重庆城市污泥燃烧及动力学特性分析

Study on Combustion Characteristics and Kinetics of Chongqing Municipal Sewage Sludge

为研究重庆某污水处理厂剩余污泥的燃烧及动力学特性,采用热重(thermogravimetry,TG)–差示扫描量热(differential scanning calorimetry,DSC)同步分析仪对自然风干的污泥样本在空气流中进行燃烧试验,分析所得TG-DSC试验数据并将污泥的热反应进程划分为:化学结合水与小分子挥发分析出、挥发分析出着火气相燃烧、半挥发性有机质析出燃烧、难降解有机质与固定碳燃烧、方解石与燃烧残余物的分解。试样着火性能较好;其综合燃烧特性随升温速率的增加单调减小。当升温速率超过25 K.min-1时,试样平均活化能显著增加;当升温速率低于25 K.min-1时,其平均活化能波动较小。选取Coats-Redfern积分法分析污泥燃烧特性并求解各主要热反应阶段的表观活化能E和表观频率因子A,建立污泥燃烧动力学模型。

In order to study the combustion characteristics and kinetics of sewage sludge from a sewage treatment plant in Chongqing, a sync analyzer of thermogravimetry （TG） and differential scanning calorimetry （DSC） were used for testing parameters of sewage sludge combustion in air condition. According to the parameters obtained, the entire process of weightlessness during sewage sludge combustion can be divided into five phases： precipitation of water and small molecule volatile, precipitation and gas-phase combustion of volatile, precipitation and combustion of semi-volatile, combustion of recalcitrant organic matter, thermal decomposition of calcite and relicts. The ignition of samples is good and the comprehensive combustion characters monotonically decrease with increasing of the heating rate. The mean activation energy significantly increases when the heating rate exceeds 25 K·min-1 and small changes of it occurrs when the heating rate less than 25 K·min-1. An integral method of Coats-Redfern was employed to analyze the kinetics of sewage sludge combustion characteristics. The apparent activation energy and pre-exponential factor of central combustion phases were calculated. The dynamic models were established on the basis of kinetic parameters.