流化床干燥实验装置气体分布板的改进

Improvement of the Gas Distributor for the Experimental Fluidized Bed Dryer

原流化床干燥实验装置没有布置气体分布板,使得床层内存在很大的死角,难以形成较佳的床内流场分布,导致学生做实验时所测得的临界含水率增大,干燥速率变小,干燥速度曲线恒速干燥阶段无法确定,鉴于此,采用双层直流式锥形孔气体分布板改进了原流化床干燥实验装置。经FLUNET数值模拟分析发现,经改进后,热空气在颗粒床层内分布的均匀性显著提高,其扩散范围明显扩大,流速更加趋于稳定,则进出口的速度差显著地降低了,减小为原实验装置的0.072倍,从而使热空气更均匀地干燥床层内的固体颗粒变色硅胶,可减小实验误差,提高实验结果的准确率。

The former experimental fluidized bed dryer did not arrange the gas distributor to cause the existing of dead angle and bad flow field distribution of the hot air in the fluidized bed. This may lead to increase of the experimental data of critical moisture content and decrease of drying rate,which is hard to determine constant the speed stage of drying speed curve. Therefore,this experimental fluidized bed dryer was improved by using of the double direct-air conical-hole gas distributor. The flow field of before and after improvement of experi-mental fluidized bed dryer was analysis by FLUNET numerical simulation. The results showed that the hot air was well distributed in the fluidized bed after improvement of experimental fluidized bed dryer,and its range of scatter was wider. Moreover,the velocity of the hot air was tended to be stable,and then its velocity difference was 0. 072 times of the former experimental fluidized bed dryer. Consequently,the hot air may more evenly dry granular allochroic silica gel in order to decrease experimental error and increase accuracy of experimental re-sult after improvement of experimental fluidized bed dryer.