Chemical Effects of H2O on Heat Release Characteristic and NO Generation Pathway in Syngas Flames
Using the Chemkin software,the chemical effects of H2O on the premixed flame temperature,heat release characteristics,and NO production pathways for syngas with different hydrogen contents(i.e.,H2/CO volume ratio=10∶90 and 50∶50)are investigated.The results show that although H2O has a larger specific heat compared to N2,it can directly participate in the chemical reactions,promote the generation of OH and HO2 radicals,and enhance the heat release rate of the reactions,such as H+O2+H2O=HO2+H2O,H+HO2=2OH,OH+CO=H+CO2,and OH+H2=H+H2O,which results in the chemical effect of H2O being able to enhance the syngas flame temperature,and the enhancement effect on the flame temperature is more pronounced for the low-hydrogen syngas.Regardless of the H2/CO ratio,the chemical effect of H2O promotes the thermal-NO production and suppresses the con-tribution of the NNH pathway to NO production;the chemical effect of H2O promotes the N2O pathway to NO production in the syngas flame with high hydrogen contents(H2/CO=50∶50)but suppresses the conversion of N2O to NO in the syngas flame with low hydrogen contents(H2/CO=10∶90).
syngasflame temperatureH2O chemical effectheat release characteristicNO generation pathway
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