A combustion-type dual-well hydraulic compressed air energy storage system and its operation method

Abstract

The present invention discloses a combustion-type double-well hydraulic compressed air energy storage system and an operation method thereof. The system includes a fluid conveying device, double wells, a turbine, a control system, a burner, a hydrogen supply system and a water electrolysis hydrogen production system; the double wells include a first well and a second well that are interconnected at the bottom, the first well is filled with water, and the second well is filled with air, a turbine is arranged at the connection point at the bottom of the double wells, the second well is connected to an air source, and the water outlet and water inlet of the first well are connected to a water source; a heat exchanger is arranged in the second well; the water electrolysis hydrogen production system, the hydrogen supply system and the burner are connected in sequence, the hydrogen supply system is also connected to a heat storage system, and the heat storage system is also connected to a heat exchanger; the heat storage system is connected to a waste heat utilization system to realize the use of valley electricity and abandoned electricity to start the fluid conveying device to transport water, and compress air to transfer energy to the heat exchanger, and then store the heat energy in the compressed air into the heat storage system through the heat exchanger, and the heat storage system can provide waste heat for the waste heat utilization system.

Description

Technical Field

[0001] The present invention belongs to the technical field of compressed air energy storage, and in particular relates to a combustion-type double-well hydraulic compressed air energy storage system and an operating method thereof. Background Art

[0002] Compressed air energy storage (CAES) is the second most promising technology, after pumped hydro, for large-scale electricity storage at the gigawatt level. Its operating principle is that during periods of low electricity demand, electricity is used to compress air to a high pressure and store it in a cavern or pressure vessel, converting the electricity into the air's internal energy for storage. During peak demand, the high-pressure air is released from the storage chamber to drive a turbine for power generation. This energy storage technology offers several advantages, including long operating time, large capacity, good economic performance, and a high charge-discharge cycle. It has matured and has achieved large-scale commercial application. Its power generation efficiency is 60%, with room for improvement.

[0003] A hydraulic turbine primarily utilizes the gravitational potential energy of water to propel its rotor. Theoretically, the efficiency of utilizing this gravitational potential energy difference can reach 100%. Taking into account the kinetic energy loss of a small amount of upstream water, the actual conversion efficiency can reach 90%. Combining a compressed air energy storage system with a hydraulic turbine power generation system can leverage the advantages of both compressed air energy storage and hydraulic turbine power generation technologies to create an energy storage system with excellent economic efficiency, large capacity, a wide range of charge and discharge cycles, a long operating time, and high efficiency. Summary of the Invention

[0004] In order to solve the problems existing in the prior art, the present invention provides a combustion-type double-well hydraulic compressed air energy storage system and its operation method, which can use valley electricity and abandoned electricity to start the fluid conveying device to transport water, and compress the air to transfer energy to the heat exchanger. The heat energy in the compressed air is then stored in the heat storage system through the heat exchanger. The heat storage system can provide waste heat for the waste heat utilization system.

[0005] In order to achieve the above-mentioned purpose, the technical solution adopted by the present invention is: a combustion-type double-well hydraulic compressed air energy storage system, including a fluid conveying device, a water source, double wells, a turbine, a control system, a burner, a hydrogen supply system, a water electrolysis hydrogen production system, a heat storage system and a heat exchanger; the double well includes a first well and a second well connected to each other at the bottom, the first well is filled with water, and the second well is filled with air, a turbine is arranged at the connection point at the bottom of the double well, the well cover of the second well is provided with an air hole, the second well is connected to the air source through the air hole, the well cover of the first well is provided with a water outlet and a water inlet, and the water outlet and the water inlet are connected to the water source; a heat exchanger is arranged in the second well; the water electrolysis hydrogen production system, the hydrogen supply system and the burner are connected in sequence, the hydrogen supply system is also connected to the heat storage system, and the heat storage system is also connected to the heat exchanger; the heat storage system is connected to the waste heat utilization system.

[0006] The water source is any one of a lake, a pond, the sea, a tank, and a reservoir.

[0007] The heat exchange medium in the heat exchanger is molten salt, oil, liquid metal or water vapor; the heat storage system is any single or mixed heat storage system.

[0008] A fluid conveying device is provided on the pipeline from the water source to the water inlet of the first well. The fluid conveying device adopts a water pump. One or more fluid conveying devices are provided. The control signal input end of the fluid conveying device is connected to the output end of the control system.

[0009] The depth of the double well is 500-1000m, the diameter of a single well is 2-10m, and the double well is U-shaped. The double well is dug below the ground and poured with concrete or seamlessly welded with stainless steel.

[0010] The turbine adopts a vertical turbine or a horizontal turbine.

[0011] A valve is provided at the water outlet of the first well. The valve is a valve with signal input and output, and the actuator of the valve is connected to the control system.

[0012] The burner is a hydrogen and air mixed gas burner.

[0013] A solid-state hydrogen storage device is installed in the hydrogen supply system, and the hydrogen production system adopts water electrolysis or chemical hydrogen production system.

[0014] The operating method of the combustion-type dual-well hydraulic compressed air energy storage system of the present invention includes the following steps:

[0015] a. If the liquid level indicator detects that the liquid level has not reached the set level, the control system will start the fluid conveying device to transport water to the water storage well until the liquid level detected by the liquid level indicator reaches the set level, thus preparing for the start-up of the entire system. During operation, if the liquid level does not reach the set level, a signal will be transmitted to the control system, and the control system will start the fault alarm program;

[0016] b. When the control system detects off-peak electricity consumption or power abandonment, it activates the fluid conveying device to pump water and closes the water inlet of the first well. It also activates the hydrogen production system to produce hydrogen and stores it in the hydrogen supply system for standby use. The fluid conveying device conveys water to the water storage wells of the double wells. The water from the water storage wells gradually enters the air storage wells to compress the air. The air generates heat and stores energy during the compression process. The heat exchanger absorbs the heat energy in the compressed air and stores it in the heat storage system. When the liquid level reading on the liquid level gauge remains unchanged, indicating that the compressed air has reached its compression limit, the fluid conveying device is powered off and stops operating.

[0017] c. When the control system detects peak power consumption or when power is needed, it opens the water outlet of the first well. The thermal storage system transfers part of the heat to the hydrogen supply system and starts releasing hydrogen. The hydrogen is then passed to the burner and mixed with air, where it burns to release heat. Part of the heat from the thermal storage system is sent to the waste heat utilization system, and part of the heat is sent to the air storage well through a heat exchanger and transferred to compressed air. The air expands, causing the liquid water to retreat toward the water storage well, driving the turbine to rotate rapidly and generate electricity. The water in the water storage well flows to the water source.

[0018] d. When air needs to be injected or discharged into the double well, open the valve set on the air hole. When the injection or discharge of air is completed, close the valve.

[0019] Compared with the prior art, the present invention has at least the following beneficial effects:

[0020] The present invention constructs two connected wells and stores air and water in each well. This allows the use of off-peak electricity and abandoned power to activate a fluid conveying device to transport water, and the compressed air to transfer energy to a heat exchanger. The heat energy in the compressed air is then stored in a heat storage system through the heat exchanger, providing waste heat for the waste heat utilization system. When electricity is needed, the heat storage system transfers heat to the hydrogen supply system through the heat exchanger, releasing hydrogen. The heat is then transferred to the compressed air storage well through the heat exchanger, igniting the hydrogen released by the hydrogen supply system. This hydrogen collides with oxygen in the compressed air and burns in the burner, releasing heat. This further increases the compressed air pressure and heat on the air storage side, causing the air to expand and force the liquid water back toward the water storage well, driving the turbine to rotate rapidly and generate power. Water in the water storage well flows through a valve to the water source. This process achieves a power generation efficiency exceeding 90%, and the overall system has a power generation efficiency exceeding 75%. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 The figure is a schematic diagram of a system structure that can be implemented in the present invention.

[0022] In the figure: 1-fluid conveying device, 2-air, 3-water, 4-double well, 5-turbine, 6-valve, 7-control system, 8-liquid level gauge, 9-liquid level indicating device, 10-air hole, 11-burner, 12-hydrogen supply system, 13-water electrolysis hydrogen production system, 14-heat storage system, 15-waste heat utilization system, 16-heat exchanger. DETAILED DESCRIPTION

[0023] The present invention will be further described in detail below with reference to specific embodiments, which are intended to explain the present invention rather than to limit it.

[0024] A system and method for double-well hydraulic compressed air energy storage, comprising a water source, a fluid conveying device 1, an air source, a water source 3, a double well 4, a turbine 5, a valve 6, a control system 7, a liquid level gauge 8, a liquid level indicating device 9, a heat exchanger 11, a hydrogen supply system 12, and a water electrolysis hydrogen production system 13; the double well 4 comprises a first well and a second well interconnected at the bottom, the first well is filled with water, and the second well is filled with air, a turbine 5 is provided at the connection point at the bottom of the double well 4, an air hole 10 is provided on the well cover of the second well, the second well is connected to the air source through the air hole 10, and a water outlet and a water inlet are provided on the well cover of the first well, the water outlet and the water inlet are connected to the water source; a heat exchanger 11 is provided in the second well; the water electrolysis hydrogen production system 13, the hydrogen supply system 12, and the burner 11 are connected in sequence, the hydrogen supply system 12 is also connected to the heat storage system 14, and the heat storage system 14 is also connected to the heat exchanger 16; the heat storage system 14 is connected to the waste heat utilization system.

[0025] Optionally, the water source can be any device or apparatus that can provide water, such as a lake, a pond, the sea, or a sink.

[0026] The fluid conveying device 1 can be any device or equipment that can extract water and deliver it to the water storage end of the double well 4. One or more devices can be set according to specific circumstances.

[0027] The double wells 4 are two wells connected at their lower ends, one of which is mainly used to store air and the other is mainly used to store water, and a turbine is provided at the connecting portion at the lower ends.

[0028] The depth of the twin wells 4 is 500-1000m, the diameter of a single well is 2-10m, and the diameters of the two wells can be the same or different.

[0029] The double well 4 is excavated below ground and constructed with concrete or seamlessly welded stainless steel. It offers excellent overall sealing, mechanical strength, and compressive strength, effectively preventing water and air leakage. The air storage well's top cover features an air hole 10 for replenishing or draining air from the well. The top cover is seamlessly connected and sealed, effectively preventing air leakage. The water storage well has two connections at its top: one connects to the outlet of the fluid delivery device to receive water from the fluid delivery device, and the other connects to a water source via a pipeline to return any overflowing water from the water storage well to the source.

[0030] The water turbine 5 is any water turbine that can convert water into electrical energy or mechanical energy, and can be a vertical or horizontal water turbine.

[0031] The valve 6 adopts any valve with signal input and output, and can be started and stopped according to the signal sent by the control system.

[0032] The control system 7 tracks the supply and demand of the power grid, the rising indication of the liquid level 8 in the water storage well, identifies peak and valley electricity, and controls the start and stop of the fluid conveying device 1 and the valve 6.

[0033] The liquid level meter 8 adopts a liquid level meter with signal output and can monitor the water level; the liquid level indicating device 9 adopts a system or device with signal output that can indicate a specific liquid level. After monitoring that the liquid reaches the set liquid level, the signal is transmitted to the control system 7 before the entire system can be started.

[0034] The burner 11 is a device or apparatus that can be used for mixed combustion of hydrogen and air.

[0035] The hydrogen supply system 12 is any device or equipment that can provide a hydrogen gas source, including solid-state hydrogen storage.

[0036] The hydrogen production system 13 may be a system or device for producing hydrogen by electrolysis of water or chemical hydrogen production.

[0037] The heat exchanger 16 can be any device or equipment that can perform heat exchange, and the heat exchange medium in the heat exchanger 11 can be any medium such as molten salt, oil, liquid metal, and water vapor.

[0038] The heat storage system 14 can be any single or hybrid heat storage system.

[0039] A combustion-type dual-well hydraulic compressed air energy storage system and method specifically includes the following process:

[0040] a. When the liquid level indicator 9 detects that the liquid level has not reached the set level, the control system 7 activates the fluid delivery device to deliver water to the water storage well until the liquid level detected by the liquid level indicator 9 reaches the set level, thus preparing for the start-up of the entire system. During operation, if the liquid level fails to reach the set level, a signal is transmitted to the control system 7, which initiates the fault alarm program.

[0041] b. When control system 7 detects off-peak electricity consumption or power abandonment, it immediately activates the pumping program of fluid conveying device 1 and closes valve 6. It also activates hydrogen production system 13 to produce hydrogen and store it in the hydrogen supply system for future use. Fluid conveying device 1 conveys water to the water storage well of the double well 4. Under the action of gravitational potential energy, the water level in the water storage well moves downward, causing the water in the water storage well to gradually enter the air storage well to compress the air. The air generates heat and stores energy during the compression process. Heat exchanger 11 absorbs the heat energy in the compressed air and stores it in the heat storage system. When the liquid level reading of liquid level gauge 8 remains unchanged, indicating that the compressed air has reached its compression limit, fluid conveying device 1 is powered off and stops operating.

[0042] c. When control system 7 detects peak power demand or when power is needed, it opens valve 6, causing the thermal storage system to transfer some of its heat to the hydrogen supply system 12. This system then releases hydrogen, which then flows to burner 11. The hydrogen collides with oxygen in the air and burns there, releasing heat. A portion of the heat from the thermal storage system is then transferred to waste heat utilization system 15. The remaining heat is then transferred to the air storage well via heat exchanger 16, where it is transferred to compressed air. This ignites the hydrogen-oxygen combustion reaction, further increasing the pressure and heat of the air in the air storage well, causing the air to expand and force the liquid water back toward the water storage well, driving turbine 5 to rotate rapidly and generate electricity. Water from the water storage well then flows through valve 6 to the water source. This process achieves a power generation efficiency exceeding 90%, and the overall system efficiency is >75%.

[0043] d. When air needs to be injected or discharged into the double well, the valve 6 provided on the air hole 10 is opened. When the injection or discharge of air is completed, the valve is closed.

[0044] Example 1

[0045] like Figure 1 As shown, in this embodiment, the system and method of the double-well hydraulic compressed air energy storage of the present invention are used. Figure 1 Implemented on the system.

[0046] The well depth in this embodiment is 600m, the side diameter of the air storage well is 8m, the side diameter of the water storage well is 5m, and the liquid flow rate of the fluid conveying device is 10000m 3 / h, the fluid conveying device has a power of 7kW and a built-in 20,000m 3 Air, using the abandoned electricity of the supercritical Brayton test bench for energy storage, its comprehensive energy utilization efficiency is as high as 75.3%.

Claims

1. A method for operating a combustion-type dual-well hydraulic compressed air energy storage system, characterized in that: The combustion type double-well hydraulic compressed air energy storage system comprises a fluid conveying device (1), a water source (3), a double well (4), a turbine (5), a control system (7), a burner (11), a hydrogen supply system (12), a water electrolysis hydrogen production system (13), a heat storage system (14) and a heat exchanger (16); the double well (4) comprises a first well and a second well interconnected at the bottom, the first well is filled with water, and the second well is filled with air, a turbine (5) is provided at the bottom connection of the double well (4), and a well cover of the second well is provided. The air hole (10) is connected to the air source through the air hole (10), and the well cover of the first well is provided with a water outlet and a water inlet, and the water outlet and the water inlet are connected to the water source; a heat exchanger (16) is provided in the second well; the water electrolysis hydrogen production system (13), the hydrogen supply system (12) and the burner (11) are connected in sequence, the hydrogen supply system (12) is further connected to the heat storage system (14), and the heat storage system (14) is further connected to the heat exchanger (16); the heat storage system (14) is connected to the waste heat utilization system, and the operation includes the following process: a. When the liquid level indicator (9) detects that the liquid level has not reached the set level, the control system (7) starts the fluid conveying device (1) to convey water to the water storage well until the liquid level detected by the liquid level indicator (9) reaches the set level, so as to prepare for the start-up of the entire system. During operation, if the liquid level does not reach the set level, a signal is transmitted to the control system (7), and the control system (7) starts a fault alarm program; b. When the control system (7) detects that the power consumption is at a low point or that there is power abandonment, the fluid conveying device (1) is started to pump water and the water inlet of the first well is closed, and the hydrogen production system (13) is started to prepare hydrogen and store it in the hydrogen supply system for standby use; the fluid conveying device (1) conveys water to the water storage well of the double well (4), and the water in the water storage well gradually enters the air storage well to compress the air. The air generates heat and stores energy during the compression process, and the heat exchanger (16) absorbs the heat energy in the compressed air and stores the heat energy in the heat storage system; when the liquid level reading of the liquid level gauge (8) remains unchanged, it indicates that the compressed air has reached the compression limit, and the fluid conveying device (1) is powered off and stops running; c. When the control system (7) detects peak power consumption or power supply is needed, the water outlet of the first well is opened, and the heat storage system transfers part of the heat to the hydrogen supply system (12), and the hydrogen supply system (12) is opened to release hydrogen. The hydrogen is passed to the burner (11) and mixed with air and then burned in the burner (11) to release heat; part of the heat of the heat storage system is sent to the waste heat utilization system (15), and part of the heat is sent to the air storage well through the heat exchanger (16) and transferred to the compressed air. The air expands, causing the liquid water to retreat to the side of the water storage well, driving the turbine (5) to rotate rapidly to generate power; the water in the water storage well flows to the water source; d. When air needs to be injected or discharged into the double well, the valve (6) provided on the air hole (10) is opened. When the injection or discharge of air is completed, the valve is closed.

2. The operating method according to claim 1, characterized in that: The water source is any one of a lake, a pond, the sea, a tank, and a reservoir.

3. The operating method according to claim 1, characterized in that: The heat exchange medium in the heat exchanger (16) is molten salt, oil, liquid metal or water vapor; the heat storage system (14) is any single or mixed heat storage system.

4. The operating method according to claim 1, characterized in that: A fluid conveying device (1) is provided on a pipeline from a water source (3) to a water inlet of the first well. The fluid conveying device (1) adopts a water pump. One or more fluid conveying devices (1) are provided. A control signal input end of the fluid conveying device (1) is connected to an output end of a control system (7).

5. The operating method according to claim 1, characterized in that: The depth of the double well (4) is 500-1000m, the diameter of the single well is 2-10m, the double well (4) is U-shaped, and the double well (4) is excavated below the ground and cast in concrete or seamlessly welded with stainless steel.

6. The operating method according to claim 1, characterized in that: The water turbine (5) adopts a vertical water turbine or a horizontal water turbine.

7. The operating method according to claim 1, characterized in that: A valve (6) is provided at the water outlet of the first well. The valve (6) is a valve with signal input and output. The actuator of the valve (6) is connected to the control system (7).

8. The operating method according to claim 1, characterized in that: The burner (11) is a hydrogen and air mixed gas burner.

9. The operating method according to claim 1, characterized in that: A solid-state hydrogen storage device is provided in the hydrogen supply system (12), and the hydrogen production system (13) adopts a water electrolysis hydrogen production system or a chemical hydrogen production system.

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