| 摘要 |
<p>1,040,791. Drying foamed material. AMERICAN MACHINE & FOUNDRY CO. Feb. 3, 1964 [Feb. 15, 1963], No. 4474/64. Heading F4G. [Also in Division A2] A method of drying a foam, e.g. a food such as tomato paste or tea or fruit juice concentrates, consists in depositing the foam in a layer up to 0À1 inch thick on a moving support, applying heat by condensing a vapour on the underside of the support and passing a drying gas over the foam on the support. The layer is preferably 0À005-0À040 inch thick and the moving support is preferably an impervious, e.g. metallic, endless belt. The condensing vapour which applies the heat is preferably a mixture of air and steam, and the drying gas is preferably air at 140-210‹ F. moving at a velocity of 500-1500 ft./min. relative to the foam, preferably transversely to the direction of movement of the conveyer belt. At the terminal portion of the drying process the foam may be passed under an inert gas or a dessicated gas, and the end product may be treated with an azeotroping agent and re-dried. Food emulsion from hopper 10 and a foam stabilizing emulsion 12 are spread on to endless belt 26, preferably of stainless steel, by spreader 22. The foam layer passes under drying hoods 28 (see also Fig. 3) into which heated air is introduced at 29 centrally of the belt, moves transversely across the belt and is exhausted at 35. Instead of air, an inert gas may be used in the last drying hood. Under the belt, heat is applied by steam chests 30 into which a controllable proportion of air may be admitted at 33. As shown, the dried material is removed at 40, but alternatively the material may be left adhering to the belt and further drying effected by enclosing the lower run of the belt in a drying tunnel, the material being removed at the bottom of roller 23.</p> |
