GB643184A - - Google Patents

Abstract

643,184. Cooling powdered material. LUWA AKT.-GES., and ANDERMATT, C. Dec. 30, 1947, No. 34661. Convention date, July 9, 1946. [Class 64(ii)] Relates to a process for cooling a powder yielded by the pulverization drying process and continually exhausted from the drying chamber by means of a stream of the gas used for drying, in which, after the mixture of drying gas and powder has been withdrawn from the drying chamber, firstly a portion of the drying gas is withdrawn after which the powder, together with the remainder of the drying gas, is passed into a current of cool gas flowing in the same direction and is carried therein to a dust extractor, the powder being cooled in transit to the dust extractor by contact with the cool gas. According to the invention, a plurality of such devices are connected in parallel the powder'and drying gas residue being combined in each single stream with an adjustable current of added cooling gas and the separate steams being combined into a single stream leading to the dust extractor. Apparatus for carrying out the process comprises, in the form shown, a plurality of drying gas extractors 2, 3 connected to the pulverization drying chambers (not shown) by means of a duct 1 and each having a pipe 9 contiguous thereto for the cooling gas which continues the conveyance of the powder. The pipes 9 are ultimately combined in a duct 10 which leads to the dust extractor. Each pipe 9 has an initial portion 6 of enlarged crosssection into which projects the discharge opening 16 leading from the drying gas extractor 2 or 3 and the cooling gas enters this enlarged section at a point 7 which lies behind the opening 16. To prevent condensation in the dust extractor that portion which projects into the enlarged portion of the pipe 9 may be provided with a heat-insulating envelope 15. The chambers formed by the enlargement of the pipe 9 may be divided into two parts 11, 12 by a perforated transverse wall or by a local constriction in the enlargement 6 or by an adjustable flanged ring 14. That portion of the drying gas which is extracted initially is led away through the duct 4. Air or an inert gas is mentioned as the cooling medium.