Supercritical carbon dioxide working medium-based nuclear energy power generation system, and control method

Abstract

The present application relates to the technical field of nuclear power, and discloses a supercritical carbon dioxide working medium-based nuclear energy power generation system and a control method. In order to improve the efficiency and safety of existing nuclear energy power generation systems, the supercritical carbon dioxide working medium-based nuclear energy power generation system comprises a main power generation system, a waste heat discharge system, a working medium loading control system, and a working medium charging and recovery system, wherein the working medium in the main power generation system, the waste heat discharge system, the working medium loading control system, and the working medium charging and recovery system is supercritical carbon dioxide. The nuclear energy power generation system and the control method can improve the thermoelectric conversion efficiency, improve system compactness and safety, and can be widely used in nuclear energy power generation systems to replace conventional water working medium-based power generation systems and water working medium-based waste heat removal systems, thereby realizing efficient heat exchange, safe reactor shutdown, and the capability to cope with accidents such as emergency shutdowns. The working medium recovery and purification functions can also improve the energy utilization rate and reduce waste emissions, and the present invention is environmentally friendly and paves the way for the future of clean energy.

Description

Nuclear power generation system based on supercritical carbon dioxide working medium and control method

[0001] The present application claims priority from the Chinese patent application No. 2024108374139 filed on June 26, 2024, and entitled "Nuclear power generation system based on supercritical carbon dioxide working medium and control method", the whole content of which is incorporated herein by reference. TECHNICAL FIELD

[0002] The present application relates to the field of nuclear power technology, in particular to a nuclear power generation system based on supercritical carbon dioxide working medium, and a nuclear power generation control method. BACKGROUND

[0003] Nuclear power generation system is an important heat and electricity conversion method in the field of power generation due to its high power density, stable energy, long-term reliable operation, environmental friendliness and other advantages. The fourth generation reactor types include lead-bismuth reactors, sodium-cooled fast reactors and other liquid metal reactors. Compared with traditional second and third generation nuclear reactors, liquid metal reactors are more optimized in terms of nuclear safety, economy, reduction of nuclear waste, prevention of nuclear proliferation, elimination of severe accidents, and avoidance of off-site emergency. Liquid metal reactors have better heat conductivity, higher safety, and high system compactness, which is beneficial to miniaturization.

[0004] Traditional steam power generation systems have low thermal-electric conversion efficiency, high system complexity, more auxiliary systems, large volume and weight, and energy conversion form needs to be optimized. In addition, the working medium of the residual heat removal system commonly used in traditional nuclear power generation systems is generally water, which requires a large-capacity cooling water tank. During the cooling process, the working medium may undergo phase change in the reactor vessel, which may affect the service life of the reactor pressure vessel and reduce the safety of the reactor. The residual heat removal of reactor accident shutdown and normal shutdown needs to be designed with higher safety factor, more effective, lower failure probability, avoiding the safety problems caused by phase change, reducing the damage to the reactor vessel, ensuring the integrity of the reactor vessel, and improving the safety of reactor normal shutdown and accident shutdown.

[0005] The new supercritical carbon dioxide power generation system is a small, clean, efficient and fast response closed power generation system. There are multiple loop feedbacks in the system, and the properties change dramatically near the critical point, with strong nonlinearity. The system is sensitive to property changes during operation, and the system behavior analysis and control are complex. The system operation mode and control strategy are different from traditional water vapor power generation systems, and a new control operation method needs to be developed based on the characteristics of the working medium, system configuration and demand background. There is no comprehensive and systematic research on this in China.

[0006] SUMMARY

[0007] In order to improve the safety of the existing reactor and the efficiency of the nuclear power generation system, the application provides a supercritical carbon dioxide working medium-based nuclear power generation system and a control method, which has the characteristics of high thermoelectric conversion efficiency, high compactness, high inherent safety and simple and efficient operation control. The liquid metal reactor is provided, which has higher thermal conductivity and inherent safety, the intermediate heat exchanger is arranged in the reactor, which has higher compactness and is beneficial to miniaturization; the main power generation system is arranged to complete the conversion from heat energy to electric energy, which has the characteristics of high efficient thermoelectric conversion efficiency, small volume and rapid load change; the active residual heat removal system and the passive residual heat removal system are arranged, which can realize the export of the core heat energy in the reactor accident state or even the whole plant power failure state, and ensure the safety of the nuclear reactor; the working medium charge control system is arranged to realize the efficient load change function of the power generation system; the working medium charging and recycling system is arranged to provide the conditions for the movement of the system, and has the ability to provide working medium charging for the system at any time, recycle and reuse the "waste gas mixture" generated by the system, improve the energy utilization rate and the thermoelectric conversion efficiency, and reduce the waste discharge; the partition efficient load change control method is proposed, including the working medium charge control method, the bypass adjustment control method and the throttling control method, which can match the optimal load adjustment method for different load intervals.

[0008] The technical scheme adopted by the embodiment of the application to solve the technical problems is:

[0009] A supercritical carbon dioxide working medium-based nuclear power generation system, comprising a main power generation system, a residual heat removal system, a working medium charge control system and a working medium charging and recycling system, wherein the working medium of the main power generation system, the residual heat removal system, the working medium charge control system and the working medium charging and recycling system is supercritical carbon dioxide.

[0010] The main power generation system can convert heat energy into electric energy, and the main power generation system comprises a reactor and a power generation system device, the power generation system device contains a turbine, a generator, a high-temperature regenerator, a low-temperature regenerator, a first cooler, a first pressurizing branch and a second pressurizing branch, the first pressurizing branch is sequentially provided with a first compressor stage one, a second cooler and a first compressor stage two, the second pressurizing branch is provided with a second compressor, the working medium output by the reactor can enter the turbine to do work, the turbine can drive the generator to generate electricity, the spent gas after work can enter the high-temperature regenerator and the low-temperature regenerator in sequence to release heat, the spent gas after heat release can enter the first cooler to be cooled, the spent gas after cooling enters the first compressor stage one to be compressed, the working medium after compression is cooled in the second cooler, the working medium after cooling enters the first compressor stage two to be compressed again, the high-pressure working medium compressed by the first compressor stage one and the first compressor stage two can enter the high-temperature regenerator and the low-temperature regenerator in sequence to absorb heat, the spent gas at the outlet of the low-temperature regenerator also enters the second compressor to be compressed, the high-pressure working medium compressed by the second compressor is combined with the working medium at the outlet of the low-temperature regenerator, and then enters the high-temperature regenerator to absorb heat, and the working medium after heat absorption can enter the reactor to absorb heat to become high-temperature and high-pressure working medium.

[0011] The reactor working medium outlet is connected with the inlet of the turbine through a turbine inlet pipeline, the outlet of the turbine is connected with the heat release inlet of the high-temperature regenerator through a spent gas delivery pipeline, the reactor working medium inlet is connected with the heat absorption outlet of the high-temperature regenerator through a working medium input pipeline, and the compression outlet of the first compressor stage two is connected with the heat absorption inlet of the low-temperature regenerator through a high-pressure working medium delivery pipeline.

[0012] The turbine inlet pipeline is connected with the spent gas delivery pipeline through a turbine bypass pipeline, the turbine bypass pipeline can realize load adjustment and load rejection functions; the working medium input pipeline is connected with the turbine inlet pipeline through a reactor bypass pipeline, the reactor bypass pipeline can realize isolation of the reactor and the main power generation system; and the high-pressure working medium delivery pipeline is communicated with the inlet end of the first cooler through a first compressor bypass pipeline, and the first compressor bypass pipeline can realize working medium flow adjustment.

[0013] The power generation system device further contains a first speed increasing box, a first motor, a second speed increasing box, a second motor and a speed reducing box, the first compressor stage one, the first compressor stage two and the first motor are coaxially arranged, the first compressor stage one, the first compressor stage two and the first motor are connected through gears in the first speed increasing box, the second compressor and the second motor are coaxially arranged, the second compressor and the second motor are connected through gears in the second speed increasing box, the turbine and the generator are coaxially arranged, and the turbine and the generator are connected through gears in the speed reducing box.

[0014] The first cooler, the second cooler, the high-temperature regenerator and the low-temperature regenerator all adopt PCHE type micro-channel high-efficiency heat exchangers, and small volume and high specific surface area heat exchange can be realized.

[0015] The reduction gearbox, the first speed-increasing gearbox and the second speed-increasing gearbox are connected with the recovered working medium import pipeline of the working medium charging and recovering system through the first pipeline, the inlet end of the first cooler is communicated with the working medium charging outlet pipeline of the main power generation system of the working medium charging and recovering system through the second pipeline, and the working medium charging and recovering system can charge and recover working medium.

[0016] The inlet end of the first cooler is communicated with the working medium charging and recovering system outlet pipeline of the working medium charging and recovering system through the third pipeline, the outlet end of the second compressor is communicated with the working medium charging and recovering system import pipeline of the working medium charging and recovering system through the fourth pipeline, and the working medium charging and recovering system can change the load of the main power generation system.

[0017] The reactor contains a control rod drive mechanism, a reactor vessel, a core, a coolant, a coolant pump and an intermediate heat exchanger, the control rod drive mechanism can move the core up and down, the core, the coolant, the coolant pump and the intermediate heat exchanger are located in the reactor vessel, the core can release heat to the coolant, the coolant pump can flow the coolant, the coolant can release heat to the intermediate heat exchanger, the working medium in the main power generation system can enter the intermediate heat exchanger to absorb heat, the inlet of the intermediate heat exchanger is communicated with the reactor working medium inlet, and the outlet of the intermediate heat exchanger is communicated with the reactor working medium outlet.

[0018] The intermediate heat exchanger is a PCHE heat exchanger, a plurality of intermediate heat exchangers are arranged along the circumference of the reactor vessel, the intermediate heat exchanger contains a high-temperature side and a low-temperature side, the coolant is a liquid metal coolant, the coolant flows in the high-temperature side, and the main power generation system working medium flows in the low-temperature side, the inlet of the intermediate heat exchanger is communicated with the reactor working medium inlet, and the outlet of the intermediate heat exchanger is communicated with the reactor working medium outlet.

[0019] The reactor further contains a heat-conducting inner partition plate, the reactor vessel is divided into a working cavity and an auxiliary cavity which are independent of each other by the heat-conducting inner partition plate, the core, the coolant, the coolant pump and the intermediate heat exchanger are located in the working cavity of the reactor vessel, the upper part of the auxiliary cavity is annular, the lower part of the working cavity is sleeved in the upper part of the auxiliary cavity, and the reactor vessel is provided with a residual heat outlet and a residual heat inlet, and the residual heat outlet and the residual heat inlet are communicated with the auxiliary cavity.

[0020] The residual heat removal system contains an active residual heat removal system pipeline, supercritical carbon dioxide is used as a circulating cooling working medium in the active residual heat removal system pipeline, a fourth cooler, a first booster pump and a first heater are sequentially arranged on the active residual heat removal system pipeline in the direction from the inlet end of the active residual heat removal system pipeline to the outlet end of the active residual heat removal system pipeline, the inlet end of the active residual heat removal system pipeline is in communication with the reactor working medium outlet, and the outlet end of the active residual heat removal system pipeline is in communication with the reactor working medium inlet.

[0021] When the reactor needs to be cooled by the active residual heat removal system pipeline during normal shutdown, the first valve on the working medium input pipeline is closed, the second valve on the reactor bypass pipeline is opened, the high-pressure working medium absorbing heat from the high-temperature regenerator does not enter the reactor but enters the turbine through the reactor bypass pipeline, and the working medium discharged from the reactor working medium outlet returns to the reactor working medium inlet through the fourth cooler and the first booster pump in the active residual heat removal system pipeline, so that the core is cooled.

[0022] When the reactor needs to be heated to maintain the temperature of the coolant during shutdown for maintenance, the working medium discharged from the reactor working medium outlet returns to the reactor working medium inlet through the first booster pump and the first heater in the active residual heat removal system pipeline, so that the coolant of the core is heated.

[0023] The residual heat removal system contains a passive residual heat removal system pipeline, supercritical carbon dioxide is used as a circulating cooling working medium in the passive residual heat removal system pipeline, and a third cooler is arranged on the passive residual heat removal system pipeline, the third cooler is located in a water tank, the third cooler is provided with a cold source by the water tank, the inlet end of the passive residual heat removal system pipeline is in communication with the reactor working medium outlet and the residual heat outlet, and the outlet end of the passive residual heat removal system pipeline is in communication with the reactor working medium inlet and the residual heat inlet.

[0024] When the reactor needs to be cooled by the passive residual heat removal system pipeline during an accident shutdown, the circulating cooling working medium in the passive residual heat removal system pipeline enters the reactor from the reactor working medium outlet and the residual heat outlet, and the circulating cooling working medium in the reactor enters the passive residual heat removal system pipeline from the reactor working medium inlet and the residual heat inlet.

[0025] The working medium charging recovery system contains a recovery working medium import pipeline, a charging heat exchanger, a working medium storage tank and a second heater, the outlet end of the recovery working medium import pipeline is connected with the heat release inlet of the charging heat exchanger, the heat release outlet of the charging heat exchanger is connected with the inlet of the working medium storage tank through a heat release branch pipe, the heat absorption inlet of the charging heat exchanger is connected with the outlet of the working medium storage tank through a heat absorption inlet branch pipe, the heat absorption outlet of the charging heat exchanger is connected with the inlet of the second heater through a heat absorption outlet branch pipe, the outlet of the second heater is communicated with the first cooler inlet end through a main power generation system working medium charging outlet pipeline, the outlet of the second heater is also communicated with the active waste heat discharge system pipeline through an active waste heat discharge system charging outlet pipeline and a fifth pipeline in sequence, the outlet of the second heater is also communicated with the passive waste heat discharge system pipeline through a passive waste heat discharge system charging outlet pipeline and a sixth pipeline in sequence.

[0026] Along the direction from the inlet end of the recovery working medium import pipeline to the outlet end of the recovery working medium import pipeline, an induced draft fan, an oil-gas separation cooling device, a high-temperature heating furnace, a dust removal filter and a dryer are sequentially arranged on the recovery working medium import pipeline, the inlet of the high-temperature heating furnace is communicated with the exhaust port of the oil-gas separation cooling device, an oil filter, a sixth cooler and a lubricating oil tank are sequentially connected to the oil discharge port of the oil-gas separation cooling device, a fifth cooler is arranged on the heat release branch pipe, and a second booster pump is arranged on the heat absorption inlet branch pipe.

[0027] The working medium charging control system contains a working medium tank, the outlet of the working medium tank is connected with a working medium charging control system outlet pipeline, the inlet of the working medium tank is connected with a working medium charging control system inlet pipeline, the working medium tank is connected with a cooling water pipe and an electric heating rod, the cooling water pipe can cool the working medium in the working medium tank, and the electric heating rod can heat the working medium in the working medium tank.

[0028] A nuclear power generation control method is applied to the nuclear power generation system based on supercritical carbon dioxide working medium, and the nuclear power generation control method comprises the following steps:

[0029] When the power grid or the load changes, the rated load, the current load, the variable load amplitude and the target load of the main power generation system are determined by changing the electric output of the generator in response to the change of the power grid or the load, and the variable load amplitude is the difference between the target load and the current load;

[0030] When it is judged in sequence that the current load < 50% of the rated load and the variable load amplitude < 20% of the rated load, the working medium charging control method is used for variable load response;

[0031] When it is judged in sequence that the current load < 50% of the rated load and the variable load amplitude ≥ 20% of the rated load, the bypass regulation control method is used for variable load response;

[0032] When the current load is greater than 50% of the rated load and the load variation is less than 20% of the rated load, the working medium quantity control method is used to respond to the load variation;

[0033] When the current load is greater than 50% of the rated load and the load variation is greater than 20% of the rated load, the throttling control method is used to respond to the load variation.

[0034] The working medium quantity control method comprises the following steps:

[0035] The valve opening required under the load variation is determined from the current load and the valve opening-load curve, the valves on the working medium quantity control system outlet pipeline and the working medium quantity control system inlet pipeline are coarsely adjusted, and the valves on the working medium quantity control system outlet pipeline and the working medium quantity control system inlet pipeline are finely adjusted based on the load deviation between the current load and the required load by using feedback control, so as to accurately control the quantity of the working medium in the working medium tank and the main power generation system, and finally change the output load of the generator.

[0036] The working medium quantity control method comprises the following steps:

[0037] The cooling water pipe row and the electric heating rod are adjusted based on the deviation between the set value of the thermophysical property of the working medium in the working medium tank and the measured value of the thermophysical property of the working medium in the working medium tank, so as to overcome the thermophysical property disturbance of the working medium in the working medium tank caused by the change of the valve opening on the working medium quantity control system outlet pipeline and the working medium quantity control system inlet pipeline.

[0038] The bypass adjustment control method comprises the following steps:

[0039] The valve opening required on the turbine bypass pipeline and the compressor bypass pipeline under the load variation is determined from the current load and the valve opening-load curve, the valves on the turbine bypass pipeline and the compressor bypass pipeline are coarsely adjusted, and the valve on the turbine bypass pipeline is finely adjusted based on the load deviation between the current load and the required load by using feedback control, so as to change the working medium flow in the main power generation system, and finally change the output load of the generator.

[0040] The throttling control method comprises the following steps:

[0041] The valve opening required on the turbine inlet pipeline under the load variation is determined from the current load and the valve opening-load curve, the valve on the turbine inlet pipeline is coarsely adjusted, and the valve on the turbine inlet pipeline is finely adjusted based on the load deviation between the current load and the required load by using feedback control, so as to change the air intake amount of the turbine, and finally change the output load of the generator.

[0042] The embodiment of the present application has the advantages of improving the thermal-electric conversion efficiency of the nuclear power generation system, improving the compactness and safety of the system, and being widely applied in the nuclear power generation system, replacing the conventional water working medium power generation system and the water working medium waste heat discharge system, realizing efficient heat exchange, safe shutdown, coping with emergency shutdown and other accidents, and improving the energy utilization rate and reducing waste discharge through working medium recovery and purification function, being environmentally friendly, and being the development direction of future clean energy. BRIEF DESCRIPTION OF DRAWINGS

[0043] The accompanying drawings, which form a part of the present application, are included to provide a further understanding of the present application, and are incorporated herein for purposes of illustrating the preferred embodiments of the present application and explaining the present application but are not intended to limit the present application unduly.

[0044] Fig. 1 is a schematic diagram of the nuclear power generation system based on the supercritical carbon dioxide working medium according to the present application.

[0045] Fig. 2 is a schematic diagram of the working medium charging and recovery system.

[0046] Fig. 3 is a schematic diagram of the working medium charging control system.

[0047] Fig. 4 is a schematic diagram of the reactor.

[0048] Fig. 5 is a flowchart of the nuclear power generation control method.

[0049] Fig. 6 is a flowchart of the load control in the working medium charging control method.

[0050] Fig. 7 is a flowchart of the working medium tank control in the working medium charging control method.

[0051] Fig. 8 is a flowchart of the bypass regulation control method.

[0052] Fig. 9 is a flowchart of the throttling control method.

[0053] The reference signs are explained as follows: 1, reactor; 2, intermediate heat exchanger; 3, turbine; 4, generator; 5, speed reducer; 6, high-temperature regenerator; 7, low-temperature regenerator; 8, first cooler; 9, first compressor stage 1; 10, first compressor stage 2; 11, first motor; 12, first speed increaser; 13, second cooler; 14, second compressor; 15, second motor; 16, second speed increaser; 17, third cooler; 18, water tank; 19, fourth cooler; 20, first booster pump; 21, first heater; 101, first pipeline; 102, second pipeline; 103, third pipeline; 104, fourth pipeline; 105, fifth pipeline; 106, sixth pipeline; 107, turbine bypass pipeline; 108, reactor bypass pipeline; 109, compressor bypass pipeline; 110, turbine inlet pipeline; 111, exhaust gas delivery pipeline; 112, working medium input pipeline; 113, high-pressure working medium delivery pipeline; 121, first valve; 122, second valve; 123, third valve; 124, fourth valve; 125, fifth valve; 126, sixth valve; 127, seventh valve; 128, eighth valve; 129, ninth valve; 1210, tenth valve; 1211, eleventh valve; 201, working medium storage tank; 202, fifth cooler; 203, second booster pump; 204, charging heat exchanger; 205, second heater; 206, dryer; 207, dust removal filter; 208, high-temperature heating furnace; 209, oil-gas separation cooling device; 210, induced draft fan; 211, oil filter; 212, sixth cooler; 213, lubricating oil tank; 214, recovered working medium import pipeline; 215, main power generation system working medium charging export pipeline; 216, active residual heat discharge system charging export pipeline; 217, passive residual heat discharge system charging export pipeline; 301, working medium tank; 302, cooling water pipe row; 303, electric heating rod; 304, working medium charge control system export pipeline; 305, working medium charge control system import pipeline; 401, control rod drive mechanism; 402, reactor vessel; 403, core; 404, auxiliary cavity; 405, coolant pump; 406, reactor working medium inlet; 407, reactor working medium outlet; 408, heat-conducting inner partition plate; 409, residual heat inlet; 410, residual heat outlet. DETAILED DESCRIPTION

[0054] It should be noted that the embodiments and features in the embodiments in the present application can be combined with each other without conflict. The present application will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0055] As shown in FIGS. 1-4, the nuclear power generation system based on supercritical carbon dioxide working medium according to the embodiment of the application comprises a main power generation system, a residual heat removal system, a working medium charging control system and a working medium charging recovery system, and the working medium of the main power generation system, the residual heat removal system, the working medium charging control system and the working medium charging recovery system is supercritical carbon dioxide.

[0056] The nuclear power generation system based on supercritical carbon dioxide working medium can convert thermal energy in the reactor 1 into electric energy, and is provided with a supercritical carbon dioxide Brayton cycle power generation system with high thermal-electric conversion efficiency; the intermediate heat exchanger 2 is arranged in the reactor 1 in an integrated and compact manner; the active residual heat removal system and the passive residual heat removal system are arranged, so that the heat energy of the reactor core can be discharged when the reactor 1 is in an accident state or even in a whole-plant power-off state, and the safety of the nuclear reactor is ensured; the working medium charging control system is arranged to realize the high-efficiency variable load function of the power generation system; the working medium charging recovery system is arranged to provide conditions for the movement of the system, and has the ability to provide working medium charging for the system at any time, recycle and reuse the "waste gas mixture" generated by the system, improve the energy utilization rate and the thermal-electric conversion efficiency, and reduce waste discharge. The nuclear power generation system based on supercritical carbon dioxide working medium has the characteristics of high efficiency, compactness and inherent safety.

[0057] The main power generation system realizes the conversion of thermal energy into electric energy, and comprises the reactor 1 and power generation system equipment. The reactor 1 in the main power generation system is a liquid metal reactor, for example, a lead-bismuth reactor, a sodium-cooled fast reactor and other liquid metal reactors, which is a fourth-generation new reactor type, and the reactor core coolant is a liquid metal coolant, including but not limited to a lead-bismuth alloy coolant and a sodium coolant, and has the advantage of higher inherent safety.

[0058] The reactor in the main power generation system comprises a reactor core 403, a reactor vessel 402, a control rod drive mechanism 401, a coolant pump 405, an intermediate heat exchanger 2, a working cavity and an auxiliary cavity 404. The intermediate heat exchanger 2 in the reactor is a PCHE type high-efficiency and compact heat exchanger, which is built-in in the reactor vessel 402, has higher compactness and higher inherent safety, and can be arranged with multiple intermediate heat exchangers 2 according to the space for arranging the in-core equipment, is arranged in a ring around the reactor core 403, and is divided into a high-temperature side and a low-temperature side. The liquid metal coolant of the reactor core flows on the high-temperature side, and the carbon dioxide working medium flows on the low-temperature side. The entire intermediate heat exchanger is immersed in the reactor core coolant, and the coolant pump 405 provides power for the circulation flow of the reactor core coolant.

[0059] As shown in Fig. 4, the working fluid circulation process in the reactor 1 is as follows: the working fluid in the main power generation system enters the cold side of the intermediate heat exchanger 2 through the reactor working fluid inlet 406, exchanges heat with the reactor coolant in the hot side, and then flows out from the reactor working fluid outlet 407. The working fluid in the hot side of the intermediate heat exchanger 2 is the reactor coolant, which can be a liquid metal. The coolant pump 405 provides circulation power for the reactor coolant, forms a flow heat exchange condition in the reactor vessel, exchanges heat with the core 403, cools the core 403, and transfers heat to the working fluid in the main power generation system. The control rod drive mechanism 401 adjusts the power of the core. The auxiliary cavity 404 provides an interface for residual heat export.

[0060] The working fluid in the main power generation system is supercritical carbon dioxide, and the power generation cycle configuration is an inter-cooling recompression Brayton cycle. Other cycle configurations can also be used, including but not limited to a supercritical carbon dioxide single-stage regenerative Brayton cycle, a supercritical carbon dioxide recompression Brayton cycle, a supercritical carbon dioxide reheating Brayton cycle, etc.

[0061] The working process of the main power generation system is as follows: the high-temperature and high-pressure supercritical carbon dioxide working fluid from the intermediate heat exchanger 2 in the reactor 1 enters the turbine 3 to do work and drive the generator 4 to generate electricity, thereby converting heat energy into electrical energy. The exhausted gas after work enters the hot side of the high-temperature regenerator 6 to preheat the cold side working fluid and then enters the low-temperature regenerator 7 to release heat further. The working fluid from the outlet of the low-temperature regenerator 7 is divided into two branches. The first branch enters the first cooler 8 to cool further. The cooled exhausted gas can enter the first compressor stage 9 and the first compressor stage 2 in sequence to be compressed. The second cooler 13 arranged between the first compressor stage 9 and the first compressor stage 2 can cool the carbon dioxide working fluid heated due to the compression of the first compressor stage 9, thereby reducing the compression work of the subsequent first compressor stage 2 and improving the system heat-electricity conversion efficiency. The presence of the second cooler 13 cools the working fluid heated after compression, reduces the compression power consumption of the second stage compressor, and ultimately achieves the goal of improving the heat-electricity conversion system efficiency. The working fluid from the second cooler 13 enters the first compressor stage 2 to be further pressurized, and then enters the cold side of the low-temperature regenerator 7 to be preheated. The first motor 11 provides power for the first compressor stage 9 and the first compressor stage 2. The second branch directly enters the second compressor 14 to be pressurized, and the second motor 15 provides power for it. The working fluid pressurized by the second compressor 14 is mixed with the working fluid from the outlet of the low-temperature regenerator 7 and then enters the cold side of the high-temperature regenerator 6 to be preheated further. The preheated working fluid enters the intermediate heat exchanger 2 to absorb heat. The high-temperature and high-pressure carbon dioxide working fluid after heat absorption enters the turbine 3 to do work, thereby completing a closed cycle.

[0062] The reactor working medium outlet 407 is connected with the inlet of turbine 3 through turbine inlet pipeline 110, the outlet of turbine 3 is connected with the heat releasing inlet of high temperature regenerator 6 through waste gas delivery pipeline 111, the reactor working medium inlet 406 is connected with the heat absorbing outlet of high temperature regenerator 6 through working medium input pipeline 112, the heat absorbing outlet of high temperature regenerator 6 is communicated with the heat absorbing outlet of low temperature regenerator 7, the outlet of first compressor secondary stage 10 is connected with the heat absorbing inlet of low temperature regenerator 7 through high pressure working medium delivery pipeline 113, turbine inlet pipeline 110 is connected with waste gas delivery pipeline 111 through turbine bypass pipeline 107, working medium input pipeline 112 is connected with turbine inlet pipeline 110 through reactor bypass pipeline 108, high pressure working medium delivery pipeline 113 is communicated with the inlet end of first cooler 8 through main compressor bypass pipeline 109.

[0063] The reactor 1 further comprises a heat conducting inner partition plate 408, the reactor vessel 402 is divided into independent working cavity and auxiliary cavity 404 by the heat conducting inner partition plate 408, the working cavity and the auxiliary cavity 404 are arranged in a vertical manner, the reactor core 403, the coolant, the coolant pump 405 and the intermediate heat exchanger 2 are located in the working cavity of the reactor vessel 402, the upper part of the auxiliary cavity 404 is annular, the lower part of the working cavity is sleeved in the upper part of the auxiliary cavity 404, the reactor vessel 402 is provided with a residual heat outlet 410 and a residual heat inlet 409, the residual heat outlet 410 and the residual heat inlet 409 are communicated with the auxiliary cavity 404.

[0064] The power generation system in the main power generation system is provided with turbine bypass pipeline 107, reactor bypass pipeline 108 and main compressor bypass pipeline 109, so as to realize system power regulation and control.

[0065] The main compressor set in the power generation system in the main power generation system comprises first compressor primary stage 9, first compressor secondary stage 10, first speed increasing box 12 and first motor 11, the first compressor primary stage 9 and the first compressor secondary stage 10 are coaxially arranged with the first motor 11 and connected through gears in the first speed increasing box 12, and lubricating oil bearings are arranged in the gear box; the auxiliary compressor comprises second compressor 14, second speed increasing box 16 and second motor 15, the second compressor 14 is coaxially arranged with the second motor 15 and connected through gears in the second speed increasing box 16, and lubricating oil bearings are arranged in the gear box; the turbine generator set comprises turbine 3, speed reducing box 5 and generator 4, the turbine 3 is coaxially arranged with the generator 4 and connected through gears in the speed reducing box 5, and lubricating oil bearings are arranged in the speed reducing box 5; the carbon dioxide working medium and oil mist mixture generated in the above gear boxes are recycled through working medium filling and purifying system, and the interface is first pipeline 101 and recovered working medium inlet pipeline 214.

[0066] The power generation system in the main power generation system is provided with a third pipeline 103 connected with the working medium quantity control system outlet pipeline 304 and a fourth pipeline 104 connected with the working medium quantity control system inlet pipeline 305, so as to realize the variable working medium quantity of the power generation system and the high-efficiency variable load function of the system.

[0067] The power generation system in the main power generation system is provided with a first pipeline 101 connected with the recovered working medium inlet pipeline 214 and a second pipeline 102 connected with the main power generation system working medium filling outlet pipeline 215, so as to realize the working medium filling, recovery and lubricating oil recovery of the power generation system.

[0068] The waste heat removal system includes a dynamic waste heat removal system and a non-dynamic waste heat removal system.

[0069] The waste heat removal system uses supercritical carbon dioxide as the working medium, and no related patent application using supercritical carbon dioxide as the working medium of the reactor waste heat removal system has been known so far.

[0070] The dynamic waste heat removal system includes a fourth cooler 19 for heat removal, a first booster pump 20 for providing power for the working medium circulation, and a first heater 21 for providing heat when the reactor needs to be heated.

[0071] The working process of the active residual heat removal system is as follows: when the reactor is normally shut down and the active residual heat removal system needs to be put into operation to realize cooling, the first valve 121, the third valve 123, the ninth valve 129 and the tenth valve 1210 are closed, the fourth valve 124, the fifth valve 125, the eighth valve 128, the eleventh valve 1211 and the second valve 122 are opened, the power generation system in the main power generation system directly enters the turbine through the reactor bypass pipeline 108 without passing through the intermediate heat exchanger 2 in the reactor core, and the carbon dioxide in the active residual heat removal system is pressurized by the first booster pump 20, flows through the eleventh valve 1211 into the intermediate heat exchanger 2 in the reactor 1 to exchange heat with the reactor core coolant, carries out the residual heat of the reactor core, and then enters the fourth cooler 19 through the fourth valve 124 and the eighth valve 128 for cooling, and then enters the reactor core through the first booster pump 20 after cooling to complete the closed cycle and realize the residual heat removal of the reactor core. When the reactor is shut down for maintenance and needs to be heated to maintain the temperature of the reactor core coolant, the first valve 121 and the third valve 123, the eighth valve 128 and the eleventh valve 1211 are closed, the fourth valve 124, the fifth valve 125, the ninth valve 129 and the eleventh valve 1211 are opened, and the power generation system is isolated, that is, the power generation system in the main power generation system directly enters the turbine 3 through the reactor bypass pipeline 108 without passing through the intermediate heat exchanger 2 in the reactor core 403; and the carbon dioxide in the active residual heat removal system is pressurized by the first booster pump 20, enters the first heater 21 to be heated, and the heated working medium enters the intermediate heat exchanger 2 to exchange heat with the reactor core coolant, heats the reactor core coolant to a specified temperature, and then returns to the first booster pump 20 of the working medium through the fourth valve 124 and the ninth valve 129 to complete the closed cycle and realize the heating of the reactor core.

[0072] The non-active residual heat removal system includes a third cooler 17, a water tank 18 and corresponding pipeline valve connection members. The non-active residual heat removal system uses supercritical carbon dioxide as a circulating working medium, which has the characteristics of high density difference with the change of pressure and temperature. The strong natural circulation capacity of the working medium can realize the non-active removal of the residual heat of the reactor core. In the case of reactor accidents or even power failure of the whole plant, the non-active residual heat removal system can still realize the removal of the residual heat of the reactor core, ensure the safety of the reactor and prevent the occurrence of serious accidents of the reactor.

[0073] The working process of the passive residual heat removal system is as follows: when the reactor is tripped and needs to be cooled by the passive residual heat removal system, the first valve 121 and the third valve 123 are closed, and the second valve 122, the sixth valve 126 and the seventh valve 127 are opened, so that the carbon dioxide working medium in the circulating system is divided into two branches and enters the reactor, one branch enters the reactor inlet pipe and then enters the core through the reactor inlet pipe; the other branch enters the auxiliary cavity 404 of the reactor to realize uniform cooling of the reactor shell, and then combines with the carbon dioxide working medium in the reactor inlet pipe and flows out from the reactor outlet pipe. The carbon dioxide working medium heated by the core is heated and pressurized, and the working medium density decreases to form a natural circulation buoyancy in the pipe, which rises to the high-level water tank 18 through the sixth valve 126, exchanges heat with water by using the third cooler 17, cools the working medium, and then the cooled carbon dioxide working medium is cooled and pressurized, and the working medium density increases, which enters the reactor 1 through the seventh valve 127 under the action of gravity to continue to be heated, forming a closed passive residual heat cooling circulation loop.

[0074] When the working medium of the passive residual heat removal system enters the core 403 to take heat, it enters the reactor in two branches, which can realize synchronous cooling of the in-core components and the reactor cylinder, uniform cooling, avoid thermal stress problems and material fatigue life problems, greatly improve the safety of the reactor, ensure the integrity of the reactor, and reduce the probability of serious accidents.

[0075] The working medium charging and recycling system provides carbon dioxide working medium for the power generation system, the active residual heat removal system and the passive residual heat removal system in the main power generation system, and recycles the carbon dioxide working medium leaked into the gearbox / reduction gearbox, avoids the need to supplement the working medium during long-term power generation operation, separates the oil gas mixture formed by the carbon dioxide working medium leaked into the gearbox / reduction gearbox and the volatile matter in the lubricating oil, and then recycles the carbon dioxide working medium and the lubricating oil respectively, which can improve energy utilization, reduce system operation waste emissions and reduce power generation working medium supplement.

[0076] As shown in Figure 2, the working fluid charging and recycling system described in the application comprises a working fluid storage tank 201 capable of storing low-temperature and low-pressure liquid working fluid, which is used to store liquid carbon dioxide working fluid, provide a gas source for working fluid charging, and store working fluid in liquid state, which has small storage space and is convenient for transportation; a second booster pump 203 for liquid pressure boosting, which provides power for working fluid circulation; a charging heat exchanger 204, which is used to reduce the configuration capacity of the fifth cooler 202 and the second heater 205, reduce costs, and improve economic efficiency, and the application sets the charging heat exchanger 204 to preheat the working fluid outlet of the working fluid storage tank 201 using the waste heat of the recycled working fluid; a second heater 205, which is used to heat the carbon dioxide working fluid to a specified temperature and inject it into the power generation system; a dryer 206, a dust removal filter 207, and a high-temperature heating furnace 208, which are used to carbonize the remaining small amount of oil mist of the carbon dioxide working fluid after oil mist separation in a high-temperature oil mist carbonization manner to ensure the purity of the recycled working fluid; an oil and gas separation cooling device 209, which is used to separate oil mist and carbon dioxide working fluid; an oil filter 211, a sixth cooler 212, and a lubricating oil tank 213, which complete the recycling, filtering, and storage of lubricating oil after the separation of oil mist and carbon dioxide working fluid.

[0077] The working process of the working fluid charging and recycling system described in the application is as follows:

[0078] The working fluid charging process is as follows: the liquid carbon dioxide working fluid from the working fluid storage tank 201 is pressurized by the second booster pump 203 and enters the charging heat exchanger 204 for preheating, and after absorbing heat, it enters the second heater 205 for further heating. The working fluid heated to a specified temperature enters the corresponding system charging through the main power generation system working fluid charging outlet pipeline 215, the active waste heat discharge system charging outlet pipeline 216, or the non-active waste heat discharge system charging outlet pipeline 217. For example, the outlet of the second heater 205 is in communication with the active waste heat discharge system pipeline through the active waste heat discharge system charging outlet pipeline 216 and the fifth pipeline 105 in sequence, and the outlet of the second heater 205 is in communication with the non-active waste heat discharge system pipeline through the non-active waste heat discharge system charging outlet pipeline 217 and the sixth pipeline 106 in sequence.

[0079] The working fluid recovery process is as follows: the oil mist working fluid mixture from the speed increasing box / speed reducing box enters the recovery working fluid inlet pipeline 214 through the first pipeline 101, enters the oil-gas separation cooling device 209 through the induced draft fan 210 to realize the rough separation of the carbon dioxide working fluid and the oil mist, the separated oil mist is purified and recovered through the oil filter 211 and the sixth cooler 212, and finally is injected into the lubricating oil tank 213 for storage; the carbon dioxide working fluid separated from the oil-gas separation cooling device 209 contains a small amount of oil mist, is further carbonized by heating in the high-temperature heating furnace 208 to ensure the purity of the separated working fluid, and forms particles adhering to the volume wall surface; the separated pure carbon dioxide working fluid enters the dust removal filter 207 and the dryer 206 in sequence to realize purification, then enters the filling heat exchanger 204 to preheat the liquid working fluid at the outlet of the storage tank, and finally is cooled to a liquid state through the fifth cooler 202 and is injected back into the working fluid storage tank.

[0080] As shown in FIG. 3, the working fluid charge control system described in the application can realize the requirement of efficient and rapid load change of the power generation system, and the density difference of the carbon dioxide working fluid is changed with the change of the pressure and temperature, so as to change the working fluid charge in the power generation system loop, and then change the power generation point power of the turbine generator set. The working fluid tank 301 is used to store the system working fluid, the cooling water pipe row 302 is used to cool the working fluid, the pressure and density of the working fluid in the storage tank are changed, the electric heating rod 303 is used to heat the working fluid, the pressure and density of the working fluid in the storage tank are changed, and the working fluid charge control system inlet / outlet pipeline realizes working fluid replacement.

[0081] The working process of the working fluid charge control system described in the application is as follows: the working fluid charge control system inlet pipeline 305 is connected with the fourth pipeline 104, and the working fluid charge control system outlet pipeline 304 is connected with the third pipeline 103. When the system needs to reduce the load, the valve on the working fluid charge control system inlet pipeline 305 is opened, and the valve on the working fluid charge control system outlet pipeline 304 is closed, so that the high-pressure working fluid at the outlet of the second compressor 14 enters the working fluid tank 301 under the action of the pressure difference, the working fluid of the power generation system is reduced, the working capacity is reduced, and the output electric power is reduced to respond to the load reduction action; when the system needs to increase the load, the carbon dioxide working fluid in the working fluid tank 301 needs to be sent back to the power generation system through the working fluid charge control system outlet pipeline 304 based on the density difference, that is, the pressure difference, the working fluid at the third pipeline 103 is the low-pressure section of the system, the cooling and heating functions of the cooling water pipe row 302 and the electric heating rod 303 are controlled to change the pressure in the working fluid tank 301, so that the density of the working fluid in the working fluid tank is always higher than the density of the working fluid in the third pipeline 103, at this time, under the action of the pressure difference, the working fluid enters the power generation system, the working fluid of the power generation system is increased, the working capacity is increased, and the output electric power is increased to respond to the load increase action.

[0082] The working medium charge control system described in the application has the characteristics of low energy consumption variable load control, no need to set up a power source such as a working medium pump, and automatic displacement circulation of the working medium by using the high density difference of carbon dioxide working medium at different temperatures. The system is provided with heating and cooling functions, and can realize adjustable working medium pressure and temperature in the working medium tank, adapt to variable load requirements of different working conditions, and reduce the volume of the working medium tank by using the cooling function. The system has the functions of high efficiency and rapid load change, and can realize more economic load change than conventional throttle regulation and bypass regulation by changing the power generation system loop charge to respond to load changes, and has no energy waste.

[0083] The system described in the application is a closed power generation cycle system, and has a loop feedback. For example, the turbine back pressure is related to the compressor inlet pressure, the compressor outlet pressure is related to the turbine inlet pressure, and the parameter change of one device of the compressor or turbine will affect the other device. The system loop includes two compressors, and the first compressor and the second compressor 14 have flow distribution. The working points of the two compressors are different, and the operating characteristics are different. Therefore, the compressor control and operating matching need to be considered. The first compressor inlet is close to the critical point, the property changes sharply near the critical point, has strong non-linear characteristics, the system running process is sensitive to the property change, and the system behavior analysis and control are complex. The system uses a high-temperature regenerator 6 and a low-temperature regenerator 7, the fluid temperatures on the hot side and the cold side affect each other, the outlet temperature and the inlet temperature of the heat source are coupled to each other, the outlet temperature and the inlet temperature of the compressor are coupled to each other, and the system has strong coupling characteristics. It is necessary to establish a targeted control strategy and method for the system in combination with the variable load requirements, the working medium characteristics, the system configuration and the characteristics of the control means. The advanced nuclear energy system control method proposed in the application is a partition efficient variable load control, including a working medium charge control method, a bypass regulation control method and a throttle control method. The method can match the optimal load regulation means for different load intervals.

[0084] The nuclear power generation control method has the characteristics of high efficiency, simplicity, rapidity and energy saving. In the case of high load level of the system (such as higher than 50% load level), a high-efficiency variable load method is suitable to be selected to achieve energy saving and high efficiency, and not to cause waste of system thermal energy. At this time, the working medium quantity control method and the throttling control method are most suitable for realizing system variable load. The working principle of the working medium quantity control method is to adjust the system load by increasing or reducing the working medium mass in the loop. The advantage of this control method is that the system efficiency can be well maintained when the power changes. However, this control method needs working medium storage tank for storage. For a large power device, the volume of the storage tank can be very large. Considering the economy, this method is more suitable for use in small range load regulation. Therefore, the control method divides the variable load range (20% load range is taken as the boundary). The working principle of the throttling control method is to adjust the turbine main gas regulating valve, i.e. the valve opening of the turbine inlet pipeline 110, to realize the change of the rotating speed and the working medium flow, so as to realize the adjustment of the system load. The advantage of this control method is that there is no waste of working medium energy in the variable load process, and the system efficiency can be maintained, and the adjustment rate is fast. In the case of low load level of the system (such as lower than 50% load level), the system efficiency is not the priority guarantee factor. Under the requirement of frequent variable load, a simple and direct variable load means will be more suitable. At this time, the working medium quantity control method and the bypass regulation control method are more suitable. The working principle of the bypass regulation method is to realize variable load by changing the working medium mass entering the turbine to do work through working medium bypass. The advantage of this control method is fast and simple, and is suitable for frequent operation. The disadvantage is that it causes waste of system energy and reduces the efficiency of system variable load. From the perspective of energy saving, it is not suitable for use in high power level and large amplitude variable load. Therefore, the system control method proposed in the application also divides the variable load range at low load level, and combines the characteristics of the working medium quantity control method and the bypass regulation method to adjust the load. The specific examples are as follows:

[0085] As shown in Fig. 5, the preprocessor monitors the external power grid load demand in real time, compares it with the measured load to generate a variable load instruction, and judges the variable load control method to be executed in combination with the current load level and variable load amplitude. If the load level is less than 50%, it is further judged whether the variable load amplitude is less than 20%. If it is less than 20%, the working medium charge control method is used for variable load control, entering the first processing module. After adjustment by the first processing module, the output power is changed, and the current measured load is fed back to the preprocessor to form a closed loop load control. Otherwise, if the variable load amplitude is greater than or equal to 20%, the bypass adjustment control method is used, entering the second processing module. After adjustment by the second processing module, the output power is changed, and the current measured load is fed back to the preprocessor to form a closed loop load control. If the load level is greater than or equal to 50%, it is further judged whether the variable load amplitude is less than 20%. If it is less than 20%, the working medium charge control method is used for variable load control, entering the first processing module. After adjustment by the first processing module, the output power is changed, and the current measured load is fed back to the preprocessor to form a closed loop load control. Otherwise, if the variable load amplitude is greater than or equal to 20%, the throttling control method is used, entering the third processor. After adjustment by the third processor, the output power is changed, and the measured load is fed back to the preprocessor.

[0086] The first processing module is shown in Figs. 6 and 7, which is divided into a load control part and a working medium tank control part. Fig. 6 is a schematic diagram of the load control part of the first processing module, and Fig. 7 is a schematic diagram of the working medium tank control part of the first processing module. The load control part is a priori-feedback closed loop servo control structure. When receiving the target load, one part enters the priori channel to perform valve position coarse adjustment according to the valve opening-load curve, so as to improve the rapid response to load changes. The other part enters the feedback channel to generate a load difference by comparing with the measured load value, and adjusts the valve opening of the working medium charge control system outlet pipeline 304 and the working medium charge control system inlet pipeline 305 by using a valve position PID controller, so as to change the working medium charge in the tank, and then change the working medium charge in the main power generation system, so as to realize accurate control of the output load, and meet the accurate following requirement of load changes. The working medium tank control part is a single closed loop constant value control structure, which aims to overcome the thermal property disturbance of the working medium tank 301 caused by the change of the working medium tank outlet and inlet pipeline valve opening, by adjusting the cooling water pipe row 302 and the electric heating rod 303, so as to maintain good regulation performance.

[0087] The specific implementation includes but is not limited to: when receiving the target load, first, based on the valve opening-load curve (which can be obtained through a limited number of experiments) to obtain the valve opening on the working fluid mass control system inlet pipeline 305 and the working fluid mass control system outlet pipeline 304, to realize the rough adjustment of the valve. Next, compare the target load with the load measurement value to obtain the load difference. When the difference is positive, the electric power output of the generator 4 needs to be increased, and the turbine 3 needs to output more work. At this time, the regulating valve on the working fluid mass control system inlet pipeline 305 is closed, and the valve on the working fluid mass control system outlet pipeline 304 is finely adjusted by the working fluid mass PID controller, to inject high-pressure and high-density working fluid into the main power generation system, thereby increasing the working fluid mass of the main power generation system and increasing the power generation output, and realizing the following of the load demand. Conversely, when the difference is negative, the electric power output of the generator 4 needs to be reduced, and the turbine needs to output less work. At this time, the regulating valve on the working fluid mass control system outlet pipeline 304 is closed, and the valve on the working fluid mass control system inlet pipeline 305 is finely adjusted by the working fluid mass PID controller, so that the high-pressure and high-density working fluid of the main power generation system at the fourth pipeline 104 interface enters the storage tank, thereby reducing the working fluid mass of the main power generation system and reducing the power generation output, and realizing the following of the load demand. In addition, during the valve adjustment process, the working fluid tank mass changes will cause the thermal properties of the working fluid tank to change, resulting in a decrease in the adjustment performance. In order to maintain good adjustment performance, the thermal properties of the working fluid tank 301 need to be maintained near the set value. When the working fluid is filled, the temperature and pressure of the working fluid tank rise. At this time, the electric heating rod 303 is closed, and the cooling water pipe discharge 302 is adjusted by the cooling water PID controller to increase the amount of cooling water, so as to reduce the pressure and temperature of the working fluid in the working fluid tank 301, and facilitate the filling of the working fluid in the working fluid tank. When the working fluid is discharged, the temperature and pressure of the working fluid tank decrease. At this time, the cooling water pipe discharge 302 is closed, and the heating power of the electric heating rod 303 is increased by the PID controller of the electric heating rod 303, so as to increase the pressure and temperature of the working fluid in the working fluid tank 301, and facilitate the injection of the working fluid from the working fluid tank to the main power generation system. It is worth mentioning that the electric heating rod 303 and the cooling water pipe discharge 302 provided in the present application will continuously monitor the deviation of the thermal properties in the working fluid tank from the set value after each execution of the working fluid mass control system load conversion, and when the deviation occurs, the working fluid in the storage tank can be restored to the expected and set pressure and temperature state through heating and cooling, so as to maintain good adjustment performance, and better realize the next load conversion execution.

[0088] The second processing module is shown in Figure 8, which adopts a double-priori-single-feedback servo control structure. When the target load is received, one part enters the priori channel to coarsely adjust the valve position of the valves on the turbine bypass pipeline 107 and the compressor bypass pipeline 109 according to the valve opening-load curve, so as to improve the rapid response to load changes. The other part enters the feedback channel, in which the feedback channel only acts on the valve on the turbine bypass pipeline 107 to ensure the stability of the control, generates a load difference by comparing with the measured load value, and adjusts the valve opening of the valve on the turbine bypass pipeline 107 by using a valve position PID controller, so as to change the working medium flow of the main power generation system, finally affect the turbine work and the output electric power of the generator, and accurately respond to the load change requirements.

[0089] The specific implementation includes but is not limited to: when the target load is received, the valve opening of the valve on the turbine bypass pipeline 107 and the compressor bypass pipeline 109 is obtained based on the valve opening-load curve (which can be obtained by a limited number of experiments) to achieve coarse adjustment of the valve. Next, the target load is compared with the measured load value to obtain a load difference. If the calculated load deviation is negative, the electric power output of the generator 4 needs to be increased, and the turbine 3 needs to increase the work output. At this time, the valve on the turbine bypass pipeline 107 is finely adjusted by the valve position PID controller to reduce the working medium flow through the turbine bypass pipeline 107, so that the working medium flow through the main power generation system is increased, and the power output is increased to follow the load demand. Conversely, the working medium flow through the turbine bypass pipeline 107 is increased, so that the working medium flow through the main power generation system is reduced, and the power output is reduced to follow the load demand. This adjustment method is a bypass adjustment control method.

[0090] The third processing module is shown in Figure 9, which adopts a priori-feedback servo control structure. When the target load is received, one part enters the priori channel to coarsely adjust the turbine inlet valve on the turbine inlet pipeline 110 according to the valve opening-load curve, so as to improve the rapid response to load changes. The other part enters the feedback channel, generates a load difference by comparing with the measured load value, and adjusts the valve opening of the turbine inlet valve on the turbine inlet pipeline 110 by using a valve position PID controller, so as to change the turbine inlet flow, finally affect the turbine work and the output electric power of the generator, and accurately respond to the load change requirements.

[0091] The specific embodiments include but are not limited to: when receiving the target load, firstly, the turbine inlet valve opening on the turbine inlet pipeline 110 is obtained based on the valve opening-load curve (which can be obtained through a limited number of experiments) to achieve rough adjustment of the valve. Next, the target load is compared with the measured load to obtain a load difference. If the calculated load deviation is negative, the power output of the generator 4 needs to be increased, and the turbine 3 needs to increase the output. At this time, the turbine inlet valve on the turbine inlet pipeline 110 is finely adjusted by the valve position PID controller to increase the turbine inlet flow rate, thereby increasing the turbine output and the generator output power to follow the load demand. Conversely, reducing the turbine inlet flow rate, thereby reducing the turbine output and the generator output power to follow the load demand. This adjustment method is the throttling control method.

[0092] The working medium charge control method corresponds to the first processing module, the bypass adjustment control method corresponds to the second processing module, and the throttling control method corresponds to the third processing module. The above is only a specific embodiment of the present application, and cannot limit the scope of the application. Therefore, the replacement of equivalent components or equivalent changes and modifications made within the scope of protection of the present application should still fall within the scope of the present application. In addition, the technical features in the present application can be freely combined with each other, and the technical features can be freely combined with each other.

Claims

1. A nuclear power generation system based on supercritical carbon dioxide as the working fluid, wherein, The nuclear power generation system based on supercritical carbon dioxide working fluid includes a main power generation system, a waste heat removal system, a working fluid quantity control system, and a working fluid filling and recovery system. The working fluid in the main power generation system, the waste heat removal system, the working fluid quantity control system, and the working fluid filling and recovery system is all supercritical carbon dioxide.

2. The nuclear power generation system based on supercritical carbon dioxide working fluid according to claim 1, wherein, The main power generation system can convert thermal energy into electrical energy. The main power generation system includes a reactor (1) and power generation system equipment. The power generation system equipment includes a turbine (3), a generator (4), a high-temperature regenerator (6), a low-temperature regenerator (7), a first cooler (8), a first pressurization branch, and a second pressurization branch. The first pressurization branch is sequentially equipped with a first compressor stage (9), a second cooler (13), and a first compressor stage (10). The second pressurization branch is equipped with a second compressor (14). The working fluid output from the reactor (1) can enter the turbine (3) to do work. The turbine (3) can drive the generator (4) to generate electricity. The exhaust gas after doing work can sequentially enter the high-temperature regenerator (6) and the low-temperature regenerator (7) to release heat. The exhaust gas can enter the first cooler (8) for cooling. The cooled exhaust gas enters the first stage of the first compressor (9) for compression. The compressed working fluid is cooled in the second cooler (13). The cooled working fluid enters the second stage of the first compressor (10) for compression again. The high-pressure working fluid compressed by the first stage of the first compressor (9) and the second stage of the first compressor (10) can enter the high-temperature regenerator (6) and the low-temperature regenerator (7) in sequence to absorb heat. The exhaust gas at the outlet of the low-temperature regenerator (7) also enters the second compressor (14) for compression. The high-pressure working fluid compressed by the second compressor (14) merges with the working fluid at the outlet of the low-temperature regenerator (7) and then enters the high-temperature regenerator (6) to absorb heat. The working fluid after absorbing heat can enter the reactor (1) to absorb heat and become a high-temperature and high-pressure working fluid.

3. The nuclear power generation system based on supercritical carbon dioxide working fluid according to claim 2, wherein, The reactor working fluid outlet (407) is connected to the inlet of the turbine (3) through the turbine inlet pipeline (110). The outlet of the turbine (3) is connected to the heat release inlet of the high-temperature regenerator (6) through the exhaust gas transmission pipeline (111). The reactor working fluid inlet (406) is connected to the heat absorption outlet of the high-temperature regenerator (6) through the working fluid input pipeline (112). The compression outlet of the second stage (10) of the first compressor is connected to the heat absorption inlet of the low-temperature regenerator (7) through the high-pressure working fluid transmission pipeline (113).

4. The nuclear power generation system based on supercritical carbon dioxide working fluid according to claim 3, wherein, The turbine inlet pipeline (110) is connected to the exhaust gas transmission pipeline (111) via the turbine bypass pipeline (107), which enables load regulation and load shedding functions; the working fluid input pipeline (112) is connected to the turbine inlet pipeline (110) via the reactor bypass pipeline (108), which enables the isolation of the reactor (1) and the main power generation system; the high-pressure working fluid transmission pipeline (113) is connected to the inlet end of the first cooler (8) via the first compressor bypass pipeline (109), which enables the working fluid flow regulation and load regulation functions.

5. The nuclear power generation system based on supercritical carbon dioxide working fluid according to claim 2, wherein, The power generation system equipment also includes a first speed increaser (12), a first motor (11), a second speed increaser (16), a second motor (15), and a gearbox (5). The first compressor stage (9), the first compressor stage (10), and the first motor (11) are coaxially arranged. The first compressor stage (9), the first compressor stage (10), and the first motor (11) are connected by gears in the first speed increaser (12). The second compressor (14) and the second motor (15) are coaxially arranged. The second compressor (14) and the second motor (15) are connected by gears in the second speed increaser (16). The turbine (3) and the generator (4) are coaxially arranged. The turbine (3) and the generator (4) are connected by gears in the gearbox (5).

6. The nuclear power generation system based on supercritical carbon dioxide working fluid according to claim 5, wherein, The first cooler (8), the second cooler (13), the high-temperature regenerator (6) and the low-temperature regenerator (7) all adopt PCHE-type microchannel high-efficiency heat exchangers, which can achieve heat exchange with small volume and high specific surface area.

7. The nuclear power generation system based on supercritical carbon dioxide working fluid according to claim 5, wherein, The gearbox (5), the first speed increaser (12), and the second speed increaser (16) are all connected to the working fluid inlet pipeline (214) of the working fluid filling and recovery system through the first pipeline (101). The inlet end of the first cooler (8) is connected to the working fluid filling outlet pipeline (215) of the main power generation system of the working fluid filling and recovery system through the second pipeline (102). The working fluid filling and recovery system is capable of filling and recovering working fluid.

8. The nuclear power generation system based on supercritical carbon dioxide working fluid according to claim 2, wherein, The inlet end of the first cooler (8) is connected to the outlet pipeline (304) of the working fluid quantity control system of the working fluid quantity control system through the third pipeline (103), and the outlet end of the second compressor (14) is connected to the inlet pipeline (305) of the working fluid quantity control system of the working fluid quantity control system through the fourth pipeline (104). The working fluid quantity control system can change the load of the main power generation system.

9. The nuclear power generation system based on supercritical carbon dioxide working fluid according to claim 3, wherein, The reactor (1) includes a control rod drive mechanism (401), a reactor vessel (402), a core (403), a coolant, a coolant pump (405), and an intermediate heat exchanger (2). The control rod drive mechanism (401) can move the core (403) up and down. The core (403), the coolant, the coolant pump (405), and the intermediate heat exchanger (2) are all located inside the reactor vessel (402). The core (403) can release heat to the coolant. The coolant pump (405) can make the coolant flow. The coolant can release heat to the intermediate heat exchanger (2). The working fluid in the main power generation system can enter the intermediate heat exchanger (2) to absorb heat. The inlet of the intermediate heat exchanger (2) is connected to the reactor working fluid inlet (406), and the outlet of the intermediate heat exchanger (2) is connected to the reactor working fluid outlet (407).

10. The nuclear power generation system based on supercritical carbon dioxide working fluid according to claim 9, wherein, Intermediate heat exchanger (2) is a PCHE heat exchanger. Multiple intermediate heat exchangers (2) are arranged circumferentially along the reactor vessel (402). The intermediate heat exchanger (2) contains a high-temperature side and a low-temperature side. The coolant is a liquid metal coolant. The coolant flows on the high-temperature side, and the working fluid of the main power generation system flows on the low-temperature side. The inlet of the intermediate heat exchanger (2) is connected to the reactor working fluid inlet (406), and the outlet of the intermediate heat exchanger (2) is connected to the reactor working fluid outlet (407).

11. The nuclear power generation system based on supercritical carbon dioxide working fluid according to claim 9, wherein, The reactor (1) also contains a thermally conductive inner baffle (408). The reactor vessel (402) is divided by the thermally conductive inner baffle (408) to form an independent working chamber and an auxiliary chamber (404). The core (403), the coolant, the coolant pump (405) and the intermediate heat exchanger (2) are all located in the working chamber of the reactor vessel (402). The upper part of the auxiliary chamber (404) is annular, and the lower part of the working chamber is fitted inside the upper part of the auxiliary chamber (404). The reactor vessel (402) is provided with a residual heat outlet (410) and a residual heat inlet (409). The residual heat outlet (410) and the residual heat inlet (409) are both connected to the auxiliary chamber (404).

12. The nuclear power generation system based on supercritical carbon dioxide working fluid according to claim 11, wherein, The waste heat removal system includes a dynamic waste heat removal system pipeline. Supercritical carbon dioxide is used as the circulating cooling medium in the dynamic waste heat removal system pipeline. Along the direction from the inlet end to the outlet end of the dynamic waste heat removal system pipeline, a fourth cooler (19), a first booster pump (20), and a first heater (21) are sequentially arranged on the dynamic waste heat removal system pipeline. The inlet end of the dynamic waste heat removal system pipeline is connected to the reactor working medium outlet (407), and the outlet end of the dynamic waste heat removal system pipeline is connected to the reactor working medium inlet (406).

13. The nuclear power generation system based on supercritical carbon dioxide working fluid according to claim 12, wherein, When the reactor (1) needs to be cooled by activating the active waste heat removal system pipeline during normal shutdown, the first valve (121) on the working fluid input pipeline (112) is closed, and the second valve (122) on the reactor bypass pipeline (108) is opened. The high-pressure working fluid that absorbs heat from the high-temperature regenerator (6) does not enter the reactor (1) but enters the turbine (3) through the reactor bypass pipeline (108). The working fluid discharged from the reactor working fluid outlet (407) passes through the... The fourth cooler (19) and the first booster pump (20) in the active waste heat removal system pipeline return to the reactor working fluid inlet (406) to achieve cooling of the reactor core (403); When the reactor (1) is shut down for maintenance and heating is required to maintain the temperature of the coolant, the working medium discharged from the reactor working medium outlet (407) returns to the reactor working medium inlet (406) through the first booster pump (20) and the first heater (21) in the active residual heat removal system pipeline, thereby achieving heat tracing of the coolant in the reactor core (403).

14. The nuclear power generation system based on supercritical carbon dioxide working fluid according to claim 11, wherein, The waste heat removal system includes a passive waste heat removal system pipeline. The passive waste heat removal system pipeline uses supercritical carbon dioxide as the circulating cooling medium. A third cooler (17) is installed on the passive waste heat removal system pipeline. The third cooler (17) is located in a water tank (18). The third cooler (17) is provided with a cold source by the water tank (18). The inlet end of the passive waste heat removal system pipeline is connected to both the reactor working medium outlet (407) and the waste heat outlet (410). The outlet end of the active waste heat removal system pipeline is connected to both the reactor working medium inlet (406) and the waste heat inlet (409).

15. The nuclear power generation system based on supercritical carbon dioxide working fluid according to claim 14, wherein, When the reactor (1) experiences an accident and needs to be shut down, requiring the passive residual heat removal system pipeline to be put into operation for cooling, the circulating cooling working medium in the passive residual heat removal system pipeline enters the reactor (1) from the reactor working medium outlet (407) and the residual heat outlet (410), and the circulating cooling working medium in the reactor (1) enters the passive residual heat removal system pipeline from the reactor working medium inlet (406) and the residual heat inlet (409).

16. The nuclear power generation system based on supercritical carbon dioxide working fluid according to claim 7, wherein, The working fluid filling and recovery system includes a working fluid inlet pipeline (214), a filling heat exchanger (204), a working fluid storage tank (201), and a second heater (205). The outlet end of the working fluid inlet pipeline (214) is connected to the heat release inlet of the filling heat exchanger (204). The heat release outlet of the filling heat exchanger (204) is connected to the inlet of the working fluid storage tank (201) through a heat release branch pipe. The heat absorption inlet of the filling heat exchanger (204) is connected to the outlet of the working fluid storage tank (201) through a heat absorption inlet branch pipe. The heat absorption outlet of the filling heat exchanger (204) is connected to the outlet of the working fluid storage tank (201) through a heat absorption outlet branch pipe. The outlet of the second heater (205) is connected to the inlet of the first cooler (8) through the working fluid filling outlet pipeline (215) of the main power generation system. The outlet of the second heater (205) is also connected to the active waste heat discharge system pipeline through the active waste heat discharge system filling outlet pipeline (216) and the fifth pipeline (105) in sequence. The outlet of the second heater (205) is also connected to the passive waste heat discharge system pipeline through the passive waste heat discharge system filling outlet pipeline (217) and the sixth pipeline (106) in sequence.

17. The nuclear power generation system based on supercritical carbon dioxide working fluid according to claim 16, wherein, Along the direction from the inlet end of the working medium inlet pipeline (214) to the outlet end of the working medium inlet pipeline (214), the working medium inlet pipeline (214) is sequentially equipped with an induced draft fan (210), an oil-gas separation and cooling device (209), a high-temperature heating furnace (208), a dust removal filter (207), and a dryer (206). The inlet of the high-temperature heating furnace (208) is connected to the exhaust port of the oil-gas separation and cooling device (209). An oil filter (211), a sixth cooler (212), and a lubricating oil tank (213) are sequentially connected to the oil outlet of the oil-gas separation and cooling device (209). A fifth cooler (202) is installed on the heat release branch pipe, and a second booster pump (203) is installed on the heat absorption inlet branch pipe.

18. The nuclear power generation system based on supercritical carbon dioxide working fluid according to claim 8, wherein, The working fluid filling control system includes a working fluid tank (301). The outlet of the working fluid tank (301) is connected to the outlet pipeline (304) of the working fluid filling control system, and the inlet of the working fluid tank (301) is connected to the inlet pipeline (305) of the working fluid filling control system. The working fluid tank (301) is connected to a cooling water pipe bank (302) and an electric heating rod (303). The cooling water pipe bank (302) can cool the working fluid in the working fluid tank (301), and the electric heating rod (303) can heat the working fluid in the working fluid tank (301).

19. A nuclear power generation control method, wherein, The nuclear power generation control method is applied to the nuclear power generation system based on supercritical carbon dioxide working fluid as described in claim 1, and the nuclear power generation control method includes the following steps: When the power grid or load changes, the rated load, current load, load variation range and target load of the main power generation system are determined by changing the electrical output of the generator (4) in response to the power grid or load change, wherein the load variation range is the difference between the target load and the current load; When it is determined that the current load is less than 50% of the rated load and the change in load amplitude is less than 20% of the rated load, the working fluid quantity control method is used to respond to the change in load. When it is determined that the current load is less than 50% of the rated load and the load change amplitude is greater than or equal to 20% of the rated load, the bypass regulation control method is used to respond to the load change. When it is determined that the current load is greater than or equal to 50% of the rated load and the change in load is less than 20% of the rated load, the working fluid quantity control method is used to respond to the change in load. When it is determined that the current load is greater than or equal to 50% of the rated load and the change in load is greater than or equal to 20% of the rated load, the throttling control method is used to respond to the change in load.

20. The nuclear power generation control method according to claim 19, wherein, The method for controlling the amount of working fluid includes the following steps: Based on the current load and valve opening-load curve, the required valve opening under the variable load range is determined. The valves on the outlet pipeline (304) and inlet pipeline (305) of the working fluid loading control system are coarsely adjusted. Based on the load deviation between the current load and the required load, feedback control is used to finely adjust the valves on the outlet pipeline (304) and inlet pipeline (305) of the working fluid loading control system, so as to achieve precise control of the working fluid loading in the working fluid tank (301) and the main power generation system, and finally change the output load of the generator (4).

21. The nuclear power generation control method according to claim 20, wherein, The method for controlling the amount of working fluid includes the following steps: Based on the deviation between the set value of the thermal properties of the working medium in the working medium tank (301) and the measured value of the thermal properties of the working medium in the working medium tank (301), feedback control is used to adjust the cooling water pipe bank (302) and the electric heating rod (303) to overcome the disturbance of the thermal properties of the working medium in the working medium tank (301) caused by the change of valve opening on the outlet pipeline (304) and the inlet pipeline (305) of the working medium filling control system.

22. The nuclear power generation control method according to claim 19, wherein, The bypass regulation control method includes the following steps: Based on the current load and valve opening-load curve, the valve openings on the turbine bypass line (107) and compressor bypass line (109) required under the variable load range are determined. The valves on the turbine bypass line (107) and compressor bypass line (109) are coarsely adjusted. Based on the load deviation between the current load and the required load, the valves on the turbine bypass line (107) are finely adjusted using feedback control. By changing the working fluid flow rate in the main power generation system, the output load of the generator (4) is ultimately changed.

23. The nuclear power generation control method according to claim 19, wherein, The throttling control method includes the following steps: Based on the current load and valve opening-load curve, the valve opening of the turbine inlet pipeline (110) required under the variable load range is determined. The valve on the turbine inlet pipeline (110) is coarsely adjusted, and based on the load deviation between the current load and the required load, the valve on the turbine inlet pipeline (110) is finely adjusted using feedback control. By changing the air intake of the turbine (3), the output load of the generator (4) is ultimately changed.

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