不同来源污泥混燃特性及其综合燃烧性能评价

Co-combustion of various sources of sludge and its combustion performance

采集了广州两种生活污水污泥、两种工业污泥(印染污泥和造纸污泥),利用热重法对这4种不同来源的单一干污泥及混合污泥在不同条件下进行实验研究,同时计算了试样的4个燃烧特性指数,获得了污泥燃烧的动力学参数.实验结果表明,各污泥燃烧阶段主要分为水分析出、挥发分析出、固定碳的燃烧和无机盐类挥发分解4个阶段,其中挥发分的析出和燃烧制约着污泥燃烧整个过程.市政污泥S1与其他类污泥混烧过程中,各污泥有较明显的交互作用,其中市政污泥S1与其他3种污泥按照1∶1质量比混合后,其挥发特性指数D提高较明显,而综合燃烧特性指数S改变不明显.两种市政污泥8∶2质量比混合后,其混合样燃烧性能明显提高,其中综合燃烧指数提高接近2倍.采用积分法(Coats-Redfern方程)计算得到各燃烧阶段反应的机理方程及相应的活化能参数,发现各试样燃烧反应级数不尽相同,其中市政污泥S1与其他污泥混合后活化能E普遍降低,与样品S2混燃的活化能降低最多,对燃烧最有利.

Two kinds of sewage sludge samples and two kinds of industrial sludge samples（ dyeing sludge and papermaking sludge） were collected in Guangzhou. Those four kinds of sludge samples and their mixtures were estimated by thermogravimetric analysis（ TGA） under various conditions. Four combustion indexes and their kinetic parameters were also calculated. Experimental results showed there were four combustion steps for sludge samples found as moisture exhalation,volatile exhalation,fixed carbon combustion and exhalation of inorganic salt. Thus,volatile exhalation stage was considered as the dominating step of sludge combustion in this study. When blending sewage sludge S1 with other kinds of sludge,it was discovered that a significant interaction among those four sludge samples. Volatile characteristic index（ D） increased,but the combustion performance（ S） varied insignificantly while the sewage sludge S1 mixed with other sludge samples with the ratio of 1∶1. Nevertheless,the combustion performance could improve when sewage sludge samples were mixed,and the comprehensive combustion index also increased up to 2 times. On the other hand,Coats-Redfern equation was adopted to understand both reaction equations and the kinetic parameters（ E） during various combustion stages. Calculation results showed that different reaction orders were found under combustion of various mixtures. The activation energy decreased with the increase of sewage sludge S1 in mixed sample. Notably,the activation energy reduced significantly during co-combustion of sludge with S2 sample,and it contributed the thermal treatment of sludge via combustion.