A compressed air energy storage system with an air storage tank heat recovery system and a control method thereof

Abstract

The present invention discloses a compressed air energy storage system with an air storage tank heat recovery system and a control method thereof, including a compressed air storage tank, a cold storage tank and a heat storage tank, wherein the cold storage tank outlet is connected to the temperature drop control valve inlet, the heat storage tank outlet is connected to the temperature rise control valve inlet, the temperature drop control valve outlet intersects with the temperature rise control valve outlet, and is connected to the heat exchanger inlet of the compressed air storage tank, and the heat exchanger outlet of the compressed air storage tank is divided into two paths, one path is connected to the high-temperature outlet valve inlet, and the high-temperature outlet valve outlet is connected to the heat storage tank inlet; the other path is connected to the low-temperature outlet valve inlet, and the low-temperature outlet valve outlet is connected to the cold storage tank inlet. The present invention effectively improves the energy storage capacity of the compressed air energy storage in the compressed air energy storage stage; and effectively improves the work-doing capacity of the compressed air energy storage in the energy release stage, thereby improving the electric-to-electric conversion efficiency of the compressed air energy storage as a whole.

Description

Technical Field

[0001] The invention relates to a compressed air energy storage system with an air storage tank heat recovery system and a control method thereof, belonging to the technical field of compressed air energy storage systems. Background Art

[0002] Compressed air energy storage is one of the more advanced energy storage methods currently available. Its main feature is that it consumes electricity storage capacity during low electricity consumption periods, and drives the generator to generate electricity through the expander during peak electricity consumption periods. It has the advantages of large energy storage scale, long storage cycle, and low environmental pollution. It is considered to be one of the most promising large-scale power energy storage technologies.

[0003] Compressed air energy storage includes energy storage and energy release. In the energy storage stage, the compressor increases the air pressure by compressing the air in the environment, and stores the high-pressure air in a compressed air storage tank or salt cavern. The compressed air in the compressed air storage tank or salt cavern has a higher and higher temperature due to the compressed air at the compressor outlet doing work on it. According to the ideal gas equation, the higher the temperature, the less the mass of the stored working fluid will be when the volume and pressure are constant, thereby reducing the energy storage capacity of the system.

[0004] During the energy release stage, as the compressed air in the compressed air storage tank or salt cavern does work externally, its temperature will gradually decrease. According to the ideal gas equation, the lower the temperature, the greater the mass of the working fluid stored when the volume and pressure are constant, thereby reducing the work capacity of the system.

[0005] In order to fully utilize the system's energy storage and work capabilities and improve the compressed air energy storage electric-to-electric conversion efficiency, it is necessary to control the temperature of the compressed air storage tank or salt cavern. Summary of the invention

[0006] The technical problem to be solved by the present invention is: to provide a compressed air energy storage system with an air tank heat recovery system and a control method thereof, by arranging a heat exchanger for the compressed air energy storage tank and utilizing the adjustment characteristics of a regulating valve to realize the adjustment and control of the temperature of the compressed air storage tank in the compressed air energy storage stage and the energy release stage, thereby solving the problem of the reduced energy storage capacity of the traditional compressed air energy storage system due to the increase in the temperature of the compressed air storage tank during the energy storage stage, and also solving the problem of the reduced working capacity of the traditional compressed air energy storage system due to the decrease in the temperature of the compressed air storage tank during the energy release stage.

[0007] The technical solution adopted by the present invention is: a compressed air energy storage system with an air storage tank heat recovery system, including a compressed air storage tank, a cold storage tank and a heat storage tank, the cold storage tank outlet is connected to the temperature drop control valve inlet, the heat storage tank outlet is connected to the temperature rise control valve inlet, the temperature drop control valve outlet intersects with the temperature rise control valve outlet, and is connected to the heat exchanger inlet of the compressed air storage tank, the heat exchanger outlet of the compressed air storage tank is divided into two paths, one path is connected to the high-temperature outlet valve inlet, and the high-temperature outlet valve outlet is connected to the heat storage tank inlet; the other path is connected to the low-temperature outlet valve inlet, and the low-temperature outlet valve outlet is connected to the cold storage tank inlet.

[0008] Preferably, the air outlet of the compressed air storage tank is connected to a plurality of expansion machines connected in series, the leftmost expansion machine is provided with an exhaust port, the expansion machines are connected by transmission shafts, and the rightmost expansion machine is connected to the generator through a transmission shaft; the air inlet of the compressed air storage tank is connected to a plurality of compressors in series, the compressors are connected by transmission shafts, and the rightmost compressor is connected to the transmission shaft of the motor.

[0009] Preferably, a heat exchanger 1 is installed on the connecting air path between the adjacent compressors, and the heat exchanger 1 is also connected to the cold storage tank and the heat storage tank.

[0010] Preferably, a second heat exchanger is installed on the connecting gas path between the adjacent expanders, and the second heat exchanger is also connected to the cold storage tank and the heat storage tank.

[0011] Preferably, the number of the above-mentioned cold storage tanks is greater than or equal to one.

[0012] Preferably, the number of the above-mentioned heat storage tanks is greater than or equal to one.

[0013] Preferably, the number of the compressed air tanks is greater than or equal to one.

[0014] Preferably, the temperature drop control valve is controlled manually, electrically, pneumatically or hydraulically.

[0015] Preferably, the temperature rise control valve is controlled manually, electrically, pneumatically or hydraulically.

[0016] Preferably, the temperature drop control valve is a regulating valve type, which can be operated and maintained at any opening.

[0017] Preferably, the temperature rise control valve is a regulating valve type, which can be operated and maintained at any opening degree.

[0018] Preferably, the above-mentioned heat exchanger is a plate type, a tube type, or a heat pipe type heat exchanger.

[0019] A control method for a compressed air energy storage system having an air storage tank heat recovery system, the method comprising the following steps:

[0020] Energy storage stage:

[0021] Step 1: Close the temperature rise control valve, close the low temperature outlet valve, and open the high temperature outlet valve;

[0022] Step 2: Start the compressor, and the compressed air from the compressor enters the compressed air storage tank after passing through the heat exchanger;

[0023] Step 3: When the actual temperature in the compressed air storage tank is greater than the set temperature, gradually open the temperature drop control valve; when the actual temperature in the compressed air storage tank is less than or equal to the set temperature, gradually close the temperature drop control valve;

[0024] Energy release stage:

[0025] Step 1: Close the temperature drop control valve, close the high temperature outlet valve, and open the high temperature outlet valve and the low temperature outlet valve;

[0026] Step 2: Open the expander inlet valve, and the compressed air enters the expander from the compressed air storage tank through the heat exchanger;

[0027] Step 3: When the actual temperature in the compressed air storage tank is lower than the set temperature, gradually open the temperature rise control valve; when the actual temperature in the compressed air storage tank is higher than or equal to the set temperature, gradually close the temperature rise control valve.

[0028] Beneficial effects of the present invention: Compared with the prior art, the present invention realizes the regulation and control of the temperature of the compressed air storage tank in the compressed air energy storage stage and the energy release stage by arranging a heat exchanger for the compressed air energy storage tank and utilizing the regulation characteristics of the regulating valve. In the compressed air energy storage stage, by controlling the temperature of the compressed air storage tank not higher than the set value, the temperature does not increase with the increase of the gas storage amount of the compressed air energy storage tank, thereby effectively improving the energy storage capacity of the compressed air energy storage; in the energy release stage, by controlling the temperature of the compressed air storage tank not lower than the set value, the temperature does not decrease with the decrease of the gas storage amount of the compressed air energy storage tank, thereby effectively improving the working capacity of the compressed air energy storage, thereby improving the overall electric-to-electric conversion efficiency of the compressed air energy storage. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 is a system schematic diagram of the present invention;

[0030] Figure 2 It is a schematic diagram of the connection structure in which the compressed air storage tank is replaced by a salt cavern. DETAILED DESCRIPTION

[0031] The present invention is further described below in conjunction with the accompanying drawings and specific embodiments.

[0032] Example 1: Figure 1As shown, a compressed air energy storage system with an air storage tank heat recovery system includes a compressed air storage tank, a cold storage tank, and a heat storage tank. The cold storage tank outlet is connected to the inlet of a temperature drop control valve 31, and the heat storage tank outlet is connected to the inlet of a temperature rise control valve 34. The outlet of the temperature drop control valve 31 intersects with the outlet of the temperature rise control valve 34, and is connected to the inlet of a heat exchanger 30 of the compressed air storage tank. The outlet of the heat exchanger 30 of the compressed air storage tank is divided into two paths, one path is connected to the inlet of a high-temperature outlet valve 32, and the outlet of the high-temperature outlet valve 32 is connected to the inlet of the heat storage tank; the other path is connected to the inlet of a low-temperature outlet valve 33, and the outlet of the low-temperature outlet valve 33 is connected to the inlet of the cold storage tank.

[0033] Preferably, the air outlet of the compressed air storage tank is connected to a plurality of expansion machines connected in series, the leftmost expansion machine is provided with an exhaust port, the expansion machines are connected by transmission shafts, and the rightmost expansion machine is connected to the generator through a transmission shaft; the air inlet of the compressed air storage tank is connected to a plurality of compressors in series, the compressors are connected by transmission shafts, and the rightmost compressor is connected to the transmission shaft of the motor.

[0034] Preferably, a heat exchanger 1 is installed on the connecting air path between the adjacent compressors, and the heat exchanger 1 is also connected to the cold storage tank and the heat storage tank.

[0035] Preferably, a second heat exchanger is installed on the connecting gas path between the adjacent expanders, and the second heat exchanger is also connected to the cold storage tank and the heat storage tank.

[0036] Preferably, the number of the above-mentioned cold storage tanks is greater than or equal to one.

[0037] Preferably, the number of the above-mentioned heat storage tanks is greater than or equal to one.

[0038] Preferably, the number of the compressed air tanks is greater than or equal to one.

[0039] Preferably, the temperature drop control valve is controlled manually, electrically, pneumatically or hydraulically.

[0040] Preferably, the temperature rise control valve is controlled manually, electrically, pneumatically or hydraulically.

[0041] Preferably, the temperature drop control valve is a regulating valve type, which can be operated and maintained at any opening.

[0042] Preferably, the temperature rise control valve is a regulating valve type, which can be operated and maintained at any opening degree.

[0043] Preferably, the above-mentioned heat exchanger is a plate type, a tube type, or a heat pipe type heat exchanger.

[0044] A control method for a compressed air energy storage system having an air storage tank heat recovery system comprises the following steps:

[0045] Energy storage stage:

[0046] Step 1: close the temperature rise control valve 34, close the low temperature outlet valve 33, and open the high temperature outlet valve 32;

[0047] Step 2: Start the compressor, and the compressed air from the compressor enters the compressed air storage tank after passing through the heat exchanger;

[0048] Step 3:

[0049] When t1≥t0+ε, gradually open the temperature drop control valve 31;

[0050] When t1≤t0-ε, gradually close the temperature drop control valve 31;

[0051] In the formula, t1 is the actual temperature in the compressed air storage tank, t0 is the set temperature of the compressed air storage tank, and ε is the temperature adjustment dead zone;

[0052] Step 4: When p1≥p0, stop the compressor; where p1 is the actual pressure of the compressed air tank, and p0 is the design pressure of the compressed air tank;

[0053] Step 5: After the compressor is shut down for 10 minutes, fully close the temperature drop control valve 31 and fully close the high-temperature outlet valve 32;

[0054] Energy release stage:

[0055] Step 1: close the temperature drop control valve 31, close the high temperature outlet valve 32, and open the low temperature outlet valve 33;

[0056] Step 2: Open the expander inlet valve, and the compressed air enters the expander from the compressed air storage tank through the heat exchanger;

[0057] Step 3:

[0058] When t1≤t0+ε, gradually open the temperature rise control valve 34;

[0059] When t1≥t0-ε, gradually close the temperature rise control valve 34;

[0060] In the formula, t1 is the actual temperature in the compressed air storage tank, t0 is the set temperature of the compressed air storage tank, and ε is the temperature adjustment dead zone;

[0061] Step 4: When p1≤p0, stop the compressor. In the formula, p1 is the actual pressure of the compressed air storage tank, and p0 is the design pressure of the compressed air storage tank;

[0062] Step 5: After the expander is shut down for 10 minutes, the temperature rise control valve 34 and the low-temperature outlet valve 33 are fully closed.

[0063] Example 2: Figure 2As shown, a compressed air energy storage system with an air storage tank heat recovery system includes a salt cavern, a cold storage tank, and a heat storage tank. The cold storage tank outlet is connected to the inlet of a temperature drop control valve 31, and the heat storage tank outlet is connected to the inlet of a temperature rise control valve 34. The outlet of the temperature drop control valve 31 intersects with the outlet of the temperature rise control valve 34 and is connected to the inlet of a heat exchanger 30 of the salt cavern. The outlet of the heat exchanger 30 of the salt cavern is divided into two paths, one of which is connected to the inlet of a high-temperature outlet valve 32, and the outlet of the high-temperature outlet valve 32 is connected to the inlet of the heat storage tank; and the other is connected to the inlet of a low-temperature outlet valve 33, and the outlet of the low-temperature outlet valve 33 is connected to the inlet of the cold storage tank.

[0064] The exhaust gas from the leftmost compressor passes through a heat exchanger and enters a salt cavern for storage.

[0065] The leftmost expander is provided with an exhaust port, the expanders are connected by transmission shafts, and the generator is connected to the transmission shaft of the rightmost expander; the compressors are connected by transmission shafts, and the rightmost compressor is connected to the transmission shaft of the motor.

[0066] A control method for a compressed air energy storage system having an air storage tank heat recovery system comprises the following steps:

[0067] Energy storage stage:

[0068] Step 1: close the temperature rise control valve 34, close the low temperature outlet valve 33, and open the high temperature outlet valve 32;

[0069] Step 2: Start the compressor, and the compressed air from the compressor enters the salt cavern after passing through the heat exchanger;

[0070] Step 3:

[0071] When t1≥t0+ε, gradually open the temperature drop control valve 31;

[0072] When t1≤t0-ε, gradually close the temperature drop control valve 31;

[0073] In the formula, t1 is the actual temperature in the salt cavern, t0 is the set temperature of the salt cavern, and ε is the temperature adjustment dead zone;

[0074] Step 4: When p1≥p0, stop the compressor; where p1 is the actual pressure of the compressed air tank, and p0 is the design pressure of the compressed air tank;

[0075] Step 5: After the compressor is shut down for 10 minutes, fully close the temperature drop control valve 31 and fully close the high-temperature outlet valve 32;

[0076] Energy release stage:

[0077] Step 1: close the temperature drop control valve 31, close the high temperature outlet valve 32, and open the low temperature outlet valve 33;

[0078] Step 2: Open the expander inlet valve, and the compressed air enters the expander from the salt cavern through the heat exchanger;

[0079] Step 3:

[0080] When t1≤t0+ε, gradually open the temperature rise control valve 34;

[0081] When t1≥t0-ε, gradually close the temperature rise control valve 34;

[0082] In the formula, t1 is the actual temperature in the salt cavern, t0 is the set temperature of the salt cavern, and ε is the temperature adjustment dead zone;

[0083] Step 4: When p1≤p0, stop the compressor. Where p1 is the actual pressure of the salt cavern, and p0 is the design pressure of the salt cavern;

[0084] Step 5: After the expander is shut down for 10 minutes, the temperature rise control valve 34 and the low-temperature outlet valve 33 are fully closed.

[0085] The above description is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can easily think of changes or substitutions within the technical scope disclosed by the present invention, which should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A compressed air energy storage system with an air storage tank heat recovery system, comprising a compressed air storage tank, characterized in that: The invention also comprises a cold storage tank and a heat storage tank, wherein the outlet of the cold storage tank is connected to the inlet of the temperature drop control valve (31), the outlet of the heat storage tank is connected to the inlet of the temperature rise control valve (34), the outlet of the temperature drop control valve (31) intersects with the outlet of the temperature rise control valve (34), and is connected to the inlet of the heat exchanger (30) of the compressed air storage tank, the outlet of the heat exchanger (30) of the compressed air storage tank is divided into two paths, one path is connected to the inlet of the high-temperature outlet valve (32), the outlet of the high-temperature outlet valve (32) is connected to the inlet of the heat storage tank; the other path is connected to the inlet of the low-temperature outlet valve (33), the outlet of the low-temperature outlet valve (33) is connected to the inlet of the cold storage tank; the air outlet of the compressed air storage tank is connected to To multiple expansion machines connected in series, the leftmost expansion machine is provided with an exhaust port, the expansion machines are connected by transmission shafts, and the rightmost expansion machine is connected to the generator through a transmission shaft; the compressed air storage tank inlet is connected in series with multiple compressors, the compressors are connected by transmission shafts, and the rightmost compressor is connected to the transmission shaft of the motor; a heat exchanger 1 is installed on the connecting air path between adjacent compressors, and the heat exchanger 1 is also connected to the cold storage tank and the heat storage tank; a heat exchanger 2 is installed on the connecting air path between adjacent expansion machines, and the heat exchanger 2 is also connected to the cold storage tank and the heat storage tank; a control method for a compressed air energy storage system with a gas storage tank heat recovery system, the method comprising the following steps: Energy storage stage: Step 1: close the temperature rise control valve (34), close the low temperature outlet valve (33), and open the high temperature outlet valve (32); Step 2: Start the compressor, and the compressed air from the compressor enters the compressed air storage tank after passing through the heat exchanger; Step 3: when the actual temperature in the compressed air storage tank is greater than the set temperature, gradually open the temperature drop control valve (31); when the actual temperature in the compressed air storage tank is less than or equal to the set temperature, gradually close the temperature drop control valve (31); Step 4: When p1≥p0, stop the compressor; where p1 is the actual pressure of the compressed air tank, and p0 is the design pressure of the compressed air tank; Step 5: After the compressor is shut down for 10 minutes, fully close the temperature drop control valve (31) and fully close the high-temperature outlet valve (32); Energy release stage: Step 1: close the temperature drop control valve (31), close the high temperature outlet valve (32), and open the low temperature outlet valve (33); Step 2: Open the expander inlet valve, and the compressed air enters the expander from the compressed air storage tank through the heat exchanger; Step 3: when the actual temperature in the compressed air storage tank is lower than the set temperature, gradually open the temperature rise control valve (34); when the actual temperature in the compressed air storage tank is higher than or equal to the set temperature, gradually close the temperature rise control valve (34); Step 4: When p1≤p0, stop the compressor, where p1 is the actual pressure of the compressed air storage tank, and p0 is the design pressure of the compressed air storage tank; Step 5: After the expander is shut down for 10 minutes, the temperature rise control valve (34) and the low-temperature outlet valve (33) are fully closed.

2. A compressed air energy storage system with an air storage tank heat recovery system according to claim 1, characterized in that: The number of the cold storage tanks is greater than or equal to one.

3. The compressed air energy storage system with an air storage tank heat recovery system according to claim 1, characterized in that: The number of the heat storage tanks is greater than or equal to one.

4. The compressed air energy storage system with an air storage tank heat recovery system according to claim 1, characterized in that: The number of the compressed air tanks is greater than or equal to one.

5. The compressed air energy storage system with an air storage tank heat recovery system according to claim 1, characterized in that: The temperature drop control valve (31) is controlled by manual, electric, pneumatic or hydraulic operation; the temperature rise control valve (34) is controlled by manual, electric, pneumatic or hydraulic operation; the temperature drop control valve (31) is a regulating valve type, which can be operated and maintained at any opening; the temperature rise control valve (34) is a regulating valve type, which can be operated and maintained at any opening.

6. A compressed air energy storage system with an air storage tank heat recovery system according to claim 1, characterized in that: The heat exchanger (30) is a plate type, a tube type, or a heat pipe type heat exchanger.

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