Method and device for directly preheating feedwater by using heat source of low-temperature divertor of fusion reactor

Abstract

The application discloses a kind of method and device for directly preheating feedwater by fusion reactor cryogenic divertor heat source, belongs to the field of nuclear fusion power generation and thermal system engineering, directly utilizes cryogenic divertor heat source to heat feedwater by regenerator to improve power generation during pulse operation period of fusion reactor;During the pulse intermittent period of fusion reactor, the divertor loop is physically isolated, and the steam turbine extraction is switched into the regenerator to continue heating the feedwater.The application realizes the immediate use of divertor heat and lossless efficient conversion, eliminates the divertor exclusive energy storage system, reduces the initial investment of power station, and can also avoid the risk of supercooling and material failure under the condition of frequent start-stop.

Description

Technical Field

[0001] This invention belongs to the field of nuclear fusion power generation and thermal system engineering, specifically relating to a method and apparatus for direct preheating of feedwater from a cryogenic divertor heat source in a fusion reactor. Background Technology

[0002] In fusion reactor power generation systems, the blanket typically serves as the primary heat source driving the Rankine cycle for power generation. Besides the blanket, the divertor, a key component for heat dissipation and ash removal in fusion reactors, also generates a significant amount of heat. Because the divertor outlet temperature (around 200°C) is relatively low, its heat grade falls within the low-temperature range.

[0003] Fusion reactors exhibit pulsed or intermittent operation, resulting in intermittent output from both the blanket and divertor heat sources. This characteristic prevents direct integration into a power generation system for continuous and stable power generation. To overcome this intermittency, current technologies typically divide the fusion reactor heat source into several independent heating loops based on temperature grade, each equipped with its own energy storage system: a high-temperature energy storage device is configured for the high-temperature blanket heat source, while a medium-low temperature energy storage loop is configured for the low-temperature divertor heat source. During the pulse intervals, each energy storage system releases heat, working together to maintain continuous power generation.

[0004] However, the above-mentioned all-energy storage solution has the following drawbacks:

[0005] (i) After the heat source is transferred through the energy storage system, there is energy loss in the storage and release process, and the heat quality is reduced, resulting in a decrease in the overall heat utilization efficiency.

[0006] (ii) The heat grade of the divertor is relatively low. It requires a separate set of energy storage tank, heat exchanger and working fluid pump, which greatly increases the initial investment of the power plant, occupies a large area and has low economic benefits.

[0007] (iii) Multiple parallel energy storage loops require complex collaborative control strategies. Temperature fluctuations in any loop may cause imbalances in the thermodynamic parameters of the entire Rankine cycle, posing a severe challenge to system reliability and operation and maintenance.

[0008] It is worth noting that concentrated solar power (CSP) and other fields also face the problem of intermittent heat sources. However, the intermittent characteristics and operational constraints of the two types of systems are fundamentally different, making this approach unsuitable for fusion reactor scenarios.

[0009] First, the intermittent nature of concentrated solar power (CSP) plants stems from the alternation of day and night, with a timescale ranging from minutes to hours. The heat source power changes slowly, allowing the system ample time to respond. In contrast, fusion reactors experience instantaneous plasma extinguishing after the pulse ends, with the blanket and divertor thermal power returning to near zero synchronously, resulting in extremely short pulse intervals. This ultra-short-cycle, zero-inertia thermal shock characteristic requires the thermal control system to complete switching within seconds. Methods such as slowly adjusting the molten salt flow or switching auxiliary heat sources in CSP systems are unsuitable due to insufficient response speed.

[0010] Secondly, the working fluid in the fusion reactor blanket and divertor loop is radioactive. During pulse intervals, if the divertor loop, which stops generating heat, is not physically isolated in time, it will overcool under heat-free conditions, leading to safety hazards such as thermal stress fatigue, material creep failure, and even loop blockage. Concentrated solar power plants do not have the constraints of radioactive working fluid and loop isolation; their auxiliary heat source switching schemes do not need to consider physical isolation requirements and cannot provide technical reference for fusion reactor scenarios.

[0011] Therefore, there is an urgent need for a method for utilizing the divertor heat source that is oriented towards the "short pulse, zero inertia, and high safety" operating characteristics of fusion reactors. This method should be able to achieve efficient and immediate utilization of divertor heat during operation, and also enable seamless connection of physical isolation and energy compensation of the radioactive loop during pulse intervals. At the same time, it should avoid the need to configure an expensive energy storage system separately for the medium and low temperature divertor heat source. Summary of the Invention

[0012] To address the technical challenges of high costs and complex control associated with independent energy storage systems due to the intermittent operation of cryogenic divertor heat sources in existing fusion reactors, this invention provides a method and apparatus for directly preheating feedwater using a cryogenic divertor heat source. The aim is to effectively reduce initial investment and improve overall energy conversion efficiency by employing a novel non-full energy storage structure, while ensuring unit operational stability and radiation isolation safety. During fusion reactor pulse operation, the cryogenic divertor heat source is directly used to heat feedwater through a regenerator to increase power generation. During fusion reactor pulse intervals, the divertor loop is physically isolated, and steam is extracted from the turbine and fed into the regenerator to continue heating the feedwater. This invention achieves "on-demand" and lossless, efficient conversion of divertor heat, eliminating the need for a dedicated divertor energy storage system, reducing initial power plant investment, and mitigating the risks of overcooling and material failure under frequent start-up and shutdown conditions.

[0013] To achieve the above objectives, the present invention adopts the following technical solution:

[0014] A method for directly preheating feedwater using a cryogenic divertor heat source in a fusion reactor involves the following steps: During the fusion reactor pulse operation period, the circulation loop containing the divertor is activated, and the heat from the divertor is transferred to the regenerator side to heat the feedwater, directly utilizing the divertor heat source to heat the feedwater through the regenerator to increase power generation. During the fusion reactor pulse interval, the circulation loop containing the divertor is physically isolated, and the turbine extraction steam is switched to enter the same regenerator to continue heating the feedwater. When switching from the fusion reactor pulse operation period to the fusion reactor pulse interval, the circulation loop containing the divertor is isolated again, and the heat source flow path is switched simultaneously, with the turbine extraction steam being introduced to the regenerator side to continue heating the feedwater. During the fusion reactor pulse interval, the turbine extraction steam rate introduced into the regenerator is adjusted according to the amount of heat from the divertor to achieve a smooth transition of the heat source and a stable feedwater temperature.

[0015] This invention also provides a device for direct preheating feedwater from a fusion reactor cryogenic divertor heat source, used to implement the aforementioned method for direct preheating feedwater from a fusion reactor cryogenic divertor heat source. The device includes a fusion reactor heat source subsystem and a Rankine cycle power generation system. The fusion reactor heat source subsystem is connected to the heat source of the fusion reactor and is used to absorb heat and drive the Rankine cycle power generation system to generate electricity. The Rankine cycle power generation system absorbs heat from the high-temperature heat source of the fusion reactor and drives power generation, and receives heat from a cryogenic heat source or extracted steam to preheat the working fluid. The Rankine cycle power generation system includes a main loop and a multi-source circuit on the hot side of the regenerator. The multi-source circuit on the hot side of the regenerator is equipped with a three-way valve for dynamically adjusting the heat source of the regenerator in the main loop.

[0016] Beneficial effects:

[0017] 1. Addressing the pulsed characteristics of fusion reactor heat sources, this invention employs a non-full energy storage structure: the blanket is equipped with energy storage, while the divertor is not. The divertor heat follows a "produce-as-you-go" principle, providing direct heating during operation and physical isolation during off-peak periods, with the blanket energy storage system indirectly compensating for the heat required for feedwater heating via turbine extraction. Because the divertor heat is directly utilized without passing through an energy storage stage, there is no loss in heat quality, resulting in higher overall efficiency than a full energy storage scheme. Simultaneously, it completely eliminates independent energy storage tanks, dedicated heat exchangers, and working fluid pumps, significantly reducing the footprint and initial investment, and fundamentally simplifying the complex collaborative control logic resulting from multi-loop parallel energy storage.

[0018] 2. During the pulse operation of the fusion reactor, this invention directly utilizes the divertor to heat the feedwater, reducing the amount of regenerative steam extraction and allowing more steam to expand and perform work in the turbine, thereby directly improving the power generation of the Rankine cycle and the overall thermal efficiency of the plant.

[0019] 3. The divertor and turbine extraction steam share the same regenerator, switching between pulse operation and intermittent operation through a logical combination of three-way valves and isolation valves. The heating parameters of the two heat sources are matched to ensure that the inlet and outlet temperatures of the cold-side feedwater of the regenerator remain consistent throughout the entire pulse cycle. This ensures the stability of the Rankine cycle thermodynamic parameters throughout the cycle, eliminating parameter disturbances caused by the heat source pulse returning to zero, and guaranteeing the unit's operational reliability and stable grid output under frequent start-stop conditions. Simultaneously, the valve closure during intermittent operation completely physically isolates the divertor's radioactive working fluid loop from the Rankine cycle, fundamentally avoiding the risks of overcooling, thermal stress, and material failure under heat source-free conditions. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of a direct preheating feedwater device for a fusion reactor cryogenic divertor heat source according to the present invention.

[0021] The attached figures are labeled as follows: 1-cladding; 2-energy storage system; 3-divertor; 4-steam generator; 5-regenerator; 6-low temperature heat source heat exchanger; 7-high pressure cylinder; 8-medium pressure cylinder; 9-low pressure cylinder; 10-generator; 11-condenser; 12-low pressure feedwater heater; 13-deaerator; 14-high pressure feedwater heater; 15-circulating working fluid pump; 16-feedwater pump; 17-first isolation valve; 18-second isolation valve; 19-first three-way valve; 20-second three-way valve. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0023] like Figure 1 As shown, the direct preheating feedwater device for a fusion reactor cryogenic divertor heat source proposed in this invention includes a fusion reactor heat source subsystem and a Rankine cycle power generation system. The fusion reactor heat source subsystem is connected to the heat source of the fusion reactor and is used to absorb heat and drive the Rankine cycle power generation system to generate electricity; the Rankine cycle power generation system absorbs heat from the high-temperature heat source of the fusion reactor and drives power generation, and receives heat from the cryogenic heat source or extracted steam to preheat the working fluid;

[0024] The fusion reactor heat source subsystem includes a blanket 1, an energy storage system 2, a divertor 3, a circulating working fluid pump 15, and a second isolation valve 18.

[0025] The outlet of the cladding 1 is connected to the energy storage system 2, which in turn is connected to the hot side of the steam generator 4 to supply heat to the power generation system. The outlet of the divertor 3 is connected to the hot side inlet of the low-temperature heat source heat exchanger 6 via a circulating working fluid pump 15; the hot side outlet of the low-temperature heat source heat exchanger 6 is connected back to the inlet of the divertor 3 via a second isolation valve 18, forming a closed-loop circulation circuit for the cooling working fluid of the divertor. The cladding 1 and the divertor 3 use different cooling working fluid circuits and operate in different temperature ranges. The cladding 1 is typically a high-temperature heat source, while the divertor 3 is a medium- or low-temperature heat source.

[0026] The Rankine cycle power generation system includes a steam generator 4, a high-pressure cylinder 7, a medium-pressure cylinder 8, a low-pressure cylinder 9, a generator 10, a condenser 11, a low-pressure feedwater heater 12, a regenerator 5, a deaerator 13, a feedwater pump 16, a high-pressure feedwater heater 14, a first isolation valve 17, a second isolation valve 18, and a core valve group for switching operating conditions, a first three-way valve 19 and a second three-way valve 20.

[0027] The Rankine cycle power generation system's piping utilizes a logical combination of two three-way valves to achieve flexible distribution of multi-source heat energy.

[0028] In the main circuit, the cold-side outlet of the steam generator 4 is sequentially connected to the high-pressure cylinder 7, the intermediate-pressure cylinder 8, and the low-pressure cylinder 9 for expansion and work, coaxially driving the generator 10 to generate electricity. The exhaust steam from the low-pressure cylinder 9 is condensed by the condenser 11 and then sequentially passes through the first isolation valve 17 and the pipe side of the low-pressure feedwater heater 12 before entering the cold-side inlet of the regenerator 5. The feedwater, heated by the regenerator 5, then sequentially passes through the deaerator 13, the feedwater pump 16, and the high-pressure feedwater heater 14 for further heating and pressurization before finally returning to the cold-side inlet of the steam generator 4, completing the main circuit cycle.

[0029] In the multi-source circuit on the hot side of the regenerator, the heat source on the hot side of the regenerator 5 has two switchable sources. The first inlet of the first three-way valve 19 is connected to the cold side outlet of the low-temperature heat source heat exchanger 6, its second inlet is connected to the exhaust / extraction port of the high-pressure cylinder 7, and its outlet is connected to the hot side inlet of the regenerator 5; the inlet of the second three-way valve 20 is connected to the hot side outlet of the regenerator 5, its first outlet is connected to the cold side inlet of the low-temperature heat source heat exchanger 6, and its second outlet is connected to the hot side drain inlet of the low-pressure feedwater heater 12.

[0030] Preferably, the circulating working fluid of the energy storage system 2 is a fluid with high stability and high specific heat capacity, such as high-temperature heat transfer oil, molten salt, phase change material or other liquid metal (such as sodium-potassium alloy).

[0031] Preferably, the circulating working fluid in the cooling working fluid loop of the divertor 3 is a fluid such as water, supercritical carbon dioxide, or an organic working fluid.

[0032] Based on the above system, this invention provides a method for directly preheating feedwater using a cryogenic divertor heat source in a fusion reactor. During the fusion reactor pulse operation period, the circulation loop containing divertor 3 is activated, and the heat from the divertor is introduced to the regenerator side to heat the feedwater. The cryogenic heat source from the divertor is directly used to heat the feedwater through the regenerator 5 to increase power generation. During the fusion reactor pulse interval, the circulation loop containing divertor 3 is physically isolated, and the turbine extraction steam is switched to enter the same regenerator 5 to continue heating the feedwater. When the fusion reactor switches from the fusion reactor pulse operation period to the fusion reactor pulse interval, the circulation loop containing divertor 3 is isolated, and the heat source flow path is switched simultaneously, introducing the turbine extraction steam to the regenerator side to continue heating the feedwater. During the fusion reactor pulse interval, the amount of turbine extraction steam introduced into the regenerator 5 is adjusted according to the amount of heat from the divertor to achieve a smooth transition of the heat source and a stable feedwater temperature.

[0033] Preferably, the real-time thermal power is calculated based on the inlet and outlet temperature difference and flow signal of the circulation loop where the divertor is located, and the opening of the extraction steam regulating valve is adjusted accordingly to maintain the total heating capacity of the regenerator at the set value.

[0034] Specifically, the present invention provides a method for direct preheating of feedwater from a cryogenic divertor heat source in a fusion reactor, which has two operating modes, achieved by adjusting the switching of isolation valves (first isolation valve 17, second isolation valve 18) and three-way valve groups (first three-way valve 19, second three-way valve 20):

[0035] a. Fusion reactor pulse operation mode:

[0036] At this time, the fusion reactor is outputting thermal power normally. Open the first isolation valve 17 and the second isolation valve 18; start the circulating working fluid pump 15 and the feed water pump 16.

[0037] Control the first three-way valve 19 to connect the cold side outlet of the low-temperature heat source heat exchanger 6 to the hot side inlet of the regenerator 5; control the second three-way valve 20 to connect the hot side outlet of the regenerator 5 to the cold side inlet of the low-temperature heat source heat exchanger 6.

[0038] The high-temperature heat generated by the cladding 1 enters the steam generator 4 through the energy storage system 2 to drive the main circuit for power generation. Simultaneously, the heat source generated by the divertor 3 exchanges heat with the regenerating circulating medium through the low-temperature heat source heat exchanger 6. This medium flows through the first three-way valve 19 into the regenerator 5 to release heat and heat the main condensate, and then returns to the low-temperature heat source heat exchanger 6 through the second three-way valve 20, forming an independent small heat exchange cycle. In this mode, the heat from the divertor directly replaces the steam extracted from the turbine, achieving immediate and full utilization and improving the unit's power generation capacity.

[0039] b. Fusion reactor pulse-intermittent mode:

[0040] At this time, the fusion reactor is in a low-power pulse intermittent period. Close the second isolation valve 18 and stop the circulating working fluid pump 15.

[0041] Control the first three-way valve 19 to switch to connect the steam extraction port of the high-pressure cylinder 7 with the hot side inlet of the regenerator 5; control the second three-way valve 20 to switch to receive the incoming flow from the hot side outlet of the regenerator 5 and guide it to the hot side drain inlet of the low-pressure feedwater heater 12.

[0042] The circulation loop containing cladding 1 and divertor 3 is physically isolated and stops supplying heat. Heat is generated by energy storage system 2 through steam generator 4, maintaining continuous steam production and stable power generation in the main loop. Since the heat source for the divertor stops supplying heat, the system uses high-pressure cylinder 7 to extract steam via the first three-way valve 19 to heat the feedwater in regenerator 5. The condensate from the extracted steam in regenerator 5 flows by gravity through the second three-way valve 20 into the low-pressure feedwater heater 12 to continue utilizing sensible heat. In this mode, the stored high-temperature medium simultaneously meets the requirements for main steam generation and steam extraction reheating, ensuring the stability of the Rankine cycle thermodynamic system and continuous power generation capability throughout the entire intermittent period.

[0043] In the above embodiment, the regenerator 5 is located between the low-pressure feedwater heater 12 and the deaerator 13, suitable for situations where the divertor outlet temperature is in the low-temperature range (typically around 150–200°C). Alternatively, depending on the divertor outlet temperature, the regenerator 5 can be flexibly arranged in different locations within the regenerative system to achieve optimal thermal matching.

[0044] (1) When the outlet temperature of the cooling medium in the divertor is low (e.g., below 150°C), its heat quality is only sufficient to heat the feedwater from the condenser outlet temperature (approximately 30-50°C) to the required temperature at the inlet of the low-pressure feedwater heater 12. At this time, the regenerator 5 is arranged between the outlet of the condenser 11 and the low-pressure feedwater heater 12, undertaking the task of preheating the feedwater in the lowest temperature range. During the intermittent period, the steam extracted from the low-pressure cylinder (corresponding to the extraction stage with the lowest pressure and temperature) is taken to ensure the consistency of the heating parameters of the two heat sources and to ensure that the feedwater outlet temperature remains unchanged.

[0045] (2) When the outlet temperature of the cooling medium in the divertor is in the medium-low temperature range (e.g., 150–250°C), its heat quality is sufficient to further heat the feedwater at the outlet of the low-pressure feedwater heater 12 to the inlet temperature required by the deaerator 13 (approximately 150–160°C). The regenerator 5 is arranged in this section to directly replace the feedwater preheating requirement before the deaerator. During the intermittent period, the steam is extracted from the exhaust steam of the high-pressure cylinder or the extraction steam of the intermediate-pressure cylinder, and the pressure and temperature of both are matched to the heating requirement of the feedwater before the deaerator.

[0046] (3) When the outlet temperature of the cooling medium in the divertor is in the medium temperature range (e.g., 250–350°C), its heat quality is sufficient to meet the further temperature increase requirements of the feedwater at the deaerator outlet. The regenerator 5 is arranged between the outlet of the deaerator 13 and the high-pressure feedwater heater 14, undertaking part of the high-pressure feedwater preheating task and replacing the extraction steam supply of the first-stage or multi-stage high-pressure feedwater heater 14. During the intermittent period, the corresponding extraction steam is taken from the intermediate-pressure cylinder 8 to maintain the feedwater inlet and outlet parameters unchanged in this temperature range.

[0047] (4) When the outlet temperature of the cooling medium in the divertor is high (e.g., above 350°C), its heat quality is sufficient to directly heat the high-pressure feedwater after it has been heated by the high-pressure feedwater heater 14, further increasing the feedwater temperature entering the steam generator 4, and replacing all or most of the extraction steam supply from the high-pressure feedwater heater 14. During the intermittent period, the steam is extracted from the high-pressure cylinder to ensure that the feedwater temperature at the inlet of the steam generator remains consistent throughout the entire pulse cycle.

[0048] In summary, this invention addresses the characteristics of fusion reactor heat sources by employing a non-full energy storage configuration. The blanket, serving as the high-temperature primary heat source, is equipped with an energy storage system to overcome pulse intermittents and maintain continuous main steam generation. The divertor, serving as the medium- and low-temperature heat source, does not have independent energy storage; instead, it follows a "produce-as-you-go" principle, directly injecting heat into the feedwater preheating circuit during pulse periods. After the pulse ends, the circuit is immediately shut off via valves to achieve physical isolation. During pulse intermittent periods, with the divertor power at zero and the physical circuit isolated, the heat required for feedwater preheating is transferred to turbine extraction steam. The blanket and energy storage system maintain a continuous main steam supply, and the turbine operates normally. Extracted steam is drawn from the turbine and used to heat the feedwater via the same regenerator previously supplied by the divertor. The condensate from the extracted steam is then channeled into the low-pressure feedwater heater for continued use. Thus, the heat loss from the divertor is compensated by the extracted steam, ensuring uninterrupted heat supply to the feedwater throughout the entire pulse cycle. The divertor and turbine extraction steam share the same regenerator. Through the logical coordination of a three-way valve and an isolation valve, the two heat sources are connected to the hot side of the regenerator in a time-sharing manner. During the fusion reactor pulse operation period, the isolation valve opens, the divertor cooling medium circulation pump starts, and the three-way valve connects the hot side of the regenerator to the divertor heat source circuit, while the extraction steam channel is closed. During the fusion reactor pulse interval, the isolation valve closes, the circulation pump stops, and the three-way valve switches to connect the turbine extraction steam to the hot side of the regenerator, physically disconnecting the divertor circuit. In both modes, the inlet and outlet temperatures of the cold side feedwater of the regenerator remain consistent, meaning the heating parameters of the divertor match the heating parameters of the extraction steam during the fusion reactor pulse interval, ensuring a constant feedwater temperature throughout the entire pulse cycle.

[0049] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for directly preheating feedwater using a heat source in a cryogenic divertor for a fusion reactor, characterized in that, During the fusion reactor pulse operation period, the circulation loop containing the divertor is activated, transferring the heat from the divertor to the regenerator side to heat the feedwater. This direct use of the divertor heat source to heat the feedwater through the regenerator increases power generation. During the fusion reactor pulse intermittent period, the circulation loop containing the divertor is physically isolated, and turbine extraction steam is switched to the same regenerator to continue heating the feedwater. When switching from the fusion reactor pulse operation period to the fusion reactor pulse intermittent period, the circulation loop containing the divertor is isolated again, and the heat source flow path is switched simultaneously, transferring turbine extraction steam to the regenerator side to continue heating the feedwater. During the fusion reactor pulse intermittent period, the turbine extraction steam rate to the regenerator is adjusted according to the amount of heat transferred from the divertor to achieve a smooth transition of the heat source and stable feedwater temperature. Real-time thermal power is calculated based on the inlet and outlet temperature difference and flow rate signal of the circulation loop containing the divertor, and the opening of the extraction steam regulating valve is adjusted accordingly to maintain the total heating capacity of the regenerator at the set value.

2. A device for directly preheating feedwater from a fusion reactor cryogenic divertor heat source, used to implement the method for directly preheating feedwater from a fusion reactor cryogenic divertor heat source as described in claim 1, characterized in that, It includes a fusion reactor heat source subsystem and a Rankine cycle power generation system; the fusion reactor heat source subsystem is connected to the heat source of the fusion reactor to absorb heat and drive the Rankine cycle power generation system to generate electricity; the Rankine cycle power generation system absorbs heat from the high-temperature heat source of the fusion reactor to drive power generation, and receives heat from the low-temperature heat source or extracted steam to preheat the working fluid; the Rankine cycle power generation system includes a main loop and a multi-source circuit on the hot side of the regenerator, and the multi-source circuit on the hot side of the regenerator is equipped with a three-way valve to dynamically adjust the heat source of the regenerator in the main loop.

3. The direct preheating feedwater device for a fusion reactor cryogenic divertor heat source according to claim 2, characterized in that, The fusion reactor heat source subsystem includes a blanket, an energy storage system, a divertor, a circulating working fluid pump, and a second isolation valve. The outlet of the blanket is connected to the energy storage system, which is connected to the hot side of the steam generator to supply heat to the Rankine cycle power generation system. The outlet of the divertor is connected to the hot side inlet of the cryogenic heat source heat exchanger. The hot side outlet of the cryogenic heat source heat exchanger is connected to the inlet of the divertor through the second isolation valve.

4. The direct preheating feedwater device for a fusion reactor cryogenic divertor heat source according to claim 3, characterized in that, The cladding and divertor operate in different temperature ranges.

5. A direct preheating feedwater device for a fusion reactor cryogenic divertor heat source according to claim 3, characterized in that, The Rankine cycle power generation system includes a steam generator, a high-pressure cylinder, an intermediate-pressure cylinder, a low-pressure cylinder, a generator, a condenser, a low-pressure feedwater heater, a regenerator, a deaerator, a feedwater pump, a high-pressure feedwater heater, a first isolation valve, a second isolation valve, a first three-way valve, and a second three-way valve. In the main circuit, the cold-side outlet of the steam generator is sequentially connected to the high-pressure cylinder, the intermediate-pressure cylinder, and the low-pressure cylinder. Its exhaust steam, after condensation, flows sequentially through the first isolation valve and the low-pressure feedwater heater, entering the cold side of the regenerator. Subsequently, it returns to the steam generator via the deaerator, the feedwater pump, and the high-pressure feedwater heater.

6. The direct preheating feedwater device for a fusion reactor cryogenic divertor heat source according to claim 5, characterized in that, In the multi-source circuit on the hot side of the regenerator, the first inlet of the first three-way valve is connected to the cold side outlet of the low-temperature heat source heat exchanger, the second inlet of the first three-way valve is connected to the steam extraction port of the steam turbine, and the outlet of the first three-way valve is connected to the hot side inlet of the regenerator; the inlet of the second three-way valve is connected to the hot side outlet of the regenerator, the first outlet of the second three-way valve is connected to the cold side inlet of the low-temperature heat source heat exchanger, and the second outlet of the second three-way valve is connected to the hot side drain inlet of the low-pressure feedwater heater.

7. A direct preheating feedwater device for a fusion reactor cryogenic divertor heat source according to claim 6, characterized in that, The main circuit is a circuit that realizes either a steam Rankine cycle or a supercritical carbon dioxide Brayton cycle; the regenerator in the multi-source circuit on the hot side of the regenerator is arranged on the pipeline between the condenser outlet and the steam generator inlet according to the temperature range of the working fluid at the divertor outlet.

8. A direct preheating feedwater device for a fusion reactor cryogenic divertor heat source according to claim 6, characterized in that, During the fusion reactor pulse operation period, the circulation loop where the divertor is located is opened; the first three-way valve and the second three-way valve are controlled to introduce the circulating medium from the low-temperature heat source heat exchanger into the hot side of the regenerator to heat the feedwater, replacing the turbine extraction steam; during the fusion reactor pulse interval, the circulation loop where the divertor is located is isolated; the first three-way valve and the second three-way valve are controlled to switch, and the turbine extraction steam is introduced into the hot side of the regenerator to continue heating the feedwater.

9. A direct preheating feedwater device for a fusion reactor cryogenic divertor heat source according to claim 5, characterized in that, During the pulse operation of the fusion reactor, the first isolation valve and the second isolation valve are opened, and the circulating working fluid pump and the feed water pump are started; the first three-way valve is controlled to connect the cold side outlet of the low-temperature heat source heat exchanger with the hot side inlet of the regenerator, and the second three-way valve is controlled to connect the hot side outlet of the regenerator with the cold side inlet of the low-temperature heat source heat exchanger, forming an independent small heat exchange cycle.

10. A direct preheating feedwater device for a fusion reactor cryogenic divertor heat source according to claim 9, characterized in that, During the fusion reactor pulse interval, the second isolation valve is closed and the circulating working fluid pump is stopped; the first three-way valve is switched to connect the turbine extraction port and the hot side inlet of the regenerator, and the second three-way valve is switched to receive the incoming flow from the hot side outlet of the regenerator and guide it to the hot side drain inlet of the low-pressure feedwater heater.

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