液固循环流化床的研究(Ⅰ)相含率及颗粒循环速率

LIQUID - SOLID CIRCULATING FLUIDIZED BED ( I )STUDIES ON THE PHASE HOLDUPS AND SOLID CIRCULATING RATE

在内径为140mm、高为3m的有机玻璃设备中对液固并流向上的循环流化床中两相流动特性进行了研究.相含率的研究表明,在循环流态化条件下,全床相含率轴向均匀分布;而径向具有显著的不均匀性,表现为中心区液相含率高,在r/R=0.7处液合率最低.颗粒循环速率的研究表明,在循环流态化区域,在一定的二次水流速下,颗粒循环速率不随总液速的改变而改变.由于在循环流态化下存在床层径向参数的不均匀性,因此床层的相合率与颗粒循环速率的关系与广义流态化方法预测的结果间存在差异,即在操作条件一定的情况下,床层内真实液合率比由广义流态化预测的低.

The hydrodynamics of a liquid - solid circulating fluidized bed was investigated in a plexiglass equipment of 140 mm in inner diameter and 3 m in height. In the circulating fluidizing regime, the bed has the characteristics of uniform distribution of phase holdups in the axial direction but non - uniform in the radial position. The solid circulating rate keeps constant when the superfacial liquid velocity changes within the circulating fluidization regime. Because of the non-uniformity of the phase holdups in the radial position there is a great difference between the theoretical results based on the generalized fluidization principles and the experimental results of the variation of the solid circulating rate versus the bed voidage.