Compressed gas energy storage system and method combined with pumped storage

Abstract

The invention discloses a compressed gas energy storage system and method combined with pumped storage, and relates to the technical field of compressed gas energy storage. The compressed gas energy storage system comprises a compressor, an expansion machine, a high-pressure gas storage tank, a low-pressure gas storage tank and a pump turbine, the pump turbine is connected with the high-pressure gas storage tank and the low-pressure gas storage tank, and the low-pressure gas storage tank is connected with a control valve; the control valve is connected with the compressor, the compressor is connected with the high-pressure air storage tank, the high-pressure air storage tank is connected with the throttling valve, the throttling valve is connected with the expansion machine, and the expansion machine is connected with the low-pressure air storage tank. According to the compressed gas energy storage system and method combined with pumped storage, the change of pressure difference in the system operation process is reduced, meanwhile, potential energy of water is utilized for power generation, and the utilization rate of gas in the system and the circulation efficiency of the system are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of compressed gas energy storage, and in particular to a compressed gas energy storage system and method combined with pumped storage. Background Art

[0002] The instability and discontinuity of renewable energy generation can impact the grid during the integration process. Energy storage systems can mitigate the volatility of renewable energy generation and help shift peaks and valleys. Currently, megawatt-scale and long-term energy storage technologies primarily include pumped hydro and compressed gas storage. Compressed gas storage, a technology with high energy density and no geographical restrictions, has attracted widespread attention.

[0003] Currently, the research on compressed gas energy storage technology is relatively mature. The inventors believe that this technology has the following problems:

[0004] 1. In traditional compressed gas energy storage systems, the gas in the high-pressure tank cannot fully expand and perform work when releasing energy, resulting in low gas utilization and energy loss.

[0005] 2. In traditional compressed gas energy storage systems, as the energy storage process progresses, the pressure in the high-pressure tank increases, while the pressure in the low-pressure tank decreases. This increases the pressure differential across the compressor, reduces gas flow, and increases power consumption. During the energy release phase, the pressure in the high-pressure tank decreases, while the pressure in the low-pressure tank increases. This decreases the pressure differential across the expander, reduces gas flow, and reduces the work performed by the expander. This change in pressure differential affects the system's cycle efficiency. Summary of the Invention

[0006] The purpose of the present invention is to provide a compressed gas energy storage system and method combined with pumped storage, which can reduce the change of pressure difference during system operation, generate electricity by using the potential energy of water, and improve the utilization rate and circulation efficiency of the working fluid in the compressed gas energy storage system.

[0007] To achieve the above objectives, the present invention provides a compressed gas energy storage system combined with pumped storage, including a compressor, an expander, a high-pressure gas storage tank, a low-pressure gas storage tank and a water pump turbine, wherein the water pump turbine is connected to the high-pressure gas storage tank and the low-pressure gas storage tank, the low-pressure gas storage tank is connected to a control valve, the control valve is connected to the compressor, the compressor is connected to the high-pressure gas storage tank, the high-pressure gas storage tank is connected to a throttle valve, the throttle valve is connected to the expander, and the expander is connected to the low-pressure gas storage tank.

[0008] Preferably, water and gas are provided in both the low-pressure gas storage tank and the high-pressure gas storage tank, and a partition is provided between the gas and the water.

[0009] Preferably, the partition is movably arranged in the low-pressure gas storage tank and the high-pressure gas storage tank.

[0010] Preferably, the low-pressure gas storage tank is arranged at a height higher than that of the high-pressure gas storage tank.

[0011] A method for compressing gas combined with pumped storage includes a storage phase and a release phase. In the release phase, the gas in a high-pressure gas storage tank is pressurized and water is released to generate electricity. In the storage phase, the gas in a low-pressure gas storage tank is pressurized and pumped for storage.

[0012] Preferably, the energy storage stage includes the following steps:

[0013] Step 1: Close the throttle valve and open the control valve;

[0014] Step 2: The compressor compresses the gas in the low-pressure gas storage tank, and the compressed gas enters the high-pressure gas storage tank;

[0015] Step 3: Gas pressurization: Electricity drives the water pump turbine to pump water from the high-pressure gas storage tank to the top of the low-pressure gas storage tank, increasing the gas pressure in the low-pressure tank.

[0016] Preferably, the energy release stage comprises the following steps:

[0017] Step 1: Open the throttle valve and close the control valve;

[0018] Step 2: The gas in the high-pressure gas storage tank drives the expander to perform work and output electrical energy, and the expanded gas enters the low-pressure gas storage tank;

[0019] Step 3: The water above the low-pressure gas storage tank drives the water pump turbine to generate electricity. The water in the low-pressure gas storage tank enters the high-pressure gas storage tank, and the pressure in the high-pressure gas storage tank increases.

[0020] Therefore, the present invention utilizes the aforementioned compressed gas energy storage system and method combined with pumped storage. Water is pumped from the top of the high-pressure gas storage tank to the top of the low-pressure gas storage tank via a pump-turbine, reducing the pressure differential across the compressor during energy storage and the power consumption during storage. The water above the low-pressure gas storage tank flows through the pump-turbine via the height difference and flows into the top of the high-pressure gas storage tank, increasing the pressure differential across the expander during energy release, boosting the work done during energy release and fully utilizing the potential energy of the water for power generation. This allows more gas to participate in the cycle, increasing gas flow, improving gas utilization, and enhancing the system's cycle efficiency.

[0021] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 Schematic diagram of the energy storage process of the compressed gas energy storage system of the present invention;

[0023] Figure 2 Schematic diagram of the energy release process of the compressed gas energy storage system of the present invention;

[0024] Reference numerals

[0025] 1. High-pressure gas storage tank; 2. Throttle valve; 3. Expander; 4. Low-pressure gas storage tank; 5. Control valve; 6. Compressor; 7. Water pump and turbine; 8. Partition. DETAILED DESCRIPTION

[0026] The technical solution of the present invention is further described below with reference to the accompanying drawings and embodiments.

[0027] Unless otherwise defined, the technical or scientific terms used in the present invention shall have the usual meanings understood by persons of ordinary skill in the field to which the present invention belongs. The words "first", "second" and similar terms used in the present invention do not indicate any order, quantity or importance, but are only used to distinguish different components. Words such as "include" or "comprise" mean that the elements or objects preceding the word include the elements or objects listed after the word and their equivalents, without excluding other elements or objects. Words such as "connect" or "connected" are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. "Up", "down", "left", "right" and the like are only used to indicate relative positional relationships. When the absolute position of the object being described changes, the relative positional relationship may also change accordingly.

[0028] Example

[0029] See also Figure 1-Figure 2 The present invention provides a compressed gas energy storage system combined with pumped storage, including a compressor 6, an expander 3, a high-pressure gas storage tank 1, a low-pressure gas storage tank 4 and a water pump turbine 7, the water pump turbine 7 is connected to the high-pressure gas storage tank 1 and the low-pressure gas storage tank 4, the low-pressure gas storage tank 4 is connected to the control valve 5, the control valve 5 is connected to the compressor 6, the compressor 6 is connected to the high-pressure gas storage tank 1, the high-pressure gas storage tank 1 is connected to the throttle valve 2, the throttle valve 2 is connected to the expander 3, and the expander 3 is connected to the low-pressure gas storage tank 4.

[0030] Both the low-pressure gas storage tank 4 and the high-pressure gas storage tank 1 contain water and gas, with a partition 8 positioned between the gas and water. The partition 8 is movable within the low-pressure gas storage tank 4 and the high-pressure gas storage tank 1. The low-pressure gas storage tank 4 is positioned higher than the high-pressure gas storage tank 1. A pump-turbine 7 pumps water above the partition 8 in the low-pressure gas storage tank 4, pressurizing the gas in the low-pressure gas storage tank 4 and generating pumped water energy. Water from above the low-pressure gas storage tank 4 flows through the pump-turbine 7 into the high-pressure gas storage tank 1, pressurizing the gas in the high-pressure gas storage tank 1 and releasing water for power generation.

[0031] A method for compressing gas combined with pumped storage includes a storage phase and a release phase. During the storage phase, a water pump pumps water to the top of a low-pressure gas tank 4, where the gravity of the water pressurizes the gas in the tank, reducing the pressure differential across the compressor and lowering power consumption. During the release phase, due to the height difference, the water in the tank 4 generates power through a pump-turbine 7, then flows into the high-pressure gas tank 1, pressurizing the gas there. This increases the pressure differential across the expander and boosts power output.

[0032] The energy storage phase includes the following steps:

[0033] Step 1: Close the throttle valve 2 and open the control valve 5;

[0034] Step 2: The compressor 6 compresses the gas in the low-pressure gas storage tank 4, and the compressed gas enters the high-pressure gas storage tank 1;

[0035] Step 3: Gas pressurization: Electricity drives the water pump turbine 7 to pump water from the high-pressure gas storage tank 1 to the top of the low-pressure gas storage tank 4, thereby increasing the gas pressure in the low-pressure gas storage tank 4.

[0036] During periods of low electricity consumption, energy is stored. Excess electricity drives pump-turbine 7, which pumps water from high-pressure gas storage tank 1 to the top of low-pressure gas storage tank 4. Throttle valve 2 closes, and control valve 5 opens. Excess electricity drives compressor 6, compressing gas from low-pressure gas storage tank 4. The compressed gas is then stored in high-pressure gas storage tank 1.

[0037] The energy release phase includes the following steps:

[0038] Step 1: Open the throttle valve 2 and close the control valve 5;

[0039] Step 2: The gas in the high-pressure gas storage tank 1 drives the expander 3 to perform work and output electrical energy, and the expanded gas enters the low-pressure gas storage tank 4;

[0040] Step 3: The water above the low-pressure gas storage tank 4 drives the water pump turbine 7 to generate power. The water in the low-pressure gas storage tank 4 enters the high-pressure gas storage tank 1, and the pressure in the high-pressure gas storage tank 1 increases.

[0041] During peak electricity demand, the water above the low-pressure gas storage tank 4 drives the pump-turbine 7 to generate power, which then flows into the upper portion of the high-pressure gas storage tank 1. The throttle valve 2 opens, and the control valve 5 closes. The high-temperature, high-pressure gas from the high-pressure gas storage tank 1 drives the expander 3 to generate power and output electricity. The expanded gas then flows into the low-pressure gas storage tank 4.

[0042] Therefore, the present invention utilizes the aforementioned compressed gas energy storage system and method combined with pumped storage. Water is pumped from the top of the high-pressure gas storage tank to the top of the low-pressure gas storage tank via a pump-turbine, reducing the pressure differential across the compressor during energy storage and the power consumption during storage. The water above the low-pressure gas storage tank flows through the pump-turbine via the height difference and flows into the top of the high-pressure gas storage tank, increasing the pressure differential across the expander during energy release, boosting the work done during energy release and fully utilizing the potential energy of the water for power generation. This allows more gas to participate in the cycle, increasing gas flow, improving gas utilization, and enhancing the system's cycle efficiency.

[0043] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit the same. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that they can still modify or replace the technical solutions of the present invention with equivalents, and these modifications or equivalent replacements cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A compressed gas energy storage system combined with pumped storage, characterized by: It includes a compressor, an expander, a high-pressure gas storage tank, a low-pressure gas storage tank and a water pump turbine. The water pump turbine is connected to the high-pressure gas storage tank and the low-pressure gas storage tank, the low-pressure gas storage tank is connected to a control valve, the control valve is connected to the compressor, the compressor is connected to the high-pressure gas storage tank, the high-pressure gas storage tank is connected to a throttle valve, the throttle valve is connected to the expander, and the expander is connected to the low-pressure gas storage tank.

2. A compressed gas energy storage system combined with pumped storage according to claim 1, characterized in that: Water and gas are both provided in the low-pressure gas storage tank and the high-pressure gas storage tank, and a partition is provided between the gas and the water.

3. A compressed gas energy storage system combined with pumped storage according to claim 2, characterized in that: The partition is movably arranged in the low-pressure gas storage tank and the high-pressure gas storage tank.

4. A compressed gas energy storage system combined with pumped storage according to claim 3, characterized in that: The low-pressure gas storage tank is arranged at a height higher than that of the high-pressure gas storage tank.

5. A method for combining compressed gas with pumped storage, using the compressed gas energy storage system combined with pumped storage as claimed in any one of claims 1 to 4, characterized in that: It includes the energy storage stage and the energy release stage. In the energy release stage, the gas in the high-pressure gas tank is pressurized and water is released to generate electricity. In the energy storage stage, the gas in the low-pressure gas tank is pressurized and pumped for energy storage.

6. A method for compressing gas in combination with pumped storage according to claim 5, characterized in that: The energy storage phase includes the following steps: Step 1: Close the throttle valve and open the control valve; Step 2: The compressor compresses the gas from the low-pressure gas storage tank, and the compressed gas enters the high-pressure gas storage tank; Step 3: While the compressor is working, the gas is pressurized, and electricity drives the water pump turbine to pump water from the high-pressure gas storage tank to the top of the low-pressure gas storage tank, increasing the gas pressure in the low-pressure tank.

7. The method for compressing gas in combination with pumped storage according to claim 5, characterized in that: The energy release phase includes the following steps: Step 1: Open the throttle valve and close the control valve; Step 2: The gas in the high-pressure gas storage tank drives the expander to perform work and output electrical energy, and the expanded gas enters the low-pressure gas storage tank; Step 3: The water above the low-pressure gas storage tank drives the water pump turbine to generate electricity. The water in the low-pressure gas storage tank enters the high-pressure gas storage tank, and the pressure in the high-pressure gas storage tank increases.

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