Carbon dioxide energy storage system

Abstract

The utility model relates to the technical field of energy storage, and provides a carbon dioxide energy storage system. The utility model provides a carbon dioxide energy storage system. The carbon dioxide energy storage system comprises an air storage chamber, a compressor, a multi-stage multi-medium heat storage and release device, a liquid storage tank, an expansion machine and a heat dissipation device which are sequentially communicated and form a circulation loop. The gas storage chamber can store low-pressure carbon dioxide; the compressor can compress carbon dioxide to supercritical pressure; the multi-stage multi-medium heat storage and release device can store compression heat of the compressor and transfer the compression heat to carbon dioxide for expansion acting of the expansion machine; the liquid storage tank can store high-pressure liquid carbon dioxide. The utility model provides a carbon dioxide energy storage system, which is used for solving the technical problems of heat energy waste caused by single-medium primary heat storage and low energy storage efficiency caused by low air inlet temperature of an expansion machine in the prior art.

Description

Technical Field

[0001] The utility model relates to the technical field of energy storage, and particularly relates to a carbon dioxide energy storage system. Background Technique

[0002] With the continuous growth of global energy demand, the problems of energy shortage and environmental pollution have become increasingly prominent. To address these challenges, governments and research institutions around the world are seeking effective ways to save energy and reduce emissions. Among them, vigorously developing renewable energy sources such as wind energy and solar energy has become an important strategy to solve energy security problems and reduce environmental pollution. The utilization of these renewable energy sources has reduced the dependence on traditional fossil energy to a certain extent, helping to slow down global climate change and environmental degradation.

[0003] Although significant progress has been made in renewable energy technologies such as wind power generation and photovoltaic power generation, they still have some inherent limitations. The output of renewable energy is volatile, periodic, and uncertain, which poses challenges to large-scale grid connection and stable power supply of the power grid. To solve these problems, it is necessary to develop an efficient energy storage system that can smooth energy output and balance supply and demand.

[0004] Currently, the main energy storage technologies include pumped hydro storage, compressed air energy storage, and battery energy storage, etc. However, these technologies each have their own deficiencies: pumped hydro storage is limited by geographical conditions and is not easy to be widely promoted on a large scale; compressed air energy storage has problems such as low energy storage density and large heat loss; battery energy storage faces problems such as short lifespan, environmental impact, and safety hazards. These limitations have prompted people to explore and develop new energy storage technologies.

[0005] In recent years, with the improvement of environmental awareness, carbon dioxide, as a non-toxic, safe, and environmentally friendly natural working medium, has attracted people's attention again. The carbon dioxide energy storage system shows great application potential due to its advantages such as high energy storage efficiency, long lifespan, safety and stability, and relatively low cost.

[0006] The carbon dioxide energy storage system mainly consists of a compression unit, an expansion unit, a heat storage unit, and a carbon dioxide storage unit. The heat storage unit is responsible for storing the heat generated during compression during the energy storage process and releasing heat to heat carbon dioxide during the expansion process. Efficiently storing and releasing heat energy is crucial for improving the overall round-trip efficiency of the system.

[0007] However, traditional heat storage technologies, such as double-tank heat storage and direct and indirect heat storage in packed beds, usually adopt a one-stage heat storage method. These methods have deficiencies in the matching of the heat exchange curve between the heat storage medium and carbon dioxide, resulting in waste of heat energy. In addition, the exhaust temperature of the compressor is relatively low, which also limits the further improvement of energy storage efficiency. Content of the Utility Model

[0008] The present utility model provides a carbon dioxide energy storage system to solve the technical problems of heat energy waste caused by single-stage single-medium primary heat storage and low energy storage efficiency caused by low intake temperature of the expander in the prior art.

[0009] The present utility model provides a carbon dioxide energy storage system, including a gas storage chamber, a compressor, a multi-stage multi-medium heat storage and heat release device, a liquid storage tank, an expander and a heat dissipation device that are sequentially connected to form a circulation loop; the gas storage chamber can store carbon dioxide at low pressure; the compressor can compress the carbon dioxide to supercritical pressure; the multi-stage multi-medium heat storage and heat release device can accumulate the compression heat of the compressor and transfer the compression heat to the carbon dioxide for the expander to expand and do work; the liquid storage tank can store carbon dioxide in a high-pressure liquid state.

[0010] According to an embodiment of the present utility model, the multi-stage multi-medium heat storage and heat release device includes a molten salt heat storage and heat release unit and a heat transfer oil heat storage and heat release unit; the gas storage chamber, the compressor, the molten salt heat storage and heat release unit, the heat transfer oil heat storage and heat release unit, the liquid storage tank, the expander and the heat dissipation device are sequentially connected to form a circulation loop.

[0011] According to an embodiment of the present utility model, the multi-stage multi-medium heat storage and heat release device further includes a pressurized water heat storage and heat release unit, and the gas storage chamber, the compressor, the molten salt heat storage and heat release unit, the heat transfer oil heat storage and heat release unit, the pressurized water heat storage and heat release unit, the liquid storage tank, the expander and the heat dissipation device are sequentially connected to form a circulation loop.

[0012] According to an embodiment of the present utility model, the multi-stage multi-medium heat storage and heat release device further includes an atmospheric pressure water heat storage and heat release unit, and the gas storage chamber, the compressor, the molten salt heat storage and heat release unit, the heat transfer oil heat storage and heat release unit, the pressurized water heat storage and heat release unit, the atmospheric pressure water heat storage and heat release unit, the liquid storage tank, the expander and the heat dissipation device are sequentially connected to form a circulation loop.

[0013] According to an embodiment of the present utility model, the atmospheric pressure water heat storage and heat release unit includes a first cooler, a high-temperature atmospheric pressure water tank, a first heater and a low-temperature atmospheric pressure water tank; the first cooler has a first cooler heat exchange channel and a second cooler heat exchange channel; the first heater has a first heater heat exchange channel and a second heater heat exchange channel; the gas storage chamber, the compressor, the molten salt heat storage and heat release unit, the heat transfer oil heat storage and heat release unit, the pressurized water heat storage and heat release unit, the first cooler heat exchange channel, the liquid storage tank, the second heater heat exchange channel, the expander and the heat dissipation device are sequentially connected to form a circulation loop; the second cooler heat exchange channel, the high-temperature atmospheric pressure water tank, the first heater heat exchange channel and the low-temperature atmospheric pressure water tank are sequentially connected to form a circulation loop.

[0014] According to an embodiment of the present utility model, the pressurized water heat storage and release unit includes a second cooler, a high-temperature pressurized water tank, a second heater, and a low-temperature pressurized water tank; the second cooler has a third cooler heat exchange channel and a fourth cooler heat exchange channel; the second heater has a third heater heat exchange channel and a fourth heater heat exchange channel; the gas storage chamber, the compressor, the molten salt heat storage and release unit, the heat-conducting oil heat storage and release unit, the third cooler heat exchange channel, the first cooler heat exchange channel, the liquid storage tank, the second heater heat exchange channel, the fourth heater heat exchange channel, the expander, and the heat dissipation device are sequentially connected and form a circulation loop; the fourth cooler heat exchange channel, the high-temperature pressurized water tank, the third heater heat exchange channel, and the low-temperature pressurized water tank are sequentially connected and form a circulation loop.

[0015] According to an embodiment of the present utility model, the heat-conducting oil heat storage and release unit includes a third cooler, a high-temperature heat-conducting oil tank, a third heater, and a low-temperature heat-conducting oil tank; the third cooler has a fifth cooler heat exchange channel and a sixth cooler heat exchange channel; the third heater has a fifth heater heat exchange channel and a sixth heater heat exchange channel; the gas storage chamber, the compressor, the molten salt heat storage and release unit, the fifth cooler heat exchange channel, the third cooler heat exchange channel, the first cooler heat exchange channel, the liquid storage tank, the second heater heat exchange channel, the fourth heater heat exchange channel, the sixth heater heat exchange channel, the expander, and the heat dissipation device are sequentially connected and form a circulation loop; the sixth cooler heat exchange channel, the high-temperature heat-conducting oil tank, the fifth heater heat exchange channel, and the low-temperature heat-conducting oil tank are sequentially connected and form a circulation loop.

[0016] According to an embodiment of the present utility model, the molten salt heat storage and release unit includes a fourth cooler, a high-temperature molten salt tank, a fourth heater, and a low-temperature molten salt tank; the fourth cooler has a seventh cooler heat exchange channel and an eighth cooler heat exchange channel; the fourth heater has a seventh heater heat exchange channel and an eighth heater heat exchange channel; the gas storage chamber, the compressor, the seventh cooler heat exchange channel, the fifth cooler heat exchange channel, the third cooler heat exchange channel, the first cooler heat exchange channel, the liquid storage tank, the second heater heat exchange channel, the fourth heater heat exchange channel, the sixth heater heat exchange channel, the eighth heater heat exchange channel, the expander, and the heat dissipation device are sequentially connected and form a circulation loop; the eighth cooler heat exchange channel, the high-temperature molten salt tank, the seventh heater heat exchange channel, and the low-temperature molten salt tank are sequentially connected and form a circulation loop.

[0017] According to an embodiment of the present utility model, a pressurizing pump is further included, which is arranged between the liquid storage tank and the second heater heat exchange channel.

[0018] According to an embodiment of the present utility model, a throttle valve is further included, which is arranged between the gas storage chamber and the compressor.

[0019] The characteristics and advantages of the carbon dioxide energy storage system of the present utility model are:

[0020] The carbon dioxide energy storage system of the present utility model adopts an innovative multi-stage and multi-medium heat storage and heat release device in view of the heat energy waste problem caused by the primary heat storage medium in the prior art. This design allows the system to use the most suitable heat storage medium in different temperature ranges, ensuring a more efficient heat absorption and release process, and reducing heat loss caused by mismatched heat transfer performance. In this way, each heat storage medium can work within its most suitable temperature range, thereby improving the heat energy utilization efficiency of the entire energy storage system.

[0021] In addition, the compressor of the system can not only compress carbon dioxide to supercritical pressure, but also significantly increase the exhaust temperature. This increase is crucial for energy storage efficiency because a higher exhaust temperature means that the heat storage and heat release device can store more heat energy. When the system needs to release energy, this heat energy can be more effectively transferred to carbon dioxide, increasing the inlet temperature of the expander, allowing it to expand and do work in the expander, thereby improving the power generation efficiency.

[0022] In summary, the present utility model realizes the efficient storage and utilization of heat energy through a carefully designed multi-stage and multi-medium heat storage and heat release device and a strategy of increasing the compressor exhaust temperature. This not only solves the heat energy waste problem of the traditional primary heat storage medium, but also significantly improves the overall performance and power generation efficiency of the carbon dioxide energy storage system by increasing the heat energy conversion efficiency. Description of the Drawings

[0023] In order to more clearly illustrate the technical solutions in the present utility model or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present utility model. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0024] Figure 1 It is a schematic diagram of the carbon dioxide energy storage system of the present utility model;

[0025] Figure 2 It is another schematic diagram of the carbon dioxide energy storage system of the present utility model.

[0026] Reference Signs:

[0027] 1. Gas storage chamber; 2. Compressor; 3. Multi-stage and multi-medium heat storage and release device; 31. Molten salt heat storage and release unit; 311. Fourth cooler; 312. High-temperature molten salt tank; 313. Fourth heater; 314. Low-temperature molten salt tank; 32. Heat transfer oil heat storage and release unit; 321. Third cooler; 322. High-temperature heat transfer oil tank; 323. Third heater; 324. Low-temperature heat transfer oil tank; 33. Pressurized water heat storage and release unit; 331. Second cooler; 332. High-temperature pressurized water tank; 333. Second heater; 334. Low-temperature pressurized water tank; 34. Atmospheric pressure water heat storage and release unit; 341. First cooler; 342. High-temperature atmospheric pressure water tank; 343. First heater; 344. Low-temperature atmospheric pressure water tank; 4. Liquid storage tank; 5. Expander; 6. Heat dissipation device. Detailed implementation mode

[0028] To make the objectives, technical solutions and advantages of the present utility model clearer, the technical solutions in the present utility model will be clearly and completely described below with reference to the accompanying drawings in the present utility model. Apparently, the described embodiments are some but not all of the embodiments of the present utility model. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the present utility model without any creative effort shall fall within the protection scope of the present utility model.

[0029] In the description of this implementation mode, it should be understood that the orientation or positional relationships indicated by the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. are based on the orientation or positional relationships shown in the accompanying drawings, and are only for the convenience of describing this implementation mode and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus cannot be construed as a limitation to this implementation mode.

[0030] In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include at least one of such features. In the description of this implementation mode, the meaning of "a plurality" is at least two, such as two, three, etc., unless otherwise specifically and clearly defined.

[0031] In this embodiment, unless otherwise clearly defined and limited, terms such as "set", "installed", "connected", "linked", "fixed", etc. shall be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or integrated; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two components or the interaction relationship between two components, unless otherwise clearly defined. For those of ordinary skill in the art, the specific meanings of the above terms in this embodiment can be understood according to specific circumstances.

[0032] In the embodiment of the present utility model, unless otherwise clearly defined and limited, the first feature being "on" or "under" the second feature can be that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, the first feature being "above", "over" and "on top of" the second feature can be that the first feature is directly above or obliquely above the second feature, or merely indicates that the first feature has a higher horizontal height than the second feature. The first feature being "under", "beneath" and "underneath" the second feature can be that the first feature is directly below or obliquely below the second feature, or merely indicates that the first feature has a lower horizontal height than the second feature.

[0033] Figures 1 to 2 The carbon dioxide energy storage system provided by the present utility model is shown. It can be seen from the figure that the present utility model provides a carbon dioxide energy storage system, which includes a gas storage chamber 1, a compressor 2, a multi-stage multi-medium heat storage and heat release device 3, a liquid storage tank 4, an expander 5 and a heat dissipation device 6 that are connected in sequence to form a circulation loop; the gas storage chamber 1 can store low-pressure carbon dioxide; the compressor 2 can compress carbon dioxide to supercritical pressure; the multi-stage multi-medium heat storage and heat release device 3 can accumulate the compression heat of the compressor 2 and transfer the compression heat to the carbon dioxide for the expander 5 to expand and do work; the liquid storage tank 4 can store high-pressure liquid carbon dioxide.

[0034] For the technical problems of heat energy waste caused by single-medium primary heat storage and low energy storage efficiency caused by low intake temperature of the expander in the prior art, the carbon dioxide energy storage system of the present utility model adopts an innovative multi-stage multi-medium heat storage and heat release device 3. This design allows the system to use the most suitable heat storage medium in different temperature ranges, ensuring that the heat absorption and release processes are more efficient and reducing heat losses caused by mismatched heat transfer performance. In this way, each heat storage medium can work within its most suitable temperature range, thereby improving the heat energy utilization efficiency of the entire energy storage system.

[0035] In addition, the compressor 2 of the system can not only compress carbon dioxide to supercritical pressure, but also significantly increase the exhaust temperature. This increase is crucial for energy storage efficiency because a higher exhaust temperature means that the heat storage and release device can store more thermal energy. When the system needs to release energy, this thermal energy can be more effectively transferred to carbon dioxide, increasing the intake temperature of the expander 5 and enabling it to expand and do work in the expander, thereby improving the power generation efficiency. In summary, through the carefully designed multi-stage multi-medium heat storage and release device 3 and the strategy of increasing the exhaust temperature of the compressor 2, the present utility model realizes the efficient storage and utilization of thermal energy. This not only solves the problem of thermal energy waste in traditional single-stage heat storage media, but also significantly improves the overall performance and power generation efficiency of the carbon dioxide energy storage system by increasing the thermal energy conversion efficiency.

[0036] According to an embodiment of the present utility model, the multi-stage multi-medium heat storage and release device 3 includes a molten salt heat storage and release unit 31 and a heat transfer oil heat storage and release unit 32; the gas storage chamber 1, the compressor 2, the molten salt heat storage and release unit 31, the heat transfer oil heat storage and release unit 32, the liquid storage tank 4, the expander 5, and the heat dissipation device 6 are sequentially connected and form a circulation loop.

[0037] In specific implementation, by adopting the multi-stage multi-medium heat storage and release device 3, the thermal energy storage and conversion efficiency of the system is significantly improved. Specifically, the system includes a molten salt heat storage and release unit 31 and a heat transfer oil heat storage and release unit 32, which work in different temperature ranges respectively to adapt to the temperature changes of carbon dioxide during compression and expansion. The molten salt heat storage and release unit 31 utilizes the high heat capacity characteristic of molten salt at high temperatures to effectively store the high-temperature thermal energy generated during the operation of the compressor 2. The heat transfer oil heat storage and release unit 32 works in a lower temperature range to further absorb and store thermal energy. This multi-stage heat storage design ensures the effective capture and utilization of thermal energy throughout the operating temperature range and reduces heat loss. The working process of the system is as follows: Low-pressure carbon dioxide is first collected in the gas storage chamber 1 and then compressed by the compressor 2 to supercritical pressure. The resulting high-temperature and high-pressure carbon dioxide then enters the multi-stage heat storage and release device. Here, the heat is transferred to the molten salt and the heat transfer oil, and these media absorb thermal energy within their respective optimal temperature ranges. After that, the high-temperature and high-pressure carbon dioxide is stored in the liquid storage tank 4. When the system needs to release energy, the high-pressure liquid carbon dioxide stored in the liquid storage tank 4 is transported to the expander 5. At this time, the thermal energy stored in the heat storage and release device is used to heat the carbon dioxide to the temperature required for expansion, thereby driving the expander 5 to do work and generate electricity. Finally, the heat dissipation device 6 cools the carbon dioxide at the outlet of the expander 5 and returns it to the gas storage chamber 1 to complete the cycle.

[0038] According to an embodiment of the present utility model, the multi-stage multi-medium heat storage and heat release device 3 further includes a pressurized water heat storage and heat release unit 33. The gas storage chamber 1, the compressor 2, the molten salt heat storage and heat release unit 31, the heat transfer oil heat storage and heat release unit 32, the pressurized water heat storage and heat release unit 33, the liquid storage tank 4, the expander 5 and the heat dissipation device 6 are connected in sequence to form a circulation loop.

[0039] In specific implementation, the pressurized water heat storage and heat release unit 33 undertakes the tasks of heat energy storage and release in a medium temperature range in the system. Due to the fact that water has a high heat capacity and good heat exchange performance under pressurized conditions, it can effectively absorb and store the medium temperature heat energy generated during the operation of the compressor 2. In this way, the heat storage and heat release device can cover a wide temperature range from low temperature to high temperature, realizing more uniform and efficient heat energy management. The working process of the entire circulation loop is as follows: Low-pressure carbon dioxide is collected in the gas storage chamber 1 and then compressed to supercritical pressure by the compressor 2. The compressed high-temperature and high-pressure carbon dioxide flows through the molten salt, heat transfer oil and pressurized water heat storage and heat release unit 33 in sequence. These units absorb the heat of carbon dioxide in sequence according to their different working temperatures. The high-temperature molten salt heat storage and heat release unit 31 first captures the heat at the highest temperature, then the heat transfer oil heat storage and heat release unit 32 absorbs the medium-high temperature heat, and finally the pressurized water heat storage and heat release unit 33 stores the remaining medium temperature heat energy. In the energy release stage of the system, high-pressure liquid carbon dioxide flows out of the liquid storage tank 4 and is heated by the medium in the heat storage and heat release device through a heater to reach the high temperature required for expansion. Subsequently, the high-temperature and high-pressure carbon dioxide drives the expander 5 to do work and generate electricity. Finally, the heat dissipation device 6 cools the carbon dioxide with a reduced temperature after expansion and returns it to the gas storage chamber 1 to complete the entire cycle.

[0040] According to an embodiment of the present utility model, the multi-stage multi-medium heat storage and heat release device 3 further includes an atmospheric pressure water heat storage and heat release unit 34. The gas storage chamber 1, the compressor 2, the molten salt heat storage and heat release unit 31, the heat transfer oil heat storage and heat release unit 32, the pressurized water heat storage and heat release unit 33, the atmospheric pressure water heat storage and heat release unit 34, the liquid storage tank 4, the expander 5 and the heat dissipation device 6 are connected in sequence to form a circulation loop.

[0041] In specific implementation, the atmospheric-pressure water heat storage and release unit 34 is responsible for the storage and release of low to medium temperature thermal energy in the system. Since water is easily accessible and operable under atmospheric pressure and has good thermophysical properties, it can effectively absorb and store heat in the lower temperature range. In this way, the system can utilize this characteristic of atmospheric-pressure water to achieve effective thermal energy storage even in the lower temperature stage. The working process of the entire circulation loop is as follows: First, low-pressure carbon dioxide is collected in the gas storage chamber 1. Then, it is compressed by the compressor 2 to supercritical pressure, generating high-temperature and high-pressure carbon dioxide. This high-temperature and high-pressure carbon dioxide flows through the molten salt, heat transfer oil, pressurized water, and the atmospheric-pressure water heat storage and release unit 34 in sequence, and these units absorb and store heat in sequence according to their respective suitable temperature ranges. The molten salt heat storage and release unit 31 captures the heat at the highest temperature, the heat transfer oil heat storage and release unit 32 absorbs medium to high temperature heat, the pressurized water heat storage and release unit 33 stores medium temperature thermal energy, and the atmospheric-pressure water heat storage and release unit 34 is responsible for the storage of low to medium temperature heat. In the energy release stage of the system, high-pressure liquid carbon dioxide flows out from the liquid storage tank 4 and is heated by the heater using the thermal energy stored in the heat storage and release device to reach the high temperature required for expansion. Subsequently, this high-temperature and high-pressure carbon dioxide drives the expander 5 to do work and generate electricity. Finally, the heat dissipation device 6 cools the carbon dioxide with a reduced temperature after expansion and returns it to the gas storage chamber 1 to complete the entire cycle. By adding the atmospheric-pressure water heat storage and release unit 34, the carbon dioxide energy storage system of the present utility model not only improves the storage efficiency of thermal energy, but also realizes a more efficient and extensive thermal energy coverage through the collaborative work of the multi-stage heat storage and release devices, further enhancing the energy storage efficiency and power generation performance of the system. This design enables the system to more flexibly respond to different thermal energy demands, optimizes the utilization of thermal energy, and enhances the practicality and economy of the system.

[0042] According to an embodiment of the present utility model, the atmospheric-pressure water heat storage and release unit 34 includes a first cooler 341, a high-temperature atmospheric-pressure water tank 342, a first heater 343, and a low-temperature atmospheric-pressure water tank 344; the first cooler 341 has a first cooler heat exchange channel and a second cooler heat exchange channel; the first heater 343 has a first heater heat exchange channel and a second heater heat exchange channel; the gas storage chamber 1, the compressor 2, the molten salt heat storage and release unit 31, the heat transfer oil heat storage and release unit 32, the pressurized water heat storage and release unit 33, the first cooler heat exchange channel, the liquid storage tank 4, the second heater heat exchange channel, the expander 5, and the heat dissipation device 6 are sequentially connected and form a circulation loop; the second cooler heat exchange channel, the high-temperature atmospheric-pressure water tank 342, the first heater heat exchange channel, and the low-temperature atmospheric-pressure water tank 344 are sequentially connected and form a circulation loop.

[0043] In specific implementation, the first cooler 341 includes two heat exchange channels: the first cooler heat exchange channel and the second cooler heat exchange channel. The function of these channels is to transfer the heat in the high-temperature carbon dioxide generated by the compressor 2 to the normal-pressure water during the carbon dioxide compression stage, realizing the preliminary storage of thermal energy. The high-temperature normal-pressure water tank 342 is used to store the normal-pressure water heated by the first cooler 341, and this hot water stores a part of the thermal energy generated when the compressor 2 operates. The first heater 343 also includes two heat exchange channels: the first heater heat exchange channel and the second heater heat exchange channel. During the energy release stage of the system, these channels are used to transfer the thermal energy stored in the normal-pressure water to the carbon dioxide about to enter the expander 5, increasing its temperature, and thus improving the efficiency of expansion work. The low-temperature normal-pressure water tank 344 is used to store the normal-pressure water after releasing the thermal energy. After transferring the thermal energy to the carbon dioxide in the first heater 343, the temperature of this water decreases and is stored here for reuse in the next cycle. The working process of the entire circulation loop is as follows: The low-pressure carbon dioxide is collected in the gas storage chamber 1 and then compressed by the compressor 2 to the supercritical pressure. The compressed high-temperature and high-pressure carbon dioxide first enters the molten salt, heat transfer oil, pressurized water heat storage and heat release unit 33, and finally reaches the first cooler heat exchange channel, where part of the thermal energy is transferred to the normal-pressure water. The high-temperature normal-pressure water tank 342 stores the hot water. When the system needs to release energy, this hot water heats the carbon dioxide about to enter the expander 5 through the first heater heat exchange channel. After the expander 5 drives the generator to generate electricity, the cooled carbon dioxide returns to the gas storage chamber 1, and the normal-pressure water that has released the thermal energy flows back to the low-temperature normal-pressure water tank 344 to prepare for the next round of thermal energy absorption process.

[0044] According to an embodiment of the present invention, the pressurized water heat storage and heat release unit 33 includes a second cooler 331, a high-temperature pressurized water tank 332, a second heater 333, and a low-temperature pressurized water tank 334; the second cooler 331 has a third cooler heat exchange channel and a fourth cooler heat exchange channel; the second heater 333 has a third heater heat exchange channel and a fourth heater heat exchange channel; the gas storage chamber 1, the compressor 2, the molten salt heat storage and heat release unit 31, the heat transfer oil heat storage and heat release unit 32, the third cooler heat exchange channel, the first cooler heat exchange channel, the liquid storage tank 4, the second heater heat exchange channel, the fourth heater heat exchange channel, the expander 5, and the heat dissipation device 6 are sequentially connected and form a circulation loop; the fourth cooler heat exchange channel, the high-temperature pressurized water tank 332, the third heater heat exchange channel, and the low-temperature pressurized water tank 334 are sequentially connected and form a circulation loop.

[0045] In specific implementation, the second cooler 331 includes two heat exchange channels: the third cooler heat exchange channel and the fourth cooler heat exchange channel. The function of these heat exchange channels is to transfer the heat in the high-temperature and high-pressure carbon dioxide generated by the compressor 2 to the pressurized water during the carbon dioxide compression stage, thereby achieving the storage of thermal energy. The high-temperature pressurized water tank 332 is used to store the pressurized water heated by the second cooler 331. This hot water stores the thermal energy within a medium temperature range generated during the operation of the compressor 2. The second heater 333 also includes two heat exchange channels: the third heater heat exchange channel and the fourth heater heat exchange channel. During the energy release stage of the system, these channels are used to transfer the thermal energy stored in the pressurized water to the carbon dioxide about to enter the expander 5, further increasing its temperature, and thus increasing the efficiency of expansion work. The low-temperature pressurized water tank 334 is used to store the pressurized water after the release of thermal energy. After transferring the thermal energy to the carbon dioxide in the second heater 333, the temperature of this water decreases and is stored here for reuse in the next cycle. The working process of the entire circulation loop is as follows: Low-pressure carbon dioxide is collected in the gas storage chamber 1 and then compressed by the compressor 2 to supercritical pressure. The compressed high-temperature and high-pressure carbon dioxide first enters the molten salt and heat transfer oil heat storage and heat release unit 32, and then successively flows through the fifth cooler heat exchange channel and the first cooler heat exchange channel, transferring part of the thermal energy to the pressurized water and normal pressure water. The high-temperature pressurized water tank 332 stores the hot water. When the system needs to release energy, this hot water heats the carbon dioxide about to enter the expander 5 through the heat exchange channels of the second heater 333. After the expander 5 drives the generator to generate electricity, the cooled carbon dioxide returns to the gas storage chamber 1, and the pressurized water after the release of thermal energy flows back to the low-temperature pressurized water tank 334 to prepare for the next round of thermal energy absorption process.

[0046] According to an embodiment of the present invention, the heat transfer oil heat storage and heat release unit 32 includes a third cooler 321, a high-temperature heat transfer oil tank 322, a third heater 323, and a low-temperature heat transfer oil tank 324; the third cooler 321 has a fifth cooler heat exchange channel and a sixth cooler heat exchange channel; the third heater 323 has a fifth heater heat exchange channel and a sixth heater heat exchange channel; the gas storage chamber 1, the compressor 2, the molten salt heat storage and heat release unit 31, the fifth cooler heat exchange channel, the third cooler heat exchange channel, the first cooler heat exchange channel, the liquid storage tank 4, the second heater heat exchange channel, the fourth heater heat exchange channel, the sixth heater heat exchange channel, the expander 5, and the heat dissipation device 6 are sequentially connected and form a circulation loop; the sixth cooler heat exchange channel, the high-temperature heat transfer oil tank 322, the fifth heater heat exchange channel, and the low-temperature heat transfer oil tank 324 are sequentially connected and form a circulation loop.

[0047] In specific implementation, the third cooler 321 includes two heat exchange channels: the fifth cooler heat exchange channel and the sixth cooler heat exchange channel. These heat exchange channels play a key role in the carbon dioxide compression stage. They receive the high-temperature and high-pressure carbon dioxide from the compressor 2 and transfer its heat to the heat-conducting oil to achieve heat energy storage. The high-temperature heat-conducting oil tank 322 is used to store the heated heat-conducting oil, which absorbs the high-temperature heat energy generated during the operation of the compressor 2. The third heater 323 also includes two heat exchange channels: the fifth heater heat exchange channel and the sixth heater heat exchange channel. In the energy release stage of the system, these channels are responsible for transferring the heat energy stored in the heat-conducting oil to the carbon dioxide about to enter the expander 5, further increasing its temperature, thereby improving the efficiency of expansion work. The low-temperature heat-conducting oil tank 324 is used to store the heat-conducting oil after releasing the heat energy. After transferring the heat energy to the carbon dioxide in the third heater 323, the temperature of these oils decreases and they are stored here for reuse in the next cycle. The working process of the entire circulation loop is as follows: The low-pressure carbon dioxide is collected in the gas storage chamber 1 and then compressed by the compressor 2 to the supercritical pressure. The compressed high-temperature and high-pressure carbon dioxide first enters the molten salt heat storage and release unit 31, and then flows through the fifth cooler heat exchange channel, the third cooler heat exchange channel, and the first cooler heat exchange channel in sequence, gradually transferring the heat to the heat-conducting oil, pressurized water, and atmospheric pressure water. The high-temperature heat-conducting oil tank 322 stores the hot heat-conducting oil. When the system needs to release energy, this hot heat-conducting oil heats the carbon dioxide about to enter the expander 5 through the heat exchange channels of the third heater 323. After the expander 5 drives the generator to generate electricity, the cooled carbon dioxide returns to the gas storage chamber 1, and the heat-conducting oil that has released the heat energy flows back to the low-temperature heat-conducting oil tank 324 to prepare for the next round of heat energy absorption process.

[0048] According to an embodiment of the present invention, the molten salt heat storage and release unit 31 includes a fourth cooler 311, a high-temperature molten salt tank 312, a fourth heater 313, and a low-temperature molten salt tank 314; the fourth cooler 311 has a seventh cooler heat exchange channel and an eighth cooler heat exchange channel; the fourth heater 313 has a seventh heater heat exchange channel and an eighth heater heat exchange channel; the gas storage chamber 1, the compressor 2, the seventh cooler heat exchange channel, the fifth cooler heat exchange channel, the third cooler heat exchange channel, the first cooler heat exchange channel, the liquid storage tank 4, the second heater heat exchange channel, the fourth heater heat exchange channel, the sixth heater heat exchange channel, the eighth heater heat exchange channel, the expander 5, and the heat dissipation device 6 are sequentially connected and form a circulation loop; the eighth cooler heat exchange channel, the high-temperature molten salt tank 312, the seventh heater heat exchange channel, and the low-temperature molten salt tank 314 are sequentially connected and form a circulation loop.

[0049] In specific implementation, the fourth cooler 311 includes two heat exchange channels: the seventh cooler heat exchange channel and the eighth cooler heat exchange channel. During the carbon dioxide compression stage, these heat exchange channels are responsible for transferring the heat in the high-temperature and high-pressure carbon dioxide to the molten salt for thermal energy storage. The high-temperature molten salt tank 312 is used to store the heated molten salt, and this molten salt absorbs the high-temperature thermal energy generated when the compressor 2 operates in the fourth cooler 311. The fourth heater 313 also includes two heat exchange channels: the seventh heater heat exchange channel and the eighth heater heat exchange channel. During the system energy release stage, these heat exchange channels are responsible for transferring the thermal energy stored in the molten salt to the carbon dioxide about to enter the expander 5, thereby further increasing its temperature and the efficiency of expansion work. The low-temperature molten salt tank 314 is used to store the molten salt after releasing the thermal energy. After transferring the thermal energy to the carbon dioxide in the fourth heater 313, the temperature of this molten salt decreases and is stored here for reuse in the next cycle. The working process of the entire circulation loop is as follows: Low-pressure carbon dioxide is collected in the gas storage chamber 1 and then compressed by the compressor 2 to the supercritical pressure. The compressed high-temperature and high-pressure carbon dioxide flows through the seventh cooler heat exchange channel, the fifth cooler heat exchange channel, the third cooler heat exchange channel, and the first cooler heat exchange channel in sequence, gradually transferring the heat to the molten salt, heat transfer oil, pressurized water, and atmospheric pressure water. The high-temperature molten salt tank 312 stores the hot molten salt. When the system needs to release energy, this hot molten salt heats the carbon dioxide about to enter the expander 5 through the heat exchange channels of the fourth heater 313. After the expander 5 drives the generator to generate electricity, the cooled carbon dioxide returns to the gas storage chamber 1, and the molten salt that has released the thermal energy flows back to the low-temperature molten salt tank 314 to prepare for the next round of thermal energy absorption process.

[0050] According to an embodiment of the present invention, a pressure pump is further included, which is arranged between the liquid storage tank 4 and the second heater heat exchange channel.

[0051] In specific implementation, the main function of the pressure pump is to increase the pressure of the liquid carbon dioxide to ensure its effective circulation and flow in the system.

[0052] According to an embodiment of the present invention, a throttle valve is further included, which is arranged between the gas storage chamber 1 and the compressor 2.

[0053] In specific implementation, the addition of the throttle valve provides additional adjustment ability for the system to control the carbon dioxide flow rate entering the compressor 2, thereby affecting the compression process and the operating efficiency of the entire energy storage system.

[0054] In this embodiment, of course, the following is the text rearranged after deleting the content in the brackets:

[0055] 1. Gas storage chamber 1: Used to store gaseous carbon dioxide in a low-pressure state. After primary compression and multi-stage cooling, it enters the high-pressure liquid carbon dioxide storage tank for storage.

[0056] 2. Compressor 2: Used to compress low-pressure carbon dioxide into a high-pressure state, converting electrical energy into potential energy and heat energy.

[0057] 3. First cooler 341: Uses atmospheric-pressure water as the heat storage medium and adopts the direct heat storage method. The temperature range of this stage of heat storage is about 25 - 40 °C. This stage of heat storage is mainly used to liquefy CO2 and increase the energy storage density.

[0058] 4. Second cooler 331: Uses pressurized water as the heat storage medium and adopts the direct heat storage method. The temperature range of this stage of heat storage is about 25 - 200 °C.

[0059] 5. Third cooler 321: Uses heat-conducting oil as the heat storage medium and adopts the direct heat storage method. The temperature range of this stage of heat storage is about 200 - 300 °C.

[0060] 6. Fourth cooler 311: Uses high-temperature molten salt as the heat storage medium and adopts the direct heat storage method. The molten salt is in a fluid state and flows directly in the pipeline, capable of efficiently storing high-grade thermal energy in the fourth stage of heat storage. The temperature range is about 300 - 500 °C.

[0061] 7. High-pressure liquid carbon dioxide storage tank: Used to store carbon dioxide in a high-pressure state.

[0062] 8. First heater 343: Utilizes the low-temperature thermal energy stored in atmospheric-pressure water to heat and gasify high-pressure liquid carbon dioxide, realizing the gasification of carbon dioxide.

[0063] 9. Second heater 333: Further heats carbon dioxide using the heat stored in pressurized water to increase the temperature.

[0064] 10. Third heater 323: Further heats carbon dioxide using the heat stored in heat-conducting oil to increase the temperature.

[0065] 11. Fourth heater 313: Further heats carbon dioxide using the heat stored in molten salt to increase the temperature to above 400 °C. After four-stage heating, the temperature of carbon dioxide increases significantly, which is beneficial for subsequent expansion work.

[0066] 12. Expander 5: Used for the expansion of high-pressure carbon dioxide, connected to a generator. The work done by the expander 5 drives the generator to rotate and generate electricity.

[0067] 13. Radiator: When the temperature of the carbon dioxide at the outlet of the expander 5 is much higher than the ambient temperature, further heat dissipation and cooling are required to ensure the safety and stability of the gas storage chamber 1. The radiator medium can use the cooling water of the cooling tower, but is not limited to this form.

[0068] 14. High-temperature molten salt tank: Used to store the high-temperature molten salt after heat absorption.

[0069] 15. Low-temperature molten salt tank: used to store the low-temperature molten salt after heat release.

[0070] 16. High-temperature heat-conducting oil tank 322: used to store the high-temperature heat-conducting oil after heat absorption.

[0071] 17. Low-temperature heat-conducting oil tank 324: used to store the low-temperature heat-conducting oil after heat release.

[0072] 18. High-temperature pressurized water tank 332: used to store the high-temperature pressurized water after heat absorption.

[0073] 19. Low-temperature pressurized water tank 334: used to store the low-temperature pressurized water after heat release.

[0074] 20. High-temperature atmospheric pressure water tank 342: used to store the high-temperature atmospheric pressure water after heat absorption.

[0075] 21. Low-temperature atmospheric pressure water tank 344: used to store the low-temperature atmospheric pressure water after heat release.

[0076] In the present utility model, the compressor 2 and the expander 5 adopt a first-stage design, compressing carbon dioxide from atmospheric pressure to above the supercritical pressure to obtain a high exhaust temperature and increase the heat storage temperature. The heat storage method is not limited to four stages. Suitable heat storage working media are selected for each stage, and good matching between each stage is achieved.

[0077] The cooler and the heater can adopt forms such as shell-and-tube heat exchangers, plate heat exchangers, and finned heat exchangers. The equipment for storing carbon dioxide in the gaseous state at atmospheric pressure can adopt flexible air bags, artificial storage tanks, or natural gas storage spaces such as salt caverns, etc.; the equipment for storing liquid carbon dioxide uses pressure vessels made of cast iron or steel. Corresponding circulation pumps are also provided in the circulation pipelines of the heat storage media at each stage for the flow and heat exchange of the working medium.

[0078] The energy storage power generation subsystem operates in different time periods. During the low electricity consumption period at night, the compressor 2 is driven by the low-cost electricity or abandoned electricity from the power grid to compress carbon dioxide for energy storage; during the high electricity consumption period during the day, carbon dioxide expands to release energy and drives the generator to generate electricity. The heat storage media and carbon dioxide at each stage all circulate in a closed loop within the system.

[0079] The carbon dioxide energy storage system based on multi-stage heat storage proposed by the present utility model has the following beneficial effects:

[0080] 1. Innovatively propose a multi-medium coupled cascade heat storage carbon dioxide energy storage power generation technology, which can reduce the electricity consumption cost of the park through peak-valley price difference arbitrage, or be equipped near new energy power stations to improve the new energy power grid connection rate and reduce the phenomenon of abandoned wind and light.

[0081] 2. The stepped heat storage technology increases the heat storage temperature, reduces the heat energy loss during the heat storage and heat release processes, and significantly improves the energy storage efficiency of the system.

[0082] 3. The selected heat storage working media at each level are suitable for their working temperature ranges, match well between levels, and have high overall operating efficiency.

[0083] 4. Using carbon dioxide as the energy storage working medium has good environmental protection performance. Carbon dioxide has a relatively high molecular weight, enabling equipment miniaturization, a simple and compact system, and is suitable for large-scale popularization and application.

[0084] In the description of this specification, the descriptions with reference to terms such as "one embodiment", "some embodiments", "way", "specific way", or "some ways", etc. mean that the specific features, structures, materials, or characteristics described in connection with that embodiment or way are included in at least one embodiment or way of the embodiments of the present utility model. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or way. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable way in any one or more embodiments or ways. In addition, without contradiction, those skilled in the art can combine and combine the different embodiments or ways described in this specification and the features of different embodiments or ways.

[0085] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present utility model and are not intended to limit them; although the present utility model has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements for some of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present utility model.

Claims

1. A carbon dioxide energy storage system, characterized in that, It includes a gas storage chamber (1), a compressor (2), a multi-stage multi-medium heat storage and heat release device (3), a liquid storage tank (4), an expander (5) and a heat dissipation device (6) that are connected in sequence to form a circulation loop; the gas storage chamber (1) can store carbon dioxide at low pressure; The compressor (2) can compress the carbon dioxide to supercritical pressure; The multi-stage multi-medium heat storage and heat release device (3) can store the compression heat of the compressor (2) and transfer the compression heat to the carbon dioxide for the expander (5) to expand and do work; The liquid storage tank (4) can store carbon dioxide in a high-pressure liquid state.

2. The carbon dioxide energy storage system according to claim 1, wherein The multi-stage multi-medium heat storage and heat release device (3) includes a molten salt heat storage and heat release unit (31) and a heat transfer oil heat storage and heat release unit (32); The gas storage chamber (1), the compressor (2), the molten salt heat storage and heat release unit (31), the heat transfer oil heat storage and heat release unit (32), the liquid storage tank (4), the expander (5) and the heat dissipation device (6) are connected in sequence to form a circulation loop.

3. The carbon dioxide energy storage system according to claim 2, wherein The multi-stage multi-medium heat storage and heat release device (3) further includes a pressurized water heat storage and heat release unit (33), and the gas storage chamber (1), the compressor (2), the molten salt heat storage and heat release unit (31), the heat transfer oil heat storage and heat release unit (32), the pressurized water heat storage and heat release unit (33), the liquid storage tank (4), the expander (5) and the heat dissipation device (6) are connected in sequence to form a circulation loop.

4. The carbon dioxide energy storage system according to claim 3, characterized in that, The multi-stage multi-medium heat storage and heat release device (3) further includes an atmospheric pressure water heat storage and heat release unit (34), and the gas storage chamber (1), the compressor (2), the molten salt heat storage and heat release unit (31), the heat transfer oil heat storage and heat release unit (32), the pressurized water heat storage and heat release unit (33), the atmospheric pressure water heat storage and heat release unit (34), the liquid storage tank (4), the expander (5) and the heat dissipation device (6) are connected in sequence to form a circulation loop.

5. The carbon dioxide energy storage system according to claim 4, wherein The atmospheric pressure water heat storage and heat release unit (34) includes a first cooler (341), a high-temperature atmospheric pressure water tank (342), a first heater (343) and a low-temperature atmospheric pressure water tank (344); The first cooler (341) has a first cooler heat exchange channel and a second cooler heat exchange channel; The first heater (343) has a first heater heat exchange channel and a second heater heat exchange channel; The gas storage chamber (1), the compressor (2), the molten salt heat storage and heat release unit (31), the heat transfer oil heat storage and heat release unit (32), the pressurized water heat storage and heat release unit (33), the first cooler heat exchange channel, the liquid storage tank (4), the second heater heat exchange channel, the expander (5) and the heat dissipation device (6) are connected in sequence to form a circulation loop; The second cooler heat exchange channel, the high-temperature atmospheric pressure water tank (342), the first heater heat exchange channel and the low-temperature atmospheric pressure water tank (344) are connected in sequence to form a circulation loop.

6. The carbon dioxide energy storage system according to claim 5, characterized in that The pressurized water heat storage and heat release unit (33) includes a second cooler (331), a high-temperature pressurized water tank (332), a second heater (333) and a low-temperature pressurized water tank (334); The second cooler (331) has a third cooler heat exchange channel and a fourth cooler heat exchange channel; The second heater (333) has a third heater heat exchange channel and a fourth heater heat exchange channel; The gas storage chamber (1), the compressor (2), the molten salt heat storage and release unit (31), the heat transfer oil heat storage and release unit (32), the third cooler heat exchange channel, the first cooler heat exchange channel, the liquid storage tank (4), the second heater heat exchange channel, the fourth heater heat exchange channel, the expander (5) and the heat dissipation device (6) are connected in sequence to form a circulation loop; The fourth cooler heat exchange channel, the high-temperature pressurized water tank (332), the third heater heat exchange channel and the low-temperature pressurized water tank (334) are connected in sequence to form a circulation loop.

7. The carbon dioxide energy storage system according to claim 6, wherein The heat transfer oil heat storage and release unit (32) includes a third cooler (321), a high-temperature heat transfer oil tank (322), a third heater (323) and a low-temperature heat transfer oil tank (324); The third cooler (321) has a fifth cooler heat exchange channel and a sixth cooler heat exchange channel; The third heater (323) has a fifth heater heat exchange channel and a sixth heater heat exchange channel; The gas storage chamber (1), the compressor (2), the molten salt heat storage and release unit (31), the fifth cooler heat exchange channel, the third cooler heat exchange channel, the first cooler heat exchange channel, the liquid storage tank (4), the second heater heat exchange channel, the fourth heater heat exchange channel, the sixth heater heat exchange channel, the expander (5) and the heat dissipation device (6) are connected in sequence to form a circulation loop; The sixth cooler heat exchange channel, the high-temperature heat transfer oil tank (322), the fifth heater heat exchange channel and the low-temperature heat transfer oil tank (324) are connected in sequence to form a circulation loop.

8. The carbon dioxide energy storage system according to claim 7, wherein The molten salt heat storage and release unit (31) includes a fourth cooler (311), a high-temperature molten salt tank (312), a fourth heater (313) and a low-temperature molten salt tank (314); the fourth cooler (311) has a seventh cooler heat exchange channel and an eighth cooler heat exchange channel; The fourth heater (313) has a seventh heater heat exchange channel and an eighth heater heat exchange channel; The gas storage chamber (1), the compressor (2), the seventh cooler heat exchange channel, the fifth cooler heat exchange channel, the third cooler heat exchange channel, the first cooler heat exchange channel, the liquid storage tank (4), the second heater heat exchange channel, the fourth heater heat exchange channel, the sixth heater heat exchange channel, the eighth heater heat exchange channel, the expander (5) and the heat dissipation device (6) are connected in sequence to form a circulation loop; The eighth cooler heat exchange channel, the high-temperature molten salt tank (312), the seventh heater heat exchange channel and the low-temperature molten salt tank (314) are connected in sequence to form a circulation loop.

9. The carbon dioxide energy storage system according to claim 5, characterized in that, It further includes a pressure pump, which is arranged between the liquid storage tank (4) and the second heater heat exchange channel.

10. The carbon dioxide energy storage system according to any one of claims 1 to 9, characterized in that, It further includes a throttle valve, which is arranged between the gas storage chamber (1) and the compressor (2).

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