A control system based on the emergency cut-off valve at the inlet of a natural gas pressure regulating station

Abstract

The utility model discloses a control system based on natural gas pressure regulating station entrance emergency cut -out valve, relate to natural gas pipeline entrance pressure monitoring technical field, it includes: pressure transmitter is set up in the natural gas pipeline of emergency cut -out valve downstream, for real -time monitoring the natural gas pressure in pipeline, first pressure switch is set up in the natural gas pipeline of pressure transmitter downstream, and built -in low pressure alarm value, second pressure switch is set up in the natural gas pipeline of pressure transmitter downstream, and built -in high pressure alarm value, intermediate relay is linked with the output of first pressure switch, second pressure switch, solenoid valve is set up on compressed air pipeline, with emergency cut -out valve, intermediate relay is linked respectively. The application has realized natural gas pressure regulating station entrance pressure's whole time monitoring and intelligent protection, and especially applicable to the gas delivery scene of extremely high security requirement.

Description

Technical Field

[0001] This utility model relates to the field of natural gas pipeline inlet pressure monitoring technology, specifically to a control system based on the emergency shut-off valve at the inlet of a natural gas pressure regulating station. Background Technology

[0002] In natural gas transmission systems within the petrochemical industry, natural gas pressure regulating stations play a crucial role in stabilizing downstream gas supply pressure. The precise control of their inlet pressure directly impacts the safe operation of critical equipment such as downstream gas turbines. When the upstream gas pressure at the emergency shut-off valve of the natural gas pipeline is excessive, a mismatch occurs between the actual pressure value regulated by the pressure regulating station and the preset inlet pressure value of the gas turbine. This pressure mismatch not only affects the operating efficiency of the gas turbine but can also trigger serious safety accidents such as sudden turbine tripping, posing a significant threat to the stable operation of the entire system.

[0003] Currently, the emergency shut-off control of inlet emergency shut-off valves in natural gas pressure regulating stations has significant deficiencies, the core issue being the limitations of the control method. Existing control methods mainly rely on manual emergency stop button operation in the control room. This purely manual control mode has significant shortcomings: firstly, manual operation requires manual execution of the shut-off command, resulting in a delayed response speed and difficulty in completing valve closure immediately when the pressure exceeds the safe range, easily missing the optimal protection opportunity; secondly, manual operation is greatly affected by human factors, and operational errors and reaction delays may lead to untimely control, further amplifying safety risks.

[0004] Meanwhile, the inlet pressure transmitters used in the existing system to monitor pipeline pressure have a potential single point of failure. When the pressure transmitter fails, the system will completely lose its ability to monitor the pressure inside the natural gas pipeline in real time, and will be unable to accurately determine whether the current pressure is higher or lower than the preset safety threshold. At this time, even if dangerous situations such as overpressure or underpressure occur in the pipeline, it is impossible to trigger the emergency shut-off valve to close automatically, and it can only be detected and operated manually. This undoubtedly increases the probability of accidents and seriously affects the reliability and safety of the natural gas pressure regulating station. Utility Model Content

[0005] The purpose of this invention is to provide a control system based on the emergency shut-off valve at the inlet of a natural gas pressure regulating station, which improves the ability to detect pressure anomalies and the speed of emergency response, and ensures that the emergency shut-off valve can be automatically and quickly closed when the pressure exceeds the safe range, thereby ensuring the safe and stable operation of downstream equipment and the entire system.

[0006] To achieve the above objectives, this application proposes a control system based on the emergency shut-off valve at the inlet of a natural gas pressure regulating station, comprising: A pressure transmitter is installed on the natural gas pipeline downstream of the emergency shut-off valve to monitor the natural gas pressure in the pipeline in real time. The first pressure switch is located on the natural gas pipeline downstream of the pressure transmitter and has a built-in low pressure alarm value. The second pressure switch is installed on the natural gas pipeline downstream of the pressure transmitter and has a built-in high pressure alarm value. The intermediate relay is connected to the output terminals of the first pressure switch and the second pressure switch. The solenoid valve is installed on the compressed air pipeline and is connected to the emergency shut-off valve and the intermediate relay respectively.

[0007] In one embodiment, the solenoid valve is connected to an emergency shut-off valve via a pneumatic actuator.

[0008] In one embodiment, the first pressure switch and the second pressure switch output switching signals. When the pressure in the natural gas pipeline is lower than the low pressure alarm value or higher than the high pressure alarm value, the switching signals trigger the intermediate relay to lose power.

[0009] In one embodiment, the intermediate relay is a normally open contact relay. When a switching signal triggers the intermediate relay to lose power, the normally open contact opens, causing the solenoid valve to lose power.

[0010] In one embodiment, the pressure transmitter outputs an analog signal to a DCS system, which then controls an intermediate relay based on the analog signal.

[0011] In one embodiment, the intermediate relay includes a first intermediate relay and a second intermediate relay connected in parallel.

[0012] In one embodiment, the solenoid valve includes a first solenoid valve and a second solenoid valve connected in parallel, wherein the first solenoid valve is connected to a first intermediate relay and the second solenoid valve is connected to a second intermediate relay.

[0013] In one embodiment, an isolation ball valve and an instrument valve are provided between the first pressure switch, the second pressure switch and the natural gas pipeline.

[0014] In one embodiment, an isolation ball valve and an instrument valve are provided between the pressure transmitter and the natural gas pipeline.

[0015] In one embodiment, an instrument valve is provided on the compressed air pipeline before the solenoid valve.

[0016] The advantages of the above technical solution adopted in this utility model compared with the prior art are: 1. By forming a multi-pressure monitoring system through pressure transmitters, a first pressure switch (low alarm value), and a second pressure switch (high alarm value), the risk of system failure caused by single-point failure is greatly reduced.

[0017] 2. When the pressure exceeds the preset range, the pressure switch directly triggers the intermediate relay to operate, and the emergency shut-off valve is quickly closed through the solenoid valve-pneumatic actuator link, with a response speed much faster than manual operation.

[0018] 3. Both the intermediate relays and solenoid valves are configured in parallel with redundancy, so that the failure of a single component does not affect the overall function of the system, thus significantly improving reliability.

[0019] 4. The pressure transmitter outputs an analog signal to the DCS system in real time, supporting manual intervention control and providing backup operation means when automatic control fails, forming a closed-loop control.

[0020] 5. Isolation ball valves and instrument valves are installed at each monitoring point and before the solenoid valve, which can be used for online isolation and maintenance without affecting the main process operation, thus reducing maintenance costs. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of a control system based on an emergency shut-off valve at the inlet of a natural gas pressure regulating station. Figure 2 This is an application diagram of a control system based on an emergency shut-off valve at the inlet of a natural gas pressure regulating station. Among them: 1. Emergency shut-off valve, 11. Valve open button, 12. Valve close button, 13. DCS open command, 14. DCS close command, 2. First pressure switch, 3. Second pressure switch, 41. First intermediate relay, 411. Normally open contact of the first intermediate relay, 42. Second intermediate relay, 421. Normally open contact of the second intermediate relay, 51. First solenoid valve, 52. Second solenoid valve, 6. Pressure transmitter, 7. Natural gas pipeline, 8. Compressed air pipeline, 91. Instrument valve, 92. Isolation ball valve, 10. Pneumatic actuator. Detailed Implementation

[0022] To make the technical problems, technical solutions, and beneficial effects to be solved by this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and are not intended to limit the scope of this application.

[0023] It should be noted that when a component is referred to as being "fixed to" or "set on" another component, it can be directly on or indirectly on that other component. When a component is referred to as being "connected to" another component, it can be directly connected to or indirectly connected to that other component.

[0024] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, "multiple" means two or more, unless otherwise expressly specified. "Several" means one or more, unless otherwise expressly specified.

[0025] In the description of this application, it should be understood that the terms "center", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0026] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0027] like Figure 1 , Figure 2 As shown, this utility model discloses a control system based on the emergency shut-off valve at the inlet of a natural gas pressure regulating station. This system, through multiple monitoring and redundant control design, achieves automated and intelligent control of the emergency shut-off valve, specifically including: Emergency shut-off valve 1 is installed on the natural gas pipeline 7 at the inlet of the natural gas pressure regulating station. As the core control component for pipeline on / off, its on / off state directly determines the start and stop of natural gas transmission.

[0028] Pressure transmitter 6 is installed on natural gas pipeline 7 downstream of emergency shut-off valve 1. It is used to monitor the natural gas pressure in the pipeline in real time and continuously transmit the monitored pressure signal to the DCS system in analog form. The DCS system is equipped with low pressure threshold and high pressure threshold. Isolation ball valve 92 and instrument valve 91 are sequentially installed between pressure transmitter 6 and natural gas pipeline 7. By closing these two valves, pressure transmitter 6 can be isolated and maintained online without affecting the normal operation of the main natural gas pipeline.

[0029] Both the first pressure switch 2 and the second pressure switch 3 are located on the natural gas pipeline 7 downstream of the pressure transmitter 6, and are each equipped with an isolation ball valve 92 and an instrument valve 91 for easy independent maintenance. The first pressure switch 2 has a built-in low-pressure alarm value, and the second pressure switch 3 has a built-in high-pressure alarm value. These two switches monitor abnormally low and high pressure conditions in the pipeline, respectively. It should be noted that independently setting the high and low pressure alarm values ​​allows for precise adjustment according to process requirements, avoiding malfunctions caused by pressure fluctuations and improving system stability.

[0030] The intermediate relays include a first intermediate relay 41 and a second intermediate relay 42 connected in parallel. The input terminals of the two relays are electrically connected to the output terminals of the first pressure switch 2 and the second pressure switch 3, respectively, to receive the switching signals transmitted by the pressure switches. The first intermediate relay 41 is equipped with a normally open contact 411, and the second intermediate relay 42 is equipped with a normally open contact 421. The contact state changes in conjunction with the energized / de-energized state of the relay coil.

[0031] The solenoid valves, including a first solenoid valve 51 and a second solenoid valve 52 connected in parallel, are both installed on the compressed air pipeline 8. An instrument valve 91 is provided on the compressed air pipeline 8 before the solenoid valves for controlling the air supply to the solenoid valves and for online maintenance. The first solenoid valve 51 is connected in series with the normally open contact 411 of the first intermediate relay 41 and then connected to the control circuit. The second solenoid valve 52 is connected in series with the normally open contact 421 of the second intermediate relay 42 and then connected to the control circuit. The output terminals of both solenoid valves are connected to the pneumatic actuator 10, which is connected to the emergency shut-off valve 1. The valve is opened and closed by controlling the flow of compressed air.

[0032] The working principle of the control system in this embodiment is as follows: When the natural gas pipeline pressure is between the low pressure alarm value and the high pressure alarm value, the first pressure switch 2 and the second pressure switch 3 output a closing signal, at which time the intermediate relay coil is energized. After the coil is energized, its normally open contact 411 or 421 becomes closed. After the normally open contact is closed, the first solenoid valve 51 or the second solenoid valve 52 connected in series with it is energized, the compressed air supply is normal, and the pneumatic actuator drives the emergency shut-off valve to remain open, ensuring the normal transportation of natural gas through the pipeline.

[0033] When the inlet pressure in the natural gas pipeline 7 is lower than the low-pressure alarm value of the first pressure switch 2 or higher than the high-pressure alarm value of the second pressure switch 3, the first pressure switch 2 or the second pressure switch 3 will output a disconnect signal, which is transmitted to the coil of the first intermediate relay 41 or the second intermediate relay 42. After the intermediate relay coil is de-energized, its corresponding normally open contact 411 or 421 opens, causing the first solenoid valve 51 or the second solenoid valve 52 connected in series to be de-energized. Since the pneumatic actuator 10 adopts the "fail-safe shutdown" switching characteristic design, the compressed air supply will be cut off after the solenoid valve is de-energized. The pneumatic actuator 10 then drives the emergency shut-off valve 1 to close quickly, realizing the emergency shut-off of the natural gas pipeline and avoiding dangers such as gas turbine tripping due to abnormal pressure.

[0034] Meanwhile, the pressure transmitter 6 monitors the pipeline pressure in real time and transmits the analog signal to the DCS system, forming a dual monitoring mechanism: when the first pressure switch 2 or the second pressure switch 3 fails, the DCS system can determine the pressure abnormality based on the signal from the pressure transmitter 6, and control the intermediate relay to operate by issuing the DCS shut-off command 14, thereby indirectly achieving the closure of the emergency shut-off valve 1; in addition, the system also supports manual operation via the valve shut-off button 12, providing backup protection when the automatic control link fails, and ensuring the reliability of control.

[0035] When it is necessary to reopen the emergency shut-off valve 1, it can be manually operated by the valve opening button 11, or the DCS system can issue a DCS opening command 13 to energize the intermediate relay coil, close the normally open contact, energize the solenoid valve and allow air to pass through, and drive the pneumatic actuator 10 to open the valve.

[0036] The beneficial effects of this implementation are as follows: by using dual monitoring of the first / second pressure switches and parallel configuration of the first / second intermediate relays and solenoid valves, system failure caused by single-point failure is avoided. Even if one component fails, the remaining components can still maintain control functions. When the pressure is abnormal, the pressure switch directly triggers a chain reaction without manual intervention. The response time from pressure exceeding the threshold to valve closure is much shorter than that of traditional manual control, significantly reducing the risk of accidents.

[0037] The combination of automatic control, DCS remote control and manual control forms a closed-loop control system to meet the control needs under different working conditions, and the control mode can be flexibly switched in emergency situations.

[0038] The isolation ball valve 92 and instrument valve 91 between each monitoring component and the pipeline, as well as the instrument valve 91 before the solenoid valve, enable online isolation and maintenance of individual components without interrupting the main natural gas flow, significantly reducing maintenance costs and downtime losses.

[0039] In summary, through scientific hardware configuration and logic control, this system has achieved accurate monitoring of the inlet pressure of the natural gas pressure regulating station and automated control of the emergency shut-off valve, effectively ensuring the safe and stable operation of downstream equipment and the entire system.

[0040] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application.

Claims

1. A control system for an inlet emergency shut-off valve of a natural gas pressure regulating station, characterized in that, include: A pressure transmitter is installed on the natural gas pipeline downstream of the emergency shut-off valve to monitor the natural gas pressure in the pipeline in real time. The first pressure switch is located on the natural gas pipeline downstream of the pressure transmitter and has a built-in low pressure alarm value. The second pressure switch is installed on the natural gas pipeline downstream of the pressure transmitter and has a built-in high pressure alarm value. An intermediate relay is connected to the output terminals of the first pressure switch and the second pressure switch. The solenoid valve is installed on the compressed air pipeline and is connected to the emergency shut-off valve and the intermediate relay respectively.

2. The control system for the emergency shut-off valve at the inlet of a natural gas pressure regulating station according to claim 1, characterized in that, The solenoid valve is connected to the emergency shut-off valve via a pneumatic actuator.

3. The control system for the emergency shut-off valve at the inlet of a natural gas pressure regulating station according to claim 1, characterized in that, The first pressure switch and the second pressure switch output switching signals. When the pressure in the natural gas pipeline is lower than the low pressure alarm value or higher than the high pressure alarm value, the switching signals trigger the intermediate relay to lose power.

4. The control system for the emergency shut-off valve at the inlet of a natural gas pressure regulating station according to claim 3, characterized in that, The intermediate relay is a normally open contact relay. When a switching signal triggers the intermediate relay to lose power, the normally open contact opens, causing the solenoid valve to lose power.

5. The control system for the emergency shut-off valve at the inlet of a natural gas pressure regulating station according to claim 1, characterized in that, The pressure transmitter outputs an analog signal to the DCS system, and the DCS system controls the intermediate relay based on the analog signal.

6. The control system for the emergency shut-off valve at the inlet of a natural gas pressure regulating station according to claim 1, characterized in that, The intermediate relay includes a first intermediate relay and a second intermediate relay connected in parallel.

7. The control system for the emergency shut-off valve at the inlet of a natural gas pressure regulating station according to claim 6, characterized in that, The solenoid valve includes a first solenoid valve and a second solenoid valve connected in parallel, wherein the first solenoid valve is connected to a first intermediate relay and the second solenoid valve is connected to a second intermediate relay.

8. The control system for the emergency shut-off valve at the inlet of a natural gas pressure regulating station according to claim 1, characterized in that, An isolation ball valve and an instrument valve are installed between the first pressure switch, the second pressure switch and the natural gas pipeline.

9. The control system for the emergency shut-off valve at the inlet of a natural gas pressure regulating station according to claim 1, characterized in that, An isolation ball valve and an instrument valve are installed between the pressure transmitter and the natural gas pipeline.

10. The control system for an emergency shut-off valve at the inlet of a natural gas pressure regulating station according to claim 1, characterized in that, An instrument valve is installed on the compressed air pipeline before the solenoid valve.

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