Bilateral liquid carbon dioxide energy storage system

Abstract

The invention relates to a double-side liquid carbon dioxide energy storage system which comprises a low-pressure side liquid storage tank, a high-pressure side liquid storage tank, an energy storage mechanism, an energy release mechanism, a first low-temperature working medium storage tank, a first high-temperature working medium storage tank and a heating assembly. The energy release mechanism comprises a high-pressure side gasifier, at least one energy release assembly and a low-pressure side liquefier which are sequentially connected from the high-pressure side liquid storage tank to the low-pressure side liquid storage tank. Each energy releasing assembly comprises a heater, a heat exchanger and an expansion machine which are sequentially connected from the high-pressure side liquid storage tank to the low-pressure side liquid storage tank. According to the bilateral liquid carbon dioxide energy storage system, after high-pressure liquid carbon dioxide in the high-pressure side liquid storage tank is gasified through the high-pressure side gasifier, the high-pressure liquid carbon dioxide is heated for the first time through the heater and then heated for the second time through the heat exchanger, the grade of CO2 is improved in a gradient mode, and therefore the circulation efficiency of the bilateral liquid carbon dioxide energy storage system is improved.

Description

Technical Field

[0001] The present application relates to the technical field of carbon dioxide energy storage systems, and in particular to a double-sided liquid carbon dioxide energy storage system. Background Art

[0002] Offshore wind power is an inevitable trend in the future development of wind power. At present, China's offshore wind power has achieved large-scale development. Offshore wind power configuration energy storage is mainly used in peak load regulation services, frequency regulation services, grid stability control, clean substitution and other aspects.

[0003] Both offshore energy storage and conventional energy storage need to have the characteristics of high safety, high energy density, long cycle, low cost, maintenance-free and long working life in terms of performance, but offshore energy storage has special requirements for its devices, such as resistance to high pressure, wind and wave impact, seawater immersion, and seawater corrosion. At present, the only energy storage technologies that meet the most basic energy storage density requirements for offshore applications (energy storage density > 20kW·h / m3) are electrochemical energy storage (lithium batteries, sodium batteries, excluding flow batteries, which have low energy storage density) and liquefied gas energy storage (excluding compressed gas energy storage, which has low energy storage density). Among them, lithium batteries are only suitable for small-scale, short-term energy storage scenarios of several MW and less than 4 hours due to their safety, capacity characteristics, life and cost issues. The only large-scale, long-term energy storage technologies for offshore wind power with long-term application prospects are liquid air energy storage (LAES) and liquid CO2 energy storage (LCES).

[0004] Among them, the circulating working fluid of the LAES system is air, and the critical point of air is: 3.7MPa, -145℃. The critical point temperature is low, and the energy consumption required for gas-liquid conversion is large, so it is difficult to achieve gas-liquid conversion. The circulating working fluid of the LCES system is CO2, and the critical point of CO2 is: 7.4Mpa, 30℃. Compared with air, CO2 is easier to liquefy. Moreover, the viscosity of supercritical CO2 is relatively low and the density is relatively large. At the same power level, the compressed CO2 energy storage system is more compact than the compressed air energy storage system. In addition, unlike the compressed air energy storage system, the compressed CO2 energy storage system is a closed-loop system, which also provides a feasible way for the large-scale utilization of CO2. Therefore, LCES is the first choice for large-scale long-term energy storage on offshore platforms. The liquid CO2 energy storage system takes into account the characteristics of medium safety, environmental friendliness, low construction cost, and high energy storage density. It can be directly built on the offshore platform to store and re-issue the unevenly distributed offshore wind power in time, and continuously and smoothly supply it to the green power application on the shore.

[0005] At present, the world's first 10MW / 80MWh carbon dioxide energy storage demonstration system was successfully connected to the grid and generated electricity in Wuhu, Anhui on December 30, 2023. The project uses low-grade industrial waste heat above 40°C to improve the system's energy storage efficiency, and uses independently developed flexible materials as storage containers for gaseous carbon dioxide at room temperature and pressure. The space and load-bearing limitations of offshore platforms place high demands on the design and integration of energy storage systems. Therefore, the double-sided liquid CO2 energy storage method is more suitable for offshore platforms, which has the characteristics of high energy storage density and high integration. The project uses gaseous storage on the low-pressure side, with a low energy storage density, which is more suitable for onshore spaces with ample space, and cannot meet the high requirements of offshore platforms for the design and integration of energy storage systems.

[0006] In order to reduce the space required for the energy storage system and save floor space, patent CN118582266A invented a double-sided liquid carbon dioxide energy storage system and method, which can realize liquid storage on the low-pressure side and the high-pressure side. However, the double-sided liquid carbon dioxide energy storage system of patent CN118582266A only uses compression heat, and the expansion machine efficiency is low, which leads to low system cycle efficiency. The energy storage efficiency can only be maintained at about 60%, and the energy storage efficiency is low. Summary of the invention

[0007] The embodiment of the present application provides a double-sided liquid carbon dioxide energy storage system, which can simultaneously solve the technical problems of low energy storage density and low energy storage efficiency existing in the current double-sided liquid carbon dioxide energy storage system.

[0008] The embodiment of the present application provides a double-sided liquid carbon dioxide energy storage system, including: a low-pressure side liquid storage tank, a high-pressure side liquid storage tank, an energy storage mechanism, an energy release mechanism, a first low-temperature working medium storage tank, a first high-temperature working medium storage tank and a heating mechanism; the energy storage mechanism includes a low-pressure side gasifier, at least one group of energy storage components and a high-pressure side liquefier connected in sequence from the low-pressure side liquid storage tank to the high-pressure side liquid storage tank; each energy storage component includes a compressor and a cooler connected in sequence from the low-pressure side liquid storage tank to the high-pressure side liquid storage tank; the energy release mechanism includes a high-pressure side gasifier, at least one group of energy release components and a low-pressure side liquefier connected in sequence from the high-pressure side liquid storage tank to the low-pressure side liquid storage tank; each energy release component includes a compressor and a cooler connected in sequence from the high-pressure side liquid storage tank to the low-pressure side liquid storage tank A heater, a heat exchanger and an expander connected thereto; wherein the cold side inlet of each cooler is connected to the first storage tank for low-temperature working fluid, and the cold side outlet of each cooler is connected to the first storage tank for high-temperature working fluid; the hot side inlet of each heater is connected to the first storage tank for high-temperature working fluid, and the hot side outlet of each heater is connected to the first storage tank for low-temperature working fluid; the first working fluid circulates in the first storage tank for low-temperature working fluid, the cooler, the first storage tank for high-temperature working fluid and the heater; the heating mechanism comprises a second storage tank for low-temperature working fluid and a second storage tank for high-temperature working fluid, the hot side inlet of each heat exchanger is connected to the second storage tank for high-temperature working fluid, and the hot side outlet of each heat exchanger is connected to the second storage tank for low-temperature working fluid, and the second working fluid circulates in the second storage tank for high-temperature working fluid, the heat exchanger and the second storage tank for low-temperature working fluid.

[0009] In some embodiments, the heating mechanism further includes: a heat collector, which is connected to the second high-temperature working fluid storage tank and is used to heat the second working fluid in the second high-temperature working fluid storage tank.

[0010] In some embodiments, the collector includes at least one of a solar collector, a gas collector, an industrial waste heat recovery collector, a ground source heat pump collector, a seawater source heat pump collector, a biomass collector and a heat pipe collector.

[0011] In some embodiments, the heating mechanism also includes: a third storage tank for low-temperature working fluid and a third storage tank for high-temperature working fluid, the hot side inlet of each heat exchanger is connected to the third storage tank for high-temperature working fluid, the hot side outlet of each heat exchanger is connected to the third storage tank for low-temperature working fluid, and the second working fluid circulates in the third storage tank for high-temperature working fluid, the heat exchanger and the third storage tank for low-temperature working fluid.

[0012] In some embodiments, the collector is a solar collector; the hot side inlet of each heat exchanger is connected to the second high-temperature working fluid storage tank through a first pipeline, and a first valve is provided on the first pipeline; the hot side inlet of each heat exchanger is connected to the third high-temperature working fluid storage tank through a second pipeline, and a second valve is provided on the second pipeline; when there is sufficient sunlight, the solar collector heats the second working fluid in the second high-temperature working fluid storage tank and the second working fluid in the third high-temperature working fluid storage tank at the same time; the first valve is opened and the second valve is closed; when there is insufficient sunlight, the second valve is opened.

[0013] In some embodiments, a first high-temperature working fluid pump is provided on the first pipeline, and the first high-temperature working fluid pump is located between the first valve and the second high-temperature working fluid storage tank; a second high-temperature working fluid pump is provided on the second pipeline, and the second high-temperature working fluid pump is located between the second valve and the third high-temperature working fluid storage tank.

[0014] In some embodiments, the hot side outlet of each heat exchanger is connected to the second storage tank of low-temperature working fluid through a third pipeline, and a third valve is provided on the third pipeline; the hot side outlet of each heat exchanger is connected to the third storage tank of low-temperature working fluid through a fourth pipeline, and a fourth valve is provided on the fourth pipeline.

[0015] In some embodiments, a fifth valve is provided at the inlet of the second high-temperature working fluid storage tank, and a sixth valve is provided at the outlet of the second low-temperature working fluid storage tank; a seventh valve is provided at the inlet of the third high-temperature working fluid storage tank, and an eighth valve is provided at the outlet of the third low-temperature working fluid storage tank.

[0016] In some embodiments, the solar thermal collector includes at least one of a flat plate collector, an evacuated tube collector, a tube collector, a dish collector, and a tube-sheet collector.

[0017] In some embodiments, the first working medium includes at least one of air, surface water, groundwater, reclaimed water and seawater.

[0018] In some embodiments, the second working fluid includes heat transfer oil.

[0019] In some embodiments, the heat source of the low-pressure side gasifier includes at least one of seawater and air; the cold source of the high-pressure side liquefier includes seawater.

[0020] In some embodiments, the heat source of the high-pressure side gasifier includes at least one of seawater and air; the cold source of the low-pressure side liquefier includes liquefied natural gas, and the temperature of the liquefied natural gas is lower than -140°C.

[0021] In the double-sided liquid carbon dioxide energy storage system provided by the present application, the high-pressure liquid carbon dioxide in the high-pressure side liquid storage tank is vaporized by the high-pressure side vaporizer, firstly passes through a heater for a first heating, and then passes through a heat exchanger for a second heating, so as to improve the grade of CO2 in a step-by-step manner, thereby improving the circulation efficiency of the double-sided liquid carbon dioxide energy storage system.

[0022] The first working fluid in the low-temperature working fluid first storage tank of the present application enters the cooler to absorb the heat of the CO2 compressed by the compressor to cool the CO2, and then enters the high-temperature working fluid first storage tank, and then enters the heater from the outlet of the high-temperature working fluid first storage tank to heat the CO2 in the heater for the first time, and then enters the low-temperature working fluid first storage tank from the hot side outlet of the heater. By using the circulatory first working fluid to cool and heat the CO2, the energy consumption of the double-sided liquid carbon dioxide energy storage system can be greatly reduced, and the energy storage efficiency of the double-sided liquid carbon dioxide energy storage system can be improved.

[0023] The present application heats the second working fluid through the solar collector gas and then enters the heat exchanger to heat the CO2 in the heat exchanger, thereby utilizing renewable solar energy to heat the second working fluid and thus achieve heating of CO2, which can greatly improve the energy storage efficiency of the double-sided liquid carbon dioxide energy storage system.

[0024] The present application utilizes a high-pressure side liquid storage tank and a low-pressure side liquid storage tank to store compressed and liquefied liquid CO2 and expanded and liquefied liquid CO2, respectively, which can increase the energy storage density of CO2, reduce the floor space occupied by equipment, pipelines, etc., and ensure that the entire closed cycle is leak-free, thereby improving the safety of the offshore platform.

[0025] This application can use local materials, use seawater as the cold source of the high-pressure side liquefier, and use the liquefied natural gas in the liquid cargo tank as the cold source of the low-pressure side liquefier, which can reduce energy consumption, reduce the operating cost of the offshore platform, and meet the large-scale energy storage needs of the offshore platform. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For those skilled in the art, other drawings can be obtained based on these drawings without creative work.

[0027] Figure 1 A schematic diagram of the energy storage structure of the double-sided liquid carbon dioxide energy storage system of an embodiment of the present application;

[0028] Figure 2 A schematic diagram of the energy release structure of the double-sided liquid carbon dioxide energy storage system according to an embodiment of the present application;

[0029] Figure 3 It is a schematic diagram of the structure of the heating mechanism and the heat exchanger of an embodiment of the present application.

[0030] The components in the figure are marked as follows:

[0031] 100, low-pressure side liquid storage tank; 200, high-pressure side liquid storage tank; 300, low-temperature working fluid first storage tank; 400, high-temperature working fluid first storage tank;

[0032] 101, low-pressure side vaporizer; 102, compressor; 103, cooler; 104, high-pressure side liquefier;

[0033] 201, high-pressure side vaporizer; 202, heater; 203, heat exchanger; 204, expander; 205, low-pressure side liquefier;

[0034] 501, the second storage tank for low-temperature working fluid; 502, the second storage tank for high-temperature working fluid; 503, the collector; 504, the third storage tank for low-temperature working fluid; 505, the third storage tank for high-temperature working fluid; 506, the first pipeline; 507, the first valve; 508, the first pump for high-temperature working fluid; 509, the second pipeline; 510, the second valve; 511, the second pump for high-temperature working fluid; 512, the third pipeline; 513, the third valve; 514, the fourth pipeline; 515, the fourth valve; 516, the fifth valve; 517, the sixth valve; 518, the seventh valve; 519, the eighth valve. DETAILED DESCRIPTION

[0035] The preferred embodiments of the present application are described in detail below in conjunction with the drawings in the specification, so as to fully introduce the technical content of the present application to those skilled in the art, to illustrate that the present application can be implemented, to make the technical content disclosed in the present application clearer, and to make it easier for those skilled in the art to understand how to implement the present application. However, the present application can be embodied through many different forms of embodiments, and the protection scope of the present application is not limited to the embodiments mentioned in the text, and the description of the embodiments below is not intended to limit the scope of the present application.

[0036] The directional terms mentioned in this application, such as "up", "down", "front", "back", "left", "right", "inside", "outside", "side", etc., are only directions in the drawings. The directional terms used in this article are used to explain and illustrate this application, and are not used to limit the scope of protection of this application.

[0037] In the drawings, components with the same structure are represented by the same numerical labels, and components with similar structures or functions are represented by similar numerical labels. In addition, for the convenience of understanding and description, the size and thickness of each component shown in the drawings are arbitrarily shown, and the present application does not limit the size and thickness of each component.

[0038] Example 1

[0039] See also Figure 1 , Figure 2 and Figure 3The present application provides a double-sided liquid carbon dioxide energy storage system. The double-sided liquid carbon dioxide energy storage system includes: a low-pressure side liquid storage tank 100, a high-pressure side liquid storage tank 200, an energy storage mechanism, an energy release mechanism, a low-temperature working fluid first storage tank 300, a high-temperature working fluid first storage tank 400, and a heating mechanism 500.

[0040] See also Figure 1 , the energy storage mechanism includes a low-pressure side vaporizer 101, at least one group of energy storage components and a high-pressure side liquefier 104, which are connected in sequence from the low-pressure side liquid storage tank 100 to the high-pressure side liquid storage tank 200. Each energy storage component includes a compressor 102 and a cooler 103, which are connected in sequence from the low-pressure side liquid storage tank 100 to the high-pressure side liquid storage tank 200. In this embodiment, the energy storage mechanism includes four groups of energy storage components. That is, the energy storage mechanism includes four compressors 102, which are the first compressor 102A, the second compressor 102B, the third compressor 102C and the fourth compressor 102D. That is, the energy storage mechanism includes four coolers 103, which are the first cooler 103A, the second cooler 103B, the third cooler 103C and the fourth cooler 103D.

[0041] See also Figure 1 The low-pressure liquid CO2 in the low-pressure side liquid storage tank 100 passes through the low-pressure side gasifier 101, the first compressor 102A, the first cooler 103A, the second compressor 102B, the second cooler 103B, the third compressor 102C, the third cooler 103C, the fourth compressor 102D, the fourth cooler 103D, and the high-pressure side liquefier 104 in sequence until entering the high-pressure side liquid storage tank 200 to complete energy storage. The present application utilizes the high-pressure side liquid storage tank 200 to store compressed and liquefied liquid CO2, which can improve the energy storage density of CO2, reduce the floor space occupied by equipment, pipelines, etc., and the entire closed cycle is leak-free, thereby improving the safety of the offshore platform.

[0042] The heat source of the low-pressure side gasifier 101 includes at least one of seawater and air. In this example, the heat source of the low-pressure side gasifier 101 is seawater. The present application can use local materials and use seawater as the heat source of the low-pressure side gasifier 101, which can reduce energy consumption, reduce the operating cost of the offshore platform, and meet the demand for large-scale energy storage of the offshore platform.

[0043] The cold source of the high-pressure side liquefier 104 includes seawater. In this example, the cold source of the high-pressure side liquefier 104 is seawater. The present application can use local materials and use seawater as the cold source of the high-pressure side liquefier 104, which can reduce energy consumption, reduce the operating cost of the offshore platform, and meet the demand for large-scale energy storage of the offshore platform.

[0044] See also Figure 2, the energy release mechanism includes a high-pressure side vaporizer 201, at least one group of energy release components and a low-pressure side liquefier 205, which are sequentially connected from the high-pressure side liquid storage tank 200 to the low-pressure side liquid storage tank 100. Each energy release component includes a heater 202, a heat exchanger 203 and an expander 204, which are sequentially connected from the high-pressure side liquid storage tank 200 to the low-pressure side liquid storage tank 100. In this embodiment, the energy release mechanism includes two groups of energy release components. That is, the energy release mechanism includes two heaters 202, which are a first heater 202A and a second heater 202B. That is, the energy release mechanism includes two heat exchangers 203, which are a first heat exchanger 203A and a second heat exchanger 203B. That is, the energy release mechanism includes two expanders 204, which are a first expander 204A and a second expander 204B.

[0045] See also Figure 2 The high-pressure liquid CO2 in the high-pressure side liquid storage tank 200 passes through the high-pressure side gasifier 201, the first heater 202A, the first heat exchanger 203A, the first expander 204A, the second heater 202B, the second heat exchanger 203B, the second expander 204B, and the low-pressure side liquefier 205 in sequence until entering the low-pressure side liquid storage tank 100 to complete energy release. The present application utilizes the low-pressure side liquid storage tank 100 to store the expanded and liquefied liquid CO2, which can improve the energy storage density of CO2, reduce the floor space occupied by equipment, pipelines, etc., and the entire closed cycle is leak-free, thereby improving the safety of the offshore platform.

[0046] The heat source of the high-pressure side gasifier 201 includes at least one of seawater and air. In this example, the heat source of the high-pressure side gasifier 201 is seawater. The present application can use local materials to make the heat source of the high-pressure side gasifier 201, which can reduce energy consumption, reduce the operating cost of the offshore platform, and meet the demand for large-scale energy storage of the offshore platform.

[0047] The cold source of the low-pressure side liquefier 205 includes liquefied natural gas, and the temperature of the liquefied natural gas is lower than -140° C. The present application can use local materials and use the liquefied natural gas in the cargo tank as the cold source of the low-pressure side liquefier. The cold capacity is currently not used. Using it for cooling can reduce energy consumption, reduce the operating cost of the offshore platform, and meet the demand for large-scale energy storage of the offshore platform.

[0048] In the double-sided liquid carbon dioxide energy storage system provided in the embodiment of the present application, the high-pressure liquid carbon dioxide in the high-pressure side liquid storage tank 200 is vaporized by the high-pressure side vaporizer 201, firstly passes through the heater 202 for the first heating, and then passes through the heat exchanger 203 for the second heating, so as to improve the grade of CO2 in a step-by-step manner, thereby improving the circulation efficiency of the double-sided liquid carbon dioxide energy storage system.

[0049] See also Figure 1 and Figure 2, the cold side inlet of each cooler 103 is connected to the first low temperature working medium storage tank 300, and the cold side outlet of each cooler 103 is connected to the first high temperature working medium storage tank 400. The hot side inlet of each heater 202 is connected to the first high temperature working medium storage tank 400, and the hot side outlet of each heater 202 is connected to the first low temperature working medium storage tank 300. The first working medium circulates in the first low temperature working medium storage tank 300, the cooler 103, the first high temperature working medium storage tank 400 and the heater 202. The first working medium includes: at least one of air, surface water, groundwater, reclaimed water and seawater. In this embodiment, the first working medium is tap water. The first working fluid in the low-temperature working fluid first storage tank 300 of the present application enters the cooler 103 to absorb the heat of the CO2 compressed by the compressor 102 to cool the CO2, and then enters the high-temperature working fluid first storage tank 400, and then enters the heater 202 from the outlet of the high-temperature working fluid first storage tank 400 to heat the CO2 in the heater 202 for the first time, and then enters the low-temperature working fluid first storage tank 300 from the hot side outlet of the heater 202. By using the circulatory first working fluid to cool and heat CO2, the energy consumption of the double-sided liquid carbon dioxide energy storage system can be greatly reduced, and the energy storage efficiency of the double-sided liquid carbon dioxide energy storage system can be improved.

[0050] In other embodiments, local materials can be used to take seawater as the first working fluid, thereby reducing energy consumption, lowering the operating cost of the offshore platform, and meeting the demand for large-scale energy storage of the offshore platform.

[0051] See also Figure 3 The heating mechanism 500 includes a low-temperature working medium second storage tank 501 and a high-temperature working medium second storage tank 502. The hot side inlet of each heat exchanger 203 is connected to the high-temperature working medium second storage tank 502, and the hot side outlet of each heat exchanger 203 is connected to the low-temperature working medium second storage tank 501. The second working medium circulates in the high-temperature working medium second storage tank 502, the heat exchanger 203 and the low-temperature working medium second storage tank 501. The second working medium includes heat transfer oil. In this embodiment, the second working medium is heat transfer oil.

[0052] See also Figure 3, the heating mechanism 500 also includes: a collector 503. The collector 503 is connected to the second high-temperature working fluid storage tank 502 and is used to heat the second working fluid in the second high-temperature working fluid storage tank 502. Among them, the collector 503 includes at least one of a solar collector, a gas collector, an industrial waste heat recovery collector, a ground source heat pump collector, a seawater source heat pump collector, a biomass collector and a heat pipe collector. In this example, the collector 503 is a solar collector. The solar collector includes at least one of a flat plate collector, a vacuum tube collector, a tubular collector, a dish collector and a tube-sheet collector. In this way, the second working fluid can be heated by the solar collector gas and then enter the heat exchanger 203 to heat the CO2 in the heat exchanger 203. Thus, the second working fluid is heated by renewable solar energy and then the CO2 is heated, which can greatly improve the energy storage efficiency of the double-sided liquid carbon dioxide energy storage system.

[0053] See also Figure 3 The heating mechanism 500 further includes: a third low-temperature working medium storage tank 504 and a third high-temperature working medium storage tank 505. The hot side inlet of each heat exchanger 203 is connected to the third high-temperature working medium storage tank 505, and the hot side outlet of each heat exchanger 203 is connected to the third low-temperature working medium storage tank 504. The second working medium circulates in the third high-temperature working medium storage tank 505, the heat exchanger 203 and the third low-temperature working medium storage tank 504.

[0054] The hot side inlet of each heat exchanger 203 is connected to the second high temperature working medium storage tank 502 through the first pipeline 506. A first valve 507 is provided on the first pipeline 506, and a first high temperature working medium pump 508 is provided on the first pipeline 506. The first high temperature working medium pump 508 is located between the first valve 507 and the second high temperature working medium storage tank 502. The hot side outlet of each heat exchanger 203 is connected to the second low temperature working medium storage tank 501 through the third pipeline 512, and a third valve 513 is provided on the third pipeline 512. A fifth valve 516 is provided at the inlet of the second high temperature working medium storage tank 502, and a sixth valve 517 is provided at the outlet of the second low temperature working medium storage tank 501.

[0055] The hot side inlet of each heat exchanger 203 is connected to the third high temperature working medium storage tank 505 through the second pipeline 509, and the second pipeline 509 is provided with a second valve 510, and the second pipeline 509 is provided with a second high temperature working medium pump 511, and the second high temperature working medium pump 511 is located between the second valve 510 and the third high temperature working medium storage tank 505. The hot side outlet of each heat exchanger 203 is connected to the third low temperature working medium storage tank 504 through the fourth pipeline 514, and the fourth pipeline 514 is provided with a fourth valve 515. The inlet of the third high temperature working medium storage tank 505 is provided with a seventh valve 518, and the outlet of the third low temperature working medium storage tank 504 is provided with an eighth valve 519.

[0056] When the sun is sufficient, the solar collector heats the second working fluid in the second high-temperature working fluid storage tank 502 and the second working fluid in the third high-temperature working fluid storage tank 505 at the same time. At this time, the first valve 507 is opened and the second valve 510 is closed. In this way, when the sun is sufficient, the second working fluid in the third high-temperature working fluid storage tank 505 absorbs the heat of the solar collector for energy storage, and only the second working fluid in the second high-temperature working fluid storage tank 502 is used to perform secondary heating of CO2.

[0057] When the sunlight is insufficient, the second valve is opened. In this way, when the second working fluid in the second high-temperature working fluid storage tank 502 cannot meet the requirement of secondary heating of CO2, the second working fluid in the third high-temperature working fluid storage tank 505 can meet the requirement of secondary heating of CO2, thereby improving the energy storage efficiency of the double-sided liquid carbon dioxide energy storage system.

[0058] Compared with the double-sided liquid carbon dioxide energy storage system of patent CN118582266A, the double-sided liquid carbon dioxide energy storage system of the present application is aimed at liquid CO2 energy storage on offshore platforms. Seawater resources and solar energy resources are easy to access, which can greatly reduce the energy consumption of the double-sided liquid carbon dioxide energy storage system.

[0059] Specifically, in an offshore platform project, the energy storage capacity of the double-sided liquid carbon dioxide energy storage system is 10MW*8h. During the energy release stage, the second working fluid can heat CO2 to 150°C.

[0060] The collector absorbs solar radiation and converts it into heat energy to heat the second working medium (heat transfer oil). The temperature of the second working medium can reach 200-350°C, and the temperature of CO2 after heat exchange with the second working medium can reach above 150°C.

[0061] In the trough energy storage stage, the low-pressure liquid CO2 in the low-pressure side liquid storage tank 100 is gasified by the low-pressure side gasifier 101. The heat source of the gasifier 101 can be seawater or air. The temperature of the gasified CO2 can be in any range of 0 to 30°C. It is then compressed to a pressure of 7.4MPa by the four-stage compressor 102. The isentropic efficiency of the compressor 102 is 0.85, and the mechanical efficiency of the compressor 102 is 0.97. The compressed CO2 is liquefied by the high-pressure side liquefier 104 and stored in the high-pressure side liquid storage tank 200 for subsequent energy release. The first working fluid in the first cryogenic working fluid storage tank 300 is tap water.

[0062] In the peak energy release stage, the high-pressure liquid CO2 in the high-pressure side liquid storage tank 200 is first gasified by the high-pressure side gasifier 201, and then the temperature is stepped up. The CO2 working medium first enters the heater 202 and performs a heat exchange with the hot water from the first high-temperature working medium storage tank 400. Then, the CO2 working medium performs a secondary heat exchange with the second working medium (heat transfer oil) of the heating mechanism 500. According to the temperature of the second working medium (heat transfer oil), the temperature of CO2 before entering the expander 204 is 150°C. After the heat exchange with the second working medium (heat transfer oil) is completed, the CO2 working medium enters the first expander 204A for power generation. The expanded CO2 respectively exchanges heat with the hot water and the second working medium (heat transfer oil) from the first high-temperature working medium storage tank 400, and then enters the second expander 204B for power generation. The isentropic efficiency of the expander 204 is 0.8, and the mechanical efficiency of the expander 204 is 0.97. The low-pressure gaseous CO2 after power generation exchanges heat with the cold energy of LNG from the cargo tank. The temperature of LNG is -140°C, and the temperature of the exchanged CO2 reaches below -53°C and is stored in liquid form back in the low-pressure side liquid storage tank 100. The cycle efficiency of the above system can reach 72.9%.

[0063] Example 2

[0064] This embodiment includes most of the technical features of Embodiment 1. The difference between this embodiment and Embodiment 1 is that in an offshore platform project, the energy storage scale of the double-sided liquid carbon dioxide energy storage system is 20MW.

[0065] The collector absorbs solar radiation and converts it into heat energy to heat the second working medium (heat transfer oil). The temperature of the second working medium can reach 200-350°C, and the temperature of CO2 after heat exchange with the second working medium can reach above 150°C.

[0066] In the trough energy storage stage, the low-pressure liquid CO2 in the low-pressure side liquid storage tank 100 is gasified by the low-pressure side gasifier 101. The heat source of the gasifier 101 can be seawater or air. The temperature of the gasified CO2 can be in any range of 0 to 30°C. It is then compressed to a pressure of 7.4MPa by the four-stage compressor 102. The isentropic efficiency of the compressor 102 is 0.83, and the mechanical efficiency of the compressor 102 is 0.97. The compressed CO2 is liquefied by the high-pressure side liquefier 104 and stored in the high-pressure side liquid storage tank 200 for subsequent energy release. The first working fluid in the first cryogenic working fluid storage tank 300 is tap water.

[0067] In the peak energy release stage, the high-pressure liquid CO2 in the high-pressure side liquid storage tank 200 is first gasified by the high-pressure side vaporizer 201, and then the temperature is stepped up. The CO2 working medium first enters the heater 202 and performs a heat exchange with the hot water from the first high-temperature working medium storage tank 400. Then, the CO2 working medium performs a secondary heat exchange with the second working medium (heat transfer oil) of the heating mechanism 500. According to the temperature of the second working medium (heat transfer oil), the temperature of CO2 before entering the expander 204 is 160°C. After the heat exchange with the second working medium (heat transfer oil) is completed, the CO2 working medium enters the first expander 204A for power generation. The expanded CO2 respectively exchanges heat with the hot water and the second working medium (heat transfer oil) from the first high-temperature working medium storage tank 400, and then enters the second expander 204B for power generation. The isentropic efficiency of the expander 204 is 0.82, and the mechanical efficiency of the expander 204 is 0.95. The low-pressure gaseous CO2 after power generation exchanges heat with the cold energy of LNG from the cargo tank. The temperature of LNG is -140°C, and the temperature of CO2 after exchange reaches below -53°C, and is stored in liquid form back in the low-pressure side liquid storage tank 100. The cycle efficiency of the above system can reach 73.7%.

[0068] Example 3

[0069] This embodiment includes most of the technical features of Embodiment 1. The difference between this embodiment and Embodiment 1 is that this case is an extreme working condition. When the light is insufficient, the second working fluid in the heating mechanism 500 can only heat the CO2 at the inlet of the expander 204 to 120°C.

[0070] The collector absorbs solar radiation and converts it into heat energy to heat the second working medium (heat transfer oil). The temperature of the second working medium can reach 200-350°C, and the temperature of CO2 after heat exchange with the second working medium can reach above 120°C.

[0071] In the trough energy storage stage, the low-pressure liquid CO2 in the low-pressure side liquid storage tank 100 is gasified by the low-pressure side gasifier 101. The heat source of the gasifier 101 can be seawater or air. The temperature of the gasified CO2 can be in any range of 0 to 30°C. It is then compressed to a pressure of 7.4MPa by the four-stage compressor 102. The isentropic efficiency of the compressor 102 is 0.85, and the mechanical efficiency of the compressor 102 is 0.97. The compressed CO2 is liquefied by the high-pressure side liquefier 104 and stored in the high-pressure side liquid storage tank 200 for subsequent energy release. The first working fluid in the first cryogenic working fluid storage tank 300 is tap water.

[0072] In the peak energy release stage, the high-pressure liquid CO2 in the high-pressure side liquid storage tank 200 is first gasified by the high-pressure side gasifier 201, and then the temperature is stepped up. The CO2 working medium first enters the heater 202 and performs a heat exchange with the hot water from the first high-temperature working medium storage tank 400. Then, the CO2 working medium performs a secondary heat exchange with the second working medium (heat transfer oil) of the heating mechanism 500. According to the temperature of the second working medium (heat transfer oil), the temperature of CO2 before entering the expander 204 is 120°C. After the heat exchange with the second working medium (heat transfer oil) is completed, the CO2 working medium enters the first expander 204A for power generation. The expanded CO2 respectively exchanges heat with the hot water and the second working medium (heat transfer oil) from the first high-temperature working medium storage tank 400, and then enters the second expander 204B for power generation. The isentropic efficiency of the expander 204 is 0.8, and the mechanical efficiency of the expander 204 is 0.97. The low-pressure gaseous CO2 after power generation exchanges heat with the cold energy of LNG from the cargo tank. The temperature of LNG is -140°C, and the temperature of CO2 after exchange reaches below -53°C, and is stored back in the low-pressure side liquid storage tank 100 in liquid form. The cycle efficiency of the above system can reach 65.6%.

[0073] In summary, in the double-sided liquid carbon dioxide energy storage system of the present application, the high-pressure liquid carbon dioxide in the high-pressure side liquid storage tank 200 is gasified by the high-pressure side gasifier 201, firstly passes through the heater 202 for the first heating, and then passes through the heat exchanger 203 for the second heating, so as to improve the grade of CO2 in a step-by-step manner, thereby improving the circulation efficiency of the double-sided liquid carbon dioxide energy storage system.

[0074] In the above embodiments, the description of each embodiment has its own emphasis. For parts that are not described in detail in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0075] The above is a detailed introduction to a double-sided liquid carbon dioxide energy storage system provided in an embodiment of the present application. Specific examples are used in this article to illustrate the principles and implementation methods of the present application. The description of the above embodiments is only used to help understand the technical solution and its core idea of ​​the present application. Ordinary technicians in this field should understand that they can still modify the technical solutions recorded in the aforementioned embodiments, or replace some of the technical features therein with equivalents; and these modifications or replacements do not make the essence of the corresponding technical solution deviate from the scope of the technical solution of each embodiment of the present application.

Claims

1. A double-sided liquid carbon dioxide energy storage system, characterized in that: include: A low-pressure side liquid storage tank (100), a high-pressure side liquid storage tank (200), an energy storage mechanism, an energy release mechanism, a first low-temperature working fluid storage tank (300), a first high-temperature working fluid storage tank (400), and a heating mechanism; The energy storage mechanism comprises a low-pressure side vaporizer (101), at least one group of energy storage components and a high-pressure side liquefier (104) connected in sequence from the low-pressure side liquid storage tank (100) to the high-pressure side liquid storage tank (200); each of the energy storage components comprises a compressor (102) and a cooler (103) connected in sequence from the low-pressure side liquid storage tank (100) to the high-pressure side liquid storage tank (200); The energy release mechanism comprises a high-pressure side vaporizer (201), at least one set of energy release components and a low-pressure side liquefier (205) connected in sequence from the high-pressure side liquid storage tank (200) to the low-pressure side liquid storage tank (100); each of the energy release components comprises a heater (202), a heat exchanger (203) and an expander (204) connected in sequence from the high-pressure side liquid storage tank (200) to the low-pressure side liquid storage tank (100); The cold side inlet of each cooler (103) is connected to the first low-temperature working medium storage tank (300), and the cold side outlet of each cooler (103) is connected to the first high-temperature working medium storage tank (400); the hot side inlet of each heater (202) is connected to the first high-temperature working medium storage tank (400), and the hot side outlet of each heater (202) is connected to the first low-temperature working medium storage tank (300); the first working medium circulates in the first low-temperature working medium storage tank (300), the cooler (103), the first high-temperature working medium storage tank (400), and the heater (202); The heating mechanism comprises a low-temperature working medium second storage tank (501) and a high-temperature working medium second storage tank (502); the hot side inlet of each heat exchanger (203) is connected to the high-temperature working medium second storage tank (502); the hot side outlet of each heat exchanger (203) is connected to the low-temperature working medium second storage tank (501); and the second working medium circulates in the high-temperature working medium second storage tank (502), the heat exchanger (203) and the low-temperature working medium second storage tank (501).

2. The double-sided liquid carbon dioxide energy storage system according to claim 1, characterized in that: The heating mechanism further comprises: a heat collector (503), wherein the heat collector (503) is connected to the second high-temperature working fluid storage tank (502) and is used to heat the second working fluid in the second high-temperature working fluid storage tank (502).

3. The double-sided liquid carbon dioxide energy storage system according to claim 2, characterized in that: The collector (503) includes at least one of a solar collector, a gas collector, an industrial waste heat recovery collector, a ground source heat pump collector, a seawater heat pump collector, a biomass collector and a heat pipe collector.

4. The double-sided liquid carbon dioxide energy storage system according to claim 3, characterized in that: The heating mechanism further comprises: a third storage tank (504) for low-temperature working fluid and a third storage tank (505) for high-temperature working fluid, wherein the hot side inlet of each heat exchanger (203) is connected to the third storage tank (505) for high-temperature working fluid, and the hot side outlet of each heat exchanger (203) is connected to the third storage tank (504) for low-temperature working fluid, and the second working fluid circulates in the third storage tank (505) for high-temperature working fluid, the heat exchanger (203) and the third storage tank (504) for low-temperature working fluid.

5. The double-sided liquid carbon dioxide energy storage system according to claim 4, characterized in that: The heat collector (503) is a solar heat collector; The hot side inlet of each heat exchanger (203) is connected to the second high-temperature working medium storage tank (502) through a first pipeline (506), and a first valve (507) is provided on the first pipeline (506); the hot side inlet of each heat exchanger (203) is connected to the third high-temperature working medium storage tank (505) through a second pipeline (509), and a second valve (510) is provided on the second pipeline (509); When there is sufficient sunlight, the solar thermal collector heats the second working fluid in the second high-temperature working fluid storage tank (502) and the second working fluid in the third high-temperature working fluid storage tank (505) at the same time, opens the first valve (507), and closes the second valve (510); When the sunlight is insufficient, the second valve (510) is opened.

6. The double-sided liquid carbon dioxide energy storage system according to claim 5, characterized in that: A first high-temperature working fluid pump (508) is provided on the first pipeline (506), and the first high-temperature working fluid pump (508) is located between the first valve (507) and the second high-temperature working fluid storage tank (502); A second high-temperature working fluid pump (511) is provided on the second pipeline (509), and the second high-temperature working fluid pump (511) is located between the second valve (510) and the third high-temperature working fluid storage tank (505).

7. The double-sided liquid carbon dioxide energy storage system according to claim 5, characterized in that: The hot side outlet of each heat exchanger (203) is connected to the second low-temperature working medium storage tank (501) through a third pipeline (512), and a third valve (513) is provided on the third pipeline (512); The hot side outlet of each heat exchanger (203) is connected to the third low-temperature working medium storage tank (504) through a fourth pipeline (514), and a fourth valve (515) is provided on the fourth pipeline (514).

8. The double-sided liquid carbon dioxide energy storage system according to claim 7, characterized in that: A fifth valve (516) is provided at the inlet of the second high-temperature working medium storage tank (502), and a sixth valve (517) is provided at the outlet of the second low-temperature working medium storage tank (501); A seventh valve (518) is provided at the inlet of the third storage tank (505) for high-temperature working fluid, and an eighth valve (519) is provided at the outlet of the third storage tank (504) for low-temperature working fluid.

9. The double-sided liquid carbon dioxide energy storage system according to claim 3, characterized in that: The solar thermal collector includes at least one of a flat plate collector, a vacuum tube collector, a tube collector, a dish collector and a tube-sheet collector.

10. The double-sided liquid carbon dioxide energy storage system according to claim 1, characterized in that: The first working medium includes at least one of air, surface water, groundwater, reclaimed water and seawater.

11. The double-sided liquid carbon dioxide energy storage system according to claim 1, characterized in that: The second working medium includes heat transfer oil.

12. The double-sided liquid carbon dioxide energy storage system according to claim 1, characterized in that: The heat source of the low-pressure side vaporizer (101) includes at least one of seawater and air; and the cold source of the high-pressure side liquefier (104) includes seawater.

13. The double-sided liquid carbon dioxide energy storage system according to claim 1, characterized in that: The heat source of the high-pressure side gasifier (201) includes at least one of seawater and air; the cold source of the low-pressure side liquefier (205) includes liquefied natural gas, and the temperature of the liquefied natural gas is lower than -140°C.

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