GB1154012A - Plant for Heat Treating Pulverulent Substances - Google Patents

Abstract

1,154,012. Preheating pulverulent material. SOC. DES FORGES ET ATELIERS DU CREUSOT. 2 Aug., 1966 [4 Aug., 1965], No. 34605/66. Heading F4B. Pulverulent material introduced at 3, and following path 4 is preheated by heat exchange with counter-current flowing waste gases following path 2, on its way to a rotary kiln 1. The heat exchange occurs in pre-heaters G1, G2, G3 and D each of which are succeeded by powder/gas separators S1 S2, S3, S4. A fraction of the waste gases is recycled through paths 6 and 7 respectively by fans 6b, 7b which are driven by motors 6d, 7d respectively, each controlled by a speed regulator 6e, 7e respectively. The gas recirculation rate through path 6 is controlled by the final pulverulent material preheat temperature measured by temperature detector T1. Additionally or alternatively this rate may be controlled by the waste gas temperature entering the preheating section D (Fig. 2, not shown). The recirculation rate through the path 7 is controlled by, the temperature in the other preheaters, the pulverulent material feed rate measured by dosimeter P, and the gas flow rate at the points m 1 , m 2 in the gas flow path as measured by pressure indicator M. The recirculation rate in the systems 6 and 7 may be compared by a manometer (C, Fig. 2) and the resulting signal used either to modify the pulverulent material feed rate, or to prevent imbalance between the two recycle rates by means of a regulating device (6g, Fig. 3) incorporated in one or both of the gas recycle paths. The recycle gases, for either of the paths 6, 7 may be drawn off downstream of the last separator S1, or upstream of the first preheater G1. They may be reintroduced at more than one point.