不同粒径城市污泥热解和燃烧动力学研究

采用德国耐驰公司STA 409pc热重分析仪,对3个不同粒径的污泥颗粒(d≤0.25mm,0.25mm0.83mm)以升温速率20℃/min在纯氮和空气气氛中进行实验,并对污泥进行了元素分析和工业分析,对金属的含量进行测定.采用MATLAB 7.11.0(R2010b)中的surface fitting tool进行平面拟合的方法计算了相关的动力学参数.结果表明,污泥的热解可以分为3个阶段:水析出阶段(100～180℃)、挥发份热解阶段(205～550℃)和部分难挥发有机物与无机物的降解阶段(550～900℃).而污泥的燃烧可以分为4个阶段:水析出阶段(100～180℃)、挥发份的燃烧阶段(180～475℃)、碳燃烧阶段(475～595℃)和无机盐分解阶段(595～900℃).不同粒径下污泥热解第2阶段活化能约为48kJ/mol,反应级数为1.5～1.8.燃烧第2阶段的活化能约为33kJ/mol,反应级数为1.1～1.8.燃烧第3阶段活化能约为176kJ/mol,反应级数为1.1～1.2.

Research on the Pyrolysis and Combustion Kinetics of Sewage Sludge of Different Sizes

The pyrolysis and combustion of sewage sludge particles(d≤0.25 mm,0.25 mm0.83 mm) were analyzed with the thermogravimetric analyzer(TGA,STA 409 model,NETZSCH,Germany) at the heating rate of 20 ℃/min.To determine the chemical characteristics of sewage sludge,elemental and proximate analysis was carried out,and the metal content of the dry sewage sludge was determined.Meanwhile,a new method was developed to calculate pyrolysis kinetic parameters with surface fitting tool in software MATLAB7.11.0(R2010b).The results have shown that sewage sludge pyrolysis process are divided into three stages: water evaporation(100～180 ℃),volatile matter pyrolysis(205～550 ℃) and inorganic salt decompose(550～900 ℃).Sewage sludge combustion process are divided into four stages: water evaporation(100～180 ℃),volatile matter combustion(180～475 ℃),carbon combustion(475～595 ℃) and inorganic salt decompose(595～900℃).The pyrolysis kinetic parameters of the second stage are as follows: the reaction orders are in the range of 1.5～1.8 and the activation energy is about 48 kJ/mol.The combustion kinetic parameters of the second stage and the third stage are as follows: the reaction orders are in the range of 1.2～1.3 and 1.1～1.2,and the activation energy is about 48 kJ/mol and 176 kJ/mol respectively.