生物质与烟煤混合燃烧特性及动力学分析研究

使用非等温热分析方法研究了生物质(麦秆)和烟煤混合燃烧的反应特性。结果表明,生物质的添加可以降低混合样品的燃烧着火温度和燃烬温度,且混合样品燃烧反应性能随着生物质混合比例的增加而提升;生物质添加质量分数为20%时,煤和生物质混合燃烧协同作用最明显。使用Coats-Redfern(CR)、Flynn-Wall-Ozawa(FWO)和Kissinger-Akahira-Sunose(KAS)动力学模型对混合样品燃烧活化能进行计算,其值在挥发分燃烧阶段随着生物质混合比例的增加而增加,在焦炭燃烧阶段呈现下降趋势;通过对FWO和KAS动力学模型有效性进行分析发现,FWO和KAS模型在描述混合样品燃烧动力学时存在一定的局限性,而采用适宜机理函数的CR模型更适用于描述混合样品的燃烧反应动力学,对燃烧机理的分析也印证了动力学的分析结果。

Study on combustion characteristics and kinetic analysis of biomass mixed with bituminous coal

The reaction characteristics of wheat straw(WS)and bituminous coal(BC)mixed combustion was studied using non-isothermal thermogravimetric analysis(TGA).The results showed that the addition of biomass could lower the ignition temperature and burnout temperature of blends,and the combustion reactivity of blends increased with the increase of biomass proportion.When the biomass ratio was 20%,the most obvious interaction between coal and biomass was obtained.Coats Redfern(CR),Flynn-Wall-Ozawa(FWO)and Kissinger-Akahira-Sunose(KAS)kinetic models were used to calculate the activation energy of the mixed combustion.The results showed that the activation energy increased with the increase of biomass proportion during the combustion of volatiles,and decreased during the coke combustion.Based on the analysis of the validity of FWO and KAS kinetic models,it was found that FWO and KAS had some limitations in describing the combustion kinetics of the mixed sample,while CR model with appropriate mechanism function was more suitable for describing the kinetics behavior of the blends.The analysis of combustion mechanism also confirmed the results of kinetic analysis.