JP5122381B2 - Valve controller for petrochemical plant - Google Patents

Description

  The present invention relates to a valve control device for controlling a valve incorporated in a petrochemical plant such as an FCC device or an RFCC device for petroleum refining, and relates to a petrochemical system having a plurality of control units that can be immediately replaced when an abnormality occurs. The present invention relates to a valve control device for a plant.

  In a petrochemical plant, there is a risk of an explosion or the like due to an error in the control of the controlled fluid, and once the operation is stopped due to an abnormality in the equipment, it takes time to check the equipment to resume the operation. High reliability is required for the valves and valve control devices used.

  Conventionally, a valve control device of a petrochemical plant has a valve opening value input from an opening sensor that detects the opening of a valve arranged in each stroke constituting the plant, and a valve control input from a main controller. A control unit that calculates a control value of an actuator that drives the valve based on the command value, and that can feedback-control the opening degree of the valve based on the calculated control value. When an abnormality occurs, it is configured to be switchable so that the valve is controlled by another control unit.

  For example, Patent Document 1 has a pair of controllers that receive an input signal and output an output signal for controlling the opening degree of the valve. In the middle of each signal line connecting the input / output port, a switch for selecting and switching the controller connected to each input / output terminal is provided, and a switching signal transmitting means for outputting a switching instruction signal to each switch is provided. There has been proposed a valve control device having a duplex controller, characterized in that a start switch for starting the switching signal transmitting means is provided.

In addition, Patent Document 2 relates to a switching method of a dual air conditioning unit in which the air conditioning unit is duplicated on the control side and the standby side as a control method of the main water supply control valve of the PWR plant. When switching from the standby side to the standby side, there is disclosed a switching method for the dual air conditioning unit characterized in that the control signal is first tracked and then switched.
JP 2000-88130 A Japanese Patent Laid-Open No. 10-61815

  However, in the former case, since the control is started based on the input signal switched to the standby controller by the changeover switch, the control state is temporarily changed due to the response delay occurring at that time, and the stability is impaired. There was a problem of fear.

  In the latter case, when switching to the air conditioning unit on the standby side, the control signal is primarily tracked before switching, so that the air conditioning unit on the standby side is in a state where some abnormality has occurred in the air conditioning unit on the control side. When switching to a part, it is tracked in an abnormal state and there is a possibility that appropriate control becomes difficult.

  Furthermore, in the valve control device of a petrochemical plant, it is proposed not only to double the control unit, but also to include a sensor that detects the control state input to each control unit. Since the sensors are duplicated as a pair, there is a problem that when one of the sensors is abnormal, the control unit is switched, and the probability of continuing operation of the plant cannot be increased so much.

  The present invention has been made in view of the above-described conventional problems, and maintains an appropriate plant operating state without causing a response delay even when switching a redundantly designed control unit. An object of the present invention is to provide a valve control device for a petrochemical plant capable of

In order to achieve the above-mentioned object, the first characteristic configuration of the valve control device of the petrochemical plant according to the present invention is an opening degree for detecting the opening degree of the valve as described in claim 1 of the claims. Based on the valve opening value input from the sensor and the control command value of the valve input from the main controller, the control value of the actuator that drives the valve is calculated, and the control value of the valve is calculated based on the calculated control value. A petrochemical plant comprising a plurality of control units capable of feedback-controlling the opening degree, and capable of being switched to control the valve by another control unit when an abnormality occurs in the control unit controlling the valve. a valve control device, is initialized to the initial control right is set to one of a plurality of control unit, also the control unit which does not have control over not only the control unit having the control right, front The control value is calculated based on the valve opening value input from the opening sensor and the control command value input from the main controller, and a control signal is output to the actuator based on the calculated control value. A control unit having a control right outputs its own control signal to the actuator, and a control unit without the control right is configured to block its control signal , and each control unit has its own control unit The control unit having an abnormality detection unit that detects an abnormality and transmits the abnormal state to another control unit, and the control unit having the control right detects its own abnormality by the abnormality detection unit, the control unit having no control right It is configured to determine whether or not to hand over the control right based on the presence or absence of abnormality .

Not only the control unit having the control right but also the backup control unit not having the control right drives the valve based on the valve opening value input from the opening sensor and the control command value input from the main controller. Since the control value of the actuator is calculated and a control signal is output to the actuator based on the calculated control value, even when the control right is switched, the control can be continued immediately and appropriately without any response delay. become. In this case, since the backup control unit is configured to block its own control signal, the control signal output from the control unit having the control right and the control signal output from the backup control unit Is avoided. Each control unit is equipped with an abnormality detection unit that detects an abnormality of its own control unit. When an abnormality occurs in a control unit having the control right, the control right is not handed over to another control unit, Since it is determined whether or not the control right is to be handed over based on the abnormal normal state including the section, the reliability is further improved.

In the second feature configuration, as described in claim 2, in addition to the first feature configuration described above , an abnormality is detected in the control unit having the control right, and an abnormality occurs in the control unit having no control right. In this case, the control unit having the control right performs a fail-safe operation of outputting a control signal to the actuator so that the valve is closed without handing over the control right.

According to the above-described configuration, when both the control units become abnormal, the control unit having the control right executes the fail-safe operation in which the valve is closed, so that the valve can be prevented from being damaged.

In the third feature configuration, as described in claim 3 , in addition to the first or second feature configuration described above, valve opening values from a plurality of opening sensors provided in the valve are set to each control unit. Each control unit selects a valve opening value from any one opening sensor based on a predetermined priority setting condition set in each opening sensor, and calculates the control value The point is that it is configured to do.

  According to the above configuration, a plurality of opening sensors that detect the opening of the valve are provided, and the opening values of the valves detected by the respective opening sensors are redundantly input to each control unit. Even if the opening degree sensor breaks down, it becomes possible to appropriately control based on the opening degree value detected by another opening degree sensor, so that the reliability is further improved. In this case, each control unit selects a valve opening value from any one of the opening sensors based on a predetermined priority setting condition among a plurality of opening values input from each opening sensor. To calculate the control value.

The fourth characterizing feature of the can, as noted in the claim 4, in addition the first above the third one characteristic feature of the includes an abnormality detecting unit that detects its own abnormality in the control unit, When the control unit having the control right detects its own abnormality by the abnormality detection unit, the control unit is configured to shut off its own control signal and to output a control right delivery signal for transferring the control right to another control unit. In the point.

  According to the above configuration, when the abnormality detection unit provided in the control unit having the control right detects that an abnormality has occurred in the control unit, the control signal output to the actuator is interrupted, Since the control right delivery signal is output to the other control unit, an appropriate control signal is immediately output to the actuator by the other control unit.

In addition to any one of the first to fourth feature configurations described above, the fifth feature configuration includes a hardware watchdog circuit in the abnormality detection unit, as described in claim 5 , Regardless of the output state of the control signal, the control signal is shut off by the abnormal signal output from the watchdog circuit, and the abnormal signal is output to the other control unit as the control right delivery signal.

  According to the above configuration, when an abnormality of the control unit is detected by the hardware watchdog circuit provided in the abnormality detection unit, the abnormality is output by the abnormality signal output from the watchdog circuit regardless of the control state of the control unit. The control signal is interrupted, and the abnormal signal is output as a control right delivery signal to another control unit, so that another control unit immediately outputs an appropriate control signal to the actuator.

The sixth characterizing feature of the can, as noted in the claim 6, in addition the first above Fifth any feature configuration of, includes a watchdog timer by software in the abnormality detection unit, the watchdog When the timer overflows, regardless of the output state of its own control signal, it outputs an abnormal signal to shut off its own control signal and outputs the abnormal signal to the other control unit as the control right delivery signal. is there.

  According to the above configuration, when the watchdog timer by the software provided in the abnormality detection unit overflows for some reason, the control signal is cut off by the abnormality signal output from the control unit, and the abnormality signal is transferred to the control right delivery signal. Therefore, an appropriate control signal is immediately output to the actuator by the other control unit.

The seventh characterizing feature of the can, as noted in the claim 7, in addition the first aforementioned Sixth any feature configuration of the opening sensor to the abnormality detection unit, the actuator, the control command A signal discriminating unit for detecting any abnormality of the value, and detecting any abnormality by the signal discriminating unit, outputs an abnormal signal regardless of the output state of the own control signal and In addition to blocking, the abnormality signal is output to another control unit as the control right delivery signal.

  According to the above-described configuration, when any one of the opening sensor, the actuator, and the control command value is detected by the signal determination unit provided in the abnormality detection unit, the abnormality signal is output and the control signal is shut off. At the same time, the abnormal signal is output as a control right delivery signal to another control unit, so that an appropriate control signal is immediately output to the actuator by the other control unit.

The eighth characterizing feature of the can, as noted in the claim 8, in addition from the first described above seventh any feature configuration of receiving an abnormality signal from the control unit with the control right, the control right A control right acquisition circuit that outputs a delivery signal to another control unit is provided.

  According to the configuration described above, the control right acquisition circuit that has received the abnormal signal from the control unit having the control right outputs the control right transfer signal to the other control unit, so that the other control unit immediately controls the actuator appropriately. A signal is output.

The ninth characterizing feature of the can, as noted in the claim 9, in addition from the first described above eighth one characteristic feature of the control unit with the control right is inputted from the opening sensor If there is an excessive difference between the control units with respect to the valve opening value and the control value based on each valve opening value, an alarm is output without switching the control right.

  According to the above-described configuration, if there is an excessive difference between the valve opening value and the control value based on each valve opening value between the control units, an abnormality has occurred in one of the redundantly designed systems. By judging that there is a possibility, outputting an alarm while continuing control, and notifying that there is a need for maintenance, it is possible to prevent an inconvenient situation from occurring.

The tenth feature configuration includes a shared memory connected to each control unit by a communication bus in addition to any of the first to ninth feature configurations described above, as described in claim 10 . The control information is configured to be shared.

  According to the above configuration, control information for each control unit can be efficiently set via the shared memory.

  As described above, according to the present invention, valve control of a petrochemical plant that can maintain an appropriate operation state of a plant without causing a response delay even when switching a redundantly designed control unit. The device can now be provided.

  Below, the valve control apparatus built in the FCC apparatus and RFCC apparatus for petroleum refining which are examples of a petrochemical plant is demonstrated. As shown in FIG. 1, a valve control device 1 is incorporated in a hydraulic unit U arranged in the vicinity of a valve V incorporated in a plant, and is a target opening degree with respect to the valve V inputted from a plant main control device CT. Based on the signal and the opening signal of the valve detected by the opening sensor S, the hydraulic mechanism VD is controlled to adjust the opening of the valve V, and the position signal indicating the opening state of the valve V to the main controller CT Is a control device that outputs.

  As shown in FIG. 2, the hydraulic unit U includes a hydraulic mechanism VD including a hydraulic pump, an accumulator, a servo valve for hydraulic control as an actuator, an explosion-proof casing C in which the control device 1 is accommodated, a casing An air unit AU for press-fitting explosion-proof air into C is provided.

  A transparent glass is disposed on the door of the casing C, and the screen of the liquid crystal display panel provided in the internal control device 1 is configured to be recognized from the outside. A plurality of explosion-proof switches SW1, SW2, SW3 are attached to the door.

  The switch SW1 is a rotary multi-contact switch or a push button switch, and the display screen of the liquid crystal display panel can be switched by rotating or pressing the switch SW1 while maintaining the explosion-proof state of the casing C. It is possible.

  Further, the switch SW2 is a push button type switch that serves as a control mode switching operation unit according to the present invention. By operating the switch SW2, the control device 1 can operate in the local control mode and the remote control while maintaining the explosion-proof state of the casing C. Switch to mode.

  Further, the switch SW3 is a dial switch with a built-in variable resistor, which is a manual operation unit according to the present invention. By rotating the switch SW3 in the local control mode, the casing C is kept in an explosion-proof state, and the valve V The opening can be manually controlled.

  The control device 1 is based on the valve opening value input from the opening sensor S that detects the opening of the valve V and the control command value of the valve V input from the main control device CT, that is, the target opening signal. A control value for a servo valve that drives the valve V is calculated, and a plurality of control units are provided for feedback control of the opening degree of the valve V based on the calculated control value.

  As shown in FIG. 3, the valve V to be controlled is a slide valve V that adjusts the flow path P to a predetermined opening according to the operation state of the plant, and is driven by pressure oil supplied via a servo valve. The valve body V1 is slid and driven through a valve rod V2 connected to the piston of the hydraulic cylinder SL. A pair of magnetostrictive opening sensors S (S1, S2) are incorporated between the piston and the valve stem V2 via a coupling, and the output of the opening sensor S is input to the control device 1. The valve V to be controlled is not limited to the slide valve V, and the same applies to other valves such as a plug valve and a butterfly valve.

  The magnetostrictive opening sensor S is a position of the magnet, that is, the position of the valve V, by measuring the propagation time of torsional strain generated by the magnet that moves in a non-contact manner on the sensor rod as the piston moves forward and backward. It is a sensor that measures the opening.

  As shown in FIG. 4, the control device 1 includes two control unit substrates 2 and 3, a display unit substrate 4, a terminal substrate 5, and the like, and each is connected by a single or a plurality of connectors. Two control units 20 and 30 according to the present invention are constituted by the two control unit substrates 2 and 3, respectively, and a display unit 40 is constituted by the display unit substrate 4.

  Various signals are inputted to and outputted from the main control device CT and the valve drive mechanism that is a control target in the control unit substrates 2 and 3 and the display unit substrate 4 via the terminal substrate 5.

  Specifically, the control command value of the valve V is input from the main control device CT to the control units 20 and 30 via the terminal board 5, and the position signal of the valve V is transmitted from the control units 20 and 30 to the main control device CT. Is output. Further, the valve opening values from the pair of opening sensors S are input via the terminal board 5, and control signals are output from the control units 20 and 30 to the servo valves.

  As shown in FIG. 6, each of the pair of control units 20 and 30 and the display unit 40 includes a CPU, a ROM that stores a control program executed by the CPU, and a RAM that is used as a working area. A microcomputer and peripheral circuits are mounted, and the control program is executed by the CPU, thereby realizing an intended valve control function and the like.

  Each of the control units 20, 30 and the display unit 40 is provided with a shared memory CM that functions as a communication bus and is connected via a local network such as CU net (registered trademark of Step Technica Co., Ltd.). 30, control information, control parameters, display data, and the like are shared through the shared memory CM.

  A color liquid crystal display unit 45 is incorporated in the display unit substrate 4, and the control state of the valve as shown in FIG. The monitor screen is displayed.

  The display unit board 4 is mounted with a battery-backed SRAM 44, and is configured so that control information obtained by the control units 20 and 30 obtained via the shared memory CM is stored in a ring buffer format. A removable SD memory 46 for backup storage is mounted.

  In addition, the display unit substrate 4 communicates with a personal computer located at a remote place via a LAN, and transmits a control state displayed on the color liquid crystal display unit 45 to the personal computer. 42, an infrared interface 43 capable of communicating with an external personal computer via an explosion-proof casing C is provided.

  The infrared interface 43 communicates with the control unit 1 without opening the door of the explosion-proof casing C, sets various initial setting control parameters, and reads control information including abnormality information, display data, and the like. It is provided to connect to a personal computer PC for maintenance.

  Control parameters input from the maintenance personal computer PC are written to the shared memory CM via the microcomputer 41 of the display unit 40, and are similar to the shared memory CM mounted on another control unit board via the local network. Is written to.

  In the control parameter, a control right parameter that sets which of the two control units 20 and 30 has an initial control right, and a sensor selection that sets which of the doubled opening sensors S is initially selected Parameter, signal level with respect to the control command value of the valve V input from the main controller CT to the control units 20 and 30 (for example, current specifications that define the opening degree 0% to opening degree 100% from 4 mA to 20 mA, Voltage specification specified from 0V to 10V), signal level of the opening signal input from the opening sensor S, signal level and upper / lower limit values of thrust pressure of the hydraulic cylinder, output signal level to the servo valve, main controller CT The predetermined control parameters required for operating the system, such as the signal level of the position signal output to the control unit, the abnormality determination reference value of the opening sensor C detected by the control units 20 and 30, and the like. Data are included.

  As shown in FIG. 6, a control command value from the main control unit CT is input to the microcomputers 21 and 31 via the input signal processing units 26 and 36 in each of the control units 20 and 30, and the opening signal The output signals of the pair of opening sensors S1 and S2 are input to the microcomputers 21 and 31 via the processing units 22 and 32, respectively.

  The input signal processing units 26 and 36 and the opening degree signal processing units 22 and 32 include an isolation amplifier that electrically separates signals and an A / D converter that converts an analog output signal of the isolation amplifier into a digital signal. ing.

  In addition, the control values for the servo valves SV output from the microcomputers 21 and 31 are output to the control valves 20 and 30 to the servo valves SV via the servo output sections 23 and 33, respectively. The output position of the valve V to the main controller CT that has been output is configured to be output via the position signal output units 24 and 34.

  The servo output units 23 and 33 include a D / A converter that converts digital control value information into an analog signal, and a driver circuit that amplifies the output. The position signal output units 24 and 34 include an isolation circuit that electrically separates digital opening position information, and a D / A converter that converts the output of the isolation circuit into an analog signal.

  The control unit (in this case, the control unit 20) for which the control right is set based on the control parameter described above is selected by the sensor selection parameter among the valve opening values input from the opening sensors S1 and S2. Based on the valve opening value of the opening sensor and the control command value input from the main controller CT, the digital PID calculation is performed to calculate the control value for the valve V, and the electromagnetic type is calculated based on the calculated control value. A control signal is output to the servo valve SV.

  Similarly, the standby control unit (in this case, the control unit 30) that does not have the control right also includes a sensor selection parameter of any one of the valve opening values input from the opening sensors S1 and S2. On the basis of the valve opening value of the opening sensor selected in step 1 and the control command value input from the main controller CT, a digital PID calculation is performed to calculate a control value for the valve V. Based on the calculated control value A control signal is output to the servo valve SV.

  Then, each control part 20 and 30 selects the valve opening value from any one opening sensor based on the predetermined priority setting conditions set to each opening sensor S1, S2, Calculate the control value.

  Predetermined priority setting conditions include, in addition to the sensor selection parameters described above, whether or not a feedback loss occurs in which the valve opening value does not converge to a predetermined range corresponding to a control signal based on the control command value for a predetermined time. The occurrence of a reverse DEV value in which the state in which the deviation between the control command value and the valve opening value changes in the increasing direction continues for a predetermined time period. The feedback loss is an abnormality due to deterioration of the opening sensor, and the reverse DEV value is an abnormality due to incorrect wiring. These are detected by a signal determination unit 260 (see FIG. 7) described later.

  When each of the control units 20 and 30 determines that a feedback loss or a reverse DEV value has occurred in the opening sensor S selected by the sensor selection parameter, it switches to the other opening sensor S and opens the currently selected opening sensor S. The degree sensor information, the abnormality information of the opening sensor in which an abnormality has occurred, and the like are stored in its own shared memory CM.

  Information stored in each shared memory CM is written to the shared memory of the display unit 40 via the local network, and the display unit 40 monitors the color liquid crystal display unit 45 based on the contents of its own shared memory CM. The information is displayed and stored in the SRAM 44 and the SD memory 46.

  Further, for each opening sensor S, when the deviation of the DEV value, which is the deviation between the control command value and the valve opening value, exceeds the abnormality determination threshold, the opening sensor S is provided in the control device 1 without switching. Activate the alarm to sound.

  Various abnormality determination thresholds (signal level threshold, duration, etc.) for the opening sensor S and the like are set in advance by the personal computer PC for maintenance and stored in each shared memory CM.

  As shown in FIG. 7, the control unit 20 includes a relay circuit 250 a that switches whether the control signal output to the servo valve itself is connected to the servo valve SV, and the position signal output to the main control unit CT. A switch circuit 250 (250a, 250b) comprising a relay circuit 250b for switching whether or not to connect the signal line to the signal line to the main control unit CT is provided. The switch circuit 250 (250a, 250b) is turned off when it is turned on and does not have the control right. The control unit 30 is similarly configured.

  Therefore, the drive current for the servo valve SV is output only from the control unit (20 or 30) having the control right, and the position signal of the valve V is output to the main control unit CT, so that no signal interference occurs. It is configured as follows.

  When an abnormality occurs in the control unit (20 or 30) having the control right, a control right transfer signal is output to the standby control unit (30 or 20), and the standby control unit (30 or 20) When the delivery signal is detected, the switch circuit 250 is turned on to continue the control of the valve.

  Hereinafter, the transfer of the control right will be described in detail by taking the control unit 20 as an example, but the same applies to the control unit 30. The control unit 20 includes a plurality of abnormality detection units that detect its own abnormality. If the abnormality detection unit detects an abnormality of itself when it has the control right, the switch circuit 250 is turned off so as to cut off its control signal, and the control right is transferred to the other control unit 30 It is configured to output a signal. Further, at that time, the alarm unit provided in the control device 1 is activated to sound.

  As shown in FIG. 7, a hardware watchdog circuit 220 and software watchdog timer 210 are provided as an abnormality detection unit.

  The watchdog circuit 220 is reset by a watchdog pulse (hereinafter referred to as “WD pulse”) input at a predetermined cycle from the microcomputer 21 and outputs an abnormal signal when the counter circuit exceeds a predetermined value. If a malfunction such as runaway occurs in the CPU of the microcomputer 21 for some reason and the state where no WD pulse is input continues for a predetermined time, the counter circuit becomes larger than the predetermined value and an abnormal signal is output. The

  The watchdog timer 210 includes firmware having a counter that is automatically counted by an internal timer of the microcomputer 21 and a program that resets the value of the counter by software, and resetting by a program is performed for a predetermined time due to a runaway of the CPU or the like. If not, an abnormal signal (a signal described as “overflow” in the figure) is output by the firmware.

  When an abnormal signal is input from either the watchdog circuit 220 or the watchdog timer 210, a watchdog error circuit 230 having a latch circuit that retains the state is provided. A control right delivery signal (in the figure, a signal described as “control CPU abnormality / normal”, which is a high level when normal and a low level when abnormality) is output.

  In FIG. 7, a signal described as “other control CPU abnormality / normal” is input to the microcomputer 21, and this signal is a signal from a watchdog error circuit provided in the other control unit 30.

  The switch circuit 250 described above is controlled by an output switching circuit 240 having an AND gate. That is, the switch circuit 250 is turned on when the high-level control switching signal output from the microcomputer 21 having the control right and the high-level control right delivery signal output from the watchdog error circuit 230 are input. When the control signal and the position signal are output and at least one of the control switching signal and the control right delivery signal is at a low level, the switch circuit 250 is turned off. Accordingly, the switch circuit 250 is turned off by the low-level control switching signal output from the waiting microcomputer 21 having no control right.

  Therefore, regardless of the output state of the own control signal, the abnormal signal output from either the watchdog circuit 220 or the watchdog timer 210 blocks the own control signal and the position signal, and the abnormal signal is controlled. It is output to another control unit 30 as a delivery signal.

  Further, as the abnormality detection unit, a signal determination unit 260 that is a functional block for detecting any abnormality of the opening sensor S, the servo valve SV, and the control command value based on a control program executed by the CPU is provided. .

  The signal discriminating unit 260 includes an opening value of the valve V input from the opening sensor S, a control command value input from the main controller CT, a current value for the servo valve SV output based on the result of the PID calculation, For each of the position signals of the valve V output to the main controller CT, it is determined that there is an abnormality when a state exceeding any of the upper and lower limit abnormality determination thresholds stored in the shared memory CM continues for a predetermined time. The result is stored in the shared memory CM. The current value is configured such that the output value from the servo output unit 23 is monitored by the current detection unit shown in FIG.

  When any of the above-described abnormalities is detected by the signal discriminating unit 260, the CPU abnormal signal output at a high level from the microcomputer 21 at the normal time is switched to the low level, and the low-level CPU abnormal signal is changed to the watchdog error circuit 230. The control right delivery signal latched at the low level by the watchdog error circuit 230 is output to the waiting control unit 30. Note that when the CPU abnormality signal is switched to the low level, the operation of the watchdog circuit 220 is stopped.

  That is, when any abnormality is detected by the signal discriminating unit 260, the abnormality signal is output to block the own control signal and the position signal regardless of the output state of the own control signal and the position signal. Is output to another control unit as a control right delivery signal.

  In addition, an excessive difference between the control units 20 and 30 in the valve opening value and the control value based on each valve opening value based on the control information such as the valve opening value and the control value stored in the shared memory CM. When it is determined that there is a possibility that an error has occurred in one of the redundantly designed systems, control is continued, that is, an alarm is issued from the alarm unit without handing over the control right. Output to notify that there is a need for maintenance.

  When the above-described watchdog circuit 220, watchdog timer 210, watchdog error circuit 230 and their input / output signal ports assigned to the microcomputer 21 receive abnormal signals from the control units 20 and 30 having the control right. Control right acquisition circuits 25 and 35 for outputting a control right transfer signal to the other control units 30 and 20 are configured.

  When a low-level control right delivery signal (“other control CPU abnormality / normal” signal in FIG. 7) is input from the control right acquisition circuit 35 of the control unit 30 having the control right to the standby control unit 20, The control right is handed over to the control unit 20. The control unit 20 switches the control switching signal for the output switching circuit 240 from the low level to the high level, turns on the switch circuit 250, and continues the control on the valve V.

  As described above, not only the control unit having the control right but also the backup control unit not having the control right includes the valve opening value input from the opening sensor and the control command value input from the main controller. The control value of the actuator that drives the valve is calculated based on the control value, and the control signal is output to the actuator based on the calculated control value. Will be able to continue.

  Even when the abnormality is detected by the signal determination unit 260 of the control unit 20 having the control right and it is necessary to hand over the control right to the standby control unit 30, the signal determination unit 260 of the standby control unit 30 is required. If it is recognized based on the control information stored in the shared memory CM that the same abnormality is detected by the control signal, the servo current is determined so that the valve V is closed without determining the control right and handing over the control right. Perform a fail-safe operation that sets the value to zero.

  In addition, even when an abnormality is detected by the signal determination unit 260 of the control unit 20 having the control right and it is necessary to transfer the control right to the standby control unit 30, it is input from the standby control unit 30. If the control right delivery signal is at a low level, that is, it can be determined that some abnormality has occurred, it is determined that the control is impossible, and the servo current value is set so that the valve V is closed without handing over the control right. Perform a fail-safe operation that sets to zero.

  Further, the signal determination unit 260 not only detects the abnormality for the above-mentioned control right delivery, but also the pressure of the pump constituting the hydraulic mechanism VD, the pressure of the accumulator, the ESD hydraulic pressure, the hydraulic fluid level, the thrust push of the hydraulic cylinder SL. Whether or not an abnormality has occurred in the pressure or the pulling pressure (detected by the pressure sensor) is determined based on the abnormality determination threshold or the determination time included in the control parameter stored in advance in the shared memory CM. The alarm unit is configured to operate when it is determined.

  The abnormality of thrust pressing pressure or pulling pressure will be described. In the case where the valve 1 to be controlled is a plug valve that is arranged at the bottom of the reaction tower and adjusts the flow rate by adjusting the area of the bottom opening, the plug valve Is closed, and then the opening degree is controlled.

  The plug valve has a tapered truncated cone shape and is disposed so as to be fitted into a cylindrical guide erected on the periphery of an opening formed in the bottom horizontal surface of the reaction tower. In this state, if the reaction tower thermally expands and a force acts on the plug valve side, the tip side bites into the cylindrical guide and may buckle and deform, so the gap between the cylindrical guide and the plug valve when fully closed. It is necessary to maintain a state in which no excessive force is applied without causing the above-described phenomenon.

  As shown in FIG. 6, the detected values of the pressure sensors that detect the thrust pressing force and the pulling pressure of the hydraulic cylinder that drives the plug valve V are input to the control units 20 and 30. Each of the control units 20 and 30 calculates the push side pressure and the pull side pressure by multiplying the input pressure value and the pressure receiving area, and seems to exceed the upper and lower limit values of the thrust pressure set in advance as control parameters. In such a case, the thrust control is executed to suppress it. And when the control part which has a control right is performing thrust control, it is comprised so that the relay contact for outputting an alarm from an alarm part may be output.

  Each of the control units 20 and 30 normally performs feedback control of the opening, that is, the position of the plug valve based on a control command value input from the main control device CT. When the pressure is about to exceed the upper and lower limit values, in addition to the position feedback control, the servo valve SV is controlled so that the push side pressure and the pull side pressure do not exceed the upper and lower limit values. The occurrence of this is avoided.

  For example, if the upper limit value of the thrust pressure is set to 3 tons, the control units 20 and 30 perform position control so that the thrust pressure is less than 3 tons when determining that the thrust pressure of 3 tons or more has acted on the plug valve. It is moderate.

  Various information such as which control unit has acquired the control right, which opening sensor is selected for control, valve control state, various abnormal states described above, etc. It is displayed on the color liquid crystal display unit 45 provided in the display unit 40 via the shared memory CM, or displayed on the screen of the personal computer PC connected via the communication interface 42.

  Each of the control units 20 and 30 reads a control command value, an opening value from the opening sensor S, a PID control calculation process, and controls a servo valve at a preset control cycle (for example, 10 msec. Cycle). A series of processing such as output processing of signals and position signals, abnormality detection processing, and the like are repeatedly executed, and the result is stored in its own shared memory CM.

  By the local network connecting the shared memories CM, mutual data is read and written in substantially the same cycle as the above-described control cycle, and the data is shared with each other.

  The display unit 40 performs display processing based on the control information stored in the shared memory CM, and further displays preset control information in the SRAM 44 together with time information in a cycle longer than the above-described control cycle (for example, 1 second cycle). In addition to writing, the data is written to the SD memory 46. The SRAM 44 stores control information for about 4 hours in a ring buffer system, and the SD memory 46 stores control information for several years.

  As described above, the functions of the control units 20 and 30 that execute the control sequence for the valve V and the display unit 40 that displays the result are distributed via the shared memory CM. Display processing can be smoothly performed without causing a delay in control due to a load for display processing.

  In the above-described embodiment, the case where the control unit that controls the valve V is redundantly controlled by the two control units has been described. However, the control unit may be configured to be redundantly controlled by three or more control units. In this case, a priority order can be set for each control unit, and a control right can be transferred from a control unit with a higher priority to a lower control unit.

  In the embodiment described above, an example in which two opening degree sensors S for detecting the opening degree of the valve V are provided has been described. However, three or more opening degree sensors S are provided, and each output is input to each control unit. You may comprise.

  The various embodiments described above are examples of the present invention, and specific circuit configurations and the like of each part can be appropriately changed and designed within the scope of the effects of the present invention.

Block diagram of a system incorporating a control device according to the present invention Illustration of hydraulic unit Illustration of valve, hydraulic cylinder, opening sensor Explanatory drawing of the board which constitutes the control device built in the hydraulic unit Illustration of the screen displayed on the color liquid crystal display unit by the display unit Functional block configuration diagram of two control units and display unit constituting the control device Configuration diagram of the main part of the control unit

1: Control devices 20, 30: Control unit 40: Display unit CT: Main control devices S, S1, S1: Opening angle sensor SV: Actuator (servo valve)
V: Valve VD: Hydraulic mechanism

Claims (10)

Based on the valve opening value input from the opening sensor that detects the opening of the valve and the control command value of the valve input from the main controller, the control value of the actuator that drives the valve is calculated and calculated A plurality of control units capable of feedback control of the opening degree of the valve based on the control value, and when the abnormality occurs in the control unit controlling the valve, the other control unit controls the valve Switchable petrochemical plant valve control device,
The initial control right is set to any one of the plurality of control parts, and not only the control part having the control right but also the control part not having the control right is opened by the valve opening sensor. The control value is calculated based on the degree value and the control command value input from the main control device, and a control signal is output to the actuator based on the calculated control value. And a control unit having no control right is configured to cut off its own control signal ,
Each control unit includes an abnormality detection unit that detects an abnormality in its own control unit and transmits the abnormal state to the other control unit, and a control unit having control right detects its own abnormality by the abnormality detection unit. A valve control device for a petrochemical plant configured to determine whether or not to hand over the control right based on whether there is an abnormality in the control unit that does not have the control right . When an abnormality is detected in the control unit having the control right and an abnormality has occurred in the control unit not having the control right, the control unit having the control right can close the valve without handing over the control right. The valve control device for a petrochemical plant according to claim 1, wherein a fail safe operation for outputting a control signal to the actuator is executed . A valve opening value from a plurality of opening sensors provided in the valve is input to each control unit, and each control unit is any one based on a predetermined priority setting condition set in each opening sensor. The valve control device for a petrochemical plant according to claim 1 or 2 , wherein the valve opening value from two opening sensors is selected to calculate the control value. When the control unit having the control right detects its own abnormality by the abnormality detection unit, the control unit is configured to shut off its own control signal and to output a control right delivery signal for transferring the control right to another control unit. The valve control device for a petrochemical plant according to any one of claims 1 to 3 . The abnormality detection unit is provided with a watchdog circuit by hardware, regardless of the output state of the control signal of itself, the control signal is interrupted by the abnormality signal output from the watchdog circuit, and the abnormality signal is The valve control device for a petrochemical plant according to any one of claims 1 to 4, wherein the valve control device outputs the control right delivery signal to another control unit. The abnormality detection unit is provided with a software watchdog timer, and when the watchdog timer overflows, regardless of the output state of its own control signal, the abnormality signal is output and the control signal is shut off, and the abnormality signal The valve control device for a petrochemical plant according to any one of claims 1 to 5 , wherein the control right delivery signal is output to another control unit. The abnormality detection unit includes a signal determination unit that detects any abnormality of the opening sensor, the actuator, or the control command value, and outputs an own control signal when any abnormality is detected by the signal determination unit. The petrochemical according to any one of claims 1 to 6, wherein, regardless of the state, an abnormal signal is output to block its own control signal, and the abnormal signal is output to the other control unit as the control right delivery signal. Plant valve control device. The valve of the petrochemical plant according to any one of claims 1 to 7 , further comprising a control right acquisition circuit that receives an abnormality signal from a control unit having a control right and outputs the control right delivery signal to another control unit. Control device. The control unit having the control right switches the control right if there is an excessive difference between the control units with respect to the valve opening value input from each opening degree sensor and the control value based on each valve opening value. The valve control device for a petrochemical plant according to any one of claims 1 to 8, which outputs an alarm without any warning. Each controller in the connected shared memory each comprise a communication bus, the valve control equipment of the petrochemical plant according to claim 1 which is configured to share control information 9.

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