Technology
Chem Show spotlights process equipment Computer systems for process control, pollution control technologies, and advances in handling corrosion head list of equipment offerings James H. Krieger C&EN Washington
The Exposition of Chemical Industries—known informally as the Chem Show—over the years has been a mirror reflecting the current state of the art in chemical process equipment. Now an annual event, the exposition, held early this month in its 38th edition at Chicago's McCormick Place, was no exception. Among the array of developments on view were new offerings in process control systems and in pollution control technology and new developments stemming from continuing concern with corrosion. The show marked the introduction of two new computer systems from Taylor Instrument Co., Rochester, in its series of MOD systems for process control. The new computer systems are part of the company's MOD 3100 series. The MOD 3103 is the smaller of the two computer systems, with a 64,000-word capacity and with primary memory expansions of up to 256,000 words. It's designed, the company says, to make computer control of small unit processes and remote or critical operations with only a few control loops economically possible. The larger of the two systems is the MOD 3106. With a 64,000-word capacity and primary memory expansions of up to 512,000 words, it is designed for complex or critical process management and control requirements. Optional peripherals such as programers, terminals, color graphic operator consoles, and high-speed disk memories are supported by the two computer systems in modular configurations. The MOD 3106 can be linked to communicate directly with other 3100 computers and thus su20
C&EN Dec. 22, 1980
pervise other systems in multiple computer system applications. Both the MOD 3103 and 3106 employ 16-bit semiconductor main memories. Error checking and correcting logic in the memories automatically corrects all single-bit memory errors. This feature, the company says, greatly increases system availability by virtually eliminating downtime caused by memory failure. Perhaps the main feature of the MOD 3100 systems is the software available. Taylor explains that the systems use an evolutionary extension of the company's POL (processoriented language) software. It is a real-time, high-level process control language with on-line editing capability. Operating procedures can be added or deleted without shutting down the system or interrupting control of the process. Included in the system is a comprehensive library of preprogramed application software called ICAP (industrial control application programs). The programs are implemented by defining operating and process parameters on fill-in forms and then entering these data into the system. The programs are organized on a task-by-task and loop-by-loop basis as an assortment of preprogramed modules. This feature, the company says, makes it possible for a user without professional programing experience to develop a totally custom system easily. For example, ICAP Continuous provides supervisory set-point control or direct digital control of continuous proportional - integral - differential loops. It automatically organizes the data base and provides programing for measurement, control, alarms, logging, and operator displays. Included is a variety of standard control algorithms, but the program also can implement user-written algorithms. ICAP Digital provides integrated control of motors, pumps, lights, relays, and other discrete devices. ICAP Sequential provides control of batch processes and complex startup, shutdown, and emergency procedures. And ICAP Graphics provides a system for creating custom process graphics. Most of the visitors to the Chem
Show also got their first look at the Network 90 distributed control system introduced a couple of months ago by Bailey Controls Co. of Wickliffe, Ohio. A modular system, it can be designed to provide control for as much as an entire plant or as little as one control loop. A number of elements are employed in building an integrated control system with the Network 90. The main component is the process control unit. It can stand alone or has the capability for intercommunication in larger plant systems. The basic process control unit can contain up to three module mounting units, each providing a common module bus for intermodule and system communication for up to 12 plug-in controller modules or logic master modules. The controller module can accept up to four analog and three digital inputs and provides up to two analog and four digital outputs for control. At a minimum, Bailey says, the controller module can be set up for two proportional - integral - differential control loops, with display on a digital control station and including five arithmetic, signal processing or status, or binary logic functions. The logic master module is used to implement large sequential control systems. Each can be set up for 250 function blocks including up to 128 input/output points. A configuration and tuning module provides for system configuration, tuning, and diagnostics. Using a front panel keyboard, an operator can monitor, tune, and reconfigure the control blocks of the other modules in the process control unit. The digital control station is a passive, conventional operator interface that connects by cable to a controller module. It provides displays, alarm indication, and manual/automatic capability for station control of the controller module and associated drive mechanisms. An operator interface unit consists of one or more cathode-ray-tube consoles, each with a functional keyboard. Printers, video copiers, and trend recorders are available as optional peripherals. Tieing it all together is a plant communication loop for intermodule communications. The loop is driven
Chem Show in Chicago: Exhibits display state of art in plant equipment
Dec. 22, 1980 C&EN
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low. According to CroU-Reynolds, the best conventional packed column removes only up to 70% of the inlet nitrogen oxides. CroU-Reynolds has found that it can overcome the absorption problem through use of a nickel-bearing stainless steel mesh. As the gas rises through the mesh, nitric oxide is re tained on the surface of the packing long enough for it to oxidize to nitro gen dioxide within the scrubber. The nitrogen dioxide then can be ab sorbed in water sprayed downward over the packing from distribution nozzles. Since no chemicals are added, the absorbed nitrogen dioxide can be recovered as dilute nitric acid. The result, according to the com pany, is that a minimum of 90%, and up to 99%, of all oxides of nitrogen are removed. A UOP spokesman notes that UOP's unit is operating at 93% efficiency, with the nitric acid being neutralized for disposal. The new system is relatively ex pensive—$7.00 to $10 per cfm, com pared to about $2.00 per cfm for a conventional base unit. However, CroU-Reynolds points out that return on investment is particularly good. No periodic additions of chemicals Owens-Coming Fiberglas' high-perfor are required. The catalyst has a long life and can be used over and over mance plastic tank with no effect on its surface by by loop interface modules housed in chemical reactions. And, if there is a the process control units and operator use or market for the nitric acid, interface units. The Network 90 payback is enhanced. communication system, Bailey ex A different pollution problem was plains, doesn't rely on a single "traffic the incentive for development of a director" to run the system. Rather, new control unit from Chemetron the job is distributed among the loop Process Equipment Inc., Louisville, interface modules. Bailey points out Ky., although the technology em that this approach eliminates a single ployed isn't itself new. The unit is a failure point that could take a system packaged, automatic Votator solvent off line. recovery system designed for. small Among developments in pollution operations of paint, varnish, adhesive, control technology is a new wet or rubber solvent manufacturers. scrubber system from CroU-Reynolds Besides recovering costly solvent, the Co., Westfield, N.J., designed spe unit reduces waste disposal vol cifically for operations emitting ox umes. ides of nitrogen. The company an The packaged system, called Sannounced the availability of the system Loc, is factory assembled, prepiped, at the Chem Show, following suc and prewired. It has a capacity of up cessful operation of a commercial unit to 400 gal per hour and can be in for nearly a year at a UOP plant stalled in a space 6 feet by 9 feet with making catalyst for automobile 15 feet of headroom. emission systems. In operation, faaste solvent is The scrubber, CroU-Reynolds says, pumped from storage into the unit, overcomes a major problem with where rotating blades continuously water absorption of nitrogen ox clean a thin film from the heated in ides—that is, removal of nitrogen terior wall. As the solvent vaporizes, dioxide is limited by the chemical it and the bottoms pass into a sepa reactions that occur. The problem rator that allows only clean, dry va arises because nitric oxide is relatively pors to pass into a condenser. The dry insoluble. The absorption of 3 moles vapors are condensed, cooled, and of nitrogen dioxide results in the re pumped into solvent storage, and the lease of close to 1 mole of nitric oxide, bottoms sludge is pumped to tempo but the nitric oxide passes out of the rary storage or drums for disposal. scrubber before it has a chance of The San-Loc unit has replaceable being absorbed. high-temperature plastic scraper As a result, overall efficiencies are blades. The internal volume of the 22
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unit is less than 4 gal, which, the company says, facilitates fast startup, shutdown, and changeover. Corrosion was the problem being eyed by Owens-Corning Fiberglas Corp. in designing the new high-per formance series of glass-fiber-rein forced plastic tanks it introduced at the Chem Show. The tanks are de signed for applications much more aggressive than are usual for glassfiber-reinforced tanks. The tanks are made with a new filament-wound laminate composi tion designed, the company says, to improve temperature and impact re sistance and increase hoop and axial strength. The resin used depends on the particular application, but the company specifies a premium-grade, corrosion-resistant thermoset resin suitable for the corrosive environ ment at the operating temperature. The tanks are designed with an al lowable strain of 0.001 inch per inch at 200° F with the tank full of liquid and at a superimposed pressure of 2 psig. Impact resistance is twice that of standard industry filament-wound tanks. Minimum wall thickness is 0.280 inch, with a corrosion-resistant liner thickness of 0.180 inch. In another corrosion-related de velopment, Cabot Corp. announced that it is making its computerized corrosion data bank available to in terested persons outside the compa ny. The data bank now contains about 100,000 tests of Hastelloy and Haynes alloys gathered by the com pany's high-technology materials di vision, Kokomo, Ind., over 10 years of lab and field work. The company ex pects to have another 50,000 data points in about another year. Searches can be made for nine variables, such as material, environ ment, corrosion rates, time periods, and the like. The information, Cabot says, can be provided in a day. D
Dry scrubber system uses electron beams A new system of stack gas cleanup is being developed jointly by Avco Ev erett Research Laboratory Inc., Ev erett, Mass., and Ebara Corp. of Japan. A cross-licensing agreement was signed recently by the two com pany presidents that provides for sharing of patents and know-how for the Ε-Beam dry scrubber system. Each company has been developing . the system independently since 1970, and the system is now ready for the final drive to commercialization. If successful, it could reduce the cost of stack gas cleanup considerably. The Ε-beam system uses electron
