Spring breakage identification in the preload drive of the regulating valve

Abstract

This invention relates to a method for identifying spring breakage in a preloaded drive mechanism of a control valve. The method is based on the significant reduction in the force required to achieve a specific valve spool position after spring breakage or failure. In this way, spring breakage within the preloaded drive mechanism can be reliably identified using a sensor system already present within the control valve, precisely without interfering with or interrupting continuous operation.

Description

Technical Field

[0001] This invention relates to a method for identifying spring breakage in the preload drive of a control valve. Control valves can be designed as rotary valves or stroke valves. They are commonly used in process technology equipment or engineering equipment to control or regulate processes or process media. Other application examples are solar thermal equipment or local or long-range heating systems. In addition to control and regulation applications, control valves are also used as safety valves to protect equipment or processes.

[0002] Control valves generally have an actuation device or actuator and a valve spool for controlling or regulating the movement of a process or process medium. The actuation device or actuator acts on the valve spool's drive rod. It is mostly located outside the fluid-sealed valve housing. The valve spool's drive rod is correspondingly guided through the fluid-sealed housing, where the seal (e.g., the seal) seals the drive rod externally relative to the housing.

[0003] Wear typically occurs between the actuator rod and the seal. This wear can be caused by deposits, abrasion, corrosion, or other seals in the actuator. Incorrect installation of control valve components or the control valve itself can also lead to wear on control valve components and unwanted loads.

[0004] Fluid-driven devices are generally used as drive mechanisms to move a drive rod. In many cases, pneumatic drives are employed, where a chamber is filled with or emptied of compressed air to move the drive rod.

[0005] In the field of safety-related valves or safety valves, pneumatic actuation devices are commonly used, which are preloaded on one side by a spring force. Compressed air always acts in the opposite direction to the spring force of the preloaded actuation device. When the actuation device is depressurized, i.e., when compressed air escapes from the actuation device's chamber, the preloaded actuation device moves independently to a safe position or safety position by the spring force. This occurs, for example, when a current-pressure (l / P) transducer or solenoid valve is no longer energized.

[0006] In the case of a safety valve, the valve is normally open during operation and automatically closes in the event of a fault (such as a power outage). If the actuator is now depressurized, the valve begins to close once the spring force has overcome any static friction and dislodged the valve core. The safe position can also be either open when power is off (actuator depressurized) or closed when power is on (actuator pressurized).

[0007] The position or stroke of the valve spool is generally described in relation to the closed position. If the position or stroke of the valve spool is described as 0, the valve spool is in the closed position. If the position or stroke of the valve spool is described as 100%, the valve spool is in the position opposite to the open position. This position corresponds to a fully open valve.

[0008] In many cases, the spring forces of one or more springs in a spring group are applied. These springs are typically designed as metal coil springs (especially steel) and arranged in parallel, so that the spring constants or spring forces of some springs are added together. Air springs or elastic (rubber) pads can also be used for preload.

[0009] A broken or damaged spring in the preloaded actuator can cause safety valve failure or at least a longer response time. In many safety-critical applications, this is unacceptable and tantamount to valve failure. Additionally, uneven loading of the actuator or valve spool can occur, reducing the actuator's thrust and potentially limiting the valve's operating range. Reduced seat load in the closed position and resulting leakage can also be a consequence. Furthermore, unevenly loaded components experience accelerated wear. Therefore, a broken or damaged spring in many cases foreshadows the impending failure of other springs or components in the control valve.

[0010] Generally, spring breakage or damage can be attributed to a range of factors such as corrosion or fatigue. Structural failure of other components of the actuator or control valve, as well as improper installation, can also cause spring breakage or failure.

[0011] A spring does not necessarily break into more than two parts when it breaks. It can also undergo plastic deformation or bending. The welds securing the spring can crack, causing slippage or tilting of the spring. In the case of air springs or rubber springs, the diaphragm may rupture or burst. Therefore, spring breakage is generally referred to when the spring constant changes in a way that the spring loses its function or effect, or contributes little or no to the preload of the drive mechanism. Existing technology

[0012] Various methods have been found in the prior art for identifying spring breakage in the preloaded actuator of a control valve. For example, patent document US4,976,144A proposes a benchtop fault diagnosis method. For this purpose, the valve spool is moved within the test operating range, and stroke-pressure curves are recorded when the actuator is pressurized and when it is depressurized. The two curves differ due to wear. They define a region known as the valve profile. The slope of the stroke-pressure curve is a measure of the spring constant used for the spring assembly. Spring failure is identified based on changes in this or these slopes.

[0013] Similarly, the time curves of the operating parameters during opening and closing, plotted in DE102015225999A1, allow for the deduction of the force required for opening and closing. The breakage of a spring is thus identified based on the change in the force required to open and close the valve.

[0014] To avoid test runs used to identify spring breakage, publication WO2004 / 074947A1 proposes calculating the spring constant based on the stroke-pressure curve recorded in a continuous seat. For this purpose, a test is performed where the valve spool is moved a short distance and then returned to its initial position. Spring breakage is then identified based on the slope of the stroke-pressure curve recorded at this point.

[0015] Utility model patent document DE29612346U1 discloses an alternative starting method. Here, although the valve core also partially moves, the spring constant is not determined within the slope range of the corresponding stroke-pressure curve, but rather within the time period elapsed. If a spring breaks, a small amount of compressed air must be supplied to or vented from the drive unit to move the valve core. Correspondingly, the reaction time of the drive component is shortened, which is used to identify spring breakage or failure.

[0016] In the published document WO2009 / 111101A1, the slope of the valve core's stroke-pressure curve and response time is also used to determine the predetermined stroke variation for spring constant variation in order to identify spring breakage or failure (see also Ralph Hebrich's "Control Valve Breakage" in Chapter 3.5 "Valve Failure Diagnosis").

[0017] Known methods rely on identifying changes in the slope of the valve spool's stroke-pressure curve or response time. The valve spool must move within a certain stroke range, where the corresponding stroke Δ must exceed a certain range to allow for safe calculation of the slope or response time. This is not always feasible in static processes and may lead to undesirable process failures. Furthermore, there is a delay after spring breakage until it is detected. However, this may be too late in many cases. Additionally, if the process conditions or process medium conditions change during the method's implementation, this directly impacts the analysis, resulting in spring breakage not being identified or being incorrectly identified. Inconsistencies or irregularities in the stroke-pressure characteristic curve, such as those caused by indentations or irregularities in the seal, can also lead to misreading and incorrect writing of spring breakage. Summary of the Invention

[0018] The objective of this invention is to provide a method for more reliably and easily identifying the breakage of a spring in the preload drive of a regulating valve, specifically without interfering with or needing to interrupt continuous operation.

[0019] Solution

[0020] This task is accomplished through the subject matter of the independent claims. Favorable improvements to the subject matter of the independent claims are characterized in the dependent claims. The wording of all claims is hereby incorporated into this specification.

[0021] The use of the singular should not preclude the plural, and vice versa, unless otherwise stated.

[0022] The following describes some method steps in detail. These steps do not necessarily have to be performed in the specified order, and the proposed method may also have other steps not mentioned. To accomplish this task, a method is proposed for identifying the breakage of a spring in the preload drive of a control valve, wherein the control valve is designated as part of a device in which a process operates with a process medium. The control valve herein has the following components:

[0023] - A valve core used to influence the process media and / or process operating on this equipment.

[0024] - A pneumatically driven device, configured to position a valve spool to influence the process medium and / or process, wherein the pneumatically driven device has a spring preloaded on the drive device.

[0025] - A position sensor used to measure the actual position of the valve core.

[0026] - A pressure sensor used to measure the actual pressure inside a pneumatic drive unit.

[0027] The method includes the following steps:

[0028] 1. Define or set a valve legend that allows each valve spool's actual position to be assigned a range of pressures achievable during the operation of a control valve with an undamaged spring.

[0029] 2. Measure the actual position of the valve core at a given moment using a position sensor.

[0030] 3. The actual pressure inside the pneumatic drive device is measured at this moment using a pressure sensor.

[0031] 4. Determine if the spring is broken, wherein if the spring is found to be broken, the actual pressure being measured is less than the pressure assigned to the actual position of the valve core by means of a valve diagram, and / or the actual position being measured is greater than the position assigned to the actual pressure of the valve core being measured by means of a valve diagram.

[0032] 5. If it is determined that the spring is broken, issue a notification.

[0033] Spring breakage or failure occurs almost instantaneously in many operating conditions; that is, the preload of the failed spring decreases within a very short period compared to the typical timescale for valve adjustment and / or achieving force balance. Due to the direct line of action between the spring, actuator, or drive, and the valve spool, the characteristics of the actuator or drive also change almost instantaneously. After spring breakage or failure, the pressure required to achieve a certain valve spool position decreases significantly over a long period. The proposed method utilizes systematically low pressure to identify spring breakage or failure using a sensor system present for valve spool position adjustment, precisely without interrupting continuous operation or being interfered with by additional measures. Immediately following spring breakage or failure, there is generally no balance between the forces acting on the valve spool, including the force applied to the valve spool by compressed air in the pneumatic actuator and the spring force that moves the valve spool to a safe position when the actuator is depressurized. In such an unbalanced state, the correlation between the actual valve spool position and the actual pressure of the pneumatic actuator depends on many factors that are insignificant in the balanced state. However, these factors are either very difficult to obtain or completely unobtainable. Therefore, methods based on determining the spring constant (or directly related parameters, such as the reaction time for moving the valve core from a first position to a second position) using the actual position of the valve core and the actual pressure of the pneumatic actuation device are unavailable or can only identify a spring breakage or failure when a force equilibrium is achieved. This may be too late. The proposed method can identify spring breakage much earlier and more reliably in non-equilibrium conditions than methods described using existing techniques.

[0034] This method is based on measurements of the actual valve spool position and the actual pressure of the pneumatic actuator at a given moment. Further measurements at other moments or at different moments are not necessary. Delays and / or disturbances resulting from further measurements, such as those caused by changes in process conditions or process media conditions, can be mitigated or even avoided in this way.

[0035] The control valve may include a position adjuster that adjusts the valve spool position using a pneumatic actuation device and a position sensor. The position adjuster may be configured to implement the proposed method as an additional fault diagnosis function during normal operation. It may also be configured to generate data indicating spring breakage or failure upon identification of such breakage or failure. This data may be stored in the position adjuster or transmitted to the device control console. In other embodiments, the data may be further processed in a fault diagnosis display using a suitable display device on the position adjuster and / or control valve and / or control console.

[0036] Valve symbols can be determined or set using an input mask on the position controller, control valve, or control panel. This can be done by explicitly setting the pressure range corresponding to the valve spool position, and / or by determining a calibration cycle for the measured pressure range. The relevant data can be stored in memory and recalled to execute the method. The calibration cycle can, for example, begin before or at the time of installation of the position controller or control valve.

[0037] In this way, the valve diagrams used can be individually adapted to the specific installation conditions of the control valve and the springs used for preload. Additionally, tolerances can be increased for the valve diagrams to adapt to the current application and avoid false alarms.

[0038] Valve diagrams can also be updated at regular intervals. Updates can be performed during continuous operation or within maintenance cycles. This allows the valve, valve core, actuator, and especially seal wear and contamination to be taken into account in the proposed method. The method is therefore designed to be more reliable.

[0039] A fracture diagram can be derived from the valve diagram, which allows for the assignment of a range of pressures achievable at the point of spring breakage to each actual valve spool position. Here, spring breakage can be determined such that the measured actual pressure corresponds to a pressure that, using the fracture diagram, can be assigned to the measured actual valve spool position.

[0040] In a simple case, the fracture diagram includes a pressure that is less than the positive pressure that can be correspondingly assigned to the actual position of the valve core using each valve diagram.

[0041] The fracture diagram can also be calculated by multiplying the valve diagram by a coefficient that simulates spring breakage or failure. If the drive unit is preloaded, for example, with n identical or at least similar springs, the valve diagram can be multiplied by a coefficient of (n-1) / n. Possible intersections with the valve diagram can be subtracted from the fracture diagram. Additionally, the fracture diagram, along with the valve diagram, can have a tolerance range to avoid false alarms.

[0042] The fracture pattern can also be calculated from the average value. For each actual position of the valve spool, an average pressure P can be calculated, for example, which can be correspondingly assigned to the actual position of the valve spool using the valve pattern. The corresponding pressure range of the fracture pattern can then be described, for example, by the following intervals: [((n-1) / n)P(1-δ)-ε, ((n-1) / n)P(1+δ)+ε], where δ is the scale and ε is the constant width of the pattern. In this way, measurement errors proportional to the measured pressure and wear, which typically contributes a constant contribution to the valve pattern, can be simulated and incorporated into the method. The fracture pattern can also be supplemented with other correction factors to account for the interference effects on the valve spool, actuator, or sensor. P can also represent the arithmetic mean of the pressure or be calculated using other weights of the pressure.

[0043] By setting fracture patterns, the reliability of this method can be improved and it can be adapted to current applications. If the preload mechanism of the drive unit includes multiple springs that are different or act at different points on the drive unit, the fracture patterns can be set individually for each spring. The sum of the fracture patterns can include discrete regions. In this way, not only can the fracture or failure of the carbon fiber be identified, but it may also be possible to indicate which spring broke and / or in which region of the drive unit the spring broke.

[0044] The fracture diagram can include correction factors. Such factors can be used to account for, for example, changes or errors in determining the cone surface, the diaphragm surface of the drive unit, or errors in measuring the pressure or position of the valve core.

[0045] Spring breakage or failure, under many operating conditions, triggers a spontaneous movement of the valve spool against the spring force used to preload the drive mechanism. This movement has characterizing properties that can be used to identify spring breakage or failure within the scope of the proposed method. For this purpose, the actual position of the valve spool and the actual pressure within the pneumatic drive mechanism can be measured and recorded at various times. Spring breakage can be determined here by analyzing the recorded actual position and actual pressure to determine whether a spontaneous movement of the valve spool against the spring force occurs, where this spontaneous movement characterizes the movement of the valve spool immediately following spring breakage.

[0046] In this way, information already obtained during valve spool position adjustment can be utilized. The reliability of this method can also be further improved.

[0047] The spontaneous motion of the valve core against the spring force can be identified within a method using the time elapsed during the spontaneous motion, the distance traveled during the spontaneous motion, the maximum deviation between the actual and theoretical positions of the valve core, the actual and / or theoretical positions, the velocity and / or acceleration during the spontaneous motion, and the area swept within a predetermined range of stroke-pressure curves and / or position and pressure values ​​during the spontaneous motion. This predetermined range includes the valve core motion change process obtained by measurement and / or calculation upon spring breakage. The swept area can be formed with respect to the theoretical position of the valve core.

[0048] Spontaneous motion is decisively influenced by the type and method of valve adjustment. In many cases, a position regulator is used. However, the function of the position regulator can also be performed by a part of the equipment control panel. The compressed air supply source of the drive unit, especially the pressure of the compressed air used to supply it, has another decisive influence.

[0049] The regulator resists spontaneous movement of the valve spool after the spring breaks or fails. Without the regulator, the valve spool would move a considerable distance after the spring breaks. If such valve spool movement is detected by a position sensor, the actuator is typically depressurized to allow the valve spool to return to the position set by the regulator as its theoretical position.

[0050] This method allows for the consideration of various factors and the resulting valve spool movement time scale after spring breakage or failure. It can also be adapted to the installation conditions of the actuator and valve spool within the control valve, and the installation conditions of the control valve within the equipment. Changes caused by wear or deposits, for example, can also be taken into account.

[0051] Pattern recognition and / or machine learning methods can also be used to identify the spontaneous movement of the valve core after the spring breaks or fails.

[0052] If the drive unit is preloaded with different springs, the method can be used to identify which spring has broken or failed. This can be achieved, for example, by means of the motion variation process for each spring.

[0053] When investigating spring breakage, the actual operating conditions and / or dominant parameters of the control valve can be considered. In this way, valve spool movement, such as that set by the equipment control panel and temporarily changed (e.g., due to interference) or that occurs due to the current process, can be distinguished from spontaneous valve spool movement caused by spring breakage or failure. If spring breakage or failure is identified using a breakage diagram, these factors can also be included in the breakage diagram.

[0054] A control valve may have one or more sensors for measuring the pressure of the process medium. Therefore, the reaction of the process medium on the valve core and actuator can be determined, and the pressure value measured by the pressure sensor of the actuator can be corrected, for example, by the medium inflow. Thus, for example, two sensors can be used to determine the pressure drop within the control valve and the resulting force exerted by the process medium through the valve core on the actuator. In this way, fluctuations in the process medium pressure that cause the valve core to move spontaneously can be identified.

[0055] This task is also accomplished by a position adjuster, which is part of a control valve with a preload drive, wherein the control valve is designated for use in equipment sections where the process operates with process media. The control valve here has the following components:

[0056] - A valve core used to influence the process media and / or process operating on the equipment.

[0057] - A pneumatically driven device, configured to position a valve spool to influence the process medium and / or process, wherein the pneumatically driven device has a spring preloaded on the device.

[0058] - A position sensor used to measure the actual position of the valve core.

[0059] - A pressure sensor used to measure the actual pressure of a pneumatic drive unit.

[0060] The position adjuster herein includes a mechanism adapted to perform the steps of the method of the present invention.

[0061] A computer program containing instructions that cause the aforementioned position adjuster to perform the method steps of the present invention also performs this task.

[0062] This task is also accomplished via a data carrier on which the computer programs just described are stored.

[0063] Other details and features are derived from the following description of the preferred embodiments in conjunction with the figures. In this case, each feature may be implemented individually or in combination with others. Possible ways to accomplish this task are not limited to the embodiments described.

[0064] The embodiments are schematically illustrated in the figures. The same reference numerals in these figures denote the same or functionally identical components or components that correspond to each other in function, as specifically shown in:

[0065] Figure 1 A regulating valve with a pre-tightened drive mechanism is shown;

[0066] Figure 2 The regulating valve section with a pre-tightened drive mechanism is shown;

[0067] Figure 3The stroke-pressure curves with the motion trajectory are shown.

[0068] Figure 4 A portion of the stroke-pressure curve is shown;

[0069] Figure 5 Another illustration showing a portion of the stroke-pressure curve along with the motion trajectory; and

[0070] Figure 6 A process diagram of the method of the present invention is shown.

[0071] Figure 1 A "gas-locked" control valve 100 with a valve body 105 is shown. The valve body 105 includes an inlet 110, an outlet 115, a valve seat 120, and a valve core 125 with a valve cone 130. The flow of the process medium through the control valve 100 can be regulated or controlled by means of the valve cone 130 or the valve core 125. The process medium flows into the control valve 100 via the inlet 110 and exits the valve 100 via the flow port formed by the valve seat 120 and the valve cone 130 and the outlet 115. The process medium can also flow through the control valve 100 in the opposite direction.

[0072] Furthermore, the valve core 125 has a drive rod or valve stem 135, wherein the valve cone 130 is fixed to the lower end of the drive rod or valve stem 135. To close the valve 100, the valve cone 130 is moved toward the valve seat 120 by means of the valve stem 135. To open, the valve cone 130 or valve core is moved in the opposite direction. In this way, the size of the through-hole formed by the valve seat 120 and the valve cone 130 of the regulating valve 100 can be enlarged or reduced, so the flow rate of the fluid medium or process medium is controlled by the regulating valve 100.

[0073] The valve core 125 is guided through an opening 185 within the valve housing 105. The valve housing 105 has a sealing packing 180 disposed within the opening 185. The sealing packing 180 seals the valve core 125 relative to the valve housing 105.

[0074] To move the valve core 125 or valve cone 130, the regulating valve 100 includes a pneumatic actuation device 140. The pneumatic actuation device has a chamber 145 that is pressurized or depressurized to move the valve core 125. The pressure of the air in the chamber 145 is measured by a compressed air sensor 150.

[0075] The drive unit 140 is controlled by a position adjuster 155, to which a compressed air sensor 150 is integrated. The position adjuster 155 has a position sensor 160 for controlling the movement of the valve spool 125 via the drive unit 140. In the illustrated example, the position sensor 160 is designed as a magnetic sensor that detects the position of a magnet 165. The magnet 165 is fixedly coupled to the drive rod 135. The position of the magnet 165 thus indicates the position of the valve spool 125, at least within the operating range of the valve 100.

[0076] The drive unit 140 is preloaded by the spring assembly 170. In the schematic arrangement shown, the spring assembly 170 has six helical springs 175, three of which are arranged before the cutting plane and three after it. The helical springs 175 are steel springs and are arranged in parallel, so that the spring constant of the spring assembly 170 is obtained by summing the spring constants of the springs 175.

[0077] The proposed method is performed by the position adjuster 155 during the operation of valve 100. This is achieved within the scope of fault diagnosis functions performed in parallel with the adjustment of the valve spool 125 position by means of the position adjuster 155. For this purpose, the valve spool 125 position measured and recorded during the adjustment, as well as the pressure within the chamber 145 of the pneumatic actuation device 140, are recorded and analyzed. In this way, a breakage or failure of one of the springs 175 can be identified, specifically adjusting the balance between the force applied to the valve spool by the compressed air within the chamber 145 and the force applied to the valve spool 125 by the remaining or undamaged spring 175.

[0078] Figure 2 A portion of the control valve 200 is shown, its structure being almost identical to that of the control valve 100. It also includes a valve body 205, an inlet 210, an outlet 215, a valve seat 220, and a valve core 225 for opening or closing the valve 200. The valve core 225 is composed of a valve cone 230 and a valve stem or drive rod 235 and is sealed relative to the valve body 205 using sealing packing 280. The position of the valve core 225 is also adjusted by means of a position adjuster 255, for which it is driven by a drive mechanism (not shown) and a position sensor 260. The drive mechanism of the control valve 200 can be preloaded, for example, using three springs. The control valve 200 has two additional pressure sensors 290 and 295 within the valve body 205, which are connected to the position adjuster 255. The pressure sensors 290 and 295 can be used to measure the pressure of the process medium before or after passing through the valve seat 220.

[0079] The position regulator 255 implements an extension phase of the proposed method using sensors 290 and 295, where the process medium pressure within the valve housing 205 is considered. For this purpose, sensor 290 determines the process medium pressure P1 at the sensor 290 position or on the side of the valve seat 220 or valve cone 230 facing inlet 210. Correspondingly, sensor 295 determines the process medium pressure P2 at the sensor 295 position or on the side of the valve seat 220 or valve cone 230 facing outlet 215. Pressures P1 and P2 can be used to calculate or at least estimate the force exerted by the process medium on the valve cone 230, valve stem 235, or valve core 225. This force, in particular, causes valve figure displacement. This displacement generally depends on the continuous process. It is used in the extension phase of the proposed method to correct for the measured actual pressure within the pneumatic actuation mechanism of the control valve 200.

[0080] This method avoids false alarms caused by process-related forces acting on the valve core 225, which, when acting on the measured actual pressure, are similar to the force at spring breakage. With this correction, spontaneous movement of the valve core 225 caused by process medium fluctuations can also be identified and distinguished from spontaneous movement of the valve core 225 based on the breakage of one of the springs. Furthermore, the valve pattern can be dynamically adapted to the operating conditions of the control valve 200. The same applies to the breakage pattern, which is also considered by the position controller during method execution. Additionally, the sensitivity of the method can be improved because a higher pressure in the process-related displacement of the valve pattern or breakage pattern into the pneumatic drive device is identified, and the actual pressure can be correspondingly attributed to spring breakage, which is uncorrected and located within or above the valve pattern and therefore not correspondingly attributed to spring breakage.

[0081] The position adjuster 255 can be equipped with a correction model that uses the pressure values ​​of sensors 290, 295 to calculate an approximation of the disturbance force acting on the valve actuation device by the medium reaction. This calculation, for example, allows for the exclusion of certain features from inspection. This avoids unnecessarily indicating failure, but also reduces the number of available features or indicators. Therefore, it is possible to adapt features such as valve diagrams or breakage diagrams to changes in the pressure of this or these process media.

[0082] The force exerted by the process medium on the valve cone 230 or valve core 225 can be reduced to two main values, for example, which can be calculated or estimated using the area A1 of the projection of the valve cone 230 onto the plane of the valve seat 220 and the area A2 corresponding to the difference between the area A1 and the cross-sectional area of ​​the valve stem 235. The disturbance force exerted by the process medium on the valve cone 230, valve stem 235, or valve core 225 can then be described or estimated using the difference vector (P1·A1-P2·A2)·e, where e is a unit vector that extends parallel to the valve stem 235 and points towards the drive mechanism of the control valve 200.

[0083] Figure 3 The stroke-pressure curve 300 is shown. The stroke-pressure curve 300 includes the operating range of valve 200, from the open position (stroke = 0%, pressure = P). 0％ Extend to the closed position (stroke = 100%, pressure = P) 100％ The position adjuster 255 adjusts the pneumatic drive of the regulating valve 200 so that the actual position of the valve core 225 coincides with the theoretical position X0. The valve core 225 then moves within the valve diagram 310 in curve 300. With the aid of valve diagram 310, each actual position of the valve core 225 can be corresponding to a pressure range achievable when the regulating valve 200 with its undamaged spring assembly is operating. Valve diagram 310 includes a supply pressure curve 315 and a relief pressure curve 320. The supply pressure curve 315 defines the maximum pressure, which can be corresponding to the actual position of the valve core 225 with the aid of valve diagram 310. The relief pressure curve 320 defines the minimum pressure, which can be corresponding to the actual position of the valve core 225 with the aid of valve diagram 310. The difference between curves 315 and 320 is a measure of friction that occurs when the valve core 225 moves, for example, along the sealing packing 280.

[0084] Figure 3 Intermediate value curve 325 is also shown. Intermediate value curve 325 represents the arithmetic mean of pressure supply curve 315 and pressure relief curve 320. Intermediate value curve 325 is used to derive fracture pattern 330 with intermediate value curve 335. For this purpose, curve 325 is scaled with a coefficient (3-1) / (3) to calculate intermediate value curve 335 of fracture pattern 330. The difference between intermediate value curve 325 and pressure supply curve 315 is then added to intermediate value curve 335 to define the upper boundary curve 340 of fracture pattern 330 up to high pressure. The difference between intermediate value curve 325 and pressure relief curve 315 is correspondingly subtracted from intermediate value curve 335 to define the lower boundary curve 345 of fracture pattern 330 up to low pressure.

[0085] If the values ​​at the actual location and actual pressure measurements are located within the fracture diagram 330, i.e. between the upper boundary curve 340 and the lower boundary curve 345, it can be assumed that one of the three springs of the preload drive of the regulating valve 200 has broken.

[0086] The breakage of one of the three springs in the preloaded drive mechanism of the control valve 200 causes the valve spool 225 to deflect, which is measured by the position adjuster 255. The position adjuster 255 then adjusts the pressure drive mechanism of the valve 200 to return the valve spool 225 to its initial or theoretical position X0. Graph 300 shows the motion trajectory 350, which represents the possible movement of the valve spool 225 after the breakage of one of the three springs in the control valve 200.

[0087] also, Figure 3 The motion trajectory 355 is shown. The motion trajectory 355 represents the characteristics of the valve core 225 without fine-tuning by the position adjuster 255.

[0088] During continuous operation of the control valve 200, the position of the valve core 225 is typically controlled by the position adjuster 255 and is checked within the fault diagnosis function range to see if one of the measured actual pressures, together with the actual position of the valve core 225, lies within the fracture diagram 330. If this is the case, the position adjuster 225 issues a notification or warning to the equipment control panel that one of the three springs of the preloaded drive has failed.

[0089] Figure 3 As exemplarily shown, the change in the operating characteristics of the drive or actuator of the control valve 200 due to spring failure can be simply understood as replacing the first family of characteristic curves (valve illustration 310) with a second family of characteristic curves (fracture illustration 330). Here, each family of characteristic curves includes three stroke-pressure characteristic curves (e.g., characteristic curves 315, 320, and 325 of valve illustration 310 or characteristic curves 335, 340, and 345 of fracture illustration 330), which are also referred to in the literature as illustrations of actuator-valve systems.

[0090] The intermediate value curve 325 can be understood as the ideal characteristic curve. The characteristic curve corresponds to the balance between pressure and spring force. Because of friction, the ideal characteristic curve is actually identifiable in many cases. For example, the valve core 225 effectively varies along the true positive characteristic curve 315, shown as a dashed line extending parallel to the ideal characteristic curve, from 0% to 100% of the runaway stroke. There, the force effectively acting on the spring assembly is reduced by friction. This movement falls behind the frictionless true condition. When moving in the opposite direction, the valve core 225 varies along the reverse characteristic curve 320, placed below the ideal characteristic curve, by the same dashed line. The exemplary parallel deviations of equal magnitude between the three explained characteristic curves correspond to the simplified assumption of constant friction. Friction can depend on direction, position, and other factors. For example, the sealing packing 280 can be moved into certain valve position areas and thus exert less friction on the valve core 225.

[0091] The adjustment strategy of the position adjuster 255 can be set to adjust the valve core 225 to a predetermined target position X0, just like in Figure 3 As shown in the exemplary sketch. The operating point of valve core 225 at the target position X0 can, in principle, lie in the line between the positive characteristic curve 315 and the negative characteristic curve 320 within the stroke-pressure curve diagram 300.

[0092] The normal operating point on the ideal characteristic curve is generally considered preferred, especially under symmetrical disturbance forces, which cause the valve core 225 to move away from the theoretical position X0. In this case, the force required to disengage from the target position in both directions is almost equal to the static friction force. The target position near the positive characteristic curve 315 or the negative characteristic curve 320 can be considered unaffected by unidirectional disturbance forces because there, in order to disengage from the target position in one direction, in addition to the static friction force, the preload force of the actuator must be overcome. The method explained in this application is generally independent of the location of the preferred normal operating point.

[0093] The failure defect of the springs of concern in the actuator spring assembly can be understood as a change in its family of characteristic curves. In graph 300, the lower family of characteristic curves 330 replaces the previous family 310. Family 330 exhibits a gentler trend due to the decrease in the spring constant of the spring assembly. In the exemplary case, it is assumed that one of the three identically configured springs fails. Accordingly, in this figure, the slope of the ideal characteristic curve 335 of family 330 is determined to be 2 / 3 of the slope of the ideal characteristic curve 325 of family 310. It is also assumed that friction is unaffected by spring failure. This may be different in reality. In particular, the failure of one spring may result in a total force relative to the eccentricity of the push rod 235, affecting friction in its guide mechanism or sealing packing 280.

[0094] Figure 4 A partial view 400 of the stroke-pressure curve 300 is shown. Three characteristic parameters are plotted here, which can be considered to characterize the trajectory 350 of the valve core 225 against the spring force or its associated spontaneous motion, including:

[0095] ·Maximum deviation 410,

[0096] • Pressure difference 420, and

[0097] • The area swept was 430.

[0098] The maximum deviation 410 is the largest difference between the theoretical position Xo and the position of the valve core 225 along the motion trajectory 350.

[0099] The pressure differential of 420 indicates the position of the valve core at Xo before and after one of the three springs of the control valve 200 breaks (see...). Figure 3 The required pressure difference. The swept area 430 is the distance between the motion trajectory 350 and the straight line from the starting point to the ending point of the motion trajectory 350.

[0100] The value used for the characteristic parameter is determined by simulating the breakage of one of the three springs in the control valve 200 and stored in the memory unit of the position regulator 255 during installation with the input mask. This value can be checked within the extended phase of the method performed by the position regulator 255 to identify the breakage of one of the springs in the preload drive of the control valve 200. If the valve core movement is recorded and there is a match with all or most of the stored values, it can be assumed that one of the springs has broken. The position regulator issues a corresponding alarm in this case. The function of the control valve 200 should then be checked and the defective spring assembly should be deactivated or replaced.

[0101] Figure 5 A portion 500 of the stroke-pressure curve 300 is shown, having the same range as portion 400. Several measurement points 510 are shown within this portion. A motion trajectory 350 is formed through these measurement points 510. Additionally, a window 520 is plotted. Window 520 indicates the position-related range of the position and pressure values.

[0102] The area formed by window 520 encompasses the possible movement changes of the valve spool when one of the springs breaks. This window, like the values ​​for characteristic parameters 410, 420, and 430, is determined through simulation or approximate calculation and stored in the memory unit of position adjuster 255 during installation with the aid of an input mask. In an extended phase of the method performed by position adjuster 255 to identify the breakage of one of the springs in the preload drive of control valve 200, it can be checked whether the measurement points recorded during valve spool movement are within window 520. If so, this is a strong indication that one of the springs has broken or failed. It can also be determined how many measurement points are located within window 520. The number of measurement points present within window 520 can also be considered for identifying the breakage of one of the springs and can be plotted, analyzed, and stored, for example, as a histogram.

[0103] Window 520 can also be determined by measurement. An exemplary measurement can be performed at the regulating valve, where the spring assembly is reduced by one spring. With the same explicitly specified spring, the result does not depend primarily on the choice of spring. Direct measurement first reveals the upper boundary curve 340 and the lower boundary curve 345 of the fracture diagram 330. The ideal characteristic curve 335 can be approximated by averaging, assuming friction is independent of direction. However, knowledge of the ideal characteristic curve 335 is not required in this exemplary case.

[0104] Figure 6A process diagram illustrating a preferred embodiment of the method 600 of the present invention is shown. The method begins at step 610, in which method parameters, such as valve diagrams, are specifically set. In step 620, the actual pressure and actual position of the valve spool are measured at a given moment. In step 630, a determination is made on how to continue the method based on the measured actual pressure and actual position. If no spring breakage is found, the method continues to step 620. If spring breakage is determined based on the measured values, an alarm or fault notification is output in step 640 and the method ends. This method can be implemented as a fault diagnosis function, for example, in the position regulator of a control valve or the control console of an equipment. As long as no spring breakage is found and the method is ended, the actual pressure of the pneumatic actuator and the actual position of the valve spool are periodically determined. This can be done, for example, at a fixed rate of 5Hz, 10Hz, 100Hz, 200Hz, or 500Hz. If spring breakage is found, the actuator of the control valve can be depressurized. The remaining spring force then moves the valve spool to a safe position. In this way, other spring breakages or control valve failures can be prevented.

[0105] Vocabulary

[0106] equipment

[0107] Equipment is a planned arrangement of technical components. These components may include machines, instruments, mechanisms, storage devices, pipelines or conveyor sections, and / or control or regulation components. They may be interconnected, wired, or logically linked to each other in terms of function, control technology, and / or safety technology.

[0108] Equipment operates in many different fields for a wide variety of purposes, including, in many cases, process technology equipment or technology equipment belonging to the chemical industry. The term "equipment" also includes refineries, long-distance heating systems, geothermal or solar thermal equipment, food production equipment, freshwater supply equipment or waste gas treatment equipment, biogas equipment, etc.

[0109] drive device or actuator

[0110] A drive or actuator is a unit that converts signals or signal sequences, such as those from a position adjuster or control computer, into mechanical motion or changes in physical parameters such as pressure or temperature. Drives or actuators are therefore suitable for controlling or regulating processes, such as those using process technology equipment. These signals or signal sequences are mostly transmitted electrically or via radio technology and can be designed to be analog or digital. Drives can be electric or fluid-driven, with fluid-driven drives potentially operating hydraulically or with compressed air.

[0111] Input mask

[0112] An input mask is a graphical user interface (GUI) that allows operation of application software via graphical symbols or controls. It is particularly used to input parameters and / or data into a computing unit that runs and is thus made available to the application software. This operation is accomplished, for example, using a mouse as a controller to operate or select graphical elements, typically via a touch sensor plane in smartphones, tablets, and electronic shopping information management systems. Parameter input can be made through a corresponding operating area or keyboard. Data is available via appropriate data carriers such as CDs, DVDs, or USB drives. Input masks can also be implemented via a network interface. Here, the parameters and / or data to be input can be entered via a network connector. Position adjusters may have input masks for, for example, setting or inputting valve symbols, (operating) parameters, or other characteristic parameters. Input masks can also be used to start or invoke calibration cycles or calibration steps to receive, record, or determine valve symbols, (operating) parameters, or other characteristic parameters.

[0113] Spring assembly

[0114] A spring assembly comprises multiple springs arranged and interconnected such that they can be compressed together. The springs can be arranged parallel to each other, so that the spring constant of the spring assembly is the sum of the spring constants of the individual springs. The spring assembly can be composed of identical or different springs, differing in their spring constants, the materials used in their manufacture, their configuration, or, in the case of helical springs, the number of coils. Spring assemblies can be used, for example, to preload the actuators of regulating valves.

[0115] spring

[0116] Springs are engineered components that can deform elastically in practical use. Springs are typically designed as helical springs. Helical springs are metal wires wound or coiled into a spiral shape. They are stretched apart (tension springs) or compressed together (compression springs) in the direction of the helical axis. Other implementations of springs involve air springs or elastic (rubber) pads.

[0117] balance

[0118] Equilibrium is the state of an object (such as a valve core) in which it is not experiencing acceleration. It therefore remains at rest or moves at a constant velocity. An object is in mechanical equilibrium when all the forces acting on it are in balance, that is, when the vector sum of the forces equals zero.

[0119] journey

[0120] The valve core stroke indicates the distance the valve core travels when moving from the first position to the second position.

[0121] Actual pressure

[0122] Actual pressure is the pressure at a specific moment, such as within a closed cavity or at a specific (planar) location. Actual pressure is a measure of the force exerted by a medium on the wall of a closed cavity or the area of ​​that specific location at a given moment. In many cases, actual pressure is the same as the pressure or corresponding force acting instantaneously on the surface of the cavity wall or location at the current moment. However, a specific moment can also refer to a past or future moment.

[0123] actual location

[0124] Actual position is the spatial location and / or orientation of an object at a given moment. In many cases, the actual position of an object is the same as its instantaneous position or orientation, that is, the same as the object's current position or orientation. However, a given moment may also involve a past or future moment. Actual position is typically used as the starting point for an object's purposeful movement to its theoretical position.

[0125] non-equilibrium

[0126] Non-equilibrium is the state of an object (such as a valve core) in which it undergoes acceleration. It therefore does not remain stationary and does not move at a constant velocity. An object is in mechanical non-equilibrium when all the forces acting on it are in non-equilibrium, that is, when the vector sum of the forces is not equal to zero.

[0127] process

[0128] A (technical) process is the entire process of a (technical) device. A continuous process is a process that operates directly on the device or during normal operation of the device. Processes can be continuous or ongoing (e.g., petroleum refining, remote heating, or electric current generation), discontinuous, batch, or cyclic (e.g., paste production for food processing, pharmaceutical production, or coffee roasting).

[0129] Process media

[0130] A process medium is a fluid medium that circulates or is transported within equipment within the scope of a process and may be altered at the same time. A process medium can be oil, salt, liquid, gas, or a mixture thereof.

[0131] Position adjuster

[0132] A position controller is a component of a valve that operates or controls the valve spool to open or close the valve. Position controllers in many cases include or are connected to an electric or fluid actuator.

[0133] Theoretical position

[0134] The theoretical position is the intended or desired spatial position or orientation of an object, and the deviation from the actual position should be as small as possible. In many cases, the theoretical position or orientation is the target of the object's directional movement or the final result sought through that movement. Ideally, at least as a result of the object's purposeful directional movement, the actual position should match the desired theoretical position, or the deviation should be within the positioning safety or predetermined position tolerance achievable through purposeful directional movement.

[0135] regulating valve

[0136] Also known as process valves or control valves, regulating valves are used to throttle or adjust fluid flow. For this purpose, an actuating device moves a closing component, such as an orifice cone or valve cone, relative to the valve seat. Here, the flow port is opened or closed, thereby affecting the flow rate until the flow port is fully closed. Generally, pneumatic or electric actuating devices are used for this purpose.

[0137] valve core

[0138] The valve core is a component of a valve that opens or closes the valve seat and is actuated, for example, by a position regulator to open or close the valve. It typically consists of a valve stem and a valve cone, with the valve cone mounted on the end of the valve stem.

[0139] Valve diagram

[0140] A valve symbol is a family of stroke-pressure curves within a stroke-pressure graph. Stroke-pressure curves are used to distribute pressure (e.g., the pressure distribution of a valve core's stroke, as in a pneumatically driven control valve) to the valve's travel. Valve symbols are mostly defined by supply and relief curves. The stroke-pressure curves of a valve symbol lie within the band defined by the supply and relief curves. These curves are non-coincident due to friction and exhibit hysteresis. The definition of a valve symbol can be supplemented by data from intermediate value curves.

[0141] time

[0142] A moment in time is a precisely defined instant within a time frame. It can be specified according to a time scale and, unlike a time interval, does not have an extended range.

[0143] Figure Labels

[0144] 100 regulating valve

[0145] 105 valve housing

[0146] 110 Entrance

[0147] 115 Exports

[0148] 120 valve seat

[0149] 125 valve core

[0150] 130 valve cone

[0151] 135 drive lever

[0152] 140 drive unit

[0153] 145 chambers

[0154] 150 Pressure Sensor

[0155] 155 Position Adjuster

[0156] 160 position sensor

[0157] 165 magnets

[0158] 170 spring assembly

[0159] 175 spring

[0160] 180 Sealing Packing

[0161] 185 Opening

[0162] 200 regulating valve

[0163] 205 valve housing

[0164] Entrance 210

[0165] 215 Exports

[0166] 220 valve seat

[0167] 225 valve core

[0168] 230 valve cone

[0169] 235 drive lever

[0170] 255 Position Adjuster

[0171] 280 Sealing Packing

[0172] 290 Pressure Sensor

[0173] 295 Pressure Sensor

[0174] 300 stroke-pressure curve

[0175] 310 Valve Legend

[0176] 315 Pressure Supply Curve

[0177] 320 pressure relief curve

[0178] 325 median curve

[0179] 330 Fracture Legend

[0180] 335 median curve

[0181] 340 Upper Boundary Curve

[0182] 345 Lower Boundary Curve

[0183] 350 Motion Trajectory

[0184] 355 Motion Trajectory

[0185] A partial view of the 400 stroke-pressure curve at 300.

[0186] 410 Maximum deviation

[0187] 420 pressure difference

[0188] The area swept by 430

[0189] A partial view of the 500 stroke-pressure curve at 300.

[0190] 510 Measurement Points

[0191] 520 windows

[0192] 600 methods

[0193] Input 610

[0194] 620 Measurement

[0195] 630 Inspection

[0196] 640 issued a report

[0197] References

[0198] The cited patent documents

[0199] US4,976,144A

[0200] WO2004 / 074947A1

[0201] DE29612346U1

[0202] WO2009 / 111101A1

[0203] DE102015225999A1.

[0204] Non-patent literature cited

[0205] Ralf Hebrich: Control Valves (Oldenburg Industrial Press, 2004, ISBN-13:978-3486630558, Chapter 3.5 "Valve Fault Diagnosis")

Claims

1. A method (600) for identifying the breakage of a spring (175) within a control valve (100; 200), 1.1 Wherein, the regulating valve (100; 200) is designated as part of the equipment on which the process is operated using the process medium; 1.2 Wherein, the regulating valve (100; 200) has the following components: 1.2.1 Valve core (125; 225), for influencing the process medium and / or the process operating on the equipment; 1.2.2 Pneumatic drive device (140), said pneumatic drive device (140) is configured to position the valve core (125; 225) to influence the process medium and / or the process; 1.2.2.1 Wherein, the pneumatic drive device (140) has the spring (175); 1.2.2.2 Wherein, the spring (175) preloads the pneumatic drive device (140); 1.2.3 A position sensor (160) for measuring the actual position of the valve core (125; 225); and 1.2.4 Pressure sensor (150) for measuring the actual pressure inside the pneumatic drive device (140); The method includes the following steps: 1.3 Define or set (610) valve diagram (310); 1.3.1 Wherein, the valve diagram (310) allows each valve core (125; 225) to be assigned a region of pressure that can be reached during the operation of the regulating valve (100; 200) with the non-destructive spring (175); 1.4 At a certain moment, the actual position of the valve core (125; 225) is measured (620) by means of the position sensor (160); 1.5 At a certain moment, the actual pressure within the pneumatic drive device (140) is measured (620) by means of the pressure sensor (150); 1.6 Determine whether the spring (175) is broken (630), wherein the breakage of the spring (175) is determined as follows: 1.6.1 The measured actual pressure is less than the pressure at each measured actual position that can be matched with the valve core (125; 225) by means of the valve diagram (310); and / or 1.6.2 The measured actual position is greater than each of the measured actual pressures that can be assigned to the valve core (125; 225) by means of the valve diagram (310); 1.7 Once the breakage of the spring (175) is determined, a notification (640) is output; 1.8 Measure and plot the actual positions of the valve core (125; 225) at different times, and 1.9 Measure and plot the actual pressure in the pneumatic drive unit (140) at different times; 1.10 Wherein, the breakage of the spring (175) is determined by analyzing whether the actual position and the actual pressure plotted out spontaneous movement of the valve core (125; 225) against the spring force occurs; 1.10.1 Wherein, the spontaneous motion characterizes the motion of the valve core (125; 225) immediately following the breakage of the spring (175); 1.11 The occurrence of the spontaneous movement of the valve core (125; 225) against the spring force is identified by the maximum deviation from the theoretical position that occurs during the spontaneous movement. 1.11.1 Among them, The pneumatic drive device (140) is adjusted such that the actual position of the valve core (125; 225) matches the theoretical position.

2. The method (600) according to claim 1, characterized in that, The valve diagram (310) is determined or set by means of an input mask.

3. The method (600) according to claim 1 or 2, characterized in that, The valve diagram (310) is updated according to an ordered interval.

4. The method (600) according to claim 1, characterized in that, 4.1 Derive the fracture diagram (330) from the valve diagram (310); 4.1.1 Among them, The fracture diagram (330) allows each actual position of the valve core (125; 225) to be assigned a region of pressure that can be reached when the spring (175) breaks; 4.2 The fracture of the spring (175) is determined such that the measured actual pressure corresponds to one of the pressures at the measured actual position of the valve core (125; 225) that can be assigned to the valve core (125; 225) by means of the fracture diagram (330).

5. The method (600) according to claim 1, characterized in that the occurrence of the spontaneous movement of the valve core (125; 225) against the spring force is also identified by at least one of the following means: 5.1 By means of the time elapsed during the said spontaneous motion, and / or 5.2 By means of the distance traveled during the spontaneous motion, and / or 5.3 By means of the velocity and / or acceleration that occurs during the said spontaneous motion, and / or 5.4 By means of the area swept in the stroke-pressure curve during the spontaneous motion.

6. The method (600) according to claim 1 or 5, characterized in that, The occurrence of the spontaneous motion is identified by using a predetermined region of position and pressure values, wherein the predetermined region includes the motion change process of the valve core (125; 225) when the spring (175) breaks. The motion change process is obtained through measurement and / or calculation.

7. The method (600) according to claim 1, characterized in that, When it is determined that the spring (175) of (630) has broken, the actual operating conditions and / or dominant parameters of the regulating valve (100; 200) shall be taken into account.

8. The method (600) according to claim 1, characterized in that, The regulating valve (100; 200) has one sensor (290, 295) or multiple sensors (290, 295) for measuring the pressure of the process medium.

9. A position adjuster for a regulating valve having a pre-tightened pneumatic actuation device (140), 9.1 Wherein, the regulating valve (100; 200) is designated as part of the equipment on which the process is operated using process media; 9.2 Wherein, the regulating valve (100; 200) has the following components: 9.2.1 Valve core (125; 225) for influencing the process medium and / or the process operating on the equipment; 9.2.2 Pneumatic drive device (140), said pneumatic drive device (140) being configured to position the valve core (125; 225) to influence the process medium and / or the process; 9.2.2.1 Wherein, the pneumatic drive device (140) has a spring (175); 9.2.2.2 Among them, The spring (175) preloads the pneumatic drive device (140); 9.2.3 A position sensor (160) for measuring the actual position of the valve core (125; 225); and 9.2.4 Pressure sensor (150) for measuring the actual pressure inside the pneumatic drive device (140); 9.3 Wherein, the position adjuster has a mechanism adapted to perform the steps of the method (600) according to any one of claims 1 to 8.

10. A regulating valve having a preload drive (140), wherein, The regulating valve has a position adjuster according to claim 9.

11. A process technology apparatus having a regulating valve according to claim 10.

12. A computer program product comprising instructions for causing a position adjuster according to claim 9 to perform the steps of the method according to any one of claims 1 to 8.

13. A data carrier on which a computer program product according to claim 12 is stored.

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