Nuclear power plant conventional island high-pressure heater liquid level control method

Abstract

The application discloses a high-pressure heater liquid level control method for a conventional island of a nuclear power plant. The nuclear power plant conventional island comprises a controller and at least one high-pressure heater group. Each high-pressure heater group comprises at least one high-pressure heater. Each high-pressure heater is provided with at least three liquid level transmitters. The at least three liquid level transmitters are respectively used for continuously measuring liquid levels in real time and outputting liquid level measurement signals to the controller. The method is applied to the controller and comprises the following steps: receiving the liquid level measurement signals of the at least three liquid level transmitters of each high-pressure heater; comprehensively analyzing the liquid level measurement signals of the at least three liquid level transmitters of each high-pressure heater; and adjusting normal drainage and emergency drainage of the corresponding high-pressure heater according to the comprehensive analysis result. According to the application, each high-pressure heater is provided with at least three liquid level transmitters to participate in the adjustment of the normal drainage and emergency drainage of the corresponding high-pressure heater. The failure of a single liquid level transmitter will not directly affect the liquid level control of the high-pressure heater.

Description

Technical Field

[0001] This invention relates to the field of nuclear power plant technology, and in particular to a method for controlling the liquid level of a high-pressure heater in the conventional island of a nuclear power plant. Background Technology

[0002] In nuclear power plants, the high-pressure heaters in the conventional island are controlled by level transmitters or level switches to maintain the high-pressure heaters at the normal level. However, each level transmitter controls one drain valve, and the relevant control logic of the level switch is also a single trigger. Therefore, the existing high-pressure heater level control has a single logic, which can lead to equipment malfunctions causing abnormal drain level control. Summary of the Invention

[0003] The technical problem this invention aims to solve is to address at least one deficiency in the related technologies mentioned in the background section: existing high-pressure heater level control relies on a single logic, leading to potential equipment malfunctions that cause abnormal condensate level control. This invention provides a high-pressure heater level control method for the conventional island of a nuclear power plant.

[0004] The technical solution adopted by the present invention to solve its technical problem is: to construct a high-pressure heater liquid level control method for the conventional island of a nuclear power plant, wherein the conventional island of the nuclear power plant includes a controller and at least one row of high-pressure heater groups, each row of high-pressure heater groups includes at least one high-pressure heater, each high-pressure heater is equipped with at least three liquid level transmitters, and the at least three liquid level transmitters are used to continuously measure the liquid level in real time and output the liquid level measurement signal to the controller. The high-pressure heater liquid level control method is applied to the controller and includes the following steps: S1: Receive level measurement signals from at least three level transmitters for each of the high-pressure heaters; S2: Perform comprehensive analysis on the liquid level measurement signals of at least three liquid level transmitters for each high-pressure heater, and adjust the normal drainage and emergency drainage of the corresponding high-pressure heater according to the comprehensive analysis results.

[0005] In the aforementioned method for controlling the liquid level of the high-pressure heater in the conventional island of a nuclear power plant, preferably, at least three of the liquid level transmitters are respectively arranged on at least three different DCS cards.

[0006] In the aforementioned method for controlling the liquid level of high-pressure heaters in the conventional island of a nuclear power plant, preferably, the conventional island of the nuclear power plant further includes a feedwater pump, a feedwater header, a secondary side pipeline of a steam generator, a high-pressure cylinder of a steam turbine, a steam-water separator reheater, a deaerator, a condenser, and a third isolation valve, as well as a first isolation valve and a second isolation valve corresponding to each column of the high-pressure heater group, and a fourth isolation valve, a first drain valve, a second drain valve, and a third drain valve corresponding to each of the high-pressure heaters; The feedwater inlet of each high-pressure heater group is connected to the outlet of the feedwater pump via a corresponding first isolation valve, and the feedwater outlet of each high-pressure heater group is connected to the feedwater main pipe via a corresponding second isolation valve. The outlet of the feedwater pump is also connected to the feedwater main pipe via a third isolation valve. The feedwater main pipe is connected to the secondary side pipeline of the steam generator. Each high-pressure heater is connected to the high-pressure cylinder of the steam turbine via a corresponding fourth isolation valve, and the high-pressure cylinder of the steam turbine outputs heating steam to the high-pressure heater through steam extraction. The condensate inlet of each high-pressure heater is connected to the condensate outlet of the steam-water separator reheater via a corresponding first condensate valve. One condensate outlet of each high-pressure heater is connected to the deaerator via a corresponding second condensate valve (the second condensate valve is a normal condensate valve). The other condensate outlet of each high-pressure heater is connected to the condenser via a corresponding third condensate valve (the third condensate valve is an emergency condensate valve). Step S2 includes: S21a: If the liquid level measurement signal value of at least three liquid level transmitters of the high-pressure heater is less than the first liquid level threshold, then control the second drain valve corresponding to the high-pressure heater to drain water to the deaerator, and all the drain water is delivered to the deaerator; at the same time, control the opening of the first isolation valve and the second isolation valve corresponding to the high-pressure heater group, control the closing of the third isolation valve, and control the opening of the fourth isolation valve and the first drain valve corresponding to the high-pressure heater. S22a: If the liquid level measurement signal values ​​of at least three liquid level transmitters of the high-pressure heater are greater than or equal to the first liquid level threshold and less than the second liquid level threshold, then the second drain valve corresponding to the high-pressure heater is controlled to drain water to the deaerator; and the liquid level measurement signal values ​​of the at least three liquid level transmitters are sorted according to their numerical values ​​and the median value is taken. The opening of the third drain valve corresponding to the high-pressure heater is controlled according to the median value to perform emergency drain adjustment, and part of the drain water is delivered to the condenser; at the same time, the first isolation valve and the second isolation valve corresponding to the high-pressure heater group are controlled to open, the third isolation valve is controlled to close, and the fourth isolation valve and the first drain valve corresponding to the high-pressure heater are controlled to open. S23a: If the level measurement signal value of more than half of the three level transmitters of the high-pressure heater is greater than or equal to the second level threshold and less than the third level threshold, then the second drain valve corresponding to the high-pressure heater is controlled to drain water to the deaerator; and the third drain valve corresponding to the high-pressure heater is controlled to be fully opened for emergency drain adjustment, and part of the drain water is delivered to the condenser; at the same time, the first isolation valve and the second isolation valve corresponding to the high-pressure heater group are controlled to be opened, the third isolation valve is controlled to be closed, and the fourth isolation valve and the first drain valve corresponding to the high-pressure heater are controlled to be opened. S24a: If the liquid level measurement signal value of more than half of the liquid level transmitters of at least three liquid level transmitters of the high-pressure heater is greater than or equal to the third liquid level threshold, then the first isolation valve and the second isolation valve corresponding to the high-pressure heater group in the row are controlled to close, the third isolation valve is controlled to open, and the fourth isolation valve and the first drain valve corresponding to the high-pressure heater are controlled to close, so as to isolate the entire row of high-pressure heater groups.

[0007] In the aforementioned method for controlling the liquid level of high-pressure heaters in the conventional island of a nuclear power plant, preferably, each column of the high-pressure heater group includes at least two high-pressure heaters connected in series, and the feedwater between the at least two high-pressure heaters connected in series is connected; the condensate drain between each pair of high-pressure heaters connected in series is connected. Step S21a includes: if the liquid level measurement signal value of at least three liquid level transmitters of the high-pressure heater is less than the first liquid level threshold, then control the second drain valve corresponding to the high-pressure heater to drain water to the next-stage high-pressure heater in series, or directly drain water to the deaerator; at the same time, control the opening of the first isolation valve and the second isolation valve corresponding to the high-pressure heater group, control the closing of the third isolation valve, and control the opening of the fourth isolation valve and the first drain valve corresponding to the high-pressure heater. Step S22a includes: if the liquid level measurement signal values ​​of at least three liquid level transmitters of the high-pressure heater are greater than or equal to the first liquid level threshold and less than the second liquid level threshold, then the second drain valve corresponding to the high-pressure heater is controlled to drain water to the next-stage high-pressure heater in series, or directly to the deaerator; and, the liquid level measurement signal values ​​of the at least three liquid level transmitters are sorted according to their numerical values ​​and the median value is taken, and the third drain valve corresponding to the high-pressure heater is controlled according to the median value to perform emergency drain adjustment, and part of the drain water is delivered to the condenser; at the same time, the first isolation valve and the second isolation valve corresponding to the high-pressure heater group are controlled to open, the third isolation valve is controlled to close, and the fourth isolation valve and the first drain valve corresponding to the high-pressure heater are controlled to open. Step S23a includes: if the level measurement signal value of more than half of the level transmitters of at least three level transmitters of the high-pressure heater is greater than or equal to the second level threshold and less than the third level threshold, then the second drain valve corresponding to the high-pressure heater is controlled to drain water to the next-stage high-pressure heater in series, or directly to the deaerator; and the third drain valve corresponding to the high-pressure heater is controlled to be fully opened for emergency drain adjustment, with some drain water being transported to the condenser; simultaneously, the first isolation valve and the second isolation valve corresponding to the high-pressure heater group are controlled to be opened, the third isolation valve is controlled to be closed, and the fourth isolation valve and the first drain valve corresponding to the high-pressure heater are controlled to be opened.

[0008] In the aforementioned method for controlling the liquid level of the high-pressure heater in the conventional island of a nuclear power plant, preferably, each high-pressure heater is further provided with at least four liquid level switches, which are respectively used to trigger at different liquid level thresholds and output switch signals to the controller. Step S1 includes: receiving level measurement signals from at least three level transmitters of each of the high-pressure heaters and switching signals from at least four level switches; Step S2 includes: performing a comprehensive analysis on the level measurement signals of at least three level transmitters and the switching signals of at least four level switches for each high-pressure heater, and adjusting the normal drainage and emergency drainage of the corresponding high-pressure heater based on the comprehensive analysis results.

[0009] In the aforementioned method for controlling the liquid level of the high-pressure heater in the conventional island of a nuclear power plant, preferably, at least four liquid level switches include a first liquid level switch for triggering when the liquid level is below a first liquid level threshold, a second liquid level switch for triggering when the liquid level reaches the first liquid level threshold, a third liquid level switch for triggering when the liquid level reaches the second liquid level threshold, and a fourth liquid level switch for triggering when the liquid level reaches the third liquid level threshold. The conventional island of the nuclear power plant also includes feedwater pumps, feedwater headers, secondary side piping of the steam generator, high-pressure cylinder of the steam turbine, steam-water separator reheater, deaerator, condenser and third isolation valve, as well as first isolation valve and second isolation valve corresponding to each column of the high-pressure heater group, and fourth isolation valve, first drain valve, second drain valve and third drain valve corresponding to each of the high-pressure heaters; The feedwater inlet of each high-pressure heater group is connected to the outlet of the feedwater pump via a corresponding first isolation valve, and the feedwater outlet of each high-pressure heater group is connected to the feedwater main pipe via a corresponding second isolation valve. The outlet of the feedwater pump is also connected to the feedwater main pipe via a third isolation valve. The feedwater main pipe is connected to the secondary side pipeline of the steam generator. Each high-pressure heater is connected to the high-pressure cylinder of the steam turbine via a corresponding fourth isolation valve, and the high-pressure cylinder of the steam turbine outputs heating steam to the high-pressure heater through steam extraction. The condensate inlet of each high-pressure heater is connected to the condensate outlet of the steam-water separator reheater via a corresponding first condensate valve. One condensate outlet of each high-pressure heater is connected to the deaerator via a corresponding second condensate valve (the second condensate valve is a normal condensate valve). The other condensate outlet of each high-pressure heater is connected to the condenser via a corresponding third condensate valve (the third condensate valve is an emergency condensate valve). Step S2 includes: S21b: If the actual liquid level of the high-pressure heater is less than the first liquid level threshold and a switching signal from the first liquid level switch of the high-pressure heater is received, then the second drain valve corresponding to the high-pressure heater is controlled to drain water to the deaerator, and all the drain water is delivered to the deaerator; at the same time, the first isolation valve and the second isolation valve corresponding to the high-pressure heater group are controlled to open, the third isolation valve is controlled to close, and the fourth isolation valve and the first drain valve corresponding to the high-pressure heater are controlled to open; S22b: If the actual liquid level of the high-pressure heater is greater than or equal to the first liquid level threshold and less than the second liquid level threshold, and a switching signal from the second liquid level switch of the high-pressure heater is received, then the second drain valve corresponding to the high-pressure heater is controlled to drain water to the deaerator; and, based on the actual liquid level, the opening of the third drain valve corresponding to the high-pressure heater is controlled for emergency drain adjustment, with some drain water being transported to the condenser; simultaneously, the first isolation valve and the second isolation valve corresponding to the high-pressure heater group are controlled to open, the third isolation valve is controlled to close, and the fourth isolation valve and the first drain valve corresponding to the high-pressure heater are controlled to open. S23b: If the actual liquid level of the high-pressure heater is greater than or equal to the second liquid level threshold and less than the third liquid level threshold, and a switching signal from the third liquid level switch of the high-pressure heater is received, then the second drain valve corresponding to the high-pressure heater is controlled to drain water to the deaerator; and the third drain valve corresponding to the high-pressure heater is controlled to be fully opened for emergency drain adjustment, with some drain water being transported to the condenser; simultaneously, the first isolation valve and the second isolation valve corresponding to the high-pressure heater group are controlled to be opened, the third isolation valve is controlled to be closed, and the fourth isolation valve and the first drain valve corresponding to the high-pressure heater are controlled to be opened. S24b: If the actual liquid level of the high-pressure heater is greater than or equal to the third liquid level threshold and a switching signal of the fourth liquid level switch of the high-pressure heater is received, then the first isolation valve and the second isolation valve corresponding to the high-pressure heater group in the row are controlled to close, the third isolation valve is controlled to open, and the fourth isolation valve and the first drain valve corresponding to the high-pressure heater are controlled to close, so as to isolate the entire row of high-pressure heater groups. The actual liquid level of the high-pressure heater is determined by taking the median value after sorting the liquid level measurement signal values ​​of at least three liquid level transmitters according to their numerical values.

[0010] In the aforementioned method for controlling the liquid level of high-pressure heaters in the conventional island of a nuclear power plant, preferably, each column of the high-pressure heater group includes at least two high-pressure heaters connected in series; the feedwater connection between the at least two high-pressure heaters connected in series is maintained; and the condensate connection between each pair of high-pressure heaters connected in series is maintained. Step S21b includes: if the actual liquid level of the high-pressure heater is less than the first liquid level threshold and a switching signal from the first liquid level switch of the high-pressure heater is received, then the second drain valve corresponding to the high-pressure heater is controlled to drain water to the next-stage high-pressure heater connected in series, or directly to the deaerator; simultaneously, the first isolation valve and the second isolation valve corresponding to the high-pressure heater group are controlled to open, the third isolation valve is controlled to close, and the fourth isolation valve and the first drain valve corresponding to the high-pressure heater are controlled to open. Step S22b includes: if the actual liquid level of the high-pressure heater is greater than or equal to the first liquid level threshold and less than the second liquid level threshold, and a switching signal from the second liquid level switch of the high-pressure heater is received, then the second drain valve corresponding to the high-pressure heater is controlled to drain water to the next-stage high-pressure heater in series, or directly to the deaerator; and, based on the actual liquid level, the opening of the third drain valve corresponding to the high-pressure heater is controlled for emergency drain adjustment, with some drain water being transported to the condenser; simultaneously, the first isolation valve and the second isolation valve corresponding to the high-pressure heater group are controlled to open, the third isolation valve is controlled to close, and the fourth isolation valve and the first drain valve corresponding to the high-pressure heater are controlled to open. S23b: If the actual liquid level of the high-pressure heater is greater than or equal to the second liquid level threshold and less than the third liquid level threshold, and a switching signal from the third liquid level switch of the high-pressure heater is received, then the second drain valve corresponding to the high-pressure heater is controlled to drain water to the next-stage high-pressure heater in series, or directly to the deaerator; and the third drain valve corresponding to the high-pressure heater is controlled to be fully opened for emergency drain adjustment, with some drain water being transported to the condenser; simultaneously, the first isolation valve and the second isolation valve corresponding to the high-pressure heater group are controlled to be opened, the third isolation valve is controlled to be closed, and the fourth isolation valve and the first drain valve corresponding to the high-pressure heater are controlled to be opened.

[0011] In the aforementioned method for controlling the liquid level of high-pressure heaters in the conventional island of a nuclear power plant, preferably, the conventional island of the nuclear power plant includes at least two rows of the high-pressure heater groups; the conventional island of the nuclear power plant also includes a fifth isolation valve corresponding to each of the high-pressure heaters, and in every two rows of the high-pressure heater groups, the high-pressure heaters in the two rows are connected to the fifth isolation valve corresponding to them; Step S24a or step S24b further includes: controlling the closure of the fifth isolation valve provided for the high-pressure heater of the unit.

[0012] In the aforementioned method for controlling the liquid level of the high-pressure heater in the conventional island of a nuclear power plant, preferably, step S2 further includes: S25: If the level measurement signal value of at least one level transmitter in the high-pressure heater deviates from the level measurement signal values ​​of at least two other level transmitters by more than the deviation limit, then at least one level transmitter is determined to be faulty. The average value of the level measurement signal values ​​of the other at least two level transmitters is taken, and the opening of the third drain valve corresponding to the high-pressure heater is controlled according to the average value to perform emergency drain adjustment. S26: If the liquid level measurement signal value of at least two of the liquid level transmitters in the high-pressure heater exceeds the measurement limit, then at least two of the liquid level transmitters are determined to be faulty. Based on the liquid level measurement signal value of at least one of the liquid level transmitters that is not faulty, the opening degree of the third drain valve set for the corresponding high-pressure heater is controlled to perform emergency drain adjustment. S27: If the liquid level measurement signal value of at least three of the liquid level transmitters in the high-pressure heater exceeds the measurement limit, or the deviation between the liquid level measurement signal values ​​of any two liquid level transmitters exceeds the deviation limit, then at least three of the liquid level transmitters are determined to be faulty. Based on the effective value of the previous control output, the opening degree of the third drain valve corresponding to the high-pressure heater is controlled to perform emergency drain adjustment.

[0013] In the aforementioned method for controlling the liquid level of the high-pressure heater in the conventional island of a nuclear power plant, preferably, the conventional island of the nuclear power plant further includes a sixth isolation valve; One branch of the feedwater main pipe is connected to the secondary side pipeline of the steam generator, and the other branch of the feedwater main pipe is connected to the condenser via the sixth isolation valve.

[0014] By implementing this invention, the following beneficial effects are achieved: In this invention, each high-pressure heater has at least three level transmitters involved in the regulation of normal and emergency condensation of the corresponding high-pressure heater. The failure of a single level transmitter will not directly affect the level control of the high-pressure heater, thereby avoiding the abnormal level of the high-pressure heater caused by the failure of one level transmitter, which would lead to abnormal unit operation. Attached Figure Description

[0015] The present invention will be further described below with reference to the accompanying drawings and embodiments. In the accompanying drawings: Figure 1 The logical structure diagram of a nuclear power plant is shown; Figure 2 The logical structure diagram of a high-pressure heater in the conventional island of a nuclear power plant is shown. Figure 3 The logical structure diagram of the two rows of high-pressure heaters in the conventional island of a nuclear power plant according to the present invention is shown. Figure 4 A flowchart of the high-pressure heater liquid level control method for the conventional island of a nuclear power plant according to the present invention is shown. Detailed Implementation

[0016] To provide a clearer understanding of the technical features, objectives, and effects of the present invention, specific embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0017] It should be noted that the flowcharts shown in the accompanying drawings are merely illustrative and do not necessarily include all content and operations / steps, nor do they necessarily have to be performed in the described order. For example, some operations / steps can be broken down, while others can be combined or partially combined; therefore, the actual execution order may change depending on the specific circumstances.

[0018] The block diagrams shown in the accompanying drawings are merely functional entities and do not necessarily correspond to physically independent entities. That is, these functional entities can be implemented in software, in one or more hardware modules or integrated circuits, or in different network and / or processor devices and / or microcontroller devices.

[0019] The terms “first”, “second”, etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated.

[0020] It should be noted that, apart from the flow direction relationship between the entrance and exit, the connections between components are only physical structural connections and do not uniquely limit the connectivity and flow direction relationships. The connection can be a direct pipeline connection or a pipeline connection through other components.

[0021] like Figure 1 As shown, the nuclear island of a nuclear power plant includes the main pump, reactor, pressurizer, and steam generator. The conventional island of a nuclear power plant includes the turbine, steam-water separator reheater, generator, condenser, low-pressure heater, deaerator, feedwater pump, and high-pressure heater. Specifically, steam from the steam generator first enters the high-pressure cylinder of the turbine to do work, driving the generator to generate electricity; steam discharged from the high-pressure cylinder of the turbine enters the steam-water separator reheater, and after dehumidification and reheating, it is sent to the low-pressure cylinder of the turbine to continue expanding and doing work, similarly driving the generator; the condensate produced by the steam-water separator reheater is recovered to the high-pressure heater; the exhaust steam discharged from the low-pressure cylinder of the turbine enters the condenser, is cooled by seawater and condensed into water, and this condensate flows sequentially through the low-pressure heater and deaerator for preliminary heating and deaeration, and is then pressurized by the feedwater pump and sent to the high-pressure heater. The heating steam of the high-pressure heater comes from the extraction steam of the high-pressure cylinder of the turbine, and the high-pressure heater uses the heating steam to further heat the water, finally sending it back to the steam generator, forming a complete two-stage thermodynamic cycle.

[0022] Some embodiments of the present invention disclose a method for controlling the liquid level of a high-pressure heater in the conventional island of a nuclear power plant, such as... Figure 2 As shown, the conventional island of a nuclear power plant includes a controller and at least one row of high-pressure heater groups. Each row of high-pressure heater groups includes at least one high-pressure heater, and each high-pressure heater is equipped with at least three level transmitters 1. The at least three level transmitters 1 are used to continuously measure the liquid level in real time and output liquid level measurement signals to the controller.

[0023] like Figure 4 As shown, this high-pressure heater level control method is applied to a controller and includes the following steps: S1: Receives level measurement signals from at least three level transmitters 1 for each high-pressure heater; S2: Perform comprehensive analysis on the liquid level measurement signals of at least three liquid level transmitters 1 for each high-pressure heater, and adjust the normal drainage and emergency drainage of the corresponding high-pressure heater according to the comprehensive analysis results.

[0024] In this invention, each high-pressure heater has at least three level transmitters 1 participating in the regulation of normal and emergency condensation of the corresponding high-pressure heater. The failure of a single level transmitter 1 will not directly affect the level control of the high-pressure heater, thereby avoiding the abnormal level of the high-pressure heater caused by the failure of one level transmitter 1, which would lead to abnormal unit operation.

[0025] In some embodiments, each high-pressure heater is equipped with at least three level transmitters 1, which are respectively arranged on at least three different DCS cards. This avoids the risk of all level transmitters 1 failing simultaneously due to a single card failure, thereby improving reliability. Understandably, "at least three" can be three, four, or any number.

[0026] In some embodiments, the conventional island of a nuclear power plant includes at least one row of high-pressure heater units. It is understood that this at least one row can be one, two, three, or any number, with the following preferred configurations: Figure 3 The diagram shows at least two interconnected high-pressure heater groups.

[0027] Each high-pressure heater group includes at least one high-pressure heater. Understandably, "at least one" can be one, two, three, or any number, with at least two high-pressure heaters connected in series being preferred. For example, Figure 3 The first and second high-pressure heaters connected in series shown have different hydrophobic cooling zone areas for at least two of them.

[0028] The liquid level control of the high-pressure heater is essentially the liquid level control of the high-pressure heater condensate. The purpose of controlling the condensate is twofold: firstly, to ensure the heat exchange effect, and secondly, to prevent water from entering the steam turbine through the extraction pipe connected to the high-pressure cylinder of the steam turbine.

[0029] In some embodiments, such as Figure 2 As shown, the conventional island of a nuclear power plant includes at least one row of high-pressure heater groups. When each row of high-pressure heater groups includes at least one high-pressure heater, the conventional island of the nuclear power plant also includes feedwater pumps, feedwater headers, secondary side piping of the steam generator, high-pressure cylinder of the turbine, steam-water separator reheater, deaerator, condenser, and third isolation valve 5. It also includes a first isolation valve 3 and a second isolation valve 4 corresponding to each row of high-pressure heater groups, and a fourth isolation valve 6, a first drain valve 7, a second drain valve 8, and a third drain valve 9 corresponding to each high-pressure heater. Specifically: The feedwater inlet of each high-pressure heater group is connected to the outlet of the feedwater pump via a corresponding first isolation valve 3. The feedwater outlet of each high-pressure heater group is connected to the feedwater main pipe via a corresponding second isolation valve 4. Another path of the feedwater pump outlet is connected to the feedwater main pipe via a third isolation valve 5; this path is the main bypass pipeline. The feedwater main pipe is connected to the secondary side pipeline of the steam generator. Each high-pressure heater is connected to the high-pressure cylinder of the turbine via a corresponding fourth isolation valve 6. The high-pressure cylinder of the turbine outputs heated steam to the high-pressure heater through steam extraction. The condensate inlet of each high-pressure heater is connected to the condensate outlet of the steam-water separator reheater via a corresponding first condensate valve 7. One condensate outlet of each high-pressure heater is connected to the deaerator via a corresponding second condensate valve 8; the second condensate valve 8 is a normal condensate valve. The other condensate outlet of each high-pressure heater is connected to the condenser via a corresponding third condensate valve 9; the third condensate valve 9 is an emergency condensate valve.

[0030] Accordingly, step S2 includes S21a, S22a, S23a and S24a, as follows: S21a: If the liquid level measurement signal values ​​of at least three liquid level transmitters 1 of the high-pressure heater are less than the first liquid level threshold, then the second drain valve 8 corresponding to the high-pressure heater is controlled to drain water to the deaerator, and all the drain water is delivered to the deaerator. At the same time, the first isolation valve 3 and the second isolation valve 4 corresponding to the high-pressure heater group are controlled to open, the third isolation valve 5 is controlled to close, and the fourth isolation valve 6 and the first drain valve 7 corresponding to the high-pressure heater are controlled to open.

[0031] S22a: If the level measurement signal values ​​of at least three level transmitters 1 of the high-pressure heater are greater than or equal to the first level threshold and less than the second level threshold, then the second drain valve 8 corresponding to the high-pressure heater is controlled to drain water to the deaerator. Furthermore, the median value of the level measurement signal values ​​of the at least three level transmitters 1 is taken after sorting them by magnitude, and the opening of the third drain valve 9 corresponding to the high-pressure heater is controlled based on the median value for emergency drain adjustment, with some drain water being sent to the condenser. Simultaneously, the first isolation valve 3 and the second isolation valve 4 corresponding to the high-pressure heater group are controlled to open, the third isolation valve 5 is controlled to close, and the fourth isolation valve 6 and the first drain valve 7 corresponding to the high-pressure heater are controlled to open.

[0032] S23a: If the level measurement signal value of more than half of the three level transmitters 1 of the high-pressure heater is greater than or equal to the second level threshold and less than the third level threshold, then the second drain valve 8 corresponding to the high-pressure heater is controlled to drain water to the deaerator. Simultaneously, the third drain valve 9 corresponding to the high-pressure heater is fully opened for emergency drain regulation, with some drain water being sent to the condenser. At the same time, the first isolation valve 3 and the second isolation valve 4 corresponding to the high-pressure heater group are opened, the third isolation valve 5 is closed, and the fourth isolation valve 6 and the first drain valve 7 corresponding to the high-pressure heater are opened.

[0033] S24a: If the liquid level measurement signal value of more than half of the three liquid level transmitters 1 of the high-pressure heater is greater than or equal to the third liquid level threshold, then the first isolation valve 3 and the second isolation valve 4 corresponding to the high-pressure heater group are closed, the third isolation valve 5 is opened, and the fourth isolation valve 6 and the first drain valve 7 corresponding to the high-pressure heater are closed to isolate the entire high-pressure heater group.

[0034] In some embodiments, the conventional island of the aforementioned nuclear power plant includes at least one row of high-pressure heater groups, with each row of high-pressure heater groups including at least one high-pressure heater, such as... Figure 3 As shown, each high-pressure heater group includes at least two high-pressure heaters connected in series, and the water supply between the at least two high-pressure heaters connected in series is connected. For example, each high-pressure heater group includes a first high-pressure heater and a second high-pressure heater connected in series. The water supply inlet of the first high-pressure heater is connected to the outlet of the water supply pump via a first isolation valve 3 corresponding to its column. The water supply outlet of the first high-pressure heater is connected to the water supply inlet of the second high-pressure heater. The water supply outlet of the second high-pressure heater is connected to the water supply header via a second isolation valve 4 corresponding to its column.

[0035] The drains between any two high-pressure heaters connected in series are connected via a second drain valve 8 of one of the high-pressure heaters. For example, one drain outlet of the second high-pressure heater is connected to the second drain inlet of the first high-pressure heater via the second drain valve 8 corresponding to the second high-pressure heater, and the other drain outlet of the second high-pressure heater is connected to the condenser via a third drain valve 9 corresponding to the second high-pressure heater.

[0036] Accordingly, step S21a includes: if the liquid level measurement signal values ​​of at least three liquid level transmitters 1 of the high-pressure heater are less than the first liquid level threshold, then controlling the second drain valve 8 corresponding to the high-pressure heater to drain water to the next-stage high-pressure heater in series. Simultaneously, controlling the opening of the first isolation valve 3 and the second isolation valve 4 corresponding to the high-pressure heater group, controlling the closing of the third isolation valve 5, and controlling the opening of the fourth isolation valve 6 and the first drain valve 7 corresponding to the high-pressure heater.

[0037] Alternatively, step S21a includes: if the level measurement signal values ​​of at least three level transmitters 1 of the high-pressure heater are less than the first level threshold, then controlling the second drain valve 8 corresponding to the high-pressure heater to directly drain water to the deaerator. Simultaneously, controlling the opening of the first isolation valve 3 and the second isolation valve 4 corresponding to the high-pressure heater group, controlling the closing of the third isolation valve 5, and controlling the opening of the fourth isolation valve 6 and the first drain valve 7 corresponding to the high-pressure heater.

[0038] Step S22a includes: if the liquid level measurement signal values ​​of at least three level transmitters 1 of the high-pressure heater are greater than or equal to a first liquid level threshold and less than a second liquid level threshold, then the second drain valve 8 corresponding to the high-pressure heater is controlled to drain water to the next-stage high-pressure heater in series. Furthermore, the liquid level measurement signal values ​​of the at least three level transmitters 1 are sorted according to their numerical values, and the median value is taken. Based on this median value, the third drain valve 9 corresponding to the high-pressure heater is controlled for emergency drain adjustment, with some drained water being transported to the condenser. Simultaneously, the first isolation valve 3 and the second isolation valve 4 corresponding to the high-pressure heater group are controlled to open, the third isolation valve 5 is controlled to close, and the fourth isolation valve 6 and the first drain valve 7 corresponding to the high-pressure heater are controlled to open.

[0039] Alternatively, step S22a includes: if the level measurement signal values ​​of at least three level transmitters 1 of the high-pressure heater are greater than or equal to the first level threshold and less than the second level threshold, then the second drain valve 8 corresponding to the high-pressure heater is controlled to directly drain water to the deaerator. Furthermore, the level measurement signal values ​​of the at least three level transmitters 1 are sorted by magnitude and the median value is taken. Based on this median value, the third drain valve 9 corresponding to the high-pressure heater is controlled for emergency drain adjustment, with some drained water being delivered to the condenser. Simultaneously, the first isolation valve 3 and the second isolation valve 4 corresponding to the high-pressure heater group are controlled to open, the third isolation valve 5 is controlled to close, and the fourth isolation valve 6 and the first drain valve 7 corresponding to the high-pressure heater are controlled to open.

[0040] Step S23a includes: if the level measurement signal value of more than half of the three level transmitters 1 of the high-pressure heater is greater than or equal to the second level threshold and less than the third level threshold, then the second drain valve 8 corresponding to the high-pressure heater is controlled to drain water to the next-stage high-pressure heater in series. Simultaneously, the third drain valve 9 corresponding to the high-pressure heater is controlled to fully open for emergency drain regulation, with some drain water being delivered to the condenser. At the same time, the first isolation valve 3 and the second isolation valve 4 corresponding to the high-pressure heater group are controlled to open, the third isolation valve 5 is controlled to close, and the fourth isolation valve 6 and the first drain valve 7 corresponding to the high-pressure heater are controlled to open.

[0041] Alternatively, step S23a includes: if the level measurement signal value of more than half of the at least three level transmitters 1 of the high-pressure heater is greater than or equal to the second level threshold and less than the third level threshold, then the second drain valve 8 corresponding to the high-pressure heater is controlled to directly drain water to the deaerator. Furthermore, the third drain valve 9 corresponding to the high-pressure heater is controlled to fully open for emergency drain regulation, with some drain water being delivered to the condenser. Simultaneously, the first isolation valve 3 and the second isolation valve 4 corresponding to the high-pressure heater group are controlled to open, the third isolation valve 5 is controlled to close, and the fourth isolation valve 6 and the first drain valve 7 corresponding to the high-pressure heater are controlled to open.

[0042] In some embodiments, the conventional island of the aforementioned nuclear power plant includes at least one row of high-pressure heater groups, each row comprising at least one high-pressure heater; or, the conventional island of the aforementioned nuclear power plant includes at least one row of high-pressure heater groups, each row comprising at least two high-pressure heaters connected in series. Figure 3As shown, the conventional island of a nuclear power plant includes at least two rows of high-pressure heater groups, such as row A and row B. The conventional island also includes a fifth isolation valve 10 corresponding to each high-pressure heater, and in every two rows of high-pressure heater groups, the high-pressure heaters in each row are connected to the fifth isolation valve 10 corresponding to their respective fifth isolation valves.

[0043] Accordingly, step S24a further includes: controlling the closure of the fifth isolation valve 10 set for the high-pressure heater of the unit.

[0044] In some embodiments, such as Figure 2 and Figure 3 As shown, in order to clean the high-pressure heater group before startup, a recirculation pipeline is also provided from the feedwater header back to the condenser. The pipeline is equipped with the sixth isolation valve 11. That is, the conventional island of the nuclear power plant also includes the sixth isolation valve 11. One branch of the feedwater header is connected to the secondary side pipeline of the steam generator, and the other branch of the feedwater header is connected to the condenser via the sixth isolation valve 11.

[0045] In some embodiments, such as Figure 2 and Figure 3 As shown, the conventional island of the nuclear power plant also includes a seventh isolation valve 12. Another outlet of the feedwater pump is also connected to the feedwater main pipe via the seventh isolation valve 12. This route is a backup bypass pipeline.

[0046] In some embodiments, such as Figure 2 and Figure 3 As shown, the conventional island of a nuclear power plant also includes a balancing valve 13. The balancing valve 13 is connected in parallel to the second isolation valve 4, meaning that the two ends of the balancing valve 13 are connected to the two ends of the second isolation valve 4. Accordingly, when the second isolation valve 4 is closed or opened, the balancing valve 13 is closed or opened simultaneously.

[0047] For example, the isolation valve mentioned above is a gate valve, globe valve, ball valve, butterfly valve, or plug valve, etc., and the steam trap mentioned above is a mechanical, thermostatic, or thermodynamic steam trap, etc. These are just examples and are not intended to be the only limitation of this application; others may also be included.

[0048] The condensate drainage process of a high-pressure heater assembly is as follows: Figure 3 As shown, the condensate from the steam-water separator reheater enters the second high-pressure heater, and together with the condensate from the second high-pressure heater itself, it is discharged into the first high-pressure heater through the second drain valve 8. The first high-pressure heater simultaneously receives the condensate from the steam-water separator reheater. Under normal circumstances, the condensate from the first high-pressure heater is discharged to the deaerator through the second drain valve 8.

[0049] When the condensate flow rate of the first high-pressure heater exceeds the normal condensate capacity, for example, when the internal liquid level of the first high-pressure heater rises above the normal operating liquid level by 175 mm, the condensate of the first high-pressure heater, under the action of its liquid level transmitter 1, opens the third condensate valve 9 to discharge the excess condensate to the condenser.

[0050] In addition, normal condensate from the high-pressure heaters typically flows to the deaerator via pressure differential. When the generator load is less than 30% FP, the pressure of the first high-pressure heater is insufficient to overcome the total pressure of the deaerator pressure plus the static pressure head of the deaerator liquid level. This reduces or even prevents the normal condensate flow, causing condensate to accumulate in the first high-pressure heater, raising the liquid level. The third condensate valve 9 then opens, directing the condensate to the condenser. If the liquid level continues to rise above the threshold, an alarm is triggered, and the corresponding high-pressure heater group is automatically isolated.

[0051] In some embodiments, each high-pressure heater is further provided with at least four liquid level switches 2, which are triggered at different liquid level thresholds and output switching signals to the controller. Understandably, the at least four can be four, five, or any number.

[0052] Step S1 includes: receiving liquid level measurement signals from at least three liquid level transmitters 1 and switching signals from at least four liquid level switches 2 of each high-pressure heater. Step S2 includes: comprehensively analyzing the liquid level measurement signals of at least three liquid level transmitters 1 and the switching signals of at least four liquid level switches 2 for each high-pressure heater, and adjusting the normal drainage and emergency drainage of the corresponding high-pressure heater according to the comprehensive analysis results.

[0053] This invention controls the condensate drain of the high-pressure heater by combining a level transmitter 1 and a level switch 2. This allows for mutual verification by combining the signal characteristics of different monitoring elements, solving the problem of level control relying solely on the level switch for triggering. It avoids control errors caused by single element failure or signal deviation, accurately prevents risks such as overfilling or low water level in the high-pressure heater, improves the reliability and safety of high-pressure heater level control, and ensures the stable operation of the conventional island of the nuclear power plant.

[0054] In some embodiments, at least four level switches 2 include a first level switch triggered when the level is below a first level threshold, a second level switch triggered when the level reaches the first level threshold, a third level switch triggered when the level reaches a second level threshold, and a fourth level switch triggered when the level reaches a third level threshold. The first, second, third, and fourth level thresholds here are the same as those in steps S21a, S22a, S23a, and S24a described above. For example, the first level threshold is high, the second level threshold is high-high, and the third level threshold is high-high-high.

[0055] In some embodiments, such as Figure 2 As shown, the conventional island of a nuclear power plant includes at least one row of high-pressure heater groups. When each row of high-pressure heater groups includes at least one high-pressure heater, the conventional island of the nuclear power plant also includes feedwater pumps, feedwater headers, secondary side piping of the steam generator, high-pressure cylinder of the turbine, steam-water separator reheater, deaerator, condenser, and third isolation valve 5. It also includes a first isolation valve 3 and a second isolation valve 4 corresponding to each row of high-pressure heater groups, and a fourth isolation valve 6, a first drain valve 7, a second drain valve 8, and a third drain valve 9 corresponding to each high-pressure heater. Specifically: The feedwater inlet of each high-pressure heater group is connected to the outlet of the feedwater pump via a corresponding first isolation valve 3. The feedwater outlet of each high-pressure heater group is connected to the feedwater main pipe via a corresponding second isolation valve 4. Another path of the feedwater pump outlet is connected to the feedwater main pipe via a third isolation valve 5; this path is the main bypass pipeline. The feedwater main pipe is connected to the secondary side pipeline of the steam generator. Each high-pressure heater is connected to the high-pressure cylinder of the turbine via a corresponding fourth isolation valve 6. The high-pressure cylinder of the turbine outputs heated steam to the high-pressure heater through steam extraction. The condensate inlet of each high-pressure heater is connected to the condensate outlet of the steam-water separator reheater via a corresponding first condensate valve 7. One condensate outlet of each high-pressure heater is connected to the deaerator via a corresponding second condensate valve 8; the second condensate valve 8 is a normal condensate valve. The other condensate outlet of each high-pressure heater is connected to the condenser via a corresponding third condensate valve 9; the third condensate valve 9 is an emergency condensate valve.

[0056] Accordingly, step S2 includes S21b, S22b, S23b and S24b, as follows: S21b: If the actual liquid level of the high-pressure heater is less than the first liquid level threshold and a switching signal from the first liquid level switch of the high-pressure heater is received, then the second drain valve 8 corresponding to the high-pressure heater is controlled to drain water to the deaerator, and all the drain water is delivered to the deaerator. At the same time, the first isolation valve 3 and the second isolation valve 4 corresponding to the high-pressure heater group are controlled to open, the third isolation valve 5 is controlled to close, and the fourth isolation valve 6 and the first drain valve 7 corresponding to the high-pressure heater are controlled to open.

[0057] S22b: If the actual liquid level of the high-pressure heater is greater than or equal to the first liquid level threshold and less than the second liquid level threshold, and a switching signal from the second liquid level switch of the high-pressure heater is received, then the second drain valve 8 corresponding to the high-pressure heater is controlled to drain water to the deaerator. Furthermore, the opening of the third drain valve 9 corresponding to the high-pressure heater is controlled according to the actual liquid level for emergency drain adjustment, with some drain water being sent to the condenser. Simultaneously, the first isolation valve 3 and the second isolation valve 4 corresponding to the high-pressure heater group are controlled to open, the third isolation valve 5 is controlled to close, and the fourth isolation valve 6 and the first drain valve 7 corresponding to the high-pressure heater are controlled to open.

[0058] S23b: If the actual liquid level of the high-pressure heater is greater than or equal to the second liquid level threshold and less than the third liquid level threshold, and a switching signal from the third liquid level switch of the high-pressure heater is received, then the second drain valve 8 corresponding to the high-pressure heater is controlled to drain water to the deaerator. Simultaneously, the third drain valve 9 corresponding to the high-pressure heater is fully opened for emergency drain regulation, with some drain water being sent to the condenser. At the same time, the first isolation valve 3 and the second isolation valve 4 corresponding to the high-pressure heater group are opened, the third isolation valve 5 is closed, and the fourth isolation valve 6 and the first drain valve 7 corresponding to the high-pressure heater are opened.

[0059] S24b: If the actual liquid level of the high-pressure heater is greater than or equal to the third liquid level threshold and the switch signal of the fourth liquid level switch of the high-pressure heater is received, then the first isolation valve 3 and the second isolation valve 4 corresponding to the high-pressure heater group are closed, the third isolation valve 5 is opened, and the fourth isolation valve 6 and the first drain valve 7 corresponding to the high-pressure heater are closed to isolate the entire high-pressure heater group.

[0060] The actual liquid level of the high-pressure heater is determined by taking the median value after sorting the liquid level measurement signal values ​​of at least three liquid level transmitters 1 according to their numerical values.

[0061] In some embodiments, the conventional island of the aforementioned nuclear power plant includes at least one row of high-pressure heater groups, with each row of high-pressure heater groups including at least one high-pressure heater, such as... Figure 3 As shown, each high-pressure heater group includes at least two high-pressure heaters connected in series, and the water supply between the at least two high-pressure heaters connected in series is connected. For example, each high-pressure heater group includes a first high-pressure heater and a second high-pressure heater connected in series. The water supply inlet of the first high-pressure heater is connected to the outlet of the water supply pump via a first isolation valve 3 corresponding to its column. The water supply outlet of the first high-pressure heater is connected to the water supply inlet of the second high-pressure heater. The water supply outlet of the second high-pressure heater is connected to the water supply header via a second isolation valve 4 corresponding to its column.

[0062] The condensate drains between any two high-pressure heaters connected in series are specifically connected via a second condensate drain valve 8 of one of the high-pressure heaters. For example, one condensate drain outlet of the second high-pressure heater is connected to the condenser via the corresponding second condensate drain valve 8, while the other condensate drain outlet of the second high-pressure heater is connected to the second condensate drain inlet of the first high-pressure heater via a corresponding third condensate drain valve 9.

[0063] Accordingly, step S21b includes: if the actual liquid level of the high-pressure heater is less than the first liquid level threshold and a switching signal from the first liquid level switch of the high-pressure heater is received, then the second drain valve 8 corresponding to the high-pressure heater is controlled to drain water to the next-stage high-pressure heater in series. Simultaneously, the first isolation valve 3 and the second isolation valve 4 corresponding to the series of high-pressure heaters are controlled to open, the third isolation valve 5 is controlled to close, and the fourth isolation valve 6 and the first drain valve 7 corresponding to the high-pressure heater are controlled to open.

[0064] Alternatively, step S21b includes: if the actual liquid level of the high-pressure heater is less than the first liquid level threshold and a switching signal from the first liquid level switch of the high-pressure heater is received, then the second drain valve 8 corresponding to the high-pressure heater is controlled to directly drain water to the deaerator. Simultaneously, the first isolation valve 3 and the second isolation valve 4 corresponding to the high-pressure heater group are controlled to open, the third isolation valve 5 is controlled to close, and the fourth isolation valve 6 and the first drain valve 7 corresponding to the high-pressure heater are controlled to open.

[0065] Step S22b includes: if the actual liquid level of the high-pressure heater is greater than or equal to the first liquid level threshold and less than the second liquid level threshold, and a switching signal from the second liquid level switch of the high-pressure heater is received, then the second drain valve 8 corresponding to the high-pressure heater is controlled to drain water to the next-stage high-pressure heater in series. Furthermore, the opening degree of the third drain valve 9 corresponding to the high-pressure heater is controlled according to the actual liquid level for emergency drain adjustment, with some drain water being transported to the condenser. Simultaneously, the first isolation valve 3 and the second isolation valve 4 corresponding to the high-pressure heater group are controlled to open, the third isolation valve 5 is controlled to close, and the fourth isolation valve 6 and the first drain valve 7 corresponding to the high-pressure heater are controlled to open.

[0066] Alternatively, step S22b includes: if the actual liquid level of the high-pressure heater is greater than or equal to the first liquid level threshold and less than the second liquid level threshold, and a switching signal from the second liquid level switch of the high-pressure heater is received, then the second drain valve 8 corresponding to the high-pressure heater is controlled to directly drain water to the deaerator. Furthermore, the opening degree of the third drain valve 9 corresponding to the high-pressure heater is controlled according to the actual liquid level for emergency drain adjustment, with some drain water being transported to the condenser. Simultaneously, the first isolation valve 3 and the second isolation valve 4 corresponding to the high-pressure heater group are controlled to open, the third isolation valve 5 is controlled to close, and the fourth isolation valve 6 and the first drain valve 7 corresponding to the high-pressure heater are controlled to open.

[0067] Step S23b includes: if the actual liquid level of the high-pressure heater is greater than or equal to the second liquid level threshold and less than the third liquid level threshold, and a switching signal from the third liquid level switch of the high-pressure heater is received, then the second drain valve 8 corresponding to the high-pressure heater is controlled to drain water to the next-stage high-pressure heater in series. Simultaneously, the third drain valve 9 corresponding to the high-pressure heater is fully opened for emergency drain regulation, with some drain water being transported to the condenser. At the same time, the first isolation valve 3 and the second isolation valve 4 corresponding to the high-pressure heater group are opened, the third isolation valve 5 is closed, and the fourth isolation valve 6 and the first drain valve 7 corresponding to the high-pressure heater are opened.

[0068] Alternatively, step S23b includes: if the actual liquid level of the high-pressure heater is greater than or equal to the second liquid level threshold and less than the third liquid level threshold, and a switching signal from the third liquid level switch of the high-pressure heater is received, then the second drain valve 8 corresponding to the high-pressure heater is controlled to directly drain water to the deaerator. Furthermore, the third drain valve 9 corresponding to the high-pressure heater is controlled to fully open for emergency drain regulation, with some drain water being transported to the condenser. Simultaneously, the first isolation valve 3 and the second isolation valve 4 corresponding to the high-pressure heater group are controlled to open, the third isolation valve 5 is controlled to close, and the fourth isolation valve 6 and the first drain valve 7 corresponding to the high-pressure heater are controlled to open.

[0069] In some embodiments, the conventional island of the aforementioned nuclear power plant includes at least one row of high-pressure heater groups, each row comprising at least one high-pressure heater; or, the conventional island of the aforementioned nuclear power plant includes at least one row of high-pressure heater groups, each row comprising at least two high-pressure heaters connected in series. Figure 3 As shown, the conventional island of a nuclear power plant includes at least two rows of high-pressure heater groups, such as row A and row B. The conventional island also includes a fifth isolation valve 10 corresponding to each high-pressure heater. In every two rows of high-pressure heater groups, the high-pressure heaters in the two rows are connected to each other via the fifth isolation valve 10.

[0070] Accordingly, step S24b further includes: controlling the closure of the fifth isolation valve 10 corresponding to the high-pressure heater of the unit.

[0071] The above embodiment describes the control method for the level transmitter 1 under normal and fault-free conditions. Steps S25, S26, and S27 below describe the control method for the level transmitter 1 under fault conditions. Therefore, step S2 further includes: S25: If the deviation of the level measurement signal value of at least one level transmitter 1 in the high-pressure heater from the level measurement signal values ​​of at least two other level transmitters 1 exceeds the deviation limit, then at least one level transmitter 1 is determined to be faulty. The average value of the level measurement signal values ​​of the other at least two level transmitters 1 is taken, and the opening degree of the third drain valve 9 corresponding to the high-pressure heater is controlled based on the average value for emergency drain adjustment. In some other embodiments, an alarm is also generated to remind the operator to pay attention and notify the maintenance personnel for handling.

[0072] S26: If the level measurement signal values ​​of at least two level transmitters 1 in the high-pressure heater exceed the measurement limit, then at least two level transmitters 1 are determined to be faulty. The opening of the third drain valve 9 corresponding to the high-pressure heater is controlled based on the level measurement signal value of at least one non-faulty level transmitter 1 for emergency drain adjustment. In some other embodiments, an alarm is also generated to remind operators to pay attention and notify maintenance personnel for handling.

[0073] S27: If the level measurement signal values ​​of at least three level transmitters 1 in the high-pressure heater exceed the measurement limit, or the deviation between the level measurement signal values ​​of any two level transmitters 1 exceeds the deviation limit, then at least three level transmitters 1 are deemed to be faulty. The opening of the third drain valve 9 corresponding to the high-pressure heater is controlled based on the effective value of the previous control output for emergency drain adjustment. In some other embodiments, the valve is switched to manual mode and a red alarm is triggered to remind the operator to intervene, alerting the operator to the situation and notifying maintenance personnel for handling.

[0074] It is understood that the above embodiments only illustrate some implementation methods of the present invention, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can freely combine the above embodiments or technical features without departing from the concept of the present invention, and can also make several modifications and improvements, all of which fall within the protection scope of the present invention. That is, the embodiments described in "some embodiments" can be freely combined with any of the embodiments above and below. Therefore, all equivalent transformations and modifications made within the scope of the claims of the present invention should be covered by the claims of the present invention.

Claims

1. A method for controlling the liquid level of a high-pressure heater in the conventional island of a nuclear power plant, characterized in that, The conventional island of the nuclear power plant includes a controller and at least one row of high-pressure heater groups. Each row of high-pressure heater groups includes at least one high-pressure heater. Each high-pressure heater is equipped with at least three level transmitters (1). The at least three level transmitters (1) are used to continuously measure the liquid level in real time and output the liquid level measurement signal to the controller. The high-pressure heater liquid level control method is applied to the controller and includes the following steps: S1: Receive level measurement signals from at least three level transmitters (1) of each of the high-pressure heaters; S2: Perform a comprehensive analysis of the liquid level measurement signals of at least three liquid level transmitters (1) of each high-pressure heater, and adjust the normal drainage and emergency drainage of the corresponding high-pressure heater according to the comprehensive analysis results.

2. The method for controlling the liquid level of the high-pressure heater in the conventional island of a nuclear power plant according to claim 1, characterized in that, At least three of the level transmitters (1) are respectively arranged on at least three different DCS cards.

3. The method for controlling the liquid level of the high-pressure heater in the conventional island of a nuclear power plant according to claim 1, characterized in that, The conventional island of the nuclear power plant also includes a feedwater pump, a feedwater header, a secondary side pipeline of the steam generator, a high-pressure cylinder of the steam turbine, a steam-water separator reheater, a deaerator, a condenser, and a third isolation valve (5), as well as a first isolation valve (3) and a second isolation valve (4) corresponding to each column of the high-pressure heater group, and a fourth isolation valve (6), a first drain valve (7), a second drain valve (8), and a third drain valve (9) corresponding to each of the high-pressure heaters; The feedwater inlet of each high-pressure heater group is connected to the outlet of the feedwater pump via the first isolation valve (3) corresponding to it, and the feedwater outlet of each high-pressure heater group is connected to the feedwater main pipe via the second isolation valve (4) corresponding to it; another outlet of the feedwater pump is connected to the feedwater main pipe via the third isolation valve (5); the feedwater main pipe is connected to the secondary side pipeline of the steam generator; each high-pressure heater is connected to the high-pressure cylinder of the steam turbine via the fourth isolation valve (6) corresponding to it, and the high-pressure cylinder of the steam turbine... The cylinder outputs heating steam to the high-pressure heater through extraction steam; the condensate inlet of each high-pressure heater is connected to the condensate outlet of the steam-water separation reheater via the first condensate valve (7) corresponding to it; one condensate outlet of each high-pressure heater is connected to the deaerator via the second condensate valve (8) corresponding to it, the second condensate valve (8) being a normal condensate valve; the other condensate outlet of each high-pressure heater is connected to the condenser via the third condensate valve (9) corresponding to it, the third condensate valve (9) being an emergency condensate valve; Step S2 includes: S21a: If the liquid level measurement signal value of at least three liquid level transmitters (1) of the high-pressure heater is less than the first liquid level threshold, then control the second drain valve (8) corresponding to the high-pressure heater to drain water to the deaerator, and all the drain water is delivered to the deaerator; at the same time, control the opening of the first isolation valve (3) and the second isolation valve (4) corresponding to the high-pressure heater group, control the closing of the third isolation valve (5), and control the opening of the fourth isolation valve (6) and the first drain valve (7) corresponding to the high-pressure heater. S22a: If the liquid level measurement signal value of at least three liquid level transmitters (1) of the high-pressure heater is greater than or equal to the first liquid level threshold and less than the second liquid level threshold, then control the second drain valve (8) set for the high-pressure heater to drain water to the deaerator; and, sort the liquid level measurement signal values ​​of at least three liquid level transmitters (1) according to their numerical values ​​and take the middle value, and control the opening of the third drain valve (9) set for the high-pressure heater to perform emergency drain adjustment, and send part of the drain water to the condenser; at the same time, control the opening of the first isolation valve (3) and the second isolation valve (4) set for the high-pressure heater group, control the closing of the third isolation valve (5), and control the opening of the fourth isolation valve (6) and the first drain valve (7) set for the high-pressure heater. S23a: If the level measurement signal value of more than half of the three level transmitters (1) of the high-pressure heater is greater than or equal to the second level threshold and less than the third level threshold, then the second drain valve (8) corresponding to the high-pressure heater is controlled to drain water to the deaerator; and the third drain valve (9) corresponding to the high-pressure heater is controlled to be fully opened for emergency drain adjustment, and part of the drain water is transported to the condenser; at the same time, the first isolation valve (3) and the second isolation valve (4) corresponding to the high-pressure heater group are controlled to be opened, and the third isolation valve (5) is controlled to be closed, and the fourth isolation valve (6) and the first drain valve (7) corresponding to the high-pressure heater are controlled to be opened. S24a: If the liquid level measurement signal value of more than half of the three liquid level transmitters (1) of the high-pressure heater is greater than or equal to the third liquid level threshold, then the first isolation valve (3) and the second isolation valve (4) corresponding to the high-pressure heater group in the row are closed, the third isolation valve (5) is opened, and the fourth isolation valve (6) and the first drain valve (7) corresponding to the high-pressure heater are closed to isolate the entire row of high-pressure heater groups.

4. The method for controlling the liquid level of the high-pressure heater in the conventional island of a nuclear power plant according to claim 3, characterized in that, Each column of the high-pressure heater group includes at least two high-pressure heaters connected in series, and the water supply between the at least two high-pressure heaters connected in series is connected; the condensate drain between each pair of high-pressure heaters connected in series is connected. Step S21a includes: if the liquid level measurement signal value of at least three liquid level transmitters (1) of the high-pressure heater is less than the first liquid level threshold, then control the second drain valve (8) corresponding to the high-pressure heater to drain water to the next-level series high-pressure heater, or directly drain water to the deaerator; at the same time, control the opening of the first isolation valve (3) and the second isolation valve (4) corresponding to the high-pressure heater group, control the closing of the third isolation valve (5), and control the opening of the fourth isolation valve (6) and the first drain valve (7) corresponding to the high-pressure heater. Step S22a includes: if the liquid level measurement signal value of at least three liquid level transmitters (1) of the high-pressure heater is greater than or equal to the first liquid level threshold and less than the second liquid level threshold, then control the second drain valve (8) corresponding to the high-pressure heater to drain water to the next-level series high-pressure heater, or directly drain water to the deaerator; and, sort the liquid level measurement signal values ​​of at least three liquid level transmitters (1) according to their numerical values ​​and take the middle value, and control the third drain valve (9) corresponding to the high-pressure heater to perform emergency drain adjustment based on the middle value, and deliver part of the drain water to the condenser; at the same time, control the opening of the first isolation valve (3) and the second isolation valve (4) corresponding to the high-pressure heater group, control the closing of the third isolation valve (5), and control the opening of the fourth isolation valve (6) and the first drain valve (7) corresponding to the high-pressure heater. Step S23a includes: if the level measurement signal value of more than half of the three level transmitters (1) of the high-pressure heater is greater than or equal to the second level threshold and less than the third level threshold, then control the second drain valve (8) corresponding to the high-pressure heater to drain water to the next-stage high-pressure heater in series, or directly drain water to the deaerator; and control the third drain valve (9) corresponding to the high-pressure heater to be fully open for emergency drain adjustment, and partially drain water to the condenser; at the same time, control the opening of the first isolation valve (3) and the second isolation valve (4) corresponding to the high-pressure heater group, control the closing of the third isolation valve (5), and control the opening of the fourth isolation valve (6) and the first drain valve (7) corresponding to the high-pressure heater.

5. The method for controlling the liquid level of the high-pressure heater in the conventional island of a nuclear power plant according to claim 1, characterized in that, Each of the high-pressure heaters is also provided with at least four liquid level switches (2), which are used to trigger at different liquid level thresholds and output switch signals to the controller. Step S1 includes: receiving level measurement signals from at least three level transmitters (1) and switching signals from at least four level switches (2) of each of the high-pressure heaters; Step S2 includes: performing a comprehensive analysis of the liquid level measurement signals of at least three liquid level transmitters (1) and the switching signals of at least four liquid level switches (2) for each high-pressure heater, and adjusting the normal drainage and emergency drainage of the corresponding high-pressure heater according to the comprehensive analysis results.

6. The method for controlling the liquid level of the high-pressure heater in the conventional island of a nuclear power plant according to claim 5, characterized in that, At least four of the liquid level switches (2) include a first liquid level switch for triggering when the liquid level is below a first liquid level threshold, a second liquid level switch for triggering when the liquid level reaches the first liquid level threshold, a third liquid level switch for triggering when the liquid level reaches the second liquid level threshold, and a fourth liquid level switch for triggering when the liquid level reaches the third liquid level threshold. The conventional island of the nuclear power plant also includes a feedwater pump, a feedwater header, a secondary side pipeline of the steam generator, a high-pressure cylinder of the steam turbine, a steam-water separator reheater, a deaerator, a condenser, and a third isolation valve (5), as well as a first isolation valve (3) and a second isolation valve (4) corresponding to each column of the high-pressure heater group, and a fourth isolation valve (6), a first drain valve (7), a second drain valve (8), and a third drain valve (9) corresponding to each of the high-pressure heaters; The feedwater inlet of each high-pressure heater group is connected to the outlet of the feedwater pump via the first isolation valve (3) corresponding to it, and the feedwater outlet of each high-pressure heater group is connected to the feedwater main pipe via the second isolation valve (4) corresponding to it; another outlet of the feedwater pump is connected to the feedwater main pipe via the third isolation valve (5); the feedwater main pipe is connected to the secondary side pipeline of the steam generator; each high-pressure heater is connected to the high-pressure cylinder of the steam turbine via the fourth isolation valve (6) corresponding to it, and the high-pressure cylinder of the steam turbine... The cylinder outputs heating steam to the high-pressure heater through extraction steam; the condensate inlet of each high-pressure heater is connected to the condensate outlet of the steam-water separation reheater via the first condensate valve (7) corresponding to it; one condensate outlet of each high-pressure heater is connected to the deaerator via the second condensate valve (8) corresponding to it, the second condensate valve (8) being a normal condensate valve; the other condensate outlet of each high-pressure heater is connected to the condenser via the third condensate valve (9) corresponding to it, the third condensate valve (9) being an emergency condensate valve; Step S2 includes: S21b: If the actual liquid level of the high-pressure heater is less than the first liquid level threshold and the switch signal of the first liquid level switch of the high-pressure heater is received, then the second drain valve (8) corresponding to the high-pressure heater is controlled to drain water to the deaerator, and all the drain water is delivered to the deaerator; at the same time, the first isolation valve (3) and the second isolation valve (4) corresponding to the high-pressure heater group are controlled to open, the third isolation valve (5) is controlled to close, and the fourth isolation valve (6) and the first drain valve (7) corresponding to the high-pressure heater are controlled to open. S22b: If the actual liquid level of the high-pressure heater is greater than or equal to the first liquid level threshold and less than the second liquid level threshold, and the switch signal of the second liquid level switch of the high-pressure heater is received, then the second drain valve (8) corresponding to the high-pressure heater is controlled to drain water to the deaerator; and, according to the actual liquid level, the opening degree of the third drain valve (9) corresponding to the high-pressure heater is controlled to perform emergency drain adjustment, and part of the drain water is transported to the condenser; at the same time, the first isolation valve (3) and the second isolation valve (4) corresponding to the high-pressure heater group are controlled to open, and the third isolation valve (5) is controlled to close, and the fourth isolation valve (6) and the first drain valve (7) corresponding to the high-pressure heater are controlled to open. S23b: If the actual liquid level of the high-pressure heater is greater than or equal to the second liquid level threshold and less than the third liquid level threshold, and the switch signal of the third liquid level switch of the high-pressure heater is received, then the second drain valve (8) corresponding to the high-pressure heater is controlled to drain water to the deaerator; and the third drain valve (9) corresponding to the high-pressure heater is controlled to be fully opened for emergency drain adjustment, and part of the drain water is transported to the condenser; at the same time, the first isolation valve (3) and the second isolation valve (4) corresponding to the high-pressure heater group are controlled to be opened, and the third isolation valve (5) is controlled to be closed, and the fourth isolation valve (6) and the first drain valve (7) corresponding to the high-pressure heater are controlled to be opened. S24b: If the actual liquid level of the high-pressure heater is greater than or equal to the third liquid level threshold and the switch signal of the fourth liquid level switch of the high-pressure heater is received, then the first isolation valve (3) and the second isolation valve (4) corresponding to the high-pressure heater group in the row are closed, the third isolation valve (5) is opened, and the fourth isolation valve (6) and the first drain valve (7) corresponding to the high-pressure heater are closed to isolate the entire row of high-pressure heater groups; The actual liquid level of the high-pressure heater is determined by taking the median value after sorting the liquid level measurement signal values ​​of at least three liquid level transmitters (1) according to their numerical values.

7. The method for controlling the liquid level of the high-pressure heater in the conventional island of a nuclear power plant according to claim 6, characterized in that, Each column of the high-pressure heater group includes at least two high-pressure heaters connected in series; the water supply connection between the at least two high-pressure heaters connected in series is connected; the condensate connection between each pair of high-pressure heaters connected in series is connected. Step S21b includes: if the actual liquid level of the high-pressure heater is less than the first liquid level threshold and a switching signal of the first liquid level switch of the high-pressure heater is received, then the second drain valve (8) corresponding to the high-pressure heater is controlled to drain water to the next-level series high-pressure heater, or directly to the deaerator; at the same time, the first isolation valve (3) and the second isolation valve (4) corresponding to the high-pressure heater group are controlled to open, the third isolation valve (5) is controlled to close, and the fourth isolation valve (6) and the first drain valve (7) corresponding to the high-pressure heater are controlled to open. Step S22b includes: if the actual liquid level of the high-pressure heater is greater than or equal to the first liquid level threshold and less than the second liquid level threshold, and a switching signal of the second liquid level switch of the high-pressure heater is received, then the second drain valve (8) corresponding to the high-pressure heater is controlled to drain water to the next-stage high-pressure heater in series, or directly to the deaerator; and, according to the actual liquid level, the opening degree of the third drain valve (9) corresponding to the high-pressure heater is controlled to perform emergency drain adjustment, and part of the drain water is transported to the condenser; at the same time, the first isolation valve (3) and the second isolation valve (4) corresponding to the high-pressure heater group are controlled to open, and the third isolation valve (5) is controlled to close, and the fourth isolation valve (6) and the first drain valve (7) corresponding to the high-pressure heater are controlled to open. S23b: If the actual liquid level of the high-pressure heater is greater than or equal to the second liquid level threshold and less than the third liquid level threshold, and the switch signal of the third liquid level switch of the high-pressure heater is received, then the second drain valve (8) corresponding to the high-pressure heater is controlled to drain water to the next-level series high-pressure heater, or directly to the deaerator; and the third drain valve (9) corresponding to the high-pressure heater is controlled to be fully opened for emergency drain adjustment, and part of the drain water is transported to the condenser; at the same time, the first isolation valve (3) and the second isolation valve (4) corresponding to the high-pressure heater group are controlled to be opened, and the third isolation valve (5) is controlled to be closed, and the fourth isolation valve (6) and the first drain valve (7) corresponding to the high-pressure heater are controlled to be opened.

8. The method for controlling the liquid level of the high-pressure heater in the conventional island of a nuclear power plant according to claim 3, 4, 6 or 7, characterized in that, The conventional island of the nuclear power plant includes at least two rows of the high-pressure heater groups; the conventional island of the nuclear power plant also includes a fifth isolation valve (10) corresponding to each of the high-pressure heaters, and in every two rows of the high-pressure heater groups, the high-pressure heaters in the two rows are connected to the fifth isolation valve (10) corresponding to them; Step S24a or step S24b further includes: controlling the closure of the fifth isolation valve (10) provided for the high-pressure heater of the unit.

9. The method for controlling the liquid level of the high-pressure heater in the conventional island of a nuclear power plant according to claim 3, 4, 6 or 7, characterized in that, Step S2 also includes: S25: If the level measurement signal value of at least one of the level transmitters (1) in the high-pressure heater deviates from the level measurement signal values ​​of at least two other level transmitters (1) by more than the deviation limit, then at least one level transmitter (1) is judged to be faulty. The average value of the level measurement signal values ​​of the other at least two level transmitters (1) is taken, and the opening degree of the third drain valve (9) corresponding to the high-pressure heater is controlled according to the average value to perform emergency drain adjustment. S26: If the liquid level measurement signal value of at least two of the liquid level transmitters (1) in the high-pressure heater exceeds the measurement limit, then at least two of the liquid level transmitters (1) are judged to be faulty. The opening degree of the third drain valve (9) set for the high-pressure heater is controlled according to the liquid level measurement signal value of at least one of the liquid level transmitters (1) that is not faulty, and emergency drain adjustment is performed. S27: If the liquid level measurement signal value of at least three of the liquid level transmitters (1) in the high-pressure heater exceeds the measurement limit, or the deviation between the liquid level measurement signal values ​​of two liquid level transmitters (1) exceeds the deviation limit, then at least three of the liquid level transmitters (1) are judged to be faulty, and the opening degree of the third drain valve (9) corresponding to the high-pressure heater is controlled according to the effective value of the previous control output to perform emergency drain adjustment.

10. The method for controlling the liquid level of the high-pressure heater in the conventional island of a nuclear power plant according to claim 3, 4, 6 or 7, characterized in that, The conventional island of the nuclear power plant also includes a sixth isolation valve (11). One branch of the water supply main pipe is connected to the secondary side pipe of the steam generator, and the other branch of the water supply main pipe is connected to the condenser via the sixth isolation valve (11).

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