GB425056A - Improvements in or relating to the treatment of fish offal - Google Patents

Abstract

<PICT:0425056/III/1> <PICT:0425056/III/2> A process for the dehydration of fish offal, employing the principle of multiple effect evaporation, consists in expressing some of the liquid content of the offal, concentrating the expressed liquid in a tubular evaporator and drying the remainder of the offal in a drier heated by the steam from the evaporator, and operating at a lower internal pressure than that in the vapour space of the evaporator with or without returning the concentrate produced in the evaporator. Two forms are shown. In Fig. 1, a batch method is shown. Fish offal is charged into a steam jacketed sterilizer 1 and is passed on to an expeller 2, which may be of the worm type combined with steel bars, so that solid is retained and water passes through. From the expeller 2 de-watered offal passes to one or other of feed hoppers 3, 4 which deliver to one or other of steam jacketed driers 5, 6. The driers are employed alternatively and heated by steam produced in an evaporator 7 from the water expelled in 2 by way of a feed tank 8. The pressure in the driers 5, 6 is lower than that of the evaporator, the interior of the driers being connected to a vacuum pump 9. Valves 10, 11 control the vacuum and other valves 12, 13 control the vapour from evaporator 7 to the steam jackets of the driers. With reference to Fig. 2, a sterilizer 16 and expeller 17 are used as before, but the de-watered offal is delivered directly to a steam heated drying tube 18 and then to similar tubes 20, 22. A screw conveyer passes the offal therealong and agitates it in the presence of heat in the steam jackets. The steam is supplied as before from an evaporator 23 operating upon filtrate from the expeller 17 via a tank 24. The pressure in the tubes 18--22 is rendered lower than that in the evaporator 23 by means of a pump 25 with independently controlled valves 26, 27, 28. The tube 22 delivers offal alternately to vacuum receivers 29, 30 fitted with air-tight doors 33, 34.