Method and system for steady-state simulation of different working conditions of nuclear energy heat exchange loop model
By adjusting the heat exchanger structure and loop parameters, the problem of performance variation of the heat exchanger under varying operating conditions was solved, and accurate simulation of nuclear energy heat exchange loops under different operating conditions was achieved, thus improving the reliability of the design.
Patent Information
- Application Number
- CN202510959296.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-07-11
- Publication Date
- 2025-11-21
AI Technical Summary
Existing nuclear energy heat exchange loop design and simulation methods fail to effectively consider the changes in heat exchange performance of heat exchangers under varying operating conditions, resulting in significant differences between simulation results and actual performance.
By determining whether the heat exchanger's heat exchange area and heat load meet the design requirements, and adjusting the heat exchanger structure, loop flow rate, and heating extraction rate based on the determination results until the design requirements are met, simulation is performed in conjunction with operating parameters.
It enables accurate simulation of nuclear energy heat exchange circuits under different operating conditions, improving the reliability and accuracy of the design.
Smart Images
Figure CN120995653A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of nuclear power steam supply technology, and in particular relates to a method and system for steady-state simulation of nuclear heat exchange loop models under different operating conditions. Background Technology
[0002] To ensure the safe and stable operation of the nuclear reactor, the heat exchange loop needs to be designed, taking into account not only the rated operating conditions, but also the possible variable load conditions and accident conditions.
[0003] Current heat exchanger loop design and simulation methods are based on thermal equilibrium, without taking into account the heat exchanger's performance under varying operating conditions. Since the heat exchanger is designed according to rated operating conditions and its structure remains unchanged, its heat exchange performance will change when it operates at flow rates and temperatures other than those in the design conditions. This may cause the simulation or calculation based on thermal equilibrium to differ significantly from the actual performance of the heat exchanger. Summary of the Invention
[0004] To address the aforementioned problems, this invention proposes a steady-state simulation method and system for nuclear energy heat exchange loop models under different operating conditions. First, it determines whether the heat exchanger's heat exchange area meets the required area and whether the heat exchanger's heat load reaches the design heat load. Then, it determines whether the fluid outlet temperature after heat exchange meets the design requirements. Based on the determination results, the heat exchanger structure, loop flow rate, and / or heating extraction rate are adjusted until the requirements are met. The simulation considers relevant heat exchanger data and operating parameters, enabling accurate simulation of the heat exchange loop operation under different conditions, thus supporting the reliability of heat exchange loop design.
[0005] To achieve the above objectives, the present invention is implemented through the following technical solution: In a first aspect, the present invention provides a method for steady-state simulation of a nuclear energy heat exchange loop model under different operating conditions, including: Obtain design operating parameters and relevant data for the heat exchanger; Simulate the nuclear energy heat exchange loop model corresponding to the operating parameters and heat exchanger-related data; Determine whether the heat exchanger's heat exchange area is sufficient to meet the required heat exchange area, and whether the heat exchanger's heat load meets the design heat load; if so, determine whether the fluid outlet temperature after heat exchange meets the design requirements; otherwise, adjust the heat exchanger structure, loop flow rate, and / or heating extraction rate, and perform the simulation again. If the outlet temperature of the fluid after heat exchange meets the design requirements, the simulation is complete; otherwise, continue to adjust the loop flow rate or the heating and pumping rate until the outlet temperature of the fluid after heat exchange meets the design requirements.
[0006] Furthermore, the design operating parameters include one or more of the following: inlet and outlet temperatures, flow rate, and pressure.
[0007] Furthermore, the relevant data for heat exchangers include the number of heat exchangers in operation and / or the heat transfer coefficient of the heat exchangers.
[0008] Furthermore, when the reactor load percentage is greater than the first preset percentage, three sets of heat exchangers are put into operation in parallel; when the load decreases to the second preset percentage, two sets of heat exchangers are put into operation in parallel; when the load decreases to the third preset percentage, only one set of heat exchangers is put into operation; at the same time, the secondary loop bypass is activated to adjust the flow rate through the heat exchanger set and adjust the heating steam quantity according to the operating conditions; the first preset percentage is greater than the second preset percentage, and the second preset percentage is greater than the third preset percentage.
[0009] Furthermore, when the reactor load is reduced to the first preset percentage, the inlet temperature and flow rate of the secondary loop change, the secondary loop bypass is activated, so that part of the secondary loop flow does not pass through the heat exchanger and eventually merges with the heat exchanged medium and returns to the reactor; at the same time, the heating pumping rate is reduced.
[0010] Furthermore, when the reactor load is reduced to the second preset percentage, only two sets of heat exchangers are put into operation. The inlet and outlet temperatures and heat exchange flow rates of the secondary loop change, the bypass flow rate of the secondary loop is increased, the heating extraction rate is further reduced, and the flow rate of the tertiary loop is reduced.
[0011] Secondly, the present invention also provides a steady-state simulation system for different operating conditions of a nuclear energy heat exchange loop model, comprising: The data acquisition module is configured to acquire design operating parameters and heat exchanger-related data. The simulation startup module is configured to simulate the nuclear energy heat exchange loop model corresponding to the operating parameters and heat exchanger-related data. The first adjustment module is configured to: determine whether the heat exchange area of the heat exchanger can meet the required heat exchange area, and whether the heat load of the heat exchanger reaches the design heat load; if it meets the requirements, determine whether the outlet temperature of the fluid after heat exchange can meet the design requirements; otherwise, adjust the heat exchanger structure, loop flow rate and / or heating extraction rate, and perform simulation again. The second adjustment module is configured to: complete the simulation if the outlet temperature of the fluid after heat exchange meets the design requirements; otherwise, continue to adjust the loop flow rate or the heating pumping rate until the outlet temperature of the fluid after heat exchange meets the design requirements.
[0012] Thirdly, the present invention also provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the steps of the steady-state simulation method for different operating conditions of the nuclear energy heat exchange loop model described in the first aspect.
[0013] Fourthly, the present invention also provides an electronic device, including a memory, a processor, and a computer program stored in the memory and capable of running on the processor, wherein the processor executes the program to implement the steps of the steady-state simulation method for different operating conditions of the nuclear energy heat exchange loop model described in the first aspect.
[0014] Fifthly, the present invention also provides a computer program product, the computer program product comprising a computer program, which, when executed by a processor, implements the steps of the steady-state simulation method for different operating conditions of the nuclear energy heat exchange loop model described in the first aspect.
[0015] Compared with the prior art, the beneficial effects of the present invention are as follows: When simulating a nuclear energy heat exchange loop model, this invention first determines whether the heat exchanger's heat exchange area meets the required area and whether the heat exchanger's heat load reaches the design heat load. Then, it determines whether the fluid outlet temperature after heat exchange meets the design requirements. Based on the results, the heat exchanger structure, loop flow rate, and / or heating extraction rate are adjusted until the requirements are met. The model considers relevant heat exchanger data and operating parameters, enabling accurate simulation of the heat exchange loop operation under different operating conditions, thus providing support for the reliability of heat exchange loop design. Attached Figure Description
[0016] The accompanying drawings, which form part of this embodiment, are used to provide a further understanding of this embodiment. The illustrative embodiments and their descriptions are used to explain this embodiment and do not constitute an improper limitation of this embodiment.
[0017] Figure 1 This is a schematic diagram of the method flow of the present invention; Figure 2 This is a schematic diagram of the simulation results under the design operating parameters of Embodiment 1 of the present invention; Figure 3 This is a schematic diagram of the simulation results of adjusting the heating steam extraction rate to 2 kg / s in Embodiment 1 of the present invention; Figure 4 This is a schematic diagram of the simulation results of Embodiment 1 of the present invention; Figure 5 This is a schematic diagram of the simulation results of adjusting the heating steam rate to 1.8 kg / s in Embodiment 1 of the present invention; Figure 6 This is a schematic diagram of the simulation results when the nuclear reactor load is reduced to 75% in Embodiment 1 of the present invention; Figure 7 This is a schematic diagram of the simulation results when the nuclear reactor load is reduced to 50% in Embodiment 1 of the present invention. Detailed Implementation
[0018] The present invention will be further described below with reference to the accompanying drawings and embodiments.
[0019] It should be noted that the following detailed descriptions are exemplary and intended to provide further explanation of this application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains.
[0020] Nuclear energy, with its cleanliness, high efficiency, and technological scalability, is an important option for optimizing the energy structure and ensuring energy security. It is particularly suitable as a baseload power source to support grid stability and facilitate the low-carbon transformation of energy-intensive industries. Using nuclear power to generate steam can supplement or even replace fossil fuels in heating, industrial applications, and power generation. However, ensuring the safe and stable operation of a nuclear reactor requires the design of its heat exchange circuits, which must consider not only rated operating conditions but also potential variable load conditions and accident scenarios, and must be designed and simulated.
[0021] Existing design and simulation methods are based on thermal equilibrium and do not take into account the heat exchanger's performance under varying operating conditions. Since the heat exchanger is designed for rated operating conditions with a fixed structure, its heat exchange performance will change when operating at flow rates and temperatures other than the design conditions. This may cause the simulation or calculation based on thermal equilibrium to differ significantly from the actual performance of the heat exchanger.
[0022] The nuclear energy heat exchange loop model in this invention is used for heat exchange between the secondary and tertiary loops, heating the demineralized water in the tertiary loop into superheated steam. The heat exchange loop model mainly includes a preheater module, a deaerator module, a tertiary loop pressurization pump module, an evaporator module, a superheater module, a first splitting module B7, a merging module B8, and a second splitting module B9. The first splitting module B7 and the second splitting module B9 can divide a single stream into multiple streams, and the merging module B8 can merge multiple streams into a single stream.
[0023] The preheater module represents the preheater in the heat exchange loop, which preheats the demineralized water in the three loops. It can represent one or more preheaters operating in parallel or in series.
[0024] The deaerator module represents a deaerator in a heat exchange circuit. It uses heating steam to heat the demineralized water to saturation temperature, reducing the dissolved oxygen content in the water. It can represent one or more deaerators.
[0025] The three-loop pressurization pump module represents the pressurization pump in the loop, and its function is to increase the pressure in the three loops. The module can represent one or more pumps.
[0026] The evaporator module represents a kettle evaporator in the loop, which heats the water in the three loops to saturated steam. The module can represent one or more kettle evaporators operating in series or in parallel.
[0027] The superheater module represents the superheater in the loop, and its function is to heat the saturated steam in the three loops to superheated steam. The module can represent one or more evaporators operating in series or in parallel.
[0028] Optionally, the workflow of the heat exchange loop model includes: The demineralized water from the third loop enters the preheater module (loop 1), is heated by the high-temperature, high-pressure water from the second loop (loop 9), and then enters the deaerator module. In the deaerator, the third loop water mixes with the heating steam to become saturated water, which is then pressurized by the third loop booster pump and sent to the evaporator. In the evaporator, the saturated water is heated to saturated steam by the high-temperature, high-pressure water from the second loop, while a small portion of the saturated water is discharged as blowdown. The saturated steam enters the superheater and is heated to superheated steam by the high-temperature, high-pressure water from the second loop. The superheated steam is used for turbine power generation or heating the feedwater to the heating network, and a portion of the superheated steam is returned to the deaerator as heating steam to heat the demineralized water.
[0029] The high-temperature, high-pressure water from the secondary loop enters through stream 13 and is divided into two streams depending on the system operation. One stream serves as a secondary loop bypass without passing through the heat exchange loop, while the other stream enters the heat exchange loop to exchange heat and lower the temperature. It then enters the superheater through stream 7 for heat exchange, then enters the evaporator module for heat exchange, and finally enters the preheater for heat exchange. After exiting the preheater, it mixes with the secondary loop bypass and returns to the secondary loop through stream 15 to continue exchanging heat and dissipating the reactor heat.
[0030] When the reactor load changes, the operation of the heat exchange loop is adjusted accordingly. When the reactor load is high (100% load or 75% (first preset percentage) load), three sets of heat exchangers operate in parallel with equal flow distribution. When the load decreases to 50% (second preset percentage), two sets of heat exchangers operate in parallel with equal flow distribution. When the load decreases to 25% or 15% (third preset percentage), only one set of heat exchangers operates. Simultaneously, depending on the operating conditions, the secondary loop bypass is activated to adjust the flow rate through the heat exchanger group and the heating extraction rate. Since the heat exchangers are designed for rated operating conditions and their structure remains unchanged, their heat exchange performance will change when operating at flow rates and temperatures outside of the design conditions. The purpose of this invention is to provide a simulation method for the heat exchange loop, incorporating the geometry of the heat exchanger or its heat exchange performance under varying operating conditions into the process simulation to achieve accurate simulation of the heat exchange system operating under different conditions, thus supporting the reliability of the heat exchange loop design.
[0031] like Figure 1 As shown, the steady-state simulation method for nuclear energy heat exchange loop models under different operating conditions provided by this invention substitutes the geometry of the heat exchanger or the heat exchange performance of the heat exchanger under varying operating conditions into the process simulation, achieving accurate simulation of the heat exchange system operating under different conditions and providing support for the reliability of heat exchange loop design; the method includes: S1. Input the inlet and outlet temperatures, flow rates, pressures, and other parameters of the design conditions into the model to complete the thermal balance simulation.
[0032] S2. Input the structural parameters of the heat exchanger, including the shell inner diameter, number of tubes, arrangement, number and spacing of baffles, etc., to determine the number and mode of operation of the heat exchanger. Alternatively, you can input parameters such as the heat transfer coefficient, heat transfer area, or heat load, which can be obtained through experiments or simulations.
[0033] S3. Conduct a verification operation to check whether the heat exchanger can meet the requirements. For example, whether the actual heat exchange area of the heat exchanger can meet the required heat exchange area, and whether the heat load of the heat exchanger reaches the design heat load.
[0034] If the requirements are not met, adjust the heat exchanger structure or the loop flow rate and temperature, and perform the verification calculation again.
[0035] If the requirements are met, switch to simulation mode for operation.
[0036] S4. Determine whether the outlet temperature of the fluid after heat exchange meets the design requirements and is within an acceptable range.
[0037] If the requirements are not met, adjust the loop flow rate or the heating extraction rate, and run the simulation again.
[0038] If the conditions are met, the simulation for this working condition is complete, and simulations for other working conditions can be performed.
[0039] Example 1: This embodiment provides a steady-state simulation method for a nuclear energy heat exchange loop model under different operating conditions, specifically including: like Figure 2 As shown, the design parameters are input into the model: Third-loop demineralized water inlet temperature 25℃, 1330kPa, flow rate 72.65kg / s. Third-loop steam parameters: at least 230℃, 1500kPa, flow rate 72.65kg / s; Second-loop high-temperature, high-pressure water inlet temperature 248℃, 12500kPa, 733.33kg / s; Second-loop water outlet temperature 188℃. Heating steam flow rate is set to 0kg / s.
[0040] The structural parameters of the heat exchangers are input into the heat exchanger module. For example, the preheater is a BEU type with a shell inner diameter of 1250mm, 2712 tubes, and double-baffle design. The two heat exchangers operate in parallel with equal flow distribution. Verification calculations reveal that the preheater's heat load is high, and the existing structural design cannot meet the heat exchange requirements. The outlet temperature is also high, reaching 191.46℃. The deaerator requires heat input to heat the demineralized water, necessitating adjustment of the heating extraction rate.
[0041] like Figure 3As shown, the heating steam extraction rate was adjusted to 2 kg / s. The outlet temperature of the preheater's third loop decreased to 179.15℃, which is significantly lower than the saturation temperature of 191.61℃, eliminating the risk of vaporization. The deaerator heat load was negative, indicating that no additional heat input was required. The preheater area margin was 6.66%, sufficient to meet the heat load requirements. Simulation can be performed.
[0042] like Figure 4 As shown, the simulation results show that the outlet temperature of the second loop is 186.96℃ and the outlet steam temperature of the third loop is 236.79℃. The heat load of the evaporator and superheater is higher than that under the verification mode. This is because the area margin of the evaporator and superheater is large, which leads to a certain difference between the simulation results and the verification results. Therefore, the heating steam extraction rate is adjusted to keep the inlet and outlet temperatures and the heat load of the heat exchanger within an acceptable range.
[0043] like Figure 5 As shown, the heating air extraction rate was adjusted to 1.8 kg / s, and the simulation was run again. The outlet water temperature of the secondary loop was 187.22℃, which is less than 1℃ different from the design value of 188℃. If the simulation results are not significantly different from the design values, the operating strategy under this condition is acceptable. Other operating conditions can be achieved by adjusting the inlet and outlet flow rates and temperatures of the heat exchange loops and repeating this simulation process.
[0044] like Figure 6 As shown, when the reactor load decreases to the first preset percentage (75%), the inlet temperature and flow rate of the secondary loop change. At 75% load, the secondary loop inlet temperature is 249℃, the heat exchange flow rate is 506 kg / s, the expected heat exchanger outlet temperature is 183.13℃, and the return water temperature is 204.1℃. Simulations are performed according to the above simulation process. Under this condition, the secondary loop bypass needs to be activated, allowing a portion of the secondary loop flow to bypass the heat exchanger and ultimately merge with the heat-exchanged medium back to the reactor. The secondary loop bypass flow rate is 227.33 kg / s. Simultaneously, the heating extraction rate also needs to be adjusted, decreasing from 1.8 kg / s at 100% load to 0.5 kg / s. Superheated steam at 54.26 kg / s, 242.29℃, and 1532.7 kPa is provided.
[0045] like Figure 7As shown, when the reactor load decreases to the second preset percentage (50%), only two sets of heat exchangers are put into operation, with the flow rate evenly distributed. Simultaneously, the inlet and outlet temperatures and heat exchange flow rates of the secondary loop change. At 50% load, the secondary loop inlet temperature is 250.2℃, the heat exchange flow rate is 333.33 kg / s, the expected heat exchanger outlet temperature is 220.2℃, and the return water temperature is 182.618℃. Following the simulation process described above, under this condition, the secondary loop bypass flow rate needs to be further increased to 400 kg / s, the heating extraction rate adjusted to 0.1 kg / s, the tertiary loop flow rate reduced by 36.7 kg / s, and the superheated steam parameters are 243.29 degrees Celsius and 1532.6 kPa.
[0046] Example 2: This embodiment provides a steady-state simulation system for different operating conditions of a nuclear energy heat exchange loop model, including: The data acquisition module is configured to acquire design operating parameters and heat exchanger-related data. The simulation startup module is configured to simulate the nuclear energy heat exchange loop model corresponding to the operating parameters and heat exchanger-related data. The first adjustment module is configured to: determine whether the heat exchange area of the heat exchanger can meet the required heat exchange area, and whether the heat load of the heat exchanger reaches the design heat load; if it meets the requirements, determine whether the outlet temperature of the fluid after heat exchange can meet the design requirements; otherwise, adjust the heat exchanger structure, loop flow rate and / or heating extraction rate, and perform simulation again. The second adjustment module is configured to: complete the simulation if the outlet temperature of the fluid after heat exchange meets the design requirements; otherwise, continue to adjust the loop flow rate or the heating pumping rate until the outlet temperature of the fluid after heat exchange meets the design requirements.
[0047] The working method of the system is the same as the steady-state simulation method under different operating conditions of the nuclear energy heat exchange loop model in Example 1, and will not be repeated here.
[0048] Example 3: This embodiment provides a computer-readable storage medium storing a computer program that, when executed by a processor, implements the steps of the steady-state simulation method for different operating conditions of the nuclear energy heat exchange loop model described in Embodiment 1.
[0049] Example 4: This embodiment provides an electronic device, including a memory, a processor, and a computer program stored in the memory and capable of running on the processor. When the processor executes the program, it implements the steps of the steady-state simulation method for different operating conditions of the nuclear energy heat exchange loop model described in Embodiment 1.
[0050] Example 5: This embodiment provides a computer program product, which includes a computer program. When the computer program is executed by a processor, it implements the steps of the steady-state simulation method for different operating conditions of the nuclear energy heat exchange loop model described in Embodiment 1.
[0051] The above description is merely a preferred embodiment of this practice and is not intended to limit the scope of this practice. Various modifications and variations can be made to this practice by those skilled in the art. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of this practice should be included within the protection scope of this practice.
Claims
1. A steady-state simulation method for a nuclear energy heat exchange loop model under different operating conditions, characterized in that, include: Obtain design operating parameters and relevant data for the heat exchanger; Simulate the nuclear energy heat exchange loop model corresponding to the operating parameters and heat exchanger-related data; Determine whether the heat exchanger's heat exchange area is sufficient to meet the required heat exchange area, and whether the heat exchanger's heat load meets the design heat load; if so, determine whether the fluid outlet temperature after heat exchange meets the design requirements; otherwise, adjust the heat exchanger structure, loop flow rate, and / or heating extraction rate, and perform the simulation again. If the outlet temperature of the fluid after heat exchange meets the design requirements, the simulation is complete; otherwise, continue to adjust the loop flow rate or the heating and pumping rate until the outlet temperature of the fluid after heat exchange meets the design requirements.
2. The steady-state simulation method for a nuclear energy heat exchange loop model under different operating conditions as described in claim 1, characterized in that, Design operating parameters include one or more of the following: inlet and outlet temperature, flow rate, and pressure.
3. The steady-state simulation method for a nuclear energy heat exchange loop model under different operating conditions as described in claim 1, characterized in that, The relevant data for heat exchangers include the number of heat exchangers in operation and / or the heat transfer coefficient of the heat exchangers.
4. The steady-state simulation method for a nuclear energy heat exchange loop model under different operating conditions as described in claim 1, characterized in that, When the reactor load percentage is greater than the first preset percentage, three sets of heat exchangers are put into operation in parallel. When the load decreases to the second preset percentage, two sets of heat exchangers are put into operation in parallel. When the load decreases to the third preset percentage, only one set of heat exchangers is put into operation. At the same time, the secondary loop bypass is activated to adjust the flow rate through the heat exchanger set and adjust the heating steam quantity according to the operating conditions. The first preset percentage is greater than the second preset percentage, and the second preset percentage is greater than the third preset percentage.
5. The steady-state simulation method for a nuclear energy heat exchange loop model under different operating conditions as described in claim 4, characterized in that, When the reactor load is reduced to the first preset percentage, the inlet temperature and flow rate of the secondary loop change, the secondary loop bypass is activated, so that part of the secondary loop flow does not pass through the heat exchanger and eventually merges with the heat exchanged medium and returns to the reactor; at the same time, the heating pumping rate is reduced.
6. The steady-state simulation method for a nuclear energy heat exchange loop model under different operating conditions as described in claim 5, characterized in that, When the reactor load is reduced to the second preset percentage, only two sets of heat exchangers are put into operation. The inlet and outlet temperatures and heat exchange flow rates of the secondary loop change. The bypass flow rate of the secondary loop is increased, the heating and extraction flow rate is further reduced, and the flow rate of the tertiary loop is reduced.
7. A steady-state simulation system for a nuclear energy heat exchange loop model under different operating conditions, characterized in that, include: The data acquisition module is configured to acquire design operating parameters and heat exchanger-related data. The simulation startup module is configured to simulate the nuclear energy heat exchange loop model corresponding to the operating parameters and heat exchanger-related data. The first adjustment module is configured to: determine whether the heat exchange area of the heat exchanger can meet the required heat exchange area, and whether the heat load of the heat exchanger reaches the design heat load; if it meets the requirements, determine whether the outlet temperature of the fluid after heat exchange can meet the design requirements; otherwise, adjust the heat exchanger structure, loop flow rate and / or heating extraction rate, and perform simulation again. The second adjustment module is configured to: complete the simulation if the outlet temperature of the fluid after heat exchange meets the design requirements; otherwise, continue to adjust the loop flow rate or the heating pumping rate until the outlet temperature of the fluid after heat exchange meets the design requirements.
8. A computer-readable storage medium having a computer program stored thereon, characterized in that, When executed by the processor, the program implements the steps of the steady-state simulation method for different operating conditions of the nuclear energy heat exchange loop model as described in any one of claims 1-6.
9. An electronic device comprising a memory, a processor, and a computer program stored in the memory and capable of running on the processor, characterized in that, When the processor executes the program, it implements the steps of the steady-state simulation method for different operating conditions of the nuclear energy heat exchange loop model as described in any one of claims 1-6.
10. A computer program product, characterized in that, The computer program product includes a computer program that, when executed by a processor, implements the steps of the steady-state simulation method for different operating conditions of the nuclear energy heat exchange loop model as described in any one of claims 1-6.