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组合加热流化床干燥机综合了间接加热热效率高及普通流化床热质传递效率高的优点 ,在高湿含量物料及热敏性物料的干燥中具有优势。本文考察了带水平传热管束的组合加热流化床干燥机中各操作条件对传热系数及干燥机热效率的影响。结果表明 ,操作气速及床层温度对传热系数及热效率有较大影响 ,操作气速增大 ,传热系数先增大后降低 ,存在一个最大值 ,而热效率呈单调下降 ;床层温度升高 ,传热系数增大 ,而热效率降低 ;因此 ,合理选择这些操作条件 ,对提高传热系数及热效率是非常重要的。工业装置的运行结果表明 ,该干燥机的热效率达70 %以上 ,远高于普通流化床干燥机。
Combined heating fluidized bed dryer combines the advantages of high indirect heat efficiency and high heat and mass transfer efficiency of ordinary fluidized bed and has advantages in drying of high moisture content materials and heat sensitive materials. This paper examines the effects of operating conditions on the heat transfer coefficient and the thermal efficiency of the dryer in a combined heated fluidized bed dryer with horizontal heat transfer tubes. The results show that the operating gas velocity and bed temperature have a great influence on the heat transfer coefficient and thermal efficiency. The operating gas velocity increases, the heat transfer coefficient first increases and then decreases, with a maximum value, while the thermal efficiency decreases monotonously. The bed temperature Increase, heat transfer coefficient increases, and thermal efficiency decreases; Therefore, a reasonable choice of these operating conditions, to improve the heat transfer coefficient and thermal efficiency is very important. The operation results of the industrial plant show that the thermal efficiency of the dryer reaches more than 70%, which is much higher than that of an ordinary fluidized bed dryer.