Nitrogen purging facility for preventing reverse flowing of acid gas
By using a wire mesh with a porosity of 80% and a ramp structure to capture sulfuric acid droplets in a nitrogen purging system, combined with a support mesh and grating plate, the problem of sulfuric acid droplet corrosion of the check valve was solved, achieving effective interception and efficient backflow, extending valve life, and reducing maintenance costs.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2025-07-29
- Publication Date
- 2026-04-17
AI Technical Summary
In existing nitrogen purging systems, small droplets carried in the residual acid gas during sulfuric acid transport can easily corrode check valve components, leading to frequent valve failures, high maintenance costs, and reduced operational efficiency.
Small droplets are captured by a wire mesh with a porosity of 80%, and large droplets are refluxed by a sloping structure inside the tube shell. The wire mesh is supported by a support mesh and a grid plate to prevent deformation or detachment, simplifying the wire mesh replacement process. Acid gas is intercepted by both a check valve and a shut-off valve.
It effectively intercepts small droplets in acid gas, reduces valve corrosion, extends service life, lowers maintenance costs, shortens maintenance downtime, and improves system processing efficiency.
Smart Images
Figure CN224135688U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of dock facilities technology, specifically a nitrogen purging facility to prevent acid gas backflow. Background Technology
[0002] In sulfuric acid transportation operations at docks, sulfuric acid is a highly corrosive medium, making the safe operation and maintenance of its transportation pipeline system crucial. To prevent residual sulfuric acid in the pipeline after transportation from stagnating and evaporating to form acid gas (containing a large amount of sulfuric acid droplets), which could cause corrosion of the pipeline wall or react with air and create safety hazards, the industry commonly uses a nitrogen purging process—using a stream of nitrogen to forcibly remove residual sulfuric acid and acid gas from the pipeline, ensuring pipeline cleanliness.
[0003] In existing nitrogen purging systems, a dual-valve design of "check valve + shut-off valve" is typically used to prevent acid gas from backflowing into the nitrogen source system. The check valve automatically closes based on the pressure difference of the medium, preventing acid gas from flowing backward. The shut-off valve, on the other hand, is manually or automatically controlled to open or close the nitrogen purging path. Together, they form a double barrier, theoretically cutting off the acid gas backflow path. Some acid gas backflow prevention systems also include additional sensors to detect the presence of acid gas in the pipeline downstream of the shut-off valve in real time, facilitating timely leak detection and maintenance.
[0004] However, existing solutions have drawbacks in practical applications. The residual acid gas from sulfuric acid transportation carries a large number of small droplets, which are highly fluid and corrosive. These droplets can enter the check valve with the gas flow and adhere to the surfaces of the valve disc, valve seat, and spring. Due to continuous contact with sulfuric acid droplets, the inside of the check valve is prone to valve disc corrosion and aging of the sealing surface (such as swelling of rubber seals and corrosion of metal sealing surfaces), leading to frequent valve failures. Acid gas can further backflow into the stop valve with the droplets, shortening the replacement cycle, increasing maintenance costs, and affecting the efficiency of dock operations. Summary of the Invention
[0005] Therefore, the purpose of this utility model is to provide a nitrogen purging device to prevent acid gas backflow, so as to solve the technical problems mentioned in the background art.
[0006] To achieve the above objectives, this utility model provides the following technical solution: a nitrogen purging device to prevent acid gas backflow, comprising a check valve, a tube shell connected to the bottom of the check valve, and a drawer frame penetrating the outer surface of the tube shell, a wire mesh installed inside the drawer frame, and a grid plate connected to the top and bottom of the drawer frame via a support mesh, with a second bolt connecting the grid plate to the drawer frame; a sealing ring and a first bolt are respectively connected between the drawer frame and the tube shell.
[0007] By adopting the above technical solution, the wire mesh inside the tube shell serves as the core trapping component. Utilizing its 80% porosity, it intercepts and adsorbs small droplets carried in the acid gas through its porous structure without significantly hindering nitrogen flow. These small droplets then aggregate into larger droplets on the wire mesh surface. Under the influence of gravity and aided by the sloping structure at the bottom of the tube shell, the aggregated droplets flow back towards the sulfuric acid pipeline system. During nitrogen purging, the support mesh provides uniform support to the wire mesh, preventing deformation or detachment under the impact of the nitrogen flow. The grating plate further strengthens... To enhance support strength and prevent significant deformation of the support mesh and wire mesh due to long-term stress, ensuring that the wire mesh remains in an effective trapping position, the first bolt is removed during each inspection to stop the drawer frame from being locked. The drawer frame can then be pulled out to check the condition of the wire mesh. If the wire mesh is damaged, the second bolt, grating plate, and support mesh are removed in sequence, and then the wire mesh can be removed and replaced. After replacing the wire mesh, the support mesh, grating plate, and second bolt are reinstalled one by one to lock the wire mesh. The entire process does not require disassembling the piping system, significantly reducing maintenance downtime.
[0008] Furthermore, the check valve is connected to the pipe shell by threads or flanges, and a shut-off valve is connected to the top of the check valve via an intermediate pipe.
[0009] By adopting the above technical solution, the remaining acid gas without dripping will be intercepted by both the check valve and the shut-off valve, preventing acid gas from backflowing into the nitrogen purging system. The shut-off valve can be manual or electric. When purging is required, the shut-off valve is opened, and after purging is completed, the shut-off valve is closed.
[0010] Furthermore, the drawer frame is detachably connected to the tube shell and the sealing ring, and the wire mesh, support mesh and grid plate are all detachably connected to the drawer frame.
[0011] By adopting the above technical solution, the first bolt is removed during each inspection to stop the drawer frame from being stopped. Then the drawer frame can be pulled out to check the condition of the wire mesh. If the wire mesh is damaged, the second bolt, the grating plate, and the support mesh are removed in sequence, and then the wire mesh can be removed and replaced. After the wire mesh is replaced, the support mesh, the grating plate, and the second bolt are reinstalled one by one to stop the wire mesh. The whole process does not require disassembling the piping system, which greatly shortens the maintenance downtime.
[0012] Furthermore, the wire mesh is made of polytetrafluoroethylene material, and the porosity of the wire mesh is 80%.
[0013] By adopting the above technical solution, with a porosity of 80%, small droplets entrained in acid gas are intercepted and adsorbed through a porous structure without significantly hindering the flow of nitrogen gas, causing the small droplets to aggregate into large droplets on the surface of the wire mesh 6.
[0014] Furthermore, the mesh size of the support mesh is 20 to 30 meshes.
[0015] By adopting the above technical solution, during the nitrogen purging process, the support mesh provides uniform support to the wire mesh, preventing the wire mesh from deforming or falling off under the impact of the nitrogen flow, while also reducing the resistance to the nitrogen.
[0016] Furthermore, the upper and lower parts of the inner surface of the tube shell are both sloped.
[0017] By adopting the above technical solution, large droplets flow back towards the sulfuric acid pipeline system under the action of gravity and with the help of the sloping structure at the bottom of the tube shell.
[0018] Furthermore, a polytetrafluoroethylene coating is provided between the contact surfaces of the drawer frame and the tube shell.
[0019] By adopting the above technical solutions, the frictional resistance between the drawer frame and the tube shell can be reduced when the drawer is pulled out, while the acid corrosion resistance of the contact surface can be enhanced, further improving the long-term stability of the structure.
[0020] Furthermore, both the first and second bolts are provided with double washers on their exteriors, and the double washers are a flat washer and a spring washer, respectively.
[0021] By adopting the above technical solution, in the double-washer design of the first and second bolts, the flat washer increases the force-bearing area to prevent component deformation, and the spring washer prevents the bolt from loosening during nitrogen purging vibration through elastic preload, ensuring connection sealing and structural stability.
[0022] Furthermore, the tube shell is made of 316L stainless steel or 2507 duplex stainless steel.
[0023] By adopting the above technical solutions, the 316L stainless steel tube shell can meet normal use, but it is still prone to corrosion in extreme environments, such as high temperature. Using 2507 duplex stainless steel, its structural strength and corrosion resistance are stronger than 316L stainless steel, and it can withstand harsher environments, making it easier to use for a long time.
[0024] Furthermore, the drawer frame, support mesh, and grille are all made of 316L stainless steel, and the sealing ring is made of FFKM material.
[0025] By adopting the above technical solution, the drawer frame, support mesh, and grille are made of 316L stainless steel, and the sealing ring is made of FFKM material. The overall structure has excellent resistance to sulfuric acid corrosion and can withstand the erosion of acid gas and droplets for a long time.
[0026] In summary, the present invention has the following main advantages:
[0027] 1. This utility model, through the setting of the wire mesh, can effectively capture sulfuric acid droplets carried in acid gas: the wire mesh has a porosity of 80%, which can reduce the resistance caused by nitrogen purging, and its porous structure can intercept and adsorb small droplets in acid gas, so that the droplets gather into large droplets and flow back by gravity, reducing the amount of sulfuric acid droplets entering the check valve. This reduces the corrosion and sealing failure of valve discs, valve seats and other components due to continuous contact with sulfuric acid, significantly extending the service life of check valves and shut-off valves, reducing the risk of acid gas backflow; it also facilitates the interception of droplets in acid gas, thereby extending the service life of check valves.
[0028] 2. This utility model, through the setting of the tube shell, can be installed vertically or at an angle to the ground. Combined with the sloping structure inside the tube shell, gravity can be used to allow droplets to fall naturally along the surface of the wire mesh and support mesh. This can efficiently guide the collected droplets back, avoid droplets from accumulating inside the tube shell, further reduce the corrosion of the tube shell and subsequent valves by sulfuric acid residue, improve the droplet treatment efficiency of the overall system, and reduce the possibility of sulfuric acid accumulating inside the tube shell and wire mesh.
[0029] 3. This utility model, through the arrangement of a drawer frame, support mesh, grid plate, and sealing ring, allows the drawer frame to be stopped by removing the first bolt during each inspection. The drawer frame can then be pulled out to check the condition of the wire mesh. If the wire mesh is damaged, the second bolt, grid plate, and support mesh are removed in sequence, allowing the wire mesh to be replaced. After replacing the wire mesh, the support mesh, grid plate, and second bolt are reinstalled one by one. The support mesh stops the wire mesh, preventing it from falling off during nitrogen purging. Simultaneously, the grid plate provides support for the support mesh and wire mesh, preventing significant deformation. This facilitates the replacement of damaged wire mesh, and the wire mesh exhibits good structural stability during operation. Attached Figure Description
[0030] Figure 1 This is a schematic diagram of the structure of this utility model;
[0031] Figure 2 This is a schematic diagram of the side sectional structure of the tube shell of this utility model;
[0032] Figure 3 This is a schematic diagram of the exploded structure of the shell of this utility model;
[0033] Figure 4 This is a bottom view of the drawer frame structure of this utility model;
[0034] Figure 5 This is a schematic diagram of the exploded structure of the drawer rack of this utility model.
[0035] In the diagram: 1. Check valve; 2. Intermediate pipe; 3. Gate valve; 4. Pipe shell; 5. Drawer rack; 6. Wire mesh; 7. Support mesh; 8. Grating plate; 9. Sealing ring; 10. First bolt; 11. Second bolt. Detailed Implementation
[0036] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.
[0037] The embodiments of this utility model will be described below based on its overall structure.
[0038] Example 1
[0039] A nitrogen purging device to prevent acid gas backflow, such as Figures 1-5 As shown, the system includes a check valve 1, with a housing 4 connected to its bottom. The upper and lower interior surfaces of the housing 4 are sloped. A drawer frame 5 runs through the outer surface of the housing 4, and a wire mesh 6, made of polytetrafluoroethylene (PTFE), is installed inside the drawer frame 5. The wire mesh 6 has a porosity of 80%. As the core trapping component, the wire mesh 6, with its 80% porosity, intercepts and adsorbs small droplets carried in the acid gas through its porous structure without significantly hindering nitrogen flow. These small droplets then aggregate into larger droplets on the surface of the wire mesh 6. Under the influence of gravity and aided by the sloped structure at the lower interior of the housing 4, the aggregated large droplets flow back towards the sulfuric acid pipeline system. A grid plate 8 is connected to the top and bottom of the drawer frame 5 via a support mesh 7. The support mesh 7 has a mesh size of 20 to 30, providing uniform support to the wire mesh 6 and preventing deformation or detachment under the impact of nitrogen flow. The grid plate 8 further strengthens the support and prevents the support mesh from... Due to long-term stress, wire mesh 6 undergoes significant deformation, ensuring that it remains in an effective trapping position. A second bolt 11 connects the grid plate 8 to the drawer frame 5. Wire mesh 6, support mesh 7, and grid plate 8 are all detachably connected to the drawer frame 5. A sealing ring 9 and a first bolt 10 connect the drawer frame 5 to the pipe shell 4. Both the first bolt 10 and the second bolt 11 have double washers on their exteriors: a flat washer and a spring washer. The drawer frame 5 is detachably connected to the pipe shell 4 and the sealing ring 9. During each inspection, the first bolt 10 is removed to stop the drawer frame 5 from being locked. The drawer frame 5 can then be pulled out to inspect the condition of the wire mesh 6. If the wire mesh 6 is damaged, the second bolt 11, grid plate 8, and support mesh 7 are removed sequentially, allowing the wire mesh 6 to be replaced. After replacing the wire mesh 6, the support mesh 7, grid plate 8, and second bolt 11 are reinstalled one by one to lock the wire mesh 6. The entire process does not require disassembling the piping system, significantly reducing maintenance downtime.
[0040] See Figure 1 In the above embodiment, the check valve 1 is connected to the shell 4 by a thread or flange. The top of the check valve 1 is connected to the shut-off valve 3 through the intermediate pipe 2. The remaining acid gas without dripping will be doubly intercepted by the check valve 1 and the shut-off valve 3 to prevent acid gas from backflowing into the nitrogen purging system. The shut-off valve 3 is manual or electric. When purging is required, the shut-off valve 3 is opened and closed after purging is completed.
[0041] Example 2
[0042] Based on the above embodiment one, in order to reduce wear during maintenance, the following settings are now implemented.
[0043] See Figures 2-5 In the above embodiments, a polytetrafluoroethylene coating is provided between the contact surfaces of the drawer frame 5 and the tube shell 4, which can reduce the frictional resistance between the drawer frame 5 and the tube shell 4 when the drawer frame 5 is pulled out, while enhancing the acid corrosion resistance of the contact surfaces and further improving the long-term stability of the structure.
[0044] Example 3
[0045] Based on the above embodiment one, the following settings are now implemented to extend the service life of the structure.
[0046] See Figures 1-5 In the above embodiments, the tube shell 4 is made of 316L stainless steel or 2507 duplex stainless steel, the drawer frame 5, the support mesh 7 and the grating plate 8 are all made of 316L stainless steel, and the sealing ring 9 is made of FFKM material. The tube shell 4 is made of 316L stainless steel or 2507 duplex stainless steel, the drawer frame 5, the support mesh 7 and the grating plate 8 are made of 316L stainless steel, and the sealing ring 9 is made of FFKM material. The overall structure has excellent resistance to sulfuric acid corrosion and can withstand the erosion of acid gas and droplets for a long time.
[0047] The implementation principle of this utility model is as follows: First, the pipe shell 4 is connected to the sulfuric acid pipeline system via a flange or thread, and the pipe shell 4 is perpendicular or inclined to the ground. The sulfuric acid remaining in the sulfuric acid pipeline system will volatilize to form acid gas containing sulfuric acid droplets. The acid gas flows with the airflow towards the check valve 1 and first enters the interior of the pipe shell 4. At this time, the wire mesh 6 inside the pipe shell 4 acts as the core capturing component. With a porosity of 80%, it intercepts and adsorbs small droplets carried in the acid gas through a porous structure without significantly hindering the flow of nitrogen gas. The small droplets are then aggregated into large droplets on the surface of the wire mesh 6. Under the action of gravity, the aggregated large droplets flow back towards the sulfuric acid pipeline system with the help of the sloping structure at the bottom of the inside of the pipe shell 4. The remaining acid gas without droplets is intercepted by both the check valve 1 and the shut-off valve 3 to prevent the acid gas from backflowing into the nitrogen purging system. The shut-off valve 3 is manual or electric. When purging is required, the shut-off valve 3 is opened, and after purging is completed, the shut-off valve 3 is closed.
[0048] During nitrogen purging, the support mesh 7 provides uniform support to the wire mesh 6, preventing the wire mesh 6 from deforming or falling off under the impact of nitrogen flow. The grating plate 8 further strengthens the support, preventing the support mesh 7 and wire mesh 6 from undergoing large deformation due to long-term stress, ensuring that the wire mesh 6 is always in an effective trapping position. Meanwhile, the tube shell 4 is made of 316L stainless steel or 2507 duplex stainless steel, the drawer frame 5, the support mesh 7, and the grating plate 8 are made of 316L stainless steel, and the sealing ring 9 is made of FFKM material. The overall structure has excellent resistance to sulfuric acid corrosion and can withstand the erosion of acid gas and droplets for a long time.
[0049] During each inspection, the first bolt 10 is removed to stop the drawer frame 5 from being locked. Then, the drawer frame 5 can be pulled out to check the condition of the wire mesh 6. If the wire mesh 6 is damaged, the second bolt 11, the grid plate 8, and the support mesh 7 are removed in sequence, and then the wire mesh 6 can be removed and replaced. After the wire mesh 6 is replaced, the support mesh 7, the grid plate 8, and the second bolt 11 are reinstalled one by one to lock the wire mesh 6. The whole process does not require disassembling the piping system, which greatly shortens maintenance downtime. In addition, in the double-waist design of the first bolt 10 and the second bolt 11, the flat washer increases the force-bearing area to prevent component deformation, and the spring washer prevents the bolt from loosening during the vibration of nitrogen purging through elastic preload, ensuring connection sealing and structural stability.
[0050] Although embodiments of the present invention have been shown and described, these specific embodiments are merely explanations of the present invention and are not intended to limit the invention. The specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. After reading this specification, those skilled in the art may make modifications, substitutions, and variations to the embodiments as needed without departing from the principles and spirit of the present invention, provided that such modifications, substitutions, and variations are within the scope of the claims of the present invention and are protected by patent law.
Claims
1. A nitrogen purging acid gas reverse string prevention facility comprising a check valve (1), characterized in that: The bottom of the check valve (1) is connected to a shell (4), and a drawer frame (5) runs through the outer surface of the shell (4). A wire mesh (6) is installed inside the drawer frame (5). The top and bottom of the drawer frame (5) are connected to a grid plate (8) through a support mesh (7). A second bolt (11) connects the grid plate (8) to the drawer frame (5). A sealing ring (9) and a first bolt (10) are respectively connected between the drawer frame (5) and the shell (4).
2. The acid gas revamp facility of claim 1, wherein: The check valve (1) is connected to the shell (4) by a thread or flange, and the top of the check valve (1) is connected to a stop valve (3) through an intermediate pipe (2).
3. The acid gas revamp facility of claim 1, wherein: The drawer frame (5) is detachably connected to the tube shell (4) and the sealing ring (9), and the wire mesh (6), the support mesh (7) and the grid plate (8) are all detachably connected to the drawer frame (5).
4. The acid gas revamp facility of claim 3, wherein: The wire mesh (6) is made of polytetrafluoroethylene material and has a porosity of 80%.
5. The acid gas revamp facility of claim 3, wherein: The mesh number of the support net (7) is 20 to 30.
6. The acid gas revamp facility of claim 3, wherein: The upper and lower interior of the tube shell (4) are both sloped.
7. The acid gas revamp facility of claim 3, wherein: A polytetrafluoroethylene coating is provided between the contact surfaces of the drawer frame (5) and the tube shell (4).
8. The acid gas revamp facility of claim 1, wherein: Both the first bolt (10) and the second bolt (11) are provided with double washers on the outside, and the double washers are a flat washer and a spring washer, respectively.
9. The acid gas revamp facility of claim 6, wherein: The shell (4) is made of 316L stainless steel or 2507 duplex stainless steel.
10. The acid gas revamp facility of claim 3, wherein: The drawer frame (5), support mesh (7) and grille (8) are all made of 316L stainless steel, and the sealing ring (9) is made of FFKM material.