CA2166867C - Valve positioner with pressure feedback, dynamic correction and diagnostics - Google Patents
Valve positioner with pressure feedback, dynamic correction and diagnostics Download PDFInfo
- Publication number
- CA2166867C CA2166867C CA002166867A CA2166867A CA2166867C CA 2166867 C CA2166867 C CA 2166867C CA 002166867 A CA002166867 A CA 002166867A CA 2166867 A CA2166867 A CA 2166867A CA 2166867 C CA2166867 C CA 2166867C
- Authority
- CA
- Canada
- Prior art keywords
- valve
- positioner
- control
- sensed
- control pressure
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
Links
Classifications
-
- G—PHYSICS
- G05—CONTROLLING; REGULATING
- G05D—SYSTEMS FOR CONTROLLING OR REGULATING NON-ELECTRIC VARIABLES
- G05D7/00—Control of flow
- G05D7/005—Control of flow characterised by the use of auxiliary non-electric power combined with the use of electric means
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16K—VALVES; TAPS; COCKS; ACTUATING-FLOATS; DEVICES FOR VENTING OR AERATING
- F16K31/00—Actuating devices; Operating means; Releasing devices
- F16K31/12—Actuating devices; Operating means; Releasing devices actuated by fluid
- F16K31/126—Actuating devices; Operating means; Releasing devices actuated by fluid the fluid acting on a diaphragm, bellows, or the like
- F16K31/1262—Actuating devices; Operating means; Releasing devices actuated by fluid the fluid acting on a diaphragm, bellows, or the like one side of the diaphragm being spring loaded
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16K—VALVES; TAPS; COCKS; ACTUATING-FLOATS; DEVICES FOR VENTING OR AERATING
- F16K37/00—Special means in or on valves or other cut-off apparatus for indicating or recording operation thereof, or for enabling an alarm to be given
- F16K37/0075—For recording or indicating the functioning of a valve in combination with test equipment
- F16K37/0083—For recording or indicating the functioning of a valve in combination with test equipment by measuring valve parameters
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
- Y10T137/00—Fluid handling
- Y10T137/2278—Pressure modulating relays or followers
- Y10T137/2409—With counter-balancing pressure feedback to the modulating device
- Y10T137/2452—With counter-counter balancing pressure feedback
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
- Y10T137/00—Fluid handling
- Y10T137/7722—Line condition change responsive valves
- Y10T137/7758—Pilot or servo controlled
- Y10T137/7759—Responsive to change in rate of fluid flow
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
- Y10T137/00—Fluid handling
- Y10T137/7722—Line condition change responsive valves
- Y10T137/7758—Pilot or servo controlled
- Y10T137/7761—Electrically actuated valve
Abstract
In this invention, a valve positioner (50) receives a setpoint from a master (62) and provides a control pressure to a valve actuator (70) for controlling a valve (72). A sensing circuit (102) in the positioner (50) senses the position of the valve (72) and the control pressure, and a control circuit (94) in the positioner (50) uses both the sensed pressure and position to provide a command output to a pneumatic section (100) which produces the control pressure.
Description
VALVE POSITIONER WITH PRESSURE FEEDBACK, DYNAMIC CORRECTION AND DIAGNOSTICS
A portion of the disclosure of this patent document contains material which is subject to copyright protection . The copyright owner has no obj ection to the facsimile reproduction by anyone of the patent document or the patent disclosure, as it appears in the Patent and Trademark Office patent file or records, but otherwise reserves all copyright rights whatsoever.
$ACKGROUND OF THE INVENTION
This invention relates to a valve positioner for controlling a valve which affects a process variable and more particularly, to such valve positioners having microprocessors.
There is a desire to improve the accuracy, dynamic performance and stability with which valve positioners operate, and to provide real-time diagnostics to a control room, for quality auditing requirements and so that maintenance and plant down-time can be predicted rather than suffer emergency shutdowns or unnecessary planned valve maintenance.
Various types of positioners are used in the process control industry. Some positioners are mechanically coupled to an actuator while some incorporate the actuator within the positioner. The actuator provides means for physically positioning the valve and may be electric, hydraulic or pneumatic.
Electric actuators have a current signal which drives a motor which positions the valve. Hydraulic actuators have oil-filled means for positioning the valve. By far the most common in the process control industry, a pneumatic actuator has a piston or a combination of a spring and diaphragm. Depending on the application and the level of control integration, positioners receive WO 95/06276 ~ ~ PCT/US94/07914 several types of input from a controller which are representative of the desired valve position. One type is a current input having a 4-20 mA or 10-50 mA
magnitude, a second is a digital signal superimposed on the current signal and a third is a fully digital input ' such as Fieldbus or Modbus~. Alternatively, the positioner may receive a 3-15 pound per square inch (PSI) pneumatic input representative of the desired valve position. Depending on the level of integration and the application as well, positioners have different types of outputs. Some positioners provide an output current to a motor, while still others have a fast responding hydraulic output. The most common type of positioner output is a 0-200 PSI pneumatic output.
Positioners, as the word is used in this application, includes all these field mounted instruments, including the various inputs and outputs, and their respective means for positioning valves, if applicable.
In the most common case of a spring and diaphragm actuator, the diaphragm deflects with the pressure delivered by the positioner, thereby exerting a force or torque on a control valve stem or rotary member, respectively, so as to change the position of the valve. Almost all positioners have a mechanical or an electronic position sensor to provide a position signal and some of them feed the position signal back into a microprocessor-based control section of the positioner. No matter what the specific means are for delivering force to position a valve, positioners having microprocessor based control algorithms are known.
Existing positioners improve the loop dynamic response, but have a limited bandwidth so that their usage is limited to slow control loops such as one which controls level in a tank or temperature in a reactor.
WO 95/Ob27C
A portion of the disclosure of this patent document contains material which is subject to copyright protection . The copyright owner has no obj ection to the facsimile reproduction by anyone of the patent document or the patent disclosure, as it appears in the Patent and Trademark Office patent file or records, but otherwise reserves all copyright rights whatsoever.
$ACKGROUND OF THE INVENTION
This invention relates to a valve positioner for controlling a valve which affects a process variable and more particularly, to such valve positioners having microprocessors.
There is a desire to improve the accuracy, dynamic performance and stability with which valve positioners operate, and to provide real-time diagnostics to a control room, for quality auditing requirements and so that maintenance and plant down-time can be predicted rather than suffer emergency shutdowns or unnecessary planned valve maintenance.
Various types of positioners are used in the process control industry. Some positioners are mechanically coupled to an actuator while some incorporate the actuator within the positioner. The actuator provides means for physically positioning the valve and may be electric, hydraulic or pneumatic.
Electric actuators have a current signal which drives a motor which positions the valve. Hydraulic actuators have oil-filled means for positioning the valve. By far the most common in the process control industry, a pneumatic actuator has a piston or a combination of a spring and diaphragm. Depending on the application and the level of control integration, positioners receive WO 95/06276 ~ ~ PCT/US94/07914 several types of input from a controller which are representative of the desired valve position. One type is a current input having a 4-20 mA or 10-50 mA
magnitude, a second is a digital signal superimposed on the current signal and a third is a fully digital input ' such as Fieldbus or Modbus~. Alternatively, the positioner may receive a 3-15 pound per square inch (PSI) pneumatic input representative of the desired valve position. Depending on the level of integration and the application as well, positioners have different types of outputs. Some positioners provide an output current to a motor, while still others have a fast responding hydraulic output. The most common type of positioner output is a 0-200 PSI pneumatic output.
Positioners, as the word is used in this application, includes all these field mounted instruments, including the various inputs and outputs, and their respective means for positioning valves, if applicable.
In the most common case of a spring and diaphragm actuator, the diaphragm deflects with the pressure delivered by the positioner, thereby exerting a force or torque on a control valve stem or rotary member, respectively, so as to change the position of the valve. Almost all positioners have a mechanical or an electronic position sensor to provide a position signal and some of them feed the position signal back into a microprocessor-based control section of the positioner. No matter what the specific means are for delivering force to position a valve, positioners having microprocessor based control algorithms are known.
Existing positioners improve the loop dynamic response, but have a limited bandwidth so that their usage is limited to slow control loops such as one which controls level in a tank or temperature in a reactor.
WO 95/Ob27C
One obstacle to ideal valve dynamic position control is that the valve characteristic (defined in this application as the relationship between flow and stem position or angle) deviates from the published valve characteristics by as much as five percent. Such non-ideality typifies all three major types of control valve characteristics: linear, equal percentage and quick opening. Furthermore, rotary and sliding stem valves may exhibit a nonlinear relationship between the actuator force provided to the valve and the flow through the valve, which is difficult for the inherently linear positioner to control even with the present valve stem position feedback. In fact, rotary valves have a non-monotonic torque vs. flow function as a result of the flow induced dynamic torque on the ball/butterfly in the valve. Everyday wear on valve components contributes to non-ideality in the control loop as well.
In practice newly installed loops are "detuned", or purposefully assigned non-ideal control constants, to compensate for wear so that the loop remains stable over a wide variety of conditions. Compounding these issues of static and dynamic control accuracy, valve-related loop shutdowns are undesirable and expensive for industry.
The Electric Power Research Institute estimates that electric power utilities would save $400 million U.S. dollars if each control valve operated only one week longer each year. Most plants schedule regular maintenance shutdowns to monitor and repair valves, replace worn packing and worn out valve components so as to avoid even more costly and hazardous emergency shutdowns. Diagnostic systems which monitor valve integrity are known, but are generally configured to diagnose problems in valves disconnected from a process .
WO 95/06276 ~ t 6 6 8 6 7 p~~s~4/07914 One real-time control valve has limited diagnostics capability.
A positioner, control valve and actuator are assembled and properly configured for installation in a time consuming process called bench-setting. During ' benchset, an operator manually sets the valve's maximum travel position (called the stroke position), the minimum travel position (called the zero), limit stops and stiffness parameters. The process is iterative because the settings are not independent.
Thus, there is a need for a microprocessor-based valve positioner easily configurable at benchset, with increased bandwidth and improved dynamic positioning accuracy, which also has real-time diagnostics to provide valve and actuator integrity information.
SUMMARY OF THE INVENTION
In this invention, a valve positioner provides a control pressure to a valve actuator mechanically coupled to a valve as a function of a signal representative of the position of the valve, a desired position setpoint received from a controller and the time derivative of the sensed control pressure. The positioner includes receiving means connected to a current loop for receiving the setpoint, sensing means for sensing the valve position and the control pressure and transducer means for converting a supply of pneumatic air to the control pressure as a function of a command output received from a control circuit within the positioner. In another embodiment of the invention, a valve positioner has a control circuit with position feedback includes a sensing circuit for sensing a set of state variables related to the valve performance. The -positioner includes a diagnostic circuit for storing an attribute of the valve and provides an output as a function of the stored valve attribute and a selected one of the state variables. Examples of stored valve attributes are position versus flow, torque versus position and torque versus flow curves. In another embodiment of the invention, the positioner includes a benchset control circuit which ramps the control pressure between an initial control pressure and a final control pressure and back to the initial control pressure, while sampling specific control pressures and their corresponding positions, in order to provide an output indicating the proper spring preload force on an actuator spring. In another embodiment of the invention, a valve positioner has a control circuit having position feedback providing a command output to a transducer circuit which provides.a control pressure as a function of the command output. The positioner includes a sensing circuit for sensing a set of state variables related to the valve performance. The positioner includes a correction circuit which stores a valve attribute affected by one of the physical parameters and dynamically compensates the command output as a function of the sensed physical parameter and the stored valve attribute.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a control flow chart of a control loop including a prior art valve positioner.
FIG. 2 is a block drawing of a valve positioner according to the present invention, connected to a master and an actuator mechanically coupled to a valve.
FIG. 3 is a block drawing of a valve positioner according to the present invention, connected ~1~686T
to a master and an actuator mechanically coupled to a valve.
FIG. 4 is a plot of stem position as a function of flow for quick opening, linear and equal percentage valves.
FIG. 5A is a plot of unit torque as a function of angular position for a butterfly valve; FIG. 5B is plan drawing of the butterfly valve in a pipe.
FIG. 6 is a block drawing of a valve positioner according to the present invention, connected to a master and an actuator mechanically coupled to a valve.
FIG. 7 is a plot of position versus flow as a function of valve seat wear.
FIG. 8 is a plot of actuator torque versus angular distance travelled, as a function of valve seat wear.
'FIG. 9 is a block drawing of a valve positioner according to the present invention, communicating with a hand-held communicator and an actuator mechanically coupled to a valve.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Positioners are generally used in slower process control loops, such as level or temperature, to improve loop performance. A control diagram of a typical prior-art electropneumatic positioner is shown in FIG. 1, where an inner cascade loop 20 comprises an error generator 22 for generating a difference between a controller setpoint 24 and a position sensor feedback 26, a current-to-pressure converter 28, an actuator connected to a valve 30 and a position sensor 32. An ' outer loop, shown generally at 34, includes an error generator 36 for differencing a desired setpoint 38 and a measurement 40 representative of the state of the 21~~8~~
_7_ process 42, and a controller 44 in series with cascade loop 20 and process 42. The overall system shown in FIG. 1 is usually stable if the bandwidth of the positioner, shown as the cascade loop 20, is at least a factor of four times larger than the bandwidth of outer loop 34. For loops which are difficult to tune, the factor should be increased. Prior art loops are purposefully detuned, or tuned non-ideally, to provide stability over a wide range of operating conditions. In addition, it is desirable to minimize overshoot. For second order systems with proportional feedback in a typically underdamped system, however, the overshoot increases when bandwidth is increased. In a valve positioner 50 made according to the present invention and shown in FIG. 2, a derivative of the pressure feedback signal 52 provides the rate feedback required to decrease overshoot without affecting bandwidth. In other words, the amount of overshoot, which is well controlled by the amount of damping in the process loop, is reduced without decreasing the bandwidth of positioner 50, unlike the loop shown in FIG. 1. In FIG.
2, a process loop shown generally at 60 includes a master 62 located in a control room sending a desired valve position signal to valve positioner 50 over a two wire current loop, although other communications loops, such as three and four wire current loops may be used.
Positioner 50 receives a supply of pneumatic air 61 and provides a control pressure 64 as a function of the desired setpoint from master 62 and two variables: the derivative of the control pressure signal 52 and a sensed position signal 68. Control pressure 64 provides pressurized air to an actuator 70 mechanically connected to a linear stem control valve 72, although rotary valves are adaptable for use with the present invention.
~' 166861 _8_ Actuator 70 has a diaphragm 71 which deflects when the pressurized control pressure air pushes against it, so as to urge stem 76 downwards. Stem 76 is fastened to a valve plug 78 which stops the flow between a first passageway 80 and a second passageway 82 when plug 78 is fully seated. Valve 72 is connected via flanges 84 to a pipe 86 carrying the flow Q. A transmitter 88 measures a flow Q and transmits a signal representative of the flow to master 62. Within positioner 50, a receiving circuit 92 receives a 4-20 mA signal from master 62, but may also receive the signal from a hand-held communicator. The magnitude of the current is representative of the desired valve position, but digital information including sensor selection commands and data may be superimposed on the current according to a protocol such as HART~, or with digital protocols such as DE, BRAIN~, Infinity or Modbus~. For critical control, position signal 68 is temperature compensated within a microprocessor. Alternatively, master 62 uses a fully digital protocol such as Fieldbus to communicate with positioner 50. This feature provides added flexibility and less wiring complexity over other schemes since the master need not recognize the need for the variable, request the process variable and subsequently transmit it to the field device which requires such variable. This direct communication of a process variable between transmitter 88 and positioner 50 significantly reduces delay in loop 60, making positioner 50 adapted for use in faster control loops such as ones which control flow.
A control circuit 94 provides a command output 97 as a function of the desired setpoint from circuit 92, the position signal 68 and pressure signal 52. A
time derivative circuit.96 within circuit 94 provides a _g_ rate feedback signal, or in other words, a derivative of pressure signal 52 with respect to time for the control algorithm within circuit 94. It is preferable to use the pressure signal as the rate feedback signal because it is available as a diagnostic and/or dynamic error correction signal in other embodiments of the present invention, but a force or torque signal suffices.
Control circuit 94 is preferably implemented in a low power CMOS microprocessor, or another appropriate 10' technology offering improved power and bandwidth, using an adaptive control algorithm which makes use of available sensed signals such as pressure, position, force, packing and seat wear to fine tune PID constants, and thereby obviate loop detuning. Power consumption is a concern in all embodiments of the present invention, since positioner 50 operates wholly on the 4-20 mA at 10-15 VDC ( 9 mA at 9V for Fieldbus ) received from master 62. For this reason, capacitance and frequency at which digital logic in the positioner operates must be minimized. Even aside from capacitance and frequency concerns, positioner 50 minimizes power in that it incorporates a current to pressure transducer and a pneumatic positioner, both of which are 4-20 mA
instruments. Therefore, valve control which previously consumed a maximum of 40 mA now consumes a maximum of 20 mA. A transducer and pneumatics circuit 100 receives a 0-200 PSI supply of air 61 and provides control pressure 64 as a function of the control signal from circuit 94, using a co-linear magnetic actuator and a deflected jet pilot stage as in Rosemount's Current to Pressure Transducer 3311 disclosed in U.S. Patent 4,534,376 to Brown, owned by the same assignee as the present invention. Sensing means 102 senses signals from a pressure sensor 54 and a mechanical position sensor 55, ~J84~
digitizes the signals and provides both to control circuit 94. , In addition to the primary benefit of decreasing the overshoot without affecting the undamped .
natural frequency (and therefore the bandwidth), rate feedback has other advantages. Actuators have varying internal load volumes, shown generally at 98, which have a wide range of pneumatic compliances. Those actuators used with low flow valves with a relatively small diameter have a smaller compliance than do actuators used with larger control valves. In prior art positioners, the gain in the control algorithm had to be manually adjusted to accommodate varying load volumes to assure stability. However, the present invention, which is initially tuned to accommodate large actuator compliance, requires no gain adjustment for small compliances because the magnitude of the rate feedback is necessarily smaller for a small actuator. When the positioner is connected to an actuator with a small load volume, the rate of change of pressure is large, so that the effective positioner loop gain is reduced during transients to prevent excessive overshoot, ringing and limit cycling. When the positioner is connected to an actuator with a large load volume, the rate of change of pressure is small, so that the effective positioner loop gain remains high during transients. By properly balancing the amount of pressure rate feedback~with the proportional gain and integral action of the control algorithm, a large range of actuator load volumes are accommodated while maintaining minimal overshoot and minimizing bandwidth.
In FIG. 3, a control loop 200 controls the flow Q in a pipe 202. A transmitter 204 senses the flow and transmits a signal to a master controller 206 over R'O 95/06276 PCT/US94/07914 ~~~8~~
a pair of twisted wires. Controller 206 sends a signal over another pair of twisted wires 208 to a valve positioner 210. Positioner 210 provides a control pressure 212 to a valve 214 through an actuator 216. A
diaphragm 220 in actuator 216 deflects with the control pressure and exerts a spring force on a sliding stem 222 fastened to a valve plug 224 located in flow Q, thereby urging plug 224 to further obstruct and therefore lessen flow Q. In order to increase the flow, the control pressure is exhausted in order to allow the spring force to re-position plug 224 upwards.
Positioner 210 comprises a receiving circuit 228, a control circuit 230, a transducer circuit and pneumatics 232, a sensing circuit 234 and a correction circuit 236. Sensing circuit 234 is connected to a pressure sensor 238 for sensing the control pressure, a mechanical member 240 connected to stem 222 for sensing valve position, and a load cell 242 for sensing force or torque as appropriate. However, force or torque is preferably sensed by dividing the pressure sensor 238 output by the actuator diaphragm area, so as to reduce the cost, power consumption and complexity associated with load cell 242. For applications requiring fine control, the sensed force signal is modified by the air spring effect from the volume of air between the diaphragm and the case. For all embodiments of the present invention, a non-contact position sensor with a continuous output but without moving linkages, such as LVDT sensors, RVDT sensors, and Hall Effect sensors are most appropriate. A multiplexer circuit 246 selects which of the sensor inputs is supplied to correction circuit 236, as a function of a command received from receiving circuit 228.
WO 95!06276 x ~ ~ y PCT/US94l07914 Receiving circuit 228 receives a 4-20 mA
signal from master 206, but may also receive the signal from a hand-held communicator. Circuit 228 operates in substantially the same way as circuit 92. Control circuit 230 receives a digital signal from circuit 228 representative of the desired valve position and a sensed position signal 229 representative of the valve position and provides an electrical control signal 231 as a function of appropriate PID constants set in circuit 230. Transducer and pneumatics circuit 232 receives a 0-200 PSI supply of air and uses standard current-to-pressure technology, as exemplified in Rosemount Current-to-Pressure Converter 3311 to provide control pressure 212 at the positioner nozzle.
Correction circuit 236 is preferably embodied in a low power CMOS microprocessor and includes a non-volatile storage 250 for storing an attribute of valve 214. In a first mode, generic information specific to valve 214 is stored in storage 250, such as its fully opened and fully closed positions, or its maximum and minimum acceptable pressures for control pressure 212.
The former data provides for correction of overdriven or underdriven valves; the latter data provides for correction of excessive over or under pressurization.
In a second mode, laboratory tested flow and torque measurements are collected for valve 214 and downloaded to storage 250 from master 206 through receiving circuit 228. Alternatively, the measured attribute may be stored in a non-volatile memory such as EEPROM and subsequently installed in positioner 210. Positioning is thereby tailored to the particular non-linearities of a valve to be used in the process. In a third mode of operation used for very precise positioning control, flow and torque attributes are initially stored in storage 250 and then dynamically updated while the valve is in operation. In this mode, a measured attribute is downloaded into storage 250 and then updated, point by point, as data is sampled at each point of operation.
Far all these modes, correction circuit 236 compares the stored attribute to the actual sensed physical parameter from sensing means 234 and compensates command output 231 accordingly. The stored attributes are updated dynamically during valve operation.
l0 One such stored attribute is the flow through valve 214 as a function of position. The flow is given by:
DP
SG
where Q is the flow, C~ is the valve coefficient, DP is the differential pressure across the valve and SG is the specific gravity of the fluid in the pipe. FIG. 4 shows three types of general flow versus position characteristics for quick opening, linear and equal percentage valves, labelled respectively at A, B and C.
A set of curves as a function of specific gravity are stored in storage 250. Correction circuit 236 receives a signal representative of the sensed flow from transmitter 204 and compares the stored position corresponding to the sensed flow to the sensed position.
Correction circuit compensates command output 231 for the deviation between the actual sensed position and the predicted position based on the sensed flow, using op-amp summing junction techniques. The effective bandwidth of the positioner may be lessened in this mode if the time required to request and receive the process variable is long compared to the response time for the positioner pneumatics. For implementations which impose significant transfer delays, such as a delay of 600 mS, WO 95/06276 ~j, 8' ~' ~ PCT/US94/07914 the positioner bandwidth is necessarily lessened.
However, when a communications protocol such as Fieldbus, which has a 1 mS request and retrieve time is employed, the target positioner bandwidth of 12 to 20 Hz is preserved.
A second stored attribute is the torque versus position attribute of valve 214. As a positioner is an inherently non-linear device, it has difficulty controlling valve position in a non-linear part of the torque vs. position curve. For some rotary valves, torque vs. position is not only non-linear but non-monotonic. FIG. 5A shows a pair of torque versus angular travel attributes for a rotary valve 400 in a pipe 402, as shown in FIG. 5B. Torque as a function of angular travel for opening the valve is shown by curve 404, while valve closing attributes are shown by curve 406. The accuracy provided by this feature is especially useful for control valves which pivot about a central operating point, since they continuously switch between disjointed operating attributes and have special problems associated with their control. In this mode, correction circuit 236 receives a torque signal required to move the valve through a unit distance (for a stem valve ) , or unit angle ( for a rotary valve ) and compares it to the stored force required at the current sensed position or angle. Correction circuit 236 compensates command output 231 for the deviation between the actual sensed position and the predicted position based on the sensed force. A third stored attribute is the measured torque versus flow attribute of valve 214.
In this mode, correction circuit 236 compares the sensed torque, as reported from load cell 242, to the stored torque at the desired flow Q, and compensates command output 231 for the difference.
Over time, the valve packing (shown at 244) degrades, and the seat (shown at 246) starts to leak, both of which change valve flow as a function of position. In this mode, the initial flow vs. position curve is stored in storage 250 as discussed earlier, but is dynamically updated. For example, when a position versus flow curve is selected, the sensed flow as reported from. transmitter 204, at each new operating position is stored, so as to replace a previous operating point on the characteristic. Standard interpolation algorithms are used to interpolate between large discontinuities in the updated curve. As the flow and the corresponding sensed position output is stored over time, a new curve is constructed which reflects the dynamic flow versus position attributes of the positioner. Modification of these attribute curves over time makes dynamic correction, combined with real-time updating of the stored torque attribute, essential to accurate static positioning. Although the previous example shows a loop controlling flow, appropriate alterations to the same scheme are apparent for control of other physical variables such as temperature, pH, upstream and downstream process pressure and valve position at operating limits (e.g.limit switches).
In FIG. 6, a control loop 300 including a transmitter 304, a master 306, a positioner 310, an actuator 314 and a valve 316 controls the flow Q in a pipe 302 in substantially the same way as discussed regarding FIG. 3. Positioner 310 comprises a receiving circuit 330, a transmit circuit 358, a control circuit 332, a transducer circuit and pneumatics 334, a sensing circuit 336 and a diagnostic circuit 338. Receiving circuit 330 communicates in substantially the same way as receiving circuit 228. Circuit 330 provides an output to a storage 354 for downloading valve attributes and another output to a mux 352 for selecting which of the sensed signals is selected for use in diagnostic circuit 338. Control circuit 332 receives both a position signal 333 representative of the valve position and a desired valve position signal from circuit 330 to provide an electrical command output 335 as a function of PID constants set in circuit 332. Transducer and pneumatics circuit 334 receives a 0-200 PSI supply of air and uses standard current-to-pressure technology to provide control pressure 312 at the positioner nozzle.
Sensing circuit 336 is connected to a pressure sensor 340 for sensing a control pressure 312 at a nozzle output on positioner 310, a mechanical member 342 connected to a valve stem 344 for sensing the valve position, a load cell 346 for sensing force, an acoustic sensor 348 for sensing cavitation and valve packing noises and a fugitive emission sensor 350 for sensing vapors from organic chemicals in piping 302. Other sensors which sense physical parameters related to valve performance can be added, such as ones for sensing upstream and downstream temperature, process pressure and limit switches for sensing position at extreme open and closed positions or sensors which provide process variables to cascaded control loops. A multiplexes circuit 352 selects which of the sensor inputs is supplied to diagnostic circuit 338, as a function of a command received from circuit 330. A transmit circuit 358 transmits alarms and diagnostic data to master 306.
Diagnostic circuit 338 is preferably embodied in a CMOS low power microprocessor and includes non-volatile storage circuit 354 for storing physical parameters related to the valve. As appropriate, the characteristics are in the form of a range of acceptable values or a single expected value representative of a maximum limit. The expected values are downloaded to storage means 354 from master 306 over a two wire loop 308. Master 306 typically is a loop controller located in a control room, but may also be a hand-held communicator communicating communications protocols such as HART~ or Fieldbus. A comparator 356 compares the expected physical parameter with the sensed physical parameter and provides a diagnostic output to transmit circuit 358. The diagnostic output may be an alarm or alert transmitted through circuit 358 to master 306 for immediate action, as when valve 314 is improperly positioned in a critical control loop, but may also be a value transmitted to master 306 on a regular basis, or available upon polling, so as to assess when maintenance is required. Seat wear is also important in planning maintenance as it contributes to valve leakage. For example, valve seat leakage is particularly critical in quick opening valves or such valves which provide a significant change in flow for a small adjustment to valve position. Curve A on FIG. 4 shows a quick opening valve characteristic, which is translated upwards by a constant representative of the amount of leakage (see dashed curve D). Seat leakage occurs when fluid flows between passageways 353a,b when plug 360 is fully seated in seat 360. One way to assess leakage is to store a position value corresponding to a fully-seated valve as manufactured, or alternatively the seated position value at last maintenance. As valve seat 360 wears, plug 356 seats at progressively lower positions. The diagnostic circuit compares the sensed position value when the valve is seated to the stored seated position value.
When the difference exceeds a stored limit, a valve seat wear value is transmitted to master 306. Another way to WO 95!06276 , ~ ~ ~ PCT/US94I07914 assess leakage is to compare a valve characteristic of valve 316 as originally manufactured, to another valve characteristic collected after wear has induced leakage.
In FIG. 7, a position versus flow characteristic is shown at A for valve 316 as originally manufactured, or alternatively, as collected at a previous maintenance.
After use, the dashed curve B represents the same characteristic collected at a later time. The characteristic is collected dynamically and constructed point by point at each position at which the valve is operated. The difference between the x-axis intercepts is representative of the leakage, which is reported to master 306 through circuit 358.
Diagnosis of valve packing-related failures is also critical to proper valve maintenance. In this diagnostic mode, a value is stored in storage 354 representative of the cumulative distance at which the packing must be re-packed. The stored value is compared to the cumulative distance travelled, (degrees of travel for rotary valves) so that when the cumulative distance travelled exceeds the distance at which re-packing is required, circuit 358 transmits the diagnostic output to master 306. Another measure of packing and seat erosion is the degradation, over time, of the force required to unseat the valve. In FIG. 8, curve A represents the actuator torque versus angular distance of a valve as originally manufactured, or at a previous maintenance, and curve B represents the same characteristic at a later date. The difference in the x-axis intercept represents the difference in force required to unseat the valve. When the difference is greater than a stored limit, the actuator force value is transmitted to master 306.
~~~~g~.7 Determining when the valve trim (i.e. valve stem and cage assemblies ) is galling is also critical for planning maintenance. In this mode, the force signal is selected for use in diagnostic circuit 338 and compared to a value representative of an excessive amount of force. When the sensed force signal exceeds the stored force value, the force value is reported to master 306 through circuit 358. Another stored attribute is related to solenoid valves, which are either fully open or shut. They are common in critical control applications, where they bring the loop to a safe state. Solenoid valves are prone to undesirable sticking after long periods of non-use. In this mode, control circuit 332 sends out alternating open and shut position commands at a rate faster than that which the process responds, so that the solenoid valve will be able to operate when needed. When the sensed position signal iri sensing circuit 336 indicates that the solenoid was unresponsive, a diagnostic message is sent to master 306. Another stored attribute is the concentration level of chemical emissions, measured initially after manufacture or during the last valve servicing. In this case, diagnostic circuit 338 receives the output from emissions sensor 350 and when the concentration of the organic chemical exceeds a stored limit, the concentration value is transmitted to master 306. Alternatively, a value representative of the chemical concentration is transmitted to master 306.
Cavitation and the integrity of valve stem and cage assemblies (i.e. valve trim) may also be diagnosed using the present invention. When the frequency spectra from acoustic sensor 348 matches a stored frequency spectra representative of cavitation noise in pipe 302 or noise from the valve trim, a cavitation value or a trim wear WO 95/06276 PCTlUS94/07914 ~1~~8~~
value is reported to master 306 through circuit 358.
Cavitation noise occurs at frequencies greater than 10 MHz, while trim vibration occurs in the 5-200 Hz range, and therefore is easily distinguishable from other pipe noises at lower frequencies. Broken actuator components can also be diagnosed. In this mode, a ruptured actuator diaphragm, a broken valve stem or plugged supply pressure is identified where the sensed position signal is constant when command output 335 changes.
Diagnostic circuit 338 sends an alarm or alert when the sensed position signal is constant while command output 335 changes a predetermined amount over a specific time.
Thermal history also assists in planning preventive maintenance for valves components which fail frequently or which are time-consuming to repair, such as electronics components in positioners. In this mode, diagnostic circuit 338 logs different categories of thermal events in storage 354 and provides this data to master 306 through circuit 358. For example, certain positioner components have a predicted mean time between failure (MTBF) of 1.9 years when operated at 100 relative humidity and at a temperature of 150°F.
Maintenance can be scheduled before the MTBF, 1.9 years, has elapsed since the last maintenance. Only a small portion of storage 354 is dedicated to this function, since the data is stored and uploaded at specific time intervals calculated to use only~a portion of storage 354. Newly stored data is written over previous data.
Positioner 310 also functions as a field mounted data logger. In this mode, circuit 338 logs relevant process variables for a short duration to record process dynamics and positioner response. The logged information is uploaded through circuit 358 to master 306, for process modeling and process upset correlation.
WO 95!06276 PCT/CTS94107914 Precise modeling is possible because both process and positioner dynamics are in a similar logging mode.
State variables at the time of valve maintenance are recorded for uploading and planning maintenance.
In order to set the proper spring preload force in a positioner, a benchset operation is performed. Usual practice requires initial setting of the stroke position (i.e. 100 position), zero position, limit stops and the stiffness of the actuator spring so the valve is properly configured for the process it will control. This process is iterative and time consuming and typically takes between one and four hours to complete for prior art ~positioners, since the sensed stem position and the sensed control pressure are not available to the operator. In the present invention, benchset operations are more efficient and precise than before. In FIG. 9, a positioner 500 operates in a benchset mode, where it is connected to a valve body 502 mechanically coupled to an actuator 504 but disconnected from the process. Positioner 500 receives benchset commands from and transmits benchsetting parameters to hand-held communicator 508, or alternatively a properly configured PC. A receiving circuit 520 connected to a two wire cable 522 translates commands from communicator 508 and sends them to a common bus 524 connecting a benchset control circuit 526 and a transmit circuit 528 for translating benchset data into a format communicable to master 508. Control circuit 526 is preferably implemented as a CMOS microprocessor including a non-volatile storage 530, although it could be implemented in analog circuitry as well. Control circuit 526 pravides an electrical command output to a transducer circuit and pneumatics section 542, which uses known I~P
technology to produce control pressure 540. A sensing WO 95/06276 a ~. ~ PCT/US94/07914 circuit 532 senses the position of a stem 534 in valve 502 via position sensor 536 and a pressure sensor 538 senses control pressure 540.
The first segment of a benchset operation calculates the spring constant of spring 506 while actuator 504 is disconnected so as to remove frictional effects. While positioner 500 is connected solely to valve 502, the operator sends a benchset command to circuit 526 through receiving circuit 520. Next, the operator enters into master 508 the desired initial control pressure, Po, and the end control pressure P1~, for use in control circuit 526 via receiving circuit 520. Control circuit 526 commands pneumatics 542 to ramp between pressure Po and P1~ while sending the sensed position signal to master 508 for display through transmit circuit 528. Control circuit 526 stored the sensed position corresponding to pressures Po and pressure P1~, and stores them in storage 530. The spring constant KS is calculated in circuit 526 according to the equation:
K _ C Ps-PR) AE Fs-Fn s Ys_Yo where y, is the valve position at 100 of stroke, yo is the valve position at 0~ of stroke, AE is the effective area of the diaphragm, PS is the control pressure at 100 stroke' and PR is the control pressure at 0~ stroke.
When fine control is required, the spring constant is calculated using an air spring constant as well. After connecting valve 502 to actuator 504, the frictional forces and the preload force on spring 506 is measured.
The operator enters valve stem positions corresponding to 0~ and 100 travel (yo and yl~), the line pressure in the installation, PL, and a seating pressure safety factor, SM, related to the amount of pressure which should be applied to valve 502 after the valve plug is seated. While circuit 526 sends a control signal to pneumatics 542 to cycle positioner 500 from 0~ travel and 100 travel and back to 0~, the sensed control pressure is stored in storage 530 at various positions:
PM is the control pressure just before the valve stem overcomes the frictional forces and moves, PR is the control pressure just after the stem has moved, PD is the control pressure at 25~ of positional span with the stem moving towards the closed position, PU is the control pressure at 75~ with the stem moving towards the fully open position and F; is the preload force on the spring, as sampled at 0~ position. The force signal is most cost effectively and efficiently sampled by dividing the output from pressure sensor 538 by the area of the actuator diaphragm, AE, but alternatively may be derived from a load cell, not shown. Circuit 526 now calculates and stores the static frictional force, FS, given by Fs- ~ PM PR) AE FD
and the dynamic frictional force opposing stem motion, FD:
FD. ~PD_PU) 2s The most time-consuming and iterative part of a benchset operation with a prior art positioner is for the operator to set the spring preload force by manually adjusting a nut 544 on the valve stem which changes the force on spring 506. However, a force balance equation can be derived for the positioner as connected to the WO 95/06276 ~ 6 ~ PCT/L1S94107914 actuator and valve and solved for the desired position, ys. The equation calculated in circuit 526 is:
Ff+F.i+PLAv AA ( Po-Pioo) YS' K +Yo-Yioo s where all but A" (the effective area of the actuator diaphragm) are previously defined. The quantity YS is the desired stem position at which nut 544 must be positioned in order to achieve the necessary preload force at specified control pressure and corresponding stem positions. During the manual adjustment of nut 544, the sensed position signal is transmitted through transmit circuit 528 to communicator 508, displayed as a percentage of the required stem travel adjustment.
Although the present invention has been described with reference to preferred embodiments, workers skilled in the art will recognize that changes may be made in form and detail without departing from the spirit and scope of the invention.
In practice newly installed loops are "detuned", or purposefully assigned non-ideal control constants, to compensate for wear so that the loop remains stable over a wide variety of conditions. Compounding these issues of static and dynamic control accuracy, valve-related loop shutdowns are undesirable and expensive for industry.
The Electric Power Research Institute estimates that electric power utilities would save $400 million U.S. dollars if each control valve operated only one week longer each year. Most plants schedule regular maintenance shutdowns to monitor and repair valves, replace worn packing and worn out valve components so as to avoid even more costly and hazardous emergency shutdowns. Diagnostic systems which monitor valve integrity are known, but are generally configured to diagnose problems in valves disconnected from a process .
WO 95/06276 ~ t 6 6 8 6 7 p~~s~4/07914 One real-time control valve has limited diagnostics capability.
A positioner, control valve and actuator are assembled and properly configured for installation in a time consuming process called bench-setting. During ' benchset, an operator manually sets the valve's maximum travel position (called the stroke position), the minimum travel position (called the zero), limit stops and stiffness parameters. The process is iterative because the settings are not independent.
Thus, there is a need for a microprocessor-based valve positioner easily configurable at benchset, with increased bandwidth and improved dynamic positioning accuracy, which also has real-time diagnostics to provide valve and actuator integrity information.
SUMMARY OF THE INVENTION
In this invention, a valve positioner provides a control pressure to a valve actuator mechanically coupled to a valve as a function of a signal representative of the position of the valve, a desired position setpoint received from a controller and the time derivative of the sensed control pressure. The positioner includes receiving means connected to a current loop for receiving the setpoint, sensing means for sensing the valve position and the control pressure and transducer means for converting a supply of pneumatic air to the control pressure as a function of a command output received from a control circuit within the positioner. In another embodiment of the invention, a valve positioner has a control circuit with position feedback includes a sensing circuit for sensing a set of state variables related to the valve performance. The -positioner includes a diagnostic circuit for storing an attribute of the valve and provides an output as a function of the stored valve attribute and a selected one of the state variables. Examples of stored valve attributes are position versus flow, torque versus position and torque versus flow curves. In another embodiment of the invention, the positioner includes a benchset control circuit which ramps the control pressure between an initial control pressure and a final control pressure and back to the initial control pressure, while sampling specific control pressures and their corresponding positions, in order to provide an output indicating the proper spring preload force on an actuator spring. In another embodiment of the invention, a valve positioner has a control circuit having position feedback providing a command output to a transducer circuit which provides.a control pressure as a function of the command output. The positioner includes a sensing circuit for sensing a set of state variables related to the valve performance. The positioner includes a correction circuit which stores a valve attribute affected by one of the physical parameters and dynamically compensates the command output as a function of the sensed physical parameter and the stored valve attribute.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a control flow chart of a control loop including a prior art valve positioner.
FIG. 2 is a block drawing of a valve positioner according to the present invention, connected to a master and an actuator mechanically coupled to a valve.
FIG. 3 is a block drawing of a valve positioner according to the present invention, connected ~1~686T
to a master and an actuator mechanically coupled to a valve.
FIG. 4 is a plot of stem position as a function of flow for quick opening, linear and equal percentage valves.
FIG. 5A is a plot of unit torque as a function of angular position for a butterfly valve; FIG. 5B is plan drawing of the butterfly valve in a pipe.
FIG. 6 is a block drawing of a valve positioner according to the present invention, connected to a master and an actuator mechanically coupled to a valve.
FIG. 7 is a plot of position versus flow as a function of valve seat wear.
FIG. 8 is a plot of actuator torque versus angular distance travelled, as a function of valve seat wear.
'FIG. 9 is a block drawing of a valve positioner according to the present invention, communicating with a hand-held communicator and an actuator mechanically coupled to a valve.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Positioners are generally used in slower process control loops, such as level or temperature, to improve loop performance. A control diagram of a typical prior-art electropneumatic positioner is shown in FIG. 1, where an inner cascade loop 20 comprises an error generator 22 for generating a difference between a controller setpoint 24 and a position sensor feedback 26, a current-to-pressure converter 28, an actuator connected to a valve 30 and a position sensor 32. An ' outer loop, shown generally at 34, includes an error generator 36 for differencing a desired setpoint 38 and a measurement 40 representative of the state of the 21~~8~~
_7_ process 42, and a controller 44 in series with cascade loop 20 and process 42. The overall system shown in FIG. 1 is usually stable if the bandwidth of the positioner, shown as the cascade loop 20, is at least a factor of four times larger than the bandwidth of outer loop 34. For loops which are difficult to tune, the factor should be increased. Prior art loops are purposefully detuned, or tuned non-ideally, to provide stability over a wide range of operating conditions. In addition, it is desirable to minimize overshoot. For second order systems with proportional feedback in a typically underdamped system, however, the overshoot increases when bandwidth is increased. In a valve positioner 50 made according to the present invention and shown in FIG. 2, a derivative of the pressure feedback signal 52 provides the rate feedback required to decrease overshoot without affecting bandwidth. In other words, the amount of overshoot, which is well controlled by the amount of damping in the process loop, is reduced without decreasing the bandwidth of positioner 50, unlike the loop shown in FIG. 1. In FIG.
2, a process loop shown generally at 60 includes a master 62 located in a control room sending a desired valve position signal to valve positioner 50 over a two wire current loop, although other communications loops, such as three and four wire current loops may be used.
Positioner 50 receives a supply of pneumatic air 61 and provides a control pressure 64 as a function of the desired setpoint from master 62 and two variables: the derivative of the control pressure signal 52 and a sensed position signal 68. Control pressure 64 provides pressurized air to an actuator 70 mechanically connected to a linear stem control valve 72, although rotary valves are adaptable for use with the present invention.
~' 166861 _8_ Actuator 70 has a diaphragm 71 which deflects when the pressurized control pressure air pushes against it, so as to urge stem 76 downwards. Stem 76 is fastened to a valve plug 78 which stops the flow between a first passageway 80 and a second passageway 82 when plug 78 is fully seated. Valve 72 is connected via flanges 84 to a pipe 86 carrying the flow Q. A transmitter 88 measures a flow Q and transmits a signal representative of the flow to master 62. Within positioner 50, a receiving circuit 92 receives a 4-20 mA signal from master 62, but may also receive the signal from a hand-held communicator. The magnitude of the current is representative of the desired valve position, but digital information including sensor selection commands and data may be superimposed on the current according to a protocol such as HART~, or with digital protocols such as DE, BRAIN~, Infinity or Modbus~. For critical control, position signal 68 is temperature compensated within a microprocessor. Alternatively, master 62 uses a fully digital protocol such as Fieldbus to communicate with positioner 50. This feature provides added flexibility and less wiring complexity over other schemes since the master need not recognize the need for the variable, request the process variable and subsequently transmit it to the field device which requires such variable. This direct communication of a process variable between transmitter 88 and positioner 50 significantly reduces delay in loop 60, making positioner 50 adapted for use in faster control loops such as ones which control flow.
A control circuit 94 provides a command output 97 as a function of the desired setpoint from circuit 92, the position signal 68 and pressure signal 52. A
time derivative circuit.96 within circuit 94 provides a _g_ rate feedback signal, or in other words, a derivative of pressure signal 52 with respect to time for the control algorithm within circuit 94. It is preferable to use the pressure signal as the rate feedback signal because it is available as a diagnostic and/or dynamic error correction signal in other embodiments of the present invention, but a force or torque signal suffices.
Control circuit 94 is preferably implemented in a low power CMOS microprocessor, or another appropriate 10' technology offering improved power and bandwidth, using an adaptive control algorithm which makes use of available sensed signals such as pressure, position, force, packing and seat wear to fine tune PID constants, and thereby obviate loop detuning. Power consumption is a concern in all embodiments of the present invention, since positioner 50 operates wholly on the 4-20 mA at 10-15 VDC ( 9 mA at 9V for Fieldbus ) received from master 62. For this reason, capacitance and frequency at which digital logic in the positioner operates must be minimized. Even aside from capacitance and frequency concerns, positioner 50 minimizes power in that it incorporates a current to pressure transducer and a pneumatic positioner, both of which are 4-20 mA
instruments. Therefore, valve control which previously consumed a maximum of 40 mA now consumes a maximum of 20 mA. A transducer and pneumatics circuit 100 receives a 0-200 PSI supply of air 61 and provides control pressure 64 as a function of the control signal from circuit 94, using a co-linear magnetic actuator and a deflected jet pilot stage as in Rosemount's Current to Pressure Transducer 3311 disclosed in U.S. Patent 4,534,376 to Brown, owned by the same assignee as the present invention. Sensing means 102 senses signals from a pressure sensor 54 and a mechanical position sensor 55, ~J84~
digitizes the signals and provides both to control circuit 94. , In addition to the primary benefit of decreasing the overshoot without affecting the undamped .
natural frequency (and therefore the bandwidth), rate feedback has other advantages. Actuators have varying internal load volumes, shown generally at 98, which have a wide range of pneumatic compliances. Those actuators used with low flow valves with a relatively small diameter have a smaller compliance than do actuators used with larger control valves. In prior art positioners, the gain in the control algorithm had to be manually adjusted to accommodate varying load volumes to assure stability. However, the present invention, which is initially tuned to accommodate large actuator compliance, requires no gain adjustment for small compliances because the magnitude of the rate feedback is necessarily smaller for a small actuator. When the positioner is connected to an actuator with a small load volume, the rate of change of pressure is large, so that the effective positioner loop gain is reduced during transients to prevent excessive overshoot, ringing and limit cycling. When the positioner is connected to an actuator with a large load volume, the rate of change of pressure is small, so that the effective positioner loop gain remains high during transients. By properly balancing the amount of pressure rate feedback~with the proportional gain and integral action of the control algorithm, a large range of actuator load volumes are accommodated while maintaining minimal overshoot and minimizing bandwidth.
In FIG. 3, a control loop 200 controls the flow Q in a pipe 202. A transmitter 204 senses the flow and transmits a signal to a master controller 206 over R'O 95/06276 PCT/US94/07914 ~~~8~~
a pair of twisted wires. Controller 206 sends a signal over another pair of twisted wires 208 to a valve positioner 210. Positioner 210 provides a control pressure 212 to a valve 214 through an actuator 216. A
diaphragm 220 in actuator 216 deflects with the control pressure and exerts a spring force on a sliding stem 222 fastened to a valve plug 224 located in flow Q, thereby urging plug 224 to further obstruct and therefore lessen flow Q. In order to increase the flow, the control pressure is exhausted in order to allow the spring force to re-position plug 224 upwards.
Positioner 210 comprises a receiving circuit 228, a control circuit 230, a transducer circuit and pneumatics 232, a sensing circuit 234 and a correction circuit 236. Sensing circuit 234 is connected to a pressure sensor 238 for sensing the control pressure, a mechanical member 240 connected to stem 222 for sensing valve position, and a load cell 242 for sensing force or torque as appropriate. However, force or torque is preferably sensed by dividing the pressure sensor 238 output by the actuator diaphragm area, so as to reduce the cost, power consumption and complexity associated with load cell 242. For applications requiring fine control, the sensed force signal is modified by the air spring effect from the volume of air between the diaphragm and the case. For all embodiments of the present invention, a non-contact position sensor with a continuous output but without moving linkages, such as LVDT sensors, RVDT sensors, and Hall Effect sensors are most appropriate. A multiplexer circuit 246 selects which of the sensor inputs is supplied to correction circuit 236, as a function of a command received from receiving circuit 228.
WO 95!06276 x ~ ~ y PCT/US94l07914 Receiving circuit 228 receives a 4-20 mA
signal from master 206, but may also receive the signal from a hand-held communicator. Circuit 228 operates in substantially the same way as circuit 92. Control circuit 230 receives a digital signal from circuit 228 representative of the desired valve position and a sensed position signal 229 representative of the valve position and provides an electrical control signal 231 as a function of appropriate PID constants set in circuit 230. Transducer and pneumatics circuit 232 receives a 0-200 PSI supply of air and uses standard current-to-pressure technology, as exemplified in Rosemount Current-to-Pressure Converter 3311 to provide control pressure 212 at the positioner nozzle.
Correction circuit 236 is preferably embodied in a low power CMOS microprocessor and includes a non-volatile storage 250 for storing an attribute of valve 214. In a first mode, generic information specific to valve 214 is stored in storage 250, such as its fully opened and fully closed positions, or its maximum and minimum acceptable pressures for control pressure 212.
The former data provides for correction of overdriven or underdriven valves; the latter data provides for correction of excessive over or under pressurization.
In a second mode, laboratory tested flow and torque measurements are collected for valve 214 and downloaded to storage 250 from master 206 through receiving circuit 228. Alternatively, the measured attribute may be stored in a non-volatile memory such as EEPROM and subsequently installed in positioner 210. Positioning is thereby tailored to the particular non-linearities of a valve to be used in the process. In a third mode of operation used for very precise positioning control, flow and torque attributes are initially stored in storage 250 and then dynamically updated while the valve is in operation. In this mode, a measured attribute is downloaded into storage 250 and then updated, point by point, as data is sampled at each point of operation.
Far all these modes, correction circuit 236 compares the stored attribute to the actual sensed physical parameter from sensing means 234 and compensates command output 231 accordingly. The stored attributes are updated dynamically during valve operation.
l0 One such stored attribute is the flow through valve 214 as a function of position. The flow is given by:
DP
SG
where Q is the flow, C~ is the valve coefficient, DP is the differential pressure across the valve and SG is the specific gravity of the fluid in the pipe. FIG. 4 shows three types of general flow versus position characteristics for quick opening, linear and equal percentage valves, labelled respectively at A, B and C.
A set of curves as a function of specific gravity are stored in storage 250. Correction circuit 236 receives a signal representative of the sensed flow from transmitter 204 and compares the stored position corresponding to the sensed flow to the sensed position.
Correction circuit compensates command output 231 for the deviation between the actual sensed position and the predicted position based on the sensed flow, using op-amp summing junction techniques. The effective bandwidth of the positioner may be lessened in this mode if the time required to request and receive the process variable is long compared to the response time for the positioner pneumatics. For implementations which impose significant transfer delays, such as a delay of 600 mS, WO 95/06276 ~j, 8' ~' ~ PCT/US94/07914 the positioner bandwidth is necessarily lessened.
However, when a communications protocol such as Fieldbus, which has a 1 mS request and retrieve time is employed, the target positioner bandwidth of 12 to 20 Hz is preserved.
A second stored attribute is the torque versus position attribute of valve 214. As a positioner is an inherently non-linear device, it has difficulty controlling valve position in a non-linear part of the torque vs. position curve. For some rotary valves, torque vs. position is not only non-linear but non-monotonic. FIG. 5A shows a pair of torque versus angular travel attributes for a rotary valve 400 in a pipe 402, as shown in FIG. 5B. Torque as a function of angular travel for opening the valve is shown by curve 404, while valve closing attributes are shown by curve 406. The accuracy provided by this feature is especially useful for control valves which pivot about a central operating point, since they continuously switch between disjointed operating attributes and have special problems associated with their control. In this mode, correction circuit 236 receives a torque signal required to move the valve through a unit distance (for a stem valve ) , or unit angle ( for a rotary valve ) and compares it to the stored force required at the current sensed position or angle. Correction circuit 236 compensates command output 231 for the deviation between the actual sensed position and the predicted position based on the sensed force. A third stored attribute is the measured torque versus flow attribute of valve 214.
In this mode, correction circuit 236 compares the sensed torque, as reported from load cell 242, to the stored torque at the desired flow Q, and compensates command output 231 for the difference.
Over time, the valve packing (shown at 244) degrades, and the seat (shown at 246) starts to leak, both of which change valve flow as a function of position. In this mode, the initial flow vs. position curve is stored in storage 250 as discussed earlier, but is dynamically updated. For example, when a position versus flow curve is selected, the sensed flow as reported from. transmitter 204, at each new operating position is stored, so as to replace a previous operating point on the characteristic. Standard interpolation algorithms are used to interpolate between large discontinuities in the updated curve. As the flow and the corresponding sensed position output is stored over time, a new curve is constructed which reflects the dynamic flow versus position attributes of the positioner. Modification of these attribute curves over time makes dynamic correction, combined with real-time updating of the stored torque attribute, essential to accurate static positioning. Although the previous example shows a loop controlling flow, appropriate alterations to the same scheme are apparent for control of other physical variables such as temperature, pH, upstream and downstream process pressure and valve position at operating limits (e.g.limit switches).
In FIG. 6, a control loop 300 including a transmitter 304, a master 306, a positioner 310, an actuator 314 and a valve 316 controls the flow Q in a pipe 302 in substantially the same way as discussed regarding FIG. 3. Positioner 310 comprises a receiving circuit 330, a transmit circuit 358, a control circuit 332, a transducer circuit and pneumatics 334, a sensing circuit 336 and a diagnostic circuit 338. Receiving circuit 330 communicates in substantially the same way as receiving circuit 228. Circuit 330 provides an output to a storage 354 for downloading valve attributes and another output to a mux 352 for selecting which of the sensed signals is selected for use in diagnostic circuit 338. Control circuit 332 receives both a position signal 333 representative of the valve position and a desired valve position signal from circuit 330 to provide an electrical command output 335 as a function of PID constants set in circuit 332. Transducer and pneumatics circuit 334 receives a 0-200 PSI supply of air and uses standard current-to-pressure technology to provide control pressure 312 at the positioner nozzle.
Sensing circuit 336 is connected to a pressure sensor 340 for sensing a control pressure 312 at a nozzle output on positioner 310, a mechanical member 342 connected to a valve stem 344 for sensing the valve position, a load cell 346 for sensing force, an acoustic sensor 348 for sensing cavitation and valve packing noises and a fugitive emission sensor 350 for sensing vapors from organic chemicals in piping 302. Other sensors which sense physical parameters related to valve performance can be added, such as ones for sensing upstream and downstream temperature, process pressure and limit switches for sensing position at extreme open and closed positions or sensors which provide process variables to cascaded control loops. A multiplexes circuit 352 selects which of the sensor inputs is supplied to diagnostic circuit 338, as a function of a command received from circuit 330. A transmit circuit 358 transmits alarms and diagnostic data to master 306.
Diagnostic circuit 338 is preferably embodied in a CMOS low power microprocessor and includes non-volatile storage circuit 354 for storing physical parameters related to the valve. As appropriate, the characteristics are in the form of a range of acceptable values or a single expected value representative of a maximum limit. The expected values are downloaded to storage means 354 from master 306 over a two wire loop 308. Master 306 typically is a loop controller located in a control room, but may also be a hand-held communicator communicating communications protocols such as HART~ or Fieldbus. A comparator 356 compares the expected physical parameter with the sensed physical parameter and provides a diagnostic output to transmit circuit 358. The diagnostic output may be an alarm or alert transmitted through circuit 358 to master 306 for immediate action, as when valve 314 is improperly positioned in a critical control loop, but may also be a value transmitted to master 306 on a regular basis, or available upon polling, so as to assess when maintenance is required. Seat wear is also important in planning maintenance as it contributes to valve leakage. For example, valve seat leakage is particularly critical in quick opening valves or such valves which provide a significant change in flow for a small adjustment to valve position. Curve A on FIG. 4 shows a quick opening valve characteristic, which is translated upwards by a constant representative of the amount of leakage (see dashed curve D). Seat leakage occurs when fluid flows between passageways 353a,b when plug 360 is fully seated in seat 360. One way to assess leakage is to store a position value corresponding to a fully-seated valve as manufactured, or alternatively the seated position value at last maintenance. As valve seat 360 wears, plug 356 seats at progressively lower positions. The diagnostic circuit compares the sensed position value when the valve is seated to the stored seated position value.
When the difference exceeds a stored limit, a valve seat wear value is transmitted to master 306. Another way to WO 95!06276 , ~ ~ ~ PCT/US94I07914 assess leakage is to compare a valve characteristic of valve 316 as originally manufactured, to another valve characteristic collected after wear has induced leakage.
In FIG. 7, a position versus flow characteristic is shown at A for valve 316 as originally manufactured, or alternatively, as collected at a previous maintenance.
After use, the dashed curve B represents the same characteristic collected at a later time. The characteristic is collected dynamically and constructed point by point at each position at which the valve is operated. The difference between the x-axis intercepts is representative of the leakage, which is reported to master 306 through circuit 358.
Diagnosis of valve packing-related failures is also critical to proper valve maintenance. In this diagnostic mode, a value is stored in storage 354 representative of the cumulative distance at which the packing must be re-packed. The stored value is compared to the cumulative distance travelled, (degrees of travel for rotary valves) so that when the cumulative distance travelled exceeds the distance at which re-packing is required, circuit 358 transmits the diagnostic output to master 306. Another measure of packing and seat erosion is the degradation, over time, of the force required to unseat the valve. In FIG. 8, curve A represents the actuator torque versus angular distance of a valve as originally manufactured, or at a previous maintenance, and curve B represents the same characteristic at a later date. The difference in the x-axis intercept represents the difference in force required to unseat the valve. When the difference is greater than a stored limit, the actuator force value is transmitted to master 306.
~~~~g~.7 Determining when the valve trim (i.e. valve stem and cage assemblies ) is galling is also critical for planning maintenance. In this mode, the force signal is selected for use in diagnostic circuit 338 and compared to a value representative of an excessive amount of force. When the sensed force signal exceeds the stored force value, the force value is reported to master 306 through circuit 358. Another stored attribute is related to solenoid valves, which are either fully open or shut. They are common in critical control applications, where they bring the loop to a safe state. Solenoid valves are prone to undesirable sticking after long periods of non-use. In this mode, control circuit 332 sends out alternating open and shut position commands at a rate faster than that which the process responds, so that the solenoid valve will be able to operate when needed. When the sensed position signal iri sensing circuit 336 indicates that the solenoid was unresponsive, a diagnostic message is sent to master 306. Another stored attribute is the concentration level of chemical emissions, measured initially after manufacture or during the last valve servicing. In this case, diagnostic circuit 338 receives the output from emissions sensor 350 and when the concentration of the organic chemical exceeds a stored limit, the concentration value is transmitted to master 306. Alternatively, a value representative of the chemical concentration is transmitted to master 306.
Cavitation and the integrity of valve stem and cage assemblies (i.e. valve trim) may also be diagnosed using the present invention. When the frequency spectra from acoustic sensor 348 matches a stored frequency spectra representative of cavitation noise in pipe 302 or noise from the valve trim, a cavitation value or a trim wear WO 95/06276 PCTlUS94/07914 ~1~~8~~
value is reported to master 306 through circuit 358.
Cavitation noise occurs at frequencies greater than 10 MHz, while trim vibration occurs in the 5-200 Hz range, and therefore is easily distinguishable from other pipe noises at lower frequencies. Broken actuator components can also be diagnosed. In this mode, a ruptured actuator diaphragm, a broken valve stem or plugged supply pressure is identified where the sensed position signal is constant when command output 335 changes.
Diagnostic circuit 338 sends an alarm or alert when the sensed position signal is constant while command output 335 changes a predetermined amount over a specific time.
Thermal history also assists in planning preventive maintenance for valves components which fail frequently or which are time-consuming to repair, such as electronics components in positioners. In this mode, diagnostic circuit 338 logs different categories of thermal events in storage 354 and provides this data to master 306 through circuit 358. For example, certain positioner components have a predicted mean time between failure (MTBF) of 1.9 years when operated at 100 relative humidity and at a temperature of 150°F.
Maintenance can be scheduled before the MTBF, 1.9 years, has elapsed since the last maintenance. Only a small portion of storage 354 is dedicated to this function, since the data is stored and uploaded at specific time intervals calculated to use only~a portion of storage 354. Newly stored data is written over previous data.
Positioner 310 also functions as a field mounted data logger. In this mode, circuit 338 logs relevant process variables for a short duration to record process dynamics and positioner response. The logged information is uploaded through circuit 358 to master 306, for process modeling and process upset correlation.
WO 95!06276 PCT/CTS94107914 Precise modeling is possible because both process and positioner dynamics are in a similar logging mode.
State variables at the time of valve maintenance are recorded for uploading and planning maintenance.
In order to set the proper spring preload force in a positioner, a benchset operation is performed. Usual practice requires initial setting of the stroke position (i.e. 100 position), zero position, limit stops and the stiffness of the actuator spring so the valve is properly configured for the process it will control. This process is iterative and time consuming and typically takes between one and four hours to complete for prior art ~positioners, since the sensed stem position and the sensed control pressure are not available to the operator. In the present invention, benchset operations are more efficient and precise than before. In FIG. 9, a positioner 500 operates in a benchset mode, where it is connected to a valve body 502 mechanically coupled to an actuator 504 but disconnected from the process. Positioner 500 receives benchset commands from and transmits benchsetting parameters to hand-held communicator 508, or alternatively a properly configured PC. A receiving circuit 520 connected to a two wire cable 522 translates commands from communicator 508 and sends them to a common bus 524 connecting a benchset control circuit 526 and a transmit circuit 528 for translating benchset data into a format communicable to master 508. Control circuit 526 is preferably implemented as a CMOS microprocessor including a non-volatile storage 530, although it could be implemented in analog circuitry as well. Control circuit 526 pravides an electrical command output to a transducer circuit and pneumatics section 542, which uses known I~P
technology to produce control pressure 540. A sensing WO 95/06276 a ~. ~ PCT/US94/07914 circuit 532 senses the position of a stem 534 in valve 502 via position sensor 536 and a pressure sensor 538 senses control pressure 540.
The first segment of a benchset operation calculates the spring constant of spring 506 while actuator 504 is disconnected so as to remove frictional effects. While positioner 500 is connected solely to valve 502, the operator sends a benchset command to circuit 526 through receiving circuit 520. Next, the operator enters into master 508 the desired initial control pressure, Po, and the end control pressure P1~, for use in control circuit 526 via receiving circuit 520. Control circuit 526 commands pneumatics 542 to ramp between pressure Po and P1~ while sending the sensed position signal to master 508 for display through transmit circuit 528. Control circuit 526 stored the sensed position corresponding to pressures Po and pressure P1~, and stores them in storage 530. The spring constant KS is calculated in circuit 526 according to the equation:
K _ C Ps-PR) AE Fs-Fn s Ys_Yo where y, is the valve position at 100 of stroke, yo is the valve position at 0~ of stroke, AE is the effective area of the diaphragm, PS is the control pressure at 100 stroke' and PR is the control pressure at 0~ stroke.
When fine control is required, the spring constant is calculated using an air spring constant as well. After connecting valve 502 to actuator 504, the frictional forces and the preload force on spring 506 is measured.
The operator enters valve stem positions corresponding to 0~ and 100 travel (yo and yl~), the line pressure in the installation, PL, and a seating pressure safety factor, SM, related to the amount of pressure which should be applied to valve 502 after the valve plug is seated. While circuit 526 sends a control signal to pneumatics 542 to cycle positioner 500 from 0~ travel and 100 travel and back to 0~, the sensed control pressure is stored in storage 530 at various positions:
PM is the control pressure just before the valve stem overcomes the frictional forces and moves, PR is the control pressure just after the stem has moved, PD is the control pressure at 25~ of positional span with the stem moving towards the closed position, PU is the control pressure at 75~ with the stem moving towards the fully open position and F; is the preload force on the spring, as sampled at 0~ position. The force signal is most cost effectively and efficiently sampled by dividing the output from pressure sensor 538 by the area of the actuator diaphragm, AE, but alternatively may be derived from a load cell, not shown. Circuit 526 now calculates and stores the static frictional force, FS, given by Fs- ~ PM PR) AE FD
and the dynamic frictional force opposing stem motion, FD:
FD. ~PD_PU) 2s The most time-consuming and iterative part of a benchset operation with a prior art positioner is for the operator to set the spring preload force by manually adjusting a nut 544 on the valve stem which changes the force on spring 506. However, a force balance equation can be derived for the positioner as connected to the WO 95/06276 ~ 6 ~ PCT/L1S94107914 actuator and valve and solved for the desired position, ys. The equation calculated in circuit 526 is:
Ff+F.i+PLAv AA ( Po-Pioo) YS' K +Yo-Yioo s where all but A" (the effective area of the actuator diaphragm) are previously defined. The quantity YS is the desired stem position at which nut 544 must be positioned in order to achieve the necessary preload force at specified control pressure and corresponding stem positions. During the manual adjustment of nut 544, the sensed position signal is transmitted through transmit circuit 528 to communicator 508, displayed as a percentage of the required stem travel adjustment.
Although the present invention has been described with reference to preferred embodiments, workers skilled in the art will recognize that changes may be made in form and detail without departing from the spirit and scope of the invention.
Claims (18)
1. A valve positioner for use in a process-control system for providing a control pressure to a valve actuator mechanically coupled to a valve, the positioner comprising:
receiving means coupled to a communications loop, for receiving an input representative of a desired valve position;
sensing means for providing state variables representative of a process, one state variable representative of the position of the valve and the other representative of the control pressure;
transducer means receiving a source of pressurized air and a command output, for providing the control pressure as a function of the command output; and control means coupled to the sensing means and the receiving means, for providing the command output as a function of the desired valve position, the sensed position and the time derivative of the sensed pressure;
wherein the time derivative of sensed pressure provides reduced overshoot in the valve position.
receiving means coupled to a communications loop, for receiving an input representative of a desired valve position;
sensing means for providing state variables representative of a process, one state variable representative of the position of the valve and the other representative of the control pressure;
transducer means receiving a source of pressurized air and a command output, for providing the control pressure as a function of the command output; and control means coupled to the sensing means and the receiving means, for providing the command output as a function of the desired valve position, the sensed position and the time derivative of the sensed pressure;
wherein the time derivative of sensed pressure provides reduced overshoot in the valve position.
2. The positioner of claim 1, where the input to the receiving means is a 4-20 mA current having a magnitude representative of the desired valve position.
3. The positioner of claim 1, where the input to the receiving means is formatted according to a digital communications protocol.
4. The positioner of claim 1, 2 or 3, where the control means is implemented in a CMOS microprocessor.
5. The positioner of claim 1 to 4, where the control means uses an adaptive control algorithm having at least one PID constant which changes as a function of the sensed-state variables.
6. The positioner of claim 1 to 5, where the state variable representative of the valve position is temperature compensated.
7. The positioner of claim 6, where the sensing means further comprise a sensor for detecting force.
8. The positioner of claim 1 to 7, further comprising diagnostic means coupled to the sensing means, for storing an attribute of the valve and providing a diagnostic output as a function of the stored valve attribute and at least one of the state variables.
9. A valve positioner for use in a process-control system for providing a control pressure to a valve actuator mechanically coupled to a valve, the positioner comprising:
receiving means coupled to a communications loop, for receiving an input representative of a desired valve position;
sensing means for providing state variables representative of a process, one state variable representative of the position of the valve and the other representative of a force required to move the valve;
transducer means receiving a source of pressurized air and a command output, for providing the control pressure as a function of the command output; and control means coupled to the sensing means and the receiving means, for providing the command output as a function of the desired valve position, the time derivative of the sensed force and the sensed position;
wherein the time derivative of the sensed force and sensed position provide reduced overshoot in the valve position.
receiving means coupled to a communications loop, for receiving an input representative of a desired valve position;
sensing means for providing state variables representative of a process, one state variable representative of the position of the valve and the other representative of a force required to move the valve;
transducer means receiving a source of pressurized air and a command output, for providing the control pressure as a function of the command output; and control means coupled to the sensing means and the receiving means, for providing the command output as a function of the desired valve position, the time derivative of the sensed force and the sensed position;
wherein the time derivative of the sensed force and sensed position provide reduced overshoot in the valve position.
10. A valve positioner for providing a control pressure to a valve actuator mechanically coupled to a valve, the positioner communication with a master over a communications loop, the positioner comprising:
receiving means coupled to the communication loop, for receiving an input representative of a desired valve position;
sensing means for sensing a set of physical parameters affecting the valve, the set of sensed physical parameters including a position of the valve;
control means coupled to the sensing means and the receiving means, for providing a command output as a function of the desired valve position and the sensed valve position;
transducer means receiving a source of pressurized air and the command output, for providing the control pressure as a function of the command output; and correction means for storing a valve attribute of the valve which is affected by one of the physical parameters, the correction means compensating the command output as a function of the sensed physical parameter and the stored valve attribute.
receiving means coupled to the communication loop, for receiving an input representative of a desired valve position;
sensing means for sensing a set of physical parameters affecting the valve, the set of sensed physical parameters including a position of the valve;
control means coupled to the sensing means and the receiving means, for providing a command output as a function of the desired valve position and the sensed valve position;
transducer means receiving a source of pressurized air and the command output, for providing the control pressure as a function of the command output; and correction means for storing a valve attribute of the valve which is affected by one of the physical parameters, the correction means compensating the command output as a function of the sensed physical parameter and the stored valve attribute.
11. The valve positioner of claim 10, where the receiving means is adapted to receive a valve attribute over the loop, and the stored valve attribute is the flow through the valve as a function of valve position, and where the correction means compensates the command output as a function of the sensed flow and the stored flow attribute.
12. The valve positioner of claim 10 or 11, where the sensing means include a sensor for sensing the force required to move the valve, and the stored attribute is the force attribute of the valve as a function of position, and where the correction means compensates the command output as a function of the sensed force and the stored force attribute.
13. The positioner of claim 10, 11 or 12, where the input to the receiving means is a 4-20 mA current having a magnitude representative of the desired valve position.
14. The positioner of any one of claims 10 to 13, where the input to the receiver means is formatted according to ~
a digital communications protocol.
a digital communications protocol.
15. The positioner of any one of claims 10 to 14, where the sensed position value is compensated for temperature effects.
16. The positioner of any one of claims 10 to 15, where one of the set of sensed physical parameters is the control pressure, and where such control pressure is compensated for the air spring effect.
17. A valve positioner for providing a control pressure to an actuator diaphragm mechanically coupled to a valve spring, the valve spring requiring a preload force in order for the positioner to drive a valve stem between a first control pressure and a first corresponding valve stem position and a second control pressure and a second corresponding valve stem position, the positioner comprising:
means for receiving communications representative of the first and second control pressures and their corresponding valve stem positions;
means for sensing the valve position and the control pressure;
transducer means receiving a supply of air, for providing the control pressure as a function of a command output;
benchsetting means receiving the sensed position and control pressure, the benchsetting means providing a command output corresponding to the first and the second control pressures and ramping therebetween, the benchsetting means storing the sensed control pressure at predetermined stem positions, and for providing the preload force as a function of the stored control pressures, the first and second control pressures and their corresponding positions; and means for transmitting the preload force to a master;
wherein the benchsetting means calculates a spring constant according to the equation:
where y s is the valve position at 100% of stroke, y o is the valve position at 0% of stroke, A E is the effective area of the diagram, P s is the control pressure at 100% stroke and P R is the control pressure at 0% stroke, F s is the static frictional force, and F D is the dynamic frictional force.
means for receiving communications representative of the first and second control pressures and their corresponding valve stem positions;
means for sensing the valve position and the control pressure;
transducer means receiving a supply of air, for providing the control pressure as a function of a command output;
benchsetting means receiving the sensed position and control pressure, the benchsetting means providing a command output corresponding to the first and the second control pressures and ramping therebetween, the benchsetting means storing the sensed control pressure at predetermined stem positions, and for providing the preload force as a function of the stored control pressures, the first and second control pressures and their corresponding positions; and means for transmitting the preload force to a master;
wherein the benchsetting means calculates a spring constant according to the equation:
where y s is the valve position at 100% of stroke, y o is the valve position at 0% of stroke, A E is the effective area of the diagram, P s is the control pressure at 100% stroke and P R is the control pressure at 0% stroke, F s is the static frictional force, and F D is the dynamic frictional force.
18. The positioner of claim 17, where the spring constant is compensated for the air spring effect in the actuator.
Applications Claiming Priority (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US08/112,694 | 1993-08-25 | ||
US08/112,694 US5549137A (en) | 1993-08-25 | 1993-08-25 | Valve positioner with pressure feedback, dynamic correction and diagnostics |
PCT/US1994/007914 WO1995006276A1 (en) | 1993-08-25 | 1994-07-14 | Valve positioner with pressure feedback, dynamic correction and diagnostics |
Publications (2)
Publication Number | Publication Date |
---|---|
CA2166867A1 CA2166867A1 (en) | 1995-03-02 |
CA2166867C true CA2166867C (en) | 2004-06-01 |
Family
ID=22345360
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
CA002166867A Expired - Fee Related CA2166867C (en) | 1993-08-25 | 1994-07-14 | Valve positioner with pressure feedback, dynamic correction and diagnostics |
Country Status (9)
Country | Link |
---|---|
US (3) | US5549137A (en) |
EP (2) | EP0957418B1 (en) |
JP (1) | JP3595554B2 (en) |
CN (1) | CN1072816C (en) |
BR (1) | BR9407585A (en) |
CA (1) | CA2166867C (en) |
DE (2) | DE69432029T2 (en) |
SG (1) | SG44472A1 (en) |
WO (1) | WO1995006276A1 (en) |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CN105114692A (en) * | 2008-02-29 | 2015-12-02 | 费希尔控制国际公司 | Diagnostic method for detecting control valve component failure |
Families Citing this family (309)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE4431463C2 (en) * | 1994-09-03 | 1997-10-16 | Honeywell Ag | Compact controller for a control valve |
US5706007A (en) * | 1995-01-03 | 1998-01-06 | Smar Research Corporation | Analog current / digital bus protocol converter circuit |
DE19540441A1 (en) * | 1995-10-27 | 1997-04-30 | Schubert & Salzer Control Syst | Microprocessor-controlled setting regulator for flow control valve in equipment and plant |
US5992229A (en) * | 1996-02-05 | 1999-11-30 | Neles-Jamesbury Oy | Method and equipment for determining the performance of control valve |
US5764891A (en) * | 1996-02-15 | 1998-06-09 | Rosemount Inc. | Process I/O to fieldbus interface circuit |
US7949495B2 (en) | 1996-03-28 | 2011-05-24 | Rosemount, Inc. | Process variable transmitter with diagnostics |
US6017143A (en) | 1996-03-28 | 2000-01-25 | Rosemount Inc. | Device in a process system for detecting events |
US8290721B2 (en) | 1996-03-28 | 2012-10-16 | Rosemount Inc. | Flow measurement diagnostics |
DE19612370C1 (en) * | 1996-03-28 | 1997-11-20 | Samson Ag | Flow determining apparatus for process fluid at regulating device |
US6539267B1 (en) | 1996-03-28 | 2003-03-25 | Rosemount Inc. | Device in a process system for determining statistical parameter |
US6654697B1 (en) | 1996-03-28 | 2003-11-25 | Rosemount Inc. | Flow measurement with diagnostics |
US5828851A (en) * | 1996-04-12 | 1998-10-27 | Fisher-Rosemount Systems, Inc. | Process control system using standard protocol control of standard devices and nonstandard devices |
US6032208A (en) * | 1996-04-12 | 2000-02-29 | Fisher-Rosemount Systems, Inc. | Process control system for versatile control of multiple process devices of various device types |
US5862052A (en) * | 1996-04-12 | 1999-01-19 | Fisher-Rosemount Systems, Inc. | Process control system using a control strategy implemented in a layered hierarchy of control modules |
US5768119A (en) * | 1996-04-12 | 1998-06-16 | Fisher-Rosemount Systems, Inc. | Process control system including alarm priority adjustment |
US5909368A (en) | 1996-04-12 | 1999-06-01 | Fisher-Rosemount Systems, Inc. | Process control system using a process control strategy distributed among multiple control elements |
US5940294A (en) * | 1996-04-12 | 1999-08-17 | Fisher-Rosemont Systems, Inc. | System for assisting configuring a process control environment |
US6098116A (en) * | 1996-04-12 | 2000-08-01 | Fisher-Rosemont Systems, Inc. | Process control system including a method and apparatus for automatically sensing the connection of devices to a network |
US6868538B1 (en) | 1996-04-12 | 2005-03-15 | Fisher-Rosemount Systems, Inc. | Object-oriented programmable controller |
US5838563A (en) * | 1996-04-12 | 1998-11-17 | Fisher-Rosemont Systems, Inc. | System for configuring a process control environment |
US5995916A (en) * | 1996-04-12 | 1999-11-30 | Fisher-Rosemount Systems, Inc. | Process control system for monitoring and displaying diagnostic information of multiple distributed devices |
US6178956B1 (en) * | 1996-05-20 | 2001-01-30 | Borgwarner Inc. | Automotive fluid control system with pressure balanced solenoid valve |
US5720313A (en) * | 1996-05-24 | 1998-02-24 | Weiss Construction Co. | Flow rate control system |
FI104129B1 (en) * | 1996-06-11 | 1999-11-15 | Neles Jamesbury Oy | Procedure for monitoring the condition of control valve |
EP0825506B1 (en) | 1996-08-20 | 2013-03-06 | Invensys Systems, Inc. | Methods and apparatus for remote process control |
US6047222A (en) * | 1996-10-04 | 2000-04-04 | Fisher Controls International, Inc. | Process control network with redundant field devices and buses |
JP2001501760A (en) | 1996-10-04 | 2001-02-06 | フィッシャー コントロールズ インターナショナル,インコーポレイテッド | Maintenance interface device for use in process control networks |
US6044305A (en) * | 1996-10-04 | 2000-03-28 | Fisher Controls International, Inc. | Method and apparatus for debugging and tuning a process control network having distributed control functions |
DE69710201T3 (en) | 1996-10-04 | 2007-07-05 | Fisher Controls International Llc (N.D.Ges.D.Staates Delaware) | NETWORK ACCESS INTERFACE FOR PROCESS CONTROL NETWORK |
US5970430A (en) * | 1996-10-04 | 1999-10-19 | Fisher Controls International, Inc. | Local device and process diagnostics in a process control network having distributed control functions |
DE19643297C1 (en) * | 1996-10-21 | 1998-03-12 | Samson Ag | In-service monitoring method for servo equipment |
US6601005B1 (en) | 1996-11-07 | 2003-07-29 | Rosemount Inc. | Process device diagnostics using process variable sensor signal |
US6449574B1 (en) | 1996-11-07 | 2002-09-10 | Micro Motion, Inc. | Resistance based process control device diagnostics |
US6519546B1 (en) | 1996-11-07 | 2003-02-11 | Rosemount Inc. | Auto correcting temperature transmitter with resistance based sensor |
US6754601B1 (en) | 1996-11-07 | 2004-06-22 | Rosemount Inc. | Diagnostics for resistive elements of process devices |
US6434504B1 (en) | 1996-11-07 | 2002-08-13 | Rosemount Inc. | Resistance based process control device diagnostics |
US5848609A (en) * | 1996-11-26 | 1998-12-15 | Worcester Control Licenseco Inc. | Digital valve positioner |
US5980078A (en) * | 1997-02-14 | 1999-11-09 | Fisher-Rosemount Systems, Inc. | Process control system including automatic sensing and automatic configuration of devices |
DE19713668A1 (en) * | 1997-04-02 | 1998-10-08 | Wagner Int | Device and method for measuring and regulating the flow of a fluid |
US5913183A (en) * | 1997-04-07 | 1999-06-15 | Taiwan Semiconductor Manufacturing Company, Ltd. | Check device for air activated pressure valve |
JPH10306801A (en) * | 1997-05-01 | 1998-11-17 | Smc Corp | Control method of automatic control pneumatic apparatus |
EP1452937B1 (en) * | 1997-07-23 | 2006-03-22 | Dresser, Inc. | Valve positioner system |
US6272401B1 (en) | 1997-07-23 | 2001-08-07 | Dresser Industries, Inc. | Valve positioner system |
US6035878A (en) * | 1997-09-22 | 2000-03-14 | Fisher Controls International, Inc. | Diagnostic device and method for pressure regulator |
US6056008A (en) * | 1997-09-22 | 2000-05-02 | Fisher Controls International, Inc. | Intelligent pressure regulator |
US6014612A (en) * | 1997-10-02 | 2000-01-11 | Fisher Controls International, Inc. | Remote diagnostics in a process control network having distributed control functions |
CN1177266C (en) * | 1997-10-13 | 2004-11-24 | 罗斯蒙德公司 | Communication technique for field device in industrial process |
US6128541A (en) * | 1997-10-15 | 2000-10-03 | Fisher Controls International, Inc. | Optimal auto-tuner for use in a process control network |
FR2770276B1 (en) * | 1997-10-24 | 2000-01-07 | Framatome Sa | METHOD AND DEVICE FOR CONTROLLING AN ALL OR NOTHING PNEUMATIC CONTROL VALVE |
US6088665A (en) * | 1997-11-03 | 2000-07-11 | Fisher Controls International, Inc. | Schematic generator for use in a process control network having distributed control functions |
US5997280A (en) * | 1997-11-07 | 1999-12-07 | Maxon Corporation | Intelligent burner control system |
US6283138B1 (en) | 1998-04-24 | 2001-09-04 | Anderson, Greenwood Lp | Pressure relief valve monitoring device |
FR2779227B1 (en) * | 1998-05-28 | 2000-08-18 | Snecma | FLUID FLOW MEASUREMENT |
JP2000035003A (en) * | 1998-07-16 | 2000-02-02 | Smc Corp | Positioner and method for setting thereof |
US6341238B1 (en) * | 1998-10-01 | 2002-01-22 | United Technologies Corporation | Robust engine variable vane monitor logic |
AU1445000A (en) * | 1998-10-17 | 2000-05-08 | Rosemount Analytical Inc | Power positioner with digital communication |
US6611775B1 (en) | 1998-12-10 | 2003-08-26 | Rosemount Inc. | Electrode leakage diagnostics in a magnetic flow meter |
US6615149B1 (en) | 1998-12-10 | 2003-09-02 | Rosemount Inc. | Spectral diagnostics in a magnetic flow meter |
JP3924386B2 (en) * | 1998-12-28 | 2007-06-06 | 日本エム・ケー・エス株式会社 | Flow control system |
AU3211900A (en) * | 1999-01-20 | 2000-08-07 | Mykrolis Corporation | Flow controller |
US6490493B1 (en) | 1999-01-21 | 2002-12-03 | Rosemount Inc. | Industrial process device management software |
FI111106B (en) * | 1999-02-19 | 2003-05-30 | Neles Controls Oy | Procedure for setting a process control loop in an industrial process |
US6510351B1 (en) | 1999-03-15 | 2003-01-21 | Fisher-Rosemount Systems, Inc. | Modifier function blocks in a process control system |
DE19921828C2 (en) * | 1999-05-11 | 2001-06-07 | Samson Ag | Method for operating a positioner and positioner using this method |
US6754885B1 (en) | 1999-05-17 | 2004-06-22 | Invensys Systems, Inc. | Methods and apparatus for controlling object appearance in a process control configuration system |
AU5273100A (en) | 1999-05-17 | 2000-12-05 | Foxboro Company, The | Methods and apparatus for control configuration with versioning, security, composite blocks, edit selection, object swapping, formulaic values and other aspects |
US7089530B1 (en) | 1999-05-17 | 2006-08-08 | Invensys Systems, Inc. | Process control configuration system with connection validation and configuration |
US6788980B1 (en) | 1999-06-11 | 2004-09-07 | Invensys Systems, Inc. | Methods and apparatus for control using control devices that provide a virtual machine environment and that communicate via an IP network |
US6356191B1 (en) | 1999-06-17 | 2002-03-12 | Rosemount Inc. | Error compensation for a process fluid temperature transmitter |
EP1247268B2 (en) | 1999-07-01 | 2009-08-05 | Rosemount Inc. | Low power two-wire self validating temperature transmitter |
US6505517B1 (en) | 1999-07-23 | 2003-01-14 | Rosemount Inc. | High accuracy signal processing for magnetic flowmeter |
US6510352B1 (en) | 1999-07-29 | 2003-01-21 | The Foxboro Company | Methods and apparatus for object-based process control |
US6701274B1 (en) | 1999-08-27 | 2004-03-02 | Rosemount Inc. | Prediction of error magnitude in a pressure transmitter |
US6618745B2 (en) | 1999-09-10 | 2003-09-09 | Fisher Rosemount Systems, Inc. | Linking device in a process control system that allows the formation of a control loop having function blocks in a controller and in field devices |
US6556145B1 (en) | 1999-09-24 | 2003-04-29 | Rosemount Inc. | Two-wire fluid temperature transmitter with thermocouple diagnostics |
US6711629B1 (en) | 1999-10-18 | 2004-03-23 | Fisher-Rosemount Systems, Inc. | Transparent support of remote I/O in a process control system |
US6535827B1 (en) | 1999-10-28 | 2003-03-18 | Mpr Associates, Inc. | Method and apparatus for detecting and isolating a rupture in fluid distribution system |
US6357335B1 (en) | 1999-12-23 | 2002-03-19 | Sox Corporation | Pneumatic volume booster for valve positioner |
DE20115473U1 (en) * | 2001-09-19 | 2003-02-20 | Biester Klaus | Universal energy supply system |
DE20115471U1 (en) * | 2001-09-19 | 2003-02-20 | Biester Klaus | Universal energy supply system |
US7615893B2 (en) * | 2000-05-11 | 2009-11-10 | Cameron International Corporation | Electric control and supply system |
DE20115474U1 (en) * | 2001-09-19 | 2003-02-20 | Biester Klaus | DC converter device |
DE20018560U1 (en) * | 2000-10-30 | 2002-03-21 | Cameron Gmbh | Control and supply system |
US6745107B1 (en) * | 2000-06-30 | 2004-06-01 | Honeywell Inc. | System and method for non-invasive diagnostic testing of control valves |
US6735484B1 (en) | 2000-09-20 | 2004-05-11 | Fargo Electronics, Inc. | Printer with a process diagnostics system for detecting events |
DE10054288A1 (en) * | 2000-11-02 | 2002-05-16 | Festo Ag & Co | Sensor arrangement for recording at least one measured value |
JPWO2002041917A1 (en) * | 2000-11-22 | 2004-03-25 | 三菱ウェルファーマ株式会社 | Ophthalmic agent |
US6814096B2 (en) * | 2000-12-15 | 2004-11-09 | Nor-Cal Products, Inc. | Pressure controller and method |
US6644332B1 (en) * | 2001-01-25 | 2003-11-11 | Fisher Controls International Inc. | Method and apparatus for multiple-input-multiple-output control of a valve/actuator plant |
US6954713B2 (en) * | 2001-03-01 | 2005-10-11 | Fisher-Rosemount Systems, Inc. | Cavitation detection in a process plant |
EP1417552B1 (en) * | 2001-04-05 | 2005-12-14 | Fisher Controls International Llc | System to manually initiate an emergency shutdown test and collect diagnostic data in a process control environment |
US7621293B2 (en) * | 2001-04-05 | 2009-11-24 | Fisher Controls International Llc | Versatile emergency shutdown device controller implementing a pneumatic test for a system instrument device |
US6382226B1 (en) | 2001-04-17 | 2002-05-07 | Fisher Controls International, Inc. | Method for detecting broken valve stem |
US6629059B2 (en) * | 2001-05-14 | 2003-09-30 | Fisher-Rosemount Systems, Inc. | Hand held diagnostic and communication device with automatic bus detection |
DE10128448B4 (en) * | 2001-06-12 | 2008-01-24 | Abb Patent Gmbh | Method for diagnosing a process valve |
FR2827674B1 (en) * | 2001-07-20 | 2003-10-03 | Chpolansky Ets | METHOD AND APPARATUS FOR TESTING A VALVE WITH A LIQUID FILLING, WITHOUT PRIOR OPENING OF THE SHUTTER |
EP1288757A1 (en) * | 2001-08-07 | 2003-03-05 | Siemens Aktiengesellschaft | Method and process control system for operating a technical installation |
US6772036B2 (en) | 2001-08-30 | 2004-08-03 | Fisher-Rosemount Systems, Inc. | Control system using process model |
US6655151B2 (en) † | 2001-09-07 | 2003-12-02 | Honeywell International, Inc. | Method for controlling fuel flow to a gas turbine engine |
US7020271B2 (en) * | 2003-06-12 | 2006-03-28 | Barbara Isabel Hummel | Ring control device |
DE20115475U1 (en) * | 2001-09-19 | 2003-02-20 | Biester Klaus | DC converter device |
US6725876B2 (en) * | 2001-10-15 | 2004-04-27 | Woodward Governor Company | Control valve with integrated electro-hydraulic actuator |
ES2256142T3 (en) | 2001-11-23 | 2006-07-16 | Siemens Aktiengesellschaft | METHOD FOR CONTINUOUS REGULATION OF A POSITION OF A REGULATION VALVE. |
TW571182B (en) * | 2001-12-04 | 2004-01-11 | Smc Kk | Flow rate control apparatus |
JP3568930B2 (en) * | 2001-12-04 | 2004-09-22 | Smc株式会社 | Flow control device |
US7426452B2 (en) | 2001-12-06 | 2008-09-16 | Fisher-Rosemount Systems. Inc. | Dual protocol handheld field maintenance tool with radio-frequency communication |
ATE308775T1 (en) * | 2001-12-06 | 2005-11-15 | Fisher Rosemount Systems Inc | INTRINSICALLY SAFE FIELD EQUIPMENT MAINTENANCE TOOL |
US20030229472A1 (en) * | 2001-12-06 | 2003-12-11 | Kantzes Christopher P. | Field maintenance tool with improved device description communication and storage |
US20030204373A1 (en) * | 2001-12-06 | 2003-10-30 | Fisher-Rosemount Systems, Inc. | Wireless communication method between handheld field maintenance tools |
US7039744B2 (en) * | 2002-03-12 | 2006-05-02 | Fisher-Rosemount Systems, Inc. | Movable lead access member for handheld field maintenance tool |
US7027952B2 (en) * | 2002-03-12 | 2006-04-11 | Fisher-Rosemount Systems, Inc. | Data transmission method for a multi-protocol handheld field maintenance tool |
US20040002950A1 (en) | 2002-04-15 | 2004-01-01 | Brennan Sean F. | Methods and apparatus for process, factory-floor, environmental, computer aided manufacturing-based or other control system using hierarchically enumerated data set |
US6999853B2 (en) * | 2002-05-03 | 2006-02-14 | Fisher Controls International Llc. | Methods and apparatus for operating and performing diagnostics in a control loop of a control valve |
US6678584B2 (en) * | 2002-05-03 | 2004-01-13 | Fisher Controls International Llc | Method and apparatus for performing diagnostics in a control loop of a control valve |
DE10221088A1 (en) * | 2002-05-11 | 2003-11-27 | Braun Gmbh | Electronic circuit with at least one input for selecting a state of the electronic circuit |
JP4035585B2 (en) * | 2002-06-13 | 2008-01-23 | 株式会社山武 | Abnormality diagnosis device |
JP2005534111A (en) | 2002-07-19 | 2005-11-10 | マイクロリス・コーポレーション | Liquid flow controller and precision dispensing device and system |
US7240906B2 (en) | 2002-12-04 | 2007-07-10 | Daimlerchrysler Corporation | Hydro-pneumatic suspension system |
US10261506B2 (en) * | 2002-12-05 | 2019-04-16 | Fisher-Rosemount Systems, Inc. | Method of adding software to a field maintenance tool |
KR100625071B1 (en) | 2002-12-19 | 2006-09-20 | 가부시키가이샤 후지킨 | Method for closing fluid passage, and water hammerless closing device |
US7089086B2 (en) * | 2003-02-14 | 2006-08-08 | Dresser, Inc. | Method, system and storage medium for performing online valve diagnostics |
US8216717B2 (en) | 2003-03-06 | 2012-07-10 | Fisher-Rosemount Systems, Inc. | Heat flow regulating cover for an electrical storage cell |
US6904476B2 (en) | 2003-04-04 | 2005-06-07 | Rosemount Inc. | Transmitter with dual protocol interface |
US7512521B2 (en) | 2003-04-30 | 2009-03-31 | Fisher-Rosemount Systems, Inc. | Intrinsically safe field maintenance tool with power islands |
US7054695B2 (en) | 2003-05-15 | 2006-05-30 | Fisher-Rosemount Systems, Inc. | Field maintenance tool with enhanced scripts |
US7526802B2 (en) | 2003-05-16 | 2009-04-28 | Fisher-Rosemount Systems, Inc. | Memory authentication for intrinsically safe field maintenance tools |
US8874402B2 (en) | 2003-05-16 | 2014-10-28 | Fisher-Rosemount Systems, Inc. | Physical memory handling for handheld field maintenance tools |
US7036386B2 (en) * | 2003-05-16 | 2006-05-02 | Fisher-Rosemount Systems, Inc. | Multipurpose utility mounting assembly for handheld field maintenance tool |
US7199784B2 (en) * | 2003-05-16 | 2007-04-03 | Fisher Rosemount Systems, Inc. | One-handed operation of a handheld field maintenance tool |
US6925419B2 (en) | 2003-05-16 | 2005-08-02 | Fisher-Rosemount Systems, Inc. | Intrinsically safe field maintenance tool with removable battery pack |
US7280048B2 (en) * | 2003-08-07 | 2007-10-09 | Rosemount Inc. | Process control loop current verification |
US6917858B2 (en) * | 2003-08-29 | 2005-07-12 | Dresser, Inc. | Fluid regulation |
US8180466B2 (en) * | 2003-11-21 | 2012-05-15 | Rosemount Inc. | Process device with supervisory overlayer |
US20050150552A1 (en) * | 2004-01-06 | 2005-07-14 | Randy Forshey | Device, method, and system for controlling fluid flow |
JP4406292B2 (en) * | 2004-01-20 | 2010-01-27 | 株式会社フジキン | Water hammerless opening method of fluid passage and water hammerless opening device using the same |
US7761923B2 (en) | 2004-03-01 | 2010-07-20 | Invensys Systems, Inc. | Process control methods and apparatus for intrusion detection, protection and network hardening |
EP1733161A4 (en) * | 2004-04-05 | 2009-02-04 | Westlock Controls Corp | Device and method for pneumatic valve control |
DE102004022453B4 (en) * | 2004-05-06 | 2007-01-25 | Helmut Bälz GmbH | Valve control device with leakage rate consideration |
US7464721B2 (en) * | 2004-06-14 | 2008-12-16 | Rosemount Inc. | Process equipment validation |
CN1304760C (en) * | 2004-06-16 | 2007-03-14 | 陈城书 | Electrohydraulic tube for electrohydraulic chip |
US8636021B2 (en) * | 2004-07-08 | 2014-01-28 | Carleton Technologies, Inc. | Non-magnetic latching servo actuated valve |
US7637970B1 (en) | 2004-07-14 | 2009-12-29 | Marathon Ashland Petroleum Llc | Method and apparatus for recovery and recycling of hydrogen |
WO2006025550A1 (en) * | 2004-08-31 | 2006-03-09 | Asahi Organic Chemicals Industry Co., Ltd. | Fluid control device |
JP4461329B2 (en) * | 2004-08-31 | 2010-05-12 | 旭有機材工業株式会社 | Fluid control device |
JP2006070946A (en) | 2004-08-31 | 2006-03-16 | Asahi Organic Chem Ind Co Ltd | Control valve |
US9493936B2 (en) * | 2004-10-08 | 2016-11-15 | Sdb Ip Holdings, Llc | System, method, and apparatus for monitoring wear in a flush valve using pressure detection |
CN101103322B (en) * | 2004-11-03 | 2011-06-08 | 第四层联合公司 | Electrically controlled pressure relief valve |
US7504961B2 (en) * | 2005-03-31 | 2009-03-17 | Saudi Arabian Oil Company | Emergency isolation valve controller with integral fault indicator |
US8072343B2 (en) * | 2005-03-31 | 2011-12-06 | Saudi Arabian Oil Company | Local emergency isolation valve controller with diagnostic testing and trouble indicator |
US7493195B2 (en) * | 2005-05-20 | 2009-02-17 | Dresser, Inc. | Fluid regulation control |
US8112565B2 (en) | 2005-06-08 | 2012-02-07 | Fisher-Rosemount Systems, Inc. | Multi-protocol field device interface with automatic bus detection |
US7835295B2 (en) * | 2005-07-19 | 2010-11-16 | Rosemount Inc. | Interface module with power over Ethernet function |
US20070068225A1 (en) | 2005-09-29 | 2007-03-29 | Brown Gregory C | Leak detector for process valve |
EP1772673A1 (en) * | 2005-10-06 | 2007-04-11 | Siemens Aktiengesellschaft | Method and Device for Monitoring the Deposition of Solid Particles, in particular in the Fuel Line of a Gas Turbine |
US7814936B2 (en) * | 2005-11-16 | 2010-10-19 | Fisher Controls International Llc | Sound pressure level feedback control |
DE102005062421A1 (en) * | 2005-12-27 | 2007-06-28 | Vega Grieshaber Kg | Heating device for field device display module, has heating unit designed as heating foil to convert electric current into heat energy, where heating unit is coupled to display module, such that module is heated using heating unit |
US7818092B2 (en) * | 2006-01-20 | 2010-10-19 | Fisher Controls International Llc | In situ emission measurement for process control equipment |
US7283894B2 (en) | 2006-02-10 | 2007-10-16 | Dresser, Inc. | System and method for fluid regulation |
WO2007123753A2 (en) | 2006-03-30 | 2007-11-01 | Invensys Systems, Inc. | Digital data processing apparatus and methods for improving plant performance |
US8332567B2 (en) | 2006-09-19 | 2012-12-11 | Fisher-Rosemount Systems, Inc. | Apparatus and methods to communicatively couple field devices to controllers in a process control system |
US9411769B2 (en) | 2006-09-19 | 2016-08-09 | Fisher-Rosemount Systems, Inc. | Apparatus and methods to communicatively couple field devices to controllers in a process control system |
US7953501B2 (en) * | 2006-09-25 | 2011-05-31 | Fisher-Rosemount Systems, Inc. | Industrial process control loop monitor |
US8788070B2 (en) * | 2006-09-26 | 2014-07-22 | Rosemount Inc. | Automatic field device service adviser |
WO2008042290A2 (en) | 2006-09-29 | 2008-04-10 | Rosemount Inc. | Magnetic flowmeter with verification |
US8761196B2 (en) * | 2006-09-29 | 2014-06-24 | Fisher-Rosemount Systems, Inc. | Flexible input/output devices for use in process control systems |
US20080099705A1 (en) * | 2006-10-25 | 2008-05-01 | Enfield Technologies, Llc | Retaining element for a mechanical component |
DE102006055747B4 (en) * | 2006-11-25 | 2021-08-26 | Abb Ag | Method and arrangement for diagnosing an actuator |
DE202006020516U1 (en) * | 2006-12-21 | 2008-10-16 | Abb Ag | Control device for a pressure-medium-operated actuator |
US7539560B2 (en) * | 2007-01-05 | 2009-05-26 | Dresser, Inc. | Control valve and positioner diagnostics |
DE102007016817A1 (en) * | 2007-04-05 | 2008-10-09 | Siemens Ag | Method for checking the functionality of a positioning device |
DE102007020597A1 (en) * | 2007-05-02 | 2009-01-02 | Siemens Ag | Method for checking the functionality of a positioning device |
US8898036B2 (en) | 2007-08-06 | 2014-11-25 | Rosemount Inc. | Process variable transmitter with acceleration sensor |
US20090116969A1 (en) * | 2007-11-02 | 2009-05-07 | Mcvicker R Vance | Rail tank car evacuation and transfer system and method |
DE102007058517B4 (en) * | 2007-12-05 | 2018-07-26 | Abb Ag | Digital positioner |
DE102008028190A1 (en) * | 2008-06-12 | 2009-12-17 | Abb Technology Ag | Method for operating an electropneumatic valve |
DE102008028192A1 (en) * | 2008-06-12 | 2009-12-17 | Abb Technology Ag | Electropneumatic valve |
CN104407518B (en) | 2008-06-20 | 2017-05-31 | 因文西斯系统公司 | The system and method interacted to the reality and Simulation Facility for process control |
DK2307938T3 (en) | 2008-06-26 | 2013-12-16 | Belparts | FLOW CONTROL SYSTEM |
CN102216691B (en) * | 2008-07-25 | 2014-07-16 | 贝利莫控股公司 | Method for the hydraulic compensation and control of a heating or cooling system and compensation and control valve therefor |
DE102008038723B3 (en) * | 2008-08-12 | 2010-04-15 | Abb Technology Ag | Method and device for controlling an electropneumatic valve of a pressure-medium-actuated positioner |
US20100051110A1 (en) * | 2008-09-04 | 2010-03-04 | Ch2M Hill, Inc. | Gas actuated valve |
CN101676824B (en) * | 2008-09-16 | 2013-06-19 | 宝元数控精密股份有限公司 | Method for correcting output of hydraulic device |
CA2745428C (en) | 2008-12-05 | 2018-06-26 | Fisher Controls International Llc | Method and apparatus for operating field devices via a portable communicator |
DE102008062290A1 (en) | 2008-12-15 | 2010-06-24 | Abb Technology Ag | Method for diagnosing the state of wear of a valve arrangement for controlling a process medium flow |
DE102008062289A1 (en) | 2008-12-15 | 2010-06-24 | Abb Technology Ag | Method for the path and pressure sensoric wear condition determination of a valve mechanism and such a use valve arrangement |
DE102008064359A1 (en) | 2008-12-22 | 2010-07-01 | Abb Technology Ag | Method for the position-dependent determination of electronic wear status of a valve mechanism and pneumatic valve |
US8290631B2 (en) * | 2009-03-12 | 2012-10-16 | Emerson Process Management Power & Water Solutions, Inc. | Methods and apparatus to arbitrate valve position sensor redundancy |
WO2010117361A1 (en) * | 2009-04-07 | 2010-10-14 | Flowserve Management Company | Fluid control valve |
US7921734B2 (en) | 2009-05-12 | 2011-04-12 | Rosemount Inc. | System to detect poor process ground connections |
US8463964B2 (en) | 2009-05-29 | 2013-06-11 | Invensys Systems, Inc. | Methods and apparatus for control configuration with enhanced change-tracking |
US8127060B2 (en) | 2009-05-29 | 2012-02-28 | Invensys Systems, Inc | Methods and apparatus for control configuration with control objects that are fieldbus protocol-aware |
US8312892B2 (en) * | 2009-07-02 | 2012-11-20 | Fisher Controls International Llc | Device and method for determining a failure mode of a pneumatic control valve assembly |
US8286652B2 (en) * | 2009-09-22 | 2012-10-16 | Eaton Corporation | Configurable active jerk control |
US20110083746A1 (en) * | 2009-10-09 | 2011-04-14 | Cameron International Corporation | Smart valve utilizing a force sensor |
GB2510519B (en) * | 2009-10-09 | 2014-09-24 | Cameron Int Corp | Valve utilizing a force sensor |
US8996328B2 (en) * | 2009-12-29 | 2015-03-31 | Fisher Controls International Llc | Methods, apparatus and articles of manufacture to test safety instrumented system solenoids |
US8967590B2 (en) * | 2010-03-02 | 2015-03-03 | Westlock Controls Corporation | Micro-power generator for valve control applications |
JP5457249B2 (en) * | 2010-03-30 | 2014-04-02 | アズビル株式会社 | Positioner |
JP5426452B2 (en) * | 2010-03-30 | 2014-02-26 | アズビル株式会社 | Positioner |
JP5466068B2 (en) * | 2010-03-31 | 2014-04-09 | アズビル株式会社 | Electro-pneumatic positioner and electro-pneumatic converter |
EP2439602A1 (en) * | 2010-10-05 | 2012-04-11 | Siemens Aktiengesellschaft | Method for designing a process regulator |
US8587320B2 (en) | 2010-11-09 | 2013-11-19 | Honeywell International Inc. | System and method for testing a secondary servo control circuit in a redundant control configuration |
US20120167996A1 (en) * | 2011-01-05 | 2012-07-05 | Fisher Controls International Llc | Valve Controller Automatic Calibration Without User Interface |
CN102072489B (en) * | 2011-02-25 | 2012-07-04 | 凯明企业有限公司 | Combustor |
EP2500550A1 (en) * | 2011-03-16 | 2012-09-19 | Siemens Aktiengesellschaft | Stroke transmitter for gas turbine |
US9207670B2 (en) | 2011-03-21 | 2015-12-08 | Rosemount Inc. | Degrading sensor detection implemented within a transmitter |
NO332570B1 (en) * | 2011-04-06 | 2012-11-05 | Bjorge Solberg & Andersen As | Instrumentation system for determining risk factors |
US10851621B2 (en) * | 2011-04-06 | 2020-12-01 | MRC Solberg & Andersen AS | Instrumentation system for determining risk factors |
US8905371B2 (en) * | 2011-06-30 | 2014-12-09 | General Equipment And Manufacturing Company, Inc. | Valve signature diagnosis and leak test device |
US9020768B2 (en) | 2011-08-16 | 2015-04-28 | Rosemount Inc. | Two-wire process control loop current diagnostics |
JP5803552B2 (en) * | 2011-10-14 | 2015-11-04 | 東京エレクトロン株式会社 | Processing equipment |
JP5843669B2 (en) * | 2012-03-14 | 2016-01-13 | アズビル株式会社 | Maintenance target valve selection device and selection method |
US20130327403A1 (en) * | 2012-06-08 | 2013-12-12 | Kurtis Kevin Jensen | Methods and apparatus to control and/or monitor a pneumatic actuator |
JP6010353B2 (en) * | 2012-06-08 | 2016-10-19 | アズビル株式会社 | Positioner |
JP6010354B2 (en) * | 2012-06-08 | 2016-10-19 | アズビル株式会社 | Positioner |
US9411321B2 (en) * | 2012-06-20 | 2016-08-09 | Fisher Controls International Llc | Methods and system for minor loop feedback fallback |
US9528629B2 (en) * | 2012-06-27 | 2016-12-27 | Fisher Controls International Llc | Methods and apparatus to use vibration data to determine a condition of a process control device |
US9052240B2 (en) | 2012-06-29 | 2015-06-09 | Rosemount Inc. | Industrial process temperature transmitter with sensor stress diagnostics |
US9207129B2 (en) | 2012-09-27 | 2015-12-08 | Rosemount Inc. | Process variable transmitter with EMF detection and correction |
US9602122B2 (en) | 2012-09-28 | 2017-03-21 | Rosemount Inc. | Process variable measurement noise diagnostic |
US9534795B2 (en) * | 2012-10-05 | 2017-01-03 | Schneider Electric Buildings, Llc | Advanced valve actuator with remote location flow reset |
CN203979570U (en) * | 2012-10-22 | 2014-12-03 | 费希尔控制国际公司 | Control valve assembly |
GB201219184D0 (en) * | 2012-10-25 | 2012-12-12 | Buhler Sortex Ltd | Adaptive ejector valve array |
US10295080B2 (en) | 2012-12-11 | 2019-05-21 | Schneider Electric Buildings, Llc | Fast attachment open end direct mount damper and valve actuator |
DE102013001979A1 (en) * | 2013-02-05 | 2014-08-07 | Eisenmann Ag | pressure regulator |
AR095272A1 (en) * | 2013-03-14 | 2015-09-30 | Fisher Controls Int Llc | FORECAST OF VALVE IN FUNCTION OF LABORATORY ANALYSIS |
EP2971901B1 (en) * | 2013-03-15 | 2018-10-17 | Schneider Electric Buildings LLC | Advanced valve actuator with integral energy metering |
WO2014143922A1 (en) * | 2013-03-15 | 2014-09-18 | Schneider Electric Buildings, Llc | Advanced valve actuator with true flow feedback |
US9464422B2 (en) | 2013-03-15 | 2016-10-11 | Sdb Ip Holdings, Llc | System and method for a diaphragm valve controlled through measurement of water pressure and solenoid opening time |
US9423050B2 (en) * | 2013-04-09 | 2016-08-23 | Fisher Controls International Llc | Intelligent actuator and method of monitoring actuator health and integrity |
US9695956B2 (en) * | 2013-07-29 | 2017-07-04 | Dresser, Inc. | Spectral analysis based detector for a control valve |
US9304053B2 (en) | 2013-08-07 | 2016-04-05 | Dresser, Inc. | System to monitor performance of packing material in a seal |
US9423334B2 (en) * | 2013-08-27 | 2016-08-23 | Fisher Controls International Llc | Method of cavitation/flashing detection in or near a process control valve |
CN103472761B (en) * | 2013-09-10 | 2015-10-07 | 上海大众汽车有限公司 | Aerodynamic force loads closed-loop control device and method |
US9638344B2 (en) | 2013-11-19 | 2017-05-02 | Dresser, Inc. | System and method to monitor characteristics of an operating fluid in a process line |
EP3702873A1 (en) * | 2013-12-20 | 2020-09-02 | IMI Hydronic Engineering International SA | A valve and a method of operating a valve |
AR100120A1 (en) * | 2014-04-04 | 2016-09-14 | Fisher Controls Int Llc | SYSTEM AND METHOD FOR CONTROLLING A VALVE |
WO2015157936A1 (en) * | 2014-04-16 | 2015-10-22 | Changzhou Ruize Microelectronics Co., Ltd | A flow control valve servo mechanism based on a step motor and control method thereof |
CN105302169B (en) * | 2014-07-29 | 2021-02-12 | 盛美半导体设备(上海)股份有限公司 | Flow control method |
CN104265990A (en) * | 2014-09-13 | 2015-01-07 | 国家电网公司 | Position feedback device of shock-resisting automatic valve |
US10337647B2 (en) * | 2014-12-15 | 2019-07-02 | General Electric Company | Obstruction detection for a control valve |
ES2809553T3 (en) * | 2015-03-02 | 2021-03-04 | Ampo S Coop | System for the predictive maintenance of valves and procedure to carry out said maintenance |
US10684030B2 (en) | 2015-03-05 | 2020-06-16 | Honeywell International Inc. | Wireless actuator service |
US10378994B2 (en) * | 2015-03-05 | 2019-08-13 | Ai Alpine Us Bidco Inc. | Wireless vibration monitoring of movable engine parts |
FI126989B (en) | 2015-03-16 | 2017-09-15 | Metso Flow Control Oy | USING FLUID VALVE ASSEMBLY, PROCESS VALVE INSTALLATION AND USING FLUID VALVE ASSEMBLY IN PROCESS VALVE CONTROL |
JP6295221B2 (en) * | 2015-03-17 | 2018-03-14 | アズビル株式会社 | Positioner |
CA2980141C (en) * | 2015-03-19 | 2024-01-02 | Fisher Controls International Llc | Pressure control for calibrating process control devices |
US10845781B2 (en) * | 2015-03-23 | 2020-11-24 | Fisher Controls International Llc | Integrated process controller with loop and valve control capability |
US9739682B2 (en) * | 2015-05-04 | 2017-08-22 | Dresser, Inc. | Valve assembly calibration |
CN104832698B (en) * | 2015-05-22 | 2018-02-16 | 北方民族大学 | A kind of novel pneumatic intelligent positioner and its application method |
DE102015210208A1 (en) | 2015-06-02 | 2016-12-08 | Gemü Gebr. Müller Apparatebau Gmbh & Co. Kommanditgesellschaft | Method for determining a state variable of a valve diaphragm of an electronically controlled and motor-driven diaphragm valve, and diaphragm valve system |
JP6542052B2 (en) * | 2015-07-15 | 2019-07-10 | アズビル株式会社 | Positioner |
JP2017020631A (en) * | 2015-07-15 | 2017-01-26 | アズビル株式会社 | Positioner |
CN105000391A (en) * | 2015-07-29 | 2015-10-28 | 衡阳中微科技开发有限公司 | Method for stabilizing pressure of pneumatic transmission system through automatic pressure stabilizing device |
US10367612B2 (en) | 2015-09-30 | 2019-07-30 | Rosemount Inc. | Process variable transmitter with self-learning loop diagnostics |
US10371285B2 (en) * | 2015-10-27 | 2019-08-06 | Dresser, Llc | Predicting maintenance requirements for a valve assembly |
WO2017071753A1 (en) * | 2015-10-29 | 2017-05-04 | Festo Ag & Co. Kg | Fluid control device and method for operating a fluid control device |
US9665099B1 (en) | 2015-12-31 | 2017-05-30 | Google Inc. | Integrated valve for a legged robot |
US10503181B2 (en) * | 2016-01-13 | 2019-12-10 | Honeywell International Inc. | Pressure regulator |
JP6576841B2 (en) * | 2016-01-19 | 2019-09-18 | アズビル株式会社 | Positioner |
CN108779876B (en) * | 2016-03-16 | 2023-07-04 | 德莱赛公司 | Extending functionality of a process device |
JP6671202B2 (en) * | 2016-03-23 | 2020-03-25 | アズビル株式会社 | Positioner |
FI128617B (en) | 2016-03-30 | 2020-08-31 | Metso Flow Control Oy | Fluid valve assembly, process valve positioner and use of a fluid valve assembly in control of a process valve |
JP2017194122A (en) * | 2016-04-21 | 2017-10-26 | アズビル株式会社 | Positioner and valve control system |
US10557736B2 (en) | 2016-05-10 | 2020-02-11 | Mks Instruments, Inc. | Predictive diagnostics systems and methods using vacuum pressure control valves |
DE102016108832A1 (en) * | 2016-05-12 | 2017-11-16 | Bürkert Werke GmbH | Method for controlling a valve and valve |
US10203704B2 (en) * | 2016-06-16 | 2019-02-12 | Moog Inc. | Fluid metering valve |
US9953474B2 (en) | 2016-09-02 | 2018-04-24 | Honeywell International Inc. | Multi-level security mechanism for accessing a panel |
US11274685B2 (en) | 2016-09-21 | 2022-03-15 | Neles Finland Oy | Actuator of a process device having a controller configured to operate in a measured position feedback mode and a simulated position feedback mode |
US10234058B2 (en) | 2016-10-20 | 2019-03-19 | Fisher Controls International Llc | Methods and apparatus of assessing a test of a solenoid valve via a positioner |
US10240687B2 (en) | 2016-10-20 | 2019-03-26 | Fisher Controls International Llc | Methods and apparatus of testing a solenoid valve of an emergency valve via a positioner |
US10041610B2 (en) * | 2016-10-20 | 2018-08-07 | Fisher Controls International Llc | Methods and apparatus of stabilizing a valve positioner when testing a solenoid valve |
DE102016125643B3 (en) * | 2016-12-23 | 2018-06-14 | Samson Aktiengesellschaft | Control and / or control method for an electropneumatic field device |
US11454962B2 (en) | 2017-05-08 | 2022-09-27 | Idex Health & Science, Llc | Flow control assembly having localized non-volatile memory |
US10792697B2 (en) * | 2017-05-17 | 2020-10-06 | Taiwan Semiconductor Manufacturing Company, Ltd. | Drippage prevention system and method of operating same |
US11071266B2 (en) * | 2017-06-14 | 2021-07-27 | Grow Solutions Tech Llc | Devices, systems, and methods for providing and using one or more pressure valves in an assembly line grow pod |
US10696906B2 (en) | 2017-09-29 | 2020-06-30 | Marathon Petroleum Company Lp | Tower bottoms coke catching device |
US10670054B2 (en) | 2017-10-25 | 2020-06-02 | Dresser, Llc | Constructing valve positioners for hazardous areas |
US11306748B2 (en) | 2017-10-25 | 2022-04-19 | Dresser, Llc | Constructing valve positioners for hazardous areas |
CN109826991B (en) * | 2017-11-23 | 2020-12-04 | 西门子瑞士有限公司 | Actuating mechanism, control valve and valve control system |
WO2019126095A1 (en) | 2017-12-21 | 2019-06-27 | Swagelok Company | Systems and methods for control and monitoring of actuated valves |
DE102018116048B4 (en) * | 2018-07-03 | 2020-10-01 | Samson Aktiengesellschaft | Diagnosis of possible causes for changes in a control valve |
US11608840B2 (en) * | 2018-08-21 | 2023-03-21 | Michael Yuan | Piezoelectric ring bender servo valve assembly for aircraft flight control actuation and fuel control systems |
DE102018214295A1 (en) | 2018-08-23 | 2020-02-27 | Stabilus Gmbh | Measurement of operating parameters on actuators |
WO2020077332A1 (en) | 2018-10-12 | 2020-04-16 | Bray International, Inc. | Smart valve with integrated electronics |
EP3647899A1 (en) | 2018-10-29 | 2020-05-06 | Siemens Schweiz AG | Method for operating a valve, related electronic control unit and valve drive |
US11347463B2 (en) | 2018-10-31 | 2022-05-31 | Honeywell International Inc. | Correlative display system with decluttered displays for aircraft |
DE102018130579A1 (en) * | 2018-11-30 | 2020-06-04 | Gemü Gebr. Müller Apparatebau Gmbh & Co. Kommanditgesellschaft | Shut-off device, component for a shut-off device, control unit for a shut-off device and method for operating a shut-off device |
CN113167391B (en) | 2018-12-06 | 2023-12-15 | 布雷国际有限公司 | Intelligent valve adapter with integrated electronics |
CN109491273B (en) * | 2018-12-25 | 2021-11-16 | 航天科工哈尔滨风华有限公司电站设备分公司 | Comprehensive signal control device and control method thereof |
JP7238461B2 (en) * | 2019-02-25 | 2023-03-14 | 株式会社島津製作所 | Valve controller and vacuum valve |
US11143328B2 (en) * | 2019-03-06 | 2021-10-12 | Honeywell International Inc. | Health monitoring for proportional actuators |
EP3942208B1 (en) * | 2019-03-18 | 2023-06-07 | Belimo Holding AG | Method for operating a control valve, hvac actuator and computer program product |
US10789800B1 (en) | 2019-05-24 | 2020-09-29 | Ademco Inc. | Systems and methods for authorizing transmission of commands and signals to an access control device or a control panel device |
US10832509B1 (en) | 2019-05-24 | 2020-11-10 | Ademco Inc. | Systems and methods of a doorbell device initiating a state change of an access control device and/or a control panel responsive to two-factor authentication |
CN110597104A (en) * | 2019-08-11 | 2019-12-20 | 潘琳琳 | Intelligent electropneumatic valve positioner |
CN110720656B (en) * | 2019-10-09 | 2021-12-24 | 河南卷烟工业烟草薄片有限公司 | Heating control device and method for paper-making reconstituted tobacco drying box |
CN110715174B (en) * | 2019-10-17 | 2021-09-14 | 重庆川仪自动化股份有限公司 | Valve position accumulation method and device of intelligent valve positioner, storage medium and electronic terminal |
CN111022735A (en) * | 2019-12-18 | 2020-04-17 | 中国空气动力研究与发展中心低速空气动力研究所 | TPS is experimental with quick voltage regulator device of large-traffic gas |
CA3109675A1 (en) | 2020-02-19 | 2021-08-19 | Marathon Petroleum Company Lp | Low sulfur fuel oil blends for stability enhancement and associated methods |
US11788934B2 (en) | 2020-07-01 | 2023-10-17 | Saudi Arabian Oil Company | In-line fluid and solid sampling within flowlines |
IT202000017689A1 (en) * | 2020-07-22 | 2022-01-22 | Sti S R L | SYSTEM FOR DIAGNOSTICS OF LEAKAGE LEAKS BETWEEN THE SEAT AND PLUG OF A VALVE |
US11692903B2 (en) | 2020-10-01 | 2023-07-04 | Saudi Arabian Oil Company | Valve diagnostic and performance system |
US11441697B2 (en) | 2020-10-01 | 2022-09-13 | Saudi Arabian Oil Company | Valve diagnostic and performance system |
US11898109B2 (en) | 2021-02-25 | 2024-02-13 | Marathon Petroleum Company Lp | Assemblies and methods for enhancing control of hydrotreating and fluid catalytic cracking (FCC) processes using spectroscopic analyzers |
US20220268694A1 (en) | 2021-02-25 | 2022-08-25 | Marathon Petroleum Company Lp | Methods and assemblies for determining and using standardized spectral responses for calibration of spectroscopic analyzers |
US11905468B2 (en) | 2021-02-25 | 2024-02-20 | Marathon Petroleum Company Lp | Assemblies and methods for enhancing control of fluid catalytic cracking (FCC) processes using spectroscopic analyzers |
US11865928B2 (en) | 2021-11-24 | 2024-01-09 | Saudi Arabian Oil Company | Generating power with a conduit inspection tool |
US11802257B2 (en) | 2022-01-31 | 2023-10-31 | Marathon Petroleum Company Lp | Systems and methods for reducing rendered fats pour point |
Family Cites Families (16)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2769943A (en) * | 1953-04-20 | 1956-11-06 | Milwaukee Gas Specialty Co | Electromagnetic control device |
US3575209A (en) * | 1969-02-24 | 1971-04-20 | Gen Electric | Fluidic position limit control |
DE2439030A1 (en) * | 1973-09-26 | 1975-03-27 | Sanders Associates Inc | Two stage hydraulic flow regulating valve - flow sensing valve located in output line provides feedback compensating signals for flapper auxiliary control pistons |
GB1518720A (en) * | 1975-11-21 | 1978-07-26 | Ishikawajima Harima Heavy Ind | Hydraulic servomechanism |
US4492246A (en) * | 1983-03-28 | 1985-01-08 | Mcgraw-Edison Company | Solid state current-to-pressure and current-to-motion transducer |
GB8404169D0 (en) * | 1984-02-17 | 1984-03-21 | Dowty Hydraulic Units Ltd | Electrohydraulic servo valve |
US4712173A (en) * | 1984-10-01 | 1987-12-08 | Yamatake Honeywell | Multicontrol process control system |
US4672997A (en) * | 1984-10-29 | 1987-06-16 | Btu Engineering Corporation | Modular, self-diagnostic mass-flow controller and system |
US4665938A (en) * | 1986-09-30 | 1987-05-19 | Rosemount Inc. | Frequency feedback on a current loop of a current-to-pressure converter |
US4845416A (en) * | 1987-02-13 | 1989-07-04 | Caterpillar Inc. | Electronic valve actuator |
US4976144A (en) * | 1988-08-25 | 1990-12-11 | Fisher Controls International, Inc. | Diagnostic apparatus and method for fluid control valves |
US5197328A (en) * | 1988-08-25 | 1993-03-30 | Fisher Controls International, Inc. | Diagnostic apparatus and method for fluid control valves |
US5251148A (en) * | 1990-06-01 | 1993-10-05 | Valtek, Inc. | Integrated process control valve |
US5193568A (en) * | 1991-06-20 | 1993-03-16 | Martin Marietta Energy Systems, Inc. | Noninvasive valve monitor using alternating electromagnetic field |
US5325884A (en) * | 1991-07-10 | 1994-07-05 | Conservair Technologies | Compressed air control system |
US5146941A (en) * | 1991-09-12 | 1992-09-15 | Unitech Development Corp. | High turndown mass flow control system for regulating gas flow to a variable pressure system |
-
1993
- 1993-08-25 US US08/112,694 patent/US5549137A/en not_active Expired - Lifetime
-
1994
- 1994-07-14 BR BR9407585A patent/BR9407585A/en not_active IP Right Cessation
- 1994-07-14 EP EP99202230A patent/EP0957418B1/en not_active Expired - Lifetime
- 1994-07-14 CA CA002166867A patent/CA2166867C/en not_active Expired - Fee Related
- 1994-07-14 JP JP50756595A patent/JP3595554B2/en not_active Expired - Fee Related
- 1994-07-14 EP EP94923482A patent/EP0739503B1/en not_active Expired - Lifetime
- 1994-07-14 CN CN94193113.7A patent/CN1072816C/en not_active Expired - Fee Related
- 1994-07-14 DE DE69432029T patent/DE69432029T2/en not_active Expired - Lifetime
- 1994-07-14 SG SG1996000693A patent/SG44472A1/en unknown
- 1994-07-14 DE DE69427487T patent/DE69427487T2/en not_active Expired - Lifetime
- 1994-07-14 WO PCT/US1994/007914 patent/WO1995006276A1/en active IP Right Grant
-
1995
- 1995-06-07 US US08/478,506 patent/US5573032A/en not_active Expired - Lifetime
- 1995-06-07 US US08/481,085 patent/US5558115A/en not_active Expired - Lifetime
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CN105114692A (en) * | 2008-02-29 | 2015-12-02 | 费希尔控制国际公司 | Diagnostic method for detecting control valve component failure |
CN105114692B (en) * | 2008-02-29 | 2017-12-15 | 费希尔控制国际公司 | For detecting the diagnostic method of control valve component failure |
Also Published As
Publication number | Publication date |
---|---|
EP0739503A1 (en) | 1996-10-30 |
EP0739503B1 (en) | 2001-06-13 |
WO1995006276A1 (en) | 1995-03-02 |
EP0957418A2 (en) | 1999-11-17 |
JPH09502292A (en) | 1997-03-04 |
CN1072816C (en) | 2001-10-10 |
US5558115A (en) | 1996-09-24 |
DE69432029T2 (en) | 2003-11-20 |
JP3595554B2 (en) | 2004-12-02 |
SG44472A1 (en) | 1997-12-19 |
CN1129480A (en) | 1996-08-21 |
EP0957418B1 (en) | 2003-01-15 |
CA2166867A1 (en) | 1995-03-02 |
DE69427487D1 (en) | 2001-07-19 |
DE69427487T2 (en) | 2002-04-25 |
DE69432029D1 (en) | 2003-02-20 |
EP0957418A3 (en) | 2000-05-10 |
US5549137A (en) | 1996-08-27 |
US5573032A (en) | 1996-11-12 |
BR9407585A (en) | 1997-01-07 |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
CA2166867C (en) | Valve positioner with pressure feedback, dynamic correction and diagnostics | |
EP2257724B1 (en) | Diagnostic method for detecting control valve component failure | |
CA2642457C (en) | System and method for fluid regulation | |
CA2447001C (en) | Method for detecting broken valve stem | |
CA2668315C (en) | Intelligent pressure regulator | |
US20090216350A1 (en) | Control valve and positioner diagnostics | |
US20220333714A1 (en) | Valve positioner and diagnostic method | |
WO2005124160A1 (en) | Feedback control methods and apparatus for electro-pneumatic control systems | |
US11274685B2 (en) | Actuator of a process device having a controller configured to operate in a measured position feedback mode and a simulated position feedback mode | |
Kiesbauer et al. | Modern control valves with failure diagnostics | |
Tlisov et al. | Adaptive control system for pipeline valve pneumatic actuator | |
Fitzgerald | Keep valve top works from becoming a bottom priority |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
EEER | Examination request | ||
MKLA | Lapsed |
Effective date: 20140715 |