JP4893917B2 - Diagnostic equipment - Google Patents

Description

  The present invention relates to a diagnostic apparatus for diagnosing a differential pressure / pressure transmitter that receives a pressure of a process fluid through a process diaphragm.

When differential pressure / pressure measurement of a process fluid containing hydrogen is performed with a pressure measurement capsule, measurement errors due to hydrogen accumulated in the capsule through the process diaphragm (seal diaphragm) of the pressure measurement capsule, and the diaphragm There is a need to diagnose damage and the like.

  FIG. 7 is a functional block diagram showing an example of a differential pressure measuring device having a diagnostic function disclosed in Patent Document 1. An object of the present invention is to provide a differential pressure measuring device capable of self-diagnosis of leakage of encapsulated liquid and mixing of hydrogen gas into the encapsulated liquid without removing the differential pressure measuring apparatus from the measurement line.

  The structural features are that when the differential pressure detector is in the normal state, an excessive pressure is applied to one seal diaphragm in the differential pressure detector and an atmospheric pressure is applied to the other seal diaphragm, and an excessive pressure is applied to the other seal diaphragm. And a memory circuit for storing the output of the differential pressure detector when the atmospheric pressure is applied to one of the seal diaphragms.

  At the time of diagnosis, when an overpressure is applied to the stored value of one memory circuit and one seal diaphragm and an atmospheric pressure is applied to the other seal diaphragm, or an overpressure is applied to the other seal diaphragm and an atmospheric pressure is applied to one seal diaphragm. A diagnostic circuit is provided that compares the output of the differential pressure detection unit when applied with the leakage to determine leakage of the encapsulated liquid and mixing of hydrogen gas into the encapsulated liquid.

  FIG. 8 is a main part configuration diagram showing an example of a differential pressure measuring device having a diagnostic function disclosed in Patent Document 2. As shown in FIG. This invention is a differential pressure measurement that can self-diagnose in severe environments where mechanical failure of the diaphragm seal and permeation of hydrogen gas frequently occur, such as high temperature of process fluid, strong corrosiveness, direct contact with process fluid, etc. The object is to provide a device.

  A structural feature is that, in a differential pressure measuring device having an encapsulated liquid, heating / cooling means for heating or cooling the encapsulated liquid and temporarily changing the internal pressure of the encapsulated liquid is provided, and this occurs when the heating / cooling means is in operation. Comparing the output change pattern with the normal state of the differential pressure measuring device, a detecting means for detecting breakage or abnormality of the seal diaphragm of the differential pressure measuring device and permeation of hydrogen is provided.

Japanese Patent Laid-Open No. 8-082566

JP 2003-156401 A

"Hydrogen erosion resistance of spiral stratified containers" Utsu et al., Journal of Petroleum Institute, Vol.14, No. 9, P.685, 1971

Conventional diagnostic methods have the following problems.
(1) For diagnosis, it is necessary to temporarily disconnect the differential pressure / pressure transmitter from the plant operating state. At this time, it may be necessary to stop the plant.

(2) A special measuring device for measuring the hydrogen permeation amount is required, the diagnostic device becomes large, the diagnostic cost is large, and it is not versatile.

  The present invention has been made to solve the above-described problems, and predicts and calculates the hydrogen permeation amount without requiring a special hydrogen permeation amount measurement device while the differential pressure / pressure transmitter remains on-line. The purpose is to realize a diagnostic device that can be used.

In order to achieve such a subject, the present invention has the following configuration.
(1) A diagnostic device for diagnosing a differential pressure / pressure transmitter that receives the pressure of a process fluid via a process diaphragm,
A diagnostic apparatus comprising hydrogen permeation amount calculating means for calculating the hydrogen permeation amount of the process diaphragm in real time based on the temperature and pressure of the process fluid and the hydrogen permeation coefficient of the process diaphragm.

(2) The hydrogen permeation amount calculation means includes a process stress model equation using the temperature and pressure of the process fluid and the hydrogen permeation coefficient of the process diaphragm as parameters .
Q_i = κ ・ A / d ・ (√P1_i-√P2_i-1) ・ exp (-Ea / (k ・ T_i)) ・ t_i
Q_i: Hydrogen permeation rate
A: Process diaphragm area
d: Process diaphragm thickness
T_i: Process temperature
P1_i: Process side pressure
P2_i-1 ： Previous value of pressure increase in pressure-receiving capsule
κ: coefficient
Ea: Activation energy
k: Boltzmann constant
t_i: The diagnostic apparatus according to (1), wherein the hydrogen permeation amount is calculated based on time .

(3) The diagnostic apparatus according to (1) or (2), further comprising on-line diagnostic means for predicting deterioration of the process diaphragm based on the hydrogen permeation amount by the hydrogen permeation amount calculating means.

(4) The diagnostic device according to (3), wherein the online diagnostic unit includes a notification unit that transmits a diagnostic result to at least one of a display device and an external device.

(5) The apparatus according to any one of (1) to (4), further comprising an instruction error correction unit that corrects a differential pressure or pressure instruction error based on the hydrogen permeation amount by the hydrogen permeation amount calculation unit. Diagnostic device.

(6) The apparatus includes (3) to (5) an off-line diagnosis unit that corrects a diagnosis result of the on-line diagnosis unit based on a zero-point drift amount in an off-line state in which the pressure of the process fluid is stopped. ) The diagnostic device according to any one of

(7) The method according to any one of (1) to (6), further comprising a parameter generation unit that measures the hydrogen permeation coefficient for each material of the process diaphragm and passes the hydrogen permeation amount to the hydrogen permeation amount calculation unit offline. Diagnostic equipment.

As is apparent from the above description, the present invention has the following effects.
(1) Since the hydrogen permeation amount can be measured while the differential pressure / pressure transmitter is on-line, there is no need to temporarily disconnect from the plant operating state for diagnosis, and there is no possibility of plant shutdown.

(2) By providing the on-line differential pressure / pressure measurement signal, temperature measurement signal, and hydrogen permeation coefficient to the process stress model equation to estimate and calculate the hydrogen permeation amount, no special hydrogen permeation amount measuring device is required. Therefore, it is possible to greatly reduce the diagnostic cost and contribute to the generalization of the device.

(3) Since the measurement error of the differential pressure / pressure transmitter due to hydrogen permeation can be corrected online, the measurement accuracy can be easily maintained.
(4) It is possible to predict in advance that the permeated hydrogen in the pressure-receiving capsule that has been suppressed by the pressure of the plant during operation of the plant expands when the pressure guiding tube is released and plastically deforms the process diaphragm and becomes unusable. Therefore, it is possible to reduce on-site troubleshooting work when an indication error occurs and the impact on the plant operation due to sudden accidents.

  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 diagnostic apparatus to which the present invention is applied. Elements 1 to 22 are components of a general differential pressure / pressure transmitter. The hydrogen permeation deterioration diagnosis device 100 and the parameter generation means 200 are elements that form the characterizing portion of the present invention.

  In FIG. 1, reference numeral 1 is a pipe line through which the process fluid F is transferred, and 2 is an orifice inserted into the pipe line. Reference numeral 3 denotes a high-pressure side pressure guiding pipe that guides the upstream pressure of the orifice 2 to the differential pressure / pressure transmitter 10. Reference numeral 4 denotes a low pressure side pressure guiding pipe that guides the downstream pressure of the orifice 2 to the differential pressure / pressure transmitter 10.

  5 is a high pressure side stop valve inserted into the high pressure side pressure guiding tube 3, 6 is a low pressure side stop valve inserted into the low pressure side pressure guiding tube 4, and 7 is a pressure equalizing valve. The figure shows a normal online state, in which the high-pressure side stop valve 5 and the low-pressure side stop valve 6 are opened, and the pressure equalizing valve 7 is closed.

  In the differential pressure / pressure transmitter 10, reference numeral 11 denotes a high pressure side pressure chamber, and a process fluid F on the upstream side of the orifice 2 is introduced through the high pressure side pressure guiding tube 3. Reference numeral 12 denotes a low-pressure side pressure chamber, and a process fluid F downstream of the orifice 2 is introduced through the low-pressure side pressure guiding tube 4.

  Reference numeral 13 denotes a pressure receiving capsule, which is provided with a high pressure side process diaphragm 14 that receives the pressure of the process fluid in the high pressure side pressure chamber 11 and a low pressure side process diaphragm 15 that receives the pressure of the process fluid in the low pressure side pressure chamber 12.

  The pressure receiving capsule 13 includes a flexible film forming a differential pressure / pressure sensor 16 therein, and the high pressure side pressure receiving pressure filled with a sealing liquid by the flexible film, the high pressure side process diaphragm 14 and the low pressure side process diaphragm 15. A chamber 17 and a low pressure side pressure receiving chamber 18 are formed.

  Reference numeral 19 denotes hydrogen accumulated in the high pressure side pressure receiving chamber 17 through the high pressure side process diaphragm 14, and reference numeral 20 denotes hydrogen accumulated in the low pressure side pressure receiving chamber 18 through the low pressure side process diaphragm 15. When hydrogen is accumulated in the pressure receiving chamber, it becomes impossible to correctly measure the differential pressure / pressure with the hydrogen pressure in the capsule, and when the hydrogen pressure exceeds a certain value, the process diaphragms 14 and 15 undergo plastic deformation, and the differential pressure・ The pressure transmitter is damaged and cannot be used.

  Reference numeral 21 denotes a process fluid temperature sensor. Reference numeral 22 denotes a receiving instrument that receives the differential pressure / pressure measurement signal EP from the differential pressure / pressure transmitter 10 and the process temperature measurement signal ET from the temperature sensor, and indicates the temperature-compensated differential pressure / pressure measurement value. Or, it transmits to the host device.

  Reference numeral 100 denotes a hydrogen permeation deterioration diagnosis apparatus that forms a feature of the present invention. In this hydrogen permeation deterioration diagnosis apparatus 100, 101 is a data collection means that receives and holds the differential pressure / pressure measurement signal EP and the process temperature measurement signal ET from the differential pressure / pressure transmitter 10 at regular intervals.

  Reference numeral 102 denotes a hydrogen permeation amount calculation means, and the hydrogen permeation amount and the total hydrogen permeation amount based on the collected process measurement values, the process stress model held in the model formula storage unit 103, and the hydrogen permeation coefficient set offline. Is calculated in real time.

  104 is an on-line diagnostic means for predicting the amount of accumulated hydrogen and the life expectancy that are allowed by the lifetime of the pressure-receiving capsule 13 based on the total hydrogen permeation amount calculated by the hydrogen permeation amount calculating means 102.

  An instruction error correction unit 105 estimates a measurement error of the differential pressure / pressure transmitter based on an increase in internal pressure due to hydrogen in the pressure receiving capsule, corrects an apparent instruction value of the receiving instrument 22 and corrects the true differential pressure. • Correct to the pressure measurement value.

  A diagnostic result display means 106 visually displays the outputs of the online diagnostic means 104, the instruction error correction means 105, and an offline diagnostic means 108 described later. Reference numeral 107 denotes notification means, which outputs the outputs of the online diagnosis means 104 and the instruction error correction means 105 to the diagnosis result display means 106 and transmits them to an external device as necessary.

  Reference numeral 108 denotes an off-line diagnosis unit that corrects the diagnosis result of the on-line diagnosis unit 104 based on the zero point drift amount in the off-line state in which the process fluid pressure is periodically stopped. The purpose of the off-line diagnostic means is to improve the reliability of prediction of the on-line diagnostic device.

  200 is a parameter generation means that measures a hydrogen permeation coefficient, which will be described later, offline for each process diaphragm used in the differential pressure / pressure transmitter 10, passes it to the hydrogen permeation amount calculation means 102, and substitutes it into the process stress model equation. Let

  FIG. 2 is a functional block diagram for explaining the operation of each means in the online diagnostic mode. Reference numeral 109 denotes a database provided in common, which holds the calculation results of the hydrogen permeation amount calculation means 102 and the online diagnostic device 104.

  FIG. 3 is a flowchart showing a signal processing procedure in each calculation unit in the hydrogen permeation amount calculation unit 102 and the online diagnosis unit 104, and includes steps S1 to S4. Hereinafter, the operation in the online diagnostic mode will be described with reference to each step of FIG.

  In the data collection means 101, reference numeral 101a denotes a periodic data sampling storage means that receives the differential pressure / pressure measurement signal EP and the process temperature measurement signal ET at regular intervals, and stores and holds them in the local database 101b.

  In the hydrogen permeation amount calculation means 102, reference numeral 102a denotes a Q_i calculation unit, which executes the signal processing in step S1 in FIG. That is, the pressure rise in the pressure receiving capsule calculated based on the sample data of the differential pressure / pressure measurement signal P1_i and the process temperature measurement signal T_i acquired from the database 101b and the total hydrogen permeation amount ΣQ_i-1 estimated in the previous calculation. Substituting the value P2_i-1 and the hydrogen permeation coefficient acquired from the parameter generation means 200 into the process stress model equation held in the model equation storage unit 103, the hydrogen permeation amount Q_i for each sample data is estimated and calculated, and the database 109 to be held.

  The process stress model formula held in the model formula storage unit 103 is based on the “model formula relating to the hydrogen erosion resistance of the spiral stratified container” disclosed in Non-Patent Document 1, and the hydrogen permeation amount Q_i is It is expressed by the following formula.

  Here, K and Ea are measured off-line by experiment for each process diaphragm used by the parameter generation unit 107 as hydrogen permeation coefficients, and are passed to the Q_i calculation unit 102a and set.

The process temperature T is the average value T = (T_i) of the previous sample value T_i-1 and the current sample value T_i.
−1 + T_i) / 2, the time t is the difference between the previous sample value t_i−1 and the current sample value t_i, t = (t_i−1−t_i), and the process side pressure P1 is the previous sample value P1_i−1. This time, the average value P1 = (P1_i-1 + P1_i) / 2 of the sample values P1_i is multiplied by a known hydrogen partial pressure ratio H2_ratio.

  Furthermore, the capsule internal pressure P2 is calculated by converting the total hydrogen amount ΣQ_i permeated up to the previous sampling into the apparent amount in use, and increasing the internal pressure by the coefficient of permeation amount versus pressure variation obtained for each process diaphragm material. Calculate That is, the pressure in the pressure receiving capsule at the time of manufacture is set to 1 atm, and the subsequent pressure increase due to the hydrogen permeation amount (10 Kpa per 1 ml of hydrogen permeation amount) is added to this.

  In calculating Q_i, P2_i-1 calculated in the previous sampling is acquired from the database 109 and executed. The calculation is performed for each of the high-pressure side and the low-pressure side, and is passed to the database 109 for holding.

  In the hydrogen permeation amount calculation means 102, 102b is a Q_now calculation unit, which executes the signal processing in step S2 of FIG. The calculation result Q_i of the Q_i calculation unit 102a is acquired from the database 109, and the total hydrogen permeation amount Q_now is calculated by Q_now = ΣQ_i (i = 1 to n) for each of the high pressure side and the low pressure side, and is passed to the database 109 and stored. Let

  In the online diagnostic unit 104, reference numeral 104a denotes a Q_rest calculation unit, which executes the signal processing in step S3 in FIG. The calculation result Q_now of the Q_now calculation unit 102b is acquired from the database 109, and the allowable permeated hydrogen amount Q_rest up to the life Q_life of the pressure-receiving capsule is calculated by Q_rest = Q_life−Q_now and transferred to the database 109 to be held. Here, Q_life is the lifetime hydrogen permeation amount that leads to plastic deformation of the process diaphragm obtained by calculation and experimental verification.

  In the online diagnostic means 104, 104b is a t_rest calculation unit, which calculates the remaining life t_rest until the process diaphragm reaches plastic deformation by executing the signal processing in step S4 in FIG. It is passed to the database 109 for holding. In the calculation procedure, the latest differential pressure / pressure measurement signal and the process temperature measurement signal are substituted into Q_rest to obtain a time t_rest to reach Q_life.

  Next, operations of the instruction error correction unit 105 and the diagnosis result display unit 106 will be described. In the command error correction means 105, 105a is a correction calculation unit, which acquires the high pressure side and low pressure side internal pressure increase values P2 from the database 109, and uses the difference as the command error value. The difference between the differential pressure / pressure measurement signal and the indicated error value is used as an error correction value, and the high pressure side and the low pressure side are calculated and passed to the local database 105b for holding.

  This error correction value is passed to the receiving instrument 22 at regular intervals, and an instruction error correction process is executed. 22a is an instruction value display screen, in which the instruction values before and after correction are displayed in comparison, and the instruction error due to permeated hydrogen can be grasped visually.

  In the diagnosis result display means 106, an instruction error trend display screen 106a displays an increasing tendency of the instruction error value for each sample period held in the database 105b. This makes it possible to visually grasp whether or not the measurement signal is within the required accuracy range in the current operating state.

  Reference numeral 106b denotes a hydrogen permeation amount trend display screen, which displays an increasing tendency of the total hydrogen permeation amount Q_now held in the database 109 up to now and Q_rest and t_rest on the high pressure side and the low pressure side visually. This makes it possible to intuitively understand the life expectancy of the process diaphragm.

  Next, the functional configuration and operation of the off-line diagnostic means 108 executed at a predetermined cycle will be described with reference to FIGS. FIG. 4 is a functional block diagram of another embodiment of the present invention showing an off-line diagnostic mode in which the differential pressure / pressure transmitter 10 stops receiving the process fluid F5. The difference from FIG. 1 is that the high pressure side stop valve 5 inserted into the high pressure side pressure guiding tube 3 and the low pressure side stop valve 6 inserted into the low pressure side pressure guiding tube 4 are closed and the pressure equalizing valve 7 is opened. Yes.

  FIG. 5 is a functional block diagram showing a related configuration of the data collection unit 101, the offline diagnosis unit 108, and the diagnosis result display unit 106. In the off-line diagnosis means 108, 108a is an evaluation / correction unit, which measures the zero point movement of the pressure-receiving capsule 13 by the measurement signal in the off-line state acquired from the database 101a of the data collection means 101, and performs the calculation in the on-line diagnosis. The result is evaluated and corrected, and transferred to the database 109 for holding.

  FIG. 6 is an explanatory diagram showing a calculation procedure of the evaluation / correction unit 108. The deviation between the zero point at the previous offline diagnosis shown in (A) and the zero point due to hydrogen permeation at the current offline diagnosis shown in (B) is measured. A correction value is determined based on this deviation amount.

  In the diagnosis result display means 106, 106c is a total hydrogen permeation amount correction screen, which visually displays the total hydrogen permeation amount of the online diagnosis result and the total hydrogen permeation amount corrected by the offline diagnosis. As a result, the error of the online diagnosis is corrected at a predetermined cycle, so that the reliability of the online diagnosis is ensured.

  The differential pressure / pressure transmitter shown in FIGS. 1 and 4 has a configuration in which the pressure receiving capsule is directly provided with a process diaphragm, but is connected to the process by a remote seal diaphragm and capillary piping, as shown in FIG. The present invention can also be applied to the hydrogen permeation deterioration diagnosis of the differential pressure / pressure transmitter.

It is a functional block diagram which shows one Embodiment of the diagnostic apparatus to which this invention is applied. It is a functional block diagram explaining operation | movement of each means in online diagnostic mode. It is a flowchart which shows the signal processing procedure in each calculating part in a hydrogen permeation amount calculating means and an on-line diagnostic means. It is a functional block diagram of other embodiments of the present invention showing an off-line diagnostic mode. It is a functional block diagram which shows the related structure of a data collection means, an offline diagnostic means, and a diagnostic result display means. It is explanatory drawing which shows the calculation procedure of the evaluation / correction | amendment part in an offline diagnostic means. It is a functional block diagram of the differential pressure measuring device provided with the diagnostic function currently disclosed by patent document 1. FIG. It is a principal part block diagram of the differential pressure measuring device provided with the diagnostic function currently disclosed by patent document 2. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Pipe line 2 Orifice 3 High pressure side pressure guiding tube 4 Low pressure side pressure guiding tube 5 High pressure side stop valve 6 Low pressure side stop valve 7 Pressure equalizing valve 10 Differential pressure / pressure transmitter 11 High pressure side pressure chamber 12 Low pressure side pressure chamber 13 Pressure receiving capsule 14 High pressure Side Process Diaphragm 15 Low Pressure Side Process Diaphragm 16 Differential Pressure / Pressure Sensor 17 High Pressure Side Pressure Receiving Chamber 18 Low Pressure Side Pressure Receiving Chamber 19, 20 Hydrogen 21 Temperature Sensor 22 Receiving Instrument 100 Hydrogen Permeation Deterioration Diagnosis Device 101 Data Collection Unit 102 Hydrogen Permeation Amount Calculation Unit 103 Model Expression Storage Unit 104 Online Diagnosis Unit 105 Instruction Error Correction Unit 106 Diagnosis Result Display Unit 107 Notification Unit 108 Offline Diagnosis Unit 200 Parameter Generation Unit

Claims (7)

A diagnostic device for diagnosing a differential pressure / pressure transmitter that receives the pressure of a process fluid through a process diaphragm,
A diagnostic apparatus comprising hydrogen permeation amount calculating means for calculating the hydrogen permeation amount of the process diaphragm in real time based on the temperature and pressure of the process fluid and the hydrogen permeation coefficient of the process diaphragm. The hydrogen permeation amount calculation means includes a process stress model equation using the temperature and pressure of the process fluid and the hydrogen permeation coefficient of the process diaphragm as parameters .
Q_i = κ ・ A / d ・ (√P1_i-√P2_i-1) ・ exp (-Ea / (k ・ T_i)) ・ t_i
Q_i: Hydrogen permeation rate
A: Process diaphragm area
d: Process diaphragm thickness
T_i: Process temperature
P1_i: Process side pressure
P2_i-1 ： Previous value of pressure increase in pressure-receiving capsule
κ: coefficient
Ea: Activation energy
k: Boltzmann constant
The diagnostic apparatus according to claim 1, wherein the hydrogen permeation amount is calculated based on t_i: time . The diagnostic apparatus according to claim 1, further comprising an on-line diagnosis unit that predicts deterioration of the process diaphragm based on a hydrogen permeation amount by the hydrogen permeation amount calculation unit. The diagnostic apparatus according to claim 3, wherein the online diagnostic unit includes a notification unit that transmits a diagnostic result to at least one of a display device and an external device. The diagnostic apparatus according to claim 1, further comprising an instruction error correction unit that corrects a differential pressure or pressure instruction error based on a hydrogen permeation amount by the hydrogen permeation amount calculation unit. 6. The off-line diagnosis unit that corrects a diagnosis result of the on-line diagnosis unit based on a zero point drift amount in an off-line state in which the pressure of the process fluid is stopped is provided. The diagnostic device described. The diagnostic apparatus according to any one of claims 1 to 6, further comprising a parameter generation unit that measures the hydrogen permeation coefficient for each material of the process diaphragm and transfers the hydrogen permeation amount to the hydrogen permeation amount calculation unit offline.

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