Gas turbine cycle with external combustion chamber for prosumer and distributed energy systems

Abstract

The use of various biofuels, usually of relatively small Lower Heating Value (LHV), afiects the gas turbine eficiency. The present paper shows that applying the proposed air by-pass system of the combustor at the turbine exit causes tan increase of effciency of the turbine cycle increased by a few points. This solution appears very promising also in combined gas/steam turbine power plants. The comparison of a turbine set operating according to an open cycle with partial bypassing of external combustion chamber at the turbine exit (a new solution) and, for comparison, a turbine set operating according to an open cycle with a regenerator. The calculations were carried out for difierent fuels: Gas from biomass gasification (LHV = 4.4 MJ/kg), biogas (LHV = 17.5 MJ/kg) and methane (LHV = 50 MJ/kg). It is demonstrated that analyzed solution enables construction of several kW power microturbines that might be used on a local scale. Such turbines, operated by prosumer's type of organizations may change the eficiency of electricity generation on a country-wide scale evidently contributing to the sustainability of power generation, as well as the economy as a whole.