PARAMETRIC ANALYSIS OF A GAS-STEAM PLANT SCHEME USING A MATHEMATICAL MODEL

The relevance of the topic is caused by the need for a complex of scientific research on the development and optimization of thermal circuits and calculation methods for gas-steam installations. Gas-steam plants are a promising direction for increasing the efficiency of power plants based on gas turbine engines with environmental and energy injection of water vapor into the combustion chamber. The main aim of the research is to improve the calculation methodology of gas turbine units with steam injection for the study of issues of increasing the efficiency of electric and thermal energy generation in order to reduce natural gas consumption, as well as to improve thermal schemes and optimize the parameters of gas-steam installations. Objects: combined gas-steam installations based on gas turbine installations with steam injection into the combustion chamber. Methods: numerical methods of research by mathematical modeling of systems and elements of gas-steam installations based on material and energy balances. Results. A mathematical model has been developed for calculating the energy characteristics of a gas-steam installation, taking into account changes in input parameters in a wide range. The influence of the gas temperature at the outlet of the combustion chamber and the compression ratio in the compressor on the main energy characteristics of a gas turbine installation without steam injection and with injection into the combustion chamber is analyzed. It is shown that steam injection can increase the efficiency of a gas turbine installation by up to 9 %, while the consumption of injected steam is significantly reduced with an increase in the temperature of the gases at the outlet of the combustion chamber and the compression ratio in the compressor. Also, steam injection significantly reduces the excess air coefficient in the combustion chamber and the temperature of the gases leaving the waste boiler. At the same time, the specific power of electricity generation increases by about 1,5...2,0 times compared to a gas turbine installation without injection. It is established that the need to ensure temperature pressures in the heat recovery boiler significantly limits the range of operating modes of the gas-steam plant in terms of the compression ratio in the compressor.