A seawater dosing control method for nuclear power plant

Abstract

This invention belongs to the field of nuclear power plant three-loop operation control technology, specifically relating to a method for controlling seawater dosing in nuclear power plants. Step 1: Install temperature sensors on the main cooling water pipeline of the three-loop system to collect cooling water temperature data in real time and transmit it to the control station. Step 2: Establish a model corresponding to cooling water temperature and aquatic organism growth rate. Based on the collected cooling water temperature, derive and preset a correlation curve between cooling water temperature and target sodium hypochlorite concentration. Dynamically correct the target concentration based on the real-time collected cooling water temperature and the current measured concentration. Step 3: After receiving the real-time cooling water temperature data, the control station automatically calculates the required target sodium hypochlorite concentration based on the preset curve. Simultaneously, it obtains the real-time concentration of sodium hypochlorite in the cooling water through a concentration sensor, compares the results, and then performs control measures. This invention achieves intelligent management of seawater dosing in the three-loop system, improving the safety, stability, and economy of system operation.

Description

Technical Field

[0001] This invention belongs to the field of nuclear power plant three-loop operation control technology, specifically relating to a method for controlling seawater dosing in nuclear power plants. Background Technology

[0002] A nuclear power plant system mainly consists of three loops. In the primary loop, the nuclear reactor generates heat through nuclear fission, which is transferred to the steam generator. In the secondary loop, steam is generated through interlayer ventilation, driving a turbine generator to produce electricity. Waste heat is removed via seawater and steam in the tertiary loop. The tertiary loop uses seawater as its water source, which contains marine life such as fish, shrimp, and shellfish. If these marine organisms proliferate excessively in the seawater channels, it can cause problems such as clogged filters, reduced heat exchanger efficiency, and equipment corrosion in the tertiary loop system. To prevent these problems, sodium hypochlorite is added to the seawater in the tertiary loop to kill marine organisms and inhibit their growth in the seawater pipelines, ensuring the proper performance of the pipelines and equipment.

[0003] Currently, most nuclear power plants use seawater electrolysis to produce and store sodium hypochlorite. The sodium hypochlorite solution in the storage tanks is then pumped into the tertiary coolant loop via dosing pumps. The dosage is controlled by starting and stopping the pumps, typically using a timed and metered dosing method. However, this method does not consider the dynamic changes in the tertiary coolant temperature. Marine organism reproduction rates are closely related to water temperature. Considering that timed and metered dosing may be insufficient to inhibit marine growth when water temperature rises, and could lead to equipment corrosion due to excessive dosage when water temperature falls, most current sodium hypochlorite dosing schemes for operating nuclear power units have shortcomings in utilization rate and level of automation.

[0004] Chinese patent application CN113521991A discloses an automatic dosing device that can add chemical solution to a water tank without human intervention based on harmful gas concentration information collected by an information acquisition system. However, when issuing the dosing command, it only makes a judgment based on the current harmful gas concentration and does not consider the feedforward parameters that affect changes in the demand for the chemical solution, resulting in problems such as response lag and low control accuracy.

[0005] Given the shortcomings of the current three-loop sodium hypochlorite dosing operation mode in nuclear power plants, it is necessary to design an automatic control method for three-loop sodium hypochlorite dosing to improve the adaptability of the cooling water system to environmental changes and reduce operating costs. Summary of the Invention

[0006] The purpose of this invention is to provide a nuclear power plant seawater dosing control method based on two parameters: three-loop cooling water temperature and sodium hypochlorite concentration. Through real-time monitoring, dynamic calculation, and precise control, intelligent management of three-loop seawater dosing is achieved, thereby improving the safety, stability, and economy of system operation.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A method for controlling the chemical dosing in seawater at a nuclear power plant includes the following steps: Step 1: Install temperature sensors in the three-loop cooling water main pipeline to collect cooling water temperature data in real time and transmit it to the control station; Step 2: Establish a model corresponding to cooling water temperature and aquatic organism growth rate. Based on the collected cooling water temperature, derive and preset the correlation curve between cooling water temperature and target sodium hypochlorite concentration. Dynamically correct the target concentration based on the real-time collected cooling water temperature and the current measured concentration. Step 3: After receiving real-time cooling water temperature data, the control station automatically calculates the current target concentration of sodium hypochlorite based on the preset curve; at the same time, it obtains the real-time concentration of sodium hypochlorite in the cooling water through the concentration sensor, compares the results, and then performs regulation.

[0008] Step 1: Set up a visual interface on the control station's host computer to synchronously display real-time temperature, sodium hypochlorite concentration, dosing pump operating status, and tank liquid level parameters.

[0009] Step 2: Ensure that each cooling water temperature value corresponds to a unique sodium hypochlorite concentration that can effectively inhibit the growth of marine organisms.

[0010] Step 3: If the real-time concentration is less than the target concentration, the dosing pump will automatically start to increase the dosage; if the real-time concentration is greater than or equal to the target concentration, the dosing pump will automatically stop.

[0011] It also includes step four: installing a liquid level sensor in the sodium hypochlorite storage tank to issue an alarm when the liquid level is lower than the preset lower limit; and installing a concentration sensor in the sodium hypochlorite storage tank to issue an abnormal concentration alarm when the concentration of the solution exceeds the preset effective range.

[0012] Before initial commissioning, the operators confirmed that neither the abnormal concentration alarm nor the abnormal liquid level alarm of the storage tank was triggered. By comparing the values ​​of the liquid level sensor and the concentration sensor with the preset values, it was confirmed that there was sufficient sodium hypochlorite solution with the required concentration available for use.

[0013] The operator confirms that the dosing pump is in manual mode; on the control station, click the dosing mode selection button, and in the pop-up dosing pump mode selection screen, click automatic mode and confirm to put the dosing pump in automatic mode; when the current measured concentration is confirmed to be less than the current target concentration, the dosing pump automatically starts, and after a period of time, the current measured concentration gradually increases; when the control station calculates that the current measured concentration is greater than or equal to the current target concentration plus the concentration hysteresis value, the dosing pump automatically stops; when it is necessary to manually adjust the target concentration according to the unit's operating conditions, click the manual target concentration setting button, enter the required target concentration in the pop-up manual target concentration setting screen, and click confirm to complete the manual setting of the target concentration; when the automatic control function malfunctions and automatic dosing cannot be achieved, click the dosing mode selection button, and in the pop-up dosing pump mode selection screen, click manual mode and confirm to put the dosing pump in manual mode; when the current measured concentration is less than the current target concentration, click the manual start button to manually start the dosing pump; when the current measured concentration is greater than or equal to the current target concentration plus the concentration hysteresis value, click the manual stop button to manually stop the dosing pump.

[0014] The beneficial effects achieved by this invention are as follows: This invention resolves the contradiction between marine organism growth and excessive chemical dosage by dynamically adjusting the dosage of sodium hypochlorite through monitoring the cooling water temperature, thus ensuring the safe and efficient operation of the three-loop system.

[0015] Dynamic adaptation and efficient pollution control: By monitoring the temperature and sodium hypochlorite concentration of the three-loop cooling water in real time, the system can quickly respond to changes in water temperature and automatically adjust the amount of sodium hypochlorite added, ensuring the efficient operation of the three-loop cooling water system. Automatic operation reduces human error: The system operates stably and reliably, and can maintain an automated operation state for a long time, reducing the number of manual adjustments when the water temperature changes frequently, thus reducing human error and improving the work efficiency of operators. Adaptable to various working conditions and highly reliable: It supports automatic and manual mode switching. In case of automatic mode failure, the target concentration can be manually set or the dosing pump can be started or stopped without affecting the normal operation of the three circuits. It meets the automated dosing needs under different working conditions and has strong applicability. Low-cost retrofitting and easy to promote: It can be implemented by retrofitting the existing chemical dosing system of the power plant without large-scale equipment replacement, resulting in low retrofitting costs and compatibility with various seawater-cooled power plant systems. Attached Figure Description

[0016] Figure 1 A logic diagram for the seawater chemical dosing control method in nuclear power plants; Figure 2 This is a schematic diagram of the main interface of the control station; Figure 3 This is the screen for manually setting the target concentration; Figure 4Select the operation screen for the dosing pump mode. Detailed Implementation

[0017] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0018] like Figure 1 As shown, a method for controlling seawater chemical dosing in nuclear power plants is based on real-time monitoring, intelligent calculation, dynamic regulation, and safety assurance as its core logic. The specific technical solution is as follows: Real-time monitoring system deployment: High-precision temperature sensors are installed on the three-loop cooling water main pipeline to collect cooling water temperature data in real time and transmit it to the control station; the host computer of the control station is equipped with a visual interface to synchronously display key parameters such as real-time temperature, sodium hypochlorite concentration, dosing pump operating status, and storage tank level, ensuring that operators can keep track of the system's operating status in real time.

[0019] Intelligent Target Concentration Calculation Model: Based on engineering practice, a model corresponding to cooling water temperature and aquatic organism growth rate is first established. By collecting cooling water temperature data, a correlation curve between cooling water temperature and target sodium hypochlorite concentration is further derived and preset to ensure that each temperature value corresponds to a unique sodium hypochlorite concentration that can effectively inhibit marine organism growth. On this basis, the intelligent calculation module dynamically corrects the target concentration based on the real-time collected temperature and the current measured concentration, enabling the dosing decision to have adaptive capabilities.

[0020] Dynamic control logic: After receiving real-time temperature data, the control station automatically calculates the current target concentration of sodium hypochlorite based on the preset curve; at the same time, it obtains the real-time concentration of sodium hypochlorite in the cooling water through the concentration sensor, and performs control after comparison: if the real-time concentration is less than the target concentration, the dosing pump is automatically started to increase the dosage; if the real-time concentration is greater than or equal to the target concentration, the dosing pump is automatically stopped to avoid overdose.

[0021] Safety Assurance Module: Two additional feedback and alarm modules are added to ensure stable system operation: Liquid Level Monitoring Alarm: A liquid level sensor is installed in the sodium hypochlorite storage tank. When the liquid level is lower than the preset lower limit (insufficient solution), an alarm is issued to prevent interruption of dosing; Concentration Monitoring Alarm: A concentration sensor is installed in the sodium hypochlorite storage tank. When the solution concentration exceeds the preset effective range (too high / too low), an abnormal concentration alarm is issued to avoid affecting the pollution control effect or aggravating corrosion.

[0022] Before initial commissioning, operators confirmed that neither the "tank concentration abnormality alarm" nor the "tank level abnormality alarm" had been triggered. By comparing the values ​​from the level and concentration sensors with preset values, it was confirmed that sufficient sodium hypochlorite solution with the required concentration was available. Operators confirmed that the dosing pump was in "manual" mode. Instrumentation personnel confirmed that the thermometer used to measure the temperature of the three-loop circuit and the instrument used to measure the sodium hypochlorite concentration of the three-loop circuit had been calibrated and met the requirements, displaying normal readings. Figure 2 The dosing mode selection button is "Manual / Automatic". In the pop-up dosing pump mode selection screen... Figure 4 In the system settings, click "Automatic Mode" and then click "OK" to put the dosing pump into automatic mode. Check the system operation and confirm that the dosing pump automatically starts when the "Current Measured Concentration" is less than the "Current Target Concentration," and the "Current Measured Concentration" gradually increases after a period of time. The control station calculates that the "Current Measured Concentration" is greater than or equal to the "Current Target Concentration" plus the concentration hysteresis value (Q). 差 When the dosing pump automatically stops, click [the appropriate button]. When it is necessary to manually adjust the target concentration according to the unit's operating conditions, click [the appropriate button]. Figure 2 The "Manually set target concentration" button appears in the pop-up "Manually set target concentration" screen. Figure 3 Enter the desired target concentration in the field and click OK to complete the manual setting of the target concentration; if the system's automatic control function malfunctions and cannot achieve automatic dosing, click... Figure 2 The dosing mode selection button is "Manual / Automatic". In the pop-up dosing pump mode selection screen... Figure 4 In the manual mode, click "Manual Mode" and then click "OK" to put the dosing pump into manual mode; when the "Current Measured Concentration" is lower than the "Current Target Concentration", click... Figure 2 The "Manual Pump Start" button will manually start the dosing pump; when the "Current Measured Concentration" is greater than or equal to the "Current Target Concentration" + concentration hysteresis value (Q)... 差 When clicking, Figure 2 The "Manual Stop Pump" button will manually stop the dosing pump.

Claims

1. A method for seawater chemical addition control of a nuclear power plant, characterized by: Includes the following steps: Step 1: Install temperature sensors in the three-loop cooling water main pipeline to collect cooling water temperature data in real time and transmit it to the control station; Step 2: Establish a model corresponding to cooling water temperature and aquatic organism growth rate. Based on the collected cooling water temperature, derive and preset the correlation curve between cooling water temperature and target sodium hypochlorite concentration. Dynamically correct the target concentration based on the real-time collected cooling water temperature and the current measured concentration. Step 3: After receiving real-time cooling water temperature data, the control station automatically calculates the current target concentration of sodium hypochlorite based on the preset curve; at the same time, it obtains the real-time concentration of sodium hypochlorite in the cooling water through the concentration sensor, compares the results, and then performs regulation.

2. The method for controlling seawater chemical dosing in a nuclear power plant according to claim 1, characterized in that: Step 1: Set up a visual interface on the control station's host computer to synchronously display real-time temperature, sodium hypochlorite concentration, dosing pump operating status, and tank liquid level parameters.

3. The method for controlling seawater chemical dosing in a nuclear power plant according to claim 1, characterized in that: Step 2: Ensure that each cooling water temperature value corresponds to a unique sodium hypochlorite concentration that can effectively inhibit the growth of marine organisms.

4. The method for controlling seawater chemical dosing in a nuclear power plant according to claim 1, characterized in that: Step 3: If the real-time concentration is less than the target concentration, the dosing pump will automatically start to increase the dosage; if the real-time concentration is greater than or equal to the target concentration, the dosing pump will automatically stop.

5. The method for controlling seawater chemical dosing in a nuclear power plant according to claim 1, characterized in that: It also includes step four: installing a liquid level sensor in the sodium hypochlorite storage tank to issue an alarm when the liquid level is lower than the preset lower limit; and installing a concentration sensor in the sodium hypochlorite storage tank to issue an abnormal concentration alarm when the concentration of the solution exceeds the preset effective range.

6. The method for controlling seawater chemical dosing in a nuclear power plant according to claim 5, characterized in that: Before initial commissioning, the operators confirmed that neither the abnormal concentration alarm nor the abnormal liquid level alarm of the storage tank was triggered. By comparing the values ​​of the liquid level sensor and the concentration sensor with the preset values, it was confirmed that there was sufficient sodium hypochlorite solution with the required concentration available for use.

7. The method for controlling seawater chemical dosing in a nuclear power plant according to claim 4, characterized in that: The operator confirms that the dosing pump is in manual mode; on the control station, click the dosing mode selection button, and in the pop-up dosing pump mode selection screen, click automatic mode and confirm to put the dosing pump in automatic mode; when the current measured concentration is confirmed to be less than the current target concentration, the dosing pump automatically starts, and after a period of time, the current measured concentration gradually increases; when the control station calculates that the current measured concentration is greater than or equal to the current target concentration plus the concentration hysteresis value, the dosing pump automatically stops; when it is necessary to manually adjust the target concentration according to the unit's operating conditions, click the manual target concentration setting button, enter the required target concentration in the pop-up manual target concentration setting screen, and click confirm to complete the manual setting of the target concentration; when the automatic control function malfunctions and automatic dosing cannot be achieved, click the dosing mode selection button, and in the pop-up dosing pump mode selection screen, click manual mode and confirm to put the dosing pump in manual mode; when the current measured concentration is less than the current target concentration, click the manual start button to manually start the dosing pump; when the current measured concentration is greater than or equal to the current target concentration plus the concentration hysteresis value, click the manual stop button to manually stop the dosing pump.

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