Nitrogen sealing system capable of saving nitrogen consumption

Abstract

The application relates to a nitrogen sealing system saving the nitrogen consumption, belonging to the technical field of nitrogen sealing. Each reaction storage tank is connected with a tail gas main through branch pipelines, and adjusting valves are arranged on the branch pipelines. One end of the tail gas main is connected with a high-pressure nitrogen source, and the other end is connected with a nitrogen sealing tank gas inlet end through an explosion-proof valve and a connecting pipe. The nitrogen sealing tank gas outlet end is connected with the tail gas main through a reflux pipe. A nitrogen sealing condenser is connected in series on the tail gas main. The application realizes the complementation of tail gas of devices in the same process system, reduces the nitrogen consumption and cost, and improves the system safety and reliability.

Description

Technical Field

[0001] This application belongs to the field of nitrogen sealing technology, specifically relating to a nitrogen sealing system that saves nitrogen usage. Background Technology

[0002] Nitrogen sealing is a process of filling the top gaseous space of a storage container or reactor with nitrogen gas to protect the internal materials and prevent oxidation, corrosion, polymerization, degradation, and the formation of explosive mixtures caused by the presence of air. In chemical enterprises, especially fine chemical enterprises, nitrogen sealing systems serve a dual purpose: first, by sealing the gaseous components inside the tank or reactor with an inert gas to isolate them from air, the system keeps the gaseous components below the lower explosive limit, achieving intrinsic explosion protection; second, by increasing the equilibrium pressure of the internal gaseous space, the system reduces the volatilization of the medium, preventing material oxidation or contamination and achieving energy conservation and emission reduction.

[0003] Traditional nitrogen sealing systems for storage tanks mainly consist of a nitrogen supply valve, a single-exit valve, and a breather valve. Their operating mode is as follows: when liquid enters the storage tank, causing the liquid level to rise, the gas phase volume to decrease, and the pressure to rise to the set value of the single-exit valve, the single-exit valve opens to release nitrogen gas, and closes after the pressure drops to the set point; when liquid exits the storage tank, causing the liquid level to drop, the gas phase volume to increase, and the pressure to decrease, the nitrogen supply valve opens to inject nitrogen gas, and closes after the pressure rises to the set point.

[0004] However, traditional nitrogen blanketing systems have many drawbacks: First, high-pressure nitrogen needs to be introduced to each point of use, and each point of use needs to be equipped with a nitrogen supply valve and a breather valve, which significantly increases nitrogen consumption and investment, operation, and maintenance costs; Second, high-pressure nitrogen leaks can easily cause personnel asphyxiation, requiring nitrogen content detection devices to be installed at each point of use, further increasing costs; Third, most points of use are atmospheric pressure vessels, and to prevent overpressure rupture, safety valves or rupture discs or other safety relief devices need to be installed at each point of use, further increasing investment costs; Fourth, it is impossible to guarantee buffer time at each point of use during peak nitrogen usage, which greatly limits the scope of application. Utility Model Content

[0005] The technical problem to be solved by this application is to overcome the shortcomings of the prior art and provide a nitrogen sealing system that saves nitrogen consumption. This application realizes the complementarity of exhaust gas of equipment in the same process system, reduces nitrogen consumption and cost, and improves system safety and reliability.

[0006] The technical solution adopted by this application to solve its existing problems is: A nitrogen sealing system that saves nitrogen usage, wherein each nitrogen sealing unit is connected to the exhaust gas main pipe through branch pipes, and the branch pipes are equipped with regulating valves.

[0007] One end of the exhaust manifold is connected to a high-pressure nitrogen source, and the other end is connected to the inlet of the nitrogen sealing tank via an explosion-proof valve and a connecting pipe.

[0008] The exhaust end of the nitrogen-sealed tank is connected to the exhaust manifold via a return pipe, and a nitrogen-sealed condenser is connected in series on the exhaust manifold.

[0009] Furthermore, an air extraction device is connected in series on the return pipe.

[0010] Furthermore, the return pipe is connected to the high-pressure nitrogen supply pipeline and the exhaust gas main pipe via a three-way valve.

[0011] Furthermore, the two outlets of the explosion-proof valve are respectively connected to the connecting pipe and the pressure relief pipe.

[0012] When the inlet pressure of the explosion-proof valve is lower than the threshold, the exhaust gas main pipe is connected to the connecting pipe through the explosion-proof valve.

[0013] When the inlet pressure of the explosion-proof valve is higher than the threshold, the exhaust gas main pipe is connected to the pressure relief pipe through the explosion-proof valve.

[0014] Furthermore, an exhaust gas treatment pipeline is connected through the connecting pipe, and both the connecting pipe and the exhaust gas treatment pipeline are equipped with shut-off valves.

[0015] Furthermore, the regulating valve includes a first valve body, with a first air pipe and a second air pipe respectively passing through both ends of the first valve body. A slide tube is slidably provided inside the first valve body, and a partition is fixed at the center position inside the slide tube. A first spring and a second spring are respectively provided on both sides of the partition. Under the push of the first spring and the second spring, the slide tube is located at the axial center position of the first valve body.

[0016] The first valve body has a first through hole and a second through hole on its side wall. The first through hole and the second through hole are arranged opposite to each other on both sides of the center of the first valve body. When the slide tube is located at the center of the first valve body, the slide tube simultaneously blocks the first through hole and the second through hole. The first through hole is located between the partition and the second air pipe, and the second through hole is located between the partition and the first air pipe.

[0017] The first valve body is provided with a first bypass pipe that connects the first through hole to the first air pipe. The first bypass pipe is provided with a first one-way valve, and the flow direction of the first one-way valve is from the first through hole to the first air pipe.

[0018] The first valve body is provided with a second bypass pipe that connects the second through hole to the second air pipe. The second bypass pipe is provided with a second one-way valve, and the flow direction of the second one-way valve is from the second through hole to the second air pipe.

[0019] The first and second tracheas are connected to the branch pipes, with the first trachea being close to the nitrogen sealing unit.

[0020] Furthermore, the explosion-proof valve includes a second valve body, on the side wall of which a third through hole and a fourth through hole are arranged at intervals along its axial direction. The second valve body is slidably provided with a first piston and a second piston arranged at intervals. The first piston and the second piston are fixedly connected by a slide rod, one end of which extends to the outside of the second valve body.

[0021] The slide rod has an air chamber inside, and the opening of the air chamber is located at the end of the slide rod outside the second valve body. The air chamber is connected to the exhaust gas main pipe. The slide rod has an air outlet that is connected to the air chamber. The air outlet is located between the first piston and the second piston.

[0022] The second piston is provided with a third spring at the end opposite to the first piston. The fourth through hole is arranged corresponding to the first piston, the third through hole is arranged corresponding to the second piston, the fourth through hole is connected to the connecting pipe, and the third through hole is connected to the pressure relief pipe.

[0023] Under the push of the third spring, the axial end of the first piston abuts against the second valve body, the second piston seals the third through hole, and the vent hole connects with the fourth through hole to condense.

[0024] When the internal air pressure of the exhaust manifold reaches the threshold, the third spring is compressed, the first piston seals the fourth through hole, and the exhaust port is connected to the third through hole.

[0025] Furthermore, a pressure plate is slidably provided inside the second valve body, and the two ends of the third spring abut against the pressure plate and the second piston, respectively.

[0026] The second valve body has a threaded hole on the end face opposite to the pressure plate, and a pressure regulating block is threaded inside the threaded hole, which abuts against the pressure plate.

[0027] Compared with the prior art, the beneficial effects of this application are as follows: (1) The same process system shares a nitrogen sealing system. The equipment exhaust gas is complemented through the main pipe. Only a small amount of nitrogen is added when the overall system pressure is insufficient, which greatly reduces nitrogen consumption. (2) There is no need to install nitrogen supply valves, breathing valves, nitrogen detection devices and safety relief devices at each point of use. Only one centralized equipment is needed, which significantly reduces the cost of equipment procurement, installation and subsequent maintenance. (3) Reduce the number of high-pressure nitrogen delivery nodes and usage points to lower the risk of leakage; centrally install overpressure relief devices to make safety management more efficient; (4) Through the tail gas complementarity mechanism and automated pressure control, the system pressure is kept stable during peak nitrogen usage, expanding the application range and making it suitable for the use and storage of flammable, explosive, toxic and corrosive substances.

[0028] (5) The regulating valve and explosion-proof valve adopt the principle of pure mechanical pressure balance, without relying on electrical signals and sensors. This completely solves the problem of untimely pressure regulation caused by electrical signal delay or sensor damage, ensuring that the system can respond quickly to pressure changes under various working conditions and improve the stability and reliability of system regulation. Attached Figure Description

[0029] The present application will be further described below with reference to the accompanying drawings and embodiments.

[0030] Figure 1 This is a diagram of a nitrogen sealing system that saves nitrogen usage according to this application. Figure 2 This is a structural diagram of a regulating valve in a nitrogen sealing system that saves nitrogen usage, as described in this application. Figure 3 This is a cross-sectional view of the control valve. Figure 4 This application presents a first structural diagram of an explosion-proof valve in a nitrogen sealing system that saves nitrogen usage. Figure 5 This application presents a diagram of the second mechanism of an explosion-proof valve in a nitrogen sealing system that saves nitrogen usage. Figure 6 This is the first sectional view of the explosion-proof valve. Figure 7 This is the second sectional view of the explosion-proof valve.

[0031] In the diagram: 1-Nitrogen sealing unit, 2-Branch pipe, 3-Regulating valve, 301-First valve body, 302-First gas pipe, 303-Second gas pipe, 304-First through hole, 305-Second through hole, 306-First spring, 307-Second spring, 308-Slide pipe, 309-Baffle plate, 3010-First bypass pipe, 3011-First check valve, 3012-Second bypass pipe, 3013-Second check valve. 4-Exhaust gas main pipe, 5-Explosion-proof valve, 501-Second valve body, 502-Third through hole, 503-Fourth through hole, 504-Pressure regulating block, 505-Pressure plate, 506-Third spring, 507-Stop ring, 508-Gas chamber, 509-Gas outlet, 5010-Slide rod, 5011-First piston, 5012-Second piston, 6-Connecting pipe, 7-Nitrogen sealing tank, 8-Nitrogen sealing condenser, 9-Return pipe, 10-Extraction device, 11-Three-way valve, 12-High-pressure nitrogen source, 13-Pressure relief pipe. Detailed Implementation

[0032] The attached figure shows a preferred embodiment of this nitrogen sealing system that saves nitrogen usage. The following is a more detailed description of this application in conjunction with the attached figure.

[0033] A nitrogen sealing system that saves nitrogen usage, wherein each nitrogen sealing unit 1 is connected to the exhaust gas main pipe 4 through a branch pipe 2, and a regulating valve 3 is provided on the branch pipe 2.

[0034] One end of the exhaust manifold 4 is connected to the high-pressure nitrogen source 8, and the other end is connected to the inlet of the nitrogen sealing tank 7 through the explosion-proof valve 5 and the connecting pipe 6.

[0035] The exhaust end of the nitrogen-sealing tank 7 is connected to the exhaust manifold 4 via a return pipe 9. The return pipe 9 is connected to the high-pressure nitrogen source 12 supply line and the exhaust manifold 4 via a three-way valve 11. A suction device 10 is connected in series on the return pipe 9 to promote nitrogen flow within the system. A nitrogen-sealing condenser 8 is connected in series on the exhaust manifold 4. The nitrogen-sealing condenser 8 is located at the front end of the nitrogen-sealing tank 7. The gas inside the exhaust manifold 4 is cooled by the nitrogen-sealing condenser 8 before flowing into the nitrogen-sealing tank 7.

[0036] When the inlet pressure of the explosion-proof valve 5 is lower than the threshold, the exhaust gas main pipe 4 is connected to the connecting pipe 6 through the explosion-proof valve 5. When the inlet pressure of the explosion-proof valve 5 is higher than the threshold, the exhaust gas main pipe 4 is connected to the pressure relief pipe 13 through the explosion-proof valve 5.

[0037] The connecting pipe 6 is connected to an exhaust gas treatment pipeline, and both the connecting pipe 6 and the exhaust gas treatment pipeline are equipped with shut-off valves.

[0038] The working process of this system is as follows: S01, Initial Startup Phase: Nitrogen is introduced into the nitrogen sealing system through the high-pressure nitrogen source 12 until the pressure sensors on the exhaust gas main pipe 4 and each branch pipe 2 detect that the system pressure has reached the set constant value, then the nitrogen supply stops and the system enters standby mode. S02, Pressure Increase Condition: When the pressure rises due to the feeding of nitrogen sealing unit 1 or the expansion of the heated gas phase space, the exhaust gas discharged from the equipment enters the exhaust gas main pipe 4 through branch pipe 2. If the pressure in the exhaust gas main pipe 4 does not exceed the upper limit setting value, this part of the exhaust gas directly replenishes the nitrogen sealing unit 1 with lower pressure in the system to achieve exhaust gas complementarity; if the pressure in the exhaust gas main pipe 4 exceeds the upper limit setting value, the pressure sensor sends a signal to the connecting pipe 6 and the shut-off valves on the exhaust gas treatment pipeline to adjust the opening and closing mode of each shut-off valve, discharging the excess exhaust gas into the downstream exhaust gas treatment system until the pressure drops to the normal range and the regulating valve closes. S03, Pressure Reduction Condition: When the nitrogen sealing unit 1 discharges material or is cooled, causing the gas phase space to contract and the pressure to decrease, it is preferentially supplemented by the exhaust gas discharged from other equipment in the exhaust gas main pipe 4. If the pressure in the exhaust gas main pipe 4 is still lower than the lower limit setting value, the pressure sensor triggers the three-way valve 11 to adjust the switching mode, and the high-pressure nitrogen source 12 injects nitrogen into the system. When the pressure rises to the upper limit setting value, the switching mode of the three-way valve 11 changes. S04. Emergency Fault Condition: If a system fault causes the system pressure to rise continuously and exceed the burst pressure setting, the explosion-proof valve 5 will open instantly and release pressure through the pressure relief pipe 13 to control the system pressure within a safe range and prevent equipment from being damaged by overpressure.

[0039] In this embodiment, through the centralized nitrogen sealing design and tail gas complementarity mechanism of the same process system, the nitrogen replenishment amount is only 10%-20% of that of the traditional system, the equipment investment cost is reduced by more than 40%, and the nitrogen leakage risk points are reduced by more than 80%, which significantly improves the economy and safety of the system.

[0040] To reduce the number of valve assemblies and avoid untimely pressure regulation caused by electrical signal delays or sensor malfunctions, this embodiment designs the regulating valve 3 and the explosion-proof valve 5 in a mechanical form. Automatic intake and exhaust, as well as gas path changes, are regulated through pressure balance, making the regulation more reliable. Specifically, as follows: The regulating valve 3 includes a first valve body 301, with a first air pipe 302 and a second air pipe 303 respectively passing through both ends of the first valve body 301. A slide tube 308 is slidably provided inside the first valve body 301, and a partition 309 is fixed at the center of the slide tube 308. A first spring 306 and a second spring 307 are respectively provided on both sides of the partition 309. Under the push of the first spring 306 and the second spring 307, the slide tube 308 is located at the axial center of the first valve body 301.

[0041] The first valve body 301 has a first through hole 304 and a second through hole 305 on its side wall. The first through hole 304 and the second through hole 305 are arranged opposite to each other on both sides of the center of the first valve body 301. When the slide tube 308 is located at the center of the first valve body 301, the slide tube 308 simultaneously blocks the first through hole 304 and the second through hole 305. The first through hole 304 is located between the partition plate 309 and the second air pipe 303, and the second through hole 305 is located between the partition plate 309 and the first air pipe 302.

[0042] The first valve body 301 is provided with a first bypass pipe 3010 that connects the first through hole 304 and the first air pipe 302. The first bypass pipe 3010 is provided with a first one-way valve 3011, and the flow direction of the first one-way valve 3011 is from the first through hole 304 to the first air pipe 302.

[0043] The first valve body 301 is provided with a second bypass pipe 3012 that connects the second through hole 305 and the second air pipe 303. The second bypass pipe 3012 is provided with a second one-way valve 3013, and the flow direction of the second one-way valve 3013 is from the second through hole 305 to the second air pipe 303.

[0044] The first trachea 302 and the second trachea 303 are connected to the branch pipe 2, with the first trachea 302 being close to the nitrogen sealing unit 1.

[0045] The explosion-proof valve 5 includes a second valve body 501. The side wall of the second valve body 501 is provided with a third through hole 502 and a fourth through hole 503 arranged at intervals along its axial direction. The second valve body 501 is slidably provided with a first piston 5011 and a second piston 5012 arranged at intervals. The first piston 5011 and the second piston 5012 are fixedly connected by a slide rod 5010, one end of which extends to the outside of the second valve body 501.

[0046] The slide rod 5010 has an air chamber 508 inside. The open end of the air chamber 508 is located at the end of the slide rod 5010 outside the second valve body 501. The air chamber 508 is connected to the exhaust gas main pipe 4. The slide rod 5010 has an air outlet 509 that is connected to the air chamber 508. The air outlet 509 is located between the first piston 5011 and the second piston 5012.

[0047] The second piston 5012 is provided with a third spring 506 at the end opposite to the first piston 5011. The fourth through hole 503 is arranged corresponding to the first piston 5011, and the third through hole 502 is arranged corresponding to the second piston 5012. The fourth through hole 503 is connected to the connecting pipe 6, and the third through hole 502 is connected to the pressure relief pipe 13.

[0048] Under the push of the third spring 506, the axial end of the first piston 5011 abuts against the second valve body 501, the second piston 5012 seals the third through hole 502, and the vent 509 and the fourth through hole 503 are connected to condense. When the internal air pressure of the exhaust manifold 4 reaches the threshold, the third spring 506 is compressed, the first piston 5011 seals the fourth through hole 503, and the exhaust port 509 is connected to the third through hole 502.

[0049] The second valve body 501 has a pressure plate 505 slidingly disposed inside, and the two ends of the third spring 506 abut against the pressure plate 505 and the second piston 5012 respectively. The second valve body 501 has a threaded hole on the end face opposite to the pressure plate 505. A pressure regulating block 504 is threadedly connected inside the threaded hole, and the pressure regulating block 504 abuts against the pressure plate 505.

[0050] When the system pressure exceeds the threshold, the explosion-proof valve 5 releases pressure, and the fourth through hole 503 connected to the connecting pipe 6 is blocked. Pressure exceeding the threshold will not enter the interior of the connecting pipe 6, ensuring the safe operation of the connecting pipe 6 and subsequent connected equipment.

[0051] The regulating valve 3 is a mechanical structure that achieves automatic intake and exhaust and air path regulation through pressure balance. Its core relies on the axial movement of the slide tube inside the first valve body, combined with the spring thrust and the one-way flow characteristic of the check valve to complete its work. Specifically, it has the following two working conditions: 1. Pressure Increase Condition of Nitrogen Sealing Unit 1: When the pressure of nitrogen sealing unit 1 increases due to the expansion of the gas phase space caused by feeding or heating, the pressure in the first gas pipe 302 near nitrogen sealing unit 1 increases accordingly. This pressure pushes the slide tube 308 to move axially towards the second gas pipe 303, compressing the second spring 307. During this process, the slide tube 308 releases its blockage of the first through hole 304, while still maintaining its blockage of the second through hole 305. A portion of the high-pressure exhaust gas discharged from nitrogen sealing unit 1 enters the first bypass pipe 3010 through the first gas pipe 302 and the opened first through hole 304. Under the guidance of the first one-way valve 3011, it supplements the first gas pipe 302 side to participate in the gas circulation until the pressure of nitrogen sealing unit 1 and exhaust gas main pipe 4 tend to be balanced. The elastic force of the first spring 306 and the second spring 307 drives the slide tube 308 to reset, re-blocking the first through hole 304 and the second through hole 305, and the adjustment is completed.

[0052] 2. Pressure Reduction Condition of Nitrogen Sealing Unit 1: When the pressure of nitrogen sealing unit 1 decreases due to material discharge or cooling, causing the gas phase space to contract, the pressure in the first gas pipe 302 becomes lower than the pressure on the side of the second gas pipe 303. This pressure difference pushes the slide tube 308 towards the first gas pipe 302, compressing the first spring 306. At this time, the slide tube 308 releases its obstruction of the second through hole 305, while maintaining its obstruction of the first through hole 304. The gas in the exhaust manifold 4 enters the second bypass pipe 3012 through the second gas pipe 303 and the opened second through hole 305. Under the guidance of the second one-way valve 3013, the auxiliary gas path flows. Once the pressure of nitrogen sealing unit 1 returns to equilibrium, the spring force drives the slide tube 308 to reset and obstruct the second through hole 305, thus terminating the adjustment.

[0053] By responding to the tank pressure in real time through a mechanical structure, regulating valve 3 can precisely control the gas flow between the tank and the exhaust gas main. When the pressure of some tanks in the system increases and others decreases, the exhaust gas discharged from the high-pressure tank can be directly replenished to the low-pressure tank through regulating valve 3, realizing exhaust gas complementarity within the same process, reducing the start-up frequency of the high-pressure nitrogen source, and with the overall system design, the nitrogen replenishment amount is only 10%-20% of that of traditional systems.

[0054] The combined design of the first and second bypass pipes with the one-way valve not only avoids gas backflow interfering with the regulation accuracy, but also assists in the flow of gas when the pressure changes, improving regulation efficiency, while simplifying the valve group structure and reducing equipment maintenance costs.

[0055] The explosion-proof valve 5 is also a mechanical structure. It uses the spring force of the third spring 506 as an initial constraint and controls the piston movement through the balance between the exhaust manifold pressure and the spring force, thus switching the gas path between the connecting pipe 6 and the pressure relief pipe 13. Its core relies on the linkage structure of the first piston, the second piston, and the sliding rod, and it operates in three specific conditions: 1. Intake pressure below threshold condition: In the initial state, under the thrust of the third spring 506, the pressure plate 505 drives the second piston 5012 to move towards the first piston 5011, so that the axial end of the first piston 5011 abuts against the inner wall of the second valve body 501, and the second piston 5012 seals the third through hole 502 connected to the pressure relief pipe 13. At this time, the gas in the gas chamber 508 connected to the exhaust gas main pipe 4 in the slide rod 5010 is discharged through the gas outlet 509 and connects with the fourth through hole 503. The gas in the exhaust gas main pipe can flow through the explosion-proof valve 5 to the connecting pipe 6 and enter the nitrogen sealing tank 7 to complete the normal gas circuit circulation.

[0056] 2. Intake pressure exceeding the threshold condition: When the pressure in the exhaust manifold 4 rises to the set threshold, the pressure in the air chamber 508 increases synchronously. This pressure acts through the outlet 509 on the area between the first piston 5011 and the second piston 5012, generating a force that pushes the piston towards the third spring 506. This force overcomes the elasticity of the third spring 506, compressing the spring and causing the slide rod 5010 to move synchronously with the piston until the first piston 5011 seals the fourth through hole 503, and the second piston 5012 releases the seal on the third through hole 502. At this time, the outlet 509 and the third through hole 502 are connected, and the high-pressure gas in the exhaust manifold is discharged through the pressure relief pipe 13 until the pressure drops below the threshold. Then, the third spring 506 pushes the piston back to its original position, and the air passage returns to normal.

[0057] In addition, the position of the pressure plate 505 can be adjusted by rotating the pressure regulating block 504, thereby changing the initial compression of the third spring 506, so as to achieve flexible setting of the pressure threshold and adapt to different working conditions.

[0058] The embodiments of this application have been described in detail above with reference to the accompanying drawings. However, this application is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of this application.

Claims

1. A nitrogen sealing system that saves nitrogen consumption, characterized in that: Each nitrogen sealing unit (1) is connected to the exhaust gas main pipe (4) through a branch pipe (2), and a regulating valve (3) is provided on the branch pipe (2). One end of the exhaust manifold (4) is connected to the high-pressure nitrogen source (12), and the other end is connected to the inlet of the nitrogen sealing tank (7) through the explosion-proof valve (5) and the connecting pipe (6); The exhaust end of the nitrogen sealing tank (7) is connected to the exhaust manifold (4) via a return pipe (9); A nitrogen-sealed condenser (8) is connected in series on the exhaust manifold (4).

2. The nitrogen sealing system for saving nitrogen usage according to claim 1, characterized in that: An air extraction device (10) is connected in series on the return pipe (9).

3. The nitrogen sealing system for saving nitrogen usage according to claim 1, characterized in that: The return pipe (9) is connected to the high-pressure nitrogen source (12) supply pipeline and the exhaust gas main pipe (4) via a three-way valve (11).

4. A nitrogen sealing system for saving nitrogen consumption according to claim 1, characterized in that: The two outlets of the explosion-proof valve (5) are respectively connected to the connecting pipe (6) and the pressure relief pipe (13); When the inlet pressure of the explosion-proof valve (5) is lower than the threshold, the exhaust gas main pipe (4) is connected to the connecting pipe (6) through the explosion-proof valve (5); When the intake pressure of the explosion-proof valve (5) is higher than the threshold, the exhaust gas main pipe (4) is connected to the pressure relief pipe (13) through the explosion-proof valve (5).

5. A nitrogen sealing system for saving nitrogen consumption according to any one of claims 1 to 4, characterized in that: The connecting pipe (6) is connected to a tail gas treatment pipeline, and both the connecting pipe (6) and the tail gas treatment pipeline are equipped with shut-off valves.

6. A nitrogen sealing system for saving nitrogen consumption according to any one of claims 1 to 4, characterized in that: The regulating valve (3) includes a first valve body (301), with a first air pipe (302) and a second air pipe (303) respectively connected through both ends of the first valve body (301). A slide tube (308) is slidably provided inside the first valve body (301), and a partition (309) is fixed at the center of the slide tube (308). A first spring (306) and a second spring (307) are respectively provided on both sides of the partition (309). Under the push of the first spring (306) and the second spring (307), the slide tube (308) is located at the axial center of the first valve body (301). The first valve body (301) has a first through hole (304) and a second through hole (305) on its side wall. The first through hole (304) and the second through hole (305) are arranged opposite to each other on both sides of the center of the first valve body (301). When the slide tube (308) is located at the center of the first valve body (301), the slide tube (308) simultaneously blocks the first through hole (304) and the second through hole (305). The first through hole (304) is located between the partition plate (309) and the second air pipe (303), and the second through hole (305) is located between the partition plate (309) and the first air pipe (302). The first valve body (301) is provided with a first bypass pipe (3010) that connects the first through hole (304) and the first air pipe (302) on the outside. The first bypass pipe (3010) is provided with a first one-way valve (3011). The flow direction of the first one-way valve (3011) is from the first through hole (304) to the first air pipe (302). The first valve body (301) is provided with a second bypass pipe (3012) that connects the second through hole (305) and the second air pipe (303) on the outside. The second bypass pipe (3012) is provided with a second one-way valve (3013). The flow direction of the second one-way valve (3013) is from the second through hole (305) to the second air pipe (303). The first trachea (302) and the second trachea (303) are connected to the branch pipe (2), and the first trachea (302) is close to the nitrogen sealing unit (1).

7. A nitrogen sealing system for saving nitrogen consumption according to any one of claims 1 to 4, characterized in that: The explosion-proof valve (5) includes a second valve body (501). The second valve body (501) has a third through hole (502) and a fourth through hole (503) arranged at intervals along its axial direction on its side wall. The second valve body (501) is slidably provided with a first piston (5011) and a second piston (5012) arranged at intervals. The first piston (5011) and the second piston (5012) are fixedly connected by a slide rod (5010). One end of the slide rod (5010) extends to the outside of the second valve body (501). The slide rod (5010) has an air chamber (508) inside. The opening of the air chamber (508) is located at the end of the slide rod (5010) outside the second valve body (501). The air chamber (508) is connected to the exhaust gas main pipe (4). The slide rod (5010) has an air outlet (509) that is connected to the air chamber (508). The air outlet (509) is located between the first piston (5011) and the second piston (5012). The second piston (5012) is provided with a third spring (506) at the end opposite to the first piston (5011), the fourth through hole (503) is arranged correspondingly to the first piston (5011), the third through hole (502) is arranged correspondingly to the second piston (5012), the fourth through hole (503) is connected through the connecting pipe (6), and the third through hole (502) is connected through the pressure relief pipe (13); Under the push of the third spring (506), the axial end of the first piston (5011) abuts against the second valve body (501), the second piston (5012) seals the third through hole (502), and the vent hole (509) and the fourth through hole (503) are connected to condense; When the internal air pressure of the exhaust manifold (4) reaches the threshold, the third spring (506) is compressed, the first piston (5011) seals the fourth through hole (503), and the exhaust hole (509) is connected to the third through hole (502).

8. A nitrogen sealing system for saving nitrogen usage according to claim 7, characterized in that: The second valve body (501) has a pressure plate (505) slidingly mounted inside, and the two ends of the third spring (506) abut against the pressure plate (505) and the second piston (5012) respectively. The second valve body (501) has a threaded hole on the end face opposite to the pressure plate (505), and a pressure regulating block (504) is threaded inside the threaded hole, which abuts against the pressure plate (505).

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