| 摘要 |
<p>1,249,632. Preheating or drying pulverulent material. F. L. SMIDTH & CO. A/S. 29 Jan., 1969 [24 April, 1968], No. 19440/68. Headings F4B, F4G and F4U. A shaft heat exchanger 1 for pre-heating or drying falling granular or pulverulent material by means of a rising gas stream incorporates a continuous helical surface 2 forming a downwardly facing acute angle (V, Fig. 1) with the shaft wall and decreasing in pitch in the upward direction of the shaft. As shown, the heat exchanger is a preheater for heating cement raw material in a rotary kiln plant (see Fig. 3, not shown). The flow of material through the shaft can be controlled by the inclusion of a vertical frusto-conical member 5 arranged to regulate the width of the continuous gap formed between the inner edge of the helical surface and the member 5. In a modification, Fig. 4, the shaft is provided with a second helical surface 21 extending between the radially inner edge 20 of the surface 2 and the shaft wall, as shown. This arrangement permits part of the shaft wall to be removed and replaced by vertical structural bars 25.</p> |
