MVR空心桨叶干燥污泥的特性及动力学

Drying properties and kinetics of MVR technology applied to the hollow blade dryer drying sludge

基于空心桨叶干燥机建立了一套机械蒸汽再压缩式热泵干燥系统,将相同质量的污泥(100±0.1)kg,在真空压力约为95kPa、压缩机出口蒸汽温度为95~115℃进行恒温干燥实验,从而得到污泥干燥过程中含水率以及干燥速率等变化曲线,压缩机出口蒸汽温度为95~115℃,污泥临界湿含量从0.22增加到0.34。引入5种常用的污泥干燥模型,利用Origin软件对实验数据进行分段拟合分析,得到污泥加速阶段和降速阶段的干燥动力学模型MR=exp(-kt n)。以分段函数形式表示的干燥方程分别为:MR=exp-(2.78×10-4 T-0.01896)t1.596[],(加速阶段);MR=0.894-0.564(1.737×10-4 T-8.05×10-3)t(恒速阶段);MR=exp-(2.26×10-4 T-0.01365)t1.984[](降速阶段)。对实验得到的干燥模型进行验证,计算得到各干燥阶段污泥湿含量平均相对误差,并将实验所得干燥曲线和干燥速率曲线与模型计算值进行比较,可以看出分段处理能较好的描述污泥干燥规律。

Based hollow paddle dryer set up a mechanical vapor recompression heat pump vacuum drying system.The vacuum pressure was about 95 kPa,the same mass of sludge(100±0.1)kg at a constant temperature drying experiment at 95—115℃.Get the moisture content of the sludge drying process curves and drying rate curves.The outlet steam temperature of the compressor was 95—115℃,and the critical moisture content of the sludge was increased from 0.22 to 0.34.Five kinds of sludge drying models were introduced.The experimental data were segmented fitting analysis by using origin software and obtain sludge drying kinetics model MR =exp(-kt n),Dried equation with piecewise function expressed respectively:MR =exp-(2.78×10-4 T-0.01896)t1.596[ ](acceleration phase);MR =0.894-0.564(1.74 × 10-4 T-8.05 × 10-3)t(constant speed phase); MR = exp-(2.26×10-4 T-0.01365)t 1.984[ ](deceleration phase).The drying model was verified by experiments,the average relative error of wet content of sludge in each drying stage was calculated,and the resulting experimental drying curves and drying rate curves were compared with the predicted values.It can be seen that the segmentation process can better describe the sludge drying law.