Chemical processing march 2014 by harvad web

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CONTENTS MARCH 2014 | VOLUME 76, ISSUE 3

COVER STORY

COLUMNS

18 Get to the Root of Accidents Accident investigations usually focus on operator error or technical failures. However, applying systems thinking may provide greater insights on underlying causes and, in the long run, prevent more incidents.

From the Editor: How Do You Deal with the Four Ds?

Field Notes: Rest Easy With a Good BEDD

FEATURES

15 Energy Saver: Break Energy Audits into Phases, Part II

DESIGN AND OPTIMIZATION

29 Optimize Water Cleanup with Activated Carbon More plants are now placing greater emphasis on treating and reusing process water. Carbon adsorpton often plays a key role. A few pointers can help you make the most of such systems.

17 Compliance Advisor: EPA Targets DecaBDE and BPA 53 Plant InSites: Do Your Homework

MAINTENANCE AND OPERATIONS

35 Carefully Consider Nozzle Loads Choices can impact piping design as well as equipment reliability. Inappropriate nozzle loads can cause distortion of the machinery casing and internals, and shaft misalignment. INSTRUMENTATION AND CONTROL

39 Widespread Wireless Beckons The increasing availability of low-cost wireless sensors promises unprecedented amounts of data and, with it, improved process control. However, security remains a concern.

58 End Point: CSB Urges Tougher Safety Regulations

DEPARTMENTS 11 In Process: Dual Catalysts Boast Unprecedented Reactivity | Photoreaction Provides High Enantioselectivity 49 Process Puzzler: Vanquish Vacuum Distillation Difficulties 54 Equipment & Services

MAKING IT WORK

45 Plant Assesses Alarm Displays A South African plant tested alternative approaches for alarm summary displays, identifying potential changes that help operators react properly to abnormal situations.

55 Product Spotlight/Classifieds 57 Ad Index

Chemical Processing (ISSN 0009-2630) is published monthly by Putman Media Inc.,1501 E. Woodfield Road, Suite 400N, Schaumburg, IL 60173. Phone (630) 467-1300. Fax (630) 467-1109. Periodicals postage paid at Schaumburg, IL, and additional mailing offices. POSTMASTER: Send address changes to Chemical Processing, P.O. Box 3434, Northbrook, IL 60065-3434. SUBSCRIPTIONS: Qualified reader subscriptions are accepted from operating management in the chemical processing industries at no charge. To apply for a qualified subscription, fill in the subscription card. To nonqualified subscribers in the United States, subscriptions are $68 per year. Single copies are $15. Canadian and other international annual subscriptions are accepted at $200 Airmail. Single copies are $16. Canada Post International Publications Mail Product Sales Agreement No. 40028661. Canadian Mail Distributor information: Frontier/BWI, PO Box 1051, Fort Erie, Ontario, Canada, L2A 5N8. Copyright 2014 Putman Media Inc. All rights reserved. The contents of this publication may not be reproduced in whole or in part without the consent of the copyright owner. REPRINTS: Reprints are available on a custom basis. For price quotation, contact Foster Reprints, (866) 879-9144, www.fostereprints.com also publishes Control, Control Design, Food Processing, Pharmaceutical Manufacturing and Plant Services. Chemical Processing assumes no responsibility for validity of claims in items reported.

CHEMICALPROCESSING.COM

MARCH 2014

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FROM THE EDITOR In Memory of Julie Cappelletti-Lange, Vice President 1984-2012 1501 E. Woodfield Road, Suite 400N Woodfield, IL 60173 Phone: (630) 467-1300 Fax: (630) 467-1109 www.chemicalprocessing.com E-mail: chemicalprocessing@putman.net Subscriptions/Customer Service: (888) 644-1803 or (847) 559-7360 Editorial Staff Mark Rosenzweig, Editor in Chief, x478 mrosenzweig@putman.net Amanda Joshi, Managing Editor, x442 ajoshi@putman.net Traci Purdum, Senior Digital Editor, x428 tpurdum@putman.net Seán Ottewell, Editor at Large Ireland sottewell@putman.net Contributing Editors Andrew Sloley, Troubleshooting Columnist Lynn L. Bergeson, Regulatory Columnist Ven Venkatesan, Energy Columnist Dirk Willard, Columnist Design & Production Stephen C. Herner, Vice President of Creative Services, x312 sherner@putman.net Angela Labate, Associate Art Director, x461 alabate@putman.net Rita Fitzgerald, Production Manager, x468 rfitzgerald@putman.net Editorial Board Vic Edwards, Consultant Tim Frank, Dow Chemical Ben Paterson, Eli Lilly Roy Sanders, Consultant Ellen Turner, Eastman Chemical Ben Weinstein, Procter & Gamble Jon Worstell, Consultant Sheila Yang, Genentech Publisher Brian Marz, Publisher, x411 bmarz@putman.net Executive Staff John M. Cappelletti, President/CEO Rick Kasper, CFO Jerry Clark, Vice President of Circulation Jack Jones, Circulation Director Reprints Rhonda Brown, Reprint Marketing Manager rhondab@fosterprinting.com 866-879-9144 x 194 • Fax 219-561-2019 4295 S. Ohio Street, Michigan City, IN 46360

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How Do You Deal with the Four Ds? Dull, dirty, dangerous and distant operations pose complex challenges “The Four Ds” got attention at the formal opening in late January of the Emerson Innovation Center — Process Systems and Solutions in Round Rock, Texas. That’s because a key part of the facility is an “Integrated Operations Center” where customers can explore new ways to manage remote operations and enhance collaboration internally and with outside experts. Right now, manufacturers face myriad difficulties in tackling the challenges posed by the Four Ds, notes Peter Zornio, chief strategic officer of Emerson Process Management. They must contend with worker shortages and loss of experienced personnel in general — but finding suitable people willing to go to remote, inhospitable locations is an even tougher task. In addition, the companies suffer from disconnections among job functions and disjointed communication and decision-making. So, firms are turning to a new organizational model called integrated operations to confront the challenges, he explains. This usually involves putting people from key functional groups such as operations, maintenance and business planning at a single hospitable location, and creating an environment with specialized applications and teleconferencing to enhance access to field staff as well as to internal and outside experts. Another must is providing actionable real-time data. The aim is to streamline decision-making and align organizational priorities and metrics. The building blocks for integrated operations include reliable, secure, highbandwidth connections, wireless sensors and mobile worker infrastructure, and collaboration tools, Zornio stresses. Highly flexible, scalable automation and safety systems, and coordinatied local and remote control also are essential. So, too, is full integration of systems from enterprise resource planning on down, and the availability of accurate, real-time production, equipment-health, environmental, logistics, business and other data, he adds. To help its customers succeed with 7

integrated operations, the facility includes a 14,000-ft2 “iOps” Center. “We worked for nearly two years on the vision and execution of the iOps Center,” says Jim Nyquist, president of Process Systems and Solutions for Emerson Process Management. “Customers gain a clear vision of what’s possible through an experience they can’t get anywhere else in the world.” Its centerpiece is the iOps Command Center. In this state-of-the-art room, personnel can monitor remote operations (as well as an on-site skid with mixing and separation units), check the performance and health of assets worldwide, conduct videoconferences with field staff and specialists, and make decisions to optimize process and business results. The Command Center features a 30-ft × 6-ft. video wall that shows operators’ level 1 overview displays, closed-circuit video feeds, dashboards of key performance indicators, and other visuals. The idea is to give customers a realistic look at technologies and work processes they might consider. Besides the iOps Center, the new 282,000-ft2 facility houses Emerson’s Human Centered Design Institute, which focuses on making products easier to use, an interoperability and testing lab, a training facility for customers, as well as other operations. It also serves as global headquarters for Emerson’s automation systems and project services businesses. The innovation center joins Emerson’s existing ones on flow control applications and technologies at Marshalltown, Iowa (see: “Marshalltown Really Builds Upon a Legacy,” www.ChemicalProcessing.com/ articles/2010/110/) and software application development at Pune, India.

The iOps Command Center gives customers a realistic look at technologies and work processes they might consider.

Mark Rosenzweig, Editor in Chief mrosenzweig@putman.net

chemicalprocessing.com

March 2014

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field notes

Rest Easy With a Good BEDD If you don’t know what one is you should “What’s the temperature range on your cooling water?” I asked. A shrug was his reply. “What’s the water quality for your boilers?” was my second question. This prompted another shrug. I got the answers I needed from his vendors but was embarrassed for him, even if he wasn’t. My young client needed a basic engineering data document (BEDD). It should have been in the first document he handed me. A BEDD should be developed during the initial design of a plant and updated periodically during commissioning, construction and operation of the plant. In short, a BEDD establishes the ground rules. Don’t confuse a BEDD with basic engineering data (BED), which is specific to a particular project, although it should excerpt parts of the BEDD. As a minimum, a BEDD should include the following: 1) a site map; 2) an electrical area classification map of the facility; 3) utilities condition — e.g., temperature, pressure and composition, if applicable, of nitrogen, oxygen, air, instrument air, breathing air, process water, potable water, steam, condensate, eyewash water, fuel gases, etc.; 4) ambient conditions — e.g., maximum and minimum temperature, design conditions, including the effects of solar heating; 5) base elevation above sea level and barometric pressure; 6) pipe standards — e.g., ANSI ratings, surface finishes, corrosion classifications, paint guidelines as well as construction, testing and inspection requirements; 7) line list standards — e.g., how operating and design pressure is to be established; 8) grounding requirements for equipment and instruments; 9) drawing templates — e.g., process and instrumentation drawings (P&IDs), plans, elevations, electrical and civil diagrams; 10) basic vendor package form requirements — e.g., cover letter, design basis, data sheet and summary drawing; 11) product quality control criteria — e.g., parts per million (it’s generally better to express ppm in terms of mass not volume); 12) programming standards — e.g., faceplate ones for a pump operation; 13) design conditions for sewer, flares and stacks; 14) management of change procedures and applicability — use flow diagrams; 15) ground excavation standards — e.g., depth required for trenches where trucks will pass and footing specifications; 16) the frost line, or freezing depth, and acceptable means of counteracting freezing; and 17) contacts for permits, inside the company, and in government bodies — e.g., in municipal and state environmental and safety agencies as well as federal ones.

This may seem like a lot — it is. The best way to simplify developing a BEDD is to use a checklist provided by a general contractor. For example, consider 25-psig steam produced by a 400-psig boiler. The first box would list the saturation pressure: 25 psig. The second box would detail the assumed nominal (design) temperature, which usually is the saturation temperature, in this case, 267°F. The maximum temperature assumes the steam is reduced from the boiler pressure and operated at the site high pressure — use the saturation temperature of 400-psig saturated steam as the maximum temperature, i.e., 448°F. The minimum temperature would be the condensate tank temperature, which should be part of the BEDD. Suppose we choose 40 psig as the pressure, then the minimum temperature would be 267°F for the collected steam. If the 25-psig steam isn’t collected, then the minimum temperature would be the freezing point of water, 32°F. Once the BEDD checklist is prepared, it must be updated as necessary. As with all important documents, explain amendments and ensure the general contractor and the company that will live with the BEDD long after the contractor has left both agree on them. A chronological history memo should document all significant changes. In contrast, a BED is specific to a particular project and is less extensive. A typical BED should contain: 1) the process flow diagram; 2) a P&ID; 3) a preliminary line list; 4) an equipment list; 5) design procedures — e.g., software accepted for design; 6) purchasing, shipping, commissioning and turnover standards — e.g., types of flow measurements that are acceptable, equipment quality assurance, process loop checks, etc.; 7) reference to excerpts of the BEDD, such as barometric pressure; 8) citations to documentation procedures — e.g., drawing standards, instrument and equipment data sheets, documentation security requirements and approval procedures, etc. Some people contend a BED also should contain the design basis and other project details but I don’t agree. Don’t consider the BEDD and BEDs as fixed documents. However, to avoid confusion, freeze them at times. Over the life of a facility, they are truly living things that require frequent re-assessment; change files and exception files must be maintained if they are to be useful.

The company will live with the BEDD long after the contractor has left.

dirk willard, Contributing Editor dwillard@putman.net

chemicalprocessing.com

March 2014

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in process

Dual Catalysts Boast Unprecedented Reactivity Sequential reactions promise more-efficient conversion of alpha-olefins to chiral compounds Economic Snapshot 66,000 $ Million

65,000 64,000 63,000 62,000 77.0

75.0

76.0

74.0 73.0 72.0 95.0 94.0 2007 = 100

By combining a pair of catalytic reactions in sequence, researchers at Boston College, Chestnut Hill, Mass., have developed a process that can convert inexpensive alpha-olefins into a diverse range of organic compounds. The synthesis promises a rapid, more-efficient method to produce new compounds from non-functionalized terminal alkenes that generates less waste and reduces costs. The two catalytic reactions, developed in conjunction with Massachusetts Institute of Technology (MIT), Cambridge, Mass., when combined in a sequential process, result in unprecedented reaction with high levels of purity and selectivity (>95:5 enantiomer ratio), says James P. Morken, lead researcher and professor of chemistry at Boston College. The team first devised a catalytic enantioselective conversion of alpha-oefins into new boron compounds, then paired it with a palladium-catalyzed reaction developed by MIT (Figure 1). The combination of the diboration and cross-coupling reactions transforms the alpha-olefins into an array of chiral products. The shape of the chiral phosphonite ligand that is part of the platinum catalyst controls the formation of the enantiomer in the diboration, Morken notes. “Fortunately, the chiral phosphonite is easy to prepare and it is now commercially available …,” he adds. More details appear in a recent Nature article. Low loadings of catalysts and reagents, which are available on a multi-kilo scale, make the reaction amenable to large-scale synthesis. The dual-catalyst approach also provides an expansive substrate scope and can address a broad range of alcohol and amine synthesis. “The reaction can be used to produce an array of different products all from the same alkene starting material. This allows rapid exploration of chemical structure space,” Morken explains. Despite these benefits, Morken says challenges remain. “We always worry about catalyst efficiency — can loadings be lowered? And about green chemistry aspects — can we avoid the use of noxious reagents, minimize solvent use, and avoid purification of intermediates?” Morken now is capitalizing on the reactivity of the 1,2-diboron intermediate to participate in other transition metal-catalyzed processes, and has had some success in cross-coupling other electrophiles that are of use in target-oriented synthesis. “In this way, one can imagine an entire suite of stereoselective catalytic transformations of alpha-olefins that aren’t presently available,” he adds.

93.0 92.0 91.0 90.0 Jan 13

Feb 13

Mar 13 Apr 13 May 13 June 13 July 13 Aug 13 Sep 13 Oct 13 Nov 13 Dec 13

Capacity utilization

Shipments (NAICS S325)

Chemical Activity Barometer

All three indicators rose slightly. Source: American Chemistry Council.

Future research could include expanding the cross-coupling chemistry in many other directions. “For example, a process that involves C-N bond formation at the terminal carbon, followed by oxidation would provide a route to simple amino aminoalcohols, which are important building blocks,” Morken notes. DUAL-CATALYST SYSTEM

asymmetric diboration

L2B

BL2

cross-coupling

L2B

α-olefins

NH2 Ar

phenethylamines

OH Ar

fungicides

R chiral building blocks

Figure 1. An in-sequence diboration cross-coupling reaction converts alpha-olefins into new organic compounds. Source: James P. Morken.

chemicalprocessing.com

March 2014

in process When was the last time your site did an audit of its compressed air system?

35.9% Never

15.4% More than 5 years ago

More than one third of sites never have conducted a compressed-air audit, say respondents.

23.1% Within the last year

15.4% From 1-2 years ago

10.3% From 3-5 years ago

Responses (%) To participate in this month’s poll, go to ChemicalProcessing.com.

Morken also hopes to try the dual-catalyst system on a pilot plant scale as soon as someone wants to. “We have run the reactions on a multi-gram scale and would love an excuse to run them on an even larger scale,” he says. Eager to help people use the reaction if it solves their problems, Morken hasn’t claimed any

intellectual property for commercial use of the diboration chemistry. “The diboration cross-coupling tandem reaction sequence can target a lot of compounds that we already prepare by existing technology. It just gets to those same targets from different starting materials and often-times that can result in much shorter synthesis sequences. So, if anyone thinks that this technology could be of use in their enterprise, we 17.5%be more than happy to help in any way.” would Poor

Photoreaction Provides High Enantioselectivity The use of a Lewis acid as catalyst leads to photoreactions that favor the formation of a single enantiomer, report researchers at the Technical University of Munich, Munich, Germany. They performed [2+2] photocycloadditions on enone substrates, producing the desired enantiomer at high enantiomeric excess (ee), 80–92%, in a single step. “I believe the ee can be raised… to 95% by

further optimization,” notes Thorsten Bach, a professor of organic chemistry at the school. The Lewis acid is bulky and has a specific spatial structure that shields part of the enone substrate (Figure 2). Th is prompts production of a single enantiomer because the Lewis acidcomplexed enone requires a lower excitation energy than the substrate alone, explain Bach and doctoral student Richard Brimioulle in a recent article in Science. “The energy is not sufficient for the non-specific reaction of the uncomplexed substrate,” adds Brimioulle. The Lewis acid is released upon formation of the product and then can react with the next molecule. Currently, the researchers mainly are focusing on determining optimal Lewis acids for other substrates. “Key challenges are to fi nd Lewis acids which combine a strong absorption shift (i.e., selective excitation of the enone in the complex) with a high enantioface differentiation,” says Bach. “The [2+2] photocylocaddition is the shortest and, for many products, the only method to generate the cyclobutane ring. In this respect, everyone who needs to make cyclobutanes in

IMPACT OF LEWIS ACID

Figure 2. Lewis acid (top) shields one side of the substrate (bottom), favoring formation of the desired enantiomer. Source: Technical University of Munich.

enantiomerically pure form should be interested in our method,” he notes. The technique may suit selective synthesis of many diff erent substances, the researchers believe. They foresee it enabling quick and efficient production of even unusually complicated molecular frameworks from simple starting materials.

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ENERGY SAVER

Break Energy Audits into Phases, Part II After approval of projects, implementation can begin Once an energy audit team presents its findings, along with a prioritized list of actions, decision makers must decide which — if not all — recommendations should be implemented. (Keep in mind, unless the cost benefits of the recommendations are attractive, decision makers will focus on other compelling budget priorities.) Then, for those projects getting the go-ahead, the third phase of the energy audit cycle can begin. Implementing phase: The first step in the third phase of the energy audit cycle (Phases 1 and 2 were highlighted in last month’s column, “Break Energy Audits into Phases, Part I, www.ChemicalProcessing. com/articles/2014/break-energy-audits-into-phases/) is to develop an implementation plan. Each team should include members from relevant disciplines. Some recommendations, such as fixing steam leaks and reducing excess air levels at the fuel-fired boilers and heaters, are straightforward and require obvious actions. These projects can be started quickly, typically yield quick results, and require zero or little capital investment. For instance, in a graphite plant that molds and bakes calcined petroleum coke powder into large-sized electrodes, an energy expert attempted to control excess air at one of several baking furnaces to record the best-achievable operational settings. Because the baking cycle undergoes several stages of heating over a 72-hr period, a portable flue gas analyzer, along with the recordings of the existing on-line flue-gas oxygen analyzer, monitored and adjusted hourly the excess air level. Due to its capability of measuring the CO and combustible gas contents in flue gas, the portable flue gas analyzer trimmed the oxygen levels. A fuel-oil flow totalizer also recorded hourly readings from the baking furnace. This oxygen-trimming exercise resulted in developing a chart of operational settings for the baking furnace that established just 5% excess air achieved complete combustion at some stages of the baking cycle. The exercise also reduced fuel oil consumption 12% compared to the average fuel oil use per cycle recorded earlier in that same furnace. Some energy audit recommendations, such as those requiring partial or total plant shutdowns, need well-defined individual project plans and more-detailed engineering before implementation. Typically, these recommendations should be evaluated carefully with more supportive operating data as well as detailed cost estimations that should include budget quotes from equipment vendors and contractors. These projects typically take longer to implement.

For example, in a medium-sized oil-field chemicals manufacturing plant in Oklahoma, an energy audit produced seven recommendations. Management approved all seven and initiated detailed engineering development for each one. The results confirmed the savings levels for each recommendation, but the detailed project cost estimates for implementing them was much higher on two of them. So, management decided to implement the five projects that were still attractive. This stage also can help fine-tune the initial energy audit recommendations. For instance, in one of the projects (installing an economizer for a boiler), after a detailed review, engineers changed the heat recovery source from boiler feed water to soft water heated by steam. In another condensate recovery project, the group changed the initial suggested location of the condensate pump to facilitate future maintenance needs. Hence, detailed engineering is essential to make better investment decisions. Sustaining phase: As projects are implemented, the next phase focuses on measuring and quantifying results to determine whether the project achieved the initial envisioned goals. Measurements should verify the actual attained operational settings compared to the expected or set target levels. Deviations from the initial savings estimates commonly remain within 60–110% range. In most cases, the lower values in this range stem from inaccurate assumptions due to lack of flow measuring devices in the processes. Changes in the plant’s production levels also can cause deviations. Energy audits typically recommend installing permanent monitoring instruments to sustain the achieved results. Simple monitoring devices such as on-line flue-gas oxygen indicators contribute significantly to preserving optimum combustion conditions at fuel-fired boilers and furnaces. Adjusting maintenance programs and practices is another important requirement to sustaining energy audit results. This involves providing necessary preventive and predictive maintenance activities to the process equipment, and cleaning and calibrating monitoring devices. Timely troubleshooting support and prompt repairs during failures are essential to sustain the achieved energy savings. Periodically, a follow-up energy audit may be required to verify and sustain the results and to systematically repeat the cyclic process.

Some energy audit recommendations are straightforward.

Ven V. Venkatesan, Energy Columnist vvenkatesan@putman.net

chemicalprocessing.com

March 2014

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EPA Targets DecaBDE and BPA Agency has determined several safer alternatives to using the two chemicals On January 29, 2014, the U.S. Environmental Protection Agency (EPA) released two final Alternatives Assessment Reports for the flame retardant decabromodiphenyl ether (DecaBDE) and bisphenol A (BPA) in thermal paper. The EPA’s Design for the Environment (DfE) program developed the assessments, which profile the environmental and human health hazards for DecaBDE, BPA, and their alternatives. This article explains why these assessments are important. DfE, a federal EPA program started in 1992, works to prevent pollution and its health and environmental risks. The program provides information regarding a range of product categories, including electronics, flame retardants and safer chemical formulations. The DfE has three main goals: promoting green cleaning and recognizing safer consumer and industrial products through safer labeling; defining best practices; and identifying safer chemicals, taking into account life cycle considerations, through alternative assessments. Under the DfE program, products meeting EPA’s criteria are able to include on their labels “DfE,” an increasingly recognized symbol of product safety. Over 2,700 products carry the EPA DfE brand. DecaBDE is a flame retardant that has been used in electronics, vehicles, textiles and building materials. U.S. manufacturers of DecaBDE committed to phaseout production of the chemical by December 2013. The final DfE Alternatives Assessment Report on DecaBDE profiles 29 alternatives, including some predicted to be safer than DecaBDE. This report is part of a broader agency effort to address flame retardant chemicals. Additional information can be found at www.epa.gov/dfe/ pubs/projects/decaBDE/about.htm. The safety of BPA has drawn much attention over the years. BPA is widely used as a building block for plastics and to develop images on thermal paper, which is used in printed retail receipts, and in many other applications, such as airline and movie tickets. The EPA’s final BPA DfE Alternatives Assessment includes a review of 19 chemicals that may be used as heat-activated “developers” in thermal paper. The assessment found trade-offs with respect to human health or environmental safety for all of the possible alternatives. Information on this report can be found at www.epa.gov/dfe/pubs/projects/bpa/about.htm.

have on their health and on the environment. The commercial push we have witnessed over the past decade for “greener” and “safer” products reflects these growing market realities. Product manufacturers, particularly consumer product makers, are increasingly challenged to reformulate their product compositions to deselect components believed to pose risk and replace them with ingredients believed to be safer, and to manufacture their products using environmentally prudent production methods. Some product manufacturers may find this trend unsettling and challenging. The ability to reformulate products is not in all cases assured, and even if it were, product reformulation is costly and can be commercially risky. This is especially true for product ingredients that offer unique or highly specific properties or functionalities that have been specifically designed to work in concert with other product ingredients. Other product manufacturers choose to focus on the commercial upside. An EPA determination that a particular chemical poses risks, that there are alternatives to that chemical, and the EPA has found those alternatives to be efficacious and less harmful offer appealing and significant commercial opportunities. This is a key reason the DfE program is believed by many to offer considerable value to product manufacturers. EPA’s determination that alternatives to a particular chemical ingredient exist and are safer provides a comforting and commercially promising basis upon which to make product reformulation decisions. Other pressures driving product manufacturers to reformulate products include potential product liability and tort claims related to the products they offer to the public. Reformulating products and selecting the safest product ingredients possible, while still providing product efficacy and performance, increasingly is the option of choice to diminish a manufacturer’s potential product and tort liability. For more information on EPA’s DfE program, visit www.epa.gov/dfe/.

Reformulating products can diminish a manufacturer’s potential product and tort liability.

Lynn Bergeson, Regulatory Editor lbergeson@putman.net Lynn is managing director of Bergeson & Campbell, P.C., a Washington, D.C.-based law firm that concentrates on chemical

Implications

industry issues. The views expressed herein are solely those of

Consumers are increasingly aware of chemical exposures and the impact such exposures may

the author. This column is not intended to provide, nor should be construed as, legal advice.

chemicalprocessing.com

March 2014

GET TO THE

ROOT OF ACCIDENTS Systems thinking can provide insights on underlying issues not just their symptoms

By Nancy Leveson, Massachusetts Institute of Technology, and Sidney Dekker, Griffith University

MARCH 2014

CHEMICALPROCESSING.COM

An often-claimed “fact” is that operators or maintenance workers cause 70–90% of accidents. It is certainly true that operators are blamed for 70–90%. Are we limiting what we learn from accident investigations by limiting the scope of the inquiry? By applying systems thinking to process safety, we may enhance what we learn from accidents and incidents and, in the long run, prevent more of them. Systems thinking is an approach to problem solving that suggests the behavior of a system’s components only can be understood by examining the context in which that behavior occurs. Viewing operator behavior in isolation from the surrounding system prevents full understanding of why an accident occurred — and thus the opportunity to learn from it. We do not want to depend upon simply learning from the past to improve safety. Yet learning as much as possible from adverse events is an important tool in the safety engineering tool kit. Unfortunately, too narrow a perspective in accident and incident investigation often destroys the opportunity to improve and learn. At times, some causes are identified but not recorded because of filtering and subjectivity in accident reports, frequently for reasons involving organizational politics. In other cases, the fault lies in our approach to pinpointing causes, including root cause seduction and oversimplification, focusing on blame, and hindsight bias.

the accident investigation never went beyond the obvious symptoms of the deeper problems, no real improvement is made. The plant then finds itself in continual fire-fighting mode. A similar argument can be made for the common label of “operator error.” Traditionally operator error is viewed as the primary cause of accidents. The obvious solution then is to do something about the operator(s) involved: admonish, fire or retrain them. Alternatively, something may be done about operators in general, perhaps by rigidifying their work (in ways that are bound to be impractical and thus not followed) or marginalizing them further from the process they are controlling by putting in more automation. This approach usually does not have long-lasting results and often just changes the errors made rather than eliminating or reducing errors in general. Systems thinking considers human error to be a symptom, not a cause. All human behavior is affected by the context in which it occurs. To understand and do something about such error, we must look at the system in which people work, for example, the design of the equipment, the usefulness of procedures, and the existence of goal conflicts and production pressures. In fact, one could claim that human error is a symptom of a system that needs to be redesigned. However, instead of changing the system, we try to change the people — an approach doomed to failure. For example, accidents often have precursors that ROOT CAUSE SEDUCTION AND OVERSIMPLIFICATION are not adequately reported in the official error-reporting system. After the loss, the investigation report Assuming that accidents have a root cause gives us an recommends that operators get additional training illusion of control. Usually the investigation focuses in using the reporting system and that the need to on operator error or technical failures, while ignoring always report problems be emphasized. Nobody looks flawed management decision-making, safety culture at why the operators did not use the system. Often, problems, regulatory deficiencies, and so on. In most it is because the system is difficult to use, the reports major accidents, all these factors contribute; so to prevent accidents in the future requires all to be identi- go into a black hole and seemingly are ignored (or at least the person writing the report gets no feedback fied and addressed. Management and systemic causal it even has been read, let alone acted upon), and the factors, for example, pressures to increase productivity, fastest and easiest way to handle a detected potential are perhaps the most important to fix in terms of preproblem is to try to deal with it directly or to ignore venting future accidents — but these are also the most it, assuming it was a one-time occurrence. Without likely to be left out of accident reports. fixing the error-reporting system itself, not much As a result, many companies find themselves playheadway is made by retraining the operators in how to ing a sophisticated “whack-a-mole” game: They fix use it, particularly where they know how to use it but symptoms without fixing the process that led to those ignored it for other reasons. symptoms. For example, an accident report might Another common human error cited in investigaidentify a bad valve design as the cause, and, so, might tion reports is that the operators did not follow the suggest replacing that valve and perhaps all the others with a similar design. However, there is no investigation written procedures. Operators often do not follow procedures for very good reasons. An effective type of of what flaws in the engineering or acquisition process industrial action for operators who are not allowed to led to the bad design getting through the design and review processes. Without fixing the process flaws, it is strike, like air traffic controllers in the U.S., is to follow the procedures to the letter. This type of job action can simply a matter of time before those process flaws lead bring the system down to its knees. to another incident. Because the symptoms differ and 19

chemicalprocessing.com

March 2014

MENTAL MODELS Evolution and changes over time

Manufacturing and construction variances

Actual System Original design specification Designer deals with ideals or averages, not constructed system

Operational experience and experimentation

Operator’s Model

Designer’s Model

Operators continually test their models against reality

Operational procedures Training Figure 1. Designers and operators necessarily view systems differently.

Figure 1 shows the relationship between the mental models of the designers and those of the operators. Designers deal with ideals or averages, not with the actual constructed system. The system may differ from the designer’s original specification either through manufacturing and construction variances or through evolution and changes over time. The designer also provides the original operational procedures as well as information for basic operator training based on the original design specification. These procedures may be incomplete, e.g., missing some remote but possible conditions or assuming that certain conditions cannot occur. For example, the

procedures and simulator training for the operators at Three Mile Island nuclear power plant omitted the conditions that actually occurred in the well-known incident because the designers assumed that those conditions were impossible. In contrast, operators must deal with the actual constructed system and the conditions that occur, whether anticipated or not. They use operational experience and experimentation to continually test their mental models of the system against reality and to adjust the procedures as they deem appropriate. They also must cope with production and other pressures such as the desire for efficiency and “lean operations.” These concerns may not have been accounted for in the original design. Procedures, of course, periodically are updated to reflect changing conditions or knowledge. But between updates operators must balance between: 1. Adapting procedures in the face of unanticipated conditions, which may lead to unsafe outcomes if the operators do not have complete knowledge of the existing conditions in the plant or lack knowledge (as at Three Mile Island) of the implications of the plant design. If, in hindsight, they are wrong, operators will be blamed for not following the procedures.

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2. Sticking to procedures rigidly when feedback suggests they should be adapted, which may lead to incidents when the procedures are wrong for the particular existing conditions. If, in hindsight, the procedures turn out to be wrong, the operators will be blamed for rigidly following them. In general, procedures cannot assure safety. No procedures are perfect for all conditions, including unanticipated ones. Safety comes from operators being skillful in judging when and how they apply. Safety does not come from organizations forcing operators to follow procedures but instead from organizations monitoring and understanding the gap between procedures and practice. Examining the reasons why operators may not be following procedures can lead to better procedures and safer systems. Designers also must provide the feedback necessary for the operators to correctly update their mental models. At BP’s Texas City refinery, there were no sensors above the maximum allowed height of the hydrocarbons in the distillation tower. The operators were blamed for not responding in time although they had no way of knowing what was occurring in the tower due to inadequate engineering design. FOCUSING ON BLAME

Blame is the enemy of safety. “Operator error” is a useless finding in an accident report because it does not provide any information about why that error occurred, which is necessary to avoid a repetition. There are three levels of analysis for an incident or accident: • What — the events that occurred, for example, a valve failure or an explosion; • Who and how — the conditions that spurred the events, for example, bad valve design or an operator not noticing something was out of normal bounds; and • Why — the systemic factors that led to the who and how, for example, production pressures, cost concerns, flaws in the design process, flaws in the reporting process, and so on. Most accident investigations focus on finding someone or something to blame. The result is a lot of non-learning and a lot of finger pointing because nobody wants to be the focus of the blame process. Usually the person at the lowest rung of the organizational structure (the operator) ends up shouldering the blame. The factors that explain why the operators acted the way they did never are addressed. The biggest problem with blame, besides deflecting attention from the most important factors in an accident, is that it creates a culture where people are afraid to report mistakes, hampering accident investigators’ ability to get the true story about what happened.

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Putting Safety First

RELATED CONTENT ON CHEMICALPROCESSING.COM “Key Steps Spur More-Effective Root Cause Analysis,” www.ChemicalProcessing.com/articles/2014/key-stepsspur-more-effective-root-cause-analyses/ “Achieve Effective Process Safety Management,” www. ChemicalProcessing.com/articles/2013/achieve-effectiveprocess-safety-management/ “Process Safety Begins in the Board Room,” www. ChemicalProcessing.com/articles/2013/process-safetybegins-in-the-board-room/ “Orchestrate an Effective Process Safety Culture,” www.ChemicalProcessing.com/articles/2012/orchestratean-effective-safety-culture/ “Fight Over-Confidence,” www.ChemicalProcessing. com/articles/2012/fight-over-confidence/ “Make Safety Second Nature,” www.ChemicalProcessing.com/articles/2011/make-safety-second-nature/

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One of the reasons commercial aviation is so safe is that blame-free reporting systems have been established that find potential problems before a loss occurs. A safety culture that focuses on blame will never be very effective in preventing accidents. HINDSIGHT BIAS

Hindsight bias permeates almost all accident reports. After an accident, it is easy to see where people went wrong and what they should have done or avoided or to judge them for missing a piece of information that turned out (after the fact) to be critical. It is almost impossible for us to go back and understand how the world appeared to someone who did not already have knowledge of the outcome of the actions or inaction. Hindsight is always twenty-twenty. For example, in an accident report about a tank overflow of a toxic chemical, the investigators concluded “the available evidence should have been sufficient to give the board operator a clear indication that the tank was indeed filling and required immediate attention.” One way to evaluate such statements is to examine exactly what information the operator actually had. In this case, the operator had issued a command to close the control valve, the associated feedback on the control board indicated the control valve was closed, and the flow meter showed no flow. In addition, the high-level alarm was off. This alarm had been out of order for several months but the operators involved did not know this and the maintenance department had not fixed it. The alarm that would have detected the presence of the toxic chemical in the air also had not sounded. All the evidence the operators actually had at the time indicated conditions were normal. When questioned about

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REFERENCES 1. L eveson, N. G., “Engineering a Safer World: Systems Thinking Applied to Safety,” MIT Press, Cambridge, Mass. (2012). 2. Leveson, N. G., “Applying Systems Thinking to Analyze and Learn from Accidents,” Safety Science, 49 (1), pp. 55–64 (2011). 3. Dekker, S. W. A., “The Field Guide to Understanding Human Error,” Ashgate Publishing, Aldershot, U.K. (2006). 4. Dekker, S. W. A., “Just Culture: Balancing Safety and Accountability,” 2nd ed., Ashgate Publishing, Farnham, U.K. (2012).

this, the investigators said that the operator “could have trended the data on the console and detected the problem.” However, that would have required calling up a special tool. The operator had no reason to do that, especially as he was very busy at the time dealing with and distracted by a potentially dangerous alarm in another part of the plant. Only in hindsight, when the overflow was known, was it reasonable for the investigators to conclude that the operators should have suspected a problem. At the time, the operators acted appropriately. In the same report, the operators are blamed for not taking prompt enough action when the toxic chemical alarm detected the chemical in the air and finally sounded. The report concluded that “interviews with personnel did not produce a clear reason why the response to the … alarm took 31 minutes. The only explanation was that there was not a sense of urgency since, in their experience, previous … alarms were attributed to minor releases that did not require a unit evacuation.” The surprise here is that the first sentence claims there was no clear reason while the very next sentence provides a very good one. Apparently, the investigators did not like that reason and discarded it. In fact, the alarm went off about once a month and, in the past, had never indicated a real emergency. Instead of issuing an immediate evacuation order (which, if done every month, probably would have resulted in at least a reprimand), the operators went to inspect the area to determine if this was yet another false alarm. Such behavior is normal and, if it had not been a real emergency that time, would have been praised by management. Hindsight bias is difficult to overcome. However, it is possible to avoid it (and therefore learn more

from events) with some conscious effort. The first step ESCAPING THE WHACK-A-MOLE TRAP is to start the investigation of an incident with the Systems are becoming more complex. This comassumption that nobody comes to work with the inten- plexity is changing the nature of the accidents and tion of doing a bad job and causing an accident. The losses we are experiencing. This complexity, possible person explaining what happened and why it happened because of the introduction of new technology such needs to assume that the people involved were doing as computers, is pushing the limits that human reasonable things (or at least what they thought was minds and current engineering tools can handle. reasonable) given the complexities, dilemmas, tradeoffs We are building systems whose behavior cannot be and uncertainty surrounding the events. Simply high- completely anticipated and guarded against by the lighting their mistakes provides no useful information designers or easily understood by the operators. for preventing future accidents. Systems thinking is a way to stretch our intellecHindsight bias can be detected easily in accident tual limits and make significant improvement in proreports (and avoided) by looking for judgmental state- cess safety. By simply blaming operators for accidents ments such as “they should have …,” “if they would and not looking at the role played by the encomonly have …”, “they could have …” or similar. Note all passing system in why those mistakes occurred, we the instances of these phrases in the examples above cannot make significant progress in process safety from the refinery accident report. Such statements do and will continue playing a never-ending game of not explain why the people involved did what they did whack-a-mole. and, therefore, provide no useful information about RO-2931B Christine B. - Motionless MixerThey 1/2 pg Ad for Chem. Processing Mag. Size (Live): x 4.875LEVESON ” 4-C | Date: 12/11/12 | SCD#12ROSS108 causation. only serve to judge people for |what, in 7” NANCY is professor of aeronautics and astronauhindsight, appear to be mistakes but at the time may tics and professor of engineering systems at the Massachusetts have been reasonable. Institute of Technology, Cambridge, Mass. SIDNEY DEKKER Only when we understand why people behaved is professor of social science and director of the Safety Science the way they did will we start on the road to greatly Innovation Lab at Griffith University, Brisbane, Australia. E-mail improving process safety. them at leveson@mit.edu and s.dekker@griffith.edu.au.

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Optimize Water Cleanup

with Activated Carbon

Follow a few pointers to make the most of your adsorption system By Robert Deithorn, Calgon Carbon Corp.

Treating and reusing process water is a multidimensional challenge for process plants. Compliance with regulatory requirements to prevent and mitigate industrial pollution can require significant capital investment as well as ongoing maintenance outlays. The increasing scarcity and cost of fresh water for production processes also compounds the problem. (For insights on how major chemical manufacturers view water issues, see “The Tide is Turning,” www.ChemicalProcessing.com/articles/2013/sustainable-watermanagement-the-tide-is-turning/.) Ultimately, equally compelling pressures to address product purification needs, reduce the carbon footprint, and operate efficiently and profitably ratchet up the challenges. The hard truth is that process plants need a practical solution that’s economical and regulatory-compliant. For more than 40 years, no other method has offered better results for control of organic chemicals in liquids and gases than activated carbon adsorption. However, some plants undermine their treatment efforts. So, let’s go over a few pointers. DETERMINE THE BEST METHOD

Don’t presume that one process can handle everything. Instead, put in time to identify the most appropriate technology for the job(s) at hand. A wide range of treatment technologies, e.g., reverse osmosis (RO), ion exchange and granular activated carbon (GAC), exist and can be used alone or in combination for industrial water treatment. The most-appropriate technology depends upon the feed water quality and effluent water purity required for a given application. RO systems typically remove or reduce dissolved mineral salts, organics and other particles; they may require water pretreatment to protect the RO membranes against fouling, scaling or chemical degrada-

tion. Such systems usually incur higher investment and operating costs than a GAC system. Systems with ion exchange resins can produce highpurity deionized water for reuse by exchanging the ions present in the water. The choice of resin depends upon the specific ions present. These systems typically aren’t used to remove soluble organic species as GAC does. GAC is a highly porous, high-surface-area adsorbent onto which contaminant molecules collect. It has an excellent track record as a cost-effective material for removing organic contaminants from liquids and gases. At process plants, GAC finds wide use in liquid and gas purification and to purify and reuse process water. GAC also meets regulatory requirements in wastewater treatment, groundwater remediation and for volatile organic compound (VOC) abatement in vapor-phase applications. GAC technology can help plants maintain emissions permit levels, meet state and local environmental requirements, and adhere to U.S.

AVOID COMMON ERRORS Plants potentially can compromise the life and efficiency of their GAC by making some all-too-frequent mistakes: • Installing an activated carbon system based on process assumptions without an actual pilot test. Any trials should include appropriate comprehensive sampling and analysis so that the pilot can be meaningful and not simply raise more questions because insufficient results were obtained. Often the analytical costs will be the most significant portion of the pilot-plant costs. • Leaving spent carbon online for an excessive amount of time to save on change-out costs. This can make the spent carbon unsuitable for reactivation due to contamination level and calcification. • Overlooking the potential need for prefiltration. Undissolved contaminants and solids may limit access to the carbon and greatly reduce bed life. So, pretreat such streams to allow the activated carbon to focus on adsorption rather than having to contend with scaling or deposits.

chemicalprocessing.com

March 2014

CONSIDER SOME SUCCESSFUL RECENT APPLICATIONS One prominent chemical maker sought a cost-saving alternative to wastewater disposal. Specifically, it was looking for a way to reduce the organic chemical content of its process wastewater so that water could go to a water treatment unit at the plant. After evaluating the available options, the site installed a modular carbon-adsorption system configured as two adsorbers with connected piping; each adsorber contains 20,000 pounds of GAC and treats up to 100 gpm. Instead of using virgin carbon, the plant reduced its carbon footprint and costs by purchasing a large volume of reactivated-grade carbon and implementing an ongoing protocol for spent-activated-carbon reactivation by the carbon manufacturer. The chemical maker leased the carbon adsorption equipment from the carbon vendor, which also provided field service personnel for equipment maintenance and troubleshooting (Figure 1). A major international chemical manufacturer wanted to reuse its process wastewater, so it could decrease its raw water intake from a nearby river and reduce its discharge volume to a local wastewater treatment plant. A principal concern was whether carbon adsorption could adequately purify the wastewater, which contained organic contaminants detrimental to the final product. After a trial test proved satisfactory, the plant decided on a modular carbon-adsorption system configured as two adsorbers with connecting piping, with each adsorber containing 20,000 pounds of GAC and treating up to 100 gpm. The purified wastewater was recycled to the process. FIELD SERVICE

Environmental Protection Agency (EPA) guidelines and regulations such as the Resource Conservation and Recovery Act, the Clean Water Act and the Clean Air Act, particularly its National Emission Standard for Hazardous Air Pollutants program and benzene regulations. Recycling or thermally reactivating carbon gives process plants the opportunity to reduce cost and waste, save energy, lower carbondioxide emissions and conserve natural resources while decreasing the long-term liability of spentcarbon disposal. In fact, GAC has been classified as an EPA Best Available Technology (BAT) for removal of many organic contaminants. As defined by the EPA, “BAT effluent limitations guidelines, in general, represent the best existing performance of treatment technologies that are economically achievable within an industrial point source category or subcategory.” That being said, how does a chemical company determine if GAC adsorption is the best technology to meet its organic contaminant removal needs? SELECT THE RIGHT GAC`

Figure 1. Vendor usually handles the installation of fresh activated carbon.

March 2014

chemicalprocessing.com

A fundamental consideration is choosing the type of activated carbon that will deliver on your water purification and reuse goals. Virgin GAC is best reserved for initial system startup and reactivation of spent GAC (which we’ll discuss later). A standard, unimpregnated, bituminous-coal-based material made by the re-agglomeration method is used most often for adsorption of organic contaminants in industrial applications because it has a wide range of pore sizes to adsorb a broad variety of organic chemicals. Re-agglomerated GAC is produced by grinding the raw material to a powder, adding a suitable binder for hardness, recompacting

and then crushing to the specified size. Next, the material is thermally activated in a furnace using a controlled atmosphere and high heat. The resultant product has an incredibly large surface area per unit volume and network of submicroscopic pores where adsorption takes place. GAC has the highest volume of adsorbing porosity of any known material. Amazingly, five grams of re-agglomerated carbon have the surface area of one football field. Re-agglomerated carbon is generally preferred over direct activated because it’s a more-robust material with a fully developed porosity, and at the same time has the necessary strength to withstand use and reuse. To ensure optimal GAC adsorption operations, process plant installations typically include carbon adsorption equipment with the associated transfer piping. These systems can be operated with single- or multi-stage vessels, depending upon the desired treatment objective. The adsorption system generally follows chemical clarification and filtration and precedes disinfection, if these steps are required. Activated carbon can remove a variety of VOCs and semivolatile organic compounds in one unit operation. It’s important to fully characterize a stream prior to analyzing it for activated carbon purification. Information on a vapor-phase stream should include all VOCs and gases present, humidity concentration, temperature and pressure. All these factors will affect activated carbon performance. Similarly, characterization of a liquid-phase stream, including its ionic content and profile, types and concentrations of suspended solids, and pH, is crucial. Capacity tests that measure the mass of adsorbate removed per unit weight or unit

volume of activated carbon then can measure adsorption effectiveness. PILOT THE PROCESS

When considering a GAC system, a pilot plant study can determine if the technology will meet discharge permit requirements. Pilot plant testing of actual streams is the most reliable means to predict performance. Pilots should match the fullscale project equipment as closely as possible as far as superficial velocity, bed depth and empty bed contact time. For example, you can conduct an organic contaminant removal trial that uses a portable liquidtreatment unit and a liquid-phase GAC. Organics readily adsorbed by GAC include: • aromatic solvents (benzene, toluene and nitrobenzenes);

• chlorinated aromatics (polychlorinated biphenyls, chlorobenzenes and chloronaphthalene); • phenols and chlorophenols; • fuels (gasoline, kerosene and oil); • polynuclear aromatics, e.g., acenaphthene and benzopyrenes; and • pesticides and herbicides, e.g., DDT, aldrin, chlordane and hepthaclor. The pilot study also should quantify optimum flow rate, bed depth and operating capacity for a particular liquid or gas. This information is needed to determine the dimensions and number of carbon contactors required for continuous treatment. Other options also might be possible. For example, point source treatment of lower flows may

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provide a more-economical alternative than whole effluent treatment. Through use of computer predictive modeling or treatability studies, a supplier can determine if carbon adsorption technology can effectively reduce the concentration of the pollutants to levels that would allow discharge into the total wastewater stream — thus eliminating the need for more-expensive treatment methods for the total wastewater flow. By using these various studies and analyses, activated carbon manufacturers accurately can predict the viability as well as capital and operating costs of applying adsorption treatment, allowing you to compare these costs to those of other applicable technologies.

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During the carbon adsorption process, the available surface and pores of the GAC fill up with chemicals. At some point, the system no longer can meet the required performance criteria — often this is determined when the effluent quality from the carbon treatment vessels begins to approach the quality of the influent. The carbon is said to be “spent” and must be replaced. The spent carbon then either is discarded or recycled for reuse.

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Three alternatives exist for dealing with spent carbon. The first is shipping it to a landfill or incinerator. However, this approach necessitates the purchase of new carbon and isn’t the most environmentally friendly. Regeneration via either a chemical or steam process may offer advantages over disposal in a landfill. However, this option generally is reserved for recovering and reusing a valuable adsorbate. It also is less efficient than reactivation.

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RELATED CONTENT ON CHEMICALPROCESSING.COM “Plants Save Water,” www.ChemicalProcessing.com/articles/ 2013/chemical-processing-plants-save-water/ “The Tide is Turning,” www.ChemicalProcessing.com/articles/ 2013/sustainable-water-management-the-tide-is-turning/ “Every Drop Counts,” www.ChemicalProcessing.com/articles/ 2012/every-drop-counts/ “Water Turns Green,” www.ChemicalProcessing.com/articles/ 2011/water-turns-green-for-sustainability/ “Optimize Water Use,” www.ChemicalProcessing.com/articles/ 2005/571/

The third option, high-temperature thermal reactivation, usually makes the most sense. The process destroys the adsorbed organic compounds and restores the GAC’s adsorptive capacity. Reactivation can achieve up to 95% recovery of the virgin activated carbon’s capacity. The reactivated material then can be blended with a small amount of virgin carbon to make up for the minor loss of volume. Over the past few years, reactivation and reuse have surged in popularity at process plants for several reasons. From an environmental standpoint, reactivated carbon is considered an environmentally friendly product because reactivation produces only about 20% of the greenhouse gases generated in making virgin activated carbon. Moreover, GAC has a nearly infinite reactivation capability, so it rarely ends up in a landfill or incinerator. Reactivation is a logical choice for companies that

incorporate sustainability in their long-term strategy. Reactivation also delivers significant cost savings — it typically costs 20–40% less than purchasing virgin GAC. In addition, it ends the chain of custody for adsorbed contaminants, eliminating spent carbon handling and disposal liabilities. Some facilities may qualify to receive environmental credits issued by regulatory agencies for waste minimization because reactivated carbon is considered a recovered resource. The profiling and testing processes to identify reactivation as an option are very straightforward. Depending upon the economics and volume of spent carbon produced, some plants may opt for onsite reactivation facilities. Those deciding to contract for off-site reactivation services should look for a vendor with the following field capabilities: • spent carbon analyses; • spent carbon removal and packaging; • appropriate waste handling (hazardous or nonhazardous); • transportation to the reactivation plant; • carbon vessel inspection with minor repair; and • vessel reloading with reactivated carbon. TACKLING EMERGING APPLICATIONS

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Carbon adsorption has treated some organic contaminants for more than four decades and is considered a mature technology. However, its role promises to expand as the EPA regulates additional chemicals. The agency maintains a contaminant candidate list of chemicals of emerging concern (CECs) that the EPA may consider for future regulation. Some carbon manufacturers like Calgon Carbon provide forward-looking assistance to chemical makers by monitoring the CEC list, offering a preview of what federal and state rules may require for treatment technologies, and conducting research and development to advance the use of activated carbon and treatment methods for removing CECs. Every chemical manufacturer must contend with the ongoing demands of achieving regulatory compliance while maintaining operational profitability and creating high-quality products. For organic contaminant removal from liquids and gases in process applications, GAC remains a proven, reliable way to satisfy environmental management demands and product purification needs. Furthermore, use of reactivated carbon instead of virgin carbon offers additional cost efficiencies and environmental benefits. ROBERT DEITHORN is business unit product director for Calgon Carbon Corp., Pittsburgh, Pa. E-mail him at info@ calgoncarbon-us.com.

CAREFULLY CONSIDER

NOZZLE LOADS Choices can impact piping design as well as equipment reliability By Amin Almasi, rotating equipment consultant

PIPING LOADS that can be imposed on machinery nozzles (such as those of pumps, compressors, etc.) should be restrained within certain limits. Piping designers always want higher allowable nozzle loads to simplify piping designs while machinery manufacturers want smaller allowable nozzle loads to ensure good alignment, higher reliability and fewer complaints about operation. Process plant operators place great importance on long-term reliability of equipment and, so, generally should side with the machinery manufacturers. Regardless, it’s essential for all parties to agree upon optimum nozzle loads for any machinery package. Let’s look specifically at nozzle loads for pumps and compressors. Pump nozzle loads. These are specified in the pump’s codes and standards (for example, API 610). The API 610 standard covers nozzle loads for horizontal pumps, vertical in-line pumps and vertically suspended pumps for nozzle sizes up to 16 in. (400 mm). For larger pump nozzles, come to an agreement with the vendor about nozzle loads before placing the order. Figure 1 depicts a piping design for horizontal pumps. Figure 2 shows real piping of an electric-motor-driven pump in a process plant. Generally, small pumps not anchored to their foundations can tolerate higher nozzle loads than anchored ones. Allowable nozzle loads for vertical in-line pumps with supports not anchored to the foundation could be twice those of anchored pumps. Compressor nozzle loads. For centrifugal compressors, the API 617 standard specifies the nozzle load limits. However, many purchasers usually ask for two times the API 617 nozzle loads (2×API 617) to make piping design easier. While some machinery engineers and vendors may consider the API nozzle-load values optimum, in many situations piping engineers and stress analysis specialists can’t achieve these values. A higher value (particularly 2×API 617) is a good solution to allow piping without expansion joints at nozzles or to avoid very complex piping systems. For special applications with very large differences between operating and ambient temperatures and very large nozzle sizes, it may make sense to specify a nozzle load three times the API 617 values (3×API

617). Figure 3 shows an example of large compressor piping. Assign relatively low nozzle loads to integrally geared centrifugal compressors or rotating machines primarily designed for low pressures (such as some axial compressors, low-pressure overhung compressors, and machinery with open impellers) that rely upon close radial and axial clearances of rotating components (impeller or rotor assemblies) to machinery casings. For these compressors, allowable nozzle loads above conventional values in the API 617 standard aren’t feasible. While the nozzle loads in AP I 617 usually can be achieved, the nozzles loads often instead are limited to 0.9×API 617. In any event, come to an agreement with the vendor on suitable nozzle loads before ordering such machines. For screw compressors, the API 619 standard recommends nozzle loads. The nozzle loads of reciprocating compressors are left for the purchaser and HORIZONTAL PUMP PIPING

Figure 1. This layout typifies piping design for horizontal pumps.

CHEMICALPROCESSING.COM

MARCH 2014

PROCESS PUMP

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Figure 2. Electric-motor-driven pumps such as this are common at process plants.

vendor to jointly set. Generally, screw or reciprocating compressors come as packages; the purchaser and vendor should agree upon allowable nozzle loads at vendor interfaces.

To achieve maximum reliability, a machinery engineer’s goal usually is to keep nozzle loads as low as practical. However, piping designers and stress analysis engineers generally design piping systems based on allowable (i.e., maximum) or even sometimes slightly higher than allowable nozzle loads to avoid very complex and expensive piping systems. The piping should have optimum flexibility to prevent distortion of machinery alignment or component damage. So, it’s important to carefully consider two effects of nozzle loads: 1. Internal alignment problems, i.e., distortion of a machine’s casing and internals. Misalignment of internal machine components will create accelerated wear, rubbing or even early failure. 2. External alignment problems, i.e., misalignment of various shafts in a machine’s train — for example, between a driven shaft and a driver shaft. The effects of external misalignment might not be as obvious as those from internal misalignment. However, external misalignment in time will take a toll.

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RELATED CONTENT ON CHEMICALPROCESSING.COM “How Much Will Your Compressor Installation Cost?,” www. ChemicalProcessing.com/articles/2014/how-much-will-yourcompressor-installation-cost/ “Apply Wet Screw Compressors Wisely,” www.ChemicalProcessing.com/articles/2013/apply-wet-screw-compressorswisely/ “Enhance Centrifugal Pump Reliability,” www.ChemicalProcessing.com/articles/2013/enhance-centrifugal-pump-reliability/ “Choose the Right Air Compressor,” www.ChemicalProcessing.com/articles/2013/choose-the-right-air-compressor/ “Make the Most of Reciprocating Compressors,” www. ChemicalProcessing.com/articles/2013/make-the-most-ofreciprocating-compressors/ “Correctly Commission Rotating Equipment,” www.ChemicalProcessing.com/articles/2013/correctly-commission-rotatingequipment/ “Rethink Options for Large Drivers,” www.ChemicalProcessing.com/articles/2013/rethink-options-for-large-drivers/ “Avoid Bad Turns with Rotating Equipment,” www. ChemicalProcessing.com/articles/2012/avoid-bad-turns-withrotating-equipment/

MONITOR VISCOSITY SIMPLY SENSE MIXER MOTOR HORSEPOWER WITH UNIVERSAL POWER CELL EASY INSTALLATION • No holes in tanks or pipes • Away from sensitive processes VERSATILE • One size adjusts to motors, from small up to 150hp • Works on 3 phase, ﬁxed or variable frequency, DC and single phase power

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Figure 3. Large centrifugal compressors often are piped in this way.

Vibration levels increase as couplings become misaligned. A high vibration trip could result in an unscheduled outage. Extended operation at high levels of misalignment could cause coupling failure, possibly bearing damage or even catastrophic failure. To minimize misalignment of various shafts in a machine’s train because of piping load effects, it’s crucial to ensure that train casings, casing supports and baseplate(s) have sufficient structural stiff ness to limit displacements of casings and shafts. Differences in thermal growth as well as errors in piping fabrication, and alignment all contribute to actual deflection values and fi nal nozzle loads achieved in the field. Avoid to the maximum extent possible the use of expansion joints — they are expensive and maintenance-prone. Instead, put in more bends or loops to accommodate expansion. Also, avoid conservative stress analysis. One modern approach is to have the vendor model the entire system (including the piping and the machinery) at the same time. Concurrent modeling can reduce inherent conservatism and could allow the thermal movements to be accommodated correctly by both systems. Th is may result in a more-flexible combined system and can allow better optimization. Elimination of the expansion joint often can pay for the engineering time needed to remodel, re-evaluate and redesign the entire system. Ideally, include such an optimization-simulation in the vendor scope before the order. AMIN ALMASI is a rotating equipment consultant based in

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Brisbane, Australia. E-mail him at amin.almasi@ymail.com.

WIDESPREAD WIRELESS BECKONS Unprecedented amounts of data promise real value but security remains a concern By Seán Ottewell, Editor at Large

THE RISE of wireless sensing technologies that are multivariable and self-powered, cover wide areas, and are easy to configure and maintain presents both solutions and challenges to the chemical industry. For operating companies, such technologies allow access to hitherto unknown levels of process data, opening a vista of vastly improved process control and management. For vendors, the challenge is to both improve and increase the range of existing sensors, and to ensure that all the data from them is presented in such a way that customers can drive plant efficiency and profitability. Ultimately, though, wide acceptance will depend upon making these new technologies totally secure. The benefits of such sensing regimes already are emerging. At the Emerson Global Users Exchange in Grapevine, Texas, last October, a speaker from the Flint Hills Resources refinery in Pine Bend, Minn., explained how using wireless vibration transmitters for continuous fault detection had reduced maintenance costs dramatically and prevented possible catastrophic failures. Similarly, a speaker from Fluor, Irving, Texas, recounted how one of its customers used wireless acoustic transmitters to provide instant alerts about failed steam traps, saving $36,000 in the first year. For Emerson, these are tangible outcomes of its

new “pervasive sensing” strategy that stemmed from a review of customers’ requirements to improve plant safety, reliability and energy efficiency. The company believes it has found a “business critical” space next to its traditional process control space — one that could be worth $16 billion. “Pervasive sensing is an outcome, not a set of products,” notes Eric Milavickas, wireless, sales and marketing director, Emerson Process Management, Chanhassen, Minn. “These business-critical results are achieved with incremental investments that acquire new insight without adding complexity, all while increasing profitability and productivity.” Pervasive sensing has three basic elements: sensor technology that enables data collection, industry expertise that analyzes the data, and actionable information that communicates to the customer what action to take and when (Figure 1). BROAD UTILITY

Milavickas cites the example of stream traps. A typical chemical facility might have more than 4,000 of them, 800–1,000 of which are critical. “For an $800,000 investment, a typical return can be achieved [in] anywhere from 6–14 months depending on the cost of the steam and the size of 39

CHEMICALPROCESSING.COM

MARCH 2014

ACTIONABLE INFORMATION

Figure 1. Data from wireless devices coupled with industry expertise can help guide steps a plant should take. Source: Emerson.

the various traps. In addition to the energy savings, there is an incredible safety and reliability message that helps the customer avoid a water hammer situation and keep their overall system working more optimally. Once you analyze the steam trap and generate the right information about that individual piece of equipment, we are then able to take that data and convert it into actionable information for the customer.”

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It’s a similar story with capital equipment such as heat exchangers, pumps and compressors: with pervasive sensing, it’s possible look at the oil level in a pump seal and also to monitor changes in vibration in the pump. “Using software analysis of the data, we can give customers actionable information,” he explains. One unnamed customer — the operator of a next-generation process plant — is determined to seize the opportunities offered by pervasive sensing to substantially increase the number of measurements. The facility already has installed 20,000 process-critical instruments. Now, it aims to boost measurements by 60% for business-critical applications, adding an extra 2,000 personal-safety, 8,000 reliability and 2,000 energy measurements. Pervasive sensing also is attracting interest from customers that transport products. One barge owner on the Mississippi requires 24-hour remote monitoring to verify accurate custody transfer of oil. “The customer wanted to know if we could continuously monitor level transmitters for them, something which is critical to ensure proper business practices are taking place. We see this more and more on moving tanks, such as on rail or trucks,” says Milavickas. One major hurdle with pervasive sensing is making sure that customers can reap the benefits of all the new data to which they have access. “Th is is one of the basic challenges for us,” admits Milavickas. “We have the basic software and, at the moment, we are working on making it easier to get to the information. In the visionary case, we are looking at web-based solutions, i.e., you could download an app to get the interface you want. In October we launched a PC Navigator, which is essentially hardware with software enabled on it that allows the customer to manage their entire wireless system. Th is is our fi rst tool for marrying wireless infrastructure together. We will continue to develop this product and have a more defi nite perspective on it by the end of 2014.” Customers’ internal structure poses another hurdle. “They definitely see the value but what they don’t have is a ‘wireless manager’ — someone who sits between IT [information technology] and process control. Both sides have different priorities and neither fully understands the wireless role. So customers do have to change their internal structures and functions. However, we are seeing more and more recognition from customers who realize that they need these internal practices to really recognize the value of pervasive sensing,” notes Milavickas.

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Preferred Solution for NH3 Emissions Abatement with Minimal Change in NOX Emissions In a batch production unit, two product formulations were produced. The same emission control system had to cope with the two formulations, although they generated two distinct emission profiles: Formulation A produced a NOX emission greater than its NH3 emission; Formulation B produced a NOX emission much less than its NH3 emission. Although an SCR catalyst with supplemental NH3 injection was suitable for Formulation A, it was ineffective for Formulation B, since a significant amount of the NH3 emission remained unreacted through the SCR catalyst due to a lack of NOX. A standard oxidation catalyst was installed, but soon proved inadequate as it converted too much of the NH3 to NOX. Once BASF NOXCAT™ AD Catalyst replaced the standard oxidation catalyst, the emissions abatement system reliably controlled both NOX and NH3 emissions for all batch calcination formulations, having reduced NH3 emissions by over 98% to less than 10 mg/Nm3 with no net impact on NOX emissions and no extra pressure drop penalty from the original design. Formulation A

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as BASF NOXCAT™ AD Catalyst enabled NH3 slip emissions control independent of the NOX concentration in the exhaust gas. Throughout the batch production cycle, the NH3 slip in the stack was controlled consistently to less than 10 mg/Nm3, which was equivalent to as much as 99% NH3 conversion, with no net impact on stack NOX emissions.

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RELATED CONTENT ON CHEMICALPROCESSING.COM “CP Wireless Resource Center,” www.ChemicalProcessing.com/ resource-centers/wireless/ “Cyber Security Challenges Continue,” www.ChemicalProcessing. com/articles/2013/cyber-security-challenges-continue/ “Energy Harvesting Widens Wireless’ Appeal,” www.ChemicalProcessing.com/articles/2013/energy-harvesting-widens-wireless-appeal/ “Low-Cost Monitoring Protects Pricey Pump,” www.ChemicalProcessing.com/articles/2012/low-cost-monitoring-protects-pricey-pump/ “Plant of the Future: Whither Wireless?,” www.ChemicalProcessing.com/articles/2009/112/ “Protect Your Plant,” www.ChemicalProcessing.com/articles/2008/127/

OTHER ADVOCATES

Endress+Hauser also is promoting the value of widescale wireless sensing. “Using sensors with wireless as an enabling technology allows you to collect and share data — and consequently process information — into the higher level systems. Wireless in this context offers the possibility to access in a cost-effective way information on the plant that has previously been restricted due to location or cost,” says John Salusbury, director corporate marketing, Endress+Hauser Consult, Reinach, Switzerland. A recent project at PZ Cussons, Manchester, U.K., illustrates the point. Together with alliance partner Rockwell Automation, Endress+Hauser installed level, flow, temperature and pressure sensors on a new high-speed liquids manufacturing facility. The improved process and diagnostic data now available have enabled PZ Cussons to increase production, meet tougher quality targets, reduce downtime and enhance the accuracy of its validation procedures. Shorter batch times also have led to energy savings and reduced time to market for products. As a result, the company will continue manufacturing its homecare, personal care, beauty and nutrition brands in the U.K. instead of transferring production abroad, as it had been considering. Meanwhile, Yokogawa Electric, Tokyo, Japan, is promoting

its Wireless Anywhere concept, which advocates plantwide use of field wireless systems, particularly by the chemicals and petrochemicals industries. In line with that initiative, the company announced in February that it has developed a multiprotocol wireless adaptor to enable wired field instruments or analytical sensors to function as ISA 100 wireless devices. The adaptor can be mounted on devices commonly used in plants, including those for monitoring temperature, pressure, liquid level or vibration or detecting gas, and is compatible with instruments and sensors from both Yokogawa and other vendors. The first two models are intended for wired HART and RS485 Modbus communications, with later releases aimed at other standards including Foundation Fieldbus and Profibus. A REFINER’S INITIATIVE

BP has announced the successful deployment of the Permasense integrity monitoring system at all company-operated refineries as part of its refining and logistics technology program (Figure 2). The system now is being piloted at BP upstream and alternative energy facilities. Developed by monitoring systems specialist Permasense, Horsham, U.K., in partnership with Imperial College London and BP, the system reportedly offers corrosion engineers, inspectors,

planners and plant managers previously unavailable insights into the condition and capability of critical oil and gas assets. Sensors can be permanently attached to pipes operating in extreme temperatures and in difficultto-access locations. The sensors then are linked via a wireless network to provide data directly to the user for single viewings or integration into other plant monitoring systems. The early warning system enables BP teams to monitor the effectiveness of corrosion mitigation strategies and intervene, if necessary, to prevent or minimize leaks and any associated environmental impacts caused by corrosion. Unlike conventional corrosion monitoring, which can be expensive to perform and doesn’t always identify unexpected changes in wall thickness at an early stage, the new system provides more consistent and robust data at no incremental cost after the initial installation. THE SECURITY CHALLENGE

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— worry about security. So, vendors are working on an ongoing basis to bolster security. For instance, Emerson’s Milavickas notes, “Ensuring security of data inputs is a constant challenge and we continually monitor and upgrade — doing everything we deem possible for the highest levels of security.” Security concerns likely ratcheted up recently because of a talk in January at Digital Bond’s 7th annual SCADA Security Scientific Symposium in Miami Beach, Fla. Alexander Bolshev of ERPScan, St. Petersburg, Russia, gave a presentation in which he demonstrated how HART has the same insecureby-design issues as other industrialcontrol-system protocols. He showed how access to the 4–20mA control loop could be used to attack the entire plant, including applications and protocols that appear to be unrelated to HART. “These findings are not new, but they are significant. None of the fieldbus/communications protocols were designed with security in mind and some are 20-odd-years old now,” says Eric Byres, CTO and VP engineering of Tofino Security, Lantzville, B.C. “Protocols such as HART and HART over IP are losing their ‘security by obscurity’ protection and are easy to hack — and once someone takes aim at them, the devices all are badly flawed. Once we were secure because we were obscure. Now we aren’t and as a result we are a lot more vulnerable,” he cautions. He urges vendors to ensure their products are ISA 100 certified. “Since Shamoon in the Middle East, the market there is demanding that vendors build the highest levels of security into their devices. These demands will come to North American and Europe, too.”

making it work

Plant Assesses Alarm Displays Trial finds that many operators prefer an alternative visualization approach By Peter T. Bullemer and Dal Vernon C. Reising, Human Centered Solutions, Mischa Tolsma, Shell, and Jason C. Laberge, Alberta Health Services

Alarm flooding is the phenomenon of presenting more alarms in a given time period than a human operator can effectively address. A significant finding of a 2006 research project of the Abnormal Situation Management (ASM) Consortium (www. asmconsortium.net) was that even though configuration techniques can significantly reduce the size of the alarm flooding associated with process upsets, these techniques on their own don’t suffice to reduce the alarm loads to a level at which human operators can mentally process and physically respond. A key need that remains is to provide effective alarm summary displays to help operators cope with these inevitable alarm floods. In plants where modern distributed control systems (DCSs) are installed, alarms are presented via scrolling lists on console monitors instead of via dedicated annunciator tiles as was done on older directwired panel boards. The traditional practice is to show alarms using a chronologically sorted list-based alarm summary display. The usability challenges of this display during an alarm flood include the fact that alarms move through the list and off the page faster than a typical operator can read them [1, 2]. The viewable list for a given page also fills up quickly; operators must scroll or change pages to see all the alarms that

are occurring — taking their attention away from their operating displays and wasting valuable time. A consequence of the scrolling list is that alarms will move down the list as the operator actually is trying to read it; so to read the alarm details, the operator’s gaze must descend at the same rate as the changing alarm position. Higher priority alarms also will be scrolled off a given page as it fills up while the operator’s attention is directed elsewhere. Similarly, alarms that came in earlier in the flood (and that the operator may be “chasing” on other operating graphics) will have moved to successive pages in the alarm summary display. Therefore, the operator won’t notice if any of these “clear” on their own accord. It is apparent that the rapidly changing, chronological list-based alarm summary display installed in most process plants doesn’t support the operator’s situation awareness. The alarm list display tends to be too detailed with the presentation of sequential information and lacks the functional organization necessary to understand the nature and progress of a disturbance. Therefore, the ASM Consortium members decided to explore alternative visual display techniques that might improve operator situation awareness during plant upsets that result in these inevitable alarm flood situations [3, 4].

chemicalprocessing.com

March 2014

MAKING IT WORK

EXPLORING ALTERNATIVES

The consortium conducted a series of studies in 2007–2008 with experienced console operators in a controlled experimental setting to examine how two alternative visualization techniques compared to the traditional list-based alarm display (Figure 1) on operators’ ability to respond to alarm flood scenarios. Alternative Visualization No. 1 was an alarm display with an equipment-based overview — each major equipment area for which the console operator is responsible is represented at the top of the display in a single or double row of alarm panels. The panels are arranged in a left-to-right organization that intuitively reflects the plant process flow or geographical arrangement. Within each panel, alarm indicators are arranged vertically with the most recent alarms appearing at the top. Each alarm indicator provides key attributes such as alarm priority, acknowledgement status, alarm type, parameter type and a short tag descriptor. A mouse-over with the cursor results in the display of a full alarm description. The selection of a specific equipment area panel focuses the content of the detailed list (i.e., just below the overview) on alarms for just that area. Alternative Visualization No. 2 was an alarm display with a time-based overview — each major equipment area for which the console operator is responsible is represented at the top of the display in rows of alarm panels (i.e., consistent with the two other summary displays). The panels are arranged in a top-to-bottom organization that intuitively reflects the plant process flow or geographical arrangement. Within each panel, alarm indicators are arranged horizontally with the most recent alarms appearing on the right (in a fashion similar to a trend display with the most recent information on the right). The

selection of a specific equipment area panel focuses the content of the detailed list on alarms for just that area. The study participants were volunteers — 45 active console operators from four plants in the Sasol Secunda Synfuels operations. Each operator received a two-hour familiarity training session on the display concepts and the alarm response task. In the performance evaluation sessions, each operator handled alarm floods in six simulated scenarios. The operators were asked to respond to an individual alarm or a group of alarms in the alarm scenario by pointing out where in the plant the problem was (i.e., specific unit and particular piece of equipment), what the key alarms were (i.e., indicators) and what underlying abnormal conditions were signified (i.e., conditions). As the alarms were appearing on the alarm summary displays, the participants continuously were trying to detect and interpret as many alarms as possible to respond to the underlying abnormal plant conditions. The alarm flood scenarios lasted from 8 to 10 minutes. The average alarm rate across the flood scenarios was 110 per 10 minutes, with a range of 32 to 316 total alarms. The number of unique alarms averaged 30 per 10-minute scenario, with a range of 14 to 42. The number of plant equipment areas ranged from 6 to 11. In the familiarity training session, operators were shown an “effective” alarm response strategy to help improve situation awareness during alarm flooding situations. This effective strategy, which could be used with the traditional list-based display as well as with the new alternative displays, comprised: • using the summary view to determine what equipment area required attention; • selecting just that area for viewing in the alarm list;

RELATED CONTENT ON CHEMICALPROCESSING.COM “CP Webinar: Alarm Management — Proven Methods to Alleviate Alarm Issues,” www.ChemicalProcessing.com/webinars/ “Properly Handle Abnormal Situations,” www.ChemicalProcessing.com/articles/2013/properly-handle-abnormal-situations/ “Make Some Alarming Moves,” www.ChemicalProcessing.com/articles/2012/make-some-alarmingmoves/ “How Many Alarms Can an Operator Handle?,” www.ChemicalProcessing.com/articles/2011/howmany-alarms-can-an-operator-handle/ “Avoid the Domino Effect,” www.ChemicalProcessing.com/articles/2010/033/ “Choose an Alarm Champion,” www.ChemicalProcessing.com/articles/2010/076/ “Consider State-Based Control,” www.ChemicalProcessing.com/articles/2010/051/ “Adroitly Manage Alarms,” www.ChemicalProcessing.com/articles/2009/074/ “Avoid Alarm Blunders,” www.ChemicalProcessing.com/articles/2006/091/ “Rescue Your Plant from Alarm Overload,” www.ChemicalProcessing.com/articles/2005/209/

MARCH 2014

CHEMICALPROCESSING.COM

• evaluating the pattern of alarms in that area; • completing the alarm response task in an Access database form; • returning to the alarm list; and • acknowledging all alarms (as opposed to acknowledging individual alarms). Less effective strategies were characterized by: • not focusing the alarm list by equipment area and acknowledging all alarms in the alarm list while all units were shown; or • not focusing the alarm list by equipment area and only acknowledging single alarms.

ALARM DISPLAYS USED

THE RESULTS

The trial generated three key findings: 1. The effectiveness of a particular display design can be influenced by the alarm response strategy used when interacting with that display. The study results found both effective and ineffective strategies for all three alarm-summary display designs. Most importantly, all three designs provided features that enabled operators to strategically focus the contents of the detailed alarm list view on a specific equipment area of interest to reduce the number of alarms seen. Significant positive correlations were found between the operators’ alarm response score, indicating better situation awareness, and their respective effective strategy score. Moreover, the benefit of the effective alarm strategy was greater with the time-based overview visualization technique than with the traditional list-based alarm summary display. This strategy was impactful because it allowed the operators to be aware of more alarm conditions and see patterns in the alarms associated with an equipment area that were not readily perceptible when distributed within the list of all alarms. 2. The effective response to alarm flood conditions may depend upon operator training. Another observation from the study was that — despite the project team purposefully training each operator on the effective strategy of using the summary view to focus what equipment area was in the alarm list — many operators reverted back to the strategy they brought to the study, based on how they interact with the existing DCS alarm summary display (similar to the industrytypical display used in the study). The consequence of this very common behavior was that each of the three display conditions essentially was reduced to a single alarm list, with no summary information being used. The training session didn’t include feedback on performance. Hence, some operators thought they actually performed better when they didn’t use the effective alarm response strategy. In fact, some had the mistaken perception they were performing better

Figure 1. Operators evaluated two alternatives as well as traditional list-based visualization.

because they were aware of fewer alarms, i.e., they weren’t aware of what they weren’t responding to. Training that includes feedback on performance has a better chance of establishing the value of using the effective alarm response strategy. 3. With the option to choose display type, the operators prefer the new time-based display to the traditional display. An alarm summary display with the timebased overview was installed in a control room for three months to allow operators to get familiar with the display during a pilot study period. That control room has two console areas, each devoted to a specific processing unit. In one console area, half the operators chose to use the new display over the traditional display during their normal shift duties. In the other, all the operators opted to use the new display. Operators reported they were better able to associate groups of alarms with specific equipment areas and contextualize alarms in time in terms of old and new concerns. After the pilot was completed, the operators requested the prototype display be left in the control room. In conclusion, the ASM research studies revealed some promising findings on alarm presentation techniques that can enable operators to better manage plant upset situations that result in alarm floods. Past research has revealed significant usability issues with the traditional presentation in list format. The Sasol trial showed that console operator performance improved with all the alarm presentation techniques when an effective alarm response strategy also was used. Specifically, the study demonstrates that operator performance under alarm flood conditions can be upgraded if the operator interface allows the operator to strategically view subsets of the alarms associated 47

chemicalprocessing.com

March 2014

MAKING IT WORK

REFERENCES 1. Bransby, M., “Design of Alarm Systems,” p. 207 in “People in Control: Human Factors in Control Room Design,” J. Noyes and M. Bransby, eds., Institution of Electrical Engineers, London, U.K. (2001). 2. Brown, W., O’Hara, J. and Higgins, J., “Advanced Alarm Systems: Guidance Development and Technical Basis,” (NUREG/C$6684), U.S. Nuclear Regulatory Commission, Washington, D.C. (2000). 3. Bullemer, P. T., Tolsma, M., Reising, D. C. and Laberge, J. C., “Towards Improving Operator Alarm Flood Responses: Alternative Alarm Presentation Techniques,” Proceedings of the ISA Automation Week Conference (Chicago, Ill.), ISA, Research Triangle Park, N.C. (2011). 4. Laberge, J., Bullemer, P., Tolsma, M., and Reising, D., “Addressing Alarm Flood Situations in the Process through Alarm Summary Display Design and Alarm Response Strategy,” accepted for publication in Intl. Journal of Industrial Ergonomics.

with specific equipment areas rather than a list containing all the alarms. The time-based overview visualization coupled with an effective alarm response strategy produced the best alarm awareness. Future research examining the impact of potential enhancements to the new display concepts might provide additional insight on how to resolve this significant challenge in the process industries. Meanwhile, Sasol has chosen to adopt the new visualization developed on the Honeywell Experion platform as the Alarm Tracker display. PETER T. BULLEMER is Independence, Minn.-based senior partner of Human Centered Solutions. DAL VERNON C. REIS-

ING is Canton, Mich.-based senior partner of Human Centered Solutions. MISCHA TOLSMA had been divisional manager, instrumentation and control engineering, for Sasol, Secunda, South Africa, during the time of the trial; he now is senior operations management engineer for Shell Global Solutions, The Hague, Netherlands. JASON C. LABERGE had been leader at Honeywell’s Human Factors Center of Excellence, Golden Valley, Minn., when this trial took place; he now is manager of human factors for Alberta Health Services, Calgary, Alberta. E-mail them at pbullemer@ applyhcs.com, dreising@applyhcs.com, Mischa.tolsma@gmail.com and jasoncharleslaberge@yahoo.com.

PROCESS puzzler

Vanquish Vacuum Distillation Difficulties Readers recommend a variety of improvements

CHECK THE INTER-COOLER

UNDERSTAND THE IMPACTS

As a consulting engineer who has been designing ejectors and systems for over 45 years, I have several comments. First, if the operating temperature of the cooling water is higher than the summer design temperature, the condenser pressure will increase, resulting in poor vacuum and unstable operation. By design, the design water temperature is the maximum allowable and the steam pressure is based on the minimum available. Second, higher concentrations of sulfur in crude will increase solids’ carryover and cause erosion in the diffuser and on the external surface of the steam nozzle due to impingement. Perhaps a separator pot upstream of the first-stage ejector suction will help. Lastly, if the steam nozzle split, it would leak steam not air. This would put an additional load on the ejector, increasing the suction pressure. A few additional points are in order: Wear in the diffuser and nozzle can also be an effect of wet steam. This wear is usually on the inside of the nozzle, causing “wire drawing.” To operate efficiently, ejectors require 97% quality steam (minimum). The system may have a steam separator but the condensate, if not properly trapped, still will carry into the nozzle. No mention was made regarding the condition of the second-stage ejector. If its condition is reasonably good, then the corrosive gases are going out in the condenser. That being the case, what is the physical condition of the inter-condenser and tubes? Louis Decker, manager DecTecH Associates, Bridgewater, N.J.

A change in feedstock, such as a change to high sulfur Canadian crude, can impact a vacuum system in several ways. Ejector systems are sized to handle a specific load rate and composition. An increase in the overall f low or a change in a load’s component makeup can have consequences, including performance and corrosion problems. High cooling water temperature and low cooling water f low both impact a condenser’s operating pressure. During the winter months, cooling water temperatures are colder and this allows the condensers to operate at much better pressures than would be seen during hotter summertime operation. Problems with the startup and operation of multistage ejector systems are more common during hot weather because of the warmer water temperatures. An ejector depends on the downstream equipment (condensers, ejectors and piping) to maintain a certain pressure at its discharge. If an ejector’s downstream pressure deteriorates past its design point, unstable operation will likely occur. Hotter-than-design cooling water can cause poor condenser performance. This is why it is important that ejector systems be designed for the hottest cooling water temperature expected at the site. Condenser fouling will have a similar impact on vacuum as hotterthan-design cooling water. As the heat transfer rate decreases, the operating pressure of the condenser becomes worse and the first stage ejector is then subject to a poorer49

This Month’s

Puzzler

The two-stage steam ejector system for our vacuum distillation column causes us numerous problems. Startup is difficult because of poor vacuum control — especially during the summer when our cooling-tower water runs warmer than usual. When this occurs, we cut the tower vacuum but that only gives modest improvement. Moreover, ever since we began using higher ratios of high-sulfur Canadian crude, we’ve had corrosion and erosion issues. Recently, the motive steam nozzle split and leaked, causing us to pull air instead of tower vapor. We swapped the carbon steel ejectors for Type-316 stainless steel ones but still experience erosion in the ejector diverging nozzle, converging diffuser and even in the outlet diffuser. We’re also wondering whether we should capture more of the hydrocarbon vapors now lost to the thermal oxidizer. How can we improve this operation? What’s behind our corrosion problem? Should we be concerned about the economics of the thermal oxidizer?

chemicalprocessing.com

March 2014

PROCESS PUZZLER

MAY’S

PUZZLER Catastrophic pump failures at the tank farm (Figure 1) are plaguing the commissioning of our new plant. The tank farm has an ordinary centrifugal pump (CP) as well as magneticdrive CPs and a gear pump. The mag-drive pump started failing after the first few days. We got some warning from a pressure switch low (PSL) that flashed for a couple of minutes. PUMP PROBLEMS LT

Organic solvent, high vapor pressure

Viscous reactant

Water

PI PSL RO

PI PSL FV

Gear pump – packing Mag. drive CP

CP – double seals

Figure 1. All three types of pumps in the tank farm are experiencing problems.

We switched to a spare and it did the same thing after a day. The gear pump seemed to be operating fi ne, even after a few days — but a reading on an infrared gun indicated the casing was hot; the downstream fl ow meter showed a dropping fl ow rate. An operator loosened the packing on the pump while I was away at lunch and it now runs fi ne. The water pump is showing the same symptoms as the mag-drive pump but hasn’t failed yet during the fi rst week of commissioning. Are we out of the woods? Send us your comments, suggestions or solutions for this question by April 11, 2014. We’ll include as many of them as possible in the May 2014 issue and all on ChemicalProcessing.com. Send visuals — a sketch is fine. E-mail us at ProcessPuzzler@putman.net or mail to Process Puzzler, Chemical Processing, 1501 E. Woodfield Rd., Suite 400N, Schaumburg, IL 60173. Fax: (630) 467-1120. Please include your name, title, location and company affiliation in the response. And, of course, if you have a process problem you’d like to pose to our readers, send it along and we’ll be pleased to consider it for publication.

than-design discharge pressure. In these cases, the condenser bundles should be cleaned or replaced. Care needs to be taken when replacing condenser bundles as they are designed for vacuum service and have special construction features. Vacuum control for a distillation tower is most commonly obtained by recycling load from the discharge of the first-stage ejector back to its suction. This allows one to manipulate the load to control the process vacuum. There are other control schemes for ejector systems but they have drawbacks that make recycle control the ideal choice for this application. Throttling the motive steam to the ejectors is not an acceptable way of controlling the tower pressure and can cause the vacuum system to be unstable. Erosion damage is almost always attributed to wet motive steam. This type of damage is often seen inside an ejector’s motive nozzle and in the converging section of an ejector’s diff user. Wet

SEE ANOTHER RESPONSE ONLINE An additional reader response to this Puzzler appears at www.ChemicalProcessing.com/articles/2014/vanquish-vacuum-distillation-difficulties/

NLB Solutions steam greatly reduces the service life of ejectors and has a negative impact on ejector performance. Corrosion can also negatively impact an ejector. Certain crude slates, notably ones with higher sulfur levels, lead to the creation of acids. Inside a vacuum system, sulfur and other impurities mix with the motive steam, leading to the formation of corrosive compounds, like sulfuric acid. Corrosion rates are accelerated by temperature. The outside of an ejector’s motive nozzle, its diff user throat and its diverging diff user section are more prone to corrosion problems because they will be significantly hotter. Corrosion-controlling inhibitors can be considered as a means to combat corrosion. In other cases, the ejector bodies and condenser shells can be built in high-grade stainless steel or other alloys. The increased rate in the refining of more-sour crudes has led to a notable increase in the selection of duplex stainless steels. Eric Michael Johnson, service engineer Graham Corp., Batavia, N.Y.

Improved 3-D spray pattern cleans faster

ASSESS SEVERAL OPTIONS

Have you considered replacing the steam ejectors with vacuum pumps? However, the erosion issue you mentioned may be a problem for the vacuum pumps as well. An obvious question is have you considered reducing the “Canadian crude” content of the feedstock since you mentioned the problems started when more of the high sulfur feed was used? Upsizing your condensers or adding another in series may help you reduce your hydrocarbon vapors going to the thermal oxidizers. Michael Dobrowolsky, controls engineer SI Group, Schenectady, N.Y.

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PROCESS puzzler

TACKLE TWO ISSUES

There appear to be two distinct problems: cooling water in the summer and, more importantly, steam quality. If the tower cooling water is incapable of maintaining vacuum, you either need to increase the f low or the condenser temperature differential. Maybe you need chillers for the cooling water in the summer. One simple solution might be to adjust stage 2 so it receives fresh cold water instead of water from the first condenser. Also, you must look at the positions of the coolingwater control valves — if they’re wide open in the summer, seriously consider putting in larger valves or larger water lines; on cooling lines I usually plan for butterf ly valves because of their high Cv s. Steam quality is only part of the problem with the ejector corrosion. You may need to go with high nickel alloys for internal components subject to erosion. Ceramics are another choice; thermal shock normally isn’t a problem with modern ceramics, especially with water systems. (Ceramic coatings have been used to protect fired heaters: www.advancedmaterialtechnologies.com/pdf/

fmp/C2012-0001687%20(2).pdf.) Coatings such as silicon nitride (Si 3N4), silicon carbide (SiC), titanium nitride (TiN) and tantalum nitride (TaN) have been used to protect metals from erosion. A coating is just that, a coating — it may prevent erosion but if the metal behind it is penetrated, corrosion continues. Perhaps, it would be best to build critical components out of ceramic alone; silicon nitride should be the best choice for this type of application. Another issue is steam operation. You’ll want to check the steam trap and the pressure control valve. It may be that the trap is not functioning or has been poorly selected. Perhaps the pressure control valve is being bypassed. Check the condition of the steam line and its history. If the steam separator isn’t working well or has been scaled up in the past, it may be because the supply piping is poorly insulated or because condensate has built up in the piping. Look at how often the piping has been replaced. Wet steam will cause as much damage as condensing hydrocarbons, line rust or scale. Dirk Willard, senior process engineer Ambitech Engineering, Downers Grove, Ill.

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Do Your Homework Evaluate a variety of factors before embarking upon continuing education The willingness of employers to commit funds for continuing education for their personnel waxes and wanes with the management philosophy in vogue and the availability of funds. When times are good, it’s easier to convince the boss to spend money on courses, seminars and conferences; when times are bad, it’s harder. Continuing education takes more than money, of course. It requires you to invest time and make a commitment. This applies to everything from self-study to university courses. Continuing education must provide value for the time spent. An employer only will pay if it can expect some level of return. Corporate training programs range from non-existent to highly structured. If your company lacks a program, it’s completely up to you to decide what you need and how to get it. Even in structured programs, a lot of variation may be available. You always have the final responsibility for improving your skills. Your personal motivations for training and continuing education should guide your efforts. So, first and foremost, you must determine your objectives. These might vary from enhancing your knowledge of a certain technology to retaining a professional engineering (PE) license to earning an advanced engineering degree. Once you’ve set your objectives, continuing education plans then can fit a logical structure. For instance, if your goal is to do the minimum amount of work to keep a PE license in force, the answer is straightforward. Online training, to the limit permitted, usually is cheapest and quickest. Cost may range from free to very modest and no travel time and expense are incurred. If some face-to-face training is required, local technical meetings generally are the next step because both direct and indirect (travel) expenses are low. At the other extreme, getting a worthwhile advanced engineering degree generally demands that you go back to school. Many universities offer master’s degree programs for working professionals. These mix evening courses, short but intensive sessions, and some distance learning. Most professionals lie in the vast middle ground. They have a desire to learn and do their job better. At the same time, they realize the commitment required for an advanced degree doesn’t fit their objectives. So, here are some pointers for the typical professional looking to sharpen skills and keep them up-to-date. Carefully select online and distance learning. Such options continue to grow. Webinars lasting from 30 to 90 minutes can cover everything from a general introduction

to a subject to detailed exploration of a specialized area. Direct costs are relatively low and travel costs are zero. Webinars normally are sponsored by professional societies, magazines (see, for example, www.ChemicalProcessing.com/webinars/), commercial training companies and vendors. Quality varies but, with careful selection, you can put together an effective training program. Webinars may be either real-time or on demand (i.e., listening when you want to a recorded presentation). Attending a real-time online presentation usually is worth the effort. Not only will you get the opportunity to ask questions but also, in my experience, such presentations more strongly hold an attendee’s attention and thus provide more value for the time you invest. Focus on gaining short-term benefits. Moving up to intensive training sessions requires spending money, e.g., for seminar or conference fees and travel expenses. If you expect to get your employer to pay, remember that a successful event to an employer is one where you come back with something that makes money immediately. So, ask specific questions before signing up. Will the particular subjects covered help do your daily job? What sorts of people (e.g., process engineers, researchers or managers) does the event target and can you learn from them as well as the instructor? Do the subjects focus on the future of the industry or just look back at the past? Some people may decry this attitude as short-term thinking instead of long-term planning. There’s some validity to that criticism. Nevertheless, your plan must account for the realities your boss deals with. If you want your employer to give you the time and money to attend an event, you must focus on the short-term payoff. Afterwards, you must advertise the benefits it provided. That will make selling the next course, seminar or conference easier. Teach to learn. If no available offering covers what you’re interested in, why not teach it? Nothing makes you learn a subject more than having to organize your thoughts and experience so you can teach others. This is the hardest and most-time-consuming route to take — but it will teach you the most. Offer to do a 30-to-60-minute technical presentation at a local meeting of a professional society. Or put together an in-house presentation for a lunchtime session. Figuring out what’s important to teach other people will get you to learn more than any other method.

Attending a real-time online presentation usually is worth the effort.

andrew sloley, Contributing Editor ASloley@putman.net

chemicalprocessing.com

March 2014

Equipment & services

Software Mobilizes Analytics The FactoryTalk VantagePoint Mobile App offers a native Windows 8.1 experience where users can access centralized reporting and analytics from the Rockwell Software FactoryTalk software suite. Within the app, users can view key performance indicators (KPIs) such as energy usage, operational equipment effectiveness, or mean time between failure/to repair. By touching the KPI gauge or chart, users can dive deeper into the FactoryTalk VantagePoint portal for full, detailed reports and trends driving those metrics. Users can send KPI information to coworkers by swiping to bring up the Windows share charm. The selected KPI is then ready to send to anyone in their contacts list. Rockwell Automation 440-646-3806 www.rockwellautomation.com

Touchscreen Panels Improve Operator Visualization The PP882 and PP885 touchscreen operator interface panels for compact controls provide improved process visibility through larger screens, sharper displays, quicker access to multiple applications and an easy-to-use-and-navigate touchscreen interface. With 12.1-in. and 15.4-in. display sizes respectively, both are equipped with high-resolution widescreen TFT/LED backlit, touchscreen displays with 262,000 colors. Both panels offer interfaces for connecting USB peripherals,

March 2014

chemicalprocessing.com

including serial ports and two Ethernet ports. This means loading human-machine interface projects can be done safely and easily via standard cables or a USB cable. The panels are equipped with IP65/IP20 front/rear casings, enabling them to withstand operating temperatures from -10 up to 50°C. ABB 919-856-2360 www.abb.com

Transmitter Enables Remote Access The Liquiline CM44x multichannel transmitter now includes EtherNet/ IP connectivity for easy, seamless integration with the Rockwell Automation PlantPAx Process Automation System. The transmitter features an integrated web server that allows the operator to remotely view diagnostic data, perform configuration or access device parameters via any web browser. Data can be securely accessed and maintenance functions can be performed via the FieldCare asset management system. With Memosens digital sensors, manufacturers can use EtherNet/IP and one CM44 transmitter to access many parameters and accept inputs down to the sensor level including sensor condition and diagnostics. Endress+Hauser 317-535-1306 www.us.endress.com

Software Totalizes Multiple Gases The QuadraTherm Software Interface Program (SIP) now features a flow totalizer software module for the

QuadraTherm 640i/780i mass flow meter that helps totalize and monetize all gases. The module’s high accuracy (±0.5% of full scale) gives users accurate totalization of multiple gases from an industrial flow meter, says the company. Users can totalize up to four gases with one device and software package, set units per pulse and pulse width, reset totalizers or turn them on or off. The SIP user interface screen displays the four totalizers. The user selects one to be active. Each totalizer is independent of the others, allowing users to totalize one gas, then switch and totalize another. Sierra Instruments, Inc. 800-866-0200 www.sierrainstruments.com

Dumper Rotates 180° A lift and dump drum dumper unit accepts a drum of non-free flowing material and discharges the contents into a hopper at approximately 183 in. above floor level. Unit features a Lift & Seal system for dust-tight operation, a patented Control-Link Rotation system for 180° dump carriage rotation, and Type-304-stainless-steel product contact surfaces. Continuously welded tubular steel strengthens the frame and custom caging with load-side light curtain enhance operator safety. Unit includes a gravity roller conveyor base for easy drum loading and unloading, and comes available in discharge heights up to 40 ft. Material Transfer 800-836-7068 www.materialtransfer.com

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CSB Urges Tougher Safety Regulations Investigation of a deadly refinery blast reveals inefficient industry-wide safety standards

“Companies must do a better job of preventing refinery accidents,” says Moure-Eraso.

March 2014

The U.S. Chemical Safety Board (CSB), Washington, D.C., states in a published draft report that high-temperature-hydrogen-attack (HTHA) damage to a heat exchanger caused the April 2010 explosion and fire at the Tesoro refinery, Anacortes, Wash., that killed seven workers. The report also notes the company failed to apply inherently safer technology and install damage-resistant materials. “Seven lives were tragically lost at the Tesoro refinery in 2010,” says Dr. Rafael Moure-Eraso, CSB chairperson. “I believe the draft report does an outstanding job of tracing this complex accident to its roots: a deficient refinery safety culture, weak industry standards for safeguarding equipment, and a regulatory system that too often emphasizes activities rather than outcomes. The report is a clarion call for refinery safety reform.” Using sophisticated computer models, the investigation found the industry-wide method used to predict the risk of HTHA damage to be inaccurate, with equipment failures occurring under conditions deemed to be safe from HTHA. It cited deficiencies in the company’s safety culture that led to a “complacent” attitude toward flammable leaks and occasional fires. Investigators determined that during the unit startup, Tesoro did not correct the history of hazardous conditions or limit the number of people involved in the non-routine startup of the heat exchangers. Instead, because reoccurring leaks and the need to manually open a series of long-winded valves requiring more than 100 turns by hand to fully open, a supervisor requested five additional workers to help. All seven lost their lives as a result of the blast. Moure-Eraso adds, “The accident at Tesoro could have been prevented had the company applied inherent safety principles and used HTHA-resistant construction materials to prevent the heat exchanger cracking. This accident is very similar to the one that occurred at the Chevron refinery in Richmond, Calif., in August 2012, where corrosion of piping went undetected for decades until it ruptured, endangering the lives of 19 workers caught in a vapor cloud and sending 15,000 community members to the hospital. Companies must do a better job of preventing refinery accidents, which occur all too frequently.” The draft report notes that recommended practices of the American Petroleum Institute (API) are written “permissively” with no minimum requirements to prevent HTHA failures. For example, API Recommended Practice 941 — Steels for Hydrogen Service at Elevated Temperatures and Pressures… — uses the term

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“should” 27 times and “shall” only once. It also doesn’t require users to verify actual operating conditions in establishing operation limits of the equipment, or to confirm that the materials of construction will prevent the damage. An inspection strategy that relied on design operating conditions rather than verifying actual operating parameters contributed to the accident. The investigation found Tesoro, like others in the industry, used published data from the API called Nelson curves, to predict the susceptibility of the heat exchangers to HTHA damage. The CSB found these curves unreliable because they use historical data concerning HTHA that may not sufficiently reflect actual operating conditions. For example, a CSB computer reconstruction of the process conditions in the exchangers determined that the portion of the carbon steel exchanger that failed likely operated below the applicable Nelson curve — indicating it was “safe.” The CSB determined that inspections for such damage are unreliable because the microscopic cracks can be localized and difficult to identify. The report concludes, “Inherently safer design is a better approach to prevent HTHA.” It notes that API has identified high-chromium steels that are highly resistant; these were not installed by Tesoro. The CSB has called for the adoption of inherently safer technology, design and equipment in other reports, notably the one on the Chevron refinery fire. The draft report — subject to a future vote by the CSB — makes numerous safety recommendations to Washington’s legislature and governor, to its regulatory agency, Tesoro, and the API. These include recommending the state establish a more-rigorous regulatory model, possibly based on the safety case regime; revise the state’s process safety management regulations to ensure prevention of catastrophic releases; and perform a safety verification audit at all refineries in the state. The CSB also released a computer animation that recreates the explosion and fire at the refinery. The five-minute animation illustrates the process of HTHA and can be seen here: http://goo.gl/FzLISG. The draft report is available at www.csb.gov for public comment until March 16, 2014. Comments should be sent to tesorocomments@csb.gov. All comments received will be reviewed and published on the CSB website. Seán ottewell, Editor at Large sottewell@putman.net

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