水稻秸秆与煤粉混合燃烧特性及动力学

Co-combustion characteristics and kinetic analyses of rice straw and pulverized coal

采用热重分析法研究了水稻秸秆(RS)、煤粉(PC)及两者不同掺混比的混合物在不同升温速率下(10, 20, 40℃/min)从室温升至1000℃的燃烧特性,用Kissinger-Akahira-Sunose (KAS)法和Flynn-Wall-Ozawa (FWO)法计算了燃烧过程中的活化能。结果表明,失重速率(DTG)曲线中RS比PC多一个失重峰,且残余质量低。随升温速率增加,所有样品DTG曲线均向高温偏移,产生热滞后现象。RS和PC在混合燃烧过程中存在协同效应,且高温区域内更显著。PC掺混比例为50wt%时,混合物平均活化能的计算值较低,仅为76.0 kJ/mol (KAS)和83.2 kJ/mol (FWO)。

The synergistic interaction and kinetics of rice straw(RS), pulverized coal(PC) and their blends in the combustion process were investigated in this study. The content of PC in the blends were 30 wt%, 50 wt% and 70 wt%, respectively. The experiments were carried out at different heating rates(10, 20 and 40 ℃/min) under air atmosphere with a flow rate of 60 mL/min and the temperature ranged from room temperature to 1 000 ℃ in a thermogravimetric simultaneous thermal analyzer. Meanwhile their activation energy during combustion was studiedby Kissinger-Akahira-Sunose(KAS) and Flynn–Wall–Ozawa(FWO) methods. The results indicated that the RS showed one more weight loss peak than the PC in the derivative thermogravimetric(DTG) curves and the residual mass of RS was lower than PC. The different mass of PC in the samples had no obvious effect on the co-combustion weight loss characteristics at the low temperature stage, but there was significant effect in the high temperature zone. As the heating rate increasing, the DTG curves of all samples were shifted to the high temperature side, resulting in thermal hysteresis. The interaction between RS and PC was inhibited in the temperature range of 320~520 ℃. When the temperature was above 530℃, there existed positive synergistic interaction between the combustion process of RS and PC, especially at 600 ℃. The kinetic analysis showed that the values of average activation energies calculated by KAS and FWO methods were highly consistent. When the content of PC was 50 wt%, the activation energy reached the lower level, 76.0 kJ/mol by KAS and 83.2 kJ/mol by FWO, which indicated that the chemical reaction was easy to complete.