生物质焦与煤混合燃烧特性及动力学分析

Combustion characteristics and kinetic analysis of biomass char and coal blends

利用热重分析天平,采用非等温燃烧的方法对生物质热解产物——生物质焦与两种无烟煤混合试样的燃烧特性及其反应动力学参数进行了实验研究,考察了不同配比的混合试样的着火温度、燃烧速率最大时温度、燃尽温度和最大燃烧速率等燃烧特征参数,求出了反应的动力学参数活化能Ea和指前因子A.结果表明:活化能和指前因子均随混煤中生物质焦比例的增加而降低,存在动力学补偿效应;煤中掺入生物质焦后,试样燃烧的第一阶段和第二阶段的活化能分别呈现出"U形"曲线和"阶梯形"曲线的规律,且对混合燃料热解过程的作用要优于对固定碳燃烧过程的作用;活化能的计算表明生物质焦的存在有助于改善煤的着火性能,对煤的燃烧有催化促进作用.

Experimental research on non-isothermal combustion characteristics and dynamic parameters of biomass char and coal blends was conducted with a thermo gravimetric balance. The combustion characteristic parameters such as ignition temperature, peak temperature at maximum weight loss rate, burnout temperature, and maximum combustion rate were studied by thermo-gravimetric anal- ysis. The kinetic parameters of reaction such as activation energy and frequency factor for samples in different ratios were calculated. It is shown that both the activation energy and the frequency factor decrease with increasing biomass char content in the blend and the ki- netic compensation effect exists in the two parameters. The combustion of biomass char and coal blends is divided into two stages, cor- responding to the regularities of the U-shaped curve and the ladder-shaped curve for activation energy, respectively. Biomass char has more remarkable effect on pyrolysis than charcoal combustion. It is indicated for the calculating results of activation energy that biomass char can improve the ignition property of coal.