High-temperature energy store with recuperator

Abstract

A charging circuit for converting electrical energy into thermal energy is provided, having a compression stage, connected via a shaft to an electric motor, a heat exchanger and an expansion stage, which is connected via a shaft to a generator, wherein the compression stage is connected to the expansion stage via a hot-gas line, and the heat exchanger is connected on the primary side into the hot-gas line, wherein the expansion stage is connected via a return line to the compression stage, so that a closed circuit for a working gas is formed. A recuperator is also provided which, on the primary side, is connected into the hot-gas line between the heat exchanger and the expansion stage and, on the secondary side, is connected into the return line, so that heat from the working gas in the hot-gas line can be transferred to the working gas in the return line.

Claims

1. A system comprising a charging circuit for converting electric energy into thermal energy, the charging circuit comprising: a compression stage, which is connected via a motor shaft to an electric motor, a Heat exchanger and an expansion stage, which is connected via a charging circuit generator shaft to a charging circuit generator, wherein the compression stage is connected to the expansion stage via a hot gas line, and the heat exchanger is connected on the primary side into the hot gas line, and wherein the expansion stage is connected to the compression stage via a return line so that a closed circuit for a working gas is formed, and a recuperator which is connected on the primary side into the hot gas line between the heat exchanger and the expansion stage and connected on the secondary side into the return line so that heat of the working gas in the hot gas line can be transferred to the working gas in the return line, the system further comprising a discharging circuit that is discrete from the charging circuit and which comprises: a thermal store that receives heat from the charging circuit; a medium that receives heat from the thermal store; and a discrete energy extractor that extracts the received heat from the medium, wherein the thermal store receives the heat from the working gas in the charging circuit, and wherein the heat exchanger is configured such that a pressure of the working gas is reduced when delivering the heat to the thermal store.

2. The system as claimed in claim 1, the charging circuit further comprising an ambient air heat exchanger connected into the return line, by means of which the working gas which is conducted in the return line can be heated to outside temperature.

3. The system as claimed in claim 1, wherein a secondary side of the heat exchanger is connected to a primary side of the thermal store via a gas line so that the heat from the charging circuit can be transferred from the charging circuit via the heat exchanger indirectly into the thermal store.

4. The system as claimed in claim 1, wherein the thermal store comprises the heat exchanger so that the working gas flows from the charging circuit through the thermal store, and consequently the heat from the working gas can be transferred directly to the thermal store.

5. The system as claimed in claim 4, wherein the discrete energy extractor comprises a steam turbine, wherein the discharging circuit further comprises a steam generator, a discharging circuit generator, and a condenser, wherein the steam turbine is connected via a discharging circuit generator shaft to the discharging circuit generator, and wherein the steam generator, the steam turbine and the condenser are connected into a water-steam cycle, and wherein a primary side of the steam generator is connected via a steam line to a secondary side of the thermal store.

6. The system as claimed in claim 4, wherein the discrete energy extractor comprises a steam turbine, wherein the discharging circuit further comprises a steam generator, a discharging circuit generator and a condenser, wherein the steam turbine is connected via a discharging circuit generator shaft to the discharging circuit generator, and wherein the steam generator, the steam turbine and the condenser are connected into a water-steam cycle, and wherein the steam generator is the thermal store so that by introducing water steam can be generated directly in the thermal store.

7. The system as claimed in claim 1, the charging circuit further comprising an electric auxiliary heater connected into the hot gas line upstream of the thermal store.

8. The system as claimed in claim 1, wherein the compression stage and the expansion stage are interconnected via a charging circuit interconnecting shaft.

9. The system as claimed in claim 1, wherein the compression stage comprises a plurality of compressor stages and a respective heat exchanger is connected downstream to each compressor stage in each case so that a first heat exchanger is connected downstream to at least a first compressor stage and a second heat exchanger is connected downstream to a second compressor stage.

10. The system as claimed in claim 1, wherein the expansion stage comprises a plurality of expansion stages and a respective ambient air heat exchanger is connected downstream to each expansion stage so that a first ambient air heat exchanger is connected downstream to at least a first expander stage and a second ambient air heat exchanger is connected downstream to a second expander stage.

11. The system as claimed in claim 1, wherein the system is used in a power plant, which is operated with renewable energy, for storing seasonal electric surplus energy.

12. The system as claimed in claim 1, wherein the thermal store contains a porous storage medium, sand, clay, stones, or concrete.

13. The system as claimed in claim 1, wherein the charging circuit is configured to heat the thermal store to over 350 C.

14. The system as claimed in claim 1, wherein the discharging circuit does not include heat transfer from the medium at one location in the discharging circuit to the medium at another location in the discharging circuit.

15. A method, comprising: a) in a compression process in a charging circuit, compressing a working gas from a temperature T1 and a pressure P1 to a pressure P2 with a temperature T2, b) in a heat exchange process in the charging circuit, transferring heat from the working gas to a thermal store in a discrete discharging circuit, as a result of which temperature and pressure of the working gas are reduced to a temperature T3 and a pressure P3, and c) in an expansion process in the charging circuit, expanding the working gas to a pressure P4 with a temperature T4, and feeding the expanded working gas back again in a return line to the compression process, wherein in the charging circuit heat is extracted from the working gas between the heat exchange process and the expansion process and is transferred to the working gas in the return line, the method further comprising: transferring heat from the thermal store to a medium in the discharging circuit; and extracting the transferred heat from the medium via a discrete energy extractor of the discharging circuit.

16. The method as claimed in claim 15, wherein the heat exchange process comprises a heat exchanger, and the temperature T3 and the pressure P3 are set by dimensions of the heat exchanger.

17. The method as claimed in claim 15, further comprising driving the compression process by electrically seasonally arising surplus energy of a power plant with renewable energies.

18. The method as claimed in claim 15, further comprising using as storage material for the thermal store of the heat exchange process porous materials, sand, clay, stones, concrete, water or saline solution.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 shows an example of a charging circuit for converting electrical energy into thermal energy according to aspects of the invention.

(2) FIGS. 2-3 show examples of a charging circuit as a component part of an energy storage device which has a thermal store and a discharging circuit according to aspects of the invention.

DETAILED DESCRIPTION OF INVENTION

(3) FIG. 1 shows an example of a charging circuit 1 for converting electrical energy into thermal energy, having a compression stage 2, which is connected via a shaft 3 to an electric motor 4, a heat exchanger 5 and an expansion stage 6, which is connected via a shaft 7 to a generator 8, wherein the compression stage 2 is connected to the expansion stage 6 via a hot-gas line 9, and the heat exchanger 5 is connected on the primary side into the hot-gas line 9, wherein the expansion stage 6 is connected via a return line 11 to the compression stage 2, so that a closed circuit 12 for a working gas 13 is formed, wherein, furthermore, a recuperator 18 is provided which, on the primary side, is connected into the hot-gas line 9 between the heat exchanger 5 and the expansion stage 6 and, on the secondary side, is connected into the return line 11, so that heat from the working gas 13 in the hot-gas line 9 can be transferred to the working gas 13 in the return line 11. The charging circuit 1 may be a component part of a heater, wherein the heater is connected on the secondary side into the heat exchanger 5 so that heat can be transferred by means of the heater, via the heat exchanger 5, to a medium which is to be heated.

(4) FIGS. 2-3 show an example of a charging circuit 1 as a component part of an energy storage device 14 which has a thermal store 15 and a discharging circuit 16. An ambient air heat exchanger 20a, 20b may be connected into the return line 11, by means of which the working gas 13 which is conducted in the return line 11 can be heated to outside temperature.

(5) The secondary side of the heat exchanger 5 may be connected to the primary side of the thermal store 15 via a gas line 24 so that heat of the working gas 13 can be transferred from the circuit 12 via the heat exchanger 5 indirectly into the thermal store 15.

(6) The heat exchanger 5 may be the thermal store 15 so that the working gas 13 flows from the circuit 12 through the thermal store 15, and consequently the heat from the working gas 13 can be transferred directly to the thermal store 15.

(7) The discharging circuit 16 may further include a steam generator 30, a steam turbine 31, a generator 32 and a condenser 33, wherein the steam turbine 31 is connected via shaft 34 to the generator 32, and the steam generator 30, the steam turbine 31 and the condenser 33 are connected into a water-steam cycle 35, wherein the primary side of the steam generator 30 is connected via a steam line 25 to the secondary side of the thermal store 15.

(8) The steam generator 30 may be the thermal store 15 so that by introducing water steam can be generated directly in the thermal store 15.

(9) In a further embodiment, an electric auxiliary heater 21 may be connected into the hot gas line 9 upstream of the thermal store 15. Moreover, the compression stage 2 and the expansion stage 6 may be interconnected via a shaft 22.

(10) In still further embodiments, the compression stage 2 may have a plurality of compressor stages and a heat exchanger 5 is connected downstream to each compressor stage in each case so that a first heat exchanger 5a is connected downstream to at least a first compressor stage 2a and a second heat exchanger 5b is connected downstream to a second compressor stage 2b. The expansion stage 6 may further include a plurality of expansion stages and an ambient air heat exchanger 20a, 20b is connected downstream to each expansion stage so that a first ambient air heat exchanger 20a is connected downstream to at least a first expander stage 6a and a second ambient air heat exchanger 20b is connected downstream to a second expander stage 6b.

(11) As a method, an embodiment herein includes generating thermal energy, in which in a charging process: a) in a compression process, a working gas 13 is compressed from a temperature T1 and a pressure P1 to a pressure P2 with a temperature T2, b) in a heat exchange process, heat is transferred from the working gas 13 to a thermal store 15, as a result of which temperature and pressure of the working gas 13 are reduced to a temperature T3 and a pressure P3, and c) in an expansion process, the working gas 13 is expanded to a pressure P4 with a temperature T4, and the expanded working gas 13 is fed back again in a return line to the compression process, wherein heat is extracted from the working gas between the heat exchange process and the expansion process and is transferred to the working gas in the return line. The temperature T3 and the pressure P3 may be set by the dimensioning of the heat exchange process. The compression process may be driven by electrically seasonally arising surplus energy of a power plant with renewable energies. As storage material for the thermal store of the heat exchange process porous materials, sand, clay, stones, concrete, water or saline solution may be used.