A method and device for direct heat source reheating of a warm blanket in a fusion reactor

Abstract

This invention discloses a method and apparatus for direct reheating of a heat source from a medium-temperature divertor in a fusion reactor, belonging to the field of fusion reactor energy conversion technology. It directly uses the medium-temperature heat source of the divertor for reheating, avoiding the waste of grade caused by downgrading it for feedwater preheating or driving an organic Rankine cycle. During operation, the divertor directly supplies heat for reheating; during intermittent periods, it switches to heat release reheating from the energy storage device, ensuring continuous reheating throughout the entire cycle. No steam extraction is required, eliminating pressure ratio imbalance and axial thrust imbalance. Only one energy storage device is used for time-sharing, simultaneously meeting the needs of main steam generation and reheating. The apparatus includes a fusion reactor heat source, an energy storage device, and a Rankine cycle power generation system. The fusion reactor heat source comprises a blanket and a divertor; the blanket is used for main steam generation, and the divertor provides reheat heat. The energy storage device stores blanket heat during operation and releases heat during intermittent periods. This invention has advantages such as simplified system structure, significantly improved power generation efficiency, and higher operational reliability.

Description

Technical Field

[0001] This invention belongs to the field of fusion reactor energy conversion technology, specifically relating to a method and apparatus for direct reheating of a heat source in a fusion reactor medium-temperature divertor. Background Technology

[0002] As the mainstream device for magnetic confinement nuclear fusion, the tokamak device exhibits significant pulsed fluctuations in its thermal power output, and its heat source is complex, mainly comprising the blanket, divertor, and vacuum chamber. Currently, the divertor is a low-temperature heat source (around 200°C), but its power level and temperature are continuously increasing with the development of fusion technology. Novel approaches, such as using supercritical carbon dioxide (SCO2) or other working fluids to cool the divertor, can maintain a medium-temperature level (around 300~500°C) at the divertor outlet.

[0003] Regarding the heat utilization of medium-temperature divertors, existing technical solutions have the following significant drawbacks:

[0004] Firstly, some solutions use both the divertor and the vacuum chamber as preheating heat sources for the regenerative system. However, this approach fails to consider the energy value of the increased temperature grade from the divertor, resulting in the downgrading of medium-temperature heat energy for low-temperature preheating and significant waste of energy. Simultaneously, the pulse fluctuations in the divertor's thermal power are directly transmitted to the regenerative system, disturbing the feedwater temperature and consequently causing instability in the main steam parameters at the steam generator outlet, affecting power generation quality and equipment safety.

[0005] Secondly, some solutions involve configuring a separate small energy storage device for the divertor to mitigate its fluctuations. While this approach can alleviate pulse shocks to some extent, it adds an extra energy storage medium loop and heat exchange equipment, significantly increasing system complexity, equipment investment costs, and resulting in poor economic efficiency and system compactness.

[0006] Thirdly, another approach uses the heat from the divertor to preheat the feedwater, with the surplus driving an independent low-temperature organic Rankine cycle for power generation. While this achieves the appearance of cascaded energy utilization, the organic Rankine cycle itself is inefficient, with a large amount of medium-temperature heat energy used only for low-quality power generation, resulting in significant energy conversion losses. Furthermore, adding an independent power generation circuit complicates the system, making control difficult and operational stability poor when coupled with a water Rankine cycle.

[0007] With the development of fusion technology, the outlet temperature and heat load power of divertors are increasing simultaneously. Against this backdrop, how to efficiently utilize the increasingly high-grade heat from divertors, so as to avoid the impact of pulse fluctuations on the main system, fully utilize the work potential of medium-temperature heat energy, and avoid excessive system complexity, is a key problem that urgently needs to be solved. Summary of the Invention

[0008] To address the issues of wasted heat source quality and low utilization efficiency in medium-temperature divertors, the impact of system fluctuations on operational stability, and the high humidity and limited efficiency of the turbine's final stage, this invention provides a method and apparatus for direct reheating of the heat source from a medium-temperature divertor in a fusion reactor. This method directly utilizes the medium-temperature heat source from the divertor for reheating, avoiding the waste caused by downgrading it for feedwater preheating or driving an organic Rankine cycle. During fusion reactor operation, reheating is achieved directly from the divertor; during fusion reactor downtime, reheating is switched to heat release from the energy storage device, ensuring continuous reheating throughout the entire cycle. No steam extraction is required, eliminating pressure ratio imbalance and axial thrust imbalance. Only one energy storage device is needed for time-sharing reuse, simultaneously meeting the needs of main steam generation and reheating. This invention includes a fusion reactor heat source, an energy storage device, and a Rankine cycle power generation system. The fusion reactor heat source includes a blanket and a divertor. The blanket is used for main steam generation, and the divertor provides reheat heat. The energy storage device stores blanket heat during operation and releases heat during off-peak periods. The Rankine cycle power generation system converts steam heat energy into electrical energy and enables steam reheating for work. This invention has advantages such as simplified system structure, significantly improved power generation efficiency, and higher operational reliability.

[0009] To achieve the above objectives, the present invention adopts the following technical solution:

[0010] A method for direct reheating of a fusion reactor's intermediate-temperature divertor heat source includes a fusion reactor operation mode and a fusion reactor off-peak mode. In the fusion reactor operation mode, the divertor directly supplies heat. The cooling working fluid of the blanket is split, with one stream entering a steam generator to release heat and then merging with another working fluid to return to the blanket, while the other stream enters an energy storage device to store heat. At this time, the energy storage device only stores energy and does not release it externally. The superheated steam from the steam generator outlet enters the first turbine to expand and do work. The exhaust steam from the first turbine enters the first reheater, where it is reheated using the heat transferred from the divertor and then continues to do work via the second turbine. In the fusion reactor off-peak mode, the method switches to heat supply from the energy storage device. All the cooling working fluid of the blanket enters the energy storage device to absorb and store energy. The exhaust steam from the first turbine enters the second reheater, where it is reheated using the heat released from the energy storage device and then continues to do work via the second turbine. By switching time-sharing, the direct impact of divertor pulse fluctuations on the reheat steam parameters is avoided, achieving continuous and stable reheating throughout the entire pulse cycle.

[0011] This invention also provides a direct reheat device for a fusion reactor intermediate-temperature divertor heat source, used to realize the above-mentioned direct reheat method for a fusion reactor intermediate-temperature divertor heat source, including a fusion reactor heat source, an energy storage system, and a Rankine cycle power generation system; the fusion reactor heat source includes a blanket and a divertor; the blanket outlet is connected to the inlet of a second three-way valve, one path of the second three-way valve is connected to the hot-side inlet of the steam generator via a third three-way valve, and the other path is connected to the energy storage system; the hot-side outlet of the steam generator is connected to the working fluid from the energy storage system via a second circulating working fluid pump and a fourth three-way valve, and after merging, it is connected to a first three-way valve and a first circulating working fluid pump. Returning to the envelope; the Rankine cycle power generation system includes a steam generator, a first steam turbine, a second steam turbine, a first isolation valve, a second isolation valve, a third isolation valve, and a fourth isolation valve. The cold-side outlet of the steam generator is connected to the first steam turbine. The exhaust port of the first steam turbine is connected to the first isolation valve and the third isolation valve, respectively. The first isolation valve is connected to the cold-side inlet of the first reheater. The third isolation valve is connected to the cold-side inlet of the second reheater. The cold-side outlet of the first reheater is connected to the second isolation valve. The cold-side outlet of the second reheater is connected to the fourth isolation valve. The second and fourth isolation valves are both connected to the inlet of the second steam turbine.

[0012] Beneficial effects:

[0013] 1. This invention uses the heat source of the medium-temperature divertor directly for Rankine cycle reheat, avoiding waste of the medium-temperature heat source; during the intermittent period, it switches to the energy storage device to supply energy, ensuring continuous reheat throughout the entire cycle; there is no need for steam extraction, avoiding pressure ratio imbalance, axial thrust imbalance and low-load final stage blower effect caused by steam extraction.

[0014] 2. This invention only requires one energy storage device, which stores heat during operation and releases heat during intermittent periods. It also undertakes the generation of main steam and reheat energy supply. No additional energy storage is required on the divertor side, simplifying the system structure. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of a direct reheat device for a fusion reactor intermediate temperature divertor heat source according to the present invention.

[0016] The reference numerals in the attached drawings are as follows: 1-cladding; 2-divertor; 3-energy storage device; 4-steam generator; 5-first reheater; 6-second reheater; 7-condenser; 8-first steam turbine; 9-second steam turbine; 10-generator; 11-first circulating working fluid pump; 12-second circulating working fluid pump; 13-energy storage medium pump; 14-feed water pump; 15-first three-way valve; 16-second three-way valve; 17-third three-way valve; 18-fourth three-way valve; 19-reheat valve; 20-first isolation valve; 21-second isolation valve; 22-third isolation valve; 23-fourth isolation valve. Detailed Implementation

[0017] 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.

[0018] like Figure 1 As shown, the present invention provides a direct reheat device for a fusion reactor intermediate temperature divertor heat source, which consists of a fusion reactor system, an energy storage system, and a Rankine cycle power generation system.

[0019] The fusion reactor system is divided into a blanket system and a divertor system, each employing different cooling media loops and operating within different temperature ranges. The blanket system includes blanket 1, a second three-way valve 16, a third three-way valve 17, a steam generator 4, a second circulating working fluid pump 12, a fourth three-way valve 18, a first three-way valve 15, and a first circulating working fluid pump 11. The divertor system includes divertor 2 and a first reheater 5.

[0020] The energy storage system includes an energy storage device 3, an energy storage medium pump 13, a reheat valve 19, and a second reheater 6.

[0021] The Rankine cycle power generation system includes a steam generator 4, a first steam turbine 8, a second steam turbine 9, a generator 10, a condenser 7, a feedwater pump 14, a first reheater 5, a second reheater 6, a first isolation valve 20, a second isolation valve 21, a third isolation valve 22, and a fourth isolation valve 23.

[0022] The outlet of cladding 1 is connected to the inlet of the second three-way valve 16. The second three-way valve 16 has two outlets: one connected to the energy storage device 3, and the other connected to one inlet of the third three-way valve 17. The outlet of the third three-way valve 17 is connected to the hot-side inlet of the steam generator 4. The hot-side outlet of the steam generator 4 is connected to the inlet of the second circulating working fluid pump 12. The outlet of the second circulating working fluid pump 12 is connected to the inlet of the fourth three-way valve 18. One outlet of the fourth three-way valve 18 is connected to the energy storage device 3, and the other outlet is connected to one inlet of the first three-way valve 15. The outlet of the first three-way valve 15 is connected to the inlet of the first circulating working fluid pump 11, and the outlet of the first circulating working fluid pump 11 is connected to the inlet of the return cladding 1. Both one inlet of the third three-way valve 17 and one inlet of the first three-way valve 15 are connected to the energy storage device 3. The energy from the divertor 2 is transferred to the first reheater 5. The energy storage device 3 is sequentially connected to the energy storage medium pump 13, the reheat valve 19, and the second reheater 6. The cold-side outlet of steam generator 4 is superheated steam, which enters the first steam turbine 8 for expansion and work. The outlet of the first steam turbine 8 is split: one path passes sequentially through the first isolation valve 20, the cold side of the first reheater 5, and the second isolation valve 21, before entering the second steam turbine 9; the other path passes sequentially through the third isolation valve 22, the cold side of the second reheater 6, and the fourth isolation valve 23, before entering the second steam turbine 9. The first steam turbine 8, the second steam turbine 9, and the generator 10 are coaxially connected, driving the generator 10 to generate electricity. The exhaust steam from the second steam turbine 9 enters the condenser 7 for condensation. The condensate is pressurized by the feedwater pump 14 and returned to the cold-side inlet of the steam generator 4, completing the thermodynamic cycle.

[0023] Based on the above-mentioned direct reheat device for the intermediate-temperature divertor heat source in fusion reactors, this invention provides a method for direct reheating of the intermediate-temperature divertor heat source in fusion reactors. The heat from the intermediate-temperature divertor is used for the reheating of the turbine exhaust steam. During the operation of the fusion reactor, the heat is directly supplied by the divertor. During the intermittent operation of the fusion reactor, the heat is switched to be supplied by the energy storage device. By switching in a time-sharing manner, the direct influence of divertor pulse fluctuations on the reheat steam parameters is avoided, and continuous and stable reheating throughout the entire pulse cycle is achieved.

[0024] Specifically, the direct reheating method for a fusion reactor intermediate-temperature divertor heat source according to the present invention has two operating modes, which are switched by a valve group:

[0025] a. Fusion reactor operation mode:

[0026] The first circulating working fluid pump 11 and the second circulating working fluid pump 12 are started. The cooling working fluid of the cladding 1 is split through the second three-way valve 16. Part of it enters the steam generator 4 to release heat through the third three-way valve 17, and the other part enters the energy storage device 3 to store heat. The working fluid at the hot side outlet of the steam generator 4, after passing through the second circulating working fluid pump 12 and the fourth three-way valve 18, merges with the working fluid flowing out of the energy storage device 3 and returns to the cladding 1 through the first circulating working fluid pump 11. During this process, the energy storage medium pump 13 and the reheat valve 19 remain closed, and the energy storage device 3 only stores heat and does not release heat.

[0027] Superheated steam from the outlet of steam generator 4 enters the first steam turbine 8 to do work. The first isolation valve 20 and the second isolation valve 21 are opened, and the third isolation valve 22 and the fourth isolation valve 23 are closed. The exhaust steam from the first steam turbine 8 is reheated by the heat from the first reheater 5 and the diverter 2, and then enters the second steam turbine 9 to continue doing work.

[0028] b. Fusion reactor off-peak mode:

[0029] The first circulating working fluid pump 11 is shut down, and the energy storage medium pump 13 and reheat valve 19 are opened. All the cladding cooling working fluid enters the energy storage device 3 through the fourth three-way valve 18 to absorb and store heat. The first isolation valve 20 and the second isolation valve 21 are closed, and the third isolation valve 22 and the fourth isolation valve 23 are opened. The exhaust steam from the first turbine 8 is reheated by the energy storage device 3 via the second reheater 6 and then enters the second turbine 9 to continue performing work. During the intermittent period, both the cladding 1 and the divertor 2 are isolated. The system relies entirely on the energy storage device 3 to simultaneously meet the main steam generation and reheat requirements, ensuring continuous and stable operation of the Rankine cycle throughout the entire pulse cycle.

[0030] The above method is illustrated using a two-stage steam turbine configuration as an example, and is equally applicable to a three-stage configuration with a high-pressure cylinder, an intermediate-pressure cylinder, and a low-pressure cylinder. In the three-stage configuration, the first reheater 5 and the second reheater 6 are connected in parallel between the exhaust outlet of the intermediate-pressure cylinder and the inlet of the low-pressure cylinder. During operation, the exhaust steam of the intermediate-pressure cylinder is heated by the divertor 2, and during the intermittent period, the heating is switched to the energy storage device 3. The valve switching logic is the same as that of the two-stage configuration.

[0031] As one embodiment, taking an ultra-high pressure reheat unit as an example, the cladding cooling medium uses lithium-lead and helium, with an outlet temperature of 520-570℃; the divertor cooling medium uses supercritical carbon dioxide, with an outlet temperature of 480-530℃; the energy storage device uses either Solar Salt (binary salt) or Hitec (ternary salt) as the energy storage medium, with a heat release temperature of 500-540℃. Within the above temperature range, both the divertor and the energy storage device have the ability to reheat the exhaust steam from the first turbine to 450-500℃. The reheat steam temperature can remain consistent when switching energy supply between operating and off-peak periods, meeting the steam inlet parameter requirements of the second turbine.

[0032] After adopting this method, the system's cycle thermal efficiency can reach 38%~40%; the dryness fraction of the last-stage steam in the second turbine after reheating increases from approximately 0.85 to over 0.92, significantly reducing wet steam loss and the risk of last-stage blade erosion. Compared to using the intermediate-temperature heat from this portion of the divertor for feedwater preheating or driving an organic Rankine cycle, this invention can additionally increase net power generation by approximately 50~70MW (taking a fusion reactor with a thermal power of 2000MW as an example) under the same divertor thermal power, equivalent to an annual power generation increase of approximately 400~560GWh.

[0033] Furthermore, compared to the steam extraction reheat method conventionally used in pressurized water reactor nuclear power plants (MSR), where the heat source is drawn from the main steam, the reheat temperature of the MSR is typically only 250-280°C. Its main function is to reduce the humidity of the final-stage steam to protect the blades, with limited contribution to improving cycle efficiency. In contrast, this invention directly utilizes the medium-temperature heat of 480-530°C at the divertor outlet to reheat the exhaust steam from the first turbine to a higher level of 450-500°C. This effectively controls the humidity of the final stage while significantly increasing the average endothermic temperature of the cycle, thus achieving a significant efficiency gain. Simultaneously, this invention eliminates the need for steam extraction from the main steam pipeline, fundamentally avoiding disturbances to the main steam parameters and the impact on the turbine's axial thrust. The system piping and control logic are simplified, and the reheat temperature stability is superior during fusion reactor pulse intermittent switching.

[0034] In summary, this invention achieves continuous reheat supply throughout the entire pulse cycle by setting up two reheaters connected in parallel between the exhaust port of the first turbine and the inlet of the second turbine. During operation, the reheat heat is provided by the divertor, and during off-peak periods, the energy storage device provides the energy. The energy storage device only stores blanket heat during operation and does not participate in heat release; during off-peak periods, it switches to heat release mode, simultaneously handling both main steam generation and reheat energy supply. The valve group control logic is based on the switching of operating phases, and the same energy storage device is time-sharing multiplexed.

[0035] 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 direct reheating of a heat source in a fusion reactor intermediate-temperature divertor, characterized in that, The system includes a fusion reactor operation mode and a fusion reactor off-peak mode. In the fusion reactor operation mode, the divertor provides direct heating. The cooling medium in the blanket is split, with one stream entering the steam generator to release heat and then merging with another stream of working medium before returning to the blanket. The other stream enters the energy storage device to store heat, where it only stores energy and does not release it. The superheated steam from the steam generator outlet enters the first turbine to expand and perform work. The exhaust steam from the first turbine enters the first reheater, where it is reheated using the heat transferred from the divertor and then continues to perform work in the second turbine. In the fusion reactor off-peak mode, the system switches to a system where the energy storage device provides heating. All the cooling medium in the blanket enters the energy storage device to absorb and store energy. The exhaust steam from the first turbine enters the second reheater, where it is reheated using the heat released from the energy storage device and then continues to perform work in the second turbine. By switching between time-sharing modes, the direct impact of divertor pulse fluctuations on the reheat steam parameters is avoided, achieving continuous and stable reheating throughout the entire pulse cycle.

2. A direct reheat device for a heat source of a fusion reactor intermediate-temperature divertor, used to implement the direct reheat method for a heat source of a fusion reactor intermediate-temperature divertor as described in claim 1, characterized in that, The system includes a fusion reactor heat source, an energy storage system, and a Rankine cycle power generation system. The fusion reactor heat source includes a blanket and a divertor. The blanket outlet is connected to the inlet of a second three-way valve. One path of the second three-way valve is connected to the hot-side inlet of the steam generator via a third three-way valve, and the other path is connected to the energy storage system. The hot-side outlet of the steam generator is connected to the working fluid from the energy storage system via a second circulating working fluid pump and a fourth three-way valve. After merging, the working fluid returns to the blanket via a first three-way valve and a first circulating working fluid pump. The Rankine cycle power generation system includes a steam generator, a first turbine, a second turbine, a first isolation valve, a second isolation valve, a third isolation valve, and a fourth isolation valve. The cold-side outlet of the steam generator is connected to the first turbine. The exhaust port of the first turbine is connected to the first isolation valve and the third isolation valve. The first isolation valve is connected to the cold-side inlet of the first reheater. The third isolation valve is connected to the cold-side inlet of the second reheater. The cold-side outlet of the first reheater is connected to the second isolation valve. The cold-side outlet of the second reheater is connected to the fourth isolation valve. The second and fourth isolation valves are connected to the inlet of the second turbine.

3. The direct reheat device for a heat source of a fusion reactor intermediate-temperature divertor according to claim 2, characterized in that, The Rankine cycle power generation system also includes a condenser and a feedwater pump. The exhaust steam from the second turbine enters the condenser for condensation, and the condensate is pressurized by the feedwater pump and returned to the cold side inlet of the steam generator. The energy storage system includes an energy storage device, an energy storage medium pump, a reheat valve, and a second reheater.

4. The direct reheat device for a fusion reactor intermediate-temperature divertor heat source according to claim 2, characterized in that, The first reheater is connected to a divertor on its hot side, and the second reheater is connected to an energy storage medium pump and a reheat valve on its hot side.

5. A direct reheat device for a heat source of a fusion reactor intermediate-temperature divertor according to claim 2, characterized in that, The switching between the fusion reactor's operational and off-peak modes is achieved through valve group switching. In the operational mode, the first and second circulating working fluid pumps are activated. The cooling working fluid in the blanket is split at the second three-way valve. One stream enters the steam generator through the third three-way valve to release heat and then merges with the other working fluid before returning to the blanket. The other stream enters the energy storage device to store heat. The superheated steam from the steam generator outlet enters the first turbine to expand and perform work. The exhaust steam from the first turbine enters the first reheater, where it is reheated using the heat transferred from the divertor and then continues to perform work in the second turbine. In the off-peak mode, the first circulating working fluid pump is shut down, and the energy storage medium pump and reheat valve are activated. All the working fluid in the blanket cooling circuit enters the energy storage device to absorb and store energy. The exhaust steam from the first turbine enters the second reheater, where it is reheated using the heat released from the energy storage device and then continues to perform work in the second turbine.

6. A direct reheat device for a heat source of a fusion reactor intermediate-temperature divertor according to claim 2, characterized in that, During the fusion reactor's operation, both the energy storage medium pump and the reheat valve are closed, and the energy storage device does not supply power to the Rankine cycle power generation system.

7. A direct reheat device for a fusion reactor intermediate-temperature divertor heat source according to claim 2, characterized in that, In the intermittent mode of the fusion reactor, the cooling working fluid of the blanket no longer passes through the first three-way valve, the first circulating working fluid pump and the blanket, but instead enters the energy storage device through the fourth three-way valve to absorb the stored energy.

8. A direct reheat device for a heat source of a fusion reactor intermediate-temperature divertor according to claim 2, characterized in that, During the fusion reactor operation mode, the first and second isolation valves are open, while the third and fourth isolation valves are closed, allowing the exhaust steam from the first turbine to flow through the first reheater.

9. A direct reheat device for a heat source of a fusion reactor intermediate-temperature divertor according to claim 2, characterized in that, In the fusion reactor intermittent mode, the first and second isolation valves are closed, while the third and fourth isolation valves are opened, allowing the exhaust steam from the first turbine to flow through the second reheater.

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