Integrated divertor heat recovery for nuclear fusion rankine cycle

Abstract

The application belongs to the cross technical field of nuclear fusion energy technology and heat power conversion system, and provides a nuclear fusion Rankine cycle structure integrated with a divertor heat recovery, which comprises a heat collection module on a primary side and a heat power conversion module on a secondary side; the heat power conversion module comprises a steam generator, a first valve, a high-pressure turbine, a dehumidifier, a reheater, a low-pressure turbine, a condenser, a first water pump, a first feedwater heater, a second feedwater heater, a deoxidizer, a second water pump, a third feedwater heater and a preheating heat exchanger which are sequentially connected through pipelines; the preheating heat exchanger is used for preheating secondary side water supply before entering the steam generator by using the heat of the divertor; the outlet water temperature of the third feedwater heater is matched with the temperature of the preheating heat exchanger by adjusting the inlet steam extraction flow of the third feedwater heater. The structure realizes gradient utilization of nuclear fusion heat and reduces irreversible loss in the heat exchange process.

Description

Technical Field

[0001] This invention relates to the interdisciplinary field of nuclear fusion energy technology and heat-work conversion systems, specifically to a thermonuclear Rankine cycle structure with a divertor as a preheater. Background Technology

[0002] Excessive greenhouse gas emissions are a major cause of climate change. Nuclear energy, including fission and fusion reactors, along with renewable energy sources, is seen as an alternative to fossil fuels to combat the greenhouse effect. In terms of nuclear power plants, fusion reactors are currently the world's hottest topic compared to fission reactors due to their inherent advantages, such as high-grade fusion heat energy, coolant temperature at the outlet, inherent safety due to the lack of chain reaction risk, and the requirement of only hydrogen isotopes to initiate the reaction. Power plants based on the fusion energy concept can overcome the world's electricity demand, meeting energy needs and powering homes, industries, buildings, and cooling systems. Nuclear fusion energy is considered one of the ultimate solutions for future clean energy. In magnetic confinement fusion devices (such as tokamak), deuterium-tritium fuel forms plasma and undergoes a fusion reaction at hundreds of millions of degrees Celsius, releasing enormous energy. However, the reaction process produces helium ash and other impurities, releasing a large amount of heat. If this heat is not effectively removed and controlled in a timely manner, it will lead to plasma cooling and reaction termination. The divertor is a core component for solving this challenge; it is located at the bottom of the fusion reactor's vacuum chamber, serving as a transition zone where the high-temperature plasma directly contacts the solid material.

[0003] The Rankine cycle is currently the most widely used heat-to-work conversion cycle in nuclear fission power generation. At present, nuclear fusion research and the design of power conversion systems are relatively independent. In fusion reactor design, the divertor is considered a passively cooled "heat load," and the enormous heat it carries is usually directly discharged into the environment through complex cooling systems (such as helium or water cooling systems), failing to be effectively converted into useful work. This leads to a huge waste of high-quality thermal energy and reduces the overall energy utilization efficiency of the fusion reactor. Existing research has begun to consider using the low-grade heat from the divertor to heat the secondary feedwater to supply the steam generator. For example, Chinese invention patent application CN119642180A, "A Fusion Energy Heat Feed System Loop Structure," provides two independent cooling loops: a blanket cooling loop and a divertor cooling loop. The divertor cooling loop cools the divertor's coolant through the main heat exchanger. However, this structure consists of two independent cooling cycles, and its primary focus is on the safety of cooling the fusion reaction, rather than the efficient use of the divertor's heat for power generation. Therefore, the heat from the divertor is directly coupled to the circulating water, without integration with the fluid communication of the steam generator or the multi-stage heater. Consequently, compared to the high-grade (~300-500°C) heat from the cladding, the low-grade (~150-250°C) heat from the divertor is mismatched and used to heat the overall circulating water, resulting in insufficient thermodynamic matching and significant irreversible losses in some heat exchange processes. Summary of the Invention

[0004] The technical problem to be solved by this invention is how to achieve gradient utilization of nuclear fusion heat in the Rankine cycle based on nuclear fusion, and reduce irreversible losses in the heat exchange process.

[0005] The present invention solves the above-mentioned technical problems through the following technical means: This invention provides a nuclear fusion Rankine cycle structure with integrated divertor heat recovery, comprising: A primary heat collection module and a secondary heat-work conversion module; The heat collection module includes a cladding heat exchange loop for high-grade heat collection and a divertor preheating loop for low-grade heat collection. The heat conversion module includes a steam generator, a first valve, a high-pressure turbine, a dehumidifier, a reheater, a low-pressure turbine, a condenser, a first water pump, a first feedwater heater, a second feedwater heater, a deaerator, a second water pump, a third feedwater heater, and a preheating heat exchanger, all connected in sequence via pipelines. The preheating heat exchanger uses the heat from the divertor to preheat the secondary side water supply before it enters the steam generator. Based on the outlet water temperature of the third feedwater heater, adjust the inlet steam flow rate of the third feedwater heater to match the outlet water temperature of the preheating heat exchanger, thereby reducing irreversible losses.

[0006] Preferably, the exhaust port of the steam generator is also connected to the reheater via a pipe, and the outlet steam of the high-pressure turbine is heated by the reheater after passing through the dehumidifier and then enters the low-pressure turbine for the second stage of expansion.

[0007] Preferably, after passing through the low-pressure turbine, the steam is condensed in the condenser and then pumped into the first feedwater heater by the first water pump. Preferably, the low-pressure turbine is also connected to the first feedwater heater and the second feedwater heater via pipelines for steam extraction, and the steam temperature at the connection point between the first feedwater heater and the low-pressure turbine is lower than the steam temperature at the connection point between the second feedwater heater and the low-pressure turbine.

[0008] Preferably, the high-pressure turbine is also connected to the third feedwater heater via a pipeline for steam extraction.

[0009] Preferably, a bypass pipe and a second valve connected in series are provided between the second feedwater heater and the first feedwater heater. The steam extracted from the low-pressure turbine is condensed into water after heat exchange and returns to the first feedwater heater through the second valve.

[0010] Preferably, a bypass pipe and a third valve connected in series are provided between the third feedwater heater and the deaerator. The steam extracted from the high-pressure turbine is condensed into water after heat exchange and enters the deaerator through the third valve.

[0011] Preferably, the dehumidifier is also connected to the deaerator via a pipe to provide the heat required for the deaeration process.

[0012] Preferably, the reheater is also connected to the deaerator via a pipeline to provide the heat required for the deaeration process.

[0013] Preferably, the inlet steam flow rate of the third feedwater heater is adjusted by adjusting the opening degree of the third valve.

[0014] The advantages of this invention are: (1) This invention incorporates the heat from the divertor into the power cycle, forming a series structure of "feedwater preheating + blanket steam generation," which ensures safe heat dissipation of the divertor while effectively recovering residual heat. Simultaneously, by controlling the extraction steam flow rate of the last-stage feedwater heater, the temperature of the secondary side supply water entering the preheating heat exchanger is controlled, ensuring that the temperature of the preheating heat exchanger matches the supply water temperature. This avoids thermodynamic mismatch caused by directly using a low-grade heat source and reduces irreversible losses in the heat exchange process. Furthermore, by progressively heating the secondary side supply water, heat waste from the extraction steam of the high-pressure and low-pressure turbines is avoided, increasing the effective output of the turbine and improving the overall efficiency of the cycle, thereby enhancing the performance of the nuclear fusion power generation system.

[0015] (2) The design of this invention places the divertor heat exchanger at the low-temperature feedwater heating position, forming a complementary relationship with the traditional high-pressure / low-pressure heater. The design structure is compact, requiring no additional equipment, reducing system complexity, and making the system more suitable for the overall energy management of fusion reactors. At the same time, it directly results in a reduction in cooling load and an improvement in reactor safety. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of a nuclear fusion Rankine cycle structure with integrated divertor heat recovery according to an embodiment of the present invention; Reference numerals: 1. Steam generator; 2. First valve; 3. High-pressure turbine; 4. Dehumidifier; 5. Reheater; 6. Low-pressure turbine; 7. Condenser; 8. First water pump; 9. First feedwater heater; 10. Second feedwater heater; 11. Deaerator; 12. Second water pump; 13. Third feedwater heater; 14. Preheating heat exchanger; 15. Second valve; 16. Third valve; 17. Coating; 18. Divertor. Detailed Implementation

[0017] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0018] Example 1 This embodiment provides a novel nuclear fusion power generation system structure based on the Rankine cycle. The system incorporates two stages of expansion and one stage of reheat, and rationally integrates divertor heat with a multi-stage feedwater heating system, resulting in a compact structure. By effectively recovering divertor heat, the heat dissipation burden on the cooling circuit is reduced, improving the reactor's operational safety. Simultaneously, by controlling the secondary-side supply water temperature entering the divertor preheating loop to match the temperature of the preheating heat exchanger, irreversible losses in the heat exchange process are reduced, avoiding the loss of extraction steam heat and improving the overall system efficiency. The specific structure is as follows: Figure 1 As shown, it includes: The primary side has a heat collection module and the secondary side has a heat-work conversion module; this embodiment is not limited to the cooling heat feedback loop of nuclear fusion, but is a Rankine cycle-based structure that combines the cooling safety of nuclear fusion reaction with heat-work conversion.

[0019] The heat collection module includes a cladding 17 heat exchange loop for high-grade heat collection and a divertor 18 preheating loop for low-grade heat collection. The cladding 17 heat exchange loop uses the high-grade heat (300–500 °C) of the cladding 17 as the heat source for the core of the steam generator 1, while the divertor 18 preheating loop uses the low-grade heat (approximately 150–250 °C) of the divertor to preheat the water supply through the preheating heat exchanger 14.

[0020] The heat-power conversion module includes a steam generator 1, a first valve 2, a high-pressure turbine 3, a dehumidifier 4, a reheater 5, a low-pressure turbine 6, a condenser 7, a first water pump 8, a first feedwater heater 9, a second feedwater heater 10, a deaerator 11, a second water pump 12, a third feedwater heater 13, and a preheating heat exchanger 14, all connected in sequence via pipelines. The high-pressure turbine 3 and the low-pressure turbine 6 are coaxially connected.

[0021] The preheating heat exchanger 14 uses the heat from the divertor 18 to preheat the secondary side water supply before it enters the steam generator 1. Based on the temperature difference between the outlet water temperature of the third feedwater heater 13 and the temperature of the preheating heat exchanger 14, the inlet steam flow rate of the third feedwater heater 13 is adjusted to match the outlet water temperature of the third feedwater heater 13 with the temperature of the preheating heat exchanger 14, thereby reducing irreversible losses.

[0022] The exhaust port of the steam generator 1 is also connected to the reheater 5 through a pipe. The outlet steam of the high-pressure turbine 3 passes through the dehumidifier 4 and is heated by the reheater 5 before entering the low-pressure turbine 6 for the second stage of expansion.

[0023] After passing through the low-pressure turbine 6, the steam is condensed in the condenser 7 and then sent to the first feedwater heater 9 by the first water pump 8. In this embodiment, the circulation process from cold-end water supply to hot-end steam in the above structure is as follows: After the steam low-pressure turbine 6 performs its second expansion and work, it is condensed by the condenser 7, discharging excess heat from the system. The condensate is pressurized by the first water pump 8 and fed into the first feedwater heater 9, and then heated in stages, passing through the second feedwater heater 10 and the third feedwater heater 13 before finally entering the preheating heat exchanger 14, completing the multi-stage feedwater heating for the cold end. During the cold end feedwater circulation stage, the water also passes through the deaerator 11, which releases dissolved oxygen in the water through physical thermal deoxygenation, reducing the oxygen corrosion effect on the system. The deoxygenated water deposited in the deaerator 11 tank is pressurized by the second water pump 12 and sent to the third feedwater heater 13 and the preheating heat exchanger 14, completing the feedwater heating stage before vaporization.

[0024] Preheated water enters steam generator 1, where it undergoes a phase change and is heated into high-pressure steam using the high-grade heat of the cladding 17. This steam is then fed into high-pressure turbine 3 via the first valve 2 for its first expansion and work. After completing its work, the steam exits high-pressure turbine 3, passes through dehumidifier 4, and enters reheater 5. It is then reheated to a higher temperature before entering low-pressure turbine 6 for its second expansion and work, completing the hot-end steam's work phase. The dehumidifier 4 is included to reduce humidity and improve the quality of the steam entering low-pressure turbine 6.

[0025] During the hot-end steam circulation stage, steam is extracted from the inlet of the high-pressure turbine 3 to the reheater 5 and the third feedwater heater 13, respectively, to provide the heat required for steam reheating and cold-end water preheating. Simultaneously, steam is extracted from the low-pressure turbine 6 to the first feedwater heater 9 and the second feedwater heater 10, respectively, to provide the heat required for the initial two-stage water supply heating. As required for graded heating, the steam temperature at the connection point between the first feedwater heater 9 and the low-pressure turbine 6 is lower than the steam temperature at the connection point between the second feedwater heater 10 and the low-pressure turbine 6.

[0026] Specifically, the steam extraction flow rate from the inlet of the high-pressure turbine 3 to the third feedwater heater 13 is determined by the temperature difference between the supply water temperature at the outlet of the third feedwater heater 13 and the temperature of the preheating heat exchanger 14. The supply water temperature is measured using conventional methods of existing technology, and will not be elaborated upon in this embodiment. The operating mode where the steam extraction flow rate is determined by the temperature difference is as follows: (1) When the temperature difference deviates from the temperature matching range due to the large temperature difference (in this embodiment, considering the reasonable area of ​​the heat exchanger, the temperature difference of 100°C ± 10% is used as the matching range), it is necessary to increase the steam extraction flow rate to provide more heat to the third feedwater heater 13 to increase the outlet water supply temperature, reduce the temperature difference to enter the temperature matching range, and reduce the irreversible loss of the heat exchange process.

[0027] (2) When the temperature difference is too small and deviates from the temperature matching range (in this embodiment, considering the reasonable area of ​​the heat exchanger, the temperature difference is 100°C ± 10% as the matching range), it is necessary to reduce the steam extraction flow rate, reduce the heat supplied to the third feedwater heater 13 to reduce the outlet water supply temperature, narrow the temperature difference to enter the temperature matching range, reduce the irreversible loss of the heat exchange process, and at the same time avoid wasting the steam extraction flow rate at the inlet of the high pressure turbine 3 and improve the effective output of the high pressure turbine 3.

[0028] In this embodiment, a bypass pipe and a third valve 16 connected in series are provided between the third feedwater heater 13 and the deaerator 11. The extraction steam from the high-pressure turbine 3 is condensed into water after heat exchange and enters the deaerator 11 through the third valve 16. By adjusting the opening of the third valve 16, the flow rate of the condensate is adjusted, thereby adjusting the inlet steam flow rate of the third feedwater heater 13.

[0029] A bypass pipe and a second valve 15 connected in series are provided between the second feedwater heater 10 and the first feedwater heater 9. The steam extracted from the low-pressure turbine 6 is condensed into water after heat exchange and returns to the first feedwater heater 9 through the second valve 15. In this embodiment, similarly, by measuring the temperature difference between the outlet water temperature of the second feedwater heater 10 and the third feedwater heater 13, the opening of the second valve 15 is adjusted to regulate the condensate flow rate, thereby adjusting the steam extraction flow rate of the second feedwater heater 10. This achieves temperature matching for the second-stage water supply heating from the second feedwater heater 10 to the third feedwater heater 13, reducing irreversible losses in the heat exchange process, avoiding wasted steam extraction from the low-pressure turbine 6, and improving the effective output of the low-pressure turbine 6.

[0030] The dehumidifier 4 is also connected to the deaerator 11 via a pipe to provide the heat required for the deaeration process.

[0031] The reheater 5 is also connected to the deaerator 11 via a pipe to provide the heat required for the deaeration process.

[0032] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A nuclear fusion Rankine cycle structure with integrated divertor heat recovery, characterized in that, include: A primary heat collection module and a secondary heat-work conversion module; The heat collection module includes a cladding (17) heat exchange loop for high-grade heat collection and a divertor (18) preheating loop for low-grade heat collection; The heat conversion module includes a steam generator (1), a first valve (2), a high-pressure turbine (3), a dehumidifier (4), a reheater (5), a low-pressure turbine (6), a condenser (7), a first water pump (8), a first feedwater heater (9), a second feedwater heater (10), a deaerator (11), a second water pump (12), a third feedwater heater (13), and a preheating heat exchanger (14), which are connected in sequence by pipes. The preheating heat exchanger (14) uses the heat from the divertor (18) to preheat the secondary side water supply before it enters the steam generator (1); Based on the temperature difference between the outlet water temperature of the third feedwater heater (13) and the temperature of the preheating heat exchanger (14), the inlet steam flow rate of the third feedwater heater (13) is adjusted so that the outlet water temperature of the third feedwater heater (13) matches the temperature of the preheating heat exchanger (14), thereby reducing irreversible losses. The low-pressure turbine (6) is also connected to the first feedwater heater (9) and the second feedwater heater (10) via pipes. The steam temperature at the point where the first feedwater heater (9) is connected to the low-pressure turbine (6) is lower than the steam temperature at the point where the second feedwater heater (10) is connected to the low-pressure turbine (6). A bypass pipe and a third valve (16) connected in series are provided between the third feedwater heater (13) and the deaerator (11). The steam extracted from the high-pressure turbine (3) is condensed into water after heat exchange and enters the deaerator (11) through the third valve (16). The high-pressure turbine (3) is also connected to the steam extraction inlet of the third feedwater heater (13) via a pipeline; The inlet steam flow rate of the third feedwater heater (13) is adjusted by adjusting the opening of the third valve (16); The operating mode where the extraction steam flow rate is determined by the temperature difference is as follows: when the temperature difference is too large and deviates from the temperature matching range by 100°C±10%, the extraction steam flow rate is increased; when the temperature difference is too small and deviates from the temperature matching range by 100°C±10%, the extraction steam flow rate is decreased.

2. The nuclear fusion Rankine cycle structure with integrated divertor heat recovery according to claim 1, characterized in that, The exhaust port of the steam generator (1) is also connected to the reheater (5) through a pipe. The outlet steam of the high-pressure turbine (3) passes through the dehumidifier (4) and is heated by the reheater (5) before entering the low-pressure turbine (6) for the second stage of expansion.

3. The nuclear fusion Rankine cycle structure with integrated divertor heat recovery according to claim 1, characterized in that, After passing through the low-pressure turbine (6), the steam is condensed in the condenser (7) and then sent to the first feedwater heater (9) by the first water pump (8).

4. The nuclear fusion Rankine cycle structure with integrated divertor heat recovery according to claim 1, characterized in that, A bypass pipe and a second valve (15) connected in series are provided between the second feedwater heater (10) and the first feedwater heater (9). The steam extracted from the low-pressure turbine (6) is condensed into water after heat exchange and returns to the first feedwater heater (9) through the second valve (15).

5. The nuclear fusion Rankine cycle structure with integrated divertor heat recovery according to claim 1, characterized in that, The dehumidifier (4) is also connected to the deaerator (11) via a pipe to provide the heat required for the deaeration process.

6. The nuclear fusion Rankine cycle structure with integrated divertor heat recovery according to claim 1, characterized in that, The reheater (5) is also connected to the deaerator (11) via a pipe to provide the heat required for the deaeration process.

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