THE EFFECTS OF FUEL DILUTION WITH STEAM ON GAS TURBINE COMBUSTOR PERFORMANCE

摘要

The formation of nitrogen oxides (NO_x) in combustion systems is a significant pollutant source in the environment, and How to control NO_x emission is a worldwide concern as the utilization of fossil fuels continues to increase. Syngas is produced from variety of fossil fuels through a gasification process. Though syngas is regarded as one kind of clean fuel, its NO_X emission control techniques in combustion systems still remain many problems for further development. Steam dilution of fuel is an effective method for NO_x reduction in practical gas turbine systems. This paper describes the study focusing on the influence about steam dilution of fuel for reducing the NO_x emission. Experimental investigations are conducted on a 40MW gas turbine fired with syngas. The pollutant emissions, combustor dynamic pressure, metal temperature distribution of liner and combustion efficiency are analyzed at the base load of gas turbine with different steam injection rate to fuel flow. Three-dimensional CFD numerical simulation of combustor according to experiment parameters is applied to investigate the influence of steam dilution on NO_x emission and the combustion liner wall temperature. Comparisons are made between experiment data and CFD simulation results for further understandings about NO_x formation characteristics in steam diluted syngas and its influence to gas turbine combustion system. The investigation of this paper's work shows tha steam dilution is an effective method of NO_x emission control technique in practical gas turbine combustion systems fired with syngas. The CFD simulation results show that steam in flame can remarkably reduce temperature of the flame for its high thermal capacity and it can remarkably reduce formation of NO_x in gas turbine combustor. Moreover, as the steam flowrate added to fuel increase the wall temperature of some zone of liner may increase because of the convection heat transfer is strengthened and the combustion oscillation will be weaken.