Anti-disturbance system of pneumatic piston type double-acting straight stroke regulating valve

Abstract

The utility model discloses an anti-disturbance system of a pneumatic piston type double-acting straight stroke regulating valve, which relates to the technical field of automatic regulation and control of automation instruments and is characterized in that a coking coal pressure transmitter is mounted on a main pipeline of a high-pressure coke oven gas, and a KVVP shielding cable is adopted to connect a coking coal pressure detection signal to an input end of a signal power distribution isolator; after being magnetically coupled, isolated and output by a signal distribution isolator, the signal as a PV value enters a PLC analog quantity input template to realize input signal isolation, logical operation is performed in a processor after analog-to-digital conversion, a negative feedback automatic regulation PID control loop is formed after logical comparison is performed on the PV value and a coking coal pressure SP set value, a deviation control value forms a CV control signal after digital-to-analog conversion, and the CV control signal is transmitted to the PLC analog quantity input template after digital-to-analog conversion. And the PLC analog quantity output template sends the signals to an output signal isolator to realize control signal output isolation.

Description

Technical Field

[0001] The utility model relates to the technical field of automatic regulation and control of automatic instruments, and particularly relates to an anti-disturbance system for a pneumatic piston type double-acting direct stroke regulating valve. Background Art

[0002] The power pressurized cutting coking coal high-low pressure connected regulating valve adopts a pneumatic piston type double-acting regulating valve and a direct stroke regulating structure mode, and is the main control component for the high-pressure coke oven gas pressure regulating and conveying task in the production process. However, due to external interference of control signals at the production site and the lack of a self-locking function of the regulating valve itself, the regulating valve fails to control under the influence of external factors, seriously restricting the smooth progress of production. Content of the Utility Model

[0003] Aiming at the above technical problems, the utility model provides an anti-disturbance system for a pneumatic piston type double-acting direct stroke regulating valve, which is used to solve the problem that the regulating valve lacks a self-locking function and fails to control under the influence of external factors.

[0004] In order to achieve the above purpose, the technical solution of the utility model is specifically as follows:

[0005] An anti-disturbance system for a pneumatic piston type double-acting direct stroke regulating valve includes a regulating valve, which is composed of a left cylinder chamber, a right cylinder chamber, a regulating valve connecting component, a gear rotation output shaft, a ball valve body, a right gear-driven piston and a left gear-driven piston. It also includes a coking coal pressure transmitter, which is connected with a signal distribution isolator, the signal distribution isolator is connected with a PLC analog input template, the PLC analog input template is connected with a PLC analog output template, the PLC analog output template is connected with an output signal isolator, the output signal isolator is connected with an electronic switch, the electronic switch is connected with an intelligent valve positioner, the intelligent valve positioner is connected with an air lock valve, and the air lock valve is connected with the regulating valve. The electronic switch is also connected with a two-position three-way solenoid valve, one end of the two-position three-way solenoid valve is connected with a filter pressure reducing valve, the filter pressure reducing valve is connected with an instrument air source, the other end of the two-position three-way solenoid valve is connected with the air lock valve, and the intelligent valve positioner is connected with the filter pressure reducing valve.

[0006] Compared with the prior art, the beneficial effect of the utility model is:

[0007] 1. Implement the "power-off" and "signal-off" protection for the regulating valve. The electronic switch mainly makes the two-way three-way solenoid valve change direction according to the current value of the input signal, and then realizes self-locking and position-holding through the air-lock valve. When the input signal current is greater than the lower limit current (3.6 mA) set by the electronic switch, the electronic switch conducts, and the two-way three-way solenoid valve is energized, that is, in the normal automatic working state; when the signal current is instantaneously interrupted (lower than 3.6 mA), the electronic switch blocks, the two-way three-way solenoid valve loses power, makes the two-way three-way valve change direction to cut off the air source leading to the air-lock valve, and then realizes self-locking and position-holding through the air-lock valve, that is, the locking state. The power-off protection is that when the power is off, the two-way three-way solenoid valve switches to empty the control air source of the air-lock valve, the air-lock valve closes, cuts off the air paths leading to both ends of the cylinder, maintains the original position of the load, and realizes power-off self-locking and position-holding. The signal-off protection is realized by the electronic switch. The electronic switch can make the two-way three-way solenoid valve change direction according to the value of the input signal, and then realizes self-locking and position-holding through the air-lock valve. When the input signal current is greater than the lower limit current set by the electronic switch (3.6 mA), the electronic switch conducts, and the two-way three-way solenoid valve is energized, that is, in the normal automatic working state. When the signal current is instantaneously interrupted, the electronic switch blocks, and the solenoid valve loses power, that is, in the locking state.

[0008] 2. Implement the "air-source-off" protection for the regulating valve. An air-lock valve is installed in the instrument control air-source air path to realize the protection function when the air-source pressure is low or the air source disappears. The air-source-off protection is mainly realized by the air-lock valve. Adjust the operating pressure of the air-lock valve to the set value of 0.30 - 0.32 MPa. When the air pressure is higher than the set value, the self-locking valve opens, and the air paths leading to both ends of the cylinder of the intelligent valve positioner are connected, that is, in the normal automatic working state. When the air pressure is lower than the set value, the air-lock valve locks, cuts off the air paths leading to both ends of the cylinder of the intelligent valve positioner, maintains the original position of the load, and realizes air-source-off self-locking and position-holding. The instrument air source mainly uses 0.5 MPa low-pressure nitrogen as the control air for the regulating valve. The nitrogen signal air pressure enters the upper diaphragm chamber of the air-lock valve. If the force generated by it is greater than the force generated by the compression of the set spring of the air-lock valve, the upper diaphragm is pushed upward, the exhaust port closes, the signal nitrogen air pressure enters the lower diaphragm chamber and acts on the lower diaphragm of the air-lock valve, pressing down the piston of the air-lock valve, and the air-lock valve opens. At this time, the two air paths IN1 and OUT1 on both sides of the regulating valve cylinder are connected, and IN2 and OUT2 are connected. If the signal nitrogen air pressure becomes lower than the set pressure for some reason, the upper diaphragm of the air-lock valve is pushed downward, the pressure inside the lower diaphragm of the air-lock valve is discharged from the exhaust port, and the air-lock valve is closed by the force of the spring. At this time, the two air paths IN1 and OUT1 on both sides of the regulating valve cylinder are connected, and IN2 and OUT2 are cut off, thus realizing the position-holding function.

[0009] 3. Implement anti-disturbance measures for the control signal of the regulating valve and the detection signal of the cutting coke coal pressure. Prevent reverse interference from occurring in the instrument control signal grounding system. Separate the instrument control signal grounding from the electrical grounding. The instrument signal grounding wire is directly led to the grounding busbar in the grounding pit. In accordance with the requirements specified in the "HG / T 20513, 2000 Instrument System Grounding Design Regulations", check that the grounding resistance of the instrument control system should not be greater than 4 Ω, and the grounding connection resistance of the instrument system should not be greater than 1 Ω. According to the requirements for the input of the power-added cutting coke coal pressure detection signal and the high and low pressure connected regulating valve control signal into the computer lower-level machine template for collection with 1-5VDC or 4-20mADC standard signals for the input and output of instrument signals, perform input signal isolation power distribution and output signal passive isolation on them. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 It is a schematic structural diagram of the present utility model.

[0011] In the figure:

[0012] 1. Coke coal pressure transmitter; 2. Signal power distribution isolator; 3. PLC analog input template; 4. PLC analog output template; 5. Output signal isolator; 6. Electronic switch; 7. Intelligent valve positioner; 8. Air lock valve; 9. Two-position three-way solenoid valve; 10. Filter pressure reducing valve; 11. Left cylinder chamber; 12. Right cylinder chamber; 13. Regulating valve connecting component; 14. Gear rotation output shaft; 15. Ball valve body; 16. Right gear-driven piston; 17. Left gear-driven piston; 18. Instrument air source. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0013] To make the objectives, technical solutions, and advantages of the present utility model clearer and more understandable, the present utility model will be further described in detail below in conjunction with the specific embodiments and with reference to the accompanying drawings. It should be understood that these descriptions are merely exemplary and are not intended to limit the scope of the present utility model. In addition, in the following description, the descriptions of well-known structures and technologies are omitted to avoid unnecessarily confusing the concepts of the present utility model.

[0014] Install a coke coal pressure transmitter 1 on the main pipeline of the high-pressure coke oven gas. Connect the coke coal pressure detection signal to the input end of the signal power distribution isolator 2 using a KVVP shielded cable. After the magnetic coupling isolation output of the signal power distribution isolator, it enters the PLC analog input template 3 as the PV value to achieve input signal isolation. After analog-to-digital conversion, logical operations are performed in the processor. After the PV value is logically compared with the coke coal pressure SP set value, a negative feedback automatic regulation PID control loop is formed. The deviation control value forms a CV control signal after digital-to-analog conversion and is sent to the output signal isolator 5 by the PLC analog output template 4 to achieve output isolation of the control signal.

[0015] The output signal isolator 5 outputs a 4 - 20 mA control signal into the logic circuit of the electronic switch 6. When the logic circuit determines that the input signal current is greater than the lower limit current of 3.6 mA set by the electronic switch, the 4 - 20 mA control signal is normally output through the electronic switch 6 to the intelligent valve positioner 7 of the regulating valve, enabling the intelligent valve positioner 7 to perform corresponding electrical / pneumatic conversion according to the magnitude of the control signal. The two converted nitrogen gas sources pass through the air lock valve 8 and enter the left cylinder chamber 11 and the right cylinder chamber 12 of the regulating valve respectively, and push the right gear-driven piston 16 and the left gear-driven piston 17 to the balanced position required by the intelligent valve positioner 7 according to the magnitudes of the two air sources output by the valve positioner. The driven piston drives the gear rotation output shaft 14 to act, and the gear rotation output shaft 14 is transmitted through the regulating valve connecting component 13 to control the valve core switch of the ball valve body 15, so that the high-pressure coking coal reaches the required pressure control value.

[0016] The output signal isolator 5 outputs a 4 - 20 mA control signal into the logic circuit of the electronic switch 6. When the logic circuit determines that the input signal current is less than the lower limit current of 3.6 mA set by the electronic switch, it is determined that the control signal is in the "broken signal" state; when the 220 VAC or 24 VDC power supply of the electronic switch disappears, it is determined that the control signal is in the "power-off" state; when these two states occur, the solenoid valve output of the electronic switch 6 remains de-energized, and the two-way three-way solenoid valve 9 reverses and closes, cutting off the control air path of the air lock valve 8.

[0017] The instrument air source 18 uses 0.6 MPa low-pressure nitrogen gas or dry compressed air as the air source, which is reduced to 0.4 MPa qualified regulating valve air source through the filter pressure reducing valve 10. One air source passes through the two-way three-way solenoid valve 9 and is connected to the air lock valve 8 as the control air path. When the two-way three-way solenoid valve 9 reverses and closes, it cuts off the control air path of the air lock valve 8, causing the air lock valve to act, cutting off the two output air paths of the intelligent valve positioner 7, connecting the two sides of the cylinder chamber of the regulating valve, and stabilizing the regulating valve in the current state, realizing the "broken air source" protection of the regulating valve. The other air source enters the intelligent valve positioner 7 as the input working air source of the intelligent valve positioner 7. The intelligent valve positioner 7 outputs two regulated air sources. Under the normal state of the air lock valve 8, they pass through the air lock valve 8 and enter the left cylinder chamber 11 and the right cylinder chamber 12 to realize the function of regulating the pressure of the coking coal medium by the regulating valve.

[0018] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A pneumatic piston type double-acting linear stroke control valve anti-disturbance system, comprising a control valve, wherein the control valve is composed of a left cylinder chamber (11), a right cylinder chamber (12), a control valve connecting component (13), a gear rotating output shaft (14), a ball valve body (15), a right gear transmission piston (16) and a left gear transmission piston (17), characterized in that: The invention also comprises a coking coal pressure transmitter (1), wherein the coking coal pressure transmitter (1) is connected to a signal power distribution isolator (2), the signal power distribution isolator (2) is connected to a PLC analog input template (3), the PLC analog input template (3) is connected to a PLC analog output template (4), the PLC analog output template (4) is connected to an output signal isolator (5), the output signal isolator (5) is connected to an electronic switch (6), the electronic switch (6) is connected to an intelligent valve positioner (7), the intelligent valve positioner (7) is connected to an air lock valve (8), the air lock valve (8) is connected to the regulating valve, the electronic switch (6) is also connected to a two-position three-way solenoid valve (9), one end of the two-position three-way solenoid valve (9) is connected to a filter pressure reducing valve (10), the filter pressure reducing valve (10) is connected to an instrument gas source (18), the other end of the two-position three-way solenoid valve (9) is connected to the air lock valve (8), and the intelligent valve positioner (7) is connected to the filter pressure reducing valve (10).

Images