Steam and gas turbine device comprising a gas turbine unit and a steam turbine unit, wherein the gas turbine unit is partly composed of at least the following: - a gas compressor positioned on a compressor axle, a combustion chamber and a gas turbine positioned on a gas turbine axle; and wherein the steam turbine unit is partly composed of the following: - a closed steam line in which at least the following are accommodated: - a pump; a steam converter (8; 50), which, in operation, is in heat-exchanging contact with the gases coming from the gas turbine; a steam turbine positioned on a steam turbine axle; as well as a condenser and wherein, in operation, the steam turbine drives the gas compressor of the gas turbine unit, wherein the gas turbine unit furthermore comprises at least one heat exchanger which brings the combustible flue gases coming from the combustion chamber into heat-exchanging contact with the gases coming from the gas compressor, characterized in that the gas turbine unit comprises a blow-off valve which is arranged upstream of the gas turbine for blowing off the gases coming from the gas compressor, and wherein the device furthermore comprises an air pre-heater which brings the gases coming from the gas turbine into heat-exchanging contact with the gases coming from the gas compressor. - a gas compressor positioned on a compressor axle, a combustion chamber and a gas turbine positioned on a gas turbine axle; and wherein the steam turbine unit is partly composed of the following: - a closed steam line in which at least the following are accommodated: - a pump; a steam converter (8; 50), which, in operation, is in heat-exchanging contact with the gases coming from the gas turbine; a steam turbine positioned on a steam turbine axle; as well as a condenser and wherein, in operation, the steam turbine drives the gas compressor of the gas turbine unit, wherein the gas turbine unit furthermore comprises at least one heat exchanger which brings the combustible flue gases coming from the combustion chamber into heat-exchanging contact with the gases coming from the gas compressor, characterized in that the gas turbine unit comprises a blow-off valve which is arranged upstream of the gas turbine for blowing off the gases coming from the gas compressor, and wherein the device furthermore comprises an air pre-heater which brings the gases coming from the gas turbine into heat-exchanging contact with the gases coming from the gas compressor. - a closed steam line in which at least the following are accommodated: - a pump; a steam converter (8; 50), which, in operation, is in heat-exchanging contact with the gases coming from the gas turbine; a steam turbine positioned on a steam turbine axle; as well as a condenser and wherein, in operation, the steam turbine drives the gas compressor of the gas turbine unit, wherein the gas turbine unit furthermore comprises at least one heat exchanger which brings the combustible flue gases coming from the combustion chamber into heat-exchanging contact with the gases coming from the gas compressor, characterized in that the gas turbine unit comprises a blow-off valve which is arranged upstream of the gas turbine for blowing off the gases coming from the gas compressor, and wherein the device furthermore comprises an air pre-heater which brings the gases coming from the gas turbine into heat-exchanging contact with the gases coming from the gas compressor.