Molten salt reactor integrated with power generation system and method for generating power

Abstract

This invention relates to an integrated molten salt reactor power generation system and its power generation method. The integrated molten salt reactor power generation system includes a molten salt reactor high-temperature heating module, a heat exchange module, and a mixed working fluid Brayton cycle power generation module. The mixed working fluid Brayton cycle power generation module consists of a turbine, a regenerator, a cooler, a compressor, and a generator. The turbine, compressor, and generator are coaxially connected, and each device is sequentially connected via pipelines according to operating conditions, forming a complete circulation path. The molten salt reactor high-temperature heating module is connected to the heat exchange module via molten salt pipelines, constructing a fuel salt circulation loop. The heat exchange module is then connected to the cold-side outlet of the regenerator and the inlet of the turbine via gas flow pipelines, forming an independent gas mixed working fluid circulation loop. The entire power generation module uses inert gas as the circulating working fluid, relying on a dual-loop isolation layout and Brayton cycle structure design to avoid the inherent shortcomings of traditional steam cycles. This invention achieves a comprehensive improvement in system efficiency, compactness, and safety.

Description

Technical Field

[0001] This invention relates to the field of nuclear power generation technology, and in particular to an integrated molten salt reactor power generation system and its power generation method. Background Technology

[0002] As one of the core reactor types of fourth-generation advanced nuclear energy systems, molten salt reactors, with their outstanding technological advantages such as high operating temperature, excellent inherent safety, wide fuel adaptability, and low nuclear waste generation, have shown broad application prospects in the fields of stable supply of clean baseload energy, optimized recycling of nuclear fuel resources, and industrial heat supply in multiple scenarios. They have become a key area for global advanced nuclear energy technology research and engineering transformation. The power generation system, as the core carrier of energy output from the molten salt reactor, directly determines the effectiveness of the technological advantages of molten salt reactors through its thermoelectric conversion efficiency, system integration, and operating condition adaptability. It is a key element restricting the commercialization of molten salt reactors.

[0003] Currently, among the publicly disclosed molten salt reactor technologies both domestically and internationally, the power generation system generally adopts the steam Rankine cycle technology. The core working principle of this technology is as follows: the heat released from nuclear fission in the reactor core is extracted through the molten salt working fluid, transferred to the feedwater system via intermediate heat exchange equipment, and generates high-temperature, high-pressure steam to drive the turbine rotor. This steam then drives the generator through a coupling, converting mechanical energy into electrical energy. Due to its high technological maturity, rich engineering application experience, and good compatibility with traditional thermal power and pressurized water reactor nuclear power steam power generation systems, the steam Rankine cycle became the mainstream technology choice in the early stages of molten salt reactor development.

[0004] However, with the in-depth development of molten salt reactor technology, the inherent incompatibility between the steam Rankine cycle and the high-temperature and atmospheric-pressure operating characteristics of molten salt reactors has gradually become apparent, becoming a core bottleneck restricting the efficient, safe, and compact development of molten salt reactors. This is specifically reflected in the following aspects: 1. The upper limit of thermoelectric conversion efficiency is limited. The theoretical efficiency of the steam Rankine cycle is strictly constrained by the critical thermodynamic parameters of water (critical temperature 374℃, critical pressure 22.1MPa). Even with supercritical parameter optimization design, its net thermal efficiency is still difficult to exceed 45%, which cannot fully tap the energy potential of the molten salt reactor's 600-800℃ high-temperature heat source. As a result, the core high-temperature technology advantage of the molten salt reactor has not been effectively transformed into a power generation efficiency advantage.

[0005] 2. Balancing system safety and economy is difficult. High-temperature, high-pressure steam and radioactive molten salt working fluid require multi-layer indirect heat exchange equipment for heat transfer, posing a safety hazard of cross-leakage between the two loops. At the same time, high-temperature, high-pressure steam has a significant corrosive and erosive effect on core components such as turbine blades and steam pipelines, requiring the use of special high-temperature and corrosion-resistant materials and complex operation and maintenance processes, which greatly increases the system's construction investment and total life-cycle operating costs.

[0006] 3. Low system integration and poor environmental adaptability. Steam Rankine cycle requires large auxiliary equipment such as condensers, deaerators, steam condensers, and water treatment systems, resulting in large power plant footprints, complex system processes, and long construction periods. In addition, the steam condensation process consumes a large amount of cooling water, making it difficult to adapt to the construction needs of power plants in arid inland areas, islands, or remote areas, which seriously limits the expansion of molten salt reactor application scenarios.

[0007] 4. Lagging dynamic response characteristics. The start-up, shutdown, and load regulation of the turbine-generator system have significant mechanical and thermal inertia delays, which cannot match the rapid and flexible peak-shaving operation characteristics of molten salt reactors, and also cannot meet the grid requirements for coordinated dispatch with fluctuating new energy power generation systems such as wind power and photovoltaics.

[0008] 5. Poor pressure adaptability. The molten salt main circuit of the molten salt reactor operates under near-atmospheric pressure conditions (normally 0.1-0.5 MPa, and no more than 1 MPa under special conditions), while the steam Rankine cycle needs to maintain a high-pressure operating state of 16-25 MPa. This pressure gradient of orders of magnitude not only significantly increases the structural design difficulty of the heat exchange equipment, requiring the adoption of special structural forms that can withstand high pressure differentials, but also further increases the risk of system medium leakage and increases the safety control load. Summary of the Invention

[0009] To address the aforementioned problems in the prior art, this invention proposes an integrated molten salt reactor power generation system and its power generation method, which can comprehensively improve system efficiency, compactness, and safety.

[0010] Specifically, the present invention proposes an integrated power generation system for molten salt reactors, including a high-temperature heating module for molten salt reactors, a heat exchange module, and a mixed working fluid Brayton cycle power generation module; The mixed working fluid Brayton cycle power generation module includes a gas turbine, a regenerator, a cooler, a compressor, and a generator. The gas turbine and the compressor are coaxially connected to the generator. The outlet of the gas turbine is connected to the hot side inlet of the regenerator. The hot side outlet of the regenerator is connected to the inlet of the cooler. The outlet of the cooler is connected to the inlet of the compressor. The outlet of the compressor is connected to the cold side inlet of the regenerator. The molten salt reactor high-temperature heating module is connected to the heat exchange module through a molten salt pipeline to form a fuel salt circulation loop; the heat exchange module is connected to the cold side outlet of the regenerator and the inlet of the gas turbine through gas flow pipelines to form a gas mixed working fluid circulation loop.

[0011] According to one embodiment of the present invention, the mixed working fluid Brayton cycle power generation module uses a helium-xenon mixed gas working fluid with a relative molecular mass of 35-45 g / mol.

[0012] According to one embodiment of the present invention, the fuel salt circulation loop operates under normal pressure conditions, the gas mixture circulation loop operates under high pressure conditions, and the corresponding operating pressure of the gas mixture circulation loop is ≤1.5 MPa.

[0013] According to one embodiment of the present invention, the heat exchange module includes a first heat exchanger and a second heat exchanger, the first heat exchanger and the second heat exchanger are connected by a cooling salt pipe to form a cooling salt circulation loop, and the fuel salt in the fuel salt circulation loop and the cooling salt in the cooling salt circulation loop exchange heat in the first heat exchanger.

[0014] According to one embodiment of the present invention, the second heat exchanger is a shell-and-tube heat exchange structure, including a shell and a plurality of heat exchange tubes arranged in parallel and spaced apart inside the shell. The outer walls of the plurality of heat exchange tubes are in direct contact with molten salt, and the inner walls of the plurality of heat exchange tubes are in contact with the inert gas mixture working fluid.

[0015] According to one embodiment of the present invention, the shell and the heat exchange tube are made of Hastelloy, and the inner wall of the heat exchange tube is coated with an anti-oxidation coating.

[0016] According to one embodiment of the present invention, the heat exchange module further includes a cooling salt circulation pump disposed on the cooling salt pipeline.

[0017] According to one embodiment of the present invention, the power generation system further includes a fuel salt circulation pump disposed on the molten salt pipeline.

[0018] According to one embodiment of the invention, the cooler is connected to an external final heat sink for heat dissipation.

[0019] The present invention also provides a power generation method applicable to the aforementioned molten salt reactor integrated power generation system, the power generation method comprising the following steps: The low-temperature, low-pressure inert gas mixture is compressed to a high-pressure state by the compressor. A high-pressure inert gas mixture enters the cold side channel of the regenerator and exchanges heat with the high-temperature inert gas mixture entering the regenerator from the turbine outlet for preheating. The preheated inert gas mixture enters the heat exchange module through the gas flow pipe, absorbs the heat transferred by the molten salt reactor high-temperature heating module, and generates a high-temperature and high-pressure inert gas mixture. A mixture of high-temperature and high-pressure inert gas working fluid enters the gas turbine through the gas flow pipe, expands and does work, driving the coaxially connected generator to generate electricity and the compressor to operate; The high-temperature inert gas mixture from the turbine outlet enters the hot-side channel of the regenerator, transferring waste heat to the high-pressure inert gas mixture on the cold side of the regenerator. The inert gas mixture, cooled by the regenerator, enters the cooler, where it is cooled to form a low-temperature, low-pressure inert gas mixture, which then returns to the compressor inlet via the cooler.

[0020] This invention provides an integrated power generation system and method for molten salt reactors. By adopting an integrated architecture of a high-temperature heating module, a heat exchange module, and a Brayton cycle power generation module, and setting a dual-loop isolation design for the fuel salt circulation loop and the gas-mixed working fluid circulation loop, the highly radioactive fuel salt can be confined to a local area of ​​the reactor core, avoiding cross-leakage between different working fluid media and improving system operational safety. The closed-loop Brayton cycle with coaxial connection of the turbine-compressor-generator can reduce transmission mechanical inertia and energy loss. The system has no phase change heat process, and the dynamic load response speed is fast. It can adapt to the rapid peak shaving and grid connection requirements of molten salt reactors and new energy sources. It solves the core problems of traditional molten salt reactors, such as limited upper limit of steam Rankine cycle efficiency, system complexity, dependence on cooling water, and poor pressure adaptability. It can achieve system compactness and modularity, eliminate the risk of high-pressure vessel rupture, get rid of dependence on cooling water, and greatly expand the application scenarios of molten salt reactors.

[0021] It should be understood that the above general description and the following detailed description of the present invention are exemplary and illustrative, and are intended to provide further explanation of the present invention. Attached Figure Description

[0022] The accompanying drawings are included to provide further explanation of the invention; they are incorporated into and constitute a part of this application. The drawings illustrate embodiments of the invention and, together with this specification, serve to explain the principles of the invention. In the drawings: Figure 1 A schematic diagram of the overall architecture of an integrated power generation system for a molten salt reactor according to an embodiment of the present invention is shown.

[0023] Figure 2 A schematic diagram of a hybrid working fluid Brayton cycle power generation module according to an embodiment of the present invention is shown.

[0024] Figure 3 A schematic diagram of the structure of a molten salt reactor high-temperature heating module and a heat exchange module according to an embodiment of the present invention is shown.

[0025] Figure 4 A schematic diagram of the structure of a second heat exchanger according to an embodiment of the present invention is shown.

[0026] Figure 5 A flowchart of a power generation method according to an embodiment of the present invention is shown.

[0027] The above figures include the following reference numerals: Molten salt reactor integrated power generation system 100 Molten salt reactor high-temperature heating module 110 Heat exchange module 120 First heat exchanger 121 Second heat exchanger 122 Casing 1221 Heat exchanger tube 1222 Molten salt inlet monitoring interface 1223 Molten salt outlet monitoring interface 1224 Mixed gas inlet monitoring interface 1225 Mixed gas outlet monitoring interface 1226 Cooling salt pipe 123 Cooling salt circulation pump 124 Mixed working fluid Brayton cycle power generation module 130 Gas Turbine 131 Regenerator 132 Cooler 133 Compressor 134 Generator 135 Molten salt pipeline 140 Gas flow pipe 150 160 fuel salt circulation pump Final heat sink 170 Detailed Implementation

[0028] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other.

[0029] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit this application or its application or use. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.

[0030] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0031] Unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps described in these embodiments do not limit the scope of this application. It should also be understood that, for ease of description, the dimensions of the various parts shown in the drawings are not drawn to actual scale. Techniques, methods, and devices known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and devices should be considered part of the specification. In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar reference numerals and letters in the following drawings denote similar items; therefore, once an item is defined in one drawing, it need not be further discussed in subsequent drawings.

[0032] In the description of this application, it should be understood that the orientation or positional relationship indicated by directional terms such as "front, back, up, down, left, right", "horizontal, vertical, horizontal" and "top, bottom" is usually based on the orientation or positional relationship shown in the accompanying drawings, and is only for the convenience of describing this application and simplifying the description. Unless otherwise stated, these directional terms do not indicate or imply that the device or element referred to must have a specific orientation or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on the scope of protection of this application; the directional terms "inner" and "outer" refer to the inner and outer contours relative to the outline of each component itself.

[0033] Furthermore, it should be noted that the use of terms such as "first" and "second" to define components is merely for the purpose of distinguishing the corresponding components. Unless otherwise stated, these terms have no special meaning and therefore should not be construed as limiting the scope of protection of this application. In addition, although the terminology used in this application is selected from commonly known and used terms, some terms mentioned in this application's specification may have been chosen by the applicant according to his or her judgment, and their detailed meanings are explained in the relevant sections of this description. Moreover, this application should be understood not only through the actual terms used, but also through the meaning implied by each term.

[0034] Figure 1 A schematic diagram of the overall architecture of an integrated power generation system for a molten salt reactor according to an embodiment of the present invention is shown. Figure 2 A schematic diagram of a hybrid working fluid Brayton cycle power generation module according to an embodiment of the present invention is shown. Figure 1 As shown, the present invention provides a molten salt reactor integrated power generation system 100, which mainly includes a molten salt reactor high-temperature heating module 110, a heat exchange module 120, and a mixed working fluid Brayton cycle power generation module 130. The three modules are thermally connected in sequence to form a complete energy conversion and output system.

[0035] refer to Figure 2 , the hybrid working fluid Brayton cycle power generation module 130 mainly includes a gas turbine 131, a regenerator 132, a cooler 133, a compressor 134 and a generator 135. Among them, the gas turbine 131 and the compressor 134 are arranged coaxially with the generator 135, eliminating the complex gear transmission mechanism, reducing the energy loss during the transmission process, and at the same time simplifying the structural layout of the power unit and reducing the equipment failure rate during long-term operation. The pipelines are connected in sequence according to a fixed flow direction. The outlet of the gas turbine 131 is connected to the hot-side inlet of the regenerator 132, the hot-side outlet of the regenerator 132 is connected to the inlet of the cooler 133, the outlet of the cooler 133 is connected to the inlet of the compressor 134, and the outlet of the compressor 134 is connected to the cold-side inlet of the regenerator 132, forming a complete closed circulation loop. The gas working fluid in the circulation loop flows along the established pipelines in the direction indicated by the dotted arrow, successively passing through the compressor 134, the cold side of the regenerator 132, the heat exchange module 120, the gas turbine 131, the hot side of the regenerator 132, and the cooler 133, and then returning to the compressor 134 again to complete the reciprocating cycle. Specifically, the regenerator 132 can absorb most of the waste heat carried by the working fluid discharged from the gas turbine 131 and preheat the low-temperature gas working fluid entering the heat exchange module 120, effectively reducing the heat loss during the cycle. The cooler 133 cools the gas working fluid that has completed expansion work, stabilizes the temperature of the gas working fluid within the intake range suitable for the compressor 134, provides stable operating conditions for the compressor 134 to increase pressure again, and ensures that the entire power generation cycle can operate continuously and smoothly. The present invention uses the hybrid working fluid Brayton cycle power generation module 130 to replace the steam Rankine cycle system supporting the traditional molten salt reactor, which can eliminate the efficiency limitation and system complexity brought by the steam cycle and adapt to the construction requirements of modular nuclear power plants, mobile nuclear power platforms and distributed energy stations in remote areas.

[0036] Reference Figure 1 , the high-temperature heat supply module 110 of the molten salt reactor is connected to the heat exchange module 120 through a molten salt pipeline 140 to form a fuel salt circulation loop. The fuel salt uses a fluoride salt mixture containing uranium or thorium, is heated to 600 - 800 °C after absorbing the heat generated by nuclear fission in the reactor core, is sent to the heat exchange module 120 through the fuel salt circulation loop to release heat, and then returns to the reactor core to complete the cycle. The heat exchange module 120 is respectively connected to the cold-side outlet of the regenerator 132 and the inlet of the gas turbine 131 through a gas flow pipeline 150 to form a gas hybrid working fluid circulation loop. After the preheated gas working fluid absorbs heat in the heat exchange module 120, it is directly sent to the gas turbine 131 for expansion work without passing through an intermediate steam generation link, reducing the irreversible loss during the energy conversion process.

[0037] In some examples, the compressor 134 of the mixed-working-fluid Brayton cycle power generation module 130 is equipped with a variable frequency drive system, the turbine 131 adopts an axial-flow impulsive structure, and the regenerator 132 uses a counter-flow spiral channel structure. The selection of these component models matches the closed-loop circulation path of the system to facilitate thermoelectric conversion of the working fluid without phase change throughout the energy conversion process. Specifically, the compressor 134 uses a variable frequency drive system, which can adjust its speed in real time according to the load demand of the external power grid, changing the circulation flow rate of the working fluid, enabling the system to have flexible load tracking capabilities and adapt to the power generation output requirements under different operating conditions. The turbine 131 adopts an axial-flow impulsive structure, adapted to the flow characteristics of the helium-xenon mixed working fluid, maintaining high energy conversion efficiency under medium- and high-pressure operating conditions, while also possessing a simple structure, good operational stability, and the ability to withstand long-term continuous operation. The regenerator 132 adopts a counter-flow spiral channel structure, utilizing the principle of counter-flow heat exchange to achieve efficient heat transfer between the exhaust gas of the turbine 131 and the working fluid at the outlet of the compressor 134. The spiral channel enhances the turbulence of the working fluid, further improving the heat exchange effect. Simultaneously, its compact structure and small footprint meet the design requirements of modular system integration. The inert gas mixture remains in a gaseous state throughout the circulation process of the Brayton cycle power generation module 130, without a phase change process. This avoids heat loss and two-phase flow instability caused by phase change, improving the overall reliability and energy conversion efficiency of the system.

[0038] In some examples, the Brayton cycle power generation module 130 uses an inert gas mixture as the working fluid. Because inert gases are chemically stable, they do not react chemically with metallic materials under high temperature and pressure, nor do they burn or explode, ensuring long-term safe and stable system operation. Furthermore, the working fluid loss is extremely low in a closed-loop cycle, requiring no frequent replenishment. Preferably, the Brayton cycle power generation module 130 uses a helium-xenon mixture as the working fluid with a relative molecular mass of 35–45 g / mol. Through extensive thermodynamic simulations, a 5%–20% volume fraction of xenon to helium mixture was determined to form an optimal helium-xenon mixture with a relative molecular mass of approximately 40 g / mol. This ratio maximizes the thermophysical properties of the mixture while ensuring a balance between high-pressure operation stability and the target relative molecular mass. This is a crucial design feature that addresses the low thermoelectric conversion efficiency of traditional steam Rankine cycles and increases the system's cycle efficiency to over 50%. Thermodynamic simulations have verified that helium-xenon mixtures with a relative molecular mass deviating from 40 g / mol exhibit reduced thermophysical properties and high-pressure stability, resulting in a 2%–4% lower cycle efficiency compared to the target ratio, thus failing to maximize the high-temperature heat source potential of the molten salt reactor. Therefore, a helium-xenon mixture with a relative molecular mass of 40 g / mol is the optimal choice for this invention. This ratio provides a moderate sound velocity in the working fluid, enabling the turbine 131's design speed to be reduced to approximately half that of a pure helium cycle, minimizing mechanical stress and manufacturing complexity in rotating components while maintaining good heat transfer and flow characteristics, thus balancing cycle efficiency and equipment reliability. If the xenon proportion is too low, the working fluid's sound velocity remains high, failing to effectively reduce the turbine 131's speed; if the xenon proportion is too high, the working fluid density is excessively high, significantly increasing cycle flow resistance and consequently reducing system efficiency.

[0039] In some examples, the fuel salt circulation loop operates under atmospheric pressure, while the gaseous working fluid circulation loop operates under high pressure, corresponding to an operating pressure ≤1.5MPa. Atmospheric pressure operation of the fuel salt loop eliminates the risk of high-pressure vessel rupture, reduces the design and manufacturing requirements of the core structure, and enhances the inherent safety of the system. Medium- to high-pressure operation of the gas loop can reduce the size of piping and equipment while ensuring circulation efficiency, improving system compactness and facilitating modular prefabrication and transportation.

[0040] Figure 3A schematic diagram of the structure of a molten salt reactor high-temperature heating module and a heat exchange module according to an embodiment of the present invention is shown. As shown in the figure, in some examples, the molten salt reactor high-temperature heating module 110 and the heat exchange module 120 are arranged in a close-fitting integrated manner. The heat exchange module 120 includes a first heat exchanger 121 and a second heat exchanger 122, which are connected by a cooling salt pipe 123 to form an independent closed cooling salt circulation loop. The first heat exchanger 121 of the heat exchange module 120 is directly connected to the outlet of the molten salt reactor high-temperature heating module 110. The high-temperature fuel salt in the fuel salt circulation loop flows out of the molten salt reactor high-temperature heating module 110 and enters the first heat exchanger 121, where it undergoes non-contact heat exchange with the low-temperature cooling salt in the cooling salt circulation loop. After releasing heat, the fuel salt returns to the molten salt reactor high-temperature heating module 110, and the cooling salt that has absorbed heat is transported to the second heat exchanger 122 through the cooling salt pipe 123. After releasing heat, it returns to the first heat exchanger 121 for repeated cycles. The second heat exchanger 122 is arranged between the first heat exchanger 121 and the mixed working fluid Brayton cycle power generation module 130. Figure 2 As shown, the second heat exchanger 122 is connected to the cold-side outlet of the regenerator 132 and the inlet of the turbine 131 via gas flow pipes 150. This allows the helium-xenon mixed working gas, preheated by the regenerator 132, to enter the second heat exchanger 122 to absorb the heat transferred by the molten salt, and then be sent to the turbine 131 for expansion and work. The cooling salt circuit acts as an intermediate buffer layer, confining the highly radioactive fuel salt to a small area near the reactor core, reducing the radiation protection requirements of subsequent equipment, and avoiding potential safety hazards from direct contact between the fuel salt and the gaseous working gas. Even if a minor leak occurs in one stage of the heat exchanger, radioactive materials will not directly diffuse into the power cycle system, improving the system's safety redundancy.

[0041] Figure 4A schematic diagram of a second heat exchanger according to an embodiment of the present invention is shown. As shown, in some examples, the second heat exchanger 122 is a horizontal shell-and-tube structure, with an external enclosed shell 1221. Several heat exchange tubes 1222 are arranged in parallel at intervals inside the shell 1221. The second heat exchanger 122 is arranged horizontally, and four monitoring interfaces are provided on the shell 1221: a molten salt inlet monitoring interface 1223 on the right side of the shell 1221, a molten salt outlet monitoring interface 1224 on the left side, a mixed gas inlet monitoring interface 1225 on the bottom left side, and a mixed gas outlet monitoring interface 1226 on the top right side. Solid arrows in the figure indicate the flow direction of the molten salt, and dashed arrows indicate the flow direction of the mixed gas. Specifically, the outer wall of the heat exchange tubes 1222 is in direct contact with the molten salt, and the inner wall of the heat exchange tubes 1222 is in contact with the inert gas mixture. This structure can provide a large heat exchange area in a limited space, enabling efficient non-contact heat exchange between two working fluids. At the same time, the shell-and-tube structure has good pressure resistance and can adapt to the pressure difference between the gas circuit and the molten salt circuit, which facilitates the manufacturing and maintenance of the equipment.

[0042] As an alternative to the second heat exchanger 122 structure, a plate-fin heat exchanger can also be used instead of a shell-and-tube heat exchanger. Plate-fin heat exchangers offer advantages such as high heat exchange efficiency and compact size; however, their sealing structure is complex, and under the pressure gradient between the cooling salt circulation loop and the inert gas circulation loop of this invention, their sealing reliability is lower than that of a shell-and-tube heat exchanger. Furthermore, the narrow channels of plate-fin heat exchangers are easily clogged by trace impurities in the molten salt, making maintenance difficult and reducing operational reliability. Considering heat exchange performance, operational reliability, and maintenance costs, a shell-and-tube heat exchanger is the optimal choice for the second heat exchanger 122 structure.

[0043] In some examples, the shell 1221 and heat exchange tube 1222 are made of Hastelloy, with the inner wall of heat exchange tube 1222 coated with an anti-oxidation coating. Hastelloy has excellent resistance to high-temperature molten salt corrosion and can operate stably for extended periods in environments of 600–800°C, as verified in several molten salt reactor experimental devices. The anti-oxidation coating on the inner wall further inhibits the oxidation of the metal material by high-temperature gases, reduces the formation of corrosion products, and extends the service life of the heat exchange equipment.

[0044] In some examples, reference Figure 3 The heat exchange module 120 also includes a cooling salt circulation pump 124, which is installed on the cooling salt pipeline 123. The cooling salt circulation pump 124 provides power for the circulation of cooling salt, ensuring that heat can be continuously transferred from the first heat exchanger 121 to the second heat exchanger 122, maintaining a stable heat output of the system. The cooling salt circulation pump 124 adopts a shielded pump structure, with no shaft seal leakage points, and is suitable for the transportation requirements of high-temperature molten salt.

[0045] In some examples, reference Figure 3 The power generation system 100 also includes a fuel salt circulation pump 160, which is installed on the molten salt pipeline 140. This fuel salt circulation pump 160 is preferably a high-temperature resistant magnetically driven pump with a shaft-seal-free, fully sealed structure design, which can completely avoid the risk of leakage of high-temperature molten salt and is suitable for operating conditions of 600-800℃ in the fuel salt circuit. The fuel salt circulation pump 160 drives the fuel salt to circulate between the reactor core and the first heat exchanger 121, promptly removing the heat generated by the reactor core, preventing localized overheating of the reactor core, and ensuring the thermal safety of the reactor core.

[0046] In some examples, cooler 133 is connected to an external final heat sink 170 for heat dissipation. The final heat sink 170 can be flexibly selected from cooling water or an air-cooled tower depending on the resource conditions of the project site. When an air-cooled tower is used as the final heat sink 170, the system can completely eliminate its dependence on cooling water, making it suitable for water-scarce environments such as inland arid regions and islands, significantly expanding the application range of molten salt reactors. During normal operation, forced ventilation is used to ensure heat dissipation efficiency, and in the event of an accident, it can automatically switch to natural ventilation mode, continuously dissipating residual heat from the reactor core without external power, ensuring system safety in accident conditions.

[0047] Figure 5 A flowchart of a power generation method according to an embodiment of the present invention is shown. As shown, the present invention also provides a power generation method applied to the aforementioned molten salt reactor integrated power generation system 100, wherein the entire process is a continuous closed loop with no material exchange between the working fluid and the external environment. The power generation method includes the following closed loop steps: S1. The low-temperature, low-pressure inert gas mixture enters compressor 134 and is compressed to a high-pressure state. Pressurizing the working fluid is a fundamental step in the Brayton cycle, which can improve the thermodynamic efficiency of the cycle. At the same time, the high-pressure working fluid can reduce the flow path size of pipelines and equipment, and improve the overall compactness of the system.

[0048] S2. The high-pressure inert gas mixture enters the cold side channel of the regenerator 132, where it exchanges heat with the high-temperature working fluid entering the regenerator 132 from the turbine 131 outlet for preheating. The regenerator 132 recovers most of the waste heat from the turbine 131 exhaust, reducing heat emissions into the environment during the cycle. It also increases the temperature of the working fluid entering the heat exchange module 120 without increasing the heat source input, effectively improving the system's energy utilization rate.

[0049] S3. The preheated inert gas mixture enters the heat exchange module 120 through the gas flow pipe 150, absorbing the heat transferred from the molten salt reactor high-temperature heating module 110 to generate a high-temperature, high-pressure inert gas mixture. Heat is transferred in two stages within the heat exchange module 120: first from the fuel salt to the cooling salt, and then from the cooling salt to the gaseous working fluid. This achieves efficient heat exchange while ensuring that radioactive materials do not enter the power cycle system.

[0050] S4. A high-temperature, high-pressure inert gas mixture enters the gas turbine 131 through the gas flow pipe 150, expands, and performs work, driving the coaxially connected generator 135 to generate electricity and the compressor 134 to operate. The gas turbine 131 converts the thermal energy of the working fluid into mechanical energy. Part of the output mechanical energy is used to drive the compressor 134 to maintain continuous operation, and the remainder directly drives the generator 135 to convert it into electrical energy for external output. The coaxial connection structure can avoid energy loss during the transmission process.

[0051] S5. The high-temperature inert gas mixture from the outlet of turbine 131 enters the hot-side channel of regenerator 132, transferring waste heat to the high-pressure working fluid on the cold side of regenerator 132. Through this process, about 60% to 70% of the waste heat in the exhaust is recovered and utilized, with only a small amount of low-grade heat remaining that requires further processing.

[0052] S6. The inert gas mixture, cooled by the regenerator 132, enters the cooler 133, where it is cooled to form a low-temperature, low-pressure inert gas mixture, which then returns to the inlet of the compressor 134 via the cooler 133. The cooler 133 reduces the working fluid temperature to the allowable inlet temperature range of the compressor 134, ensuring stable and efficient operation of the compressor 134, and completing the last stage of the entire closed-loop cycle.

[0053] It should be noted that the temperature and pressure ranges involved in the above power generation methods meet the requirements of normal system operation: low temperature usually refers to room temperature to 120℃, low pressure refers to normal pressure to 0.2MPa; high temperature corresponds to the heating temperature of molten salt reactor, usually 600~800℃, and high pressure corresponds to the gas mixed working fluid circulation condition, usually not exceeding 1.5MPa. This range setting can take into account the system operating efficiency, safety and equipment compatibility.

[0054] The molten salt reactor integrated power generation system and its power generation method provided by this invention have the following advantages compared with the prior art: 1. The Brayton cycle, a mixture of inert gas and working fluid, is perfectly matched with the high-temperature characteristics of molten salt reactors. Through a two-stage heat exchange design, efficient heat transfer is achieved, and the overall thermoelectric conversion efficiency of the system is significantly higher than that of traditional pressurized water reactors.

[0055] 2. The modular integrated design makes the system small in size and light in weight, which facilitates factory prefabrication and on-site assembly, and greatly shortens the construction cycle.

[0056] 3. The fuel salt circulation loop operates at atmospheric pressure, eliminating the risk of high-pressure vessel rupture; the three-loop isolation design prevents radioactive materials from entering the power conversion system and simplifies the radiation shielding design; the cooler is connected to an external final heat sink, enabling the safe discharge of waste heat.

[0057] 4. Modular construction reduces costs; waterless cooling design allows operation in water-scarce areas, expanding the scope of applications; high fuel utilization and low nuclear waste generation significantly reduce costs.

[0058] 5. It has strong load tracking capability and can adapt to the peak shaving needs of the power grid; it can be used as a distributed energy source to provide a stable supply of electricity and heat to remote areas, islands and other places.

[0059] It will be apparent to those skilled in the art that various modifications and variations can be made to the exemplary embodiments described above without departing from the spirit and scope of the invention. Therefore, it is intended that this invention cover modifications and variations falling within the scope of the appended claims and their equivalents.

Claims

1. A molten salt reactor integrated power generation system, comprising a molten salt reactor high-temperature heating module, a heat exchange module, and a mixed working fluid Brayton cycle power generation module; The mixed working fluid Brayton cycle power generation module includes a gas turbine, a regenerator, a cooler, a compressor, and a generator. The gas turbine and the compressor are coaxially connected to the generator. The outlet of the gas turbine is connected to the hot side inlet of the regenerator. The hot side outlet of the regenerator is connected to the inlet of the cooler. The outlet of the cooler is connected to the inlet of the compressor. The outlet of the compressor is connected to the cold side inlet of the regenerator. The molten salt reactor high-temperature heating module is connected to the heat exchange module through a molten salt pipeline to form a fuel salt circulation loop; the heat exchange module is connected to the cold side outlet of the regenerator and the inlet of the gas turbine through gas flow pipelines to form a gas mixed working fluid circulation loop.

2. The molten salt reactor integrated power generation system as described in claim 1, characterized in that, The hybrid working fluid Brayton cycle power generation module uses a helium-xenon mixed gas working fluid with a relative molecular mass of 35-45 g / mol.

3. The molten salt reactor integrated power generation system as described in claim 1, characterized in that, The fuel salt circulation loop operates under normal pressure, while the gas mixture circulation loop operates under high pressure, with the corresponding operating pressure of the gas mixture circulation loop being ≤1.5 MPa.

4. The molten salt reactor integrated power generation system as described in claim 1, characterized in that, The heat exchange module includes a first heat exchanger and a second heat exchanger. The first heat exchanger and the second heat exchanger are connected by a cooling salt pipe to form a cooling salt circulation loop. The fuel salt in the fuel salt circulation loop and the cooling salt in the cooling salt circulation loop exchange heat in the first heat exchanger.

5. The molten salt reactor integrated power generation system as described in claim 4, characterized in that, The second heat exchanger is a shell-and-tube heat exchange structure, including a shell and a plurality of heat exchange tubes arranged in parallel at intervals inside the shell. The outer walls of the plurality of heat exchange tubes are in direct contact with molten salt, and the inner walls of the plurality of heat exchange tubes are in contact with the inert gas mixture working fluid.

6. The molten salt reactor integrated power generation system as described in claim 5, characterized in that, The shell and heat exchange tubes are made of Hastelloy alloy, and the inner wall of the heat exchange tubes is coated with an anti-oxidation coating.

7. The molten salt reactor integrated power generation system as described in claim 4, characterized in that, The heat exchange module also includes a cooling salt circulation pump, which is installed on the cooling salt pipeline.

8. The molten salt reactor integrated power generation system as described in claim 1, characterized in that, The molten salt reactor integrated power generation system also includes a fuel salt circulation pump, which is installed on the molten salt pipeline.

9. The molten salt reactor integrated power generation system as described in claim 1, characterized in that, The cooler is connected to an external final heat sink for heat dissipation.

10. A power generation method, applicable to the molten salt reactor integrated power generation system as described in any one of claims 1 to 9, characterized in that, Includes the following steps: The low-temperature, low-pressure inert gas mixture is compressed to a high-pressure state by the compressor. A high-pressure inert gas mixture enters the cold side channel of the regenerator and exchanges heat with the high-temperature inert gas mixture entering the regenerator from the turbine outlet for preheating. The preheated inert gas mixture enters the heat exchange module through the gas flow pipe, absorbs the heat transferred by the molten salt reactor high-temperature heating module, and generates a high-temperature and high-pressure inert gas mixture. A mixture of high-temperature and high-pressure inert gas working fluid enters the gas turbine through the gas flow pipe, expands and does work, driving the coaxially connected generator to generate electricity and the compressor to operate; The high-temperature inert gas mixture from the turbine outlet enters the hot-side channel of the regenerator, transferring waste heat to the high-pressure inert gas mixture on the cold side of the regenerator. The inert gas mixture, cooled by the regenerator, enters the cooler, where it is cooled to form a low-temperature, low-pressure inert gas mixture, which then returns to the compressor inlet via the cooler.

Images