Combustion of syngas with humid air is important for integrated coal gasification humid air turbine cycle for power generation. In contrast to hydrocarbon fuels, CO exists in bulky content in syngas. Thus the influence of air humidity on the oxidation of CO in syngas flames should be well understood. In the present study, the influence of air humidity on CO oxidation in syngas diffusion flames was investigated both experimentally and numerically. In the experiment, CO, CO2, O2 and temperature profiles in a model combustor of a syngas turbulent jet diffusion flame were measured. It was found that as the mass flow rate of dry air and the exhaust temperature kept constant, the profile of CO was influenced by air humidity, but CO exhaust did not exhibit a monotone increase over humidity. There exist an inflexion at the case of absolute humidity of the air X = 6.0. In addition, CO emission decreases with the increase of the thermal load. And the influence of the humidity on CO oxidation was not obviously when the thermal load is high. In the numerical simulation, flow field in the combustor was calculated by applying the composition PDF transport model and Flamelet model respectively. The numerical results were compared with the experiment and the PDF model was verified that it is more suited to simulate the CO oxidation. From the numerical analysis, it was found that the concentration of OH wasn’t monotonously increased with the added H2O and this directly affect the oxidation of CO via CO + OH → CO2 + H. In general, the influence of air humidity on the oxidation of CO in syngas diffusion flames depends on the coupling and competition of chemistry and fluid mechanics aspects. This helps to interpret the discrepancy of the results of gas turbine combustor test.

This content is only available via PDF.
You do not currently have access to this content.