PRODUCTION
Right bank of cylinders contains a tandem, two-stage nitrogen compressor and a single-stage methane cylinder. Left bank has first- and second-stage air cylinders
Compression Giant Single power unit compresses three individual streams simultaneously to different pressure levels QPENCER
Chemical's
recently
com-
^ pleted Vicksburg Works has a unique system for compression of proc ess gases in production of anhydrous ammonia. A single power unit simul taneously compresses three individual streams t o different pressure levels. Air, nitrogen, a n d m e t h a n e are all used in separate phases of new partial oxi dation process (C&EN, F e b . 15, p a g e 5 7 2 ) . F l o w s a n d pressures are in dividually controlled. Power is supplied by a 2000-hp., G M W 8 , U - t y p e natural gas engine m a n u f a c t u r e d a n d sold by Cooper BesProcess gas compressors at Spencer's am monia plant handle three streams simul taneously—air, nitrogen, and methane
VOLUME
semer. Eight two-cycle power cylin ders ( 1 8 X 2 0 inch bore) drive t h e shaft at a rated 250 r.p.m. Horizontal compression cylinders are located a t right angles on either side of engine, thus forming a compact reciprocating unit. This arrangement saves space, piping, and installation costs, requires less operational a n d maintenance labor. From flywheel end, right side of trie unit contains a tandem, two-stage nitro gen compressor. Dry, pure nitrogen at a rate of 2 1 0 0 standard c u b i c feet per minute is compressed from 25 t o 3 1 0 pounds p e r square inch gage. O n same side, a single-stage m e t h a n e cylin der raises pressure level from 100 t o 4 0 0 pounds p e r square inch gage, d e livering 2190 standard cubic feet p e r minute. Left side of unit h a s firsta n d second-stage air cylinders with separate drives. At a full flow capacity of 8600 standard cubic feet p e r min u t e , air is compressed from 125 to 6O0 pounds per square inch gage. Each stream is separately controlled t o either constant flow or pressure b y remote, automatic, air-loaded instruments a n d is i n t e r d e p e n d e n t on other streams only as required for proper operation of con stant speed engine. Control. Automatic controls regu late constant speed engine—a AVoodware P G hydraulic governor xvith a remote control, manual reset. Constant air flow is maintained b y variable suc
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tion pressure t o first stage, obtained from s p e e d changes o n centrifugal compressor furnishing air t o recipro cating compressor. Nitrogen a t con stant discharge pressure is controlled by varying suction pressure with a n automatic by-pass, or recycling from discharge t o suction. By adjusting s u c tion pressure supplied from a pipe line, m e t h a n e is controlled to a constant dis charge pressure. F o r additional con trol, m e t h a n e cylinders are also e q u i p p e d with four double-deck, valve type clearance pockets a n d a n auto matic discharge overpressure vent. Failure of one stream does not neces sarily affect operation of others w i t h this arrangement, since cylinders h a n dling failing gas can be unloaded a n d unit left on stream. If unit itself m u s t be taken out of service, all t h r e e streams will b e interrupted. I n Spen cer's process, simultaneous interrup tion of t h r e e streams is not as serious as it could b e in other processes. I t is still a disadvantage, however. T o off set this possibility, another unit is u s e d in parallel, so t h a t only a 5 0 % r e d u c tion occurs with a n engine failure. A d vantages of this type of installation outweigh disadvantages; all concerned with this operation consider the choice an excellent one for the job.
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I N CHEMICAL A N D THERMAL STABILITY
• ANTI-SEIZING PROPERTIES • TEMPERATURE RANC Ε— F R O M - 1 0 0 ° TO 1 1 0 0 ° F.
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