Variable Condition Calculation And Optimization Research On Bottoming Cycle Of Gas-steam Combined Cycle

Since the implementation of reform and opening up policy in China, it is a long-term strategic task to develop energy industry prior. Because of the power and thermal efficiency of gas turbine has improved, especially the gas-steam combined cycle technology mature gradually, the status of gas turbine and combined cycle have changed dramatically in world power industry. Combined cycle power plants can not only save the increasingly tense energy reserves, but also protect the environment effectively, which conforms to the sustainable development strategy. It is important to increase the investment of gas-steam combined cycle and realize the system running efficiently.In this paper, we research on the model of a domestic gas turbine, according to the exhaust parameters of this gas turbine our team provide suitable flowsheet structures for steam bottoming cycle. The main research contents precise calculation of part load performance parameters and optimization analysis based on thermodynamics of the bottoming cycle.First of all, the research status of off-design performance and optimization of gas-steam combined cycle at home and abroad is introduced, and analyze the meaning of the calculation of part load performance parameters and optimization in gas-steam combined cycle. The off-design calculation algorithm was implemented in Fortran language, and the off-design performance parameters of five different bottoming cycles(single pressure cycle, dual pressure cycle, dual pressure reheat cycle, triple pressure cycle, triple pressure reheat cycle) were calculated. The calculated results were compared with the parameters that were calculated by the combined cycle simulation software GateCycle, in order to make sure that the calculation method converges faster and calculates accurately.On this basis, using the dual pressure without reheat system as an example, based on the first law of thermodynamics, the effects of parameters on the bottoming cycle performance and the constraints that should be paid attention to in the operation were analyzed, with the goal of maximizing the efficiency of the bottoming cycle through the comprehensive optimization of multiple parameters. Further more, the paper analyzed the different optimization results under different objective function based on the second law of thermodynamics, Selected the appropriate objective function to describe the system performance, compared the optimization result of this type of gas turbine with the optimization results of other two different types in the same objective function, the influence of gas turbine exhaust parameters on the performance optimization in bottoming cycle was achieved.