THERMAL POWER STATION AND METHOD FOR GENERATING ELECTRIC POWER IN A THERMAL POWER STATION

Abstract

A thermal power station and method for generating includes (a) at least one thermal energy storage having a housing, a storage chamber and a fluid inlet port fluidically connected to the storage chamber and a fluid outlet port connected to the storage chamber, and (b) a Brayton cycle heat engine including gas turbine, a cooler and a compressor connected with each other by a closed cycle containing a second working fluid, (c) the Brayton cycle heat engine further includes a control unit arranged for operating the Brayton cycle heat engine according to a Brayton cycle, (d) the gas turbine is thermally coupled to the at least one thermal energy storage by a first heat exchanger and a first working fluid, the first working fluid being different, and (e) the gas turbine is connected to a generator for producing electrical power by the thermal energy from the thermal energy storage.

Claims

1. A thermal power station comprising (a) at least one thermal energy storage having a housing, a storage chamber with heat storage material inside the storage chamber and a fluid inlet port fluidically connected to the storage chamber and a fluid outlet port fluidically connected to the storage chamber, and (b) a Brayton cycle heat engine comprising a gas turbine, a cooler and a compressor connected with each other by means of a closed cycle containing a second working fluid, whereby (c) the Brayton cycle heat engine further comprises a control unit arranged for operating the Brayton cycle heat engine according to a Brayton cycle, (d) the gas turbine is thermally coupled to the at least one thermal energy storage by means of a first heat exchanger and a first working fluid, the first working fluid being different from the second working fluid, and (e) the gas turbine is connected to a generator for producing electrical power by means of the thermal energy from the thermal energy storage.

2. The thermal power station according to claim 1, wherein, the fluid inlet port is connected to a diffusor section of the thermal energy storage and/or the fluid outlet port is connected to a nozzle section of the thermal energy storage.

3. The thermal power station according to claim 2, wherein, the diffusor section and/or the nozzle section are formed by the housing.

4. The thermal power station according to claim 1, wherein the heat storage material consists of magmatic rock.

5. The thermal power station according to claim 1, wherein, the thermal energy storage comprises at least two fluid inlet ports and/or at least two fluid outlet ports.

6. The thermal power station according to claim 1, wherein, the thermal energy storage is provided with at least one electric heater.

7. The thermal power station according to claim 1, wherein the first working fluid is air and the second working fluid is CO.sub.2.

8. The thermal power station according to claim 1, wherein, the second working fluid is transcritical or supercritical in the Brayton cycle.

9. The thermal power station according to claim 1, wherein, the control unit is arranged to control the Brayton cycle heat engine in a way such that the second working fluid at the gas turbine is provided with a temperature of at least T=700° C., whereby the second working fluid is CO.sub.2, in particular transcritical or supercritical CO.sub.2.

10. The thermal power station according to claim 1, wherein the Brayton cycle heat engine further comprises a second heat exchanger arranged between the turbine and the cooler in the closed cycle to heat the second working fluid after passing through the cooler by means of residual heat in the second working fluid after passing through the gas turbine.

11. The thermal power station according to claim 10, wherein the Brayton cycle heat engine comprises at least two second heat exchangers and at least two compressors of the at least one compressor, whereby they are arranged such that the second working fluid after passing through the cooler is alternatingly compressed by means of one of the at least two compressors and heated by means of one of the at least two second heat exchangers.

12. The thermal power station according to claim 1, wherein the thermal power station further comprises a Rankine cycle heat engine having a steam turbine or a further Brayton cycle heat engine being thermally coupled with the Brayton cycle heat engine such that they form a combined cycle.

13. The thermal power station according to claim 1, wherein the at least one thermal energy storage is connected to a renewable energy source.

14. A method for generating electric power in the thermal power station according to claim 1, whereby the method comprises the steps of: (a) heating the first working fluid in a charging mode, so that a heated charging mode first working fluid is obtained, (b) transporting the heated charging mode first working fluid to the fluid inlet port of the thermal energy storage, whereby thermal energy from the heated charging mode first working fluid is transferred to the heat storage material of the storage chamber, so that thermal energy is stored in the heat storage material, (c) transporting discharging mode first working fluid of a discharging mode to the fluid inlet port of the thermal energy storage, whereby the stored thermal energy from the heat storage material of the storage chamber is transferred to the discharging mode first working fluid, so that a heated discharging mode first working fluid is obtained, which exits the fluid outlet port of the thermal energy storage and the heat from the heated discharging mode first working fluid is transferred to the second working fluid by means of the first heat exchanger, and (d) producing electric power in the generator by means of driving the gas turbine with the second working fluid.

15. The method for generating electric power in the thermal power station according to claim 14, wherein, the second working fluid flows through the closed cycle according to the Brayton cycle.

Description

BRIEF DESCRIPTION

[0040] Some of the embodiments will be described in detail, with reference to the following figures, wherein like designations denote like members, wherein:

[0041] FIG. 1 a sectional cut through a thermal energy storage as can be used in a thermal power station according to the invention; and

[0042] FIG. 2 a circuit diagram of a thermal power station according to an embodiment of the invention.

DETAILED DESCRIPTION

[0043] FIG. 1 shows a sectional cut through a thermal energy storage 10 as can be used in a thermal power station 1 (see FIG. 2) according to embodiments of the invention.

[0044] The thermal energy storage 10 comprises a housing 11, in which a storage chamber 12 filled with heat storage material 13 is located. A first working fluid A (see FIG. 2) may enter a fluid inlet port 14 of the housing 11 in the direction indicated by an arrow. The fluid inlet port 14 is connected to a diffusor section 15. The fluid inlet port 14 and the diffusor section 15 are formed by the housing 11. Further, the first working fluid A may exit the housing 11 in the direction indicated by a further arrow through a fluid outlet port 16. The fluid outlet port 16 is connected to a nozzle section 17. The fluid outlet port 16 and the nozzle section 17 are formed by the housing 11.

[0045] FIG. 2 shows a circuit diagram of a thermal power station 1 according to an embodiment of the invention.

[0046] The thermal power station 1 comprises the thermal energy storage 10 and the Brayton cycle heat engine 20 coupled thermally with each other by means of the first heat exchanger 25.

[0047] A first working fluid A flows through a pipe taking in the heat from the thermal energy storage 10 and through the first heat exchanger 25, thereby transporting the heat from the thermal energy storage 10 to the first heat exchanger 25. For this purpose, a pipe from the first heat exchanger 25 is fluidically connected to the fluid inlet port 14 of the thermal energy storage 10 and a further pipe from the first heat exchanger 25 is fluidically connected to the fluid outlet port 16 of the thermal energy storage 10. In this particular embodiment, the first working fluid A may be air, for example.

[0048] A second working fluid B flows within a closed cycle 26 of the Brayton cycle heat engine 20 having several pipes 26.1, 26.2, 26.3, 26.4, 26.5, 26.6, 26.7, 26.8, 26.9, 26.10 and through the first heat exchanger 25. Thereby, the heat from the first working fluid A is exchanged with the second working fluid B being in a compressed state, whereby the second working fluid B becomes heated. The second working fluid B is supercritical CO.sub.2 in this particular embodiment. The heating of the second working fluid B is a second step within the closed Brayton cycle of the Brayton cycle heat engine 20.

[0049] The second working fluid B is transported by means of the pipe 26.1 of the closed cycle 26 to a gas turbine 21 of the Brayton cycle heat engine 20. In the gas turbine 21, the second working fluid B being in the compressed state is expanded. This is a third step within the closed Brayton cycle. The gas turbine 21 is connected to a generator 30, whereby the gas turbine 21 by means of expanding the compressed and heated second working fluid B drives the generator 30, which in turn produces electric power.

[0050] The second working fluid B in the expanded state still has residual heat. Therefore, the second working fluid B passes through two second heat exchangers 22.1, 22.2 by means of the pipes 26.2, 26.3 of the closed cycle 26.

[0051] After the two second heat exchangers 22.1, 22.2, which are arranged in series, the second working fluid B is relatively cold and is further cooled in cooler 23 to which it is passed through by means of pipe 26.4. This is a fourth step of the Brayton cycle.

[0052] In the first step of the Brayton cycle, the cold second working fluid B is compressed by means of two compressors 24.1, 24.2 of the Brayton cycle heat engine 20 being arranged in series. For this purpose, a pipe 26.5 connects the cooler 23 with the compressor 24.1 and a pipe 26.7 connects the second heat exchanger 22.2 with the compressor 24.2. Thereby, the second working fluid B is passed before and after the cooler 23 to different compressors 24.1, 24.2, in which it is compressed. Thereby, the same compression of the second working fluid B may be achieved in every one of the two compressors 24.1, 24.2.

[0053] However, before passing through the first heat exchanger 25, the second working fluid B from pipe 26.6 coming from the compressor 24.1 is heated by means of the second heat exchanger 22.2 and by means of the second heat exchanger 22.1 and the second working fluid B from pipe 26.8 coming from the compressor 24.2 is heated by means of the second heat exchanger 22.1. Thereby a type of two-stage-preheating is provided. In pipe 26.9 arranged between the second heat exchangers 22.1, 22.2, the second working fluid B coming from the different compressors 24.1, 24.2 is mixed together. The preheated and compressed second working fluid B then passes through pipe 26.10 and to the first heat exchanger 25, where the second working fluid B once again undergoes the second step of the closed Brayton cycle.

[0054] Although the present invention has been disclosed in the form of preferred embodiments and variations thereon, it will be understood that numerous additional modifications and variations could be made thereto without departing from the scope of the invention.

[0055] For the sake of clarity, it is to be understood that the use of “a” or “an” throughout this application does not exclude a plurality, and “comprising” does not exclude other steps or elements.