A carbon dioxide phase change energy storage system and method

Abstract

The present application provides a carbon dioxide phase change energy storage system and method, comprising a first phase change conversion element, a liquid storage element, a second phase change conversion element, and a hot component and a cold component connected in sequence; the hot component and the cold component are respectively connected between the first phase change conversion element and the second phase change conversion element; the first phase change conversion element is used for the first phase change of carbon dioxide from gas phase to liquid phase, and the second phase change conversion element is used for the second phase change of carbon dioxide from liquid phase to gas phase; the liquid storage element is used to store liquid carbon dioxide generated by the first phase change, and gaseous carbon dioxide for pressure maintenance, and the liquid carbon dioxide is used to be supplied to the second phase change conversion element for the second phase change; the hot component is used to supply the heat exchange medium after the first phase change to the second phase change conversion element for the second phase change, and the cold component is used to supply the heat exchange medium after the second phase change to the first phase change conversion element for the first phase change.

Description

Technical Field

[0001] The present application belongs to the field of energy storage technology, and more specifically, to a carbon dioxide phase change energy storage system and method. Background Art

[0002] For the carbon dioxide phase change energy storage process, during the energy storage process, the low-temperature and low-pressure gaseous carbon dioxide is compressed by the compressor to increase the pressure and temperature. The high-temperature and high-pressure gaseous carbon dioxide exchanges heat with the heat storage medium and stores the heat energy in the heat storage medium. The high-pressure carbon dioxide cooled by the heat storage medium is further cooled by cold water and condensed into liquid carbon dioxide for storage. During the energy release process, the liquid carbon dioxide is heated by hot water to evaporate it into a gaseous state, and then heated by the stored heat storage medium to become high-temperature and high-pressure carbon dioxide to do work. After doing work, it becomes low-pressure carbon dioxide, completing a cycle of energy storage and release.

[0003] In the existing carbon dioxide energy storage and release process, the condensation process and evaporation process of carbon dioxide require the consumption of cold water and hot water respectively. The energy storage and release system needs to be equipped with a hot water station corresponding to the condensation process and a cold water station corresponding to the evaporation process. The hot water station and the cold water station are configured and used separately, which increases the complexity of the system configuration and the hardware investment cost of the system. Summary of the invention

[0004] The purpose of the embodiments of the present application is to provide a carbon dioxide phase change energy storage system and method to solve the technical problem that the existing carbon dioxide energy storage and release system uses separate hot water stations and cold water stations to participate in the energy storage and release process, which leads to increased system configuration complexity and investment costs.

[0005] To achieve the above purpose, the technical solution adopted in this application is:

[0006] Provided is a carbon dioxide phase change energy storage system, comprising a first phase change conversion element, a liquid storage element, a second phase change conversion element, and a hot component and a cold component connected in sequence; the hot component and the cold component are respectively connected between the first phase change conversion element and the second phase change conversion element;

[0007] The first phase change conversion element is used for the carbon dioxide to undergo a first phase change from gas phase to liquid phase, and the second phase change conversion element is used for the carbon dioxide to undergo a second phase change from liquid phase to gas phase; the liquid storage element is used to store the liquid phase carbon dioxide generated by the first phase change and the gas phase carbon dioxide for pressure maintenance, and the liquid phase carbon dioxide is used to be supplied to the second phase change conversion element to undergo the second phase change;

[0008] The hot component is used to supply the heat exchange medium after the first phase change to the second phase change converter for use in the second phase change, and the cold component is used to supply the heat exchange medium after the second phase change to the first phase change converter for use in the first phase change.

[0009] In some embodiments, the liquid storage element has a liquid phase port and a gas phase port, and the liquid phase port connects the liquid phase outlet of the first phase change conversion element and the liquid phase inlet of the second phase change conversion element;

[0010] The phase change energy storage system further includes a gas phase balance tube, one port of which is connected to the gas phase inlet of the first phase change converter, and the other port of which is directly or indirectly connected to the gas phase port.

[0011] In some embodiments, the phase change energy storage system includes a plurality of the liquid storage components and a liquid phase main pipe;

[0012] The liquid inlet of the liquid phase main pipe is connected to the liquid phase outlet of the first phase change converter, the liquid outlet of the liquid phase main pipe is connected to the liquid phase inlet of the second phase change converter, and the multiple liquid phase ports of the multiple liquid storage components are respectively connected to the liquid phase main pipe.

[0013] In some embodiments, the phase change energy storage system further includes a gas phase main pipe, and the multiple gas phase ports of the multiple liquid storage components are respectively connected to the gas phase main pipe; wherein the gas phase port is arranged at the top of the liquid storage component, and the liquid phase port is arranged at the bottom of the liquid storage component.

[0014] In some embodiments, the plurality of liquid storage elements are arranged at the same height, and the height of the first phase change converter is higher than the height of the liquid storage element.

[0015] In some embodiments, the phase change energy storage system further includes a gas-liquid two-phase separation element;

[0016] The gas-liquid two-phase separator is connected between the liquid storage element and the second phase-change converter, and is used to separate gaseous carbon dioxide from the liquid carbon dioxide to supply the liquid carbon dioxide to the second phase-change converter separately.

[0017] In some embodiments, the height of the gas-liquid two-phase separation element is higher than the height of the second phase change conversion element.

[0018] In some embodiments, the gas-liquid two-phase separator has a gas-liquid inlet, a liquid phase separation port and a gas phase separation port, the liquid phase separation port is arranged at the bottom of the gas-liquid two-phase separator, the gas phase separation port is arranged at the top of the gas-liquid two-phase separator, and the gas-liquid inlet is arranged in the middle of the gas-liquid two-phase separator;

[0019] The liquid phase inlet of the second phase change conversion element is arranged at the bottom of the second phase change conversion element, and the gas phase outlet of the second phase change conversion element is arranged at the top of the second phase change conversion element;

[0020] Among them, the liquid phase port of the liquid storage component is connected to the gas-liquid inlet, and the liquid phase separation port is connected to the liquid phase inlet; the phase change energy storage system also includes a gas phase exhaust pipe, and the gas phase separation port and the gas phase outlet are both connected to the gas phase exhaust pipe.

[0021] In some embodiments, the thermal assembly includes a heat pipe, and a hot water tank and a hot water pump sequentially arranged on the heat pipe, and the heat pipe connects the heat medium outlet of the first phase change conversion element and the heat medium inlet of the second phase change conversion element;

[0022] The cold assembly includes a cold pipe, and a cold water tank and a cold water pump sequentially arranged on the cold pipe, and the cold pipe connects the cold medium inlet of the first phase change conversion component and the cold medium outlet of the second phase change conversion component.

[0023] In some embodiments, the phase change energy storage system further comprises a pressure reducing valve, which is arranged on the liquid phase main pipe between the second phase change converter and the liquid storage component closest thereto;

[0024] A liquid shut-off valve is provided on the path where the liquid phase port of each liquid storage component is connected to the liquid phase main pipe.

[0025] The beneficial effects of the carbon dioxide phase change energy storage system provided by the present application are:

[0026] Compared with the prior art, the carbon dioxide phase change energy storage system provided by the present application includes a first phase change conversion component, a liquid storage component, a second phase change conversion component, and a hot component and a cold component connected in sequence. Among them, the hot component is connected between the first phase change conversion component and the second phase change conversion component, and the cold component is connected between the first phase change conversion component and the second phase change conversion component. Among them, the first phase change conversion component is used for the first phase change of carbon dioxide from gas phase to liquid phase, and the second phase change conversion component is used for the second phase change of carbon dioxide from liquid phase to gas phase. The liquid storage component is used to store liquid carbon dioxide generated by the first phase change, and gaseous carbon dioxide for pressure maintenance. Among them, the hot component is used to supply the heat exchange medium after the first phase change to the second phase change conversion component for use in the second phase change, and the cold component is used to supply the heat exchange medium after the second phase change to the first phase change conversion component for use in the first phase change.

[0027] During the energy storage step of the system, the gaseous carbon dioxide passes through the first phase change conversion element and exchanges heat with the heat exchange medium provided by the cold component for the first phase change, thereby undergoing a first phase change from gas phase to liquid phase. The generated liquid carbon dioxide enters the liquid storage element, and the liquid storage element stores liquid carbon dioxide at a set liquid level and gaseous carbon dioxide at a set pressure.

[0028] In this way, the liquid storage element can store gaseous carbon dioxide for pressure maintenance. In the process of the liquid storage element providing liquid carbon dioxide to the second phase change conversion element, the internal pressure of the liquid storage element decreases. According to the physical properties of liquid carbon dioxide, the saturation temperature of the liquid carbon dioxide after decompression decreases, so that the evaporation temperature of the liquid carbon dioxide is lower than the condensation temperature of the liquid carbon dioxide. Since there is a certain temperature difference between the evaporation temperature and the condensation temperature, the evaporation process can use the heat exchange medium generated by the condensation process for evaporation, and the heat exchange medium can be used in the condensation process after the evaporation process, thereby achieving the recycling of heat exchange media with different cold and hot temperatures.

[0029] Furthermore, in the energy release step, since the liquid storage component stores gaseous carbon dioxide for pressure maintenance in the energy storage step to ensure that the pressure inside the liquid storage component is higher than the pressure of the first phase change conversion component, the liquid carbon dioxide directly or indirectly enters the second phase change conversion component driven by the pressure difference between the liquid storage component and the second phase change conversion component, and exchanges heat with the heat exchange medium provided by the thermal component for the second phase change, thereby causing a second phase change from liquid phase to gas phase.

[0030] Therefore, the carbon dioxide phase change energy storage system provided in the present application cleverly applies the heat exchange medium that participates in the first phase change of carbon dioxide to the second phase change of carbon dioxide, and applies the heat exchange medium that participates in the second phase change of carbon dioxide to the first phase change of carbon dioxide. The heat exchange media required for the energy storage step and the energy release step of carbon dioxide are converted into each other, without the need to set up a hot water station that supplies hot water separately and a cold water station that supplies cold water separately, thereby simplifying the configuration complexity of the system and reducing the hardware investment cost of the system.

[0031] In addition, since the liquid storage component stores gaseous carbon dioxide for maintaining pressure in the energy storage step, ensuring that the pressure inside the liquid storage component is higher than the pressure of the first phase change conversion component, the liquid carbon dioxide enters the second phase change conversion component directly or indirectly driven by the pressure difference between the liquid storage component and the second phase change conversion component, without the need to set a pump structure on the supply path of the liquid carbon dioxide, further simplifying the configuration complexity of the system.

[0032] Another object of the present application is to provide a carbon dioxide phase change energy storage method, which is based on the carbon dioxide phase change energy storage system as described above; the carbon dioxide phase change energy storage method includes an energy storage step and an energy release step, and the energy storage step includes a pressure increase stage and a condensation stage;

[0033] In the pressure-increasing stage, the gaseous carbon dioxide enters the liquid storage component through the first phase-change conversion component, and the pressure inside the liquid storage component is increased to the set pressure;

[0034] In the condensation stage, the gaseous carbon dioxide passes through the first phase change conversion element and exchanges heat with the heat exchange medium provided by the cold component for the first phase change to undergo a first phase change, thereby undergoing a first phase change from gas phase to liquid phase. The generated liquid carbon dioxide enters the liquid storage element, and the liquid storage element stores the liquid carbon dioxide at a set liquid level and the gaseous carbon dioxide at a set pressure.

[0035] In the energy release step, liquid carbon dioxide is driven directly or indirectly into the second phase change conversion element by the pressure difference between the liquid storage element and the second phase change conversion element, and exchanges heat with the heat exchange medium provided by the thermal component for the second phase change to cause a second phase change from liquid phase to gas phase.

[0036] In some embodiments, in the pressurization stage, high-pressure gaseous carbon dioxide passes through the first phase change conversion element and exchanges heat with the heat exchange medium provided by the cold component for the first phase change to reduce the temperature of the high-pressure gaseous carbon dioxide. The cooled high-pressure gaseous carbon dioxide enters the liquid storage element and the pressure inside the liquid storage element is increased to the set pressure.

[0037] In some embodiments, during the condensation stage, the liquid storage element delivers gaseous carbon dioxide to the first phase change converter through a gas phase balance pipe, so that the set pressure in the liquid storage element remains constant.

[0038] In some embodiments, the phase change energy storage system includes a plurality of the liquid storage components, namely the first, second, ...nth;

[0039] In the energy release step, the path between the first liquid storage element and the second phase change conversion element is first opened, and the liquid carbon dioxide in the first liquid storage element enters the second phase change conversion element under the driving force of the pressure difference;

[0040] When the pressure inside the first liquid storage element drops to a set value, the gas phase main pipe between the second liquid storage element and the first liquid storage element is connected, so that the gas phase carbon dioxide in the second liquid storage element enters the first liquid storage element, and the pressure inside the first liquid storage element is maintained at not less than the set value until the liquid phase carbon dioxide in the first liquid storage element is exhausted;

[0041] And so on, until the liquid carbon dioxide in the n-1th liquid storage element is emptied, and then the path between the nth liquid storage element and the second phase change conversion element is opened.

[0042] In some embodiments, a liquid shut-off valve is provided on the path where the liquid phase port of each liquid storage element is connected to the liquid phase main pipe; the phase change energy storage system further includes a pressure reducing valve, which is provided on the liquid phase main pipe between the second phase change conversion element and the liquid storage element closest thereto;

[0043] In the energy release step, when the path between the first liquid storage element and the second phase change conversion element is opened, the liquid cut-off valve on the path connecting the liquid phase port of the first liquid storage element and the liquid phase main pipe is first opened, and then the pressure reducing valve is opened;

[0044] When the paths between the second to nth liquid storage elements and the second phase-change converter are sequentially opened, the liquid shut-off valves respectively corresponding to the second to nth liquid storage elements are sequentially opened.

[0045] The beneficial effects of the carbon dioxide phase change energy storage method provided in this application are:

[0046] Compared with the prior art, the carbon dioxide phase change energy storage method provided by the present application, in which during the pressure-increasing stage, the gaseous carbon dioxide enters the liquid storage part through the first phase change conversion part, and the pressure inside the liquid storage part is raised to the set pressure. In this way, the liquid storage part can store gaseous carbon dioxide for pressure maintenance. In the process of the liquid storage part providing liquid carbon dioxide to the second phase change conversion part, the internal pressure of the liquid storage part decreases. According to the physical properties of liquid carbon dioxide, the saturation temperature of the liquid carbon dioxide after decompression decreases, so that the evaporation temperature of the liquid carbon dioxide is lower than the condensation temperature of the liquid carbon dioxide. Since the evaporation temperature and the condensation temperature have a certain temperature difference, the evaporation process can use the heat exchange medium generated by the condensation process for evaporation, and the heat exchange medium can be used in the condensation process after the evaporation process, thereby achieving the recycling of heat exchange media with different cold and hot temperatures.

[0047] Furthermore, in the condensation stage, the gaseous carbon dioxide passes through the first phase change conversion element and exchanges heat with the heat exchange medium provided by the cold component for the first phase change to undergo a first phase change, thereby undergoing a first phase change from the gas phase to the liquid phase, and the generated liquid carbon dioxide enters the liquid storage element. Furthermore, in the energy release step, the liquid carbon dioxide enters the second phase change conversion element directly or indirectly under the drive of the pressure difference between the liquid storage element and the second phase change conversion element, and exchanges heat with the heat exchange medium provided by the hot component for the second phase change to undergo a second phase change from the liquid phase to the gas phase.

[0048] Therefore, the carbon dioxide phase change energy storage method provided in the present application cleverly applies the heat exchange medium that participates in the first phase change of carbon dioxide to the second phase change of carbon dioxide, and applies the heat exchange medium that participates in the second phase change of carbon dioxide to the first phase change of carbon dioxide. The heat exchange media required for the carbon dioxide energy storage step and the energy release step are converted into each other, without the need to set up a hot water station that supplies hot water separately and a cold water station that supplies cold water separately, thereby reducing the control objects and control difficulty, and reducing the control cost.

[0049] In addition, since the liquid storage component stores gaseous carbon dioxide for maintaining pressure in the energy storage step, the pressure inside the liquid storage component is ensured to be higher than the pressure of the first phase change conversion component. The liquid carbon dioxide enters the second phase change conversion component directly or indirectly under the drive of the pressure difference between the liquid storage component and the second phase change conversion component, without the need to set a pump structure on the supply path of the liquid carbon dioxide, further reducing the control objects and control difficulty. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0051] Figure 1 A schematic diagram of a carbon dioxide phase change energy storage system provided in an embodiment of the present application;

[0052] Figure 2 This is a heat map of the carbon dioxide phase change energy storage system provided in an embodiment of the present application.

[0053] Among them, the reference numerals in the figure are:

[0054] 100, first phase change conversion element; 200, liquid storage element; 300, gas-liquid two-phase separation element; 400, second phase change conversion element; 500, hot component; 600, cold component; 700, gas phase balance pipe; 800, liquid phase main pipe; 900, gas phase main pipe; 1000, gas pressure regulating valve; 1100, liquid shut-off valve; 1200, flow regulating valve; 1300, pressure reducing valve; 1400, pressure control valve; 1500, liquid level control valve;

[0055] 101, gas phase inlet; 102, liquid phase outlet; 103, hot medium outlet; 104, cold medium inlet;

[0056] 201, liquid phase port; 202, gas phase port;

[0057] 301, gas-liquid inlet; 302, liquid phase separation port; 303, gas phase separation port;

[0058] 401, liquid phase inlet; 402, gas phase outlet; 403, hot medium inlet; 404, cold medium outlet;

[0059] 501, heat pipe; 502, hot water tank; 503, hot water pump;

[0060] 601, cold pipe; 602, cold water tank; 603, cold water pump. DETAILED DESCRIPTION

[0061] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present application more clearly understood, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0062] It should be noted that when an element is referred to as being "fixed to" or "disposed on" another element, it can be directly on the other element or indirectly on the other element. When an element is referred to as being "connected to" another element, it can be directly connected to the other element or indirectly connected to the other element.

[0063] It should be understood that the terms "length", "width", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0064] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of this application, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0065] The carbon dioxide phase change energy storage system and method provided in the embodiments of the present application are now described.

[0066] See also Figure 1 The carbon dioxide phase change energy storage system provided in the embodiment of the present application includes a first phase change converter 100, a liquid storage component 200, a second phase change converter 400, and a hot component 500 and a cold component 600 connected in sequence; the hot component 500 and the cold component 600 are respectively connected between the first phase change converter 100 and the second phase change converter 400.

[0067] The first phase change conversion element 100 is used for the first phase change of carbon dioxide from gas phase to liquid phase, and the second phase change conversion element 400 is used for the second phase change of carbon dioxide from liquid phase to gas phase; the liquid storage element 200 is used to store the liquid phase carbon dioxide generated by the first phase change and the gas phase carbon dioxide for pressure maintenance, and the liquid phase carbon dioxide is used to supply the second phase change conversion element 400 to undergo the second phase change;

[0068] The hot component 500 is used to supply the heat exchange medium after the first phase change to the second phase change converter 400 for the second phase change, and the cold component 600 is used to supply the heat exchange medium after the second phase change to the first phase change converter 100 for the first phase change.

[0069] Among them, the first phase change conversion component 100 includes but is not limited to a condenser, the second phase change conversion component 400 includes but is not limited to an evaporator, and the liquid storage component 200 includes but is not limited to a liquid storage tank. Each component can realize the functions required by the embodiment of the present application, and the embodiment of the present application does not make specific limitations on this.

[0070] The carbon dioxide phase change energy storage system provided in the embodiment of the present application, during the process of the system performing the energy storage step, the gaseous carbon dioxide passes through the first phase change conversion element 100 and exchanges heat with the heat exchange medium provided by the cold component 600 for the first phase change to undergo a first phase change, thereby undergoing a first phase change from gas phase to liquid phase, and the generated liquid carbon dioxide enters the liquid storage element 200, and the liquid storage element 200 stores liquid carbon dioxide of a set liquid level and gaseous carbon dioxide of a set pressure.

[0071] In this way, the liquid storage part 200 can store gaseous carbon dioxide for pressure maintenance. In the process of the liquid storage part 200 providing liquid carbon dioxide to the second phase change conversion part 400, the internal pressure of the liquid storage part 200 decreases. According to the physical properties of the liquid carbon dioxide, the saturation temperature of the liquid carbon dioxide after decompression decreases, so that the evaporation temperature of the liquid carbon dioxide is lower than the condensation temperature of the liquid carbon dioxide. Since there is a certain temperature difference between the evaporation temperature and the condensation temperature, the evaporation process can use the heat exchange medium generated by the condensation process for evaporation, and the heat exchange medium can be used in the condensation process after the evaporation process, thereby achieving the recycling of heat exchange media with different cold and hot temperatures.

[0072] Furthermore, in the energy release step, since the liquid storage component 200 stores gaseous carbon dioxide for pressure maintenance in the energy storage step, ensuring that the pressure inside the liquid storage component 200 is higher than the pressure of the first phase change conversion component 100, the liquid carbon dioxide directly or indirectly enters the second phase change conversion component 400 driven by the pressure difference between the liquid storage component 200 and the second phase change conversion component 400, and exchanges heat with the heat exchange medium provided by the thermal component 500 for the second phase change, thereby causing a second phase change from liquid phase to gas phase.

[0073] Therefore, the carbon dioxide phase change energy storage system provided in the embodiment of the present application cleverly applies the heat exchange medium after participating in the first phase change of carbon dioxide to the second phase change of carbon dioxide, and applies the heat exchange medium after participating in the second phase change of carbon dioxide to the first phase change of carbon dioxide. The heat exchange media required for the energy storage step and the energy release step of carbon dioxide are converted into each other, without the need to set up a hot water station for supplying hot water separately and a cold water station for supplying cold water separately, thereby simplifying the configuration complexity of the system and reducing the hardware investment cost of the system.

[0074] In addition, since the liquid storage component 200 stores gaseous carbon dioxide for maintaining pressure in the energy storage step, the pressure inside the liquid storage component 200 is ensured to be higher than the pressure of the first phase change conversion component 100. The liquid carbon dioxide enters the second phase change conversion component 400 directly or indirectly driven by the pressure difference between the liquid storage component 200 and the second phase change conversion component 400, without the need to set a pump structure on the supply path of the liquid carbon dioxide, further simplifying the configuration complexity of the system.

[0075] In some embodiments, the liquid storage element 200 has a liquid phase port 201 and a gas phase port 202, and the liquid phase port 201 is connected to the liquid phase outlet 102 of the first phase change converter 100 and the liquid phase inlet 401 of the second phase change converter 400. The phase change energy storage system further includes a gas phase balance tube 700, one port of which is connected to the gas phase inlet 101 of the first phase change converter 100, and the other port of the gas phase balance tube 700 is directly or indirectly connected to the gas phase port 202.

[0076] By configuring the gas phase balance pipe 700, in the condensation stage, the gas phase carbon dioxide is completely liquefied in the first phase change converter 100 and then flows into the liquid storage part 200. At the same time, the liquid storage part 200 can discharge the gas phase carbon dioxide through the gas phase balance pipe 700 to maintain a constant pressure inside the liquid storage part 200. In some embodiments, the gas phase carbon dioxide discharged from the liquid storage part 200 through the gas phase port 202 enters the gas phase inlet 101 on the carbon dioxide side of the first phase change converter 100 from the gas phase balance pipe 700, and the gas phase inlet 101 supplies the gas phase carbon dioxide in the gas storage reservoir to enter the first phase change converter 100.

[0077] In some embodiments, the phase change energy storage system includes a plurality of liquid storage elements 200 and a liquid phase main pipe 800. The liquid inlet of the liquid phase main pipe 800 is connected to the liquid phase outlet 102 of the first phase change converter 100, the liquid outlet of the liquid phase main pipe 800 is connected to the liquid phase inlet 401 of the second phase change converter 400, and the plurality of liquid phase ports 201 of the plurality of liquid storage elements 200 are respectively connected to the liquid phase main pipe 800.

[0078] For example, the plurality of liquid storage elements 200 are respectively the first, second, ... nth. In the energy release step, the path between the first liquid storage element 200 and the second phase change conversion element 400 is first opened, and the liquid carbon dioxide in the first liquid storage element 200 enters the second phase change conversion element 400 driven by the pressure difference. When the pressure inside the first liquid storage element 200 is reduced to a set value, the gas phase main pipe 900 between the second liquid storage element 200 and the first liquid storage element 200 is opened, so that the gas phase carbon dioxide in the second liquid storage element 200 enters the first liquid storage element 200, and the pressure inside the first liquid storage element 200 is maintained not lower than the set value until the liquid phase carbon dioxide in the first liquid storage element 200 is emptied. And so on, until the liquid phase carbon dioxide in the n-1th liquid storage element 200 is emptied, then the path between the nth liquid storage element 200 and the second phase change conversion element 400 is opened.

[0079] By setting up multiple liquid storage components 200 and liquid phase main pipes 800, the liquid can be discharged from each liquid storage component 200 one by one, maximizing the use of the pressure difference between each liquid storage component 200 and the second phase change conversion component 400 for liquid transportation, and ensuring that the liquid carbon dioxide in each liquid storage component 200 is emptied, thereby improving the energy release efficiency and thoroughness.

[0080] In addition, the storage pressure inside each liquid storage component 200 is high, while the liquid release pressure required for each liquid storage component 200 is low, that is, the actual work pressure is low, that is, the material density inside the liquid storage component 200 can be higher, while the material density in the liquid phase main pipe 800 can be lower, which reduces the volume of the liquid storage component 200 to a certain extent and reduces the hardware investment of the system.

[0081] In some embodiments, the phase change energy storage system further includes a pressure reducing valve 1300, which is disposed on the liquid phase main pipe 800 between the second phase change converter 400 and the liquid storage element 200 closest thereto. A liquid shut-off valve 1100 is disposed on the path where the liquid phase port 201 of each liquid storage element 200 is connected to the liquid phase main pipe 800.

[0082] Based on the method of discharging liquid from the liquid storage parts 200 one by one, the pressure inside the liquid storage part 200 is first reduced through the liquid cut-off valve 1100, and then reduced through the pressure reducing valve 1300, thereby avoiding the direct reduction of high pressure to low pressure and achieving step-by-step pressure reduction. The number of pressure reducing valves 1300 can be set according to demand to maximize the use of pressure difference for liquid transportation.

[0083] In some embodiments, a flow regulating valve 1200 can also be set on the liquid phase main pipe 800 between the second phase change conversion element 400 and the liquid storage element 200 closest thereto. The flow regulating valve 1200 is closer to the side where the liquid storage element 200 is located, and can adjust the liquid phase flow in the liquid phase main pipe 800 according to real-time conditions.

[0084] In some embodiments, the phase change energy storage system further includes a gas phase main pipe 900 , and multiple gas phase ports 202 of multiple liquid storage components 200 are respectively connected to the gas phase main pipe 900 ; wherein the gas phase port 202 is arranged at the top of the liquid storage component 200 , and the liquid phase port 201 is arranged at the bottom of the liquid storage component 200 .

[0085] For example, in the energy release step, the path between the first liquid storage element 200 and the second phase change conversion element 400 is first opened, and the liquid carbon dioxide in the first liquid storage element 200 enters the second phase change conversion element 400 driven by the pressure difference. When the pressure inside the first liquid storage element 200 is reduced to the set value, the gas phase main pipe 900 between the second liquid storage element 200 and the first liquid storage element 200 is opened, so that the gas phase carbon dioxide in the second liquid storage element 200 enters the first liquid storage element 200, and the pressure inside the first liquid storage element 200 is maintained not less than the set value until the liquid phase carbon dioxide in the first liquid storage element 200 is exhausted. And so on, until the liquid phase carbon dioxide in the n-1th liquid storage element 200 is exhausted, and then the path between the nth liquid storage element 200 and the second phase change conversion element 400 is opened.

[0086] By setting up the gas phase main pipe 900 and adopting the method of replenishing the pressure of the rear liquid storage component 200 to the front liquid storage component 200, the pressure difference is maximized for liquid transportation, and it is ensured that the liquid carbon dioxide in each liquid storage component 200 is emptied, thereby improving the energy release efficiency and thoroughness.

[0087] Based on the above-mentioned gas phase main pipe 900, in some embodiments, the above-mentioned gas phase balance pipe 700 can be indirectly connected to the gas phase port 202 of the liquid storage member 200 by connecting to the gas phase main pipe 900. Of course, in other embodiments, the gas phase balance pipe 700 can also be directly connected to the gas phase port 202 of each liquid storage member 200.

[0088] In some embodiments, a gas pressure regulating valve 1000 is provided in the path connecting each gas phase port 202 of each liquid storage member 200 and the gas phase main pipe 900, so as to adjust the flow of gas phase carbon dioxide through each gas phase port 202 according to real-time conditions.

[0089] In some embodiments, multiple liquid storage components 200 are arranged at the same height, and the height of the first phase change conversion component 100 is higher than the height of the liquid storage component 200, so that the first phase change conversion component 100 uses the potential energy generated by the height difference to transport liquid carbon dioxide to each liquid storage component 200, thereby simplifying the configuration complexity of the system.

[0090] In some embodiments, the phase change energy storage system further includes a gas-liquid two-phase separator 300. The gas-liquid two-phase separator 300 is connected between the liquid storage element 200 and the second phase change converter 400, and the gas-liquid two-phase separator 300 is used to separate gas phase carbon dioxide and liquid phase carbon dioxide to supply liquid phase carbon dioxide to the second phase change converter 400 alone.

[0091] Among them, the gas-liquid two-phase separator 300 includes but is not limited to a flash tank. The gas-liquid two-phase separator 300 can achieve the functions required by the embodiment of the present application, and the embodiment of the present application does not make specific limitations on this.

[0092] By setting up the gas-liquid two-phase separation element 300, the gas-liquid two-phase mixture from the liquid storage element 200 and after decompression is separated into gas phase and liquid phase in the gas-liquid two-phase separation element 300, thereby preventing the gas phase from being entrained by the liquid phase and entering the second phase change conversion element 400, which is beneficial to improving the heat exchange efficiency of the second phase change conversion element 400.

[0093] In addition, a liquid level control valve 1500 may be provided on the path between the gas-liquid two-phase separator 300 and the second phase change converter 400, and a pressure control valve 1400 may be provided outside the gas phase separation port 303 of the gas-liquid two-phase separator 300. The liquid level of the liquid phase and the pressure of the gas phase in the gas-liquid two-phase separator 300 may be controlled by the liquid level control valve 1500 and the pressure control valve 1400, and the stability of the system operation may be ensured by adjusting the carbon oxide flow in the liquid phase main pipe 800.

[0094] In some embodiments, the height of the gas-liquid two-phase separator 300 is higher than the height of the second phase change converter 400, so that the gas-liquid two-phase separator 300 uses the potential energy generated by the height difference to transport liquid carbon dioxide to the second phase change converter 400, simplifying the configuration complexity of the system.

[0095] In some embodiments, the gas-liquid two-phase separator 300 has a gas-liquid inlet 301, a liquid phase separation port 302 and a gas phase separation port 303, the liquid phase separation port 302 is arranged at the bottom of the gas-liquid two-phase separator 300, the gas phase separation port 303 is arranged at the top of the gas-liquid two-phase separator 300, and the gas-liquid inlet 301 is arranged in the middle of the gas-liquid two-phase separator 300. The liquid phase inlet 401 of the second phase change converter 400 is arranged at the bottom of the second phase change converter 400, and the gas phase outlet 402 of the second phase change converter 400 is arranged at the top of the second phase change converter 400. Among them, the liquid phase port 201 of the liquid storage member 200 is connected to the gas-liquid inlet 301, and the liquid phase separation port 302 is connected to the liquid phase inlet 401; the phase change energy storage system also includes a gas phase discharge pipe, and the gas phase separation port 303 and the gas phase outlet 402 are both connected to the gas phase discharge pipe.

[0096] In some embodiments, the heat assembly 500 includes a heat pipe 501, and a hot water tank 502 and a hot water pump 503 sequentially arranged on the heat pipe 501, and the heat pipe 501 connects the hot medium outlet 103 of the first phase change converter 100 and the hot medium inlet 403 of the second phase change converter 400. The cold assembly 600 includes a cold pipe 601, and a cold water tank 602 and a cold water pump 603 sequentially arranged on the cold pipe 601, and the cold pipe 601 connects the cold medium inlet 104 of the first phase change converter 100 and the cold medium outlet 404 of the second phase change converter 400.

[0097] Another purpose of the embodiments of the present application is to provide a carbon dioxide phase change energy storage method, which is based on the above carbon dioxide phase change energy storage system; the carbon dioxide phase change energy storage method includes an energy storage step and an energy release step, and the energy storage step includes a pressure boosting stage and a condensation stage.

[0098] In the pressure increasing stage, the gaseous carbon dioxide enters the liquid storage element 200 through the first phase change converter 100, and the pressure inside the liquid storage element 200 increases to the set pressure.

[0099] During the condensation stage, the gaseous carbon dioxide passes through the first phase change conversion element 100 and exchanges heat with the heat exchange medium provided by the cold component 600 for the first phase change, thereby undergoing a first phase change from gas phase to liquid phase. The generated liquid carbon dioxide enters the liquid storage element 200, and the liquid storage element 200 stores liquid carbon dioxide at a set liquid level and gaseous carbon dioxide at a set pressure.

[0100] In the energy release step, liquid carbon dioxide is driven directly or indirectly into the second phase change conversion element 400 by the pressure difference between the liquid storage element 200 and the second phase change conversion element 400, and exchanges heat with the heat exchange medium provided by the thermal component 500 for the second phase change to cause a second phase change from liquid phase to gas phase.

[0101] In the carbon dioxide phase change energy storage method provided by the embodiment of the present application, in the boosting stage, the gaseous carbon dioxide enters the liquid storage part 200 through the first phase change conversion part 100, and the pressure inside the liquid storage part 200 is raised to the set pressure. In this way, the liquid storage part 200 can store gaseous carbon dioxide for pressure maintenance. In the process of the liquid storage part 200 providing liquid carbon dioxide to the second phase change conversion part 400, the internal pressure of the liquid storage part 200 decreases. According to the physical properties of liquid carbon dioxide, the saturation temperature of the liquid carbon dioxide after decompression decreases, so that the evaporation temperature of the liquid carbon dioxide is lower than the condensation temperature of the liquid carbon dioxide. Since the evaporation temperature and the condensation temperature have a certain temperature difference, the evaporation process can use the heat exchange medium generated by the condensation process for evaporation, and the heat exchange medium can be used in the condensation process after the evaporation process, thereby achieving the recycling of heat exchange media with different cold and hot temperatures.

[0102] Furthermore, in the condensation stage, the gaseous carbon dioxide passes through the first phase change conversion element 100 and exchanges heat with the heat exchange medium provided by the cold component 600 for the first phase change to undergo a first phase change, thereby undergoing a first phase change from the gas phase to the liquid phase, and the generated liquid carbon dioxide enters the liquid storage element 200. Furthermore, in the energy release step, the liquid carbon dioxide enters the second phase change conversion element 400 directly or indirectly under the drive of the pressure difference between the liquid storage element 200 and the second phase change conversion element 400, and exchanges heat with the heat exchange medium provided by the hot component 500 for the second phase change to undergo a second phase change, thereby undergoing a second phase change from the liquid phase to the gas phase.

[0103] Therefore, the carbon dioxide phase change energy storage method provided in the present application cleverly applies the heat exchange medium that participates in the first phase change of carbon dioxide to the second phase change of carbon dioxide, and applies the heat exchange medium that participates in the second phase change of carbon dioxide to the first phase change of carbon dioxide. The heat exchange media required for the carbon dioxide energy storage step and the energy release step are converted into each other, without the need to set up a hot water station that supplies hot water separately and a cold water station that supplies cold water separately, thereby reducing the control objects and control difficulty, and reducing the control cost.

[0104] In addition, since the liquid storage component 200 stores gaseous carbon dioxide for maintaining pressure in the energy storage step, the pressure inside the liquid storage component 200 is ensured to be higher than the pressure of the first phase change conversion component 100. The liquid carbon dioxide enters the second phase change conversion component 400 directly or indirectly driven by the pressure difference between the liquid storage component 200 and the second phase change conversion component 400, without the need to set a pump structure on the supply path of the liquid carbon dioxide, further reducing the control objects and control difficulty.

[0105] In some embodiments, during the pressure increase stage, the high-pressure gas phase carbon dioxide passes through the first phase change conversion element 100 and exchanges heat with the heat exchange medium provided by the cold assembly 600 for the first phase change to reduce the temperature of the high-pressure gas phase carbon dioxide, and the cooled high-pressure gas phase carbon dioxide enters the liquid storage element 200, and the pressure inside the liquid storage element 200 is increased to the set pressure. The cooled high-pressure gas phase carbon dioxide enters the liquid storage element 200, so that the liquid storage element 200 can maintain the set pressure and the saturation temperature of the liquid phase carbon dioxide can be reduced after the pressure is reduced.

[0106] In some embodiments, during the condensation stage, the liquid storage element 200 delivers gaseous carbon dioxide to the first phase change converter 100 through the gas phase balance pipe 700 to keep the set pressure in the liquid storage element 200 constant.

[0107] In the condensation stage, the gaseous carbon dioxide is completely liquefied in the first phase change converter 100 and then flows into the liquid storage component 200. At the same time, the liquid storage component 200 can discharge the gaseous carbon dioxide through the gas phase balance pipe 700 to maintain a constant pressure inside the liquid storage component 200.

[0108] In some embodiments, the phase change energy storage system includes multiple liquid storage components 200, namely the first, second...nth; in the energy release step, the path between the first liquid storage component 200 and the second phase change conversion component 400 is first opened, and the liquid carbon dioxide in the first liquid storage component 200 enters the second phase change conversion component 400 driven by the pressure difference.

[0109] When the pressure inside the first liquid storage component 200 drops to a set value, the gas phase main pipe 900 between the second liquid storage component 200 and the first liquid storage component 200 is connected to allow the gaseous carbon dioxide in the second liquid storage component 200 to enter the first liquid storage component 200, and maintain the pressure inside the first liquid storage component 200 not lower than the set value until the liquid carbon dioxide in the first liquid storage component 200 is emptied.

[0110] This process is repeated in this way until the liquid carbon dioxide in the n-1th liquid storage element 200 is exhausted, and then the path between the nth liquid storage element 200 and the second phase change converter 400 is opened.

[0111] By using the rear liquid storage component 200 to supplement the pressure of the front liquid storage component 200, the pressure difference is maximized for liquid transportation, and it is ensured that the liquid carbon dioxide in each liquid storage component 200 is emptied, thereby improving the energy release efficiency and thoroughness.

[0112] In some embodiments, a liquid shut-off valve 1100 is provided on the path connecting the liquid phase port 201 of each liquid storage component 200 and the liquid phase main pipe 800 respectively; the phase change energy storage system also includes a pressure reducing valve 1300, which is arranged on the liquid phase main pipe 800 between the second phase change conversion component 400 and the liquid storage component 200 closest thereto.

[0113] In the energy release step, when the path between the first liquid storage element 200 and the second phase change conversion element 400 is opened, the liquid shut-off valve 1100 on the connection path between the liquid phase port 201 of the first liquid storage element 200 and the liquid phase main pipe 800 is first opened, and then the pressure reducing valve 1300 is opened. When the paths between the second to nth liquid storage elements 200 and the second phase change conversion element 400 are sequentially opened, the liquid shut-off valves 1100 corresponding to the second to nth liquid storage elements 200 are sequentially opened.

[0114] Based on the method of discharging liquid from the liquid storage parts 200 one by one, the pressure inside the liquid storage part 200 is first reduced through the liquid cut-off valve 1100, and then reduced through the pressure reducing valve 1300, thereby avoiding the direct reduction of high pressure to low pressure and achieving step-by-step pressure reduction. The number of pressure reducing valves 1300 can be set according to demand to maximize the use of pressure difference for liquid transportation.

[0115] As an example, this embodiment provides a relatively detailed carbon dioxide phase change energy storage method, wherein the heat exchange medium is water, and the number of liquid storage components 200 is three.

[0116] In the pressurization stage, low-pressure gaseous carbon dioxide is pre-stored in the liquid storage component 200. The high-pressure gaseous carbon dioxide passes through the first phase change conversion component 100, exchanges heat with the cold water from the cold component 600 and is cooled. The cooled high-pressure gaseous carbon dioxide flows into each liquid storage component 200 at the same time through the liquid phase main pipe 800. With the entry of high-pressure gaseous carbon dioxide, the pressure in the first phase change conversion component 100 and each liquid storage component 200 gradually increases until it reaches the set pressure, which is a high pressure value.

[0117] In the condensation stage, the high-pressure gas phase carbon dioxide is completely liquefied in the first phase change conversion element 100 and then flows into each liquid storage element 200. At the same time, the liquid storage element 200 discharges the gas phase carbon dioxide through the gas phase main pipe 900 and the gas phase balance pipe 700 to maintain the pressure in the liquid storage element 200 constant. The discharged gas phase carbon dioxide enters the gas phase inlet 101 of the first phase change conversion element 100 from the gas phase main pipe 900 through the gas phase balance pipe 700. When the liquid level in the liquid storage element 200 reaches the set value, the liquid shut-off valve 1100 corresponding to each liquid storage element 200 is closed, and finally each liquid storage element 200 stores the liquid phase carbon dioxide of the set liquid level and the gas phase carbon dioxide of the set pressure. Among them, the cold water exchanges heat with the high-pressure gas phase carbon dioxide in the first phase change conversion element 100 and is heated to become hot water and stored in the hot water tank 502.

[0118] In the energy release step, the liquid carbon dioxide in the first liquid storage component 200 is regulated by the flow regulating valve 1200 and decompressed by the pressure reducing valve 1300, and then flows into the gas-liquid two-phase inlet for flash separation under the action of the pressure difference. The separated liquid carbon dioxide flows into the second phase change conversion component 400 from the liquid phase separation port 302 under the action of gravity, and is heat-exchanged with the hot water from the thermal component 500 to complete evaporation. The gaseous carbon dioxide generated by evaporation is mixed with the gaseous carbon dioxide separated by the gas-liquid two-phase separation component 300 and flows to the subsequent process. In this process, the liquid level in the gas-liquid two-phase separation component 300 can be adjusted by the liquid level control valve 1500, and the pressure in the gas-liquid two-phase separation component 300 can be adjusted by the pressure control valve 1400, so as to ensure the stability of the pressure and liquid level inside the gas-liquid two-phase separation component 300, and then ensure the stability of the vaporization amount.

[0119] As the liquid carbon dioxide in the first liquid storage part 200 flows out, the pressure inside the first liquid storage part 200 decreases. When the pressure drops to the set value, the gaseous carbon dioxide in the second liquid storage part 200 is introduced into the first liquid storage part 200 through the gas pressure regulating valve 1000 to maintain the pressure inside the first liquid storage part 200 not lower than the set value until the liquid carbon dioxide inside the first liquid storage part 200 is emptied. By switching the liquid shut-off valve 1100, the liquid continues to flow out from the second liquid storage part 200. Similarly, when the internal pressure of the second liquid storage part 200 drops to the set value, the gaseous carbon dioxide in the third liquid storage part 200 is used to maintain the pressure of the second liquid storage part 200 until the liquid in the second liquid storage part 200 is emptied. This is carried out in sequence until the liquid in each liquid storage part 200 is completely emptied. The liquid level in the last liquid storage element 200 is set lower than the liquid levels in other liquid storage elements 200, so that the last liquid storage element 200 has a larger gas space inside, ensuring that the liquid inside the last liquid storage element 200 can be emptied. In this process, hot water exchanges heat with liquid carbon dioxide in the second phase change converter 400 and is cooled to become cold water and stored in the cold water tank 602.

[0120] like Figure 2 As shown, in the above energy storage and release process, after the liquid phase carbon dioxide in the liquid storage element 200 is depressurized, the pressure in the second phase change conversion element 400 depends on the heat exchange end difference and the temperature rise of water, that is, the temperature difference (10°C) between the saturation temperature (28.7°C) corresponding to the high-pressure carbon dioxide and the saturation temperature (18.7°C) corresponding to the low-pressure carbon dioxide is equal to the sum of the heat exchange end difference (25.7°C-21.7°C=4°C) of the first phase change conversion element 100, the hot end difference (21.7°C-18.7°C=3°C) of the second phase change conversion element 400, and the temperature rise of water (28.7°C-25.7°C=3°C). In addition, by adjusting the intake temperature of the high-pressure carbon dioxide, the temperature of the first phase change conversion element can be adjusted, thereby ensuring that the temperature difference between the first phase change conversion element 100 and the second phase change conversion element 400 is always consistent, so as to achieve the purpose of cold and hot water balance and realize the use of cold and hot water circulation.

[0121] As an example, this embodiment provides a more detailed carbon dioxide phase change energy storage method, wherein the heat exchange medium is water, and the number of liquid storage components 200 is three.

[0122] In the energy storage step, the local system composed of the first phase change conversion element 100, the first liquid storage element 200, the second liquid storage element 200, and the third liquid storage element 200 is filled with 5.9MPa of saturated gas phase carbon dioxide. The liquid shut-off valves 1100 corresponding to the three liquid storage elements 200 are opened at the same time, and the high-pressure gas phase carbon dioxide enters the first phase change conversion element 100 to cool down, and then enters all liquid storage elements 200 from the liquid phase main pipe 800 at the same time. With the entry of the gas phase, the pressure of the local system gradually increases. When the pressure of the local system rises to 7MPa, the air pressure regulating valves 1000 corresponding to each liquid storage element 200 are fully opened. At this time, the high-pressure gas phase carbon dioxide condenses into liquid after heat exchange in the first phase change converter 100 and flows into all liquid storage components 200. At the same time, part of the gas phase carbon dioxide in all liquid storage components 200 is squeezed out, enters the first phase change converter through the gas phase main pipe 900 and the gas phase balance pipe 700, condenses into liquid and returns to all liquid storage components 200, thereby maintaining the stability of the local system pressure. When the liquid level in the liquid storage component 200 reaches the set value, the corresponding liquid shut-off valve 1100 is closed until the energy storage step is completed, and all liquid shut-off valves 1100 and air pressure regulating valves 1000 are closed. In this stage, the cold water in the cold water tank 602 is transported to the water side of the first phase change converter 100 through the cold water pump 603, and returns to the hot water tank 502 for storage after heat exchange with the gas phase carbon dioxide and temperature rises.

[0123] In the energy release step, the vaporization system composed of the gas-liquid two-phase separator 300 and the second phase change converter 400 is filled with 5.6MPa of saturated gas phase carbon dioxide. The liquid shut-off valve 1100 at the bottom of the first liquid storage member 200 is opened, the opening of the flow control valve 1200 is adjusted to meet the carbon dioxide vaporization amount, and the outlet pressure of the pressure reducing valve 1300 is adjusted so that the high-pressure liquid phase carbon dioxide that can flow into the gas-liquid two-phase separator 300 is reduced in temperature after decompression, and becomes a gas-liquid mixture and enters the gas-liquid two-phase separator 300 for further flash evaporation and cooling. The liquid phase enters the second phase change converter 400 from the bottom of the gas-liquid two-phase separator 300 through the liquid level control valve 1500 to exchange heat with hot water for vaporization, and the separated and vaporized carbon dioxide is mixed with the top and enters the subsequent process.

[0124] As the liquid carbon dioxide flows out of the first liquid storage part 200, its internal pressure decreases, and the liquid carbon dioxide flashes and cools down. When its internal pressure drops to 5.9 MPa, the first air pressure regulating valve 1000 is fully opened, and the opening of the second air pressure regulating valve 1000 is adjusted to allow the liquid carbon dioxide gas of the second liquid storage part 200 to enter the first liquid storage part 200, and the pressure of the first liquid storage part 200 is maintained at 5.9 MPa until the liquid in the first liquid storage part 200 is completely discharged. At this time, the first liquid shut-off valve 1100 and the first air pressure regulating valve 1000 are closed, and the second liquid shut-off valve 1100 is opened to switch the second liquid storage part 200 to discharge liquid.

[0125] Similarly, when the internal pressure of the second liquid storage part 200 drops to 5.9 MPa, the second air pressure regulating valve 1000 is fully opened, and the opening of the third air pressure regulating valve 1000 is adjusted to allow the carbon dioxide gas in the third liquid storage part 200 to enter the second liquid storage part 200, and the pressure of the second liquid storage part 200 is maintained at 5.9 MPa until the liquid in the second liquid storage part 200 is completely discharged. At this time, the second liquid shut-off valve 1100, the second air pressure regulating valve 1000 and the third air pressure regulating valve 1000 are closed, and the third liquid shut-off valve 1100 is opened to switch the third liquid storage part 200 to discharge liquid. When the internal pressure of the third liquid storage part 200 drops to 5.9 MPa, the third liquid shut-off valve 1100 is closed, and the energy release ends.

[0126] Generally, the third liquid storage element 200 is required to be filled with less liquid than the other liquid storage elements 200, so that its gas phase space occupies a larger proportion and the pressure changes more slowly, and all liquid carbon dioxide can be discharged when the pressure drops to 5.9 MPa. In this stage, the hot water in the hot water tank 502 is transported to the water side of the second phase change converter 400 through the hot water pump 503, and is returned to the cold water tank 602 for storage after heat exchange with carbon dioxide and cooling.

[0127] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present application should be included in the protection scope of the present application.

Claims

1. A carbon dioxide phase change energy storage method, characterized in that: The carbon dioxide phase change energy storage method is based on a carbon dioxide phase change energy storage system; The carbon dioxide phase change energy storage system comprises a first phase change conversion element (100), a liquid storage element (200), a second phase change conversion element (400), a hot component (500) and a cold component (600) which are connected in sequence; the hot component (500) and the cold component (600) are respectively connected between the first phase change conversion element (100) and the second phase change conversion element (400); The first phase change conversion element (100) is used for the carbon dioxide to undergo a first phase change from a gas phase to a liquid phase, and the second phase change conversion element (400) is used for the carbon dioxide to undergo a second phase change from a liquid phase to a gas phase; the liquid storage element (200) is used for storing liquid carbon dioxide generated by the first phase change and gaseous carbon dioxide for pressure maintenance, and the liquid carbon dioxide is used to be supplied to the second phase change conversion element (400) to undergo the second phase change; The hot component (500) is used to supply the heat exchange medium after the first phase change to the second phase change conversion element (400) for use in the second phase change, and the cold component (600) is used to supply the heat exchange medium after the second phase change to the first phase change conversion element (100) for use in the first phase change; Wherein, the carbon dioxide phase change energy storage method comprises an energy storage step and an energy release step, and the energy storage step comprises a pressure increase stage and a condensation stage; In the pressure-increasing stage, gaseous carbon dioxide enters the liquid storage component (200) through the first phase-change conversion component (100), and the pressure inside the liquid storage component (200) is increased to a set pressure; In the condensation stage, the gaseous carbon dioxide passes through the first phase change conversion element (100) and exchanges heat with the heat exchange medium provided by the cold component (600) for the first phase change to undergo a first phase change, thereby undergoing a first phase change from gaseous phase to liquid phase, and the generated liquid carbon dioxide enters the liquid storage element (200), and the liquid storage element (200) stores liquid carbon dioxide at a set liquid level and gaseous carbon dioxide at a set pressure; In the energy release step, the liquid carbon dioxide is driven by the pressure difference between the liquid storage element (200) and the second phase change conversion element (400) to directly or indirectly enter the second phase change conversion element (400), and exchanges heat with the heat exchange medium provided by the thermal component (500) for the second phase change to cause a second phase change from liquid phase to gas phase; The phase change energy storage system comprises a plurality of liquid storage components (200), namely, a first, a second, ... an nth; In the energy release step, the path between the first liquid storage element (200) and the second phase change conversion element (400) is first opened, and the liquid carbon dioxide in the first liquid storage element (200) enters the second phase change conversion element (400) under the driving force of the pressure difference; When the pressure inside the first liquid storage component (200) drops to a set value, the gas phase main pipe (900) between the second liquid storage component (200) and the first liquid storage component (200) is connected, so that the gas phase carbon dioxide in the second liquid storage component (200) enters the first liquid storage component (200), and the pressure inside the first liquid storage component (200) is maintained at not less than the set value until the liquid phase carbon dioxide in the first liquid storage component (200) is exhausted; This process is repeated by analogy until the liquid carbon dioxide in the n-1th liquid storage element (200) is exhausted, and then the path between the nth liquid storage element (200) and the second phase change conversion element (400) is opened.

2. The carbon dioxide phase change energy storage method according to claim 1, characterized in that: In the pressure-increasing stage, the high-pressure gaseous carbon dioxide passes through the first phase-change conversion element (100) and exchanges heat with the heat exchange medium provided by the cold component (600) for the first phase change to reduce the temperature of the high-pressure gaseous carbon dioxide. The cooled high-pressure gaseous carbon dioxide enters the liquid storage element (200) and the pressure inside the liquid storage element (200) is increased to the set pressure.

3. The carbon dioxide phase change energy storage method according to claim 1, characterized in that: In the condensation stage, the liquid storage element (200) transports gaseous carbon dioxide to the first phase change conversion element (100) through the gas phase balance pipe (700), so that the set pressure in the liquid storage element (200) remains constant.

4. The carbon dioxide phase change energy storage method according to claim 1, characterized in that: A liquid shut-off valve (1100) is provided on the path where the liquid phase port (201) of each liquid storage element (200) is connected to the liquid phase main pipe (800); the phase change energy storage system further comprises a pressure reducing valve (1300), and the pressure reducing valve (1300) is provided on the liquid phase main pipe (800) between the second phase change conversion element (400) and the liquid storage element (200) closest thereto; In the energy release step, when the path between the first liquid storage element (200) and the second phase change conversion element (400) is opened, the liquid shut-off valve (1100) on the connection path between the liquid phase port (201) of the first liquid storage element (200) and the liquid phase main pipe (800) is first opened, and then the pressure reducing valve (1300) is opened; When the paths between the second to nth liquid storage elements (200) and the second phase change conversion element (400) are sequentially conducted, the liquid shut-off valves (1100) respectively corresponding to the second to nth liquid storage elements (200) are sequentially conducted.

5. The carbon dioxide phase change energy storage method according to claim 1, characterized in that: The liquid storage element (200) has a liquid phase port (201) and a gas phase port (202), and the liquid phase port (201) is connected to the liquid phase outlet (102) of the first phase change conversion element (100) and the liquid phase inlet (401) of the second phase change conversion element (400); The phase change energy storage system further comprises a gas phase balance tube (700), one port of the gas phase balance tube (700) being connected to the gas phase inlet (101) of the first phase change converter (100), and the other port of the gas phase balance tube (700) being directly or indirectly connected to the gas phase port (202).

6. The carbon dioxide phase change energy storage method according to claim 1, characterized in that: The phase change energy storage system comprises a plurality of liquid storage components (200) and a liquid phase main pipe (800); The liquid inlet of the liquid phase main pipe (800) is connected to the liquid phase outlet (102) of the first phase change conversion element (100), the liquid outlet of the liquid phase main pipe (800) is connected to the liquid phase inlet (401) of the second phase change conversion element (400), and the multiple liquid phase ports (201) of the multiple liquid storage elements (200) are respectively connected to the liquid phase main pipe (800).

7. The carbon dioxide phase change energy storage method according to claim 6, characterized in that: The phase change energy storage system further comprises a gas phase main pipe (900), and the multiple gas phase ports (202) of the multiple liquid storage components (200) are respectively connected to the gas phase main pipe (900); wherein the gas phase port (202) is arranged at the top of the liquid storage component (200), and the liquid phase port (201) is arranged at the bottom of the liquid storage component (200).

8. The carbon dioxide phase change energy storage method according to claim 6, characterized in that: The plurality of liquid storage components (200) are arranged at the same height, and the height of the first phase change conversion component (100) is higher than the height of the liquid storage components (200).

9. The carbon dioxide phase change energy storage method according to any one of claims 1 to 8, characterized in that: The phase change energy storage system also includes a gas-liquid two-phase separation element (300); The gas-liquid two-phase separator (300) is connected between the liquid storage element (200) and the second phase change converter (400), and the gas-liquid two-phase separator (300) is used to separate gaseous carbon dioxide and liquid carbon dioxide so as to supply the liquid carbon dioxide to the second phase change converter (400) separately.

10. The carbon dioxide phase change energy storage method according to claim 9, characterized in that: The height of the gas-liquid two-phase separation element (300) is higher than the height of the second phase change conversion element (400).

11. The carbon dioxide phase change energy storage method according to claim 9, characterized in that: The gas-liquid two-phase separation element (300) comprises a gas-liquid inlet (301), a liquid phase separation port (302) and a gas phase separation port (303); the liquid phase separation port (302) is arranged at the bottom of the gas-liquid two-phase separation element (300); the gas phase separation port (303) is arranged at the top of the gas-liquid two-phase separation element (300); and the gas-liquid inlet (301) is arranged in the middle of the gas-liquid two-phase separation element (300); The liquid phase inlet (401) of the second phase change conversion element (400) is arranged at the bottom of the second phase change conversion element (400), and the gas phase outlet (402) of the second phase change conversion element (400) is arranged at the top of the second phase change conversion element (400); The liquid phase port (201) of the liquid storage element (200) is connected to the gas-liquid inlet (301), and the liquid phase separation port (302) is connected to the liquid phase inlet (401); the phase change energy storage system further comprises a gas phase exhaust pipe, and the gas phase separation port (303) and the gas phase outlet (402) are both connected to the gas phase exhaust pipe.

12. The carbon dioxide phase change energy storage method according to any one of claims 1 to 8, characterized in that: The thermal assembly (500) comprises a heat pipe (501), and a hot water tank (502) and a hot water pump (503) arranged in sequence on the heat pipe (501), wherein the heat pipe (501) connects a heat medium outlet (103) of the first phase change conversion element (100) and a heat medium inlet (403) of the second phase change conversion element (400); The cold assembly (600) comprises a cold pipe (601), and a cold water tank (602) and a cold water pump (603) arranged in sequence on the cold pipe (601), wherein the cold pipe (601) connects a cold medium inlet (104) of the first phase change conversion element (100) and a cold medium outlet (404) of the second phase change conversion element (400).

13. The carbon dioxide phase change energy storage method according to claim 6, characterized in that: The phase-change energy storage system further comprises a pressure reducing valve (1300), wherein the pressure reducing valve (1300) is arranged on the liquid phase main pipe (800) between the second phase-change conversion element (400) and the liquid storage element (200) closest thereto; A liquid shut-off valve (1100) is provided on the path where the liquid phase port (201) of each liquid storage element (200) is connected to the liquid phase main pipe (800).

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