Carbon dioxide energy storage device and method for nuclear power system

Abstract

The invention relates to the technical field of nuclear power system energy management, and discloses a carbon dioxide energy storage device and method, and the device comprises a carbon dioxide capture unit, a compression liquefaction unit, a storage unit and an energy release power generation unit. Wherein the carbon dioxide capturing unit comprises at least two parallel absorption towers, and each absorption tower is provided with a cooling medium interface for connecting a nuclear power system cooling medium and a heating medium interface for connecting a nuclear waste heat medium; the compressing and liquefying unit is connected with the trapping unit, and the storage unit stores liquefied carbon dioxide; the energy-releasing power generation unit is connected with the storage unit and drives a power generator to generate power through liquid carbon dioxide cold energy and nuclear waste heat. According to the invention, the residual heat and cold source of the nuclear power system can be effectively utilized, continuous capture, liquefied storage and on-demand energy release of carbon dioxide are realized, and the peak clipping and valley filling requirements of small-sized or offshore nuclear power devices are met.

Description

Technical Field

[0001] This invention relates to the field of energy management technology for nuclear power systems, and in particular to a carbon dioxide energy storage device and energy storage method for nuclear power systems. Background Technology

[0002] Small nuclear power plants and offshore floating nuclear power platforms generally face the challenge of unstable and highly volatile load demand due to the unique operating environment. Unlike traditional large nuclear power plants connected to a large power grid, these small nuclear power units often operate in a regional or islanded mode, exhibiting significant peak-valley characteristics in their load. Limited by economic and technical constraints, the load tracking capability of these units is usually weak, and excess energy generated during off-peak periods is difficult to utilize effectively and is often directly discarded, resulting in energy waste. For offshore floating platforms, load changes are even more rapid and drastic. Nuclear power systems have high inertia and slow response, making it difficult to adapt to such rapidly changing load demands. Especially in islanded operation, the lack of effective energy storage and peak-shaving methods has become a key issue restricting their stable and economical operation.

[0003] Currently, to address the energy storage needs of nuclear power plants for peak shaving and valley filling, the main technological approaches considered in this field include pumped hydro storage, compressed air storage, and electrochemical energy storage. Pumped hydro storage is a mature technology, but it has stringent geographical requirements, necessitating the construction of reservoirs and requiring a large land area, making it difficult to apply in space-constrained small nuclear power plant sites or offshore platforms. Compressed air storage faces similar challenges, relying on large underground gas storage caverns or pressure vessels, requiring significant site volume and limiting its applicability. Electrochemical energy storage, such as lithium-ion batteries or flow batteries, while offering improved energy density, still faces safety challenges in megawatt-level applications, with a high risk of accidents. Furthermore, its limited cycle life and performance degradation issues are difficult to match with the long design life of nuclear power plants. Therefore, developing an energy storage device suitable for small-scale and offshore nuclear power scenarios that is safe, reliable, environmentally adaptable, and capable of long-term stable operation is urgently needed and of great significance. Summary of the Invention

[0004] This invention provides a carbon dioxide energy storage device and method for nuclear power systems. It can effectively utilize the waste heat and cold source of the nuclear power system itself to achieve continuous capture, liquefaction and storage of carbon dioxide and release it on demand to do work, without relying on specific geographical conditions and ensuring system safety. This effectively meets the peak shaving and valley filling function requirements of small or offshore nuclear power plants.

[0005] The present invention provides a carbon dioxide energy storage device for a nuclear power system, comprising: A carbon dioxide capture unit includes at least two absorption towers arranged in parallel, wherein the at least two absorption towers are used to alternately adsorb and desorb carbon dioxide directly from ambient air; The absorption tower is equipped with a cooling medium interface and a heating medium interface. The cooling medium interface is used to connect to the cooling medium, and the heating medium interface is used to connect to the waste heat medium generated by the nuclear power system. A compression-liquefaction unit, connected to the carbon dioxide capture unit, is used to compress and liquefy the desorbed carbon dioxide; Storage unit for storing liquefied carbon dioxide; An energy-generating unit is connected to the storage unit and is configured to use the cold energy of liquid carbon dioxide from the storage unit and the waste heat medium generated by the nuclear power system to drive a generator to generate electricity.

[0006] In one embodiment of the present invention, the energy release power generation unit includes an expansion energy release unit and a waste heat utilization and recycling unit; the expansion energy release unit is connected to the storage tank and is connected to a generator, which is used to release energy by expanding the liquid carbon dioxide output from the storage tank after absorbing heat, and to drive the generator to generate electricity; the waste heat utilization and recycling unit is connected between the storage tank and the expansion energy release unit, and is used to exchange heat and recycle the liquid carbon dioxide output from the storage tank and the waste heat medium of the nuclear power system.

[0007] In one embodiment of the present invention, the expansion energy release unit includes a carbon dioxide expander and an organic working fluid expander, and the generator is drivenly connected to both the carbon dioxide expander and the organic working fluid expander; wherein, the working fluid inlet of the carbon dioxide expander is connected to the storage tank through a pipeline, and is used to receive carbon dioxide that has been vaporized after absorbing heat and to drive the generator to generate electricity through expansion; the organic working fluid expander is used to receive organic working fluid heated by waste heat and to drive the generator to generate electricity through expansion.

[0008] In one embodiment of the present invention, the waste heat utilization recycling unit includes a working fluid pump, a working fluid / carbon dioxide heat exchanger, and a working fluid waste heat exchanger. The working fluid pump drives the working fluid to flow within the recycling unit. The hot-side interface of the working fluid waste heat exchanger is connected to the waste heat medium of the nuclear power system to absorb waste heat. The working fluid / carbon dioxide heat exchanger is used to transfer the heat absorbed by the working fluid to the liquid carbon dioxide output from the storage tank, thereby realizing the recycling of waste heat.

[0009] In one embodiment of the present invention, the energy release power generation unit includes: A carbon dioxide expander, the working fluid inlet of which is connected to the storage unit via a pipeline; Organic working fluid circuit, including organic working fluid expander; A generator is connected to the carbon dioxide expander and the organic working fluid expander; The pipeline is equipped with a waste heat exchanger, and the hot side interface of the waste heat exchanger is used to connect to the waste heat medium generated by the nuclear power system. The organic working fluid circuit is equipped with a working fluid / carbon dioxide heat exchanger and a working fluid waste heat heat exchanger. The working fluid / carbon dioxide heat exchanger is used to exchange heat with the liquid carbon dioxide output from the storage unit, and the hot side interface of the working fluid waste heat heat exchanger is used to connect to the waste heat medium generated by the nuclear power system.

[0010] In one embodiment of the present invention, the adsorbent is one or more of the following: solid amine adsorbent, metal-organic framework, non-amine adsorbent resin, covalent organic framework, or lithium-zeolite.

[0011] In one embodiment of the present invention, the cooling medium connected to the cooling medium interface of the absorption tower includes condensate water or seawater from the condenser of the nuclear power system, and the heating medium interface is used to connect condensate water or exhaust steam from the secondary loop of the nuclear power system.

[0012] In one embodiment of the present invention, the compression liquefaction unit includes a compressor, and a first cooler and a second cooler disposed before and after the compressor. The first cooler is used to cool the desorbed carbon dioxide, and the second cooler is used to cool the compressed carbon dioxide to a near-liquefied state.

[0013] In one embodiment of the present invention, the working fluid / carbon dioxide heat exchanger in the organic working fluid circuit is located downstream of the outlet of the storage unit, the cold side flow channel of the working fluid / carbon dioxide heat exchanger is connected to the organic working fluid circuit, and the hot side flow channel of the working fluid / carbon dioxide heat exchanger is connected to the pipeline before the carbon dioxide expander.

[0014] In one embodiment of the present invention, the waste heat exchanger on the pipeline is a first waste heat vaporizer, and its hot-side interface is configured to be connected to the exhaust steam of the second loop of the nuclear power system; the working fluid waste heat exchanger on the organic working fluid loop is a second waste heat vaporizer, and its hot-side interface is configured to be connected to the condensate of the second loop of the nuclear power system.

[0015] In one embodiment of the present invention, a waste heat superheater is further provided downstream of the second waste heat vaporizer, the hot side interface of which is configured to be connected to the exhaust steam or condensate of the second loop of the nuclear power system, for heating the organic working fluid to a superheated state.

[0016] In one embodiment of the present invention, the carbon dioxide energy storage device for a nuclear power system further includes a fan connected to the air inlet of the absorption tower.

[0017] The present invention also provides a carbon dioxide energy storage method for a nuclear power system, characterized by comprising the following steps: in one embodiment of the present invention, the cooling medium provided by the nuclear power system is condensate from the condenser of the nuclear power system or seawater taken from a floating platform at sea; the waste heat medium generated by the nuclear power system is condensate from the secondary loop of the nuclear power system or exhaust steam.

[0018] In one embodiment of the present invention, during the energy release process, the cold energy of the liquid carbon dioxide output from the storage unit is recovered and utilized sequentially through the heat exchanger in the energy release power generation unit, and the thermal energy of the waste heat medium generated by the nuclear power system is recovered and utilized sequentially through the heat exchanger in the energy release power generation unit, so as to realize the multi-level utilization of cold energy and thermal energy.

[0019] The present invention also provides a method for carbon dioxide energy storage in a nuclear power system, comprising the following steps: Capture steps: Carbon dioxide is directly and alternately adsorbed and desorbed from ambient air using at least two absorption towers connected in parallel; wherein, a cooling medium provided by the nuclear power system is introduced into the absorption tower performing the adsorption operation; and a waste heat medium generated by the nuclear power system is introduced into the absorption tower performing the desorption operation. Compression liquefaction step: The carbon dioxide desorbed from the absorption tower is compressed and cooled to liquefy it; Storage steps: Store the liquefied carbon dioxide in the storage unit; Energy release and power generation steps: During peak energy demand periods, liquid carbon dioxide from the storage unit is first transported to a working fluid / carbon dioxide heat exchanger to exchange heat with an organic working fluid, and then transported to a waste heat heat exchanger to heat and vaporize it using the waste heat medium generated by the nuclear power system; the vaporized carbon dioxide is then introduced into a carbon dioxide expander to expand and do work. Furthermore, the organic working fluid is cooled by liquid carbon dioxide as it flows through the working fluid / carbon dioxide heat exchanger, and then the cooled organic working fluid is compressed, heated and vaporized by the waste heat medium generated by the nuclear power system, and then introduced into the organic working fluid expander to expand and do work; the carbon dioxide expander and the organic working fluid expander together drive the generator to generate electricity.

[0020] The beneficial effects of this invention are as follows: This invention proposes a carbon dioxide energy storage device for nuclear power systems. By setting up a carbon dioxide capture unit including at least two parallel absorption towers and configuring a cooling medium interface and a heating medium interface, it can directly utilize the cooling medium and waste heat medium provided by the nuclear power system, achieving effective and continuous capture and desorption of carbon dioxide from the air. The desorbed carbon dioxide is processed by a compression liquefaction unit and then stored in a storage unit. When energy needs to be released, the cold energy of the liquid carbon dioxide from the storage unit and the waste heat medium generated by the nuclear power system are used to drive a generator to generate electricity. This device directly uses carbon dioxide from the air as the medium, eliminating the need for pre-stored working fluid and freeing it from dependence on special geographical conditions. The entire process fully utilizes the inherent heat sink and heat source of the nuclear power system, achieving cascaded energy utilization. The device mainly operates based on a mechanical structure, avoiding the safety and lifespan limitations of electrochemical energy storage, and possessing higher reliability and a long lifespan potential matching that of nuclear power plants. Its system has a compact structure and high energy density, making it suitable for small nuclear power plants or offshore floating nuclear power platforms with limited space, providing them with a safe, effective and flexible peak shaving and valley filling solution. Attached Figure Description

[0021] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application. It is obvious that the drawings described below are merely some embodiments of this application, and those skilled in the art can obtain other drawings based on these drawings without any inventive effort.

[0022] In the attached diagram: Figure 1 This is a schematic diagram of a carbon dioxide energy storage device for a nuclear power system according to an embodiment of the present invention; The attached figures are labeled as follows: Carbon dioxide capture unit 10, first absorption tower 11, second absorption tower 12, cooling medium A, waste heat medium B, first absorption tower inlet valve 13, first absorption tower air exhaust valve 14, first absorption tower outlet valve 15, second absorption tower inlet valve 16, second absorption tower outlet valve 17, second absorption tower air exhaust valve 18, fan 19, compression liquefaction unit 20, compressor 21, first cooler 22, second cooler 23, throttle valve 24, storage unit 30, gas supply valve 31, energy release and power generation unit 40, carbon dioxide expander 41, organic working fluid expander 42, generator 43, waste heat heat exchanger 44, working fluid / carbon dioxide heat exchanger 45, waste heat superheater 46, working fluid pump 47, organic working fluid circuit. Detailed Implementation

[0023] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments. Various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. In the absence of conflict, the following embodiments and features in the embodiments can be combined with each other.

[0024] It should be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of the present invention. The drawings only show the components related to the present invention and are not drawn according to the actual number, shape and size of the components in the actual implementation. In the actual implementation, the form, quantity and proportion of each component can be arbitrarily changed, and the layout of the components may also be more complex.

[0025] In the following description, numerous details are explored to provide a more thorough explanation of embodiments of the invention. However, it will be apparent to those skilled in the art that embodiments of the invention may be practiced without these specific details. In other embodiments, well-known structures and devices are shown in block diagram form rather than in detail to avoid obscuring embodiments of the invention.

[0026] Small nuclear power plants offer advantages such as high safety and versatility, but they face the challenge of unstable load demand. Unlike the grid users served by traditional large nuclear power units, small nuclear power plants typically serve regionally focused, small-scale users with distinct peak-valley load demands. Furthermore, due to economic considerations and technological limitations, small nuclear power plants have weaker load tracking capabilities, and the energy generated during off-peak periods is easily discarded, resulting in energy waste.

[0027] While nuclear power offers significant advantages for offshore floating nuclear-powered platforms due to its independence from air and high energy density, the rapid and volatile nature of marine energy loads, coupled with the complexity of nuclear power systems, significant load tracking inertia, and lag in regulation, makes it difficult to adapt to rapid changes in external load demands. This is especially true when the offshore floating nuclear-powered platform is operating in an isolated environment, where the need for energy storage capacity becomes even more urgent.

[0028] When external energy demand is insufficient, energy storage devices can be used to store and absorb excess energy load, and then output it during peak energy demand periods. This is of great significance for the stable operation of small nuclear power plants and offshore floating nuclear power platforms, the full utilization of energy, and the improvement of economic efficiency.

[0029] Energy storage devices used for peak shaving and valley filling in nuclear power plants need to have megawatt-level energy storage capacity. Currently, the technologies that are widely used and have large-scale energy storage capacity mainly include pumped hydro storage, compressed air storage, and electrochemical energy storage.

[0030] For example, existing technologies utilize pumped-storage hydroelectric power, which uses water as the energy storage medium. It stores and manages electrical energy through the conversion of electrical energy and potential energy. Specifically, during periods of low electricity demand, water is pumped to an upstream reservoir using electricity, and during peak demand periods, the water is released to a downstream reservoir to drive power generation. This converts excess electricity during off-peak periods into high-value electricity during peak periods. The main drawback of this approach is that pumped-storage technology requires the construction of a hydroelectric power station with a certain gravitational potential energy difference, placing stringent requirements on the geographical conditions of the application environment, and incurring high investment costs. Small nuclear power plants have relatively small footprints and high economic requirements, therefore, this type of energy storage device is not suitable for small nuclear power plants; furthermore, the geographical conditions of offshore floating nuclear power platforms cannot meet the application requirements of pumped-storage hydroelectric power.

[0031] For example, existing technologies utilize compressed air energy storage. This technology uses electricity to compress air during periods of low grid load and stores the high-pressure air in sealed containers such as abandoned mines, submerged seabed gas tanks, caves, expired oil and gas wells, or newly built gas wells. During peak grid load periods, the compressed air is released to drive a steam turbine to generate electricity. The main drawback of this approach is that compressed air energy storage technology requires large-volume gas pressure vessels, imposing stringent requirements on the space and footprint of the application environment. It also cannot meet the application needs of small nuclear power plants and offshore floating nuclear power platforms, for reasons similar to the incompatibility of pumped-storage technology.

[0032] For example, existing technologies utilize electrochemical energy storage (including lithium-ion batteries, flow batteries, etc.). This technology converts electrical energy into chemical energy through electrochemical reactions for storage, and then converts the chemical energy back into electrical energy when needed. Specifically, it achieves energy storage and release through the charging and discharging process of batteries or similar chemical devices. Based on the different energy storage media, it can be mainly divided into lead-acid batteries, sodium-sulfur batteries, flow batteries, and lithium-ion batteries. The main drawback of this approach is that although lithium-ion batteries and flow batteries currently possess high energy density, their safe application in megawatt-level energy storage scenarios still faces challenges. Various malfunctions and combustion accidents occur frequently, failing to meet the nuclear safety application requirements of small nuclear power plants and offshore floating nuclear power platforms. Furthermore, electrochemical energy storage devices generally suffer from performance degradation and self-discharge characteristics. As usage time increases, their electrochemical activity gradually decreases, resulting in a shorter designed lifespan that cannot match the design life of nuclear power plants.

[0033] In response to the characteristics of small nuclear power plants, such as insufficient peak-shaving capacity, limited land use, and "off-grid" sites (i.e., regionalized and small-scale users), as well as the peak-shaving and valley-filling needs of offshore floating nuclear power platforms operating in isolated environments, this solution adopts a method of directly capturing carbon dioxide from the air to provide energy storage for small nuclear power plants and offshore floating nuclear power platforms, thereby alleviating their load regulation pressure. When external energy demand is insufficient, the excess energy load is stored and absorbed through this energy storage device, and then output to the outside world during peak energy demand periods.

[0034] The present invention provides a carbon dioxide energy storage device for a nuclear power system, comprising: a carbon dioxide capture unit 10, a compression liquefaction unit 20, a storage unit 30, and an energy release and power generation unit 40; The carbon dioxide capture unit 10 includes at least two absorption towers arranged in parallel, each containing an adsorbent. Each absorption tower has a cooling medium A interface and a heating medium interface. The cooling medium A interface is used to connect to cooling medium A provided by the nuclear power system, and the heating medium interface is used to connect to waste heat medium B generated by the nuclear power system. A compression-liquefaction unit 20, connected to the carbon dioxide capture unit 10, is used to compress and liquefy the desorbed carbon dioxide. A storage unit 30 is used to store the liquefied carbon dioxide. An energy release and power generation unit 40, connected to the storage unit 30, is configured to use the cold energy from the liquid carbon dioxide in the storage unit 30 and the waste heat medium B generated by the nuclear power system to drive a generator 43 to generate electricity.

[0035] As an optional embodiment of this case, the energy release power generation unit 40 includes a carbon dioxide expander 41, an organic working fluid loop 48, and a generator 43; the working fluid inlet of the carbon dioxide expander 41 is connected to the storage unit 30 through a pipeline; the organic working fluid loop 48 includes an organic working fluid expander 42; the generator 43 is connected to the carbon dioxide expander 41 and the organic working fluid expander 42; wherein, a waste heat exchanger 44 is provided on the pipeline, and the hot side interface of the waste heat exchanger 44 is used to connect to the waste heat medium B generated by the nuclear power system; The organic working fluid loop 48 is provided with a working fluid / carbon dioxide heat exchanger 45 and a working fluid waste heat exchanger 44. The working fluid / carbon dioxide heat exchanger 45 is used to exchange heat with the liquid carbon dioxide output from the storage unit 30, and the hot side interface of the working fluid waste heat exchanger 44 is used to connect to the waste heat medium B generated by the nuclear power system.

[0036] It should be noted that the carbon dioxide capture unit 10 is the core component for directly capturing carbon dioxide from the air. It is equipped with at least two parallel absorption towers. The purpose is to ensure the continuity of the carbon dioxide capture process through the alternating operation of the absorption towers. When one absorption tower is in adsorption mode, the other absorption tower can simultaneously be in desorption mode, avoiding interruptions in capture caused by switching modes of a single tower. The "at least two absorption towers" can specifically be set to two, three, or more. The specific number can be flexibly set according to the excess energy scale of the nuclear power system and the carbon dioxide capture requirement. For example, in scenarios with high capture requirements, three absorption towers can be set to further improve capture efficiency and system redundancy. An adsorbent is installed inside the absorption tower for selectively adsorbing carbon dioxide from the air. The adsorbent can be a solid amine adsorbent or a porous metal-organic framework adsorbent. Solid amine adsorbents have the characteristics of large adsorption capacity and high selectivity, while porous metal-organic framework adsorbents have the advantages of fast adsorption rate and good cycle stability, both of which can meet the requirements for effective carbon dioxide capture. The cooling medium A interface and heating medium interface of the absorption tower are key structures for switching between absorption and desorption modes. The cooling medium A interface is used to connect the cooling medium A provided by the nuclear power system when the absorption tower is in absorption mode. Cooling medium A removes the heat generated during adsorption, maintaining the adsorbent at a lower temperature and thus improving carbon dioxide adsorption efficiency. The heating medium interface is used to connect the waste heat medium B generated by the nuclear power system when the absorption tower is in desorption mode. This waste heat heats the adsorbent, causing the adsorbed carbon dioxide to desorb and be released. Cooling medium A can be cooling water from the nuclear power system or seawater directly usable by a floating nuclear power platform, both of which can provide a stable cold source for the absorption tower. Waste heat medium B can be condensate from the secondary loop of the nuclear power system or exhaust steam from the nuclear power plant. Both are low-grade waste heat generated during the operation of the nuclear power system and can be fully utilized to reduce the additional energy consumption of this device.

[0037] The compression-liquefaction unit 20 is connected to the carbon dioxide capture unit 10. Its core function is to receive carbon dioxide desorbed from the absorption tower and convert gaseous carbon dioxide into liquid carbon dioxide through compression and liquefaction for subsequent storage. The compression-liquefaction unit 20 can adopt a multi-stage compression and cooling structure, for example, including a primary compressor 21 and a secondary compressor 21. The desorbed carbon dioxide is first compressed by the primary compressor 21 and then cooled in a cooler to lower its temperature. It is then compressed to a supercritical state by the secondary compressor 21, followed by further cooling and liquefaction through a throttling structure. Alternatively, a single-stage high-pressure compressor 21 combined with an effective cooler can be used, depending on the carbon dioxide processing capacity and liquefaction efficiency requirements. Through compression-liquefaction, the volume of carbon dioxide can be significantly reduced, increasing energy storage density and adapting to the space constraints of small nuclear power plants and offshore floating nuclear power platforms.

[0038] The storage unit 30 is used to store liquefied carbon dioxide. Its function is to temporarily store the carbon dioxide captured and liquefied during periods of low load, forming an energy reserve, which is then released and utilized during periods of high load. The structural form of the storage unit 30 can be flexibly selected according to the installation space of the nuclear power system. Horizontal or vertical storage units can be used. Horizontal storage units 30 are suitable for scenarios with limited height, while vertical storage units 30 are suitable for scenarios with limited floor space. The material of the storage unit 30 must meet the requirements of low temperature resistance and carbon dioxide corrosion resistance, such as stainless steel or nickel-based alloys, to ensure safety and airtightness during long-term storage. Since carbon dioxide has a low critical temperature, it can be stored in liquid form at room temperature through low-pressure storage, eliminating the need for complex low-temperature insulation measures, thus reducing the design difficulty and manufacturing cost of the storage unit 30.

[0039] The working fluid inlet of the carbon dioxide expander 41 is connected to the storage unit 30 via a pipeline. Its function is to receive liquid carbon dioxide output from the storage unit 30. The liquid carbon dioxide is vaporized before entering the carbon dioxide expander 41. The vaporized gaseous carbon dioxide expands and does work inside the expander, converting the internal energy of the carbon dioxide into mechanical energy. The pipeline connecting the storage unit 30 and the carbon dioxide expander 41 can be equipped with control components according to actual needs. For example, a shut-off valve is used to control the opening and closing of the pipeline, and a check valve is used to prevent backflow of carbon dioxide, ensuring that the carbon dioxide enters the carbon dioxide expander 41 in a predetermined direction. The carbon dioxide expander 41 can be a radial flow expander or an axial flow expander. The radial flow expander is suitable for small and medium power scenarios, while the axial flow expander is suitable for high power scenarios. Both can achieve effective conversion of carbon dioxide expansion energy.

[0040] The organic working fluid circuit 48 includes an organic working fluid expander 42. The core function of this circuit is to utilize the cold energy of the liquid carbon dioxide output from the storage unit 30 to further recover energy through the phase change and expansion process of the organic working fluid, thereby improving the overall energy utilization efficiency of the device. The organic working fluid flowing in the organic working fluid circuit 48 can be R245fa or R218. R245fa is environmentally friendly and has good stability, while R218 has a lower freezing point and is suitable for operation in low-temperature environments. The organic working fluid expander 42 is used to convert the internal energy of the organic working fluid into mechanical energy. A scroll expander or a screw expander can be used to ensure the effectiveness of the organic working fluid expansion process.

[0041] The generator 43 is connected to the carbon dioxide expander 41 and the organic working fluid expander 42. Its function is to convert the mechanical energy output from the two expanders into electrical energy, which can be directly supplied to the power grid of the nuclear power system to alleviate the power supply gap during peak load periods. The generator 43 can be connected to the expanders via direct coupling, where the input shaft of the generator 43 is connected to the output shafts of the carbon dioxide expander 41 and the organic working fluid expander 42 respectively through couplings to ensure direct transmission of mechanical energy; alternatively, a gearbox can be used to adjust the output speed of the two expanders to a speed compatible with the generator 43, thereby improving power generation stability. The specific connection method can be determined based on the output characteristics of the expanders and the operating parameters of the generator 43.

[0042] The waste heat exchanger 44, installed on the pipeline connecting the carbon dioxide expander 41 and the storage unit 30, has the core function of using the waste heat medium B generated by the nuclear power system to heat the liquid carbon dioxide output from the storage unit 30, causing the liquid carbon dioxide to vaporize and increase in temperature. This provides a suitable gaseous working fluid for the subsequent work in the carbon dioxide expander 41, ensuring the working efficiency of the carbon dioxide expander 41. The waste heat medium B connected to the hot side interface of the waste heat exchanger 44 is of the same type as the waste heat medium B connected to the heating medium interface of the absorption tower. It can be selected from the condensate of the secondary loop of the nuclear power system or the exhaust steam of the nuclear power plant, which can make full use of the waste heat resources of the nuclear power system and avoid energy waste. The waste heat exchanger 44 can be a shell-and-tube heat exchanger or a plate heat exchanger. Shell-and-tube heat exchangers are characterized by their robust structure and high pressure resistance, while plate heat exchangers have the advantages of high heat exchange efficiency and small size, both of which can meet the waste heat exchange requirements.

[0043] The working fluid / carbon dioxide heat exchanger 45 and the working fluid waste heat heat exchanger 44 installed on the organic working fluid loop 48 are key components for realizing the recovery and utilization of organic working fluid energy. The working fluid / carbon dioxide heat exchanger 45 is used to exchange heat between the organic working fluid and the liquid carbon dioxide output from the storage unit 30. The low temperature characteristics of the liquid carbon dioxide can cool the organic working fluid, causing it to condense into a liquid state, preparing for the subsequent compression and heating process. This process also realizes the recovery and utilization of the cold energy of the liquid carbon dioxide. The hot side interface of the working fluid waste heat heat exchanger 44 is connected to the waste heat medium B generated by the nuclear power system. Secondary loop condensate or exhaust steam can be selected to heat the liquid organic working fluid after being compressed by the working fluid pump 47, causing the organic working fluid to vaporize and rise to a superheated state, thereby improving the work capacity of the organic working fluid after entering the organic working fluid expander 42. The working fluid / carbon dioxide heat exchanger 45 can be a shell-and-tube heat exchanger or a plate-and-shell heat exchanger. The shell-and-tube heat exchanger is suitable for small flow rate scenarios, while the plate-and-shell heat exchanger is suitable for large flow rate scenarios. The structure of the working fluid waste heat heat exchanger 44 can be consistent with that of the waste heat heat exchanger 44 to ensure compatibility with the waste heat medium B of the nuclear power system.

[0044] This device specifically addresses the core technical challenges of small-scale nuclear power plants and offshore floating nuclear power platforms: First, it overcomes the limitations of existing pumped-storage technology, which has stringent geographical requirements, and compressed-air energy storage technology, which has high space requirements, making them unsuitable for small-scale nuclear power plant sites and offshore platforms. This device uses carbon dioxide from the air as the energy storage medium, requiring no special terrain or large-scale gas storage facilities, and exhibits strong environmental adaptability. Second, it addresses the issues of poor safety and short cycle life of electrochemical energy storage technology in megawatt-level applications, making it difficult to match the long design life of nuclear power plants. The core of this device is a mechanical structure, eliminating the risk of combustion and performance degradation, and its service life can be synchronized with the nuclear power system. Third, it solves the problems of weak load tracking capability of nuclear power systems, waste of excess energy during off-peak periods, and lack of effective peak-shaving means during isolated operation. This device can fully absorb excess energy and replenish energy in a timely manner during peak load periods, ensuring the stable operation of the nuclear power system. Accordingly, this device works in conjunction with a nuclear power system, utilizing the system's own cooling medium A and waste heat medium B, eliminating the need for additional energy consumption and achieving high economic efficiency; at least two parallel absorption towers ensure continuous carbon dioxide capture, resulting in strong system operational stability; the liquid carbon dioxide storage has high energy density and small volume, making it suitable for small nuclear power plants and offshore platforms with limited space; the dual expanders work together to generate electricity, resulting in high energy utilization efficiency and significant peak shaving and valley filling effects; the mechanical structure has high safety and long service life, meeting the long-term operational requirements of the nuclear power system.

[0045] In this case, during periods of low load, the device operates in a capture and storage state, utilizing surplus energy from the nuclear power unit to capture carbon dioxide for energy storage. The adsorbent in each absorption tower is a solid amine adsorbent. The first absorption tower 11 and the second absorption tower 12 are connected in parallel for the direct capture of carbon dioxide from the air. A controllable valve group allows the first absorption tower 11 and the second absorption tower 12 to operate alternately, with one performing adsorption and the other performing desorption, thus ensuring continuous system operation.

[0046] When the absorber tower performs carbon dioxide adsorption, it connects to cooling medium A (condensate from the nuclear power system's condenser or seawater) provided by the nuclear power system through its cooling medium A interface, while simultaneously interrupting the connection to waste heat medium B (condensate from the nuclear power system's secondary loop) through the heating medium interface. This ensures that the adsorbent is in a sufficiently cooled state, which is conducive to carbon dioxide absorption. When the absorber tower performs carbon dioxide desorption, it connects to condensate from the nuclear power system's secondary loop through its heating medium interface, using the waste heat of the condensate to heat the adsorbent, causing the adsorbent to release carbon dioxide.

[0047] The desorbed carbon dioxide enters the first cooler 22 directly. After being cooled by cooling water, it enters the compressor 21 for compression. The compressed carbon dioxide enters the second cooler 23 and is cooled to a near-liquefied state. Then, it is liquefied by the throttle valve and finally stored in the storage unit 30.

[0048] During peak load periods, the device is in a state of releasing energy supply, using two energy supply methods—direct expansion of carbon dioxide and utilization of cold energy from organic working fluid—to generate electricity.

[0049] In terms of direct carbon dioxide expansion, the liquefied carbon dioxide in the storage unit 30 is transported through pipeline to the hot side flow channel of the working fluid / carbon dioxide heat exchanger 45, and then enters the first waste heat vaporizer; the hot side interface of the first waste heat vaporizer is connected to the exhaust steam of the second loop of the nuclear power system, and the waste heat of the exhaust steam is used to heat the liquefied carbon dioxide, causing the liquefied carbon dioxide to vaporize. The vaporized carbon dioxide enters the carbon dioxide expander 41, driving the carbon dioxide expander 41 to do work.

[0050] In terms of utilizing the cold energy of the organic working fluid, the organic working fluid (R245fa, R218, or R115) in the organic working fluid loop 48 enters the cold side flow channel of the working fluid / carbon dioxide heat exchanger 45, where it exchanges heat with the low-temperature liquefied carbon dioxide in the hot side flow channel. After being cooled, the organic working fluid enters the working fluid pump 47, where it is compressed and pressurized. The pressurized organic working fluid then enters the second waste heat vaporizer, whose hot side interface is connected to the condensate of the second loop of the nuclear power system. The waste heat of the condensate is used to heat the organic working fluid, causing it to vaporize. The vaporized organic working fluid then enters the waste heat superheater 46, whose hot side interface is connected to the exhaust steam or condensate of the second loop of the nuclear power system, further heating the organic working fluid to a superheated state. The superheated organic working fluid then enters the organic working fluid expander 42, driving the expander 42 to perform work.

[0051] The carbon dioxide expander 41 and the organic working fluid expander 42 operate synchronously through a gearbox or coupling, jointly driving the generator 43 to generate electrical energy, which is then output to the nuclear power system to make up for the power supply gap of the nuclear power unit and realize the function of peak shaving and valley filling.

[0052] As an optional embodiment of this case, the cooling medium A interface of the absorption tower is used to connect to cooling water, and the heating medium interface is used to connect to the condensate of the secondary loop of the nuclear power system. The cooling water includes condensate of the nuclear power system, seawater, or other cooling water.

[0053] It should be noted that this design closely integrates the operational characteristics of small-scale nuclear power plants (land-based) and floating nuclear power platforms (offshore). Land-based small-scale nuclear power plants can directly utilize the low-temperature condensate generated by their own condensers as a cold source, eliminating the need for an external cold source. The condensate in a nuclear power system is formed after steam is cooled in the condenser. Its main function is as cooling medium A, used to cool the absorbent (such as a solid amine adsorbent) during carbon dioxide adsorption in the absorption tower, thereby promoting carbon dioxide absorption. Floating nuclear power platforms can utilize readily available seawater as a cold source, eliminating the need for additional storage facilities. The heating medium interface is used to connect to the condensate in the secondary loop of the nuclear power system. The condensate in the secondary loop originates from the secondary loop system of the nuclear power plant and is water formed by the condensation of turbine exhaust in the condenser, serving as a waste heat carrier in the nuclear power system cycle. Its main function is to act as a heating medium to heat the absorbent during the desorption of carbon dioxide in the absorption tower, thereby causing the absorbent to release carbon dioxide. This avoids the need for additional electrical energy or fuel to provide heat for desorption. This design solves the technical problem that existing energy storage devices rely heavily on external facilities for their cold and heat sources, resulting in high costs and strong dependence when adapting to small nuclear power plants and offshore platforms. Ultimately, it achieves the elimination of the need for external cold and heat sources, reduces operating costs, and is suitable for both onshore and offshore scenarios, ensuring stable adsorption and desorption operations in the absorption tower and improving carbon dioxide capture efficiency.

[0054] As an optional embodiment of this case, at least two of the absorption towers are equipped with controllable valve groups on their piping systems. The controllable valve groups are configured to allow one absorption tower to perform an adsorption operation while the other absorption tower performs a desorption operation, so as to achieve continuous capture of carbon dioxide.

[0055] It should be noted that by precisely controlling the on / off state of the air inlet, air outlet, and carbon dioxide outlet of each absorption tower, one absorption tower can perform adsorption operations (connecting cooling medium A, introducing air, and blocking carbon dioxide output) while another performs desorption operations (connecting heating medium, blocking air, and opening carbon dioxide output). This ensures continuous and uninterrupted carbon dioxide capture. This design solves the technical problem that when the capture process is interrupted due to operating condition switching in a single tower or without controllable valve groups, the excess energy in small nuclear power plants during off-peak periods cannot be continuously absorbed, and the liquid carbon dioxide reserves in storage unit 30 are insufficient. Ultimately, it achieves continuous capture to fully absorb excess energy and avoid energy waste, while ensuring sufficient liquid carbon dioxide is available for release during peak load periods, thus improving the reliability of peak shaving and valley filling.

[0056] As an optional embodiment of this case, the compression liquefaction unit 20 includes a compressor 21, and a first cooler 22 and a second cooler 23 disposed before and after the compressor 21. The first cooler 22 is used to cool the desorbed carbon dioxide, and the second cooler 23 is used to cool the compressed carbon dioxide to a near-liquefied state.

[0057] It should be noted that the compression liquefaction unit 20 includes a compressor 21 and two-stage coolers. The first cooler 22 is located before the compressor 21 and is used to cool the carbon dioxide desorbed from the absorption tower and carrying waste heat, thereby reducing the compression load and energy consumption of the compressor 21. The second cooler 23 is located after the compressor 21 and is used to cool the high-temperature carbon dioxide compressed to a supercritical state to a near-liquefied state, thereby reducing the cooling energy consumption of subsequent throttling liquefaction. This structural design solves the technical problems of high energy consumption and low liquefaction efficiency of existing single-stage compression or single-stage cooling methods, which are not suitable for the economic requirements of small nuclear power plants and the space and energy constraints of offshore platforms. Ultimately, it reduces the energy consumption of the compression liquefaction process, improves energy storage efficiency, and the compact structure adapts to space constraints, enabling rapid absorption of excess energy from the nuclear power system.

[0058] As an optional embodiment of this case, the working fluid / carbon dioxide heat exchanger 45 in the organic working fluid circuit 48 is located downstream of the outlet of the storage unit 30, with its cold side flow channel connected to the organic working fluid circuit 48 and its hot side flow channel connected to the pipeline before the carbon dioxide expander 41.

[0059] It should be noted that this layout allows the low-temperature liquid carbon dioxide (carrying cold energy) output by the storage unit 30 to exchange heat with the high-temperature gaseous organic working fluid on the hot side and the cold side. This utilizes the cold energy to condense the organic working fluid into liquid (without the need for an additional cold source) and also allows the liquid carbon dioxide to be initially heated (laying the foundation for subsequent vaporization). This design solves the technical problems of waste of carbon dioxide cold energy, the need for an additional cold source for the condensation of organic working fluid, and the low vaporization efficiency of liquid carbon dioxide in existing devices. Ultimately, it achieves bidirectional utilization of cold energy and condensation needs to reduce energy consumption, improve the vaporization efficiency of liquid carbon dioxide, and thus improve the overall energy utilization efficiency of the device.

[0060] As an optional embodiment of this case, the waste heat exchanger 44 on the pipeline is a first waste heat vaporizer, and its hot side interface is configured to connect to the exhaust steam of the second loop of the nuclear power system; the working fluid waste heat exchanger 44 on the organic working fluid loop 48 is a second waste heat vaporizer, and its hot side interface is configured to connect to the condensate of the second loop of the nuclear power system.

[0061] It should be noted that a waste heat vaporizer is a device that can collect and utilize waste heat and transfer heat to a specific medium to vaporize it. The waste heat exchanger 44 on the pipeline is the first waste heat vaporizer, whose hot-side interface is connected to the high-temperature exhaust steam of the secondary loop of the nuclear power system. It uses the waste heat of the exhaust steam to rapidly vaporize liquid carbon dioxide into a gaseous state. The working fluid waste heat exchanger 44 of the organic working fluid loop 48 is the second waste heat vaporizer, whose hot-side interface is connected to the medium-low temperature condensate of the secondary loop. It uses the waste heat of the condensate to vaporize the compressed liquid organic working fluid into a gaseous state. This cascade design for utilizing the waste heat of the nuclear power system solves the technical problems of existing vaporization processes that rely on additional energy, waste heat, and large device size. Ultimately, it achieves full recovery and utilization of waste heat to reduce operating costs, eliminates the need for additional vaporization heat sources to simplify the device structure, adapts to the space constraints of small nuclear power plants and offshore platforms, and ensures a stable and effective vaporization process.

[0062] As an optional embodiment of this case, a waste heat superheater 46 is also provided downstream of the second waste heat vaporizer, and its hot side interface is configured to connect to the exhaust steam or condensate of the second loop of the nuclear power system for heating the organic working fluid to a superheated state.

[0063] It should be noted that the hot-side interface of the waste heat superheater 46 is connected to the exhaust steam or condensate of the secondary loop to heat the saturated steam organic working fluid output from the second waste heat vaporizer to a superheated state. This prevents the organic working fluid from condensing into a liquid state due to expansion and cooling after entering the expander (which would result in low working efficiency and liquid slugging damage to the equipment). This design solves the technical problems of low efficiency and high risk of equipment damage when the organic working fluid enters the expander in a saturated steam state. Ultimately, it improves the working efficiency of the organic working fluid expander 42 to increase power output, eliminates the risk of liquid slugging to extend equipment life, and ensures long-term stable operation of the device.

[0064] As an optional embodiment of this case, the carbon dioxide expander 41 and the organic working fluid expander 42 are connected to the same generator 43 through a gearbox or coupling.

[0065] It should be noted that the gearbox is suitable for scenarios where the output speeds of the two expanders are different (the speed can be adjusted to match the speed of the generator 43), while the coupling is suitable for scenarios where the speeds are similar (reducing transmission energy consumption). This connection method solves the technical problems of redundant equipment and large footprint caused by setting separate generators 43 for the two expanders, or the problem of fluctuating generator speed and poor power quality caused by simple connection. Ultimately, it reduces the footprint of the device to adapt to space constraints, ensures stable generator speed to output high-quality power, and reduces transmission energy consumption and improves energy utilization efficiency through the adaptive connection method.

[0066] As an optional embodiment of this case, a fan 19 connected to the air inlet of the absorption tower is also included.

[0067] It should be noted that the fan 19 connected to the air inlet of the absorption tower can actively transport external air to the absorption tower at a stable flow rate and volume, ensuring that the carbon dioxide in the air is in full contact with the adsorbent in the absorption tower. This avoids the problem of unstable air flow and the adsorbent not being able to fully play its role during natural ventilation. This design solves the technical problem that natural ventilation leads to low carbon dioxide capture efficiency and slow speed, making it impossible to absorb excess energy during the off-peak period of the nuclear power system. Ultimately, it improves capture efficiency and speed to fully absorb excess energy, ensures uniform adsorption of the adsorbent to extend its service life, and the fan 19 has a simple structure, low energy consumption, and is suitable for space and economic requirements.

[0068] As an optional embodiment of this case, the adsorbent is one or more of the following: solid amine adsorbent, metal-organic framework, non-amine adsorbent resin, or lithium-zeolite.

[0069] It should be noted that the solid amine adsorbent in this case achieves effective capture through the reversible chemical reaction between amines and carbon dioxide. Its alternative materials must meet the core requirements of selective adsorption of low-concentration carbon dioxide, room temperature / low temperature adsorption, waste heat-driven desorption, long life and high stability. For example, metal-organic frameworks (MOFs) such as Mg-MOF-74 and CALF-20; non-amine adsorption resins such as oxygen / fluorine group-modified resins or anion-functionalized resins all have high adsorption capacity for carbon dioxide, require medium to low temperatures for desorption, have good cycle stability, and their adsorption performance can be controlled by temperature and pressure to achieve adsorption and desorption cycles, making them suitable for industrial-grade gas capture and separation applications. The adsorbents in conventional absorption towers (such as liquid amines and activated carbon commonly used in industrial waste gas treatment) are typically designed for high-concentration carbon dioxide sources (such as power plant flue gas and chemical tail gas, where the carbon dioxide concentration is often above 5%). Their adsorption performance depends on the mass transfer efficiency under high-concentration conditions. They have weak adsorption capacity and poor selectivity for low-concentration carbon dioxide in the air (approximately 0.04%), and the adsorption rate is extremely low at low concentrations, making it difficult to meet the requirements for effective capture. In addition, the regeneration process of conventional adsorbents (such as thermal desorption) often consumes a large amount of energy. If used to treat low-concentration gas sources such as air, it would lead to a serious imbalance between energy consumption and benefits, making it impractical. In contrast, the adsorbent in this case (such as solid amine adsorbent) is specifically designed to have a high selective adsorption capacity for low-concentration carbon dioxide. Even when the carbon dioxide concentration in the air is extremely low, it can still effectively capture carbon dioxide molecules through chemical adsorption or physical adsorption. Meanwhile, by combining the alternating operation mechanism of the absorption tower (one adsorption, one desorption) and the waste heat and cold source support of the nuclear power system (cooling water is used to maintain low temperature during adsorption to enhance adsorption efficiency, and waste heat from the secondary loop condensate is used to heat and regenerate effectively during desorption), this type of adsorbent can complete the adsorption and desorption cycle under low energy consumption conditions. It is specifically adapted to the scenario of directly capturing carbon dioxide from the air, solving the technical pain point that ordinary adsorbents cannot effectively capture carbon dioxide from low-concentration gas sources, and providing a feasible medium source solution for the energy storage needs of small nuclear power plants or offshore platforms.

[0070] As an optional embodiment of this case, the organic working fluid in the organic working fluid circuit 48 is R245fa, R218, or R115. It should be noted that the organic working fluid in the organic working fluid circuit 48 is R245fa, R218, or R115, wherein R245fa is environmentally friendly and stable and suitable for land-based scenarios, R218 is resistant to low temperatures and suitable for marine scenarios, and R115 has thermodynamic properties suitable for cold energy utilization.

[0071] As an optional embodiment of this case, the organic working fluid loop 48 further includes a working fluid pump 47, which is disposed between the working fluid / carbon dioxide heat exchanger 45 and the working fluid waste heat heat exchanger 44.

[0072] It should be noted that the working fluid pump 47, located between the working fluid / carbon dioxide heat exchanger 45 and the working fluid waste heat exchanger 44 in the organic working fluid loop 48, can pressurize the cooled, liquid organic working fluid to ensure sufficient pressure and flow rate for stable delivery to the working fluid waste heat exchanger 44. At the same time, it improves the heat absorption efficiency of the organic working fluid in the heat exchanger to ensure full vaporization. This design solves the technical problem that the natural flow of liquid organic working fluid cannot overcome loop resistance and has low vaporization efficiency, resulting in insufficient power supply to the organic working fluid expander 42. Ultimately, it ensures stable circulation of the organic working fluid loop 48 to avoid power interruption, improves the vaporization efficiency of the organic working fluid to increase the work output of the expander, and thus better supplements the power supply gap of the nuclear power system.

[0073] The present invention also provides a method for carbon dioxide energy storage in a nuclear power system, comprising the following steps: Capture steps: Carbon dioxide is directly and alternately adsorbed and desorbed from ambient air using at least two absorption towers connected in parallel; wherein, cooling medium A provided by the nuclear power system is introduced into the absorption tower performing the adsorption operation; and waste heat medium B generated by the nuclear power system is introduced into the absorption tower performing the desorption operation. Compression liquefaction step: The carbon dioxide desorbed from the absorption tower is compressed and cooled to liquefy it; Storage steps: Store the liquefied carbon dioxide in storage unit 30; Energy release and power generation steps: During peak energy demand periods, liquid carbon dioxide from the storage unit 30 is first transported to a working fluid / carbon dioxide heat exchanger 45 to exchange heat with an organic working fluid, and then transported to a waste heat heat exchanger 44, where it is heated and vaporized using the waste heat medium B generated by the nuclear power system; the vaporized carbon dioxide is then introduced into a carbon dioxide expander 41 to expand and do work. Furthermore, the organic working fluid is cooled by liquid carbon dioxide as it flows through the working fluid / carbon dioxide heat exchanger 45, and then the cooled organic working fluid is compressed, heated and vaporized by the waste heat medium B generated by the nuclear power system and superheated, and then introduced into the organic working fluid expander 42 to expand and do work. The generator 43 generates electricity, which is jointly driven by the carbon dioxide expander 41 and the organic working fluid expander 42.

[0074] As an optional embodiment of this case, the absorption tower includes a first absorption tower 11 and a second absorption tower 12. Each absorption tower is equipped with a controllable valve group at its air inlet, air outlet, and carbon dioxide outlet. The controllable valve group includes a first absorption tower inlet valve 13, a first absorption tower air exhaust valve 14, a first absorption tower outlet valve 15, a second absorption tower inlet valve 16, a second absorption tower outlet valve 17, and a second absorption tower air exhaust valve 18. When one of the absorption towers performs adsorption operation, its air inlet valve and air outlet valve are open, the carbon dioxide outlet valve is closed, and cooling medium A is introduced into the cooling medium A interface. When the other absorption tower performs desorption operation, its air inlet valve and air outlet valve are closed, the carbon dioxide outlet valve is open, and waste heat medium B is introduced into the heating medium interface. Therefore, the controllable valve group is configured to allow one absorption tower to perform adsorption operation while the other absorption tower performs desorption operation, so as to achieve continuous capture of carbon dioxide. This design solves the technical problems of inaccurate control of existing valve groups leading to cross-flow and leakage of media, reduced carbon dioxide purity, and damage to the compression liquefaction unit 20. Ultimately, it achieves precise control of media flow to avoid cross-flow and leakage, ensures carbon dioxide purity to guarantee the effective operation of the compression liquefaction unit 20, and further ensures the continuity of alternating operation of the absorption tower, thereby improving the overall reliability of the device.

[0075] The working process of the device in this case: In the capture and storage state, the first absorption tower 11 performs adsorption operation and the second absorption tower 12 performs desorption operation. The operating conditions are controlled by a controllable valve group: the inlet valve 13 and the air exhaust valve 14 of the first absorption tower are opened, the inlet valve 16 and the air exhaust valve 18 of the second absorption tower are closed, the outlet valve 15 of the first absorption tower is closed, and the outlet valve 17 of the second absorption tower is opened.

[0076] At this time, the outside air is driven by the fan 19 and enters the first absorption tower 11 through the inlet valve 13 of the first absorption tower. The first absorption tower 11 is connected to the condensate water or seawater of the nuclear power system through the cooling medium A interface to cool the solid amine adsorbent in the tower. The carbon dioxide in the air is fully absorbed by the solid amine adsorbent, and the remaining gas after absorbing carbon dioxide is discharged back to the atmosphere through the air exhaust valve 14 of the first absorption tower.

[0077] Simultaneously, the second absorption tower 12 is connected to the condensate of the second loop of the nuclear power system through a heating medium interface. The waste heat of the condensate is used to heat the solid amine adsorbent in the tower, causing the adsorbed carbon dioxide to desorb and be released. The desorbed carbon dioxide is discharged through the outlet valve 17 of the second absorption tower and enters the first cooler 22. After being cooled by the first cooler 22, it enters the compressor 21 and is compressed to a supercritical state. The supercritical carbon dioxide enters the second cooler 23 and is further cooled to a near-liquefied state. The cooled carbon dioxide is throttled by the throttling valve 24 and converted into liquid carbon dioxide, which is finally stored in the storage unit 30, completing the carbon dioxide capture and storage process.

[0078] After the first absorption tower 11 is saturated with adsorption and the second absorption tower 12 has completed desorption, the operating conditions are switched by a controllable valve group: the inlet valve 13 and the air exhaust valve 14 of the first absorption tower are closed, the inlet valve 16 and the air exhaust valve 18 of the second absorption tower are opened, the outlet valve 15 of the first absorption tower is opened, and the outlet valve 17 of the second absorption tower is closed, so that the first absorption tower 11 performs desorption operation and the second absorption tower 12 performs adsorption operation, ensuring continuous carbon dioxide capture.

[0079] In the energy release state, the gas supply valve 31 of the storage unit 30 is opened, and the liquefied carbon dioxide in the storage unit 30 enters the hot side flow channel of the working fluid / carbon dioxide heat exchanger 45 through the gas supply valve 31, and exchanges heat with the organic working fluid in the cold side flow channel; the liquefied carbon dioxide after heat exchange enters the first waste heat vaporizer, which is connected to the exhaust steam of the second loop of the nuclear power system, and uses the waste heat of the exhaust steam to heat the liquefied carbon dioxide to a vaporized state. The vaporized carbon dioxide enters the carbon dioxide expander 41, which drives the carbon dioxide expander 41 to do work.

[0080] The organic working fluid (R245fa, R218, or R115) in the organic working fluid loop 48 enters the cold side flow channel of the working fluid / carbon dioxide heat exchanger 45. After being cooled by the low-temperature liquefied carbon dioxide in the hot side flow channel, it enters the working fluid pump 47. The working fluid pump 47 compresses and pressurizes the organic working fluid and delivers it to the second waste heat vaporizer. The second waste heat vaporizer is connected to the condensate of the second loop of the nuclear power system, and uses the waste heat of the condensate to heat the organic working fluid to a vaporized state. The vaporized organic working fluid enters the waste heat superheater 46. The waste heat superheater 46 is connected to the exhaust steam or condensate of the second loop of the nuclear power system to heat the organic working fluid to a superheated state. The superheated organic working fluid enters the organic working fluid expander 42, which drives the organic working fluid expander 42 to do work.

[0081] The carbon dioxide expander 41 and the organic working fluid expander 42 are connected by a gearbox or coupling, and synchronously output mechanical energy to drive the generator 43 to generate electrical energy. The electrical energy is directly output to the nuclear power system to supplement the energy supply gap of the nuclear power system and realize peak shaving and valley filling.

[0082] This invention offers the following technical advantages: First, it achieves effective storage and precise peak shaving of excess nuclear energy. By directly capturing carbon dioxide from the air as the energy storage medium, surplus electrical energy during off-peak periods is converted into the potential energy of liquid carbon dioxide for storage. During peak periods, the stored energy is promptly converted into electrical output through coordinated power generation using dual expanders, effectively smoothing load fluctuations and significantly improving the overall utilization efficiency of nuclear energy. Second, it overcomes the stringent limitations of energy storage systems on application scenarios. Utilizing room-temperature liquid-atmospheric pressure carbon dioxide storage, it achieves high energy density, eliminates the need for large underground caverns or high-pressure containers, and features a compact structure and small footprint, perfectly adapting to the space-constrained installation conditions of small onshore nuclear power plants and offshore floating platforms, giving the energy storage system excellent environmental adaptability. Third, it fundamentally improves the system's safety and reliability. The entire energy storage and release process is based on thermodynamic cycles and mechanical transmission, eliminating the risk of combustion and explosion, and completely eradicating the thermal runaway hazards of electrochemical energy storage routes. The system's core is a mechanical component, minimizing performance degradation issues. Its design life matches that of the nuclear power plant, meeting the extremely high safety and reliability requirements of the nuclear energy field. Fourth, it achieves closed-loop energy utilization and high system integration. It utilizes the condensate (or seawater) from the nuclear power system's own condenser as cooling medium A, and the low-grade waste heat from the secondary loop (condensate and exhaust steam) as a heat source for desorption and working fluid heating. This eliminates reliance on any external energy source, deeply integrating the energy storage system with the nuclear power system to form a self-consistent and effectively circulating organic whole. Fifth, it improves overall energy utilization efficiency. It employs a cascade expansion of carbon dioxide and organic working fluid to generate electricity, and utilizes the cold energy of liquid carbon dioxide to condense the organic working fluid. This achieves high utilization of waste heat and cold energy from the nuclear system, significantly improving the overall efficiency of the entire energy conversion process.

[0083] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

Claims

1. A carbon dioxide energy storage device for a nuclear power system, characterized in that, include: A carbon dioxide capture unit includes at least two absorption towers arranged in parallel, wherein the at least two absorption towers are used to alternately adsorb and desorb carbon dioxide directly from ambient air; each absorption tower is provided with a cooling medium interface and a heating medium interface, wherein the cooling medium interface is used to connect to a cooling medium, and the heating medium interface is used to connect to a waste heat medium generated by a nuclear power system. A compression-liquefaction unit, connected to the carbon dioxide capture unit, is used to compress and liquefy the desorbed carbon dioxide; Storage unit for storing liquefied carbon dioxide; An energy-generating unit is connected to the storage unit and is configured to use the cold energy of liquid carbon dioxide from the storage unit and the waste heat medium generated by the nuclear power system to drive a generator to generate electricity.

2. The carbon dioxide energy storage device for nuclear power systems according to claim 1, characterized in that, The energy release power generation unit includes: A carbon dioxide expander, the working fluid inlet of which is connected to the storage unit via a pipeline; Organic working fluid circuit, including organic working fluid expander; A generator is connected to the carbon dioxide expander and the organic working fluid expander; The pipeline is equipped with a waste heat exchanger, and the hot side interface of the waste heat exchanger is used to connect to the waste heat medium generated by the nuclear power system. The organic working fluid circuit is equipped with a working fluid / carbon dioxide heat exchanger and a working fluid waste heat heat exchanger. The working fluid / carbon dioxide heat exchanger is used to exchange heat with the liquid carbon dioxide output from the storage unit, and the hot side interface of the working fluid waste heat heat exchanger is used to connect to the waste heat medium generated by the nuclear power system.

3. The carbon dioxide energy storage device for a nuclear power system according to claim 1, characterized in that, The adsorbent is one or more of the following: solid amine adsorbent, metal-organic framework, non-amine adsorbent resin, or lithium-zeolite.

4. The carbon dioxide energy storage device for a nuclear power system according to claim 1, characterized in that, The cooling medium connected to the cooling medium interface of the absorption tower includes condensate water from the condenser of the nuclear power system or seawater, and the heating medium interface is used to connect condensate water or exhaust steam from the secondary loop of the nuclear power system.

5. The carbon dioxide energy storage device for a nuclear power system according to claim 1, characterized in that, The compression liquefaction unit includes a compressor, and a first cooler and a second cooler disposed before and after the compressor. The first cooler is used to cool the desorbed carbon dioxide, and the second cooler is used to cool the compressed carbon dioxide to a near-liquefied state.

6. The carbon dioxide energy storage device for a nuclear power system according to claim 2, characterized in that, The working fluid / carbon dioxide heat exchanger in the organic working fluid circuit is located downstream of the outlet of the storage unit. The cold side flow channel of the working fluid / carbon dioxide heat exchanger is connected to the organic working fluid circuit, and the hot side flow channel of the working fluid / carbon dioxide heat exchanger is connected to the pipeline before the carbon dioxide expander.

7. The carbon dioxide energy storage device for a nuclear power system according to claim 2, characterized in that, The waste heat exchanger on the pipeline is a first waste heat vaporizer, and its hot-side interface is configured to connect to the exhaust steam of the second loop of the nuclear power system; the working fluid waste heat exchanger on the organic working fluid loop is a second waste heat vaporizer, and its hot-side interface is configured to connect to the condensate of the second loop of the nuclear power system.

8. The carbon dioxide energy storage device for a nuclear power system according to claim 7, characterized in that, Downstream of the second waste heat vaporizer is a waste heat superheater, whose hot-side interface is configured to connect to the exhaust steam or condensate of the second loop of the nuclear power system, for heating the organic working fluid to a superheated state.

9. The carbon dioxide energy storage device for a nuclear power system according to claim 1, characterized in that, It also includes a fan connected to the air inlet of the absorption tower.

10. A method for carbon dioxide energy storage in a nuclear power system, characterized in that, Includes the following steps: Carbon dioxide is adsorbed and desorbed directly from ambient air by at least two absorption towers arranged in parallel; wherein a cooling medium provided by the nuclear power system is introduced into the absorption tower performing the adsorption operation; and a waste heat medium generated by the nuclear power system is introduced into the absorption tower performing the desorption operation. The carbon dioxide desorbed from the absorption tower is compressed and cooled to liquefy it; the liquefied carbon dioxide is then stored in a storage unit. During peak energy demand periods, liquid carbon dioxide from the storage unit is first transported to a working fluid / carbon dioxide heat exchanger to exchange heat with an organic working fluid, and then transported to a waste heat heat exchanger to heat and vaporize it using the waste heat medium generated by the nuclear power system; the vaporized carbon dioxide is then introduced into a carbon dioxide expander to expand and do work. Furthermore, the organic working fluid is cooled by liquid carbon dioxide as it flows through the working fluid / carbon dioxide heat exchanger, and then the cooled organic working fluid is compressed, heated and vaporized by the waste heat medium generated by the nuclear power system, and then introduced into the organic working fluid expander to expand and do work; the carbon dioxide expander and the organic working fluid expander together drive the generator to generate electricity.

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