Numerical Study on the Gas Turbine Combustor Burning Coalor Heavy Residue Oil-derived Gas as Alternative Fuel

摘要

A CFD(Computational Fluid Dynamics) research is conducted for the investigation of the fuel alteration of MBTU(medium-Btu) gas in the IGCC gas turbine combustor which is originally designed with natural gas. The computational analysis method of the gas turbine combustor is constructed by incorporating MBTU gas reaction and fuel NOx models into the CFD scheme of the commercial code, FLUENT, and then it is applied to a small annular-type gas turbine combustion chamber. With the use of the present analysis method, comparisons are made on the flow velocity, the chemical species and the temperature distributions, and on the flame shape and behavior of gas turbine combustors firing natural gas or MBTU gases(coal gas, heavy residue oil gas). Furthermore, the NOx formation characteristics of the combustor are analyzed and compared. The computation results show that the MBTU-gas firing cases give higher flame temperature and longer flame zone than the natural case. Thermal and fuel NOx.emissions from the MBTU-gas firing combustor is more produced due to the higher temperature characteristics in the combustor. Based on the computed analysis results, the present study presents the directions for the redeisgn and the design modification of IGCC gas turbine combustor firing MBTU gas as alternative fuel.