Liquefied natural gas leakage early recognition flow guide device and recognition method

Abstract

The invention discloses a liquefied natural gas leakage early-stage identification flow guiding device and an identification method, and belongs to the technical field of natural gas leakage detection.The identification flow guiding device comprises a flange box used for being installed outside a flange of a liquefied natural gas pipeline, the flange box contains a cold insulation material, and a cavity capable of containing the flange is formed in the flange box; the flange box forms a closed structure on the outer side of the liquefied natural gas pipeline and is provided with a flow guide pipe, and the flow guide pipe is communicated with the cavity and the outside of the flange box. The identification method comprises the following steps: observing white fog generated by air condensation at an outlet of the flow guide pipe to judge leakage of liquefied natural gas; liquefied natural gas is guided out through the flow guide pipe, and liquefied natural gas leakage is judged through signals output by the low-temperature detector. According to the device and method, it is ensured that leaked natural gas does not flow out of a pipeline in the cold insulation material any more, large-range leakage diffusion is prevented, leakage can be found in time in the early stage of leakage, leakage is controllable, and the safety risk caused by natural gas leakage is effectively reduced.

Description

Technical Field

[0001] The present application belongs to the technical field of natural gas leakage detection, and in particular, relates to a diversion device and an identification method for early identification of liquefied natural gas leakage. Background Art

[0002] Due to the low temperature characteristics of liquefied natural gas (LNG), its leakage has a destructive effect on steel structures and equipment. The natural gas formed after its gasification has flammable, explosive, fire-hazardous characteristics and suffocating properties. Considering the safety of the facilities, it is necessary to set up an accident collection system to prevent the accidental leakage or spillage of LNG from spreading and spreading, causing secondary disasters. According to the requirements of relevant domestic and foreign LNG station design specifications (GB 50183, GB 51156, NFPA 59A, EN 1473, etc.), a leakage collection system must be set up at the LNG station to safely and centrally handle the leaked LNG to avoid the low temperature damage caused by the low temperature liquefied natural gas spreading everywhere, the pool fire that may occur after the formation of the liquid pool, and the fire and explosion risks caused by the flammable and explosive vapor cloud formed after gasification.

[0003] The LNG collected by the LNG station leakage collection system mainly comes from the leakage at the flange. The leakage collection system is mainly composed of a collection plate, a collection pipe, a collection ditch and a liquid collection pool. The collection plate is located below the leakage source (flange). Whether the collection plate can collect all the leaked LNG is the key to the leakage collection effect. In order to keep the LNG in the low temperature state of the pipeline and equipment, LNG pipelines and equipment generally take cold preservation measures: cold insulation materials are generally used outside the flange. This means that when a leak occurs at the flange, there is a possibility that the leaked LNG will flow along the outer wall of the pipeline in the cold insulation material to both sides or low points. Finally, the leaked LNG leaks from the weakest point of the pipeline cold insulation material to the external environment and cannot be effectively monitored, resulting in leakage or even safety accidents.

[0004] The existing technology does not take the above situation into consideration, and the monitoring of LNG leakage is not comprehensive. There are leakage points, and the collection plate at the leakage point cannot effectively collect the gas, resulting in leakage. The leakage is uncontrollable and may even lead to safety accidents. Summary of the invention

[0005] The present application aims to at least to some extent solve the technical problem of the inability to effectively monitor LNG leaks. To this end, the present application provides a liquefied natural gas leak early identification diversion device and identification method. The leaked natural gas no longer flows out of the pipeline inside the cold insulation material. The leaked LNG can be safely diverted and an LNG leakage signal can be provided. The leakage can be discovered in time at an early stage, and the leakage signal can be distinguished according to the different LNG leakage amounts, so that targeted remedial measures can be taken to effectively reduce the safety risks caused by natural gas leakage.

[0006] In a first aspect, an embodiment of the present application provides a liquefied natural gas leakage early identification and diversion device, which includes:

[0007] The flange box is used to be installed outside the flange of the liquefied natural gas pipeline. The flange box contains cold insulation material. A cavity capable of accommodating the flange is provided inside the flange box. The flange box forms a closed structure outside the liquefied natural gas pipeline. The flange box is provided with a flow guide pipe connecting the cavity and the outside of the flange box.

[0008] The prior art does not take into account the situation where the leaked LNG flows out along the pipeline inside the cold insulation material. Although the prior art can prevent the leaked LNG from flowing outward at the flange to a certain extent, it is actually aimed at how to detect LNG leakage, and does not take into account the above-mentioned outflow situation for drainage. After the leakage is detected, remedial measures can only be taken manually. Some of the prior art will even fail after the leakage occurs, resulting in a larger leakage amount, and cannot solve the problem of LNG leakage. However, the present application keeps the leaked LNG in the flange box through a closed structure, thereby preventing the LNG from flowing out along the liquefied natural gas pipeline. The temperature environment in the liquefied natural gas pipeline is continued to be maintained by the cold insulation material of the flange box. The problem of LNG leakage can be alleviated to a certain extent in the early stage of LNG leakage, and time is bought for relevant personnel to discover the leakage and take measures to ensure that the leakage is controllable, effectively reducing the safety risks caused by natural gas leakage. The leaked LNG can be safely drained out of the flange box through the guide pipe, avoiding the large-scale leakage and spread of LNG, and providing an LNG leakage signal at the outlet of the guide pipe. In this way, once LNG leaks out from the outlet of the guide pipe, it can be discovered in time at the early stage of the leakage, and the leakage signal can be distinguished according to the different LNG leakage amounts. When the leakage amount is small, since the temperature of liquefied natural gas is around -162°C, it will quickly condense the water vapor in the surrounding air at the moment of leakage, resulting in white mist. When the leakage amount is large, liquefied natural gas directly flows out of the guide pipe in liquid form and can be detected by relevant instruments, so as to take targeted remedial measures and effectively reduce the safety risks caused by natural gas leakage. On the other hand, the structure is simple and does not require precision instruments such as pressure gauges, saving costs.

[0009] In an optional embodiment, when the flange box is installed outside the flange, the interface of the flow guide pipe in the flange box is located at the bottom of the flange box, so that the fluid can enter the flow guide pipe under the action of gravity. The flow guide pipe can serve as a channel for fluid diversion. After the flange box is installed, the leaked LNG first flows to the bottom of the flange box under the influence of gravity. The above-mentioned interface setting enables the flow guide pipe to effectively and quickly divert the LNG out.

[0010] In an optional embodiment, the cold insulation material adopts a low-temperature cold insulation material with a temperature resistance of ≦-150°C. The flange box adopts the above-mentioned low-temperature resistant cold insulation material, wherein the cold insulation material is a kind of thermal insulation material in the material field, which keeps the low temperature state of the object. Unlike the thermal insulation material, the cold insulation material is also required to have a certain sealing property; by adopting the above-mentioned low-temperature resistant cold insulation material, the flange box can maintain or maintain the liquefied natural gas transportation temperature environment to a certain extent, thereby reducing the leakage of LNG, and the LNG leakage is controllable.

[0011] In an alternative embodiment, the length of the cavity in the fluid flow direction of the liquefied natural gas pipeline is Wherein, l is the diameter of the flange, and d is the diameter of the liquefied natural gas pipeline. In the height direction, the cavity is firstly able to accommodate the flange, and through the above cavity size setting, a certain space can be maintained in the flange box to reserve accommodation space for LNG leakage.

[0012] In an optional embodiment, in the fluid flow direction of the liquefied natural gas pipeline, the length of the cavity is ≦d, where d is the diameter of the liquefied natural gas pipeline. By setting the cavity size as above, the flange box can keep the LNG in a low temperature state and maintain the cold preservation effect.

[0013] In an optional embodiment, the liquefied natural gas leakage early identification diversion device further includes a seal for sealing the outlet of the diversion pipe, and when the pressure in the cavity increases, the seal can be separated from the diversion pipe or the seal can open the outlet. The seal can be used to seal the outlet of the diversion pipe and open under a certain pressure difference, so as to send a leakage signal in time when LNG leaks.

[0014] In an optional embodiment, the sealing member is made of a non-metallic material with a temperature resistance of ≤-150° C. Through the above arrangement of the sealing member, the low temperature environment in the cavity can be further maintained.

[0015] In an optional embodiment, the diameter of the flow guide pipe ranges from 10 mm to 50 mm. The diameter of the flow guide pipe can smoothly guide the leaked LNG. At the same time, since the collection pipe design of the leakage system complies with the existing domestic and foreign liquefied natural gas station design specifications, the use of the above-mentioned flow guide pipe can adapt to the existing collection pipe.

[0016] In an optional embodiment, the liquefied natural gas leakage early identification and diversion device further includes:

[0017] A collecting plate, used for collecting the fluid flowing out of the outlet of the guide tube;

[0018] A collecting pipe, used to guide the fluid in the collecting tray to the liquid collecting tank, the collecting pipe is connected to the collecting tray;

[0019] The low temperature detector is used to detect the temperature of the fluid flowing out of the outlet of the guide tube, and the low temperature detector is arranged in the collection tray.

[0020] The leaked LNG can be collected by the collecting plate and diverted to the liquid collecting pool through the collecting pipe. The low-temperature detector can detect and send a signal as soon as the LNG flows out of the diversion pipe, which helps relevant personnel take remedial measures.

[0021] In a second aspect, an embodiment of the present application provides a method for early identification of liquefied natural gas leakage, which adopts the above-mentioned liquefied natural gas leakage early identification diversion device, and the identification method includes:

[0022] The white mist produced by air condensation at the outlet of the guide pipe can be used to determine the leakage of liquefied natural gas;

[0023] And / or the guide pipe guides out the liquefied natural gas, and the leakage of liquefied natural gas is determined by the signal output by the low-temperature detector.

[0024] Through the above method, when the leakage is small, it can be visually displayed through physical phenomena, effectively identified and judged, and discovered in time at the early stage of leakage; when the leakage is large, it can be detected by relevant instruments, and the signal is directly transmitted to relevant personnel, and it can also be discovered in time when the leakage occurs; in this way, the leakage signal can be distinguished according to the different LNG leakage amounts and adapt to different LNG leakage situations. Therefore, LNG leakage can be efficiently discovered, targeted remedial measures can be taken, and the safety risks caused by natural gas leakage can be effectively reduced.

[0025] It can be seen from the above technical solution that the beneficial effects of this application are:

[0026] 1. The identification and diversion device keeps the leaked LNG in the flange box through a closed structure, thereby preventing LNG from flowing out along the liquefied natural gas pipeline. The temperature environment in the liquefied natural gas pipeline is continued to be maintained through the cold insulation material of the flange box. The problem of LNG leakage can be alleviated to a certain extent in the early stage of LNG leakage, and time is gained for relevant personnel to discover the leakage and take measures, thereby ensuring that the leakage is controllable and effectively reducing the safety risks caused by natural gas leakage. The leaked LNG can be safely diverted out of the flange box through the diversion pipe, thereby preventing the large-scale leakage and diffusion of LNG, and providing an LNG leakage signal at the outlet of the diversion pipe. In this way, once LNG flows out from the outlet of the diversion pipe and leaks, it can be discovered in time at the early stage of leakage, so that targeted remedial measures can be taken to effectively reduce the safety risks caused by natural gas leakage.

[0027] 2. When the leakage volume is small, this identification method can be effectively identified and judged through intuitive display of physical phenomena, and can be discovered in time at the early stage of leakage; when the leakage volume is large, it can be detected by relevant instruments, and the signal is directly transmitted to relevant personnel, and can also be discovered in time when the leakage occurs; in this way, the leakage signal can be distinguished according to the different LNG leakage volumes, adapting to different LNG leakage situations, so that LNG leakage can be efficiently discovered, and the safety risks caused by natural gas leakage can be effectively reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following is a brief introduction to the drawings required for use in the description of the embodiments. Obviously, the drawings described below are some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0029] Figure 1 A cross-sectional schematic diagram of an embodiment of a liquefied natural gas leakage early detection and diversion device is shown.

[0030] Figure 2 A cross-sectional schematic diagram of an installation scenario of an embodiment of a liquefied natural gas leakage early identification and diversion device is shown.

[0031] Figure 3 A schematic diagram of an installation scenario of an embodiment of a liquefied natural gas leakage early identification and diversion device after a portion of a flange box is removed is shown.

[0032] Figure 4 A schematic diagram of an application scenario of an embodiment of a liquefied natural gas leakage early identification and diversion device is shown.

[0033] Figure 5 A schematic diagram of an embodiment of a method for early identification of liquefied natural gas leakage is shown.

[0034] Figure numerals: 1. pipeline insulation layer; 2. liquefied natural gas pipeline; 3. flange; 4. flange box; 5. flow guide tube; 6. sealing member; 7. collecting tray; 8. collecting tube; 9. low temperature detector. DETAILED DESCRIPTION

[0035] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0036] It should be noted that all directional indications in the embodiments of the present invention are only used to explain the relative position relationship, movement status, etc. between various components in a certain specific posture. If the specific posture changes, the directional indication will also change accordingly.

[0037] In the present invention, unless otherwise clearly specified and limited, the terms "connection", "fixation", etc. should be understood in a broad sense. For example, "fixation" 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.

[0038] In addition, in the present invention, descriptions such as "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying their 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 addition, the technical solutions between the various embodiments can be combined with each other, but they must be based on the ability of ordinary technicians in the field to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0039] The present application is described below with reference to the accompanying drawings and specific embodiments:

[0040] Please refer to Figure 1The first embodiment of the present application provides an early identification and diversion device for liquefied natural gas leakage. The identification and diversion device is installed at the flange 3 of the liquefied natural gas pipeline 2. The liquefied natural gas pipeline 2 is provided with a pipeline cold insulation layer 1 to maintain the transportation environment of the liquefied natural gas. The identification and diversion device includes: a flange box 4, which is used to be installed outside the flange 3 of the liquefied natural gas pipeline 2. The flange box 4 is used in combination with the flange 3 on the liquefied natural gas pipeline 2. The flange box 4 is box-shaped. In the radial direction of the flange 3, the flange box 4 is circular. It can also be square, elliptical, triangular or other shapes. It is sufficient to ensure that the flange 3 can be located in the flange box 4 when in use. The flange box 4 is provided with a cavity that can accommodate the flange 3. The flange box 4 wraps the flange 3 in the cavity. The shape of the cavity can also be a variety of different shapes, including cylindrical, cube, rectangular, etc. It is sufficient to ensure that the cavity can accommodate the flange 3, and the cavity has a certain LNG holding capacity in addition to the flange 3. The flange box 4 forms a closed structure on the outside of the liquefied natural gas pipeline 2. The cavity is enclosed inside, and the inner edge of the flange box 4 is connected, fixed and sealed to the outer wall of the liquefied natural gas pipeline 2 by welding or the flange box 4 is a detachable structure. If the flange box 4 adopts a detachable structure, a sealing ring or sealant is required at the connection between the flange box 4 and the liquefied natural gas pipeline 2; in other embodiments, the flange box 4 can also be connected and fixed to the flange 3; the flange box 4 contains a cold insulation material, and a cold insulation material layer is coated on the inner wall and the outer wall of the flange box 4, or the cold insulation material and the cold insulation material layer are used when the flange box 4 is manufactured. The flange box 4 is provided with a guide tube 5, one end of the guide tube 5 is connected to the flange box 4, and this end of the guide tube 5 is connected to the cavity in the flange box 4, and the other end of the guide tube 5 is located outside the flange box 4, so that the guide tube 5 connects the cavity and the outside of the flange box 4.

[0041] The identification and diversion device keeps the leaked LNG in the flange box 4 through a closed structure, thereby preventing the LNG from flowing out along the liquefied natural gas pipeline 2. The temperature environment in the liquefied natural gas pipeline 2 is continued to be maintained by the cold insulation material of the flange box 4, which can alleviate the problem of LNG leakage to a certain extent in the early stage of LNG leakage, buy time for relevant personnel to discover the leakage and take measures, ensure that the leakage is controllable, and effectively reduce the safety risks caused by natural gas leakage. The leaked LNG can be safely diverted out of the flange box 4 through the diversion pipe 5 and collected in the liquid collecting pool, thereby preventing the large-scale leakage and spread of LNG, and providing an LNG leakage signal at the outlet of the diversion pipe 5. In this way, once LNG flows out from the outlet of the diversion pipe 5 and leaks, it can be discovered in time at the early stage of leakage, so that targeted remedial measures can be taken to effectively reduce the safety risks caused by natural gas leakage. On the other hand, the structure is simple and does not require precision instruments such as pressure gauges, saving costs.

[0042] When LNG flows out from the outlet of the guide pipe 5, a leakage signal appears. The leakage signal can be distinguished according to the different amounts of LNG leakage. When the leakage is small, since the temperature of liquefied natural gas is around -162°C, the water vapor in the surrounding air will be quickly condensed at the moment of leakage, and white mist will appear, which can intuitively remind relevant personnel of the leakage. When the leakage is large, the liquefied natural gas directly flows out of the guide pipe 5 in liquid form, which can be detected by relevant instruments, thereby sending a leakage signal.

[0043] Please refer to Figure 2 In an optional embodiment, when the flange box 4 is installed outside the flange 3, the interface of the guide tube 5 in the flange box 4 is located at the bottom of the flange box 4, so that the fluid can enter the guide tube 5 under the action of gravity; the guide tube 5 adopts a straight tube, and can also adopt a curved tube. When the flange box 4 is used as a product, there is no top-bottom and up-down position relationship. The guide tube 5 is connected to the flange box 4. When the flange box 4 is installed and fixed at the flange 3, the flange box 4 has a top and a bottom. The part of the flange box 4 connected with the guide tube 5 serves as the bottom of the flange box 4. At this time, the flange box 4 has an up-down relationship, so that the guide tube 5 faces downward. In this way, the guide tube 5 can be used as a channel for fluid diversion. After the flange box 4 is installed, the leaked LNG first flows to the bottom of the flange box 4 under the influence of gravity. The above-mentioned interface setting enables the guide tube 5 to effectively and quickly divert the LNG out. In an optional embodiment, the diameter of the guide pipe 5 ranges from 10 mm to 50 mm. For example, if a diameter value of 10 mm, 50 mm or therebetween is used, under this diameter, the LNG flowing out of the guide pipe 5 can correspond to the collecting pipe 8 entering the leakage system, which is convenient for the collection of LNG and avoids the diffusion of LNG. The diameter setting of the guide pipe 5 can smoothly guide the leaked LNG. At the same time, since the design of the collecting pipe 8 of the leakage system conforms to the existing domestic and foreign liquefied natural gas station design related specifications, the use of the above-mentioned guide pipe 5 can adapt to the existing collecting pipe 8.

[0044] In an optional embodiment, the cold insulation material adopts a low-temperature cold insulation material with a temperature resistance of ≤-150°C, such as -150°C, -160°C, -162°C or temperatures therebetween, or other temperatures below -150°C. In order to ensure the transportation environment of liquefied natural gas and maintain the state of liquefied natural gas, the pipeline cold insulation layer 1 adopts a low-temperature cold insulation material that is resistant to -162°C, and the flange box 4 also adopts a low-temperature cold insulation material that is resistant to -162°C, such as a composite cold insulation material: a composite material of polyurethane foam wrapped in aluminum-plated iron sheet. The cold insulation material used in the flange box 4 can be the same as the material of the pipeline cold insulation layer 1, or different, as long as it is ensured that the flange box 4 can maintain the above-mentioned low temperature, and the cold insulation material is provided on the inner wall of the cavity of the flange box 4 in a coating manner, or a layered structure of the cold insulation material is adopted, or the flange box 4 is made of the cold insulation material, and the sealing of the flange box 4 and the liquefied natural gas pipeline 2 must be ensured. The flange box 4 adopts the above-mentioned low-temperature resistant cold insulation material, wherein the cold insulation material is a kind of thermal insulation material in the material field, which keeps the object in a low-temperature state. Unlike the thermal insulation material, the cold insulation material is also required to have a certain sealing performance; by adopting the above-mentioned low-temperature resistant cold insulation material, the flange box 4 can maintain or maintain the transportation temperature environment of liquefied natural gas to a certain extent, thereby reducing the leakage of LNG and making the LNG leakage controllable.

[0045] Please refer to Figure 3 In an optional embodiment, the length of the cavity refers to the size of the cavity in the fluid flow direction of the liquefied natural gas pipeline 2. In an optional embodiment, in the fluid flow direction of the liquefied natural gas pipeline 2, the length of the cavity is ≦d, where l is the diameter of the flange 3 and d is the diameter of the liquefied natural gas pipeline 2. In the height direction, the cavity is firstly able to accommodate the flange 3, that is, the height of the entire cavity is greater than the outer diameter of the flange 3, and in the horizontal direction of the figure, the length of the cavity is limited to a certain extent, and the length of the cavity cannot be too small or too large. The minimum value of the cavity length needs to have a gap on the basis of accommodating the flange 3. Through the setting of the cavity size, a certain space can be maintained in the flange box 4 to reserve accommodation space for LNG leakage. The maximum value of the cavity length enables the flange box 4 to still maintain a low temperature. Through the setting of the cavity size, the flange box 4 can maintain the low temperature state of LNG and maintain the cold preservation effect.

[0046] In an optional embodiment, the liquefied natural gas leakage early identification diversion device further includes a seal 6, which is used to close the outlet of the diversion pipe 5. The seal 6 is separately arranged from the diversion pipe 5, that is, the seal 6 is a separate structure, such as a sealing plug or a sealing cap, which blocks the outlet of the diversion pipe 5 by the sealing plug, or covers and seals the outlet of the diversion pipe 5 by the sealing cap. The seal 6 can also be arranged at the outlet of the diversion pipe 5. For example, if a micro differential pressure valve is used, the seal 6 can be opened when a preset differential pressure value range appears between the flange box 4 and the outside world, and can remain in the open state after opening; as a structure connected or arranged with the diversion pipe 5, the seal 6 must first ensure that the outlet of the diversion pipe 5 can be sealed, and then the seal 6 can be separated from the diversion pipe 5 or the seal 6 can open the outlet when the pressure in the cavity increases. For example, the sealing plug or the sealing cap is opened after the LNG leaks into the cavity to a certain amount, and the leaked LNG is displayed at the outlet of the diversion pipe 5 through physical phenomena or detected by an instrument, so that a leakage signal can be issued in time when LNG leaks. In an optional embodiment, the seal 6 is made of a non-metallic material with a temperature resistance of ≤ -150°C. The seal 6 can be made of a low-temperature resistant non-metallic material of -150°C, -160°C, -162°C or temperatures therebetween, or other temperatures below -150°C, such as a material made of polytrifluorochloroethylene. Through the above-mentioned setting of the seal 6, the low-temperature environment in the cavity can be further maintained.

[0047] Please refer to Figure 4 In an optional embodiment, the identification and diversion device further includes: a collecting tray 7, a collecting tube 8 and a low-temperature detector 9. The collecting tray 7 is used to collect the fluid flowing out of the outlet of the diversion tube 5. The collecting tray 7 is in the shape of a tray. The edge of the collecting tray 7 has an upwardly protruding bent edge to prevent the fluid from diffusing. A through hole is provided in the middle of the collecting tray 7. The surface of the collecting tray 7 can be a flat surface or a slope similar to a funnel, and the fluid can smoothly enter the through hole. The bottom of the through hole of the collecting tray 7 is connected to the collecting tube 8. The collecting tube 8 is used to divert the fluid in the collecting tray 7 to the liquid collecting pool. The collecting tube 8 is always connected to the liquid collecting pool of the leakage system. The collecting tray 7 and the collecting tube 8 can also adopt the structure of the existing leakage system; a low-temperature detector 9 is arranged on the surface of the collecting tray 7. The low-temperature detector 9 is used to detect the temperature of the fluid flowing out of the outlet of the diversion tube 5. The low-temperature detector 9 is directly opposite to the outlet of the diversion tube 5, or is arranged next to the above-mentioned outlet. The leaked LNG can be collected by the collecting tray 7 and directed to the liquid collecting tank through the collecting pipe 8. The low-temperature detector 9 can detect and send a signal as soon as the LNG flows out of the guide pipe 5, which helps relevant personnel to take remedial measures.

[0048] The second aspect of the present application is an embodiment of a method for early identification of liquefied natural gas leakage, which adopts the above-mentioned liquefied natural gas leakage early identification diversion device.

[0049] Please refer to Figure 5The identification method includes two situations, corresponding to different identification methods S1 and S2. Among them, S1 and S2 are not in any order. Different identification methods are used for different situations. In some cases, one of S1 and S2 may appear, or the identification of S1 and S2 may occur at the same time.

[0050] S1. When the LNG leakage is small, that is, when the liquefied natural gas leaks from a small hole (0-5 mm) at the flange 3, the LNG leakage is not enough to form liquid flow in the collecting tray 7. The leakage scene cannot be detected by the low-temperature detector 9 installed on the collecting tray 7, so it is difficult to be found. The leaked liquefied natural gas first leaks into the internal cavity of the flange box 4, accompanied by the evaporation of LNG. As the amount of evaporated natural gas increases, the gas phase pressure of the internal cavity of the flange box 4 increases. When the pressure increases to a certain extent, under the action of the pressure difference between the inside and outside of the flange box 4, the seal 6 opens. The opening form of the seal 6 is similar to that of the liquefied natural gas. The embodiments of the diversion device for early identification of natural gas leakage include various methods. For example, the sealing cap on the diversion pipe 5 is pushed open by natural gas, and the pressure in the cavity is released instantly. The natural gas flowing out of the diversion pipe 5 can quickly condense the water vapor in the air due to its low temperature (about -162°C), and white mist appears. By observing the appearance of white mist, it can be determined that the liquefied natural gas is leaking. Since LNG has been leaking, the diversion pipe 5 has been in an open state, and white mist has been appearing. The white mist can be discovered by the inspection personnel in time. At the same time, since the leakage amount is small and not enough to cause an accident, the inspection personnel are allowed to discover the leakage at a certain interval.

[0051] S2. When the LNG leakage is large, that is, when a large hole (5-50 mm) of liquefied natural gas leaks at the flange 3, the leaked LNG flows out through the guide pipe 5 and enters the collecting tray 7 to form a liquid flow, which is then collected by the collecting pipe 8 to form a liquid collecting pool, thereby avoiding the large-scale leakage and diffusion of LNG. The leakage scenario can be detected by the low-temperature detector 9 installed on the collecting tray 7. The leakage of liquefied natural gas can be judged by the signal output by the low-temperature detector 9. The alarm can be electrically connected to the low-temperature detector 9. After the alarm receives the leakage signal of the low-temperature detector 9, it triggers an alarm, and relevant personnel take remedial measures in time.

[0052] Through the above methods S1 and S2, when the leakage is small, it can be visually displayed through physical phenomena, effectively identified and judged, and discovered in time at the early stage of leakage; when the leakage is large, it can be detected by relevant instruments, and the signal is directly transmitted to relevant personnel, and it can also be discovered in time when the leakage occurs; in this way, the leakage signal can be distinguished according to the different LNG leakage amounts and adapt to different LNG leakage situations. Therefore, LNG leakage can be efficiently discovered, targeted remedial measures can be taken, and the safety risks caused by natural gas leakage can be effectively reduced.

[0053] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", "optional example" or "optional implementation" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification.

[0054] In addition, the technical solutions between the various embodiments can be combined with each other, but they must be based on the fact that they can be implemented by ordinary technicians in this field. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such combination of technical solutions does not exist and is not within the scope of protection required by this application.

[0055] Although the embodiments of the present application have been shown and described, those skilled in the art will appreciate that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present application, and that the scope of the present application is defined by the claims and their equivalents.

Claims

1. A liquefied natural gas leakage early identification and diversion device, characterized in that: include: A flange box is used to be installed outside the flange of a liquefied natural gas pipeline. The flange box contains cold insulation material. A cavity capable of accommodating the flange is provided inside the flange box. The flange box forms a closed structure outside the liquefied natural gas pipeline. The flange box is provided with a flow guide pipe, which connects the cavity and the outside of the flange box.

2. The liquefied natural gas leakage early identification and diversion device according to claim 1 is characterized in that: When the flange box is installed outside the flange, the flow guide pipe is located at the bottom of the flange box at the interface of the flange box, so that the fluid can enter the flow guide pipe under the action of gravity.

3. The liquefied natural gas leakage early identification and diversion device according to claim 1 is characterized in that: The cold-insulating material is a low-temperature cold-insulating material with a temperature resistance of ≤-150°C.

4. The liquefied natural gas leakage early identification and diversion device according to claim 3 is characterized in that: In the fluid flow direction of the liquefied natural gas pipeline, the (ld), wherein l is the diameter of the flange and d is the diameter of the liquefied natural gas pipeline.

5. The liquefied natural gas leakage early identification and diversion device according to claim 4 is characterized in that: In the fluid flow direction of the liquefied natural gas pipeline, the length of the cavity is ≦d, wherein d is the diameter of the liquefied natural gas pipeline.

6. The liquefied natural gas leakage early identification and diversion device according to claim 1 is characterized in that: The invention also comprises a sealing member for closing the outlet of the flow guide tube. When the pressure in the cavity increases, the sealing member can be separated from the flow guide tube or the sealing member can open the outlet.

7. The liquefied natural gas leakage early identification and diversion device according to claim 6 is characterized in that: The sealing element is made of non-metallic material with a temperature resistance of ≤-150°C.

8. The liquefied natural gas leakage early identification and diversion device according to any one of claims 1 to 7, characterized in that: The diameter of the flow guide pipe ranges from 10 mm to 50 mm.

9. The liquefied natural gas leakage early identification and diversion device according to any one of claim 8, characterized in that: Also includes: A collecting plate, used for collecting the fluid flowing out of the outlet of the guide tube; A collecting pipe, used to guide the fluid in the collecting tray to the liquid collecting tank, the collecting pipe being connected to the collecting tray; A low temperature detector is used to detect the temperature of the fluid flowing out of the outlet of the guide tube, and the low temperature detector is arranged in the collection tray.

10. A method for early identification of liquefied natural gas leakage, characterized in that: The liquefied natural gas leakage early identification and diversion device according to any one of claims 1 to 9 is used, and the identification method includes: The white mist produced by the condensation of air at the outlet of the guide pipe can be observed to determine the leakage of liquefied natural gas; And / or the guide pipe guides out liquefied natural gas, and the leakage of liquefied natural gas is determined by the signal output by the low-temperature detector.

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