Supersonic Cooling Technology of Gas Turbine Air

Abstract

For the first time, a technology for cooling the intake air of a gas turbine based on supersonic movement of compressed air is proposed. An increase in the outside air temperature leads to a decrease in the mass flow rate of air, and the efficiency and output power of the gas turbine are reduced. The article analyzes various gas turbine cooling systems, shows their advantages and disadvantages. It is shown that only 37 % of the intake air is spent on combustion, most of it is used to cool the heated parts of the gas turbine, which predetermines a decrease in turbine power at high outside air temperatures. It is noted that gas turbines, along with energy facilities, are increasingly occupying positions in the systems of gas collection, transportation, and gas-lift oil production at offshore fields. Only at the Neft Dashlary and Guneshli fields, developed in the Caspian Sea, 34 gas turbines with a total capacity of 232 MW are operated, which decreases by 32.0 MW at an ambient temperature of 40 °C. A design of a cooler for a specific turbine based on the air-to-air principle with 24 copper tubes with Laval nozzles mounted in the inlet section has been developed. A gas-dynamic calculation of the movement of air compressed in an additionally installed compressor through the tubes has been performed. A decrease in air temperature by 89 °C (from plus 45 °C to minus 44 °C) has been noted, which makes it possible to use this temperature to cool the main air flow sucked in from the environment. The design is free from the disadvantages associated with the use of water, is technologically simple, less capital-intensive, is safer due to the low operating pressure of 3 bar and is easily reconstructed by replacing the nozzles and changing the length and number of cooling tubes. The parasitic power of the proposed technology is 2 times lower than for mechanical air-cooled chillers. The technology is universal and can be used for a gas turbine of any power and under all climatic conditions. Bibl. 13, Fig. 2.