Method And Device For Storing And Recovering Energy

Abstract

The invention relates to a method for storing and recovering energy, wherein an air liquefaction product (LAIR) is formed during an energy storage period, and a fluid pressure flow (12) is formed during an energy recovery period using at least one part of the air liquefaction product (LAIR) and is expanded for operation in at least one energy recovery device (14, 17). The air liquefaction product (LAIR) is obtained as a liquid medium during the energy storage period by compressing air in an air conditioning device (3), said compression being operated while supplying energy, in particular while supplying a current (9), optionally stored in a cold state, and fed to an evaporator unit (7). The air liquefaction product (LAIR) is expanded for operation as a fluid pressure flow (12) in the at least one energy recovery device (14, 17) during the energy recovery period after a pressure increase. The aim of the invention is to provide a solution with which even existing gas and steam power plants or open gas turbines are to be equipped with an energy storage capability. This is achieved in that the fluid pressure flow (12), in particular an air flow, is expanded in a first energy recovery device (14) and conducted through a recuperator device (13), in particular a heat boiler, upstream of said first energy recovery device (14), and thermal energy which has been decoupled from a flue gas flow (23) fed to the recuperator device (13) is coupled into the fluid pressure flow (12) in said heating tank. The flue gas flow (23) is fed to the recuperator device (13) from a fuel-fired second energy recovery device (17), in particular a gas turbine.

Claims

1. A method of storing and recovering energy, in which an air liquefaction product (LAIR) is formed in an energy storage period and a fluid pressure stream is formed using at least a portion of the air liquefaction product (LAIR) in an energy recovery period and is expanded to perform work in at least one energy generation device, in which the air liquefaction product (LAIR) is obtained as liquid medium in the energy storage period by compression of air, operated with supply of energy, in an air conditioning device, and sent to an evaporator unit and in which the air liquefaction product (LAIR) is expanded to perform work at least in the energy recovery period after a pressure increase as the fluid pressure stream in the at least one energy generation device, characterized in that the fluid pressure stream is expanded in a first energy generation device and, downstream of this first energy generation device, is passed through a recuperator device in which heat energy abstracted from a flue gas stream fed to the recuperator device is injected into the fluid pressure stream, the flue gas stream being fed to the recuperator device from a fuel-fired second energy generation device.

2. The method as claimed in claim 1, wherein the fluid pressure stream is fed to the recuperator at a pressure of 30-100 bar and is heated therein by means of the heat energy injected to a temperature of >400 C.

3. The method as claimed in claim 1, wherein the fluid pressure stream is expanded in at least one first expansion stage of the first energy generation device to a pressure of 0.2 bar.

4. The method as claimed in claim 1, wherein the fluid pressure stream is expanded in the at least one first expansion stage of the first energy generation device to a pressure of 10 bar, then a substream is branched off and fed to the fuel-fired second energy generation device.

5. The method as claimed in claim 1, wherein the fluid pressure stream is expanded in the first expansion stage of the first energy generation device to a pressure of 10 bar, then a substream is branched off and fed to the fuel-fired second energy generation device, and the remaining residual substream is fed to a third expansion stage of the first energy generation device.

6. The method as claimed in claim 4, wherein the substream of the fluid pressure stream fed to the second energy generation device corresponds to 2%-40% of the mass flow of air which is compressed by at least one compressor stage of the second energy generation device in operation of the second energy generation device.

7. The method as claimed in claim 1, wherein the flue gas stream is passed through a recuperator device which brings about denoxing.

8. The method as claimed in claim 1, wherein the flue gas stream fed to the recuperator device, prior to entry into the recuperator device, is supplied with a fresh air stream at ambient temperature in such an amount that the flue gas stream is cooled prior to entry into the recuperator device to a temperature between 250 C. and 500 C.

9. The method as claimed in claim 1, wherein the flue gas stream, prior to entry into the recuperator device, is cooled by means of sprayed introduction of water to a temperature of 250 C. to 500 C.

10. The method as claimed in claim 1, wherein the waste heat of compression that arises in the compression of air in the air conditioning device is stored and/or provided as district heat and/or as process heat.

11. The method as claimed in claim 1, wherein heat energy is abstracted from the output air stream leaving the first energy generation device and/or from the flue gas stream leaving the recuperator device and made available as district heat and/or as process heat.

12. The method as claimed in claim 1, wherein the air conditioning device comprising a liquefaction unit and an evaporator unit is supplied with cooling energy that arises in other evaporation processes.

13. A device for storage and recovery of energy by formation of an air liquefaction product (LAIR) in an energy storage period and for production and work-performing expansion of a fluid pressure formed using at least a portion of the air liquefaction product (LAIR) in an energy recovery period, the device comprising an air conditioning device that can be operated with supply of energy, by means of which the air liquefaction product (LAIR) can be produced as liquid medium by compression of air, a conveying device that compresses the air liquefaction product (LAIR) in a pressure-increasing manner to give the fluid pressure stream and at least one energy generation device which is connected by conduits to the conveying device and expands the fluid pressure stream to perform work, in the conduit connection upstream of a first energy generation device through which the fluid pressure stream flows in flow direction of the fluid pressure stream, a recuperator device is disposed through which the fluid pressure stream flows, in which heat energy abstracted from a flue gas stream fed to the recuperator device can be injected into the fluid pressure stream, the recuperator device being within a conduit connection that supplies the flue gas stream to a fuel-fired second energy generation device.

14. The device as claimed in claim 13, wherein the first and second energy generation devices are within a conduit connection that supplies a substream of the fluid pressure stream.

15. The device as claimed in claim 13, wherein the first energy generation device and/or the fuel-fired second energy generation device take(s) the form of a generator turbine(s).

16. The device as claimed in claim 13, wherein the first energy generation device and/or the fuel-fired second energy generation device have/has at least one expansion stage that expands the fluid pressure stream supplied.

17. The device as claimed in claim 13, wherein the first energy generation device and/or the fuel-fired second energy generation device have/has at least one compression stage that compresses the fluid pressure stream supplied and/or air supplied.

18. The device as claimed in claim 13, wherein a flue gas denoxing unit is configured and arranged within the recuperator device.

19. The device as claimed in claim 13, wherein the air conditioning device comprises a liquefaction unit, an evaporation unit and a cooling energy storage unit.

20. The device as claimed in claim 13, wherein it has means that have been set up to conduct a method in which an air liquefaction product (LAIR) is formed in an energy storage period and a fluid pressure stream is formed using at least a portion of the air liquefaction product (LAIR) in an energy recovery period and is expanded to perform work in at least one energy generation device, in which the air liquefaction product (LAIR) is obtained as liquid medium in the energy storage period by compression of air, operated with supply of energy, in an air conditioning device, and sent to the evaporator unit, and in which the air liquefaction product (LAIR) is expanded to perform work at least in the energy recovery period after a pressure increase as the fluid pressure stream in the at least one energy generation device, characterized in that the fluid pressure stream is expanded in the first energy generation device and, downstream of this first energy generation device, is passed through the recuperator device in which heat energy abstracted from a flue gas stream fed to the recuperator device is infected into the fluid pressure stream, the flue gas stream being fed to the recuperator device from a fuel-fired second energy generation device.

Description

[0053] The invention is elucidated in detail by way of example hereinafter with reference to a drawing.

[0054] The drawing shows, in FIGS. 1-9, working examples of the device of the invention for performance of the method of the invention in schematic view.

[0055] FIGS. 1-9 illustrate identical, analogous or basically corresponding elements, apparatuses, devices and fluid streams with identical reference signs, and for the sake of clarity they are not elucidated again in all cases. This is all the more true in that the individual variants according to FIGS. 1-9 differ from one another in partial regions only.

[0056] FIG. 1 shows a device of the invention in the form of an energy storage plant 1 and an energy generation plant 2. In the energy storage plant 1, an air liquefaction product (LAIR) is formed in an energy storage period. For this purpose, in an air conditioning device 3 comprising a compression unit 5 operated with power 4, a liquefaction unit 6 and an evaporator unit 7 with dedicated cooling energy storage means 8, an air liquefaction product (LAIR) is prepared from air 9 supplied to the compressor unit 5. The air liquefaction product (LAIR) is (intermediately) stored in a storage device 10 configured as a liquid storage means, such that this storage unit 10 constitutes an air liquefaction product storage device. In order to be able to utilize the energy stored in this air liquefaction product (LAIR) again in the energy generation plant 2, this air liquefaction product is fed to the evaporator unit 7 with the aid of a conveying device configured as a pump 11 within an energy recovery period, flows through it and is then available in the form of a cold fluid pressure stream 12 with a pressure in the range between 30 and 10 bar, preferably 30 and 90 bar, especially 40 to 70 bar, most preferably 55-75 bar, and ambient temperature. It is also possible here that the air liquefaction product (LAIR) is not (intermediately) stored in the storage unit 10 but fed to the pump 11 immediately after it has been generated. The cold fluid pressure stream 12 is conveyed through a recuperator device 13 to a first energy generation device 14. In the working example according to FIG. 1, the first energy generation device 14 comprises a first expansion stage 15 with a connected generator 16, the first expansion stage 15 taking the form of an expansion turbine.

[0057] The energy generation plant 2 further comprises a fuel-fired second energy generation device 17 in the form of a gas turbine unit 18, especially of an open gas turbine 18a with a connected generator 19. The gas turbine unit 18 has a compression stage 20, especially a compression turbine, by means of which air 41 supplied is compressed and fed to a combustion chamber 21. In the combustion chamber 21, the compressed air 41 is combusted with fuel supplied, natural gas 40 in the working example, and the offgas stream formed is passed to a second expansion stage 22, especially an expansion turbine, of the gas turbine unit 18. The flue gas leaving the second expansion stage 22, having a temperature of more than 400 C., especially a temperature in the range of 450-500 C., is likewise fed to the recuperator device 13 as flue gas stream 23. In the recuperator device 13, heat is exchanged between the flue gas stream 23 and the fluid pressure stream 12 in such a way that heat energy is abstracted from the flue gas stream 23 and injected into the fluid pressure stream 12. After flowing through the recuperator device 13 in the form of a waste heat boiler, the fluid pressure stream 12 has a temperature of more than 400 C., preferably more than 450 C., especially a temperature in the range of 500-550 C. This fluid pressure stream 12 that has now been heated to a high temperature is fed to the expansion stage 15 of the first energy generation device 14 and expanded such that the air 24 released to the environment still has a pressure of 0.2 bar. In the case of this combined operation of first energy generation device 14 and second energy generation device 17, power is generated by means of the two generators 16 and 19.

[0058] In the embodiment according to FIG. 2, by contrast with the embodiment according to FIG. 1, a substream 25 of the fluid pressure stream 12 is branched off from the first expansion stage 15 of the first energy generation device 14 after the fluid pressure stream has been expanded in the first expansion stage 15 to a pressure of >10 bar, preferably a pressure between 10 bar and 25 bar. This substream 25 of the fluid pressure stream is fed to the combustion chamber 21 of the second energy generation device 17. In addition, a substream 34 is branched off from the air stream of the air 41 having a temperature of about 450 C. at the end of the compression stage 20, which has been compressed in the compression stage 20, and is mixed into the fluid pressure stream 12 upstream of the recuperator device 13, such that the latter is already heated prior to entry into the recuperator device 13. In this case, the substream 25 can be mixed into the residual substream of compressed air 41 fed to the combustion chamber 21 even before it enters the combustion chamber 21, as indicated by a dotted line in FIG. 2.

[0059] The further configuration is as in the embodiment according to FIG. 1.

[0060] The embodiment according to FIG. 3 differs from the preceding embodiments in that the expansion stage of the first energy generation device 14 is in two-stage form and comprises the first expansion stage 15 and a third expansion stage 15a. Here, the fluid pressure stream 12 is expanded in the first expansion stage 15 to a pressure of >10 bar, preferably >14 bar, and then fed to the third expansion stage 15a. Between the first and third expansion stages 15, 15a, a substream 26 of the fluid pressure stream 12 is branched off and fed to the combustion chamber 21 of the second energy generation device 17. The remaining residual substream 12a of the fluid pressure stream 12 is fed to the third expansion stage 15a of the first energy generation device 14.

[0061] The embodiment according to FIG. 4 differs from that according to FIG. 3 merely in that the expansion stage of the second energy generation device 17 is also in two-stage form and comprises the second expansion stage 22 and a fourth expansion stage 22a.

[0062] The embodiment according to FIG. 5 is supposed to illustrate that the waste heat of compression 27 that arises in the compression of the air 9 supplied in the compression unit 5 can be stored in a heat storage means 28 and then supplied to a district heating grid and/or a process heat grid 29.

[0063] FIG. 6 illustrates that it is also possible to arrange a heat exchanger 30 downstream of the recuperator device 13, and this can be used to withdraw residual heat still present in the flue gas stream 23 and likewise supply it to the district heating grid and/or process heat grid 29. It is likewise possible to feed the output air 24 leaving the first energy generation device 14 to a heat exchanger 31 in which, in turn, heat energy still present in the output air 24 can be abstracted and then made available to the district heating grid and/or process heat grid 29.

[0064] FIG. 7 shows that cooling energy/surplus cooling energy 32 originating from other processes, especially evaporation processes, preferably from the compression of natural gas or liquid natural gas, can be fed to the air conditioning device 3 and can be used here particularly in the liquefaction unit 6.

[0065] While FIG. 8 illustrates that the heat energy stored in the heat storage means 28 can also be fed in the form of process heat 29a to the evaporator unit 7 or to the fluid pressure stream 12, FIG. 9, finally, shows that outside heat 33 can also be used in order to supply heat energy to the evaporator unit 7 and/or to the fluid pressure stream 12 upstream and/or downstream of the recuperator device 13 in flow direction.

[0066] An air liquefaction product in the context of the invention is any product which can be produced in the form of a cryogenic liquid at least by compression, cooling and subsequent expansion of air. More particularly, an air liquefaction product may be liquid air, liquid oxygen, liquid nitrogen and/or a liquid noble gas such as liquid argon. The terms liquid oxygen and liquid nitrogen each also refer to a cryogenic liquid including oxygen or nitrogen in an amount above that in atmospheric air. Thus, these liquids need not necessarily be pure liquids having high contents of oxygen and nitrogen respectively. Liquid nitrogen is thus understood to mean either pure or essentially pure nitrogen or a mixture of liquefied air gases whose nitrogen content is higher than that of atmospheric air. For example, the latter has a nitrogen content of at least 90 and preferably at least 99 mole percent.

[0067] The terms energy storage period and energy recovery period are especially understood to mean periods of time that do not overlap. This means that the measures described above and below for the energy storage period are typically not conducted during the energy recovery period, and vice versa. However, it may also be the case, for example in a further period, that at least some of the measures described for the energy storage period are conducted simultaneously with the measures described for the energy recovery period, for example in order to assure greater continuity in the operation of a corresponding plant. For example, it is also possible to supply a fluid pressure stream 12 in an energy storage period of a unit or energy generation plant 12 set up for energy generation and to expand it so as to perform work therein, for example in order to be able to operate the compressor used here without shutdown. The energy storage period and energy recovery period each correspond to a mode of operation or process mode of a corresponding plant or corresponding method.