高温流化床的流化特性及结焦非流化行为

Flow Characteristics and Defluidization Behavior with Agglomeration at High Temperature Fluidized Bed

在 8 0 mm× 30 mm和 80 mm× 10 mm石英流化床中 ,以低温粘结的高密度聚乙烯和聚丙烯 ,高温粘结的玻璃珠为实验物料 ,研究了高温流化床的流化特性及高温下物料结焦产生的非流化行为。结果表明 ,在本文实验条件下 ,Geldart A、B类高温表面粘结物料 ,床层温度小于其最小粘结温度时 ,床层温度增大 ,颗粒的最小流化速度减小 ;Geldart D类高温表面粘结物料的最小流化速度随温度增加而增大。得出了不同温度下颗粒最小流化速度预测式。床层温度大于最小粘结温度时 ,流化床需在较高的表观气速下才能保持流化 ,床层温度愈高床层流化所需的表观气速越大。研究同时发现 ,颗粒物料的粒径减小 ,流化颗粒的最小粘结温度减小。

Flow characteristics and defluidization behavior due to agglomeration at high temperatures were investigated in two fluidized beds made of quartz, a 80 mm long, 30 mm wide and a 80 mm long, 10 mm wide. Various experimental materials, including high density polyethylene, polypropylene and glass beads with different size distributions were employed. When the temperature of the fluidized bed was lower than the minimum sintering temperature (Tx), the minimum fluidization velocity of sintering material, belonging to Geldart groups A and B, decreased with the increase of the bed temperature, while the minimum fluidization velocity of sintering material, belonging to Geldart group D, increased with the bed temperature. A correlation for predicting the minimum fluidization velocity of sintering materials was proposed. The superficial gas velocity should be larger than Umf to keep the fluidized bed fluiding when the bed temperature was higher than the minimum sintering temperature. In addition, the sintering material with a small diameter corresponds to a lower minimum sintering temperature.