JP2006119968A - Duplex automatic switching control device for fluid distribution line - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a duplex automatic switching control device for fluid distribution line capable of automatically switching a regulating valve while minimizing the fluctuation of a control target value, and reducing the cost while avoiding enlargement of its actuator part without extending the range of the regulating valve. <P>SOLUTION: In normal time, the aperture of a main regulating valve 12A is automatically adjusted, in a state where driven cutoff valves 13B and 14B are fully closed and main cutoff valves 13A and 14A are fully opened, so that a flow rate 11 detected by a flowmeter 15 becomes a flow set value 16, while in the event of abnormality of the main regulating valve 12A, the aperture of the main regulating valve at that time 12A is held, the openings of the driven cutoff valves 13B and 14B are changed from full close to full open while gradually throttling the main cutoff valve 13A from full open to full close, and the aperture of a driven regulating valve 12B is automatically adjusted so that the flow rate detected by the flowmeter 15 becomes the flow set value 16. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a dual automatic switching control device for a fluid distribution line.

  In general, in a plant having a boiler, a steam turbine, and the like, it is extremely important to control the flow rate as a control target value of a fluid such as water supply or fuel.

For this reason, conventionally, as shown in FIG. 4, the fluid supply system for supplying fluid to the plant has a dual configuration of system A and system B, and control valves 1A, 1B, motor operated valves 2A, 2B and Manual valves 3A and 3B are provided,
Process data is input, the opening degree of the control valves 1A and 1B is determined based on the process data to control the flow rate, and the opening signal (electric signal) is sent to the air signal by the electro / pneumatic converters 5A and 5B. A common controller 6 is provided for the A system and the B system that are converted into the control valves 1A and 1B and
A valve opening / closing command is input from the controller 6, and during normal operation, a valve operation signal for fully opening the A-system electric valve 2A and the B-system electric valve 2B is output. When the A-system control valve 1A is abnormal, A There is a valve operation device 7 that outputs an operation signal for fully closing the motor-operated valve 2A. (For example, refer to Patent Document 1.)
JP-A-5-341849

  However, in the conventional switching control device as disclosed in Patent Document 1, as shown in FIG. 5, the opening degree of the control valves 1A and 1B is normally set with the A-system and B-system electric valves 2A and 2B fully open. The control distribution ratio is controlled as 50:50 [%], and when the A system control valve 1A is abnormal, the A system electric valve 2A is fully closed, and the B system control valve 1B is matched to the fully closed time. Since the distribution ratio of the opening control of the valve is gradually increased to finally become 0: 100 [%], the control valves 1A and 1B each adjust the flow rate half of the minimum flow rate required for the plant. I have to do it.

  For example, if the minimum flow rate required for the plant is 10 [ton / hr] and the maximum flow rate is 100 [ton / hr], the control valves 1A and 1B are completely switched and used. If so, the control valves 1A and 1B may be those in the range of 10 [ton / hr] to 100 [ton / hr], but the control valves 1A and 1B disclosed in Patent Document 1 may be used. In 1B, since the distribution ratio of the opening degree control is controlled as 50:50 at the normal time, a range of 5 [ton / hr] to 100 [ton / hr] must be used.

  This means that the range of the control valves 1A and 1B is greatly widened, and the actuator portion is enlarged, leading to an increase in cost. In particular, when the actuator portion is an electric motor, the electric capacity is increased and the running is increased. It had the disadvantage of having a significant impact on cost.

  In view of such circumstances, the present invention can automatically switch the control valve while minimizing the fluctuation of the control target value, and avoids increasing the size of the actuator without expanding the range of the control valve. Thus, it is an object of the present invention to provide a dual automatic switching control device for a fluid distribution line that can reduce costs.

The present invention is a main system control valve provided in the middle of the main system line through which fluid flows,
A main system shut-off valve provided on at least one of the upstream side and the downstream side of the main system control valve of the main system line;
A subordinate control valve provided in the middle of the subordinate line that is arranged in parallel to bypass the main control valve and the main cutoff valve of the main line;
A slave cutoff valve provided on at least one of the upstream side and the downstream side of the slave control valve of the slave line;
A detector for detecting a fluid control target value;
Under normal conditions, with the slave shut-off valve fully closed and the main shut-off valve fully open, the opening of the main control valve is automatically adjusted so that the control target value detected by the detector becomes the set value. When an abnormality occurs in the main control valve, the opening of the main control valve is maintained at the current opening, and the opening of the main shut-off valve is gradually reduced from fully open to fully closed. And a control means for automatically adjusting the opening of the slave control valve so that the opening of the secondary shutoff valve is changed from fully closed to fully open and the control target value detected by the detector becomes a set value. The invention relates to a dual automatic switching control device for a fluid distribution line, characterized in that it is provided.

  According to the above means, the following operation can be obtained.

  Under normal conditions, the control means opens the main control valve so that the control target value detected by the detector becomes the set value with the slave shut-off valve fully closed and the main shut-off valve fully opened. When the abnormality is generated in the main system control valve, the opening degree of the main system control valve is maintained at the current opening degree by the control means. Is gradually throttled from fully open to fully closed, and at the same time, the opening of the secondary shut-off valve is changed from fully closed to fully open, and the slave control is adjusted so that the control target value detected by the detector becomes the set value. The valve opening is automatically adjusted.

  As a result, it is possible to automatically switch the control valve while minimizing fluctuations in the control target value, and the main control valve and the subordinate control valve can each be controlled when the control target value is a flow rate. It is only necessary to use a plant that can adjust the minimum flow rate required for the plant, it is not necessary to expand the range of the main control valve and the subordinate control valve, the actuator part is not enlarged, and the cost can be reduced. When the actuator portion is an electric motor, the electric capacity is not increased, and the running cost is suppressed.

  In the dual automatic switching control device of the fluid distribution line, the absolute value of the opening deviation between the opening command output to the main control valve and the actual opening of the main control valve exceeds the allowable value. It is possible to provide an abnormality detecting means for determining that an abnormality has occurred in the main system control valve when the state continues for a predetermined time. In this way, the abnormality of the main system control valve can be reliably detected. Is possible.

  In the fluid flow line duplex automatic switching control device, a main system shut-off valve is provided on both the upstream side and the downstream side of the main system control valve of the main system line, and the upstream side when an abnormality occurs in the main control valve. It is desirable that the downstream main system shut-off valve be fully closed when the main system shut-off valve is gradually throttled and fully closed. After the switching to the secondary control valve is completed, the main control valve can be repaired immediately.

  According to the duplex automatic switching control device of the fluid distribution line of the present invention, the control valve can be automatically switched while minimizing the fluctuation of the control target value, and the actuator portion can be obtained without widening the range of the control valve. It is possible to achieve an excellent effect that the cost can be reduced by avoiding the increase in size.

  Embodiments of the present invention will be described below with reference to the accompanying drawings.

1 to 3 are examples of embodiments for carrying out the present invention.
A main control valve 12A for adjusting the flow rate 11 as a fluid control target value is provided in the middle of the main system line 10A through which a fluid such as water supply or fuel flows, and from the main system control valve 12A of the main system line 10A. On the upstream side and downstream side, a main system cutoff valve 13A and a main system cutoff valve 14A are provided,
A slave control valve 12B for adjusting the flow rate 11 of the fluid is provided in the middle of the slave line 10B arranged in parallel to bypass the master control valve 12A and the master shut-off valves 13A, 14A of the master line 10A. Provided, a slave cutoff valve 13B and a slave cutoff valve 14B are provided upstream and downstream of the slave control valve 12B of the slave line 10B,
The flow rate of the fluid that has passed through the main system control valve 12A and the main system shut-off valves 13A, 14A of the main system line 10A, or the fluid that has passed through the sub system control valve 12B and the sub system shut-off valves 13B, 14B of the slave system line 10B. 11 is provided as a detector for detecting 11;
In a normal state, the main system control valve is set so that the flow rate 11 detected by the flow meter 15 becomes the flow rate set value 16 in a state where the sub system cutoff valves 13B and 14B are fully closed and the main system cutoff valves 13A and 14A are fully opened. While the opening degree of 12A is automatically adjusted, when an abnormality occurs in main system control valve 12A, the opening degree of main system control valve 12A is maintained at the opening degree at that time, and main system shutoff valve 13A The opening of the secondary shutoff valves 13B, 14B is changed from fully closed to fully open at the same time as the opening is gradually reduced from fully open to fully closed, and the flow rate 11 detected by the flow meter 15 is the flow set value 16 Thus, a control device 17 is provided as control means for automatically adjusting the opening of the secondary control valve 12B.

The control device 17
A subtractor 19 for obtaining and outputting a flow deviation 18 between the flow rate set value 16 based on a command such as a load command in the plant and the flow rate 11 detected by the flow meter 15;
A proportional-integral controller 21 that performs proportional-integral processing on the flow rate deviation 18 output from the subtractor 19 and outputs an opening degree command 20 of the main control valve 12A or the subordinate control valve 12B for eliminating the flow-rate deviation 18; ,
When the main system control valve 12A is normal, it is switched to the a side, and the opening degree command 20 output from the proportional-plus-integral regulator 21 is output as the opening degree command 22A to the main system control valve 12A. When an abnormality occurs in the system control valve 12A, the switch 23A is switched to the b side and holds the opening of the main system control valve 12A at the opening at that time;
When the main control valve 12A is normal, the main control valve 12A is switched to the b side, and the opening of the sub control valve 12B is kept fully closed. On the other hand, when an abnormality occurs in the main control valve 12A, a A switching device 23B that outputs the opening command 20 output from the proportional integral controller 21 to the slave control valve 12B as the opening command 22B;
A subtractor 26 that calculates and outputs an opening deviation 25 between the opening command 22A of the main control valve 12A output from the switch 23A and the actual opening 24A of the main control valve 12A;
A signal monitor switch 28 that outputs a signal 27 of “1” when the absolute value of the opening deviation 25 output from the subtractor 26 is larger than an allowable value;
When the signal 27 output from the signal monitor switch 28 is input and the state of the signal 27 is continued for a preset time T [sec], the main control valve 12A on the upstream side of the main control valve 12A. An on-delay timer 31 that outputs an inching close command 29 to the system shut-off valve 13A and outputs a full-open command 30 to the slave shut-off valves 13B and 14B;
When the actual opening 32A of the main system shutoff valve 13A upstream from the main system control valve 12A is fully closed (ie, 0 [%] or less), the main system shutoff downstream from the main system control valve 12A. And a signal monitor switch 34 that outputs a full-close command 33A to the valve 14A.

  The subtractor 26, the signal monitor switch 28 and the on-delay timer 31 in the control device 17 constitute an abnormality detection means 35, and an opening degree command 22A output to the main system control valve 12A, and the main system control valve 12A. When the absolute value of the opening deviation 25 with respect to the actual opening 24A exceeds the allowable value continues for a predetermined time T [sec], it is determined that an abnormality has occurred in the main control valve 12A. It is.

  Next, the operation of the illustrated example will be described.

  In a normal state where the main system control valve 12A is normal, the control device 17 serving as a control means fully closes the sub system shutoff valves 13B and 14B, and fully opens the main system shutoff valves 13A and 14A. In the subtractor 19 of the control device 17, a flow rate deviation 18 between the flow rate set value 16 based on a command such as a load command in the plant and the flow rate 11 detected by the flow meter 15 is obtained and output to the proportional-integral controller 21. In the proportional integration controller 21, the flow rate deviation 18 output from the subtractor 19 is proportionally integrated, and the opening degree command 20 of the main control valve 12A for eliminating the flow rate deviation 18 is switched to the a side. The opening degree of the main control valve 12A is output to the main system control valve 12A via the switching device 23A and the flow rate 11 as the control target value detected by the flow meter 15 becomes the flow rate set value 16. It is automatically adjusted.

  When the main control valve 12A is normal, the switch 23B is switched to the b side, and the opening of the sub control valve 12B is kept fully closed.

  On the other hand, in the subtractor 26 constituting the abnormality detection means 35, an opening deviation 25 between the opening command 22A of the main control valve 12A output from the switch 23A and the actual opening 24A of the main control valve 12A. Is output to the signal monitor switch 28, and when the absolute value of the opening deviation 25 output from the subtractor 26 exceeds the allowable value, the signal 27 of "1" is turned on from the signal monitor switch 28. When the signal 27 is output to the delay timer 31 and the state of the signal 27 continues for a preset time T [sec], it is determined that an abnormality has occurred in the main control valve 12A, and the switch 23A Is switched to the b side, and the opening degree of the main system control valve 12A is maintained at the opening degree at that time, and is input from the on-delay timer 31 to the main system cutoff valve 13A upstream of the main system control valve 12A. And a fully open command 30 are output to the slave shut-off valves 13B and 14B, and the opening of the main shut-off valve 13A is gradually throttled from fully open to fully closed, The slave shut-off valves 13B and 14B are opened from fully closed to fully open, and the switch 23B is switched to the a side so that the flow rate 11 detected by the flow meter 15 becomes the flow rate set value 16. The opening degree of the system control valve 12B is automatically adjusted.

  Subsequently, when the actual opening degree 32A of the main system shutoff valve 13A upstream from the main system control valve 12A is fully closed (that is, 0 [%] or less), the signal control switch 34 controls the main system control valve. A fully closed command 33A is output to the main system shutoff valve 14A downstream of 12A, and the main system shutoff valve 14A is fully closed.

  The upstream main system shutoff valve 13A, the main system control valve 12A, and the downstream main system shutoff valve 14A from when the abnormality occurs in the main system control valve 12A until the switching to the subordinate control valve 12B is completed. The changes in the respective opening degrees of the upstream-side slave cutoff valve 13B, the slave-side control valve 12B, and the downstream-side slave cutoff valve 14B are shown, for example, in FIG. The flow rate changes and the total flow rates on the main line 10A side and the subordinate line 10B side from when the abnormality occurs in the valve 12A until the switching to the subordinate control valve 12B is completed are, for example, FIG. As shown.

  As a result, it is possible to automatically switch from the main control valve 12A to the subordinate control valve 12B while minimizing the fluctuation of the flow rate 11 as the control target value, and to connect the main control valve 12A to the subordinate control valve 12A. The system control valve 12B only needs to use a valve that can adjust the minimum flow rate required for each plant. It is not necessary to expand the range of the main system control valve 12A and the subordinate control valve 12B, and the actuator portion does not increase in size. In addition, the cost can be reduced. Furthermore, when the actuator portion is an electric motor, the electric capacity is not increased and the running cost can be suppressed.

  In addition, in the illustrated example, a state where the absolute value of the deviation between the opening command 22A output to the main control valve 12A and the actual opening 24A of the main control valve 12A exceeds the allowable value is predetermined. Since the abnormality detection means 35 that determines that an abnormality has occurred in the main control valve 12A when the time continues is constituted by the subtractor 26, the signal monitor switch 28, and the on-delay timer 31 in the control device 17, It is possible to reliably detect abnormality of the main system control valve 12A.

  In the illustrated example, the main system shutoff valves 13A and 14A are provided on both the upstream side and the downstream side of the main system control valve 12A of the main system line 10A, and the upstream main control valve 12A is in an upstream state when an abnormality occurs. Since the downstream main system shut-off valve 14A is fully closed when the opening of the system shut-off valve 13A is gradually reduced and fully closed, the secondary system control is performed from the main system control valve 12A side. After the switching to the valve 12B side is completed, the main control valve 12A can be repaired immediately. The downstream main shut-off valve 14A and the downstream slave shut-off valve 14B can be omitted if necessary.

  In this way, it is possible to automatically switch from the main control valve 12A to the subordinate control valve 12B while minimizing the fluctuation of the flow rate 11 as the control target value, and the main control valve 12A and the subordinate control valve 12B. Without expanding the range, it is possible to reduce the cost by avoiding an increase in the size of the actuator portion.

  In addition, the dual automatic switching control device of the fluid distribution line of the present invention is not limited to the above-described example of illustration, and the control target value is not limited to the flow rate 11 of the fluid, but the pressure, temperature, concentration, etc. It is also possible to select the main system on the downstream side of the main control valve 12A when the actual opening 32A of the main shut-off valve 13A on the upstream side of the main control valve 12A is fully closed. When a limit switch that is turned on when the main system shutoff valve 13A is fully closed is provided instead of providing the signal monitor switch 34 that outputs the full close command 33A to the shutoff valve 14A, and the limit switch is turned on. Of course, it is possible to output a full close command from the control device 17 to the downstream main system shutoff valve 14A, and other various modifications can be made without departing from the scope of the present invention. .

It is a system configuration | structure figure which shows an example of the form which implements this invention. It is a timing chart which shows the switching timing of each valve in an example which embodies the present invention. It is a diagram which shows the flow volume behavior by each valve in an example of embodiment which implements this invention. It is a system configuration | structure figure which shows a prior art example. It is a timing chart which shows the correlation of the opening degree and flow volume of each valve in a prior art example.

Explanation of symbols

10A Main line 10B Subordinate line 11 Flow rate (control target value)
12A Main system control valve 12B Subsystem control valve 13A Main system shutoff valve 13B Subsystem shutoff valve 14A Main system shutoff valve 14B Subsystem shutoff valve 15 Flow meter (detector)
16 Flow rate setting value (setting value)
17 Control device (control means)
22A Opening command 22B Opening command 24A Actual opening 25 Opening deviation 29 Inching close command 30 Full open command 32A Opening 33A Full close command 35 Abnormality detection means

Claims (3)

A main control valve provided in the middle of the main line through which fluid flows;
A main system shut-off valve provided on at least one of the upstream side and the downstream side of the main system control valve of the main system line;
A subordinate control valve provided in the middle of the subordinate line that is arranged in parallel to bypass the main control valve and the main cutoff valve of the main line;
A slave cutoff valve provided on at least one of the upstream side and the downstream side of the slave control valve of the slave line;
A detector for detecting a fluid control target value;
Under normal conditions, with the slave shut-off valve fully closed and the main shut-off valve fully open, the opening of the main control valve is automatically adjusted so that the control target value detected by the detector becomes the set value. When an abnormality occurs in the main control valve, the opening of the main control valve is maintained at the current opening, and the opening of the main shut-off valve is gradually reduced from fully open to fully closed. And a control means for automatically adjusting the opening of the slave control valve so that the opening of the secondary shutoff valve is changed from fully closed to fully open and the control target value detected by the detector becomes a set value. A dual automatic switching control device for a fluid distribution line, comprising:   When the absolute value of the opening deviation between the opening command output to the main control valve and the actual opening of the main control valve exceeds the allowable value for a predetermined time, the main control valve The fluid flow line duplex automatic switching control device according to claim 1, further comprising an abnormality detecting means for determining that an abnormality has occurred in the fluid distribution line.   A main system shut-off valve is provided on both the upstream and downstream sides of the main system control valve in the main system line, and when the main control valve malfunctions, the upstream main system shut-off valve is gradually throttled and fully closed. The dual automatic switching control device for a fluid circulation line according to claim 1 or 2, wherein the downstream main system shut-off valve is fully closed at that time.

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