KW-level container compressed air energy storage system and operation method

Abstract

The invention discloses a kW-level container compressed air energy storage system and an operation method, and belongs to the technical field of energy storage. The kW-level container compressed air energy storage system comprises an air storage unit, an energy storage unit, an energy release unit and a cooling unit; wherein the gas storage unit, the energy storage unit and the energy release unit are respectively integrated in standard containers, and the cooling unit is arranged at the top of any container; the system adopts an all-air cooling mode and is provided with a waste heat recovery device, and the whole system is of a closed circulation structure. The waste heat recovery device is used for recovering exhaust heat of the last-stage compressor so as to heat inlet air of the first-stage compressor. The modular integrated design of the system is realized, the gas storage unit, the energy storage unit and the energy release unit are respectively integrated in the standard container, and the cooling unit is arranged at the top of the container, so that the occupied area of the system is greatly reduced, the transportation and installation cost is reduced, and meanwhile, the number of modules can be flexibly matched according to user requirements; the energy storage device adapts to application scenes with different power requirements and is promoted to be popularized to urban areas.

Description

Technical Field

[0001] This invention relates to the field of energy storage technology, and in particular to a kW-class containerized compressed air energy storage system and its operation method. Background Technology

[0002] Compressed air energy storage (CASS) is an important component of new energy storage technologies, boasting advantages such as large storage capacity, long service life, and environmental friendliness, and is currently in the commercial application stage. However, existing CASS technologies still have several shortcomings that hinder their further development. First, existing CASS devices are structurally dispersed, numerous, and require large floor areas, making integration and miniaturization difficult, and thus unsuitable for applications in land-scarce areas such as urban areas. Second, thermal storage temperature is a key factor limiting the efficiency of CASS systems; current technologies struggle to increase thermal storage temperature at a reasonable cost, resulting in low overall system efficiency, high plant power consumption, and poor operational economy. Finally, existing systems often employ open cooling structures, leading to significant water losses and high requirements for cooling water temperature, limiting their adoption in water-scarce regions.

[0003] To address the aforementioned technical challenges, there is an urgent need to develop a modular, integrated, high-efficiency, and low-loss compressed air energy storage system and its operation method to meet the demands of large-scale and market-oriented development of new energy storage technologies. Summary of the Invention

[0004] To address the problems of existing compressed air energy storage devices, such as dispersed structures, numerous devices, large footprints, low overall efficiency, and high water consumption, this invention provides a kW-class containerized compressed air energy storage system and its operation method. This system can significantly reduce the footprint of the energy storage system, decrease the number of devices, improve energy storage efficiency, promote the modularization and miniaturization of energy storage devices, and further expand the application of energy storage devices in urban areas.

[0005] The technical solution adopted by the present invention, which describes a kW-level container compressed air energy storage system and its operation method, is as follows:

[0006] A kW-level containerized compressed air energy storage system includes an air storage unit, an energy storage unit, an energy release unit, and a cooling unit. The air storage unit, energy storage unit, and energy release unit are each integrated into a standard container, and the cooling unit is arranged on the top of any container. The system adopts an all-air cooling method, is equipped with a waste heat recovery device, and has an overall closed-loop structure. The waste heat recovery device is used to recover the exhaust heat of the final stage compressor to heat the inlet air of the first stage compressor.

[0007] A further improvement of the technical solution of the present invention is that: the energy storage unit and the energy release unit are each independently arranged in a container, the gas storage unit includes multiple horizontal storage tanks, each horizontal storage tank is independently arranged in a container, and each storage tank inlet is equipped with a shut-off valve, which can be isolated and maintained separately; both the energy storage unit and the energy release unit container are equipped with fans to send hot air from the container into the gas storage unit container to maintain the temperature of the storage tank.

[0008] A further improvement of the technical solution of the present invention is that: the energy storage unit includes a compressor inlet air heater, a multi-stage compressor, a multi-stage energy storage heat exchanger, a compressor cooler, and a waste heat exchange heat cooler connected in sequence; wherein, the outlet of the #2 compressor is connected in sequence to the #2 energy storage heat exchanger and the compressor cooler, and the compressor cooler reduces the inlet air temperature of the #3 compressor through two-stage heat exchange; the air outlet pipe of the compressor cooler is equipped with a condensate drain valve group, which is connected to the water supply tank of the cooling unit for water supply.

[0009] A further improvement of the technical solution of the present invention is that: the energy release unit includes an atmospheric pressure heat storage device, an expander, a high-pressure cylinder energy release heat exchanger and a low-pressure cylinder energy release heat exchanger; wherein, the atmospheric pressure heat storage device includes an atmospheric pressure water tank and separate high-temperature and low-temperature heat transfer oil tanks, and is correspondingly equipped with high-temperature and low-temperature heat transfer oil circulation pumps.

[0010] A further improvement of the technical solution of the present invention is that: the waste heat recovery device includes a waste heat exchanger, which is equipped with a two-way water source switching structure of cooling water and low temperature atmospheric pressure water; the cooling unit includes a closed cooling tower, and the water leakage during system operation is replenished by air condensation on the energy storage side, so as to achieve zero water loss in the entire system.

[0011] An operation method for a kW-level containerized compressed air energy storage system, based on the aforementioned energy storage system, includes an energy storage phase and an energy release phase;

[0012] Energy storage stage: When the corresponding shut-off valve is opened, the air is heated to the preset temperature by the air heater at the compressor inlet, and then compressed by a multi-stage compressor and cooled by a multi-stage heat exchanger before finally being sent to the gas storage unit for storage; at the same time, the heat storage medium absorbs the heat of compression through the heat exchanger and is stored in the high-temperature heat storage device.

[0013] Energy release stage: Close the energy storage stage shut-off valve and open the corresponding energy release shut-off valve. The air in the gas storage unit is heated by the energy release heat exchanger and then enters the expander to do work and generate electricity. After doing work, the air is discharged into the atmosphere. At the same time, the high-temperature heat storage medium releases heat and then cools down and is stored in the low-temperature heat storage device.

[0014] A further improvement of the technical solution of this invention is as follows: During the energy storage stage, the inlet air temperature of compressors #1 and #2 is increased to raise the heat storage temperature under the same gas storage pressure; when the water level of the cooling water system drops, the corresponding shut-off valve is opened to replenish the water tank using the condensate drained from the compressor cooler outlet air; during both the energy storage and energy release stages, the corresponding container fans are turned on to maintain the temperature of the gas storage unit; during the energy release stage, the temperature of the high-temperature heat transfer oil is controlled by the regulating valve to stabilize the inlet air temperature of the expander at a preset value.

[0015] The technological advancements achieved by this invention due to the adoption of the above technical solutions are as follows:

[0016] This invention achieves a modular integrated design of the system, integrating the gas storage unit, energy storage unit, and energy release unit into a standard container, with the cooling unit arranged on the top of the container. This significantly reduces the system's footprint and lowers transportation and installation costs. At the same time, the number of modules can be flexibly matched according to user needs to adapt to application scenarios with different power requirements, thus promoting the application of energy storage devices in urban areas.

[0017] This invention adopts an all-air cooling method. The compressor cooler, waste heat exchanger and other equipment have low requirements for cooling water temperature. With the addition of a closed cooling tower, the entire system achieves closed-loop circulation. The water leakage during daily operation can be replenished by air condensation on the energy storage side, with no additional water loss. It is suitable for use in water-scarce areas.

[0018] This invention achieves cascaded recovery and utilization of waste heat by setting up a compressor inlet air heater and a waste heat exchanger cooler. On the one hand, the heat from the exhaust of the final compressor is used to heat the inlet air of the first compressor, increasing the inlet air temperature of the #2 compressor and reducing heat loss through the cooling tower. On the other hand, by increasing the inlet temperature of the first compressor, the heat storage temperature is increased under the same gas storage pressure, thereby improving the system's energy storage efficiency and overall thermal efficiency. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the structure of a kW-class container compressed air energy storage system according to the present invention. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments and accompanying drawings. In the following description, descriptions of well-known structures and technologies are omitted to avoid unnecessarily obscuring the concept of this invention.

[0021] Example 1

[0022] like Figure 1As shown, this embodiment provides a kW-level containerized compressed air energy storage system, including an air storage unit, an energy storage unit, an energy release unit, and a cooling unit. Each unit is modularly arranged and integrated within a 40-foot standard container. The energy storage unit, integrated within one container, comprises a compressor inlet air heater, a #1 compressor, a #1 energy storage heat exchanger, a #2 compressor, a #2 energy storage heat exchanger, a compressor cooler, a #3 compressor, and a waste heat exchange cooler. These devices are connected sequentially via pipelines. The energy release unit, also integrated within one container, comprises an atmospheric pressure water tank, a high-temperature atmospheric pressure water circulation pump, a low-temperature atmospheric pressure water circulation pump, a high-temperature thermal oil tank, a low-temperature thermal oil tank, a high-temperature thermal oil circulation pump, a low-temperature thermal oil circulation pump, and a thermal oil cooler. The unit consists of a cooler, expander, high-pressure cylinder heat exchanger, and low-pressure cylinder heat exchanger, all connected by pipes and valves to form a circuit. The gas storage unit comprises multiple horizontal storage tanks, each independently arranged within a container, with a shut-off valve at the inlet of each tank for isolated maintenance. The cooling unit is a closed-loop cooling tower, located on top of any container along with a makeup water tank. A condensate drain valve assembly is installed on the air duct at the compressor cooler outlet, connected to the makeup water tank for replenishing the cooling water system.

[0023] The parameters of each device in this system are determined as follows:

[0024] ;

[0025] ;

[0026] ;

[0027] ;

[0028] ;

[0029] ;

[0030] ;

[0031] ;

[0032] The average annual temperature under typical operating conditions is taken as 273.45K.

[0033] : Average annual temperature of the application location, in K;

[0034] #1 compressor inlet air temperature, ;

[0035] #2 compressor inlet air temperature, ;

[0036] #3 compressor inlet air temperature, ;

[0037] : Design pressure of the gas storage facility, MPa;

[0038] The basic design pressure of the gas storage facility is 8, 10, 12, 14, 16, 18, or 20 MPa.

[0039] Expander power output, kW;

[0040] Reference design power, values ​​are 100, 132, 160, 180, 200, 250, 315, 355 kW;

[0041] Compressor outlet air temperature, ;

[0042] High-temperature heat transfer oil temperature (heat storage temperature). ;

[0043] : The outlet air temperature of the final compressor (the temperature entering the air storage tank). ;

[0044] Expander inlet air temperature ;

[0045] Low-temperature heat transfer oil temperature .

[0046] Example 2

[0047] This embodiment provides an operation method for a kW-level container compressed air energy storage system, including an energy storage stage and an energy release stage.

[0048] Energy storage phase operation process:

[0049] 1. Open the shut-off valve 31 and start the compressor inlet air heater to heat the air to the preset temperature t0 and then send it to the #1 compressor. The air is adiabatic compressed in the #1 compressor and the temperature rises to t3. Then it enters the #1 energy storage heat exchanger to exchange heat with the heat transfer oil. After the temperature drops to t1, it is sent to the #2 compressor.

[0050] 2. Start the low-temperature heat transfer oil circulation pump and open the shut-off valves 10 / 38 / 41 / 40 / 43. The low-temperature heat transfer oil passes through the shut-off valve 8, the low-temperature heat transfer oil circulation pump, the check valve 9, and the shut-off valves 10 / 38 / 41. After the flow rate is regulated by the regulating valves 39 / 42, it is sent to the #1 and #2 energy storage heat exchangers respectively. After absorbing the heat of air compression in the heat exchangers, the temperature of the heat transfer oil rises to t4. It is then sent to the high-temperature heat transfer oil tank for storage through the shut-off valves 40 / 43 / 11. The outlet temperature of the heat transfer oil is maintained at t4 by the regulating valves 39 and 42.

[0051] 3. After entering the #2 compressor, the air undergoes adiabatic compression, and the temperature rises again to t3. Then, it enters the #2 energy storage heat exchanger and the compressor cooler for two-stage heat exchange. After the temperature drops to t2, it is sent to the #3 compressor. The compressor cooler uses a closed cooling tower for cooling. Through two-stage heat exchange, the inlet air temperature of the #3 compressor is effectively reduced, thereby reducing the power consumption of the compressor during the energy storage stage.

[0052] 4. Start the low-temperature atmospheric pressure water circulation pump and the high-temperature atmospheric pressure water circulation pump, and open the shut-off valves 51 / 27 / 30 / 50. The low-temperature atmospheric pressure water is sent to the waste heat exchanger after passing through shut-off valve 1, the low-temperature atmospheric pressure water circulation pump, check valve 2, shut-off valve 51 / 27, and then the flow rate is regulated by regulating valve 28. After absorbing the exhaust heat of compressor #3, the low-temperature atmospheric pressure water rises in temperature to form high-temperature atmospheric pressure water, which is sent to the high-temperature atmospheric pressure water tank through shut-off valve 30. When the high-temperature atmospheric pressure water tank is full, close the low-temperature atmospheric pressure water circulation pump and shut-off valves 51 / 27 / 30.

[0053] 5. High-temperature atmospheric pressure water is sent to the compressor inlet air heater after passing through shut-off valve 3, high-temperature atmospheric pressure water circulation pump, check valve 47, shut-off valve 50, and then regulating valve 48 to provide heat for heating the inlet air. After heat exchange, low-temperature atmospheric pressure water is sent to the low-temperature atmospheric pressure water tank for recycling through shut-off valve 49. The inlet air temperature of compressor #1 is maintained at t0 by regulating valve 48.

[0054] 6. Start the cooling water circulation pump and open the shut-off valves 23 / 26 / 44 / 46. The cooling water flows through shut-off valve 23, the cooling water circulation pump, check valve 24, shut-off valves 26 / 44, and then through regulating valve 45 to adjust the flow rate before being sent to the compressor cooler. The regulating valve 45 controls the inlet air temperature of compressor #3 to be maintained at a certain level. After heat exchange, the cooling water is returned to the closed cooling tower via shut-off valve 46. When the low-temperature atmospheric pressure water circulation pump is shut off, shut-off valves 25 / 29 are opened to directly cool the outlet air of compressor #3 via cooling water. The outlet air temperature of compressor #3 is maintained at a certain level by regulating valve 28. .

[0055] 7. Air is compressed to the design pressure of the air storage tank in compressor #3. Afterwards, the air is sent to the horizontal storage tank of the gas storage unit through shut-off valves 31 / 32 / 33 / 34 / 35 for storage; when the water level of the cooling water system drops, shut-off valve 32 is opened, and the air condensate from the compressor cooler outlet is sent to the water replenishment tank for replenishment after passing through shut-off valves 31, 32 and drain valve 33.

[0056] 8. Turn on the fans of the energy storage unit container and the gas storage container to send the hot air from the energy storage unit container into the gas storage container to replace the cold air in the gas storage, maintain the temperature of the gas storage tank, and reduce system heat loss.

[0057] Energy release phase operation process:

[0058] 1. Close shut-off valve 31 and open shut-off valves 22 / 12. The high-pressure air in the gas storage unit is sent to the high-pressure cylinder energy release heat exchanger through shut-off valve 22. After exchanging heat with the high-temperature heat transfer oil, the temperature rises and then enters the high-pressure cylinder of the expander to do work. After doing work, the air enters the low-pressure cylinder energy release heat exchanger, exchanges heat with the high-temperature heat transfer oil again to rise, and then enters the low-pressure cylinder of the expander to do work and generate electricity. After doing work, the air is discharged into the atmosphere through shut-off valve 12. After the energy release is completed, shut-off valve 12 is closed to prevent the expander from losing heat.

[0059] 2. Start the high-temperature heat transfer oil circulation pump and open the shut-off valves 6 / 16 / 18 / 19 / 21. The high-temperature heat transfer oil passes through the shut-off valve 4, the high-temperature heat transfer oil circulation pump, the check valve 5, and the shut-off valves 6 / 16 / 19. After the flow rate is regulated by the regulating valve 17 / 20, it is sent to the high-pressure cylinder energy release heat exchanger and the low-pressure cylinder energy release heat exchanger respectively. After the heat transfer oil releases heat, its temperature decreases. After being cooled to t7 by the shut-off valve 18 / 2 and the heat transfer oil cooler, it is sent to the low-temperature heat transfer oil tank for storage. The temperature of the air at the expander inlet is maintained at t6 by the regulating valve 17 / 20.

[0060] 3. Start the cooling water circulation pump and open the shut-off valves 23 / 26 / 14 / 15. The cooling water flows through shut-off valve 23, the cooling water circulation pump, check valve 24, shut-off valve 13, and then the flow rate is regulated by regulating valve 14 before being sent to the heat transfer oil cooler. The outlet temperature of the heat transfer oil is maintained at a certain level by regulating valve 14. After heat exchange, the cooling water is returned to the closed cooling tower via shut-off valve 15.

[0061] 4. Turn on the blower of the energy release device container and the blower of the gas storage container to send the hot air in the energy release device container into the gas storage container to maintain the temperature of the gas storage tank and reduce system heat loss; when it is necessary to vent, the system can be vented through the shut-off valve 36 / 37.

[0062] In addition, the waste heat exchange cooler of the present invention adopts a dual water source switching structure of cooling water and low temperature atmospheric pressure water, which can switch the water source according to the system operating conditions, effectively reducing air-side resistance; except for the cooling tower, the rest of the devices are arranged indoors, which further reduces system heat loss and improves operating efficiency.

[0063] In the above embodiments, a kW-level containerized compressed air energy storage system and its operation method are provided. This invention achieves a modular integrated design of the system, integrating the gas storage unit, energy storage unit, and energy release unit into a standard container, with the cooling unit arranged on the top of the container. This significantly reduces the system's footprint and lowers transportation and installation costs. Simultaneously, the number of modules can be flexibly configured according to user needs to adapt to application scenarios with different power requirements, promoting the widespread adoption of energy storage devices in urban areas. This invention adopts an all-air cooling method, with low requirements for cooling water temperature in equipment such as the compressor cooler and waste heat exchanger. Combined with a closed-loop cooling tower, it achieves a closed-loop circulation throughout the system. Water leakage during daily operation can be replenished through air condensation on the energy storage side, resulting in no additional water loss, making it suitable for applications in water-scarce areas. This invention achieves tiered recovery and utilization of waste heat by setting up a compressor inlet air heater and a waste heat exchanger. On one hand, it utilizes the exhaust heat of the final compressor to heat the inlet air of the first compressor, increasing the inlet air temperature of the #2 compressor and reducing heat loss through the cooling tower. On the other hand, by increasing the inlet temperature of the first compressor, the heat storage temperature is increased under the same gas storage pressure, improving the system's energy storage efficiency and overall thermal efficiency.

[0064] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the concept and scope of the present invention. Various modifications and improvements made to the technical solutions of the present invention by those skilled in the art without departing from the inventive concept should fall within the protection scope of the present invention. All technical contents for which protection is sought in this invention are fully described in the claims.

Claims

1. A kW-class containerized compressed air energy storage system, characterized in that: It includes a gas storage unit, an energy storage unit, an energy release unit, and a cooling unit; wherein the gas storage unit, energy storage unit, and energy release unit are integrated into a standard container, and the cooling unit is arranged on the top of any container; the system adopts an all-air cooling method, is equipped with a waste heat recovery device, and the whole is a closed-loop structure; the waste heat recovery device is used to recover the exhaust heat of the final stage compressor to heat the inlet air of the first stage compressor.

2. The kW-level containerized compressed air energy storage system according to claim 1, characterized in that: The energy storage unit and the energy release unit are each independently arranged in a container. The gas storage unit includes multiple horizontal storage tanks, each of which is independently arranged in a container. Each storage tank inlet is equipped with a shut-off valve, which can be isolated and maintained separately. Both the energy storage unit and the energy release unit containers are equipped with fans to send hot air from inside the container into the gas storage unit container to maintain the temperature of the storage tank.

3. The kW-level containerized compressed air energy storage system according to claim 1, characterized in that: The energy storage unit includes a compressor inlet air heater, a multi-stage compressor, a multi-stage energy storage heat exchanger, a compressor cooler, and a waste heat exchange heat cooler connected in sequence; wherein, the outlet of the #2 compressor is connected in sequence to the #2 energy storage heat exchanger and the compressor cooler, and the compressor cooler reduces the inlet air temperature of the #3 compressor through two-stage heat exchange; the air outlet pipe of the compressor cooler is equipped with a condensate drain valve group, which is connected to the water supply tank of the cooling unit for water supply.

4. The kW-level containerized compressed air energy storage system according to claim 1, characterized in that: The energy release unit includes an atmospheric pressure heat storage device, an expander, a high-pressure cylinder energy release heat exchanger, and a low-pressure cylinder energy release heat exchanger; wherein, the atmospheric pressure heat storage device includes an atmospheric pressure water tank and separate high-temperature and low-temperature heat transfer oil tanks, and is equipped with corresponding high-temperature and low-temperature heat transfer oil circulation pumps.

5. The kW-level containerized compressed air energy storage system according to claim 1, characterized in that: The waste heat recovery device includes a waste heat exchanger cooler, which is equipped with a dual water source switching structure for cooling water and low-temperature atmospheric pressure water; the cooling unit includes a closed cooling tower, and the water leakage during system operation is replenished through air condensate drainage on the energy storage side, achieving zero water loss in the entire system.

6. An operation method for a kW-class containerized compressed air energy storage system, characterized in that: The energy storage system according to any one of claims 1-5 includes an energy storage stage and an energy release stage; Energy storage stage: When the corresponding shut-off valve is opened, the air is heated to the preset temperature by the air heater at the compressor inlet, and then compressed by a multi-stage compressor and cooled by a multi-stage heat exchanger before finally being sent to the gas storage unit for storage; at the same time, the heat storage medium absorbs the heat of compression through the heat exchanger and is stored in the high-temperature heat storage device. Energy release stage: Close the energy storage stage shut-off valve and open the corresponding energy release shut-off valve. The air in the gas storage unit is heated by the energy release heat exchanger and then enters the expander to do work and generate electricity. After doing work, the air is discharged into the atmosphere. At the same time, the high-temperature heat storage medium releases heat and then cools down and is stored in the low-temperature heat storage device.

7. The operation method of a kW-level containerized compressed air energy storage system according to claim 6, characterized in that: During the energy storage phase, the inlet air temperature of compressors #1 and #2 is increased to raise the heat storage temperature under the same gas storage pressure. When the water level in the cooling water system drops, the corresponding shut-off valve is opened to replenish the water tank using the condensate drained from the compressor cooler outlet. During both the energy storage and energy release phases, the corresponding container fans are turned on to maintain the temperature of the gas storage unit. During the energy release phase, the temperature of the high-temperature heat transfer oil is controlled by the regulating valve to stabilize the inlet air temperature of the expander at the preset value.

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