GB828888A - Improvements in and relating to the manufacture of portland cement, lime and the like - Google Patents

Abstract

828,888. Drying systems. ASSOCIATED PORTLAND CEMENT MANUFACTURERS Ltd. May 9, 1957 [May 16, 1956], No. 15315/56. Class 34(2) [Also in Group XII] Apparatus for drying and preheating granular materials such as cement raw materials, lime and ores, comprises an an nular rotary hearth 1, surmounted by a rotary bowl 2 and a fixed dome structure 22 forming therebetween an annular passage 24, and a stationary roof 3 carrying a flue 4 equipped with a fan F and a charging hopper D. Raw material fed from the hopper D by a rotary pocketed drum E is distributed over the dome 22, and traverses the passage 24 on to the hearth in countercurrent to hot gases which leave the kiln K by a shaft S and are exhausted by the fan F. The hearth rotates about an axis x-x and the bowl about an offset axis y-y. resulting in material being discharged from the hearth into the shaft S at a rate depending on the offset distance and the speed of rotation. Discharge of material from the hearth is assisted by the provision of a step 41 which may be sloped. steeply or gradually or may be dished, Figs. 4-6 (not shown). A ring 8 on the hearth rests on support rollers 9 carried by a sub-frame 27 adjustably mounted on a platform 7 carried by a framework 6, said ring being also engaged by thrust rollers 10. The sub-frame 27 may be moved by jacks 28 to vary the axis x-x. The hearth is driven by a motor N through reduction gearing and a pinion 33 engaging a driving ring 34, and, normally, frictional drag between the hearth, the bowl and the charge results in the two parts rotating together. Alternatively, the hearth and the bowl are connected by pivoted or flexible links, or are driven separately at the same speed. The bowl has a ring 13 engaged by support rollers 15 and 16 and by thrust rollers 20, all the rollers being mounted on a superstructure 18 disposed on the platform 7. The rollers may be adjusted vertically in their supports, Fig. 8 (not shown) to raise or lower the bowl. Waterseals 30 and 31 are respectively disposed between the hearth and the shaft, and between the bowl and the roof, and an air seal at 35 may be replaced by flange plates enclosing an asbestos gland. Fig. 8 (not shown). In a modification, Fig. 3 (not shown), the bowl is cylindrical in shape and the dome structure 22 is suspended on a shaft mounted in bearings on a cross-bar of the superstructure 18. Specification 828,886 is referred to.