JP2009092110A - Shut-off valve control system and method for predicting failure of shut-off valve control system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a shut-off valve control system capable of testing an operation during normal operation and predicting a failure of a component, and to provide a method for predicting a failure of the shut-off valve control system. <P>SOLUTION: The shut-off valve control system is provided with a shut-off valve and a control means that controls the opening of the shut-off valve, having an electromagnetic valve 5 for supplying air from an air supply source to an air cylinder drive valve that controls the rotation of the valve shaft of the shut-off valve and a cylinder of the air cylinder drive valve and for exhausting air from them. The system is furthermore provided with a pressure sensor 6 which detects the inner pressure of the cylinder, and a discriminating means 7 which discriminates normal/abnormal states of the system based on the pressure characteristic of the inner pressure of the cylinder actually measured by the pressure sensor 6 when the shut-off valve is controlled by the control means so as to be operated from a fully-opened state to a closing direction with a predetermined opening. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a shutoff valve control system and a failure prediction method for a shutoff valve control system.

  Oil pipes and gas pipelines in plant facilities are provided with shut-off valves such as ball valves to urgently shut down the lines when an abnormality occurs in the facilities. The shut-off valve was checked for the presence or absence of a failure by performing an operation test of shutdown (fully opened to fully closed) about once a year.

  However, if the shut-off valve is fully closed, the plant is stopped and the normal operation is hindered. Therefore, the operation test of the shut-off valve cannot be executed during the normal operation. Therefore, there is a need for a shut-off valve control system that can perform a shut-off valve operation test during normal operation.

  An object of the present invention is to provide a shut-off valve control system and a shut-off valve control system failure prediction method capable of performing an operation test during normal operation and predicting a failure of a system component or the like.

  The invention according to claim 1, which has been made to solve the above-described problems, includes a shutoff valve, an air cylinder drive valve that controls the rotation of the valve shaft of the shutoff valve, and an air from an air supply source to the cylinder of the air cylinder drive valve. And a control means for controlling the opening degree of the shut-off valve, comprising: a pressure sensor for detecting an internal pressure of the cylinder; and the control means. And determining means for determining normality / abnormality of the system based on the pressure characteristic of the cylinder internal pressure measured by the pressure sensor when the shut-off valve is controlled to operate in the closing direction of the predetermined opening from fully open. It exists in the shut-off valve control system characterized by having.

  The invention according to claim 2, which has been made to solve the above problem, is the shutoff valve control system according to claim 1, wherein the pressure characteristic at the time of initial normal operation of the system, the pressure characteristic at the time of failure, and the pressure at the failure prediction boundary Storage means for preliminarily storing characteristics, and the determination means determines normal if the actually measured pressure characteristic is within a range between the pressure characteristic during normal operation and the pressure characteristic at the failure prediction boundary. In the shut-off valve control system, when it is within a range between the pressure characteristic at the failure prediction boundary and the pressure characteristic at the time of the failure, it is determined as abnormal.

  The invention according to claim 3, which has been made to solve the above problem, is the shutoff valve control system according to claim 1 or 2, wherein the solenoid valve includes a large flow rate three-way solenoid valve that is normally used, and an operation test. The present invention resides in a shutoff valve control system characterized by being a solenoid valve in which a small flow three-way solenoid valve used sometimes is built in one body.

  In order to solve the above-mentioned problem, an invention according to claim 4 includes a shutoff valve, an air cylinder drive valve for rotationally controlling the valve shaft of the shutoff valve, and an air from an air supply source to the cylinder of the air cylinder drive valve. And a control means for controlling the opening degree of the shut-off valve, and detecting an internal pressure of the cylinder and opening the shut-off valve from a fully open position to a predetermined opening degree. The pressure characteristics of the cylinder internal pressure actually measured when it is controlled to operate in the closing direction are stored in advance as the pressure characteristics at the initial normal operation of the system, the pressure characteristics at the time of failure, and the pressure characteristics at the failure prediction boundary. In comparison, when the actually measured pressure characteristic is within the range between the pressure characteristic during normal operation and the pressure characteristic at the failure prediction boundary, it is determined as normal, and the pressure at the failure prediction boundary is determined. If in the range between the pressure characteristic at the time of said failure and characteristic lies in failure prediction method of the cutoff valve control system and determining that the abnormality.

  In order to solve the above-mentioned problems, an invention according to claim 5 is directed to a shutoff valve, an air cylinder drive valve for controlling rotation of a valve shaft of the shutoff valve, and an air from an air supply source to the cylinder of the air cylinder drive valve. And a control means for controlling the opening degree of the shut-off valve, and a potentiometer for detecting displacement of the valve shaft of the shut-off valve, Determining means for determining normality / abnormality of the system based on a displacement characteristic of the valve shaft of the shut-off valve measured by the potentiometer when the shut-off valve is controlled to operate in a closing direction from a fully open position to a predetermined opening by the control means. And a shut-off valve control system.

  In order to solve the above-mentioned problem, the invention according to claim 6 is the shut-off valve control system according to claim 5, wherein the initial displacement of the system during normal operation, the displacement characteristic at the time of failure, and the displacement of the failure prediction boundary Storage means for preliminarily storing characteristics, and the determination means determines normal if the measured displacement characteristics are within a range between the displacement characteristics during normal operation and the displacement characteristics of the failure prediction boundary. In the shut-off valve control system, when it is within the range between the displacement characteristic of the failure prediction boundary and the displacement characteristic at the time of the failure, it is determined as abnormal.

  According to the first aspect of the invention, the normality / abnormality of the system is determined based on the pressure characteristics of the cylinder internal pressure measured by the pressure sensor when the control means is controlled to operate the shutoff valve from the fully open position to the predetermined opening closing direction. Therefore, when installed in the pipeline of the plant equipment, an operation test for judging the failure / abnormality of the system can be performed during the normal operation of the plant equipment.

  According to the second aspect of the present invention, when the actually measured pressure characteristic is within the range between the pressure characteristic at the initial normal operation of the system and the pressure characteristic of the failure prediction boundary, it is determined as normal, and the failure prediction boundary If it is within the range between the pressure characteristic and the pressure characteristic at the time of failure, it is determined that there is an abnormality. Therefore, it is possible to predict a failure of a system component or the like depending on where the actually measured pressure characteristic is in the above range.

  According to the invention described in claim 3, the solenoid valve is a solenoid valve in which a large-flow three-way solenoid valve used during normal operation and a small-flow three-way solenoid valve used during operation test are built in one body. Therefore, it is easy to determine normality / abnormality during the operation test. Further, even if the large flow rate three-way solenoid valve breaks down, the shutoff valve can be opened and closed by switching to the small flow rate three-way solenoid valve.

  According to the fourth aspect of the present invention, when the actually measured pressure characteristic is within the range between the pressure characteristic at the initial normal operation of the system and the pressure characteristic of the failure prediction boundary, it is determined as normal, and the failure prediction boundary If it is within the range between the pressure characteristic and the pressure characteristic at the time of failure, it is determined that there is an abnormality. Therefore, a system failure can be predicted depending on where the actually measured pressure characteristic is in the above range.

  According to the fifth aspect of the present invention, the normality of the system is determined based on the displacement characteristic of the valve shaft of the shut-off valve measured by the potentiometer when the shut-off valve is controlled to be operated from the fully open position to the predetermined opening closing direction by the control means. Therefore, an operation test for determining a system failure / abnormality can be performed during normal operation of the plant equipment when installed in a pipeline of the plant equipment.

  According to the sixth aspect of the present invention, when the measured displacement characteristic is within the range between the displacement characteristic at the initial normal operation of the system and the displacement characteristic of the failure prediction boundary, it is determined to be normal, and the failure prediction boundary If it is within the range between the displacement characteristic and the displacement characteristic at the time of failure, it is determined as abnormal, and therefore a failure of a system component or the like can be predicted depending on where the measured displacement characteristic is in the above range.

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

  FIG. 1 shows a configuration of a shutoff valve control system of the present invention, where (A) is a front view and (B) is a partial cross-sectional view. The shut-off valve control system is mounted on the shut-off valve 1 and an upper portion of the shut-off valve 1 via a fixed yoke 2, and controls the opening degree of the shut-off valve 1 and the upper portion of the air cylinder drive valve 3. An outdoor type or explosion-proof position box 4 is provided. The position box 4 houses an electromagnetic valve 5, a pressure sensor (electronic digital pressure gauge) 6, a microcomputer (hereinafter referred to as a microcomputer) 7, a potentiometer 8, and the like. The air cylinder drive valve 3 and the electromagnetic valve 5 correspond to the control means in the claims, and the microcomputer 7 corresponds to the determination means in the claims.

  The shut-off valve 1 is composed of, for example, a ball valve having a ball-shaped valve body 1a, and is connected to, for example, a pipeline of plant equipment. A valve shaft 1b extending upward is connected to the valve body 1a. The valve body 1a is switched between a fully open state (see FIG. 1B) and a fully closed state when the valve shaft 1b rotates 90 degrees. The periphery of the valve body 1a is sealed with a seat packing 1c, and the periphery of the valve shaft 1b is sealed with a gland packing 1d.

  As shown in FIG. 2, the air cylinder drive valve 3 is provided with a pair of pistons 33 and 34 connected by a piston rod 32 in a single-acting pneumatic cylinder 31. One piston 33 is urged so as to always slide in the valve closing direction (right direction in FIG. 2) by the urging force of a coil spring 35 disposed in one end of the cylinder 31. The other piston 34 opens in the valve opening direction against the biasing force of the coil spring 35 by the air supplied from the outlet port OUT of the electromagnetic valve 5 connected to the air inlet 36 provided at the other end of the cylinder 31 ( It is urged to slide toward the left in FIG. The piston rod 32 is provided with a transmission mechanism 37 that converts the reciprocating motion of the piston rod 32 into a rotational motion and transmits the rotational motion to the valve shaft 1b. The transmission mechanism 37 has an engagement pin 37a projecting from the piston rod 32 and a bifurcated engagement piece 37b attached to the upper end of the valve shaft 1b. The engagement pin 37a has a bifurcated engagement piece 37b. By engaging the tip and moving the engagement pin 37a to the left and right, the two-piece engagement piece 37b is rotated, whereby the valve shaft 1b is rotated 90 degrees.

  The solenoid valve 5 has two three-way solenoid valves, a large flow rate three-way solenoid valve 5A and a small flow rate three-way solenoid valve 5B, incorporated in one body. The large flow rate three-way solenoid valve 5A has solenoids A and B for switching the valve. The effective sectional area of the valve is large, and when an abnormality occurs in the pipeline, the air cylinder drive valve 2 is rapidly closed. And is used for emergency shut-off to shut off the shut-off valve 1 urgently. The small flow rate three-way solenoid valve 5B has solenoids C and D for switching valves, and the effective sectional area of the valve is smaller than that of the large flow rate three-way solenoid valve 5A, and is used when performing a system operation test. It is for operation test. The inlet port IN, the outlet port OUT, and the exhaust port EXH of each of the large flow rate three-way solenoid valve 5A and the small flow rate three-way solenoid valve 5B are connected to each other. Port OUT and exhaust port EXH. The solenoid valve 5 supplies air from an air supply source 11 outside the position box 4 from a common inlet port IN to a common outlet port OUT via a large flow rate three-way solenoid valve 5A or a small flow rate three-way solenoid valve 5B. The air in the cylinder 21 is supplied to the cylinder 31 of the air cylinder driving valve 3 via the common outlet port OUT, and is supplied via the large flow rate three-way solenoid valve 5A or the small flow rate three-way solenoid valve 5B. Exhaust into the atmosphere via the exhaust port EXH.

  FIG. 3 is a block diagram showing an electrical configuration of the shut-off valve control system. In the shutoff valve control system, a solenoid valve 5, a pressure sensor 6, a microcomputer 7, and a potentiometer 8 are connected to a power source 10. The pressure sensor 6 detects the cylinder internal pressure on the inlet 36 side of the air cylinder drive valve 3 and supplies a detection signal to the microcomputer 7. The potentiometer 8 detects the rotational position of the valve shaft 1 b and supplies a detection signal to the microcomputer 7. The microcomputer 7 performs energization control of the solenoid of the solenoid valve, calculates the detection signal of the pressure sensor 6 and the potentiometer 8 to determine normality / failure of the system, and outputs a determination signal from the external output unit 9.

  In the shut-off valve control system having the above-described configuration, the present invention is configured to exhaust air from the solenoid valve 5 and actuate the shut-off valve 1 from the valve opening direction to the valve closing direction during the operation test. A system failure is predicted by observing changes in internal pressure over time (hereinafter referred to as pressure characteristics).

  Hereinafter, the failure prediction method will be described, but before that, the normal operation of the shutoff valve control system will be described.

  First, the switching solenoid valve 5 of the air cylinder drive valve 3 has two valves (a large flow rate three-way solenoid valve 5A and a small flow rate three-way solenoid valve 5B) built in one body. Therefore, normally, a large flow three-way solenoid valve 5A is used. At this time, the small flow rate three-way solenoid valve 5B is controlled to be in a power failure state, and is in an all-port block state in which all three ports are closed. The large flow rate three-way solenoid valve 5A and the small flow rate three-way solenoid valve 5B are electrically interlocked by the control of the microcomputer 7 so that when one solenoid valve is energized, the other solenoid valve is in a power failure state. Therefore, both are not energized at the same time.

  When the solenoid A of the large flow rate three-way solenoid valve 5A is energized and the solenoid B is energized, the air from the air supply source 11 is supplied from the common inlet port IN of the solenoid valve 5 through the large flow rate three-way solenoid valve 5A. It is supplied to the cylinder 31 from the inlet 36 via the common outlet port OUT, and the piston 24 slides leftward, so that the shut-off valve 1 is fully opened. Thereby, the pipeline can be operated while the solenoid B is energized. Note that the large flow rate three-way solenoid valve 5A is electrically interlocked by the control of the microcomputer 7 so that the other solenoid is not energized while one solenoid is energized.

  Next, when the microcomputer 7 energizes the solenoid A based on the abnormality detection signal of the plant equipment or the operation signal of the emergency cut-off switch (not shown), the air in the cylinder 21 is supplied from the outlet port OUT of the electromagnetic valve 5 to the large flow three-way electromagnetic. The air is exhausted from the common exhaust port EXH to the atmosphere via the valve 5A, the piston 24 slides from the left to the right by the spring load, the valve shaft 1a rotates 90 degrees, and the shutoff valve 1 is fully closed. Become. As a result, the pipeline is urgently shut off while the solenoid A is energized.

  In the above operation, either solenoid A or B is controlled so that it is always energized. However, as another embodiment, the solenoid B is energized and fully opened while the solenoid A remains in a power failure state. If the solenoid B also fails after the power is turned off, the large flow three-way solenoid valve 5A is in the all-port block state, the shut-off valve 1 is kept fully open, and the solenoid B is energized and the solenoid A is energized and fully closed. When the solenoid A is also powered down after becoming, the all-port block state is entered, and the shutoff valve 1 maintains the fully closed state. Thus, both the solenoids A and B are in the fully open state or the fully closed state. Power consumption can be reduced by controlling the power to the power failure state.

  Next, the operation at the time of the operation test including the prediction of failure will be described. At the time of the operation test, a small flow rate three-way solenoid valve 5B is used.

  When the shutoff valve 1 is fully open and the pipeline is in an operating state, when the microcomputer 7 energizes the solenoid D of the small flow rate three-way solenoid valve 5B based on an operation signal of an operation test switch (not shown), the large flow rate three-way solenoid. The valve 5A is controlled to be in a power failure state, and is in an all-port block state in which all three ports are closed. The air in the cylinder 31 is exhausted from the common outlet port OUT of the solenoid valve 5 to the atmosphere through the small flow rate three-way solenoid valve 5B, and from the common exhaust port EXH to the piston 34 from the left by the spring load. Sliding to the right, the shut-off valve 1 operates from the fully open state to the closing direction.

  At this time, energization of the solenoid D is stopped when the shutoff valve 1 is operated in the closing direction by a predetermined opening degree set in advance from the fully opened state, and at the same time, the solenoid C is energized. The predetermined opening is set to such an extent that does not hinder normal operation of the pipeline of the plant equipment, and is set to, for example, 10 to 15 degrees.

  When the solenoid C is energized, the air from the air supply source 11 is supplied from the common inlet port IN of the electromagnetic valve 5 to the cylinder 31 from the inlet 36 via the small outlet three-way electromagnetic valve 5B and the common outlet port OUT. , The piston 34 slides in the left direction, and the shut-off valve 1 returns to the fully open state. Note that the small flow rate three-way solenoid valve 5B is electrically interlocked under the control of the microcomputer 7 so that the other solenoid is not energized while one solenoid is energized.

  As described above, during the operation test, the change over time in the cylinder internal pressure of the air cylinder drive valve 3 when the shut-off valve 1 is operated in the closing direction by a predetermined opening degree set in advance from the fully opened state (hereinafter referred to as pressure characteristics). Is measured based on the detection signal of the pressure sensor 6, and failure determination is performed based on the transition of the measured pressure characteristic. Specifically, the pressure characteristics measured at the time of the operation test are stored in the memory of the microcomputer 7 in advance, the pressure characteristics at the time of normal operation (curve A in FIG. 4 described later), the pressure characteristics at the time of failure (described later) The curve B) in FIG. 4 and the pressure characteristic of the failure prediction boundary (failure prediction boundary C in FIG. 4 described later) are compared, and failure determination is performed based on the comparison result.

  Initial pressure characteristics during normal operation (curve A in FIG. 5 to be described later), pressure characteristics at failure (curve B in FIG. 5 to be described later), and pressure characteristics at the failure prediction boundary (failure prediction boundary line C in FIG. 5 to be described later) ) Is calculated as follows.

The operation of the air cylinder driving valve 3 according to the change in the cylinder internal pressure will be described. When the diameter of the piston 34 is D due to the supply pressure due to the supply of air from the inlet 36, the pressure receiving area Ac of the piston 34 is πD ^2. / 4, and the generated force is pressure receiving area Ac × cylinder internal pressure P. On the other hand, when the coil spring 35 having the spring constant k moves and bends by the displacement x, the spring load becomes kx.

  Therefore, if the mass, starting resistance (friction resistance), displacement, speed, and acceleration of the piston are m, C, x ′, and x ″, respectively, (mx ″ + Cx ′ + kx) <(P × Ac) At this time, the piston 34 moves from the right side to the left side, and the ball-shaped valve body 1a of the shutoff valve 1 connected at that time rotates in the opening direction. When the displacement x of the piston 34 of the cylinder 31 moves to the left by the maximum movement distance, the ball-shaped valve body 1a of the shut-off valve 1 rotates 90 degrees in the opening direction and is fully opened.

  From the state where the shut-off valve 1 is fully open, the air in the cylinder 31 is released to the atmosphere via the small flow rate three-way electromagnetic valve 5B. When kx> {(P × Ac) + mx ″ + Cx ′}, the piston 34 moves from the left side to the right side, and the ball-shaped valve element 1a of the shut-off valve 1 connected at that time rotates in the closing direction. When the displacement x of the piston 34 of the cylinder 31 moves to the right by the maximum movement distance, the ball-shaped valve body 1a of the shut-off valve 1 rotates 90 degrees in the closing direction and becomes fully closed.

  In this way, the full stroke operation confirmation test from the fully open state to the fully closed state of the shut-off valve 1 when using the small flow rate three-way solenoid valve 5B is a trial operation in which a shut-off valve control system is installed in the pipeline of the plant equipment. In this case, the temporal change in the cylinder internal pressure of the air cylinder drive valve 3 at that time is measured and stored in advance in the memory (storage means) of the microcomputer 7 as the pressure characteristic during the initial normal operation.

  The microcomputer 7 can be repeatedly calculated by changing the numerical value of each parameter in the calculation formula so as to approximate the actual measurement value using the following three calculation formulas, that is, the equation of motion, the equation of state, and the thermal energy equation. Function to store the matched parameters as data.

(Equation of motion) mx ″ + Cx ′ + P × Ac = kx (1)
Where m: piston mass of the air cylinder drive valve 3, C: starting resistance of the air cylinder drive valve 3, x: displacement of the air cylinder drive valve 3, x ': speed of the air cylinder drive valve 3, x ": air Acceleration of the cylinder drive valve 3, P: cylinder internal pressure of the air cylinder drive valve 3, and Ac: cylinder pressure receiving area of the air cylinder drive valve 3.

(State equation) dP / dt = (Rθa / Vc) G− (P / Vc) (dV / dt) + (WR / Vc) (dθc / dt) (2)
Where, R: the gas constant of air, θa: the cylinder inner wall temperature of the air cylinder drive valve 3 (same as the ambient temperature around the cylinder periphery), Vc: the cylinder volume of the air cylinder drive valve 3, G: the mass flow rate of air, W: gas mass of air, θc: air temperature in the cylinder of the air cylinder drive valve 3 Θa is measured by the microcomputer 7 based on a temperature detection signal from a temperature sensor (not shown). Further, θc is obtained by calculation from the cylinder volume and cylinder internal pressure and Boyle-Charles' law.
G = kg · Qn (3)
However, kg: coefficient, Qn: volume flow rate of air (standard state). The volume flow rate Qn is determined by the following discharge flow rate equation.
(Formula of discharge flow rate) When (Pa / P) <0.528, Qn = 11.1 SePc√ (θo / θc) (4)
However, Pa: atmospheric pressure, Se: effective cross-sectional area of small flow rate three-way solenoid valve 5B, θo: standard state air temperature (273 ° K).
When (Pa / P) ≧ 0.528, Qn = 22.2 Se√Pa (P−Pa) √ (θo / θc) (5)

(Thermal energy equation) dθc / dt = (Rθc / CvW) G + (hSh / CvW) (θa−θc) (6)
Where Cv: constant volume specific heat of air, h: heat transfer coefficient between cylinder inner wall and air, Sh: cylinder inner wall surface area.

  Failure diagnosis is finally judged by the pressure (cylinder internal pressure) -time characteristic obtained by the above equation of state (2) that applies each parameter calculated to match the measured value of cylinder internal pressure change (pressure characteristic). To do. Since only the state equation (2) does not consider the temperature change due to the cylinder internal pressure change, the temperature correction is performed using the thermal energy equation (6). Since the displacement x = 0 in the equation of motion from the time when the operation test switch is operated until the shut-off valve 1 actually starts to operate until the shut-off valve 1 is fully closed until the cylinder internal pressure reaches 0 MPa, the state equation (2 ) And the thermal energy equation (6) only apply.

  When the state equation (2) to which the calculated parameters are applied is represented in a graph, the initial pressure characteristic during normal operation is indicated by a curve A in FIG. This curve A is stored in advance in the memory of the microcomputer 7 as the pressure characteristic during the initial normal operation. In curve A, time t0 indicates the time when the operation test switch is turned on, and the air in the cylinder 31 of the air cylinder drive valve 3 begins to be exhausted, but the piston 34 still starts moving due to the influence of the starting resistance and the like. Therefore, the cylinder internal pressure gradually decreases depending only on the exhaust of the small flow rate three-way solenoid valve 5B. The time point t1 indicates a time point at which the piston 34 starts to move. The piston 34 starts moving from the left side to the right direction, the piston 34 pushes air in the cylinder 31, and the shut-off valve 1 operates in the closing direction. The pressure value at the time point t1 when the piston 34 starts to move is assumed to be Po. A time point t2 indicates a time point when the shut-off valve 1 is operated in a closing direction by a predetermined opening degree (for example, 15 degrees) set in advance from the fully opened state, and a pressure value at this time point is P1. Time t3 indicates a time when the shutoff valve 1 is fully closed, and at this time, the cylinder internal pressure becomes zero Pa (pascal).

  On the other hand, when the air cylinder drive valve 3 breaks down and the piston 34 does not operate, the piston 34 does not push the air in the cylinder 31, and the air is simply sent from the cylinder 31 through the small flow rate three-way solenoid valve 5B to the atmosphere. Since it is released, the pressure characteristic in the case of a failure is a curve B in FIG. The curve B has the same characteristics as the curve A from the time point t0 to the time point t1, and the pressure value from the time point t1 to the time point t3 is lower than the curve A. This curve B is obtained by calculation according to the above equations when the air cylinder drive valve 3 fails and does not move, and is similarly stored in advance in the memory of the microcomputer 7. Let P2 be the pressure value at time t2 of curve B.

  The pressure characteristics of the air cylinder drive valve 3 are from the initial curve A during normal operation, the deterioration of the packing of the pistons 34 and 33 of the air cylinder drive valve 3 over time, the time of the seat packing 1c of the shut-off valve 1 and the time of the gland packing 1d. Due to an increase in starting resistance due to mechanical deterioration, etc., the characteristic gradually changes and approaches the curve B at the time of failure as the time elapses. The boundary between the normal operation range and the dangerous operation range is represented between the curve A and the curve B. The pressure characteristic of the failure prediction boundary line C in FIG. 4 is set and similarly stored in advance in the memory of the microcomputer 7. Let Pth be the pressure value at time t2 on curve C. A range surrounded by the curve A and the failure prediction boundary line C is a normal operation range, and a range surrounded by the curve B and the failure prediction boundary line C is a dangerous operation range.

  As described above, the curve A, the curve B, and the failure prediction boundary line C are stored in advance in the memory of the microcomputer 7 when the shut-off valve 1 is installed.

  Next, after the installation of the shut-off valve 1, when the operation test is performed after the normal operation of the plant equipment starts (for example, several months after the installation), the shut-off valve 1 is opened from a fully opened state to a predetermined opening (for example, , 15 degrees), a partial operation confirmation test is performed, and the pressure value of the cylinder 31 of the air cylinder drive valve 3 at that time is measured based on the detection signal of the pressure sensor 6, and the pressure characteristics are measured by the microcomputer 7. Store in memory.

  Next, the microcomputer 7 compares the measured pressure characteristics with the initial normal operation, failure, and failure prediction curves A, B, and C stored in advance in the memory of the microcomputer 7 to determine whether or not there is a failure. I do. The determination result is divided into two stages, normal and abnormal.

  If the actually measured pressure characteristic is within the normal operating range between curve A and curve C, it is determined as normal. If it is determined to be normal, the shutoff valve control system continues to be used without maintenance, for example, until one year later.

  On the other hand, if the actually measured pressure characteristic is within the dangerous operation range between the curve C and the curve B, it is determined as abnormal. If it is determined that there is an abnormality, maintenance of the cylinder drive valve 3 or the shutoff valve 1 or parts or a new part must be replaced.

  The determination result can be externally output from the microcomputer 7 from the external output unit 9 as, for example, an electric signal of DC 4 to 20 mA. Moreover, the measured values of the curves A, B, and C and the pressure characteristics may be displayed on a display device (not shown) so that they can be visually recognized together with the normal / abnormal determination result. In this case, it is possible to predict a failure by visually checking which side of the normal operation range and the dangerous operation range represented by the curves A, B, and C are the actual measurement values of the pressure characteristics.

  The above failure diagnosis mainly predicts the failure of the cylinder drive valve 3 and the shutoff valve based on the transition between the time points t1 and t2 in the pressure characteristic of the cylinder drive valve 3 shown in FIG. Based on the transition between t0 and t1, it is also possible to predict failure of other parts.

  That is, from the time t0 when the operation test starts to the time t1 when the shutoff valve 1 starts to move, the temporal change in the cylinder internal pressure depends on the exhaust operation of the small flow three-way electromagnetic valve 5B, and the small flow three-way electromagnetic When a malfunction such as a malfunction or clogging occurs in the valve, the pressure characteristic from time t0 to time t1 does not become a normal characteristic, and as described above, from time t1 to time t2. In addition to determining the failure / normality of the air cylinder drive valve 3 by monitoring the pressure characteristics, the pressure characteristics from the time point t0 to the time point t1 are monitored, and the normality / failure of the operation of the small flow rate three-way solenoid valve 5B. Can also be determined.

  For example, as shown in FIG. 5, a curve B ′ is obtained when the small flow rate three-way solenoid valve 5B malfunctions or malfunctions, such as clogging, with respect to the initial normal pressure characteristic A from time t0 to time t1. As shown in FIG. Therefore, a failure prediction boundary line C ′ is set between the curve A and the curve B ′, and the pressure characteristics of the curve A, the curve B ′ and the curve C ′ are stored in advance in the memory of the microcomputer 7. When the measured characteristic of the cylinder internal pressure is within the range between the curve A and the curve C ′, it is determined as normal, and when it is within the range between the curve C ′ and the curve B ′, the flow rate three-way solenoid valve 5B. Can be determined as abnormal.

  If the cylinder 31 of the air cylinder drive valve 3 is large, an air operated valve can be provided between the solenoid valve 5 and the cylinder 31. Normal / failure can be determined as described above even when a failure such as clogging occurs.

  Next, the above-described failure diagnosis procedure will be described with reference to the flowchart of FIG. First, the product of the shutoff valve control system is shipped (step S1) and installed in the pipeline of the plant equipment (step S2). Next, during the trial operation of the plant equipment, a full stroke operation confirmation test is performed from the fully open state to the fully closed state of the shut-off valve 1 when the small flow rate three-way solenoid valve 5B is used, and the air cylinder drive valve at that time 3 is measured over time, and based on the above equations, the initial normal pressure characteristic (curve A in FIG. 4), the fault pressure characteristic (curve B), and the failure prediction boundary line C is stored in the memory of the microcomputer 7 (step S3).

  Next, after a predetermined period of time has elapsed since the product was installed (for example, several months later), a partial operation confirmation test for an operation test is performed, and the pressure characteristics of the cylinder 31 of the cylinder drive valve 3 at that time Is actually measured (step S4). Next, the pressure characteristics (curve A, curve B and failure prediction boundary line C in FIG. 4, curve B ′ and failure prediction boundary line C ′ in FIG. 5) stored in the memory of the microcomputer 7 and the actually measured pressure are measured. The characteristics are compared, and a two-step (normal and abnormal) determination is performed by the microcomputer 7 (step S5).

  Next, as a result of the determination in step S5, if the actually measured pressure characteristic is within the normal operating range between the curve A and the curve C and within the normal range of the curve A and the curve C ′, it is determined as normal (step S6). ). If it is determined to be normal, the shutoff valve control system continues to be used without maintenance, for example, until one year later.

  On the other hand, as a result of the determination in step S5, if the actually measured pressure characteristic is within the dangerous operation range between the curves C and B and / or the dangerous operation range between the curves C ′ and B ′, it is determined as abnormal. (Step S7). If it is determined that there is an abnormality, maintenance or parts such as the cylinder drive valve 3, the shutoff valve 1, the small flow rate three-way solenoid valve 5B, etc., need to be replaced. The normal / abnormal judgment result, the measured pressure characteristic value, and the curves A, B, B ′, C, C ′ can be displayed on a display (not shown) or the like. For example, it can be externally output with an electric signal of DC 4 to 20 mA.

  If it is determined that there is an abnormality in step S7, next, a measure such as maintenance or replacement of a failed part is performed (step S8), and then the shut-off valve control system test operation after maintenance or replacement of the failed part is performed. (Step S9). Next, the same operation as step S4 is performed, and based on this, the pressure characteristic (curve A) at the time of initial normal operation is re-stored (curve A stored in step S4 is updated) (step S10), then Return to step S5.

  As described above, the best mode of the present invention has been described, but the present invention is not limited to this, and various modifications and applications are possible.

  For example, in the above-described embodiment, the solenoid valve 5 includes the large flow rate three-way solenoid valve 5A and the small flow rate three-way solenoid valve 5B, but instead of this, as another example, the large flow rate four-way solenoid valve. It is good also as a structure which incorporated the valve and the small flow 4-way solenoid valve.

  FIG. 7 is a block diagram showing another embodiment in which the solenoid valve 5 has a construction in which a large flow rate four-way solenoid valve and a small flow rate four-way solenoid valve are incorporated. In FIG. 7, the switching solenoid valve 5 of the air cylinder drive valve 3 has two solenoid valves that are four-way valves in one body, and either the outlet port OUT1 or the outlet port OUT2 is set depending on the usage. It can be plugged and used as a three-way valve. The inlet port IN, the outlet port OUT1, the outlet port OUT2, the exhaust port E1, and the exhaust port E2 of each of the large flow rate four-way solenoid valve 5C and the small flow rate four-way solenoid valve 5D are connected to each other and provided on the body one by one. The common inlet port IN, outlet ports OUT1 and OUT2, and exhaust ports E1 and E2. Usually, a large flow rate three-way solenoid valve 5C is used. At this time, the small flow rate four-way solenoid valve 5D is controlled to be in a power failure state, and is in an all-port block state in which all five ports are closed. The large flow rate four-way solenoid valve 5C and the small flow rate four-way solenoid valve 5D are interlocked so that when one solenoid valve is energized, the other solenoid valve is in a power failure state. There is no state.

  In the case where the outlet port OUT1 is plugged and used as an example, when the solenoid A of the large flow rate four-way solenoid valve 5C is in a power failure state and the solenoid B is energized, the air flows from the IN port via the outlet port OUT2. This is supplied to the cylinder 31 of the cylinder drive valve 3, whereby the shut-off valve 1 is fully opened. The large flow rate four-way solenoid valve 5C is interlocked so that when one solenoid is energized, the other solenoid is not energized. When the solenoid A is powered down while the solenoid A is in a power failure state, the large flow rate four-way solenoid valve 5C is in an all-port block state, and the shutoff valve is kept fully open.

  Next, when the microcomputer 7 energizes the solenoid A based on the abnormality detection signal of the plant facility or the operation signal of the emergency cutoff switch (not shown), the air tends to flow from the IN port to the outlet port OUT1, but is plugged. Stop. On the other hand, the air in the air cylinder 31 is exhausted from the E2 port to the atmosphere via the outlet port OUT2 of the large flow rate four-way solenoid valve 5C, and the shutoff valve 1 is fully closed by the spring load. As a result, the pipeline is urgently shut off while the solenoid A is energized. The operation of the small flow rate four-way solenoid valve 5D used at the time of failure diagnosis is the same.

  In the above-described embodiment and other examples, when the shut-off valve 1 is fully opened or fully closed, which of the solenoids A and B of the corresponding large flow three-way solenoid valve 5A or large flow four-way solenoid valve 5C is selected. However, instead of this, after the shutoff valve 1 is fully opened or fully closed, both solenoids A and B may be controlled to be in a power failure state. In this case, since the large flow rate three-way solenoid valve 5A or the large flow rate four-way solenoid valve 5C is in the all-port block state, the power consumption can be reduced and the shut-off valve 1 can be kept fully open or fully closed. . If the all-port block state is used, the shut-off valve 1 can be stopped and held at an arbitrary valve opening. This operation is the same for the small flow rate three-way solenoid valve 5B or the small flow rate four-way solenoid valve 5D. Help hold in position.

  In the above-described embodiment, the curves A and B are obtained by the full stroke operation confirmation test. Instead, the curves A and B are obtained by the partial operation confirmation test from the time point t0 to the time point t2. May be.

  In the above-described embodiment, the failure / abnormality is determined by comparing the actually measured pressure characteristics with the pressure characteristics of the curves A, B, and C. Instead of this, the actually measured pressure at time t2 is determined. The pressure value P1 of the curve A, the pressure value P2 of the curve B, and the pressure value (threshold value) Pth of the curve C at the time t2, and if the actually measured pressure value is between P1 and Pth, it is normal , Pth and P2 may be determined as abnormal. Further, the actually measured pressure value at the time point t1 is compared with the pressure value P0 of the curve A, the pressure value P3 of the curve B ′, and the pressure value (threshold value) P4 of the curve C ′ at the time point t1, and the actually measured pressure value is compared. May be determined to be normal if it is between P0 and P4, and abnormal if it is between P4 and P3.

  As another example, when the effective cross-sectional area of the solenoid valve is large with respect to the cylinder volume, the pressure decrease during the operation test is quick, and the pressure characteristic is close to the curve B even during normal operation. In this case, since the operation start point (time point t1) of the shut-off valve 1 in the pressure characteristic is not clearly captured, the microcomputer 7 may detect the operation start point of the shut-off valve 1 based on the detection signal of the potentiometer 8.

  In the above-described embodiment, the failure diagnosis is performed by monitoring the pressure characteristic of the cylinder internal pressure of the air cylinder drive valve 3. However, as another embodiment, the displacement indicating the transition of the detection signal of the potentiometer 8 is used. It can be configured to perform fault diagnosis by monitoring only the characteristics.

  In this case, for example, as shown in FIG. 8, a full stroke operation confirmation test is performed at the time of trial operation of the plant equipment, and the temporal change in the detected voltage of the potentiometer 8 at that time is measured, so that The displacement characteristic D is stored in advance in the memory of the microcomputer 7. In the displacement characteristic D, the detection voltage is zero from the start time t0 of the operation check test to the operation start time t1 in the closing direction of the shut-off valve 1, and the detection voltage gradually increases from the time t1 to the time t3 where the fully closed state is reached. Thus, the maximum voltage (Vmax) is changed, and the change in the detected voltage represents the displacement of the shut-off valve 1 from the fully open position to the fully closed position (therefore, the displacement of the piston 33). Further, the failure prediction boundary line E is set between the curve D and the detection voltage zero, and stored in advance in the memory of the microcomputer 7.

  At the time of the operation test, the shut-off valve 1 is operated in a closing direction from a fully opened state by a predetermined opening degree (for example, 15 degrees) (time t2), and the measured displacement characteristics of the potentiometer 8 are the curves D and E If it is within the range, it can be determined as normal, and if it is within the range between the curve E and the voltage zero, it can be determined as abnormal.

  In the other embodiments described above, the failure / abnormality is determined by comparing the measured displacement characteristics with the displacement characteristics of the curves D and E. Instead of this, the actual measurement at the time point t2 is detected. The voltage is compared with the voltage value V1 of the curve D at the time point t2, the voltage value (threshold value) Vth of the curve E, and the zero voltage. If the measured voltage value is between V1 and Vth, normal, Vth and zero If it is between the voltages, it may be determined that there is an abnormality.

Embodiment of the shut-off valve control system of this invention is shown, (A) is a front view, (B) is a fragmentary sectional view. It is a block diagram which shows the structure of the air cylinder drive valve and electromagnetic valve in embodiment of the cutoff valve control system of this invention. It is a block diagram which shows the electric constitution in embodiment of the cutoff valve control system of this invention. It is a graph which shows the pressure characteristic of the air cylinder drive valve in embodiment of the cutoff valve control system of this invention. It is a graph which shows the pressure characteristic of the cylinder drive valve in embodiment of the cutoff valve control system of this invention. It is a flowchart explaining the procedure of the failure diagnosis in embodiment of the cutoff valve control system of this invention. It is a block diagram which shows the structure of the cylinder drive valve and electromagnetic valve in the other Example of the cutoff valve control system of this invention. It is a graph which shows the displacement characteristic of the potentiometer in other embodiment of the cutoff valve control system of this invention.

Explanation of symbols

1 Shut-off valve 3 Air cylinder drive valve (part of control means)
5 Solenoid valve (part of control means)
5A Large flow rate 3-way solenoid valve 5B Small flow rate 3-way solenoid valve 6 Pressure sensor 7 Microcomputer (determination means, storage means)
8 Potentiometer

Claims (6)

A shut-off valve, an air cylinder drive valve that controls rotation of the valve shaft of the shut-off valve, and a solenoid valve that supplies and exhausts air from an air supply source to the cylinder of the air cylinder drive valve. A shutoff valve control system comprising a control means for controlling the degree,
A pressure sensor for detecting the internal pressure of the cylinder;
Determining means for determining normality / abnormality of the system based on pressure characteristics of the cylinder internal pressure measured by the pressure sensor when the control means is controlled to operate the shut-off valve from fully open to a predetermined opening closing direction; The shut-off valve control system further comprising: The shut-off valve control system according to claim 1, wherein
Storage means for storing in advance the pressure characteristics at the initial normal operation of the system, the pressure characteristics at the time of failure, and the pressure characteristics at the failure prediction boundary;
The determination unit determines that the measured pressure characteristic is normal when the pressure characteristic is within a range between the pressure characteristic during normal operation and the pressure characteristic at the failure prediction boundary, and determines the pressure characteristic at the failure prediction boundary and the failure The shut-off valve control system is characterized in that it is determined to be abnormal when it is within a range between the pressure characteristics of the hour. The shut-off valve control system according to claim 1 or 2,
The solenoid valve is a solenoid valve in which a large-flow three-way solenoid valve used during normal operation and a small-flow three-way solenoid valve used during operation test are built in one body. . A shut-off valve, an air cylinder drive valve that controls rotation of the valve shaft of the shut-off valve, and a solenoid valve that supplies and exhausts air from an air supply source to the cylinder of the air cylinder drive valve. A shutoff valve control system comprising a control means for controlling the degree,
Detecting the internal pressure of the cylinder,
The pressure characteristics of the cylinder internal pressure measured when the shut-off valve is controlled to operate in the closing direction from the full opening to the predetermined opening are stored in advance. Compared with the pressure characteristics of the characteristics and failure prediction boundary,
When the actually measured pressure characteristic is within the range between the pressure characteristic at normal operation and the pressure characteristic at the failure prediction boundary, it is determined as normal, and between the pressure characteristic at the failure prediction boundary and the pressure characteristic at the failure A failure prediction method for a shut-off valve control system, characterized in that an abnormality is determined when the value is within the range. A shut-off valve, an air cylinder drive valve that controls rotation of the valve shaft of the shut-off valve, and a solenoid valve that supplies and exhausts air from an air supply source to the cylinder of the air cylinder drive valve. A shutoff valve control system comprising a control means for controlling the degree,
A potentiometer for detecting the displacement of the valve shaft of the shutoff valve;
Judgment to determine normality / abnormality of the system based on the displacement characteristic of the valve shaft of the shut-off valve measured by the potentiometer when the shut-off valve is controlled by the control means to operate in the closing direction from the fully open position to the predetermined opening degree. And a shut-off valve control system. In the shut-off valve control system according to claim 5,
Storage means for preliminarily storing displacement characteristics at the time of initial normal operation of the system, displacement characteristics at the time of failure, and displacement characteristics of the failure prediction boundary;
The determination means determines that the measured displacement characteristics are normal when the measured displacement characteristics are within a range between the displacement characteristics during the normal operation and the displacement characteristics of the failure prediction boundary, and the displacement characteristics of the failure prediction boundary and the failure The shut-off valve control system is characterized in that it is determined to be abnormal when it is within a range between the displacement characteristics of the hour.

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