JPH11311217A - Electropneumatic positioner and electropneumatic converter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To alternately detect the degree of soil of nozzle flapper mechanism so as to perform maintenance before malfunction of an instrument itself starts. SOLUTION: A nozzle soil detecting nozzle flapper 22 is provided to alternately detect the soil of a nozzle flapper mechanism 7 of an electropneumatic converting part 2, and a pressure gauge 23 is provided to measure the nozzle back pressure of the soil detecting nozzle flapper 22. The degree of soil of the nozzle flapper mechanism 7 is detected by an electric module 24 from the nozzle back pressure detected by the pressure sensor 23 and displayed as maintenance information on a display part 25.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electropneumatic positioner which is used in various plants such as petrochemical and chemical industries and controls an opening of a valve for controlling a flow rate of a fluid and a set opening signal of the valve. The present invention relates to an electropneumatic converter for converting an electric signal into a pneumatic signal.

[0002]

2. Description of the Related Art Generally, an electropneumatic converter used for controlling the operation of a valve used for process control is provided with an electropneumatic converter for converting an input electric signal into an air pressure. And the valve is operated. Further, the electropneumatic converter adjusts its own output air signal so that the deviation between the setting signal sent from the control unit and its output air pressure signal becomes zero (JP-A-7-110).
003 publication).

FIG. 6 is a block diagram of an electropneumatic converter. In the figure, the electropneumatic converter 4 includes an electric signal processing unit 1, an electropneumatic converter 2, and an electropneumatic converter 2, which provide an input signal corresponding to a setting signal input from the control unit to the electropneumatic converter 2. A pressure sensor 3 for detecting an output is provided.

The electro-pneumatic converter 2 includes, for example, a yoke 5 formed in a U-shape in front view so as to sandwich the magnet M at the center,
An excitation coil 6 attached to one leg 5A of the yoke 5 and a nozzle / flapper mechanism 7 are provided. nozzle·
The flapper mechanism 7 includes a swingable flapper 8 having a base fixed to the distal end surface of one leg 5A of the yoke 5 and the other leg of the yoke 5 so as to be close to and opposed to the distal end of the flapper 8. And a nozzle 9 attached to the distal end surface of the portion 5B. The nozzle 9 is connected to an air supply source (not shown) by a supply air pipe 10 and is constant (normally 1.4).
A supply air pressure Ps of Kgf / cm ² ) is supplied through a fixed throttle 11.

In the electropneumatic converter 4 provided with such an electropneumatic converter 2, the electric signal processor 1 receives an input electric signal (for example, 4 mA to 20 mA) I0 according to the measured amount. The corresponding output signal I is output to the exciting coil 6 of the electropneumatic converter 2 to change the intensity of the magnetic field. As a result, the flapper 8 swings and the gap (nozzle gap X) with the nozzle 9 changes, and the back pressure Pn of the nozzle 9 changes. After the nozzle back pressure Pn is amplified by the pilot relay 12, it is supplied as an output pressure to an operating device that drives the valve shaft of the valve 13, whereby the valve 13 is automatically opened and closed. The output air pressure from the pilot relay 12 is detected by the pressure sensor 3 and input to the electric signal processing unit 1 as a detection signal. The electric signal processing unit 1 compares the input electric signal I0 with the detection signal I1 from the pressure sensor 3 to obtain a deviation e, and inputs a signal corresponding to the deviation e to the electropneumatic conversion unit 2, thereby obtaining a flapper. 8 is returned to the position corresponding to the input electric signal I0, and the valve 13 is stabilized when the deviation e between the input electric signal I0 and the detection signal I1 becomes zero.

[0006]

As described above, in the conventional electropneumatic converter 4, the nozzle / flapper mechanism 7 is used as the electropneumatic converter 2 of the electropneumatic converter 4. The nozzle gap X between the nozzle 9 and the flapper 8 is extremely narrow, so that minute dust (dust, mist) contained in the supply air pressure Ps is liable to accumulate and become dirty. That is, the supply air pressure Ps passes through the supply air pipe 10 and
The liquid is guided to the nozzle 9 through 1 and discharged into the instrument. The fine dust contained in the supply air gradually accumulates in the narrowest nozzle gap X in the air path, and the accumulation amount increases as the operation time increases. Then, when the amount of deposition exceeds the allowable value, the meter itself falls into a malfunction state.

However, the current meter cannot check the degree of contamination of the nozzle / flapper mechanism 7 from outside the meter, so it is necessary to temporarily stop the operation of the meter and check it. There is a problem that the user has to open the container in which it is stored to perform the checking work, and the checking work is very troublesome. This problem is the same for the electropneumatic positioner having the nozzle / flapper mechanism.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned conventional problems. It is an object of the present invention to detect the degree of dirt on the nozzle flapper mechanism during operation instead of the instrument itself. It is an object of the present invention to provide an electro-pneumatic positioner and an electro-pneumatic converter capable of performing maintenance before malfunction occurs.

[0009]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides an electro-pneumatic conversion unit for making a deviation between a set opening signal from a host controller and an actual opening signal of a valve zero. An electro-pneumatic positioner, which sends an air pressure signal according to the electric signal to a pilot relay, and controls the valve with air pressure according to the air pressure signal. A dirt detection nozzle flapper connected in parallel with the nozzle flapper mechanism to the supply air pipe to alternately detect dirt on the nozzle flapper mechanism of the conversion unit, and a nozzle back pressure of the dirt detection nozzle flapper is measured. And a pressure measuring unit for measuring the pressure. In the present invention, the degree of contamination of the nozzle / flapper mechanism can be alternatively detected by the contamination detection nozzle flapper without stopping the operation of the electropneumatic positioner.

Further, the present invention is characterized in that a display unit for displaying a message based on the measurement data of the pressure measurement unit is provided. In the present invention, the display unit displays the degree of contamination of the nozzle / flapper mechanism.

Further, the present invention is characterized in that transmission means for transmitting measurement data of the pressure measurement unit to an external device is provided. In the present invention, the degree of contamination of the nozzle / flapper mechanism can be confirmed at a location away from the site where the electropneumatic positioner is installed without stopping the operation of the electropneumatic positioner.

Further, the present invention provides an electric signal transmitting an electric signal to an electropneumatic converter so that a deviation between a set opening signal from a host controller and a measurement signal of a pressure sensor for measuring an output air pressure of a pilot relay is made zero. A signal processing unit, wherein the electro-pneumatic conversion unit detects dirt on the nozzle / flapper mechanism of the electro-pneumatic conversion unit in an electro-pneumatic converter that sends an air pressure signal corresponding to the electric signal to the pilot relay. For this purpose, a dirt detecting nozzle flapper connected in parallel with the nozzle flapper mechanism to the supply air pipe and a pressure measuring unit for measuring the nozzle back pressure of the dirt detecting nozzle flapper are provided. In the present invention, the degree of dirt of the nozzle / flapper mechanism can be detected by the dirt detecting nozzle and the flapper without stopping the operation of the electropneumatic converter.

Further, the present invention is characterized in that the measurement data of the pressure measurement unit is output to a display unit. In the present invention, the degree of contamination of the nozzle / flapper mechanism can be confirmed from the outside of the instrument by the display unit.

Further, the present invention is characterized in that a transmitting means for transmitting the measurement data of the pressure measuring section to an external device is provided. In the present invention, the degree of dirt on the nozzle / flapper mechanism can be confirmed at a location away from the site.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail based on an embodiment shown in the drawings. FIG. 1 is a configuration diagram showing an embodiment of an electropneumatic converter according to the present invention. In the drawings, the same components as those shown in the section of the prior art are denoted by the same reference numerals, and description thereof will be omitted as appropriate. The electropneumatic converter 4 includes a nozzle flapper 22 for detecting dirt equivalent to the nozzle / flapper mechanism 7 of the electropneumatic converter 2 in an air circuit, a pressure gauge (pressure measuring unit) 23, and an electric module 24.
And a dirt detection mechanism 26 including a display unit 25 and the like. The other configuration is exactly the same as the above-described conventional one.

The dirt detecting nozzle flapper 22 is provided for detecting dirt on the nozzle / flapper mechanism 7 and is composed of a nozzle 27 and a flapper 28. 2, the air pressure Ps having the same pressure as the supply air pressure Ps supplied to the electropneumatic converter 2 is supplied through the pipe 10 via the fixed throttle 29. The material of the nozzle 27 and the material of the flapper 28 are preferably the same as the material of the nozzle 9 and the flapper 8 of the nozzle / flapper mechanism 7 in order to make the dirt arrive the same, but the size is not necessarily the same. In addition, the size of the nozzle back pressure Pn ′ may be reduced to a minimum size that does not change. Since the nozzle flapper 22 is not directly related to the drive control of the valve 13, the nozzle gap between the nozzle 27 and the flapper 28 is set to a representative value (described later) of the operating input pressure of the pilot relay 12.

The pressure gauge 23 is provided with the nozzle flapper 2
For detecting the nozzle back pressure Pn ′, for example, a Bourdon tube pressure gauge is used, and the detection signal is guided to the electric module 24. The electric module 24
Timer 33, memory 34, CPU (central processing unit) 3
5. A comparison circuit 36 and the like are provided, and the degree of contamination of the nozzle flapper 22 is detected by storing and comparing the nozzle back pressure Pn ′ of the nozzle flapper 22 as data in a time-series manner,
This is displayed on the display unit 25 such as an LCD as maintenance information, or the measured value of the nozzle back pressure Pn 'is displayed. The CPU 35 of the electric module 24 stores the nozzle back pressure Pn ′ of the nozzle flapper 22 in the initial state in advance,
When the comparison and judgment program is stored and | Pn ′ (t) −Pn ″ (0) | ≧ σ is satisfied, the maintenance time is displayed on the display unit 25. Here, Pn ′ (t): a nozzle back pressure value after a lapse of t hours from the initial state Pn ″ (0): a nozzle back pressure value in the initial state σ: a threshold serving as a criterion By recording '(t), time-series data of dirt can be obtained and can be used as an information source for diagnosing air equipment (plant side).

FIG. 2 shows the nozzle gap X and the input signal Ii.
n, nozzle back pressure Pn and pilot output P
It is a figure which shows the relationship of _out . In the figure, 40 is a nozzle diameter,
This is a curve determined by the diameter of the fixed stop 11. During most operations, the nozzle gap X is X1 ± ΔX
, X1 is set as the representative value of the nozzle gap of the dirt detecting nozzle flapper 22.

In the electropneumatic converter having such a structure, the contamination of the nozzle / flapper mechanism 7 is alternatively detected by the nozzle flapper 22. Therefore, the degree of the contamination of the nozzle / flapper mechanism 7 from outside during the operation of the instrument. You can know. That is, if the opposing surface between the nozzle 9 and the flapper 8 of the nozzle / flapper mechanism 7 becomes dirty by the attachment of dust or the like, the nozzle gap X becomes small and the nozzle back pressure Pn is changed. Also, the surface of the nozzle flapper 22 facing the nozzle and the flapper is similarly contaminated by adhesion and accumulation of dust and the like, so that the nozzle gap is reduced and the nozzle back pressure Pn 'is changed. In this case, since the amount of air flowing out of the nozzle 9 and the amount of air flowing out of the nozzle 27 are considered to be the same, the dirt between the nozzle gaps of the nozzle flapper mechanism 7 and the nozzle flapper 22 can be considered to be the same. The change in the nozzle back pressure Pn 'is detected by the electric module 24 as the degree of contamination of the nozzle flapper 22 and displayed on the display unit 25. Therefore, by monitoring the display unit 25, the degree of contamination of the current nozzle / flapper mechanism 7 can be indirectly and accurately grasped without stopping the operation from outside the electropneumatic converter 4. The maintenance time can be set before the instrument falls into a malfunction state.

FIG. 3 is a diagram showing another embodiment of the present invention. In this embodiment, the output of the electric module 24 is led to an external device via the communication interface (transmitting means) 41 instead of the display unit 25. A diagnostic device or the like is used as the external device, and is installed at a place away from the site. Other configurations are the same as those of the above-described embodiment. In such a configuration,
The degree of contamination of the nozzle / flapper mechanism 7 can be confirmed at a location away from the site where the electropneumatic converter 4 is installed.

FIG. 4 is a block diagram showing an embodiment of an electropneumatic positioner according to the present invention. Electro-pneumatic positioner 100
Is a device for converting an electric signal into an air signal by the electropneumatic converter 4 and adjusting the valve opening degree of the valve.
Similarly to the above, a dirt detection nozzle flapper 22, a pressure gauge 23, an electric module 24, and a display unit 25 which are equivalent to the nozzle / flapper mechanism of the electropneumatic conversion unit 2 in terms of an air circuit are provided. The dirt detection nozzle flapper 22 is connected to the supply air pipe 10 in parallel with the electropneumatic converter 2. The electric module 24 is incorporated in the electric signal processing unit 1, and a display unit 25 for displaying the degree of contamination of the nozzle flapper 22 is connected to the electric signal processing unit 1. The movement of the valve 13 is detected by the valve lift detection unit 44,
It is input to the electric processing unit 1 as a detection signal θpv. The electric signal processor 1 receives the input electric signal I0 and the valve lift detector 44.
The deviation is obtained by comparing the electric signal θpv from the first and second signals, and a signal corresponding to this deviation is input to the electropneumatic converter 2. That is, the electric signal processing unit 1 sends the electric signal to the pneumatic conversion unit 2 so as to make the deviation between the set opening signal from the host controller and the actual opening signal of the valve sent through the communication interface 41 zero. And a function of outputting a message based on the measurement data of the pressure gauge 23 to the display unit 25. Other configurations are the same as those of the embodiment of the electropneumatic converter shown in FIG.

In such an electropneumatic positioner 100, by monitoring the display section 25, the current nozzle
The degree of contamination of the flapper mechanism can be accurately grasped without stopping the operation from the outside of the electropneumatic positioner 100, and the maintenance time can be set before the instrument falls into a malfunction state.

FIG. 5 is a block diagram showing still another embodiment of the electropneumatic positioner. In this embodiment, the display section is omitted, and the output signal of the electric signal processing section 1 is transmitted to the host controller 50 by the communication interface 41. The output signal of the electric signal processing unit 1 is the actual opening degree of the valve 13, the nozzle back pressure Pn ', the measurement result, the maintenance information, and the like. Other configurations are the same as those of the embodiment shown in FIG. In such a configuration, the degree of contamination of the electropneumatic converter 2 can be confirmed by the host controller 50 at a location away from the site where the electropneumatic positioner 100 is installed.

[0024]

As described above, according to the electropneumatic positioner and the electropneumatic converter according to the present invention, a dirt detecting nozzle flapper is provided, whereby the dirt of the nozzle / flapper mechanism of the electropneumatic conversion unit is replaced. Because it was detected,
The degree of contamination of the nozzle and flapper mechanism can be accurately grasped from outside the equipment and during operation of the electro-pneumatic positioner or electro-pneumatic converter, and the maintenance time must be set before the instrument falls into a malfunction state. Can be. Also, the structure is simple because it is only necessary to connect the nozzle flapper to the pipe in parallel with the nozzle flapper mechanism.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing an embodiment of an electropneumatic converter according to the present invention.

FIG. 2 is a diagram showing a relationship among a nozzle gap, an input signal, a nozzle back pressure, and an output of a pilot relay.

FIG. 3 is a configuration diagram showing another embodiment of the electropneumatic converter.

FIG. 4 is a block diagram showing an embodiment of an electropneumatic positioner according to the present invention.

FIG. 5 is a block diagram showing another embodiment of the electropneumatic positioner.

FIG. 6 is a diagram showing an example of a conventional electropneumatic converter.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Electric signal processing part, 2 ... Electro-pneumatic conversion part, 3 ... Pressure sensor, 4 ... Electro-pneumatic converter, 7 ... Nozzle / flapper mechanism, 8 ...
Flapper, 9 ... Nozzle, 12 ... Pilot relay, 13
... Valve, 22 ... Dirt detection nozzle flapper, 23 ... Pressure gauge, 24 ... Electrical module, 25 ... Display unit, 27 ... Nozzle, 28 ... Flapper, 33 ... Timer, 34 ... Memory,
35 CPU, 36 comparison circuit, 41 communication interface, 50 upper controller, 100 electropneumatic positioner.

Claims (6)

[Claims] An electric signal processing unit for sending an electric signal to an electro-pneumatic conversion unit so that a deviation between a set opening signal from a host controller and an actual opening signal of a valve is set to zero, wherein the electro-pneumatic conversion unit is An air pressure signal corresponding to the electric signal is sent to a pilot relay, and in an electropneumatic positioner that controls the valve with air pressure corresponding to the air pressure signal, dirt on the nozzle / flapper mechanism of the electropneumatic conversion unit is alternatively detected. An electro-pneumatic positioner comprising: a dirt detecting nozzle flapper connected in parallel to the nozzle / flapper mechanism to a supply air pipe; and a pressure measuring unit for measuring a nozzle back pressure of the dirt detecting nozzle flapper. . 2. The electro-pneumatic positioner according to claim 1, further comprising a display unit for displaying a message based on the measurement data of the pressure measuring unit. 3. An electro-pneumatic positioner according to claim 1, further comprising a transmitting means for transmitting measurement data of the pressure measuring section to an external device. 4. An electric signal processing unit for transmitting an electric signal to an electropneumatic conversion unit such that a deviation between a set opening signal from a host controller and a measurement signal of a pressure sensor for measuring an output air pressure of a pilot relay is made zero. The electro-pneumatic converter includes an electro-pneumatic converter that sends a pneumatic signal according to the electric signal to the pilot relay, wherein the supply air is used for alternately detecting contamination of the nozzle / flapper mechanism of the electro-pneumatic converter. An electropneumatic converter comprising: a dirt detection nozzle flapper connected in parallel to the nozzle / flapper mechanism in a pipe for use; and a pressure measuring unit for measuring a nozzle back pressure of the dirt detection nozzle flapper. 5. The electropneumatic converter according to claim 4, wherein the measurement data of the pressure measuring unit is output to a display unit. 6. The electropneumatic converter according to claim 4, further comprising a transmission unit for transmitting the measurement data of the pressure measuring unit to an external device.