A new type of a gas–steam turbine cycle with increased efficiency

A new system with a gas–steam turbine particularly effective for district heating systems is proposed. Compared to the existing combined installations, including a gas turbine, a waste heat utilization and a steam turbine, it shows significantly lower capital cost and an increase of the thermodynamic efficiency. The simultaneous expansion of gas and steam in one turbine, as well as the utilization of the heat of condensation of the waste gases at the installation outlet allows the overall thermodynamic efficiency, calculated on the basis of the lower calorific value, to reach 108.7%.