Device for generating energy from compressed air, system including the same, and method for operating system

Abstract

To provide a device for generating energy from compressed air, a system including such a device, and a method for operating the system.SOLUTION: A device for generating energy from compressed air includes: an air turbine (16) mounted to expand gas air starting from a first pressure level to a second pressure level and generate first energy in the expanding process; a combustion chamber (17) mounted to receive the air expanded by the air turbine and burn fuel therein; and an exhaust gas turbine (18) provided to expand exhaust gas generated during combustion of the fuel in the combustion chamber (17) and generate second energy in the expansion process. At least the air turbine and the exhaust gas turbine have a common housing.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to an apparatus for generating energy from compressed air, a system comprising such an apparatus, and a method of operating the system.

Background Art

[0002] In practice, liquid air energy storage (LAES) devices and compressed air energy storage (CAES) devices for storing energy for subsequent use are known. Thus, in a liquid air energy storage device, liquid air is stored in a store that can be evaporated in an evaporator. The evaporated air is then directed through an air turbine and expanded therein, generating mechanical energy that can be utilized, for example, to drive a generator or another machine to generate electrical energy. In a compressed air energy storage device, compressed gaseous air is stored, and this gaseous air can likewise be directed through an air turbine to extract mechanical energy in the air turbine again, and this mechanical energy is utilized, for example, to drive a generator to generate electrical energy. The actually known liquid air energy storage (LAES) devices and compressed air energy storage (CAES) devices have only limited efficiency. There is a need for a device with higher efficiency for generating energy from compressed air.

Summary of the Invention

Problems to be Solved by the Invention

[0003] Starting from this, the present invention is based on the object of creating a new type of apparatus for generating energy from compressed air, a system comprising such an apparatus, and a method for operating the system.

Means for Solving the Problems

[0004] This object is achieved by means of the device for generating energy from compressed air according to claim 1, the system according to claim 10 or claim 11, and the method according to claim 13.

[0005] The device for generating energy from compressed air comprises an air turbine equipped to expand gaseous air from a first pressure level to a second pressure level and generate a first energy in the process.

[0006] The device for generating energy from compressed air further comprises a combustion chamber which is equipped to receive the air expanded in the air turbine and burn fuel therein.

[0007] The device for generating energy from compressed air further comprises an exhaust gas turbine equipped to expand the exhaust gas generated during the combustion of the fuel in the combustion chamber and generate a second energy in the process.

[0008] At least the air turbine and the exhaust gas turbine have a common housing.

[0009] With the aid of the device for generating energy from compressed air according to the invention, highly efficient energy can be generated from compressed air provided, for example, by a liquid air energy storage (LAES) device or a compressed air energy storage (CAES) device. In this process, the compressed air is first expanded in the air turbine to a first pressure level, then supplied to the combustion chamber, where the fuel is burned in the presence of the air expanded to the first pressure level, and the exhaust gas thus generated is guided via the exhaust gas turbine to generate further energy. Thus, energy, i.e., mechanical energy, is generated in both the air turbine and the exhaust gas turbine, which can be utilized, for example, to drive a generator for generating electrical energy.

[0010] Compared with a simple air turbine, the device according to the present invention can generate more than twice the effective power. Therefore, energy can be generated from compressed air with high efficiency.

[0011] Preferably, the air turbine, the combustion chamber, and the exhaust gas turbine are provided with a common housing. Alternatively, the air turbine and the exhaust gas turbine are provided with a common housing, and the combustion chamber is provided with a separate housing. In particular, when the air turbine, the combustion chamber, and the exhaust gas turbine are provided with a common housing, the device can be embodied in a particularly compact manner with low installation space requirements and low weight. Therefore, the arrangement of the air turbine, the combustion chamber, and the exhaust gas can be particularly flexible and efficient in a liquid air energy storage (LAES) device or a compressed air energy storage (CAES) device. In particular, when the combustion chamber is arranged in a separate housing, the installation space and the weight of the device increase, but the thermal stress on the common housing of the air turbine and the exhaust gas turbine can be reduced.

[0012] Preferably, the device for generating energy from compressed air includes a first heat exchanger connected between the air turbine and the combustion chamber. Through this heat exchanger, on the one hand, the air expanded in the air turbine and the air supplied to the combustion chamber are guided, and on the other hand, the exhaust gas expanded in the exhaust gas turbine is guided to heat the air expanded in the air turbine upstream of the combustion chamber. The first heat exchanger raises the temperature of the air expanded in the first air turbine, and as a result, the amount of fuel required in the combustion chamber can be reduced. Therefore, the efficiency of the device according to the present invention can be further improved.

[0013] Preferably, the device for generating energy from compressed air comprises a second heat exchanger connected upstream of the air turbine, through which, on the one hand, the air to be expanded in the air turbine and, on the other hand, the exhaust gas expanded in the exhaust gas turbine can be directed to heat the air to be expanded in the air turbine upstream of the air turbine. The efficiency of the device for generating energy from compressed air can also be further increased by means of a second heat exchanger connected upstream of the air turbine. Thus, by increasing the temperature of the air expanded in the air turbine, more energy can be generated in the air turbine.

[0014] Preferably, the air turbine and the exhaust gas turbine are arranged back to back such that the inlet sides of the two turbines are directed away from each other and the outlet sides of the two turbines face each other. By arranging the two turbines back to back, at least the common housing of the air turbine and the exhaust gas turbine can be advantageously thermally equalized with respect to the shaft driven by the air turbine and the exhaust gas turbine. Alternatively, the air turbine and the exhaust gas turbine are oriented in an inline arrangement such that the outlet side of one of the two turbines faces the inlet side of the other of the two turbines.

[0015] The system according to the invention preferably comprises a device for generating energy from compressed air and a liquid air energy storage (LAES) device according to the invention, the LAES device comprising a storage unit for storing liquid air and an evaporator for evaporating the liquid air, and the evaporated air can be supplied to the air turbine as gaseous compressed air. The device for generating energy from compressed air according to the invention is preferably used in combination with a liquid air energy storage (LAES) device for generating energy from liquid air.

[0016] Instead of a liquid air energy storage (LAES) device, the system according to the invention can also comprise a compressed air energy storage (CAES) device.

[0017] Preferred further developments of the invention result from the subclaims and the following description. Hereinafter, embodiments of the invention will be described in more detail with reference to the drawings, but the invention is not limited thereto.

Brief Description of the Drawings

[0018]

Figure 1

Figure 2

Figure 3

Embodiments for Carrying Out the Invention

[0019] This device relates to a device 10 for generating energy from compressed air. FIG. 1 shows the device 10 according to the invention in relation to a liquid air energy storage (LAES) device 11 and an electromechanical machine 12.

[0020] The LAES device 11 has a storage unit 13 for storing liquid air. Further, the LAES device 11 of the present embodiment includes a pump 14 for supplying liquid air to the evaporator 15 of the LAES device 11. In the evaporator 15, liquid air can be evaporated to thereby provide compressed gaseous air, and then energy can be generated with the assistance of the device 10, and the energy is utilized, for example, to drive the electromechanical machine 12 in FIG. 1.

[0021] The pump 14 is optional with the LAES device 11. Liquid air can also be extracted from the storage unit 13 by another method and supplied to the evaporator 15. In particular, when the pump 14 is present, it can be embodied as a cryopump.

[0022] The device 10 for generating energy from compressed air according to the present invention includes an air turbine 16. The air turbine 16 is equipped to expand compressed air from a first pressure level to a second pressure level and generate a first energy in the process.

[0023] Furthermore, the device 10 for generating energy from compressed air according to the present invention includes a combustion chamber 17. The combustion chamber 17 is provided to receive the air expanded in the air turbine 16, burn fuel in the presence of air, and generate exhaust gas in the process. The fuel to be burned is ignited in the combustion chamber 17.

[0024] The device 10 for generating energy from compressed air according to the present invention further includes an exhaust gas turbine 18. The exhaust gas turbine 18 is equipped to expand the exhaust gas generated in the combustion chamber 17 during the combustion of fuel and generate a second energy in the process.

[0025] Preferably, the air turbine 16 and the exhaust gas turbine 18 drive a common shaft 22 and, via the common shaft 22, drive the electromechanical machine 12 together. In this process, the electromechanical machine 12 is preferably operated as a generator to supply electrical energy.

[0026] According to FIG. 1, liquid air L1 is extracted from the storage section with the assistance of pump 14 and supplied to evaporator 15 as liquid air L2 by pump 14. Downstream of evaporator 15, there is gaseous compressed air L3 flowing through air turbine 16, and gaseous air L4 expanded to the second pressure level flows out from air turbine 16. The air L4 present at the second pressure level is supplied to combustion chamber 17 together with fuel K, and during the combustion of fuel K, exhaust gas is generated which exits combustion chamber 17 as exhaust gas A1 and is expanded in exhaust gas turbine 18. The expanded exhaust gas A2 is discharged from exhaust gas turbine 18.

[0027] In FIG. 1, device 10 includes a first heat exchanger 19 connected between air turbine 16 and combustion chamber 17. Through this first heat exchanger 19, the air L4 expanded in the air turbine and the exhaust gas A2 expanded in the exhaust gas turbine are guided, and the thermal energy of the exhaust gas A2 is transferred to the expanded air L4, increasing the temperature of the expanded air on the upstream side of combustion chamber 17. Thereby, the efficiency of device 10 for generating energy from compressed air according to the present invention can be increased.

[0028] FIG. 2 shows a block diagram of a second device 10 according to the present invention for generating electrical energy again from compressed air together with LAES device 11. To avoid unnecessary repetition in FIG. 2, the same reference numerals as in FIG. 1 are used for the same assemblies, and the description regarding FIG. 1 is referred to in this regard. Hereinafter, only the details in which the exemplary embodiment of FIG. 2 differs from the exemplary embodiment of FIG. 1 will be discussed.

[0029] In FIG. 1, air turbine 16, exhaust gas turbine 18, combustion chamber 17 and first heat exchanger 19 have a common housing 20. This enables a particularly compact space-saving and weight-reducing design. In contrast, in FIG. 2, only air turbine 16, exhaust gas turbine 18 and combustion chamber 17 have a common housing 20, while the first heat exchanger 19 is not integrated into the common housing 20 but rather is embodied as a separate assembly with a separate housing.

[0030] A further difference from FIG. 2 to FIG. 1 is that the exhaust gas A2 led through the first heat exchanger 19 expanded in the exhaust gas turbine 18 is subsequently led as exhaust gas A3 through the second heat exchanger 21 arranged upstream of the air turbine 16 as seen in the flow direction of the air expanded in the air turbine 16. On the other hand, the compressed gaseous air L3 and the exhaust gas A3 led through this second heat exchanger 21 are introduced, and the air L3 expanded in the air turbine 16 on the upstream side of the air turbine 16 is heated. Thereby, the efficiency can be further increased.

[0031] A further device 10 for generating energy from compressed air according to the present invention is shown in FIG. 3, in which an LAES device 11 is also shown. To avoid unnecessary repetition, the same reference numerals as in FIG. 1 are used for the same assemblies, and hereinafter only the details in which the exemplary embodiment of FIG. 3 differs from the exemplary embodiment of FIG. 1 will be discussed.

[0032] In the exemplary embodiment of FIG. 3, only the air turbine 16 and the exhaust gas turbine 18 have a common housing 20. In FIG. 3, both the first heat exchanger 19 and the combustion chamber 17 are not integrated within the common housing 20 and are embodied as separate assemblies having separate housings. Thereby, the common housing 20 of the air turbine 16 and the exhaust gas turbine 18 has a lower heat load than in FIG. 1, and heat deformation can be reduced as in FIG. 2. This is advantageous for the shaft 22 driven by the two turbines 16, 18, and the electromechanical machine 12 is driven via the shaft 22.

[0033] In the present invention, in the illustrated embodiment, the compressed gaseous air L3 provided by the LAES device 11 is expanded to the pressure level of the combustion chamber pressure of the combustion chamber 17.

[0034] In contrast to the illustrated exemplary embodiment, the compressed gaseous air can also be supplied by a compressed air energy storage (CAES) device.

[0035] In the CAES device, the evaporator 15 is old-fashioned. Instead of the pump 14, a compressor may be present with the CAES device.

[0036] The air supplied to the combustion chamber 17 is used to burn the fuel K in the combustion chamber 17. In the process within the combustion chamber 17, exhaust gas A1 is generated, which is led through the exhaust gas turbine 18 for expansion. Therefore, in both the air turbine 16 and the exhaust gas turbine 18, mechanical energy is generated in each case, and this mechanical energy is preferably used to drive a common shaft 22 of the electromechanical device 12 in the form of a generator to generate electrical energy.

[0037] Due to the combustion of this fuel K, thermal energy is supplied to the air expanded in the air turbine 16, and the exhaust gas A1 is expanded to atmospheric pressure in the exhaust gas turbine 18. The residual heat of the exhaust gas A2 can be utilized in at least one of the heat exchangers 19, 21 to heat the air L4 expanded in the air turbine 16 and / or the air L3 expanded in the air turbine 16.

[0038] According to the present invention, it is possible to output considerably more electric power than is possible with a pure air turbine combined with an LAES device or a CAES device. Therefore, it is possible to output approximately twice or more the electric power.

[0039] In the exemplary embodiments of FIGS. 1 to 3, the heat of the exhaust gas can be utilized to preheat the fuel K.

[0040] Alternatively or additionally, it is also possible to lead the exhaust gas exiting the exhaust gas turbine 18 through the evaporator 15 to the LAES device 11 in order to utilize the heat of the exhaust gas in the region of the evaporator 15.

[0041] In particular, when the LAES device 11 is present, the liquid air can be used, for example, to cool an assembly such as the combustion chamber 17, thus enabling a higher combustion temperature or operating temperature. Alternatively or additionally, the liquid air can be utilized to regulate the temperature or mass flow rate of the air or exhaust gas, and / or to optimize the combustion of the fuel, and / or to reduce emissions.

[0042] Preferably, the air turbine 16 and the exhaust gas turbine 18 are oriented in a back-to-back arrangement such that the inlet sides of the two turbines 16, 18 are directed away from each other and the outlet sides of the two turbines 16, 18 face each other. This back-to-back arrangement of the two turbines 16, 18 is not shown in FIGS. 1 to 3, and the same enables the common housing of at least the air turbine 16 and the exhaust gas turbine 18 to be advantageously thermally equalized with respect to the shaft 22 driven by the air turbine 16 and the exhaust gas turbine 20.

[0043] The present invention enables energy to be generated with high efficiency from compressed air.

[0044] Furthermore, the present invention relates to a method of operating a system of a device 10, a CAES device or a LAES device 11, and an electrical machine 12 coupled to a power network.

[0045] In particular, when the network frequency of the power network is smaller than a set value, the electrical machine 12 operates as a generator for stabilizing the network of the power network 12. In this case, for network stabilization, during the generation stage of electrical energy, the mechanical energy generated within the device 10 is converted into electrical energy and supplied to the power network. In this case, a CAES device or a LAES device 11 is connected to the device 10.

[0046] In particular, when the network frequency of the power network is greater than the set value, the electromechanical device 12 operates as a motor for stabilizing the power network. In this case, the electrical energy is converted into power losses for network stabilization. In this case, the CAES device or LAES device 11 is preferably disconnected from the device 10. In particular, when the CAES device or LAES device 11 is disconnected from the device 10, the electromechanical device 12 is preferably operated at the minimum rotational speed in order to change to the next production stage of electrical energy within a very short time.

[0047] Accordingly, the present invention also relates to the use of a system of the device 10, the CAES device or LAES device 11, and the electromechanical device 12 for stabilizing the network of the power network to which the electromechanical device 12 is connected.

Explanation of reference numerals

[0048] 10 Device 11 LAES device 12 Electromechanical device 13 Storage unit 14 Pump 15 Evaporator 16 Air turbine 17 Combustion chamber 18 Exhaust gas turbine 19 First heat exchanger 20 Housing 21 Second heat exchanger 22 Shaft

Claims

1. An apparatus for generating energy from compressed air, comprising: An air turbine (16) configured to expand gaseous air from a first pressure level to a second pressure level and generate a first energy in the process; A combustion chamber (17) configured to receive the air expanded by the air turbine and burn fuel therein; An exhaust gas turbine (18) configured to expand the exhaust gas generated during the combustion of the fuel in the combustion chamber and generate a second energy in the process; At least the air turbine (16) and the exhaust gas turbine (18) have a common housing (20).

2. The apparatus according to claim 1, wherein the air turbine (16), the combustion chamber (17), and the exhaust gas turbine (18) have a common housing (20).

3. The apparatus according to claim 1, wherein the air turbine (16) and the exhaust gas turbine (18) have a common housing (20), and the combustion chamber (17) has a separate housing.

4. The apparatus according to any one of claims 1 to 3, further comprising a first heat exchanger (19) connected between the air turbine (16) and the combustion chamber (17), through which, on one hand, the air expanded by the air turbine (16) and supplied to the combustion chamber (17), and on the other hand, the exhaust gas expanded by the exhaust gas turbine (18) can be guided upstream of the combustion chamber (17) to heat the air expanded by the air turbine (16).

5. The apparatus according to any one of claims 1 to 4, further comprising a second heat exchanger (21) connected upstream of the air turbine (16), through which, on one hand, the air to be expanded in the air turbine (16), and on the other hand, the exhaust gas expanded by the exhaust gas turbine (18) can be guided to heat the air expanded in the air turbine (16) upstream of the air turbine (16).

6. The apparatus according to claim 4 or 5, wherein the first heat exchanger (19) is provided to receive the exhaust gas expanded in the exhaust gas turbine (18) and then make the exhaust gas available for use in the second heat exchanger (21).

7. The apparatus according to claim 4, 5 or 6, wherein the first heat exchanger (19) is arranged within the common housing (20).

8. The apparatus according to any one of claims 1 to 7, wherein the air turbine (16) and the exhaust gas turbine (18) are arranged back to back such that the inlet sides of the two turbines (16, 18) face away from each other and the outlet sides of the two turbines (16, 18) face each other.

9. The apparatus according to any one of claims 1 to 8, wherein the air turbine (16) and the exhaust gas turbine (18) are arranged in series such that the outlet side of one of the two turbines (16) faces the inlet side of the other of the two turbines (18).

10. A system comprising the apparatus (10) according to any one of claims 1 to 9 and a liquid air energy storage device (11), wherein the liquid air energy storage device (11) comprises a storage unit (13) for storing liquid air and an evaporator (15) for evaporating the liquid air, and the evaporated air can be supplied to the air turbine (16). System.

11. A system comprising the apparatus (10) according to any one of claims 1 to 9 and a compressed air energy storage device comprising a storage unit for storing compressed gaseous air, and the compressed gaseous air can be supplied to the air turbine.

12. The system according to claim 11, further comprising an electromechanical device (12) connected to the apparatus (10) according to any one of claims 1 to 9 and operable as a motor and a generator.

13. A method for operating the system according to claim 12, wherein, for stabilizing the power network coupled to the electromechanical device (12), in particular when the network frequency of the power network is greater than a set value, the electromechanical device (12) is operated as a motor, and in particular when the network frequency of the power network is less than a set value, the electromechanical device (12) is operated as a generator.

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