A film tank insulation layer gas maintenance device and maintenance method

Abstract

The present invention discloses a gas maintenance device and method for the insulating layer of a membrane tank, which belongs to the field of natural gas transportation and storage technology. The device includes a gas input end and a gas output end, as well as a first circulation pipeline, wherein the gas input end and the gas output end are respectively connected to the first circulation pipeline; a plurality of monitoring sub-pipelines, each monitoring sub-pipeline is connected to the first circulation pipeline; a second circulation pipeline, wherein the second circulation pipeline is connected to each monitoring sub-pipeline through a branch pipe, a valve is provided between the second circulation pipeline and each monitoring sub-pipeline, and the second circulation pipeline is also connected to a sampling pump. The present application uses a redundant design mechanism of a first pressure differential detection mechanism and a sampling pump to achieve rapid judgment on the pressure differential of liquid cargo leakage through the first pressure differential detection mechanism, and then uses the sampling pump gas analysis to accurately judge the gas at the possible leakage location, so as to achieve refined monitoring of the membrane tank and ensure the safety of liquid cargo transportation.

Description

Technical Field

[0001] The present invention belongs to the technical field of natural gas transportation and storage, and in particular relates to a gas maintenance device and a maintenance method for the insulation layer of a membrane tank. Background Art

[0002] As a clean and efficient energy source, liquefied natural gas (LNG) is primarily transported via cryogenic, atmospheric, or pressurized storage tanks. Due to its low temperature and high compression, LNG requires stringent sealing and stability requirements during transportation. Regulations for LNG transportation typically require that natural gas storage tanks incorporate a complete or partially complete secondary shielding system for cargo containment. This secondary shielding layer is filled with dry protective gas to ensure that any leaks are contained within the protective gas atmosphere, preventing explosions caused by the cargo mixing with air.

[0003] Existing liquefied natural gas (LNG) storage tanks primarily incorporate pressure monitors and gas monitors within their cargo containment systems. These monitors analyze the gas pressure and composition within the cargo containment system to determine if there has been a leak of liquid cargo. Existing cargo containment systems typically have monitoring equipment installed at one or several locations. However, due to the large size of LNG storage tanks, by the time the monitoring equipment detects a leak, the liquid cargo has already been present within the containment system for some time, resulting in delayed monitoring. Furthermore, this monitoring method only indicates whether a membrane tank is leaking, but not the specific location of the leak. Summary of the Invention

[0004] In response to one or more of the above-mentioned defects or improvement needs of the prior art, the present invention provides a membrane tank insulation layer gas maintenance device to solve the problem that the existing cargo containment system cannot accurately monitor the leakage area of ​​the membrane tank.

[0005] To achieve the above object, the present invention provides a film tank insulation layer gas maintenance device, which includes:

[0006] A gas input end, the gas input end is used to input a protective gas;

[0007] A gas output end, the gas output end is used to output the protective gas;

[0008] a first circulation pipeline, the first circulation pipeline being arranged around the outer circumference of the membrane tank, the first circulation pipeline being arranged in a ring shape, the gas input end and the gas output end being respectively connected to the first circulation pipeline, and the gas input end and the gas output end being symmetrically arranged on both sides of the first circulation pipeline;

[0009] Monitoring sub-pipelines, wherein there are multiple monitoring sub-pipelines, each of which is distributed around the circumference of the membrane tank; the multiple monitoring sub-pipelines are all connected to the first circulation pipeline, and a valve is provided between each monitoring sub-pipeline and the first circulation pipeline;

[0010] Each of the monitoring sub-pipelines includes two pipeline openings, the two pipeline openings are arranged toward the outer wall of the film tank, and the two pipeline openings are spaced apart, and a first pressure difference detection mechanism is connected in parallel between the two pipeline openings;

[0011] The second circulation pipeline is connected to each of the monitoring sub-pipelines through a branch pipe. A valve is provided between the second circulation pipeline and each of the monitoring sub-pipelines, and the second circulation pipeline is also connected to a sampling pump.

[0012] As a further improvement of the present invention, there are multiple first circulation pipelines, each of which is vertically stacked in sequence along the side wall of the film tank, and each of which is provided with multiple monitoring sub-pipelines;

[0013] There are multiple second circulation pipelines, and each of the second circulation pipelines is arranged in a one-to-one correspondence with a monitoring sub-pipeline on each first circulation pipeline.

[0014] As a further improvement of the present invention, the sampling pump is further connected to a first incineration unit.

[0015] As a further improvement of the present invention, the first circulation pipeline is further connected to a vacuum pump through a branch pipe, and the vacuum pump is connected to the second incineration unit.

[0016] As a further improvement of the present invention, it also includes a third circulation pipeline, one end of the third circulation pipeline is connected to the vacuum pump, and the other end is connected to the gas input end. A pressure swing adsorption module is provided on the third circulation pipeline, and the pressure swing adsorption module is connected to a third incineration unit through a branch pipe.

[0017] As a further improvement of the present invention, the gas input end includes a first input part and a second input part arranged side by side, a second pressure differential detection mechanism is connected in parallel between the first input part and the second input part, the first input part and the second input part are both connected to the first circulation pipeline, and the first input part and the second input part are arranged at intervals on the horizontal plane;

[0018] The gas output end includes a first output part and a second output part arranged side by side, a third pressure difference detection mechanism is connected in parallel between the first output part and the second output part, the first output part and the second output part are both connected to the first circulation pipeline, and the first output part and the second output part are arranged at intervals on the horizontal plane.

[0019] The present application also includes a film tank insulation layer gas maintenance method, which is performed by the film tank insulation layer gas maintenance device, and includes the following steps:

[0020] S1. The gas input end inputs protective gas to each monitoring sub-pipeline through the first circulation pipeline, and the gas output end outputs protective gas to each monitoring sub-pipeline through the first circulation pipeline. The protective gas passes through the pipeline openings of each monitoring sub-pipeline to form a protective gas atmosphere around the membrane tank;

[0021] S2. A first differential pressure detection mechanism on each monitoring sub-pipeline monitors the pressure differential between the two pipeline openings. When the pressure fluctuation at one of the first differential pressure detection mechanisms exceeds a threshold, the second circulation pipeline closes the valve connecting to the other monitoring sub-pipeline. A sampling pump draws gas through the second circulation pipeline to the monitoring sub-pipeline at the pressure fluctuation location and analyzes the gas to determine whether a leak has occurred at the pressure fluctuation location.

[0022] S3. When a leak occurs, the gas input end inputs protective gas through the monitoring sub-pipeline at the leak location, and the sampling pump draws gas to the monitoring sub-pipelines on both sides of the pressure fluctuation location through the second circulation pipeline;

[0023] When no leakage occurs, the second circulation pipeline maintains communication with each monitoring sub-pipeline, and the gas input end uniformly inputs protective gas to each monitoring sub-pipeline.

[0024] As a further improvement of the present invention, there are multiple first circulation pipelines, and each of the first circulation pipelines is vertically stacked in sequence along the side wall of the membrane tank; and a protective gas purge is further included before S1:

[0025] Adjust the input pressure difference between each first circulation pipeline, increase the input pressure difference of the gas input end at the upper end, and reduce the output pressure difference of the gas output end at the upper end; reduce the input pressure difference of the gas input end at the lower end, and increase the output pressure difference of the gas output end at the lower end.

[0026] As a further improvement of the present invention, the gas input end includes two first input parts and a second input part arranged side by side, and the gas output end includes two first output parts and a second output part arranged side by side; and before S1, it also includes a protective gas purge: increasing the input pressure of the first input part, reducing the input pressure of the second input part, reducing the output pressure of the first output part, and increasing the output pressure of the second output part.

[0027] As a further improvement of the present invention, the leakage of the membrane tank is located on one side of the second input part and the second output part; when leakage occurs in S3, the step further includes:

[0028] Increase the input pressure of the first input part and reduce the output pressure of the first output part; reduce the input pressure of the second input part and reduce the output pressure of the second output part;

[0029] The sampling pump draws gas through the second circulation pipeline to the monitoring sub-pipelines on both sides of the air pressure fluctuation location.

[0030] The above-mentioned improved technical features can be combined with each other as long as they do not conflict with each other.

[0031] In general, the above technical solutions conceived by the present invention have the following beneficial effects compared with the prior art:

[0032] (1) The gas maintenance device for the insulating layer of the membrane tank of the present invention transports the protective gas input from the gas input end to various locations around the membrane tank through the first circulation pipeline and the monitoring sub-pipeline, so as to form a protective gas atmosphere around the membrane tank and ensure the safe transportation of liquid cargo; secondly, when the membrane tank leaks, the liquid cargo at the leakage location vaporizes and expands, causing the pressure at the leakage location to increase, and the pressure difference at the openings of the two corresponding monitoring sub-pipelines is unbalanced. The first pressure difference detection mechanism can monitor the pressure fluctuation, thereby achieving a preliminary judgment on the leakage of liquid cargo in the membrane tank; then, the second circulation pipeline is used to suction the monitoring sub-pipeline at the leakage location at a fixed point, so as to draw the gas at the leakage location into the sampling pump for analysis, so as to further determine whether a leakage occurs in the corresponding area of ​​the membrane tank. This application realizes a rapid judgment on the pressure difference of liquid cargo leakage and an accurate judgment of the gas analysis of the sampling pump through the redundant design mechanism of the first pressure difference detection mechanism and the sampling pump, so as to achieve refined monitoring of the membrane tank and ensure the safety of liquid cargo transportation.

[0033] (2) The gas maintenance device for the insulating layer of the membrane tank of the present invention arranges a plurality of first circulation pipelines vertically along the side wall of the membrane tank. The monitoring sub-pipelines connected to each first circulation pipeline can monitor the pressure difference in different areas around the membrane tank, thereby realizing comprehensive monitoring of the periphery of the membrane tank. Secondly, the arrangement of the first circulation pipelines at different layers enables the input and output of the protective gas in different areas to be individually controllable. By controlling the input and output of the protective gas in different areas around the membrane tank, a directional flow of the protective gas can be realized, and a directional purge of the peripheral area of ​​the membrane tank can be realized, thereby completing the gas replacement of the insulating layer of the membrane tank and facilitating the subsequent formation of a protective atmosphere around the membrane tank.

[0034] (3) The gas maintenance device for the insulating layer of the membrane tank of the present invention connects the vacuum pump with the gas input end by setting a third circulation pipeline, and sets a pressure swing adsorption module between the two. On the one hand, the pressure swing adsorption module can collect the leaked natural gas and separate it from the protective gas, so that the output protective gas can be circulated to the gas input end again to reduce the consumption of the protective gas; on the other hand, it can purify the leaked natural gas so that the natural gas output by the pressure swing adsorption module meets the incineration energy supply standard, so that the leaked natural gas can be used for energy supply, avoiding the problem of conventional waste of leaked natural gas incineration, improving the utilization rate of leaked natural gas, and reducing waste. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 2 is a schematic diagram of the overall structure of the gas maintenance device for the insulating layer of a membrane tank according to an embodiment of the present invention;

[0036] Figure 2 2 is a schematic diagram of the structure of the monitoring sub-pipeline in an embodiment of the present invention;

[0037] Figure 3 Schematic diagram of gas flow in step S1 in an embodiment of the present invention;

[0038] Figure 4 Schematic diagram of gas flow in step S3 in an embodiment of the present invention;

[0039] Figure 5 Schematic diagram of the gas flow of a protective gas purging membrane tank in one embodiment of the present invention;

[0040] Figure 6 This is a schematic diagram of gas flow when a membrane tank leaks in one embodiment of the present invention;

[0041] Figure 7 It is a schematic diagram of gas flow when a membrane tank leaks in one embodiment of the present invention.

[0042] In all the drawings, the same reference numerals represent the same technical features, specifically:

[0043] 101. Gas input; 102. Gas output; 103. First circulation pipeline; 104. Monitoring sub-pipeline; 105. Second circulation pipeline; 106. Sampling pump; 107. First incineration unit; 108. Vacuum pump; 109. Second incineration unit; 110. Third circulation pipeline; 111. Pressure swing adsorption module; 112. Third incineration unit; 113. First input; 114. Second input; 115. First output; 116. Second output; 117. Second differential pressure detection mechanism; 118. Third differential pressure detection mechanism; 119. Membrane tank;

[0044] 1041. Pipeline opening; 1042. First pressure difference detection mechanism. DETAILED DESCRIPTION

[0045] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only intended to illustrate the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.

[0046] In the description of the present invention, it should be understood that, unless otherwise specified, the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like to indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation, and therefore should not be understood as limiting the present invention.

[0047] Furthermore, unless otherwise specified, the terms "first" and "second" are used for descriptive purposes only and should not be understood to indicate or imply relative importance or implicitly specify the number of the technical features indicated. Thus, a feature specified as "first" or "second" may explicitly or implicitly include at least one of such features. In the description of the present invention, "plurality" means at least two, such as two, three, etc., unless otherwise specified.

[0048] In the present invention, unless otherwise specified or limited, the terms "installed," "connected," "connect," "fixed," etc. should be understood in a broad sense. For example, they can refer to fixed connection, detachable connection, or integration; mechanical connection, electrical connection; direct connection, or indirect connection through an intermediate medium; internal communication between two components, or interaction between two components, unless otherwise specified. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0049] In the present invention, unless otherwise expressly specified or limited, when a first feature is "above" or "below" a second feature, it may mean that the first and second features are in direct contact, or that the first and second features are in indirect contact through an intermediary. Furthermore, when a first feature is "above," "above," or "above" a second feature, it may mean that the first feature is directly above or diagonally above the second feature, or simply means that the first feature is at a higher level than the second feature. When a first feature is "below," "below," or "below" a second feature, it may mean that the first feature is directly below or diagonally below the second feature, or simply means that the first feature is at a lower level than the second feature.

[0050] Example:

[0051] See also Figures 1 to 7The membrane tank 119 insulating layer gas maintenance device in the preferred embodiment of the present invention includes a gas input end 101 and a gas output end 102, the gas input end 101 is used for inputting protective gas, and the gas output end 102 is used for outputting protective gas; and a first circulation pipeline 103, the first circulation pipeline 103 is arranged around the outer periphery of the membrane tank 119, and the first circulation pipeline 103 is arranged in a ring shape, the gas input end 101 and the gas output end 102 are respectively connected to the first circulation pipeline 103, the gas input end 101 and the gas output end 102 are symmetrically arranged on both sides of the first circulation pipeline 103; a monitoring sub-pipeline 104, the monitoring sub-pipeline 104 is multiple, and each monitoring sub-pipeline 104 is distributed around the membrane tank 119; multiple monitoring sub-pipelines 104 are all connected to the first circulation pipeline 103, and a valve is provided between each monitoring sub-pipeline 104 and the first circulation pipeline 103. Each monitoring sub-pipeline 104 includes two pipeline openings 1041, which face the outer wall of the membrane tank 119 and are spaced apart. A first pressure differential detection mechanism 1042 is connected in parallel between the two pipeline openings 1041. Furthermore, the second circulation pipeline 105 is connected to each monitoring sub-pipeline 104 via a branch pipe. A valve is installed between the second circulation pipeline 105 and each monitoring sub-pipeline 104. The second circulation pipeline 105 is also connected to a sampling pump 106. The first circulation pipeline 103 and the second circulation pipeline 105 do not interfere with each other, and both can input or output gas through the monitoring sub-pipeline 104.

[0052] The insulating layer gas maintenance device of the membrane tank 119 in the present invention transports the protective gas in the gas input end 101 to each monitoring sub-pipeline 104 through the first circulation pipeline 103, and then outputs the protective gas to different areas around the membrane tank 119 through the two pipeline openings 1041 of the monitoring sub-pipeline 104. When the membrane tank 119 is damaged and leaks, the liquid cargo at the damaged position leaks into the insulating layer area and vaporizes and expands, causing the gas pressure at the leakage position to increase, and the pressure at the two pipeline openings 1041 at the leakage position to become unbalanced, which can be detected by the first pressure difference detection mechanism 1042 at this time, thereby realizing preliminary monitoring of the leakage of the membrane tank 119; at the same time, when the membrane tank 119 leaks, it can be sucked into the monitoring sub-pipeline 104 at the leakage position at a fixed point through the second circulation pipeline 105, and the leaked gas is extracted to the sampling pump 106 for analysis to further confirm whether the corresponding area of ​​the membrane tank 119 has leaked. This application utilizes a redundant design mechanism, including the first differential pressure detection mechanism 1042 and the sampling pump 106, to prevent the expansion of the membrane tank 119 caused by the increase of flash steam inside the membrane tank 119, which would reduce the distance between the membrane tank 119 and the pipeline opening 1041 and cause the first differential pressure detection mechanism 1042 to misjudge a liquid cargo leak. This application first utilizes the first differential pressure detection mechanism 1042 to quickly determine the pressure difference in the event of a liquid cargo leak. Then, the sampling pump 106 extracts gas at a specific point for analysis, accurately determining a liquid cargo leak and enabling refined monitoring of the membrane tank 119 to ensure the safety of liquid cargo transportation.

[0053] Furthermore, as an optional embodiment of the present invention, the present application provides multiple first circulation pipelines 103, and each first circulation pipeline 103 is vertically stacked in sequence along the side wall of the membrane tank 119. The annular first circulation pipeline 103 in the present application can only monitor the leakage of the membrane tank 119 on one horizontal plane, and the leakage of the membrane tanks 119 at the upper and lower ends of the first circulation management needs to spread for a period of time before it can be detected by the monitoring sub-pipeline 104. Based on this, the present application sets up multiple first circulation pipelines 103 structures on the periphery of the membrane tank 119, and each first circulation pipeline 103 is provided with multiple monitoring sub-pipelines 104. By arranging the monitoring sub-pipelines 104 in various areas around the membrane tank 119, comprehensive monitoring of the membrane tank 119 can be achieved. On the other hand, in addition to monitoring various locations of the membrane tank 119, the monitoring sub-pipeline 104 in this application can also control the gas input and output of the first circulation pipeline 103 at different heights to achieve a pressure difference at different locations of the insulation layer of the membrane tank 119, achieve a directional flow of the protective gas, and complete the protective gas purge operation. It is worth noting that there are also multiple second circulation pipelines 105, and each second circulation pipeline 105 is arranged in a one-to-one correspondence with the monitoring sub-pipeline 104 on each first circulation pipeline 103, so as to achieve separate monitoring of the periphery of the membrane tank 119 at different levels. Optionally, multiple second circulation pipelines 105 are connected to the same sampling pump 106; or each second circulation pipeline 105 is provided with a sampling pump 106.

[0054] Optionally, the shielding gas in the present application is nitrogen or argon, preferably nitrogen. It is worth noting that other non-flammable gases that do not react with natural gas can also be used as shielding gases.

[0055] Furthermore, as an optional embodiment of the present invention, sampling pump 106 is further connected to a first incineration unit 107. In the event of a liquid cargo leak, the gas extracted by sampling pump 106 contains natural gas. To prevent direct discharge of natural gas, which could cause air pollution and explosion hazards, first incineration unit 107 is required to combust the natural gas in the extracted gas and then discharge it.

[0056] Furthermore, as an optional embodiment of the present invention, the first circulation pipeline 103 is further connected to a vacuum pump 108 via a branch pipe, and the vacuum pump 108 is connected to a second incineration unit 109. Although the second circulation pipeline 105, the sampling pump 106, and the first incineration unit 107 can achieve incineration of leaked natural gas, the sampling and analysis requirements of the sampling pump 106 result in relatively low extraction efficiency. When a large amount of natural gas leaks, the leaked liquid cargo can be directly extracted through the first circulation pipeline 103 and the vacuum pump 108, and then burned in the second incineration unit 109, preventing the leaked natural gas from spreading to other areas of the insulation layer of the membrane tank 119 and causing gas contamination of a wider area of ​​the insulation layer.

[0057] Furthermore, as an optional embodiment of the present invention, the insulating layer gas maintenance device of the membrane tank 119 also includes a third circulation pipeline 110, one end of the third circulation pipeline 110 is connected to the vacuum pump 108, and the other end thereof is connected to the gas input end 101, and a pressure swing adsorption module 111 is also provided on the third circulation pipeline 110, and the pressure swing adsorption module 111 is connected to the third incineration unit 112 through a branch pipe. The main component of the leaked gas extracted from the vacuum pump 108 is still the protective gas, and the natural gas with a lower concentration cannot meet the energy supply standard and can only be burned as waste gas, and at the same time the protective gas will be discharged to the outside, resulting in a large amount of waste of protective gas. Based on this, the present invention sets the third circulation pipeline 110, and separates the protective gas and natural gas through the pressure swing adsorption module 111, so that the protective gas can circulate normally to the gas input end 101, reducing the waste of protective gas, such as Figure 7 As shown. On the other hand, the pressure swing adsorption module 111 can enrich the natural gas in the leaked gas. When the natural gas adsorbed by the pressure swing adsorption module 111 reaches an energy-supply concentration, the natural gas is transported to the third incineration unit 112 for combustion and energy supply, effectively utilizing the leaked natural gas. Optionally, the pressure swing adsorption module 111 is a device for gas separation, purification, and cleansing based on pressure swing adsorption technology. It is a conventional gas separation device in the art and will not be described in detail here.

[0058] Furthermore, as an optional embodiment of the present invention, the gas input end 101 includes two first input parts 113 and second input parts 114 arranged side by side, a second pressure differential detection mechanism 117 is connected in parallel between the first input part 113 and the second input part 114, both of which are connected to the first circulation pipeline 103, and the first input part 113 and the second input part 114 are arranged with a spacing therebetween on the horizontal plane. Correspondingly, the gas output end 102 includes two first output parts 115 and second output parts 116 arranged side by side, a third pressure differential detection mechanism 118 is connected in parallel between the first output part 115 and the second output part 116, both of which are connected to the first circulation pipeline 103, and the first output part 115 and the second output part 116 are arranged with a spacing therebetween on the horizontal plane. The use of multiple first circulation pipelines 103 allows for vertical airflow control within the membrane tank 119, thereby achieving directional vertical purging of the insulating layer of the membrane tank 119. The arrangement of the gas input end 101 and the gas output end 102 allows for horizontal purging of the insulating layer of the membrane tank 119 from the gas input end 101 toward the gas output end 102, but does not allow for purging perpendicular to the gas input end 101 and the gas output end 102. Therefore, the present invention provides a first input portion 113 and a second input portion 114. By controlling the airflow of the first input portion 113 and the second input portion 114, a pressure differential is achieved between the first input portion 113 and the second input portion 114 in the horizontal plane, thereby causing the shielding gas to flow from the first input portion 113 to the second input portion 114, achieving directional purging of the shielding gas in the horizontal plane. Accordingly, by controlling the suction force of the first output portion 115 and the second output portion 116, directional flow of the shielding gas can also be achieved.

[0059] At the same time, the second pressure difference detection mechanism 117 and the third pressure difference detection mechanism 118 can realize quantitative detection of the pressure difference between the first input part 113 and the second input part 114, and between the first output part 115 and the second output part 116, so as to adjust the input or output pressure difference and stabilize the purge efficiency and quality of the insulation layer of the film tank 119.

[0060] Optionally, a booster pump is provided on the first input part 113 and the second input part 114 to control the gas flow rate of the first input part 113 and the second input part 114; a suction pump is provided on the first output part 115 and the second output part 116 to control the suction pressure of the first output part 115 and the second output part 116.

[0061] Optionally, valves are provided on each pipeline of the insulating layer gas maintenance device of the membrane tank 119 of the present application.

[0062] Furthermore, the present invention also includes a method for maintaining the gas in the insulating layer of the membrane tank 119, which uses the above-mentioned gas maintenance device for the insulating layer of the membrane tank 119 to perform maintenance, and includes the following steps:

[0063] S1, the gas input end 101 inputs protective gas to each monitoring sub-pipeline 104 through the first circulation pipeline 103, and the gas output end 102 outputs protective gas to each monitoring sub-pipeline 104 through the first circulation pipeline 103. The protective gas passes through the openings of each monitoring sub-pipeline 104 to form a protective gas atmosphere around the membrane tank 119, such as Figure 3 As shown in the figure, the blue line represents the flow direction of the shielding gas input from the gas input end 101, and the red line represents the flow direction of the gas in the insulating layer of the membrane tank 119 when it is extracted from the gas output end 102. It is worth noting that the red and blue lines only represent the flow direction of the gas. In actual operation, the shielding gas in the membrane tank 119 flows as a whole, and there is no absolute distinction between inflow and outflow.

[0064] S2. The first differential pressure detection mechanism 1042 on each monitoring sub-pipeline 104 monitors the pressure difference between the two pipeline openings 1041. When the pressure fluctuation at one of the first differential pressure detection mechanisms 1042 exceeds a threshold, the second circulation pipeline 105 closes the valve connected to the other monitoring sub-pipelines 104. The sampling pump 106 draws gas through the second circulation pipeline 105 to the monitoring sub-pipeline 104 at the location of the pressure fluctuation and analyzes the gas to determine whether a leak occurs at the location of the pressure fluctuation.

[0065] S3. When leakage occurs, the gas input end 101 inputs protective gas through the monitoring sub-pipeline 104 at the leakage location, and the sampling pump 106 draws gas to the monitoring sub-pipelines 104 on both sides of the pressure fluctuation location through the second circulation pipeline 105. Figure 4 As shown, the blue line in the figure represents the flow direction of the protective gas input from the gas input end 101, and the red line in the figure represents the flow direction of the gas in the insulating layer of the membrane tank 119 when it is extracted from the gas output end 102;

[0066] When no leakage occurs, the second circulation pipeline 105 maintains communication with each monitoring sub-pipeline 104 , and the gas input end 101 inputs protective gas to each monitoring sub-pipeline 104 at a uniform speed.

[0067] The gas maintenance method for the insulating layer of the membrane tank 119 in the present invention inputs protective gas into the insulating layer area of ​​the membrane tank 119 through the cooperation of the gas input end 101 and the monitoring sub-pipeline 104, and extracts the gas from the insulating layer of the membrane tank 119 through the cooperation of the gas output end 102 and the monitoring sub-pipeline 104, so as to achieve dynamic balance of the protective gas in the insulating layer of the membrane tank 119, so that the membrane tank 119 is in a flowing protective gas atmosphere; when the pressure difference of the first pressure difference detection mechanism 1042 on the monitoring sub-pipeline 104 fluctuates, it means that a natural gas leak may occur in the area where the monitoring sub-pipeline 104 is located. At this time, the valve between the second circulation pipeline 105 and the other monitoring sub-pipelines 104 can be closed, and the sampling pump 106 can be used to suction the possible leakage position at a fixed point. The gas extracted by the sampling pump 106 is analyzed to determine whether a leakage actually occurs at the pressure fluctuation location. When the membrane tank 119 leaks, protective gas can be input into the monitoring sub-pipeline 104 at the leak point through the gas input end 101. The pressurization of the protective gas can suppress the leakage of natural gas. At the same time, the sampling pump 106 draws gas to the monitoring sub-pipeline 104 on both sides of the air pressure fluctuation point through the second circulation pipeline 105, thereby increasing the output of protective gas at the leak point. The form of extracting gas on both sides of the leak point can prevent the leaked natural gas from spreading to other areas, and the leaked natural gas is extracted and discharged for treatment, thereby preventing subsequent accumulation of natural gas in the insulation layer to create safety hazards.

[0068] Furthermore, as an optional embodiment of the present invention, there are multiple first circulation pipelines 103, and each first circulation pipeline 103 is vertically stacked in sequence along the side wall of the film tank 119. Before step S1, a protective gas purge is also included:

[0069] Increase the input pressure of the gas input end 101 at the upper end and reduce the output pressure of the gas output end 102 at the upper end; reduce the input pressure of the gas input end 101 at the lower end and increase the output pressure of the gas output end 102 at the lower end, such as Figure 5 As shown in the figure, the blue line represents the flow direction of the shielding gas input from the gas input end 101, and the red line represents the flow direction of the gas in the insulating layer of the membrane tank 119 when it is extracted from the gas output end 102. By increasing the shielding gas input to the upper side of the membrane tank 119 and reducing the shielding gas output from the lower side of the membrane tank 119, a directional airflow is formed on the upper and lower sides of the membrane tank 119, achieving a shielding gas purge from top to bottom, thereby removing the air in the insulating layer of the membrane tank 119 and placing the insulating layer of the membrane tank 119 in a shielding gas atmosphere.

[0070] Furthermore, as an optional embodiment of the present invention, the gas input end 101 includes two side-by-side first input parts 113 and second input parts 114, and the gas output end 102 includes two side-by-side first output parts 115 and second output parts 116. Prior to step S1, a shielding gas purge is also performed: increasing the input pressure of the first input part 113, decreasing the input pressure of the second input part 114, decreasing the output pressure of the first output part 115, and increasing the output pressure of the second output part 116. By increasing the input pressure of the first input part 113 and decreasing the input pressure of the first output part 115, the amount of shielding gas on one side of the first input part 113 and the first output part 115 is increased; by decreasing the input pressure of the second input part 114 and increasing the output pressure of the second output part 116, negative pressure suction is generated on one side of the second input part 114 and the second output part 116, forming a directional flow on both sides, completing the shielding gas purge.

[0071] Furthermore, as an optional embodiment of the present invention, the air pressure fluctuation is located on the side of the second input part 114 and the second output part 116; when the membrane tank 119 leaks in step S3, the step further includes: increasing the input pressure of the first input part 113 and reducing the output pressure of the first output part 115; reducing the input pressure of the second input part 114 and reducing the output pressure of the second output part 116; the sampling pump 106 draws gas to the monitoring sub-pipelines 104 on both sides of the air pressure fluctuation through the second circulation pipeline 105, such as Figure 6 As shown in the figure, the blue line represents the flow of shielding gas from gas input port 101, while the red line represents the flow of gas from the insulating layer of membrane tank 119 when it is extracted from gas output port 102. If membrane tank 119 leaks, to prevent the spread of natural gas from the leak to other areas, the shielding gas concentration can be increased away from the leak point, directing the shielding gas toward the leak, allowing sampling pump 106 to extract the natural gas from the leak point through second circulation pipeline 105.

[0072] It will be easily understood by those skilled in the art that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A film tank insulation layer gas maintenance device, characterized in that: include: A gas input end, the gas input end is used to input a protective gas; A gas output end, the gas output end is used to output the protective gas; a first circulation pipeline, the first circulation pipeline being arranged around the outer circumference of the membrane tank, the first circulation pipeline being arranged in a ring shape, the gas input end and the gas output end being respectively connected to the first circulation pipeline, and the gas input end and the gas output end being symmetrically arranged on both sides of the first circulation pipeline; Monitoring sub-pipelines, wherein there are multiple monitoring sub-pipelines, each of which is distributed around the circumference of the membrane tank; the multiple monitoring sub-pipelines are all connected to the first circulation pipeline, and a valve is provided between each monitoring sub-pipeline and the first circulation pipeline; Each of the monitoring sub-pipelines includes two pipeline openings, the two pipeline openings are arranged toward the outer wall of the film tank, and the two pipeline openings are spaced apart, and a first pressure difference detection mechanism is connected in parallel between the two pipeline openings; The second circulation pipeline is connected to each of the monitoring sub-pipelines through a branch pipe. A valve is provided between the second circulation pipeline and each of the monitoring sub-pipelines, and the second circulation pipeline is also connected to a sampling pump.

2. The film tank insulation layer gas maintenance device according to claim 1, characterized in that: There are multiple first circulation pipelines, each of which is vertically stacked in sequence along the side wall of the film tank, and each of which is provided with multiple monitoring sub-pipelines; There are multiple second circulation pipelines, and each of the second circulation pipelines is arranged in a one-to-one correspondence with a monitoring sub-pipeline on each first circulation pipeline.

3. The film tank insulation layer gas maintenance device according to claim 1, characterized in that: The sampling pump is also connected to a first incineration unit.

4. The film tank insulation layer gas maintenance device according to claim 1, characterized in that: The first circulation pipeline is further connected to a vacuum pump via a branch pipe, and the vacuum pump is connected to a second incineration unit.

5. The film tank insulation layer gas maintenance device according to claim 4, characterized in that: It also includes a third circulation pipeline, one end of which is connected to the vacuum pump, and the other end is connected to the gas input end. A pressure swing adsorption module is provided on the third circulation pipeline, and the pressure swing adsorption module is connected to a third incineration unit through a branch pipe.

6. The film tank insulation layer gas maintenance device according to claim 1 or 2, characterized in that: The gas input end includes a first input part and a second input part arranged side by side, a second pressure difference detection mechanism is connected in parallel between the first input part and the second input part, the first input part and the second input part are both connected to the first circulation pipeline, and the first input part and the second input part are arranged at intervals on the horizontal plane; The gas output end includes a first output part and a second output part arranged side by side, a third pressure difference detection mechanism is connected in parallel between the first output part and the second output part, the first output part and the second output part are both connected to the first circulation pipeline, and the first output part and the second output part are arranged at intervals on the horizontal plane.

7. A method for maintaining the gas insulation layer of a film tank, which is performed by using the gas maintenance device for the insulation layer of a film tank as claimed in any one of claims 1 to 6, characterized in that: The steps include: S1. The gas input end inputs protective gas to each monitoring sub-pipeline through the first circulation pipeline, and the gas output end outputs protective gas to each monitoring sub-pipeline through the first circulation pipeline. The protective gas passes through the pipeline openings of each monitoring sub-pipeline to form a protective gas atmosphere around the membrane tank; S2. A first differential pressure detection mechanism on each monitoring sub-pipeline monitors the pressure differential between the two pipeline openings. When the pressure fluctuation at one of the first differential pressure detection mechanisms exceeds a threshold, the second circulation pipeline closes the valve connected to the other monitoring sub-pipelines. A sampling pump draws gas through the second circulation pipeline to the monitoring sub-pipeline at the pressure fluctuation location and analyzes the gas to determine whether a leak has occurred at the pressure fluctuation location. S3. When a leak occurs, the gas input end inputs protective gas through the monitoring sub-pipeline at the leak location, and the sampling pump draws gas to the monitoring sub-pipelines on both sides of the pressure fluctuation location through the second circulation pipeline; When no leakage occurs, the second circulation pipeline maintains communication with each monitoring sub-pipeline, and the gas input end uniformly inputs protective gas to each monitoring sub-pipeline.

8. The method for maintaining the gas in the insulation layer of a film tank according to claim 7, characterized in that: There are multiple first circulation pipelines, and each of the first circulation pipelines is vertically stacked in sequence along the side wall of the membrane tank; a protective gas purge is also included before S1: Increasing the input pressure of the gas input end at the upper end reduces the output pressure of the gas output end at the upper end; reducing the input pressure of the gas input end at the lower end increases the output pressure of the gas output end at the lower end.

9. The method for maintaining the insulating layer gas of a film tank according to claim 7, characterized in that: The gas input end includes two first input parts and a second input part arranged side by side, and the gas output end includes two first output parts and a second output part arranged side by side; before S1, a protective gas purge is also included: increasing the input pressure of the first input part, reducing the input pressure of the second input part, reducing the output pressure of the first output part, and increasing the output pressure of the second output part.

10. The method for maintaining the insulating layer gas of a film tank according to claim 7, characterized in that: The leakage of the membrane tank is located on one side of the second input part and the second output part; when leakage occurs in S3, the following steps are also included: Increase the input pressure of the first input part and reduce the output pressure of the first output part; reduce the input pressure of the second input part and reduce the output pressure of the second output part; The sampling pump draws gas through the second circulation pipeline to the monitoring sub-pipelines on both sides of the air pressure fluctuation location.

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