Patent GB-940627-A (GB)
Title: Method and device for deep freezing of foods (except fish) or medicines
IPC: A23L3/36
Filed: 1961-06-05
Abstract: 940,627. Preserving food &c. H. BECKMANN. June 5, 1961 [June 8, 1960], No. 20214/61. Heading A2D. [Also in Divisions B8 and F4]. Animal and vegetable substances are degasified and deaerated under a pressure of not more than 10 mm. mercury, the resulting evaporation of water pre-cooling them to about freezing point, and then they are deep-frozen by flooding them with vaporisable refrigerant, the evolved vapours being compressed, condensed and returned without throttling at least in part to the substances. The invention is applied to the treatment of fish, meat, eggs, dairy produce, fruit, vegetables, fruit juices, medicines and blood preparations. The pre-cooling may be sufficient to form an ice-glaze on the substance, the ice resulting from water existing in or added to the substance. The degasification and pre-cooling may be effected in the same container as that in which the substances are frozen or in a separate container. The freezing container may also act as a storage container for the frozen substances. As shown in Fig 1, the substance is loaded into a container 1 which is then sealed. A valve 9 is then opened, so that a steam ejector 11 can evacuate the container to effect the degasification and pre-cooling, the compressed vapours passing to a condenser 17 whence the gases and water are vented. Valve 4 is now opened so that a brine (alcohol and water, or magnesium or calcium chloride solution) can run from receiver 3 into the container 1 to flood the substance, the brine evaporating in part to deep freeze the substances and the condensate being returned from condenser 17 to the receiver through valve 20. The receiver is cooled by cold vapour from the container flowing through coil 22. The brine in the container is recirculated by an air-lift pump 23, 27. When freezing is complete, valves 4, 9 are closed and a pump 8 discharges the brine from container 1 to the receiver. Some water from the condenser may be supplied direct to the container 1 to maintain the concentration therein under automatic control. As shown in Fig. 2, container 29 is evacuated through pipes 47, 35 by ejector 38 and then the valve is closed. A valve 64 is opened to allow liquid refrigerant (nitrogen or a saturated halogenated aliphatic hydrocarbon) to flow from receiver 31 to flood the goods in the container. Valve 64 is again closed and valves 48, 71 are opened so that refrigerant vapour from a steam-heated boiler 56 can enter ejector 50 to exhaust vapour from the container through pipes 47, 49. When all refrigerant has been evaporated, valve 64 is again opened to introduce a fresh charge of liquid and the cycle is repeated until the goods are deep frozen. Refrigerant from the ejector is condensed in condenser 33 and then flows to the receiver 31. The boiler 56 is supplied with refrigerant from the receiver by pump 63. After freezing, the refrigerant ejector is stopped and a motordriven compressor 68 exhausts residual refrigerant from the container to the condenser. To maintain the container cold after freezing if it be used as a storage container, it may have a refrigerated jacket or it may be supplied with gaseous or liquid refrigerant. In Fig. 5, (not shown), it is filled with nitrogen which is then exhausted by a motor-driven compressor into a cooler and a storage vessel. When the container pressure reaches a minimum, a valve is opened to supply the gas from the storage vessel through an expansion device into the container, the valve being shut again. This cycle is repeated during storage. As shown in Fig. 6, the substance in container 85 is evacuated through connection 91 and is then charged with liquid refrigerant through valved inlet 107. This evaporates and the vapour is withdrawn by motor-driven compressor 94 supplying a condenser 108 and a receiver 111. When all the refrigerant has evaporated, the receiver is emptied into the container through valve 116 and the cycle is repeated until freezing is completed. For storage refrigerant is fed into the container from the receiver through expansion valve 114. valve 113 being continuously open. If the substance is to be frozen packed, it is placed in the dished parts 73 of a plastics or foil tray 74 (Fig. 3) which is then placed in a container 75 with a lid 80 loosely on top of the tray, the container being sealed by a closure 76. The container is evacuated through pipe 84 to degasify and pre-cool the substance and then a sealing head 82 is lowered on to the lid 80 to seal the lid on to the tray either by welding or cement both around the periphery and around each dished part. The sealed tray is then transferred to a freezing container. Specification 879,559 is referred to.