GB599989A - Improvements in or relating to a dehydration process and a dehydrating apparatus - Google Patents

Abstract

599,989. Dehydrating food products and the like. STEVENS, A. H. (Dehydration, Inc.) Sept. 27, 1945, No. 25056. [Class 34 (ii)] [Also in Group VI] Material to be dried (e.g., sliced carrots) enters the drying apparatus 10 on a conveyer 13 and is preheated by exhaust gases in the exit chamber 16. The material is thereafter conveyed through the apparatus by endless belts 15, 30, 45, 60, 75, and 85. Hot air or gases travel concurrently with the material at each level, but in the reverse succession of levels so that the material entering with high moisture content is met by the hottest discharge gases and as the moisture is progressively removed the material passes through relatively cooler drier gas at each stage. By arranging for the material and gases to travel concurrently through each stage the lighter and more quickly dried particles are carried forward by the high velocity of the gases while the heavier particles continue on the conveyer. Nozzles 90, 96, on the last conveyer 85 direct a blast of drying gas through the conveyer to separate and mix the material before discharge through a door 98. Multiple blowers 26, 38, 52, 67, 82, 92, 96 direct the drying gas through the plenum chamber 10 which is heat insulated. Additional heat for drying is supplied by steam heating coils 23, 33, 48, 63, 78 above the conveyers and by electric heaters 24, 34, 49, 64 immediately beneath the conveyer belts. The drying gas is heated by steam coils 99, 100, 101. The fan intake ducts are situated above the conveyer in such a manner that the discharge end of each conveyer is in a quiet zone so that the material falls vertically from one conveyer to the next, the conveyers being staggered for this purpose. The creation of a quiet zone at the discharge end of each conveyer is assisted by bleeding part of the drying gas to the plenum chamber by the provision of apertures 41, 55, 70, 80.