市政污泥干化动力学研究

利用同步热分析仪(TGA/DSC),采用非等温法,开展了市政脱水污泥干化过程的动力学研究。分析了升温速率对污泥干燥过程的影响,确定出污泥干化过程的最概然机理函数G(α)MP,计算了不同升温速率下的表观活化能E和指前因子A。结果表明,污泥非等温干燥过程可以分为缓慢加速、快速加速和减速3个阶段;升温速率的增大会缩短加速段干化时间,但对减速段没有影响;随着升温速率的增加,干化活化能和指前因子先增大后减小,活化能在19.45~28.46 kJ/mol之间变化,指前因子变化范围为1.5×105~5.0×106 s-1,且在升温速率为15 K/min时两者达到最大值;干燥过程最概然机理函数的积分形式为G(α)MP=1-(1-α)4反应级数为4;污泥干燥过程的活化能和指前因子之间存在动力学补偿效应。

Investigation of drying kinetic of municipal dewater sewage sludge

Thermogravimetric experiments of municipal dewater sewage sludge were carried out with non-isothermal temperature programs by TGA/DSC. The effects of heating rate on the drying of sludge were analyzed. The most probable mechanism function G(α)MP was obtained. The results indicated that three drying stages of the slowly speed-up, the fast speed-up and speed-down drying were distinguished in sludge drying. The time of the speed-up drying stage decreased with the raise of the heating rate, but no changes were found at speed-down drying stage. The active energy E and the pre-exponential A were calculated at different heating rates, they varied within the range between 19.45~28.46 kJ/mol of E and 1.5×105~5.0×106 s-1 of A. The maximum of E and A were obtained when the heating rate was 15 K/min. The most probable mechanism function G(α)MP =1-(1-α)4 of drying progress was determined. According the results, the kinetic compensation effect between A and E existed.