Liquid cargo containment system and maintenance method

Abstract

The invention discloses a liquid cargo containment system and a maintenance method, and belongs to the technical field of natural gas storage, the liquid cargo containment system comprises a main shielding layer, a secondary shielding layer, an insulating layer and a detection pipeline, one end of the detection pipeline is connected with a gas input pipeline, the other end of the detection pipeline is provided with a first branch pipe and a second branch pipe, and the first branch pipe extends between the main shielding layer and the secondary shielding layer; the first branch pipe extends into the insulating layer, the second branch pipe extends into the insulating layer, a first temperature monitoring unit is arranged in the first branch pipe, a second temperature monitoring unit is arranged in the second branch pipe, and a first pressure difference detection unit is further arranged between the first branch pipe and the second branch pipe. Through dual monitoring of the peripheral temperature and pressure of the thin film tank, accurate monitoring of the liquid cargo leakage condition is ensured, and the problem that the liquid cargo leakage condition is misreported due to pressure fluctuation caused by other factors in a conventional monitoring mode is solved.

Description

Technical Field

[0001] The present invention belongs to the technical field of natural gas storage, and particularly relates to a liquid cargo containment system and a maintenance method. Background Art

[0002] As a clean and efficient energy source, liquefied natural gas is mainly transported through low-temperature atmospheric or pressure storage tanks. Due to its own low-temperature and highly compressed state characteristics, liquefied natural gas requires high sealing requirements and stability requirements during transportation. Based on the transportation regulations of liquefied natural gas, it is usually required that the natural gas storage tank has a cargo containment system with a complete or partially complete secondary shielding space, and the secondary shielding layer is filled with dry protective gas to ensure that when the liquid cargo leaks, it is filled in the atmosphere of the protective gas, avoiding the explosion caused by the mixing of the liquid cargo and air.

[0003] Existing liquid cargo natural gas storage tanks mainly add pressure monitors and gas monitors in the cargo containment system, and judge whether there is leaked liquid cargo invading the cargo containment system by analyzing the gas pressure and components of the cargo containment system. However, although the pressure monitor can quickly identify leaks according to the pressure fluctuations caused by liquid cargo leakage, when the flash steam in the membrane tank increases, it will cause the membrane tank to expand, and then cause the space change between the membrane tank and the containment system, resulting in pressure fluctuations in the area where the protective gas is located, leading to misjudgment of liquid cargo leakage; while the gas monitor needs to specifically analyze the gas components, and its detection and analysis accuracy is relatively high, but the detection efficiency is relatively low. When the gas monitor detects natural gas in the protective gas, the leaked natural gas in the membrane tank has spread in the containment system. Summary of the Invention

[0004] In view of one or more of the above defects or improvement requirements of the prior art, the present invention provides a liquid cargo containment system to solve the problems of liquid cargo leakage detection error and low detection efficiency existing in the existing containment system.

[0005] To achieve the above object, the present invention provides a liquid cargo containment system, which includes:

[0006] A main shielding layer, which encloses to form a liquid cargo accommodation space;

[0007] A secondary shielding layer, which is arranged outside the main shielding layer;

[0008] An insulating layer, which is arranged outside the secondary shielding layer;

[0009] A detection pipeline, one end of which is connected to a gas input pipeline, and the other end is provided with a first branch pipe and a second branch pipe. The first branch pipe extends between the main shielding layer and the secondary shielding layer, and the second branch pipe extends in the insulating layer;

[0010] The space between the main shielding layer and the secondary shielding layer is in communication with the first branch pipe, and a first temperature monitoring unit is provided in the first branch pipe;

[0011] The space within the insulating layer is in communication with the second branch pipe, and a second temperature monitoring unit is provided in the second branch pipe;

[0012] A first differential pressure detection unit is further provided between the first branch pipe and the second branch pipe.

[0013] As a further improvement of the present invention, both the main shielding layer and the secondary shielding layer are formed by welding corrugated plates. The corrugated plates include flat portions and knuckle portions connecting the flat portions, and the knuckle portions are arranged in concave-convex corrugations; one end of the first branch pipe communicating with the space between the main shielding layer and the secondary shielding layer is located between two adjacent knuckle portions.

[0014] As a further improvement of the present invention, the portion of the first branch pipe extending into the space between the main shielding layer and the secondary shielding layer includes a first bent pipe section arranged in an arc shape. The first bent pipe section can be bent and deformed, and through holes communicating with the outside are provided on the first bent pipe section.

[0015] As a further improvement of the present invention, the first temperature monitoring unit is a fiber Bragg grating sensor. The first temperature monitoring unit includes a transmission optical fiber arranged in the first branch pipe, gratings are arranged in series on the transmission optical fiber, and a fiber Bragg grating demodulator is connected to one end of the transmission optical fiber facing the gas input pipeline.

[0016] As a further improvement of the present invention, the portion of the first branch pipe extending into the space within the insulating layer includes a second bent pipe section arranged in an arc shape. The second bent pipe section can be bent and deformed.

[0017] As a further improvement of the present invention, there are multiple detection pipelines, and all the multiple detection pipelines are communicated with the gas output pipeline and the gas input pipeline through branch pipes.

[0018] As a further improvement of the present invention, a second differential pressure detection unit is further provided between two adjacent detection pipelines.

[0019] As a further improvement of the present invention, the gas input pipeline is a nitrogen supply pipeline, and the nitrogen supply pipeline is embedded in the insulating layer; the detection pipeline further includes a gas output pipeline. The first branch pipe is connected to the gas output pipeline, and the gas output pipeline is embedded inside the nitrogen supply pipeline.

[0020] The present application further includes a maintenance method for a liquid cargo containment system, which is maintained through the liquid cargo containment system, and there are multiple detection pipelines. The multiple detection pipelines are all connected to the gas output pipeline and the gas input pipeline through branch pipes, and it includes the following steps:

[0021] Obtain the pressure difference between the first branch pipe and the second branch pipe through the first pressure difference detection unit, compare the pressure difference obtained by the first pressure difference detection unit with the standard pressure difference, and judge whether natural gas leaks according to the difference between the first pressure difference detection unit and the standard pressure difference;

[0022] Obtain the temperatures monitored by the first temperature monitoring unit and the second temperature monitoring unit; obtain the first standard temperature of the space between the main shielding layer and the secondary shielding layer, and obtain the second standard temperature of the space inside the insulating layer; compare the real-time temperature obtained by the first temperature monitoring unit with the first standard temperature to obtain a first difference, and compare the real-time temperature obtained by the second temperature monitoring unit with the second standard temperature to obtain a second difference; judge whether natural gas leaks according to the first difference and the second difference;

[0023] If natural gas leaks, the gas output pipeline evacuates the natural gas at the leakage location through the detection pipeline; if there is no leakage, the first pressure difference detection unit, the first temperature monitoring unit and the second temperature monitoring unit continuously monitor the pressure difference and temperature of the liquid cargo containment system.

[0024] As a further improvement of the present invention, the specific process of the gas output pipeline evacuating the natural gas at the leakage location through the detection pipeline includes:

[0025] The gas output pipeline sucks the gas in the space between the main shielding layer and the secondary shielding layer through the first branch pipe of the detection pipeline at the leakage location; the gas input pipeline injects protective gas into the space between the main shielding layer and the secondary shielding layer through the first branch pipes of the detection pipelines on both sides of the leakage location.

[0026] As long as the above improvement technical features do not conflict with each other, they can be combined with each other.

[0027] Generally speaking, compared with the prior art, the beneficial effects of the above technical solutions conceived by the present invention include:

[0028] (1) The liquid cargo containment system of the present invention monitors the relative pressures in the spaces between the primary shielding layer and the secondary shielding layer and between the secondary shielding layer and the insulation layer through the first differential pressure detection unit. When the pressure difference between the two fluctuates, it indicates that there may be a leak between the primary shielding layer and the secondary shielding layer. On the other hand, the present invention monitors the temperature changes in the spaces between the primary shielding layer and the secondary shielding layer and inside the insulation layer through the first temperature monitoring unit and the second temperature monitoring unit respectively, so as to judge whether there is natural gas leakage from the membrane tank. The present invention monitors the temperature and pressure outside the membrane tank in a dual manner to ensure accurate monitoring of the liquid cargo leakage situation, avoiding the problem of false alarms of liquid cargo leakage caused by pressure fluctuations due to other factors in the conventional monitoring method.

[0029] (2) In the liquid cargo containment system of the present invention, one end of the first branch pipe connecting the space between the primary shielding layer and the secondary shielding layer is located between two adjacent flower joint parts. The two adjacent flower joint parts and the straight part form a concave accommodation space. When the membrane tank undergoes a small contraction or expansion, it will not squeeze the end of the first branch pipe, ensuring the stable detection of the pressure difference by the first differential pressure detection unit and the accuracy of the temperature monitoring by the first temperature monitoring unit.

[0030] (3) In the liquid cargo containment system of the present invention, the gas output pipeline is arranged inside the gas input pipeline. On the one hand, it can slow down the influence of the temperature and pressure in the insulation layer space on the gas output pipeline. On the other hand, it can reduce the installation space required for the gas output pipeline in the insulation layer and save the installation and fixing fittings of the gas output pipeline in the insulation layer. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 is a schematic diagram of the overall structure of the liquid cargo containment system in an embodiment of the present invention;

[0032] Figure 2 is a schematic diagram of the air flow for replacing the gas between the primary shielding layer and the secondary shielding layer in the maintenance method of the liquid cargo containment system in an embodiment of the present invention;

[0033] Figure 3 is a schematic diagram of the air flow for injecting protective gas between the primary shielding layer and the secondary shielding layer in the maintenance method of the liquid cargo containment system in an embodiment of the present invention;

[0034] Figure 4 is a schematic diagram of the air flow for discharging the leaked natural gas in the primary shielding layer in the maintenance method of the liquid cargo containment system in an embodiment of the present invention.

[0035] In all the drawings, the same reference numerals represent the same technical features, specifically:

[0036] 101, Main shielding layer; 102, Secondary shielding layer; 103, Insulating layer; 104, First branch pipe; 105, Second branch pipe; 106, First temperature monitoring unit; 107, Gas input pipeline; 108, First differential pressure detection unit; 109, Straight section; 110, Flower section; 111, First elbow section; 112, Second elbow section; 113, Second differential pressure detection unit; 114, Gas output pipeline. Detailed implementation mode

[0037] In order to make the objectives, technical solutions and advantages of the present invention clearer and more understandable, the present invention will be 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 used 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.

[0038] In the description of the present invention, it should be understood that unless otherwise specified, the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying 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 a limitation of the present invention.

[0039] In addition, unless otherwise specified, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include at least one of such features. In the description of the present invention, "a plurality" means at least two, such as two, three, etc., unless otherwise specifically defined.

[0040] In the present invention, unless otherwise clearly defined and limited, the terms "installed", "connected", "connected", "fixed", etc. should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or integrated; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium. It can be the internal communication of two elements or the interaction relationship between two elements, unless otherwise clearly limited. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0041] In the present invention, unless otherwise clearly specified or limited, the first feature being "on" or "under" the 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, the first feature being "above", "over" and "on top of" the second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the horizontal height of the first feature is higher than that of the second feature. The first feature being "under", "beneath" and "underneath" the second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the horizontal height of the first feature is less than that of the second feature.

[0042] Embodiment:

[0043] Please refer to Figures 1 to 4 , in the liquid cargo containment system of the preferred embodiment of the present invention, there are a primary shielding layer 101, a secondary shielding layer 102 and an insulating layer 103. The primary shielding layer 101 is used to enclose and form a containment space for the liquid cargo. The secondary shielding layer 102 is arranged on the periphery of the primary shielding layer 101 to form a first layer of protection. The insulating layer 103 is arranged on the periphery of the secondary shielding layer 102 to form a second layer of protection; and a detection pipeline, one end of which is connected to a gas input pipeline 107, and the other end of which is provided with a first branch pipe 104 and a second branch pipe 105. The first branch pipe 104 extends between the primary shielding layer 101 and the secondary shielding layer 102. The second branch pipe 105 extends within the insulating layer 103. The space between the primary shielding layer 101 and the secondary shielding layer 102 communicates with the first branch pipe 104, and a first temperature monitoring unit 106 is arranged in the first branch pipe 104. The space within the insulating layer 103 communicates with the second branch pipe 105, and a second temperature monitoring unit is arranged in the second branch pipe 105. Moreover, a first differential pressure detection unit 108 is also arranged between the first branch pipe 104 and the second branch pipe 105.

[0044] Specifically, in the present application, the first branch pipe 104 and the second branch pipe 105 of the detection pipeline respectively extend into the spaces between the main shielding layer 101 and the secondary shielding layer 102, and the insulating layer 103. When the thin-film tank leaks, the natural gas located in the main shielding layer 101 first leaks into the space between the main shielding layer 101 and the secondary shielding layer 102, causing the pressure in the main shielding layer 101 and the secondary shielding layer 102 to fluctuate; secondly, the liquid natural gas in the main shielding layer 101 leaks into the secondary shielding layer 102, causing the temperature in the secondary shielding layer 102 to drop, which in turn affects the temperature of the protective gas in the insulating layer 103, resulting in a pressure fluctuation in the insulating layer 103. At this time, the first differential pressure detection unit 108 located between the first branch pipe 104 and the second branch pipe 105 can detect the differential pressure fluctuation between the two, thereby realizing the leakage monitoring of the thin-film tank. On the other hand, the main shielding layer 101, the secondary shielding layer 102, and the insulating layer 103 are independent of each other, and the spaces between the layers are relatively isolated. When the natural gas in the main shielding layer 101 leaks, it will cause the natural gas to leak into the space between the main shielding layer 101 and the secondary shielding layer 102, thereby causing the temperature of the protective gas between the main shielding layer 101 and the secondary shielding layer 102 to decrease. Since there is no leakage between the secondary shielding layer 102 and the insulating layer 103, the temperature change of the protective gas in the insulating layer 103 is relatively small. At this time, the first temperature monitoring unit 106 and the second temperature monitoring unit can respectively monitor the temperatures in the main shielding layer 101 and the secondary shielding layer 102, and the insulating layer 103. By monitoring the gas temperature between the two layers, the leakage situation of the thin-film tank is judged secondly, realizing the precise monitoring of the liquid cargo leakage situation. The present invention monitors the temperature and pressure outside the thin-film tank in a dual manner to ensure the precise monitoring of the liquid cargo leakage situation, avoiding the problem of false alarms of the liquid cargo leakage situation caused by pressure fluctuations due to other factors in the conventional monitoring method.

[0045] Furthermore, as an optional embodiment of the present invention, the primary shielding layer 101 and the secondary shielding layer 102 are both welded from corrugated sheet metal. The corrugated sheet metal includes multiple straight portions 109 and node portions 110 connecting the straight portions 109. The node portions 110 are arranged in a concave-convex corrugated pattern. One end of the first branch pipe 104, which connects the space between the primary shielding layer 101 and the secondary shielding layer 102, is located between two adjacent node portions 110. To accommodate the contraction of the subcooled liquefied natural gas injected into the membrane tank and the expansion of the membrane tank caused by the vaporization of flash steam, the primary shielding layer 101 is typically made of corrugated sheet metal. The node portions 110, which have concave-convex corrugations, adapt to the expansion and contraction of the membrane tank to prevent damage to the membrane tank. At the same time, one end of the first branch pipe 104 connecting to the space between the main shielding layer 101 and the secondary shielding layer 102 is located between the two adjacent flower nodes 110. The two adjacent flower nodes 110 and the straight portion 109 form a concave accommodating space. When the film tank shrinks or expands slightly, it will not cause squeezing on the end of the first branch pipe 104, ensuring the stable detection of the pressure difference by the first pressure difference detection unit 108 and the accuracy of the temperature monitoring by the first temperature monitoring unit 106.

[0046] Furthermore, as an optional embodiment of the present invention, the portion of the first branch pipe 104 extending into the space between the primary shielding layer 101 and the secondary shielding layer 102 includes a curved first bend section 111. This first bend section 111 is bendable and has a through hole that connects to the outside. When natural gas leaks or flash steam accumulates within the primary shielding layer 101, the membrane tank will deform accordingly, and the sidewalls of the primary and secondary shielding layers 101, 102, will compress the end of the first branch pipe 104, thereby affecting pressure differential and temperature monitoring. To address this issue, the end of the first branch pipe 104 extending into the space between the primary and secondary shielding layers 101, 102, is configured as a curved first bend section 111. When pressure is applied, the first bend section 111 deforms to absorb the pressure between the primary and secondary shielding layers 101, 102, and prevent damage to the first temperature monitoring unit 106 within the first branch pipe 104.

[0047] Furthermore, as an optional embodiment of the present invention, the portion of the first branch pipe 104 extending into the space between the primary shielding layer 101 and the secondary shielding layer 102 includes a first detection section and a second detection section. The first curved section 111 is disposed on the first detection section, the second detection section is disposed between the first detection section and the straight portion 109, and the first temperature monitoring unit 106 is disposed on the second detection section. The first detection section is primarily used to cooperate with the first branch pipe 104 to monitor the pressure between the primary shielding layer 101 and the secondary shielding layer 102, while the second detection section is primarily used to monitor the temperature of the space between the primary shielding layer 101 and the secondary shielding layer 102. The first detection section provides protection outside the second detection section, thereby reducing the possibility of pressure damage to the first temperature monitoring unit 106 therein or affecting the monitoring results.

[0048] Further, as an alternative embodiment of the present invention, the first temperature monitoring unit 106 in the present application is a fiber Bragg grating sensor. The first temperature monitoring unit 106 includes a transmission optical fiber disposed in the first branch pipe 104. A grating is arranged in series on the transmission optical fiber, and an optical fiber Bragg grating demodulator is connected to one end of the transmission optical fiber facing the gas input pipeline 107. The fiber Bragg grating sensor is mainly based on the change of the geometric length and refractive index of the optical fiber caused by temperature change, and analyzes the optical signal through the optical fiber Bragg grating demodulator to realize the monitoring of temperature change. By setting the part of the first branch pipe 104 extending into the space between the main shielding layer 101 and the secondary shielding layer 102 in the form of a first detection section and a second detection section, and forming a protection outside the second detection section through the first detection section, the influence of pressure change on the detection accuracy of the fiber Bragg grating sensor can be reduced.

[0049] Further, as an alternative embodiment of the present invention, the gas input pipeline 107 in the present application is a nitrogen supply pipeline, and the nitrogen supply pipeline is embedded in the insulating layer 103; the detection pipeline further includes a gas output pipeline 114. The first branch pipe 104 is connected to the gas output pipeline 114, and the gas output pipeline 114 is embedded inside the nitrogen supply pipeline. The nitrogen supply pipeline, as the conveying pipeline of the protective gas in the liquid cargo containment system, has relatively high strength and can be isolated from the internal space of the insulating layer 103 to a certain extent. By arranging the gas output pipeline 114 inside the nitrogen supply pipeline, on the one hand, it can slow down the influence of the temperature and pressure in the space of the insulating layer 103 on the gas output pipeline 114, and on the other hand, it can reduce the installation space required for the gas output pipeline 114 to be arranged in the insulating layer 103 and save the installation and fixing fittings of the gas output pipeline 114 in the insulating layer 103.

[0050] Further, as an alternative embodiment of the present invention, the part of the first branch pipe 104 extending into the space of the insulating layer 103 includes a second elbow section 112 arranged in an arc shape, and the second elbow section 112 can be bent and deformed. The space between the main shielding layer 101 and the secondary shielding layer 102 is the first impact area for liquid cargo leakage, and the internal pressure change is relatively large, so the probability of deformation of the first branch pipe 104 is relatively high. In addition, the space in the insulating layer 103 will also shrink or expand to a certain extent due to the temperature change in the space between the main shielding layer 101 and the secondary shielding layer 102. Therefore, the second elbow section 112 is arranged in the space where the first branch pipe 104 extends into the insulating layer 103 to reduce the probability of the first branch pipe 104 being damaged by pressure and improve the overall operation stability of the liquid cargo containment system.

[0051] Further, as an alternative embodiment of the present invention, there are multiple detection pipelines, and the multiple detection pipelines are all connected to the gas output pipeline 114 and the gas input pipeline 107 through branch pipes. Since the overall size of the membrane tank is relatively large, the form of arranging multiple detection pipelines on the outer periphery of the membrane tank can realize the monitoring of different areas of the membrane tank and achieve precise monitoring of the leakage area of the membrane tank. On the other hand, the detection pipelines are all connected to the gas input pipeline 107 and the gas output pipeline 114. When leakage occurs in the area where one of the detection pipelines is located, the form of increasing the output of the protective gas to the leakage position and extracting the mixed gas from the side of the leakage position can be adopted to prevent the leaked natural gas from escaping to other areas and reduce the pollution of the space between the main shielding layer 101 and the secondary shielding layer 102 by the natural gas.

[0052] Further, as an alternative embodiment of the present invention, a second differential pressure detection unit 113 is also provided between two adjacent detection pipelines. When natural gas leakage is detected and identified by one of the detection pipelines, the second differential pressure detection unit 113 can be used to compare the pressures between the two detection pipelines to further ensure the accuracy of differential pressure detection and avoid misjudgment.

[0053] Further, as an alternative embodiment of the present invention, the present invention also includes a maintenance method for a liquid cargo containment system, which includes the following steps:

[0054] Obtain the differential pressure between the first branch pipe 104 and the second branch pipe 105 through the first differential pressure detection unit 108, compare the differential pressure obtained by the first differential pressure detection unit 108 with the standard differential pressure, and judge whether natural gas leakage has occurred according to the difference between the first differential pressure detection unit 108 and the standard differential pressure;

[0055] Obtain the monitored temperatures of the first temperature monitoring unit 106 and the second temperature monitoring unit; obtain the first standard temperature of the space between the main shielding layer 101 and the secondary shielding layer 102, and obtain the second standard temperature of the space inside the insulating layer 103; compare the real-time temperature obtained by the first temperature monitoring unit 106 with the first standard temperature to obtain a first difference, compare the real-time temperature obtained by the second temperature monitoring unit with the second standard temperature to obtain a second difference; judge whether natural gas leakage has occurred according to the first difference and the second difference;

[0056] If natural gas leakage occurs, the gas output pipeline 114 evacuates the natural gas at the leakage position through the detection pipeline; if no leakage occurs, the first differential pressure detection unit 108, the first temperature monitoring unit 106 and the second temperature monitoring unit continuously monitor the differential pressure and temperature of the liquid cargo containment system.

[0057] Further, as an alternative embodiment of the present invention, the extraction of natural gas at the leakage location through the detection pipeline by the gas output pipeline 114 specifically includes: the gas output pipeline 114 sucks the gas in the space between the main shielding layer 101 and the secondary shielding layer 102 through the first branch pipe 104 of the leakage detection pipeline; the gas input pipeline 107 injects a protective gas into the space between the main shielding layer 101 and the secondary shielding layer 102 through the first branch pipe 104 on both sides of the leakage location, such as Figure 4 As shown, the red lines in the figure represent the flow direction schematic of the leakage gas being extracted towards the gas output pipeline 114, and the blue lines in the figure represent the flow direction schematic of the protective gas injected by the gas input pipeline 107 into the space between the main shielding layer 101 and the secondary shielding layer 102.

[0058] Further, as an alternative embodiment of the present invention, before monitoring the liquid cargo containment system, it also includes replacing the air between the main shielding layer 101 and the secondary shielding layer 102 with a protective gas, such as Figure 2 As shown, the red lines in the figure represent the flow direction schematic of the air between the main shielding layer 101 and the secondary shielding layer 102 being extracted towards the gas output pipeline 114, and the blue lines in the figure represent the flow direction schematic of the protective gas injected by the gas input pipeline 107 into the space between the main shielding layer 101 and the secondary shielding layer 102. It includes the following steps:

[0059] S1. Mark each first branch pipe 104 of the detection pipeline in sequence. The gas input pipeline 107 injects a protective gas into the first branch pipe 104 of one of the detection pipelines, and the gas output pipeline 114 extracts the gas from the first branch pipe 104 adjacent to this first branch pipe 104;

[0060] S2. The gas input pipeline 107 injects a protective gas through the first branch pipe 104 from which the gas was extracted last time, and the gas output pipeline 114 extracts the gas from the first branch pipe 104 adjacent to this first branch pipe 104;

[0061] S3. Repeat step S2 until the injection of the protective gas is completed for each first branch pipe 104.

[0062] Further, as an alternative embodiment of the present invention, before monitoring the liquid cargo containment system, it also includes adjusting the gas pressure between the main shielding layer 101 and the secondary shielding layer 102 to a set value, such as Figure 3 As shown, the blue lines in the figure represent the flow direction schematic of the protective gas injected by the gas input pipeline 107 into the space between the main shielding layer 101 and the secondary shielding layer 102. It includes the following steps: the gas input pipeline 107 continuously injects a protective gas into each first branch pipe 104 until the pressure in the space between the main shielding layer 101 and the secondary shielding layer 102 reaches the set pressure value; the gas input pipeline 107 extracts the gas from at least one of the first branch pipes 104 so that the gas output amount of the gas output pipeline 114 is the same as the amount of the protective gas input by the gas input pipeline 107.

[0063] Those skilled in the art can easily understand that the above 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 shall be included within the protection scope of the present invention.

Claims

1. A liquid cargo containment system, characterized in that, Comprising: A main shielding layer which encloses to form a liquid cargo accommodation space; A secondary shielding layer which is arranged outside the main shielding layer; An insulating layer which is arranged outside the secondary shielding layer; A detection pipeline, one end of which is connected to a gas input pipeline, and the other end of which is provided with a first branch pipe and a second branch pipe. The first branch pipe extends between the main shielding layer and the secondary shielding layer, and the second branch pipe extends inside the insulating layer; The space between the main shielding layer and the secondary shielding layer communicates with the first branch pipe, and a first temperature monitoring unit is arranged in the first branch pipe; The space inside the insulating layer communicates with the second branch pipe, and a second temperature monitoring unit is arranged in the second branch pipe; A first differential pressure detection unit is further arranged between the first branch pipe and the second branch pipe.

2. The liquid cargo containment system according to claim 1, characterized in that, Both the main shielding layer and the secondary shielding layer are formed by welding corrugated plates. The corrugated plates include a plurality of flat portions and knuckle portions connecting the flat portions. The knuckle portions are arranged in a concave-convex corrugated shape; One end of the first branch pipe communicating with the space between the main shielding layer and the secondary shielding layer is located between two adjacent knuckle portions.

3. The liquid cargo containment system according to claim 2, characterized in that, The portion of the first branch pipe extending into the space between the main shielding layer and the secondary shielding layer includes a first bent pipe section arranged in an arc shape. The first bent pipe section can be bent and deformed, and through holes communicating with the outside are formed in the first bent pipe section.

4. The liquid cargo containment system according to claim 3, characterized in that, The first temperature monitoring unit is a fiber Bragg grating sensor. The first temperature monitoring unit includes a transmission optical fiber arranged in the first branch pipe. Gratings are arranged in series on the transmission optical fiber. One end of the transmission optical fiber facing the gas input pipeline is connected with a fiber Bragg grating demodulator.

5. The liquid cargo containment system according to claim 3, characterized in that, The portion of the first branch pipe extending into the space inside the insulating layer includes a second bent pipe section arranged in an arc shape. The second bent pipe section can be bent and deformed.

6. The liquid cargo containment system according to claim 1, wherein There are multiple detection pipelines, and all the multiple detection pipelines are connected to a gas output pipeline and the gas input pipeline through branch pipes.

7. The liquid cargo containment system according to claim 6, wherein A second differential pressure detection unit is further arranged between two adjacent detection pipelines.

8. The liquid cargo containment system according to claim 1, characterized in that, The gas input pipeline is a nitrogen supply pipeline which is embedded in the insulating layer; The detection pipeline further includes a gas output pipeline. The first branch pipe is connected to the gas output pipeline, and the gas output pipeline is embedded inside the nitrogen supply pipeline.

9. A maintenance method for a liquid cargo containment system, which is maintained by the liquid cargo containment system described in any one of claims 1 to 8, wherein there are multiple inspection pipelines, and the multiple inspection pipelines are all connected to the gas output pipeline and the gas input pipeline through branch pipes; characterized in that, Including the following steps: Obtain the differential pressure between the first branch pipe and the second branch pipe through the first differential pressure detection unit, compare the differential pressure obtained by the first differential pressure detection unit with the standard differential pressure, and judge whether natural gas leaks according to the difference between the first differential pressure detection unit and the standard differential pressure; Obtain the monitored temperatures of the first temperature monitoring unit and the second temperature monitoring unit; Obtain the first standard temperature of the space between the main shielding layer and the secondary shielding layer, and obtain the second standard temperature of the space inside the insulating layer; Compare the real-time temperature obtained by the first temperature monitoring unit with the first standard temperature to obtain a first difference value. Compare the real-time temperature obtained by the second temperature monitoring unit with the second standard temperature to obtain a second difference value; Judge whether natural gas leaks according to the first difference value and the second difference value; If natural gas leaks, the gas output pipeline evacuates the natural gas at the leakage location through the detection pipeline; if there is no leakage, the first differential pressure detection unit, the first temperature monitoring unit, and the second temperature monitoring unit continuously monitor the differential pressure and temperature of the liquid cargo containment system.

10. The maintenance method of the liquid cargo containment system according to claim 9, characterized in that, The specific process of the gas output pipeline evacuating the natural gas at the leakage location through the detection pipeline includes: The gas output pipeline sucks the gas in the space between the main shielding layer and the secondary shielding layer through the first branch pipe of the detection pipeline at the leakage point; the gas input pipeline injects protective gas into the space between the main shielding layer and the secondary shielding layer through the first branch pipes of the detection pipelines on both sides of the leakage point.

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