ABSTRACT
Gas turbines are steady-flow power machines in which a gas is compressed, heated, and expanded for the purpose of generating power. The basic thermodynamic cycle on which the gas turbine is based is known as the Brayton cycle. Gas turbines are used in electric power generation, propulsion, and compressor and pump drives. Most gas turbines in use today are internal combustion engines and, consequently, require clean fuels to avoid corrosion and erosion of critical turbine components. The only internal combustion, coal-fired gas turbine of current interest is the pressurized fluidized bed (PFB) combustion system. Gas turbines typically involve high-speed gas flows, so appreciable differences exist between the static pressure and temperature and the total pressure and temperature. Gas turbine cycles are usually plotted on temperature–entropy coordinates, entropy being a measurement of energy density. Gas turbine combustors appear to be simple in design, yet they solve several difficult engineering challenges.
