Operation Performances Of Gas-steam Combined Cycle Power Units In The Case Of Dusty Compressor Flow Path

The axial flow compressor is one of the important components of the gas turbine unit,which consumes 50%-60% of the power that the gas turbine unit generate.Therefore,the performance of the compressor will have a direct impact on the operation of the entire unit.Among the many factors that affect the performance of the compressor,the degeneration of the compressor performance caused by the fouling accounted for 70%-85%.Based on the theory of air filter's pressure drop and the actual operation data of the power plant,With the Unit operation time and load change,The pressuer drop change rule of a certain type of air filter are analyzed.Based on the stage-stacking method of compressor,the sub-cooling model of gas turbine,combined with the traditio nal three-pressure reheat waste heat boiler model,the whole working condition model of gas-steam combined cycle unit model is established.According to the actual operation data of the power plant,the stage-stacking model of compressor is modified and co mpared with the actual operation data,which is verified to be feasible..The influence of the decrease of the flow capacity of the compressor on the components of the gas-steam combined cycle is analyzed by the model,and the variation trend of the compres sor characteristics is obtained.After the washing,Compressor efficiency and pressure ratio decreased with the running time of the unit.Under the performance assessment benchmark of the power plant when the IGV = 100%,the efficiency and the power of gas turbine decrease faster than the combined cycle's,when the unit is running 800 h,the gas turbine relative efficiency and relative power are respectively decrease 6.38% and 5.5%,relative efficiency and relative power of combined cycle units were 4.72% and 3.6%,the effect of compressor fouling on the downstream of waste heat boiler and steam turbine the relatively can be ignored,which slow down the adverse effect of decreasing of the compressor through flow capacity to combined cycle unit..meanwhile,it is proposed that the unit output loss caused by the decrease of the flow capacity of the compressor can be adjusted by adjusting the IGV.For example,when the unit is running 200 h,IGV=90%,the combined cycle output is only 98.4%.that can not meet the requirements of the dispatch center,Therefore,by adjusting the IGV opening makes it 93.01% to achieve the desired output.Under the condition of power plant unit performance conversion,According to the experience of compressor washing cycle in power plant,the off-line washing period is 695 h.Considering the various costs of unit output and fuel consumption during the whole washing cycle,the running cost of the power plant is calculated,and the optimum washing period is 236 h.At the same time price,fuel price,and stop washing time effect on the optimal washing cycle is discussed,when the electricity price rise,fuel prices drop and shorten the time of stopping washing will extend the best off-line washing cycle.