生物质与煤富氧混合燃烧特性研究

Study on Oxy-fuel combustion characteristics of biomass and coal blending

采用热重分析仪研究了棉秆、玉米芯和大同煤以及它们之间混合燃料的富氧燃烧特性。分析了富氧条件混合燃料的燃烧特征参数,如着火温度、峰值燃烧速率及其对应温度、燃尽温度及综合燃烧特性指数。采用Coat-Redfern法计算混合燃烧动力学参数。结果表明:在O2/CO2气氛下,提高氧气浓度可以改善生物质与煤混合燃料的燃烧反应,降低燃尽温度,使混合燃料的燃烧反应向低温区域移动;燃烧反应活化能在挥发分析出和固定碳燃烧的两个阶段均增大;但生物质与煤的掺混比例在30%情况下,氧气浓度的变化对混合燃料的着火温度的影响规律并不明显。在50%O2/50%CO2气氛下,随着生物质比例的增加,所有特征参数向低温区域前移,混合燃料燃烧反应活化能在挥发分析出阶段逐渐减小,在固定碳燃烧阶段逐渐增大。Coat-Redfern模型可以较好的描述棉秆或玉米芯与大同煤混合物在空气或富氧条件下的主要燃烧过程。

Combustion characteristics of Datong bituminous coal, cotton stalk, corncob and their blend with different ratio under oxy-fuel condition were investigated with thermogravimetric analysis. Com- bustion parameters, such as ignition temperature, peak temperature of the peak weight loss rate, burnout temperature and general combustion parameters were netic parameters were calculated by Coat-Redfern analyzed. Based on experimental results, the ki- method. The results under O2/CO2 atmosphere showed that increasing oxygen concentration can improve combustion reduce burnout temperature and move the combustion reaction of the blend fuel to the lower temperature region. The reaction activation energy increased in the stages of volatile precipitation and fixed carbon combustion. However, the change of oxygen concentration had little influence on the ignition temperature when the blending ratio of biomass and coal was 30%. Under 50%O2/50%CO2 atmosphere, with the increase in the biomass ratio. All the combustion parameters moved to lower temperature region, and the reaction activation energy decreased in the volatile precipitation stage and increases in the stage of fixed carbon combustion. Coat-Redfern model can describe the main combustion process of the blending of cotton stalk, corncob and Datong coal under the condition of air or oxygen atmosphere.