Investigations concerning the influence of selected parameters on the thermodynamic and economic characteristics of a gas-steam heat and power plant

The paper shows the methodology of modeling the thermodynamic characteristics of a heat and power gas-steam plant at various rates of production. In the paper the heat scheme and thermodynamic parameters for standard conditions have been assumed. The thermodynamic parameters of the applied turbines are known, viz. of the gas turbine and extraction-condensation steam turbine, the waste-heat boiler, the deaerator and the condenser. Moreover, the parameters connected with technological factors have been determined, too, i.e. The internal efficiencies of the machines and combustion chamber, the design parameters of the boiler, the cooling and pressure losses. The gas turbine characteristics are determined as a function of ambient temperature. Calculations were carried out for changing service conditions during ambient temperature variations in a one-year scale (-20°C ÷ 28°C) using the commercial program Gate Cycle. Special attention has been devoted to economic calculations. The influence of the energy utilization factor and primary energy savings on of the net present value was studied. Characteristics describing the influence of the investment expenditure, the electricity and heat price, the fuel price and the discount rate on the value of the coefficient net present value are included additionally. The presented analysis is connected with the implementing in Poland the directive 2004/8/WE on the promotion of cogeneration, based on the heat demand on the internal energy market.