DE20221873U1 - Valve with online acquisition of valve data - Google Patents

Abstract

Valve with online recording of valve data, with which operating parameters and / or state parameters detected and on the technical Function state of the valve is closed, characterized that when using a double-acting cylinder in arranged two cylinder compartments or chambers pressure sensors are about which to receive the state parameters during of the operation, that is online, small excited vibrations or small deflections can be detected around the working point, with which corresponding reaction quantities in these moments are measurable.

Description

The The invention relates to a valve with online detection of valve data, at which operating parameters and / or state parameters detected and closed on the technical functional condition of the valve is, according to the preamble of protection claim 1.

Method for determining the state of a valve from parameters which in the regulation of a valve or the valve position or in the case of position switches of an electropneumatic type in general, for example, determine the state related to the state of the seal packing on the valve rod. The valve stem seal is provided as a so-called stuffing box seal, which consists of a seal pack which seals the valve stem between the pressurized medium and the outside space. In addition, process connections and mechanical connections are subject to wear. Therefore, with long term operation in certain positions, valves may become stiff or even seize over time. Therefore, it is advantageous to obtain early detection of this error and thus avoid unforeseen system failures. From the DE 44 55 058 A1 is a control valve of this type specified. This is evaluated from a plurality of parameters, namely start-up time, stopping time and discharge path to the friction and the friction state and thus the general operating state of the valve seal out.

A However, equipment and methods of this kind are for online measurement impractical. In one embodiment of this known device It is envisaged that such testing procedures cyclically or in a so-called separate autoconfiguration run be recorded. The disadvantage here is that such Testing procedures basically outside the measuring times are performed.

Thereby it turns out that if this is outside the normal Operating times of the valve are carried out, the test signals be emitted with relatively large amplitudes and the entire adjustment range of the valve must be passed through. Out For this reason, these procedures are in most cases not in running processes, so applicable online.

Another method for this is from the DE 42 33 301 A1 known. Again, a suitability for online capture is not readily given, or the determination of the state variables is essentially much too inaccurate.

Of the Invention is therefore the object of a valve of the initially referred to the online collection, ie during the normal operation, so that during the actual operating phase no downtime required be to generate the test run.

The Asked task is in a valve of the generic type Type according to the invention by the characterizing Characteristics of claim 1 solved.

One Another method in solution of the task is according to the invention from the features of claim 2 indicated.

Further advantageous embodiments of the invention Methods are given in the dependent claims.

Of the Core of the invention in that as a measure of the state of the valve is used the drive pressure, so, that the drive pressure curve in a direction of movement is continuously measured until the drive starts to move detects the pressure change caused by the movement, the associated pressure value detected, and that such Test run performed online during operation becomes. For this purpose, now with a double-acting cylinder, as used in this valve for driving, in both chambers or Cylinder chambers arranged pressure sensors.

In Another Varinate is according to the feature of claim 2 no separate test run performed but said test run is performed as in claim 1, However, by the drive pressure curve during a setpoint change to Determination of state parameters of the valve considered becomes.

In the former example, in the direction of movement "opening", in contrast to the direction of movement "closing", inverse pressure profiles which are equally evaluable result. In this case, the valve around a corresponding operating point alternately in dressing and dressing an actuating signal or a setpoint signal change is pronounced. The corresponding minimum and maximum values of the drive pressure are detected, measured and stored. The difference of a pressure pair between minimum and maximum multiplied by the respective reference surface of each piston surface of a double-acting drive, for example, thus gives the measure of the static friction force, wherein stationary applies: f friction = (P Max × A 1 ) - (P min × A 2 )

In the event that A ¹ = A ² results in the end effect that the friction force approximately proportio nal is the pressure difference between P ^max and P ^min .

Essential is in an embodiment of the invention that imprinted this so to speak spurious oscillation around an operating point is, which results in the considerable advantage that no separate Test run must be performed, but that due the imprinting of a so-called diagnostic vibration around the Operating point around the overall process actually to be regulated, in which the valve is integrated, is not disturbed. As a result, calibration or testing of the valve during operation, so it can be done online.

The same applies to the second variant, in which no imprinted Vibrations around the working point are used for diagnosis, but that setpoint changes, possibly with strong Increase or severe decline within the overall control process with be installed, so that here also an online measurement possible and not stopped for testing the process must become.

In An embodiment of the invention is characterized by said pressure values on the mobility of the valve and the condition of the seal closed. Other possibilities exist, however, if necessary wear-resistant mechanical inhibitions in the mechanical Detecting coupling elements and certain pressure gradients to be able to identify.

In Another advantageous embodiment is specified that the Maintenance personnel thus issued qualified notes automatically which are either due to a wear of the seal or to point out other errors of a mechanical nature. The Hints come here because of the fact that no cyclic Process pauses have to be carried out more but can be tested online during the process, that no test cycle in a forced pause time of the operation must be inserted.

The Operation of the invention is illustrated by the drawing.

The Illustration shows a so-called Striebeck curve, which is from the Literature known stick-slip effect describes. This represents the principle course of the frictional force, if the expended Force is counted in the direction of movement. Here is the following to recognize: When the drive is, for example one second and then a setpoint change is performed, the force (or the amount of Drive pressure) in the direction of movement continuously until the drive sets in motion. This pressure then drops with increasing speed rapidly. From a certain Minimum pressure then increases the curve again. To higher Speeds so again increases the frictional force or the pressure to be applied. The friction force in the Striebeck curve also recorded on the coordinate, this results in relatively equal piston surfaces of a double-acting Drive from the Striebeck curve is recorded on the coordinate, results in relatively equal piston surfaces of a double-acting drive from the difference of the pressures in the two chambers of the drive. In a first embodiment Then, the valve or the valve rod according to the above setpoint signal in one operating point alternately moved in dressing and dressing, with the corresponding min and Maximum values of the drive pressure or the pressure differences between the two chambers detected, measured and stored. The difference of a pressure pair multiplied by the respective one Reference surface of the piston surface - at one double-acting drive are the two surfaces - results thus a measure of the static friction, from the in the manner already disclosed above, then the frictional forces be determined.

The Illustration shows the already described Striebeck curve, on the friction force on the coordinate and the velocity on the ordinate is applied. The highest point on the left, almost at speed 0, represents overcoming the static friction forces With a corresponding pressure, these are overcome and the drive starts to move, with two effects to bear come; on the one hand solves the much lower sliding friction the stiction abruptly and the other is due to the movement the piston area increases the pressure medium volume, which in total then the here resulting strong pressure and thus Reibkraftabfall is to be understood. At a lower minimum at one Minimum speed then the reversal of the frictional force curve takes place, and from then on it increases proportionally with increasing speed back to.

Of the interesting area, namely between speed 0 and minimum speed is the one for the evaluation Range used in the invention. The determined there Frictional forces are significant for mobility of the valve and the condition of the valve stem seal. In accordance with the invention These values are then used to diagnose the condition the mechanical parts in this area (valve rod, packing etc.). On equipment required you just a valve or positioner arrangement of the usual Type and uses pressure sensors in the pressure input system, the measure the pressure curves. The pressure sensors can also in the area of the active fluid chambers or the cylinders be arranged directly.

The described characteristic is essential for small, single-acting drives too. For large drives, for Example also with pneumatic amplifier, need takes into account the physically exact conditions become. Since between the friction force and the measured variable is still connected an integral-acting process, namely the formation of pressure in the volume of the drive, the measured drive pressure once differentiated, around the max. and min. values of the frictional force dynamically to grasp correctly. But this can not only diagnostically on the condition of the valve stem seal, but also mechanical transmission components be closed with the from the pressures or pressure differences determined frictional forces are physically related. In that regard, even signs of wear can mechanical parts or to joints and deflections or the like as well be determined. For certain friction force patterns can Pattern matching methods that are significant for certain errors occur.

• 1. Stellungsregler im Automatikbetrieb.
• 2. Überprüfung, ob das Ventil in Ruhe ist, anhand von Stellung und Antriebsdruck.
• 3. Start des Auswerteverfahrens.
• 4. Messung des Antriebsdruckes und der Ventilstellung.
• 5. Sprungförmige Änderung des Sollwertes für die Stellung des Ventiles, Sollwert > tote Zone des Reglers, damit eine Ventilbewegung erzwungen wird.
• 6. Messung des Antriebsdruckes, Detektion des Druckes zum Zeitpunkt, wenn das Ventil sich bewegt.
• 7. Speicherung des aktuellen Antriebsdruckes und des zugehörigen Stellungswertes.
• 8. Wiederholung der Punkte 1 bis 7 für eine Sollwertänderung in entgegengesetzter Richtung.
• 9. Berechnung der Druckdifferenz und der Reibkraft bei der gegebenen Ventilstellung.
• 10. Abspeicherung der Werte in einem Diagramm.
• 11. Vergleich der Werte mit Referenzwerten, ggf Auslösung eines Alarms.
• 12. Wiederholung der Punkte 1–10 bei anderen Stellungswerten (z. B. betriebsbedingt) und Erzeugung eines stellungsabhängigen Diagrammes.

Overall, the following steps must be performed:

• 1st positioner in automatic mode.
• 2. Check whether the valve is at rest, based on position and drive pressure.
• 3. Start of the evaluation process.
• 4. Measurement of the drive pressure and the valve position.
• 5. Jump change the setpoint value for the position of the valve, setpoint> dead zone of the controller, so that a valve movement is forced.
• 6. Measurement of the drive pressure, detection of the pressure at the time when the valve is moving.
• 7. Storage of the current drive pressure and the associated position value.
• 8. Repetition of points 1 to 7 for a setpoint change in the opposite direction.
• 9. Calculation of the pressure difference and the friction force at the given valve position.
• 10. Storage of the values in a diagram.
• 11. Comparison of the values with reference values, if necessary triggering of an alarm.
• 12. Repeat points 1-10 for other position values (eg due to operational reasons) and generate a position-dependent diagram.

The second variant is that for a limited Scope of application is a simplified procedure below suitable. In this case, the actual value of the position signal as a measure of taken the time of pressure storage. To have to no setpoint changes are imprinted. The Position change due to process-related setpoint change can be waited. The actual value of the position and the drive pressure are recorded. If the position value changes, the associated drive pressure is dependent stored by the direction of movement. The corresponding ones Pressure values of different directions of movement are as above subtracted and a graph generated.

• 1. Überprüfung, ab der Antrieb steht.
• 2. Start des Auswerteverfahrens.
• 3. Messung des Antriebsdruckes und der Ventilstellung.
• 4. Detektion einer Änderung des Stellungs-Istwertes.
• 5. Speichern des zugehörigen Antriebsdruckes richtungsabhängig.
• 6. Berechnung des Differenzdruckes zweier unterschiedlicher Bewegungsrichtungen und/oder Berechnung der Reibkraft.
• 7. Generation eines Druck/Weg-Diagrammes.
• 8. Bei Überschreitung zulässiger Schranken Alarm an das Bedienpersonals

The steps are as follows:

• 1. Check, from the drive is.
• 2. Start of the evaluation process.
• 3. Measurement of the drive pressure and the valve position.
• 4. Detection of a change of the position actual value.
• 5. Save the associated drive pressure depending on the direction.
• 6. Calculation of the differential pressure of two different directions of movement and / or calculation of the friction force.
• 7th generation of a pressure / displacement diagram.
• 8. If permissible barriers are exceeded, alarm to operating personnel

For Variant 1 results for the calculation of the dead time following.

Of the Positioner and thus the distance measurement in the positioner is mechanical coupled to the valve stem. By wear can a lot arises within the mechanical coupling. consequently the path measuring signal is delayed, in particular when the direction is reversed. The resulting dead time reduces the stability the position control loop, resulting in permanent vibration and system shutdown can lead. The basic idea of the process is that the valve is replaced by setpoint changes as described above is moved. The actual time at which the valve from the resting state sets in motion, is from the drive pressure or the time behavior of the frictional force, as described above, detectable. At this time, a timer is started. This one will stopped when a path change via the distance measurement signal is detected. The measured time is then the one described above Dead time. A measure of the permissible dead time is the ratio measured time / max. Actuating time of the drive.

• 1. Stellungsregler in Automatik-Betrieb
• 2. Überprüfung, ob das Ventil in Ruhe ist anhand von Stellung oder Antriebsdruck (z. B. für 1 s)
• 3. Start des Auswerteverfahrens
• 4. Messung des Antriebsdruckes und der Ventilstellung
• 5. Sprungförmige Änderung des Sollwertes für die Stellung des Ventils Sollwert > als tote Zone des Reglers, damit eine Ventilbewegung erzwungen wird
• 6. Messung des Antriebsdruckes, Detektion des Zeitpunktes wenn das Ventil sich bewegt
• 7. Start der Zeitmessung
• 8. Bei Änderung des Positionssignals → Stopp der Zeitmessung und abspeichern
• 9. Wiederholung der Punkte 1–8 für mehrere Sollwertänderungen
• 10. Bestimmung der Totzeit aus den Messungen
• 11. Bei Überschreiten zulässiger Schranken, Alarm an das Bedienpersonal

The steps are as follows:

• 1st positioner in automatic mode
• 2. Check whether the valve is at rest by means of position or drive pressure (eg for 1 s)
• 3. Start of the evaluation process
• 4. Measurement of the drive pressure and the valve position
• 5. Jump change the setpoint value for the position of the valve setpoint> as a dead zone of the controller, so that a valve movement is forced
• 6. Measurement of the drive pressure, detection of the time when the valve moves
• 7. Start the time measurement
• 8. When changing the position signal → Stop the time measurement and save
• 9. Repeat points 1-8 for multiple setpoint changes
• 10. Determination of the dead time from the measurements
• 11. When permissible barriers are exceeded, alarm to operating personnel

For Variant 2 gives the following for the calculation of the way

T_t1

= gemessene Totzeit (ggf. in Richtung "öffnen")

T_y1

= Stellzeit (ggf. in Richtung "öffnen")

Y

= 100%-Hubbereich des Ventils in mm

^Ytote_Zone

= Tote Zone in mm

If viewing the dead zone as a hub is required, there are two options:
If the positioning times of the valve depend on the direction, the dead time must be stored depending on the direction. After determining the dead time, the dead zone is calculated as follows Y tote_Zone = (T t1 / T y1 ) × Y; in which

T _t1

= measured dead time (possibly in the direction "open")

T _y1

= Positioning time (possibly in the direction "open")

Y

= 100% stroke range of the valve in mm

^Y dead_zone

= Dead zone in mm

If there is a difference between both positioning times, the Calculation in the closing direction analog. It only has to one direction are evaluated. The important thing is always to each other corresponding times are used.

Leaves you can make a bigger mistake, so of course to dispense with the directional dependence.

Improved calculation

When the valve is new, small setpoint changes are made around an operating point (eg, 50%, or the most commonly used operating point) as described above. The time (t ₀ ) at which the valve starts to move is detected as described above. Similarly, the time (t ₆₃ ) is stored when the actual value of the position has subsequently reached 63% of the setpoint change (y ₆₃ ). Subsequently, the difference of the time values is formed Δt = t ₆₃ -t ₀ . From this, a weighting factor is calculated and stored and used for later calculation of the dead zone. The dead zone is calculated accordingly: Y tote_Zone = (y 63 / Δt) × (T t1 ) with the weighting factor (y 63 / At). (Note: instead of y63, t63, other time parameters known from control engineering could be used)

If the valve (drive) has direction-dependent positioning times, are also only mutually corresponding times (eg. in the direction of 'open').

• 1. Stellungsregler in Automatik-Betrieb
• 2. Überprüfung, ob das Ventil in Ruhe ist anhand von Stellung oder Antriebsdruck (z. B. für 1 s)
• 3. Start des Auswerteverfahrens
• 4. Messung des Antriebsdruckes und der Ventilstellung
• 5. Sprungförmige Änderung des Sollwertes für die Stellung des Ventils; Sollwert > als tote Zone des Reglers, damit eine Ventilbewegung erzwungen wird
• 6. Messung des Antriebsdruckes, Detektion des Zeitpunktes wenn das Ventil sich bewegt
• 7. Start der Zeitmessung
• 8. Bei Änderung des Positionssignals → Stopp der Zeitmessung und abspeichern
• 9. Wiederholung der Punkte 1–8 für mehrere Sollwertänderungen
• 10. Bestimmung der Totzeit aus den Messungen
• 11. Berechnung der toten Zone gemäss einem der Verfahren 1. oder 2.
• 12. Bei Überschreiten zulässiger Schranken, Alarm an das Bedienpersonal

This results in the following steps:

• 1st positioner in automatic mode
• 2. Check whether the valve is at rest by means of position or drive pressure (eg for 1 s)
• 3. Start of the evaluation process
• 4. Measurement of the drive pressure and the valve position
• 5. Jump-shaped change of the setpoint for the position of the valve; Setpoint> as the dead zone of the controller to force a valve movement
• 6. Measurement of the drive pressure, detection of the time when the valve moves
• 7. Start the time measurement
• 8. When changing the position signal → Stop the time measurement and save
• 9. Repeat points 1-8 for multiple setpoint changes
• 10. Determination of the dead time from the measurements
• 11. Calculation of the dead zone according to one of the methods 1. Or 2.
• 12. If permissible barriers are exceeded, alarm to operating personnel

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• - DE 4455058 A1 [0002]
• - DE 4233301 A1 [0005]

Claims (5)

Valve with online detection of valve data, in which operating parameters and / or condition parameters detected and closed on the technical functional condition of the valve, characterized in that when using a double-acting cylinder in both cylinder compartments or chambers pressure sensors are arranged, via which to obtain the Condition parameters during operation, that is, online, small excited vibrations or small deflections around the operating point can be detected, with which corresponding reaction quantities are measurable in these moments. Valve according to claim 1, characterized in that the Receiving the state parameters during operation, ie online, operational or process specific setpoint changes be used to the directional drive pressure (Driving force) to determine when the valve is in motion sets and from this to determine the state parameters of the same. Valve according to claim 1 or 2, characterized that about said pressure values on the mobility of the valve and / or the condition of the seal of the valve closed becomes. Valve according to claim 1 or 2, characterized that about said pressures on the state, or the state of wear of the mechanical coupling elements can be closed. Valve according to one of the preceding claims, characterized in that the mobility of the valve the respective state of the seal or the mechanical coupling elements be displayed on an ad.