A device for preventing automatic pressure charging of a coal gas pipeline under negative pressure

Abstract

The utility model relates to the field of coal gas pipeline safety protection, especially a device for preventing automatic pressure charging of coal gas pipeline negative pressure. Including coal gas pipeline, nitrogen pipeline, pressure transmitter, digital display, solenoid valve, switching power supply, pneumatic butterfly valve, air cylinder and gas source pipe. The pressure transmitter is installed on the coal gas pipeline, and its signal output end is connected with the digital display; the manual pressure charging valve and the pneumatic butterfly valve are connected in series on the nitrogen pipeline, the valve rod of the pneumatic butterfly valve is connected with the output shaft of the air cylinder; the switching power supply supplies power to the whole system, one way of its 24V+ end is connected with the digital display, the other way is connected with the 24V+ end of the solenoid valve through the built-in opening point interface of the digital display, and the 24V- end of the solenoid valve is connected with the negative electrode of the power supply; the air inlet of the solenoid valve is connected with the external gas source, and the air outlet is connected with the air cylinder through the gas source pipe. The utility model realizes the automatic monitoring and pressure charging of the coal gas pipeline through the linkage structure of "pressure detection - circuit control - gas path driving - mechanical execution", effectively solving the problem of manual response lag.

Description

Technical Field

[0001] This utility model relates to the field of gas pipeline safety protection, specifically to a device for preventing automatic pressurization of negative pressure in gas pipelines. Background Technology

[0002] In industrial production and urban energy supply systems, coal gas, with its highly efficient energy conversion characteristics, has become an indispensable core energy source in metallurgy, chemical industry, and civil applications. The coverage of coal gas pipeline networks is constantly expanding, making pipeline operation safety a crucial link in ensuring stable production and daily life. During long-term transportation, coal gas pipelines are highly susceptible to pressure anomalies due to multiple uncontrollable factors, with excessively low pressure or even negative pressure being particularly dangerous. When the pressure inside the pipeline is lower than the external atmospheric pressure, air can seep into the pipeline through flange seals, valve interfaces, and other parts, forming a flammable and explosive mixture with the coal gas. This not only accelerates corrosion and wear of the pipeline's inner walls but may also trigger an explosion when exposed to an ignition source. Furthermore, the turbulent airflow under negative pressure can lead to interruptions in coal gas transportation, causing production stoppages and economic losses. Industry statistics show that in the past five years, safety accidents caused by negative pressure in coal gas pipelines accounted for 32% of all pipeline safety accidents, with over 80% of these directly related to untimely pressure control.

[0003] To address the aforementioned issues, existing technologies have developed solutions for regulating gas pipeline pressure, such as the "Pipeline Negative Pressure Reduction Device" with patent number CN221991233U. This device reduces the negative pressure within the pipeline by using a combination of inner and outer pipes and wear-resistant packing to decrease the diameter of the air box inlet. However, its core application is limited to negative pressure relief in specific equipment like air boxes, and it can only passively reduce negative pressure through structural optimization, failing to achieve active pressurization regulation. Currently, the mainstream pressure assurance method in the industry still relies on manual nitrogen pressurization devices. This involves periodically inspecting the pipeline pressure manually and manually opening the nitrogen valve to pressurize when the pressure is low. This method has significant technical drawbacks: firstly, manual inspections are time-sensitive, making real-time pressure monitoring impossible. Sudden drops in pipeline pressure are often difficult to detect promptly, leading to a severe delay in pressurization response and missing the optimal opportunity to curb negative pressure formation; secondly, manual operation is highly susceptible to human factors, resulting in inaccurate valve opening angle control, over- or under-pressurization, and the risk of pipeline negative pressure is even more difficult to manage during non-inspection periods such as nighttime and holidays. Furthermore, some existing automatic pressurization devices, such as the "Automatic Pressurization Device for Gas Pipeline Testing" with publication number CN120043851A, focus on pressurization detection during pipeline testing, rather than negative pressure protection for operating gas pipelines. Therefore, they cannot meet the pressure control requirements of continuous operation in industrial settings. Thus, developing a gas pipeline negative pressure protection device capable of real-time monitoring and automatic response, addressing the core issues of delayed response and reliance on manual intervention in existing technologies, has become an urgent need in the field of gas pipeline safety protection. Utility Model Content

[0004] The purpose of this invention is to provide a device for automatically pressurizing gas pipelines to prevent negative pressure, thereby solving the problems of reliance on manual labor and delayed response in the existing technology for negative pressure protection of gas pipelines.

[0005] To achieve the above objectives, the following technical solution is adopted.

[0006] An automatic pressurization device for preventing negative pressure in a gas pipeline includes a gas pipeline, a nitrogen pipeline, a pressure transmitter, a digital display, a solenoid valve, a switching power supply, a pneumatic butterfly valve, a cylinder, and a gas source pipe. The pressure transmitter is fixedly installed on the pipe body of the gas pipeline, and the signal output terminal of the pressure transmitter is connected to the signal input terminal of the digital display meter through a wire. A manual pressurization valve and a pneumatic butterfly valve are connected in series on the nitrogen pipeline. The valve stem of the pneumatic butterfly valve is fixedly connected to the output shaft of the cylinder via a coupling. The switching power supply is a DC 24V power supply. The 24V+ terminal of the switching power supply is connected in two ways via wires. One way is connected to the power input terminal of the digital display, and the other way is connected to the 24V+ terminal of the solenoid valve through the built-in open contact interface of the digital display. The 24V- terminal of the solenoid valve is connected to the 24V- terminal of the switching power supply. The air inlet of the solenoid valve is used to connect to an external air source, and the air outlet of the solenoid valve is sealed to the control air circuit interface of the cylinder through the air source pipe.

[0007] Optionally, the signal output terminal of the pressure transmitter is provided with a signal input IN+ terminal and a signal input IN- terminal, and the signal input IN+ terminal and the signal input IN- terminal are fixedly connected to the signal input terminal of the digital display through wires.

[0008] Optionally, the manual pressurizing valve and the pneumatic butterfly valve are connected in series along the nitrogen delivery direction on the nitrogen pipeline.

[0009] Optionally, the gas source pipe is a flexible sealed pipe.

[0010] Optionally, the solenoid valve is a two-position five-way solenoid valve.

[0011] Optionally, the digital display is a pressure display and interlocking control component with on / off point control function.

[0012] Optionally, the air passage interface of the cylinder is sealed to an external air source through the air source pipe.

[0013] Compared with the prior art, the present invention has the following beneficial effects: This application effectively solves the core problems of existing technologies in gas pipeline negative pressure protection, which rely on manual labor and have a delayed response, by constructing a complete linkage structure of "pressure detection - signal transmission - circuit control - pneumatic drive - pressurization execution". In this device, the pressure transmitter collects the gas pipeline pressure signal in real time and transmits it to a digital display. The digital display achieves precise control of the solenoid valve through a built-in open-circuit interface. The solenoid valve then drives the cylinder to drive the pneumatic butterfly valve to complete the pressurization action. The entire process requires no manual intervention, and the time from pressure anomaly detection to pressurization response is shortened to the second level. This completely changes the passive "post-event remedy" mode of traditional manual devices, enabling timely intervention in the early stage of negative pressure formation and effectively preventing air from seeping into the pipeline. The branch power supply design of the DC 24V switching power supply ensures the stability of the digital display pressure monitoring and realizes the interlock control between the solenoid valve and the digital display, making the circuit system more reliable. The coupling connection structure between the pneumatic butterfly valve and the cylinder ensures the accuracy of the pressurization actuator, providing structural guarantee for the timeliness of pressure control.

[0014] The one-to-one connection between the pressure transmitter's IN+ and IN- terminals and the digital display avoids interference and attenuation during signal transmission, ensuring that the 4-20mA electrical signal accurately reflects pipeline pressure changes and provides precise data support for subsequent control decisions. The clearly defined series sequence of the manual charging valve and the pneumatic butterfly valve allows for emergency charging via the manual valve in case of automatic control failure, forming a dual protection mechanism and enhancing the device's fault tolerance. The flexible, sealed air supply pipe adapts to position changes during cylinder operation while ensuring the air circuit connection's sealing, preventing charging delays caused by pressure loss. The two-position five-way solenoid valve optimizes air circuit switching efficiency, enabling faster switching between cylinder charging and venting actions, further improving charging response speed. The limited digital display with open / close point control integrates pressure display and interlocking control, simplifying the device structure while improving control accuracy. The sealed connection between the cylinder and the external air source ensures the dynamic stability of cylinder operation, providing continuous power for the reliable opening and closing of the pneumatic butterfly valve. These technical features work together to create synergistic advantages for the device in terms of accurate monitoring, rapid response, and reliable operation. This not only adapts to the renovation needs of existing gas pipeline networks but also reduces installation and maintenance costs, significantly improving the safety and economy of gas pipeline operation. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of an embodiment of the device for automatically pressurizing a gas pipeline to prevent negative pressure according to this utility model.

[0016] The components include: 1. Gas pipeline; 2. Nitrogen pipeline; 3. Pressure transmitter; 4. Digital display; 5. Solenoid valve; 6. Pneumatic butterfly valve; 7. Cylinder; 8. Gas source pipe; 9. Switching power supply. Detailed Implementation

[0017] The present invention will now be described in detail with reference to the accompanying drawings and embodiments. It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other.

[0018] The following detailed description is exemplary and intended to provide further detailed explanation of the present invention. Unless otherwise specified, all technical terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains. The terminology used in this invention is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to the present invention.

[0019] Example 1 like Figure 1As shown, coal gas is an important energy source for industrial production and urban life, and the safe operation of its transmission pipelines directly affects the continuity of production and the safety of people's lives and property. In actual operation, the internal pressure of coal gas pipeline 1 is affected by various factors such as fluctuations in user gas consumption, changes in upstream gas supply pressure, and pipeline leaks, making it prone to sudden pressure drops or even negative pressure. When negative pressure forms inside the pipeline, outside air can seep into the pipeline through flange sealing surfaces, valve stuffing boxes, and pipeline joints, mixing with the coal gas to form an explosive mixture. If this mixture encounters an ignition source, it can cause an explosion. Furthermore, the entry of air accelerates corrosion of the pipeline's inner wall, shortens its service life, and increases maintenance costs. To solve this problem, an automatic pressurization device to prevent negative pressure in coal gas pipeline 1 has been developed. This device can monitor changes in the internal pressure of coal gas pipeline 1 in real time and automatically initiate the pressurization process when the pressure is abnormal, ensuring that the pipeline pressure is always maintained within a safe range.

[0020] The core components of this device include a gas pipeline 1, a nitrogen pipeline 2, a pressure transmitter 3, a digital display 4, a solenoid valve 5, a switching power supply 9, a pneumatic butterfly valve 6, a cylinder 7, and a gas source pipe 8. These components are connected through a reasonable structure and signal linkage to form a complete pressure monitoring and automatic pressurization system. The gas pipeline 1, as the main body for gas transportation, uses seamless steel pipes conforming to industrial transportation standards. The pipe diameter can be selected between DN100 and DN1000 according to actual transportation requirements, and the pipe wall thickness is determined according to relevant pressure pipeline specifications to ensure no deformation or leakage occurs during normal operating pressure and pressurization. The nitrogen pipeline 2, as the transportation channel for the pressurizing medium, is made of 304 stainless steel. This material has good corrosion resistance and pressure resistance, preventing rust caused by trace amounts of moisture in the nitrogen. Its smooth inner wall also reduces resistance during nitrogen transportation, ensuring the pressurization speed. The diameter of nitrogen pipeline 2 must match that of gas pipeline 1. Typically, a specification of DN50 to DN150 is selected. The specific dimensions are determined based on the required pressurization flow rate to ensure that the pressure of gas pipeline 1 is increased to a safe range in the shortest possible time.

[0021] As the core component of pressure detection, the installation location of pressure transmitter 3 directly affects the accuracy and timeliness of pressure detection. It is typically fixed to the gas pipeline 1, preferably in a straight section of the pipeline, avoiding bends, valves, tees, and other areas prone to airflow disturbances. Unstable airflow in these areas can cause fluctuations in pressure detection, affecting subsequent control logic. During installation, mounting holes matching the interface of pressure transmitter 3 are pre-drilled on the gas pipeline 1. Pressure transmitter 3 is fixed using a flange connection, with gas-corrosion-resistant gaskets, such as nitrile rubber or PTFE gaskets, placed between the flanges to ensure a tight seal and prevent gas leakage. The measurement range of pressure transmitter 3 must cover the normal operating pressure of gas pipeline 1 and the possible negative pressure range, typically set to -0.1 MPa to 0.1 MPa, with an accuracy class of no less than 0.5 to ensure the accuracy of the pressure signal measurement.

[0022] The signal output terminal of pressure transmitter 3 and the signal input terminal of digital display meter 4 are stably connected via wires. To ensure that the signal transmission is not affected by external electromagnetic interference, a two-core shielded twisted-pair cable is used, with one end of the shield grounded and the grounding resistance not exceeding 4 ohms. The signal output terminal has dedicated signal input IN+ and IN- terminals. These two terminals are fixedly connected one-to-one with their corresponding terminals on the signal input terminal of digital display meter 4. During connection, crimp terminals are used to firmly crimp the wires to the terminals, and the crimped area is wrapped with insulating tape and then covered with insulating heat shrink tubing for secondary insulation to prevent short circuits or poor contact. This one-to-one connection method ensures that the 4 to 20mA analog signal output from pressure transmitter 3 is transmitted completely and accurately to digital display meter 4, without signal attenuation or distortion due to wire crossings or contact problems.

[0023] As the core component for pressure signal processing and control command issuance, the digital display meter 4 not only converts the analog signal transmitted by the pressure transmitter 3 into a digital signal and displays it in real time, but also possesses crucial on / off point control functions. The power input terminal of the digital display meter 4 is connected to a stable 24V DC voltage. Internally, it houses a signal processing module and a relay control module. The signal processing module converts the received 4-20mA analog signal into a corresponding pressure value, which is displayed in real time on the LED display screen of the digital display meter 4. The display accuracy reaches 0.001MPa, facilitating real-time monitoring of pipeline pressure by operators. Operators can preset the lower and upper pressure limits using the buttons on the digital display meter 4 according to the actual operating requirements of the gas pipeline 1. Common preset ranges are a lower pressure limit of 3kPa and an upper pressure limit of 16kPa. These preset values ​​are stored in the internal memory of the digital display meter 4 as the basis for control logic judgments. When the digital display 4 detects that the pipeline pressure is lower than the preset lower limit, its internal relay will activate, causing the built-in opening interface to close; when the pressure is higher than the preset upper limit, the relay will reset, the opening interface will open, thereby realizing the on / off control of the subsequent solenoid valve 5.

[0024] A manual pressurizing valve and a pneumatic butterfly valve 6 are connected in series on nitrogen pipeline 2 in a specific order. They are arranged sequentially along the nitrogen delivery direction; that is, after nitrogen flows out of the nitrogen source, it first passes through the manual pressurizing valve, then enters the pneumatic butterfly valve 6, and finally flows into gas pipeline 1. This arrangement allows the manual pressurizing valve to be used as an emergency pressurizing method when the equipment malfunctions or requires maintenance, and also facilitates separate maintenance of the pneumatic butterfly valve 6. The manual pressurizing valve is a shut-off valve, with its body material identical to that of nitrogen pipeline 2—304 stainless steel—and its sealing surface made of hard alloy, providing excellent sealing performance and wear resistance, ensuring no nitrogen leakage during long-term use. The nominal pressure of the manual pressurizing valve is not less than 1.6 MPa to meet the pressure requirements during nitrogen delivery. Its operating handle features a non-slip design for easy and quick operation in emergencies.

[0025] The pneumatic butterfly valve 6, serving as the actuator for switching on and off the nitrogen pipeline 2, employs an eccentric butterfly valve structure. This structure features rapid opening and closing speeds and excellent sealing performance, enabling it to quickly open or close the valve upon receiving a control signal, ensuring timely pressurization and accurate cessation of pressurization. The valve stem of the pneumatic butterfly valve 6 is fixedly connected to the output shaft of the cylinder 7 via a coupling. This coupling is a flexible coupling made of 45# steel with a galvanized surface for rust prevention. The flexible coupling has a certain ability to compensate for relative misalignment between the two shafts, effectively mitigating the impact force generated during cylinder 7's operation, protecting the valve stem and cylinder 7's output shaft from damage, while ensuring efficient power transmission between them. This allows the linear motion of cylinder 7 to be precisely converted into the rotational motion of the valve stem, thereby controlling the opening angle of the butterfly valve core. The model of cylinder 7 is selected based on the nominal diameter and working pressure of the pneumatic butterfly valve 6, ensuring that its output thrust can overcome the medium pressure experienced by the butterfly valve core during operation, achieving reliable valve opening and closing. The cylinder 7 is installed using a bracket. The bracket is fixed to the ground or a nearby steel structure with expansion bolts. The height and angle of the bracket can be adjusted according to the actual installation space to ensure that the output shaft of the cylinder 7 is coaxial with the valve stem of the pneumatic butterfly valve 6 and to avoid additional torque.

[0026] The switching power supply 9 provides a stable 24V DC power supply to all electrical components of the entire device. Its input voltage is 220V AC, adaptable to the fluctuating power grid environment of industrial sites, with an allowable input voltage fluctuation range of 160V to 260V. The output power of the switching power supply 9 is determined based on the total power of the connected electrical components; typically, a 100W switching power supply 9 is selected to meet the power supply requirements of the digital display meter 4, solenoid valve 5, and any other auxiliary electrical components that may be added. The switching power supply 9 has overcurrent protection, overvoltage protection, and short-circuit protection functions. When an excessive current, excessive voltage, or short-circuit fault occurs in the circuit, the switching power supply 9 will automatically cut off the output to protect subsequent electrical components from damage. After the fault is cleared, power supply can be automatically restored or restored manually.

[0027] The 24V+ terminal of the switching power supply 9 is split into two paths via wires. One path connects directly to the power input terminal of the digital display meter 4, providing it with a stable operating power supply. This path uses a 1 square millimeter copper core insulated wire, whose current carrying capacity meets the operating current requirements of the digital display meter 4. The outer sheath of the wire is made of PVC material with a temperature resistance rating of not less than 70 degrees Celsius to adapt to the ambient temperature of the industrial environment. The other path connects to the 24V+ terminal of the solenoid valve 5 through the built-in open contact interface of the digital display meter 4, forming a control loop. This path also uses a 1 square millimeter copper core insulated wire. During the connection process, both ends of the wire are crimped with cold-pressed terminals, and the contact resistance between the cold-pressed terminals and the wire is not greater than 0.01 ohms to ensure smooth current transmission. The 24V terminal of the solenoid valve 5 is directly connected to the 24V terminal of the switching power supply 9 via a wire to form a complete power supply and control circuit. All wire connection points are wrapped with insulating tape, with no less than 3 layers, to ensure the insulation performance of the connection points and prevent leakage or short circuit accidents.

[0028] As the switching component between circuit control and pneumatic control, the selection of solenoid valve 5 directly affects the reliability and response speed of pneumatic control. A two-position five-way solenoid valve 5 is selected. This type of solenoid valve 5 has two working positions and five ports, enabling bidirectional control of cylinder 7, that is, controlling the extension and retraction of cylinder 7, thereby driving the opening and closing of pneumatic butterfly valve 6. The nominal diameter of solenoid valve 5 is determined according to the diameter of air source pipe 8, and is usually selected in the range of DN15 to DN25. Its working pressure range is 0.15MPa to 1.0MPa, which can adapt to the compressed air pressure commonly used in industrial sites. The coil voltage of solenoid valve 5 is DC 24V, which is consistent with the output voltage of switching power supply 9. The coil power does not exceed 5W to ensure that overheating will not occur during long-term energization. The air inlet of solenoid valve 5 is connected to an external air source through an air pipe connector. The external air source is usually compressed air, and its pressure needs to be stable between 0.6MPa and 0.8MPa. A filter pressure reducing valve is installed at the air inlet to filter impurities and moisture in the compressed air and stabilize the pressure within the working pressure range of solenoid valve 5, protecting the internal seals of solenoid valve 5 from damage and extending its service life.

[0029] The outlet of solenoid valve 5 is sealed to the control air circuit interface of cylinder 7 via air supply pipe 8. Air supply pipe 8 is a flexible, sealed pipe with good flexibility and aging resistance, adapting to position changes during cylinder 7's operation and preventing air circuit blockage caused by pipe bending. Air supply pipe 8 is made of either polytetrafluoroethylene (PTFE) or nitrile rubber. PTFE pipe 8 offers stronger corrosion resistance and is suitable for industrial environments containing corrosive gases; nitrile rubber pipe 8 offers better elasticity and is suitable for applications with significant vibration. The diameter of air supply pipe 8 is determined based on the air consumption of cylinder 7 to ensure sufficient airflow for cylinder 7's operation; typically, an inner diameter of 8 mm to 12 mm is selected. Quick-connect fittings are used to connect air supply pipe 8 to the outlet of solenoid valve 5 and the control air circuit interface of cylinder 7. Quick-connect fittings offer quick connection and good sealing performance, enabling rapid connection without tools while ensuring a leak-proof seal. The pull-out force between the quick-connect fitting and the air supply pipe 8 shall not be less than 50N to prevent the air supply pipe 8 from falling off due to vibration or other factors during operation.

[0030] In addition to connecting to the outlet of the solenoid valve 5, the air supply interface of cylinder 7 is also sealed to an external air source via another air supply pipe 8, forming a complete air supply system. This air supply pipe 8 also uses a flexible sealing pipe, and the connection method is the same as above, ensuring that cylinder 7 can obtain continuous and stable air pressure during operation. Cylinder 7 has a piston and piston rod inside, and the piston is equipped with a sealing ring made of polyurethane, which has good sealing performance and wear resistance, effectively preventing gas leakage inside cylinder 7 and ensuring that cylinder 7 outputs sufficient thrust. When the solenoid valve 5 is energized, compressed air enters the rodless chamber of cylinder 7 through air supply pipe 8, pushing the piston and causing the piston rod to extend. The piston rod drives the valve stem of the pneumatic butterfly valve 6 to rotate through the coupling, opening the valve core of the butterfly valve, opening the nitrogen pipeline 2, and starting to pressurize the gas pipeline 1; when the solenoid valve 5 is de-energized, compressed air enters the rod chamber of cylinder 7, pushing the piston and causing the piston rod to retract, closing the valve core of the butterfly valve, and stopping the pressurization.

[0031] The specific operating process of the device is as follows: Before starting the device, the operator first checks the connection of each component to ensure that the connection and seal of the gas pipeline 1 and nitrogen pipeline 2 are good, and that the electrical wiring is correct, without any looseness or short circuits. Then, the manual pressurization valve is opened to the normally open state to prepare for nitrogen delivery. Next, the switching power supply 9 is turned on, and the switching power supply 9 starts to output DC 24V voltage, energizing the digital display 4 and the solenoid valve 5, and the device enters normal operating condition. The pressure transmitter 3 detects the pressure inside the gas pipeline 1 in real time and converts the detected pressure signal into a 4 to 20mA analog electrical signal, which is transmitted to the digital display 4 through the signal input IN+ and signal input IN- terminals. The signal processing module inside the digital display 4 converts the received analog signal into a digital signal and displays the corresponding pressure value on the display screen in real time. The operator can intuitively understand the pressure status of the gas pipeline 1 through the display screen.

[0032] The digital display 4 has preset lower and upper pressure limits as control thresholds. When the detected pressure in gas pipeline 1 is lower than the preset lower pressure limit, the relay inside the digital display 4 activates, its built-in open interface closes, the control circuit is connected, the coil of solenoid valve 5 is energized to generate a magnetic field, which pushes the valve core to move, connecting the air inlet of solenoid valve 5 with the air outlet leading to the rodless chamber of cylinder 7. Compressed air, after being filtered and depressurized by the filter pressure reducing valve, enters the rodless chamber of cylinder 7 through solenoid valve 5. As the air pressure in the rodless chamber increases, it pushes the piston to overcome the spring force and drive the piston rod to extend. The piston rod drives the valve stem of pneumatic butterfly valve 6 to rotate clockwise through the flexible coupling, and the valve core of butterfly valve gradually opens, connecting nitrogen pipeline 2 with gas pipeline 1. Nitrogen flows out from the nitrogen source, passes through the manual pressurization valve pneumatic butterfly valve 6, and enters gas pipeline 1, starting the pressurization of gas pipeline 1. During the pressurization process, the pressure transmitter 3 continuously monitors the pressure changes in the gas pipeline 1 and transmits the real-time pressure signal to the digital display 4, and the pressure value on the display screen of the digital display 4 gradually increases.

[0033] When the pressure in gas pipeline 1 rises to the preset upper pressure limit, the relay inside digital display 4 resets, the built-in opening interface disconnects, the control circuit is cut off, the coil of solenoid valve 5 is de-energized, the magnetic field disappears, and the valve core resets under the action of spring force, connecting the air inlet of solenoid valve 5 with the air outlet leading to the rod chamber of cylinder 7. Compressed air enters the rod chamber of cylinder 7, pushing the piston and causing the piston rod to retract. The piston rod drives the valve stem of pneumatic butterfly valve 6 to rotate counterclockwise through the coupling, and the valve core of the butterfly valve gradually closes. When the valve core is completely closed, the passage between nitrogen pipeline 2 and gas pipeline 1 is cut off, and the pressurization process stops. At this time, the pressure in gas pipeline 1 is maintained within the safe range between the upper and lower pressure limits, and the device returns to the pressure monitoring state, waiting for the next pressure abnormality signal to be triggered.

[0034] During operation, if a malfunction occurs in solenoid valve 5 or a control circuit failure causing the automatic pressurization function to fail, the operator can perform emergency pressurization of gas pipeline 1 using the manual pressurization valve. In this case, the operator simply rotates the handle of the manual pressurization valve to open the valve, allowing nitrogen to directly enter gas pipeline 1 through the manual pressurization valve to replenish pressure. After troubleshooting, the manual pressurization valve is returned to its normally open position, and the device resumes automatic control mode. Furthermore, all components of the device adopt a modular design. When a component malfunctions, it can be disassembled and replaced individually without disassembling the entire device, greatly simplifying the maintenance process and reducing maintenance costs.

[0035] To ensure stable operation of the device in various industrial environments, all components have undergone appropriate protective treatment. The housing of pressure transmitter 3 adopts an explosion-proof design with a protection level of no less than IP65, which can adapt to dusty and humid industrial environments and prevent the risk of explosion caused by gas leaks. The housing of digital display 4 is made of flame-retardant ABS material with a waterproof sealing ring on the surface, achieving a protection level of IP65, which can effectively prevent liquids and dust from entering the interior and affecting the circuit operation. The surfaces of solenoid valve 5 and cylinder 7 are galvanized or painted, improving their rust and corrosion resistance and extending their service life. All electrical component wiring is laid in conduit made of galvanized steel pipe, fixed to brackets or walls, to avoid mechanical damage or corrosion from the external environment.

[0036] This device is suitable not only for newly built gas pipelines but also for upgrading existing ones. It achieves automatic pressurization through simple installation and connection, eliminating the need for large-scale modifications to existing pipelines and significantly reducing renovation costs. It has broad application prospects in various fields such as metallurgy, chemical engineering, and urban gas supply. It can effectively prevent safety accidents caused by negative pressure in gas pipelines, improve the safety and reliability of gas pipeline operations, reduce production interruptions due to abnormal pressure, and create greater economic benefits for enterprises. Furthermore, the device operates without continuous manual supervision, reducing labor costs, improving work efficiency, and providing strong support for the intelligent management of gas pipelines.

[0037] In practical applications, the components of the device can be flexibly adjusted according to the specific diameter and conveying pressure of the gas pipeline 1 and the site layout. For example, for a large-diameter gas pipeline 1, a pneumatic butterfly valve 6 and a nitrogen pipeline 2 with a larger nominal diameter can be selected to ensure that the pressurization flow meets the requirements; for sites with significant vibration, a shock-absorbing pad can be added between the cylinder 7 and the support to reduce the impact of vibration on the connection between the cylinder 7 and the pneumatic butterfly valve 6; for areas with low ambient temperatures, a gas source pipe 8 and seals made of low-temperature resistant materials can be selected to prevent the pipeline from becoming brittle and breaking due to low temperatures. Through these targeted adjustments, the device can better adapt to different application scenarios, ensuring that it always maintains stable and reliable operating performance.

[0038] As is known from common technical knowledge, this utility model can be implemented through other embodiments that do not depart from its spirit or essential characteristics. Therefore, the disclosed embodiments described above are merely illustrative in all respects and are not the only ones. All modifications within the scope of this utility model or its equivalents are included in this utility model.

Claims

1. An automatic pressurization device for preventing negative pressure in gas pipelines, characterized in that, It includes a gas pipeline (1), a nitrogen pipeline (2), a pressure transmitter (3), a digital display (4), a solenoid valve (5), a switching power supply (9), a pneumatic butterfly valve (6), a cylinder (7), and a gas source pipe (8); The pressure transmitter (3) is fixedly installed on the pipe body of the gas pipeline (1), and the signal output terminal of the pressure transmitter (3) is connected to the signal input terminal of the digital display (4) through a wire. The nitrogen pipeline (2) is connected in series with a manual pressurization valve and a pneumatic butterfly valve (6). The valve stem of the pneumatic butterfly valve (6) is fixedly connected to the output shaft of the cylinder (7) through a coupling. The switching power supply (9) is a DC 24V power supply. The 24V+ terminal of the switching power supply (9) is connected to two paths via wires. One path is connected to the power input terminal of the digital display (4), and the other path is connected to the 24V+ terminal of the solenoid valve (5) through the built-in open contact interface of the digital display (4). The 24V- terminal of the solenoid valve (5) is connected to the 24V- terminal of the switching power supply (9). The air inlet of the solenoid valve (5) is used to connect to an external air source, and the air outlet of the solenoid valve (5) is sealed to the control air circuit interface of the cylinder (7) through the air source pipe (8).

2. The automatic pressurization device for preventing negative pressure in gas pipelines according to claim 1, characterized in that, The signal output terminal of the pressure transmitter (3) is provided with a signal input IN+ terminal and a signal input IN- terminal. The signal input IN+ terminal and the signal input IN- terminal are fixedly connected to the signal input terminal of the digital display (4) one-to-one by wires.

3. The automatic pressurization device for preventing negative pressure in gas pipelines according to claim 1, characterized in that, The manual pressurizing valve and the pneumatic butterfly valve (6) are connected in series along the nitrogen delivery direction on the nitrogen pipeline (2).

4. The automatic pressurization device for preventing negative pressure in gas pipelines according to claim 1, characterized in that, The gas source pipe (8) is a flexible sealed pipe.

5. The automatic pressurization device for preventing negative pressure in gas pipelines according to claim 1, characterized in that, The solenoid valve (5) is a two-position five-way solenoid valve (5).

6. An automatic pressurization device for preventing negative pressure in gas pipelines according to any one of claims 1 to 5, characterized in that, The digital display (4) is a pressure display and interlocking control component with opening and closing point control function.

7. An automatic pressurization device for preventing negative pressure in gas pipelines according to any one of claims 1 to 5, characterized in that, The air passage interface of the cylinder (7) is sealed to an external air source through the air source pipe (8).

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