| China pays more attention to high efficiency and low pollution gas-steam combined cycle power plants(CCPP) step by step, since the requirements of energy saving and environment protecting become more and more strict in recent years,.In the Chinese ―thirteenth five‖ plan, gas-steam CCPP construction will be a important project, and gas-steam CCPP will develop quickly due to its advantage of friendly environment and high efficiency. CCPP can satisfy the requirements of the distributed energy combined-cooling heating and power(DE-CHP) system with the short installation period and flexible load adjustment and which have wider developmental space. So there is important society and economy meaning to research enetgy saving and system optimizing of gas-steam CCPP.The exhaust parameters of gas turbine are influenced by the environment temperature, the actual running performance and the combustion adjugement of gas turbine and so on. And the performance of heat recovery steam generator(HRSG) and steam turbine will be degradative with the plant running hours increase. So there are some differences between actual running performance and designed performance of HRSG of combine cycle power station,which influence the steam parameters of HRSG, make the steam parameters can’t match with the features of steam turbine, reduce the output powers of steam turbine.This paper, on the basis of collecting a lot of plant actual running data and mastering the features of HRSG working medium, gave out more accurate fitted formulas of working medium features combining with other’s papers, and analyzed the performances of main components of HRSG combining with actual running and designed data, and established the simulation calculation model of HRSG. In this optimization program, the actual running entrance data of HRSG were energy input, the output power of steam turbine was considered as the objective function, the genetic algorithm was used as optimization method. First, obtaining the optimal running parameters of HRSG at some load points by genetic algorithm. Then, fitting the pressure of every calculated load points. Last, getting the optimal sliding pressure curve. Then, how to adjust the optimal sliding pressure curve was dicussed, at various conditions of gas turbine exhaust parameters, efficiency of steam turbine and the flow capacity of steam turbine.Feed water system is one of the most important part of HRSG. And it is also the main auxiliary energy consumption component in power plants. So in this paper, CCPP feed water system was discussed and analysized from viewpoint of energy saving of power plant, where variable speed pump was proposed upgrating constant speed pump. The study indicates that variable speed operation gets about 30% energy saving rate; and the variable speed operation can meet the pressure requirement of feed water system at a majority of the system loads. Improving the frequency is proposed in case of insufficient pressure water supply.The study indicates that power plants will output more powers after the plants are optimized, which will more possibly meet the national requirements of plant efficiency, energy conservation and emission reduction. And these optimized results will also indicate directions for power station actual operation optimization, which has very important engineering significance. |
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