Online calibration system and method for conductivity meter of steam-water sampling system of power plant

Abstract

The invention relates to a conductivity meter online verification system and method for a steam-water sampling system of a power plant, and the system comprises a water inlet pipe, a sampling device, a common conductivity meter and a controller, and the water inlet pipe can be respectively communicated with the sampling device and the conductivity meter; the sampling device comprises a measuring cell, a temperature sensor, a current detection assembly and an online detection device, the measuring cell is connected with the water inlet pipe, the temperature sensor is used for measuring the temperature T of a water sample in the measuring cell, the current detection assembly is used for obtaining detection current I flowing through the water sample in the measuring cell, and the online detection device is used for detecting the conductivity sigma of the water sample in the measuring cell; the controller is used for obtaining the temperature T, the detection current I and the conductivity sigma and constructing a standard conductivity sigma standard database based on the temperature T, the detection current I and the conductivity sigma; and the controller is also used for obtaining the online conductivity sigma (online) and the online standard conductivity sigma (standard) measured by the common conductivity meter, and comparing the online conductivity sigma (online) and the online standard conductivity sigma (standard). According to the verification system and method, automatic operation is achieved, operation is stable, and the online conductivity meter can be verified effectively and timely.

Description

Technical Field

[0001] The invention relates to the technical field of conductivity meter calibration, and in particular to an online calibration system and method for a conductivity meter of a steam-water sampling system of a power plant. Background Art

[0002] Online chemical instruments are a key means of monitoring and controlling the water vapor chemistry in power plants. Accurate measurement of online chemical instruments is crucial to the safe operation of power plants and is a strong guarantee for preventing sudden damage accidents to thermal equipment. Inaccurate measurement of online chemical instruments will seriously affect the accurate judgment of chemical supervision and control, and the problem of excessive water vapor quality cannot be discovered in time. Long-term accumulation will lead to accidents such as corrosion, scaling, salt accumulation and pipe burst, which will bring huge risks and hazards to the safe and economical operation of the unit. Online chemical instruments include conductivity meters, silicon meters, sodium meters, dissolved oxygen meters, pH meters, phosphorus meters, etc. Among them, conductivity meters are the most common and most commonly used chemical test instruments. Conductivity meters are widely used in water vapor detection in thermal power plants. They have low maintenance workload, high reliability, and can effectively reflect changes in water vapor quality.

[0003] According to the requirements of power plants, the conductivity meter should be calibrated once a month. The calibration method is as follows: for conductivity meters with measured water sample conductivity values ​​not exceeding 0.3μS / cm, the water sample flow method should be used to check the working error of the whole machine. For conductivity meters with measured water sample conductivity values ​​exceeding 0.3μS / cm, the water sample flow test method should be used to check the working error of the whole machine. The static standard solution offline test method can also be used to check the reference error of the whole machine. However, these calibration methods are too cumbersome and require multiple manual sampling tests. Most power plant operators do not calibrate the conductivity meter during the actual maintenance process, and cannot timely grasp the operating status of the conductivity meter and cannot perform timely maintenance.

[0004] Therefore, it is necessary to design a system and method with simple structural design, stable operation, strong practicality, and the ability to effectively and timely calibrate an online conductivity meter. Summary of the invention

[0005] The present invention provides an online calibration system and method for a conductivity meter of a steam-water sampling system of a power plant. The system is automatically and stably operated, and can effectively and timely calibrate the online conductivity meter without the need for manual monitoring, thereby improving the accuracy of the test results and the accuracy of the steam quality supervision of the steam-water sampling system.

[0006] To achieve the above object, the present invention adopts the following technical solutions:

[0007] An online calibration system for a conductivity meter of a steam-water sampling system of a power plant, comprising a water inlet pipe, a sampling device, a common conductivity meter and a controller, wherein the water inlet pipe can be connected to the sampling device and the conductivity meter respectively, and the controller is connected to the sampling device and the conductivity meter for communication respectively;

[0008] The sampling device comprises a measuring pool, a temperature sensor, a current detection component and an online inspection device. The measuring pool is connected to the water inlet pipe and is used to obtain a water sample. The temperature sensor is used to measure the temperature T of the water sample in the measuring pool. The current detection component is used to obtain a detection current I flowing through the water sample in the measuring pool. The online detection device is used to detect the conductivity σ of the water sample in the measuring pool.

[0009] The controller is used to obtain the temperature T, the detection current I and the conductivity σ and to construct a standard conductivity σ based on the temperature T, the detection current I and the conductivity σ. 标准 database;

[0010] The controller is also used to obtain the online conductivity σ measured by the common conductivity meter 在线 , and at the same time obtain the above temperature T and the above detection current I of the water sample in the current measuring pool to determine the online standard conductivity σ 标准 , and then determine the online conductivity σ 在线 and online standard conductivity σ 标准 Whether the error is within the set threshold, if not, a maintenance reminder is issued.

[0011] Preferably, it also includes a three-way valve, and the sampling device also includes a sampling tube. The three-way valve is connected to the water inlet pipe, the sampling tube and the inlet of the common conductivity meter respectively, and can control the connection and disconnection of the water inlet pipe, the sampling tube and the inlet of the common conductivity meter.

[0012] Preferably, the sampling device further comprises a water outlet pipe, the water outlet pipe is connected to the measuring pool and the online inspection device, the online inspection device is a standard conductivity meter, and the controller is used to obtain the standard conductivity σ of the water sample in the measuring pool through the standard conductivity meter within a set time. 标准 , and simultaneously obtain the temperature T and the detection current I of the water sample in the measurement pool, based on the standard conductivity σ 标准 , the above temperature T, the above detection current I to construct the standard conductivity σ 标准 database.

[0013] Preferably, during the set time, the online inspection device is a common conductivity meter, the water outlet pipe is connected to the common conductivity meter, and the set time is the initial use period of the common conductivity meter.

[0014] Preferably, the current detection component comprises two pole plates arranged opposite to each other in the measuring cell, a constant voltage AC power source connected to the two pole plates, and an ammeter.

[0015] An online calibration method for the conductivity meter of a steam-water sampling system in a power plant, using the above system, comprises the following steps:

[0016] Steps for building a database: the water inlet pipe is connected to the sampling device, the water sample flows into the measuring pool, the temperature sensor measures the temperature T of the water sample in the measuring pool, the current detection component obtains the detection current I flowing through the water sample in the measuring pool, the online detection device detects the conductivity σ of the water sample in the measuring pool, and the standard conductivity σ of the corresponding water sample 标准 Based on several different sets of temperature T, detection current I and conductivity σ, a standard conductivity σ is constructed 标准 database;

[0017] Online calibration steps: The water inlet pipe is connected to the sampling device and the common conductivity meter respectively to obtain the online conductivity σ measured by the common conductivity meter 在线 , and at the same time obtain the above temperature T and the above detection current I of the water sample in the current measuring pool to determine the online standard conductivity σ 标准 , and then determine the online conductivity σ 在线 and online standard conductivity σ 标准 Whether the error is within the set threshold, if not, a maintenance reminder is issued.

[0018] Preferably, in the above step of building a database, the relationship between conductivity σ, temperature T, and detection current I is as follows:

[0019]

[0020] σ t is the standard conductivity of the water sample in the measuring pool σ 标准 , unit is S·cm -1 ,

[0021] K is the electrode constant of the electrode plate, cm -1 ,

[0022] I0 is the detection current I when the temperature T of the water sample in the measuring pool is t0,

[0023] U is the voltage of the constant voltage AC power supply, in V.

[0024] β is the conductivity temperature coefficient of the water sample in the measuring pool,

[0025] t, t0 are the temperatures of the water sample in the measuring pool, where t is 25°C and t0 is the real-time temperature T.

[0026] Preferably, the database construction step is completed within a set time, which is the initial use period of the common conductivity meter, which is 1-2 weeks. The conductivity σ of the water sample in the measuring pool is measured by the common conductivity meter, and the standard conductivity σ of the corresponding water sample is measured by the common conductivity meter. 标准 ;

[0027] The above-mentioned online verification step is performed after the above-mentioned set time.

[0028] Preferably, in the above-mentioned online verification step, after the first maintenance reminder, the commonly used conductivity meter is maintained, and then the commonly used conductivity meter is connected to the water inlet pipe again, and the above-mentioned online verification step is repeated;

[0029] If the error is within the set threshold, the maintenance is judged to be successful; if the error is not within the set threshold, the maintenance is judged to be unsuccessful, and the common conductivity meter is maintained again or replaced with a new conductivity meter.

[0030] Preferably, in the above online verification step, the error calculation formula is as follows:

[0031]

[0032] The threshold is set to -10<δ<10.

[0033] Compared with the prior art, the present invention has the following beneficial effects:

[0034] The calibration method is based on the online calibration system. First, the standard conductivity σ is measured through the measuring cell, temperature sensor, current detection component, online inspection device and controller. 标准 The construction of the database is done before the calibration. Then, the online standard conductivity σ is obtained by using the measuring cell, temperature sensor, current detection component, common conductivity meter and controller together. 标准 and online conductivity σ 在线 , compare the two online, and perform more accurate and automated online calibration, which can effectively and timely calibrate the online conductivity meter. It does not require manual monitoring, which improves the accuracy of the test results and the accuracy of water vapor quality supervision in the soda sampling system. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0036] Figure 1 A schematic diagram of the database construction phase in the verification system of an embodiment of the present invention;

[0037] Figure 2 It is a schematic diagram of the online verification stage in the verification system of an embodiment of the present invention;

[0038] Figure 3 A schematic diagram of a measuring cell in an embodiment of the present invention;

[0039] Figure 4 It is a data table between standard conductivity σ, temperature T and conductivity temperature coefficient β in the component database stage of the embodiment of the present invention.

[0040] Description of reference numerals:

[0041] 1. Water sample tube; 2. Common conductivity meter; 3. Measuring cell; 4. Temperature sensor; 5. Constant voltage AC power supply; 6. Ammeter; 7. Plate; 8. Online calibration device; 9. Three-way valve; 10. Sampling tube; 11. Water outlet pipe. DETAILED DESCRIPTION

[0042] The technical solution of the present invention will be described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0043] In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

[0044] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0045] like Figure 1-3As shown, an online calibration system for a conductivity meter of a steam-water sampling system of a power plant, specifically includes a water inlet pipe, a sampling device, a common conductivity meter 2 and a controller, wherein the water inlet pipe can be connected to the sampling device and the conductivity meter respectively, and is used to send water samples to the sampling device and the conductivity meter, and the controller is respectively connected to the sampling device and the conductivity meter for communication, and is used to obtain some data of the water samples measured by the sampling device and the conductivity meter; specifically, the sampling device includes a measuring cell 3, a temperature sensor 4, a current detection component and an online inspection device, wherein the measuring cell 3 is connected to the water inlet pipe, and is used to continuously obtain water samples, wherein the measuring end of the temperature sensor 4 is placed in the water sample in the measuring cell 3, and is used to measure the temperature T of the water sample in the measuring cell 3, wherein the current detection component is used to obtain the detection current I flowing through the water sample in the measuring cell 3, and the online inspection device is used to detect the conductivity σ of the water sample in the measuring cell 3; specifically, the controller is used to obtain the temperature T, the detection current I and the conductivity measured by the above-mentioned online detection device, and construct a standard conductivity σ based on the above-mentioned parameters 标准 Database; at the same time, the controller is also used to obtain the online conductivity σ measured by the commonly used conductivity table 2 在线 At the same time, the temperature T of the water sample in the current measuring pool 3 and the detection current I are obtained through the standard conductivity σ 标准 Database determines the online standard conductivity σ 标准 , and then determine the online conductivity σ 在线 and online standard conductivity σ 标准 Whether the error between them is within the set threshold, if not, a maintenance reminder is issued to remind the maintenance personnel to perform maintenance. In summary, the standard conductivity σ is first measured by the measuring cell 3, the temperature sensor 4, the current detection component, the online inspection device and the controller. 标准 The database is constructed, and then the online conductivity σ is obtained through the common conductivity table 2 by using the measuring cell 3, the temperature sensor 4, the current detection component, the common conductivity table 2 and the controller. 在线 The controller uses the temperature T and the detection current I to obtain the standard conductivity σ 标准 Database to obtain online standard conductivity σ 标准 , compare the two, so as to achieve more accurate and automated online calibration, which can effectively and timely calibrate the online conductivity meter, and improve the accuracy of the test results without manual monitoring, and improve the accuracy of water vapor quality supervision in the soda sampling system.

[0046] Among them, the measuring cell 3 used above is the same size as the measuring cell 3 used inside the commonly used conductivity meter 2, thereby ensuring that the real-time temperature T and current I of the water sample measured in the measuring cell 3 are the same as the temperature T and current I of the water sample passing through the measuring cell 3 in the commonly used conductivity meter 2, thereby realizing that the sampling device indirectly measures the temperature and current of the water sample passing through the commonly used conductivity meter 2.

[0047] Specifically, the system also includes a three-way valve 9, and the sampling device also includes a sampling tube 10. The three-way valve 9 is respectively connected to the water inlet pipe, the sampling tube 10 and the inlet of the commonly used conductivity meter 2, and can control the connection and disconnection of the water inlet pipe and the sampling tube 10 and the inlet of the commonly used conductivity meter 2, thereby making it more convenient to connect and control the water sample pipelines.

[0048] Specifically, the sampling device also includes a water outlet pipe 11, which is connected to the measuring pool 3 and the online inspection device. The online inspection device is a standard conductivity meter, so that the water in the measuring pool 3 flows into the standard conductivity meter through the water outlet pipe 11, thereby realizing the conductivity value measurement of the water sample; correspondingly, the controller obtains the standard conductivity σ of the water sample in the measuring pool 3 through the standard conductivity meter. 标准 , and simultaneously obtain the temperature T and detection current I of the water sample in the measuring pool 3, based on the standard conductivity σ 标准 , temperature T, detection current I to construct standard conductivity σ 标准 Database, in the verification stage, the controller can be based on the actual temperature T, detection current I through the standard conductivity σ 标准 Database to determine online standard conductivity σ 标准 Specifically, the controller performs standard conductivity σ 标准 The construction of the database should be done before the online calibration of the commonly used conductivity table 2. In actual operation, it usually takes about two weeks to build the standard conductivity σ through the measurement cell 3, temperature sensor 4, current detection component, online inspection device and controller. 标准 Database, to ensure the comprehensiveness of database construction data.

[0049] Among them, in this embodiment, the standard conductivity meter is also the commonly used conductivity meter 2. The time period during which the controller builds the database is also the initial input time of the commonly used conductivity meter 2, thereby ensuring that the measured value of the standard conductivity meter is accurate. Preferably, after the commonly used conductivity meter 2 completes the database construction, the outlet pipe 11 is no longer connected to the online inspection device (common conductivity meter 2), but the conductivity meter is put into use, and then the measurement cell 3, the temperature sensor 4, the current detection component, the commonly used conductivity meter 2 and the controller are used together for verification, so as to achieve dual-purpose of one meter. In another embodiment, the standard conductivity meter can be other new conductivity meters, and the commonly used conductivity meter 2 can only be used as a commonly used conductivity meter detected online because it has been used for a period of time, and the new conductivity meter is only used during the construction of the database.

[0050] Specifically, the current detection component includes two electrodes 7 relatively arranged in the measuring pool 3, a constant voltage AC power supply 5 and an ammeter 6 connected to the two electrodes 7, and the current measurement of the water sample is realized through the cooperation of the constant voltage AC power supply 5, the ammeter 6 and the electrodes 7, wherein the ammeter 6 is connected to the controller, and the controller can directly obtain the reading of the ammeter 6.

[0051] The present invention also discloses an online calibration method for a conductivity meter of a steam-water sampling system of a power plant, which is implemented by using the above-mentioned conductivity meter system of the steam-water sampling system of the power plant, and comprises the following steps:

[0052] First, the database is constructed: the water inlet pipe is connected to the sampling device, that is, the water sample in the water inlet pipe flows into the measuring pool 3 through the sampling pipe 10, the temperature sensor 4 measures the temperature T of the water sample in the measuring pool 3, the current detection component obtains the detection current I flowing through the water sample in the measuring pool 3, and the online detection device detects the conductivity σ of the water sample in the measuring pool 3 标准 , corresponding to the standard conductivity σ of the water sample 标准 Then, through the above measurement steps, several sets of temperature T, detection current I and conductivity σ are obtained, and then based on several different data sets, a standard conductivity σ is constructed. 标准 database;

[0053] Online calibration steps: The water inlet pipe is connected to the measuring cell 3 in the sampling device and the measuring cell 3 in the common conductivity meter 2 respectively, and the online conductivity σ measured by the common conductivity meter 2 is obtained. 在线 At the same time, the real-time temperature T and detection current I of the water sample in the measuring pool 3 in the current sampling device are obtained. According to the above data and the standard conductivity σ 标准 Database query to determine the online standard conductivity σ 标准 , and then compare the online conductivity σ 在线 and online standard conductivity σ 标准 , determine the online conductivity σ 在线 and standard conductivity σ 标准 Whether the error is within the set threshold. Specifically, if the error value is within the set threshold, the commonly used conductivity meter 2 continues to be used. If the error is not within the set threshold, the maintenance personnel are prompted that the commonly used conductivity meter 2 needs maintenance. The specific maintenance method needs to be carried out according to the maintenance requirements of the power plant.

[0054] The above calibration method based on the calibration system can be automatically and stably operated, and can effectively and timely calibrate the online conductivity meter, without the need for manual monitoring and manual measurement of temperature T, current I and conductivity value σ, etc., which improves the accuracy of the test results and the accuracy of the water vapor quality supervision of the steam sampling system.

[0055] Specifically, in the step of building a database, the relationship between conductivity, temperature t, and detection current I is as follows:

[0056]

[0057] σ t is the standard conductivity of the water sample in the measuring pool σ 标准 , unit is S·cm-1 ,

[0058] K is the electrode constant of the electrode plate, cm -1 ,

[0059] I0 is the detection current I when the temperature T of the water sample in the measuring pool is t0,

[0060] U is the voltage of the constant voltage AC power supply, in V.

[0061] β is the conductivity temperature coefficient of the water sample in the measuring pool,

[0062] t, t0 are the temperatures of the water sample in the measuring pool, where t is 25°C and t0 is the real-time temperature T.

[0063] Specifically, since impurities may be attached to the electrode plate 7 in the conductivity meter during use, the water sample has the same temperature T at different time periods, but the water sample current I measured by the current detection component is different, resulting in the temperature T and the current I not being one-to-one corresponding. The standard conductivity value initially measured must also be corresponding, so the above formula is needed to calculate the standard conductivity value σ 标准 , and the above formula has different algorithms at different stages. Specifically, since the conductivity temperature coefficient β in the formula only changes with temperature T and is not related to current I, even if the impurities on the substrate surface change, as long as the temperature T remains the same, the conductivity temperature coefficient β remains the same. Therefore, in the database construction stage, the conductivity temperature coefficient β needs to be calculated, where σ t (Standard conductivity σ 标准 ) is measured by the online monitoring device, t0 is detected by the temperature sensor 4, t is 25°C, U is the voltage of the constant voltage AC power supply 5, I0 is read by the ammeter 6, K is the constant of the electrode plate 7, and only β is unknown in the formula. Through a set of temperature T, current I and conductivity value σ, a set of β values ​​can be obtained. Through several sets of data, several sets of β values ​​are obtained. The controller actually constructs an associated database of temperature T, current I and conductivity temperature coefficient β, such as Figure 4 Specifically, in the online verification stage, by obtaining the real-time temperature T and current I, the controller will look up the conductivity temperature coefficient β corresponding to the temperature T, and then substitute each value into the above formula to calculate the conductivity value, which is the online standard conductivity σ 标准 Then compare the online standard conductivity σ 标准 and online conductivity σ 在线 That's it.

[0064] Specifically, the database construction step is completed within a set time, and the set time is the initial use period of the common conductivity meter 2, which is 1-2 weeks. The conductivity of the water sample in the measuring pool 3 is measured by the common conductivity meter 2, and the standard conductivity σ of the corresponding water sample is标准 , this commonly used conductivity table 2 is a new table, and the online verification step is after the set time, that is, after the database is built.

[0065] Specifically, after the first maintenance reminder, the commonly used conductivity meter 2 is maintained, and then the commonly used conductivity meter 2 is connected to the water inlet pipe again, and the online verification steps are repeated;

[0066] If the error is within the set threshold, the maintenance is judged to be successful; if the error is not within the set threshold, the maintenance is judged to be unsuccessful, and the common conductivity meter 2 can be maintained again or replaced with a new conductivity meter, which is determined by the maintainer.

[0067] Specifically, in the online verification step, the error calculation formula is as follows:

[0068]

[0069] Specifically, the threshold is set to -10<δ<10, that is, after calculation, if the error value is within the set threshold, that is, -10<δ<10, the error is within the qualified rate requirement range, and the commonly used conductivity meter 2 continues to be used; if the error is not within the set threshold, that is, not within the qualified rate requirement range, the maintenance personnel is prompted that the commonly used conductivity meter 2 needs maintenance.

[0070] The above-mentioned embodiments are only preferred embodiments of the present invention and cannot be used to limit the scope of protection of the present invention. Any non-substantial changes and substitutions made by technicians in this field on the basis of the present invention shall fall within the scope of protection required by the present invention.

Claims

1. An online calibration system for conductivity meters of steam-water sampling systems in power plants, characterized in that: It includes a water inlet pipe, a sampling device, a common conductivity meter and a controller, wherein the water inlet pipe can be connected to the sampling device and the conductivity meter respectively, and the controller is connected to the sampling device and the conductivity meter respectively; The sampling device includes a measuring pool, a temperature sensor, a current detection component and an online inspection device. The measuring pool is connected to the water inlet pipe and is used to obtain a water sample. The temperature sensor is used to measure the temperature T of the water sample in the measuring pool. The current detection component is used to obtain a detection current I flowing through the water sample in the measuring pool. The online detection device is used to detect the conductivity σ of the water sample in the measuring pool. The controller is used to obtain the temperature T, the detection current I and the conductivity σ and construct a standard conductivity σ based on the temperature T, the detection current I and the conductivity σ 标准 database; The controller is also used to obtain the online conductivity σ measured by the common conductivity meter 在线 , and simultaneously obtain the temperature T and the detection current I of the water sample in the current measurement pool to determine the online standard conductivity σ 标准 , and then determine the online conductivity σ 在线 and online standard conductivity σ 标准 Whether the error is within the set threshold, if not, a maintenance reminder is issued.

2. The system according to claim 1, characterized in that It also includes a three-way valve, and the sampling device also includes a sampling tube. The three-way valve is connected to the water inlet pipe, the sampling tube and the inlet of the common conductivity meter respectively, and can control the connection and disconnection of the water inlet pipe, the sampling tube and the inlet of the common conductivity meter.

3. The system according to claim 1, characterized in that The sampling device also includes a water outlet pipe, which connects the measuring pool and the online inspection device, and the online inspection device is a standard conductivity meter. The controller is used to obtain the standard conductivity σ of the water sample in the measuring pool through the standard conductivity meter within a set time. 标准 , and simultaneously obtain the temperature T and the detection current I of the water sample in the measuring pool, based on the standard conductivity σ 标准 , the temperature T, the detection current I to construct the standard conductivity σ 标准 database.

4. The system according to claim 3, characterized in that During the set time, the online inspection device is a common conductivity meter, the water outlet pipe is connected to the common conductivity meter, and the set time is the initial use period of the common conductivity meter.

5. The system according to claim 1, wherein: The current detection component comprises two pole plates arranged opposite to each other in the measuring cell, a constant voltage AC power source connected to the two pole plates, and an ammeter.

6. An online calibration method for the conductivity meter of a steam-water sampling system in a power plant, characterized in that: The system according to any one of claims 1 to 5 comprises the following steps: Steps for building a database: the water inlet pipe is connected to the sampling device, the water sample flows into the measuring pool, the temperature sensor measures the temperature T of the water sample in the measuring pool, the current detection component obtains the detection current I flowing through the water sample in the measuring pool, and the online detection device detects the conductivity σ of the water sample in the measuring pool, corresponding to the standard conductivity σ of the water sample 标准 Based on several different sets of temperature T, detection current I and conductivity σ, a standard conductivity σ is constructed 标准 database; Online calibration step: the water inlet pipe is connected to the sampling device and the common conductivity meter respectively, and the online conductivity σ measured by the common conductivity meter is obtained. 在线 , and simultaneously obtain the temperature T and the detection current I of the water sample in the current measurement pool to determine the online standard conductivity σ 标准 , and then determine the online conductivity σ 在线 and online standard conductivity σ 标准 Whether the error is within the set threshold, if not, a maintenance reminder is issued.

7. The method according to claim 6, characterized in that In the step of constructing the database, the relationship between conductivity σ, temperature T, and detection current I is as follows: σ t is the standard conductivity of the water sample in the measuring pool σ 标准 , unit is S·cm -1 , K is the electrode constant of the electrode plate, cm -1 , I0 is the detection current I when the temperature T of the water sample in the measuring pool is t0, U is the voltage of the constant voltage AC power supply, in V. β is the conductivity temperature coefficient of the water sample in the measuring pool, t, t0 are the temperatures of the water sample in the measuring pool, where t is 25°C and t0 is the real-time temperature T.

8. The method according to claim 6, characterized in that The database construction step is completed within a set time, which is the initial use period of the common conductivity meter, which is 1-2 weeks. The conductivity σ of the water sample in the measuring pool is measured by the common conductivity meter, and the standard conductivity σ of the corresponding water sample is measured. 标准 ; The online verification step is performed after the set time.

9. The method according to claim 6, characterized in that In the online verification step, after the first maintenance reminder, the common conductivity meter is maintained, and then the common conductivity meter is connected to the water inlet pipe again, and the online verification step is repeated; If the error is within the set threshold, the maintenance is judged to be successful; if the error is not within the set threshold, the maintenance is judged to be unsuccessful, and the common conductivity meter is maintained again or replaced with a new conductivity meter.

10. The method according to claim 6, characterized in that In the online verification step, the error calculation formula is as follows: The threshold is set to -10<δ<10.

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