污泥低温干燥动力学特性及干燥参数优化

发布时间：2018-03-04 00:20

  本文选题：干燥　切入点：模型　出处：《农业工程学报》2017年17期 　论文类型：期刊论文

【摘要】：为了研究污泥的低温干燥动力学特性,以薄层污泥为研究对象进行了低温干燥试验,探讨了温度、薄层厚度以及风速对污泥水分比和干燥速率的影响,并对低温干燥参数进行了优化。结果表明:污泥低温干燥过程主要由升速和降速段组成,其中降速阶段存在第一、第二降速阶段;不同低温干燥条件下的第二临界含水率变化不大,大致在0.5 g/g(干基)附近。使用决定系数R2、卡方χ2及均方根误差RMSE对6种常用干燥模型进行评价,结果表明Midilli模型的平均R2最大、平均χ2及RMSE最小,分别为0.999 8、2.46×10-5、0.004 2,是描述污泥低温热风干燥的最优模型。根据Fick第二定律和Arrhenius方程,得到5、10和15 mm厚度污泥在50~90℃热风干燥的水分有效扩散系数和活化能。正交试验得到相对单位能耗最优干燥工艺为:温度90℃、风速0.8 m/s、厚度10 mm,平均干燥强度最优工艺为干燥温度90℃、风速0.8 m/s、厚度5 mm。试验结果可为后续研究污泥热泵干燥及太阳能-热泵联合干燥提供参考。
[Abstract]:In order to study the dynamic characteristics of sludge drying at low temperature, the effects of temperature, thickness of thin layer and wind speed on the moisture ratio and drying rate of sludge were studied. The parameters of low temperature drying were optimized. The results showed that the process of sludge drying at low temperature was mainly composed of increasing speed and decreasing speed. Under different low temperature drying conditions, the second critical moisture content changed little, about 0.5 g / g (dry base). The determination coefficient R2, chi-square 蠂 2 and root-mean-square error (RMSE) were used to evaluate six common drying models. The results show that the average R2 of Midilli model is the largest, the average 蠂 ~ 2 and RMSE are the smallest, which are 0.999 8 脳 10 ~ (-5) N _ (0.0042), respectively. It is the best model to describe the low temperature hot air drying of sludge. According to the second law of Fick and Arrhenius equation, The moisture effective diffusion coefficient and activation energy of sludge with thickness of 5 ~ 10 and 15 mm were obtained by hot air drying at 50 鈩，

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