Online monitoring and fault diagnosis system for electric gate valve

Abstract

The utility model discloses an on-line monitoring and fault diagnosis system for an electric gate valve, which relates to the technical field of valve monitoring, and comprises a valve rod, an electric actuator, a fault diagnosis module, a fault diagnosis module, a fault diagnosis module and an on-line monitoring and fault diagnosis module, and is characterized in that one end of the valve rod is fixedly connected with a flashboard of the electric gate valve; the stay wire type displacement sensor is arranged on a first bracket of the electric gate valve; a stay wire of the stay wire type displacement sensor is fixed on the transverse guide rod; the transverse guide rod is fixed on the valve rod; the at least one fiber grating sensor is arranged on the valve rod; the opening limit switch sensor is arranged on a part, close to the electric actuating mechanism, of a second bracket of the electric gate valve; the off-position limiting switch sensor is arranged at the part, close to the flashboard, of the second bracket; the current clamp is clamped at a power supply output end of a motor for driving the electric actuating mechanism; the current clamp is used for collecting working current of the motor; the industrial control box comprises a signal acquisition card and an optical fiber demodulator; the industrial control box is used for receiving sensor signals and working current of the motor.

Description

Technical Field

[0001] The utility model relates to the technical field of valve monitoring, in particular to an online monitoring and fault diagnosis system for an electric gate valve. Background Art

[0002] In the chemical industry, nuclear power and other industries, volatile, flammable, explosive and toxic gases and liquids are mostly transmitted through pipelines, which inevitably require valve control. The traditional on-site control method of valves makes it difficult to detect valve leakage in time. As a key component in the pipeline system, improving the intelligence level of valves is a hot research issue in the chemical industry.

[0003] The reliability of valve operation is crucial to the stable operation of process industrial systems. According to statistics, the annual maintenance cost of valves in a nuclear power plant with two million-kilowatt units is as high as hundreds of millions of yuan, accounting for nearly 50% of the total maintenance cost of the power plant. It is difficult for valve manufacturers to give the most reasonable preventive maintenance cycle based on the specific use of each valve. Valve manufacturers usually recommend that users perform preventive maintenance on valves every 2-3 years, but this is likely to lead to untimely or excessive maintenance of valves, resulting in a double waste of time and money for users. Existing valves are all installed on pipelines. Due to the high cost of valve disassembly, it is difficult to judge the faults encountered by the valves, which makes the maintenance of valves extremely complicated and difficult to follow up. There are problems such as high difficulty for users to use and high maintenance costs.

[0004] Therefore, it is of great significance to introduce online diagnostic technology to monitor various valve parameters, identify the operating status of valves, accurately and timely identify the initiation and evolution of key valve faults during operation, and accurately formulate preventive maintenance plans for each valve to ensure the safe operation of the process system. In the prior art, utility model patents [CN113609787A] and [CN115392313A] disclose a method for diagnosing electric valve faults based on support vector machines. This method is suitable for electric valves of a single structure and specification, and the diagnostic method has insufficient generalization ability. Utility model patent [CN106340334A] proposes a method for diagnosing nuclear power plant steam turbine valve faults and its auxiliary diagnosis method and test device, but the valve is only a solenoid valve. Utility model patent [CN110454610A] proposes a method for monitoring the valve position status of a manual valve in a chemical plant, but it is limited to the valve position detection of a manual valve. The utility model patent [CN114910265A] proposes a fault diagnosis method and device for a vehicle thermal management system valve, but the method determines the valve fault by measuring whether the temperature difference exceeds the threshold value, which is not applicable to valves that transport a large amount of normal temperature medium. The utility model patent [CN0307389A] proposes a fault diagnosis method for a steam turbine hydraulic valve based on state feedback, which detects abnormalities in the operation state of the valve stem, valve stem bushing, and spring through feedback of the oil motor force and valve stem travel curve, but this utility model is limited to fault diagnosis of steam turbine hydraulic valves. At present, there is no universal online monitoring and fault diagnosis system for electric gate valves.

[0005] Therefore, it is urgent to develop an online monitoring and fault diagnosis system for electric gate valves of different specifications, types and conveying media. Utility Model Content

[0006] In view of this, an embodiment of the utility model provides an online monitoring and fault diagnosis system for electric gate valves to solve the problem in the prior art that electric gate valves are inconvenient to repair and maintain due to excessive disassembly costs.

[0007] Another object of the present invention is to provide an online monitoring and fault diagnosis system for electric gate valves, which is suitable for electric gate valves of different specifications, forms and conveying media, and covers seven typical faults: valve not closing properly, jamming caused by valve stem bending and deformation, packing seal being too loose or too tight, sealing surface failure between gate plate and valve seat, valve not opening properly, transmission mechanism wear, and electric actuator motor failure. The system can monitor the state of the electric gate valve during operation online, and set characteristic values ​​corresponding to different faults. It can determine whether the relevant characteristic values ​​exceed the corresponding thresholds based on the measured data, and issue an alarm for the relevant faults, and diagnose the faults, thereby ensuring the long-term safe operation of the electric gate valve, and solving the problems of single valve types and specifications, and insufficient generalization ability of the diagnosis model in the online monitoring and fault diagnosis of valves proposed in the above-mentioned background technology.

[0008] The utility model embodiment provides an electric gate valve online monitoring and fault diagnosis system, comprising:

[0009] A valve stem, one end of which is fixedly connected to the gate of the electric gate valve, and the other end of the valve stem is connected to the electric actuator;

[0010] The pull-wire displacement sensor is arranged on the first bracket of the electric gate valve; the pull-wire of the pull-wire displacement sensor is fixed on the transverse guide rod; the transverse guide rod is fixed on the valve stem;

[0011] At least one fiber grating sensor is arranged on the valve stem; the fiber grating sensor is used to measure the thrust or pull force on the valve stem;

[0012] The open limit switch sensor is arranged on the second bracket of the electric gate valve and close to the electric actuator;

[0013] A closed position limit switch sensor is arranged on the second bracket near the gate plate;

[0014] A current clamp is clamped on the power output terminal of the motor used to drive the electric actuator; the current clamp is used to collect the working current of the motor;

[0015] The industrial control box includes a signal acquisition card and a fiber optic demodulator; the industrial control box is used to receive sensor signals and the working current of the motor.

[0016] Optionally, it also includes:

[0017] The host computer is connected to the industrial control box; the host computer is used for signal processing, analysis, storage and fault diagnosis of sensor signals and motor working current.

[0018] Optionally, the open limit switch sensor and the closed limit switch sensor adopt a rod-type rocker arm type; the pre-travel of the open limit switch sensor and the closed limit switch sensor is set to 20°; the over-travel of the open limit switch sensor and the closed limit switch sensor is set to 75°.

[0019] Optionally, the fiber grating sensor is metal packaged; the fiber grating sensor is mounted on the exposed valve stem surface between the packing seal and the lower surface of the electric actuator by metal spot welding.

[0020] Optionally, four fiber grating sensors are evenly distributed and installed along the circumference of the valve stem; and the tail fibers of the fiber grating sensors are parallel to the axial direction of the valve stem.

[0021] Beneficial effects of the embodiments of the utility model:

[0022] The utility model provides an online monitoring and fault diagnosis system for electric gate valves, which can monitor and manage the valves from beginning to end, perform fault diagnosis, improve after-sales service effects, facilitate repair and maintenance by understanding the status of the valves, thereby reducing user usage costs and improving user experience.

[0023] Through online monitoring of the valve stem push / pull force, a core valve status parameter, using a metal-encapsulated fiber grating sensor, combined with a fault diagnosis algorithm covering typical faults in electric gate valves 7, online monitoring and fault diagnosis of electric gate valves suitable for different gate valve specifications, forms and conveying media are achieved, ensuring the long-term safe operation of the electric gate valves, and solving the problems of single valve types and specifications and insufficient generalization ability of the diagnosis model in the prior art for online monitoring and fault diagnosis of valves.

[0024] The electric gate valve online monitoring and fault diagnosis system of the utility model is suitable for electric gate valves of different specifications, different forms and conveying media, covers the typical faults of electric gate valves, and has the advantages of wide application range and strong versatility. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The features and advantages of the present invention will be more clearly understood by referring to the accompanying drawings, which are schematic and should not be construed as limiting the present invention in any way. In the accompanying drawings:

[0026] Figure 1 A structural diagram of an online monitoring and fault diagnosis system for an electric gate valve in an embodiment of the utility model is shown;

[0027] Figure 2 A schematic diagram showing the installation position of a fiber grating sensor in an online monitoring and fault diagnosis system for an electric gate valve in an embodiment of the utility model is shown;

[0028] Figure 3A schematic diagram of the operation interface of the electric gate valve online monitoring and fault diagnosis system in the embodiment of the utility model is shown;

[0029] Figure 4 The graph shows the change of the rod thrust over time in the normal state and the valve state of the incomplete closing fault of the DN200 electric W-type normal temperature water gate valve in the embodiment of the utility model;

[0030] Figure 5 The diagram shows the change of the valve stem pull / thrust force over time in the normal state and the packing over-tightening fault state of the DN100 electric W-type water steam gate valve in the opening stroke in the embodiment of the utility model;

[0031] Figure 6 The diagram shows the change of the valve stem pull / thrust force over time in the normal state and the packing over-tightening fault state of the DN100 electric W-type water steam gate valve in the closing stroke in the embodiment of the utility model;

[0032] Figure 7 The diagram shows the change of the valve stem thrust over time in the normal state and the stuck fault state caused by the deformation of the valve stem in the closing stroke of the DN200 electric parallel normal temperature water gate valve in the embodiment of the utility model;

[0033] Reference numerals:

[0034] 1-host computer; 2-industrial control box; 201-first signal acquisition card; 202-fiber demodulator; 203-second signal acquisition card; 3-electric gate valve body; 31-closed limit switch sensor; 32-open limit switch sensor; 33-pull-wire displacement sensor; 34-current clamp; 35-fiber grating sensor; 36-pigtail; 4-valve stem; 5-electric actuator. DETAILED DESCRIPTION

[0035] In order to make the purpose, technical solution and advantages of the embodiment of the utility model clearer, the technical solution in the embodiment of the utility model will be clearly and completely described below in conjunction with the drawings in the embodiment of the utility model. Obviously, the described embodiment is a part of the embodiment of the utility model, not all the embodiments. Based on the embodiment of the utility model, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the utility model.

[0036] The utility model embodiment provides an electric gate valve online monitoring and fault diagnosis system, such as Figure 1As shown, it includes a host computer 1, an industrial control box 2, an electric gate valve body 3, a valve stem 4 and an electric actuator 5, wherein: one end of the valve stem 4 is fixedly connected to the gate plate of the electric gate valve, and the other end of the valve stem 4 is connected to the electric actuator 5; a pull-wire displacement sensor 33 is arranged on the first bracket of the electric gate valve; the pull wire of the pull-wire displacement sensor 33 is fixed on the transverse guide rod; the transverse guide rod is fixed on the valve stem 4; at least one fiber grating sensor 35 is arranged on the valve stem; the fiber grating sensor 35 is used to measure the thrust or tension exerted on the valve stem 4; the open limit switch sensor 32 is arranged on the second bracket of the electric gate valve near the electric actuator 5; the closed limit switch sensor 31 is arranged on the second bracket near the gate plate; the current clamp 34 is clamped on the power output end of the motor used to drive the electric actuator 5; the current clamp 34 is used to collect the working current of the motor; the industrial control box 2 includes a first signal acquisition card 201, an optical fiber demodulator 202 and a second signal acquisition card 203; the industrial control box 2 is used to receive sensor signals and the working current of the motor. The first signal acquisition card 201 and the second signal acquisition card 203 are used for collecting the transmission of digital signals and analog signals respectively.

[0037] The host computer 1 is connected to the industrial control box 2; the host computer 1 is used for processing, analyzing, storing and diagnosing faults of sensor signals and working currents of motors.

[0038] The open limit switch sensor 32 and the closed limit switch sensor 31 are of rod-type rocker type; the pre-travel of the open limit switch sensor 32 and the closed limit switch sensor 31 is set to 20°; the over-travel of the open limit switch sensor 32 and the closed limit switch sensor 31 is set to 75°.

[0039] The fiber grating sensor is metal packaged and installed on the exposed valve stem surface between the packing seal and the lower surface of the electric actuator by metal spot welding.

[0040] As an optional implementation, Figure 2 As shown, four fiber grating sensors 35 are evenly distributed and installed along the circumference of the valve stem; the tail fiber 36 of the fiber grating sensor is parallel to the axial direction of the valve stem.

[0041] In this embodiment, the arrangement and installation of the sensor: the metal-encapsulated fiber grating sensor is installed on the exposed valve stem surface between the packing seal and the lower surface of the electric actuator by on-site metal spot welding. The pull-wire displacement sensor is installed on the electric gate valve bracket, and a transverse guide rod is installed on the valve stem. The pull wire of the pull-wire displacement sensor is fixed on the guide rod to measure the valve opening height. Two limit switch sensors are installed on the bracket of the electric gate valve body to determine whether the valve is opened and closed in place. The current clamp is clamped on a live wire in the motor cable connected to the electric gate valve actuator to measure the current of the motor in real time when it is working.

[0042] Sensor data transmission and storage: The metal-encapsulated fiber Bragg grating sensor is connected to the fiber demodulator in the industrial control box through optical fiber to collect spectral data in real time, and transmit the spectral data to the host computer through serial communication. An acquisition card is set in the industrial control box to collect data collected by the pull-wire displacement sensor, two limit switch sensors and current clamps in real time, and transmit the data to the host computer after denoising. The host computer stores and analyzes the received data through programming.

[0043] Measurement of valve stem push / pull force: The measurement of valve stem push / pull force is based on the change of the central wavelength of the spectrum obtained by the metal encapsulated fiber grating sensor, and is calculated by eliminating the influence of valve stem temperature.

[0044] Typical fault identification and calculation method: Set the corresponding characteristic parameter calculation method and fault alarm threshold value for the typical faults of the electric gate valve in the host computer, read the stored sensor data, calculate the characteristic parameters, compare them with the threshold value, realize the alarm of typical faults, and display them on the host computer interface.

[0045] In a specific embodiment, the valve for online monitoring and fault diagnosis is an electric gate valve. The electric gate valve drives the valve stem through a motor, and the valve stem is connected to the gate plate. The gate plate moves relatively in the valve seat to realize the closing and opening of the valve, and a sensor assembly is arranged on the valve. The sensor assembly includes a metal-encapsulated Bragg fiber grating sensor installed on the surface of the metal valve stem, with a detection accuracy of not less than 0.1με, an operating temperature of -190℃~500℃, a sensor length×width×thickness of less than 2cm×2cm×2mm, and a tail connected to the optical fiber and a demodulator. The pull-wire displacement sensor installed on the bracket of the electric gate valve has a detection accuracy of not less than ±0.25%. The two limit switch sensors installed on the bracket of the electric gate valve body are of the rod-type rocker type, with a pre-travel of 20° and an over-travel of 75°. The current clamp added to a live wire in the motor cable connected to the electric gate valve actuator has a sensitivity of not less than ±1mA. The wavelength range of the optical fiber demodulator is: 1460nm~1620nm, the wavelength resolution is: 1pm, and the scanning frequency is not less than 100Hz.

[0046] The embodiment of the utility model further provides an electric gate valve online monitoring and fault diagnosis method, which adopts the electric gate valve online monitoring and fault diagnosis system in the above implementation, including:

[0047] Step S1, obtaining the working current of the motor.

[0048] In this embodiment, the data collected by the two limit switch sensors and the current clamp are transmitted to the host computer after noise removal, and the host computer stores and analyzes the received data through programming.

[0049] Step S2, obtaining the displacement signal and stress signal of the valve stem.

[0050] In this embodiment, the stress signal of the valve stem, i.e., the measurement of the push / pull force of the valve stem is based on the change of the central wavelength of the spectrum obtained by the metal-encapsulated fiber Bragg grating sensor, and the influence of the valve stem temperature is eliminated. In a specific embodiment, the value of the push / pull force of the valve stem is obtained by taking the arithmetic average of the push / pull force of the valve stem measured by four fiber Bragg grating sensors evenly distributed along the circumference of the valve stem, so as to reduce the influence of uneven axial force on the valve stem.

[0051] Step S3, obtaining characteristic parameters according to any one or more of the working current, the displacement signal and the stress signal.

[0052] Step S4, comparing the characteristic parameter with the fault alarm threshold to implement valve fault diagnosis.

[0053] Among them, the fault alarm threshold is set according to the historical data of the electric gate valve. Typical faults include valve failure to close properly, jamming caused by valve stem bending and deformation, packing seal being too loose or too tight, sealing surface failure between the gate and the valve seat, valve failure to open properly, transmission mechanism wear, and electric actuator motor failure. The host computer diagnoses the fault based on the stored sensor data and the pre-set valve fault threshold value, and automatically displays whether the valve has a fault and the type of fault on the host computer.

[0054] like Figure 3 As shown, in this embodiment, the corresponding characteristic parameter calculation method and fault alarm threshold value are set in the host computer for the typical faults of the electric gate valve, the stored sensor data is read, the characteristic parameters are calculated, and compared with the fault alarm threshold value to realize the alarm of the typical fault and display it on the host computer interface.

[0055] As an optional implementation, it also includes:

[0056] When the working current increases by more than 1A within 20ms, the displacement signal and stress signal data start to be transmitted and stored to the host computer;

[0057] When the limit switch sensor value jumps, the transmission and storage of displacement signal and stress signal data to the host computer are stopped.

[0058] In this embodiment, the host computer data acquisition and storage start and stop are triggered by the current change collected by the current clamp.

[0059] As an optional implementation, collecting the stress signal of the valve stem includes:

[0060] Acquire a first spectrum center wavelength of the valve stem surface at a first temperature;

[0061] Obtain the second spectrum center wavelength of the valve stem surface when the electric gate valve stops running, discharges the medium, completely loosens the packing seal, controls the valve opening to 50%, and is at the second temperature;

[0062] According to the first spectrum center wavelength, the second spectrum center wavelength, the first temperature, the second temperature, the temperature coefficient and the sensitivity of the fiber grating sensor, the thrust or pull of the valve stem is obtained according to Hooke's law.

[0063] In this embodiment, the measurement of the valve stem push / pull force is based on the change of the central wavelength of the spectrum obtained by the metal encapsulated fiber grating sensor, and the influence of the valve stem temperature is eliminated and calculated:

[0064]

[0065] Among them, Δε is the strain when the valve stem surface temperature is T when the electric gate valve is running, and the unit is με. ε It is the central wavelength of the spectrum measured by the grating fiber optic sensor when the valve stem surface temperature is T when the electric gate valve is running, in nm. It is the central wavelength of the spectrum measured by the grating fiber optic sensor when the electric gate valve stops running and the medium is discharged, the packing seal is completely loosened, the valve opening is controlled at 50%, and the valve stem surface temperature is T0. The unit is nm. is the temperature coefficient of the fiber Bragg grating sensor, in pm / ℃. is the sensitivity of the fiber Bragg grating sensor, in units of pm / με.

[0066] Based on the real-time measurement of λ by a fiber optic light dispersion sensor encapsulated by a metal package ε , calculate Δε according to formula (1), and then according to Hooke's law, the push / pull force of the valve stem can be obtained in real time.

[0067] As an optional implementation, the characteristic parameter is compared with the fault alarm threshold to implement valve fault diagnosis, including:

[0068] If the signal of the closing limit switch sensor does not jump after the valve is closed, it is judged that the valve is not closed properly.

[0069] If the valve is closed, the final stem thrust F C The absolute value is less than the minimum value of the valve stem thrust F when the gate is normally closed. min , it is judged that the valve is not closed properly.

[0070] If any one of the above two conditions is met, it can be determined that the valve is not fully closed.

[0071] If the maximum deviation of the measured absolute value of the valve stem thrust is greater than the rated friction force F of the packing during the process of the valve opening height changing from 80% to 50%, packIf the valve stem is bent and deformed, it is judged that the jamming failure has occurred.

[0072] Packing rated friction F pack The calculation is based on formula (2):

[0073] F pack =12×π×D×(D+15)×10 -2 (2)

[0074] Where D is the valve stem diameter in mm.

[0075] The average of the absolute values ​​of the measured valve stem thrust at 50% of the opening stroke and the valve stem thrust at 50% of the closing stroke is taken as the measured friction force F of the packing seal; if the measured friction force F is less than the rated friction force F of the packing, pack If the value is 60%, it is judged that the packing is too loose.

[0076] If the measured friction force is greater than the rated friction force of the packing, it is judged that the packing is too tight.

[0077] The sealing surface friction coefficient is calculated by the sealing surface mid-diameter of the valve seat, the upstream and downstream pressure difference of the gate valve, the valve stem pull-out force and the rated friction force of the packing; if the sealing surface friction coefficient is greater than 0.5, it is judged that the sealing surface is faulty.

[0078] Sealing surface failures mainly include sealing surface wear and mismatch, which will cause the friction resistance of the sealing surface to increase. The degree of failure is characterized by its friction coefficient μ1. The calculation method of μ1 is shown in formula (3):

[0079]

[0080] Among them, D s is the median diameter of the valve seat sealing surface, in m. Δp is the pressure difference between the upstream and downstream of the gate valve, in Pa. R The valve stem pull-out force is the maximum valve stem pull force between 0-10% of the valve opening, in N. pack Calculate according to formula (2).

[0081] The actual valve closing stroke time is obtained through the sudden increase of valve motor current and the jump of open limit switch sensor signal. If the actual valve closing stroke time exceeds the theoretical time by 0.5 seconds, it is judged that the valve cannot be opened in place. Among them, the theoretical time is calculated based on the gear system transmission ratio, valve rated stroke, trapezoidal thread pitch, valve trapezoidal thread head number and motor output speed.

[0082] The actual valve closing stroke time t0 is obtained through the sudden increase of valve motor current and the jump of the open limit switch sensor signal. If t0>t+0.5s, the valve is judged to be an incomplete opening fault. The theoretical time t is calculated as shown in formula (4):

[0083]

[0084] Wherein: i is the gear ratio; L is the rated travel of the valve, in mm; p is the trapezoidal thread pitch, in mm; x is the number of trapezoidal thread starts of the valve; N is the output speed of the motor, in r / min.

[0085] If the valve safety function is in the closed position and the open limit switch sensor signal does not jump when the valve is fully opened, it is judged that the valve cannot be opened to the full position.

[0086] The wear degree of the transmission mechanism is evaluated according to the comprehensive friction coefficient; if the comprehensive friction coefficient is greater than 0.15, the transmission mechanism is judged to be a wear fault; wherein, the comprehensive friction coefficient is back-calculated through the valve stem thrust;

[0087] The wear of the transmission mechanism is evaluated by the comprehensive friction coefficient μ2, and μ2 needs to be back-calculated by monitoring the valve stem thrust, as follows:

[0088] The valve stem thread transmission coefficient is calculated according to formula (5):

[0089]

[0090] Among them, C ma The torque setting for valve closing provided by gate valve manufacturers, in N·m. C The final valve stem thrust after the valve is closed is provided to gate valve manufacturers in N. R is the remote control efficiency, and its value is 0.85.

[0091] μ2 is calculated according to formula (6):

[0092]

[0093] Wherein, d is the middle diameter of the trapezoidal thread, in m; α is half of the trapezoidal thread profile angle, for metric trapezoidal thread, α = 15°, for ACME standard trapezoidal thread, α = 14.5°. is the thread lead angle. When μ2 exceeds 0.15, it can be determined that the valve has a transmission mechanism wear failure.

[0094] Monitor the motor starting current. If the motor starting current exceeds three times the rated current, it is judged that the motor starting current is too large.

[0095] If the motor is still running as measured by the current clamp after the open limit switch sensor signal or the closed limit switch sensor signal jumps, it is determined that the controller is faulty.

[0096] In a specific embodiment, the valve of the monitoring structure is a W-type electric gate valve as an example, the nominal diameter is DN200, the medium used is normal temperature water, the pressure before the valve is 3MPa (gauge pressure), the pressure after the valve is atmospheric pressure, and the minimum value of the valve stem thrust when the valve is closed is F min =-120kN.

[0097] Based on the above electric gate valve online monitoring and fault diagnosis system, the operation of DN150 electric W-type normal temperature water gate valve is monitored online. The changes of valve stem thrust over time in the normal state and the failure of closing in place during the closing stroke are shown as follows: Figure 4 As shown. Under normal conditions, the valve stem thrust F of the W-type electric gate valve when the valve is closed C The absolute value of the thrust is -135kN, and the absolute value of the thrust is greater than the minimum value of the valve stem thrust when the valve is closed F min =-120kN, and when the valve fails to close, although the signal of the closing limit sensor jumps, the valve stem thrust F C The absolute value of the thrust is -45kN, and the absolute value of the thrust is less than the minimum value of the valve stem thrust when the valve is closed F min =-120kN, the valve cannot achieve effective sealing and is judged as a failure to close according to the diagnostic method for failure to close.

[0098] Online monitoring of the operation of the DN100 electric W-type steam gate valve, the change of the valve stem push / pull force over time in the normal state and the packing over-tightening fault state during the opening and closing strokes. Figure 5 and Figure 6 The average absolute value of the measured valve stem thrust at 50% of the opening stroke and 50% of the closing stroke is 0.5kN, which is greater than F pack =401N, it is judged as a packing over-tightening failure.

[0099] The change of valve stem thrust over time in the normal state and the jamming fault state caused by valve stem deformation during the closing stroke is shown in the figure below. Figure 7 As shown in the figure, when the valve opening height changes from 80% to 50%, the valve stem thrust changes from -72.4kN to -40.7kN, and the maximum deviation of the absolute value is 31.7kN, which is greater than the rated friction force of the packing by 10×F pack =9.02kN, it is determined to be a jamming fault caused by valve stem deformation.

[0100] The specifications of the electric gate valves in the above embodiments are DN200 and DN150, the forms of the electric gate valves are W-type and parallel type, the conveying media are water at room temperature and water vapor, and the types of faults include three types of jamming caused by failure to open properly, over-tight packing, and valve stem bending and deformation. This fully demonstrates that the electric gate valve online monitoring and fault diagnosis system described in the utility model is suitable for electric gate valves of different specifications, different forms and conveying media, covers typical faults of electric gate valves, and has the advantages of wide applicability and strong versatility.

[0101] The utility model provides an online monitoring and fault diagnosis system for electric gate valves. Through online monitoring of the valve stem push / pull force, a core valve status parameter, based on a metal-encapsulated fiber grating sensor, combined with a fault diagnosis algorithm covering seven typical faults of electric gate valves, online monitoring and fault diagnosis of electric gate valves suitable for different gate valve specifications, forms and conveying media are realized, solving the problems of single valve type and specification, insufficient generalization ability of the diagnosis model, etc. in the prior art for online monitoring and fault diagnosis of valves, which is of great significance for ensuring the long-term safe operation of electric gate valves.

[0102] The embodiment of the utility model provides an application for online monitoring and fault diagnosis of electric gate valves, which can monitor and manage the valve from beginning to end, perform fault diagnosis, improve after-sales service effects, facilitate repair and maintenance by understanding the status of the valve, thereby reducing the user's usage cost and improving the user's usage experience.

[0103] Although the embodiments of the present invention are described in conjunction with the accompanying drawings, those skilled in the art may make various modifications and variations without departing from the spirit and scope of the present invention, and such modifications and variations are all within the scope defined by the appended claims.

Claims

1. An online monitoring and fault diagnosis system for electric gate valves, characterized in that: include: A valve stem, one end of which is fixedly connected to the gate plate of the electric gate valve, and the other end of the valve stem is connected to the electric actuator; A wire-type displacement sensor is arranged on the first bracket of the electric gate valve; the wire of the wire-type displacement sensor is fixed on a transverse guide rod; the transverse guide rod is fixed on the valve stem; At least one fiber grating sensor is arranged on the valve stem; the fiber grating sensor is used to measure the thrust or tension applied to the valve stem; An open limit switch sensor is arranged on the second bracket of the electric gate valve near the electric actuator; A closed position limit switch sensor is arranged on the second bracket near the gate plate; A current clamp, clamped on the power output terminal of the motor used to drive the electric actuator; The current clamp is used to collect the working current of the motor; Industrial control box, including signal acquisition card and fiber optic demodulator; The industrial control box is used to receive sensor signals and the working current of the motor.

2. The electric gate valve online monitoring and fault diagnosis system according to claim 1 is characterized in that: Also includes: A host computer is connected to the industrial control box; the host computer is used for processing, analyzing, storing and diagnosing faults of the sensor signals and the working current of the motor.

3. The electric gate valve online monitoring and fault diagnosis system according to claim 1 is characterized in that: The open limit switch sensor and the closed limit switch sensor are of rod-type rocker type; the pre-travel of the open limit switch sensor and the closed limit switch sensor is set to 20°; the over-travel of the open limit switch sensor and the closed limit switch sensor is set to 75°.

4. The electric gate valve online monitoring and fault diagnosis system according to claim 3 is characterized in that: The fiber grating sensor is metal packaged; the fiber grating sensor is installed on the exposed valve stem surface between the packing seal and the lower surface of the electric actuator by metal spot welding.

5. The electric gate valve online monitoring and fault diagnosis system according to claim 4 is characterized in that: The four fiber grating sensors are evenly distributed and installed along the circumference of the valve stem; the tail fibers of the fiber grating sensors are parallel to the axial direction of the valve stem.

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