Investigation On Modeling And System Performance Analysis Of Gas Turbine Cycles

IGCC (Integrated Gasification Combined Cycle) technology, considered as a feasible solution to reducing pollution and improving efficiency of burning-coal power industry, arouses extensive concern from energy utilization fields. Because the domestic heavy-duty gas turbine technology exist a large gap with foreign, the heavy-duty gas turbines adopted in China are retrofitted from the standard gas turbine burning natural gas, produced by foreign large companies (such as GE, Siemens, Mitsubishi). A series of research will be carried out on IGCC system performance analysis, flow capability evaluation and surge margin resetting when standard gas turbine retrofitted for burning syngas efficiently and clearly.Based on the above-mentioned background, the main research contents are as follows:1. In this paper, numerical simulation is applied to establish several types of gas turbine system performance analysis models and verify performance of the models: firstly, the PG6561B model and certain E-class heavy-duty gas turbine model are established, and the performance of design models are verified; secondly, certain F-class heavy-duty gas turbine model is established and performance of the combined-cycle power plant with this gas turbine is verified; finally, for integrity of the models, some Auxiliary Power Unit(APU) model, micro gas turbine model, is established, the start-up performance in the plateau of APU is verified.2. For PG6561B, certain E-class and F-class heavy-duty gas turbine, the off-design models retrofitted for burning medium/low-heating-value syngas are established in different cases and more detailed performance analysis and comparisons of the gas turbine models are carried out. Base on the modified F-class heavy-duty gas turbine model, the control strategy at a variety of ambient temperature has been bringing forward; For APU, the off-design models is established and high-speed performance at high-altitude is simulated and analyzed in detail, the design parameter is provided for its improving.Some primary conclusions can be drawn from the modeling of different gas turbines and the numerical simulation results of different retrofitting schemes and working conditions:1. The results of PG6561B model performance analysis and simulation indicate: lack of compressor map and turbine blade cooling data, the system performance, predicted by off-design model of gas turbine, is inaccurate.2. The results of the E-class heavy-duty gas turbine models system performance simulation indicate: when the standard gas turbine is retrofitted for burning syngas, the efficiency of gas turbine is the highest by use of enlarging the first-stage throat area of turbine, as well as decreasing the exit temperature of combustor; if the stall margin of compressor is enough, the efficiency and output of gas turbine could through method of increasing the pressure ratio of compressor. The efficiency of gas turbine will hold higher level by way of regulating the angle of inlet guide vane (IGV) as well as blowing off air from compressor or decreasing the exit temperature of combustor.3. The results of the F-class heavy-duty gas turbine models performance simulation and control strategy analysis indicate: According to the performance simulation at a variety of ambient temperatures from -25℃to 35℃, the control strategy has been bringing forward on the modified gas turbine. With the fall of the ambient temperature, it will reach turbine output limitation point, regulating the angle of inlet guide vane to reduce the cross passage, the gas turbine will work safely. With the rise of the ambient temperature, it will reach the compressor surge protection point. Blowing off a little air from some intermediate stage of compressor, the compressor surge margin will increase while the thermal efficiency of gas turbine will keep high level.4. The results of the APU micro gas turbine models performance simulation indicate: the gas turbine could not meet the requirement of performance in the plateau and high-speed performance at high-altitude. The re-design of the induced compressor is suggested: pressure ratio should be increased about 14%, mass flow should be increased about 5%.In conclusion, this paper describes various of gas turbine models established by numerical simulation, which could exactly predict the performance in all operating states in some extent, and accumulates some experience on gas turbine retrofit and control strategy.