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Hefrigera tiori in (2heriiical Indiistries A Survey of Applications D. 13. KILLEEBEI?,50 East 4lst Stieet, New York, N. Y. E C E S T rapid development in refrigeration engineering provides the chemieal engineer with a new kit of tools to attack and solve his problems of precise control of reaction rates and the exact separation of mixed material. The need for such control is being emphasized by the rcsnlts of researches in physical chemistry which during the past decade have placed extraordinary emphasis on the practical value in the industry of phase rule studies and of reaction velocity investigations. Our purpose here is to outline some of the applications oE modern refrigeration technic in chemical process industries. In the chemical process industries the application of refrigeration falls naturally into six major divisions of considerable commercial importance: LIque1aotion oi gaav. Solidification oi liquida. C~mtdlh~tion of ~ d t s from eolutiom. 4. tlemlution 01 miiturea into them oonstituents 5. Resulation of renation velooities. 8 . Mincellhoeoue 1°F-temperature operatione. 1.
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By far thc largest, applicatiun of refrigeration today isiii tlie food industries where perishahle foodstuffs must be maintained a t low temperatures to preserve them Erom tlie point and time of production to the consumer. This large field forms no particular part of tlie chemical p r o m s industries and lielice i i omitted from consideration here. On the other hand, a
iruinber of Eood-processing steps require rcErigerat.ion, and these are included in this discussion. OF GABBS LIQUBFALTION 1,rauio AIR. The manufacture of liquid air practiced OII a large scale in the commercial preparation of pure oxygen requires temperatures lower than -188" F. (-122" C . ) and evenaslow as -328°F. (-200" C.). The prodirctiorrof such low temperatures requires that, during purification and liquefaction, the air be compressed to 200 atmospheres or more. h s the process is operated, the compressed air is partly cooled by refrigeration externally produced in customary equipment, but the greater part of the necessary refrigeration is produced from the expansion of the compressed air itself. The compressors usod are built in three to fivc atages with refrigerated intercoolers arranged to remove water as condensed. The final liqirefaction of the air takes place by expanding it froin 200 atmospheres (3000 pounds gage) to a little more than 50 atmospheres (750 pouiids gage) using tire expanded cold air to precool the compressed air or, its way to the expmsion valve. A double-pipe heat exchanger is used for this purpose. Few are aware of the large quantity of pure oxygen produced by this process. According to the United States Census Bureau, 156 plants produced 2,086,301.000 c n l k feet by this
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guqxw, purtimlerly iii the \ ose rayoil trrxtilc, (:aiidy, and otiior iudustrics, Inrgi: air-conditioning wits are operated. I'rubal,iy the mwt imprt:uit iudust.ria appliwtim d In drying viscose rayon, particularly, a relative humidity uf glinse rule stirdics was i i i the i pnimt, US the Anlerican about 10 per cent is required, which is too low t o be easily tu aqiartite tlic constitti- producible esccpt by the use of refrigeration for dryiug the air iuture uceiirring in a nrtturtd before it is used. Large installations of air-conditioning r able t o crystallizt: out, dwirerl constitiiIirine. lii d ~ t,o he equipment, all employing more or less refrigeration, are also ents with a ininiinurri of evajior:itiuri, rarefit1 control nml required in dlie procrssing of gelatin, tile weaving of rayon regulation of crystallizer temperntiircs are cssetitinl. In this fabrics, and iii uunicrous other industrial olierations. iodustry, iis in maiiy others ling witlr salt mixtures i n SA~.IJI%AI, GABUIJNE MnmmAcwaE. Satural gas, as it soliitioii, luii-tenipcrabure cr5 llizatiim Srcquciitly a m i d s comes fruiri tlie well, coiltailis a eunsidcrable proportion of cspmsivc e\-ajioratiori of x n Tlii. halalile prdiicts iii hydrocarbons wliich are condensable and whicli are useful in t h i s case are boras and put,assioiii cldiiridc ivliich must lie the motor fuel iridost.ry. During 1927 more than 26,000,000 separated in a pure state from the brine containing a great, barrels of riatnml gasoline were separated from natural variety of other compounds. gas. T h e e iiietliods are used in this industry, singly or ill In tlii? German potash itidustry, refrigeration is used for mnl~inationn. The b s t is compression
