Liquid level measurement and control device and method used in nuclear industry environment

Abstract

The invention discloses a liquid level measurement and control device and method used in a nuclear industry environment. The device comprises a buoy module, a continuous liquid level monitoring module and an alarm module, the floating module comprises a floating ball which ascends and descends along with fluctuation of the liquid level, and a permanent magnet is connected to the upper portion of the floating ball. The continuous liquid level monitoring module comprises a reed switch assembly arranged around the vertical stroke of the permanent magnet. The alarm module comprises at least one microswitch, and when the number of the microswitch is one, the microswitch is arranged on the upper portion or the lower portion of the reed switch assembly. When the number of the microswitches is at least two, the microswitches are respectively arranged on the upper portion and the lower portion of the vertical stroke of the permanent magnet. The liquid level measurement and control device used in the nuclear industry environment is applied to the method, and the method comprises a detection program A. The detection program A comprises the following steps that A1, the liquid level measurement and control device is calibrated; a2, measuring the numerical value of the liquid level; and A3, liquid level height value alarming is carried out.

Description

Technical Field

[0001] The present invention relates to the technical field of liquid level measurement, and in particular to a liquid level measurement and control device and method used in a nuclear industry environment. Background Art

[0002] The reactor coolant pump, or main pump, is the only continuously operating equipment in the main system of the nuclear power plant loop and is the heart of the nuclear power plant. The operating conditions of the main pump are very harsh. The medium it transports is the main coolant of the nuclear power plant primary circuit, boric acid solution, which has a pressure of 152 bar and a temperature of 290°C and is highly radioactive and corrosive. Considering nuclear safety and environmental protection, the leakage of the main pump must be small and the operating reliability must be high, so the main pump must operate safely. The main pump drive motor is the only power component that drives the main pump to rotate at high speed. The operating speed is as high as 1500 rpm, which places high demands on the bearing lubrication medium. Therefore, during the service operation of the main pump motor, high requirements are placed on the sealing system of the bearing lubrication medium to ensure the continuous and safe operation of the main pump motor. Therefore, a level measurement and control system is required for monitoring.

[0003] Since the main pump motor bearing chamber cavity needs to withstand nuclear radiation (5.3×106rad), electromagnetic radiation, high amplitude vibration (peak-to-peak amplitude 75um), medium and high temperature (15-60℃) and humidity (≤100%) during operation, conventional liquid level measurement and control instruments are difficult to adapt, and the function is single, and it is difficult to meet the needs of nuclear power plants for real-time monitoring of liquid levels. Therefore, it is very necessary to develop a kind of oil level gauge with both monitoring and monitoring functions. For example, the oil level gauges used for oil level monitoring of large motor sliding bearing oil tanks currently mainly use micro switch oil level gauges, reed chain oil level gauges and magnetostrictive oil level gauges. These three oil level gauges have certain adaptability to working conditions, but there are great deficiencies in the nuclear industry working environment. They can only provide switch alarm signals and cannot continuously measure the oil level. The dead zone of the instrument is large, or the resistance to nuclear radiation is poor and the resistance to load impact is poor. Summary of the invention

[0004] The purpose of the present invention is to provide a liquid level measurement and control device and method for use in a nuclear industry environment in response to the above-mentioned existing problems, thereby reducing the problem of real-time measurement and monitoring of the liquid level of the main pump motor during the operation of a nuclear power plant, providing sufficient lubrication conditions for the safe and long-term operation of the main pump motor, and reducing the potential safety hazard of abnormal reactor shutdown caused by insufficient bearing lubrication of the main pump motor. In particular, when the oil level of the motor bearing drops due to excessive volatilization of lubricating oil, the liquid level measurement and control device of the present invention can provide monitoring data so that the maintenance personnel of the power plant can intervene in advance.

[0005] The technical solution adopted by the present invention is as follows:

[0006] A liquid level measurement and control device for use in a nuclear industry environment, comprising a float module, a continuous liquid level monitoring module and an alarm module;

[0007] The float module includes a float ball that rises and falls with the fluctuation of the liquid level, and a permanent magnet is connected to the top of the float ball;

[0008] The continuous liquid level monitoring module includes a reed switch assembly arranged around the upper and lower travels of the permanent magnet;

[0009] The alarm module includes at least one micro switch. When there is one micro switch, the micro switch is arranged at the upper part or the lower part of the reed switch assembly; when there are at least two micro switches, the micro switches are respectively arranged at the upper part and the lower part of the upper and lower travel of the permanent magnet.

[0010] Optionally, a liquid level measurement and control device for use in a nuclear industry environment also includes a monitoring box and a liquid level box, wherein the continuous liquid level monitoring module and the alarm module are both located in the monitoring box; an oil inlet pipe and an oil pressure balance pipe are provided on the liquid level box, wherein the oil inlet pipe is connected to the oil chamber of the main equipment and forms a communicating vessel with the oil chamber of the main equipment; the float is located in the liquid level box, the permanent magnet is located in the monitoring box, the float is connected to the model transmission structure via a supporting rod, and the supporting rod passes through the monitoring box and the liquid level box.

[0011] Optionally, shielding plates are provided on the outer sides of the continuous liquid level monitoring module and the alarm module.

[0012] Optionally, a grounding bolt is provided on the monitoring box.

[0013] Optionally, a first flange is provided at the lower portion of the monitoring box, and a second flange is provided at the upper portion of the liquid level box, and the first flange and the second flange are butt-jointed via an insulating pad; a sealing groove is provided at the first flange and / or the second flange and / or the insulating pad, and a first sealing ring is provided in the sealing groove.

[0014] Optionally, a sealing bracket is provided on the upper portion of the liquid level box, the sealing bracket is fixed below the first flange or the second flange, a second sealing ring is provided inside the sealing bracket, and the support rod passes through the second sealing ring.

[0015] A liquid level measurement and control method for use in a nuclear industry environment, using the liquid level measurement and control device for use in a nuclear industry environment as described above, includes a detection procedure A, wherein the detection procedure A includes the following steps:

[0016] Step A1, calibrating the liquid level measurement and control device;

[0017] Step A2, measuring the liquid level value;

[0018] Step A3: Liquid level high and low value alarm.

[0019] Optionally, the step A1 includes the following steps:

[0020] A11. Determination of analog quantity: between the high liquid level Llow and the low liquid level Lhigh, read a liquid level value L every time the liquid level drops by ΔL until the low liquid level Llow, read a total of N liquid level values, calculate the difference with the corresponding actual liquid level value, and become the positive stroke error; similarly, measure the error again from the low liquid level Llow to the high liquid level Lhigh, and become the reverse stroke error;

[0021] A12. Determination of switch quantity: The two liquid point locations L1 and L2 are used as the alarm values ​​of high and low liquid levels respectively. When the oil level is lower than the lower limit L1, that is, when the magnet reaches the position of the lower limit alarm switch module downward, the upper limit switch is activated, and the normally open and normally closed contacts are switched, that is, the high alarm oil level switch signal is transmitted remotely from the interface socket; when the oil level is lower than the lower limit L2, that is, when the magnet reaches the position of the lower limit alarm switch module downward, the lower limit switch is activated, and the normally open and normally closed contacts are switched, that is, the low alarm oil level switch signal is transmitted remotely from the interface socket.

[0022] Optionally, step A2 includes the following steps: after the liquid level measurement and control device is accurately debugged, the main equipment starts to add the measuring medium until the target liquid level value; as the liquid level inside the liquid level box gradually rises, the float also rises and drives the support rod and the permanent magnet at the upper end to continue to rise; during the continuous rise of the permanent magnet, it continuously triggers the surrounding reed switches to switch from off to on, thereby continuously transmitting the liquid level information; when the liquid level reaches the target value, the float no longer rises, and the permanent magnet at the upper end of the support rod also stops around a certain reed switch, which becomes the last reed switch to be turned on, and the output analog signal stabilizes; when the liquid level drops, the float also drops and drives the movable rod and the permanent magnet to drop synchronously, and the continuous drop of the permanent magnet drives a series of reed switches to be cut off and turned on, so that a voltage analog signal can be output.

[0023] Optionally, the step A3 comprises the following steps:

[0024] When the liquid level reaches the maximum value, the permanent magnet will trigger the micro switch at the highest position to conduct, thereby outputting a high voltage analog signal and sending out a high oil level alarm signal;

[0025] When the liquid level reaches the minimum value, the permanent magnet will trigger the micro switch at the lowest position to conduct, thereby outputting a low voltage analog signal and sending out a low oil level alarm signal.

[0026] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are:

[0027] 1. The liquid level measurement and control device and method provided by the present invention for use in a nuclear industry environment are conducive to the accurate measurement and early warning monitoring of the liquid level in the inner cavity of the main equipment. At the same time, it improves the measurement accuracy, control reliability and durability of use for working conditions such as nuclear industry radiation, high-frequency electromagnetic fields, high-amplitude vibrations, and medium and high temperature liquid media, and meets the use requirements of complex working conditions in the nuclear industry environment.

[0028] 2. It meets the needs of liquid level measurement and control in the nuclear industry environment, and can be used for remote measurement and control of lubricating oil, cooling water or other liquid media in various key equipment. It not only improves the safety and convenience of close-range measurement and control, but also can achieve accurate measurement and effective control of liquid level, maintain the safe operation of nuclear industry main equipment and the safety of monitoring personnel.

[0029] 3. The liquid level measurement and control system and method provided by the present invention for use in a nuclear industry environment has components from a wide range of sources, is simple to use, and is easy to replace. Therefore, it has high economic efficiency and can be fully used as a spare parts reserve.

[0030] 4. The present invention provides a liquid level measurement and control system and method for use in a nuclear industry environment, including two sets of high / low alarm liquid level switch signals, which are used to prompt the nuclear power plant operator to shut down the main pump motor or add oil to the bearing oil tank online; a set of continuous liquid level monitoring analog signals, which facilitates the nuclear power plant operator to determine whether there is abnormal oil vapor volatilization or leakage of the lubricating oil in the main pump motor bearing oil tank. It can continuously monitor the real-time liquid level in the main pump motor bearing oil tank and output it to the nuclear power plant control system. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] The present invention will now be described by way of example with reference to the accompanying drawings, in which:

[0032] Figure 1 The diagram is a schematic diagram of the external structure of a liquid level measurement and control device used in a nuclear industry environment.

[0033] Figure 2 It is a schematic diagram of the internal structure of the monitoring box.

[0034] Figure 3 It is a schematic diagram of the internal structure of the liquid level tank.

[0035] Figure 4 This is a schematic diagram of the internal structure of a liquid level measurement and control device used in a nuclear industry environment. Figure 2 .

[0036] Markings in the figure: 1-continuous liquid level monitoring module, 2-alarm module, 3-active module, 4-float, 5-monitoring box, 6-liquid level box, 7-support rod, 8-permanent magnet, 9-first flange, 10-second flange, 11-insulating pad, 12-first sealing ring, 13-sealing bracket, 14-second sealing ring, 15-grounding bolt, 16-socket, 17-housing seat, 18-protective cover, 19-screw, 20-upper bracket, 21-lower bracket, 22-guide tube, 23-casing. DETAILED DESCRIPTION

[0037] The present invention will be described in detail below in conjunction with the accompanying drawings.

[0038] All features disclosed in this specification, or steps in all methods or processes disclosed, except mutually exclusive features and / or steps, can be combined in any manner.

[0039] Any feature disclosed in this specification, unless otherwise stated, can be replaced by other equivalent or alternative features with similar purposes. That is, unless otherwise stated, each feature is only an example of a series of equivalent or similar features.

[0040] A liquid level measurement and control device for use in a nuclear industry environment, such as Figure 1-4 As shown, it includes a float module, a continuous liquid level monitoring module 1 and an alarm module 2;

[0041] The float module includes a float ball 4 that rises and falls with the fluctuation of the liquid level, and a permanent magnet 8 is connected to the top of the float ball 4; as the liquid level in the container rises and falls, the float module also produces corresponding lifting and lowering movements, and the permanent magnet 8 will trigger the reed switch to turn on and off through the action of the static magnetic field, thereby realizing the output of the liquid level parameters. If the liquid level parameter is close to the pre-set high and low critical values, the permanent magnet 8 on the movable component will trigger the micro switches at the high and low liquid level positions to realize the high and low liquid level alarm function. Preferably, the continuous liquid level monitoring module 1 and the alarm module 2 are connected to the same float module.

[0042] The continuous liquid level monitoring module 1 includes a reed switch assembly arranged around the up and down stroke of the permanent magnet 8; the reed switch assembly includes a plurality of reed switches, and the plurality of reed switches are fixed on a circuit board, and the same number of resistance elements are connected to the reed switches to form an analog signal circuit. The analog signal circuit can receive the liquid level information transmitted by the permanent magnet 8, and form an analog signal through the on and off of some reed switches, and transmit it over long distances. The normally open reed switch with high-precision switching sensitivity receives the static magnetic field of the permanent magnet 8 when the permanent magnet 8 moves up and down, thereby realizing the conduction and cutoff of different numbers of reed switches, thereby changing the analog signal in the circuit. The resistance element forms a certain parallel or series relationship with the reed switch, and when the number of reed switches that are turned on changes, the voltage component on some resistors is transmitted to the remote monitoring location by the circuit. Specifically, as the liquid level rises and falls, the permanent magnet 8 moves around the reed switch to realize the conduction and cutoff of the reed switch, thereby causing the total resistance (or voltage) of the transmitter to change. The transmitter then converts the changed resistance (or voltage) signal into a 4-20mA current signal output, thereby converting the liquid level distance signal into a voltage signal and transmitting it to a remote monitoring location that can ensure nuclear radiation safety.

[0043] The alarm module 2 includes at least one micro switch. When there is one micro switch, the micro switch is arranged at the upper or lower part of the reed switch assembly; when there are at least two micro switches, the micro switches are arranged at the upper and lower parts of the upper and lower strokes of the permanent magnet 8, respectively. The switch signal generated by the micro switch is output through the switch circuit. The micro switch is set to two states, normally open and on. The normal state is in the off state. When the permanent magnet 8 rises and falls to the vicinity of the micro switch with the fluctuation of the liquid level, the micro switch will be changed to the on state, and the switch signal information will be transmitted to issue an alarm of too much or too little liquid level. Preferably, a micro switch is provided at the high point of the permanent magnet 8 stroke as a monitoring element for too high liquid level, and another micro switch is provided at the low point as a monitoring element for too low liquid level. The two micro switches are used to monitor the maximum and minimum values ​​of the liquid level, and the distance information can be formed into a switch signal and transmitted to a remote monitoring location. Further, the micro switch transmits the signal through a triangular nuclear power special aviation plug.

[0044] This solution aims to solve the problems of incomplete measurement and control functions, insufficient vibration resistance, insufficient radiation resistance and insufficient measurement accuracy in existing liquid level measuring instruments. Through reasonable design, the measurement and control functional facilities are integrated, and the material selection and structural layout are optimized to form a liquid level measurement and control system with excellent comprehensive performance that has both measurement and control functions and is resistant to high-frequency vibration, radioactive radiation and electronic radiation, and has high measurement accuracy. It is suitable for the nuclear industry and has high-frequency vibration environments. Compared with the existing liquid level measurement and control instruments in conventional industrial environments or under static conditions, it has the advantages of high reliability, high precision and high efficiency, which helps to improve the safety of equipment in nuclear industrial environments.

[0045] Preferably, the present invention and the nuclear industry control system are connected by a three-pin plug (control system side) and a socket 16 (liquid level measurement and control device side) of quick plug-in type connection.

[0046] Specifically, when the liquid level fluctuation drives the permanent magnet 8 to rise and fall, when it approaches a certain reed switch in the reed switch assembly, the state of the reed switch changes from disconnected to conductive, thereby causing the resistor and resistance value in the intervention circuit to change, and the input analog voltage also changes, thereby realizing the conversion of the liquid level signal into an analog signal, and connecting to the control system through a three-pin quick connection socket 16 for long-distance transmission, wherein the socket 161# contact is connected to the positive pole of the control system, the 2# contact is connected to the negative pole of the control system, and the 3# contact does not need to be connected, and its resolution is 2mm.

[0047] Preferably, the analog signal requirement for continuously monitoring the oil level in the bearing tank is 4-20mA (DC), the nominal voltage on the control system side is 24V (DC), and when the oil level is 280mm, 4mA is output (corresponding to "0%"), and when the oil level is 210mm, 20mA is output (corresponding to "100%").

[0048] The nominal voltage on the control system side corresponding to the two sets of high / low alarm level switch signals is 48V (DC). The two sockets are used for the output of the two sets of high / low alarm level switch signals. The wiring requirements are as follows:

[0049] High alarm liquid level switch signal interface socket:

[0050] Contacts 1 and 2 are connected - high liquid level alarm.

[0051] Contacts 2 and 3 are connected - the liquid level is normal.

[0052] At the low alarm liquid level switch signal interface socket:

[0053] Contacts 1 and 2 are connected—liquid level is normal.

[0054] Contacts 2 and 3 are connected - low liquid level alarm.

[0055] Furthermore, the float 4 is a closed small ball floating on the liquid level surface, with a size of approximately Φ90±5mm×125mm. The ball is made of austenitic stainless steel with high corrosion resistance, and its shape can be adjusted according to the density and viscosity of the liquid level until the accuracy of the liquid level measurement is highest.

[0056] As another specific embodiment, it includes a monitoring box 5 and a liquid level box 6, wherein the continuous liquid level monitoring module 1 and the alarm module 2 are both located in the monitoring box 5; the liquid level box 6 is provided with an oil inlet pipe and an oil pressure balance pipe, wherein the oil inlet pipe is connected to the oil chamber of the main equipment and forms a communicating vessel with the oil chamber of the main equipment; the float 4 is located in the liquid level box 6, the permanent magnet 8 is located in the monitoring box 5, and the float 4 is connected to the model transmission structure through a support rod 7, wherein the support rod 7 passes through the monitoring box 5 and the liquid level box 6. The monitoring box 5 is used to protect and place the electronic components in the measurement and control device to prevent these electronic components from being affected by the external environment and to extend the service life of the device. The liquid level box 6 is connected to the oil chamber and is used to isolate the lubricating oil from the measurement and control components to ensure the safe operation of the measurement and control device. Among them, the material of the support rod 7 is cast iron with good wear resistance, or a metal material with chrome plating on the surface. The cross-sectional size and straightness of the movable rod have a great influence on the lifting and lowering of the movable component, and stress relief annealing is required before use to avoid deformation during use and cause the movable component to jam. Furthermore, the monitoring box 5 is made of metal, preferably austenitic stainless steel or gray cast iron, among which gray cast iron can be used as a preferred solution to improve the explosion-proof performance of the present invention due to its low thermal expansion coefficient, high dimensional stability and high strength, to prevent the oil mist medium inside the measurement and control system from combining with the external combustion-supporting gas through the matching gap to produce an explosion. Specifically, the safety protection level of the present invention is better than IP65.

[0057] As a further embodiment, the monitoring box 5 includes a housing seat 17 and a protective cover 18. The housing seat 17 is provided with a screw 19. The continuous liquid level monitoring module 1 and the alarm module 2 are respectively provided on the screw 19 through nuts for adjusting the height. The upper ends of the plurality of screws 19 are all provided on an upper bracket 20, and the lower ends are all provided on a lower bracket 21. A guide tube 22 is provided between the upper bracket 20 and the lower bracket 21, and the permanent magnet 8 is provided in the guide tube 22. A casing 23 is provided in the liquid level box 6, and a plurality of oil holes are provided on the casing 23. The float 4 is located in the casing 23.

[0058] As another specific implementation, a shielding plate is provided outside the continuous liquid level monitoring module 1 and the alarm module 2. The thinner high-purity lead shielding plate is used to shield the nuclear radiation rays in the nuclear industrial environment and protect the normal operation of the continuous liquid level monitoring module 1 and the alarm module 2.

[0059] As another specific implementation, the monitoring box 5 is provided with a grounding bolt 15. This reduces static electricity accumulation and further improves explosion-proof performance.

[0060] As another specific implementation, the lower part of the monitoring box 5 is provided with a first flange 9, and the upper part of the liquid level box 6 is provided with a second flange 10, and the first flange 9 and the second flange 10 are connected through an insulating pad 11, the purpose is to prevent the power supply of the upper measurement and control functional component from being transmitted to the lower liquid level box 6 or even the main equipment, causing safety hazards to the main equipment; the first flange 9 and / or the second flange 10 and / or the insulating pad 11 are provided with a sealing groove, and a first sealing ring 12 is provided in the sealing groove. The first flange 9 and the second flange 10 are connected to form a top-mounted liquid level measurement and control device.

[0061] As another specific embodiment, a sealing bracket 13 is provided on the upper part of the liquid level box 6, and the sealing bracket 13 is fixed below the first flange 9 or the second flange 10. A second sealing ring 14 is provided in the sealing bracket 13, and the support rod 7 passes through the second sealing ring 14. In this solution, the sealing bracket 13 includes two circular rings stacked up and down, and the circular rings are fixed upward on the first flange 9 by bolts. A groove for placing the second sealing ring 14 is provided in the middle of the contact surface of the two circular rings. The inner diameter of the second sealing ring 14 is equal to or slightly smaller than the inner diameter of the sealing bracket 13, so as to correspond to the support rod 7. The second sealing ring 14 can prevent the oil mist in the liquid level box 6 from being transmitted to the upper monitoring box 5, reduce the accumulation of oil mist and cooled liquid oil in the cavity of the monitoring box 5, and affect the sensitivity and accuracy of the monitoring element, resulting in distortion of the monitoring data; and affect the smooth rise and fall of the movable parts such as the float 4 due to the high viscosity. At the same time, due to the common problem that the support rod 7 is easily stuck when it deviates from the axis in the prior art of the same type of oil level gauge. In this solution, the sealing bracket 13 and the second sealing ring 14 can play a role in center positioning and guiding, ensuring that the support rod 7 floats up and down in the axial direction of the liquid level measurement and control device, avoiding the problem that the support rod 7 deviates from the axis and is deformed by external interference, thereby causing the liquid level measurement and control to fail.

[0062] Specifically, a rubber sealing ring with radiation resistance, oil mist resistance, low temperature resistance and high temperature resistance is preferably used, and a sealing ring made of fluororubber or hydrogenated nitrile rubber has the best sealing performance.

[0063] A liquid level measurement and control method for use in a nuclear industry environment, using the liquid level measurement and control device for use in a nuclear industry environment as described above, includes a detection procedure A, wherein the detection procedure A includes the following steps:

[0064] Step A1, calibrating the liquid level measurement and control device;

[0065] Step A2, measuring the liquid level value;

[0066] Step A3: Liquid level high and low value alarm.

[0067] As another specific implementation, the step A1 includes the following steps:

[0068] Step A11: Determination of analog quantity. Between the high liquid level of 50mm and the low liquid level of -50mm, a liquid level value L is read for every 10mm drop in liquid level until the low liquid level of -50mm is reached. A total of 11 liquid level values ​​are read, and the difference between the liquid level value and the corresponding actual liquid level value is calculated to become the positive stroke error. Similarly, the error is measured again from the low liquid level of -50mm to the high liquid level of 50mm to become the reverse stroke error.

[0069] Step A12 Determination of switch quantity. The two liquid point locations of +30mm and -40mm are used as the alarm values ​​of high and low liquid levels respectively. When the oil level is lower than the lower limit of +30, that is, when the permanent magnet 8 reaches the position of the lower limit alarm switch module downward, the upper limit switch is actuated, and the normally open and normally closed contacts are switched, that is, the high alarm oil level switch signal is transmitted remotely from the interface socket 16; when the oil level is lower than the lower limit of -40, that is, when the magnet reaches the position of the lower limit alarm switch module downward, the lower limit switch is actuated, and the normally open and normally closed contacts are switched, that is, the low alarm oil level switch signal is transmitted remotely from the interface socket 16; for a certain brand of mineral lubricating oil with a density of 0.85g / l at 15℃ and a dynamic viscosity of 31mm2 / s at 40℃, the high alarm liquid level switch signal of the liquid level measurement and control device should be calibrated at the installation liquid level of 210±1mm; the low alarm liquid level switch signal should be calibrated at the installation liquid level of 280±1mm.

[0070] Preferably, the switch value can be measured by the following method:

[0071] 1) Adjust the level of the calibration tool of the liquid level measurement and control device to 0.10mm / m.

[0072] 4) Place the upper monitoring box into the oil level gauge calibration fixture and open the protective cover on the top of the measurement and control system.

[0073] 5) Pour lubricating oil into the oil filling port until the oil level stabilizes at the -40mm oil level line.

[0074] 6) Adjust the low liquid level micro switch so that the micro switch just completes the action and fix the low liquid level micro switch.

[0075] 7) Continue to slowly pour oil until the low level micro switch is activated and the alarm is released. Record the oil level at this time in the attached record table. This oil level is the hysteresis level for the low level alarm to be released.

[0076] 8) Continue to add oil until the oil level stabilizes at the +30mm oil level line.

[0077] 9) Adjust the high liquid level micro switch so that the micro switch just completes the action. Fix the high liquid level micro switch.

[0078] 10) Slowly drain the oil until the high liquid level micro switch is activated and the high liquid level alarm is released. Record the oil level at this time in the attached record form. The oil level at this time is the high liquid level alarm release hysteresis oil level.

[0079] 11) Release the oil in the calibration tool and re-calibrate. This calibration requires the use of a multimeter to check the disconnection of the micro switch connector pins.

[0080] As another specific implementation, the step A2 includes the following steps:

[0081] Step A21: After the liquid level measurement and control device is debugged accurately, the main device starts to add the measuring medium until the target liquid level value is 0;

[0082] Step A22: As the liquid level inside the liquid level measurement and control device gradually rises, the float 4 also rises and drives the support rod 7 and the permanent magnet 8 at the upper end to continue to rise;

[0083] Step A23: During the continuous rising process, the permanent magnet 8 continuously triggers the surrounding reed switches to switch from off to on, thereby continuously transmitting the liquid level information.

[0084] Step A24: When the liquid level reaches the target value, the float 4 stops rising, and the permanent magnet 8 at the upper end of the support rod 7 stops around a certain reed switch, which becomes the last reed switch to be turned on, and the output analog signal stabilizes;

[0085] Step A25: When the liquid level drops, the float 4 also drops and drives the support rod 7 and the permanent magnet 8 to drop synchronously. The continuous drop of the permanent magnet 8 drives a series of reed switches to be cut off and turned on, thereby outputting a voltage analog signal.

[0086] As another specific implementation, the step A3 includes the following steps:

[0087] Step A31: When the liquid level reaches the maximum value, the permanent magnet 8 will trigger the micro switch at the highest position to turn on, thereby outputting a high voltage analog signal and sending out a high liquid level alarm signal.

[0088] Step A32: When the liquid level reaches the minimum value, the permanent magnet 8 will trigger the micro switch at the lowest position to turn on, thereby outputting a low voltage analog signal and sending out a low liquid level alarm signal.

[0089] As a supplement, an installation program B is also included, and the installation program B includes the following steps:

[0090] Step B1, assembling the internal structure of the monitoring box 5:

[0091] Step B10: The main support part of the liquid level measurement and control device is welded together by tungsten inert gas arc welding. When assembling these parts, the inner and outer circles are kept concentric. The weld type is a fillet weld, and the welding material is ER308L stainless steel welding wire.

[0092] Step B11: Connect the float 4 and the permanent magnet 8 to the two ends of the support rod 7 through threads;

[0093] Step B12: Place the PCB circuit board with the normally open reed switch and resistor arranged and fixed in the continuous liquid level monitoring module 1, and pass the M4 screw 19 with a diameter of Φ4 and threads at both ends through the upper and lower Φ6 light holes to seal them. The assembled continuous liquid level monitoring module 1 is used as a display module for the actual value of the liquid level;

[0094] Step B13: Use a screw 19 with a diameter of Φ16 and M16 threads at both ends to pass through the central hole Φ17 of the shell of the continuous liquid level monitoring module 1, and pre-install M16 nuts and spring washers on the threads at both ends;

[0095] Step B14: Pass the upper part of the assembly screw 19 of the one continuous liquid level monitoring module 1 and the two micro switch modules described in steps B12 and B13 through the Φ6 optical hole on the upper bracket 20 and fix them with nuts;

[0096] Step B15: slowly place the module and upper bracket 20 assembly described in step B12 on the lower bracket 21 of the housing seat 17 along the axial direction of the guide cylinder until the M12 thread on the upper end of the guide cylinder passes through the Φ12 hole in the middle of the upper bracket 20;

[0097] Step B16: Pass the Φ16 screw 19 through the Φ17 light hole in the middle of the continuous liquid level monitoring module 1 in step B13, and pass the Φ16 screw 19 through the Φ17 light hole in the middle of the alarm module 2 in step B14, and screw the lower threads of all the screws 19 into the screw holes of the lower bracket 21;

[0098] Step B17: Screw an M12 nut onto the M12 thread at the upper end of the guide cylinder to position lock the upper bracket 20 and the lower continuous liquid level monitoring module 1 and alarm module 2, so as to reduce the vibration interference of the vibration working condition on the reed switch and the micro switch, which affects the accuracy of oil level measurement and control and the reliability of long-term service;

[0099] Step B18: Assemble the permanent magnet 8, the support rod 7 and the floating ball 4 along the axial direction, the permanent magnet 8 enters the casing 23 at the lower end, the connecting tube in the middle and the guide tube at the upper part, and welds the bottom plate to the bottom of the casing 23 by welding;

[0100] Step B19: Slowly cover the upper bracket 20, continuous liquid level monitoring module 1, alarm module 2, guide cylinder and other internal components with the protective cover 18 along the axial direction, connect them with the external thread M147 of the shell seat 17, and then connect the cover plate of the shell with the upper thread M147 of the shell. The cover plate is provided with a lifting handle for easy inspection, disassembly and transfer measurement.

[0101] Step B2: Assembly of monitoring box 5 and liquid level box 6

[0102] Step B21 After completing the assembly of the monitoring box 5 according to the above step B1, slowly move the monitoring box 5 assembly onto the liquid level box 6. At this time, the first flange 9 of the monitoring box 5 is placed on the second flange 10 of the liquid level box 6. First, a rubber first sealing ring 12 that is resistant to media, high temperature, radiation and other aging is pre-installed on the first flange 9 of the liquid level box 6, and then the two flanges are fastened with M10 bolts. The monitoring box 5 is fixedly connected to the liquid level box 6.

[0103] B3. Connect the liquid level measurement and control device to the oil chamber of the main equipment.

[0104] Also included is a maintenance procedure C, the maintenance procedure C comprising the following steps:

[0105] Step C1: If the monitoring box 5 fails, the bolt fasteners on the first flange 9 should be loosened to remove the monitoring box 5 from the liquid level box 6;

[0106] Step C2: First, check the surface condition and deformation of the float 4 and the support rod 7, clean the grease on the surface of the float 4 and the support rod 7, straighten the deformed area, and replace the float 4 and the support rod 7 if necessary;

[0107] Step C3: Remove the upper protective cover 18, loosen the continuous liquid level monitoring module 1 or the alarm module 2 according to the type of fault (measurement problem or control problem), conduct a special inspection, and replace it if necessary.

[0108] Step C4: After maintenance, the monitoring box 5 is reinstalled on the flange surface of the liquid level box 6, and is re-calibrated and used according to step A.

[0109] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are:

[0110] (1) The measurement and control system of the present invention can simultaneously realize real-time measurement and real-time monitoring of the liquid level. The present invention can collect information on liquid level changes through the active component composed of the float 4, the support rod 7 and the permanent magnet 8, and convert the lifting and lowering displacement information of the active component into an analog signal of the reed switch; at the same time, the active component also realizes the on and off of the micro switch at the position of the maximum liquid level and the minimum liquid level, thereby converting the highest liquid level and the most recent liquid level into a switch signal. Therefore, the manufacture and assembly of each part of the liquid level measurement and control system of the present invention are simple and convenient, without special requirements, and can be modified and copied according to different sizes, and has wide versatility.

[0111] (2) The device of the present invention is compactly installed, and integrates two functional modules of micro switch type and reed switch type oil level gauge, with high operating reliability, high measurement accuracy, precise liquid level control, and good impact resistance. After the various parts of the device of the present invention are assembled, the overall size is compact, with a height of 810mm and a diameter of Φ157mm. In particular, the local system that forms analog signals and switch signals such as the permanent magnet 8, reed switch, and micro switch is concentrated in a small space of length 310mm×diameter Φ157mm; because the measurement and control system of the present invention has a variety of characteristics such as anti-vibration, radiation resistance, and explosion resistance from the perspective of structural design and material selection, the long-term reliability of the system is greatly improved; in addition, the measurement and control system uses high-precision reed switches and micro switches for liquid level signal conversion, which ensures the accuracy of liquid level measurement and control.

[0112] (3) The present invention has a convenient manufacturing, installation, debugging, disassembly and maintenance process. The alarm module 2 and the continuous liquid level monitoring module 1 are independent of each other and do not interfere with each other. Each functional module can be independently installed, wired, calibrated and replaced. It is obviously convenient in the installation, disassembly, maintenance and debugging process. This is because the number of components is small, the total weight is about 13Kg, the shapes of each component are regular, the material source is wide, the dimensional accuracy requirement is low, and it is easy to process and manufacture; among them, the continuous liquid level monitoring module 1 and the alarm module 2 are connected between the upper and lower brackets by a screw 19. The nut at the end of the screw 19 can adjust the upper and lower positions of the screw 19, thereby driving the module to move up and down, and finally realizing the liquid level zeroing calibration of the system; the components are connected by welding and a few threads, which not only has good rigidity, ensures the reliability of measurement and control under high-frequency vibration conditions, but also can be easily disassembled and parts replaced. In addition, the liquid level measurement and control system and the nuclear power plant system are connected by quick connectors, which is convenient for rapid isolation and maintenance.

[0113] The present invention is not limited to the above-mentioned specific embodiments, but extends to any new features or any new combination disclosed in this specification, as well as any new method or process steps or any new combination disclosed.

Claims

1. A liquid level measurement and control device for use in a nuclear industry environment, characterized in that: It comprises a float module, a continuous liquid level monitoring module (1) and an alarm module (2); The float module comprises a float ball (4) that rises and falls with the fluctuation of the liquid level, and a permanent magnet (8) is connected above the float ball (4); The continuous liquid level monitoring module (1) comprises a reed switch assembly arranged around the upper and lower travels of the permanent magnet (8); The alarm module (2) comprises at least one micro switch. When there is one micro switch, the micro switch is arranged at the upper part or the lower part of the reed switch assembly; when there are at least two micro switches, the micro switches are arranged at the upper part and the lower part of the upper and lower travel of the permanent magnet (8), respectively.

2. The liquid level measurement and control device for use in a nuclear industry environment as claimed in claim 1, characterized in that: The invention comprises a monitoring box (5) and a liquid level box (6), wherein the continuous liquid level monitoring module (1) and the alarm module (2) are both located in the monitoring box (5); the liquid level box (6) is provided with an oil inlet pipe and an oil pressure balance pipe, wherein the oil inlet pipe is connected to the oil chamber of the main equipment and forms a communicating vessel with the oil chamber of the main equipment; the float (4) is located in the liquid level box (6), the permanent magnet (8) is located in the monitoring box (5), the float (4) is connected to the model transmission structure via a support rod (7), and the support rod (7) passes through the monitoring box (5) and the liquid level box (6).

3. The liquid level measurement and control device for use in a nuclear industry environment as claimed in claim 1 or 2, characterized in that: Shielding plates are provided on the outside of the continuous liquid level monitoring module (1) and the alarm module (2).

4. The liquid level measurement and control device for use in a nuclear industry environment as claimed in claim 2, characterized in that: The monitoring box (5) is provided with a grounding bolt (15).

5. The liquid level measurement and control device for use in a nuclear industry environment as claimed in claim 2, characterized in that: The lower part of the monitoring box (5) is provided with a first flange (9), and the upper part of the liquid level box (6) is provided with a second flange (10), and the first flange (9) and the second flange (10) are butt-jointed via an insulating pad (11); a sealing groove is provided on the first flange (9) and / or the second flange (10) and / or the insulating pad (11), and a first sealing ring (12) is provided in the sealing groove.

6. The liquid level measurement and control device for use in a nuclear industry environment as claimed in claim 5, characterized in that: A sealing bracket (13) is provided on the upper part of the liquid level box (6), and the sealing bracket (13) is fixed below the first flange (9) or the second flange (10). A second sealing ring (14) is provided inside the sealing bracket (13), and the support rod (7) passes through the second sealing ring (14).

7. A liquid level measurement and control method for use in a nuclear industry environment, using the liquid level measurement and control device for use in a nuclear industry environment as claimed in any one of claims 1 to 6, characterized in that: The method comprises a detection procedure A, wherein the detection procedure A comprises the following steps: Step A1, calibrating the liquid level measurement and control device; Step A2, measuring the liquid level value; Step A3: Liquid level high and low value alarm.

8. The liquid level measurement and control method for use in a nuclear industry environment as claimed in claim 7, characterized in that: The step A1 comprises the following steps: A11. Determination of analog quantity: between the high liquid level Llow and the low liquid level Lhigh, read a liquid level value L every time the liquid level drops by ΔL until the low liquid level Llow, read a total of N liquid level values, calculate the difference with the corresponding actual liquid level value, and become the positive stroke error; similarly, measure the error again from the low liquid level Llow to the high liquid level Lhigh, and become the reverse stroke error; A12. Determination of switch quantity: The two liquid point locations L1 and L2 are used as the alarm values ​​of the high and low liquid levels, respectively. When the oil level is lower than the lower limit L1, that is, when the magnet reaches the position of the lower limit alarm switch module downward, the upper limit switch is actuated, and the normally open and normally closed contacts are switched, that is, the high alarm oil level switch signal is transmitted remotely from the interface socket (16); when the oil level is lower than the lower limit L2, that is, when the magnet reaches the position of the lower limit alarm switch module downward, the lower limit switch is actuated, and the normally open and normally closed contacts are switched, that is, the low alarm oil level switch signal is transmitted remotely from the interface socket (16).

9. The liquid level measurement and control method for use in a nuclear industry environment as claimed in claim 7, characterized in that: The step A2 comprises the following steps: after the liquid level measurement and control device is debugged accurately, the main device starts to add the measuring medium until the target liquid level value is reached; as the liquid level inside the liquid level box (6) gradually rises, the float (4) also rises accordingly and drives the support rod (7) and the permanent magnet (8) at the upper end to continue to rise; during the continuous rise process, the permanent magnet (8) continuously triggers the surrounding reed switches to switch from cut-off to conduction, thereby continuously transmitting the liquid level information; when the liquid level reaches the target value, the float (4) stops rising, and the permanent magnet (8) at the upper end of the support rod (7) also stops around a certain reed switch, and the reed switch becomes the last conducted reed switch, and the output analog signal stabilizes; when the liquid level drops, the float (4) also drops accordingly and drives the movable rod and the permanent magnet (8) to drop synchronously, and the continuous drop of the permanent magnet (8) drives a series of reed switches to achieve cut-off and conduction, thereby outputting a voltage analog signal.

10. The liquid level measurement and control method for use in a nuclear industry environment as claimed in claim 7, characterized in that: The step A3 comprises the following steps: When the liquid level reaches the maximum value, the permanent magnet (8) will trigger the micro switch at the highest position to conduct, thereby outputting a high voltage analog signal and simultaneously sending out a high oil level alarm signal; when the liquid level reaches the minimum value, the permanent magnet (8) will trigger the micro switch at the lowest position to conduct, thereby outputting a low voltage analog signal and simultaneously sending out a low oil level alarm signal.

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