微波热解污泥燃气释放影响因素及热解动力学分析

Factors Affecting Energy Gas Released in Microwave Pyrolysis of Sewage Sludge and Relevant Thermal Pyrolysis Kinetics

微波热解城市污水污泥可实现污泥资源化、减量化目标。城市污水污泥微波热解后产生大量能源气体H2和CO。运用气相色谱技术检测H2和CO的含量,研究了热解终温、污泥含水率、矿物催化剂对污泥微波热解过程中能源气体产率的影响,结合热重分析对热解过程进行了动力学分析。结果表明:随着热解终温升高,2种燃气产率均有所提高,800℃时,1 kg干污泥产生29.02 g H2以及302.72 g CO,两者体积之和占气体总体积的58%;污泥含水率越高,气体产率越高,但是达到90%含水率时,热解过程无法进行。镍基催化剂和白云石对能源气体产率均有促进作用,800℃时,镍基催化剂可使H2和CO产率提高到60%,对CxHy产率提高效果不明显;利用一级反应动力学方程对污泥热重结果进行分析,计算出热解动力学参数。

Sewage sludge treatment by microwave-induced pyrolysis could lead to the goal of both of resource recycling and sludge reduction, and the energy gas such as H2 and CO could be produced in the microwave pyrolysis process of municipal sewage sludge. This paper referred to experimental studies carried out on bench scale by use of GC to determine the contents of energy gases, i.e., H2 and CO, investigating the influences of pyrolysis conditions, which involved pyrolysis temperature,sludge water contents and the mineral catalyst, on energy gas productivity; in addition, thermo-gravimetric analysis（TGA） was used to research the pyrolysis kinetics. Results of the studies showed that productivity of energy gas increased with an increase of pyrolysis temperature; and 29.02 g of H2 and 302.72 g of CO were produced per gram of dry sludge at the temperature of 800 ℃. While an increase of sludge water content would lead to enhanced productivity of energy gas, but pyrolysis process failed in the case where water content went up to 90%. Nickel catalyst and dolomite could also boost the energy productivity, e.g., the total of H2 and CO gas volume rose to 60% of total pyrolysis gas when adding nickel catalyst.Finally, pyrolysis kinetics parameters of sewage sludge were calculated by using first order reaction kinetics equation to analyze TGA results.