Heatable low-temperature pipeline

Abstract

The invention relates to the technical field of liquid cargo conveying, in particular to a heatable low-temperature pipeline. A heatable low-temperature pipeline comprises a transportation section, the inner wall of the transportation section is used for making direct contact with liquefied natural gas, a heating strip made of ferromagnetic metal and used for making contact with the liquefied natural gas is fixedly arranged in the transportation section, a wire is arranged on the transportation section and located on the outer side of the heating strip, and the wire is spirally arranged. The wire and the heating strip are coaxially arranged, and the wire is further provided with a connecting end used for being connected to alternating current so that the heating strip can be electromagnetically heated when the wire is connected to the alternating current. When alternating current is supplied to the wire, a magnetic field is generated around the wire, and the alternating current is supplied, so that the magnetic field is always changed, the heating strip is conveniently heated, and the problem that in the prior art, a part of liquefied natural gas is left in a pipeline after the low-temperature hose is used, and the heating strip is damaged is solved. And residual liquefied natural gas is not easy to clean.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of liquid cargo transportation, and in particular to a low-temperature pipeline capable of being heated. BACKGROUND

[0002] With increasingly stringent requirements for ship exhaust emission limits, the adoption of natural gas power systems by ships has become a future development trend for ship power, and natural gas will become the preferred fuel for future green and environmentally friendly ships due to its high calorific value, lack of sulfur, clean combustion, and low emissions.

[0003] During fuel filling or cargo transfer, low-temperature hoses are required, such as the application of low-temperature hoses to LNG transfer pipelines between LNG storage and transportation ships and LNG-powered ships and LNG shore stations. Due to the need to overcome the static displacement difference between the two ship filling stations and the dynamic fluctuations of wind and waves during ship-to-ship LNG transfer, the shipping industry usually uses flexible low-temperature hoses to connect the LNG transfer pipelines of the two ships.

[0004] The existing ship-to-ship LNG transfer low-temperature hose is usually designed in a "U" shape, and a certain amount of low-temperature LNG residue at minus 163℃ is left in the lowest position of the low-temperature hose section after LNG transfer is completed. The ship usually passes normal temperature nitrogen into the low-temperature hose to heat and treat the LNG residue, and at the same time, the evaporated natural gas is driven away from the low-temperature hose. In order to further improve the heating rate, the crew will also arrange to spray seawater from the outside of the low-temperature hose with a water gun. During the treatment of LNG residue in the low-temperature hose, not only does it increase the workload of the crew, but it also takes a long time, has poor results, and reduces the service life of the low-temperature hose. SUMMARY

[0005] Therefore, the present application provides a low-temperature pipeline capable of being heated to solve the problem that a portion of liquid natural gas is left in the pipeline after the use of the low-temperature hose in the prior art, and the left liquid natural gas is not easy to clean.

[0006] A low-temperature pipeline capable of being heated, comprising a transportation section, an inner wall of the transportation section being used for direct contact with liquid natural gas, a heating strip made of a ferromagnetic metal for contact with the liquid natural gas being fixedly arranged in the transportation section, the heating strip being spirally arranged on the inner wall surface of the transportation section, a wire being arranged on the transportation section and located on the outer side of the heating strip, the wire being spirally arranged, the wire and the heating strip being coaxially arranged, and a connecting end for being connected to an alternating current being further arranged on the wire, so that the heating strip can be electromagnetically heated when the wire is connected to the alternating current.

[0007] Further, the transportation section is arranged in layers, the transportation section comprising an inner sealing layer for contact with the liquid natural gas and a protective layer located on the outer side of the inner sealing layer, and the wire being located between the inner sealing layer and the protective layer.

[0008] Further, the wire comprises an insulating layer and a conductor located in the insulating layer.

[0009] Further, a layer of fiber material is arranged on the inner surface and / or the outer surface of the inner sealing layer.

[0010] Further, the two ends of the heatable cryogenic pipeline are provided with connecting flanges fixedly connected with the transportation section.

[0011] Further, a sensor mounting hole for accommodating a temperature sensor is arranged on the connecting flange, the temperature sensor is arranged in the sensor mounting hole, and a first data line for transmitting a signal to the outside of the heatable cryogenic pipeline is arranged on the temperature sensor.

[0012] Further, the two ends of the heatable cryogenic pipeline are provided with connecting flanges fixedly connected with the transportation section, and an annular clamping groove for clamping cooperation with the protective layer is arranged on the outer peripheral surface of the connecting flange.

[0013] Further, a stress sensor for detecting the stress on the heating strip is arranged on the side surface of the heating strip, and a second data line for transmitting a signal to the outside of the heatable cryogenic pipeline is arranged on the stress sensor.

[0014] Further, the heatable cryogenic pipeline further comprises a controller connected to the connecting end of the wire, and the controller is used to control the current on the wire.

[0015] The heatable cryogenic pipeline has the following advantages: the heatable cryogenic pipeline is used for contact with liquid natural gas through the transportation section, which facilitates the transfer and filling of liquid natural gas; the heating strip is arranged in the transportation section for contact with liquid natural gas, which facilitates the heating of liquid natural gas; the wire is arranged on the transportation section and outside the heating strip, which facilitates the heating of the heating strip; when the wire is connected to alternating current, a magnetic field is generated around the wire, and since the wire is connected to alternating current, the magnetic field is always changing, which facilitates the heating of the heating strip; since the wire and the heating strip are arranged in a spiral, the magnetic field and the heating power are enhanced, which facilitates the heating of the pipeline after use; since the residual liquid natural gas is heated to become gas and volatilize, the residual liquid natural gas in the pipeline can be effectively cleaned; in addition, the heating strip is not directly connected to the power supply, but is heated by induction, so that the heating strip does not need to pass through the pipeline, which is beneficial to maintaining the performance of the pipeline, thereby solving the problem that a part of liquid natural gas remains in the pipeline after the use of the low-temperature hose in the prior art, and the residual liquid natural gas is not easy to clean. BRIEF DESCRIPTION OF DRAWINGS

[0016] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following will briefly introduce the drawings needed to be used in the embodiments. Obviously, the drawings described below only show some of the embodiments of the present application, and for those skilled in the art, other drawings can also be obtained from these drawings without creative labor.

[0017] Figure 1 A sectional view of the embodiment of the heatable cryogenic pipeline in the present application;

[0018] Figure 2 A local enlarged view of the embodiment of the heatable cryogenic pipeline in the present application.

[0019] The meanings of the reference numerals in the drawings are as follows: 1, connecting flange; 2, protective layer; 3, inner sealing layer; 4, controller; 5, inner spiral steel wire; 6, outer winding cable; 7, temperature sensor; 8, stress sensor. DETAILED DESCRIPTION

[0020] In order to make the objects, technical solutions and advantages of the present application clearer, the following will describe the present application through specific embodiments shown in the drawings. However, it should be understood that these descriptions are only exemplary, and are not intended to limit the scope of the present application. In addition, in the following description, the description of the known structures and technologies is omitted to avoid unnecessary confusion of the concept of the present application.

[0021] The terms used in the present disclosure are merely for the purpose of describing specific embodiments, and are not intended to limit the present disclosure. The singular forms "a", "an" and "the" used in the present disclosure and the appended claims are also intended to include the plural forms, unless the context clearly indicates otherwise. It should also be understood that the term "and / or" used herein refers to and includes any or all possible combinations of one or more associated listed items.

[0022] It should be understood that although the terms first, second, third, etc. can be used in the present disclosure to describe various information, these information should not be limited to these terms, and should not be understood as indicating or implying relative importance. These terms are only used to distinguish one type of information from another type of information. For example, without departing from the scope of the present disclosure, the first information can also be referred to as the second information, and similarly, the second information can also be referred to as the first information. Depending on the context, the word "if" as used herein can be interpreted as "when" or "upon determination" or "in response to determining".

[0023] In the description of the present application, it is to be understood by the terms "longitudinal", "transverse", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer" and the like indicate the orientation or positional relationship shown in the drawings, which are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application.

[0024] In the description of the present application, unless otherwise specified and limited, it is to be noted that the terms "mounting", "connecting", "connecting" should be understood broadly, for example, it can be mechanical connection or electrical connection, it can be the communication between two elements inside, it can be directly connected, or indirectly connected through intermediate medium, for those skilled in the art, the specific meaning of the above terms can be understood according to the specific circumstances.

[0025] In the subsequent description, the suffix such as "module", "component" or "unit" used to represent the element is only for the convenience of the description of the present application, and has no specific meaning. Therefore, "module" and "component" can be used interchangeably.

[0026] In order to better understand the technical solutions of the present application, the present application will be described in detail below in conjunction with the drawings.

[0027] In the embodiment 1 of the low-temperature pipeline that can be heated in the present application:

[0028] As shown in Figure 1 and Figure 2 The low-temperature pipeline that can be heated in the present application includes a transportation section for contacting and transporting liquid natural gas, and connecting flanges 1 for fixed connection with ships or other equipment are arranged at both ends of the transportation section, the connecting flanges 1 adopt national standards, bolt mounting holes are arranged on the connecting flanges 1 for fixed connection with other ships or equipment. The specifications of the connecting flanges 1 at both ends are selected according to actual needs to ensure the universality of installation.

[0029] The transport section has a double-layer structure, specifically including an inner sealing layer 3 near the inside, which is made of polymer film (such as polytetrafluoroethylene). A protective layer 2, made of corrosion-resistant and low-temperature-resistant stainless steel, is also provided on the outside of the inner sealing layer 3 to protect it. A gap exists between the inner sealing layer 3 and the protective layer 2. Fiber material layers can be added to the inner and outer surfaces of the inner sealing layer 3, and a heat insulation layer can be added to the inner surface of the protective layer 2. Since liquid natural gas will remain in the inner sealing layer 3 after use, in this embodiment, the space inside the inner sealing layer 3 is heated to convert the liquid natural gas into a gaseous state for easy discharge from the transport section. Both the inner sealing layer 3 and the protective layer 2 are snap-fitted onto the outer circumferential surface of the connecting flange 1. An annular snap-fit ​​groove is provided on the outer circumferential surface of the connecting flange 1 for engaging with the protective layer 2, effectively preventing detachment during use. Alternatively, in other embodiments, a groove can be provided on the end face of the connecting flange 1, and the inner sealing layer 3 can be snap-fitted into the groove.

[0030] Specifically, this embodiment employs a heating strip. A heating strip, made of ferromagnetic metal material, is installed on the inner wall of the inner sealing layer 3; in this embodiment, it is a steel wire. The heating strip requires power to function. In this embodiment, a wire is installed between the inner sealing layer 3 and the protective layer 2. The wire carries alternating current, generating a magnetic field around it. Due to the alternating current, this magnetic field is constantly changing, facilitating the heating of the steel wire. The use of a ferromagnetic metal material for the heating strip also facilitates heating by the magnetic field. By placing the wire and heating strip in different layers, the heating strip can directly contact the liquefied natural gas. Since the wire inevitably needs to be connected to a power source, it needs to be externally connected. Placing the wire between the inner sealing layer 3 and the protective layer 2 effectively prevents the wire from puncturing the inner sealing layer 3, thus preventing liquefied natural gas leakage. Furthermore, placing the steel protective layer 2 outside the wire does not affect the heating of the heating strip by the wire.

[0031] To improve heating efficiency and power, the steel wire is an inner spiral steel wire 5 spirally arranged on the inner wall of the inner sealing layer 3. The inner spiral steel wire 5 heats the liquefied natural gas while also providing some support to the inner sealing layer 3. The conductor is an outer wound cable 6 wound around the inner sealing layer 3. The outer wound cable 6 includes an insulation layer and a conductor disposed inside the insulation layer, thus heating the inner spiral steel wire 5 without leakage. It is worth noting that the heating power is related to the current in the outer wound cable 6, the number of turns, and the pitch. In practical use, these parameters can be adjusted to easily regulate the heating power.

[0032] The number of winding turns and the pitch are determined when the pipeline is manufactured, and the size of the current can be controlled later. In order to facilitate the control of the size of the current, the two ends of the outer winding cable 6 are provided with connection ends for connecting the power supply, and the controller 4 is directly connected to the connection ends. The controller 4 is used to receive and control the current, and the connection ends are indirectly connected to the power supply. Since the power supply must be connected externally during connection, a perforation through which the outer winding cable 6 passes is provided on the protective layer 2, which facilitates the arrangement of the external infection cable.

[0033] During heating, it is necessary to know the heating temperature, so a temperature sensor 7 is also arranged in the pipeline. In order to protect the inner sealing layer 3 and prevent liquid leakage, a sensor mounting hole for accommodating the temperature sensor 7 is provided on the connection flange 1. The temperature sensor 7 is arranged in the sensor mounting hole, and a first data line for transmitting the detected temperature signal to the outside of the pipeline is also provided on the temperature sensor 7. In the embodiment, the temperature sensor 7 is located at the place covered by the protective layer 2. Since the thickness is relatively large during sealing, better sealing can be achieved. In addition, the first data line is also connected to the controller 4, which facilitates signal transmission.

[0034] The separate arrangement of the heating strip and the wire can achieve high efficiency and fast heating speed. The thermal efficiency of electromagnetic heating can reach more than 90%, which directly acts on the space that needs to be heated, and the energy loss is low. After the conventional resistance wire generates heat, it is conducted to the inside of the pipeline through the insulation layer, and there is heat loss, and the efficiency is only 50-70%. Electromagnetic heating produces eddy current heating instantaneously, and the temperature rising speed meets the needs of quickly removing residual low-temperature LNG when the low-temperature hose is removed. Since the heating power can be controlled by the current, combined with the feedback of the temperature sensor 7, the electromagnetic heating can be precisely controlled by the controller 4, and the temperature control accuracy can reach + / -1℃ level. In addition, electromagnetic heating does not require direct contact, which reduces the risk of electric shock and ensures uniform heating to avoid local high temperature. Maintenance is convenient, the service life is long, and the economy is good.

[0035] Since the use scene of the pipeline is to transfer liquid between ships or connect the ship with the filling station, the ship may move due to the influence of wind and water flow in the water, thereby pulling the pipeline. Therefore, a stress sensor 8 for detecting the stress of the pipeline is also arranged in the pipeline. The stress sensor 8 is arranged on the side of the heating strip, and a second data line for transmitting the stress signal to the outside is arranged on the stress sensor 8. The signal is transmitted to the controller 4 through the second data line.

[0036] It should be noted that the described embodiments are merely some of the embodiments of the present application, but not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the protection scope of the present application.

Claims

1. A heatable cryogenic pipe comprising a transport section, the inner wall of the transport section being intended for direct contact with liquid natural gas, characterized in that: The heating strip is made of ferromagnetic metal and is fixedly arranged in the transportation section for contacting with the liquid natural gas, the heating strip is spirally arranged on the inner wall of the transportation section, a wire is arranged on the transportation section and outside the heating strip, the wire is spirally arranged, the wire and the heating strip are coaxially arranged, and a connecting end for connecting to an alternating current is further arranged on the wire, so that the heating strip can be electromagnetically heated when the wire is connected to the alternating current.

2. The heatable cryogenic piping of claim 1, wherein: The transportation section is arranged in layers, and the transportation section comprises an inner sealing layer for contacting with the liquid natural gas and a protective layer outside the inner sealing layer, and the wire is arranged between the inner sealing layer and the protective layer.

3. The heatable cryogenic piping of claim 2, wherein: The wire comprises an insulating layer and a conductor in the insulating layer.

4. A heatable cryogenic pipe according to claim 2 or 3, characterized in that: A layer of fiber material is arranged on the inner surface and / or the outer surface of the inner sealing layer.

5. The heatable cryogenic piping of any of claims 1-3, wherein: Both ends of the heatable low-temperature pipeline are provided with a connecting flange fixedly connected with the transportation section.

6. The heatable cryogenic piping of claim 5, wherein: A sensor mounting hole for accommodating a temperature sensor is arranged on the connecting flange, the temperature sensor is arranged in the sensor mounting hole, and a first data line for transmitting a signal to the outside of the heatable low-temperature pipeline is arranged on the temperature sensor.

7. A heatable cryogenic pipe according to claim 2 or 3, characterized in that: Both ends of the heatable low-temperature pipeline are provided with a connecting flange fixedly connected with the transportation section, and an annular clamping groove for clamping cooperation with the protective layer is arranged on the outer peripheral surface of the connecting flange.

8. The heatable cryogenic piping of any of claims 1-3, wherein: A stress sensor for detecting the stress borne by the heating strip is arranged on the side surface of the heating strip, and a second data line for transmitting a signal to the outside of the heatable low-temperature pipeline is arranged on the stress sensor.

9. The heatable cryogenic piping of any of claims 1-4, wherein: The heatable low-temperature pipeline further comprises a controller connected to the connecting end of the wire, and the controller is used for controlling the current on the wire.

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