Reactor pressure vessel liquid level measurement and correction method, device and measurement system

Abstract

The invention relates to a liquid level measurement and correction method for a reactor pressure vessel. The method comprises the following steps: dividing the pressure vessel into a plurality of measurement intervals along a pressure difference direction; acquiring first measurement data of the pressure vessel, calculating the initial measurement liquid level height of the pressure vessel according to the first measurement data, assigning the initial measurement liquid level height to the variable liquid level height to be corrected, judging the measurement interval and correcting; according to the corrected liquid level height and the to-be-corrected liquid level height before correction, the measurement intervals where the corrected liquid level height and the to-be-corrected liquid level height are located are compared, when the corrected liquid level height and the to-be-corrected liquid level height belong to different measurement intervals, the to-be-corrected liquid level height is replaced with the current corrected liquid level height, and the latest to-be-corrected liquid level height continues to be corrected; when the latest corrected liquid level height and the latest to-be-corrected liquid level height are located in the same measurement interval, the latest corrected liquid level height is used as the liquid level height of the coolant in the pressure container; on-line correction of the liquid level of the coolant in the pressure container can be achieved, and the liquid level characterization precision is improved.

Description

Technical Field

[0001] The invention relates to the technical field of nuclear reactors, and in particular to a method, a device and a measuring system for measuring and correcting the liquid level of a reactor pressure vessel. Background Art

[0002] At present, some SMR (Small Modular Reactor) small modular reactors use integrated self-stabilizing pressure vessels, that is, the reactor core, main heat exchanger (heat exchanger or steam generator), pressure vessel and other key components are integrated in the pressure vessel, and the pressurizer designed for maintaining the pressure of the primary circuit of the traditional large pressurized water reactor is cancelled. The vapor phase space above the pressure vessel and the compressible characteristics of the vapor are used to achieve the self-stabilization of the primary circuit; therefore, unlike the full water state in the pressure vessel of the traditional large pressurized water reactor, this integrated modular self-stabilizing pressure vessel has both liquid and vapor phase spaces; when measuring the liquid level of the pressure vessel with vapor and liquid phase spaces, the existing liquid level measurement method usually has insufficient measurement accuracy due to the changes in coolant temperature and pressure, especially during the operation of the reactor, as the reactor power changes, the temperature and pressure of the primary circuit also change, thereby affecting the measurement accuracy of the reactor coolant (water) level. Therefore, how to calculate the accurate level of the reactor coolant (water) level is a technical problem that needs to be solved in this case. Summary of the invention

[0003] In view of the shortcomings of the prior art, an object of the present invention is to provide a reactor pressure vessel liquid level measurement and correction method, device and measurement system, wherein the reactor pressure vessel measurement and correction method can calculate and correct the accurate liquid level of the coolant in the pressure vessel.

[0004] To achieve the above-mentioned purpose and other related purposes, the present invention provides a reactor pressure vessel liquid level measurement and correction method, which is applied to a reactor pressure vessel measurement system, wherein the reactor pressure vessel measurement system at least includes a balance tank, a pressure difference measuring element and a connecting pipeline, wherein one end of the connecting pipeline connecting the balance tank and the pressure difference measuring element in series is used to communicate with the top of the pressure vessel, and the other end is used to communicate with the bottom of the pressure vessel, and the balance tank is arranged flush with the top of the pressure vessel; the method comprises the following steps:

[0005] Acquire first measurement data of the pressure vessel, the first measurement data at least including pressure difference data between the upper and lower ends of the pressure vessel, temperature, pressure and interval height data of each measurement interval, and temperature, pressure and liquid phase height data of the balance tank;

[0006] Calculate the initial measured liquid level height of the pressure vessel according to the first measurement data, and assign the initial measured liquid level height to the variable liquid level height to be corrected;

[0007] Determine the measurement interval according to the height of the liquid level to be corrected, correct the height of the liquid level to be corrected according to the measurement interval and the first measurement data, and obtain the corrected liquid level;

[0008] According to the corrected liquid level height and the to-be-corrected liquid level height before correction, the measurement intervals in which the two are located are compared. When the measurement interval in which the corrected liquid level height is located and the measurement interval in which the to-be-corrected liquid level height before correction is located belong to different measurement intervals, the to-be-corrected liquid level height is updated or replaced with the current corrected liquid level height to obtain the latest to-be-corrected liquid level height, and the latest to-be-corrected liquid level height is continuously corrected to obtain the latest corrected liquid level height;

[0009] Until the latest corrected liquid level height and the latest to-be-corrected liquid level height are in the same measuring interval, the latest corrected liquid level height is taken as the accurate liquid level height of the coolant in the pressure vessel.

[0010] In one embodiment of the present invention, the step of calculating the initial measured liquid level height of the pressure vessel according to the first measurement data and assigning the initial measured liquid level height to the variable liquid level height to be corrected comprises:

[0011] Calculate the internal pressure difference between the upper and lower ends of the pressure vessel based on the pressure difference data between the upper and lower ends of the pressure vessel and the liquid phase pressure, temperature, and liquid phase height data of the balance tank;

[0012] Calculate the average density of the liquid phase and the average density of the vapor phase in the pressure vessel according to the temperature and pressure data of each measurement interval, and calculate the initial measurement liquid level height according to the average density of the liquid phase and the average density of the vapor phase of the coolant in the pressure vessel and the internal pressure difference between the upper and lower ends of the pressure vessel;

[0013] The initial measured liquid level height is assigned to the variable liquid level height to be corrected, and the measurement interval in which the liquid level to be corrected is located is determined according to the liquid level height to be corrected and the interval height data of each measurement interval.

[0014] In one embodiment of the present invention, the step of calculating the internal pressure difference between the upper and lower ends of the pressure vessel according to the pressure difference data between the upper and lower ends of the pressure vessel and the pressure, temperature, and liquid phase height data of the balance tank includes:

[0015] Calculate the liquid phase density of the balance tank according to the pressure and temperature data of the balance tank;

[0016] Calculate the pressure difference data of the balance tank according to the liquid density and liquid height data of the balance tank;

[0017] The internal pressure difference between the upper and lower ends of the pressure vessel is calculated based on the pressure difference data of the balance tank and the pressure difference data of the upper and lower ends of the pressure vessel.

[0018] In one embodiment of the present invention, the step of determining the measurement interval according to the liquid level to be corrected, correcting the liquid level to be corrected according to the measurement interval and the first measurement data, and obtaining the corrected liquid level comprises:

[0019] Calculate the average density of the liquid phase and the average density of the vapor phase in each measuring interval according to the coolant pressure and temperature data in each measuring interval;

[0020] According to the liquid phase density, vapor phase density and the height of the corresponding measuring interval in each measuring interval, the liquid phase pressure difference and vapor phase pressure difference in the single-phase state of each measuring interval are calculated;

[0021] The corrected liquid level height of the liquid level to be corrected is calculated based on the internal pressure difference between the upper and lower ends of the pressure vessel, the average vapor phase density of the measuring interval where the liquid level height to be corrected is located, the average liquid phase density, the height of the measuring interval, the liquid phase pressure difference of all measuring intervals below the measuring interval, and the vapor phase pressure difference of all measuring intervals above the measuring interval.

[0022] In one embodiment of the present invention, the step of calculating the average liquid phase density and the average vapor phase density of each measurement interval according to the coolant pressure and temperature data of each measurement interval includes:

[0023] Determine the average coolant pressure and average coolant temperature in each measuring interval according to the coolant pressure or temperature data in each measuring interval;

[0024] Calculate the average liquid phase volume and the average vapor phase volume of each measuring interval according to the average coolant pressure and average temperature of each measuring interval;

[0025] The average density of the liquid phase and the average density of the vapor phase in each measuring interval are determined according to the average liquid phase volume and the average vapor phase volume in each measuring interval.

[0026] In one embodiment of the present invention, the step of calculating the corrected liquid level height of the liquid level to be corrected according to the internal pressure difference between the upper and lower ends of the pressure vessel, the average vapor phase density of the measurement interval where the liquid level height to be corrected is located, the average liquid phase density, the height of the measurement interval, the liquid phase pressure difference of all measurement intervals below the measurement interval, and the vapor phase pressure difference of all measurement intervals above the measurement interval includes:

[0027] According to the existence of vapor phase and liquid phase space in the measurement interval where the liquid level height to be corrected is located, the measurement intervals above the measurement interval where the liquid level height to be corrected is all vapor phase, the measurement intervals below the measurement interval where the liquid level height to be corrected is all liquid phase, and the average vapor phase density or the average liquid phase density of the remaining measurement intervals other than the measurement interval where the liquid level height to be corrected is located and the interval heights of the remaining measurement intervals, the zone pressure differences of the remaining measurement intervals are calculated;

[0028] The zone pressure difference of the measuring interval where the liquid level to be corrected is located is calculated according to the difference between the zone pressure difference of the measuring interval where the liquid level to be corrected is located and the sum of the zone pressure differences of the other measuring intervals;

[0029] The corrected liquid level height of the liquid level to be corrected is calculated based on the obtained partition pressure difference of the measurement interval where the liquid level height to be corrected is located, the liquid phase average density and the vapor phase average density of the measurement interval where the liquid level height to be corrected is located.

[0030] To achieve the above-mentioned and other related purposes, the present invention provides a reactor pressure vessel liquid level measurement and correction device, comprising:

[0031] The acquisition module is configured to acquire first measurement data of the pressure vessel, wherein the first measurement data at least includes pressure difference data between the upper and lower ends of the pressure vessel, temperature, pressure and interval height data of each measurement interval, and temperature, pressure and liquid phase height data of the balance tank;

[0032] A calculation and correction module receives the data transmitted by the acquisition module and is configured to calculate the initial measured liquid level height of the pressure vessel according to the first measurement data and assign it to the liquid level height to be corrected which is a variable, and determine the measurement interval in which the liquid level height to be corrected is located;

[0033] Correcting the liquid level to be corrected according to the measurement interval in which the liquid level to be corrected is located and the first measurement data to obtain a corrected liquid level;

[0034] According to the corrected liquid level height and the to-be-corrected liquid level height before correction, the measurement intervals in which the two are located are compared. When the measurement interval in which the corrected liquid level height is located and the measurement interval in which the to-be-corrected liquid level height before correction is located belong to different measurement intervals, the current corrected liquid level height is assigned to the to-be-corrected liquid level height as a variable to obtain an updated to-be-corrected liquid level height, and the latest to-be-corrected liquid level height is continuously corrected to obtain the latest corrected liquid level height;

[0035] Until the latest corrected liquid level height and the to-be-corrected liquid level height before correction are in the same measuring interval, the latest corrected liquid level height is taken as the accurate liquid level height of the coolant in the pressure vessel;

[0036] The information exchange module receives the data transmitted by the calculation and correction module, outputs the liquid level height of the pressure vessel, and provides the necessary human-machine interface.

[0037] To achieve the above-mentioned purpose and other related purposes, the present invention provides a reactor pressure vessel measurement system for measuring basic measurement data of the pressure vessel, including:

[0038] A balance tank is configured to be flush with the top of the pressure vessel, and one end of the balance tank is used to communicate with the top of the pressure vessel;

[0039] Temperature measuring elements are arranged in each measuring interval divided by the vertical height pressure difference direction of the balance tank and the pressure vessel;

[0040] The pressure measuring elements are arranged in each measuring interval divided by the vertical height pressure difference direction of the balance tank and the pressure vessel;

[0041] The differential pressure measuring element is configured such that one end can be connected to the bottom of the pressure vessel and the other end is connected to the balance tank, and is used to measure the pressure difference between the upper and lower ends of the pressure vessel.

[0042] In one embodiment of the present invention, the balancing tank and the differential pressure measuring element are arranged in series through a connecting pipeline, and one end of the balancing tank can be detachably connected to the top pressure taking port set at the top of the pressure vessel through the connecting pipeline; one end of the differential pressure measuring element can be detachably connected to the bottom pressure taking port set at the bottom of the pressure vessel through the connecting pipeline.

[0043] In one embodiment of the present invention, at least two temperature measuring elements and pressure measuring elements are provided in each of the measuring intervals;

[0044] Some of the temperature measuring elements are also arranged in the balancing tank and / or the connecting pipeline, and some of the pressure measuring elements are also arranged in the balancing tank and / or the connecting pipeline.

[0045] In summary, in the present invention, since the balancing tank is located outside the pressure vessel, it is less affected by the temperature and pressure changes in the pressure vessel. Therefore, its pressure is relatively stable. The balancing tank is regarded as a reference end arranged outside the pressure vessel. By measuring the temperature and pressure data of the coolant in the balancing tank and the differential pressure measured by the differential pressure element as a set of reference data to calculate the pressure difference between the upper and lower pressure ports in the reactor pressure vessel, it can to a certain extent solve the technical problem that the temperature and pressure in the reactor pressure vessel change with the change of the reactor power, thereby affecting the pressure difference measurement accuracy between the upper and lower pressure ports in the reactor pressure vessel, and ultimately affecting the coolant level measurement and characterization accuracy in the reactor pressure vessel; and in this case, by logically dividing the space in the pressure vessel into multiple measurement intervals along the longitudinal height pressure difference direction, and through the cooperation of the balancing tank, the temperature measuring element, the pressure measuring element and the differential pressure measuring element, the basic measurement data of the pressure vessel can be measured, and the coolant level height of the reactor pressure vessel is calculated and corrected based on the basic measurement data, thereby improving the measurement correction accuracy of the liquid level height in the reactor pressure vessel. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0047] Figure 1 This is a schematic diagram of the structure of the reactor pressure vessel liquid level measurement system of the technical solution 1 in the improvement process of the present invention;

[0048] Figure 2 This is a schematic diagram of the structure of the reactor pressure vessel liquid level measurement system of the technical solution 2 in the improvement process of the present invention;

[0049] Figure 3 A schematic diagram of the structure of a reactor pressure vessel measurement system in one embodiment of the present invention;

[0050] Figure 4 It is a structural flow chart of a reactor pressure vessel liquid level measurement and correction method in one embodiment of the present invention;

[0051] Figure 5 It is a block diagram of the principle of calculating the average density of the liquid phase and the vapor phase in each measuring interval in one embodiment of the present invention;

[0052] Figure 6 This is a block diagram of the theoretical pressure difference calculation principle under the single-phase state (vapor phase or liquid phase) of zone A in one embodiment of the present invention;

[0053] Figure 7 This is a block diagram of the theoretical pressure difference calculation principle under the single-phase state (vapor phase or liquid phase) of the B zone in one embodiment of the present invention;

[0054] Figure 8 This is a block diagram of the theoretical pressure difference calculation principle under the single-phase state (vapor phase or liquid phase) of the C zone in one embodiment of the present invention;

[0055] Fig. 9 A block diagram of the internal pressure difference calculation principle of the upper and lower ends of a pressure vessel in one embodiment of the present invention;

[0056] Fig.10 This is a block diagram of the principle of calculating the initial measurement liquid level height of the coolant in one embodiment of the present invention;

[0057] Fig.11 This is a block diagram of the calculation principle of liquid level correction in zone A in one embodiment of the present invention;

[0058] Fig.12 This is a block diagram of the calculation principle of liquid level correction in zone B in one embodiment of the present invention;

[0059] Fig.13This is a block diagram of the calculation principle of liquid level correction in zone C in one embodiment of the present invention;

[0060] Fig.14 This is a block diagram of the principle of iterative correction of the initial measured liquid level height in one embodiment of the present invention;

[0061] Fig.15 It is a structural block diagram of a reactor pressure vessel liquid level measurement and correction device in one embodiment of the present invention;

[0062] Component number description: pressure vessel 1, balance tank 2, temperature measuring element 3, pressure measuring element 4, differential pressure measuring element 5, connecting pipeline 6, reactor coolant level 7, reactor core 8, reactor coolant vapor phase space 9, reactor coolant liquid phase space 10, top pressure port 11, bottom pressure port 12, reactor coolant 13, liquid level measuring point one X1, liquid level measuring point one heating temperature sensor X11, liquid level measuring point one non-heating temperature sensor X12, liquid level measuring point two X2, liquid level measuring point two heating temperature sensor X21, liquid level measuring point two non-heating temperature sensor X22, liquid level measuring point three X3, liquid level measuring point three heating temperature sensor X31, liquid level measuring point three non-heating temperature sensor X32. DETAILED DESCRIPTION

[0063] The following is an explanation of the embodiments of the present invention by specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the features in the following embodiments and the embodiments can be combined with each other without conflict. It should also be understood that the terms used in the embodiments of the present invention are intended to describe specific embodiments, rather than to limit the scope of protection of the present invention. The test methods for which specific conditions are not specified in the following examples are usually carried out under conventional conditions or according to the conditions recommended by the manufacturers.

[0064] See also Figures 1 to 15. It should be noted that the structures, proportions, sizes, etc. illustrated in the drawings of this specification are only used to match the contents disclosed in the specification for people familiar with this technology to understand and read, and are not used to limit the limiting conditions for the implementation of the present invention, so they have no substantial technical significance. Any modification of the structure, change in the proportional relationship, or adjustment of the size, without affecting the effects and purposes that can be achieved by the present invention, should still fall within the scope of the technical content disclosed by the present invention. At the same time, the terms such as "upper", "lower", "left", "right", "middle" and "one" quoted in this specification are only for the convenience of description, and are not used to limit the scope of the implementation of the present invention. Changes or adjustments in their relative relationships should also be regarded as the scope of the implementation of the present invention without substantially changing the technical content.

[0065] When numerical ranges are given in the embodiments, it should be understood that unless otherwise specified in the present invention, both endpoints of each numerical range and any value between the two endpoints can be selected. Unless otherwise defined, all technical and scientific terms used in the present invention are familiar to those skilled in the art and the description of the present invention, and any method, device and material of the prior art similar or equivalent to the method, device and material in the embodiments of the present invention can also be used to implement the present invention.

[0066] With the growth of global population and economic development, the demand for energy continues to increase. As a clean energy, nuclear energy is increasingly used. However, traditional large pressurized water reactors still have great limitations in terms of safety, economy and flexibility. Small modular reactors generally adopt advanced non-passive passive safety systems, and the reactor structure design is simple and has inherent safety characteristics. Compared with large nuclear power plants, small modular reactors are highly adaptable and can flexibly adjust the deployment scale according to actual needs. In addition to power generation, they can also be used for various purposes such as regional heating, seawater desalination, industrial heating, etc., with high economy and flexibility.

[0067] The coolant level in the reactor pressure vessel is critical to the safe operation of the reactor. Accurate coolant level measurement ensures that the reactor core is always covered with enough coolant to effectively remove the heat generated by the nuclear fuel. If the coolant level is too low, the fuel may overheat and be damaged, or even cause the fuel to melt, leading to serious safety accidents. The coolant level also directly affects the thermal hydraulic stability within the reactor. If the level is too low, the coolant flow may be affected, resulting in local hot spots and system instability. Accurate level measurement also helps maintain the pressure balance of the reactor coolant system. The primary circuit pressure control equipment relies on level data to adjust the system pressure to prevent the coolant from boiling or over-pressurizing.

[0068] In the process of improving this case, there is the following technical solution 1, such as Figure 1As shown, the first technical solution uses a temperature sensor to perform discrete measurement of the water level of the pressure vessel, that is, liquid level measurement points are set at several different elevations of the reactor pressure vessel, and two temperature sensors are set at each measurement point. One of the temperature sensors is heated, and the other temperature sensor is not heated. The water level is determined by measuring the temperature difference between the two temperature sensors. The measurement principle is based on the change of heat transfer. The temperature difference between the two temperature sensors depends on the heat transfer coefficient of the surrounding medium. That is, when the coolant level exceeds the measurement point, both temperature sensors are immersed in the coolant. Due to the good heat transfer ability of the coolant, the temperature difference measured by the two temperature sensors is small. When the coolant level is lower than the measurement point, the temperature of the heating temperature sensor rises rapidly due to the deterioration of the heat transfer conditions, and the temperature difference measured by the two temperature sensors increases significantly. Therefore, the temperature difference between the temperature sensors can indicate whether the water level of the reactor pressure vessel is lower than the location of the heating temperature sensor.

[0069] Although the above-mentioned technical solution 1 is based on the temperature difference of the temperature sensor to measure the liquid level of the reactor pressure vessel, it is simple in principle, but it also has some shortcomings and limitations. The following are some of the shortcomings. Specifically, first, the liquid level cannot be measured continuously. Since the measuring points are arranged discretely, it can only be measured when the liquid level exceeds the measuring point, that is, it can only indicate whether the liquid level exceeds the measuring point, but it cannot monitor the liquid level continuously; if you want to improve the accuracy of liquid level monitoring, you can only do it by adding multiple discrete points. Second, the measurement accuracy, the change in temperature difference may be affected by many factors, such as the response time of the sensor, the fluctuation of the heating power, etc., which may lead to inaccurate temperature difference judgment, resulting in inaccurate liquid level judgment. Third, environmental factors interfere, and the complex flow and heat transfer conditions inside the reactor may affect the accuracy of the temperature difference. For example, changes in the coolant flow rate and the flow of gas around the sensor will affect the temperature measurement.

[0070] In the process of improving this case, there is the following technical solution 2, such as Figure 2 As shown, the second technical solution uses the differential pressure method to measure the pressure difference at two different heights in the reactor pressure vessel to calculate the liquid level. Using the principle of fluid statics, when the distance and density difference between the two measuring points are known, the liquid level height can be determined by the pressure difference. A more specific technical solution is as follows:

[0071] Two pressure tapping ports are set at different heights of the reactor pressure vessel, one at the bottom of the pressure vessel (high pressure point) and the other at the top of the pressure vessel (low pressure point). The two pressure tapping ports are connected to a differential pressure transmitter through a pressure pipe. The differential pressure transmitter measures the pressure difference between the two pressure sensors. The measured value of the pressure difference will be used to calculate the liquid level. According to the principle of fluid statics, the pressure difference of the liquid column can be expressed as:

[0072] ΔP=ρ*g*h, so h=ΔP / ρ*g. Where: ΔP is the measured pressure difference; ρ is the liquid density; g is the acceleration of gravity; h is the liquid level.

[0073] The basic principle of the above-mentioned technical solution 2 for measuring the liquid level based on the pressure difference principle is simple, but there is a relatively obvious problem that the temperature and pressure in the reactor pressure vessel change with the reactor power, thereby affecting the reactor coolant density and ultimately affecting the coolant level measurement accuracy.

[0074] In response to the problems existing in the prior art and the above-mentioned technical solutions 1 and 2, this case provides a reactor pressure vessel measurement system, a reactor pressure vessel liquid level measurement and correction method, and a reactor pressure vessel liquid level measurement and correction device.

[0075] It should be understood that the pressure vessel 1 in this case can specifically refer to a reactor pressure vessel, or it can refer to another type of pressure vessel having a liquid phase and a gas phase, in which the temperature and pressure inside the container always change due to changes in heating power; that is, the reactor pressure vessel measurement system in this case can measure the basic measurement data of the reactor pressure vessel, and can also measure the basic measurement data of the other type of pressure vessel mentioned above.

[0076] This case is based on the spatial partitioning of the pressure vessel 1 and the average temperature and average pressure data of the coolant in each measurement interval, and accurately corrects the liquid level measurement value online, thereby improving the accuracy and reliability of the liquid level characterization. This method combines the comprehensive measurement of temperature, pressure and differential pressure, and uses a correction algorithm to perform real-time online correction of the measured liquid level, making the liquid level characterization result more accurate and reliable, thereby supporting the safe operation of the reactor. In the present invention, first, it is possible to realize real-time detection and judgment of the interval where the liquid level in the reactor pressure vessel is located; second, the average density of the vapor phase and liquid phase in each measurement interval in the reactor pressure vessel is calculated and corrected in real time online; third, the coolant liquid level is corrected in real time online based on the corrected average density of the coolant vapor phase and liquid phase in each measurement interval in the reactor pressure vessel; fourth, the measurement interval to which the liquid level belongs is iteratively corrected. This case is based on the basic principle of differential pressure measurement of liquid level, and uses the correction algorithm provided by this scheme to perform real-time online correction of the measured liquid level, thereby improving the accuracy of liquid level characterization.

[0077] See also Figure 3The present invention provides a reactor pressure vessel measurement system, including a balance tank 2, a temperature measuring element 3, a pressure measuring element 4 and a differential pressure measuring element 5; the pressure vessel 1 is a measured object, and the pressure vessel 1 is logically divided into at least two measurement intervals along the vertical height pressure difference direction; the balance tank 2 is configured to be flush with the top of the pressure vessel 1, and one end is used to communicate with the top of the pressure vessel 1; the temperature measuring element 3 is arranged in the balance tank 2 and each measurement interval; the pressure measuring element 4 is arranged in the balance tank 2 and each measurement interval; the differential pressure measuring element 5 is configured to have one end that can communicate with the bottom of the pressure vessel 1, and the other end is connected to the balance tank 2, and is used to measure the pressure difference between the upper and lower ends of the pressure vessel 1.

[0078] It should be noted that, generally, the vertical height pressure difference direction is the vertical direction, the vapor coolant is at the top, and the liquid coolant is at the bottom. The pressure vessel 1 can also be divided into three, four or more measurement intervals. The more measurement intervals there are, the more accurate the liquid level height of the pressure vessel measured and calculated is. Generally, there are multiple temperature measuring elements 3 and pressure measuring elements 4, which are evenly dispersed in the balance tank 2 and each measurement interval to measure the temperature and pressure data of the pressure vessel 1 and the balance tank 2. Generally, there are a large number of temperature measuring elements 3 and pressure measuring elements 4, which are evenly dispersed in each measurement interval and the balance tank 2, and the measured data will be more accurate. The balance tank 2 is flush with the top of the pressure vessel 1, and it does not need to be completely flush in the strict sense. The height difference between the top of the balance tank 2 and the top of the pressure vessel 1 only needs to meet the liquid level height measurement requirements in the reactor pressure vessel. Since the balance tank 2 is located outside the pressure vessel 1, it is less affected by the temperature and pressure changes in the pressure vessel 1. Therefore, the environment in which the balance tank 2 is located is relatively stable, and its pressure is stable. The balance tank 2 is regarded as a reference end arranged outside the pressure vessel 1. The temperature and pressure in the balance tank 2 and the differential pressure data measured by the differential pressure element 5 are measured as a set of reference data to calculate the internal pressure difference between the upper and lower pressure ports in the reactor pressure vessel, thereby being able to solve to a certain extent the technical problem that the temperature and pressure in the reactor pressure vessel change with the change of the reactor power, thereby affecting the measurement accuracy of the internal pressure difference between the upper and lower pressure ports in the reactor pressure vessel, and ultimately affecting the measurement and characterization accuracy of the coolant liquid level in the reactor pressure vessel; at the same time, by logically dividing the space in the pressure vessel 1 into multiple measurement intervals along the longitudinal height direction, the accuracy of the measurement data is improved, and it is also beneficial to the calculation and correction of the measured liquid level height of the reactor pressure vessel, thereby further improving the characterization accuracy of the liquid level height in the reactor pressure vessel.

[0079] As an optional embodiment of this case, please refer to Figure 3The balancing tank 2 and the differential pressure measuring element 5 are connected in series through a connecting pipe 6, and one end of the balancing tank 2 can be detachably connected to a top pressure taking port 11 set at the top of the pressure vessel 1 through the connecting pipe 6; one end of the differential pressure measuring element 5 can be detachably connected to a bottom pressure taking port 12 set at the bottom of the pressure vessel 1 through the connecting pipe 6.

[0080] It should be noted that by setting a top pressure port 11 on the top of the pressure vessel 1 to connect with the balance tank 2, setting a bottom pressure port 12 on the bottom of the pressure vessel 1 to connect with the differential pressure measuring element 5, one end of the connecting pipe 6 is connected to the balance tank 2, and the other end is connected to the differential pressure measuring element 5, it is ensured that the balance tank 2, the differential pressure measuring element 5 and the upper and lower ends of the pressure vessel 1 are connected, so that the accuracy of the pressure difference between the upper and lower ends of the pressure vessel 1 is calculated by taking the balance tank 2 as the reference end and by combining the temperature and pressure data of the balance tank 2 and the pressure difference data between the upper and lower ends of the pressure vessel 1. The detachable connection method facilitates the reactor pressure vessel measurement system to measure different pressure vessels 1 and is easy to repair.

[0081] As an optional embodiment of this case, please refer to Figure 3 At least two temperature measuring elements 3 and pressure measuring elements 4 are provided in each measuring interval; some temperature measuring elements 3 are also provided in the balancing tank 2 and / or the connecting pipeline 6, and some pressure measuring elements 4 are also provided in the balancing tank 2 and / or the connecting pipeline 6.

[0082] It should be noted that at least two temperature measuring elements 3 and pressure measuring elements 4 are provided in each measuring interval to ensure the accuracy of the measured data; multiple temperature measuring elements 3 distributed along the pressure difference direction are used to measure the average temperature of each measuring interval, and multiple pressure measuring elements 4 distributed along the pressure difference direction are used to measure the average pressure of each measuring interval; some temperature measuring elements 3 can measure the liquid phase temperature of the reference end, and two or more of these temperature measuring elements 3 are generally provided to improve the accuracy of the measurement. Since the pressure at the top of the balancing tank 2 needs to be measured, the pressure measuring element 4 is generally provided at the top of the balancing tank 2.

[0083] As an optional embodiment of this case, please refer to Figure 3, the temperature measuring element 3 and the pressure measuring element 4 are both redundant measuring elements. It should be understood that in order to improve the measurement accuracy of the temperature measuring element 3 and the pressure measuring element 4 at each measuring point, in addition to setting the normal measuring elements, multiple additional sensors for improving the measurement accuracy and reliability can be installed; for example, multiple temperature measuring elements 3 or pressure measuring elements 4 are set at each measuring point, the data measured by multiple temperature measuring elements 3 or pressure measuring elements 4 can be averaged, and when the main sensor fails, the backup sensor can take over immediately to ensure the continuous operation of the system, thereby increasing the accuracy and reliability of temperature and pressure data measurement.

[0084] Furthermore, in this case, more sets of redundant sensors can be used to improve the measurement accuracy of the average temperature and average pressure of each measurement area;

[0085] Furthermore, the coolant level interval of the pressure vessel 1 is divided into different numbers of intervals, for example, more measurement intervals are divided to improve the calculation accuracy of the theoretical pressure difference of each measurement interval, such as the liquid phase pressure difference and vapor phase pressure difference of each measurement interval.

[0086] See also Figure 4 The present invention provides a reactor pressure vessel liquid level measurement and correction method, which is applied to a reactor pressure vessel measurement system, wherein the reactor pressure vessel measurement system at least comprises a balance tank 2, a pressure difference measuring element 5 and a connecting pipeline 6, wherein one end of the connecting pipeline 6 connecting the balance tank 2 and the pressure difference measuring element 5 in series is used to communicate with the top of the pressure vessel 1, and the other end is used to communicate with the bottom of the pressure vessel 1, and the balance tank 2 is arranged flush with the top of the pressure vessel 1; the method comprises the following steps:

[0087] The longitudinal height of the pressure vessel 1 is divided into several measuring areas. For the convenience of description, the three measuring areas A, B and C are divided as an example, and the heights of the measuring areas are HA, HB and HC respectively;

[0088] S1: Acquire first measurement data of the pressure vessel 1, the first measurement data at least including pressure difference data between the upper and lower ends of the pressure vessel 1, temperature, pressure and interval height data of each measurement interval, and temperature, pressure and liquid phase height data of the balance tank 2;

[0089] S2: Calculate the initial measured liquid level height of the pressure vessel 1 according to the first measurement data and assign it to the variable to be corrected liquid level height; Specifically, calculate the average vapor phase density and the average liquid phase density (ρ) of each measurement interval A, B, and C according to the average measurement values ​​of the temperature and pressure instruments arranged in each measurement area. A液、 ρ A汽、 ρ B液、 ρ B汽、 ρ C液、 ρ C汽), average density of coolant liquid phase in pressure vessel 1 Average density of coolant vapor phase in pressure vessel 1 See Figure 5 ;

[0090] According to the heights HA, HB, HC of the measurement intervals A, B, and C and the average density of the vapor phase and the average density of the liquid phase (ρ A液、 ρ A汽、 ρ B液、 ρ B汽、 ρ C液、 ρ C汽 ) Calculate the theoretical pressure difference P of each measuring interval under single-phase state (liquid or vapor) A液 , P A汽 , P B液 , P B汽 , P C液 , P C汽 , that is, the pressure difference between each measuring interval, see Figure 6-8 ;

[0091] The pressure difference DP between the upper and lower pressure ports of the pressure vessel 1 is measured by the differential pressure measuring element 5; the reference end pressure P0 is calculated according to the liquid phase density at the reference end and the liquid phase height H0 at the reference end; the internal pressure difference P of the upper and lower pressure ports of the pressure vessel 1 is calculated according to the reference end pressure P0 and the pressure difference DP 内 , see Fig. 9 ;

[0092] According to the internal pressure difference P of the upper and lower pressure ports of the pressure vessel 1 内 , average density of coolant liquid phase Average density of coolant vapor phase Calculate the initial measured coolant level H and assign it to the variable to be corrected level H 待校正 According to the height of the liquid level to be corrected and the heights HA, HB and HC of each measuring interval, it is determined in which measuring interval the height of the liquid level to be corrected is located. Specifically, the total height difference h between the upper and lower measuring points of the pressure vessel 1 is 总 =HA+HB+HC; Assume that the height of the liquid level to be corrected is H 待校正 , then the vapor phase height is h 总 -H 待校正 ; Internal pressure difference P of upper and lower measuring points of pressure vessel 1 内 =P0-DP, where DP is the differential pressure value measured by the differential pressure element 5; according to the static pressure formula, the internal pressure difference between the upper and lower measuring points of the pressure vessel 1 P 内 Passed formula P 内=P0-DP is calculated as a known quantity; by analyzing the equation, the initial measured liquid level height H can be obtained; the initial measured liquid level height H is assigned to the variable to be corrected liquid level height H 待校正 , see Fig.10 .

[0093] S3: Determine H 待校正 The measurement interval and the H according to the first measurement data 待校正 Perform calibration to obtain the corrected liquid level height H 校正后 ; see Figure 11-13 ;

[0094] Specifically, according to H 待校正 There are vapor phase and liquid phase in the measurement interval, H 待校正 The upper measurement interval of the measurement interval is all vapor phase, H 待校正 The measurement interval below the measurement interval is all liquid phase, and H 待校正 The vapor phase density ρ of the remaining measurement intervals outside the measurement interval 汽 Or liquid density ρ 液 and the interval height (HA or HB or HC) of the remaining measurement intervals, and calculate two of the partition pressure differences PA, PB, and PC of the remaining measurement intervals; wherein, when only liquid phase exists in the measurement interval, according to the formula P = ρ 液 *h*g calculation, when there is only vapor phase in the measurement interval, according to the formula P = ρ 汽 *h*g calculation.

[0095] According to H 待校正 The pressure difference of the measurement interval is equal to the difference between the internal pressure difference of the upper and lower ends of the pressure vessel 1 and the sum of the pressure differences of the other measurement intervals. 内 =P0-DP=PA+PB+PC, calculate H 待校正 The pressure difference of the measurement zone. For example, H 待校正 In interval A, PA = P 内 -PB-PC=(P0-DP)-ρ B汽 *HB*g-ρ c汽 *HC*g, where DP is the measured value of the differential pressure measuring element 5 and P0 is the reference end pressure.

[0096] Specifically, when H 待校正 Located in interval A, according to the partition pressure difference PA of the measurement interval where the liquid level to be corrected is located, the liquid phase density ρ of the measurement interval where the liquid level to be corrected is located A液 and vapor phase density ρ A汽 Calculate the corrected liquid level height H of the liquid level to be corrected 校正后 The method is: Assume that the actual liquid level in area A is h A, then the vapor phase height in zone A is HA-h A , static pressure in area A PA = static pressure of liquid phase in area A + static pressure of vapor phase in area A = ρ A液 *h A *g+ρ A汽 *(HA-h A )*g; Analyzing the formula, the actual liquid level in area A is h A , that is, H 待校正 Corrected liquid level height H 校正后 =h A .

[0097] S4: According to the corrected liquid level height H 校正后 and the liquid level to be corrected H 待校正 Compare the measurement intervals of the two. When the corrected liquid level height H 校正后 The measurement interval and the height of the liquid level to be corrected before correction H 待校正 When the measurement intervals belong to different measurement intervals, the variable liquid level height to be corrected H 待校正 Update or replace with the current corrected liquid level height H 校正后 To obtain the latest liquid level height H to be corrected 待校正 , and continue to adjust the latest liquid level height H 待校正 Perform calibration to obtain the latest calibrated liquid level height;

[0098] Until the latest corrected liquid level height and the to-be-corrected liquid level height before correction are in the same measuring interval, the latest corrected liquid level height is taken as the actual accurate liquid level height of the coolant in the pressure vessel 1; see Fig.14 ;

[0099] It should be noted that the first measurement data of the reactor pressure vessel can be obtained by arranging the temperature measuring element 3, the pressure measuring element 4 and the differential pressure measuring element 5. The pressure difference data between the upper and lower ends of the pressure vessel 1 is measured by the differential pressure measuring element 5; the remaining data are measured by the temperature measuring element 3 and the pressure measuring element 4; the height of each measurement interval is known by measuring the height of each interval during the advance area division; and the liquid phase height of the balance tank 2 is a known quantity in steady state, because the balance tank 2 is normally full of liquid level, and the water exceeding the upper opening of the balance tank 2 will flow back into the pressure vessel 1, and the liquid level of the balance tank 2 is fixed in steady state; and the temperature measuring element 3 can be, for example, a temperature measuring instrument such as a thermal resistor sensor, a thermocouple sensor, etc. that meets the use requirements; the pressure measuring element 4 can be, for example, a capacitive, inductive or piezoresistive pressure sensor. The initial measured liquid level height is the pressure vessel liquid level height calculated by the preliminary measurement of the first measurement data, and the initial measured liquid level height is assigned to the variable to be corrected liquid level H 待校正, used in the subsequent liquid level correction process. The corrected liquid level is the height of the pressure vessel liquid level obtained by correcting the liquid level to be corrected through further data. It should be understood that the correction process in this case is for a certain moment. At a certain moment, all measurement parameters are static, that is, in a correction process, all measurement parameters will not be updated in real time. After the correction, the first measurement data will be updated. During the operation of the reactor, the liquid level correction algorithm will be called at different times to correct the actual liquid level in the pressure vessel in real time. For example, correction is performed once every 5 minutes and once every 10 minutes.

[0100] In this case, by correcting the initial measured liquid level height, the actual liquid level of the reactor pressure vessel coolant can be more accurately represented, which is of great safety significance for ensuring the safe operation of the reactor, preventing core melt, maintaining the primary water charge, avoiding coolant boiling, and stabilizing reactor operation.

[0101] In addition, accurate coolant level can truly reflect the amount of coolant water in the first circuit, help optimize the supply and discharge of coolant, and reduce unnecessary coolant loss. In the event of an accident or abnormal situation, accurate level data can provide timely and reliable information to help operators make correct decisions and improve emergency response capabilities; through accurate level control, the risk of radioactive material leakage during nuclear reactor operation can be effectively reduced, protecting the environment and public health; accurate level measurement and control improves the safety and reliability of reactor operation, helps to enhance public trust in nuclear energy, and promotes the sustainable development of nuclear energy. Therefore, accurate measurement of reactor pressure vessel coolant level has important application value in ensuring safe operation of reactors, optimizing operation and control, improving economic benefits, supporting emergency response, and improving environmental and social benefits.

[0102] In this case, the detailed steps of each step of the reactor pressure vessel liquid level measurement method applied to the reactor pressure vessel are as follows:

[0103] S0: logically dividing the space in the pressure vessel 1 into a plurality of measurement intervals along the longitudinal height direction;

[0104] S1: Acquire first measurement data of the pressure vessel, the first measurement data at least including pressure difference data between the upper and lower ends of the pressure vessel 1, temperature, pressure and interval height data of each measurement interval, and temperature, pressure and liquid phase height data of the balance tank 2;

[0105] S2: Calculate the initial measured liquid level height of the pressure vessel 1 according to the first measurement data, and assign the initial measured liquid level height to the variable to be corrected liquid level height (H 待校正 ); the specific steps of S2 include:

[0106] S21: Calculating the internal pressure difference between the upper and lower ends of the pressure vessel 1 according to the pressure difference data between the upper and lower ends of the pressure vessel 1 and the liquid phase pressure, temperature, and liquid phase height data of the balance tank 2;

[0107] S21: The step of calculating the internal pressure difference between the upper and lower ends of the pressure vessel 1 according to the pressure difference data between the upper and lower ends of the pressure vessel 1 and the liquid phase pressure, temperature, and liquid phase height data of the balance tank 2 comprises:

[0108] S211: Calculate the liquid phase density of the balance tank 2 according to the pressure and temperature data of the balance tank 2; specifically, according to the industrial formula of the International Association of Water and Water Vapor Sciences IAPWS-IF97, the calculation formula for the liquid phase density of the balance tank 2 is as follows:

[0109] ρ0=1 / υ0;

[0110] In the formula, ρ0 is the average density of the liquid phase in the balancing tank 2; υ0 is the average specific volume of the liquid phase in the balancing tank 2; the average specific volume υ0 of the liquid phase in the balancing tank 2 is calculated according to IAPWS-IF97 based on the average pressure and average temperature data of the balancing tank 2 or obtained by looking up the table.

[0111] S212: Calculate the pressure data of the reference end according to the average density of the liquid phase and the liquid phase height data of the balance tank 2, according to the formula: P0 = ρ0*H0*g, H0 is the liquid phase height of the reference end, and the pressure P0 of the reference end can be calculated;

[0112] S213: Calculate the internal pressure difference between the upper and lower ends of the pressure vessel 1 according to the pressure data of the reference end and the pressure difference data between the upper and lower ends of the pressure vessel 1; specifically, the internal pressure difference between the upper and lower measuring points of the pressure vessel 1, i.e., the internal pressure difference P of the pressure vessel 1 内 =P0-DP, where DP is the measured value of the differential pressure measuring element 5;

[0113] S22: Calculate the average density of the liquid phase and the average density of the vapor phase in the pressure vessel 1 according to the temperature and pressure data of each measurement interval, calculate the initial measured liquid level height according to the average density of the liquid phase and the average density of the vapor phase of the coolant in the pressure vessel 1 and the internal pressure difference of the pressure vessel 1, and assign it to the variable to be corrected liquid level height;

[0114] Among them, in step S22, the step of calculating the average density of the liquid phase and the average density of the vapor phase in the pressure vessel 1 according to the average temperature and average pressure data of each measurement interval includes:

[0115] S221: Calculating the average density of the liquid phase in the pressure vessel 1 according to the average temperature and average pressure values ​​of all measurement intervals;

[0116] S222: Calculate the average density of the vapor phase in the pressure vessel 1 based on the average temperature and average pressure values ​​of all measurement intervals.

[0117] S23: Determine the measurement interval where the liquid level height to be corrected is located according to the interval height data of each measurement interval. It should be noted that the internal pressure difference of the pressure vessel 1 refers to the internal pressure difference between the upper and lower measuring points of the pressure vessel 1, the liquid phase refers to the part of the coolant in a liquid state, and the vapor phase refers to the part of the coolant in a vaporized state above the liquid coolant.

[0118] S3: According to the liquid level height H to be corrected 待校正 The measurement interval and the first measurement data are to be corrected liquid level height H 待校正 The steps of performing calibration and obtaining the calibrated liquid level height and the measuring interval of the calibrated liquid level height include:

[0119] S31: Calculate the average liquid phase density and the average vapor phase density of each measurement interval according to the coolant pressure and temperature data of each measurement interval; the specific steps of S31 include:

[0120] S311: Determine the average liquid phase specific volume and the average vapor phase specific volume of each measurement interval according to the average coolant pressure and average temperature data of each measurement interval;

[0121] S312: Determine the average liquid phase density and the average vapor phase density of each measurement interval according to the average liquid phase specific volume and the average vapor phase specific volume of each measurement interval;

[0122] Specifically, IAPWS-IF97 is an industrial formula of the International Association of Water and Water Vapor Sciences, which aims to provide high-precision and fast calculation of water and water vapor thermodynamic property data. The average density of the liquid phase and the average density of the vapor phase in each measurement interval in this case can be calculated by the following formula:

[0123] The average density of the liquid phase in each measurement interval is obtained according to the average temperature and average pressure of each measurement interval. The calculation formula of the average density of the liquid phase in each measurement interval is as follows:

[0124] ρ1=1 / υ1;

[0125] In the formula, ρ1 is the average density of the liquid phase in the corresponding measurement interval; υ1 is the average specific volume of the liquid phase in the corresponding measurement interval; the average specific volume of the liquid phase in the corresponding measurement interval υ1 is calculated according to the average pressure and average temperature data of the coolant in the corresponding measurement interval according to IAPWS-IF97 or obtained by looking up the table;

[0126] The average vapor phase density of each measurement interval is obtained based on the average temperature and average pressure of each measurement interval; the calculation formula for the average vapor phase density of each measurement interval is as follows:

[0127] ρ2=1 / υ2;

[0128] In this formula, ρ2 is the average density of the vapor phase in the corresponding measurement interval; υ2 is the average specific volume of the vapor phase in the corresponding measurement interval; the average specific heat capacity υ2 of the vapor phase in the corresponding measurement interval is calculated according to IAPWS-IF97 or obtained by looking up the table based on the average pressure and average temperature data of the vapor phase in the corresponding measurement interval. That is, the average specific volume of the coolant in this state can be calculated through the temperature and pressure data, and the reciprocal of the specific volume is the density.

[0129] S32: Calculate the liquid phase pressure difference and vapor phase pressure difference in the single-phase state of each measuring interval according to the average density of the liquid phase and the average density of the vapor phase in each measuring interval and the height of the corresponding measuring interval;

[0130] S33: According to the internal pressure difference of the pressure vessel 1 and the height H of the liquid level to be corrected 待校正 The average density of the vapor phase, the average density of the liquid phase, the height of the measurement interval, the liquid phase pressure difference of all measurement intervals below the measurement interval, and the vapor phase pressure difference of all measurement intervals above the measurement interval are used to calculate the liquid level height H to be corrected. 待校正 Corrected liquid level height H 校正后 ; S33 specific steps include:

[0131] S331: Based on the liquid level height H to be corrected 待校正 There are vapor phase and liquid phase in the measurement interval, and the liquid level height to be corrected H 待校正 The upper measurement interval of the measurement interval is all vapor phase, and the liquid level height to be corrected H 待校正 The measuring interval below the measuring interval is all liquid phase, and the liquid level height to be corrected H 待校正 The average density of the vapor phase or the average density of the liquid phase of the remaining measurement intervals other than the measurement interval and the interval height of the remaining measurement intervals are used to calculate the zone pressure difference of the remaining measurement intervals;

[0132] S332: According to the liquid level height H to be corrected 待校正 The pressure difference of the measurement interval is equal to the difference between the internal pressure difference of pressure vessel 1 and the sum of the pressure differences of the other measurement intervals. The liquid level height H to be corrected is calculated. 待校正 The pressure difference of the measurement interval;

[0133] S333: Based on the obtained liquid level height H to be corrected 待校正 The pressure difference of the measurement interval and the height of the liquid level to be corrected H 待校正 The liquid level height H to be corrected is calculated from the average density of the liquid phase and the average density of the vapor phase in the measurement interval. 待校正 Corrected liquid level height H 待校后 .

[0134] It should be noted that the liquid level height to be corrected H 待校正The remaining measurement intervals outside the measurement interval generally only have one of the liquid phase or the vapor phase, that is, the liquid level height H to be corrected 待校正 The zone pressure difference of the remaining measurement intervals other than the measurement interval is the liquid phase pressure difference or the vapor phase pressure difference.

[0135] S34: Determine the measurement interval in which the corrected liquid level is located according to the corrected liquid level height and the interval heights of each measurement interval.

[0136] It should be noted that the average density of the liquid phase and the average density of the vapor phase in each measurement interval refer to the average temperature and average pressure measured in each measurement interval and calculated according to the process described in S311 and S312 to obtain the average density of the liquid phase and the average density of the vapor phase in each measurement interval; the liquid phase pressure difference in the measurement interval refers to the pressure difference between the top and bottom of the coolant in the liquid state in the measurement interval; the vapor phase pressure difference in the measurement interval refers to the pressure difference between the top and bottom of the coolant in the vapor state in the measurement interval; the height of the measurement interval refers to the height value between the top and bottom of the measurement interval. Generally, when the liquid level to be corrected is located in a certain measurement interval, the measurement interval has both liquid coolant and vapor coolant, that is, the measurement interval has a liquid phase and a vapor phase; and the measurement interval above the measurement interval where the height of the liquid level to be corrected is located has only vapor coolant, that is, only a vapor phase, and the measurement interval below the measurement interval where the height of the liquid level to be corrected is located has only liquid coolant, that is, only a liquid phase.

[0137] S4: comparing the measurement intervals of the corrected liquid level height and the liquid level height to be corrected according to the two. When the measurement interval of the corrected liquid level height and the measurement interval of the liquid level height to be corrected before correction belong to different measurement intervals, the liquid level height to be corrected is updated or replaced by the current corrected liquid level height to obtain the latest liquid level height to be corrected, and the latest liquid level height to be corrected is continuously corrected to obtain the latest corrected liquid level height;

[0138] When the latest corrected liquid level height and the to-be-corrected liquid level height before correction are located in the same measuring interval, the latest corrected liquid level height is taken as the accurate liquid level height of the coolant in the pressure vessel.

[0139] Specifically, the basic process of the reactor pressure vessel measurement system to which the reactor pressure vessel liquid level measurement correction method is applied will be briefly described below:

[0140] Step 1: Divide the longitudinal height of the pressure vessel 1 into several measurement areas. For ease of description, the three measurement areas A, B, and C are divided into three measurement areas, and their heights are HA, HB, and HC respectively; see Figure 3 ;

[0141] Step 2: Calculate the average vapor phase density and liquid phase average density (ρ) of each measurement interval A, B, and C based on the average measurement values ​​of the temperature and pressure instruments arranged in each measurement area. A液、 ρ A汽、 ρ B液、 ρ B汽、 ρ C液、 ρ C汽 ), average density of coolant liquid phase in pressure vessel 1 Average density of coolant vapor phase in pressure vessel 1 See Figure 5 ;

[0142] Step 3: According to the heights HA, HB, HC of the measurement intervals A, B, and C and the average density of the vapor phase and the average density of the liquid phase (ρ A液、 ρ A汽、 ρ B液、 ρ B汽、 ρ C液、 ρ C汽 ) Calculate the theoretical pressure difference P of each measuring interval under single-phase state (liquid or vapor) A液 , P A汽 , P B液 , P B汽 , P C液 , P C汽 , that is, the pressure difference between each measuring interval, see Figure 6-8 ;

[0143] Step 4: Measure the pressure difference DP between the upper and lower pressure ports in the reactor pressure vessel by using the differential pressure measuring element 5, and calculate the reference end pressure P0 according to the liquid phase density at the reference end and the liquid phase height H0 at the reference end; calculate the internal pressure difference P between the upper and lower ends of the pressure vessel 1 according to the reference end pressure P0 and the pressure difference DP 内 , see Fig. 9 ;

[0144] Step 5: Pressure difference P in the reactor pressure vessel 内 , average density of coolant liquid phase Average density of coolant vapor phase Calculate the initial measured coolant level height H and assign the H value to the variable to be corrected level H 待校正 , see Fig.10 ;

[0145] Step 6: Based on the variable H 待校正 Determine the measurement interval to which the coolant level belongs;

[0146] Step 7: According to the result of step 6, if it is in area A, call the liquid level correction module of area A, see Fig.11 ; If in area B, call the liquid level correction module in area B, see Fig.12; If in area C, call the C area liquid level correction module, see Fig.13 ;According to the calculation result of the liquid level correction module, the corrected liquid level height is obtained;

[0147] Step 8: According to the corrected liquid level height H 校正后 and the liquid level height H before calibration 待校正 Determine whether the measurement intervals of the two are consistent. If they are consistent, the calibration ends. If they are inconsistent, the variable liquid level height H to be calibrated 待校正 Update or replace with the current corrected liquid level height H 校正后 To obtain the latest liquid level to be corrected, repeat steps 6, 7, and 8 until the interval to which the liquid level belongs after iterative correction is consistent with the interval to which the liquid level belongs before correction. The liquid level correction is completed. For details, see Fig.14 .

[0148] See also Fig.15 The present invention provides a reactor pressure vessel liquid level measurement and correction device, comprising:

[0149] The acquisition module is configured to acquire first measurement data of the reactor pressure vessel, wherein the first measurement data at least includes pressure difference data between the upper and lower ends of the pressure vessel 1, temperature, pressure and interval height data of each measurement interval, and temperature, pressure and liquid phase height data of the balance tank 2;

[0150] The calculation and correction module receives the data transmitted by the acquisition module and is configured to calculate the initial measured liquid level height of the pressure vessel 1 according to the first measurement data and assign it to the variable to be corrected liquid level height H 待校正 The measurement interval of the liquid level to be corrected is not determined;

[0151] According to the liquid level height H to be corrected 待校正 The measurement interval and the first measurement data are to be corrected liquid level height H 待校正 Perform calibration to obtain the calibrated liquid level height;

[0152] According to the corrected liquid level height and the to-be-corrected liquid level height before correction, the measurement intervals in which the two are located are compared. When the measurement interval in which the corrected liquid level height is located and the measurement interval in which the to-be-corrected liquid level height before correction is located belong to different measurement intervals, the to-be-corrected liquid level height is updated or replaced with the current corrected liquid level height to obtain the latest to-be-corrected liquid level height, and the latest to-be-corrected liquid level height is continuously corrected to obtain the latest corrected liquid level height;

[0153] When the latest corrected liquid level height and the to-be-corrected liquid level height before correction are in the same measuring interval, the latest corrected liquid level height is taken as the accurate liquid level height of the coolant in the pressure vessel 1;

[0154] The information exchange module receives the data transmitted by the calculation and correction module, outputs the liquid level height of the pressure vessel, and provides the necessary human-machine interface.

[0155] It should be noted that in this case, the temperature measuring element 3 and the pressure measuring element 4 are respectively installed in several measuring areas divided longitudinally by the pressure vessel 1. The temperature measuring element 3 and the pressure measuring element 4 collect the temperature and pressure data of the coolant and the balance tank 2 in real time. The differential pressure measuring element 5 is used to measure the internal and external pressure difference between the upper and lower pressure ports of the pressure vessel 1. The acquisition module collects the first measurement data through the temperature measuring element 3, the pressure measuring element 4, and the differential pressure measuring element 5, and transmits the first measurement data to the calculation and correction module; the calculation and correction module is responsible for completing the iterative correction process of the liquid level. The information exchange module receives the data transmitted by the calculation module and outputs the liquid level height of the pressure vessel to the demander, such as the digital control system of a nuclear power plant. The information exchange module also provides the necessary human-machine interface.

[0156] Furthermore, the calculation and correction module includes an average pressure calculation module, an average temperature calculation module, a vapor phase and liquid phase density calculation module for each zone, a theoretical pressure difference calculation module for zone A, a theoretical pressure difference calculation module for zone B, a theoretical pressure difference calculation module for zone C, a reference end pressure calculation module, a pressure difference calculation module inside the pressure vessel, a measured liquid level height calculation module, a liquid level correction module for zone A, a liquid level correction module for zone B, and a liquid level correction module for zone C.

[0157] In conjunction with the instruction manual Figure 5 The average pressure calculation module can calculate the average pressure of the reference end, the average pressure of the pressure vessel, the average pressure of the A area, the average pressure of the B area, and the average pressure of the C area according to the redundant pressure measuring element of the reference end, the redundant pressure measuring element of the A area, the redundant pressure measuring element of the B area, and the redundant pressure measuring element of the C area;

[0158] The average temperature calculation module can calculate the average temperature of the reference end, the average temperature of the pressure vessel, the average temperature of the A zone, the average temperature of the B zone, and the average temperature of the C zone according to the redundant temperature measuring element of the reference end, the redundant temperature measuring element of the A zone, the redundant temperature measuring element of the B zone, and the redundant temperature measuring element of the C zone;

[0159] The vapor phase and liquid phase density calculation module of each zone can calculate the average density of the liquid phase of the pressure vessel, the average density of the vapor phase of the pressure vessel, the liquid phase density of the reference end, the average density of the liquid phase in zone A, the average density of the vapor phase in zone A, the average density of the liquid phase in zone B, the average density of the vapor phase in zone B, the average density of the liquid phase in zone C, and the average density of the vapor phase in zone C according to the average pressure of the reference end, the average pressure of the pressure vessel, the average pressure of zone A, the average pressure of zone B, the average pressure of zone C, the average temperature of the reference end, the average temperature of the pressure vessel, the average temperature of zone A, the average temperature of zone B, and the average temperature of zone C.

[0160] In conjunction with the instruction manual Figure 6-8 , the theoretical pressure difference in the single-phase state (vapor phase or liquid phase) of zones A, B, and C can be calculated respectively. The theoretical pressure difference calculation module of zone A can calculate the liquid phase pressure difference P in the single liquid phase state of zone A according to the liquid phase density of zone A, the vapor phase density of zone A, and the height HA of zone A. A液 The vapor pressure difference P under the single vapor phase state in area A A汽 The theoretical pressure difference calculation module of zone B can calculate the liquid phase pressure difference P under the single liquid phase state of zone B according to the liquid phase density of zone B, the vapor phase density of zone B, and the height HB of zone B. B液 The vapor pressure difference P under the single vapor phase state in area B B汽 The C zone theoretical pressure difference calculation module can calculate the liquid phase pressure difference P under the single liquid phase state of the C zone according to the liquid phase density of the C zone, the vapor phase density of the C zone, and the height HC of the C zone. C液 The vapor pressure difference P under the single vapor phase state in zone C C汽 .

[0161] In conjunction with the instruction manual Fig. 9 The reference end pressure calculation module can calculate the reference end pressure P0 according to the reference end liquid phase density and the reference end liquid phase height H0; the pressure difference calculation module in the pressure vessel can calculate the pressure difference P in the pressure vessel according to the reference end pressure P0 and the DP measured by the differential pressure measuring element. 内 .

[0162] In conjunction with the instruction manual Fig.10 The liquid level measurement module calculates the pressure difference P in the pressure vessel. 内 , the average density of the liquid phase of the pressure vessel, the average density of the vapor phase of the pressure vessel, HA, HB, HC calculate the initial measured liquid level height H, and assign it to the variable to be corrected liquid level height H 待校正 .

[0163] In conjunction with the instruction manual Fig.11 The liquid level correction module in zone A is based on the pressure difference P in the pressure vessel. 内 、Vapor pressure difference in zone B P B汽 、C zone vapor phase pressure difference P C汽 , the average density of the liquid phase in zone A, the average density of the vapor phase in zone A and HA can be used to calculate the corrected liquid level height (H 校正后 ).

[0164] In conjunction with the instruction manual Fig.12 The liquid level correction module in zone B is based on the pressure difference P in the pressure vessel. 内 、A zone liquid phase pressure difference P A液 、C zone vapor phase pressure difference P C汽 , the average density of the liquid phase in zone B, the average density of the vapor phase in zone B and HB can be used to calculate the corrected liquid level in zone B (H 校正后 ).

[0165] In conjunction with the instruction manual Fig.13 The liquid level correction module in zone C is based on the pressure difference P in the pressure vessel. 内 、A zone liquid phase pressure difference P A液 、Liquid pressure difference in zone B P B液 , the average density of the liquid phase in zone C, the average density of the vapor phase in zone C and HC can be used to calculate the corrected liquid level in zone C (H 校正后 ).

[0166] In summary, the present invention effectively overcomes some practical problems in the prior art and thus has high utilization value and use significance.

[0167] The above embodiments are merely illustrative of the principles and effects of the present invention, and are not intended to limit the present invention. Anyone familiar with the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by a person of ordinary skill in the art without departing from the spirit and technical concept disclosed by the present invention shall still be covered by the claims of the present invention.

Claims

1. A method for measuring and correcting the liquid level of a reactor pressure vessel, characterized in that: Applied to a reactor pressure vessel measurement system, the reactor pressure vessel measurement system at least comprises a balance tank, a pressure difference measuring element and a connecting pipeline, one end of the connecting pipeline connecting the balance tank and the pressure difference measuring element in series is used to communicate with the top of the pressure vessel, and the other end is used to communicate with the bottom of the pressure vessel, and the balance tank is arranged flush with the top of the pressure vessel; the method comprises the following steps: Divide the pressure vessel into a plurality of measurement intervals along the vertical height pressure difference direction; Acquire first measurement data of the pressure vessel, the first measurement data at least including pressure difference data between the upper and lower ends of the pressure vessel, temperature, pressure and interval height data of each measurement interval, and temperature, pressure and liquid phase height data of the balance tank; Calculate the initial measured liquid level height of the pressure vessel according to the first measurement data, and assign the initial measured liquid level height to the variable liquid level height to be corrected; Determine the measurement interval according to the height of the liquid level to be corrected, correct the height of the liquid level to be corrected according to the measurement interval and the first measurement data, and obtain the corrected liquid level; According to the corrected liquid level height and the to-be-corrected liquid level height before correction, the measurement intervals in which the two are located are compared. When the measurement interval in which the corrected liquid level height is located and the measurement interval in which the to-be-corrected liquid level height before correction is located belong to different measurement intervals, the to-be-corrected liquid level height is updated or replaced with the current corrected liquid level height to obtain the latest to-be-corrected liquid level height, and the latest to-be-corrected liquid level height is continuously corrected to obtain the latest corrected liquid level height; Until the latest corrected liquid level height and the latest to-be-corrected liquid level height are in the same measuring interval, the latest corrected liquid level height is taken as the accurate liquid level height of the coolant in the pressure vessel.

2. The reactor pressure vessel liquid level measurement and correction method according to claim 1, characterized in that: The step of calculating the initial measured liquid level height of the pressure vessel according to the first measurement data and assigning the initial measured liquid level height to the variable liquid level height to be corrected comprises: Calculate the internal pressure difference between the upper and lower ends of the pressure vessel based on the pressure difference data between the upper and lower ends of the pressure vessel and the liquid phase pressure, temperature, and liquid phase height data of the balance tank; Calculate the average density of the liquid phase and the average density of the vapor phase in the pressure vessel according to the temperature and pressure data of each measurement interval, and calculate the initial measurement liquid level height according to the average density of the liquid phase and the average density of the vapor phase of the coolant in the pressure vessel and the internal pressure difference between the upper and lower ends of the pressure vessel; The initial measured liquid level height is assigned to the variable liquid level height to be corrected, and the measurement interval in which the liquid level to be corrected is located is determined according to the liquid level height to be corrected and the interval height data of each measurement interval.

3. The reactor pressure vessel liquid level measurement and correction method according to claim 2, characterized in that: The step of calculating the internal pressure difference between the upper and lower ends of the pressure vessel according to the pressure difference data between the upper and lower ends of the pressure vessel and the pressure, temperature, and liquid phase height data of the balancing tank includes: calculating the liquid phase density of the balancing tank according to the pressure and temperature data of the balancing tank; Calculate the pressure difference data of the balance tank according to the liquid density and liquid height data of the balance tank; The internal pressure difference between the upper and lower ends of the pressure vessel is calculated based on the pressure difference data of the balance tank and the pressure difference data of the upper and lower ends of the pressure vessel.

4. The reactor pressure vessel liquid level measurement and correction method according to claim 1, characterized in that: The step of determining the measurement interval according to the height of the liquid level to be corrected, correcting the height of the liquid level to be corrected according to the measurement interval and the first measurement data, and obtaining the corrected liquid level comprises: Calculate the average density of the liquid phase and the average density of the vapor phase in each measuring interval according to the coolant pressure and temperature data in each measuring interval; According to the liquid phase density, vapor phase density and the height of the corresponding measuring interval in each measuring interval, the liquid phase pressure difference and vapor phase pressure difference in the single-phase state of each measuring interval are calculated; The corrected liquid level height of the liquid level to be corrected is calculated based on the internal pressure difference between the upper and lower ends of the pressure vessel, the average vapor phase density of the measuring interval where the liquid level height to be corrected is located, the average liquid phase density, the height of the measuring interval, the liquid phase pressure difference of all measuring intervals below the measuring interval, and the vapor phase pressure difference of all measuring intervals above the measuring interval.

5. The reactor pressure vessel liquid level measurement and correction method according to claim 4, characterized in that: The step of calculating the average liquid phase density and the average vapor phase density of each measuring interval according to the coolant pressure and temperature data of each measuring interval comprises: Determine the average coolant pressure and average coolant temperature in each measuring interval according to the coolant pressure or temperature data in each measuring interval; Calculate the average liquid phase volume and the average vapor phase volume of each measuring interval according to the average coolant pressure and average temperature of each measuring interval; The average density of the liquid phase and the average density of the vapor phase in each measuring interval are determined according to the average liquid phase volume and the average vapor phase volume in each measuring interval.

6. The reactor pressure vessel liquid level measurement and correction method according to claim 4, characterized in that: The step of calculating the corrected liquid level height of the liquid level to be corrected according to the internal pressure difference between the upper and lower ends of the pressure vessel, the average vapor phase density of the measurement interval where the liquid level height to be corrected is located, the average liquid phase density, the height of the measurement interval, the liquid phase pressure difference of all measurement intervals below the measurement interval, and the vapor phase pressure difference of all measurement intervals above the measurement interval comprises: According to the existence of vapor phase and liquid phase space in the measurement interval where the liquid level height to be corrected is located, the measurement intervals above the measurement interval where the liquid level height to be corrected is all vapor phase, the measurement intervals below the measurement interval where the liquid level height to be corrected is all liquid phase, and the average vapor phase density or the average liquid phase density of the remaining measurement intervals other than the measurement interval where the liquid level height to be corrected is located and the interval heights of the remaining measurement intervals, the zone pressure differences of the remaining measurement intervals are calculated; The zone pressure difference of the measuring interval where the liquid level to be corrected is located is calculated according to the difference between the zone pressure difference of the measuring interval where the liquid level to be corrected is located and the sum of the zone pressure differences of the other measuring intervals; The corrected liquid level height of the liquid level to be corrected is calculated based on the obtained partition pressure difference of the measurement interval where the liquid level height to be corrected is located, the liquid phase average density and the vapor phase average density of the measurement interval where the liquid level height to be corrected is located.

7. A reactor pressure vessel liquid level measurement and correction device, characterized in that: include: The acquisition module is configured to acquire first measurement data of the pressure vessel, wherein the first measurement data at least includes pressure difference data between the upper and lower ends of the pressure vessel, temperature, pressure and interval height data of each measurement interval, and temperature, pressure and liquid phase height data of the balance tank; A calculation and correction module receives the data transmitted by the acquisition module and is configured to calculate the initial measured liquid level height of the pressure vessel according to the first measurement data and assign it to the liquid level height to be corrected which is a variable, and determine the measurement interval in which the liquid level height to be corrected is located; Correcting the liquid level to be corrected according to the measurement interval in which the liquid level to be corrected is located and the first measurement data to obtain a corrected liquid level; According to the corrected liquid level height and the to-be-corrected liquid level height before correction, the measurement intervals in which the two are located are compared. When the measurement interval in which the corrected liquid level height is located and the measurement interval in which the to-be-corrected liquid level height before correction is located belong to different measurement intervals, the current corrected liquid level height is assigned to the to-be-corrected liquid level height as a variable to obtain an updated to-be-corrected liquid level height, and the latest to-be-corrected liquid level height is continuously corrected to obtain the latest corrected liquid level height; Until the latest corrected liquid level height and the to-be-corrected liquid level height before correction are in the same measuring interval, the latest corrected liquid level height is taken as the accurate liquid level height of the coolant in the pressure vessel; The information exchange module receives the data transmitted by the calculation and correction module, outputs the liquid level height of the pressure vessel, and provides the necessary human-machine interface.

8. A reactor pressure vessel measurement system, characterized in that: Basic measurement data for measuring pressure vessels, including: A balance tank is configured to be flush with the top of the pressure vessel, and one end of the balance tank is used to communicate with the top of the pressure vessel; Temperature measuring elements are arranged in each measuring interval divided by the vertical height pressure difference direction of the balance tank and the pressure vessel; The pressure measuring elements are arranged in each measuring interval divided by the vertical height pressure difference direction of the balance tank and the pressure vessel; The differential pressure measuring element is configured such that one end can be connected to the bottom of the pressure vessel and the other end is connected to the balance tank, and is used to measure the pressure difference between the upper and lower ends of the pressure vessel.

9. A reactor pressure vessel measuring device according to claim 8, characterized in that: The balancing tank and the differential pressure measuring element are arranged in series through a connecting pipeline, and one end of the balancing tank can be detachably connected to a top pressure taking port arranged at the top of the pressure vessel through a connecting pipeline; one end of the differential pressure measuring element can be detachably connected to a bottom pressure taking port arranged at the bottom of the pressure vessel through a connecting pipeline.

10. A reactor pressure vessel measuring device according to claim 8, characterized in that: At least two temperature measuring elements and pressure measuring elements are provided in each of the measuring intervals; Some of the temperature measuring elements are also arranged in the balancing tank and / or the connecting pipeline, and some of the pressure measuring elements are also arranged in the balancing tank and / or the connecting pipeline.

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