Snakelike maintenance pipeline system for thin film tank protection and thin film tank maintenance method

Abstract

The invention discloses a snakelike maintenance pipeline system for thin film tank protection and a thin film tank maintenance method, and belongs to the technical field of natural gas transportation and storage, the snakelike maintenance pipeline system comprises a gas input end, a gas output end and a protection pipeline, the protection pipeline surrounds and wraps the periphery of a thin film tank, one end of the protection pipeline is connected with the gas input end, and the other end of the protection pipeline is connected with the gas output end. The protection pipeline comprises straight sections and bent pipe sections, the straight sections and the bent pipe sections are alternately arranged, and expansion joints and air outlets are further arranged on the straight sections or the bent pipe sections. By adjusting the protection pipeline structure, the connection problem of an existing maintenance pipeline during thermal expansion and cold contraction is solved, it is ensured that the protection pipeline is always in an integrated structure, the stability of a maintenance pipeline system under different temperature working conditions such as thermal expansion and cold contraction is ensured, stable output of protection gas and stability of liquid cargo gas discharging are ensured, and the service life of the maintenance pipeline system is prolonged. Workers can conveniently master the working condition of the thin film tank, and the safety of liquid cargo storage and transportation is ensured.

Description

Technical Field

[0001] The invention belongs to the technical field of natural gas transportation and storage, and in particular relates to a serpentine maintenance pipeline system for protecting a membrane tank and a membrane tank maintenance method. Background Art

[0002] As a clean and efficient energy source, liquefied natural gas is mainly stored and transported through low-temperature atmospheric pressure storage tanks or pressure storage tanks. Due to its low temperature and high compression characteristics, the transportation of liquefied natural gas has higher sealing and stability requirements. Based on the transportation regulations of liquefied natural gas, natural gas storage tanks are usually required to have a complete or partially complete secondary shielding space cargo containment system, and the secondary shielding space needs to be filled with dry protective gas to ensure the safety of the transportation vehicle in the event of cargo leakage.

[0003] The secondary shielding space of the existing membrane tank mainly adopts straight pipes distributed on the periphery of the membrane tank, and the shielding gas is transported through the straight pipes to form a shielding gas atmosphere on the periphery of the membrane tank. When the liquefied natural gas in the membrane tank leaks, the low-temperature liquefied natural gas will cause the thermal expansion and contraction of the straight pipe, which may cause damage to the entire pipeline. In order to avoid the problem of damage to the shielding gas pipeline under thermal expansion and contraction, the straight pipe is usually cut into sections, and then a smaller pipe is nested between the two straight pipes. One end of the smaller pipe is welded to one of the straight pipes, and the other end is set in the other straight pipe. The smaller pipe can be expanded and contracted in the straight pipe to avoid damage to the entire pipeline. However, since the shielding gas transmission pipeline forms a multi-segment pipeline structure as a whole, the shielding gas can leak from the joints of each straight pipe; and when the natural gas leaks, the natural gas entering the secondary shielding space can also enter the inside of the shielding gas pipeline from the straight pipe joint, and the thermal expansion and contraction of the straight pipe will cause the size of the straight pipe joint gap to be variable, resulting in uneven distribution of the shielding gas in the secondary shielding layer, or unstable gas extraction when extracting natural gas through the shielding gas pipeline. Summary of the invention

[0004] In response to one or more of the above defects or improvement needs of the prior art, the present invention provides a serpentine maintenance pipeline system for membrane tank protection, which is used to solve the problems of uneven distribution of protective gas transmission and unstable natural gas extraction in the existing protective gas pipeline when natural gas leaks.

[0005] To achieve the above object, the present invention provides a serpentine maintenance pipeline system for membrane tank protection, comprising: A gas input end, wherein the gas input end is used to introduce a protective gas; A gas output end, wherein the gas output end is used to output the protective gas and / or liquid cargo gas to the outside; A protection pipeline, which is arranged around the outer periphery of the film tank; one end of the protection pipeline is connected to the gas input end, and the other end is connected to the gas output end; The protection pipeline includes a straight section and a curved section, and the straight section and the curved section are alternately connected to each other so as to be spirally arranged around the outer periphery of the film tank; The straight section is provided with an expansion joint, and the expansion joint can be telescopically arranged; and the straight section and / or the curved pipe section are provided with an air outlet to output the protective gas in the protective pipeline to the outer periphery of the membrane tank.

[0006] As a further improvement of the present invention, the protection pipeline includes a plurality of protection pipelines, each of which is arranged in a different area of ​​the periphery of the film tank; Two ends of each of the protection pipelines are respectively connected to the gas input end and the gas output end, and the protection pipelines are respectively provided with valves on the connecting pipelines connecting the gas input end and the gas output end.

[0007] As a further improvement of the present invention, the outer periphery of the membrane tank includes a plurality of primary monitoring areas, and each of the primary monitoring areas includes a plurality of the protection pipelines; Each of the primary monitoring areas includes a plurality of secondary monitoring areas, and each of the protection pipelines is arranged in one-to-one correspondence with each of the secondary monitoring areas.

[0008] As a further improvement of the present invention, a branch pipe is connected between one of the protection pipelines located in different first-level monitoring areas, and a first pressure difference detection device is provided on the branch pipe. The distances from both ends of the first pressure difference detection device to the gas output end are the same.

[0009] As a further improvement of the present invention, a branch pipe is connected between the two protection pipelines located in different secondary monitoring areas, and a second pressure difference detection device is provided on the branch pipe. The distances from both ends of the second pressure difference detection device to the gas output end are the same.

[0010] As a further improvement of the present invention, the protection pipeline is spirally arranged from the top of the film tank to the bottom of the film tank; The protection pipeline includes a plurality of straight sections arranged in sequence and at intervals along the vertical direction, each of the straight sections is arranged in the horizontal direction, each of the curved pipe sections is arranged in the vertical direction, and each of the curved pipe sections connects two adjacent straight sections.

[0011] As a further improvement of the present invention, the gas outlet holes are distributed on each of the straight sections, and each two adjacent gas outlet holes are arranged in a gradually decreasing spacing on the pipeline path from the gas input end to the gas output end.

[0012] As a further improvement of the present invention, a third pressure difference detection device is connected between at least two of the straight sections.

[0013] As a further improvement of the present invention, a temperature detection device is provided between at least two of the straight sections.

[0014] The present application also includes a membrane tank maintenance method, which is maintained by the membrane tank protection serpentine maintenance pipeline system, and includes the following steps: S1. Inputting protective gas into the peripheral space of the membrane tank through the protective pipeline, and extracting the air from the peripheral space of the membrane tank to achieve air replacement in the peripheral space of the membrane tank; S2, continuously inputting protective gas into the peripheral space of the membrane tank through the protective pipeline; S3. Continuously input protective gas into the leakage area, extract protective gas and liquid cargo gas into the protection pipeline adjacent to the leakage area, and complete the leakage detection of the leakage area; S4. Increase the output of protective gas in the leakage area, extract protective gas and liquid cargo gas to the protective pipeline adjacent to the leakage area, and complete the suppression of liquid cargo leakage in the leakage area.

[0015] The above-mentioned improved technical features can be combined with each other as long as they do not conflict with each other.

[0016] In general, compared with the prior art, the above technical solution conceived by the present invention has the following beneficial effects: (1) The serpentine maintenance pipeline system for protecting the membrane tank of the present invention has a protection pipeline that adopts a combination structure of a straight section and a curved section, wherein the straight section is used to form the pipeline body, and the curved section is used to connect the straight sections to achieve a spiral distribution around the periphery of the membrane tank; at the same time, the protection pipeline has an expansion joint, which uses the expansion joint's own telescopic characteristics to solve the connection problem of the existing maintenance pipeline during thermal expansion and contraction, ensuring that the protection pipeline is always in an integrated structure, and the pipeline interval will not increase or decrease due to thermal expansion and contraction; and, the present application opens an air outlet on the straight section or the curved section to output the protective gas transported in the protection pipeline to the external space of the membrane tank, so as to form a protective gas atmosphere around the membrane tank. The present application ensures the stability of the maintenance pipeline system under different temperature conditions such as thermal expansion and contraction by adjusting the protection pipeline structure, ensures the stable output of the protective gas and the stability of the liquid cargo gas discharge, facilitates the staff to master the working conditions of the membrane tank, and ensures the safety of liquid cargo storage and transportation.

[0017] (2) The serpentine maintenance pipeline system for membrane tank protection of the present invention forms multiple zoned protections on the periphery of the membrane tank through multiple protection pipeline structures. When the membrane tank leaks, the protection gas can be input at a fixed point through the protection pipeline in the area where it is located, and the protection gas and liquid cargo gas can be output in a directional manner through the side protection pipeline, so as to clear the leaked liquid cargo gas, prevent the liquid cargo gas from leaking to the entire peripheral area of ​​the membrane tank, reduce the difficulty of cleaning the liquid cargo gas leakage, and reduce the maintenance cost of the membrane tank.

[0018] (3) The membrane tank maintenance method of the present invention forms protection on the periphery of the membrane tank through multiple protection pipelines, realizes the removal of air outside the membrane tank, directional injection of protection gas, accurate monitoring of liquid cargo gas and accurate removal of liquid cargo leakage. Through the serpentine maintenance pipeline system, the stable output of protection gas and the stable discharge of leaked liquid cargo gas are realized. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 Schematic diagram of the overall structure of the serpentine maintenance pipeline system for membrane tank protection in an embodiment of the present invention; Figure 2 is a schematic diagram of the overall structure of the protection pipeline in an embodiment of the present invention; Figure 3 is a schematic flow chart of a membrane tank maintenance method according to an embodiment of the present invention; Figure 4 It is a schematic diagram of the gas flow direction of inputting protective gas into the peripheral space of the membrane tank through the protective pipeline in one embodiment of the present invention; Figure 5 It is a schematic diagram of the gas flow direction of inputting protective gas into the peripheral space of the membrane tank through the protective pipeline in one embodiment of the present invention; Figure 6 It is a schematic diagram of the gas flow direction for clearing the liquid cargo gas in the leakage area of ​​the membrane tank in an embodiment of the present invention.

[0020] In all the drawings, the same reference numerals represent the same technical features, specifically: 1. Gas input end; 2. Gas output end; 3. Protection pipeline; 4. Second pressure difference detection device; 5. Intake pressure regulating valve; 6. Intake pressure temperature detection device; 301, straight section; 302, curved section; 303, expansion joint; 304, air outlet; 305, third pressure difference detection device; 306, temperature detection device. DETAILED DESCRIPTION

[0021] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain 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 can be combined with each other as long as they do not conflict with each other.

[0022] In the description of the present invention, it should be understood that, unless otherwise specified, terms such as “center”, “longitudinal”, “lateral”, “length”, “width”, “thickness”, “up”, “down”, “front”, “back”, “left”, “right”, “vertical”, “horizontal”, “top”, “bottom”, “inside”, “outside”, “clockwise”, “counterclockwise”, “axial”, “radial”, “circumferential”, etc., indicating orientations or positional relationships are 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 operated in a specific orientation, and therefore cannot be understood as limiting the present invention.

[0023] In addition, unless otherwise specified, the terms "first" and "second" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of the present invention, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0024] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0025] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, a first feature being "above", "above" or "above" a second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. A first feature being "below", "below" or "below" a second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0026] Example:

[0027] See also Figure 1 to Figure 6 , Figure 1 A schematic diagram showing the structure of the serpentine maintenance pipeline system for protecting the membrane tank of the present application on one side of the membrane tank. It can be understood that the circumferential protection pipelines 3 of the membrane tank together constitute the serpentine maintenance pipeline system for protecting the membrane tank; Figure 2 A schematic diagram showing the specific structure of the protection pipeline 3 of the present application; Figure 3 A schematic diagram showing the overall process of the membrane tank maintenance method of the present application; Figure 4 A schematic diagram showing the gas flow direction in the pipeline when the present application outputs the protective gas to one area of ​​the membrane tank. In the figure, blue represents the flow direction of the input protective gas in the protective pipeline 3, and red represents the protective pipeline 3 discharging the protective gas to the periphery of the membrane tank through the gas outlet 304; Figure 5 A schematic diagram showing the gas flow direction when the present application outputs protective gas to one area of ​​the membrane tank and sucks protective gas and air through the side protective pipeline 3. In the figure, blue represents the gas flow direction when the protective gas is input into the protective pipeline 3, and red represents the gas flow direction when the gas is discharged to the peripheral space of the membrane tank and the peripheral space of the membrane tank is sucked into the protective pipeline 3; Figure 6 It is a schematic diagram showing the gas flow direction when a membrane tank leaks, by inputting protective gas into the area and using the protective pipelines 3 on both sides to draw the protective gas and liquid cargo gas. In the figure, blue represents the gas flow direction when the protective gas is input into the protective pipeline 3, and the red surface represents the gas discharge from the peripheral space of the membrane tank, and the gas flow direction when the peripheral space of the membrane tank is drawn into the protective pipeline 3.

[0028] like Figure 1 As shown, the serpentine maintenance pipeline system for membrane tank protection in the preferred embodiment of the present invention is arranged on the periphery of the membrane tank, and includes a gas input end 1 and a gas output end 2, wherein the gas input end 1 is used to introduce protective gas, and the gas output end 2 is used to output the protective gas and / or liquid cargo gas to the outside. And a protection pipeline 3, the protection pipeline 3 is arranged around the periphery of the membrane tank, and one end of the protection pipeline 3 is connected to the gas input end 1, and the other end is connected to the gas output end 2. Specifically, the protection pipeline 3 includes a straight section 301 and a curved section 302, and the straight section 301 and the curved section 302 are arranged alternately so as to be spirally arranged on the periphery of the membrane tank; at the same time, an expansion joint 303 is correspondingly provided on the straight section 301, and the expansion joint 303 is telescopically arranged; and an air outlet 304 is also provided on the straight section 301 and / or the curved section 302, through which the protective gas in the protection pipeline 3 can be output to the periphery of the membrane tank to form a protective gas atmosphere outside the membrane tank.

[0029] Specifically, the serpentine maintenance pipe system for protecting the membrane tank in the present application adopts a combined structure of a straight section 301 and a curved pipe section 302. The straight section 301 is used to form the pipeline body, and the curved pipe section 302 is used to connect the straight sections 301 to achieve a spiral distribution on the periphery of the membrane tank, so that the pipeline is arranged on the periphery of the membrane tank; at the same time, the expansion joint 303 itself is used to solve the connection problem of the existing maintenance pipeline during thermal expansion and contraction, ensuring that the protection pipeline 3 is always in an integrated structure, and the problem of pipeline spacing increasing or decreasing due to thermal expansion and contraction will not occur; at the same time, the present application opens an air outlet 304 on the straight section 301 and / or the curved pipe section 302 to output the protective gas transported in the protection pipeline 3 to the external space of the membrane tank, so as to form a protective gas atmosphere around the membrane tank. This application ensures the stability of the maintenance pipeline system under different temperature conditions such as thermal expansion and contraction by adjusting the structure of the protection pipeline 3, ensures the stable output of the protection gas and the stability of the gas discharge of the liquid cargo, and facilitates the staff to master the working conditions of the membrane tank and ensure the safety of liquid cargo storage and transportation. It is worth noting that the core of this application is to adjust the maintenance pipeline system to a stable and controllable structure, realize the quantification of the input and output of the protection gas, and solve the problem of uncontrollable input and output of the protection gas amount in the traditional straight pipe pipeline system during thermal expansion and contraction. This application can realize effective monitoring of the gas leakage of the membrane tank by stably monitoring the gas output, thereby ensuring the safety of liquid cargo storage and transportation.

[0030] Specifically, the serpentine maintenance pipe system for protecting the membrane tank in the present application is arranged in the shielding layer of the outer periphery of the membrane tank, and is provided between the tank body and the membrane tank.

[0031] It is worth noting that membrane tanks are usually used to store compressed refrigerated liquid cargoes, which will quickly vaporize after leakage. Therefore, the liquid cargoes leaking to the outside of the membrane tanks will be represented as liquid cargo gas in this application.

[0032] Optionally, the membrane tank in the present application is generally used for the storage and transportation of liquid cargoes such as LNG, methanol, ethanol, and ethane. The protective gas input end 1 in the present application generally introduces nitrogen and argon as protective gases. In one embodiment of the present application, the present application uses nitrogen as the protective gas.

[0033] Optionally, the gas output end 2 in the present application is provided with a negative pressure suction device, through which active pressure extraction can be achieved to extract the liquid cargo gas leaking from the membrane tank through the gas outlet 304 on the protection pipeline 3. Optionally, the gas input end 1 and the gas output end 2 in the present application are respectively connected to the protection gas supply source and the exhaust gas treatment device.

[0034] Further, as an optional embodiment of the present invention, there are multiple protective pipelines 3 in the present application, and the multiple protective pipelines 3 are respectively arranged in different areas of the periphery of the membrane tank; the two ends of each protective pipeline 3 are respectively connected to the gas input end 1 and the gas output end 2, and valves are provided on the connecting pipelines between the protective pipeline 3 and the gas input end 1 and the gas output end 2. When a set of protective pipelines 3 is used to protect the periphery of the membrane tank, the protective gas can only reach various places on the outer wall of the membrane tank through a single line, and when the protective gas is discharged to the periphery of the membrane tank through the gas outlet 304, the protective gas cannot be discharged at a fixed point. When the membrane tank leaks, the protective gas protection and the leakage of liquid cargo gas can only be completed by increasing the protective gas input and extraction amount, which will cause a large amount of protective gas waste and be time-consuming and labor-intensive. Based on this, the present application sets up multiple sets of protection pipelines 3 to cover different areas on the periphery of the membrane tank. When there is a liquid cargo leakage, the valve on the protection pipeline 3 in the corresponding area can be adjusted to increase the input and extraction amount of the protection gas in the leakage area at a fixed point, so as to achieve precise protection against liquid cargo leakage, improve the protection efficiency of the membrane tank and reduce the consumption of the protection gas.

[0035] Further, as an optional embodiment of the present invention, the periphery of the membrane tank in the present application includes a plurality of primary monitoring areas, and each primary monitoring area includes a plurality of protective pipelines 3; and each primary monitoring area includes a plurality of secondary monitoring areas, and each protective pipeline 3 is arranged in a one-to-one correspondence with the secondary monitoring area. In order to further improve the efficient fixed-point protection of the external area of ​​the membrane tank by the protective pipeline 3, the present application divides the periphery of the membrane tank into a plurality of primary monitoring areas, and divides the plurality of primary monitoring areas into a plurality of secondary monitoring areas, in this way, a one-to-one correspondence between the protective pipeline 3 and each secondary monitoring area is achieved. Through the refined zoning form, the fixed-point input of the protective gas can be achieved; at the same time, by dividing the primary monitoring area into a plurality of secondary monitoring areas, when a leak occurs in one of the secondary monitoring areas, suction can be performed through the adjacent secondary monitoring area, so as to achieve rapid removal of liquid cargo in the leaking area.

[0036] Further, as an optional embodiment of the present invention, in the present application, a branch pipe is connected between one of the protection pipelines 3 located in different primary monitoring areas, and a first pressure difference detection device is provided on the branch pipe, and the distances from both ends of the first pressure difference detection device to the gas output end 2 are the same. When the leakage situation of the periphery of the membrane tank is monitored, under normal working conditions, the protective gas input into each protection pipeline 3 flows at a stable rate, and the first pressure difference detection device between each protection pipeline 3 is in a stable state. The working condition of the membrane tank can be known by monitoring the pressure difference data of the first pressure difference detection device. When the membrane tank leaks, the liquid cargo gas in the leakage area increases, and the pressure in the external area of ​​the corresponding protection pipeline 3 increases, which makes it difficult for the gas outlet 304 to discharge the protective gas. Finally, the protective gas output from the protection pipeline 3 to the gas output end 2 increases, and the gas flow rate in the protection pipeline 3 in the leakage area is greater than the gas flow rate in the protection pipeline 3 in the non-leakage area. The first pressure difference detection device generates pressure difference data accordingly, which can be used to determine whether the membrane tank is leaking and the area where the leak is located.

[0037] Further, as an optional embodiment of the present invention, in the present application, a branch pipe is also connected between the two protection pipelines 3 located in different secondary monitoring areas, and a second pressure difference detection device 4 is provided on the branch pipe, and the distances from both ends of the second pressure difference detection device 4 to the gas output end 2 are the same. The function of the second pressure difference detection device 4 is similar to that of the first pressure difference detection device, and the second pressure difference detection device 4 is mainly used to monitor the pressure difference fluctuation within a smaller area, so as to more accurately determine the leakage point of the membrane tank.

[0038] It is worth noting that since there are multiple air outlets 304 distributed on the protection pipeline 3, the gas output pressure of the gas input end 1 is constant. As the air outlets 304 gradually discharge the protective gas, the gas flow rate in the pipeline close to the gas input end 1 is faster, and the gas flow rate in the pipeline close to the gas output end 2 is slower; therefore, by limiting the position where the first pressure difference detection device and the second pressure difference detection device 4 are connected to the protection pipeline 3, it is ensured that under normal maintenance of the diaphragm tank, the gas flow rates at both ends of the pressure difference detection device are close to the same, so as to achieve stable monitoring of the diaphragm tank.

[0039] Furthermore, if Figure 2As shown, as an optional embodiment of the present invention, the protection pipeline 3 in the present application is spirally arranged from the top of the membrane tank to the bottom of the membrane tank, wherein the straight sections 301 are arranged in sequence from top to bottom in a vertically spaced arrangement, and the curved pipe section 302 connects the straight sections 301. The straight section 301 is the main body of the protection pipeline 3. By arranging the straight sections 301 horizontally, when the membrane tank leaks, the straight sections 301 are basically in the same temperature area. The straight sections 301 are expanded and contracted in the horizontal direction, which does not affect the overall shape and structure of the protection pipeline 3, thereby ensuring stable monitoring of the leakage of the membrane tank. The curved pipe section 302 is the connecting part of the straight section 301, which is arranged in the vertical direction. The bending structure of the curved pipe section 302 itself can eliminate the stress of the protection pipeline 3 in the vertical direction, so as to achieve the overall stable connection of the protection pipeline 3. It is worth noting that the protective pipeline 3 at the side walls of the membrane tank in the present application is arranged in this form, and the straight section 301 and the curved section 302 in the protective pipeline 3 at the top and bottom of the membrane tank are all in the same horizontal plane, and its form is basically the same as the arrangement form of the protective pipeline 3 at the side walls of the membrane tank. Moreover, when the membrane tank in the present application is a cylindrical tank structure, in order to realize that the protective pipeline 3 is wrapped around the periphery of the membrane tank, the straight section 301 and the curved section 302 form a curved surface structure wrapped around the periphery of the membrane tank, and at this time, the straight section 301 has a certain curvature, forming a quasi-arc structure.

[0040] Further, as an optional embodiment of the present invention, the air outlet holes 304 in the present application are distributed on each straight section 301, and the air outlet holes 304 are arranged in a non-equidistant manner on the straight section 301, and each adjacent air outlet hole 304 is arranged in a form of gradually decreasing spacing on the pipeline path from the gas input end 1 to the gas output end 2, so that the amount of protective gas output at each location in the distribution area of ​​the protection pipeline 3 is the same. As mentioned above, the gas flow rate of the protection pipeline 3 near the gas input end 1 is larger, and the gas flow rate near the gas output end 2 is smaller. In order to balance the gas output of the area where the protection pipeline 3 is located, the air outlet holes 304 are arranged in a non-equidistant manner, that is, the number of air outlet holes 304 near the gas input end 1 is smaller, and the number of air outlet holes 304 near the gas output end 2 is larger, so as to achieve a balance in the output of the protective gas in a unit area and ensure the uniform distribution of the protective gas around the periphery of the membrane tank.

[0041] Further, as an optional embodiment of the present invention, a third pressure difference detection device 305 is also provided between at least two straight sections 301 in the present application. The third pressure difference detection device 305 is used to identify the pressure difference at different areas inside the protective pipeline 3. When there is no leakage in the membrane tank, the pressure difference between the adjacent or alternately arranged straight sections 301 is basically constant. By judging the pressure difference parameters of the third pressure difference detection device 305, it is determined whether there is a leakage in the area where the protective pipeline 3 is located. At the same time, when the third pressure difference detection device 305 is arranged between adjacent straight sections 301, the third pressure difference detection device 305 can accurately locate the leakage point of the membrane tank. In addition, in order to avoid the leakage point covering the area where the two straight sections 301 are located, resulting in the inability of the second pressure difference detection device 4 to accurately obtain the pressure difference, the third pressure difference detection device 305 can be arranged between multiple alternate straight sections 301 to achieve accurate identification of membrane tank leakage. Optionally, the third pressure difference detection device 305 may also be arranged between adjacent straight sections 301 and between alternate straight sections 301, and the leakage point of the membrane tank may be comprehensively determined by cooperating with multiple third pressure difference detection devices 305.

[0042] The serpentine maintenance piping system for membrane tank protection in the present application realizes zoning and segmented monitoring of the peripheral area of ​​the membrane tank through the coordinated detection of the first pressure difference detection device, the second pressure difference detection device 4 and the third pressure difference detection device 305 at different positions, and can effectively monitor the stable air pressure in the initial stage of membrane tank leakage, the spreading process and the subsequent absorption and treatment process, so as to realize the daily protection of membrane tanks, leakage detection and accurate monitoring of liquid cargo gas removal.

[0043] Furthermore, as an optional embodiment of the present invention, the present application further provides a temperature detection device 306 between at least two straight sections 301. In addition to using pressure detection to determine whether the membrane tank is leaking, the temperature detection device 306 can also be used to directly determine whether the membrane tank is leaking. When the membrane tank leaks, the pressure in the leaking area increases, and the liquid cargo gas leaked from the membrane tank will enter the protection pipeline 3 from the gas outlet 304. The temperature of the liquid cargo gas is lower than that of the protection gas. The temperature detection device 306 can be used to identify whether the liquid cargo gas enters the protection pipeline 3, thereby determining whether the membrane tank is leaking.

[0044] Furthermore, as an optional embodiment of the present invention, the gas input end 1 in the present application is also connected to an intake pressure regulating valve 5 and an intake pressure temperature detection device 6. The intake pressure regulating valve 5 is used to increase the gas input amount of the gas input end 1 to adapt to the high input pressure requirement when the membrane tank leaks; the intake pressure temperature detection device 6 is used to detect the temperature and pressure of the protective gas input at the gas input end 1. The protective gas temperature detection is used to compare with the gas temperature detected by the temperature detection device 306 when the membrane tank leaks to confirm whether the membrane tank is leaking; the protective gas pressure detection is used to determine the protective gas input amount, so as to achieve stable protection of the membrane tank and realize the rational use of the protective gas to avoid excessive waste of the protective gas.

[0045] Further, as an optional embodiment of the present invention, the present application also includes a membrane tank maintenance method, which is maintained by the above-mentioned membrane tank protection serpentine maintenance pipeline system, wherein there are multiple protection pipelines 3, which includes the following steps: S1, inputting protective gas into the peripheral space of the membrane tank through the protective pipeline 3, and extracting the air from the peripheral space of the membrane tank to achieve air replacement in the peripheral space of the membrane tank; S2, continuously inputting protective gas into the peripheral space of the membrane tank through the protective pipeline 3; S3, continuously inputting protective gas into the leakage area, extracting protective gas and liquid cargo gas into the protection pipeline 3 adjacent to the leakage area, and completing the leakage detection of the leakage area; S4. Increase the output of the protective gas in the leakage area, draw the protective gas and liquid cargo gas to the protection pipeline 3 adjacent to the leakage area, and complete the suppression of the liquid cargo leakage in the leakage area.

[0046] Specifically, the present application sets a serpentine maintenance pipeline system for membrane tank protection on the periphery of the membrane tank, and utilizes the serpentine pipeline structure to solve the problem of connection stability of existing pipelines during thermal expansion and contraction, thereby realizing stable delivery of protective gas to the periphery of the membrane tank by the pipeline system; at the same time, the membrane tank maintenance method in the present application forms a plurality of partitioned protection pipelines 3 on the periphery of the membrane tank through the serpentine maintenance pipeline system for membrane tank protection, thereby realizing fixed-point and directional input and output of protective gas, and realizing directional emptying and pressure output of the leakage area of ​​the membrane tank; the directional emptying of the leakage area of ​​the membrane tank can prevent the leaked liquid cargo gas from spreading to the entire peripheral area of ​​the membrane tank, thereby reducing the maintenance cost of the membrane tank; at the same time, the protection pipeline 3 in the leakage area can increase the output of protective gas at the leakage area separately, so as to reduce the pressure difference between the inside and outside of the membrane tank at the leakage point, thereby suppressing the leakage of liquid cargo, so as to reduce the loss caused by the damage of the membrane tank, and realize the precise maintenance of the leakage area of ​​the membrane tank.

[0047] Further, as an optional embodiment of the present invention, the air replacement of the peripheral space of the film tank in step S1 of the present application specifically includes: S101, the gas input end 1 sequentially inputs protective gas into each protective pipeline 3 to inject protective gas into each area outside the membrane tank; the gas output end 2 sequentially extracts the protective gas and air from each area outside the membrane tank through the protective pipeline 3; S102, the protection pipes 3 are arranged in sequence, the gas input end 1 inputs the protection gas to one of the protection pipes 3, and the gas output end 2 extracts the protection gas and the air outside the membrane tank to the protection pipe 3 next to the protection pipe 3; S103, the gas input end 1 inputs the protective gas through the protective pipeline 3 that previously extracted the protective gas, and the gas output end 2 extracts the protective gas and the air outside the membrane tank to the next protective pipeline 3 next to the protective pipeline 3; S104, repeat step S103 until each protection pipeline 3 completes the input of the protection gas.

[0048] The present application firstly inputs protective gas and extracts air to each area outside the membrane tank through each protective pipeline 3, thereby realizing the initial input of protective gas and the initial exhaust of air. Figure 4 As shown; secondly, by inputting protective gas through a protective pipeline 3 and extracting protective gas and air through an adjacent protective pipeline 3, the air in each area outside the membrane tank is emptied at a fixed point, so as to perform carpet-style emptying, ensure that the air outside the membrane tank is emptied, and ensure that the membrane tank is in the atmosphere of protective gas, such as Figure 5 shown.

[0049] Further, as an optional embodiment of the present invention, step S2 of the present application mainly continuously injects protective gas into the peripheral area of ​​the membrane tank through each protective pipeline 3, and at the same time, the gas output end 2 continuously extracts the protective gas in the protective pipeline 3 and the protective gas outside the membrane tank to achieve a dynamic balance of the protective gas in the peripheral area of ​​the membrane tank, so that the membrane tank is in a flowing protective gas atmosphere.

[0050] Further, as an optional embodiment of the present invention, in step S3 of the present application, the present application can determine the leakage area of ​​the membrane tank through the first pressure difference detection device, the second pressure difference detection device 4 and the third pressure difference detection device 305; in order to ensure the accuracy of the judgment of the leakage area of ​​the membrane tank, the present application also needs to continuously input protective gas into the leakage area, and extract the protective gas and liquid cargo gas through the protective pipeline 3 adjacent to the leakage area, and analyze the gas components at the gas output end 2 to further determine whether the membrane tank has a leakage problem.

[0051] Optionally, the present application may also use the temperature detection device 306 to determine whether the membrane tank has a leakage problem.

[0052] Further, as an optional embodiment of the present invention, after the extraction and identification of the liquid cargo gas is completed in step S3 of the present application, it is necessary to extract the liquid cargo gas that has entered the peripheral area of ​​the membrane tank and suppress the leakage of the liquid cargo. Specifically, in step S4, the present application increases the amount of protective gas in the protective pipeline 3 at the leakage area through the gas input end 1, so that the gas outlet 304 outputs more protective gas to increase the amount of protective gas at the leakage area of ​​the membrane tank, and realizes fixed-point pressurization at the leakage area, thereby reducing the internal and external pressure difference of the membrane tank at the leakage position, and then reducing the amount of liquid cargo leakage. At the same time, the protective pipeline 3 adjacent to the leakage point is evacuated to extract the liquid cargo gas discharged from the leakage area to the surrounding area, so as to avoid the leaked liquid cargo gas from polluting the entire peripheral space of the membrane tank and reducing the maintenance cost of the membrane tank. Figure 6 It is worth noting that when the protective pipeline 3 in the leakage area of ​​the membrane tank needs to increase the output of the protective gas, the valve between the gas input end 1 and the protective pipeline 3 can be opened, and the valve between the protective pipeline 3 and the gas output end 2 can be closed, so that the protective gas is discharged from the gas outlet 304 to increase the amount of protective gas in the peripheral area of ​​the membrane tank; correspondingly, the valves between the two protective pipelines 3 on the side of the leakage area and the gas input end 1 are closed, and the valves between the two protective pipelines 3 and the gas output end 2 are opened to form a suction area on both sides of the leakage area of ​​the membrane tank to remove the leaked liquid cargo gas.

[0053] It will be easily understood by those skilled in the art that the above description is only 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 protection scope of the present invention.

Claims

1. A serpentine maintenance piping system for membrane tank protection, characterized in that: include: A gas input end, wherein the gas input end is used to introduce a protective gas; A gas output end, wherein the gas output end is used to output the protective gas and / or liquid cargo gas to the outside; A protection pipeline, which is arranged around the outer periphery of the film tank; one end of the protection pipeline is connected to the gas input end, and the other end is connected to the gas output end; The protection pipeline includes a straight section and a curved section, and the straight section and the curved section are alternately connected to each other so as to be spirally arranged around the outer periphery of the film tank; The straight section is provided with an expansion joint, and the expansion joint can be telescopically arranged; and the straight section and / or the curved pipe section are provided with an air outlet to output the protective gas in the protective pipeline to the outer periphery of the membrane tank.

2. The serpentine maintenance piping system for membrane tank protection according to claim 1, characterized in that: The protective pipelines include a plurality of protective pipelines, each of which is arranged in a different area of ​​the periphery of the film tank; Two ends of each of the protection pipelines are respectively connected to the gas input end and the gas output end, and the protection pipelines are respectively provided with valves on the connecting pipelines connecting the gas input end and the gas output end.

3. The serpentine maintenance piping system for membrane tank protection according to claim 2, characterized in that: The outer periphery of the film tank includes a plurality of primary monitoring areas, and each of the primary monitoring areas includes a plurality of the protection pipelines; Each of the primary monitoring areas includes a plurality of secondary monitoring areas, and each of the protection pipelines is arranged in one-to-one correspondence with each of the secondary monitoring areas.

4. The serpentine maintenance piping system for membrane tank protection according to claim 3 is characterized in that: A branch pipe is connected between one of the protection pipelines located in different primary monitoring areas, and a first pressure difference detection device is provided on the branch pipe. The distances from both ends of the first pressure difference detection device to the gas output end are the same.

5. The serpentine maintenance piping system for membrane tank protection according to claim 3, characterized in that: A branch pipe is connected between the two protection pipelines located in different secondary monitoring areas, and a second pressure difference detection device is arranged on the branch pipe. The distances from both ends of the second pressure difference detection device to the gas output end are the same.

6. The serpentine maintenance piping system for membrane tank protection according to claim 2, characterized in that: The protection pipeline is spirally arranged from the top of the film tank to the bottom of the film tank; The protection pipeline includes a plurality of straight sections arranged in sequence along the vertical direction, each of the straight sections is arranged along the horizontal direction, each of the curved sections is arranged along the vertical direction, and each of the curved sections connects two adjacent straight sections.

7. The serpentine maintenance piping system for membrane tank protection according to claim 6, characterized in that: The gas outlet holes are distributed on each of the straight sections, and each adjacent two gas outlet holes are arranged in a gradually decreasing spacing on the pipeline path from the gas input end to the gas output end.

8. The serpentine maintenance piping system for membrane tank protection according to claim 6, characterized in that: A third pressure difference detection device is connected between at least two of the straight sections.

9. The serpentine maintenance piping system for membrane tank protection according to claim 6, characterized in that: A temperature detection device is also provided between at least two of the straight sections.

10. A membrane tank maintenance method, which is performed by using the membrane tank protection serpentine maintenance pipeline system as claimed in any one of claims 2 to 9, characterized in that: The steps include: S1. Inputting protective gas into the peripheral space of the membrane tank through the protective pipeline, and extracting the air from the peripheral space of the membrane tank to achieve air replacement in the peripheral space of the membrane tank; S2, continuously inputting protective gas into the peripheral space of the membrane tank through the protective pipeline; S3. Continuously input protective gas into the leakage area, extract protective gas and liquid cargo gas into the protection pipeline adjacent to the leakage area, and complete the leakage detection of the leakage area; S4. Increase the output of protective gas in the leakage area, extract protective gas and liquid cargo gas to the protective pipeline adjacent to the leakage area, and complete the suppression of liquid cargo leakage in the leakage area.

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