Anti-surge intermediate-stage deflation recovery system and method for compressed air energy storage compressor

Abstract

The invention relates to the field of compressed air energy storage, in particular to a compressed air energy storage compressor anti-surge intermediate-stage deflation recovery system and method. The system comprises a compressor unit, a compressor heat exchanger, an exhaust valve and a gas storage which are sequentially arranged on a main gas pipeline; the second communicating valve, the recycling gas tank, the first communicating valve, the sealing gas tank and the sealing gas valve are sequentially arranged on the auxiliary gas path; a recovery gas pipeline is arranged between the recovery gas tank and the compressor unit, and a surge deflation valve is arranged on the recovery gas pipeline; the sealing gas tank is used for storing a gas source of sealing gas and instrument power gas, and is used for dry gas sealing, an instrument, a valve and an executing mechanism when the compressor unit operates; and the recovery gas tank is used for recovering and storing the discharged gas of the compressor unit when the compressor unit operates under the non-design working condition and is used for preventing surge. According to the invention, the recovery gas tank is arranged to independently recover and utilize the deflation gas of the anti-surge intermediate stage of the compressor, so that the defects of conventional measures are avoided.

Description

Technical Field

[0001] This invention relates to the field of compressed air energy storage, and in particular to a compressed air energy storage compressor anti-surge intermediate stage venting recovery system and method. Background Technology

[0002] Intermediate-stage venting is an anti-surge measure used in multi-stage centrifugal / axial compressors. It involves creating a vent port on the casing of an intermediate stage (usually before the high-pressure stage) of the compressor. When the unit operates under off-design conditions approaching the surge zone, the vent valve is opened to release some of the gas from the intermediate stage (either venting or recovering it to the compressor inlet). This method effectively alleviates inter-stage flow imbalance, reduces the inlet pressure and flow load of downstream stages, and prevents downstream stages from triggering surge due to insufficient flow. Furthermore, compared to outlet venting, this method significantly reduces energy loss.

[0003] The gas discharged from the intermediate stage of the compressor can be either vented or recycled back to the compressor inlet for recirculation. When the medium is air, direct venting is the better option. Although there is some energy loss, it avoids the efficiency reduction, system complexity, and operating condition fluctuations that can occur with recycling.

[0004] The core principle of compressed air energy storage is to utilize off-peak electricity or surplus renewable energy to drive a compressor, compressing air into high-pressure air and storing it (while simultaneously recovering the heat of compression), thus converting electrical energy into pressure and heat energy. During peak electricity demand, the high-pressure air is released and heated using the stored heat of compression, driving an expander to power a generator, converting the pressure and heat energy back into electrical energy. This process completes the storage and release of electrical energy. In compressed air energy storage systems, the compressor is a high-load, multi-stage compressor with large flow and pressure ratios. Traditional anti-surge intermediate stage venting methods, if performed empty, waste a significant amount of compressed air, reducing the efficiency and economy of the energy storage system. Conversely, if the intermediate stage venting is recycled back to the compressor inlet for recirculation, it reduces the efficiency of the high-power, high-load compressor and causes operational fluctuations, increasing operational difficulty and cost. Since the purpose of a compressed air energy storage system is to generate electricity using stored compressed air, the intermediate stage venting can be recovered separately and used together with the stored compressed air to generate electricity. This rational utilization of the intermediate stage venting ensures the efficiency and economy of the energy storage system. How to utilize the venting from the anti-surge intermediate stage of the compressor, and then combine it with the air source in the system to make comprehensive use of all the compressed air, is an urgent problem to be solved. Summary of the Invention

[0005] The purpose of this invention is to solve the problems existing in the prior art, and to propose a compressed air energy storage compressor anti-surge intermediate stage gas release recovery system and recovery method.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: This invention discloses a compressed air energy storage compressor anti-surge intermediate stage gas recovery system, characterized in that it comprises a compressor unit, a compressor heat exchanger, an exhaust valve, and an air storage tank arranged sequentially on the main air pipeline, and a connecting two valves, a recovery air tank, a connecting one valve, a sealing air tank, and a sealing air valve arranged sequentially on the auxiliary air pipeline. The end of the auxiliary air pipeline near the connecting two valves is connected to the air storage tank, and the end near the sealing air valve is connected to the compressor unit; wherein: A recovery gas pipeline is provided between the recovery gas tank and the compressor unit, and a surge relief valve is provided on the recovery gas pipeline; Sealing gas tanks are used to store sealing gas and instrument power gas, providing dry gas for sealing, instruments, and actuators during compressor unit operation; The gas recovery tank is used to recover and store the vent gas from the compressor unit when it is operating under non-design conditions, in order to prevent surge.

[0007] As a further preferred option, the gas source for the sealing gas tank is replenished from the recovery gas tank and the gas storage tank. During operation, a small external compressor can also be connected to provide sealing gas and instrument power gas.

[0008] As a further preferred option, the gas storage tank is connected to an expander via an outlet pipe, and the outlet pipe is equipped with an expander valve and an expander heat exchanger.

[0009] As a further preferred embodiment, the compressor unit includes a low-pressure stage, an intermediate stage, and a high-pressure stage arranged in sequence, with a compressor heat exchanger corresponding to the downstream of each of the low-pressure stage, intermediate stage, and high-pressure stage. The recovered gas pipeline is connected to the intermediate stage; The main gas pipeline is connected to the low-pressure stage, intermediate stage, and high-pressure stage respectively.

[0010] The present invention discloses a recovery method for a compressed air energy storage compressor anti-surge intermediate stage vent recovery system, comprising the following steps: Step 1: In the initial state, all valves are closed: sealing valve, connecting valve 1, surge venting valve, connecting valve 2, and expander valve. Open the exhaust valve and start the compressor unit to charge the gas storage tank. After starting the compressor unit, open the sealing valve to ensure dry gas sealing and instrument power operation. If the compressor unit stalls or approaches surge under non-design conditions, open the surge venting valve to recover the intermediate stage gas from the compressor unit. Step 2: After the compressor enters the design operating condition, close the surge relief valve; Step 3: After the gas storage tank reaches the storage pressure, shut down the compressor, and close the exhaust valve and sealing valve; Step 4: Determine if the compressed air in the recovery gas tank meets the requirements for use in the sealing gas tank. If it does, open the first connecting valve and slowly supply gas to the sealing gas tank. Once the pressure in the sealing gas tank reaches the required value, close the first connecting valve. Then open the second connecting valve to connect the gas storage tank and the recovery gas tank, ensuring that the pressure in these two storage areas is uniform. If the conditions are not met, open the second connecting valve to connect the gas storage tank and the recovery gas tank. After the pressure in the two gas storage areas is uniform, open the first connecting valve and slowly supply gas to the sealed gas tank. After the pressure in the sealed gas tank reaches the usage value, close the first connecting valve. Step 5: Open the expander valve to discharge the compressed air from the gas storage tank and the recovery gas tank, drive the expander to generate electricity, and put the compressed air energy storage system into power generation mode; after power generation is completed, close the expander valve and then close the connecting valve 2. Beneficial effects

[0011] 1. Compared to ordinary air compressors, the recovery gas tank separately recovers and utilizes the vent gas from the compressor's anti-surge intermediate stage, avoiding the disadvantages of conventional measures (venting results in energy loss, and recovering it to the compressor inlet causes efficiency reduction and operating condition fluctuations).

[0012] 2. Compared with general compressed air energy storage systems, this invention adds the gas recovery of the compressor anti-surge intermediate stage, and sets up a recovery gas tank and surge gas relief valve to store the recovered compressor intermediate stage gas, and then use it after the gas storage is completed.

[0013] 3. The compressed air energy storage system integrates three storage areas: air storage tank, sealed air tank, and recovery air tank. The compressed air source of the compressor is used in stages and groups, which improves the system efficiency. Attached Figure Description

[0014] Figure 1 A schematic diagram of the anti-surge intermediate stage gas recovery system for compressed air energy storage compressor is shown.

[0015] In the diagram, 1-low pressure stage, 2-intermediate stage, 3-high pressure stage, 4-gas storage tank, 5-sealed gas tank, 6-recovery gas tank, 7-exhaust valve, 71-sealed gas valve, 72-connecting valve 1, 73-surge venting valve, 74-connecting valve 2, 75-expander valve, 8-expander, 9-compressor heat exchanger, 91-expander heat exchanger. Detailed Implementation

[0016] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0017] This invention provides a compressed air energy storage compressor anti-surge intermediate stage vent recovery system. It sets up a recovery gas tank to separately recover the vent from the compressor's anti-surge intermediate stage. In the compressed air energy storage system, three gas storage areas are integrated: a gas storage tank, a sealing gas tank, and a recovery gas tank. The compressed air source of the compressor is used in stages, maximizing the utilization of compressed air and improving system efficiency.

[0018] The compressed air energy storage compressor anti-surge intermediate stage gas release and recovery system consists of a low-pressure stage 1, an intermediate stage 2, and a high-pressure stage 3. Other components include an air storage tank 4, a sealing gas tank 5, a recovery gas tank 6, an exhaust valve 7, a sealing gas valve 71, a connecting valve 1 72, a surge vent valve 73, a connecting valve 2 74, an expander valve 75, an expander 8, a compressor heat exchanger 9, and an expander heat exchanger 91.

[0019] In the compressed air energy storage system, the compressor includes a low-pressure stage 1, an intermediate stage 2, and a high-pressure stage 3. During energy storage, the compressor compresses air. After starting, the compressor draws in air from the atmosphere and compresses it sequentially through the low-pressure stage 1, intermediate stage 2, and high-pressure stage 3. Each stage is followed by a compressor heat exchanger 9 to recover and store the heat of compression. Finally, the high-pressure air enters the air storage tank 4. During power generation, the expander valve 75 is opened. The compressed air passes through the expander heat exchanger 91, absorbing the stored heat of compression, and drives the expander 8 to generate electricity.

[0020] Air storage tank 4 is used to store compressed air for the compressed air energy storage system, generated by the compressor compressing atmospheric air. Sealing gas tank 5 is used to store the gas source for sealing gas and instrument power gas, providing dry gas for sealing and for components such as instruments, valves, and actuators during compressor operation. Recoverable gas tank 6 is used to recover the vent gas stored in the intermediate stage to prevent surge when the compressor is operating under non-design conditions.

[0021] Sealing gas is used for dry gas sealing of the compressor, ensuring that the compressor equipment is leak-proof and wear-free. Instrument power gas provides the air source power for instruments, valves, actuators, and other components in the system, enabling valve regulation, equipment start-up and shutdown, and interlock protection. Sealing gas and instrument power gas can be supplied separately by a small air compressor and stored in a sealing gas tank. This invention also employs a method of replenishing the sealing gas tank from other gas tanks. The sealing gas tank 5 is supplied with air from the recovery gas tank 6 and the air storage tank 4. During operation, a small external compressor can also be connected to provide sealing gas and instrument power gas.

[0022] The exhaust valve 7 connects the high-pressure stage 3 of the compressor and the air storage tank 4. It is opened before the compressor starts to discharge compressed air into the air storage tank 4.

[0023] The sealing gas valve 71 connects the sealing gas tank 5 to each stage of the compressor. It opens when the compressor starts and is used for dry gas sealing and instrument power.

[0024] A connecting valve 72 connects the sealed gas tank 5 and the recovery gas tank 6, and closes when the compressor starts.

[0025] The surge relief valve 73 connects the intermediate stage 2 of the compressor and the recovery gas tank 6, and closes when the compressor starts.

[0026] The connecting valve 74 connects the gas storage tank 4 and the recovery gas tank 6, and closes when the compressor starts.

[0027] Expander valve 75 connects gas storage tank 4 and expander 8, and opens when generating electricity.

[0028] System operation method: a) With all initial valves closed, open exhaust valve 7 and start the compressor to charge gas into gas storage tank 4; after starting the compressor, open sealing valve 71 to ensure dry gas sealing and instrument power operation; when the compressor stalls or approaches surge under non-design conditions, open surge vent valve 73 to recover the intermediate stage gas from the compressor.

[0029] b) After the compressor enters the design operating condition, close the surge relief valve 73.

[0030] c) After the gas storage tank 4 reaches the gas storage pressure, the compressor is turned off, and the exhaust valve 7 and the sealing valve 71 are closed.

[0031] d) Determine if the compressed air in the recovery gas tank 6 meets the requirements for use in the sealing gas tank. If it does, open the connecting valve 72 and slowly supply gas to the sealing gas tank 5. Once the pressure in the sealing gas tank 5 reaches the required value, close the connecting valve 72. Then open the connecting valve 74 to connect the gas storage tank 4 and the recovery gas tank 6, ensuring uniform pressure in both storage areas.

[0032] If the conditions are not met, open the connecting valve 74 to connect the gas storage tank 4 and the recovery gas tank 6. After the pressure in the two gas storage areas is uniform, open the connecting valve 72 to slowly supply gas to the sealed gas tank 5. After the pressure in the sealed gas tank 5 reaches the usage value, close the connecting valve 72.

[0033] e) Open expander valve 75 to discharge compressed air from gas storage tank 4 and recovery gas tank 6, driving the expander to generate electricity, and the compressed air energy storage system is in power generation mode. After power generation is completed, close expander valve 75, and then close connecting valve 74.

[0034] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A compressed air energy storage compressor anti-surge intermediate stage gas release recovery system, characterized in that: This includes a compressor unit, a compressor heat exchanger (9), an exhaust valve (7), and a gas storage tank (4) arranged sequentially on the main gas pipeline, and a connecting valve (74), a recovery gas tank (6), a connecting valve (72), a sealing gas tank (5), and a sealing gas valve (71) arranged sequentially on the auxiliary gas pipeline. The end of the auxiliary gas pipeline closest to the connecting valve (74) is connected to the gas storage tank (4), and the end closest to the sealing gas valve (71) is connected to the compressor unit; wherein: A recovery gas pipeline is provided between the recovery gas tank (6) and the compressor unit, and a surge relief valve (73) is provided on the recovery gas pipeline. The sealing gas tank (5) is used to store the gas source of sealing gas and instrument power gas, which is used for dry gas sealing and instrument and actuator when the compressor unit is running; The gas recovery tank (6) is used to recover the vent gas of the compressor unit when it is not operating under design conditions, and to store the vent gas of the compressor unit for anti-surge purposes.

2. The compressed air energy storage compressor anti-surge intermediate stage gas recovery system according to claim 1, characterized in that: The gas source for the sealing gas tank (5) is supplemented from the recovery gas tank (6) and the gas storage tank (4). During operation, a small external compressor can also be connected to provide sealing gas and instrument power gas.

3. The compressed air energy storage compressor anti-surge intermediate stage gas recovery system according to claim 1, characterized in that: The gas storage tank (4) is connected to an expander (8) via an outlet pipe. An expander valve (75) and an expander heat exchanger (91) are installed on the outlet pipe.

4. The compressed air energy storage compressor anti-surge intermediate stage gas recovery system according to claim 3, characterized in that: The compressor unit includes a low-pressure stage (1), an intermediate stage (2), and a high-pressure stage (3) arranged in sequence. Downstream of the low-pressure stage (1), the intermediate stage (2), and the high-pressure stage (3) are respectively a compressor heat exchanger (9). The recovered gas pipeline is connected to the intermediate stage (2); The main gas pipeline is connected to the low-pressure stage (1), intermediate stage (2), and high-pressure stage (3) respectively.

5. The recovery method of the compressed air energy storage compressor anti-surge intermediate stage gas recovery system according to claim 4, characterized in that, Includes the following steps: Step 1: In the initial state, the sealing valve (71), connecting valve 1 (72), surge vent valve (73), connecting valve 2 (74), and expander valve (75) are all closed. Open the exhaust valve (7) and start the compressor unit to charge the gas storage tank (4). After starting the compressor unit, open the sealing valve (71) to ensure dry gas sealing and instrument power operation. When the compressor unit stalls or approaches surge under non-design conditions, open the surge vent valve (73) to recover the intermediate stage gas of the compressor unit. Step 2: After the compressor enters the design operating condition, close the surge relief valve (73). Step 3: After the gas storage tank (4) reaches the gas storage pressure, shut off the compressor, close the exhaust valve (7) and the sealing valve (71). Step 4: Determine whether the compressed gas in the recovery gas tank (6) meets the requirements for use in the sealing gas tank (5). If it does, open the connecting valve (72) and slowly supply gas to the sealing gas tank (5). After the pressure in the sealing gas tank (5) reaches the required value, close the connecting valve (72). Then open the connecting valve (74) to connect the gas storage tank (4) and the recovery gas tank (6) to make the pressure in the two gas storage areas uniform. If not satisfied, open the connecting valve 2 (74) to connect the gas storage tank (4) and the recovery gas tank (6). After the pressure in the two gas storage areas is uniform, open the connecting valve 1 (72) and slowly supply gas to the sealed gas tank (5). After the pressure in the sealed gas tank (5) reaches the usage value, close the connecting valve 1 (72). Step 5: Open the expander valve (75) to discharge the compressed air in the gas storage tank (4) and the recovery gas tank (6), drive the expander to generate electricity, and the compressed air energy storage system is in the power generation state; after the power generation is completed, close the expander valve (75) and then close the connecting valve (74).

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