Energy gradient utilization steam Rankine cycle power generation system and method for nuclear fusion

Abstract

The invention provides an energy gradient utilization steam Rankine cycle power generation system and method for nuclear fusion, and belongs to the field of nuclear fusion energy conversion and utilization. Different temperature heat of a cladding, a divertor and a vacuum chamber is guided into a high-temperature independent heat storage loop, a medium-temperature independent heat storage loop and a low-temperature independent heat storage loop respectively, an operation section stores heat, and a pause section releases heat; feed water is heated step by step through a multi-stage preheater, an evaporator and a superheater according to the sequence of low temperature, medium temperature and high temperature, and superheated steam of 550 DEG C is formed to continuously drive a turbine to generate power. Decoupling of intermittent output of the fusion reactor and continuous operation of the power generation system is achieved, steam extraction of a steam turbine is omitted, the structure is simplified, and the energy utilization rate and the circulation efficiency are improved.

Description

Technical Field

[0001] This invention belongs to the field of nuclear fusion energy conversion and utilization, specifically relating to a steam Rankine cycle power generation system and method for the energy cascade utilization of nuclear fusion. Background Technology

[0002] With global economic development and population growth, energy demand continues to rise. Traditional fossil fuels face problems such as resource depletion and environmental pollution, making the development of clean and sustainable new energy sources an urgent priority. Nuclear fusion energy, due to its outstanding advantages such as high energy density, abundant fuel resources (the main fuel, deuterium, can be extracted from seawater, and tritium can be produced through neutron breeding of lithium), high safety, and almost no greenhouse gas emissions, is considered an important way to completely solve the energy problem in the future and is the ultimate energy source for humankind to develop and utilize in the future.

[0003] Currently, nuclear fusion energy has broad development prospects and is at a turning point in its development, moving from scientific research to engineering practice and then to commercial application. However, fusion reactor power generation still faces many technical challenges, especially the energy conversion problem. On the one hand, fusion reactors cannot operate for extended periods. Common operating modes, such as those of EU commercial reactors, involve 2.0 hours of operation followed by a 10-minute pause. This intermittent energy output during operation makes it impossible for the turbine generator to guarantee continuous and stable output, resulting in poor power generation quality and large fluctuations in secondary loop steam parameters, which adversely affect the stability of power generation equipment and the power grid. On the other hand, the temperature range of its output energy is relatively large (130-600℃), which differs from existing nuclear and thermal power generation technologies. Efficiently utilizing its output energy and converting it into electricity is a challenge in the practical application of fusion reactors.

[0004] Current research on nuclear fusion device power generation systems is limited by the fact that the simple Rankine cycle cannot fully utilize the energy of the nuclear fusion device, resulting in excessive waste of energy below 300°C. Furthermore, the simple cycle mainly refers to the characteristics of pressurized water reactor cycles, using a single main evaporator to directly generate saturated or superheated steam, which poses significant safety issues. This is because the hot-side medium temperature of the main evaporator in a pressurized water reactor is 325°C, while the cold-side medium temperature is 285°C, resulting in a small temperature difference. However, the hot-side medium temperature in a fusion reactor can reach 500-600°C. Directly heating the feedwater (generally at 240-260°C) to saturated or superheated steam results in a large temperature difference between the two sides, and the excessive temperature rise of the medium can lead to severe thermal stress, affecting the safety of the evaporator.

[0005] Chinese patent applications CN202110147915.5 (A molten salt energy storage decoupled power generation system and power generation method for fusion reactors), CN202110149331.1 (A molten salt energy storage coupled power generation system and power generation method for fusion reactors), and CN202110147551.0 (An oil energy storage coupled power generation system and power generation method for fusion reactors) all utilize only the high-temperature energy output from the fusion reactor blanket, accounting for approximately 80%. Furthermore, the power generation system directly references pressurized water reactors, employing a single main evaporator. The main steam temperature is generally limited to below 325℃, resulting in low cycle efficiency, limited to around 30%.

[0006] Currently, both domestic and international fusion reactors are in the experimental stage, focusing on the principles of the fusion process and related equipment research. Research on the conversion of fusion energy into electrical energy is still in the conceptual stage. The key to developing fusion experimental reactors into engineering reactors is solving the problem of energy conversion in fusion reactors. There is an urgent need for a safe and reliable power generation system that can simultaneously solve the problem of intermittent power generation in fusion reactors, fully utilize the heat sources at different temperatures in fusion reactors, and improve energy utilization and cycle efficiency for this field. Summary of the Invention

[0007] To overcome the shortcomings and deficiencies of existing technologies, this invention provides a steam Rankine cycle power generation system and method for energy cascade utilization in nuclear fusion. This system converts fusion energy generated by a fusion reactor into electrical energy, resolving the contradiction between the intermittent operation of the fusion reactor and stable power generation, reducing the impact of load fluctuations on turbine blades, and extending the service life of the turbine unit. Simultaneously, it utilizes the principle of energy cascade utilization to fully leverage the energy output from the fusion reactor across a wide temperature range (130-600℃), improving the utilization rate of fusion energy. Furthermore, by matching the heat from different temperature ranges of the fusion reactor with the heat required in the steam Rankine cycle, it achieves energy cascade utilization at different temperatures and pressures. Using a step-by-step heating and two-stage pressurization method, the steam temperature is raised to approximately 550℃, significantly improving the efficiency of the Rankine cycle. This also solves the safety issues caused by excessive temperature differences in the main evaporator, reduces the pressure on both sides of the intermediate-temperature preheater, lowers its manufacturing cost, and improves operational safety.

[0008] To achieve the above objectives, the present invention adopts the following technical solution:

[0009] A steam Rankine cycle power generation system for nuclear fusion energy cascade utilization includes:

[0010] The high-temperature energy extraction loop is connected to the outlet or inlet of the fusion reactor blanket and is used to extract the medium at 500-600℃.

[0011] The high-temperature energy storage and utilization circuit is coupled to the high-temperature energy output circuit via a high-temperature heat storage heat exchanger, and is equipped with a high-temperature hot tank, a high-temperature cold tank, and a superheater, an evaporator, and a high-temperature preheater connected in series.

[0012] The intermediate-temperature energy extraction loop is connected to the outlet or inlet of the fusion reactor divertor.

[0013] The medium-temperature energy storage and utilization circuit is coupled to the medium-temperature energy output circuit via a medium-temperature heat storage heat exchanger, and is equipped with a medium-temperature hot tank, a medium-temperature cold tank, and at least two stages of medium-temperature preheaters connected in series.

[0014] The cryogenic energy extraction loop is connected to the outlet or inlet of the fusion reactor vacuum chamber.

[0015] The low-temperature energy storage and utilization circuit is coupled to the low-temperature energy output circuit via a low-temperature thermal heat exchanger, and is equipped with a low-temperature hot tank, a low-temperature cold tank, and at least two stages of low-temperature preheaters connected in series.

[0016] The energy cascade utilization power generation circuit is equipped with a condenser, condensate pump, primary feedwater pump, secondary feedwater pump, and high-pressure cylinder, intermediate-pressure cylinder, and low-pressure cylinder of the steam turbine. The feedwater absorbs heat in sequence through the low-temperature preheater, intermediate-temperature preheater, high-temperature preheater, evaporator, and superheater before entering the steam turbine to do work.

[0017] Each storage and utilization circuit is independent of the others and continuously supplies energy to the energy cascade utilization power generation circuit during the operation or shutdown of the fusion reactor.

[0018] Furthermore, the heat-conducting medium of the high-temperature energy extraction circuit is helium, supercritical carbon dioxide, or lithium-lead alloy, and the heat storage medium of the high-temperature energy storage and utilization circuit is high-melting-point molten salt; the heat-conducting medium of the medium-temperature energy extraction circuit is helium, supercritical carbon dioxide, or high-pressure water, and the heat storage medium of the medium-temperature energy storage and utilization circuit is low-melting-point molten salt or heat-conducting oil; the heat-conducting medium of the low-temperature energy extraction circuit is high-pressure water, and the heat storage medium of the low-temperature energy storage and utilization circuit is heat-conducting oil.

[0019] Furthermore, the high-temperature energy storage and utilization circuit is equipped with a unidirectional molten salt flow channel, which flows sequentially through the high-temperature hot tank outlet, the third pump, the superheater hot side, the evaporator hot side, the high-temperature preheater hot side, the third valve, and the high-temperature cold tank inlet.

[0020] Furthermore, the medium-temperature energy storage and utilization circuit is equipped with a unidirectional molten salt or heat transfer oil flow channel, which flows sequentially through the outlet of the medium-temperature hot tank, the sixth pump, the hot side of the first-stage medium-temperature preheater, the hot side of the second-stage medium-temperature preheater, the hot side of the third-stage medium-temperature preheater, the sixth valve, and the inlet of the medium-temperature cold tank.

[0021] Furthermore, the cryogenic energy storage and utilization circuit is equipped with a unidirectional heat-conducting oil flow channel, which flows sequentially through the cryogenic hot tank outlet, the ninth pump, the hot side of the first-stage cryogenic preheater, the hot side of the second-stage cryogenic preheater, the hot side of the third-stage cryogenic preheater, the ninth valve, and the cryogenic cold tank inlet.

[0022] Furthermore, the energy cascade utilizes the reheater hot-side inlet of the power generation circuit to connect with the high-temperature hot tank outlet, the cold-side inlet to connect with the high-pressure cylinder outlet, and the cold-side outlet to connect with the intermediate-pressure cylinder inlet.

[0023] Furthermore, the medium-temperature preheater has three stages, the low-temperature preheater has three stages, and none of the preheaters has a turbine extraction port.

[0024] This invention also provides a method for generating electricity using a steam Rankine cycle power generation system that utilizes the energy cascade of nuclear fusion, comprising:

[0025] Step 1: During the operation of the fusion reactor, the high-temperature heat of the blanket, the medium-temperature heat of the divertor, and the low-temperature heat of the vacuum chamber are stored in the corresponding high-temperature heat tank, medium-temperature heat tank, and low-temperature heat tank through independent high-temperature energy export circuit, medium-temperature energy export circuit, and low-temperature energy export circuit, respectively.

[0026] Step 2: During the operation of the fusion reactor and the subsequent shutdown period, the heat from the low-temperature hot tank, the medium-temperature hot tank, and the high-temperature hot tank is released in sequence in the order of low temperature, medium temperature, and high temperature to continuously heat the feedwater and generate superheated steam, so that the steam turbine can continuously do work.

[0027] Furthermore, in step 1, the molten salt in the high-temperature hot tank is divided into two paths. One path flows through the reheater to heat the exhaust steam from the high-pressure cylinder of the turbine, while the other path flows sequentially through the reheater, evaporator, and high-temperature preheater to complete feedwater evaporation and primary heating. The molten salt or heat transfer oil in the medium-temperature hot tank flows sequentially through two or three stages of medium-temperature preheaters to raise the temperature of the feedwater after passing through the secondary feedwater pump, thus completing secondary heating. The heat transfer oil in the low-temperature hot tank flows sequentially through two or three stages of low-temperature preheaters to raise the temperature of the condensate, thus completing tertiary heating. Primary heating, secondary heating, and tertiary heating are completed in series in the same feedwater process, and there is no turbine steam extraction throughout the entire process.

[0028] Furthermore, during the fusion reactor shutdown period, the first pump and first valve of the high-temperature energy extraction loop, the fourth pump and fourth valve of the medium-temperature energy extraction loop, and the seventh pump and seventh valve of the low-temperature energy extraction loop are shut down, ceasing the supply of heat to the high-temperature, medium-temperature, and low-temperature hot tanks; the third pump at the outlet of the high-temperature hot tank, the sixth pump at the outlet of the medium-temperature hot tank, the ninth pump at the outlet of the low-temperature hot tank, and all preheaters, evaporators, superheaters, reheaters, turbines, condensers, and feedwater pumps are kept running, so that the molten salt in the high-temperature hot tank continues to flow sequentially through the reheater, superheater, evaporator, and high-temperature preheater, the molten salt or heat transfer oil in the medium-temperature hot tank continues to flow sequentially through each stage of the medium-temperature preheater, and the heat transfer oil in the low-temperature hot tank continues to flow sequentially through each stage of the low-temperature preheater, and the feedwater continuously absorbs heat and generates 550°C superheated steam, ensuring that the turbine continues to supply steam and perform work during the fusion reactor shutdown period.

[0029] Beneficial effects:

[0030] (1) The high, medium and low temperature energy output during the operation of the nuclear fusion device is stored separately and continuously utilized during the operation and shutdown time of the fusion device, which overcomes the intermittent problem of the energy output of the fusion device and reduces the fluctuation impact on the steam turbine power generation system.

[0031] (2) All the energy output by the fusion device (130-600℃) is utilized, which improves the utilization rate of the energy output by the fusion device.

[0032] (3) The configuration of evaporator and superheater can make full use of high temperature heat source and raise steam temperature to about 550°C, which can greatly improve the power generation efficiency of steam Rankine cycle.

[0033] (4) The configuration of the evaporator and superheater can fully match the operating temperature range of the cold and hot side media, avoid the excessive temperature difference between the two sides caused by using one main evaporator, and reduce the damage to the equipment caused by excessive temperature stress.

[0034] (5) The use of medium-temperature heat source (200-300℃) reduces the use of high-pressure heaters in the original thermal cycle and eliminates the need to extract air from the high-pressure cylinder of the steam turbine to heat the feedwater; it reduces the high-pressure and medium-pressure cylinder extraction systems of at least two steam turbines and improves the utilization efficiency of steam.

[0035] (6) The use of low-temperature heat source (130-200℃) reduces the use of low-pressure heaters in the original thermodynamic cycle and eliminates the need to extract air from the low-pressure cylinder of the steam turbine to heat the feedwater; it reduces the low-pressure cylinder extraction system of at least two steam turbines, further improving the utilization efficiency of steam.

[0036] (7) The present invention is equipped with two-stage feedwater pumps to pressurize the feedwater twice. The pressure of the water in the intermediate temperature preheater does not need to reach the rated pressure required by the turbine unit and can be maintained at a lower pressure level (its outlet can be pressurized to the high pressure required by the turbine unit by the second-stage feedwater pump). The medium on the other side can also be at a lower pressure because the heat source of the fusion reactor divertor is used to replace the original high-pressure cylinder and low-pressure cylinder extraction. Therefore, the pressure on both sides of the intermediate temperature preheater can be reduced, reducing the manufacturing cost and safety hazards caused by excessive pressure in the intermediate temperature preheater. Attached Figure Description

[0037] Figure 1 This is a schematic diagram of a steam Rankine cycle power generation system for nuclear fusion energy cascade utilization, as described in Embodiment 1 of the present invention.

[0038] Figure 2 This is a schematic diagram of a steam Rankine cycle power generation system for nuclear fusion energy cascade utilization, as described in Embodiment 2 of the present invention.

[0039] The attached diagram is labeled as follows: 1-High-temperature energy extraction circuit; 11-First pump; 12-High-temperature heat storage exchanger; 13-First valve; 2-High-temperature energy storage and utilization circuit; 21-High-temperature hot tank; 22-High-temperature cold tank; 23-Second pump; 24-Second valve; 25-Third pump; 26-Superheater; 27-Evaporator; 28-High-temperature preheater; 29-Third valve; 3-Medium-temperature energy extraction circuit; 31-Fourth pump; 32-Medium-temperature heat storage exchanger; 33-Fourth valve; 4-Medium-temperature energy storage and utilization circuit; 41-Medium-temperature hot tank; 42-Medium-temperature cold tank; 43-Fifth pump; 44-Fifth valve; 45-Sixth pump; 46-Sixth valve; 47-First-stage medium-temperature preheater; 48-Second-stage medium-temperature preheater; 49-Third-stage medium-temperature preheater; 5-Low-temperature energy extraction loop; 51-Seventh pump; 52-Low-temperature heat storage exchanger; 53-Seventh valve; 6-Low-temperature energy storage and utilization loop; 61-Low-temperature hot tank; 62-Low-temperature cold tank; 63-Eighth pump; 64-Eighth valve; 65-Ninth pump; 66-Ninth valve; 67-First-stage cryogenic preheater; 68-Second-stage cryogenic preheater; 69-Third-stage cryogenic preheater; 7-Energy cascade utilization power generation circuit; 71-First-stage feedwater pump; 72-High-pressure cylinder of steam turbine; 73-Intermediate-pressure cylinder of steam turbine; 74-Low-pressure cylinder of steam turbine; 75-Reheater; 76-Regulating valve; 77-Condenser; 78-Condensate pump; 79-Tenth valve; 710-Circulating pump; 711-Cooling tower; 712-Eleventh valve; 713-Second-stage feedwater pump. Detailed Implementation

[0040] 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.

[0041] Example 1:

[0042] like Figure 1 As shown, the present invention provides a steam Rankine cycle power generation system for energy cascade utilization in nuclear fusion, including a high-temperature energy extraction circuit 1, a high-temperature energy storage and utilization circuit 2, a medium-temperature energy extraction circuit 3, a medium-temperature energy storage and utilization circuit 4, a low-temperature energy extraction circuit 5, a low-temperature energy storage and utilization circuit 6, and an energy cascade utilization power generation circuit 7.

[0043] High-temperature energy extraction loop 1 is directly connected to the fusion reactor blanket; medium-temperature energy extraction loop 3 is directly connected to the fusion reactor divertor; and low-temperature energy extraction loop 5 is directly connected to the fusion reactor vacuum chamber. High-temperature energy extraction loop 1, medium-temperature energy extraction loop 3, and low-temperature energy extraction loop 5 are independent of each other. High-temperature energy extraction loop 1 is connected to high-temperature energy storage and utilization loop 2 via high-temperature thermal energy exchanger 12; medium-temperature energy extraction loop 3 is connected to medium-temperature energy storage and utilization loop 4 via medium-temperature thermal energy exchanger 32; and low-temperature energy extraction loop 5 is connected to low-temperature energy storage and utilization loop 6 via low-temperature thermal energy exchanger 52. The high-temperature energy storage and utilization circuit 2 is connected to the energy cascade utilization power generation circuit 7 through the superheater 26, the evaporator 27, and the high-temperature preheater 28; the medium-temperature energy storage and utilization circuit 4 is connected to the energy cascade utilization power generation circuit 7 through the first-stage medium-temperature preheater 47 and the second-stage medium-temperature preheater 48; the low-temperature energy storage and utilization circuit 6 is connected to the energy cascade utilization power generation circuit 7 through the first-stage low-temperature preheater 67 and the second-stage low-temperature preheater 68.

[0044] The high-temperature energy extraction loop 1 includes a first pump 11, a hot side of a high-temperature thermal storage heat exchanger 12, a first valve 13, and pipelines. It uses media such as helium, supercritical carbon dioxide, and lithium-lead to extract heat from the blanket and breeding blanket. The inlet of the first pump 11 is connected to the outlet of the fusion reactor blanket, the outlet of the first pump 11 is connected to the hot side inlet of the high-temperature thermal storage heat exchanger 12, the hot side outlet of the high-temperature thermal storage heat exchanger 12 is connected to the inlet of the first valve 13, and the outlet of the first valve 13 is connected to the inlet of the fusion reactor blanket.

[0045] The high-temperature energy storage and utilization circuit 2 includes a high-temperature cold tank 22, a second pump 23, the cold side of a high-temperature thermal storage heat exchanger 12, a second valve 24, a high-temperature hot tank 21, a third pump 25, the hot side of a superheater 26, the hot side of an evaporator 27, the hot side of a high-temperature preheater 28, a third valve 29, and piping. The outlet of the high-temperature cold tank 22 is connected to the inlet of the second pump 23, the outlet of the second pump 23 is connected to the cold side inlet of the high-temperature thermal storage heat exchanger 12, the cold side outlet of the high-temperature thermal storage heat exchanger 12 is connected to the inlet of the second valve 24, and the outlet of the second valve 24 is connected to the inlet of the high-temperature hot tank 21. The outlet of the high-temperature hot tank 21 is connected to the inlet of the third pump 25. The outlet of the third pump 25 is connected to the hot-side inlet of the superheater 26. The hot-side outlet of the superheater 26 is connected to the hot-side inlet of the evaporator 27. The hot-side outlet of the evaporator 27 is connected to the hot-side inlet of the high-temperature preheater 28. The hot-side outlet of the high-temperature preheater 28 is connected to the inlet of the third valve 29. The outlet of the third valve 29 is connected to the inlet of the high-temperature cold tank 22.

[0046] Heat is absorbed by a medium such as high-melting-point molten salt through a high-temperature heat exchanger 12 and stored in a high-temperature hot tank 21. The high-temperature molten salt transfers heat to the water in the energy cascade utilization power generation circuit through a superheater 26, an evaporator 27, and a high-temperature preheater 28 for evaporation and superheating of the feedwater.

[0047] The intermediate-temperature energy extraction loop 3 includes a fourth pump 31, the hot side of an intermediate-temperature thermal storage heat exchanger 32, a fourth valve 33, and piping. It uses media such as helium, supercritical carbon dioxide, and high-pressure water to extract heat from the divertor. The inlet of the fourth pump 31 is connected to the outlet of the fusion reactor divertor, the outlet of the fourth pump 31 is connected to the hot-side inlet of the intermediate-temperature thermal storage heat exchanger 32, the hot-side outlet of the intermediate-temperature thermal storage heat exchanger 32 is connected to the inlet of the fourth valve 33, and the outlet of the fourth valve 33 is connected to the inlet of the fusion reactor divertor.

[0048] The intermediate-temperature energy storage and utilization circuit 4 includes an intermediate-temperature cold tank 42, a fifth pump 43, the cold side of an intermediate-temperature heat exchanger 32, a fifth valve 44, an intermediate-temperature hot tank 41, a sixth pump 45, the hot side of a primary intermediate-temperature preheater 47, the hot side of a secondary intermediate-temperature preheater 48, a sixth valve 46, and piping. The outlet of the intermediate-temperature cold tank 42 is connected to the inlet of the fifth pump 43, the outlet of the fifth pump 43 is connected to the cold-side inlet of the intermediate-temperature heat exchanger 32, the cold-side outlet of the intermediate-temperature heat exchanger 32 is connected to the inlet of the fifth valve 44, and the outlet of the fifth valve 44 is connected to the inlet of the intermediate-temperature hot tank 41. The outlet of the intermediate-temperature heat tank 41 is connected to the inlet of the sixth pump 45. The outlet of the sixth pump 45 is connected to the hot-side inlet of the first-stage intermediate-temperature preheater 47. The hot-side outlet of the first-stage intermediate-temperature preheater 47 is connected to the hot-side inlet of the second-stage intermediate-temperature preheater 48. The hot-side outlet of the second-stage intermediate-temperature preheater 48 is connected to the inlet of the sixth valve 46. The outlet of the sixth valve 46 is connected to the inlet of the intermediate-temperature cold tank 42. Low-melting-point molten salt, heat transfer oil, or other media absorb heat through the intermediate-temperature heat exchanger 32 and store it in the intermediate-temperature heat tank 41. The media in the intermediate-temperature heat tank 41 transfers heat to the water in the energy cascade utilization power generation circuit through the first-stage intermediate-temperature preheater 47 and the second-stage intermediate-temperature preheater 48.

[0049] The cryogenic energy extraction loop 5 includes a seventh pump 51, the hot side of a cryogenic thermal storage heat exchanger 52, a seventh valve 53, and piping. It uses high-pressure water or other media to extract heat from the vacuum chamber. The inlet of the seventh pump 51 is connected to the outlet of the fusion reactor vacuum chamber, the outlet of the seventh pump 51 is connected to the hot side inlet of the cryogenic thermal storage heat exchanger 52, the hot side outlet of the cryogenic thermal storage heat exchanger 52 is connected to the inlet of the seventh valve 53, and the outlet of the seventh valve 53 is connected to the inlet of the fusion reactor vacuum chamber.

[0050] The cryogenic energy storage and utilization circuit 6 includes a cryogenic cold tank 62, an eighth pump 63, the cold side of a cryogenic heat exchanger 52, an eighth valve 64, a cryogenic hot tank 61, a ninth pump 65, the hot side of a primary cryogenic preheater 67, the hot side of a secondary cryogenic preheater 68, a ninth valve 66, and pipelines.

[0051] The outlet of the cryogenic cold tank 62 is connected to the inlet of the eighth pump 63. The outlet of the eighth pump 63 is connected to the cold-side inlet of the cryogenic thermal storage heat exchanger 52. The cold-side outlet of the cryogenic thermal storage heat exchanger 52 is connected to the inlet of the eighth valve 64. The outlet of the eighth valve 64 is connected to the inlet of the cryogenic hot tank 61. The outlet of the cryogenic hot tank 61 is connected to the inlet of the ninth pump 65. The outlet of the ninth pump 65 is connected to the hot-side inlet of the first-stage cryogenic preheater 67. The hot-side outlet of the first-stage cryogenic preheater 67 is connected to the hot-side inlet of the second-stage cryogenic preheater 68. The hot-side outlet of the second-stage cryogenic preheater 68 is connected to the ninth valve 66. The outlet of the ninth valve 66 is connected to the inlet of the cryogenic cold tank 62. Heat is absorbed by the cryogenic thermal storage heat exchanger 52 using heat transfer oil or other media and stored in the cryogenic hot tank 61. The high-temperature heat transfer oil transfers heat to the water in the energy cascade utilization power generation circuit through the first-stage cryogenic preheater 67 and the second-stage cryogenic preheater 68.

[0052] The energy cascade utilization power generation circuit 7 includes a primary feedwater pump 71, the cold side of the high-temperature preheater 28, the cold side of the evaporator 27, the cold side of the superheater 26, a high-pressure cylinder 72 of the steam turbine, an intermediate-pressure cylinder 73 of the steam turbine, a low-pressure cylinder 74 of the steam turbine, a reheater 75, a regulating valve 76, a condenser 77, a condensate pump 78, a tenth valve 79, the cold side of the secondary low-temperature preheater 68, the cold side of the primary low-temperature preheater 67, a secondary feedwater pump 713, the cold side of the secondary medium-temperature preheater 48, the cold side of the primary medium-temperature preheater 47, a cooling tower circuit, and pipelines.

[0053] The outlet of the primary feedwater pump 71 is connected to the cold-side inlet of the high-temperature preheater 28. The cold-side outlet of the high-temperature preheater 28 is connected to the cold-side inlet of the evaporator 27. The cold-side outlet of the evaporator 27 is connected to the cold-side inlet of the superheater 26. The cold-side outlet of the superheater 26 is connected to the inlet of the high-pressure cylinder 72 of the turbine. The outlet of the high-pressure cylinder 72 of the turbine is connected to the cold-side inlet of the reheater 75. The cold-side outlet of the reheater 75 is connected to the inlet of the intermediate-pressure cylinder 73 of the turbine. The outlet of the intermediate-pressure cylinder 73 of the turbine is connected to the inlet of the low-pressure cylinder 74 of the turbine. The outlet of the low-pressure cylinder 74 of the turbine is connected to the hot-side inlet of the condenser 77. The hot-side outlet of the condenser 77... The outlet of the condensate pump 78 is connected to the inlet of the condensate pump 78, the outlet of the condensate pump 78 is connected to the inlet of the tenth valve 79, the outlet of the tenth valve 79 is connected to the cold side inlet of the secondary low-temperature preheater 68, the cold side outlet of the secondary low-temperature preheater 68 is connected to the cold side inlet of the primary low-temperature preheater 67, the cold side outlet of the primary low-temperature preheater 67 is connected to the inlet of the secondary feedwater pump 713, the outlet of the secondary feedwater pump 713 is connected to the cold side inlet of the secondary medium-temperature preheater 48, the cold side outlet of the secondary medium-temperature preheater 48 is connected to the cold side inlet of the primary medium-temperature preheater 47, and the cold side outlet of the primary medium-temperature preheater 47 is connected to the inlet of the primary feedwater pump 71.

[0054] The cold side inlet of the reheater 75 is connected to the outlet of the high-pressure cylinder 72 of the steam turbine, the cold side outlet of the reheater 75 is connected to the inlet of the intermediate-pressure cylinder 73 of the steam turbine, the hot side inlet of the reheater 75 is connected to the outlet of the third pump 25 at the outlet of the high-temperature hot tank 21, and the hot side outlet of the reheater 75 is connected to the inlet of the high-temperature cold tank 22.

[0055] A regulating valve 76 is provided at the inlet of the reheater 75 to regulate and control the flow rate of high-temperature molten salt entering the reheater 75.

[0056] The hot side inlet of the condenser 77 is connected to the outlet of the low-pressure cylinder 74 of the steam turbine, the hot side outlet of the condenser 77 is connected to the inlet of the condensate pump 78, and the cold side of the condenser 77 is connected to the cooling tower circuit.

[0057] The cooling tower circuit includes a cooling tower 711, a circulating pump 710, an eleventh valve 712, and piping, etc., and uses atmospheric pressure water to condense and exhaust steam from the condenser turbine. The outlet of the cooling tower 711 is connected to the inlet of the circulating pump 710, the outlet of the circulating pump 710 is connected to the cold side inlet of the condenser 77, the cold side outlet of the condenser 77 is connected to the inlet of the eleventh valve 712, and the outlet of the eleventh valve 712 is connected to the inlet of the cooling tower 711.

[0058] The present invention also provides an operation method for a steam Rankine cycle power generation system for energy cascade utilization in nuclear fusion, comprising the following steps:

[0059] S1. During the operation of the fusion reactor, all valves and pumps are in the open state.

[0060] S1-1: High-temperature heat transfer medium helium, supercritical carbon dioxide, or lithium-lead enters the blanket and breeder blanket, absorbing energy generated during the fusion process. Its temperature rises to 500-600℃, and it flows out into the high-temperature thermal storage heat exchanger 12, where it exchanges heat with molten salt from the high-temperature cold tank 22. The temperature of the high-temperature heat transfer medium helium, supercritical carbon dioxide, or lithium-lead decreases, and it returns to the blanket and breeder blanket to continue absorbing heat. The molten salt, after being heated, enters the high-temperature hot tank 21. After flowing out of the high-temperature hot tank 21, the molten salt splits into two streams. The first stream flows sequentially through the reheater 26, evaporator 27, and high-temperature preheater 28, returning to the high-temperature cold tank 22 after its temperature decreases. The second stream flows through the reheater 75, returning to the high-temperature cold tank 22 after its temperature decreases.

[0061] S1-2, a medium-temperature heat transfer medium of helium, supercritical carbon dioxide, or high-pressure water enters the divertor, absorbs the energy deposited in the divertor by the fusion reaction, and flows out after its temperature rises, entering the medium-temperature heat storage heat exchanger 32. There, it exchanges heat with heat transfer oil or low-melting-point molten salt from the medium-temperature cold tank 42. The temperature of the heat transfer medium helium, supercritical carbon dioxide, or high-pressure water decreases, and it returns to the divertor to continue absorbing heat. The heat transfer oil or low-melting-point molten salt is heated and its temperature rises before entering the medium-temperature hot tank 41. The molten salt flows out of the medium-temperature hot tank 41, sequentially passing through the primary medium-temperature preheater 47 and the secondary medium-temperature preheater 48, and returns to the medium-temperature cold tank 42 after its temperature decreases.

[0062] S1-3. High-pressure water, a low-temperature heat transfer medium, enters the vacuum chamber, absorbs the energy deposited in the vacuum chamber by the fusion reaction, and after its temperature rises, it enters the low-temperature heat exchanger 52 to exchange heat with the heat transfer oil from the low-temperature cold tank 62. The temperature of the high-pressure water decreases, and it returns to the vacuum chamber to continue absorbing heat. The heat transfer oil, after being heated, enters the low-temperature hot tank 61. The heat transfer oil flows out of the low-temperature hot tank 61, passes through the primary low-temperature preheater 67 and the secondary low-temperature preheater 68, and returns to the low-temperature cold tank 62 after its temperature decreases.

[0063] In the S1-4 energy cascade utilization power generation circuit, condensate is pressurized by condensate pump 78 and flows sequentially through the secondary low-temperature preheater 68 and the primary low-temperature preheater 67. It is then pressurized by the secondary feedwater pump 713 and flows sequentially through the secondary medium-temperature preheater 48 and the primary medium-temperature preheater 47. As the feedwater temperature rises, it enters the primary feedwater pump 71 for further pressurization, reaching a pressure above the rated pressure required by the turbine unit. It then flows sequentially through the high-temperature preheater 28, the evaporator 27, and the superheater 26, generating superheated steam. This superheated steam enters the high-pressure cylinder 72 of the turbine, where it expands and performs work. After flowing out, it enters the reheater 75 for further heating, and its temperature rises as it enters the intermediate-pressure cylinder 73 of the turbine for further expansion and work. After performing work, the steam flows into the low-pressure cylinder 74 of the turbine for further expansion and work. The steam after performing work flows into the condenser 77, where it is cooled and condensed into water, which then enters the condensate pump 78.

[0064] S1-5 In the cooling tower circuit, cooling water is pressurized by circulating pump 710 and enters the cooling side of condenser 77 to cool the turbine exhaust steam. The temperature rises and flows out of condenser 77 into cooling tower 711 to exchange heat with the air and lower the temperature.

[0065] S2. During the fusion reactor shutdown, valve 13 and pump 11 are closed, valve 24 and pump 23 are closed, stopping the thermal storage side of high-temperature energy extraction loop 1 and high-temperature energy storage and utilization loop 2. Valve 33 and pump 31 are closed, valve 44 and pump 43 are closed, stopping the thermal storage side of medium-temperature energy extraction loop 3 and medium-temperature energy storage and utilization loop 4.

[0066] The seventh valve 53 and the seventh pump 51 are closed, as are the eighth valve 64 and the eighth pump 63, stopping the thermal storage side of the cryogenic energy export circuit 5 and the cryogenic energy storage and utilization circuit 6. All other pumps and valves are in the open state.

[0067] S2-1. After the molten salt flows out of the high-temperature hot tank 21, it is divided into two paths. The first path flows through the heat exchanger 26, the evaporator 27, and the high-temperature preheater 28 in sequence. After the temperature decreases, it returns to the high-temperature cold tank 22. The second path flows through the reheater 75. After the temperature decreases, it returns to the high-temperature cold tank 22.

[0068] S2-2, Molten salt flows out from the medium-temperature hot tank 41, flows through the first-stage medium-temperature preheater 47 and the second-stage medium-temperature preheater 48, and returns to the medium-temperature cold tank 42 after the temperature decreases.

[0069] S2-3. The heat transfer oil flows out from the low-temperature hot tank 61, flows through the first-stage low-temperature preheater 67 and the second-stage low-temperature preheater 68, and returns to the low-temperature cold tank 62 after the temperature drops.

[0070] The operation method of the S2-4 energy cascade utilization power generation circuit is the same as that of S1-4. In the energy cascade utilization power generation circuit, condensate is pressurized by condensate pump 78 and flows sequentially through the secondary low-temperature preheater 68 and the primary low-temperature preheater 67. It is then pressurized by the secondary feedwater pump 713 and flows sequentially through the secondary medium-temperature preheater 48 and the primary medium-temperature preheater 47. As the feedwater temperature rises, it enters the primary feedwater pump 71 for further pressurization, reaching a pressure above the rated pressure required by the turbine unit. The steam flows sequentially through the high-temperature preheater 28, evaporator 27, and superheater 26, generating superheated steam. It then enters the high-pressure cylinder 72 of the turbine, where it expands and does work. After exiting the high-pressure cylinder 72, the steam enters the reheater 75 for further heating. As its temperature rises, the steam enters the intermediate-pressure cylinder 73 of the turbine for further expansion and work. After doing work, the steam flows into the low-pressure cylinder 74 of the turbine to continue expanding and doing work. The steam after doing work flows into the condenser 77, where it is cooled and condensed into water, which then enters the condensate pump 78.

[0071] S2-5 The operation method of the cooling tower circuit is the same as that of S1-5. In the cooling tower circuit, the cooling water is pressurized by the circulating pump 710 and enters the condenser 77 to cool the turbine exhaust steam. The temperature rises and flows out of the condenser 77 into the cooling tower 711 to exchange heat with the air and lower the temperature.

[0072] Example 2:

[0073] like Figure 2As shown, the difference between Example 2 and Example 1 is as follows: (1) The first-stage medium-temperature preheater 47 and the second-stage medium-temperature preheater 48 are increased to a first-stage medium-temperature preheater 47, a second-stage medium-temperature preheater 48 and a third-stage medium-temperature preheater 49. In the prior art, each preheater needs to extract steam from the high or medium pressure cylinder. Now, three steam extraction systems are saved. (2) The first-stage low-temperature preheater 67 and the second-stage low-temperature preheater 68 are increased to a first-stage low-temperature preheater 67, a second-stage low-temperature preheater 68 and a third-stage low-temperature preheater 69. In the prior art, each preheater needs to extract steam from the medium or low pressure cylinder. Therefore, the present invention saves three steam extraction systems.

[0074] The fusion reactor blanket heat source temperature is 600℃, the divertor heat source temperature is 280℃, and the vacuum chamber heat source temperature is 130℃. The condenser uses conventional settings with a pressure of 15 kPa, corresponding to a condensate temperature of approximately 54℃. The vacuum chamber heat source stores heat in a cryogenic heat tank 61 via a cryogenic heat exchanger 52. The temperature difference between the terminals of the cryogenic heat exchanger 52 is set to 10℃ according to conventional engineering requirements. The storage temperature in the cryogenic heat tank 61 is 120℃. The heat from the cryogenic heat tank 61 flows sequentially through a primary cryogenic preheater 67, a secondary cryogenic preheater 68, and a tertiary cryogenic preheater 69. Based on the energy conservation on the cold and hot sides of the heat exchangers, the condensate temperature is raised from 54℃ to approximately 95℃. After exiting the primary cryogenic preheater 67, the pressure is increased to 7 MPa by a secondary feedwater pump 713.

[0075] The heat source from the divertor stores heat in the medium-temperature heat storage tank 41 via the medium-temperature heat storage heat exchanger 32. The temperature difference between the terminals of the medium-temperature heat storage heat exchanger 32 is set to 10℃ according to conventional engineering requirements. The storage temperature of the medium-temperature heat storage tank 41 is 270℃. The heat from the medium-temperature heat storage tank 41 flows sequentially through the primary medium-temperature preheater 47, the secondary medium-temperature preheater 48, and the tertiary medium-temperature preheater 49. According to the energy conservation on the cold and hot sides of the heat exchangers, the feedwater temperature is raised to approximately 260℃. After exiting the primary medium-temperature preheater 47, the pressure is increased to approximately 17MPa by the primary feedwater pump 71.

[0076] The cladding heat source stores heat in the high-temperature hot tank 21 through the high-temperature heat storage heat exchanger 12. The storage temperature of the high-temperature hot tank 21 is set to 565°C according to the upper limit of the safe operating temperature of molten salt. The heat from the high-temperature hot tank 21 flows sequentially through the heat exchanger 26, the evaporator 27, and the high-temperature preheater 28. The saturated steam temperature of the evaporator at 17MPa is about 355°C. According to the energy conservation on the cold and hot sides of the heat exchanger, the steam temperature is raised to about 550°C.

[0077] 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 steam Rankine cycle power generation system for nuclear fusion energy cascade utilization, characterized in that, include: The high-temperature energy extraction loop is connected to the outlet or inlet of the fusion reactor blanket and is used to extract the medium at 500-600℃. The high-temperature energy storage and utilization circuit is coupled to the high-temperature energy output circuit via a high-temperature heat storage heat exchanger, and is equipped with a high-temperature hot tank, a high-temperature cold tank, and a superheater, an evaporator, and a high-temperature preheater connected in series. The intermediate-temperature energy extraction loop is connected to the outlet or inlet of the fusion reactor divertor. The medium-temperature energy storage and utilization circuit is coupled to the medium-temperature energy output circuit via a medium-temperature heat storage heat exchanger, and is equipped with a medium-temperature hot tank, a medium-temperature cold tank, and at least two stages of medium-temperature preheaters connected in series. The cryogenic energy extraction loop is connected to the outlet or inlet of the fusion reactor vacuum chamber. The low-temperature energy storage and utilization circuit is coupled to the low-temperature energy output circuit via a low-temperature thermal heat exchanger, and is equipped with a low-temperature hot tank, a low-temperature cold tank, and at least two stages of low-temperature preheaters connected in series. The energy cascade utilization power generation circuit is equipped with a condenser, condensate pump, primary feedwater pump, secondary feedwater pump, and high-pressure cylinder, intermediate-pressure cylinder, and low-pressure cylinder of the steam turbine. The feedwater absorbs heat in sequence through the low-temperature preheater, intermediate-temperature preheater, high-temperature preheater, evaporator, and superheater before entering the steam turbine to do work. Each storage and utilization circuit is independent of the others and continuously supplies energy to the energy cascade utilization power generation circuit during the operation or shutdown of the fusion reactor.

2. The energy cascade utilization steam Rankine cycle power generation system for nuclear fusion according to claim 1, characterized in that, The heat-conducting medium of the high-temperature energy extraction circuit is helium, supercritical carbon dioxide, or lithium-lead alloy; the heat storage medium of the high-temperature energy storage and utilization circuit is high-melting-point molten salt. The heat-conducting medium of the medium-temperature energy extraction circuit is helium, supercritical carbon dioxide, or high-pressure water; the heat storage medium of the medium-temperature energy storage and utilization circuit is low-melting-point molten salt or heat-conducting oil. The heat-conducting medium of the low-temperature energy extraction circuit is high-pressure water; the heat storage medium of the low-temperature energy storage and utilization circuit is heat-conducting oil.

3. A steam Rankine cycle power generation system for nuclear fusion energy cascade utilization according to claim 1, characterized in that, The high-temperature energy storage and utilization circuit is equipped with a unidirectional molten salt flow channel. The molten salt flows sequentially through the outlet of the high-temperature hot tank, the third pump, the hot side of the superheater, the hot side of the evaporator, the hot side of the high-temperature preheater, the third valve, and the inlet of the high-temperature cold tank. The outlet of the third pump branches off into a molten salt branch, which flows through the regulating valve and the reheater before converging at the inlet of the high-temperature cold tank.

4. A steam Rankine cycle power generation system for nuclear fusion energy cascade utilization according to claim 1, characterized in that, The medium-temperature energy storage and utilization circuit is equipped with a unidirectional molten salt or heat transfer oil flow channel. The molten salt or heat transfer oil flows sequentially through the outlet of the medium-temperature hot tank, the sixth pump, the hot side of the first-stage medium-temperature preheater, the hot side of the second-stage medium-temperature preheater, the hot side of the third-stage medium-temperature preheater, the sixth valve, and the inlet of the medium-temperature cold tank.

5. A steam Rankine cycle power generation system for nuclear fusion energy cascade utilization according to claim 1, characterized in that, The low-temperature energy storage and utilization circuit is equipped with a one-way heat transfer oil channel. The heat transfer oil flows sequentially through the outlet of the low-temperature hot tank, the ninth pump, the hot side of the first-stage low-temperature preheater, the hot side of the second-stage low-temperature preheater, the hot side of the third-stage low-temperature preheater, the ninth valve, and the inlet of the low-temperature cold tank.

6. A steam Rankine cycle power generation system for nuclear fusion energy cascade utilization according to claim 1, characterized in that, The energy cascade utilizes the reheater hot-side inlet of the power generation circuit to connect to the high-temperature hot tank outlet, the reheater hot-side outlet to the high-temperature cold tank inlet, the reheater cold-side inlet to the turbine high-pressure cylinder outlet, and the cold-side outlet to the turbine intermediate-pressure cylinder inlet.

7. A steam Rankine cycle power generation system for nuclear fusion energy cascade utilization according to claim 1, characterized in that, The medium-temperature preheater has three stages, the low-temperature preheater has three stages, and none of the preheaters have a steam turbine extraction port.

8. A method for generating electricity using a steam Rankine cycle power generation system for nuclear fusion energy cascade utilization, as described in any one of claims 1-7, characterized in that... include: Step 1: During the operation of the fusion reactor, the high-temperature heat of the blanket, the medium-temperature heat of the divertor, and the low-temperature heat of the vacuum chamber are stored in the corresponding high-temperature heat tank, medium-temperature heat tank, and low-temperature heat tank through independent high-temperature energy export circuit, medium-temperature energy export circuit, and low-temperature energy export circuit, respectively. Step 2: During the operation of the fusion reactor and the subsequent shutdown period, the heat from the low-temperature hot tank, the medium-temperature hot tank, and the high-temperature hot tank is released in sequence in the order of low temperature, medium temperature, and high temperature to continuously heat the feedwater and generate superheated steam, so that the steam turbine can continuously do work.

9. The power generation method according to claim 8, characterized in that, In step 1, the molten salt in the high-temperature hot tank is divided into two streams. One stream flows through the reheater to heat the exhaust steam from the high-pressure cylinder of the turbine, while the other stream flows sequentially through the reheater, evaporator, and high-temperature preheater to complete feedwater evaporation and primary heating. The molten salt or heat transfer oil in the medium-temperature hot tank flows sequentially through two or three stages of medium-temperature preheaters to raise the temperature of the feedwater after passing through the secondary feedwater pump, thus completing secondary heating. The heat transfer oil in the low-temperature hot tank flows sequentially through two or three stages of low-temperature preheaters to raise the temperature of the condensate, thus completing tertiary heating. Primary heating, secondary heating, and tertiary heating are completed in series in the same feedwater process, and there is no turbine steam extraction throughout the entire process.

10. The power generation method according to claim 8 or 9, characterized in that, During the fusion reactor shutdown period, the first pump and first valve of the high-temperature energy extraction loop, the fourth pump and fourth valve of the medium-temperature energy extraction loop, and the seventh pump and seventh valve of the low-temperature energy extraction loop are shut down, ceasing the supply of heat to the high-temperature, medium-temperature, and low-temperature hot tanks. The third pump at the outlet of the high-temperature hot tank, the sixth pump at the outlet of the medium-temperature hot tank, the ninth pump at the outlet of the low-temperature hot tank, and all preheaters, evaporators, superheaters, reheaters, turbines, condensers, and feedwater pumps are kept running, allowing molten salt from the high-temperature hot tank to continue flowing through the reheater, superheater, evaporator, and high-temperature preheater, molten salt or heat transfer oil from the medium-temperature hot tank to continue flowing through each stage of the medium-temperature preheater, and heat transfer oil from the low-temperature hot tank to continue flowing through each stage of the low-temperature preheater. The feedwater continuously absorbs heat and generates 550°C superheated steam, ensuring that the turbine continues to supply steam and perform work during the fusion reactor shutdown period.

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