GB789961A - Improvements in processes and apparatus for exchanging heat between solid particles and gases - Google Patents

Abstract

789,961. Furnaces for treating solids in suspension. SMIDTH & CO., AKTIESELSKAB, F. L. Oct. 20, 1954 [Nov. 9, 1953], No. 30976/53. Class 51 (2). [Also in Group XIII] Apparatus for carrying out heat-exchange between a particulate solid and a gas, applicable to the stages of drying, preheating, calcining, sintering and cooling in cement manufacture or to the burning of lime or ores, comprises a vertical shaft, means for introducing gas into the shaft to flow up it, means at a higher point for introducing solid particles into the shaft to form a suspension in the gas moving downwards through the gas under gravity, and transverse partitions extending across the shaft and having openings which increase in size from top to bottom of the shaft whereby the downward movement of the particles is checked as they pass through the openings. The invention may be applied to apparatus for the preheating of cement raw materials in which the tower is disposed between a rotary cement kiln and a cyclone separator, Fig. 1 (not shown). The tower 2 is divided by partitions 8 formed with openings 9 alternating with partitions 10 formed with large central openings 11. The diameter of the openings 9 decreases from the bottom to the top of the tower, and they may be inclined to the shaft axis as shown in dotted lines at 16 inducing a whirling motion in the gas. The latter enters from the kiln at 7, is alternately contracted and expanded in its passage through the partitions 8 and 10, and is removed from the top of the tower by a tangential offtake 15. The granulated material, preferably in nodules averaging 0.5-2.5 mm. across, is charged in counter-current to the gas stream through an upper central hopper 14. Fig. 3 shows a plant in which slurry fed through a line 26 and dust fed through lines 24 and 25 from a cyclone 19 and filters 21 respectively is formed into nodules in the apparatus 23, which may be of the type disclosed in Specification 789,964, [Group II]. The nodules are discharged by a conveyer 27 into the tower 2, which is constructed as previously described, and which leads to the kiln 1. The hot gases may be supplied from a separate, stationary furnace,