Document nNNdeZrQobQD7g279JMn7Kd6m

Thermo-compression evaporation by A. Marriott Walker, Chiet Engineer, C. E Rogers Co, Detroit, Michi Thermo-compression as applied to evaporators, particularly in the dairyindustry, is an arrangement wherein a portion of the vapors discharged from an evaporator effect, is captured and compressed to a higher pressure and temperature for reuse on the hot side of the heating surface. This is accomplished by the use of a thermo-coinpressor, using the en ergy of the boiler steam supplied to the evaporator, to entrain and com press the low-pressure spent steam, for re-use in the same body or effect. A thermo-compressor is similar to and operates on the same principle as the steam jet ejector: pressure levels are dictated by the design of the particular evaporator. This principle is not new, having l>ecn discussed extensively in the tech nical literature of the last century. Application proved to lie more diffi cult than theory, however, and until recendy thermo-compression evapo rators had not been generally successful. Part of the difficulty lay in the primitive equipment used, which left much to l>e desired. Over the years. Ixith evaporators and ejectors have been improved with advancing the ory and increasing experience, so that the equipment came to be trulyengineered and its performance pre dictable. It then became possible and practical for engineers of the two Helds to get together and discuss the problems and potential of both evap orator and thermo-compressor, so that they could be tailored into a practical working unit. In the design of evaporators, it is advantageous to have a broad tem perature spread across the heating surface, in order to gel itinxiiiitim heat transfer with tin- least imestment in surface. It also lias been found that heat transfer decreases substantially as tile solids in the prod uct being eva|>orated increase. Hence it is desirable In conduct die evapora tion in more than one lush. to gain In ner heal transfer ulien die prod is lean and to separate diis operat Irom die portions of the evaport operating with increased solids. In the design of tltermo-couipi sol's, the maximum amount of su ss ill lie compressed when dieincrc in pressure and temperature Is 1< / t/that t/ain ini/al/ottmi / ihnna--x'innfai ssian, <11 rra/wrato .It rrtrht way hi him thr lari' hlh!t ihiiwi-t 'an/arisor in rrrtiral fnrsiti .It aftfor hj't a thr l\ihutt III "-'tail r/rrtn urntro thr I unflrrisrr. /nslnllatians mi,It ax this urr srtvirry mill. :afoalots all urn thr oruntr