城市污泥和煤泥混燃过程中交互作用的影响及机理

Influence and mechanism of interaction in co-combustion of sewage sludge and coal slime

为了明确污泥(sewage sludge,SS)和煤泥(coal slime,CS)在混燃过程中的交互作用并区分催化机制和非催化机制对交互作用的贡献,在获得燃料基本特性的基础上,利用热重分析仪研究不同污泥(原污泥、酸洗污泥、脱挥发分污泥)和煤泥的混燃特性,分析交互作用的影响及机理,并采用Coats-Redfern积分法研究燃烧动力学特征。研究结果表明:在混燃过程中,污泥可以提高共混物的着火性能,煤泥则可提高共混物的高温反应性;混燃过程中出现明显的交互现象,可归因于非催化和催化机制的共同作用,其中,非催化作用主要发生在挥发分析出阶段,对燃烧有抑制作用,协同指数为−0.24~−0.01。催化作用主要发生在固定碳燃烧阶段,可有效促进燃烧,协同指数为0.1~0.44。对于整个燃烧过程来说,污泥和煤泥具有协同作用,且脱挥发分可使协同作用增强;SS和CS的活化能分别为37.33~42.35 kJ/mol和80.77 kJ/mol,混燃时SS可降低共混物的表观活化能,同时协同作用使共混物的表观活化能低于其理论值。

In order to clarify the interaction between sewage sludge(SS) and coal slime(CS) in the co-combustion process, and to distinguish the contribution of catalytic and non-catalytic mechanisms to the interaction, on the basis of obtaining the basic characteristics of the fuels, the thermogravimetric analyzer was used to study the cocombustion characteristics of different sewage sludges(raw sludge, demineralized sludge, devolatilized sludge,)and coal slime. The influence and mechanism of the interaction were analyzed, and Coats-Redfern integration method was used to study the combustion kinetics characteristics. The results show that during the co-combustion process, SS can improve the ignition performance of the blend, and CS can improve the reactivity in the high temperature region. The obvious interaction phenomenon during the co-combustion process can be attributed to the combined effect of non-catalytic and catalytic mechanisms. Non-catalytic effects mainly occur in the devolatilization stage, which inhibits combustion, and the synergy index is-0.24--0.01. Catalytic effect mainly occurs in the fixed carbon combustion stage, which can effectively promote combustion, and the synergy index is 0.10-0.44. For the entire combustion process, there is a synergistic effect between SS and CS, and devolatilization treatment can enhance the synergy. The activation energy of SS and CS is 37.33-42.35 kJ/mol and 80.77 kJ/mol,respectively. SS can reduce the apparent activation energy of the blend during co-combustion, and the synergistic effect makes the apparent activation energy of the blend lower than its theoretical value.