SCIENCE/TECHNOLOGY
Environment, Materials Among Influences Seen at Chem Show Process equipment design reflects growing influence of environmental concerns, development of improved materials of construction James Krieger, C&EN Washington
If e n v i r o n m e n t a l considerations don't currently top the list of factors affecting chemical process equipment design, they are very near the top, judging from the just-ended '91 Chem Show at the Jacob K. Javits Convention Center in New York City. But as illustrated by the show— formally, the 44th Chemical Process Industries Exposition—there are other factors influencing equipment as well, one of them the employment of new construction materials that significantly affect design. E n v i r o n m e n t a l considerations were evident in the themes for a large number of the 20 two-hour conference program seminars presented by the Chem Show—themes ranging from the benefits of periodic wastewater audits to postuser plastics recycling. They were also evident in many of the displays on the exhibition floor. One product area feeling the hot breath of environmental regulations is that of heat-transfer fluids. There are new products drawing customer interest—a synthetic hydrocarbon heat transfer fluid introduced in the U.S. at the Chem Show by Monsanto, for example, and a computerized selection guide for silicone heat-transfer fluids from Dow Corning. But manufacturers are finding growing concerns on the part of customers in potential regulatory problems. Indeed, the concerns were enough
to prompt Dow Chemical to give a press briefing on the regulatory situation regarding heat-transfer fluids. John B. Cuthbert, Dow project leader in specialty chemicals technical service and development, pointed out that at the federal level there are four laws that may have some impact on heat-transfer fluids: the Resource Conservation & Recovery Act (RCRA); SARA Title III, Community Right-to-Know; the Clean Air Act; and the Comprehensive Environmental Response, Compensation & Liability Act. RCRA presents a typical example of how the regulations might affect heat-transfer fluids. RCRA regulates handling, storage, transportation, and final disposition of hazardous wastes. When a waste is generated, it must be classified according to various criteria. Benzene, for example, is on the list for toxicity with an exposure limit of 0.5 mg per L. Benzene is a typical degradation
product of many synthetic organic heat-transfer fluids, Cuthbert explained. Similarly, SARA Title III requires users of listed compounds to annually report releases of those chemicals to any environmental media. The regulation requires companies in certain industrial classification codes and with 10 or more full-time employees to report emissions if they use 10,0001b of a listed substance annually or manufacture, import, process, or repackage 25,000 lb annually. Cuthbert noted that biphenyl, for example, is one of the listed compounds, and that biphenyl is a major constituent of eutectic diphenyl oxide-biphenyl heat-transfer fluids. Losses of biphenyl typically are the result of emissions from valves, pumps, vents, and flanges, Cuthbert explained. To help customers avoid problems connected with such matters, heattransfer fluid manufacturers provide
Visitors wait for Chem Show to open at Javits Convention Center December 23, 1991 C&EN
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Science/Technology
Chem Show, long held in New York City, draws unique exhibitor The Chemical Process Industries Exposition, as the Chem Show is formally called, provides a biennial window on some of the new developments and ideas in equipment and plants for those industries. It brings together a large gathering of companies—some 700 this year—that provide products and services with a similarly large group of users—what were expected to be more than 16,000. It has been doing this primarily in New York City, at different sites, since 1915. Since 1987, the show has been held at the city's new Jacob K. Javits Convention Center. The Chem Show is managed by International Exposition Co. For most of its history, the show was just that, an exhibition. But in 1989, a series of seminars were added to the week's activities. This year there were 20 free seminars, ranging from "The Benefits of Periodic Wastewater Audits" to "Gaskets: the Achilles Heel of Process Equipment." Among the exhibits of process equipment this year was one of the more unusual booths to show up at a Chem Show, and it had little to do with equipment per se. Germany's Treuhandanstalt, the trusteeship organization charged by the German government
a number of services. Monsanto and Dow, for example, offer routine sampling and analysis services for the fluids. Dow particularly touts a buyback service it has, where it will buy-back certain of its fluids as raw material feedstock once the end of their useful lives as heat-transfer fluids has been reached. Use of Monsanto's new-to-the-U.S. Therminol D-12 heat-transfer fluid also has environmental implications. In use for several years now in Europe, it is designed for a temperature range of -120 to 500 ° F and is intended as a replacement for such traditional coolants as trichloroethane and Fréons used, for example, in pharmaceutical processes. It is also a replacement for brine-steam systems, providing one system for heating and cooling, so that costly and timeconsuming switching isn't necessary. Because of their different chemis18
December 23, 1991 C&EN
"freuhand anstalt
with privatizing the state assets of former East Germany, was on hand and was promoting the opportunity to acquire companies in eastern Germany. Since June 1990, the goal of the Treuhandanstalt has been threefold: to privatize wherever possible, principally through sales; to restructure companies with a view to later privatization; and to close companies that have no chance of surviving in a market economy. Investors from all over the world can ac-
tries, silicone heat-transfer fluids don't present the potential regulatory problems that face the synthetic organics. Environmental concerns over heat-transfer fluids in general were not expected to peak for another five years or so, according to John E. Wharton, senior market supervisor of the coatings program at Dow Corning. But they are now imminent, he says—and are much on the minds of visitors to Dow Coming's booth. In other areas, a development tied in directly with environmental matters is a new low-profile air stripper from ORS Environmental Equipment, a division of Groundwater Technology Inc. The company makes systems to remediate contaminated air, soil, and groundwater. The company explains that all airstripping systems are based on the volatilization of many hydrocarbon
quire from the agency companies of all sizes and from all sectors of industry. The Treuhandanstalt has a computer-based information system offering prospective investors data on all the companies belonging to the agency. Visitors to the Chem Show had a chance to browse on computer terminals in the booth. A spokesman for the agency says its representatives were quite pleased with the number of contacts made through the exhibit.
contaminants such as benzene, toluene, and xylene when exposed to an air stream. In conventional strippers, contaminated water cascades down through a tower filled with a packing that exposes large surface areas of the water to an uprushing air stream. The Lo-Pro air stripper, by contrast, consists of a sump, a vacuum blower, and a variable number of stackable aeration filter plates. The result is a multistage, counter-flow aeration system in which a thin stream of contaminated water zigzags downward, with air drawn in at the bottom of the system bubbling up from holes in the filter plates. Joseph McKeever, ORS director of sales and marketing, says the Lo-Pro air stripper can typically return a payback in less than a year based on savings associated with off-gas treatment alone. The company explains that as much as 10 times the air flow
may be required with conventional stripper design as would be needed for a counter-flow design. Up to 80% of the capital cost of a water treatment system may be attributed to equipment for thermal or thermalcatalytic treatment of off-gases. Hence, the air volume to be handled is a significant contributor to the system's cost. Environmental concerns are just one of the motivating factors behind development of the Large PrepsLab concept of Engineered Technologies Corp., an equipment and systems subsidiary of the engineering and construction management firm Herzog-Hart Corp. Touted as a bridge between chemistry and engineering, the Large PrepsLab is a selfcontained, modular, multipurpose scaleup laboratory that satisfies all hazardous code conditions in a chemical or biochemical environ-
ment. It is most suitable to multistep organic synthesis work at a level of 1 to 30 gal, although as Engineered Technologies points out, it is applicable to almost any use requiring scaleup processing in a clean, safe, and environmentally sound enclosure. A Large PrepsLab system consists of the enclosure, the process arrangement, auxiliary process modules, and the control system module. Specific design features would depend on the particular operations to be performed—for example, condensation, esterification, nitration, polymerization, or others, combined with, say, crystallization, filtration, extraction, or distillation. Typically, a Large PrepsLab enclosure assembly has three individually ventilated modules with three sliding safety-glass doors on each side (generally, only one can be opened
at a time). It measures overall 131/? feet long, 5 feet wide, and 93A feet high and requires 68sqft of floor space. Most enclosures are built with a hinged access door at one end for moving portable equipment in or out of the end bay. Everything required for processing or safety is contained within the enclosure. Thomas T. Houston, president of Engineered Technologies, says concepts for application of the Large Prepslab are still being broadened and developed. For example, besides being a bridge between lab and large pilot plant, the Large PrepsLab can function as a small manufacturing unit—producing a chemical component on the plant floor as needed and at just the time it is needed, without the manufacturer having to be concerned about environmental hazards. Houston describes one application concept, still only on paper, that would involve multiple PrepsLab units in a warehouselike pilot plant facility. Utilities would all be in one bay running along the length of the building on one side. A central bay would house "plug-in" pilot plant m o d u l e s — t h e PrepsLab units— when they are in operation. On the far side of the building from the utilities bay, the plug-in units would be retracted for reconditioning in a cleanup bay to ready them for new uses. The "warehouse" itself and the offices contained there would thus remain hazard-free regardless of the particular pilot plant operations being carried out. And the PrepsLab units would provide a great deal of flexibility in the types of uses to which they could be put. Three equipment developments introduced at or in connection with the Chem Show rely on new materials for their performance. One is a hollow-fiber membrane module for noncryogenic nitrogen production from Generon Systems, another a gear pump from Iwaki Walchem Corp., and the third a concept in steam traps from Ogontz Corp. Membrane separation is still an e n g i n e e r i n g - d r i v e n technology, notes Michael A. Porter, president and chief executive officer of Generon Systems, a joint venture of Dow C h e m i c a l a n d t h e U . K / s BOC Group. Generon's new module is December 23, 1991 C&EN
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Science/Technology tomatic variable orifice (AVO), which can withstand temperatures to 500 °F. AVO incorporates a chemically resistant, flexible elastomeric membrane, specially compounded for steam service, that pinches off the trap's orifice or opens it up. The action is controlled by a temperaturesensitive fluid that surrounds the membrane and expands or contracts. The elastomer and the hydrocarbon wax fluid were the focus of an intensive development effort to find the right combinations of properties. In operation, AVO is wide open at cool temperatures of startup, allowing dirt, air, and noncondensables to vent. As temperature increases, the fluid expands to close off the orifice. More condensate then builds up beModular construction is characteristic of PrepsLab units hind AVO, which opens to drain it the HP 6000, a smaller and lighter other gear pumps, he says, are made as the condensate cools and the fluid contracts. During draining, as version of the original HP 4200. with ceramic gears. Weighing in at 50 lb and providing Because of the cost involved, the hotter and hotter condensate conequivalent performance, the HP pumps are a "niche product/' ac- tacts the fluid, AVO begins to close, 6000 represents a compaction of the cording to Duffy. What adds to the maintaining a leg of condensate that technology from that of the 150-lb expense is that silicon carbide is dif- prevents live steam loss. The trap reHP 4200. ficult to work with and must be peats the cycle until a point of equiKey to the weight savings is a pro- ground, not machined. But the re- librium is reached. prietary new fiber material devel- sult is a pump that handles slurries One of the key reliability features oped at Dow, which does Generon's or fluids with particles, substances of the new steam trap, says Thomas fiber-development work. According that normally tear up pumps. Ac- M. Kenny, chief executive officer of to Porter, Dow scientists screened cording to the company, the high Ogontz, is that the specially commore than 2000 polymers and poly- hardness and very low fluid slip co- pounded elastomer will squeeze mer variations to get the right one efficient of the close-tolerance ce- around any small particles of dirt in for the membrane. The result is a ramic gears combines with chemical the trap and still seal without leakmembrane that does the same job in resistance to provide pumps capable age. If larger particles enter the trap a module that requires half the fiber. of constant rate, nonpulsating flow and get caught, the blockage reducThis enabled Generon to engineer for other abrasive or corrosive liq- es flow, lowering the temperature uids. the smaller, lighter module. and causing the trap to open more The new module should fit well Materials developments have also fully until the dirt passes through. into the market for nitrogen from been behind a new concept in steam Ogontz hasn't set a price yet for membrane separation. It is particu- traps, the pinch steam trap from the new steam traps, but says it will larly suitable for controlled atmo- Ogontz Corp. Though it wasn't actu- be under $100 (conventional traps sphere transportation of perishable ally exhibiting at the Chem Show, can cost several hundred dollars). commodities, offshore marine appli- Ogontz introduced the trap at a The company will begin to phase cations, and nitrogen production in press briefing timed to coincide out its production of conventional environments where nitrogen sourc- with the show. The pinch steam trap traps. es previously haven't been available. will be on the market in January. The technology employed in the The overall market is growing, and, Steam traps, designed to allow steam trap design has wider implicaPorter says, more than half of in- condensate to drain from steam tions. The company chose steam stalled membrane separation capacity lines, are generally mechanical as- traps as a point of entry into the maris in brand new applications. semblages with seats, plugs, springs, ket with the technology. But it anticGetting its first showing in the bellows, levers, pivot points, or bi- ipates development of a full family of U.S. was Iwaki Walchem's new G metallic elements. In contrast, the self-operating t e m p e r a t u r e - c o n Series chemical gear pumps. The new pinch steam trap is a single, trolled valves and traps. Says Kenny: key material here: precision ground one-piece machined stainless steel "The [pinch steam trap] begins a revsilicon carbide and zirconia ceramic body 23A inches long and 1 ljs inch in olution in steam trap and valve degears and bearings. Iwaki Walchem diameter. Weighing 8.2 oz and with- sign which is as significant as the minational sales manager John J. Duffy standing 300 psig, the steel housing crochip replacing the transistor in D calls the pump revolutionary. No encloses what Ogontz called the au- the electronics industry." 20
December 23, 1991 C&EN
