JP2016162024A - Flow rate control system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To manage the unsoundness of the flow rate control system of a controller under a higher degree of certainty.SOLUTION: A management index arithmetic unit 53 is provided in a positioner 5. The management index arithmetic unit 53 acquires an opening indication value θ_SP from a controller 4 and the actual opening θ_PV of a valve 2 detected by an opening detection unit 52 on a prescribed sampling cycle Δt, and finds, from the opening indication value θ_SP and actual opening θ_PV of the valve 2 within a prescribed period T that are acquired on sampling cycle Δt, a management index Aj(Aj=ΣΔθ_SPi÷ΣΔθ_PVi) as an index indicating the possibility of unsoundness of the flow rate control system of the controller 4. The management index Aj is sent to a host system 6, the reliability of the management index Aj is evaluated by a management index reliability evaluation unit 63, and a different kind of alarm is issued in accordance with the evaluation result.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a flow rate control system that controls the flow rate of a fluid flowing through a pipe.

  Conventionally, in a chemical plant or the like, a positioner is provided for a valve (control valve) that regulates the flow rate of a fluid (process fluid) passing through the pipe (process pipe), and the opening degree of the valve is controlled by the positioner. I am doing so. This positioner detects the actual opening degree of the valve and controls the opening degree of the valve so that the actual opening degree of the valve coincides with the opening degree instruction value sent from the host controller (controller).

  FIG. 10 shows a general flow control system using a positioner. In the figure, 1 is a process pipe, 2 is a valve for regulating the flow rate of the process fluid passing through the process pipe 1, and 3 is a flow rate for measuring an actual flow rate (mass flow rate or volume flow rate) of the process fluid passing through the process pipe 1. A total of 4 is a controller, 5 is a positioner attached to the valve 2, and 6 is a host system.

  In this flow control system, the host system 6 gives the flow command value F_SP to the controller 4. The controller 4 compares the actual flow rate F_PV of the process fluid measured by the flow meter 3 with the flow rate instruction value F_SP sent from the controller 4, and opens the opening of the valve 2 necessary to match the both. It is obtained as the degree instruction value θ_SP. The opening instruction value θ_SP obtained by the controller 4 is sent to the positioner 5. The positioner 5 detects the actual opening θ_PV of the valve 2 and controls the opening of the valve 2 so that the actual opening θ_PV of the valve 2 matches the opening instruction value θ_SP sent from the controller 4.

Japanese Patent No. 3007587

  However, in such a flow rate control system, if the flow rate control system of the controller 4 operates improperly, the opening degree instruction value θ_SP from the controller 4 may adversely affect the opening degree control system of the positioner 5. For this reason, the improvement of management of the flow rate control system of the controller 4 has been demanded.

  Patent Document 1 discloses a valve positioner that can determine that hunting has occurred in the operation of an electric actuator that drives a valve. The valve positioner disclosed in Patent Document 1 is a hunting determination that determines, during the control process of an electric actuator, that hunting in which the operating angle of the electric actuator changes in a predetermined range centered on a set value has occurred. Means.

  However, the valve positioner disclosed in Patent Document 1 detects a hunting phenomenon due to the unsoundness of the positioner opening control system, and does not focus on the unsoundness of the flow control system of the controller. .

  The present invention has been made to solve such a problem, and the object of the present invention is to manage unsoundness of the flow control system of the controller with higher accuracy. It is to provide a flow control system.

  In order to achieve such an object, the present invention measures the actual flow rate of a fluid passing through a pipe and a valve for regulating the flow rate of the fluid passing through the pipe in a flow control system that controls the flow rate of the fluid flowing through the pipe. Compare the actual flow rate of the fluid measured by the flow meter and the flow rate instruction value sent from the upper level, and obtain the opening degree of the valve necessary to match the two as the opening degree instruction value A controller, a positioner that detects the actual opening of the valve and controls the opening of the valve so that the actual opening of the valve matches the opening instruction value sent from the controller, and the opening instruction value and the valve At least one of the actual opening is acquired at a predetermined sampling cycle, and the control is performed from at least one of the opening instruction value and the actual opening of the valve within the predetermined period acquired at the predetermined sampling cycle. A management index calculation unit that determines, as a management index, an index that indicates the possibility of unhealthy flow rate control system of the controller; a management index reliability evaluation unit that evaluates the reliability of the management index calculated by the management index calculation unit; And an alarm reporting unit for reporting different types of alarms according to the management index reliability evaluation result by the management index reliability evaluation unit.

  In the present invention, the management index calculation unit acquires at least one of the opening instruction value and the actual opening of the valve at a predetermined sampling period, and the opening instruction value and the valve within a predetermined period acquired at the predetermined sampling period. An index indicating the possibility of unhealthyness of the flow control system of the controller is obtained as a management index from at least one of the actual opening degrees. For example, a ratio (corresponding to a management index Aj described later) of an integrated value of the change amount of the opening instruction value for each sampling cycle within a predetermined period and an integrated value of the change amount of the actual opening of the valve is obtained as a management index. The ratio between the integrated value of the change amount of the actual opening of the valve and the absolute value of the difference between the initial value and the final value of the actual opening of the valve for each sampling period within a predetermined period (corresponding to a management index Bj described later) As a management index, or a ratio between the integrated value of the change amount of the opening instruction value for each sampling period within a predetermined period and the absolute value of the difference between the initial value and the final value of the opening instruction value (the management index described later) (Corresponding to Cj), or an integrated value (corresponding to a management index Dj described later) of the absolute value of the difference between the actual opening of the valve and the opening instruction value for each sampling period within a predetermined period. Or ask for.

  In the present invention, the management index obtained by the management index calculation unit is evaluated for reliability by the management index reliability evaluation unit. For example, the reliability of the management index is evaluated based on the number of changes in the flow rate instruction value within a predetermined period, or the reliability of the management index is determined based on the confirmation result of whether the positioner opening control system is normal. The reliability of the management index is evaluated based on the evaluation result or the confirmation result of whether or not there is an abnormality in the flow control system of the controller. The alarm issuing unit issues different types of alarms according to the evaluation result of the reliability of the management index in the management index reliability evaluation unit. This makes it possible to manage the unsoundness of the flow control system of the controller with higher accuracy.

  In the present invention, when evaluating the reliability of the management index based on the confirmation result of whether or not the positioner opening control system is normal, for example, a step response test is performed on the positioner, and the step response test is performed. When the result is good, it is determined that there is a high possibility that there is an abnormality in the flow control system of the controller.

  Further, in the present invention, when evaluating the reliability of the management index based on the confirmation result of whether or not there is an abnormality in the flow control system of the controller, for example, the opening from the controller with respect to the change of the flow instruction value to the controller When the change of the indicated value is confirmed, and the change direction of the flow rate indicated value and the opening degree indicated value is opposite, it is determined that there is a possibility that the controller has a first abnormality in the flow rate control system. If the opening instruction value does not change with respect to the change beyond a predetermined time, it is determined that there is a possibility that the controller has a second abnormality in the flow rate control system.

  In the present invention, the reliability of the management index obtained by the management index calculation unit is evaluated. In this case, the obtained management index is compared with a predetermined threshold value, and the management index exceeds the threshold value. It is advisable to evaluate the reliability of management indicators only for items.

  According to the present invention, at least one of the opening instruction value and the actual opening of the valve is acquired at a predetermined sampling period, and the opening instruction value and the actual opening of the valve within a predetermined period acquired at the predetermined sampling period. An indicator indicating the possibility of unhealthy controller flow control system is obtained as a management indicator from at least one of the above, and the reliability of the obtained management indicator is evaluated, and different types of alarms are determined according to the evaluation result. Therefore, it is possible to manage the unsoundness of the flow rate control system of the controller with higher accuracy.

It is a figure which shows the principal part of one Embodiment of the flow control system which concerns on this invention. It is a functional block diagram of the principal part of this flow control system (functional block diagram of the principal part of the flow control system of Embodiment 1). It is a figure which shows the normal response when the flow rate instruction value is changed. It is a figure which shows the inappropriate response when a flow rate instruction | indication value is changed. 4 is a flowchart illustrating processing operations performed by a management index reliability evaluation unit and an alarm notification unit in the flow rate control system according to the first embodiment. FIG. 6 is a functional block diagram of a main part of a flow rate control system according to a second embodiment. 6 is a flowchart illustrating processing operations performed by a management index reliability evaluation unit and an alarm notification unit in the flow rate control system of the second embodiment. 10 is a flowchart illustrating processing operations performed by a management index reliability evaluation unit and an alarm notification unit in the flow rate control system according to the third embodiment. FIG. 10 is a functional block diagram of a main part of a flow rate control system according to a third embodiment. It is a figure which shows the general flow control system using a positioner.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  Prior to the description of the embodiments, the technical idea (important points of focus) of the present invention will be briefly described. When the valve (control valve) is used as an actuator of the flow control system, the inventor of the present application follows the opening instruction value when the feedback control of the flow control gives the opening instruction value in vibration. In this case, a problem was found that useless U-turn tracking (described later) may occur. And, it is possible to know the possibility of unhealthy flow control system by focusing on useless U-turn tracking as a management target, calculating and monitoring a management index as an index reflecting this phenomenon I came up with it. The embodiments described below are based on such a technical idea and show specific examples for realizing the present invention.

  FIG. 1 is a diagram showing a main part of an embodiment of a flow rate control system according to the present invention. The same reference numerals as those in FIG. 10 denote the same or equivalent components as those described with reference to FIG. The description is omitted. FIG. 2 is a functional block diagram of the main part of the flow control system.

  In the present embodiment, the controller 4 includes an opening degree instruction determination unit 41, and the positioner 5 includes an opening degree control unit 51, an opening degree detection unit 52, a management index calculation unit 53, and a management index transmission unit 54. 6 includes a flow rate instruction setting unit 61, a management index receiving unit 62, a management index reliability evaluation unit 63, an alarm notification unit 64, and a display unit 65.

  The processing operation of each unit in the controller 4, the positioner 5, and the host system 6 is realized by hardware including a processor and a storage device, and a program that realizes various functions in cooperation with these hardware. Specifically, the program is installed in the computer, and the processing operation of the CPU according to the installed program is realized.

  In the host system 6, the flow rate instruction setting unit 61 sends a flow rate instruction value F_SP to the controller 4. In the controller 4, the opening degree instruction determination unit 41 compares the flow rate instruction value F_SP sent from the host system 6 with the actual flow rate F_PV of the process fluid measured by the flow meter 3, and is necessary for matching them. The opening degree of the correct valve 2 is obtained as an opening degree instruction value θ_SP, and the obtained opening degree instruction value θ_SP is sent to the positioner 5.

  In the positioner 5, the opening detector 52 detects the actual opening θ_PV of the valve 2, and the opening controller 51 detects the opening instruction value θ_SP sent from the controller 4 and the valve 2 detected by the opening detector 52. The opening degree of the valve 2 is controlled so that the actual opening degree θ_PV coincides with the actual opening degree θ_PV. As a result, the flow rate of the process fluid flowing through the process pipe 1 is adjusted to the flow rate instruction value F_SP from the host system 6.

  In the positioner 5, the management index calculation unit 53 calculates the opening instruction value θ_SP from the controller 4 and the actual opening θ_PV of the valve 2 detected by the opening detection unit 52 at a predetermined sampling period Δt (for example, Δt = 50 ms). The possibility that the flow rate control system of the controller 4 is unhealthy from the opening instruction value θ_SP and the actual opening θ_PV of the valve 2 within a predetermined period T (for example, T = 20 s) acquired at the sampling period Δt. A management index Aj is obtained for each predetermined period T as an index indicating.

  In the positioner 5, the management index transmission unit 54 transmits the management index Aj obtained by the management index calculation unit 53 to the upper system 6 by digital communication. The management index Aj will be described later.

  In the host system 6, the management index receiving unit 62 receives the management index Aj sent from the positioner 5. In the host system 6, the management index reliability evaluation unit 63 compares the management index Aj received by the management index receiving unit 62 with a predetermined threshold Ath, and if the management index Aj exceeds the threshold Ath, the management index reliability evaluation unit 63 The reliability of the index Aj is evaluated, and the reliability evaluation result is sent to the alarm notification unit 64.

  The alarm notification unit 64 receives the evaluation result from the management index reliability evaluation unit 63 and issues different types of alarms according to the evaluation result. This alarm is sent to the display unit 65. The display unit 65 notifies the operator of an alarm from the alarm issue unit 64 on the screen. Note that an alarm may be notified to the operator by a ringing sound such as a buzzer.

[About management index Aj]
In this flow rate control system, when the flow rate instruction value F_SP from the host system 6 is changed, the controller 4 changes the opening degree instruction value θ_SP accordingly and transmits it to the positioner 5. In this case, a response as shown in FIG. 3 is usually obtained.

  FIG. 3 plots time series changes of the opening instruction value θ_SP and the actual opening θ_PV, with time on the horizontal axis and opening on the vertical axis. Following the change 50% → 55% of the opening instruction value θ_SP, the actual opening θ_PV follows with waste time and response delay. The state of response varies depending on the size of the valve 2 and the like.

  FIG. 4 shows an inappropriate response. In this example, the opening degree instruction value θ_SP is once changed from 50% to 60% and changed to 55% after 2 seconds. In this case, the actual opening θ_PV is once controlled toward 60%, exceeds 55%, and then is controlled again to 55%. Such tracking is called U-turn tracking.

  The valve 2 has many sliding portions, and generally adopting an integrated value of the sliding distance as an index for maintenance. The greater the number of movements, the higher the probability of failure. Therefore, if the integrated value of the sliding distance increases, the priority of maintenance is increased.

  In the inappropriate response shown in FIG. 4, the integrated value of the sliding distance tends to increase. After the opening instruction value θ_SP has once increased for some reason, it has settled to the target opening instruction value θ_SP (55%), and it can be seen that the actual opening θ_PV that has been followed has moved excessively.

  In the present embodiment, the management index Aj is used as an index reflecting the result of the phenomenon shown in FIG. That is, by calculating and monitoring an index based on the opening degree instruction value θ_SP and the actual opening degree θ_PV, the possibility of unsoundness of the flow rate control system of the controller 4 is known.

This management index Aj is obtained by the following equation (1).
Aj = ΣΔθ_SPi ÷ ΣΔθ_PVi (1)

In this equation (1), the subscript i of Δθ_SPi = | θ_SPi−θ_SPi ₋₁ |, Δθ_PVi = | θ_PVi−θ_PVi ₋₁ |, θ_SPi, θ_PVi is a sample of the opening instruction value and actual opening (for each sampling period Δt The subscript j of Aj is a management index sample (sample for each predetermined period T), ΣΔθ_SPi is an integrated value of Δθ_SPi within a predetermined period T, and ΣΔθ_PVi is an integrated value of Δθ_PVi within a predetermined period T.

  The management index Aj expressed by the equation (1) is an integration of the integrated value ΣΔθ_SPi of the change amount Δθ_SPi of the opening instruction value θ_SPi and the change amount Δθ_PVi of the actual opening θ_PVi of the valve 2 for each sampling period Δt within the predetermined period T. The ratio with the value ΣΔθ_PVi is shown.

  If the opening instruction value θ_SP moves more than the actual opening θ_PV, the management index Aj becomes large, and it can be estimated that this is a result of useless U-turn tracking. By monitoring this management index Aj, it is possible to know the possibility that the flow rate control system of the controller 4 is unhealthy.

  For example, the management index Aj at the normal response shown in FIG. 3 is Aj = 1.00, whereas Aj at the inappropriate response shown in FIG. 4 is Aj = 1.23 (i is Samples every 50 ms, j is every 20 s).

  If the opening degree instruction value θ_SP is normal, the management index Aj is close to 1.00, and as the management index Aj increases from 1.00, the sliding of the valve 2 due to the unhealthyness of the flow control system of the controller 4 There is a high possibility that the distance is unnecessarily large.

  Therefore, in the flow rate control system according to the present embodiment, the management index Aj is obtained every time the predetermined period T elapses in the management index calculation unit 53 provided in the positioner 5, and the management index Aj for each predetermined period T is obtained from the upper system 6. Monitoring is performed, and when the management index Aj exceeds the threshold value Ath, an alarm is automatically issued, thereby realizing unhealthy management of the flow control system of the controller 4.

The accumulated time for obtaining the management index Aj, that is, the predetermined period T (the number of samples I within the predetermined period T) in the management index calculation unit 53 is based on the following policies (1) and (2). decide.
(1) It is determined according to the time constant for the purpose of control (eg, it is sufficiently shorter than the time constant for temperature control).
* The change of the opening command value θ_SP accompanying the normal temperature setting value change is not unhealthy.
(2) It is determined according to the valve operating speed (the time required from fully closed to fully open) (eg, sufficiently longer than the valve operating speed).
* The management index is meaningless unless it is sufficiently longer than the actual opening θ_PV.

[Variations of management indicators]
In the above-described embodiment, the management index Aj represented by the above equation (1) is obtained as an index indicating the possibility of unhealthyness of the flow rate control system of the controller 4, but other similar management indices are available. There are various things.

[Management index Bj: Initial value and final value of θ_PV in a predetermined period (integrated time) T are also used]
For example, the management index Bj expressed by the following equation (2) is used to evaluate the difference between the endmost route to the value that is finally desired to be reached and the route that has actually passed (the absolute value integrated value).

Bj = ΣΔθ_PVi ÷ (| θ_PVi_Ij−θ_PVi_Ej |) (2)
In the equation (2), θ_PVi_Ij represents the value [%] of θ_PV at the start time of the sample j, and θ_PVi_Ej represents the value [%] of θ_PV at the last time of the sample j.

  The management index Bj represented by the above equation (2) is obtained by integrating the integrated value ΣΔθ_PVi of the change amount Δθ_PVi of the actual opening θ_PVi of the valve 2 and the initial value θ_PVi_Ij of the actual opening θ_PVi of the valve 2 for each sampling period Δt within the predetermined period T. And the absolute value | θ_PVi_Ij−θ_PVi_Ej | of the difference between the final value θ_PVi_Ej and the final value θ_PVi_Ej.

  When the management index Bj is greater than 1, θ_PV is passing through a useless route compared to the shortest route toward the final value. If the predetermined period (integrated time) T is sufficiently larger than the response speed of θ_PV, it is suggested that the sliding distance of the valve 2 may be increased unnecessarily due to the unsoundness of the flow control system of the controller 4. can do.

[Management index Cj: Initial value and final value of θ_SP in a predetermined period (integrated time) T are also used]
Similar to the management index Bj, the management index Cj represented by the following equation (3) is used to evaluate the difference between the most extreme path to the value to be finally reached and the actual path (the integrated value of the absolute value). Is used.

Cj = ΣΔθ_SPi ÷ (| θ_SPi_Ij−θ_SPi_Ej |) (3)
In the equation (3), θ_SPi_Ij represents the value [%] of θ_SP at the start time of the sample j, and θ_SPi_Ej represents the value [%] of θ_SP at the last time of the sample j.

  The management index Cj expressed by the above equation (3) includes the integrated value ΣΔθ_SPi of the change amount Δθ_SPi of the opening instruction value θ_SPi and the initial value θ_SPi_Ij and the final value θ_SPi_Ej of the opening instruction value θ_SPi for each sampling period Δt within the predetermined period T. And the absolute value | θ_SPi_Ij−θ_SPi_Ej |.

  When the management index Cj is larger than 1, it indicates that θ_SP tends to pass a useless route compared to the shortest route toward the final value. However, it is different from the management index Bj in that there is a possibility that such a change in θ_SP may be requested as a result of the control function of the host system 6, and attention should be paid to its use.

[Management index Dj: The difference between θ_PVi and θ_SPi is also used]
When the difference between the actual opening θ_PVi of the valve 2 and the opening instruction value θ_SPi is Ei = θ_PVi−θ_SPi, if the integrated value of | Ei | is large, the actual opening degree instruction value θ_SP is accompanied by a U-turn. There is a high possibility that the opening θ_PVi is also moving in vain. Therefore, paying attention to the integrated value of | Ei |, the management index Dj expressed by the following equation (4) is used.

Dj = Σ | Ei | (4)
In this equation (4), Σ | Ei | represents an integrated value of | Ei | within a predetermined period T.

  The management index Dj expressed by the above equation (4) indicates the integrated value of the absolute value | Ei | of the difference between the actual opening θ_PVi of the valve 2 and the opening instruction value θ_SPi for each sampling period Δt within the predetermined period T. ing.

  Since the actual opening θ_PVi of the valve 2 is delayed from the opening instruction value θ_SPi, the management index Dj is a management index having a certain size. Although the absolute value cannot be evaluated, it can be an index indicating the possibility of unsoundness of the flow control system of the controller 4 relative to the time series change of the management index Dj. For example, there is a high possibility that the flow rate control system of the controller 4 is unhealthy when, for example, the management index Dj tends to increase despite the control around the same opening degree.

  FIG. 5 shows a flowchart of processing operations performed by the management index reliability evaluation unit 63 and the alarm notification unit 64 in the host system 6.

  If the frequency of change of the flow rate instruction value F_SP to the controller 4 can be confirmed, the accuracy with respect to an index indicating the possibility of unhealthy flow rate control system of the controller 4 increases. If the flow rate instruction value F_SP is frequently changed, it is highly likely that the opening degree instruction value θ_SPi of the flow rate control system is not unhealthy. On the other hand, when the flow rate instruction value F_SP has not been changed or has been changed only once, the management index Aj becomes large, and the unhealthyness of the flow rate control system is suspected.

  Therefore, in the present embodiment (Embodiment 1), the management index reliability evaluation unit 63 compares the management index Aj received by the management index receiving unit 62 with a predetermined threshold Ath (step S101). When the management index Aj exceeds the threshold value Ath (YES in step S101), it is checked whether or not the flow rate instruction value F_SP to the controller 4 is changed more than once (step S102), and the check result is managed. The result is sent to the alarm reporting unit 64 as an evaluation result of the reliability of the index Aj.

  The alarm reporting unit 64 receives the evaluation result of the reliability of the management index Aj from the management index reliability evaluation unit 63, and when the change of the flow rate instruction value F_SP to the controller 4 is more than once, the alarm 1 (Step S103), and if the change in the flow rate instruction value F_SP to the controller 4 is less than once, alarm 2 is issued (step S104).

  In this case, alarm 1 and alarm 2 have different alarm types, and alarm 2 is more likely than alarm 1 to be more suspicious of the flow control system. That is, the alarm 2 is relatively more likely than the alarm 1 to be unhealthy in the flow control system.

[Embodiment 2]
In the first embodiment, the reliability of the management index Aj is evaluated based on the number of changes of the flow rate instruction value F_SP to the controller 4, but in the second embodiment, the opening control system of the positioner 5 is normal. Assume that the reliability of the management index Aj is evaluated based on the confirmation result of whether or not there is.

  If it can be confirmed that the position control system of the positioner 5 is normal, the accuracy with respect to the unsoundness of the flow control system of the controller 4 is increased. Therefore, in the second embodiment, whether or not the opening degree control system of the positioner 5 is normal by performing, for example, a step response test or the like when the plant is stopped with respect to the valve 3 whose management index Aj exceeds the threshold value Ath. Confirm whether or not and give the confirmation result to the management index reliability evaluation unit 63 (see FIG. 6).

  In this case, if the management index Aj is large (FIG. 7: YES in step S201) and the result of the step response test is good (YES in step S202), the management index reliability evaluation unit 63 It is determined that there is a high possibility that there is an abnormality in the flow control system, and an evaluation result to that effect is sent to the alarm notification unit 64. If the result of the step response test is not good (NO in step S202), it is determined that the possibility that there is an abnormality in the flow rate control system of the controller 4 is low, and the evaluation result to that effect is sent to the alarm notification unit 64. send.

  The alarm reporting unit 64 receives the evaluation result from the management index reliability evaluating unit 63, and issues an alarm 3 when it is determined that there is a high possibility that the flow rate control system of the controller 4 is abnormal. (Step S203), if it is determined that there is a low possibility of an abnormality in the flow rate control system of the controller 4, the alarm 4 is issued (Step S204).

  In this case, the alarm 3 and the alarm 4 have different alarm types, and the alarm 4 has a higher suspicion of unhealthy flow control system than the alarm 3. That is, the alarm 4 is relatively more likely than the alarm 3 to be unhealthy in the flow control system.

[Embodiment 3]
In the second embodiment, the reliability of the management index Aj is evaluated based on the confirmation result of whether or not the opening control system of the positioner 5 is normal. However, in the third embodiment, the flow rate of the controller 4 Assume that the reliability of the management index Aj is evaluated based on the confirmation result of whether or not there is an abnormality in the control system.

  If it can be confirmed that there is a large abnormality in the flow control system of the controller 4, the accuracy with respect to the unhealthyness of the flow control system of the controller 4 increases. Therefore, in the third embodiment, when the management index Aj exceeds the threshold value Ath, the management index reliability evaluation unit 63 checks whether there is an abnormality in the flow control system of the controller 4.

Two examples of abnormalities in the flow control system of the controller 4 are given below.
(1) Instruction in the direction opposite to the opening instruction value (Case 1)
This is a case where the controller 4 gives an instruction for decreasing the opening degree instruction value θ_SP to the positioner 5 with respect to a signal for increasing the flow rate instruction value F_SP. It is expected that a fatal abnormality exists in the controller 4, such as whether the gain of the control loop is opposite.
(2) Opening indication value does not move (Case 2)
Although the flow rate instruction value F_SP is changed, the opening degree instruction value θ_SP does not move, and it is expected that the controller 4 moves very slowly.

  FIG. 8 shows a flowchart when these two cases are assumed, and FIG. 9 shows a functional block diagram corresponding to FIG.

  The management index reliability evaluation unit 63 checks whether or not the change rate of the flow rate instruction value F_SP from the previous time is equal to or greater than a predetermined threshold e_F_SP (step S301), and the change range of the flow rate command value F_SP from the previous time. Is greater than or equal to the threshold e_F_SP (YES in step S301), the timer is counted up (step S302), and it is checked whether or not the change width of the opening instruction value θ_SP from the previous time is equal to or greater than the threshold e_θ_SP (step). S303). If the change range of the opening instruction value θ_SP from the previous time is not equal to or greater than the threshold value e_θ_SP (NO in step S303), the process returns to step S302 through step S304, and the processes in steps S302 to 304 are repeated.

  If the change range of the opening instruction value θ_SP from the previous time becomes equal to or greater than the threshold value e_θ_SP during the repetition of the processes of steps S302 to S304 (YES in step S303), the management index reliability evaluation unit 63 changes the direction of the flow instruction value F_SP. And whether the change direction of the opening instruction value θ_SP is opposite (step S305). If the change direction of the flow instruction value F_SP is opposite to the change direction of the opening instruction value θ_SP (YES in step S305), It is determined that there is a possibility that the flow rate control system of the controller 4 has a first abnormality (abnormality in case 1), and an evaluation result to that effect is sent to the alarm reporting unit 64.

  During the repetition of the processing of steps S302 to 304, the management index reliability evaluation unit 63 does not make the change width of the opening instruction value θ_SP from the previous time equal to or greater than the threshold e_θ_SP (NO in step S303), and the timer in step S302 If the count value exceeds the predetermined value N (YES in step S304), it is determined that there is a possibility that the flow rate control system of the controller 4 has a second abnormality (abnormality in case 2), and an evaluation result to that effect is alarmed. It is sent to the reporting unit 64.

  The alarm reporting unit 64 receives the evaluation result from the management index reliability evaluation unit 63, and if it is determined that there is a possibility that the flow rate control system of the controller 4 has the first abnormality, the alarm reporting unit 64 An alarm is issued (step S306), and if it is determined that there is a possibility of a second abnormality in the flow rate control system of the controller 4, an alarm 6 is issued (step S307). In this case, alarm 5 and alarm 6 have different alarm types, and alarm 5 indicates that the unhealthyness of the flow rate control system is higher than that of alarm 6.

  In the above-described embodiment, the management index calculation unit 53 is provided in the positioner 5, but may be provided in the host system 6. Conversely, the management index reliability evaluation unit 63 and the alarm notification unit 64 may be provided in the positioner 5, and various modifications are possible.

[Extension of the embodiment]
The present invention has been described above with reference to the embodiment. However, the present invention is not limited to the above embodiment. Various changes that can be understood by those skilled in the art can be made to the configuration and details of the present invention within the scope of the technical idea of the present invention.

  DESCRIPTION OF SYMBOLS 1 ... Process piping, 2 ... Valve, 3 ... Flow meter, 4 ... Controller, 5 ... Positioner, 6 ... Host system, 41 ... Opening direction determination part, 51 ... Opening control part, 52 ... Opening degree detection part, 53 ... management index calculation unit, 54 ... management index transmission unit, 61 ... flow rate instruction setting unit, 62 ... management index reception unit, 63 ... management index reliability evaluation unit, 64 ... alarm reporting unit, 65 ... display unit.

Claims (7)

In the flow rate control system that controls the flow rate of the fluid flowing through the piping,
A valve for regulating the flow rate of the fluid passing through the pipe;
A flow meter for measuring the actual flow rate of the fluid passing through the pipe;
A controller that compares the actual flow rate of the fluid measured by the flow meter with the flow rate instruction value sent from the host, and obtains the opening degree of the valve necessary to match the two as the opening degree instruction value;
A positioner that detects the actual opening of the valve and controls the opening of the valve so that the actual opening of the valve matches an opening instruction value sent from the controller;
At least one of the opening instruction value and the actual opening of the valve is acquired at a predetermined sampling period, and from at least one of the opening instruction value and the actual opening of the valve within a predetermined period acquired at the predetermined sampling period A management index calculation unit for obtaining an index indicating the possibility of unhealthy flow rate control system of the controller as a management index;
A management index reliability evaluation unit that evaluates the reliability of the management index obtained by the management index calculation unit;
A flow rate control system comprising: an alarm notification unit that issues different types of alarms according to a result of evaluation of reliability of the management index by the management index reliability evaluation unit. The flow control system according to claim 1,
The management index reliability evaluation unit
The flow rate control system characterized in that the reliability of the management index is evaluated based on the number of changes of the flow rate instruction value within the predetermined period. The flow control system according to claim 1,
The management index reliability evaluation unit
A flow rate control system characterized in that the reliability of the management index is evaluated based on a confirmation result of whether or not the position control system of the positioner is normal. The flow control system according to claim 1,
The management index reliability evaluation unit
A flow rate control system characterized in that the reliability of the management index is evaluated based on a confirmation result of whether or not there is an abnormality in the flow rate control system of the controller. The flow control system according to claim 3,
The management index reliability evaluation unit
When the result of the step response test performed on the positioner is good, it is determined that there is a high possibility that there is an abnormality in the flow control system of the controller. The flow control system according to claim 4, wherein
The management index reliability evaluation unit
When the change of the opening instruction value from the controller with respect to the change of the flow instruction value to the controller is confirmed, and the change direction of the flow instruction value and the opening instruction value is opposite, the flow control system of the controller If it is determined that there is a possibility that there is an abnormality of 1 and the opening degree indication value does not change even after a predetermined time with respect to the change of the flow indication value, a second abnormality is present in the flow control system of the controller. A flow control system characterized by determining that there is a possibility. In the flow control system according to any one of claims 1 to 6,
The management index reliability evaluation unit
The flow rate control characterized by comparing the management index obtained by the management index calculation unit with a predetermined threshold value, and evaluating the reliability of the management index when the management index exceeds the threshold value system.

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