METHOD OF OPERATING A WASTE-HEAT STEAM GENERATOR, AND A WASTE-HEAT STEAM GENERATOR OPERATED BY THIS METHOD

摘要

The invention concerns a waste-heat steam generator (1), intended for a combined gas- and steam-turbine installation (2), in which the heat contained in the expanded exhaust gases (AG) from the gas turbine (2a) is used to generate steam for the steam turbine (2b) connected in a water/steam circuit (3), the condensed steam from the steam turbine (2b) being fed back as condensate (K) to the water/steam circuit (3). In order to ensure high efficiency irrespective of the type of fuel (B, B') used in the gas turbine (2a), the invention calls, when oil is used as the gas-turbine fuel (B), for the same part (t1) of the flow in the water/steam circuit (3) to be utilized to preheat the condensate as is utilized to pre-heat the gas-turbine fuel (B) when gas is used as the fuel. In addition, a heat-exchanger (56) is fitted for preheating, as required, either the gas-turbine fuel (B) or the condensate (K) by means of part (t1) of the flow in the water/steam circuit.