煤热解过程中二次反应作用建模

为了弥补实验方法在研究煤热解中二次反应机理的不足,基于单体结构、碎片断裂、官能团理论和化学反应原理,建立了改进的煤粉热解模型。该模型可以由煤粉特性、反应条件预测热解产物产率及释放过程,将挥发份释放的模拟结果与一些实验结果比较,吻合较好。在此模型基础上,研究产物释放随终温的变化及二次反应的作用。结果表明:反应终温升高挥发份产率的增加主要来源于轻质气体的增加。一次反应气体产物的二次反应对热解过程有抑制作用,随着反应进行,由于化学反应平衡的移动,该抑制作用减弱,通过化学平衡原理分析了该作用的机理。

Modeling of secondary reaction effects on coal pyrolysis

Since there are few experimental studies on the mechanisms for the secondary reactions during pyrolysis,an improved coal pyrolysis model was developed which involves both primary and secondary reactions.The chemical reaction model includes monomers,function groups and molecule fraction scission theories for the primary devolatilization,as well as the gas-phase reactions and tar crosslinking for secondary reactions.The Modeling predictions compare favorably with several sets of data for the volatiles yield from devolatilization experiments.Analysis of the effects of temperature and secondary reactions show that as the final temperature increases,the volatile yield increases mainly due to the increased light gases.The secondary reactions restrain volatiles production and the effect diminishes gradually.Changes in the reveals secondary reaction mechanism is related to the reversible chemical reaction equilibrium for different temperatures for reactions involving the primary pyrolysis light gases.