GB930445A - Improvements in concentration of liquids by freezing - Google Patents

Abstract

930,445. Concentrating food liquids. UNION CARBIDE CORPORATION. April 7, 1961, No. 12609/61. Class 49. [Also in Group XIII] In continuously concentrating a solution or a liquid suspension of a heat-sensitive material, e.g. orange juice, beer, milk, by freezing, the material, before, during and after concentration, is in a controlled, oxygen-free atmosphere, e.g. an inert or reducing gas atmosphere. A singlestrength solution such as natural orange juice is introduced through a conduit 10 to a refrigerated storage tank 20. Through a conduit 21 nitrogen is introduced to blanket the head space in the tank 20, and is vented off through a conduit 22. Cooled juice is pumped by a pump 23 to a refrigerated cold-walled tank 25 and subjected to a temperature of minus 20‹ F. Scrapers 26 engage the inner surface up the tank 25 and driven at between 10 and 50 r.p.m. by a motor and speed reducer unit 27. Conduits 28 and 29 introduce and discharge nitrogen into and from the top of the tank 25. A slurry consisting of concentrated orange juice and 50% by weight ice crystals is taken from the bottom of the tank 25 by a pump 30 and passed to a continuous centrifuge 32 to remove the ice crystals. The juice passes to a storage tank 35 via a conduit 34, and the separated ice crystals are carried by a screw conveyer 33 to another continuous centrifuge 53, where remaining juice is removed. Nitrogen is passed by the conduit 29 to head space of the storage tank 35 and then to the centrifuge 32 from which it passes to a manifold conduit 38. The process is repeated two more times, using refrigerated cold-walled tanks 40 and 45 and continuous centrifuges 42 and 46, and the final concentrated juice is pumped to a cold walled storage tank 48, also blanketed by nitrogen. The final juice is pumped to a coldwalled blending tank 50, and juice from the tank 20 is fed as desired by a pump 51 to control the concentration of the juice product. Juice may be subjected to a stripping operation to remove any oxygen containing gas before concentration, e.g. with Fig. 2 the juice is supplied through a conduit 60 to a stripping column 62, a non-oxidizing gas, preferably nitrogen, is fed into the bottom of the column 62 through a conduit 64 and in moving upwards displaces any oxygen-containing gas, and the substantially oxygen-free juice is pumped to a heat stabilizer 68, into a cooler 72 and then into the refrigerated storage tank 20 of Fig. 1, nitrogen being passed in series through the stabilizer 68, the cooler 72 and the storage tank 20. Suitable gases for the concentrating are nitrogen, carbon dioxide, ethylene, helium and argon. Suitable gases mentioned for the stripping are nitrogen, argon, helium and hydrogen.