阅读说明：本技术 换热水箱液位测量系统及方法、核电厂pcs系统 (Heat exchange water tank liquid level measurement system and method and nuclear power plant PCS system ) 是由 于蕾 吴萍 李俭秋 郭林 于 2021-06-30 设计创作，主要内容包括：本发明提供一种换热水箱液位测量系统及方法、核电厂PCS系统,液位测量系统的第一压力检测仪表设于换热水箱底部的出水管道上,用于检测换热水箱底部的水压,液位测量系统的第二压力检测仪表设于换热水箱顶部的人孔通道上,用于检测换热水箱顶部的水压,液位测量系统的DCS系统用于计算压力差,且根据其内存储的液位和压力差的逻辑公式,计算得出换热水箱内的液位,从而避免了长距离毛细管传输带来的仪表精度差的问题,且安装的风险和维修检测的难度大大降低。(The invention provides a heat exchange water tank liquid level measuring system and method and a nuclear power plant PCS system, wherein a first pressure detecting instrument of the liquid level measuring system is arranged on a water outlet pipeline at the bottom of a heat exchange water tank and is used for detecting the water pressure at the bottom of the heat exchange water tank, a second pressure detecting instrument of the liquid level measuring system is arranged on a manhole channel at the top of the heat exchange water tank and is used for detecting the water pressure at the top of the heat exchange water tank, a DCS system of the liquid level measuring system is used for calculating pressure difference, and the liquid level in the heat exchange water tank is calculated according to a logic formula of the liquid level and the pressure difference stored in the DCS system, so that the problem of poor instrument precision caused by long-distance capillary tube transmission is solved, and the installation risk and the difficulty of maintenance and detection are greatly reduced.)

1. A heat exchange water tank liquid level measurement system, characterized by includes: the system comprises a first pressure detection instrument, a first transmitter, a second pressure detection instrument, a second transmitter and a DCS (distributed control system) (1);

the first pressure detection instrument is arranged on a water outlet pipeline (5) at the bottom of the heat exchange water tank (8), is electrically connected with the first transmitter and is used for detecting the water pressure at the bottom of the heat exchange water tank (8) and transmitting a detected first pressure signal to the first transmitter, the first transmitter is used for converting the first pressure signal into a first current signal,

the second pressure detection instrument is arranged on a manhole channel (7) at the top of the heat exchange water tank (8), is electrically connected with the second transmitter, is used for detecting the water pressure at the top of the heat exchange water tank (8) and transmitting a detected second pressure signal to the second transmitter, the second transmitter is used for converting the second pressure signal into a second current signal,

the DCS system (1) is electrically connected with the first transmitter and the second transmitter and used for collecting the first current signal and the second current signal, converting the first current signal and the second current signal into digital signals and then calculating to obtain pressure difference, and calculating to obtain the liquid level in the heat exchange water tank (8) according to the liquid level stored in the DCS system and a logic formula of the pressure difference.

2. The system for measuring the liquid level of the heat exchange water tank as claimed in claim 1, wherein the logic formula of the liquid level and the pressure difference is as follows:

wherein:

delta P is the pressure difference between the bottom and the top of the liquid level in the heat exchange water tank (8);

rho is the density of the medium in the heat exchange water tank (8), and g is the gravity acceleration.

3. The heat exchange water tank level measurement system according to claim 1 or 2, characterized in that the first pressure detection gauge and the first transmitter are integrated to form a first integrated absolute pressure transmitter (2).

4. The system for measuring the liquid level of the heat exchange water tank is characterized in that the first integrated absolute pressure transmitter (2) is arranged on a first pressure sampling pipe (4), and the first pressure sampling pipe (4) is communicated with a water outlet pipeline (5) at the bottom of the heat exchange water tank through a nozzle of the first pressure sampling pipe (4).

5. The heat exchange water tank level measurement system according to claim 1 or 2, characterized in that said second pressure detection gauge and second transmitter are integrated to form a second integrated absolute pressure transmitter (3).

6. The heat exchange water tank liquid level measurement system according to claim 5, wherein the second integrated absolute pressure transmitter (3) is arranged on a second pressure tapping pipe (6), and the second pressure tapping pipe (6) is communicated with a manhole channel (7) at the top of the heat exchange water tank through a nozzle of the second pressure tapping pipe (6).

7. A nuclear power plant PCS system comprising a heat exchange tank (8) and a heat exchange tank level measurement system according to any of claims 1-6.

8. A method for heat exchange tank level measurement using the system of any one of claims 1-6, comprising the steps of:

the first pressure detection instrument detects the water pressure at the bottom of the heat exchange water tank and transmits a detected first pressure signal to the first transmitter, the first transmitter converts the first pressure signal into a first current signal,

the second pressure detecting instrument detects the water pressure at the top of the heat exchange water tank and transmits a detected second pressure signal to the second transmitter, the second transmitter converts the second pressure signal into a second current signal,

the DCS system (1) collects the first current signal and the second current signal, converts the first current signal and the second current signal into digital signals, calculates the digital signals to obtain pressure difference, and calculates the liquid level in the heat exchange water tank according to a logic formula of the liquid level and the pressure difference stored in the DCS system.

9. The method for measuring the liquid level of the heat exchange water tank as claimed in claim 8, further comprising the following steps:

and when the calculated liquid level in the heat exchange water tank is lower than a set threshold value, the DCS (1) prompts a low threshold value to alarm.

10. The method for measuring the liquid level of the heat exchange water tank as claimed in claim 8 or 9, wherein the logic formula of the liquid level and the pressure difference is as follows:

wherein:

delta P is the pressure difference between the bottom and the top of the liquid level in the heat exchange water tank;

rho is the density of the medium in the heat exchange water tank, and g is the gravity acceleration.

Technical Field

The invention particularly relates to a heat exchange water tank liquid level measuring system and method and a nuclear power plant PCS system.

Background

A passive containment heat removal system (PCS system) of a nuclear power plant is used for long term heat removal of containment of the nuclear power plant under over-design baseline accident conditions, including accidents related to a plant blackout, spray system failure. When an over-design basis accident (including a serious accident) occurs in the power station, the pressure and the temperature of the containment vessel are reduced to acceptable levels, and the integrity of the containment vessel is maintained.

The heat exchange water tank in the PCS system is a heat trap for secondary side passive waste heat removal and containment heat, is arranged outside a containment, is of a concrete structure, is lined with a steel liner, is designed together with a containment factory building and is located at the elevation of 50.6-55.6 meters. Because the water capacity of the heat exchange water tank can meet the cooling requirements of reactor core waste heat discharge and containment vessel redundant heat conduction 72 hours after an accident, a certain liquid level monitoring means is needed to be adopted to accurately monitor the liquid level of the water tank in real time, and accurate monitoring and timely alarming are carried out when the liquid level is reduced and the water tank is leaked due to various reasons (such as steel lining damage, connected pipeline leakage and the like), so that the water capacity of the heat exchange water tank is ensured, and the correct realization of the function of a PCS system is further ensured.

In conclusion, it is of great significance to accurately and timely monitor and alarm the liquid level of the heat exchange water tank.

The heat exchange water tank of the PCS system is of a closed structure and can be regarded as an independent room hung outside the containment and is communicated with the atmosphere through a manhole channel at the top, a U-shaped pipe for water sealing and an exhaust pipeline above an outlet of the U-shaped pipe. The water tank is steel lining structure to the top skin is provided with the waterproof layer, should not be at the top trompil. In addition, there is pressure at the liquid level upper portion in the water tank, and be used for normal and super design benchmark accident (including serious accident) operating mode, the instrument has the antidetonation requirement.

For the above reasons, the tank level is generally measured by using a remote differential pressure transmitter with a double-ended capillary tube, as shown in fig. 1. Differential pressure transmitter 100 is installed on the top of heat exchange water tank 8, and is connected to the bottom and top of heat exchange water tank 8 through a capillary tube and an isolation container. In order to avoid increasing the top opening of the heat exchange water tank 8 and prevent the capillary tube from penetrating into the manhole channel, the double-ended capillary tube needs to enter the inside of the heat exchange water tank 8 along the existing U-shaped pipe 200 and the exhaust pipe 300 above the outlet of the U-shaped pipe. The differential pressure transmitter 100 transmits the current level value (corresponding to the 4-20mA current signal) to a distributed control system (DCS system 1) for collection and transmits the current level value to a main control room for display. When the monitored liquid level drops to a certain height, an alarm can be triggered through the calculation of a low threshold value in the DCS 1, and the operator of the power plant is reminded to check and carry out corresponding treatment.

According to the measuring principle and the configuration mode of the instrument, in order to not affect the space of a corridor platform at the top of the water tank, the instrument needs to be installed at the position of the parapet wall 400 which is 5m away from the outlet of the U-shaped pipeline 200, and the height of the water tank is considered to be 5m, so that the length of the capillary is preferably selected to be 15 m. Because the remote transmission distance is long, the precision of the instrument is about 7 percent, the precision is poor, and the measurement and the timely alarm are very unfavorable. In addition, the laying path of the used capillary is long, the capillary needs to move along the U-shaped pipeline 200, the capillary is easy to damage due to dragging, traction and the like in the installation process, and the follow-up overhauling and replacement of the capillary and the isolation container are difficult.

The reasons are not beneficial to monitoring the liquid level of the water tank and determining the alarm water level, and affect timely monitoring and alarming of leakage of the water tank. If the monitoring or the alarming is not timely or even fails, the water content of the heat exchange water tank can not meet the use requirement in serious conditions, even a certain heat exchange water tank is lost, and the heat extraction function of a related system cannot be finished.

On the general civil engineering project, the liquid level monitoring of the large water tank can be realized in the mode, and the reasons are that the requirements on monitoring and alarming accuracy are not high, and the effect of the water tank does not need to deal with the occurrence of over-design benchmark accidents. However, for a PCS system of a third-generation nuclear power plant, the PCS system is an important passive accident mitigation system, a heat exchange water tank is a main device of the PCS system, and the PCS system is of great importance in function, so that a timely, reliable and high-precision water tank liquid level measuring device needs to be designed to meet monitoring requirements.

Disclosure of Invention

The invention aims to solve the technical problem of providing a heat exchange water tank liquid level measuring system for improving the detection precision aiming at the defects in the prior art, and correspondingly providing a nuclear power plant PCS system with the liquid level measuring system and a method for measuring the liquid level of the heat exchange water tank by using the system.

The technical scheme adopted for solving the technical problem of the invention is as follows:

the invention provides a liquid level measuring system of a heat exchange water tank, which comprises: the system comprises a first pressure detection instrument, a first transmitter, a second pressure detection instrument, a second transmitter and a DCS (distributed control System);

the first pressure detection instrument is arranged on a water outlet pipeline at the bottom of the heat exchange water tank, is electrically connected with the first transmitter and is used for detecting the water pressure at the bottom of the heat exchange water tank and transmitting a detected first pressure signal to the first transmitter, the first transmitter is used for converting the first pressure signal into a first current signal,

the second pressure detection instrument is arranged on a manhole channel at the top of the heat exchange water tank, is electrically connected with the second transmitter and is used for detecting the water pressure at the top of the heat exchange water tank and transmitting a detected second pressure signal to the second transmitter, the second transmitter is used for converting the second pressure signal into a second current signal,

the DCS is electrically connected with the first transmitter and the second transmitter and used for acquiring the first current signal and the second current signal, converting the first current signal and the second current signal into digital signals and then calculating to obtain pressure difference, and calculating to obtain the liquid level in the heat exchange water tank according to a logic formula of the liquid level and the pressure difference stored in the DCS.

Optionally, the logical formula of the liquid level and the pressure difference is:

wherein:

delta P is the pressure difference between the bottom and the top of the liquid level in the heat exchange water tank;

rho is the density of the medium in the heat exchange water tank, and g is the gravity acceleration.

Optionally, the first pressure sensing gauge and the first transmitter are integrated to form a first integrated absolute pressure transmitter.

Optionally, the first integrated absolute pressure transmitter is arranged on a first pressure taking pipe, and the first pressure taking pipe is communicated with a water outlet pipeline at the bottom of the heat exchange water tank through a first pressure taking nozzle.

Optionally, the second pressure gauge and the second transmitter are integrated to form a second integrated absolute pressure transmitter.

Optionally, the second integrated absolute pressure transmitter is arranged on a second pressure taking pipe, and the second pressure taking pipe is communicated with a manhole channel at the top of the heat exchange water tank through a second pressure taking pipe nozzle.

The invention also provides a PCS system of a nuclear power plant, which comprises a heat exchange water tank and the heat exchange water tank liquid level measuring system.

The invention also provides a method for measuring the liquid level of the heat exchange water tank by using the system, which comprises the following steps:

the first pressure detection instrument detects the water pressure at the bottom of the heat exchange water tank and transmits a detected first pressure signal to the first transmitter, the first transmitter converts the first pressure signal into a first current signal,

the second pressure detecting instrument detects the water pressure at the top of the heat exchange water tank and transmits a detected second pressure signal to the second transmitter, the second transmitter converts the second pressure signal into a second current signal,

the DCS acquires the first current signal and the second current signal, converts the first current signal and the second current signal into digital signals, calculates the digital signals to obtain pressure difference, and calculates the liquid level in the heat exchange water tank according to a logic formula of the liquid level and the pressure difference stored in the DCS.

Optionally, the method further comprises:

and when the calculated liquid level in the heat exchange water tank is lower than a set threshold value, the DCS prompts a low threshold value to alarm.

Optionally, the logical formula of the liquid level and the pressure difference is:

wherein:

delta P is the pressure difference between the bottom and the top of the liquid level in the heat exchange water tank;

rho is the density of the medium in the heat exchange water tank, and g is the gravity acceleration.

In the invention, the pressure detection instruments are respectively arranged on the water outlet pipe and the manhole channel (water inlet) of the heat exchange water tank to respectively detect the water pressure at the bottom and the top of the medium in the heat exchange water tank, and the liquid level of the medium in the heat exchange water tank can be calculated according to the logic formula of the liquid level and the pressure difference, so that the problem of poor instrument precision caused by long-distance capillary transmission is avoided, and the installation risk and the difficulty of maintenance and detection are greatly reduced. In addition, the invention also monitors the pressure at the upper part of the liquid level of the water tank, thereby avoiding the error caused by the difference between the pressure at the low-pressure side and the atmospheric pressure.

Drawings

Fig. 1 is a schematic structural diagram of a heat exchange water tank liquid level measurement system provided in embodiment 1 of the present invention;

fig. 2 is a schematic structural diagram of a heat exchange water tank liquid level measurement system provided in embodiment 1 of the present invention.

Detailed Description

The technical solutions in the present invention will be described clearly and completely with reference to the accompanying drawings, and it is obvious that the described embodiments are some, but not all embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the scope of the present invention.

In the description of the present invention, it should be noted that the indication of orientation or positional relationship, such as "on" or the like, is based on the orientation or positional relationship shown in the drawings, and is only for convenience and simplicity of description, and does not indicate or imply that the device or element referred to must be provided with a specific orientation, constructed and operated in a specific orientation, and thus, should not be construed as limiting the present invention.

In the description of the present invention, the terms "first" and "second" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.

In the description of the present invention, it is to be noted that, unless otherwise explicitly specified or limited, the terms "connected," "disposed," "mounted," "fixed," and the like are to be construed broadly, e.g., as being fixedly or removably connected, or integrally connected; either directly or indirectly through intervening media, or may be interconnected between two elements. The specific meaning of the above terms in the present invention can be understood in specific cases for those skilled in the art.

The invention provides a liquid level measuring system of a heat exchange water tank, which comprises: the system comprises a first pressure detection instrument, a first transmitter, a second pressure detection instrument, a second transmitter and a DCS (distributed control System);

the first pressure detection instrument is arranged on a water outlet pipeline at the bottom of the heat exchange water tank, is electrically connected with the first transmitter and is used for detecting the water pressure at the bottom of the heat exchange water tank and transmitting a detected first pressure signal to the first transmitter, the first transmitter is used for converting the first pressure signal into a first current signal,

the second pressure detection instrument is arranged on a manhole channel at the top of the heat exchange water tank, is electrically connected with the second transmitter and is used for detecting the water pressure at the top of the heat exchange water tank and transmitting a detected second pressure signal to the second transmitter, the second transmitter is used for converting the second pressure signal into a second current signal,

the DCS is electrically connected with the first transmitter and the second transmitter and used for acquiring the first current signal and the second current signal, converting the first current signal and the second current signal into digital signals and then calculating to obtain pressure difference, and calculating to obtain the liquid level in the heat exchange water tank according to a logic formula of the liquid level and the pressure difference stored in the DCS.

The invention also provides a PCS system of a nuclear power plant, which comprises a heat exchange water tank and the heat exchange water tank liquid level measuring system.

The invention also provides a method for measuring the liquid level of the heat exchange water tank by using the system, which comprises the following steps:

the first pressure detection instrument detects the water pressure at the bottom of the heat exchange water tank and transmits a detected first pressure signal to the first transmitter, the first transmitter converts the first pressure signal into a first current signal,

the second pressure detecting instrument detects the water pressure at the top of the heat exchange water tank and transmits a detected second pressure signal to the second transmitter, the second transmitter converts the second pressure signal into a second current signal,

the DCS acquires the first current signal and the second current signal, converts the first current signal and the second current signal into digital signals, calculates the digital signals to obtain pressure difference, and calculates the liquid level in the heat exchange water tank according to a logic formula of the liquid level and the pressure difference stored in the DCS.

Example 1:

as shown in fig. 2, the present embodiment provides a heat exchange water tank liquid level measurement system, including: the system comprises a first pressure detection instrument, a first transmitter, a second pressure detection instrument, a second transmitter and a DCS (distributed control System) 1;

the first pressure detection instrument is arranged on the water outlet pipeline 5 at the bottom of the heat exchange water tank 8, is electrically connected with the first transmitter and is used for detecting the water pressure at the bottom of the heat exchange water tank 8 and transmitting a detected first pressure signal to the first transmitter, the first transmitter is used for converting the first pressure signal into a first current signal,

the second pressure detection instrument is arranged on the manhole channel 7 at the top of the heat exchange water tank 8, is electrically connected with the second transmitter and is used for detecting the water pressure at the top of the heat exchange water tank 8 and transmitting a detected second pressure signal to the second transmitter, the second transmitter is used for converting the second pressure signal into a second current signal,

the DCS system 1 is electrically connected with the first transmitter and the second transmitter and used for collecting the first current signal and the second current signal, converting the first current signal and the second current signal into digital signals and then calculating to obtain pressure difference, and calculating to obtain the liquid level in the heat exchange water tank 8 according to the liquid level stored in the DCS system and a logic formula of the pressure difference.

From this, through setting up pressure measurement instrument on heat exchange water tank 8's outlet conduit 5 and manhole passageway 7 (intaking) respectively to detect the water pressure at medium bottom and top in the heat exchange water tank respectively, can calculate the liquid level that obtains medium in the heat exchange water tank 8 according to the logic formula of liquid level and pressure differential again, thereby avoided the poor problem of instrument precision that long distance capillary transmission brought, and the degree of difficulty greatly reduced of the risk of installation and maintenance detection. In addition, the invention also monitors the pressure at the upper part of the liquid level of the water tank, thereby avoiding the error caused by the difference between the pressure at the low-pressure side and the atmospheric pressure.

In this embodiment, first pressure measurement appearance and first transmitter integrated form first integral type absolute pressure transmitter 2, and second pressure measurement appearance and second transmitter integrated form second integral type absolute pressure transmitter 3 to satisfy the antidetonation requirement. The measurement precision of the instrument is about 0.8%.

The meter is installed in a plate mode, the identification grade is K3, and the protection grade is IP 67.

In this embodiment, first integral absolute pressure transmitter 2 is located on a first pressure pipe 4, and first pressure pipe 4 is linked together through the outlet conduit 5 of first pressure pipe 4 mouth and heat exchange water tank bottom.

In this embodiment, second integral type absolute pressure transmitter 3 locates on a second pressure pipe 6, and second pressure pipe 6 is got through the second and is pressed 6 mouths and be linked together with manhole passageway 7 at heat exchange water tank top.

The liquid level measuring system of the heat exchange water tank mainly comprises two parts, namely a pressure detecting instrument and a transmitter, and a DCS internal calculation processing system.

The liquid level measurement of the heat exchange water tank of the PCS system is realized by respectively measuring the upper pressure and the bottom pressure of the liquid level in the water tank by using two pressure detection instruments and a transmitter and then obtaining the liquid level value of the water tank through the internal preset calculation logic of the DCS.

And pressure taking nozzles are arranged on a manhole channel at the top of the water tank and on a vertical pipeline for water outlet at the bottom of the water tank and 500mm away from the bottom of the water tank, and the direction of the pressure taking nozzles at the manhole pipeline faces to the parapet wall. The pressure detection instrument is connected through a pressure guide pipe and the like, and is used for monitoring the upper pressure MN1 of the liquid level in the water tank and the bottom pressure MN2 of the liquid level in the water tank.

The two pressure signals are converted into standard 4-20mA current signals under the action of the DCS query voltage through the transmitter, and are sent to the DCS through the measuring cable for collection and subsequent operation. And the DCS calculates the liquid level value in the water outlet tank through a preset liquid level calculation formula to complete the real-time detection of the liquid level.

The DCS internal calculation processing module presets calculation logic inside the DCS according to a formula of liquid level and pressure difference:

wherein:

delta P is the pressure difference of the upper part and the lower part of the liquid level in the water tank, namely delta P is MN2-MN 1; rho is the density of the medium in the water tank, and is 0.997kg/m based on the environmental condition of the heat exchange water tank of the PCS system³；

g is gravity acceleration, g is 9.8m/s²；

According to the preset calculation logic, automatic logic calculation is carried out under the condition that two pressure values are collected, and the liquid level value in the water tank with high accuracy can be quickly obtained. The value can be transmitted to a picture of a main control room and a backup panel through a network and hard wiring to be displayed, so that the liquid level of the water tank can be monitored in real time.

When the actual liquid level in the water tank changes, the values of MN1 and MN2 will change, and the calculated liquid level value will change accordingly.

Furthermore, on the basis of the calculated level value, threshold calculation is carried out through the interior of the DCS, an alarm can be triggered when the liquid level drops to a certain value, and corresponding acousto-optic prompts are generated in the main control room to remind power plant operators of carrying out corresponding treatment.

The detector and the transmitter adopt an integrated absolute pressure transmitter, and the upper pressure of the liquid level in the water tank is closer to the atmospheric pressure, so that the absolute pressure transmitter can be used for more accurately measuring the partial pressure.

The integrated transmitter does not require external power.

The internal calculation period of the DCS is 500ms, the calculation error can be ignored, and the timely and accurate calculation requirements can be met.

In addition, the accuracy of the absolute pressure transmitter is about 0.8%, and the instrument is mature and reliable.

Therefore, the liquid level measuring system of the heat exchange water tank can accurately monitor the liquid level of the heat exchange water tank of the PCS system of the nuclear power station in real time, and trigger the alarm in time when the liquid level is low, so as to avoid that the cooling function of the heat exchange water tank of the PCS system can not meet the requirement. The method has the advantages of high measurement and display precision, short response time, timely leakage alarm, convenience in installation and low cost, and reduces the difficulty of subsequent maintenance, instrument replacement and calibration.

In conclusion, the beneficial technical effects of the invention are as follows:

(1) the measuring accuracy is high, and the pressure at the upper part of the liquid level of the water tank is also monitored, so that errors caused by the fact that the pressure at the low-pressure side is different from the atmospheric pressure are avoided.

(2) The DCS is rapid and accurate in internal calculation, so that the liquid level of the heat exchange water tank can be accurately and reliably monitored.

(3) On the basis of (2), alarm can be triggered in time through preset logic, and risks caused by unknown water tank leakage are reduced.

(4) The used meter is easy to maintain and mature and reliable.

(5) The risk of long distance capillary installation and the difficulty of maintenance detection have been avoided.

Example 2:

the embodiment provides a nuclear power plant PCS system, including heat exchange water tank 8 to and the heat exchange water tank liquid level measurement system of embodiment 1.

Example 3:

the embodiment provides a method for measuring the liquid level of a heat exchange water tank by using the system in the embodiment 1, which comprises the following steps:

the first pressure detecting instrument detects the water pressure at the bottom of the heat exchange water tank and transmits a detected first pressure signal to the first transmitter, the first transmitter converts the first pressure signal into a first current signal,

the second pressure detecting instrument detects the water pressure at the top of the heat exchange water tank and transmits a detected second pressure signal to the second transmitter, the second transmitter converts the second pressure signal into a second current signal,

the DCS system 1 collects the first current signal and the second current signal, converts the first current signal and the second current signal into digital signals, calculates the pressure difference, and calculates the liquid level in the heat exchange water tank according to the liquid level stored in the DCS system and a logic formula of the pressure difference.

When the calculated liquid level in the heat exchange water tank is lower than a set threshold value, the DCS 1 prompts a low threshold value to alarm.

The liquid level measuring method of the heat exchange water tank of the PCS system of the nuclear power plant is used for solving the problems of poor measuring precision and inaccurate alarm in the existing design, and simultaneously can reduce the difficulty of installation and maintenance.

It will be understood that the above embodiments are merely exemplary embodiments taken to illustrate the principles of the present invention, which is not limited thereto. It will be apparent to those skilled in the art that various modifications and improvements can be made without departing from the spirit and substance of the invention, and these modifications and improvements are also considered to be within the scope of the invention.