循环喷动流化床固体流动规律

SOLIDS FLOW CHARACTERISTICS IN SPOUT - FLUIDIZED BED WITH DRAFT TUBE

循环喷动流化床由于循环管(导向管)的引入,显著地提高了射流床的操作能力、传热传质特性及接触效率,因而被广泛地应用于化工过程,如:颗粒涂层、煤气化和石油烃类的热裂解)。 鉴于循环喷动流化床的广泛应用,许多研究者对床层的气固流动循性进行了研究,但是由于实验的几何参数、特性参数及操作参数的不同,实验结果存在着较大的差异,有关固体循环速率的数学模型报道很少,已有的模型也因假设条件太多及考虑影响因素不全而不具有普遍的适用性,本文通过研究几何参数、操作参数及物性参数对固体循环速率的影响,进而得出综合考虑以上参数在内的预测固体循环速率的定量方程,为工程设计提供重要信息。

A 200mm×50mm×1450min two -dimensional spout -fluidized bed with a central draft tube was used to study the effect of geometry and operating parameters as well as phys ical properties of material on solids circulation rate. Four different solids and draft tube sizes were used in this study. With increasing gas feed rate, the gap between the draft tube inlet and conical distributor (R), the distance between the nozzle and the draft tube inlet (L1) , the draft tube area, and the solid circulation rate will be increased. The draft tube height has no effect on solids circulation rate. A quantitative correlation, derived from the concept of the gravity flow of particles through the gap (R) and consisting of geometric, operating, as well as material parameter, was proposed for predicting the solids circulation rate of this type of bed.