A Parametric Study Method of Enhancing the Efficiency of Gas Turbine Combined Cycle Power Plant

At the present time, with the ever-increasing energy price, gas steam combined-cycle power plant is well received and favored by Chinese local investors due to its quickly-start and stop, high operational flexibility, high thermal efficiency, clean exhaust flue gas, short construction period characteristics. Recent researches make many efforts on the optimization of gas turbine intake system, main equipment parameters matching, and cold side of steam turbine to increase the overall performance of combined cycle. In the paper, we focused on a kind of triple-pressure reheat combined cycle equipped with a state of the art gas turbine, which is gradually entering Chinese market. An accurate overall combined cycle model was built up for the purpose of increasing the efficiency by means of steam parameters optimization. The influence of steam pressures and temperatures of each sections, feed-water regenerative heating and fuel preheating on combined cycle performance are evaluated with the model, the restriction factors such as temperature difference of heat recovery steam generator (HRSG) and steam turbine structure design were also considered. A set of optimum parameters are obtained for combined cycle equipped with a state of the art gas turbine by using the proposed method on enhancing combined cycle performance equipped with a certain type of gas turbine.