A medium storage module and energy storage system with liquid storage and gas output

Abstract

The present invention discloses a medium storage module and energy storage system with liquid storage and gaseous output; the medium storage module includes two liquid storage tanks and two throttle valves; the two liquid storage tanks are provided with a liquid phase output port, a two-phase input port, a gas phase input port and a gas phase output port. The liquid phase output ports of the two liquid storage tanks are connected to the two-phase input ports of the two liquid storage tanks through independent throttle valves and pipelines, respectively. Phase change materials are stored in both liquid storage tanks. The present invention fills the first low-pressure liquid storage tank and the second low-pressure liquid storage tank with phase change materials, and while storing carbon dioxide, the carbon dioxide is directly contacted with the phase change materials, thereby improving the heat exchange effect of storing carbon dioxide and reducing the demand for phase change materials during the heat exchange process. In addition, the present invention improves the cold and heat storage energy density through the integrated cold storage device and liquid storage device, fully reduces the system usage area, and is conducive to reducing the cost and footprint of the energy storage system.

Description

Technical Field

[0001] The present invention belongs to the technical field of energy storage, and in particular relates to a medium storage module and an energy storage system with liquid storage and gas output. Background Art

[0002] In the context of rapid development of new energy, new energy storage has become one of the key links in building a new power system. Liquid carbon dioxide energy storage converts electrical energy into thermal energy and potential energy of carbon dioxide to achieve energy storage. Compared with air, carbon dioxide is easier to liquefy, does not need to rely on underground caves, and has more flexible site selection. In addition, carbon dioxide has high specific heat capacity, good heat transfer performance, lower parasitic energy consumption, and higher system efficiency. Therefore, liquid carbon dioxide energy storage has the advantages of ultra-long time, large scale, high flexibility, high efficiency, and high energy storage density, and has more development prospects.

[0003] However, the liquid carbon dioxide energy storage system requires a large amount of cold and heat to liquefy and gasify carbon dioxide. The heat transfer coefficient of conventional heat exchangers is low, resulting in the heat exchange system occupying too much space. In addition, the use of conventional low-temperature materials for cold storage (such as methanol) has a low energy storage density and a large energy storage space. Summary of the invention

[0004] The object of the present invention is to provide a medium storage module and an energy storage system with liquid storage and gaseous output.

[0005] In a first aspect, the present invention provides a medium storage module for liquid storage and gaseous output, which includes two liquid storage tanks and two throttle valves; the two liquid storage tanks are provided with a liquid phase output port, a two-phase input port, a gas phase input port and a gas phase output port. The liquid phase output ports of the two liquid storage tanks are connected to the two-phase input ports of the two liquid storage tanks through independent throttle valves and pipelines respectively. Phase change materials are stored in both liquid storage tanks.

[0006] In the initial state, both liquid storage tanks store liquid phase change materials, and one of the liquid storage tanks stores liquid energy storage medium; or the two liquid storage tanks store liquid phase change materials and solid phase change materials respectively. In the liquid storage tanks storing both liquid phase change materials and liquid energy storage medium, the liquid phase change material and the liquid energy storage medium are naturally layered; due to different densities, the liquid energy storage medium is above the liquid phase change material.

[0007] The medium storage module with liquid storage and gas output has two stable states, namely, a stored state and a non-stored state. In the stored state, both liquid storage tanks store liquid phase change materials, and one of the liquid storage tanks stores liquid energy storage medium; in the non-stored state, the two liquid storage tanks store liquid phase change materials and solid phase change materials respectively, and neither of them stores energy storage medium.

[0008] When the energy storage medium needs to be output, the liquid storage tank storing the liquid energy storage medium is used as the output tank, and the other liquid storage tank is used as the vaporization tank. The throttle valve between the liquid phase output port of the output tank and the two-phase input port of the vaporization tank is opened, and the liquid energy storage medium in the output tank passes through the opened throttle valve under the action of the pressure difference, and is converted into a gas-liquid two-phase energy storage medium under the action of throttling gasification, and enters the vaporization tank; the gas-liquid two-phase energy storage medium directly contacts and exchanges heat with the liquid phase change material in the vaporization tank; the liquid phase change material cools down and solidifies, and the gas-liquid two-phase energy storage medium is further vaporized into a gaseous energy storage medium and output;

[0009] When energy storage medium needs to be stored, the gaseous energy storage medium is input into the liquid storage tank containing the solid phase change material; the solid phase change material and the gaseous energy storage medium are in direct contact and heat exchange, and the solid phase change material is liquefied into liquid phase change material; the gaseous energy storage medium is liquefied into liquid energy storage medium for storage.

[0010] In the process of outputting and storing energy storage medium, the internal states of the two liquid storage tanks are exchanged, that is, the original output tank becomes the new vaporization tank; the original vaporization tank becomes the new output tank.

[0011] Preferably, the liquid storage tank is provided with an energy storage medium storage area and a phase change material storage area arranged up and down. The liquid phase output port and the gas phase output port of the liquid storage tank are both connected to the energy storage medium storage area; the two-phase input port and the gas phase input port of the liquid storage tank are both connected to the phase change material storage area.

[0012] Preferably, the liquid phase output port and the gas phase output port are provided at the bottom of the energy storage medium storage area, and the two-phase input port and the gas phase input port are provided at the bottom of the phase change material storage area.

[0013] Preferably, on-off valves are provided at the gas phase inlets and outlets of the two liquid storage tanks.

[0014] Preferably, the energy storage medium gas is carbon dioxide.

[0015] In a second aspect, the present invention provides an energy storage system, which includes a low-pressure liquid storage module, a cold storage component, a compressor, a heat storage component, a high-pressure liquid storage module, a heat release component, an expander and a cold release component, which are sequentially connected to form a circulation loop. The low-pressure liquid storage module adopts the above-mentioned medium storage module; the medium storage module, the cold storage component, the compressor, the heat storage component and the high-pressure liquid storage module form an energy storage path. The gas phase output ports of the two low-pressure liquid storage modules are each connected to the input end of the cold storage component after passing through their corresponding on-off valves; the gas phase input ports of the two low-pressure liquid storage modules are each connected to the output end of the cold release component after passing through their corresponding on-off valves; the high-pressure liquid storage module, the heat release component, the expander, the cold release component and the medium storage module form an energy release path. During operation, the energy storage system switches between the energy storage state and the energy release state.

[0016] In the energy storage state, the gaseous carbon dioxide in the medium storage module is input into the energy storage path under the action of pressure difference, and is stored in the high-pressure liquid storage module through the processes of heating, compressor work and pressurization, and liquefaction.

[0017] In the energy release state, the liquid carbon dioxide in the high-pressure liquid storage module is input into the energy release passage under the action of pressure difference, and is stored in the medium storage module through the processes of gasification, expansion and pressure reduction in the expander to release energy, and cooling.

[0018] Preferably, the heat exchangers in the cold storage component and the cold release component correspond one to one, and a heat storage tank and a cold storage tank are connected in parallel between the two corresponding heat exchangers; the heat storage component and the heat release component correspond one to one, and a heat storage tank and a cold storage tank are connected in parallel between the two corresponding heat exchangers.

[0019] The cold released by the gasification of carbon dioxide in the energy storage state is stored in the cold storage tank by heat exchange between the cold storage component and the heat exchange medium, and is supplied to the liquefied carbon dioxide in the energy release state by heat exchange between the cold release component and the heat exchange medium.

[0020] The heat released by the liquefaction of carbon dioxide in the energy storage state is stored in the heat storage tank by heat exchange between the heat storage component and the heat exchange medium, and is supplied to the gasified carbon dioxide in the energy release state by heat exchange between the heat release component and the heat exchange medium.

[0021] Preferably, the flow of gaseous carbon dioxide is controlled by an on-off valve.

[0022] Preferably, the gas phase input port and the gas phase output port of the two liquid storage tanks in the low-pressure liquid storage module are controlled by an on-off valve; during the energy storage process, the gas phase output port of the liquid storage tank that does not store liquid carbon dioxide is turned on, and the gas phase input port is closed; the gas phase input port and the gas phase output port of the liquid storage tank that has stored liquid carbon dioxide are both closed; during the energy release process, the gas phase input port of the liquid storage tank that stores solid-state phase change materials is turned on, and the gas phase output port is closed; the gas phase input port and the gas phase output port of the liquid storage tank that stores solid-state phase change materials are both closed.

[0023] The present invention has the following beneficial effects:

[0024] 1. The present invention fills the first low-pressure liquid storage tank and the second low-pressure liquid storage tank with phase change material, so that the carbon dioxide directly contacts the phase change material while storing carbon dioxide, thereby improving the heat exchange effect of storing carbon dioxide and reducing the demand for phase change material during the heat exchange process.

[0025] 2. The present invention improves the cold and heat storage energy density through the integrated cold storage device and liquid storage device, fully reduces the system usage area, and is beneficial to reducing the cost and floor space of the energy storage system. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is a schematic diagram of the system structure of Example 1 of the present invention.

[0027] Figure 2 This is a schematic diagram of the system structure of Example 2 of the present invention.

[0028] Figure numerals: 1. low-pressure liquid storage module; 2. cold storage component; 3. compressor; 4. heat storage component; 5. high-pressure liquid storage module; 6. heat release component; 7. expander; 8. cold release component; 1-1. liquid storage tank; 1-2. liquid phase output port; 1-3. two-phase input port; 1-4. gas phase input port; 1-5. gas phase output port; 1-6. throttle valve; 1-7. on-off valve. DETAILED DESCRIPTION

[0029] The present invention will be further described below in conjunction with the accompanying drawings.

[0030] Example 1

[0031] like Figure 1 As shown, a medium storage module includes two liquid storage tanks 1-1 and two throttle valves 1-6; the two liquid storage tanks 1-1 are provided with a carbon dioxide storage area and a phase change material storage area arranged up and down. The two liquid storage tanks 1-1 are provided with a liquid phase output port 1-2, a two-phase input port 1-3, a gas phase input port 1-4 and a gas phase output port 1-5. The liquid phase output port 1-2 and the gas phase output port 1-5 of the liquid storage tank 1-1 are arranged at the top of the carbon dioxide storage area, and the two-phase input port 1-3 and the gas phase output port 1-5 are arranged at the bottom of the phase change material storage area. The liquid phase output ports 1-2 of the two liquid storage tanks 1-1 are connected to the two-phase input ports 1-3 of the two liquid storage tanks 1-1 through independent throttle valves 1-6 and pipelines respectively; the gas phase input ports 1-4 and gas phase output ports 1-5 of the two liquid storage tanks 1-1 are both provided with on-off valves 1-7; the two liquid storage tanks 1-1 both store phase change materials (PCM), which are a mixture of polycarbonate and organic glass, and have a phase change point of 5°C;

[0032] In some embodiments, the gas phase input ports 1 - 4 and the gas phase output ports 1 - 5 share the same output port.

[0033] In the initial state, both liquid storage tanks 1-1 store liquid phase change materials, and one of the liquid storage tanks 1-1 stores liquid carbon dioxide; or the two liquid storage tanks 1-1 store liquid phase change materials and solid phase change materials respectively. In the liquid storage tank 1-1 storing both liquid phase change materials and liquid carbon dioxide, the liquid phase change material and the liquid carbon dioxide are naturally separated into layers; due to different densities, the liquid carbon dioxide is above the liquid phase change material.

[0034] The medium storage module with liquid storage and gas output has two stable states, namely a stored state and a non-stored state. In the stored state, both liquid storage tanks 1-1 store liquid phase change materials, and one of the liquid storage tanks 1-1 stores liquid carbon dioxide; in the non-stored state, the two liquid storage tanks 1-1 store liquid phase change materials and solid phase change materials respectively, and neither stores carbon dioxide.

[0035] When it is necessary to output carbon dioxide, the liquid storage tank 1-1 storing liquid carbon dioxide is used as the output tank, and the other liquid storage tank 1-1 is used as the gasification tank. The throttle valve 1-6 between the liquid phase output port 1-2 of the output tank and the two-phase input port 1-3 of the gasification tank is opened, and the liquid carbon dioxide in the output tank passes through the opened throttle valve 1-6 under the action of pressure difference, and is converted into gas-liquid two-phase carbon dioxide under the action of throttling gasification and enters the gasification tank; the gas-liquid two-phase carbon dioxide is in direct contact with the liquid phase change material in the gasification tank for heat exchange; the liquid phase change material cools down and solidifies, and the gas-liquid two-phase carbon dioxide is further gasified into gaseous carbon dioxide and output;

[0036] When carbon dioxide needs to be stored, gaseous carbon dioxide is input into the liquid storage tank 1-1 storing the solid phase change material; the solid phase change material and the gaseous carbon dioxide are in direct contact for heat exchange, and the solid phase change material is liquefied into liquid phase change material; the gaseous carbon dioxide is liquefied into liquid carbon dioxide for storage.

[0037] In a process of outputting and storing carbon dioxide, the internal states of the two liquid storage tanks 1-1 are interchanged, that is, the original output tank becomes a new gasification tank; the original gasification tank becomes a new output tank.

[0038] Example 2

[0039] like Figure 2 As shown, an energy storage system includes a low-pressure liquid storage module 1, a cold storage component 2, a compressor 3, a heat storage component 4, a high-pressure liquid storage module 5, a heat release component 6, an expander 7 and a cold release component 8 which are sequentially connected to form a circulation loop. The low-pressure liquid storage module 1 adopts the medium storage module in Example 1; the cold storage component 2 and the cold release component 8 both include a heat exchanger, and a heat storage tank and a cold storage tank are connected in parallel between the two heat exchangers; the heat storage component 4 and the heat release component 6 both include two heat exchangers connected in series, and the heat exchangers of the heat storage component 4 and the heat release component 6 correspond one to one, and a heat storage tank and a cold storage tank are connected in parallel between the corresponding two heat exchangers.

[0040] In some embodiments, the cold storage component 2 and the cold release component 8 each include two heat exchangers, the heat exchangers of the cold storage component 2 and the cold release component 8 correspond one to one, and a heat storage tank and a cold storage tank are connected in parallel between the corresponding two heat exchangers.

[0041] During operation, the energy storage system switches between the energy storage state and the energy release state; in the energy storage state, the low-pressure liquid storage module 1 inputs the gaseous carbon dioxide into the cold storage component 2 through the on-off valve; the heat exchange medium is provided to the heat exchanger through the heat storage tank, so that the gaseous carbon dioxide is heated in the cold storage component 2, and the gaseous carbon dioxide is output, and the heat exchange medium is transported to the cold storage tank for storage. The gaseous carbon dioxide output by the cold storage component 2 is input to the compressor 3 through the on-off valve, and the compressor 3 consumes electric energy to pressurize the gaseous carbon dioxide. After obtaining the gaseous carbon dioxide, it is input to the heat storage component 4 through the on-off valve. The two heat exchangers in the heat storage component 4 respectively use the heat exchange medium input by the corresponding cold storage tank to gradually cool the gaseous carbon dioxide in the heat storage component 4, obtain liquid carbon dioxide, and transport it to the high-pressure liquid storage module 5 for storage, and the heat exchange medium in the two heat exchangers is transported to the corresponding heat storage tank for storage, completing energy storage.

[0042] In the energy release state, the liquid carbon dioxide in the high-pressure liquid storage module 5 is input into the heat release component 6. The two heat exchangers in the heat release component 6 respectively input the heat exchange medium through the corresponding heat storage tank, so that the liquid carbon dioxide is gradually heated in the heat release component 6 and outputs gaseous carbon dioxide. The heat exchange medium in the two heat exchangers is transported to the corresponding cold storage tank for storage; the gaseous carbon dioxide output by the heat release component 6 enters the expansion machine 7 through the on-off valve, and the expansion machine 7 performs external work through the expansion of the gaseous carbon dioxide, converts the gaseous carbon dioxide into gaseous carbon dioxide output, and releases energy to complete the energy release. The gaseous carbon dioxide output by the expansion machine 7 is input into the cold release component 8 through the on-off valve; the heat exchange medium is provided to the heat exchanger through the cold storage tank, so that the gaseous carbon dioxide is cooled in the cold release component 8, the gaseous carbon dioxide is obtained and transported to the low-pressure liquid storage module 1 for storage, and the heat exchange medium is transported to the heat storage tank for storage.

[0043] The above-described embodiment is only a preferred solution of the present invention, but it is not intended to limit the present invention. A person skilled in the relevant technical field may make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, any technical solution obtained by equivalent replacement or equivalent transformation falls within the protection scope of the present invention.

Claims

1. A medium storage module with liquid storage and gaseous output, characterized in that: The invention comprises two liquid storage tanks (1-1) and two throttle valves (1-6); the two liquid storage tanks (1-1) are provided with a liquid phase output port (1-2), a two-phase input port (1-3), a gas phase input port (1-4) and a gas phase output port (1-5); the liquid phase output ports (1-2) of the two liquid storage tanks (1-1) are connected to the two-phase input ports (1-3) of the two liquid storage tanks (1-1) through independent throttle valves (1-6) and pipelines respectively; and phase change materials are stored in the two liquid storage tanks (1-1); In an initial state, both liquid storage tanks (1-1) store liquid phase change material and one of the liquid storage tanks (1-1) stores liquid energy storage medium, or one of the liquid storage tanks (1-1) stores liquid phase change material and the other liquid storage tank (1-1) stores solid phase change material; in the liquid storage tank (1-1) storing both liquid phase change material and liquid energy storage medium, the liquid phase change material and the liquid energy storage medium are naturally layered; the liquid energy storage medium is located above the liquid phase change material; The medium storage module for liquid storage and gaseous output has two stable states, namely a stored state and a non-stored state; in the stored state, both liquid storage tanks (1-1) store liquid phase change material, and one of the liquid storage tanks (1-1) stores liquid energy storage medium; in the non-stored state, one liquid storage tank (1-1) stores liquid phase change material, and the other liquid storage tank (1-1) stores solid phase change material, and neither stores energy storage medium.

2. A medium storage module for liquid storage and gaseous output according to claim 1, characterized in that: The liquid storage tank (1-1) is provided with an energy storage medium storage area and a phase change material storage area arranged in an upper and lower manner; the liquid phase output port (1-2) and the gas phase output port (1-5) of the liquid storage tank (1-1) are both connected to the energy storage medium storage area; and the two-phase input port (1-3) and the gas phase input port (1-4) of the liquid storage tank (1-1) are both connected to the phase change material storage area.

3. A medium storage module for liquid storage and gaseous output according to claim 2, characterized in that: The liquid phase output port (1-2) and the gas phase output port (1-5) are provided at the bottom of the energy storage medium storage area, and the two-phase input port (1-3) and the gas phase input port (1-4) are provided at the bottom of the phase change material storage area.

4. The medium storage module for liquid storage and gaseous output according to claim 1, characterized in that: On-off valves (1-7) are provided at the gas phase input ports (1-4) and gas phase output ports (1-5) of the two liquid storage tanks (1-1).

5. The medium storage module for liquid storage and gaseous output according to claim 1, characterized in that: The energy storage medium is carbon dioxide.

6. The working method of the medium storage module with liquid storage and gaseous output as claimed in claim 1, characterized in that: When the energy storage medium needs to be output, a liquid storage tank (1-1) storing liquid energy storage medium is used as an output tank, and another liquid storage tank (1-1) is used as a vaporization tank; a throttle valve (1-6) between the liquid phase output port (1-2) of the output tank and the two-phase input port (1-3) of the vaporization tank is opened, and the liquid energy storage medium in the output tank passes through the opened throttle valve (1-6) under the action of pressure difference, and is converted into a gas-liquid two-phase energy storage medium under the action of throttling gasification, and enters the vaporization tank; the gas-liquid two-phase energy storage medium directly contacts and exchanges heat with the liquid phase change material in the vaporization tank; the liquid phase change material cools down and solidifies, and the gas-liquid two-phase energy storage medium is further vaporized into a gaseous energy storage medium and output; When energy storage medium needs to be stored, the gaseous energy storage medium is input into a liquid storage tank (1-1) containing a solid phase change material; the solid phase change material and the gaseous energy storage medium are in direct contact and heat exchange, and the solid phase change material is liquefied into a liquid phase change material; the gaseous energy storage medium is liquefied into a liquid energy storage medium for storage; In a process of outputting and storing energy storage medium, the internal states of the two liquid storage tanks (1-1) are exchanged, that is, the original output tank becomes a new vaporization tank; and the original vaporization tank becomes a new output tank.

7. An energy storage system, comprising a low-pressure liquid storage module (1), a cold storage component (2), a compressor (3), a heat storage component (4), a high-pressure liquid storage module (5), a heat release component (6), an expander (7) and a cold release component (8) which are sequentially connected to form a circulation loop; characterized in that: The low-pressure liquid storage module (1) adopts a medium storage module for liquid storage and gaseous output as claimed in claim 5; the medium storage module, the cold storage component (2), the compressor (3), the heat storage component (4) and the high-pressure liquid storage module (5) form an energy storage path; the high-pressure liquid storage module (5), the heat release component (6), the expander (7), the cold release component (8) and the medium storage module form an energy release path; during operation, the energy storage system switches between an energy storage state and an energy release state; In the energy storage state, the gaseous energy storage medium output by the low-pressure liquid storage module (1) is input into the energy storage passage, and is sequentially stored in the high-pressure liquid storage module (5) through the processes of heating, pressurization by the compressor (3), and liquefaction; In the energy release state, the liquid energy storage medium in the high-pressure liquid storage module (5) is input into the energy release passage, and is stored in the low-pressure liquid storage module (1) through the processes of gasification, expansion and pressure reduction in the expander (7) to release energy, and temperature reduction.

8. An energy storage system according to claim 7, characterized in that: The cold storage component (2) and the cold release component (8) both include one or a plurality of heat exchangers connected in sequence; the heat storage component (4) and the heat release component (6) both include one or a plurality of heat exchangers connected in sequence.

9. An energy storage system according to claim 7, characterized in that: The heat exchangers in the cold storage component (2) and the cold release component (8) correspond one to one, and the two corresponding heat exchangers are connected to the heat storage tank and the cold storage tank to form a heat exchange circulation loop; the heat storage component (4) and the heat release component (6) correspond one to one, and the two corresponding heat exchangers are connected to the heat storage tank and the cold storage tank to form a heat exchange circulation loop; In the energy storage state, the cold energy released by the gasification of the energy storage medium is stored in the cold storage tank by means of heat exchange between the heat exchanger in the cold storage component (2) and the heat exchange medium, and in the energy release state, the cold energy released by the gasification of the energy storage medium is supplied to the liquefied energy storage medium by means of heat exchange between the heat exchanger in the cold release component (8) and the heat exchange medium; In the energy storage state, the heat released by the liquefaction of the energy storage medium is stored in the heat storage tank by means of heat exchange between the heat exchanger in the heat storage component (4) and the heat exchange medium, and in the energy release state, the heat is supplied to the gasified energy storage medium by means of heat exchange between the heat exchanger in the heat release component (6) and the heat exchange medium.

10. An energy storage system according to claim 7, characterized in that: The gas phase input ports (1-4) and gas phase output ports (1-5) of the two liquid storage tanks (1-1) in the low-pressure liquid storage module (1) are controlled to be on and off by an on-off valve; during the energy storage process, the gas phase output port (1-5) of the liquid storage tank (1-1) that does not store liquid energy storage medium is turned on, and the gas phase input port (1-4) is closed; the gas phase input port (1-4) and gas phase output port (1-5) of the liquid storage tank (1-1) that has stored liquid energy storage medium are both closed; during the energy release process, the gas phase input port (1-4) of the liquid storage tank (1-1) that stores solid phase change material is turned on, and the gas phase output port (1-5) is closed; the gas phase input port (1-4) and gas phase output port of the liquid storage tank (1-1) that stores solid phase change material are both closed.

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