CO2的物理化学属性对于煤粉富氧燃烧着火的影响

摘要

Many researchers found that,compared with O2/N2 atmosphere,the ignition of pulverized coal was de-layed in O2/CO2 atmosphere with the same mole fraction of O2,and attributed the ignition delay to the higher volume specific heat of CO2.The artificial materials X,Y and W are introduced to study the effects of chemical properties, specific heat and radiation characteristics of CO2 in homogeneous and heterogeneous ignition processes of coal parti-cles,respectively.The results show that in the homogeneous ignition of coal in O2/CO2 atmosphere,the ignition delay is due to higher specific heat and chemical properties of CO2.High concentration of CO2 results in the increase in the amount of heat absorption in the chemistry reaction,especially(R99)reaction(OH+CO=CO2+H),which is an exothermic reaction in X case but an endothermic reaction in CO2 case.Meanwhile,high concentration of CO2 may accelerate(R120)(CO2+OH=HO2+CO)and(R152)(CH2(s)+CO2=CH2+CO2)reactions,thus causing more heat absorption.Higher specific heat and higher thermal radiation of CO2 play important roles in ignition delay in heterogeneous ignition of pulverized coal in O2/CO2 atmosphere,while the chemical property of CO2 shows little effect.%许多研究者发现煤粉在O2/CO2气氛下相较O2/N2会出现明显的着火延迟，并认为这主要是由于CO2较高的比热容引起的。通过定义不同的人工物质 X，Y，W 详细计算分析了 CO2的化学属性、比热容以及辐射特性在均相着火及非均相着火机理下对于着火延迟的影响。结果表明，在均相着火中，CO2的化学属性和较高比热容对于煤粉着火延迟起重要作用，其中化学属性的影响主要是由于大量 CO2的存在导致了反应(R99)(OH＋CO＝CO2＋H)在CO2气氛下出现逆转，在 X 气氛下为放热反应，而在 CO2气氛下为吸热反应。同时，大量的 CO2会促进反应(R120)(CO2＋OH＝HO2＋CO)及反应(R152)(CH2(s)＋CO2＝CH2＋CO2)等反应加快，进而使得化学反应吸热增多。在非均相着火中，CO2的较高比热容以及辐射特性对于着火延迟起决定性作用，CO2的化学属性对于着火延迟几乎没有影响。