Cryogenic immersion freezing plant partic. for food prods. - recycles liq. carbon di:oxide by recompressing exhaust gas

摘要

Air lock valves are employed as prod. entry and exit for a pressure vessel in which the prod. is immersed in liq. CO2 under a head space of gaseous CO2 at a pressure above atmospheric. An elevator is used to lift the prod. from the liq. and deliver it to the exit. Excess gas from the head space is exhausted to a compressor which delivers it to a condenser reservoir from which liq. CO2 is returned to the pressure vessel. The air locks are pref. of the rotary or spaced shutter types. The exit pref. comprises two air lock valves in succession with an intermediate decompression space from which gas is pumped back to the headspace. Pressure inside the vessel is pref. about 6 bars and the compressor delivers at a pressure of about 12 bars. Used for rapid deep freezing of prods. esp. food prods. on an industrial scale. The installation can handle food prods. as complete items, reduced to small pieces or as particles. In partic. particles which previously tended to agglomerate are now frozen as clean, individual particles. The installation is inexpensive to buy and economic to operate because the CO2 is recycled.