Method for recovering waste heat as motive power

A novel method for the recovery of waste heat from a waste gas in the form of motive power in a cycle having a superheater provided on the upstream side and a counterflow heat exchanger on the downstream side respectively in the path of the waste gas to permit efficient recovery of the sensible heat of waste gas, characterized by injecting part of the high-pressure hot water brought to an elevated temperature by the heat absorbed within said counterflow heat exchanger into the circulation steam of the superheater system emanating from the outlet of said superheater thereby cooling the circulation steam into a saturated steam, returning the saturated steam to said superheater via the inlet thereof thereby enabling the saturated steam within said superheater to be converted into a superheated steam by the heat derived through the gas-gas heat exchange from the waste gas within said superheater, supplying a mass flow of the superheated steam equalling the amount of the hot water used for the aforementioned injection as the working steam for the steam turbine system to the steam turbine thereby causing the superheated steam within the steam turbine to be adiabatically expanded to generate motive power, subsequently introducing the expanded steam into the condenser to be condensed therein, introducing the resultant condensed cold water into said counterflow heat exchanger to be converted therein into a high-temperature, high-pressure hot water by the heat derived through the gas-liquid heat exchange from the waste gas within the heat exchanger, supplying the portion of the hot water remaining after deduction of the portion for use in the aforementioned cooling of the circulation steam to the hot water turbine to be adiabatically expanded therein to generate motive power, subsequently introducing the expanded hot water (wet steam) into the condenser to be condensed therein, and thereafter repeating the same heat cycles as described above sequentially one after another.