油菜秸秆颗粒-石英砂在导向喷动流化床内的流动特性

Operating Characters of Quartz Sand and Oilseed Rape Straw in Spout-fluidizing Bed with a Draft Tube

在内径0.15 m、高1.04 m的有机玻璃导向喷动流化床内,观察了秸秆颗粒-石英砂二元混合物系的流动特性。结果表明:最小喷动流化速度随静止床层高度和秸秆颗粒在混合物中比例的增加而减小;流化气的引入有利于喷动,可使喷动气气速减小,但会使最小喷动流化速度增大。固体循环速率随静止床层高度增加先快速增加后增加趋缓,随秸秆颗粒比例的增加而减小,但秸秆颗粒的循环速率变化不大。随静止床层高度的增加,中心喷泉高度在0.092 m之前快速增加,0.092 m之后有小幅度增加,秸秆颗粒比例增加,中心喷泉高度减小。操作相图可分为固定床、局部喷动流化床、喷动流化床、带出床4部分,喷动流化区域随静止床层高度的增加而减小,随秸秆颗粒在混合物中质量比例的增加而增大。最后,提出了导向管喷动流化床最小喷动流化速度和中心喷泉高度的关联式。

An experimental study on flow characters of oilseed rape straw and quartz sand in spout- fluidizing bed with a draft tube has been performed. The result shows that the minimum spout-fluidizing velocity decreases with increasing static bed height and the proportion of oilseed rape straw in mixture. Fluidizing gas can minimize the spouting gas velocity, but it results in an increase in minimum spout-fluidizing velocity. Solid circulation increases rapidly first and then slowly with increasing static bed height, and it decreases with increasing proportion of oilseed rape straw in mixture, but the circulation of oilseed rape straws is unchanged basically. A rapid increase in centre fountain height was measured as the static bed height is below 0. 092 m,while later on it slowly increases. Centre fountain height decreases with increasing static bed height. The flow regime map is divided into four parts such as fixed bed,partly spout- fluidizing bed,spout-fluidizing bed and carry-out bed. The range of spout-fluidizing bed decreases with increasing static bed height and increases with enhancing proportion of oilseed rape straw in mixture. Finally, the correlations used to calculate minimum spout-fluidizing velocity and central fountain height are obtained.