ES356088A1 - Co2 circuit with partial condensation for gas turbines. (Machine-translation by Google Translate, not legally binding) - Google Patents

Abstract

A gas turbine plant of the closed circuit type and using C0 2 as the working fluid comprises at least two compression stages with an inter-stage cooler therebetween, at least two turbine expansion stages with inter-stage reheat therebetween, the heat being supplied from an external source. Means are provided for liquefying part of the working fluid at an intermediate pressure, the circuit being so arranged that the liquefied part and the gaseous part of the CO 2 flow in the circuit are pressurized together. In Fig. 1 the plant comprises an LP compressor 1 which is driven by an LP turbine 9 through shaft 16, the LP turbine also driving a useful load shown as an electric generator 15, an IP compressor 3 and an HP compressor 13 which are driven by an HP turbine 7 through shaft 17, and a heat source in the form of a nuclear reactor 8. Gaseous C0 2 is compressed in compressor 1, cooled in inter-stage cooler 2 and further compressed in IP compressor 3. The gaseous C0 2 is then passed through pre-cooler 11 and cooler 12 where it is partially liquefied, the mixture of liquid C0 2 ' and gaseous C0 2 then passing together to the HP compressor 13 where they are further compressed possibly to critical pressure so that gaseous C0 2 discharges from the compressor. The gaseous C0 2 is then heated in heat exchanger 14 and further heated in heat exchanger 6 by the gaseous CO 2 discharging from the LP turbine 9. The heated C0 2 gas then passes to the HP turbine 7, through the reactor 8 where it is reheated, then to the LP turbine 9. The CO 2 gas discharging from the turbine 9 passes through the heat exchangers 6 and 14 and then through the precooler 10, finally passing back to the LP compressor 1. In Fig. 2 the gaseous C0 2 discharging from the IP compressor 3 is divided into two streams, one stream passing to the pre-cooler 11 and condenser 12 where it is liquefied, the liquid C0 2 then re-uniting with the gaseous C0 2 steam which passed directly through the line 95, the mixture of gaseous CO 2 and liquid C0 2 passing to the HP compressor 13 as in the first embodiment. The gas flow through line 95 is controlled by a valve 96 in dependence on temperature of the liquid C0 2 as sensed at the point 97a. A part of the gaseous C0 2 from the heater 6 may pass under control of valve 29a to a high pressure section 8a of the nuclear reactor, the gas then re-uniting with the C0 2 gas which has passed from the heater 6 through the line under control of valve 29. The C0 2 gas discharging from the HP turbine 7 is reheated in the low pressure section 8b of the nuclear reactor. In Fig.3 the flow of gaseous C0 2 from the IP compressor 3 is again divided into two streams as in Fig.2, the control valve 96 being controlled by a device 99 in response to the flow of liquid CO 2 The mixture of gaseous C0 2 and liquid C0 2 is further compressed in compressor 13 which in this embodiment is driven by the LP turbine 9. The gaseous C0 2 from the compressor 13 is heated in heat exchangers 14 and 6, expanded in HP turbine 7, reheated at 8c and further expanded in LP turbine 9. In this case the heat from the nuclear reactor 8 is transferred to the gaseous C0 2 by an intermediate heat transfer medium such as liquid metal.