Parameter Optimization And Performance Analysis On Large-scale Combined-cycle Cogeneration Systems

With economy quick and continued development, the adjustment ofenergy sources structure and the stricter request of environment protection,more of cogeneration of heat and power (CHP) projects with large-scale gasturbine (GT) will be built in China. Furthermore, the manufacturing techniqueof large-scale GT introduced into China is digesting, absorbing anddeveloping. Therefore we need research the parameter optimization andperformance analysis for combined cycle (CC) cogeneration with large-scaleGT.PG9171 (E) and PG9351 (FA), two kinds of gas turbine model producedby GE company, are taken as cases for research. These CC systems with heatrecovery steam generator (HRSG) of two-pressure, two-pressure and reheat,three-pressure, three-pressure and reheat models are built with GateCylesoftware. These steam pressure parameters of condensing and backpressuresteam turbine are optimized by the net income objective function of systems.Some important parameters for systems, such as high pressure and heatexchange area of HRSG, are analyzed. And the applied range of extractionfeed-water heating for improving the system efficiency is also discussed inthe paper. Based on different environment temperature, Figures of operatingcharacteristics curves for these representative configurations of S109FA andS109E are provided to show their heat and power operating ranges. Thesefigures are helpful for choosing GT models and system configurations in CHPprojects.Based on the concept of "Lost Kilowatts", the net income affected by therelation between heat supply increasing and power supply decreasing in CHPsystem is analyzed. The economical balance point is found and a reasonableprice assignment method is proposed to protect the benefit of CHP plant.Through study of the income of CHP based on fixed and timesharing electricprice, main factors contributing to the income are analyzed. Three poweradjustment policies are proposed to admit in different electric price level.When electric pricing based on time, the CHP participating in peak poweradjustment will bring in more income. And its power adjustment policy hassome new characteristics.