| 摘要 |
1,086,251. Sublimation; freeze drying. F.M.C. CORPORATION. Jan. 12, 1967 [Jan. 15, 1964], No. 1295/65. Heading B1B. [Also in Division A2] Freeze drying of aqueous material, such as coffee extract or fruit juice, is carried out by pumping the liquid material from reservoir 46 through nozzle 38 into chamber 10 maintained at a pressure less than 270 microns by pump 32 so that vaporization of some of the water in the sprayed particles takes place and the particles themselves are frozen. About 20% of the water in the sprayed particles is vaporized in chamber 10. The frozen particles flow from chamber 10 into chamber 12 through which they are conveyed by vibrating pan 54 while being heated to dryness by electricallyheated, silicone-rubber blanket 70 which is maintained at approximately 300‹F. The dried product flows into receptacle 16. The watervapour in chambers 10 and 12 condenses in the form of ice on coils 22 and 62, respectively, which are maintained at -50‹F. by refrigeration unit 24. When receptacle 16 has been filled, valves 97 and 80 are closed and air-inlet valve 96 is opened, so that the filled receptacle may be replaced by an empty one. Valve 96 is then closed, valve 92 is opened, valves 97 and 80 are re-opened, and finally valve 92 is closed. Pan 54 is connected by pivoted links 56 to posts 57; and the span is vibrated at about 500 cycles per minute by means of a rotating shaft 110 which is connected to the pan via an eccentric and a pivoted connecting rod.
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