreement, Mississippi Lime has granted a license to Ohio Lumex to take over all sales, customer support and technical services for Breen Energy Solutions, which MLC acquired in 2015. For information about Breen technologies or to request support, contact Ally Krishtal, Service Department Manager at Ohio Lumex, by email at almira.krishtal@ ohiolumex.com or visit www.ohiolumex. com.

Acquisition of Saconix to drive expansion of sulfuric acid business in North America TOKYO—Sumitomo Corporation, through Sumitomo Corporation of Americas, has completed the acquisition of Saconix LLC. from former owner Copperbeck Energy Partners LLC, a U.S. private equity fund, to make Saconix a wholly-owned subsidiary of the Sumitomo Corporation Group. Saconix is engaged in the distribution and transportation service of sulfuric acid in U.S. West and Gulf Coast. The Sumitomo Corporation Group’s sulfuric acid business has its origins in the export of sulfuric acid from Japan. In 1994, the Group acquired 100% ownership of Interacid Trading S.A., the world’s largest seaborne trader by volume of sulfuric acid. Since then, the Group has been broadly engaged in the provision of services, including seaborne trading, local distribution, and storage of sulfuric acid in the United States, Chile and other countries. The strategically located sulfuric acid storage tanks, owned by the Group, and the highly trained safety operations enable the Sumitomo Corporation Group supply customers with the required quantities at any time demanded. By leasing space in its storage tanks, it can also hold the difficult-to-store chemical on customers’ behalf. In this way, the Sumitomo Corporation Group provides added value beyond its trading. Saconix has tangible distribution facilities, including storage tanks and transloading facilities at several sites in US West and Gulf Coast, and provides local distribution and logistics services. By making Saconix its wholly owned subsidiary, the Sulfuric Acid Today • Fall/Winter 2023

Sumitomo Corporation Group will acquire new logistics bases in the western part of the U.S. and the Gulf Coast region, boost its worldwide sulfuric acid storage capacity to 19 tanks, or about 330,000 tons (including lease assets), and increase its trading volume to about 3.5 million tons of sulfuric acid per year, or around 20% of all seaborne trading volumes. For more information, please visit www.sumitomocorp.com.

First Quantum Minerals to expand Kansanshi Mine with MECS® Technology ST. LOUIS—Global copper company First Quantum Minerals Ltd. has contracted with MECS, Inc., a subsidiary of Elessent Clean Technologies, for the Kansanshi Smelter Expansion at the Kansanshi Mine in Solwezi, Zambia. The MECS scope will include a redesign of the existing sulfurburning sulfuric acid plant into a copper smelter off-gas recovery sulfuric acid plant. This transition to a copper smelter off-gas recovery acid plant will enable First Quantum to reduce emissions from the existing copper smelter, increase production at the mine, and supply more copper to the global market which will enable the adoption of greener technologies. The MECS® sulfuric acid design for First Quantum incorporates state-of-the-art products and technologies, such as MECS® catalyst for low emissions and high conversion, Brink® mist eliminators for superior mist elimination and ZeCor® alloy towers, ZeCor® pump tank and UniFlo® acid distributor technology for operational reliability and efficiency. The sulfuric acid plant conversion will also facilitate increased capacity for First Quantum to better serve their clients, as well as benefit the region by contributing to a more competitive and cleaner global supply chain of copper and gold. Startup of the Kansanshi Smelter Expansion at the mine site in Solwezi, Zambia is expected to take place in 2025. Please visit ElessentCT.com for more information.

J.R. Simplot Co. to close California facility BOISE, Idaho—The J.R. Simplot Co. plans to close its fertilizer manufacturing facility in Lathrop next year, due to lower demand for products distributed from the facility Sulfuric Acid Today • Fall/Winter 2023

and higher costs over the past several years. The closure is planned by Aug. 31, 2024. “We recognize the very real and often difficult impact a plant closure has on people and the community,” president and CEO Garret Lofto said. “We want to thank all of our Lathrop employees who have supported our efforts. The decision does not reflect the effort, pride and commitment they’ve shown over the years.” Simplot produced controlled-released fertilizer at the Lathrop plant, as well as a ‘fused-safe’ ammonium sulphate nitrate based on Honeywell technology. For more information, please visit www.simplot.com.

Department

INDUSTRY INSIGHTS

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Mount Isa Mines announces operational changes MOUNT ISA, Australia—Glencore has announced that after 60 years of copper mining, the Mount Isa Mines underground copper operations and copper concentrator will close in H2 2025. Mount Isa Mines’ other metal assets, including the copper smelter, George Fisher Mine, zinc-lead concentrator, and lead smelter in Mount Isa, as well as the copper refinery in Townsville, will all continue operating. Glencore has conducted a range of studies seeking to extend the life of the underground copper mines, but unfortunately they have reached the end of their life. The studies revealed that the remaining mineral resources are not economically viable due to low ore grades and areas where, due to geological conditions, safe extraction can’t be achieved using current technology. Glencore’s Lady Loretta zinc mine, located 140 kilometers north-west of Mount Isa, which has a finite orebody with a seven-year mine life will also close in 2025. “We know this decision will be disappointing for our people, our suppliers, and the Mount Isa community,” said Chief Operating Officer of Glencore’s Zinc Assets in Australia, Sam Strohmayr. “The reality of mining is that mines have a beginning, middle and end. And unfortunately, after 60 years of operation, Mount Isa’s underground copper operations have now reached that end. We want to give our people as much time as possible to consider the best options for them and their families, which is why we are notifying our workers and the community almost two years before these mines close.” For more information, please visit www.glencore.com.au. q

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Cover Story

Sulfuric acid production at farmer-owned Ravensdown “ Ravensdown produces and sells directly to farmers By: April Smith, Editor

As a leading fertilizer manufacturer in New Zealand, Ravensdown Limited provides a wide range of fertilizer products and services to support the country’s farmers and enhance agricultural productivity. As a 100% farmer-owned cooperative, the business is governed by its farmer shareholders and its success is closely tied to the success and well-being of those shareholders. Ravensdown produces and sells directly to farmers an array of fertilizers including superphosphate, urea, DAP, potash, sulfur products, and custom blends. The company operates three manufacturing sites in Dunedin, Christchurch, and Napier, each with its own sulfuric acid facility. The company also operates several lime quarries and over 80 stores throughout the country, employing a total of about 800 people.

strong emphasis on sustainable agricultural practices in the 1990s, working with farmers to improve nutrient management, reduce the environmental impact of farming, and promote responsible land use. In the 2000s Ravensdown invested in research and development to create more efficient solutions, including the development of custom fertilizer blends tailored to the specific needs of New Zealand farmers. In the intervening years, the company continued its commitment to sustainability and the environment, engaging in initiatives to reduce greenhouse gas emissions, encourage efficient nutrient use, and promote environmentally sound farming practices. Today, the cooperative remains a significant player in New Zealand’s agricultural market, using expertise and technology to help farmers reduce environmental impacts and optimize value from the land.

Christchurch

Ravensdown Christchurch plant readies final product for delivery.

Offering much more than fertilizer, Ravensdown provides services and advice related to nutrient management, helping farmers make sustainable and environmentally supportive decisions. Using a groundup approach, the cooperative works with farmers to study their soils and yields, then provides recommendations to meet the exact needs of the farm. The approach includes research and development, testing and analysis, highly qualified field staff, an extensive product range, a customer service center, and a national distribution network. Ravensdown began in the late 1970s in response to the announced merger of two dominant fertilizer companies, Kempthorne Prosser and Dominion. Farmers belonging to several regional cooperatives were already dealing with rising costs and lowquality products, and they worried conditions would get worse with the pending monopoly. So, they banded together in 1977 to form Ravensdown Limited, which took over Kempthorne Prosser in 1978. In the 1980s the company continued to expand, including developing new manufacturing facilities and distribution centers. The cooperative began to place a Sulfuric Acid Today • Fall/Winter 2023

The Ravensdown Christchurch manufacturing site services the upper South Island with fertilizer. Christchurch’s 250 tpd sulfuric acid unit produces mostly for the manufacture of superphosphate fertilizer products. The acid is also sold to other industries, though, including milk production, geo-thermal, and timber processing, among others.

Sulfuric acid plant at Ravensdown Christchurch, New Zealand.

Ravensdown’s Christchurch’s Hornby manufacturing facility.

In a recent equipment upgrade project, Hornby replaced its pipework, circulation tank, and pump. The original piping was cast iron, dating back to 1968 when the plant was first commis-

an array of fertilizers including superphosphate, urea, DAP, potash, sulfur products, and custom blends.

sioned. Though some sections were replaced over the years, the entirety of the pipework was exchanged this year with MONDI™ piping. “MONDI™ was chosen for long-term life cycle cost, safety, and durability,” said Rob Batt, Acid Plant Co-Ordinator, Ravensdown. “We already had some MONDI™ sections and their wear rate is very low. Plus, they have stood up to our earthquakes, some of which were significant. Cast sections fail more easily compared to the spun castings of MONDI™.”

MONDI™ piping used throughout Christchurch sulfuric acid plant.

Ease of assembly is another bonus of the pipework. “It doesn’t require specialist welders. Sections are easy to replace if the need ever arises,” Batt said. Supplied by Acid Piping Technology (APT), MONDI™ piping is a special alloy of ductile iron designed to handle 92-100% sulfuric acid at temperatures of up to 300° F (149° C). “It has four times the corrosion resistance compared to cast iron, with a heavy wall cross-section for generous corrosion allowance. It’s designed to last the life of the plant,” said Alex Knoll, of APT. In addition to cast iron being more brittle, pipe lengths are shorter requiring more connection joints and more potential

”

points of failure. “We worked closely with the plant to eliminate unneeded joints and add pieces like strainers as we went,” said Knoll. “Strainers keep tower packing from getting into the pump tank.” The circulation tank, which was due for replacement, was changed out during the same 10-week maintenance outage, along with the tank’s 6 MTH pump, which was exchanged for a higher capacity 8 MTH pump. “The new pump allows us to have common parts with the Napier acid plant and increases acid flows without over-stressing the pump, which in turn reduces maintenance requirements,” Batt said. Suppliers APT and Lewis Pumps were selected for their reliability. “We have always had Lewis pumps and they have proven themselves over a long time here,” Batt said. “The assistance from APT and SES with all the measurements/requirements— everything to get it right—was extremely helpful. At first the project seemed bigger than it was, but it didn’t end up that way— good planning is the key,” he said. The Hornby team is pleased with the new investment. “The long-term costs will be lower, and reliability will increase,” Batt said. “The hard bit is convincing the people controlling the budgets because there’s no extra budget to play with, just good value from the improvements in reliability. This is one of the best things we’ve done. In another recent equipment upgrade, both Hornby and sister plant Dunedin replaced their original economizers, each dating back to the 1960s. As they reached end-of-life, the economizers’ tubes were leaking or fouling, requiring repairs to bypass the bad tubes. Over time, each bypass reduced the heat exchange capacity. The two new economizers were supplied by Thermal Systems (Hyderabad) Pvt. Ltd.

Napier

As New Zealand’s largest superphosphate manufacturing site, the Napier operation supplies single superphosphate and variants to the growers and farmers in the Hawke’s Bay Region and throughout the PAGE 7

Cover Story

North Island. The onsite sulfuric acid plant capacity is 650 tpd and Napier is responsible for 50 percent of total Ravensdown production. The other two sites, Christchurch and Dunedin, supply the other 50 percent.

Ravensdown Napier fertilizer plant.

The biggest challenge Napier faced this year was severe flooding from cyclone Gabrielle in February. Although the acid and superphosphate plants were relatively unaffected, infrastructure elsewhere sustained major damage. “We lost power for a week, silt covered most of the site, product was affected, buildings were uninhabitable, the local waste treatment plant was damaged, and the plant and soil lab (Analytical Research Laboratories) was totally lost,” said Kieran Murray, National Technical Manager at Ravensdown. “The plant was also subjected to theft which delayed our restart.”

except for suspension of the site’s turbine, which had to be shut down because of remaining limitations in exporting power. While the site was busy cleaning up after the cyclone, plans for a new converter installation at the acid plant were underway. Replacing the original grid and post unit from 1976 will be a new stainless steel 3+1 converter with an internal superheater scheduled for installation in mid-2024. The old unit with its external superheater and associated ducting is at end-oflife, causing ongoing maintenance challenges. The new converter, a Chemetics stainless steel radial flow design, will include an internal superheater. “The internal superheater eliminates the associated hot external ducting which can contribute to leaks and maintenance issues,” Robert Maciel of Chemetics explains. Plus the new converter increases catalyst capacity by 40 percent over the old unit. Beyond maintenance and capacity benefits, the upgrade complies with a new 35-year environmental regulation that lowers the maximum SO2 emissions limit from 60kg/hr to 40kg/hr, Murray explained.

Sulfuric acid plant at Ravensdown’s Dunedin location.

Recent maintenance projects carried out at the site’s 240 tpd sulfuric acid plant are keeping the facility running smoothly. The projects included repairing brickwork in the sulfur burner, replacing gas ducting, cleaning the ABS tower acid distributer pipework, and performing a boiler survey.

said Dickinson. “We removed packing so we could withdraw the pipework for cleaning. No repairs were required.” The team performs this maintenance as needed based on acid tower performance as indicated by SO3 and acid mist levels. “Regular stack testing of SO3/acid mist will signal poor absorption from poor acid distribution caused by partial blockage of the distributor,” Dickinson said. The yearly boiler survey consisted of removing safety valves for inspection and testing. Minor repairs were made to several steam valves and internal tubes were cleaned. The company also recently completed a 6 million NZD renovation of the 90-yearold Ravensbourne wharf in Port Otago, 10 kilometers northeast of the Dunedin facility. The renovation, completed in March, is expected to eliminate as many as 7,000 truck movements from roadways each year.

Refurbished Ravensbourne wharf expands shipping capacity, decreases truck movements.

Chemetics converter design with radial flow and internal superheater.

Flooding at Ravensdown Napier from Cyclone Gabrielle suspended operations for over five months.

The onsite sulfur storage was inundated to over a meter in depth which caused high acidity levels in stored sulfur leading to significant corrosion in the sulfur filter. “Even with low acidity in the filtered product with appropriate lime added, the filter weave collapsed on multiple occasions,” Murray said. The centralized control server also failed and was replaced with hardened PCs to run the operator interface. After months of remediation during which temporary structures and intercoms were used, the site came back online in early August and is now fully functional, PAGE 8

“All ducting between the converter and other plant equipment will be redesigned and replaced to minimize stresses on the equipment and ensure leak-free operation for decades,” said Maciel. “The converter will also be delivered to the site in large shop-fabricated modules which minimizes cost and schedule impacts.” Choosing Chemetics for their converter contractor made good business sense for Ravensdown. “We’ve had previous replacements of a number of vessels at the plant over time,” Murray said. “This next vessel provided a standardized approach to consistency at the plant.”

Dunedin

Ravensdown Dunedin is based in the lower South Island, supplying fertilizers to that region and occasionally other parts of the country.

The Dunedin team replaced damaged sections of the sulfur burner’s brickwork, a regular maintenance activity typically performed once a year during a cold shutdown. “These sorts of repairs are expected for a 56-year old plant that experiences yearly heat cycles from cold stop to running temperature,” explained Phill Dickinson, Ravensdown Acid Plant Engineer. Dunedin also remedied gas leaks by replacing sections of ducting spanning from outside the pre-heaters to the converter tower. Ducting is either repaired or replaced depending on thickness of the ducting wall, explained Dickinson. “Either a localized repair is suitable or a full section replacement is required depending on the results of the thickness test. A localized repair can be completed during a plant hot stop, whereas a full section replacement, as in this last instance, takes place during a cold shutdown.” When replacing older carbon steel ducts, a more durable material is used, such as 304 stainless steel. The team performed routine inspection and cleaning of the distributor pipework in the absorption tower. “The pipework was clogged with debris (gasket material and ceramic chips) because of a failure of the acid strainer on the circulating pump outlet prior to the ABS tower,”

A new 145-metre-long berthing beam was built along the wharf length and significant maintenance work was carried out on the existing timber structure. The project was a collaboration involving Ravensdown, Port Otago, HEB Construction and consulting engineers BECA. The Ravensdown wharf renovation benefits the company’s operations, the environment, and the local community. It also affirms the company’s commitment to move product by sea.

Moving forward

Ravensdown’s sulfuric acid plants will continue site improvements at all three manufacturing facilities in the forth coming months. In future company initiatives, Ravensdown continues its dedication to the success of its owner farmers. Each year, the company invests 2 million NZD in research and development to maximize farming competitiveness and efficiency. In a partnership program with the government of New Zealand, the company is developing technology to enhance precision in aerial spreading to ensure the right amount of fertilizer is applied to maximize pasture and livestock growth. q Sulfuric Acid Today • Fall/Winter 2023

Feature

MARKET OUTLOOK

The turning point in 3Q23 By: Fiona Boyd and Freda Gordon, Directors of Acuity Commodities

From July 2022 to July 2023, there was a lull overhanging the global phosphate fertilizer market which had a knockon effect on other commodity markets, including sulfur and sulfuric acid. It was in July 2022 when signs of weaker sulfur/sulfuric acid demand began to emerge, tied mainly to lower production of phosphate fertilizers. A large contributing factor was higher prices for ammonia, another key raw material for phosphate fertilizer production outside of sulfuric acid. The spike in ammonia prices was a result of the Russia-Ukraine conflict and its impact on energy prices, with ammonia mainly derived from natural gas. As an indication, the Tampa monthly ammonia price reached as high as $1,625/t cost and freight (CFR) in April 2022, after which it hovered in the $960-1,175/t CFR range for the balance of 2022. Downward pressure on ammonia prices emerged in 2023 as volatility and uncertainty in the energy markets cooled and demand for phosphates remained constrained. By July 2023, the benchmark had sunk to $285/t CFR, steadily declining month-over-month from a high of $975/t CFR in January. It was a similar story with sulfur when in 3Q22 there was a sudden and sharp drop in sulfur prices, largely due to the sustained drop in buying to support the phosphate fertilizer industry. This had a subsequent impact on sulfuric acid pricing. While there were many market developments stemming from the drop in phosphate production, one of the most significant for the traded sulfuric acid market was a retreat in buying from the key import market of Morocco and its impact on European smelter acid producers. Last year, Morocco imported around 1.3m t of sulfuric acid, down a notable 800,000t from 2021. As of the end of June this year, it imported around 130,000t, down around 900,000t from the just over 1m t it imported in 1H22. This reflects the dramatic drop in its downstream appetite that emerged in 3Q22. This continued going into 2023, along with weaker industrial demand in Europe, driven in part by higher input costs making operations uncompetitive. Adding more pressure, Morocco’s dependency on sulfuric acid from northwest PAGE 10

Europe shifted in 2019 when it began to source more from China as supply in that country continued to grow alongside base metal smelter capacity. More competition from China along with the reduced consumption of Morocco put downward pressure on prices from Europe due to resulting length. And while unrelated to the fertilizer market, lack of spot demand from the other key import sulfuric acid market of Chile weighed on suppliers. It was in 2H22 when European producers found Chile as a regular outlet with Morocco on the sidelines and it was in a much better freight position compared with Asia. However, Chile began to have its own issues in 4Q22 that constrained its consumption going into this year as we discussed in the Spring/Summer 2023 issue of Sulfuric Acid Today. While the issues in Chile have since been resolved, spot buying interest remained limited in Chile in 1H23 for a number of reasons. Similar to Morocco, supply from China was a critical part of the puzzle for Chile. Last year, China supplied a notable 1.3m t to Chile against its annual imports of 3.7m t, and almost double what it supplied in 2021. This was a historic high with China overtaking Peru as top supplier to Chile for the first time. During the first six to seven months of this year, market conditions were largely unchanged from late 2022. In fact, the situation got worse in March 2023 when sulfuric acid prices entered negative freight on board (FOB) pricing territory, as there was a continued lack of spot interest, particularly from sustained no spot buying from Chile and Morocco. The

Fiona Boyd, Acuity Commodities

pressure was most notable in Asia, again with high freight complicating economics. This saw pricing go as low as minus $15/t FOB in March, while the northwest Europe FOB price hit a low of $0/t. Fast forward to August 2023, and the landscape had completely changed. This was triggered by a notable improvement in phosphate fertilizer demand, and therefore production, which saw sulfur/sulfuric acid demand and prices increase along with it. In addition, Morocco returned and showed strong appetite in third-party acid to complement its notable on-site sulfur-based production. It soon swooped in, purchasing cargoes available from key supply regions such as China and northwest Europe. At the same time, domestic supply issues were popping up in Chile, which triggered some unexpected demand. Meanwhile, buyers in Chile were becoming more cognizant of acid prices increasing on improved sentiment from the related sulfur and phosphate sectors. This resulted in some buyer inquires for the balance of 2023, leading to another boost in sentiment. With the return of both Morocco and Chile, spot availability thinned accordingly. This was reflected in FOB pricing with export pricing in China nearing the $50/t level at the time of writing, while Europe had firmed to close to $40/t FOB. Considering the China price was in negative territory in 1H August, and close to $50/t FOB by early September, this reflects the dramatic run up. Some price support could arguably be from reduced acid export activity from China. We have discussed in previous issues that China’s influence is topical because of its unpredictability. This

Freda Gordon, Acuity Commodities

is in part as producers weigh between the netback of domestic versus export sales. Now with China’s domestic consumption recovering amid the return of seasonal demand and its delayed rebound from the Covid-19 pandemic, it is exporting less on improved domestic consumption. Customs data from China reflects that in the first six months of this year, just over 1m t of sulfuric acid were exported, a dramatic drop from the close to 2.3m t exported in 1H22. In addition to the above, we continue to see sustained import spot buying from markets that have historically not been notable players. This includes Saudi Arabia and Indonesia, with the latter showing an increasing appetite as it develops nickel leach operations to support the electric vehicle evolution. One factor that has not changed since 2022 is ongoing high sulfuric acid freight rates. It remains particularly the case in Asia, where demand for stainless steel ships continues to outstrip supply with that being reflected in firmer freight rates. Continued firm demand from nonsulfuric acid sectors has been seen since last year. With new stainless steel builds still expected to enter the market beginning next year, there are hopes this could relieve some pressure on freight rates accordingly. As we look to the end of 2023 and begin preparing for market discussions for 2024, among the key factors to be discussed will be: demand from Morocco and Chile, Indonesia’s requirements, domestic demand in China and Europe and its impact on availability, and inflated freight rates. Acuity Commodities provides insight into the sulfur and sulfuric acid markets through price assessments, data and supporting analysis. Offerings include weekly reports on the global sulfur and sulfuric acid markets. For North America, we offer a bi-weekly report on sulfur and sulfuric acid as well as a monthly report on industrial chemicals, including caustic soda and hydrochloric. In addition, Acuity does bespoke consulting work. Please visit www.acuitycommodities.com for detailed information.. q Sulfuric Acid Today • Fall/Winter 2023

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Department

SAFETY SECTOR

The evolution of safety in the sulfuric acid industry By: Darwin Passman, CSP, Safety Director, VIP International

Safety in the sulfuric acid industry has changed significantly over the last 30 years. Thirty years ago, the industry emphasis on safety was having Workers Compensation insurance and someone to document accidents. Most of the contractor industry had little or no safety training and traditionally used temporary labor from a temporary employment agency. These employees often had no training, very little work experience and seldom stayed the full duration of the job. In the 1980s, VIP International focused solely on specialized services for the sulfuric acid industry. A training program was developed for employees in the areas of the work to be performed. VIP developed standard operating procedures specific to these services supported by the company’s health and safety manual. In the early 1990s safety councils found their way into the large industrial areas of Baton Rouge and Houston. They were the result of local area petrochemical facilities coming together and identifying the need for a more consistently trained workforce. The safety councils were commissioned to provide basic safety training to the sur-

rounding work force so they could work safely in a plant environment. This basic orientation began as a day and a half training program with written testing on each topic. The topics included everything from hand tool safety to confined space entry. The idea was to give the worker a basic understanding of safety related tasks that occur on a plant site. It touched on many topics but did not provide detailed training on any topic. The worker was given a card certifying completion of training that became a requirement for entry into the surrounding facilities. More detailed training on specific topics was apparently needed and safety councils were best suited to provide that training. The councils began providing everything from forklift training to hazardous materials handling. As usual, incidents on sites dictate new training needs. Lock out tag out, confined space, asbestos awareness, atmospheric monitoring, elevated work and electrical safety are just a few of the hot topics identified for additional training. The Baton Rouge and Houston industry began to incorporate their site-specific training under the safety council’s umbrella followed by other parts of the United States

Visit Us at Sulphur Conference: Stand 29 Bulk of radiant trapped in front zone Tight residence time distribution Cooler here

Hotter here

Solid perimeter for backmixing - same as choke ring

Spiral creates much longer “contact pathway”, or overall distance in close contact to react, even with lower temperatures here

Increased velocity and temperature carried to tubesheet Broad residence time distribution means insufficient RT for some of the reactions

What does this mean for SRU Operators?

More complete Ammonia Destruction/ increased capacity to process NH3 if desired Better BTEX Destruction

Better protection for tubesheet refractory/ cooler temperatures going into WHB

More efficient use of furnace volume means increased capacity Better mixing and longer distance together mean more complete reactions

Lower energy costs when co-firing or in tail gas incinerators

What does this mean for sulfur burning acid plants?

No more fireflies at furnace exit Increased capacity

Lower Pressure drop compared to baffles

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PAGE 12

through similar safety councils. Much of the training has become Computer Based Training (CBT). Currently there are 54 safety councils throughout the country, including one in the Virgin Islands, that belong to the Association of Reciprocal Safety Councils (ARSC). The ARSC program ensures the same training is provided to all workers regardless of their geographical location. Facilities know that out of state workers with ARSC training have received the same level of training as their local work force. Through the ARSC program, training for a specific site located in one area can be transferred to safety councils in another area to allow for the training of workers prior to their arrival for a site shutdown. As convenient as safety councils are, all training cannot be attained through them. It is the responsibility of contract employers to provide “performance based” training to their employees specific to their performance job tasks. An effective training program requires a methodology be in place for the work being performed. Standard operating procedures are an excellent tool in defining this methodology. Your health and safety manual is a great resource during the development of procedures to confirm they have the fundamental framework of safety. Examples include your company’s lock out tag out and confined space policy to develop a procedure involving confined space entry. Standard operating procedures are developed by teams of employees with experience in specific performance tasks. The team should be comprised of a cross section of persons with specific skills in the areas of operations, maintenance, process and safety. Standard operating procedures should be living documents that change with the improvement of technology, efficiency, and better ideas. Experienced teams as described above must periodically review all procedures. Once the standard operating procedures are completed, a training program must be developed to provide workers with knowledge and skills needed to perform the task safely and consistently in the field. Some skills may be generic like operating a forklift, while others are specific to the task at hand. An example of a procedure requiring specific “performance based” skills would be the systematic removal and replacement of an acid distribution system. The following training is needed for this procedure: 1. Training in the use of specialized PPE to work in an acid contaminated environment. 2. Working in an IDLH (Immediately Dangerous to Life and Health) environment. Pulmonary function testing, quantitative

fit testing, and specific training on the donning and use of a full face supplied air system with an independent backup breathing air bottle. 3. Operating atmospheric monitoring systems and making the proper response to the information provided by the monitor. 4. Cutting and welding in an acid contaminated environment. 5. Training in the use of rigging equipment and techniques to remove and replace piping. 6. Boilermaker skills to install systems properly. 7. Safety personnel trained in the development of JSAs (Job Safety Analysis) and rescue plans. 8. Personnel on site that have first Aid / CPR and rescue training in the event a rescue must take place. As noted, many skills are needed to complete one procedure. Most of these skills are not offered by a training company or safety council and must be developed by the company performing the work. I define “Performance Based Training” as training that replicates the job or task undertaken by an individual or team. The equipment, tools and conditions should give the employee “hands on” understanding of the work performed. This type of training program is invaluable to the success of new employee development and provides experienced employees with solid refresher training. The benefits to the company are a well-trained workforce with a solid foundation to safely and efficiently perform the tasks required. The development of an effective safety and training program takes time, money, energy, and attention to detail. Management must not only commit the resources, but they must also commit themselves to the development, implementation, and value of an ongoing and ever-changing program. Without this commitment, you will be unable to provide your employees a fully functional safety and training program that will ensure their success on the job site. At best, you will only have a program that may meet the minimum OSHA requirements. The next safety segment will address government requirements that must be met to work at various sites located in the United States, Canada, Europe, Australia, and Africa. The discussion will address the prequalification processes used by U.S. and foreign-based companies. One of the more interesting prequalification systems is the use of third-party audit firms that use an initial questionnaire to build a matrix structure defining the contractor’s requirements for their safety program to work safely at a specific facility. For more information, please visit www.vipinc.com. q Sulfuric Acid Today • Fall/Winter 2023

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Feature

Mosaic South Pierce upgrades decades-old drying tower Fertilizer producer Mosaic recently replaced a 40-year-old brick lined drying tower at its unit 10 sulfuric acid plant at its South Pierce facility in Mulberry, Fla. Where the old tower once stood is a new MECS ZeCor®-Z drying tower, which came online last February after a quick 16day shutdown. The drying tower replacement project is part of Mosaic’s broader effort to improve reliability of acid plants in Florida and Louisiana. The long-range capital improvement plan, with projects continuing over the next few years, is replacing acid towers and converters that have been in service for four decades or more. With 40 years of service, the old drying tower at unit 10 operated beyond the typical asset life expectancy of 30-35 years.

About Mosaic South Pierce

Mosaic is a leading worldwide producer of concentrated phosphate and potash fertilizers. With nine locations in North America and South America, the company produces 25m tonnes finished product annually and serves customers in 40 countries. The South Pierce facility has two sulfuric acid units, numbers 10 and 11, both with 2,500 tpd design capacity. The units produce sulfuric acid for the company’s internal use. Acid is stored in storage tanks and shipped to sister plants as needed to supplement fertilizer production. “The South Pierce facility is considered a ‘swing plant,’” says Jailall Jairam, Sulfuric Acid Plant Maintenance Superintendent, currently at Mosaic’s New Wales site. “This means at any given time, depending on acid demands, Unit 10 and Unit 11 can ramp up acid production to meet these demands.” South Pierce manufactures sulfuric acid in a sustainable way. Jairam explains: “In a nutshell, we burn molten sulfur to produce SO2 gas. The SO2 gas goes through different stages in the converter to create SO3 gas, which produces sulfuric acid. The process enables us to produce steam by utilizing boiler feed water in different phases of the process through temperature controls of the equipment at each phase We use the steam in turbines to generate power on site, and we utilize the power internally and sell power externally when we have excess capacity,” he said.

Project overview

In January 2022 South Pierce secured commitments for capital funding to begin engineering and design. In January of 2022, MECS was contracted to supply the tower’s engineering, design, and all internal equipment. The tower, distribution systems and meshpads are made of MECS ZeCor®-Z PAGE 14

For maximum efficiency, the top section of the drying tower was welded after the internals were installed.

material—a corrosion resistant high silicon stainless steel alloy. The tower was fitted with ceramic structured FLEXERAMIC® packing supplied by Knight Material Technologies. Knight provided the hydraulic rating calculations to confirm the allowable flow rates along with the supervision during installation to maintain quality assurance. CMW planned and executed the demolition of the old tower and installation of the new one. CMW fabricated the new tower in its Lithia, Florida shop, shipped it in modular sections, field welded and erected it prior to the outage. During the outage, they dismantled and removed the old tower, then installed the new tower, including internals, ducting, and piping.

The technology

The new ZeCor® tower offers Mosaic maintenance advantages. First, ZeCor®-Z alloy is corrosion resistant in a wide range of concentrations and temperatures. Second, if a leak develops, it’s easy to find and the material can be patched and welded simply. “Because of the material upgrades and new metallurgy, the reliability is much better and maintenance is much easier to perform and cost-effective,” said Jairam. The upgraded design also represents an advancement, which enables quick reaction time to identify and make repairs to reduce fugitive gas emissions. “The new tower has improved technology in the distribution system, mist eliminators, and structured packing, all of which enhance the tower’s performance,” Jairam said. The packing provides its own benefits. “The advantages of structured packing are simple,” said Kevin Brooks, President, Knight Material Technologies LLC. “Our unique geometry maximizes the surface area available for mass transfer (for the dying tower case, water absorption into the sulfuric acid) while minimizing the energy required to push the process gas up through the packed bed. The resulting energy savings can be as high as 50%.”

The tower was fitted with FLEXERAMIC® ceramic structured packing supplied by Knight Material Technologies. The unique geometry maximizes the surface area available for mass transfer.

Then there are distinct installation advantages. “ZeCor towers can be replaced during a normal shut-down causing no loss in production and cost less than building on a new foundation with new duct and pipe tie-ins and all new platforms,” says John Horne, Business Development Manager, Elessent MECS Technologies. A separate concrete foundation can cost $1 million and bricklaying is very time consuming. “It takes two months to brick a tower and it must be built on-site. It can’t be fabricated elsewhere and moved. Add to that all the new duct work, acid piping, and platforms that are required and it winds up costing 30% less to install a ZeCor ® tower versus brick lined. For the last 25 replacements we have done for Mosaic, they have utilized existing foundations and infrastructure for the new equipment,” Horne said.

Beating the clock

A big challenge Mosaic faced was completing the project within the scheduled turnaround time of 16 days. “I had about one year to lead the project team from engineering and design to working with MECS to produce a new drying acid tower that meets Mosaic’s needs

The drying tower bottom and mid section lifted into place.

and fulfills our obligations to produce sulfuric acid for our sister plants,” Jairam said. Jairam cites collaboration within Mosaic and with contractors as the reason the new tower started up as planned in February 2023. “Mosaic stakeholders supported the project from day one. The project was identified at an early stage, and the design parameters were established, which helped drive the capital process management (CPM) processes that included planning, leading, fabrication, and commissioning of the new tower last February. We established early decision-making and effective communication internally, and MECS helped pave the way for a successful project outcome,” said Jairam. Choosing the right contractors for the job played a significant role in finishing on schedule. Mosaic selected MECS for its technology and reliable service history. “As a technology provider for sulfuric acid plants worldwide, it was easy for us to choose MECS to help us design a new acid tower that meets 21st century acid technologies,” Jairam said. “Over the years, MECS has done major projects with Mosaic when it comes to sulfuric acid equipment, troubleshooting, and support,” he said. Sulfuric Acid Today • Fall/Winter 2023

Mosaic also contracted with structured packing supplier Knight Materials, who was recommended by MECS, Jairam said. Knight has many years of experience

installing structured packing in sulfuric acid drying and absorption towers. “Using a combination of detailed drawings, careful labeling of the packaging, and supporting supervision during installation, proper packing installation has become routine,” said Brooks. For old tower demolition and new

Elbow room

Another major challenge, particularly for demolition and construction, is maneuvering in tight spaces. “Over the years of additions to a plant or even from its original design, ground space and overhead space

for use of cranes and equipment is limited,” Legg said. “We address these challenges by strategic planning for crane use, sizing and placement, while also trying to minimize cost,” he said. “While there are many challenges in replacing industrial equipment of this size and age, including sulfite growth between brick and shell, rotten steel, acid leaks, and structural integrity to name a few,” Legg said, “our goal is to recognize and mitigate those challenges early during the planning stages.”

The result

Since its commissioning in February, the tower has performed very well, Jairam explained, including operating fully within design parameters. While a project of this caliber requires careful planning and scheduling, ultimately the people doing the work are responsible for the outcome. “The key reason for the success of this project can be summed up in two words: experience and relationship,” Legg said. “CMW has a longstanding relationship with Mosaic and we share many successful projects. And the team brought a wealth of experience. CMWs’ project manager, Will Sumner, worked closely with Mosaics’ project manager, Jai Jairam, on pre-planning, schedule creation, fabrication order, site layout, turnaround execution plan, and overall completion. Experienced personnel make these projects a success.” q

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PAGE 15

Feature

Ian Legg of CMW, left, and Jai Jairam of Mosaic pictured in front of newly constructed drying tower. CMW’s experience and relationship were some of the key factors for the success of the project.

John Horne of Elessent MECS Technologies, left, and Jai Jairam of Mosaic with new ZeCor®-Z drying tower in background. The distribution systems and meshpads are also made of MECS ZeCor®-Z corrosion resistant material.

tower construction, Mosaic chose experienced contractor CMW through competitive bidding. “CMW is by far one of the most capable contractors you can rely on when it comes to mechanical, fabrication, and installation,” Jairam said. “They have the experience, leadership, and technical abilities when it comes to providing quality workmanship in our facilities. More importantly, CMW had zero safety or environmental issues throughout the entire demolition, fabrication, and installation process,” he said. CMW’s Chemical Team is led by Ian Legg, Chemical Area Manager, CMW Inc. We have provided and managed over 30 brick lined acid tower demolitions across the country and safety is always at the forefront. “Each and every one is carefully planned to minimize potential risks from falling debris and reduce the need for workers to enter confined spaces while still completing within a critical timeframe,” said Legg. “CMW’s partner, KT-Grant, provides remote operated brick removal which minimizes or eliminates the need for tower entry. This has been a tried-and-true method in support of safety and meeting tight deadlines” Legg said.

Feature

Hindustan Zinc selects WESPs for downstream acid production By: Gary Siegel, Marketing Director, Beltran Technologies, Inc.

Hindustan Zinc (HZL), a subsidiary of Vedanta Limited, is one of the world’s largest Zinc and lead mining companies. Hindustan Zinc operates zinc smelter plants in Chanderiya, Debari, and Dariba. Beltran Technologies, with sixteen wet electrostatic precipitator systems in operation at HZL plants, has received an order for design, engineering, and construction of four more wet electrostatic precipitators (WESPs) for their sulfuric acid plants. A downstream sulfuric acid manufacturing plant is the economic revenue-generating answer for industries that generate sulfur oxides and sulfuric acid, including metallurgical smelters and refineries, petroleum refineries, natural gas processing facilities, electric generating units, spent acid regeneration plants, and municipal waste incinerators. For the purest form of market-ready sulfuric acid, an efficient sulfuric acid manufacturing process strictly requires the removal of contaminants from the input gas streams, especially fine and submicron particulates and acid mists, such as those emitted from metal ore roasters and smelters, petroleum refineries, and coal-fired industrial boilers. This is necessary for protecting downstream 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 lower maintenance and operating costs for the manufacturing plants. To capture fine and submicron particulates, submicron acid mists, and condensed organic compounds, plant engineers and consulting engineering firms continue to specify advanced wet electrostatic precipitators, which can clean complex gaseous emissions of particulates and acid mists down to submicron scale (PM 2.5) with up to 99.9% efficiency. PAGE 16

and corona intensity, to achieve maximum efficiency. Also, to prevent premature deterioration, critical surfaces should be constructed with advanced protective materials such as fiber-reinforced plastics (FRP) or high nickelchromium alloys. The high-voltage insulators should be continuously purge-air cleaned to further reduce maintenance costs.

Materials of WESP construction

Hindustan Zinc has selected Beltran Technologies to construct four more WESPs for their sulfuric acid plants.

WESPs operate by charging and collecting particulate, mists, and aerosols with a corona discharge formed by collector surfaces and sharp pointed discharge electrodes. High voltage power supplies charge WESPs at high voltage, usually between 30 and 75 kilovolts, depending on the WESP design and the process gas conditions. The WESP is usually configured with collector tubes or plates with discharge electrodes held in the center of the collector structure by a high voltage frame, supported by non-conducting insulators. Since process gases are saturated and contain electrically conductive mists and aerosols, the insulators must be operated dry, being purged by dry, clean, and heated purge gases, usually ambient air. WESPs collect liquid acid droplets, mists, and aerosols by either flushing the collector plates or continuously operating fogging sprays into the collector section. WESPs usually have deluge or wash nozzles mounted to periodically wash the WESP of solids and collected particulate not removed by the draining acid/ water collected by the WESP.

The collection efficiency of WESPs varies with the size of the particulate, mist, or aerosol. Since gas phase reaction and evaporation/condensation form particles around 0.1 to 1.0 microns, considerable acid mist and particles form in this size range. As particles increase in size from the submicron range, they are more easily collected, since field charging increases. Also, as particles decrease in size from the submicron range they are more easily collected, since diffusion charging increases. Therefore, the collection efficiency curve versus particle size forms a Ushaped curve with its minimum in the submicron range. The collection efficiency is also related to the corona power of the WESP, with the minimum efficiency increasing with greater corona power. To minimize the size of the WESP and maximize the operating efficiency, WESPs should be designed to maximize w, the drift velocity, or the rate at which particulate, mists, and aerosols move to the collector plates. The most efficient design when considering collection efficiency, compactness, and eco-

nomic design is the square tube collector configuration. The square tube collector completely utilizes the cross-section of a square or rectangular vessel, and can be effectively utilized in both round as well as hexagonal vessels. Due to the square tube’s high utilization of the vessel cross-section, it can be operated at a lower velocity so that the required tube length is lower, making it more efficient and easier to wash, since the wash sprays penetrate the collector. The high voltage frame is also more rigid, does not swing, and stays more accurately aligned, resulting in more efficient and reliable performance. Because of the shorter tube length, lower stabilizing insulators are not required, and the insulators can be mounted on the clean gas side of the WESP, reducing the requirement for heated purge air and resulting in more reliable WESP operation. Beltran WESP systems are built with sophisticated electronic controls linked to a closecoupled gas flow management system; these can optimize operating parameters such as gas velocity, saturation, temperature,

Today’s WESP systems are built of metal alloys, thermoplastic materials, thermosetting materials, and conductive graphite composite materials. Metal alloys are expensive and have extended delivery time, but their biggest disadvantage is the unreliable performance with regard to corrosion. The sulfuric acid WESP operates in highly corrosive environments, including sulfuric, hydrochloric, and hydrofluoric acid and other impurities, as well as increased temperature. Because of the high cost of more robust chrome-nickelmolybdenum alloys, like C-276, C-22 and C-2000, designers are attempting to utilize less corrosion resistant alloys like AL6XN and SMO 254, with resulting corrosion problems in some applications and conditions. The Beltran WESP manufactured with conductive graphite composite materials have the following advantages: • Highly corrosion resistant • Good mechanical properties • Electrically conductive • Homogenous • Do not require water/acid film to ground WESP • Fire retardant and thermally robust • Cost effective For more information, contact Beltran Technologies, Inc., at (718) 338-3311 or info@ beltrantechnologies.com; or visit the company website at www.beltrantechnologies.com. q

Sulfuric Acid Today • Fall/Winter 2023

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Department

LESSONS LEARNED: Case histories from the sulfuric acid industry

Case study: medium pressure HRS™ boiler leak initiation and early growth

By: Walter Weiss, Elessent Clean Technologies

Boiler leaks in general are dramatic events. The best boiler leaks are those that never happen but instead are prevented by inspection and repair prior to the point of failure. Once a leak begins, early detection of the leak and proper response are critical for minimizing damage to the boiler as well as the acid plant as a whole. The following is a case study of a boiler leak with early detection and response. The leak was detected and the plant shut down prior to any of the standard alarms and interlocks being activated. Good operator attention and communication made this possible. There was tubesheet damage (the definition of a leak) but the damage was localized and somewhat minimized so that the boiler assembly could be repaired and returned to service. The conditions precipitating boiler leaks are very difficult to observe. In hindsight, data review of the operation prior to the failure reveals subtle changes that made the upcoming need for a shutdown more obvious. But at the time, it was not readily observed by normal human attention. The next generation of controls and monitoring will use artificial intelligence (AI) which will be much more sensitive to these kinds of subtle changes and, using statistical analysis, better able to differentiate an issue from normal variation. The goal is to limit the damage from tubesheet leaks to the point where the boiler bundle is readily repairable.

What happens in a boiler leak?

A boiler is a piece of heat transfer equipment. Boiler water/steam at a controlled pressure is on one side of a tube and a process fluid is on the other. Water may be on the tube side or the shell side depending on the boiler design. Depending on the service, the boiler may operate at high pressure (400 to 900 psig or 28 to 63 kg/cm2g) if the boiler is located after the sulfur burner or furnace. It may be medium pressure (100 to 150 psig or 7 to 10 kg/cm2g) if the boiler is located before the acid towers or within the acid system. Boiler pressure determines the boiler water temperature—commensurate with saturation at that pressure. For instance, a 150 psig boiler will have a water saturation temperature of 365° F (185° C). Process fluid with sufficient heat to be above the saturation temperature of the boiler water will release some portion of its heat to generate steam. In the sulfuric acid industry, process fluid may be gas at a pressure from 40 to 200 inches wc (1000 to 5000 mm wc) or sulfuric acid at 35 psig (2.2 kg/cm2g). Insofar as the steam pressure is higher than the process pressure for any of these conditions, any steam leak will result in water/steam injection into the process fluid. Boiler water level is controlled in the steam drum or kettle. For a firetube boiler, this is done in such a way that all the tubes are adequately covered with water. As steam is generated, and as blowdown is performed, there is less water in the boiler steam drum. Additional boiler feedwater is brought in under level control. Sometimes, the level control loop is well-tuned and the boiler feed water (BFW) flow is steady. If not so well tuned, there can be substantial variations in the flow, and this can result in cycles of measured flowrate. The flow of BFW and steam should match except for the amount lost to blowdown—about two percent for good quality water. For this basis, the average ratio of water to steam should be 1.02. A water leak would result in additional BFW flow needed to maintain level due to some additional flow for injection into the process fluid through the leak. Hence, an increase in this ratio would be observed—and would continue to grow with an increased leakage rate. Many plants make an effort to trend this ratio and may provide a high ratio alarm. To avoid the nuisance alarm that may occur during points in the cycle, the alarm set point needs to be placed outside the statistical variation observed from normal BFW flowrate cycling or swings that may occur during rate changes. This gives a range of non-alarm operation levels that can hide a consistently high ratio (leak) for a period of time and compromise the value of the ratio trending.

HRS™ boiler leak

A diagram of an older HRS™ boiler design is depicted in Fig. 1. Acid is placed on the tube side and medium-pressure boiler water is on the shell side of the kettle. A boiler leak from a failure in either the tube or tube-to-tubesheet joint causes boiler water to enter the acid system and dilute the acid. The BFW flow to steam flow ratio, as discussed earlier in the context of boilers generally, applies to HRS™ boilers as well. It can be monitored and will respond as noted earlier. In addition, the ratio of BFW flow to dilution water flow is also monitored. Dilution water is added to maintain the acid concentration to the HRS™ lower stage at the controlled set point. Required dilution water flowrate is dependent on SO2 conversion and gas strength, upper stage flow, as well as ambient humidity and the use or non-use of drying tower crossflow. There is some room for variation in water flow from time to time and season to season. There is a normal and expected variation in the ratio that is not related to boiler leaks. Leaking boiler water will cause an increase in BFW flow and a corresponding reduction in dilution water flow that is additive to this normal ratio fluctuation and may make the leak difficult to find. In addition to monitoring these ratios, the HRS™ system uses a number of alarms and interlocks to respond to HRS™ boiler leaks and/or upstream steam leaks. These include low low acid concentration in the lower stage in all HRS™ plants; high high corrosion interlocks PAGE 18

Fig. 1: HRS™ kettle type boiler circa 1988

on some older plants; and a number of temperature cross alarms and interlocks in newer plants. These are known as the NOTE 4 interlocks as designated on the interlock design sheet.

Case study

A leak started in an HRS™ boiler in a 2,300 TPD (2,100 MTPD) acid production line. Steam pressure was 95 psig (6.7 kg/cm2g). The plant was coming out of shutdown and had been running near full rate (90 - 95%) for only 24 hours prior to the leak detection. Process data during this time period was proportionately in line with the design material balance for warm weather operation: Steam flow – kg/h

35,060 average

Dilution water flow – m3/h

13.2 +/- 0.3 average with standard deviation

BFW/steam flow ratio

1.03 normalized; std dev estimated at +/- 0.02

BFW/dilution water flow ratio

2.66 +/- 0.12 average with standard deviation

Boiler temperature in – deg C

193

Boiler temperature out – deg C

180

The leak was detected at shift change—just after 07:00. An outside operator coming onto the day shift walked past the HRS™ boiler and could hear something unusual. These were likely the sounds of the leak as water was mixing with acid. The noise may have been generated from water vaporizing from the heat of mixing and then imploding when mixed with the bulk acid. The plant was shut down an hour later when the leak was confirmed. No alarms or other DCS indicated deviations were noted. Only the trends were noted in hindsight. DCS data was examined every thirty minutes and observations were made to assess signs of a leak. From these trends, listed in Table 1, the rate of leakage increase can be inferred. While the leak was detected just after 07:00, it is unclear when it actually started, but by 07:00 small signs of a leak were already present. The boiler tube leak was estimated to be 0.2 m3/h at 07:00; 0.7 m3/h at 07:30; and 1.5 m3/h by 08:00. (A flowrate of 1.5 m3/h is equal to 6.5 gpm). The observed leakage rate roughly doubled every thirty minutes in the early life of the leak. A small leak will become much more problematic in just a few hours. Acid temperature increased slightly at the boiler outlet (2° C) during this time period. There was no temperature cross. No alarms or interlocks were generated from the NOTE 4 temperature cross configurations as this did not meet the alarm criteria. Acid concentration in the lower stage did not change as the dilution control still remained within range and was controlled at set point. No alarms or interlocks were generated from here. Even at 1.5 m3/h leakage rate, the bulk acid concentration changed by less than 0.1%. The BFW to dilution water ratio was increasing from the average of the previous 24 hours. Full Rate Avg

06:30

07:00

07:30

08:00

08:30

Dilution Water – m /h

13.2

12.9

12.7

12.2

11.4

Shutting

Steam Flow – kg/h

35,060

34,250

34,670 34,590 34,470

the acid

BFW/Steam Ratio

1.03

1.05

1.07

plant

BFW/Dilution Ratio

2.66

2.65

2.74

2.84

3.02

down

Acid Temperature In – deg C

193

Acid Temperature Out – deg C

180

181

182

Table 1: DCS data vs. Time Sulfuric Acid Today • Fall/Winter 2023

Department

At 07:00 it was still within standard deviation. At 07:30 it was above two standard deviations and noteworthy but still not in alarm range. It remained the same at 08:00. No alarms would have been generated from this because of the higher alarm point noted earlier. The BFW to dilution water flow ratio was noted earlier as being most sensitive and it was markedly increased. By 07:00 the ratio had increased by nearly one standard deviation. Not remarkable by the normal variation, this was not likely noticed. By 07:30 it had increased by nearly two standard deviations. This might draw some attention if carefully watched, but still within the range of operation during the previous 24 hours. By 08:00 the ratio had increased by nearly three standard deviations. Yet to avoid nuisance alarms, most operators set this alarm point higher than this. For this case study, no alarm was noted from this ratio algorithm. Based on projections, the alarm point set for the BFW/dilution water ratio may have alarmed in another hour and the dilution water valve may have closed an hour after this. Because of astute operator observations and the quick response of the control room, damage was limited to the boiler tube sheet and that damage was localized. The bundle was repaired with some tube plugs and by building up portions of the damaged tube sheet. It was returned to service without further incident. Because concentration control was not affected within the system, there

was no additional damage to the tower, the distributor, the pump, or piping.

Future monitoring

One can understand the need to avoid nuisance alarms and interlocks and set some of the alarm points high enough above the norm to not be problematic. Reducing this margin was discussed but tabled. These are discreet activation points, thus no rate-ofchange data is considered and no comparison to statistical operation is done. One can understand that the margin in these discreet alarm points allows a boiler leak to build for some time before being noted by ratio or by concentration monitoring. Using this incremental time more effectively presents a window of opportunity for quicker response which is important to minimize boiler tubesheet repair. Better monitoring by way of AI is used across many industries. This same technology is currently being considered in sulfuric acid plants—specifically for HRS™ plants. AI does not rely on discreet alarm points but on semi-continuous observation of changes in operating data such as the ratios discussed here. The system could be designed to factor in the parameters that can affect the ratio and be able to differentiate between normal fluctuations and an HRS™ boiler or highpressure steam system leak. The future is still ahead. In the interim, the continued close observation of the concentration controls and water flow ratios is advised. q

Sulfuric Acid A S S O C I A T E S

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PAGE 19

Feature

CONTRACTORS’ CORNER

The next pandemic: skilled labor shortage

By: Ian Legg, Chemical Manager, CMW Inc.

Oh, how we all love the fall season. For some, it’s vacationing, watching the leaves change colors and of course, the holidays. But for most industrial contractors it is outage season—a time when many companies have their scheduled maintenance turnarounds, which require a lot of work in a short amount of time. This type of industrial work is accomplished only through hardworking, highly skilled men and women. The short or critical timeframes also require contractors to provide higher than usual worker volumes. In this article, let’s discuss the rising issues that many have warned and talked about for years but have seemed to fall on deaf ears. Today we are feeling the squeeze of labor shortages and it is likely affecting all contractors, industries, and owners alike. I will try to factor out the influence of politics and the Covid pandemic that affected us all and added to this downturn. Did you know that in 2022 over 50 million workers quit their jobs? And, no they didn’t all go on unemployment—47 million were job or career path changes and this was all age groups. Though I don’t have the data showing what careers were chosen, I can assure you most did not become welders, electricians, ironworkers, or other tradespeople. While there are many groups and efforts working to increase recruitment into apprenticeships, increase wages, improve benefits, offer training and better work life balance, I’m not sure these efforts are enough to entice newer generations to enter these fields in enough numbers to fill the deficit. Although technology and automation seem to come out every day and are great for increased efficiency, cost/time savings, and safety, cognitive ability and physical labor are still required. If you think back to your first job, whether you were running pipes for your plumber Dad, bartending your way through col-

PAGE 20

lege, mixing mud for a brick mason, or mowing grass, I guarantee there was a physical aspect and a thinking aspect necessary for you to learn and succeed. The bottom line is there is a job for everyone. But I believe that younger generations have had limited exposure to skilled labor or trade jobs. Here’s an anecdote to illustrate this: I recently asked a server in a restaurant whether he considered working in construction where he can earn more than the $3.55/ hour plus tips he told me he’s making. He told me no one ever asked him that and he assumed he had to “know somebody” to learn a skilled trade. I said, “well you have to show initiative to do something different and now you know somebody,” and I handed him a card to a local recruiter who can arrange an apprenticeship. I explained an apprenticeship would allow him to work while he learns and in two years make five times what he does now plus have benefits for his family. He said, “Thank you sir,” and I went on my way (leaving a good tip of course). My point is, younger people (or anyone needing a job) continue to remain uninformed about all the opportunities in our industries and every trade contractor needs to step up. We all must participate in outreach to increase the skilled workforce that is in serious decline and that we all urgently need. CMW assists the trade schools, local high schools, and trade unions with recruitment, training, prospecting, and donations of practice materials in hopes of adding another quality worker to grow our core employee base. As with any successful company, this is a long-term investment in creating well-rounded employees in their craft, training for long term experience, and retaining so companies can better weather the ups and downs and grow. I spoke to some colleagues in our own industry of weld-

Arc welding and steelworking are just two of many tradescrafts in high demand.

ing and plate fabrication and they all agree it has been a huge issue for some time. A friend of mine who owns a commercial electrical company said, “I have to limit and stall my growth because I need 20 qualified workers now just to cover what I have; and we have the door open to anyone willing to try and learn.” Another friend who manages apprenticeship training said, “We shortened the requirements and accelerated the training so they can get in faster. We offer the wages they are looking for and get them the opportunities quickly, yet the retainage rate is about 2 out of every 20-25 entrants.” This is another issue, and is how programs go away. There is an investment loss in training 20 people when only 2 remain in the industry. Over time this loss will diminish the efforts. I’ve also read recently that this is a huge problem in the medical industry. I’m sure you can figure out what that does—longer wait times and higher costs. In closing, all I ask is no matter what your affiliation— contractor, management, owner, or jobseeker—please assist, inform, educate, and encourage anyone seeking to get in a trade to do so. Trades build and maintain America, create opportunity for a high quality of life, and instill pride in a job well done. Consider this, if you’re sitting in your office: a concrete worker laid the foundation, a steelworker put up the building, a welder welded the seams, a plumber/pipefitter got water to the bathroom, an electrician got the lights on, a roofer keeps you dry, an A/C worker keeps you comfortable. If it wasn’t for all this skilled labor, you wouldn’t be there. If you need assistance or consulting on getting someone into a trade field, contact Ian Legg at iLegg@cmw.cc or (813) 365-2085. q

Sulfuric Acid Today • Fall/Winter 2023

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Feature

Minimize maintenance downtime with innovative design

The high-temperature gas streams common in sulfuric acid production pose mechanical design challenges throughout the plant. The cold end exchanger and interchangers are subject to these conditions. Understanding the potential failure mechanisms and employing rigorous design techniques is essential in increasing plant reliability and safety. Equipment failures can be prevented with attention to detail during the design phase. The innovative design of our AirBTU VPRR, variable pitch radial recuperator, high-temperature gas recuperator addresses the conditions seen with cold-end and interpass exchangers and eliminates the following failure mechanisms that lead to frequent maintenance: —Weld failures due to thermal expansion —Cold-end corrosion —Cold-end fouling —Flow restriction due to unexpected pressure drop Weld failures are typically caused by materials expanding at different rates. The most common are failures of the tube-tubesheet weld caused when some tubes expand more than others. Although a shell-side expansion joint is commonly recommended whenever the LMTD is greater than 150 degrees F, it does not compensate for tubes expanding at different rates. Instead, the variable pitch tube

PAGE 22

design is employed with the goal of uniform temperatures across the tubesheet, allowing each tube to expand at the same rate. In addition, our proprietary baffle and pass design directs the gas stream through the shell, using it to assist in obtaining the desired metal temperatures. Cold-end corrosion and fouling result from material temperatures lower than the dew point of the process stream constituents. During the design process, it is important to identify if and where those low material temperatures exist, and to incorporate features to eliminate their occurrence. In addition to the baffle and tube arrangements, annular inlet plenums can be considered. If the pressure drop through the heat exchanger is higher than expected, you may not be able to achieve your design flow rate. The reduction in flow rate will affect not only the performance of the heat exchanger, but your entire process resulting in a reduction in the rate of production. Therefore, a reliable method of calculation is critical. To this end, computational fluid dynamics (CFD) modeling is a necessary step in the design process. Using methods developed through years of experience, material temperatures are evaluated in all the critical areas. Tube pitch and baffle arrangements are modified until the desired temperature uniformity

and pressure drop are achieved. Wall temperature mapping is used to identify any locations where the temperatures fall below the dew point. The tube pitch, baffle design, and pass arrangement are evaluated. An array of design features developed through both design and operational experience are considered to determine the best solution. The final design will utilize the most effective solution with minimal cost impact. Following this methodology will significantly improve the overall reliability of the heat exchanger, resulting in 2-3 times the operating life when compared to commonly designed exchangers. Apart from sulfuric acid production, CG Thermal offers revolutionary design and material technologies for the dilution and processing of sulfuric acid. Our Umax® Advanced Ceramic heat exchanger is the primary vehicle for cooling the diluted acid for safe and proper storage and transportation. Boasting exceptional strength and durability, our Umax® tubes include a Lifetime Guarantee against corrosion and erosion. And if ever a tube should require servicing, the proprietary self-contained elastomeric sealing system allows for individual tubes to be easily removed from the heat exchanger using common tools. Because the Umax® heat exchanger is field repairable, servicing the unit can be done within one shift change, reducing downtime

AirBTU VPRR features a uniquely designed expansion joint that is pre-compressed to allow operation at “near neutral”, further minimizing the operating stress at the tubeto-tube-sheet connections.

and increasing production at the plant. The tight structure of the SiC ceramic tube material results in a smooth surface that is inherently resistant to fouling, which again equates to less downtime and more production uptime. With the addition of the United States Patented XD tubesheet, the Umax® SIC Advanced Ceramic shell and tube heat exchanger can be designed for pressures up to 150 psig at 400 degrees F. This tubesheet design can accommodate larger diameters, making this highly reliable design available for larger applications. For more information please visit www. cgthermal.com. q

Sulfuric Acid Today • Fall/Winter 2023

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Feature

Upgrades to sulfuric acid equipment: Advancements through the years

By: NORAM Engineering and Constructors Ltd.

In the beginning

In the mid-1700s, sulfuric acid was made in lead-lined wooden vessels through the reaction of sulfur dioxide, steam, and nitrogen oxides in what was called the lead chamber process. In the 1900s the contact process became prominent with the use of a vanadium pentoxide catalyst, which still forms the basis for sulfur dioxide oxidation and the production of sulfuric acid. In the past 60 years, sulfuric acid technology has progressed with three major improvements: • Materials of construction: from carbon steel and cast iron to stainless steels and high-silicon alloys. • Process: from single absorption to double absorption and low-grade energy recovery and SO2 scrubbing systems. • New equipment designs: radial flow gas exchangers, stainless steel converters with improved catalysts, anodically protected and high-silicon alloy acid coolers. Let’s look at improvements in the converter, acid system, and gas exchanger.

shape of catalyst created a high bed pressure drop. New technology advancements The increased availability and use of stainless steel in the 1980s revolutionized life as we know it. And this was especially pronounced in the design of stainless steel converters. The improved mechanical properties of stainless steel for operating temperatures encountered in converters of up to 1,200 °F (650 °C) significantly improved the converter designs with thinner walls, sealed division plates, internal exchangers, better internal support systems, and reduced maintenance.

Converter

Age old technology The proverbial heart of a sulfuric acid plant is the converter. Pre-1980, converters had thick carbon steel shells, heavy cast iron grids, posts (Fig. 1), and brick-lining in bed 1 and sometimes bed 2 used to lower the steel shell temperature to an appropriate limit for carbon steel. The thick shells were required to accommodate the strength reduction of carbon steel at the high operating temperatures. High temperature oxidation caused carbon steel flaking and subsequent fouling of downstream equipment, requiring metallizing of the first pass. However, the aluminum used in the metallizing would often flake off requiring periodic reapplication. A three-catalyst bed configuration was typical as most of the early acid plants were single contact, single absorption (SCSA) plants. Catalyst activities were much lower than today and the pellet

Instead of resisting thermal expansion, some new converter designs “embraced” it, by allowing the shell to grow radially without causing any significant stress to the structure through the use of curved “blooper” (or dished) plates and sliding vessel supports. NORAM’s ‘core-less’ design (Fig. 2) allows the use of the full crosssectional area of the converter bed avoiding the area lost to a core support. The result is a converter requiring less steel and a design that allows for fabrication of modules for easy shipping to site and site assembly.

Fig. 1: 1980s-era converter catalyst support with cast iron post and grids.

SO2 Conversion Catalyst also improved in leaps and bounds. Cylindrical pellets with high pressure drop and relatively modest conversion gave way in the 1970s to rings, and in the 1980s to what various vendors refer to as stars, ribbed, or daisy-shaped rings, with even further advances from 2010, including 3D printed catalyst introduced in 2022. In addition to shape improvements with lower pressure drop and an extended surface, the late 1980s saw the use of cesium promoted catalyst. This metal additive reduced the catalyst strike temperature improving the

PAGE 24

Fig. 2: New NORAM converter with catalyst support posts and internal hot exchanger (top two photos, 2018) and catalyst support plate in small converter (bottom photo, 2023).

equilibrium and conversion and went a long way towards serious emission reductions. Catalyst technologies are forever advancing, utilizing new design structures, shapes, and compounds with the goal to reduce stack emissions as low as possible within the converter. Double absorption During the 1970s and ‘80s double absorption arrived on the scene, partly in response to the U.S. Clean Air Act of 1970. With the addition of an extra converter bed, a couple of exchangers and another absorption system, emissions plummeted from thousands to hundreds of parts per million (ppm) SO2. Different configurations were used including two beds before the new interpass tower followed by one bed after the interpass tower, and this is known as a 2:1 double contact double absorption (DCDA) system. Similarly, there are 3:1, 2:2, and 3:2 configuration systems with the 3:1 being the most common DCDA system today. Double absorption allowed some plants to increase their SO2 strength to the first pass from 7-8% to 11-12% resulting in higher temperatures in the converter and hot exchanger further compounding the requirement to use stainless steel for these components.

Gas-to-gas heat exchangers

Heat exchanger design Over the past thirty years, gas-to-gas exchanger designs have improved tremendously. Advancements include materials of construction and the process design. Benefits of stainless steel In the good old days, hot exchangers, which see among the hottest temperatures in the plant, would be fabricated in carbon steel for the shell and the hot first pass gases would flow through tubes impregnated with aluminum (also known by the trade name Alonized). As with converters, hot exchangers are now mostly fabricated in 304 type stainless steel. Stainless steel’s high temperature strength and corrosion resistance make it an easy choice for this service. Even for cold exchangers, most clients are selecting stainless steel for its corrosion resistance and to help reduce sulfate fouling. Radial flow–circular design technology In the early days gas exchangers had shells crammed full of tubes (Fig. 3). After all, shells are expensive and why not fill them up with tubes? That design may work well in the oil and gas industry but for an industry dealing with large volumes of low pressure, high temperature, corrosive, and sometimes condensing gases, there is a better way. Technology providers devel-

Fig. 3: Old gas exchanger, left, vs. new Split Flow™ NORAM cold gas exchanger (2020).

oped the radial flow gas exchanger with no tubes in the center of the shell bundle or the periphery, and the gas flowed radially between the outer and inner shell portions. This arrangement greatly increases the shell film coefficient since all the tubes are in cross flow. Compared to double segmental shell configuration, the radial flow exchanger can have over twice the heat transfer coefficient, which results in fewer tubes, more efficient heat transfer, and greater thermal and mechanical symmetry. As a practical example, a conventional exchanger with 5,400 tubes, 20ft in diameter, and weighing 226t was replaced with a radial flow exchanger with 2,800 tubes, 16ft in diameter, and weighing only 126t without any loss in heat transfer capability. Keeping the cold exchanger hot Cold exchangers can get cold. Too cold. Especially in the zone of the exchanger where the cold SO2 gas is in thermal contact with the cool SO3 gas. In this area condensation can occur which, especially in carbon steel exchangers, leads to sulfate formation that can clog the shell and tubes. Various approaches have been tried to address condensation with moderate success including sacrificial heat exchangers, bimetallic tubes, and thicker tube walls to allow more corrosion resistance. In the 1990s NORAM patented the radial flow hot sweep feature where a portion of the hot shell gas is internally directed to the cold tubesheet. A warm tubesheet prevents condensation, is dry and sulfate-free. The hot sweep feature is also used in SO3 coolers to greatly reduce the recycle air flow necessary to keep the cold end above the dewpoint. For preheaters, we turn a hot sweep to a cold sweep and we can significantly improve the thermal efficiency of the preheat exchanger.

Acid systems

Large diameter towers Early towers were carbon steel and Sulfuric Acid Today • Fall/Winter 2023

Cast iron coolers The acid piping systems at that time were cast iron and the early-day acid coolers were comprised of cast iron pipe sections with an external water-spray. These coolers were called cascade coolers or, because their convolutions looked like a musical instrument, trombone acid coolers (Fig. 8). They were prone to corrosion leaks requiring frequent acid plant shutdowns.

Feature

brick-lined with small-size packing, often installed in increasing sizes from bottom to top. Pall, Raschig, and cross partition rings were common packing materials prior to 1970. Old towers often featured low irrigation rates, cast iron trough acid distributors, and mesh pads for mist elimination. With the small-size packing, large diameter towers were required to keep the pressure drop from getting too high. The towers were brick-lined up to the distributor level, in some cases with flat floors to support the brick arches needed for the Aludur beam packing supports. After some years, acid leaks would develop on the tower bottom caused by lining failure from the high point loads of the brick arches on the floor. The tower shell section above the distributor was fabricated in carbon steel where the inevitable acid mist would result in large sulfate formation fouling the top of the acid tower.

Fig. 5: Trial assembly of a new NORAM SX SMART™ pipe distributor with external clean-out ports (2019).

Fig. 4: New (2023) NORAM SX® acid tower during installation.

which eliminates sulfate formation keeping the top section nice and clean. Tower packing is now typically a 3-inch ceramic saddle. Low pressure drop saddles such as NORAM’s HP™ saddles (Fig. 9) as well as structured ceramic packing offers further improvement in the process. With the same or better mass transfer capability, NORAM’s HP™ (high performance) packing has significantly lower pressure drop when compared to conventional 3-inch standard saddles and allows increased gas throughput or less energy consumption for the same gas flow. Modern distributors are now fabricated in long-lasting, high-silicon alloys in trough (Fig. 6) or pipe format. NORAM’s SMART™ pipe distributor (Fig. 5) permits distributor cleanout from outside of the tower negating the need for tower entry to remove chips. This feature provides a large step forward in plant safety, eliminating the requirement for plant personnel to enter the tower in cumbersome acid resistant PPE and, in some cases, supplied breathing equipment to clean a plugged distributor.

For mist elimination, mesh pads in absorbing towers have been replaced with candles, such as Brownian diffusion or impaction, which reduce acid mist carry-over down to the submicron level. Acid coolers have undergone a tremendous change from cast iron trombone (Fig. 8) to anodically protected shell and tube exchangers. Converting to anodically protected coolers resulted in a significant increase in acid plant on-stream time. And now high silicon alloy (such as NORAM

Fig. 6: New (2023) trough-type distributor in NORAM SX® with NORAM HP™ packing.

Sulfuric Acid Today • Fall/Winter 2023

Fig. 7: Modern shell and tube acid cooler in NORAM SX® high silicon alloy (2021).

Future success relies on continuous improvement

Fig. 8: Trombone acid cooler (circa 1985).

Modern new age materials Today’s acid system has improved significantly in all areas. High silicon alloys (such as NORAM SX®, ZeCor, Saramet) are now available for use in the lower tower section eliminating the need for brick-lining and permitting replacement in the same location within a two or three week shutdown (Fig. 4). Where brick lining is still required, self-supporting brick domes can be used. Brick domes eliminate the need for brick support arches and allow a dished bottom without point loads and an inherently more reliable shape. Above the acid distributor level, 316 stainless steel is used,

SX®, Fig. 7) permits operation without anodic protection, which reduces the maintenance cost and eliminates the need for spare parts associated with anodic protection. Ductile iron piping systems are being replaced with high-silicon alloys with the benefits of largely eliminating flanges and their potential leaks, reduced weight, reduced wall thickness, higher allowable velocities, and significantly higher erosion resistance. Heat recovery systems are available that can convert the heat lost to cooling water into low to medium pressure steam. And new SO2 scrubbing systems using regenerative solvents are gaining popularity.

Fig. 9: Higher gas flow with HP™ low pressure saddles compared to standard packing.

Converters, catalysts, gas exchangers, and acid systems have all made tremendous improvements in performance, operability, and reduced maintenance over the past 60 years. These changes have come through material upgrades, design improvements in equipment and systems, and new products. NORAM Engineering and Constructors Limited performs engineering studies for plant equipment upgrades, debottlenecking, and plant capacity increases. NORAM supplies world class equipment for sulfuric acid plants and can be reached at sulfuric@noram-eng.com, or (604) 6812030. q PAGE 25

Feature

PROX-SVERS vs quartz rock for sulfuric acid conversion reactor ®

Sulfuric acid is produced by reacting sulfur trioxide (SO3) with weak sulfuric acid. The SO3 for this reaction step is produced by conversion of SO2 to SO3 across a fixed catalyst bed. Like most fixed bed reactors, the SO2 conversion reactor requires catalyst support media and catalyst hold-down media to prevent catalyst loss. Traditionally, the sulfuric acid industry has used quartz rock to perform this function. However, recent trends are seeing more plants beginning to use ceramic support balls instead. Historically, one of the primary advantages of quartz rock over ceramic support balls has been cost. However, with the price of quartz rock increasing, the cost difference between the two products has narrowed in recent years. In mid-2019, the difference dropped to less than 25 percent; a difference that is easily overcome by the advantages of ceramic support balls. Ceramic support balls have three primary advantages compared to quartz rock: • Improved manufacturing and quality standards • Reduced pressure drop • Ease of handling and screening during maintenance activity

Quartz rock is a naturally occurring substance that is collected, cleaned, and sorted before being selected for use in sulfuric acid applications. Because it’s naturally occurring, a single bag of quartz rock can have pieces with wide variances in shape and size. Inconsistency in size and shape can lead to issues with gas distribution and channeling in the catalyst Fig 1: Inconsistency bed. Additionally, of materials, size and because the ma- shape in a single bag of terial is naturally quartz rock. occurring rather than manufactured, there is an increased likelihood of contaminants being present. Fig. 1 shows the size/shape inconsistency and a piece of wood or other refuse that was found in a bag of quartz rock. Christy Catalytics’ PROX-SVERS® ceramic support balls are manufactured to precise tolerances and provide a consistent

Fig. 2: PROX-SVERS® demonstrated significantly lower pressure drop than quartz rock.

size and shape for improved performance. Additionally, our products are carefully inspected before packaging to help ensure that no contaminants are present. In addition to improved manufacturing quality, PROX-SVERS® also provide improved pressure drop performance when compared to traditional quartz rock. In testing, pressure drop was measured across a 65” tall bed of support media. Two sizes of quartz rock and four sizes of PROXSVERS® were tested at three different air flow rates. The most common PROXSVERS® sizes used in this application are 1 inch and 1.25 inches. While the two sizes of quartz rock

showed almost identical performance, the PROXSVERS® demonstrated significantly lower pressure drop for all sizes tested. Pressure drop improvements ranged from 20 percent for ¾-inch support balls to 64 percent for 1.5 inch support balls. Fig. 2 shows the test data. Based on this data, sulfuric acid plants that are limited by pressure drop in the conversion reactor could experience significant production improvement by switching to PROX-SVERS® ceramic support media for their bed support and hold-down media. For more information including data sheets on Christy Catalytics T-86 PROXSVERS®, visit www.christycatalytics.com or call 314-773-7500. T-86 PROX-SVERS® are marketed globally through a wide network of sales agents and distributors. q

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Anzeigen stills SulphuricAcidToday.indd 1

PAGE 26

14.09.2023 08:40:05

Sulfuric Acid Today • Fall/Winter 2023

ALPHA-CORR TYPE III ACID BRICK

AvAilAble in the USA todAy From our strategic location in Houston, TX, we are able to supply a variety of brick shapes (straights, arches, wedges, keys) and sizes from stock for immediate purchase. Please reach out to us for technical data and pricing. Samples available upon request. Meeting ASTM C279 standards for use in new construction and refurbishment of existing structures in sulphuric acid plants including towers, process vessels, floors, sumps, pits, etc.

A-103 MASTIC® A-103 Mastic® is Still Available and in Stock in warehouses in USA and Canada. Made from the original recipe. When your plant has a product that has proven successful for over forty years, why change? With this in mind, Alphatherm Inc. purchased the recipe of Pecora A-103 Mastic® to keep this integral piece of the Sulphuric Acid Tower lining system intact. Made from the same ingredients with A DECADES OLD RECIPE, A-103 continues to be the workhorse membrane in Acid Plants worldwide. Industrial Linings for Sulphuric Acid Plants. Absorption Towers, Pump Tanks, Sulphur Pits, Secondary Containment, Acid Resistant Linings.

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| Tel: (905) 948-9949 | Email: alphatherm@ilap.com

Department

PRODUCT NEWS

Reliability by Design. Avoid cold-end corrosion and fouling Eliminate stress failures Minimize pressure drops Maximize thermal efficiency

AirBTU.VPRR

High Temperature Gas-to-Gas Recuperator

Steuler QUICKFIT New construction and replacement of defective equipment and components is inevitably time-consuming and reduces productivity. With QUICKFIT, Steuler ensures a completely smooth process when installing plant components. Steuler plans, produces, and delivers ready-to-connect plant parts or plant components using the QUICKFIT process. Steuler QUICKFIT reduces downtime because plant parts are manufactured in parallel with the customer’s ongoing operations. The installation of the new plant components is later perfectly fitted on-site. Steuler takes care of the entire logistics up through commissioning, saving customers valuable production and project implementation time. This makes customer projects much more cost-effective and reduces customer effort in implementation.

fect adhesion of the anti-corrosion lining applied immediately on top. The complete prefabrication takes place in the Steuler plant. In this way, Steuler reduces downtime and new construction time, allowing customers to maintain productivity.

A team of experts for everything

On-site installation: fast, flexible & on schedule

Steuler performs all manufacturing steps according to individual customer requirements, from steel construction with pre-treatment to rubber coating or interior coating with subsequent brick lining as well as exterior painting to safe transport. This also applies to the production of complete components including piping made of thermoplastics, glass fiber-reinforced plastics or stainless steel, as well as the production of spray nozzles made of thermoplastics, glass fiber-reinforced plastics, stainless steel, titanium, or ceramics. Steuler provides a single source for plant components, all coordinated through one contact person who takes care of everything.

Perfect protection tailored to customer requirements.

Design and fabrication

Providing solutions for corrosive and high-temperature gas streams in the Sulfuric Acid industry. PAGE 28

Steuler supplies all the steelwork for process equipment, vessels, and fittings. Steuler also provides the design of the structure and components. As part of the process, Steuler takes into account the transport requirements of the heavy components.

Application of anti-corrosion lining

Each piece of equipment is treated for corrosion protection. Steuler cleans and blasts all relevant surfaces. This ensures per-

Brick-lined equipment delivered and ready for service.

Steuler coordinates all on-site construction activity. The result: less downtime and shorter business interruptions. Equipment and components are replaced safely and quickly. The ready-to-connect plants and components are delivered directly to the construction site. Experienced Steuler professionals specializing in installation and site management control the on-site construction up to the final installation and handover.

Steuler surface protection linings

To protect components and surfaces made of concrete or steel, Steuler uses the right materials and technologies, making equipment durable and safe so that plants can reliably withstand even the highest chemical, physical, and mechanical stresses. Whether for new construction or repair, Steuler develops effective protection systems that are precisely tailored to individual requirements. Steuler’s materials portfolio includes coatings, rubber linings, brick linings, and claddings for all areas of industry, trade, and commerce. This is supplemented by mechanically anchored thermoplastic and steel linings. Each product group serves the market with precisely-fitting technologies and high-quality solutions. Together they form a unique unit for comprehensive sector solutions or specific industrial areas. Everything originates from a single supplier—coordinated and harmonized, engineered and implemented—for a wide range of industries as well as specialized applications. Like a tailor-made suit, Steuler develops corrosion protection linings to fit the specific project. The focus is on specific geometries, application-related specifications, and maximum durability under chemical, physical, and mechanical loads. Steuler combines materials and technologies to create safe and comprehensive solutions. For more information, visit www.steuler.de q Sulfuric Acid Today • Fall/Winter 2023

Feature

Which expansion joint should you use: how to pay less attention to your expansion joints By: CJ Horecky, Executive Director, INTEREP, Inc.

Expansion joints, nobody cares about them—except me I suppose. It works out in the end though because you all end up calling me when they finally rise to the attention threshold, at which point something very bad has usually happened. In this article, however, I will seek to help you prevent those situations through some offensively basic tutelage about piping and ducting expansion joints; starting with what they are, moving onto which ones are best suited for which applications, and finishing with the best practices for acid plant expansion joint layout. If you can remember the basics of these three things, you’ll be able to spot an impending problem with your expansion joint applications, and hopefully avoid the emergency phone call to INTEREP.

towers, you may see fabric expansion joints. The bottom line: if your piping never moves, grows, or rattles, you don’t need expansion joints, so get rid of them!

designers might unknowingly introduce to their plant, especially when an overzealous expansion joint vendor is involved in the design process. We’re talking about things like broken nozzles on vessels, broken pipe anchors, acid condensation and pooling, equipment being literally ‘pushed over’ by nearby expansion joints, etc. Again, nobody cares about expansion joints, so weird accidents are caused by them every day.

Must you use expansion joints?

Now, since your piping grows (and it grows a lot) you’ve got two choices. 1) absorb all of that thermal growth via pipe loops (not geographically feasible) or 2) use expansion joints. Since you’re stuck with the expansion joints, I’ll try to make this as painless as possible. You must have expansion joints in an acid plant, but you mustn’t have them scattered haphazardly all over the place. In fact, expansion joints cause a whole host of problems that engineers and piping

Can you use flanged & flued Ejs all the time?

If you look at Fig. 1, you’ll see that flanged and flued metal expansion joints are pretty much the gold standard when it comes to ease-of-maintenance in an acid plant. However, they’re incredibly stiff and can

What is an expansion joint?

In an acid plant, an expansion joint exists almost solely to mitigate thermal growth of your piping and ducting systems; and it’s almost always a metal expansion joint. However, you also have rubber expansion joints on your pump connections (those provide other benefits, see Fig. 1). And on some large diameter ducting around your

Fig. 2: INTEREP flanged & flued heavy wall universal expansion joint.

Fig. 3: INTEREP 2-ply testable metal bellows design.

Fig. 1: INTEREP expansion joint comparison. TYPE OF EXPANSION JOINT

APPLICATION

MOVEMENTS Excellent Good Poor None

COST (1-5)

CORROSION RESISTANCE

TEMPERATURE RESISTANCE

METAL FLANGED AND FLUED

Large diameter ducting with very low thermal growth

Axial Lateral Angular Torsional

3 (bolstered by thickness)

METAL BELLOWS

Areas where flanged and flued cannot handle required movements or areas where extremely high reliability is required

Axial Lateral Angular Torsional

RUBBER

Pump connections, piping where moisture & corrosion is severe (FRP, scrubbers, etc)

Axial Lateral Angular Torsional

FABRIC

Hot gas ducting where movements are extreme or unpredictable, and moisture is low to medium

BRAIDED HOSE

Fuel line connections where rubber hose is unacceptable

PAGE 30

PROS

CONS

100% leak-tight, robust, durable, repairable

High stiffness (spring rate), low movement, corrosion-prone

3 (bolstered by ability to use rare alloy sheet at lower cost)

100% leaktight, medium movement, can be monitored for leaks and built with redundant internal containment

Less robust than flanged and flued, require experts for field-repairs

5 (100% seal with no exposed metal)

100% leak-tight, medium movement, 100% chemical resistance

UV-susceptible, 400F max temp

Axial Lateral Angular Torsional

4 (PTFE is 100% corrosion resistant, but flanges are not)

High movement, field-repairable, can be stocked and cut for urgent repairs, higher temp than rubber, no pressure-thrust or stiffness

Not suitable for >3psi, slight leakage at flanges, labor intensive install

Axial Lateral Angular Torsional

3 (bolstered by ability to use rare alloy sheet at lower cost)

Inexpensive, easy to install

Cannot be restrained, often installed improperly, cannot visually inspect due to braided cover

introduce huge spring constants on nearby nozzles and connections. If you could use them everywhere, you probably still would, but they’ve got a couple of major downsides. Primarily, they can barely handle any movement. Anything that’s easy to weld is hard to move, and expansion joints are supposed to move. Please, don’t just throw flanged and flued expansion joints into your ducting without having us run a quick calculation for you on what sort of movements they can handle, so you can avoid buckling your ducting, repeated cracks at nearby flanges, and other fun things like that. Secondarily, flanged and flued EJs aren’t great if you want to know what’s going on inside the expansion joint. If you need to have active monitoring and redundant containment, you’ll need to go with a 2-ply testable metal bellows expansion joint, like in Fig. 3. These are the gold standard for catalytic cracking units in oil refineries because they offer no surprises, hide no secrets, and give you total control. They also cost a lot…but not as much as they save in unplanned downtime!

When should you use metal bellows?

Since you can’t run flanged and flued everywhere, you’ve gotta have some metal bellows expansion joints. I know, you hate them because when they fail, you’re screwed. Well, not quite screwed, but you’ve gotta call INTEREP to come out and do a field-repair and it’s not cheap. Unless you’re looking for high-reliability monitoring like the oil refineries do, then try to avoid metal bellows except where you have to have them, which is anywhere that you need lateral movement or significant axial movement. Send us your piping layout and thermal growth calcs and we’ll shoot you straight on whether you’re stuck with metal bellows or not. In most cases, if you’ve already got bellows, they’re there for a reason, and you’re stuck with them.

Fig: 4: Field repair on 310 stainless (.030”). Sulfuric Acid Today • Fall/Winter 2023

Before we move onto the other types of expansion joints that you care even less about, let’s talk movement types (see Fig. 5). As I mentioned, metal bellows are best suited for places where you have lateral movement or significant axial movement, especially in a short distance. A single expansion joint (of any type) can handle very little lateral movement, since lateral is out of plane (it causes compression on one side of the EJ and extension on the other) and will cause the expansion joint convolutions to touch. For this reason, a single flanged and flued expansion joint cannot handle lateral movement. If you want to take up lateral with a flanged and flued, you’re going to need a long center spool. Oh no, now we’re getting into expansion joint components, and I haven’t even finished talking about movements! Hold your questions, we’ll get there next.

some folks who we all know well who are based in St. Louis, MO. It works great if space allows, but you can see in Fig. 7 that it takes a lot of center spool to get a little angular movement (unlike the misleading sketch in Fig. 6 shows). All right, so that’s lateral, the bottom line: handle it with a center spool, handle it with a metal bellows expansion joint, or don’t handle it at all.

AXIAL COMPRESSION

The two flanges come toward one another (face-to-face overall length shrinks along the axis)

AXIAL EXTENSION

The two flanges move away from one another (face-toface overall length grows along the axis)

LATERAL (TRANSVERSE)

The two flanges move outof-plane from one-another (perpendicular to the axis)

ANGULAR

The two flanges move away from one another on one side of the axis, and toward one another on the other side Self-explanatory, vibration isolation is only achieved via rubber or fabric expansion joints

How to turn lateral pipe movement into angular

By adding a center spool in between two expansion joints, you create a long lever allowing for each expansion joint to angulate, translating lateral movement that would have been on one EJ into angular movement across two EJs. This is a very common design used by

Fig. 6: Lateral movement turned to angular movement with two bellows. Sulfuric Acid Today • Fall/Winter 2023

• Synonyms: convolution, con, corrugation, convolute, volute, flexible element • What it does: Takes up movement (this is the heart of the EJ)

Center spool

• Synonyms: spool, pipe-spool, pipe nipple, pup • What it does: Connects two bellows to act as a lever, turning lateral to angular

• Synonyms: tie rods, limit rods, hinges, gimbals, rods, control units • What it does: Restricts the movement of the EJ to one or more planes

Fig. 5: Expansion joint movements.

VIBRATION

Bellows

Restraining hardware

Fig. 7: Long center spool + 2 bellows used to turn lateral to angular.

Why are there so many names for the same thing?

Now let’s talk about the components of an expansion joint. I think it would probably help if we standardized some of these terms in the acid world, because you’ve all heard six different phrases for each one. Here’s my version (see Fig. 8).

Flow liner(s)

• Synonyms: deflectors, liners, shields • What it does: Protects the bellows from abrasion and accumulation of process media

Bellows cover(s)

• Synonyms: dust cover, dust shield • What it does: Protects the bellows from exterior damage (dropped objects, UV, etc.)

Fig. 9: Three-pin hinge design at sulfuric acid plant.

bellows see only angular movement. This means that when you’re running a bellows design analysis, you can run non-concurrent movements and achieve far better life cycle calcs than if you had to take up all these movements with only one or two bellows. This is done by putting a hinge on each bellows so that they can only angulate. Any axial movement is pushed directly onward through them, while any lateral movement is taken up as angular movement across the 90-degree corner. The diagram in Fig. 10 gives you a feel for the various ways that this can work to your benefit. The bottom line is that this design will put zero load on your nearby vessels and nozzles and is almost idiot proof (so long as you have a professional expansion joint designer approve it first—just in case.

Cavity pillows

• Synonyms: insulation pillow, accumulation pillow, stuffing • What it does: lowers temperature seen by bellows, prevents dust build-up inside

2-Ply pressure gauge

• Synonyms: test port, turkey popper, red top, monitoring device • What it does: Allows for predictive failure monitoring of both plies of a metal bellows

Braided seal

• Synonyms: N/A • What it does: 3rd layer of defense against particulate intrusion to bellows convolutions There are many more components that an expansion joint can include, but these are the basics of metal expansion joints, which are most of the EJs in your acid plant. Now that you’re familiar with this, and with types of movement, let’s talk about the magic expansion joint design for acid plants.

The magic of the three-pin hinge design

Fig. 8: Common components of an INTEREP expansion joint.

Feature

What movements can an expansion joint handle?

A “three-pin hinge” expansion joint design takes advantage of the same principle that a pipe-loop does, while minimizing space. By turning a corner with your piping and putting two bellows on one leg of the pipe segment, and one on the perpendicular leg, you can take up both axial and lateral movement in your piping system while your

Fig. 10: 1 hinge + 2 gimbals = 3-pin hinge capable of lateral movement in two planes.

Too long, didn’t read

Here’s the summary: Use metal expansion joints everywhere that you need EJs, use rubber where that won’t work due to higher movement needs, and use fabric where that won’t work due to higher temperature demands. Use flanged and flued EJs everywhere you need metal expansion joints, but make sure that you’re using a 3-pin hinge design, or you’re likely to break something. Don’t just put in flanged and flued expansion joints that are “like-in-kind” or “build to print” unless you know your pipe-growth calculations. When you can’t use a 3-pin hinge, it’s time to talk to us about using some clever restraining hardware or metal bellows expansion joints. For more information, visit www.INTEREPinc.com or contact CJ at 480-5009161 or cjh@interepinc.com. CJ will also be at the Sulfuric Acid Roundtable at Omni Champion’s Gate, Orlando, FL, April 2225, 2024. q PAGE 31

Feature

Mechanical and hydraulic vibrations in vertical chemical pumps By: Marwan Karaki, Sales Manger, Weir Mineral Lewis Pumps

There are many benefits to using a vertical pump to transfer molten sulfur, sulfuric acid, and phosphoric acid. These types of pumps promote a safer operational environment as the vertical design eliminates pressurized seal area concerns and the fluid pumped never touches the shaft stuffing box. However, there are considerations to be made before choosing a vertical chemical pump. To better understand the issues with vertical chemical pumps, it is important to explore common concerns of the pump system. While each company extensively tests their pumps prior to shipment, many factors can affect the effectiveness of the pump. Such factors may include the type of fluid being pumped, fluid temperature, pump speed, operation schedule, and maintenance/turnaround schedules. Regardless of the industry, vertical chemical pumps may experience complications from unintentional vibration. The most common causes of pump vibration can be categorized as either mechanical or hydraulic.

Cavitation damage to an impeller.

Mechanical vibration

Pump alignment It is very important to have all critical pump components aligned properly, particularly the shaft column, discharge pipe, and volute. Before installing a pump and after all pump maintenance, a freedom of rotation test should be performed by suspending the pump vertically and manually turning the shaft to determine if any interference exists. After installation, the forces and moments at the flanged connections should be maintained within allowable margins to eliminate distortions that may cause rubbing of rotating parts where clearances are reduced or even eliminated. Shaft straightness The pump shaft must be maintained as straight as possible at all times. Straightness must be checked at major overhauls or when the shaft assembly is rebuilt, even if there is no vibration. When mounted between cenPAGE 32

ters in a lathe, the run-out at critical points such as the midpoint of shaft bearing assemblies and the impeller location should be within 0.002 inches Total Indicator Runout (TIR). Vibration frequency owing to the degree of shaft straightness ranges from onetime rotational speed to occasionally two- to three-times rotational speed. The amplitude is typically 150% of radial vibration in the axial plane. Unbalanced impeller The impeller is a major rotating mass in the pump that, if unbalanced, may result in high vibration. All Weir Minerals Lewis® impellers are dynamically balanced to ISO standard 1,940/I Grade 6.3 or better, depending on customer specifications. Impellers in both sulfur and acid environments may face rough conditions that lead to impeller imbalance. In sulfur environments, a foreign object might hit the impeller at high speed and result in damage that causes imbalance. In an acid environment, an impeller may suffer from uneven areas of erosion or corrosion that result in imbalance and significant pump vibration. Selecting the appropriate material is critical to avoid such situations. In general, the vibration frequency in this instance is equal to the rotational speed. Amplitude is greatest in the radial direction with a magnitude that is proportional to the amount of imbalance. Bearing lubrication The majority of Lewis® vertical chemical pumps are supplied with a shielded, double-row ball bearing of maximum capacity design intended to handle the applied hydraulic and mechanical loads properly. It is important to have the bearings replaced with OEM parts and to rigorously follow the pump manufacturer’s lubrication instructions. Proper installation of the bearing to both the shaft and the ball bearing housing is critical. The vibration frequency related to bearings is equal to the rotational speed times the number of rolling elements, and amplitude is proportional to the damage and wear of the bearing. In addition, it is well known that amplitude increases with time.

plates should be levelled and sufficiently robust. The components should be carefully examined after several years of service since they have the tendency to lose their rigidity and distort, thus contributing to major pump vibration. Misaligned plates prevent the pump from being properly rebuilt and aligned. Pump motor alignment In some cases, abnormal vibration and mechanical performance can be derived from poor alignment between the pump and the motor. The misalignment of the coupling has no direct effect on motor efficiency; however, correct alignment will ensure a smooth, efficient transmission of power from the motor to the pump. Misalignment takes place when the centerlines of the pump and the pump shaft are not in line with each other. Misalignment can cause the following symptoms: excessive vibration, increased bearing temperature, and shortened bearing or coupling life. There are three types of misalignments to look for: - Angular misalignment: occurs when the motor is set at an angle to the pump. If both shafts are extended, they will cross each other. - Parallel misalignment: occurs when the motor and pump shafts are parallel to each other. - Combination misalignment: occurs when the pump and motor shaft suffer from an angular and parallel misalignment.

Hydraulic vibration

Cavitation Cavitation occurs when the NPSHr is greater than the NPSHa. This causes an implosion of vapor bubbles formed in the liquid being pumped, usually on the lowpressure side of the impeller vanes. Cavitation can result in damage to the impeller by removing particles of metal from the surface with explosive force. This causes several problems, including discernible pump vibration. Most of the time, this condition takes place when there is a change in the

Motor/driver The motor/driver may generate some vibration caused by a worn bearing or an imbalanced rotor. If supplying your own motor, it is recommended to run the motor isolated from the pump to determine if there is any vibration caused by the motor. If the motor is new, it is highly recommended to request a routine test that will lead to testing and certification by the motor manufacturer. Baseplates Vertical pump cover plates and sole

system characteristics that alter the pump flow and head conditions for which the pump was originally selected. Hydraulic imbalance Suction conditions may exist that cause the flow distribution of liquid entering the pump impeller to be uneven. This can result from vortexing, improper clearances under or around the pump’s suction inlet, or gas entrainment. The effect can be much the same as cavitation due to insufficient NPSHa. Vibration monitoring Vibration monitoring is fairly common today. Accelerometer probes are usually installed on the pump’s upper thrust bearing or on a motor bearing. Measurements in at least two horizontal planes, located 90 degrees apart, and in the vertical plane can be made for vibration amplitude and frequency. A log of these readings can be useful in both helping to discern the beginning of component wear before failure and in identifying and remedying an installation problem. It is perhaps less important to focus on the magnitude and exact frequency of vibration (unless it is extreme) than it is to pay attention to a change in the signature or pattern of the vibration spectrum. Be aware that it is nearly impossible to completely eliminate all pump installation vibration. ANSI/HI-9.6.4-2001 edition, Centrifugal and Vertical Pumps, Vibration Measurement and Allowable Values, provides a guideline for the acceptable level of vibration depending on the pump structure. However, with knowledge of vibration sources, a good maintenance program and installation procedures, and perhaps a monitoring system, pump vibration can be controlled and serious problems can be avoided. While vertical chemical pumps are an excellent choice for transferring molten sulfur, sulfuric acid, and phosphoric acid, important considerations should be made before choosing a vertical chemical pump. Unintentional mechanical or hydraulic vibrations may result in complications and affect the pump’s effectiveness. It is crucial to take preventative measures to ensure the proper alignment of critical pump components, maintain a straight shaft, have a balanced impeller, have OEM bearings with proper lubrication, and have good alignment between the motor and the pump. Proper pump selection, installation, and maintenance are necessary to achieve the best performance and longevity of vertical chemical pumps. q Reference:

Checking for shaft straightness–a common cause of pump vibration.

Sulfuric Acid Today • Fall/Winter 2023

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INSTALLATION SYSTEMS

Feature

New CIRAMET PLUS™ for most challenging service: seawater acid coolers

Chemetics® is pleased to introduce CIRAMET PLUS™ austenitic stainless steel to lead the CIRAMET® family of special steels for use in the critical components of Chemetics’ anodically protected seawater sulfuric acid coolers. Few developments in the manufacture of sulfuric acid can eclipse the importance of the Chemetics anodically protected sulfuric acid cooler. First introduced in 1967 by Chemetics’ parent company Canadian Industries Limited (CIL) and popularized in the 1970s and 1980s, the Chemetics design revolutionized the conventional method of acid cooling and continues to set the global standard for reliability and performance. Developed from the need to improve plant reliability, the CIL cooler, as it was once known, revolutionized conventional methods of acid cooling, led to uninterrupted operation, compact plant layouts, vastly reduced maintenance, greatly improved acid plant reliability, and the ability to recover valuable low-grade energy. As the originators and leaders in acid cooling technology, Chemetics has continued to introduce developments in anodic protection, thermal and mechanical design, manufacturing methods/techniques, as well as materials of construction.

Acid coolers in original 1970s-era Chemetics shop.

Chemetics acid coolers are fully designed and fabricated in a state-of-the-art facility located in Pickering Ontario, Canada. The facility is owned and operated by Chemetics, ensuring complete control of quality and schedule. Many of the fitters and welders have continuously worked on Chemetics acid coolers for their entire careers (40+

Acid cooler tubesheet shows extreme damage from seawater attack, and subsequent repeated repair attempts. PAGE 34

years). This unparalleled know-how and experience results in the highest possible weld quality which in turn allows for the industry’s most robust, reliable, and safe acid cooler. Chemetics also stocks significant quantities of acid cooler materials (tubing, plate, ANOTROL® electronics, etc.) with tubing made to Chemetics’ specifications to maximize corrosion resistance. In-house fabrication combined with stock materials allows for competitive pricing and fast delivery times. The demand for Chemetics equipment and its high level of fabrication quality has continued to increase globally. To meet this increasing demand, Chemetics is presently investing in a major expansion to the Pickering fabrication facility to be completed in 2024. Since the introduction of the original stainless steel anodically protected acid cooler, Chemetics has also developed proprietary materials and designs to address various applications and challenges. These materials include SARAMET® developed by and proprietary to Chemetics. SARAMET® is available in multiple grades (SARAMET 23, 25, 28, 35, HT™ and HT™+) which allow acid coolers to operate without anodic protection due to SARAMET’s exceptional corrosion resistance in hot sulfuric acid, with HT and HT+ grades specified for higher temperature energy recovery applications. Additionally, Chemetics developed proprietary CIRAMET® allowing for acid cooling with water containing various high levels of chlorides, from brackish water to seawater. Now Chemetics has introduced CIRAMET PLUS™ to support clients with the most severe seawater quality challenges. With this vast range of material options, Chemetics can offer anodically protected acid coolers to handle any possible type of cooling water. Typically, acid cooler failure is most often driven by water-side issues rather than acid-side. When operating acid coolers with seawater cooling, the chloride attack can be addressed by proper selection of material for waterside corrosion resistance. Chemetics successfully addressed this challenge with proprietary acid cooler design features and with the development of the original CIRAMET® alloy, with many acid coolers installed since 1977 in over 15 countries. In most cases, a CIRAMET® seawater acid cooler can last decades. However not all seawater is equal. In addition to the chloride content, seawater brings additional challenges related to biological activity, and even pollution. Ocean temperatures and biological content can vary significantly in different areas. There is a clear trend that tropical/warm seawater can have the strongest negative impact on acid coolers. In many cases, seawater is continuously treated with chlorine to control levels of biological material entering the system. But it can be tricky to find the correct balance between under-and over-chlorinating. When under-chlorinating (or not chlorinating) various organisms can easily set up shop on the surfaces of the water channels and inside tubing where the conditions seem to be just right for them to proliferate. In extreme cases, various shellfish (clams, mussels, barnacles, etc.) will grow and create a potential for under-deposit corrosion to occur. This can also restrict waterflow to the tubes causing tube-wall temperatures to increase, trigger corrosion in the form of acid attack on the outside diameter, and accelerate crevice and pitting chloride attack on the inside diameter. When over-chlorinating occurs, the chlorine and chlorides combine to aggressively attack the steel which leads to rapid acid cooler failure.

Chloride pitting on CIRAMET® acid cooler tube due to over-chlorination.

904L Acid Cooler Tube-end weld with chloride pitting corrosion from seawater.

Chloride pitting on alloy 2205 acid cooler tube from brackish water.

Barnacles growing on CIRAMET® acid cooler tube. Sulfuric Acid Today • Fall/Winter 2023

required corrosion performance in hot sulfuric acid. Compared to other alloys used for this service, CIRAMET PLUS™ demonstrates lower acid-side corrosion rates when anodically protected in concentrated sulfuric acid. A qualitative method for predicting the susceptibility of alloys to chloride pitting corrosion is the Pitting Resistance Equivalent Number (PREN), which is calculated based on the chromium (Cr), molybdenum (Mo), and nitrogen (N) content of an alloy. PREN is commonly used to rank the susceptibility of stainless steel and nickel-base alloys with the formula: PREN = %Cr + 3.3 (% Mo) + 16 (% N). Larger numbers indicate higher resistance to pitting corrosion. By comparison the PREN of 304L is 19-23 and 316L is 23-28; whereas CIRAMET® has a PREN of 44-49 and CIRAMET PLUS™ has an increased PREN of 50-58. Chemetics CIRAMET® and CIRAMET PLUS™ materials are tested to ASTM G48-C, which is an acidified ferric chloride accelerated corrosion test for chloride pitting attack, with CIRAMET PLUS™ testing to significantly higher temperatures without pitting. CIRAMET® and CIRAMET PLUS™ both demonstrate no hydrogen embrittlement susceptibility which can occur with other commonly applied materials to this serNominal Composition

CIRAMET PLUS™

Element

Chemetics acid cooler fabricated with CIRAMET PLUS™ alloy for seawater acid coolers.

CIRAMET®

Weight %

Chromium

21 – 28

Nickel

26 – 32

18 – 25

Molybdenum

6–8

4–6

Iron & other alloying elements

Balance

vice in the industry such as Superferritic and Duplex stainless steels. The most critical component of a seawater acid cooler is the tubing which is required to operate at elevated metal temperatures. For this severe service, Chemetics has developed proprietary tubing specifications which far exceed those of regular commercially produced alloy tubing. CIRAMET PLUS™ tubing is manufactured on a state-of-the-art automatic production line where frequent stringent quality control checks and regular production sampling are performed at every stage of the process to ensure a finished product of the highest possible quality with a superior/smooth bore finish. The combination of Chemetics exacting specifications, advanced acid cooler thermal and mechanical design standards, specially developed fabrication procedures, and intensive quality control procedures result in a high-quality acid cooler capable of withstanding the severe service of cooling hot acid with seawater. In the most severe seawater cooling applications CIRAMET PLUS™ has been shown to significantly extend the service life of acid coolers in comparison to other commonly applied materials in this service across the industry. Chemetics continues to lead by prioritizing technology development that will benefit sulfuric acid plants and the individuals who operate and maintain them. Chemetics also provides spare parts and site technical services globally to support acid cooler inspections, maintenance, and troubleshooting. Details matter. Please contact Chemetics at chemetics.equipment@worley.com to discuss your sulfuric acid cooling needs. q

Ramco provides simple, consistent safety solutions Ramco® Manufacturing located in Houston, specializes in products to prevent, detect, and protect from hazardous pipe connection leaks. Ramco recently celebrated their 80th year in business. Opened in 1942, the company originally manufactured dog tags for the United States military during WWII. In 1961, in conjunction with the U.S. Navy, they developed the first commercially available safety shield after a fire on the USS Constellation. In the 1970’s Ramco patented the 1st fabric safety shield

for DuPont chemical. Since that time, Ramco has been introducing products for the chemical industry to protect both people and the environment. Ramco’s products are an important part of the chemical industry safety culture. In addition to improving safety, they help to reduce costs by: —Preventing leaks with Flange Isolation Gasket Kits which help reduce downtime. —Detecting leaks early before they become a bigger problem using OnGuard™

Acid Detecting Paint and Safety Shields. —Protecting employees and equipment from harm by controlling leaks and avoiding spray outs. Ramco has also developed a field service program to assist plants with their safety shield needs. In today’s environment, many facilities do not have the time or manpower to properly identify and install safety shields where they are needed. Ramco’s highly-trained specialists can do this quickly and easily.

How it works: —Ramco sends certified personnel to the job site to identify and measure the pipe connections requiring flange shields. —Connections are marked/ tagged for easy identification during installation. —Ramco returns once the order is complete to install shields. —A maintenance program is also available, with inspections performed at scheduled intervals. For more information, please email info@ramco-safetyshields.com or visit www.ramco-safetyshields.com. q

“ For the past 80 years Ramco has provided products to protect both people and the environment.

”

Sulfuric Acid Today • Fall/Winter 2023

Based in Houston, Ramco recently celebrated its 80th year in business.

Ramco provides a wide range of safety shields, to fit any pipe connection need. PAGE 35

Feature

In certain conditions, significant biological growth can occur between planned acid cooler cleaning during plant shutdowns. For plants operating with tropical/warm seawater, high biological activity, and/or high fouling tendency, Chemetics’ new CIRAMET PLUS™ has been successfully deployed to the industry with fantastic early results. Developed based on extensive operating experience gained from Chemetics’ seawater acid coolers in service since 1977 plus exhaustive in-house lab testing and pilot plant projects, the specifications for CIRAMET PLUS™ alloy has produced a material custom designed for the most critical seawater cooling applications. Manufactured by the latest steel making processes, the chemistry and production routing of the alloy has been tailored to Chemetics’ exacting specifications to optimize pitting and crevice corrosion performance characteristics required for this most severe service, while retaining the

Feature

Plant shutdown: sulfur burner backflow By: Bruno Ferraro, Breno Avancini, Eduardo Almeida, Victor Machida, Vitor Sturm, and Nelson Clark

Furnace gas backflow with sulfur

A common problem of many sulfurburning sulfuric acid plants is post combusted sulfur-rich hot gas backflow during shut down, which can damage equipment upstream from the furnace, such as the drying tower and its internals. Some instances of this phenomenon may result in solidification of carried sulfur vapors on the transport ducts, drying tower mist eliminators, and even on tower packing and acid distributors. These events require emergency replacement or maintenance to avoid tower performance compromise or production reduction to increased pressure drop on the system. The phenomenon occurs when two factors combine: return of hot gas during shutdowns and presence of sulfur vapors in the furnace. Each of these are briefly presented to clarify the potential causes for the problem and possible solutions to minimize the phenomena.

Sulfur burning

Sulfur is burned to form sulfur dioxide, which is further catalytically converted to sulfur trioxide in manufacturing sulfuric acid. The combustion of sulfur mechanism can be divided into two stages: the liquid molten sulfur is first vaporized, and then combined with oxygen to form sulfur dioxide. The generic sulfur oxidation equation (S+O2↔SO2) shows that the theoretical amount of oxygen for burning is equimolar. In practice, the air providing oxygen for combustion in sulfuric acid plants is supplied in excess to avoid problems that may result from unburnt sulfur condensation and solidification in the coldest stream surfaces of the plant. Excess air also keeps the combustor gas outlet temperatures and the temperature rise in the catalytic converter, particularly on the first pass, at acceptable levels. Therefore, the upper limit of practicable concentrations of SO2 after burner is less than equimolar concentration. While it

Fig. 1: Pure elemental sulfur viscosity.

Fig. 2: Gas-phase sulfur allotropes. PAGE 36

is theoretically possible to reach concentrations of SO2 around 20 vol%, usually the gases from sulfur combustion furnaces associated with sulfuric acid plants contain 10-12 vol% of SO2, corresponding to an O2/ SO2 ratio close to 1:1, as usually applied in double absorption processes. The remaining oxygen in the gas stream is key for SO2 to SO3 conversion. Most liquid sulfur is mechanically sprayed between 140 and 150° C, where its viscosity is low enough to allow it to be atomized into fine droplets by single or dual fluid spray nozzles. As a result of atomization, finer droplets increase overall surface area, which offers extended surface area to help sulfur vaporize more rapidly. Sulfur burners should provide intimate and turbulent mixing of air and sulfur to accelerate the oxidation process. Sulfur chemistry is unusual due to its tendency to catenation, which is the bonding of atoms of the same element in a chain in series. Sulfur forms a range of open and closed Sn species in the gas phase of which S2 and S8 are dominant. According to Ullmann’s Encyclopedia of Industrial Chemistry on sulfur dioxide, molecules of S2 in the vapor phase are the main oxidized species. Liquid sulfur evaporates primarily as S8 molecules, which begin to decompose into S2 at 600°C and above. In practice, a portion of the oxidized sulfur is the heat source required to vaporize it. This initial phase is required for maximum mass transfer rates. Intimate mixing of air and sulfur, good atomization, and proper temperatures are key to preventing sublimated sulfur carryover. Good atomization also allows droplets to be easily evaporated, avoiding accumulation of sulfur pools at furnace bottom. Sulfur inject nozzles should be monitored for nominal plant capacity. Atomization at turndown conditions may be unsatisfactory, by either low nozzle pressure differential or risk of plugging at lower rates—so when significantly changing capacity, nozzles are typically required to change.

Backflow in shutdowns

Gas backflow during plant shutdowns, particularly in unexpected shutdown situations, is a familiar and well perceived phenomenon. At times, hot fumes can be seen when opening drying tower upper manholes shortly after plant shutdowns. When associated with the presence of unburnt sulfur vapors, furnace gas backflow leads to the appearance of sulfur inside the drying tower, which may require intervention or maintenance on the internals. Unburnt sulfur in the combustor caused by inadequate process conditions, poor air mixing turbulence and/or inadequate nozzle atomization may cause formation of liquid sulfur pools in the furnace’s bottom. During shutdowns, delays in interruption of furnace sulfur injection or inlet sulfur leakage may form or increase these

liquid sulfur pools. While there is O2 in the furnace, it is consumed by the sublimating sulfur pools due to the residual heat hot furnace environment. Once O2 is rarified by the absence of added oxygen, the residual subliming sulfur mixes with remainder hot gases which can be dragged upstream depending on flow resistance. This hot gas spreads over the plant; its temperature and occasional sulfur vapor may damage Fig. 5: Simplified plant model diagram. equipment such as blowers We investigated gas dynamics for a and drying tower mist eliminators in the steady-state operation case in which the case of backflow and plug catalyst or canblower ceases to operate at time 0 under dles in the event of forward flow. an emergency condition, imposing a linear Figures 3 and 4 show damage caused discharge pressure decrease to the system by backflow with sulfur vapors. in a 5 second interval. Once the blower is Hot gas backflow is a complex phestopped, the pressure in the plant is rapidly nomenon, and it can introduce problems to lowered, allowing the depressurizing gas to flow through the plant outlets with less resistance. In this simulated case, it is possible to verify that for approximately 7 seconds (hatched area of Fig. 6) the gases from the plant equipment return to the drying tower as the mass flow inside the ducting between the drying tower and furnace becomes negative. The dynamical response of pressures within the plant during depressurization and its duration, are governed by the resistances imposed on the outlet gas flow. To verify the plant pressure response, Fig. 3: Gas duct in drying tower outlet after Fig. 7 registers the blower pressure behavior condensation of sulfur vapors (courtesy in the furnace and drying tower. In this simClark Solutions). ulation, it is possible to see that 3 seconds after the blower is turned off, the pressure gradient inside the equipment is inverted, which generates backwards flow. The system depressurization time is a decisive factor in the intensity of the reverse side gas flow. Higher gradients of depressurization increase the duration of reverse flow. Due to the plant gas volume inertia, steep drops in the system pressure contribute to the occurrence of the reverse flow. Real plant data collected indicate that drying tower differFig. 4: Drying tower mist eliminator after ential pressure manometers had registered condensation of sulfur vapors (courtesy up to 30 seconds of negative values during Clark Solutions). failure shutdowns, indicating intense prolonged backflow. plant equipment, even without the presence of sulfur vapors, since temperatures in the order of 400 to 600°C are possible in the flowing gas, damaging instrumentation, valves, ducts, mist eliminators, and more. Fig. 5 shows a simulated mathematical model that can be used to predict the transient gas flow during shutdowns. The model allows dynamic simulation of the gases in the plant, as well as the analysis of gas flow in the ducting between the drying tower and the blower. The simulation shows the behavior of a double-absorption sulfuric acid plant with approximately 1,000 tpd capacity.

Possible solutions

A common solution to the issue of hot gas backup involves the utilization of automated Class 5 gas dampers that swiftly close following a power outage or shutdown alarm. However, this approach has its drawbacks. Over time, corrosion products or solidified sulfur can accumulate in the valves and downstream ducts, impairing their functionality and compromising the tightness of valve closure. An alternative method employs a lowerClass damper in conjunction with Clark Solutions’ mechanical gas “diode,” the “T-Valve.” Sulfuric Acid Today • Fall/Winter 2023

Functioning as a diode, the T-Valve ensures minimal pressure drop during forward gas flow and a significant pressure drop in the event of backward flow. This equipment diminishes backward flow by a factor of 10 or more, thereby reducing the volume of gas reaching the automated damper. The T-Valve is a passive device equipped with no moving parts, that exhibits distinct behavior in flow when its direction is reversed. In the favorable flow direction, the pressure drop across the valve is similar to that of a conventional gas ducting. However, in the unfavorable direction, a portion of the flow is disturbed, leading to a significant recirculation zone responsible for a high pressure drop in the reverse direction.

Fig. 7: Pressure dynamics on simulated blower shutdown

This phenomenon happens because the T-Valve induces significant energy dissipation when there is a reverse flow. In this scenario, the resulting flow streamlines exhibit velocities in opposite directions, leading to the formation of intense turbulence. Furthermore, the T-Valve is designed for effortless cleaning. Most sulfur vapors condense on its internal surface, allowing for swift cleaning procedures. This not only safeguards the damper but also protects downstream equipment from reverse-flowing gas.

Conclusion

With the results obtained through the plant model simulation, it is possible to

verify the existence of a backwards flow of the plant gas volume to the drying tower during plant shutdown, which is intensified by the depressurization ramp of the blower. This provides us with quantitative data to develop procedures to attenuate gas return and its potential damages. Furthermore, even though the model does not capture all the plant physics, such as heat transfer phenomena, it is possible to verify the presence of reverse gas flow. It is well known that when the reverse flow contains condensing sulfur vapors, its damage potential is intensified. Thus, complete burning and proper atomization of sulfur during operation is essential for extending the life of plant equipment, avoid-

References: -MÜLLER, Hermann. Sulfur dioxide. Ullmann’s Encyclopedia of Industrial Chemistry, 2000. -Freeport Sulfur Co., Freeport Sulfur Handbook ,1958

CONFERENCE REVIEW

46th Annual AIChE Clearwater Conference gathers in Florida Industry insiders and their families gathered at the beautiful Sand Key Resort in Clearwater, Florida in June for the AIChE Central Florida’s 46th Annual International Phosphate Fertilizer & Sulfuric Acid Technology Conference. Known to attendees as simply the Clearwater Convention, colleagues from around the globe gather each year to share their ideas concerning chemical process technology, specifically the production of phosphoric acid, phosphate fertilizers and sulfuric acid. One of the highlights of this year’s event was the 24th annual Sulfuric Acid Workshop, moderated by Rick Davis of Davis & Consulting Inc. The weekend also provides ample time for networking and hospitality events for both attendees and their families, a highlight of the convention. Friday, June 9, kicked off with an overview of this year’s overarching topic: “Upgrade/Update vs. Replacement In-Kind.” Presenters focused on how a company develops a valid case for the justification of building a new plant vs upgrading an existing facility. Presentations included: —”Factors Affecting the Decision to Revamp a Plant or Build a New Plant,” by Chris Brown, Elessent MECS® Technologies. —“Revamping and Old Plant or Build a New Plant,” by Sulfuric Acid Today • Fall/Winter 2023

Vulcan Mutler, EXP. —“Why Build a New Acid Plant? It’s Time for Something New!” by Collin Bartlett of Metso-Outotec. —“How to Improve Performance When Replacing Equipment,” by Rob Maciel, Chemetics. On Saturday, attendees could attend one of two concurrent Jim Ellis of GORE-TEX sessions: Phosphate Tech- Professional, right, shows nology and Sulfuric Acid examples of their protective Technology. Presentations clothing to participants of for the sulfuric acid session the 2023 AIChE Clearwater Convention. included: —“Towards a New Level in Performance with Selection of Catalyst Geometric Shape,” by Allison Belgard, BASF Corporation. —“Use of Computational Fluid Dynamics to Improve Sulfur Atomization and Combustion,” by Neal Londry, NORAM. —“How to Avoid Living With an ‘Ex-con’ – Making Smart Converter Selection Choices,” by Steve Puricelli, EXP SME.

Presenters for this year’s sulfuric acid workshop included, from left, Chris Brown of Elessent MECS, Rob Maciel of Chemetics, Vulcan Mutler of EXP, Steve Puricelli of EXP, Collin Bartlett of Metso Outotec, and Rick Davis of Davis & Associates Consulting.

—“Hydrogen Safety: Does your plant have a plan for a weak acid incident?” by Rick Davis, Davis & Associates Consulting. —“Carbon-Free Electricity Generation,” by Colin Shore, Elessent MECS Technologies. —“FEM Aided Engineering: case studies in the sulfuric acid industry,” by Nelson Clark, Clark Solutions . In addition to the technical sessions, a highlight of the AIChE Clearwater conference is always the opportunities for informal networking and fellowship. In addition to family-friendly hospitality suites and dinners with friends old and new, attendees and their families got to enjoy musicians, magic, face painting and karaoke. For more information regarding the 2024 AIChE Central Florida Section Conference, please visit the event’s website: www. aiche-cf.org. q PAGE 37

Feature

Fig. 6: Gas dynamics simulation result for blower shutdown.

ing formation of sulfur pools inside the furnace and its spread as vapor to other sensitive equipment. In scheduled shutdowns after sulfur inlet interruption, it is desirable to maintain air flow up until there is no unburnt sulfur in the system. One possible solution to the gas backflow itself presented is the Clark Solutions T-Valve, which offers with its diode-like functionality an effective means to minimize the risk of damage to automated dampers often used to contain the gas. The T-Valve stands out as a reliable and practical choice for enhancing the durability and efficiency of gas control systems in diverse industrial settings. For 30 years, Clark Solutions has been working in sulfuric acid plants in South America and other regions, sharing vast experience in troubleshooting of processes and equipment. Thanks to this vast experience, R&D resources, and a technical staff fully dedicated to thermal and mechanical separation technologies, many plants and plant equipment were studied, designed, and manufactured—including a large number of key plant equipment such as dozens of absorption and drying towers and thousands of tower internals. q

Department

CONFERENCE REVIEW

2023 Australasia Sulfuric Acid Workshop brings together industry insiders Industry leaders gathered in Brisbane, Queensland, Australia in April for Sulfuric Acid Today’s 2023 Australasia Sulfuric Acid Workshop. Some 85 attendees from around the globe enjoyed getting together to discuss changes in the industry since the last workshop, in 2016. “We were sorry to have to cancel our 2020 workshop due to the Covid-19 pandemic,” said Sulfuric Acid Today publisher Kathy Hayward. “It was wonderful getting everyone together again to exchange ideas and best practices, as well as have some fun in this beautiful location.” Co-Sponsors of the workshop included Acid Piping Technology, APMS, BASF Corp., Begg Cousland Envirotec Ltd., Central Maintenance & Welding, Chemetics, Elessent MECS Technologies Howden, Knight Material Technologies, Metso Outotec, Metz Specialty Materials, NORAM Engineering & Constructors, SensoTech Inc., SmartScope, Specialized Engineering Services, Sulphurnet, Topsoe, VIP International, and Weir Minerals Lewis Pumps. Plant attendees from around the globe included employees of Ballance AgriNutrients, BHP Nickel West, BHP Olympic Dam, FQM Australia Nickel, Incitec Pivot Ltd., Kamoto Copper Company S.A., Minara, Nyrstar Hobart, Nyrstar Port Pirie, Prony Resources, Ravensdown Fertiliser, Rio Tinto, and Sun Metals. The much-anticipated event kicked off on Sunday, April 2 with a Golf Tournament at the St. Lucia’s Links Golf Course, just outside of Brisbane. The tournament was sponsored by Knight Material Technologies. It was a beautiful day on a great course, and fun was had by all. From there, the conference moved into technical presentations from CoSponsors and Producers. The keynote address, “Sulfuric Acid Outlook: 2023 and Beyond,” was presented by Fiona Boyd, Acuity Commodities Other presentations included: —“Do it once and do it right - Acid plant reliability issues and their cost,” presented

Fiona Boyd of Acuity Commodities presented the keynote address, which included a sulfuric acid outlook for 2023. PAGE 38

Some 85 participants from around the globe gathered in Brisbane for the 2023 Australasia Sulfuric Acid Workshop.

Scott Bennett and Braydon West of Minara co-presented on the topic of sulfur contamination of the 3.5 bar steam system at their facility in Western Australia.

by Herbert Lee, Chemetics. —“Efficiency and availability improvements in sulfuric acid plants,” presented by Stefan Bräuner, Metso-Outotec. —“Sulfuric Acid Operations Troubleshooting Clinic,” presented by Darren Bridges, SES. —“Mist Elimination Troubleshooting Records,” presented by Graeme Cousland, Begg Cousland Envirotec. —“Knight Material Technologies – Acid Technology Advancements” presented by Gregory Mann, Knight Material Technologies. —“The protection of Concrete and Steel – Combatting the effects of Sulfur and Sulfuric,” presented by Stuart Ellis and Mercy Baniasad, Metz Specialty Materials. —“Maintenance & Troubleshooting of Vertical Acid/Sulfur Pumps,” presented by Ricky Jaswal, Weir Minerals Lewis Pumps. —“One size doesn’t fit all for acid piping,” presented by Alex Knoll, Acid Piping Technology. —“Sulfur combustion and sulfur combustion design,” presented by Randal Sarrazin, NORAM Engineering & Constructors. —“Make the most out of the metal booming using optimal catalyst solutions,” presented by Martin Alvarez, Topsoe. —“Towards a New Level in Performance

Martin Alvarez of Topsoe explained how to make the most out of the metal booming using optimal catalyst solutions.

Darren Bridges of Specialized Engineering Services shares his experience with economizer issues with the participants.

with Selection of Catalyst Geometric Shape,” presented by Jochen Willersinn, BASF. —“Challenges in Sulphur Melting & Purification process for the Sulfuric Acid Industry,” presented by Mathijs Sijpkes, Sulphurnet. —“Considerations in procurement of fabrication,” presented by Brad Varnum, Central Maintenance & Welding. —“Inline and lab digital measurement solutions towards process excellence,” presented by Shamsul Khan, SensoTech GmbH. —“Digitalization trends for improved compressor operations in sulfuric acid plants,” presented by Wolfhard Kiefer, Howden Turbo GmbH. —“Plant Revamping – How to identify your bottlenecks” presented by Torsten Weber, SmartScope. In addition to the presentations, attendees were able to peruse display booths and learn about the latest technology in the industry. There were also a variety of panel discussions to choose from. These discussions helped facilitate the sharing of information, best practices, and lessons learned. Panel discussion topics included: acid towers, converters, process gas monitoring/ analyzers, steam systems, sulfur, hydrogen safety, heat exchangers, and gas cleaning.

Another highlight of the Australasia Workshop is the informal networking and hospitality events. Group dinners each night gave everyone a chance to catch up while eating everything from fresh local seafood to delicious BBQ. Attendees also got to try their hand at casino games, playing for some great prizes provided by the co-sponsors of the event.

Participants in the sulfuric acid workshop were able to try their hand at casino games to win door prizes donated by the event’s co-sponsors.

Our next conference, the 2024 Sulfuric Acid Roundtable, will be held April 22-25 at Omni Resort in ChampionsGate near Orlando, Florida. For more information, please email Kathy Hayward at kathy@ h2so4today. com, or visit the event’s website: www.acidroundtable.com q Sulfuric Acid Today • Fall/Winter 2023

WorldClass Engineering and Design for Sulfuric Acid Plants

Modern Technology and Equipment Design +1.604.681.2030 | sulfuric@noram-eng.com | noram-eng.com

Faces & Places

From left, Yohan Amatjalal of Prony Resources, Samuel Bianchi of Prony Resources, William Sydes of Nyrstar, and Marnus Dannhauser of Nyrstar network during the welcome reception of the 2023 Australasia Sulfuric Acid Workshop in Brisbane, Queensland.

Jan Haesner of BASF, left, and Stefan Bräuner of Metso Outotec catch up during the workshop.

Attending the Weir Minerals Lewis Pumps customer appreciation dinner, held in conjunction with the AIChE Clearwater Conference, are from left, John Horne of Elessent MECS Technologies, Vulcan Mutler of EXP, and Anne and Chris Brown of Elessent MECS Technologies.

Manning their booth at the AIChE Clearwater Conference are, from left, Bill Goodell, Patrick Polk, and Mike Kuhlmeier of Topsoe.

Catching up at the 2023 Australasia Sulfuric Acid Workshop in Brisbane, Queensland are, from left, Brad Varnum of CMW, Darren Bridges of Specialized Engineering Services, Stan Miller of VIP International, Alex Knoll of Acid Piping Technology, and Ricky Jaswal of Weir Minerals Lewis Pumps.

Aaron Parry of BHP Olympic Dam, left, visits with Todd Hancock of Nyrstar Port Pirie, Damon Ganley of Nyrstar Port Pirie, and Lance Winders of BHP Olympic Dam during a break in the Sulfuric Acid Workshop.

The Sulfuric Acid Workshop in Brisbane, Queensland provided plenty of time for networking. From left are Mathijs Sijpkes of Sulphurnet, Werner Vorster of NORAM Engineering & Constructors and Jan Hermans of Sulphurnet.

Kurt Olandt of Weir Mineral Lewis Pumps welcomes the guests to their customer appreciation dinner held at Crabby Bill’s in conjunction with the AIChE Clearwater Conference.

Attending an AIChE Clearwater Conference hospitality function are, from left, CJ Horeky of INTEREP, Hoss Maddry of VIP International, Darwin Passman of VIP International, and Kevin Bryan of Lithium Americas.

Catching up at the AIChE Clearwater Conference are, from left, Rick and Charlotte Davis of Davis & Associates Consulting, Guy Cooper of C. Guy Cooper Projects, and George Wang of GWang Consulting.

Kimre, a global leader in clear air technology, celebrated their 50th anniversary at the AIChE Clearwater Conference.

Visiting the Chemetics hospitality function during the AIChE Clearwater Conference are, from left, Rob Maciel of Chemetics, Reed Bond of JR Simplot, Stuart Hinze of JR Simplot, Bob Whitters of Chemetics, Sergiy Moklyak of Chemetics, Terry McCormick of JR Simplot, Jhonny Vasquez of JR Simplot, and Theo Warner of JR Simplot.

Enjoying some downtime during the Sulfuric Acid Workshop in Brisbane, Queensland are, from left, Jason Harris of BHP Nickel West, Elise Hooper of BHP Nickel West, and Gary Nicholls of BHP Nickel West.

Becky and Jack Harris of VIP International enjoyed dining at Crabby Bill’s during the Weir Lewis Pumps customer appreciation dinner held in conjunction with the AIChE Clearwater Conference.

Networking at the AIChE Clearwater Conference are, from left, Graeme Cousland of Begg Cousland Envirotec, Alex Knoll of Acid Piping Technology, and Ed Knoll of Acid Piping Technology.

Jeremy Schneider of Elessent MECS Technologies and Steve Williams of Elessent MECS Technologies man their booth during the AIChE Clearwater Conference.

Solutions

Sealing is maintained due to DrySeal Static Pressure, avoiding seal break and gas by-pass

Sealing Device Candle filter mist eliminators often come paired with sealing cups containing process liquid. Some disadvantages of the cup design are frequent and burdensome refills plus vulnerability to plugging and leaking due to corrosion. To avoid these issues, Clark Solutions developed a self-draining and auto-sealing alternative, the safer DrySeal™. The device is also easy to clean and install, not requiring additional set-up steps such as refilling.

www.clarksolutions.com

Auto Sealing

Self Draining

2024

Sulfuric Acid

R O U N D T A B L E

2024 Sulfuric Acid Roundtable April 22-25, 2024

Omni ChampionsGate • Orlando, Florida

The 20 Acid R24 Sulfuric oundta ble will of fer :

— Keyno te Ad Global S dress on the ulfuric A c — Produ cing Plan id Market t Panel Discussio ns & Pr — New T echnolog esentations yD — Safety Issues & evelopments Incident Reviews