JP4968571B2 - Differential pressure measuring device with pressure guiding tube clogging diagnosis mechanism - Google Patents

Description

  The present invention includes a differential pressure transmitter that is connected to a conduit through which a fluid to be measured flows via a pressure guiding tube, a valve that is connected to the conduit and whose opening is controlled by an opening / closing operation signal, and is superimposed on the opening / closing operation signal. The present invention relates to a differential pressure measuring device with a pressure guiding tube blockage diagnosing mechanism, comprising a diagnostic device that determines a clogged state of the pressure guiding tube based on a response of the differential pressure transmitter to a diagnostic signal.

  Prior art documents related to differential pressure measurement with a pressure guiding tube clogging diagnosis mechanism include the following.

JP-A-8-166309 Japanese Patent No. 3147275

  FIG. 6 is a functional block diagram illustrating a configuration example of a conventional device disclosed in Patent Document 1. In FIG. In the figure, reference numeral 1 denotes a conduit through which the measurement fluid 2 flows. 3 is a valve for controlling the flow rate of the measurement fluid, and 4 is a valve positioner for controlling the opening degree of the valve 3. A controller 5 controls the positioner 4.

  Reference numeral 6 denotes a differential pressure transmitter, which detects the flow rate of the measurement fluid controlled by the valve 3 and sends a detection signal to the controller 5. Reference numeral 7 denotes an orifice inserted into the pipe line 1, the pressure on the high pressure side is supplied to one input of the differential pressure transmitter 6 via the pressure guiding pipe 8, and the pressure on the low pressure side is changed via the pressure guiding pipe 9. It is led to the other input of the pressure transmitter 6.

  In such a configuration, when the measurement fluid 2 flows through the pipe 1, the differential pressure transmitter 6 measures the flow rate of the measurement fluid 2. The measurement signal PV (hereinafter referred to as α) is sent to the controller 5 and compared with the target value SV, the opening / closing operation signal MV is sent to the valve positioner 4 and the opening / closing control of the valve 3 is performed.

  Reference numeral 11 is a check signal transmission means provided in the differential pressure transmitter 6 and outputs the output signal of the differential pressure transmitter body 6 instead of the measurement signal α to the check signal β when necessary. Similarly, 12 is a diagnostic means provided in the differential pressure transmitter 6, which detects a change in the differential pressure based on the check signal β and compares it with a predetermined reference value to determine the clogged state of the pressure guiding tube. Is output.

  In the above configuration, when the clogging diagnosis of the pressure guiding pipes 8 and 9 is performed, the check signal transmission means 11 changes the output signal of the differential pressure transmitter body 6 from the measurement signal α normally sent to the check signal β. Switch and output. The diagnosing means 12 detects a change in the differential pressure based on the check signal β, and determines whether the pressure guiding tubes 8 and 9 are clogged by comparing with a predetermined reference value.

  FIG. 7 is an operation explanatory diagram illustrating a determination procedure. The clogging diagnosis is usually performed at regular intervals T as shown in FIG. Of course, the diagnosis may be performed at any time.

  FIG. 7B is an enlarged view of FIG. 7A. In this case, the check signal β indicates that it has changed in a direction lower than the actual output α. In response to the check signal β, the controller 5 changes in a direction to increase the flow rate Q of the measurement fluid 2 as shown in FIG. The state of change in this case differs depending on the set value of the PID operation.

  Since the output of the controller 5 changes, the flow rate Q also changes accordingly, as shown in FIG. If the flow rate Q changes, the differential pressure ΔP before and after the orifice 7 also changes. When the pressure guiding pipes 8 and 9 are normal, the differential pressure input to the differential pressure transmitter 6 changes according to the flow rate change as shown in FIG.

  When both the high pressure side pressure guiding tube 8 and the low pressure side pressure guiding tube 9 are clogged, the differential pressure before and after the orifice 7 is not transmitted to the differential pressure transmitter 6 as shown in FIG. When one side of the pressure guiding tube 8 or 9 is clogged, as shown in FIG. 7 (g), the differential pressure is transmitted only to one side, so that the amount of change in the differential pressure transmitted to the differential pressure transmitter 6 is smaller than that in the normal state. Further, when the pressure guiding tube 8 or 9 is clogging, the output response is delayed or the amount of change is small, as shown in FIG.

The conventional differential pressure measuring device with a pressure guiding tube clogging diagnosis mechanism has the following problems.
(1) When either the high-pressure side pressure guiding tube or the low-pressure side pressure guiding tube is clogged, it is impossible to identify and determine which side of the pressure guiding tube is clogged.

(2) Therefore, the maintenance for clogging needs to be checked by removing both pressure guiding pipes, and the pressure guiding pipe on the normal side is removed and reattached, which reduces the efficiency of maintenance.

  Accordingly, the problem to be solved by the present invention is to detect the clogging of the high pressure side pressure guiding tube and the low pressure side pressure guiding tube in addition to the determination of both cloggings of the pressure guiding tube, and to detect and determine the clogging of the high pressure side pressure guiding tube Is to realize.

In order to achieve such an object, the configuration of the present invention is as follows.
(1) A differential pressure transmitter connected to a conduit through which a fluid to be measured flows through a pressure guiding tube, a valve connected to the conduit and controlled in opening degree by an opening / closing operation signal, and a diagnosis superimposed on the opening / closing operation signal A differential pressure measuring device with a pressure guiding tube blockage diagnosing mechanism, comprising a diagnostic device that determines a clogged state of the pressure guiding tube based on a response of the differential pressure transmitter to a signal;
The diagnostic device comprises:
Reference data holding means for acquiring a differential pressure change output of the differential pressure transmitter at a first time after a predetermined time after generation of the diagnostic signal when the pressure guiding tube is normal and holding it as first reference data;
Measurement data holding means for acquiring a differential pressure change output of the differential pressure transmitter at a first time after a predetermined time after generation of the diagnostic signal at the time of diagnosis and holding it as first measurement data;
Determination means for determining a clogged state of the pressure guiding tube based on the first reference data, the first measurement data, and a set parameter ;
The determination means includes
If the polarity of the first measurement data is negative, it is determined that the high pressure side pressure guiding tube is clogged,
If the polarity of the first measurement data is positive and the polarity of the difference between the first reference data and the first measurement data is negative, it is determined that the low pressure side pressure guiding tube is clogged,
If the polarity of the difference between the first reference data and the first measurement data is positive and the difference between the first measurement data and the first reference data is larger than the value of the parameter, the high pressure side pressure guiding tube and the low pressure It is determined that the side pressure pipe is clogged, and is determined to be normal if the difference between the first measurement data and the first reference data is smaller than the parameter value.
A differential pressure measuring device with a pressure guiding tube blockage diagnosing mechanism.

As is apparent from the above description, the present invention has the following effects.
(1) When either the high pressure side pressure guiding tube or the low pressure side pressure guiding tube is clogged, it is possible to make a diagnosis by identifying and judging which side of the pressure guiding tube is clogged.

(2) Therefore, the maintenance for one side clogging needs only to be checked by removing only the clogged pressure guiding tube, so that the maintenance efficiency is improved.

  Hereinafter, the present invention will be described in detail with reference to the drawings. FIG. 1 is a functional block diagram showing an embodiment of a differential pressure measuring apparatus with a pressure guiding tube clogging diagnosis mechanism to which the present invention is applied. The same elements as those in the conventional apparatus described with reference to FIG.

  In FIG. 1, 10 is a host device, and communicates with a controller 5, a differential pressure transmitter 6, a valve positioner 4 via a field bus (not shown). Reference numeral 100 denotes a diagnostic apparatus introduced in the present invention, and similarly communicates with the host apparatus 10 via the field bus.

  The diagnostic apparatus 100 includes a diagnostic unit 101 and a diagnostic signal applying unit 102. In the diagnosis unit 101, reference numeral 103 denotes a management unit. When a regular or irregular diagnosis command is received from the host device 10, a β command is transmitted to the diagnosis signal providing unit 102, and the diagnosis signal providing unit 102 is a controller. 5 outputs a diagnostic signal β superimposed on the opening / closing operation signal MV.

  Reference numeral 104 denotes basic data holding means, which acquires the differential pressure change output of the differential pressure transmitter with respect to the diagnostic signal β when the pressure guiding tubes 8 and 9 are normal (immediately after maintenance, etc.) and holds them as reference data. The basic data holding unit 104 holds at least the first reference data ΔP1std among the first reference data ΔP1std and the second reference data ΔP2std at the first time t1 and the second time t2 after the diagnosis signal is generated.

  Reference numeral 105 denotes measurement data holding means, which acquires the differential pressure change output of the differential pressure transmitter with respect to the generation of the diagnostic signal β at an arbitrary diagnosis and holds it as measurement data. The measurement data holding means 105 holds at least the first measurement data ΔP1 among the first measurement data ΔP1 and the second measurement data ΔP2 at the first time t1 and the second time t2 after the diagnosis signal β is generated.

  A determination unit 106 determines the clogged state of the pressure guiding conduit based on reference data, measurement data, and set parameters. Basically, based on the first reference data ΔP1std, the first measurement data ΔP1, and the set first parameter a, whether the pressure guiding tube is normal, double blocked, high pressure side blocked, or low pressure side blocked is determined.

  The determination means 106 further determines both of the pressure guiding pipes based on the first reference data ΔP1std and the second reference data ΔP2std, the first measurement data ΔP1 and the second measurement data ΔP2, and the set first parameter a and second parameter b. Determine the clogging size.

  The determination means 106 further determines the low pressure of the pressure guiding tube based on the first reference data ΔP1std and the second reference data ΔP2std, the first measurement data ΔP1 and the second measurement data ΔP2, and the set third parameter c and fourth parameter d. Determine the size and size of side clogging and the size and size of high pressure side clogging.

  Further, when the judging means 106 judges that both of the pressure guiding pipes are clogged and the pressure guiding pipes are clogged and clogged, the clogging alarm, the low pressure clogging alarm and the high pressure clogging alarm are generated. appear.

  The management unit 103 manages the operation sequence of the reference data holding unit 104, the measurement data holding unit 105, and the determination unit 106, and based on the information acquired from the host device 10, the first to fourth parameters a, b, c , D and time parameters t 1, t 2 are set in the determination means 106.

  FIG. 2 is a waveform diagram for explaining the acquisition of basic data. The differential pressure change output of the differential pressure transmitter 6 after the diagnostic signal β is generated at time t0 when the pressure guiding tubes 8 and 9 are in a normal state is indicated by a normal characteristic curve C0. A differential pressure change ΔP1std at a first time t1 (e.g., after 0.6 SEC) at which the transient response almost converges is acquired as first reference data and held in the reference data holding means 104. Furthermore, the differential pressure change ΔP2std at the second time t2 (for example, after 3.0 SEC) when a sufficient time (predetermined time) has passed is acquired as the second reference data and similarly held in the reference data holding means 104.

  FIG. 3 is a waveform diagram for explaining the acquisition of measurement data. A characteristic curve C0 indicated by a dotted line is a characteristic curve when the pressure guiding tube described in FIG. 2 is normal. The characteristic curve C1 is a response curve with respect to the diagnostic signal β when the pressure guiding tube is clogged, and the measurement data ΔP1 at the first time t1 is lower than the first reference data ΔP1std. Further, in the embodiment of FIG. 3, the measurement data ΔP2 at the second time t2 has substantially the same value as the second reference data ΔP2std.

  Further, when the degree of clogging increases, the difference between the measurement data ΔP1 and the first reference data ΔP1std increases. Furthermore, when the degree of clogging increases, the time constant of transient response increases.

  The characteristic curve C2 is a response curve with respect to the diagnostic signal β when the high pressure side pressure guiding tube 8 (only) is clogged. After an excessive state from the time t0 to the first time t1, the pressure difference once suddenly decreases. Ascend slowly. Accordingly, the measurement data ΔP1 at the first time t1 is lower than ΔP1std. Further, in the embodiment of FIG. 3, the measurement data ΔP2 at the second time t2 has substantially the same value as the second reference data ΔP2std.

  The characteristic curve C3 is a response curve for the diagnostic signal β when the pressure guiding tube 9 (only) on the low pressure side is clogged, and after the differential pressure has once increased rapidly in the transient state from the time t0 to the first time t1. Slowly drops. Accordingly, the measurement data ΔP1 at the first time t1 is higher than the first reference data ΔP1std. Further, in the embodiment of FIG. 3, the measurement data ΔP2 at the second time t2 has substantially the same value as the second reference data ΔP2std.

  As described above, the transient response up to the first time t1 with respect to the generation of the diagnostic signal β at the time t0 has different response curves due to the clogging of the pressure guiding pipe, the high pressure side clogging, and the low pressure side clogging. By comparing the measured data at the time and the reference data by introducing a threshold value based on an appropriate parameter, it is possible to identify and determine both clogging, high pressure side clogging, and low pressure side clogging.

  FIG. 4 is a flowchart showing the signal processing procedure of the basic diagnosis pattern (1) of the determination means 106. In this diagnostic pattern (1), normal, double clogging, high pressure side clogging, and low pressure side clogging of the pressure guiding tube are determined based on the first reference data ΔP1std, the first measurement data ΔP1 and the set first parameter a.

  Steps S1 to S5 shown in FIG. 4A are steps for obtaining the first reference data ΔP1std, and are executed when the pressure guiding tube is normal (immediately after maintenance or the like). When the process starts in step S1, the first time t1 and ΔP (change in differential pressure due to the diagnostic signal β) are set as parameters in step S2.

  In step S3, the initial value ΔP0std at time t0 is measured, and in step S4, the reference value measurement signal starts from time t0. In step S5, a reference value at time t1 (difference from the initial value ΔP0std) is measured and acquired as first reference data ΔP1std.

  S6 to S13 shown in FIG. 4B are diagnostic steps that are executed regularly or irregularly. When the diagnostic process starts in step S6, the first parameter a is set in step S7, the initial value ΔP0 at time t0 is measured in step S8, and the diagnostic signal starts in step S9.

  In step S10, data at time t1 (difference from the initial value ΔP0) ΔP1 is measured and obtained as measurement data. The polarity of the measurement data ΔP1 is determined in the determination step S11.

  If it is determined in step S11 that the polarity of ΔP1 is positive (YES), the process proceeds to step S12, and the polarity of (ΔP1std−ΔP1) is determined. If the polarity is positive (YES), the process proceeds to step S13. Based on the first parameter a, (ΔP1−ΔP1std) <a is determined. If YES, the normal determination D1 is obtained, and if NO, the double clogging determination D2 is obtained.

  If the polarity determination in step S12 is negative (NO), the low pressure side clogging D3 is determined. Similarly, if the polarity determination in step S11 is negative (NO), the high-pressure side clogging D4 is determined.

  FIG. 5 is a flowchart showing a signal processing procedure of the applied diagnostic pattern (2) of the determination means 106. In this diagnostic pattern (2), based on the first reference data, the second reference data, the first measurement data, the second measurement data, and the set third parameter and fourth parameter, the diagnosis pattern is determined in (1). In addition, the low pressure side clogging large and small and the high pressure side clogging large and small are determined.

  Steps S1 to S5 shown in FIG. 5A are steps for obtaining ΔP1std as the first reference data and ΔP2std as the second reference data, and are similar to steps S1 to S5 in the diagnostic pattern (1) described in FIG. This is a process and will not be described.

  Steps S6 to S16 shown in FIG. 5B are diagnostic steps that are executed regularly or irregularly. When the diagnostic process starts in step S6, the first to fourth parameters a, b, c, d and the time parameters t1, t2 are set in step S7, and the initial value ΔP0 at time t0 is measured in step S8. In step S9, the diagnostic signal starts.

  In step S10, data at time t1 (difference from initial value ΔP0) ΔP1 and data at time t2 (difference from initial value ΔP0) ΔP2 are measured and acquired as measurement data.

  Steps S11 to S13 are the same determination steps as in FIG. 4 and are normal determination D1, but if the determination in step S13 is NO, the process proceeds to step S14, and (ΔP2std−ΔP2) is determined by the second parameter b. If <b is determined and the determination is YES, the determination D21 indicates that both the jams are small. In the case of NO, it becomes the judgment D22 that both clogging is large, and the clogging alarm A1 is generated.

  If the polarity determination in step S12 is negative (NO), the process proceeds to step S15, and (ΔP2std−ΔP2) <c is determined from the third parameter c. If YES, the low pressure side clogging determination D31 is determined. Become. In the case of NO, the judgment is D32 that the low pressure side clogging is large, and the low pressure side clogging alarm A2 is generated.

  Similarly, if the polarity determination in step S11 is negative (NO), the process proceeds to step S16, and (ΔP2std−ΔP2) <d is determined by the fourth parameter d. If YES, the high-pressure side clogging is small. It becomes determination D41. In the case of NO, it becomes the high pressure side clogging determination D42, and the high pressure side clogging alarm A3 is generated.

  5 corresponds to the characteristic curve C1 of FIG. 3 in FIG. 3, and the characteristic at the low pressure side clogging alarm A2 in FIG. 5 corresponds to the characteristic curve C3 of FIG. Correspondingly, the characteristic at the time of the high pressure side clogging alarm A3 in FIG. 5 corresponds to the characteristic curve C2 in FIG. 3 in FIG.

  In the embodiment described above, the diagnostic device 100 is shown as a functional block independent of the differential pressure transmitter 6. However, this diagnostic mechanism is a self-diagnostic mechanism of the differential pressure transmitter, and is integrated only in the transmitter, It can take the form of communicating with the host device 10 by the bus system.

  In the present invention, acquisition of the reference data and measurement data at the first time t1 is an essential requirement, but the number of data acquisitions after the second time t2 is not limited to one as in the embodiment, and is excessive. When the state is for a long time, more detailed diagnosis is possible by acquiring an arbitrary number of measurement data.

It is a functional block diagram which shows one Embodiment of the differential pressure measuring apparatus with a clogging diagnosis mechanism of the pressure guiding tube to which this invention is applied. It is a wave form diagram explaining acquisition of basic data. It is a wave form diagram explaining acquisition of measurement data. It is a flowchart which shows the signal processing procedure of the basic diagnostic pattern (1) by a determination means. It is a flowchart which shows the signal processing procedure of the applied diagnostic pattern (2) by a determination means. It is a functional block diagram which shows the structural example of the conventional apparatus currently disclosed by patent document 1. FIG. It is operation | movement explanatory drawing explaining the procedure of determination.

Explanation of symbols

1 Pipe Line 2 Fluid 3 Valve 4 Valve Positioner 5 Controller 6 Differential Pressure Transmitter 7 Orifice 8 Impulse Pipe (High Pressure Side)
9 Pressure guiding pipe (low pressure side)
10 Host device
DESCRIPTION OF SYMBOLS 100 Diagnosis apparatus 101 Diagnosis means 102 Diagnosis signal provision means 103 Management means 104 Reference data holding means 105 Measurement data holding means 106 Determination means

Claims (1)

The differential pressure transmitter connected to the conduit through which the fluid to be measured flows through a pressure guiding tube, the valve connected to the conduit and controlled in opening degree by the opening / closing operation signal, and the diagnostic signal superimposed on the opening / closing operation signal In the differential pressure measuring device with a pressure guiding tube blockage diagnosing mechanism, comprising a diagnostic device for determining a clogged state of the pressure guiding tube based on a response of the differential pressure transmitter,
The diagnostic device comprises:
Reference data holding means for acquiring a differential pressure change output of the differential pressure transmitter at a first time after a predetermined time after generation of the diagnostic signal when the pressure guiding tube is normal and holding it as first reference data;
Measurement data holding means for acquiring a differential pressure change output of the differential pressure transmitter at a first time after a predetermined time after generation of the diagnostic signal at the time of diagnosis and holding it as first measurement data;
Determination means for determining a clogged state of the pressure guiding tube based on the first reference data, the first measurement data, and a set parameter ;
The determination means includes
If the polarity of the first measurement data is negative, it is determined that the high pressure side pressure guiding tube is clogged,
If the polarity of the first measurement data is positive and the polarity of the difference between the first reference data and the first measurement data is negative, it is determined that the low pressure side pressure guiding tube is clogged,
If the polarity of the difference between the first reference data and the first measurement data is positive and the difference between the first measurement data and the first reference data is larger than the value of the parameter, the high pressure side pressure guiding tube and the low pressure It is determined that the side pressure pipe is clogged, and is determined to be normal if the difference between the first measurement data and the first reference data is smaller than the parameter value.
A differential pressure measuring device with a pressure guiding tube blockage diagnosing mechanism.

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