A lead bismuth cooled reactor thermostatic heating system and method

Abstract

The application provides a lead-bismuth cooling reactor constant-temperature heating system and method, relates to the technical field of reactor auxiliary heating, and comprises a pressure tank body, an insulation layer, a water-cooled induction coil assembly, a wide-frequency variable-frequency power supply unit, a water-cooled circulating heat exchange system, a temperature control system and a material parameter conversion module. Through closed-loop control of the temperature control system and automatic adaptation of the material parameter conversion module, the same system can be adapted to tank body equipment with different functional positions, pressure tank bodies with different materials and reactors with different power levels, lead-bismuth alloy melting, in-core heat supplement and whole-process integrated temperature control of storage and heat preservation are realized. Meanwhile, the system relies on the eddy current induction heating principle to make the pressure tank body itself generate heat through eddy current, and the heat is directly conducted to the lead-bismuth medium. Compared with the traditional resistance wire heating mode, the heat efficiency is significantly improved, the problems of easy burning and frequent maintenance and replacement of the resistance wire are avoided, and the annual operation energy consumption and maintenance cost of the high-power reactor are reduced.

Description

Technical Field

[0001] This invention relates to the field of reactor auxiliary heating technology, and more specifically, to a constant temperature heating system and method for a lead-bismuth cooled reactor. Background Technology

[0002] The operation of lead-bismuth cooled reactors involves multiple thermal management stages, including lead-bismuth alloy melting, maintaining constant temperature of the reactor medium, and fuel insulation. Currently, these stages generally employ resistance wire external heating, which has low thermal efficiency, is prone to heating element burnout, and requires frequent maintenance and replacement, resulting in high annual operating energy consumption and maintenance costs for high-power reactors.

[0003] While existing eddy current induction heating equipment has been applied in some industrial fields, it still has significant shortcomings for the special operating conditions of lead-bismuth cooled reactors. The existing equipment has a single heating structure and cannot be flexibly adjusted according to the differentiated heat requirements of different operating conditions such as melting, constant temperature, and heat preservation. This makes it difficult for the same equipment to be adapted to multiple application scenarios such as melting tanks, reactor main tanks, and storage tanks. In addition, the existing equipment has a fixed power level, making it difficult to adapt to commercial reactor types with different power levels through simple expansion. Furthermore, it lacks the ability to adapt to the electromagnetic properties of commonly used reactor steels and cannot be adapted to nuclear power pressure vessels or other T91 equipment represented by 316NG, 316L, and 15-15Ti.

[0004] Therefore, there is an urgent need to propose a constant-temperature heating system and method for lead-bismuth cooled reactors. Summary of the Invention

[0005] In order to overcome the above-mentioned technical problems, the purpose of this invention is to provide a constant temperature heating system and method for a lead-bismuth cooled reactor.

[0006] The objective of this invention can be achieved through the following technical solutions: A constant-temperature heating system for a lead-bismuth cooled reactor includes: Pressure tank body; An insulation layer that covers the outer wall of the pressure tank; The water-cooled induction coil assembly is located within the insulation layer and is divided into three independent heating zones along the axial direction of the pressure tank. Each of the three heating zones is electrically connected to an independent temperature acquisition unit and a power adjustment unit. The wide-frequency inverter power supply unit has its output terminals electrically connected to the power regulation units corresponding to the three heating zones, providing alternating current to the water-cooled induction coils of each heating zone; A water-cooled circulating heat exchange system is connected to the water-cooled induction coil assembly, and the water-cooled circulating heat exchange system is used to circulate and cool the water-cooled induction coil assembly. The temperature control system is electrically connected to the temperature acquisition unit, the wideband inverter power supply unit, and the three power regulation units respectively. The temperature control system is used to send frequency regulation commands to the wideband inverter power supply unit and power regulation commands to the power regulation units based on the temperature data collected by the temperature acquisition unit. The material parameter conversion module is electrically connected to the wide-frequency inverter power supply unit and the temperature control system. The material parameter conversion module has pre-stored electromagnetic parameter data of various nuclear power steels calibrated with reference materials. It is used to output the appropriate target operating frequency parameters and temperature control threshold parameters according to the material identification of the pressure tank.

[0007] As a further aspect of the present invention: the three heating zones include a top heat preservation heating zone, a middle constant temperature heating zone, and a bottom melting heating zone, which are axially distributed along the pressure tank body from top to bottom.

[0008] As a further aspect of the present invention: an insulating gap is left between the water-cooled induction coil assembly and the outer wall of the pressure tank.

[0009] As a further aspect of the present invention: the water-cooled induction coil assembly is made of hollow oxygen-free purple copper water-cooled copper tubes, and the water-cooled circulating heat exchange system is connected to the hollow oxygen-free purple copper water-cooled copper tubes of the three heating zones through external insulating pipes to form a closed water circulation loop.

[0010] As a further aspect of the present invention, the output frequency of the wideband variable frequency power supply unit is 50Hz to 3kHz.

[0011] As a further aspect of the present invention: a reactive power resonant compensation module is connected in parallel on the output bus of the wideband variable frequency power supply unit.

[0012] As a further aspect of the present invention, the wall thickness of the pressure vessel is 0.5mm to 35mm.

[0013] A method for isothermal heating of a lead-bismuth cooled reactor, based on the isothermal heating system for a lead-bismuth cooled reactor as described in any of the preceding claims, includes the following steps: S1: Input parameters based on the material, wall thickness and reactor power level of the pressure tank. Use the material parameter conversion module to retrieve the corresponding conversion coefficient based on 316NG steel, calculate the matching target operating frequency and temperature control threshold parameters, send the target operating frequency to the wideband variable frequency power supply unit, send the temperature control threshold parameters to the temperature control system, and complete the initialization of the whole machine parameters. S2: The water-cooled circulating heat exchange system is started first to establish a circulating cooling water path. The temperature control system detects the water cooling flow, temperature acquisition unit and line load status. Only after all self-tests are passed can the wideband inverter power supply combination switch be allowed to supply power. S3: Each heating zone has independent temperature control and works in coordination: S4: Execute the shutdown operation. The temperature control system gradually reduces the output power of each heating zone. After the power drops to zero, the wideband inverter power supply unit is shut down. The water-cooled circulating heat exchange system runs for a delay to continuously cool the water-cooled induction coil assembly which is in a high-temperature state. After the temperature of the water-cooled induction coil assembly drops to a safe range, the water-cooled circulating heat exchange system and the temperature control system are shut down in sequence.

[0014] As a further aspect of the present invention: In step S3, in the initial stage, the temperature control system sends a command to the power adjustment unit to make the bottom molten material heating zone work at full load, and use the eddy current effect to melt the solid lead-bismuth alloy. After the material is melted, the temperature control system switches the control strategy and sends commands through the three power adjustment units to maintain the medium constant temperature with the middle constant temperature heating zone as the core, so that the top heat preservation heating zone continues to operate at low power, and each heating zone independently controls the temperature and works in coordination.

[0015] As a further aspect of the present invention: when the system experiences abnormal operating conditions, the temperature control system activates a graded protection mechanism: for minor abnormalities, the power of the corresponding heating zone is automatically reduced; if the fault reaches the threshold, the main power supply circuit is immediately cut off, and an alarm is triggered and fault data is stored.

[0016] The beneficial effects of this invention include, but are not limited to: by independently setting up partitions for the water-cooled induction coil assembly, independently adjusting the power regulation unit, implementing closed-loop control of the temperature control system, and automatically adapting the material parameter conversion module, the same system can be adapted to tank equipment with different functional positioning, pressure tanks of different materials, and reactors of different power levels. This achieves integrated temperature control for the entire process of lead-bismuth alloy melting, in-core heat replenishment, and material storage insulation, solving the technical problems of limited application scenarios and poor material compatibility of existing equipment. At the same time, the system relies on the eddy current induction heating principle to generate heat by stimulating eddy currents within the pressure tank itself. The heat is directly conducted to the lead-bismuth medium, which significantly improves thermal efficiency compared to traditional resistance wire heating methods and avoids the problems of easy burnout and frequent maintenance and replacement of resistance wires, thereby reducing the annual operating energy consumption and maintenance costs of high-power reactors. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the constant temperature heating system for a lead-bismuth cooled reactor according to an embodiment of the present invention; Figure 2 This is a schematic diagram of the pressure tank, insulation layer, and three heating zones of the constant temperature heating system for the lead-bismuth cooled reactor according to an embodiment of the present invention. Figure 3 This is a schematic diagram of the winding of the water-cooled induction coil assembly of the constant temperature heating system for the lead-bismuth cooled reactor according to an embodiment of the present invention. Figure 4 This is a flowchart illustrating the steps of the isothermal heating method for a lead-bismuth cooled reactor according to an embodiment of the present invention.

[0018] Explanation of reference numerals in the attached diagram: 1. Pressure tank body; 2. Insulation layer; 3. Water-cooled induction coil assembly; 31. Top insulation heating zone; 32. Middle constant temperature heating zone; 33. Bottom melting heating zone; 4. Temperature acquisition unit; 5. Power regulation unit; 6. Wideband variable frequency power supply unit; 7. Water-cooled circulating heat exchange system; 8. Temperature control system; 9. Material parameter conversion module; 61. Reactive power resonant compensation module. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of this application clearer, specific embodiments of this application are described clearly and completely below with reference to the accompanying drawings. It should be understood that the described embodiments are only a part of the embodiments of this application, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments described in this application without creative effort will fall within the scope of protection of this application.

[0020] Unless otherwise defined, all technical and scientific terms used in this application have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used in the specification of this application is for the purpose of describing specific embodiments only and is not intended to limit this application; the terms "comprising," "including," "having," "containing," "comprise," etc., in the specification, claims, and accompanying drawings of this application are open-ended terms, indicating that a method comprises one or more steps, or an apparatus comprises one or more elements, but do not exclude the inclusion of other steps or elements. The terms "first," "second," etc., in the specification, claims, or accompanying drawings of this application are used to distinguish different objects, not to describe a specific order or primary / secondary relationship. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined with "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, unless otherwise stated, "a plurality of" means two or more.

[0021] In the description of this application, it should be understood that the terms "upper", "lower", "left", "right", "front", "rear", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0022] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," "linking," and "attachment" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal communication between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances. In this application, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. Additionally, in this application, the character " / " generally indicates that the preceding and following related objects have an "or" relationship.

[0023] See Figures 1-2 An embodiment of the present invention provides a constant-temperature heating system for a lead-bismuth cooled reactor, comprising: a pressure tank 1 containing a lead-bismuth medium; an insulation layer 2 covering the outer wall of the pressure tank 1 to reduce heat loss from the tank to the environment and lower heat loss; and a water-cooled induction coil assembly 3 disposed within the insulation layer 2, which is divided into three independent heating zones along the axial direction of the pressure tank 1. Each heating zone is independent, allowing for independent start-up, shutdown, and power adjustment, thereby enabling differentiated heating control based on the heat demand at different axial positions of the pressure tank 1. The three heating zones are electrically connected. It has an independent temperature acquisition unit 4 and a power regulation unit 5; a wide-frequency inverter power supply unit 6, with industrial power connected to the wide-frequency inverter power supply unit 6, and the output terminals of the wide-frequency inverter power supply unit 6 are electrically connected to the power regulation units 5 corresponding to the three heating zones, providing alternating current of the target operating frequency for the water-cooled induction coils of each heating zone; a water-cooled circulating heat exchange system 7, which is connected to the water-cooled induction coil assembly 3. That is, the water-cooled induction coils of multiple heating zones are respectively connected to the water-cooled circulating heat exchange system 7, which is used to circulate and cool the water-cooled induction coil assembly 3.

[0024] The constant temperature heating system for the lead-bismuth cooled reactor also includes a temperature control system 8, which is electrically connected to the temperature acquisition unit 4, the wideband inverter power supply unit 6, and three power regulation units 5. The temperature control system 8 sends frequency regulation commands to the wideband inverter power supply unit 6 and power regulation commands to the power regulation units 5 based on the temperature data acquired by the temperature acquisition unit 4. A material parameter conversion module 9, electrically connected to the wideband inverter power supply unit 6 and the temperature control system 8, pre-stores electromagnetic parameter data for various nuclear power steels calibrated with a reference material, and is used to calculate the electromagnetic parameters based on the pressure tank body. The material identification output of module 1 is adapted to the target operating frequency parameters and temperature control threshold parameters. The material parameter conversion module 9 has pre-stored electromagnetic parameter data of various nuclear power steels calibrated based on 316NG steel, and is compatible with 15-15Ti, 316, 316L, 304, 202, 309, 310S and T91 steels. The parameter conversion is completed based on the eddy current heating formula. This conversion method is well known to those skilled in the art. The material parameter conversion module has pre-stored the electromagnetic parameters and conversion coefficients of commonly used steels in nuclear reactors, which is used to realize the rapid adaptation of the operating parameters of tanks made of different materials.

[0025] Specifically, before system startup, the material parameter conversion module 9 obtains the target operating frequency and temperature control threshold parameters of the appropriate wide-frequency inverter power supply unit 6 based on its preset data and the material identification of the pressure tank 1. The material parameter conversion module 9 sends the target operating frequency to the wide-frequency inverter power supply unit 6 and the temperature control threshold parameters to the temperature control system 8, completing the initialization of the overall parameters. Subsequently, the water-cooled circulating heat exchange system 7 starts first, establishing a circulating cooling water path. The wide-frequency inverter power supply unit 6 outputs an alternating current at the target frequency according to the appropriate target operating frequency, which is distributed to the water-cooled induction coils of the corresponding heating zones through each power adjustment unit 5. The alternating magnetic field generated by the coil penetrates the wall of the pressure tank 1, causing the tank itself to generate eddy currents and heat up. The heat is directly conducted to the internal lead-bismuth medium, achieving heating. The temperature control system 8 collects the temperature data of each zone in real time, sends frequency adjustment commands to the wide-frequency inverter power supply unit 6, and sends power adjustment commands to the power adjustment units 5, performing independent temperature control for each heating zone.

[0026] In this embodiment, through the independent partitioning of the water-cooled induction coil assembly 3, the independent adjustment of the power adjustment unit 5, the closed-loop control of the temperature control system 8, and the automatic adaptation of the material parameter conversion module 9, the same system can adapt to tank equipment with different functional positioning, pressure tanks 1 of different materials, and reactors of different power levels. This achieves integrated temperature control for the entire process of lead-bismuth alloy melting, in-core heat replenishment, and material storage insulation, solving the technical problems of limited application scenarios and poor material compatibility of existing equipment. Simultaneously, relying on the eddy current induction heating principle, the system generates heat by inducing eddy currents within the pressure tank 1 itself. This heat is directly conducted to the lead-bismuth medium, significantly improving thermal efficiency compared to traditional resistance wire heating methods. Furthermore, it avoids the problems of easy burnout of resistance wires and frequent maintenance and replacement, reducing the annual operating energy consumption and maintenance costs of high-power reactors.

[0027] See Figures 1-3 Optionally, the three heating zones include a top heat preservation heating zone 31, a middle constant temperature heating zone 32, and a bottom melting heating zone 33, which are distributed axially from top to bottom along the pressure tank 1.

[0028] In this embodiment, the top heat preservation heating zone 31 is located at the top of the pressure tank 1 along the axis. Due to its proximity to the tank opening or top structure, this area has a fast heat dissipation rate and is prone to lead-bismuth medium condensation and solidification. The top heat preservation heating zone 31 operates continuously at low power, maintaining the top temperature through low-power eddy current heating to prevent medium condensation. The middle constant temperature heating zone 32 is located in the middle of the pressure tank 1 along the axis and is the main heating area of ​​the system. During the constant temperature operation phase, it undertakes the core task of maintaining the constant temperature of the medium. The wide-frequency variable frequency power supply unit 6 slightly adjusts the output frequency and power according to the real-time load of the reactor, and uses the eddy current effect to achieve uniform heat penetration of the tank, ensuring uniform temperature of the entire tank. The bottom melting heating zone 33 is located at the bottom of the pressure tank 1 along the axis. During the initial heating phase, it undertakes the task of high-load melting. Alternating current forms a strong alternating magnetic field around the bottom coil. The magnetic field penetrates the wall of the pressure tank 1, causing eddy currents to be generated at the bottom of the tank and rapidly heating up. The heat is conducted from the tank wall to the internal solid lead-bismuth alloy, completing the material melting operation.

[0029] Specifically, during the initial stage of system operation, the bottom molten material heating zone 33 operates at full load, using the eddy current effect to melt the solid lead-bismuth alloy. After the material is melted, the system switches operating conditions, maintaining the medium constant temperature with the middle constant temperature heating zone 32 as the core, while the top heat preservation heating zone 31 continues to operate at low power. The three zones independently control temperature and work together.

[0030] Furthermore, the three heating zones are distributed axially from top to bottom, matching the temperature gradient characteristics in the actual operation of the lead-bismuth cooled reactor. This forms an axial temperature field distribution with melting at the bottom, constant temperature in the middle, and heat preservation at the top. This allows the system to flexibly combine the working modes of each zone according to the differentiated heat requirements of different working conditions such as melting, reheating, and heat preservation, enabling the same equipment to be adapted to various application scenarios such as melting tanks, reactor main tanks, and storage tanks.

[0031] See Figures 1-3 Optionally, an insulation gap is left between the water-cooled induction coil assembly 3 and the outer wall of the pressure tank 1, and a high-temperature resistant, insulating, and flame-retardant protective layer is provided on the outside of the water-cooled induction coil.

[0032] In this embodiment, the insulation gap is used to prevent an electrical short circuit between the water-cooled induction coil assembly 3 and the pressure tank 1, and to prevent the coil heat from being directly conducted to the tank, causing localized overheating. Preferably, the insulation gap is 55mm.

[0033] Optionally, the water-cooled induction coil assembly 3 is made of hollow oxygen-free copper water-cooled tubes, and the water-cooled circulating heat exchange system 7 is connected to the hollow oxygen-free copper water-cooled tubes of the three heating zones through external insulating pipes to form a closed water circulation loop.

[0034] In this embodiment, the cooling water circulates only inside the coil and does not come into contact with the pressure tank 1 and its internal lead-bismuth medium, continuously cooling all the induction coils. Preferably, the hollow oxygen-free purple copper water-cooled copper pipe has a specification of Φ14×1.5mm.

[0035] Optionally, the output frequency of the wideband variable frequency power supply unit 6 is 50Hz to 3kHz. The eddy current penetration depth corresponding to this frequency range matches the wall thickness of the pressure tank 1 commonly used in lead-bismuth cooled reactors. When the frequency is too low, the eddy current penetration depth is too large, and energy dispersion leads to reduced heating efficiency; when the frequency is too high, the skin effect is significant, and eddy currents concentrate on the surface of the tank, resulting in a large temperature difference between the inside and outside and uneven heating. In this embodiment, the output frequency of the wideband variable frequency power supply unit 6 is steplessly adjustable within the range of 50Hz to 3kHz, adapting to pressure tanks 1 with different wall thicknesses and materials. The wall thickness of the pressure tank 1 is 0.5~35mm, and preferably 15~20mm.

[0036] See Figure 1 Optionally, a reactive power resonant compensation module 61 is connected in parallel to the output bus of the wideband inverter power supply unit 6. The reactive power resonant compensation module 61 is connected between the power supply terminal and the induction coil load to perform reactive power compensation and resonant state matching for the induction heating main circuit in real time. In this embodiment, the water-cooled induction coil assembly 3 is a typical inductive load, generating inductive reactive power during operation. The reactive power resonant compensation module 61 cancels the inductive reactive power through capacitive reactive power, improving the system power factor and reducing the load current of the power supply line and the wideband inverter power supply unit 6. The reactive power resonant compensation module 61 can also match the resonant state of the heating circuit according to the output frequency of the wideband inverter power supply unit 6 and the coil load characteristics, ensuring the circuit operates near the optimal resonant point and reducing energy loss. Simultaneously, the reactive power resonant compensation module 61 absorbs and suppresses high-order harmonic currents in the circuit, balances the three-phase load, buffers voltage fluctuations, and protects the wideband inverter power supply unit 6 and the coil insulation structure. It should be noted that the above-mentioned reactive power compensation, resonant matching, harmonic suppression, and overvoltage protection functions can be implemented using conventional wideband resonant compensation circuits in the art, and their specific circuit topology and parameter configurations are conventional techniques in this field.

[0037] Preferably, the pressure vessel 1 can be a lead-bismuth alloy melting vessel, a reactor main vessel, a medium storage vessel, or other types of vessel equipment.

[0038] Preferably, the constant temperature heating system for lead-bismuth cooled reactors is compatible with 0.5MWt and 1.0MWt power-class lead-bismuth cooled reactors, and can be extended to lead-bismuth cooled reactors with power classes of 2MWt, 5MWt, 10MWt and larger, without requiring any changes to the core structure of the system when expanding its application.

[0039] See Figures 1-4 Another embodiment of the present invention also provides a method for isothermal heating of a lead-bismuth cooled reactor, based on the isothermal heating system of a lead-bismuth cooled reactor as described in any of the preceding claims, comprising the following steps: S1: Input parameters based on the material, wall thickness and reactor power level of the pressure tank 1. Use the material parameter conversion module 9 to retrieve the corresponding conversion coefficient based on 316NG steel, calculate the matching target operating frequency and temperature control threshold parameters, send the target operating frequency to the wideband variable frequency power supply unit 6, and send the temperature control threshold parameters to the temperature control system 8 to complete the initialization of the whole machine parameters. This step enables the same system to quickly switch to the optimal operating parameters of different material tanks without manual setting of each item, and can adapt to pressure tanks 1 of different materials. S2: The water-cooled circulating heat exchange system 7 is started first to establish a circulating cooling water path. The temperature control system 8 detects the water cooling flow, temperature acquisition unit 4 and line load status. Only after all items pass the self-test can the wide frequency inverter power supply unit 6 be switched on to supply power. S3: Each heating zone is independently temperature-controlled and works collaboratively. During the heating process, the reactive power resonant compensation module 61 dynamically completes reactive power compensation and resonant tuning. S4: Execute the shutdown operation. The temperature control system 8 gradually reduces the output power of each heating zone. After the power drops to zero, the wide-frequency inverter power supply unit 6 is shut down. The water-cooled circulating heat exchange system 7 runs for a delay to continuously cool the water-cooled induction coil assembly 3, which is in a high-temperature state. After the temperature of the water-cooled induction coil assembly 3 drops to a safe range, the water-cooled circulating heat exchange system 7 and the temperature control system 8 are shut down in sequence. That is, the water-cooled circulating system 7 and other equipment in the system are shut down in sequence until the temperature control system 8 is shut down.

[0040] Specifically, when the temperature acquisition unit 4 of a certain heating zone detects that the temperature of the pressure tank 1 is higher than the preset temperature control threshold of that zone, the temperature signal is fed back to the temperature control system 8 in real time via the signal line. The temperature control system 8 first compares the deviation between the current temperature and the target temperature. If the deviation is in the slightly over-temperature range, it sends a power reduction command to the power adjustment unit 5 corresponding to that zone, reducing the output power allocation ratio of the wide-frequency inverter power supply unit 6 to the coil of that zone. If the temperature continues to rise and reaches the severe over-temperature threshold, the temperature control system 8 immediately cuts off the power supply signal of the power adjustment unit 5 of that zone, and links the reactive power resonant compensation module 61 to adjust the resonance state to match the remaining load, while triggering an alarm and storing fault data.

[0041] When the temperature acquisition unit 4 detects that the temperature of the pressure tank 1 is lower than the preset temperature control threshold for that zone, the temperature signal is also fed back to the temperature control system 8 in real time. After calculating the temperature deviation, the temperature control system 8 sends a power increase command to the power adjustment unit 5 corresponding to that zone to increase the output power distribution of the wide-frequency inverter power supply unit 6 to the coil of that zone. If the temperature deviation is large, the temperature control system 8 also sends a frequency adjustment command to the wide-frequency inverter power supply unit 6 to adjust the output frequency in the range of 50Hz to 3kHz to adapt to the current heating demand. After the temperature returns to the target range, the temperature control system 8 dynamically fine-tunes the power and frequency through closed-loop control to stabilize the temperature of that zone near the set value.

[0042] In this embodiment, the water-cooled circulating heat exchange system 7 is started first in step S2 to ensure a stable cooling cycle is established before the water-cooled induction coil assembly 3 is energized, preventing the coil from overheating and being damaged due to insufficient cooling. The temperature control system 8 performs a full-item test on the water cooling flow rate, temperature acquisition unit 4, and line load status. Only when all tests are qualified will it output a signal to allow closing, avoiding safety hazards caused by starting the equipment with a fault. It should be noted that the above-mentioned water cooling flow rate detection can be achieved by configuring a flow detection device in the water-cooled circulating heat exchange system 7, and its detection signal is connected to the temperature control system 8 through a signal connection. The line load status detection can be achieved by detecting the impedance characteristics of the output circuit of the power adjustment unit 5 and the wide-frequency inverter power supply unit 6 to determine whether there is a short circuit, open circuit, or grounding abnormality. The above detection methods and signal connections are conventional technical means in the field of industrial control.

[0043] In the S3 zone heating operation, the temperature control system 8 sends power adjustment commands to the corresponding power adjustment unit 5 and frequency adjustment commands to the wide-frequency inverter power supply unit 6 based on the data fed back by the temperature acquisition unit 4 of each zone, forming an axial temperature field distribution with bottom melting, middle constant temperature, and top heat preservation, so as to realize independent temperature control and collaborative operation of each heating zone.

[0044] Step S4, which involves gradually reducing the output power of each heating zone during shutdown, avoids the thermal stress impact on the coils and the sudden temperature change of the lead-bismuth medium caused by a sudden power outage. The water-cooled circulating heat exchange system 7 operates with a delay to continuously cool the induction coils under high temperature conditions. Once the coil temperature drops to a safe range, each system is shut down sequentially to prevent residual heat accumulation in the coils from causing insulation aging or damage, thus extending the service life of the equipment. In summary, this method achieves fully automated control of the constant temperature heating process of the lead-bismuth cooled reactor through the organic coordination of four steps: parameter configuration, pre-start self-test, zoned heating operation, and normal shutdown. This not only ensures the safety and stability of the system operation but also improves the ease of operation and the service life of the equipment.

[0045] Optionally, in step S3, in the initial stage, the temperature control system 8 sends a command to the power adjustment unit 5 to make the bottom molten material heating zone 33 work at full load, using the eddy current effect to melt the solid lead-bismuth alloy. After the material is melted, the temperature control system 8 switches the control strategy and sends commands through the three power adjustment units 5 to maintain the medium constant temperature with the middle constant temperature heating zone 32 as the core, and the top heat preservation heating zone 31 continuously operates at low power throughout the process. Each heating zone independently controls the temperature and works in coordination.

[0046] In this implementation, the above operations achieve automatic switching from molten material to constant temperature. The high-load melting at the bottom solves the agglomeration problem, the main constant temperature in the middle ensures stable operation, and the low-power insulation at the top prevents condensation. The three zones work together to form a reasonable axial temperature field distribution that matches the actual operating requirements of the lead-bismuth reactor. This solves the technical problem that existing equipment cannot simultaneously adapt to multiple operating conditions such as molten material, reheating, and insulation.

[0047] Optionally, when the system encounters abnormal operating conditions, the temperature control system 8 activates a graded protection mechanism: for minor abnormalities, the power of the corresponding heating zone is automatically reduced; if the fault reaches the threshold, the main power supply circuit is immediately cut off, and an alarm is triggered and the fault data is stored.

[0048] While the present invention has been disclosed above, its scope of protection is not limited thereto. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention, and all such changes and modifications will fall within the scope of protection of the present invention.

Claims

1. A constant-temperature heating system for a lead-bismuth cooled reactor, characterized in that, include: Pressure tank (1); The insulation layer (2) covers the outer wall of the pressure tank (1); The water-cooled induction coil assembly (3) is located in the insulation layer (2) and is divided into three independent heating zones along the axial direction of the pressure tank (1). The three heating zones are electrically connected to independent temperature acquisition units (4) and power adjustment units (5). The wide-frequency inverter power supply unit (6) has its output terminal electrically connected to the power regulation unit (5) corresponding to the three heating zones, providing alternating current to the water-cooled induction coils of each heating zone; A water-cooled circulating heat exchange system (7) is connected to the water-cooled induction coil assembly (3). The water-cooled circulating heat exchange system (7) is used to circulate and cool the water-cooled induction coil assembly (3). The temperature control system (8) is electrically connected to the temperature acquisition unit (4), the wide-frequency inverter power supply unit (6), and the three power adjustment units (5). The temperature control system (8) is used to send frequency adjustment commands to the wide-frequency inverter power supply unit (6) and power adjustment commands to the power adjustment units (5) based on the temperature data collected by the temperature acquisition unit (4). Material parameter conversion module (9) is electrically connected to the wide frequency inverter power supply unit (6) and the temperature control system (8). The material parameter conversion module (9) has pre-stored electromagnetic parameter data of various nuclear power steels calibrated with reference materials. It is used to output the appropriate target working frequency parameters and temperature control threshold parameters according to the material identification of the pressure tank (1).

2. The constant-temperature heating system for a lead-bismuth cooled reactor according to claim 1, characterized in that, The three heating zones include a top heat preservation heating zone (31), a middle constant temperature heating zone (32), and a bottom melting heating zone (33) that are axially distributed from top to bottom along the pressure tank body (1).

3. The constant-temperature heating system for a lead-bismuth cooled reactor according to claim 2, characterized in that, An insulation gap is left between the water-cooled induction coil assembly (3) and the outer wall of the pressure tank (1).

4. The constant-temperature heating system for a lead-bismuth cooled reactor according to claim 3, characterized in that, The water-cooled induction coil assembly (3) is made of hollow oxygen-free purple copper water-cooled copper tubes. The water-cooled circulating heat exchange system (7) is connected to the hollow oxygen-free purple copper water-cooled copper tubes of the three heating zones through external insulating pipes to form a closed water circulation loop.

5. The constant-temperature heating system for a lead-bismuth cooled reactor according to claim 1, characterized in that, The output frequency of the wideband variable frequency power supply unit (6) is 50Hz to 3kHz.

6. The constant-temperature heating system for a lead-bismuth cooled reactor according to claim 1, characterized in that, A reactive resonant compensation module (61) is connected in parallel on the output bus of the wideband variable frequency power supply unit (6).

7. The constant-temperature heating system for a lead-bismuth cooled reactor according to claim 1, characterized in that, The wall thickness of the pressure tank (1) is 0.5~35mm.

8. A method for isothermal heating of a lead-bismuth cooled reactor, based on the isothermal heating system for a lead-bismuth cooled reactor as described in any one of claims 1-7, characterized in that, The steps include the following: S1: Input parameters based on the material, wall thickness and reactor power level of the pressure tank (1), retrieve the corresponding conversion coefficient based on 316NG steel through the material parameter conversion module (9), calculate the matching target working frequency and temperature control threshold parameters, send the target working frequency to the wide frequency converter power supply unit (6), send the temperature control threshold parameters to the temperature control system (8), and complete the initialization of the whole machine parameters; S2: The water-cooled circulating heat exchange system (7) is started first to establish a circulating cooling water path. The temperature control system (8) detects the water cooling flow, temperature acquisition unit (4) and line load status. Only after all items pass the self-inspection can the wide frequency inverter power supply unit (6) be switched on to supply power. S3: Each heating zone has independent temperature control and works in coordination: S4: Execute the shutdown operation. The temperature control system (8) gradually reduces the output power of each heating zone. After the power drops to zero, the wide-frequency inverter power supply unit (6) is shut down. The water-cooled circulating heat exchange system (7) runs for a delay to continuously cool the water-cooled induction coil assembly (3) which is in a high-temperature state. After the temperature of the water-cooled induction coil assembly (3) drops to a safe range, the water-cooled circulating heat exchange system (7) and the temperature control system (8) are shut down in sequence.

9. The isothermal heating method for a lead-bismuth cooled reactor according to claim 8, characterized in that, In step S3, in the initial stage, the temperature control system (8) sends a command to the power adjustment unit (5) to make the bottom melting heating zone (33) work at full load and use the eddy current effect to melt the solid lead-bismuth alloy. After the material is melted, the temperature control system (8) switches the control strategy and sends a command through the three power adjustment units (5) to maintain the medium constant temperature with the middle constant temperature heating zone (32) as the core, so that the top heat preservation heating zone (31) continues to operate at low power. Each heating zone independently controls the temperature and works together.

10. The isothermal heating method for a lead-bismuth cooled reactor according to claim 8, characterized in that, When the system encounters an abnormal operating condition, the temperature control system (8) activates a graded protection mechanism: for minor abnormalities, the power of the corresponding heating zone is automatically reduced; if the fault reaches the threshold, the main power supply circuit is immediately cut off, and an alarm is triggered and the fault data is stored.

Images