LNG long-distance transportation system based on composite insulation and dynamic cold preservation

Abstract

The utility model relates to liquefied natural gas (LNG) long distance transportation and cold energy utilization technical field, concretely is a kind of LNG long distance transportation system based on composite heat insulation and dynamic cold preservation, LNG long distance transportation system equipment include: upstream LNG receiving station storage tank, LNG long distance transportation pipeline, downstream LNG receiving station storage tank, propane-liquid nitrogen exchanger, open rack type gasifier, LNG comes out from upstream receiving station storage tank, enters downstream receiving storage tank by long distance transportation pipeline, after propane-liquid nitrogen exchanger and open rack type gasifier temperature rising gasification again, enter natural gas pipe network, for downstream user use, the utility model utilizes propane-liquid nitrogen cold screen to carry out active intervention type heat preservation, block most of the heat entering inner tube, to reduce the gasification of LNG in inner tube, improve economic benefit.

Description

Technical Field

[0001] This utility model relates to the field of long-distance transportation and cold energy utilization of liquefied natural gas (LNG), and in particular to a long-distance LNG transportation system based on composite insulation and dynamic cold preservation. Background Technology

[0002] Liquefied natural gas (LNG) is a high-calorific-value, clean, and efficient energy source, and its long-distance transportation technology has always been a focus of industry attention. Long-distance transportation between LNG ships and receiving terminal storage tanks, as well as between receiving terminal storage tanks and external satellite stations, both face transportation difficulties and BOG (Boiled Air Gaseous) emissions issues. Traditional LNG transportation systems mainly use vacuum insulation or foam insulation, which have limited insulation performance and significant cold loss, making them unsuitable for long-distance transportation. Furthermore, existing LNG transportation systems lack effective dynamic cooling measures, causing the LNG temperature to rise during transportation, affecting transportation efficiency and safety.

[0003] When using liquefied natural gas (LNG) pipelines, the temperature of the LNG flowing in the inner pipe is below -162℃, while the outside of the outer jacket is at ambient temperature. This creates a temperature difference of approximately 182℃ between the inner and outer jackets, inevitably leading to heat transfer. When external heat is transferred from the outer jacket to the inner pipe, the LNG inside will partially vaporize. This vaporized LNG, due to overpressure or failure to meet LNG usage requirements, must be released. Traditional LNG pipelines suffer from significant heat leakage due to small vacuum jackets and limited insulation efficiency of composite insulation layers. This results in a large amount of LNG evaporating into bound gas (BOG) and being released during transport, causing substantial waste and hindering long-distance transport.

[0004] To address the above problems, this utility model provides the following solutions. Utility Model Content

[0005] The purpose of this invention is to address the shortcomings of existing technologies by proposing a long-distance LNG transportation system based on composite insulation and dynamic cold preservation.

[0006] To achieve the above objectives, this utility model adopts the following technical solution: a long-distance LNG transportation system based on composite insulation and dynamic cold preservation. The LNG long-distance transportation system equipment includes: an upstream LNG receiving terminal storage tank, an LNG long-distance pipeline, a downstream LNG receiving terminal storage tank, a propane-liquid nitrogen cooler, and an open-frame vaporizer. After LNG comes out of the upstream receiving terminal storage tank, it enters the downstream receiving storage tank through the long-distance pipeline. After being heated and vaporized by the propane-liquid nitrogen cooler and the open-frame vaporizer, it enters the natural gas pipeline network for downstream users.

[0007] The long-distance pipeline includes an inner pipe, a vacuum insulation panel, an outer jacket pipe, a nano-aerogel composite insulation layer, a polyurethane foam filling layer, and an outer pipeline protection layer. A vacuum insulation panel is installed between the inner pipe and the outer jacket pipe to reduce the exchange of cold energy between LNG and the outside environment. A propane-liquid nitrogen cold shield pipe is arranged between the outer jacket pipe and the nano-aerogel composite insulation layer. The propane-liquid nitrogen cold shield pipe isolates external heat from entering the LNG pipeline. The nano-aerogel composite insulation layer is wrapped with a polyurethane foam filling layer to further prevent the loss of cold energy in the pipeline. The outer pipeline protection layer is used to protect the internal structure and prevent the cold insulation structure from being damaged by external forces. During the LNG vaporization process, LNG enters the propane-liquid nitrogen cooler and exchanges cold energy with the propane-liquid nitrogen mixed refrigerant. After the propane-liquid nitrogen mixed refrigerant is cooled, it flows back from the cooler outlet to the top of the LNG long-distance pipeline to keep the LNG long-distance pipeline cold. Then it returns to the inlet of the propane-liquid nitrogen cooler for another cold exchange, forming a closed loop.

[0008] A fiber optic temperature sensor is installed on the outer wall of the inner pipe. A split pressure regulating valve group is set every 500 meters in the propane-liquid nitrogen cold shield pipeline. The fiber optic temperature sensor controls the split pressure regulating valve group of the propane-liquid nitrogen cold shield pipeline in conjunction with the inner pipe temperature data. The pressure of the propane-liquid nitrogen cold shield pipeline is controlled in segments according to the inner pipe temperature data, and the refrigerant flow is adjusted in real time to maintain the stable low temperature transportation of LNG in the inner pipe. The propane-liquid nitrogen cold shield pipeline arranged between the outer jacket and the nano-aerogel composite insulation layer adopts a pipe-type pipe screen structure. The pressure regulating device matched with the inner pipe and the propane-liquid nitrogen cold shield pipeline together form a dynamic cold insulation circulation system for the long-distance LNG pipeline.

[0009] The vacuum insulation panel between the inner tube and the outer jacket, the nano-aerogel composite insulation layer, and the polyurethane foam filling layer together constitute the composite insulation layer of the LNG long-distance pipeline.

[0010] Compared with the prior art, the advantages and positive effects of this utility model are as follows:

[0011] In this invention, (1) the propane-liquid nitrogen cold shield is used for active intervention insulation, which blocks most of the heat entering the inner pipe, thereby reducing the vaporization of LNG in the inner pipe and improving economic efficiency; (2) the setting of the propane-liquid nitrogen cold shield reduces the temperature gradient in the vacuum zone between the inner pipe and the outer jacket pipe, improves the insulation performance, further reduces the vaporization of LNG in the inner pipe, and improves economic efficiency; (3) the cold source of the propane-liquid nitrogen cold shield comes from the vaporization process of downstream LNG. The propane-liquid nitrogen cooler is used to recover and extract the deep cold of LNG vaporization, and the cold energy is used for LNG long-distance transmission insulation, which reduces the vaporization of LNG in the inner pipe, which is conducive to saving energy and improving the comprehensive energy utilization rate; (4) the linkage control of the split pressure regulating valve group and temperature sensor of the LNG long-distance pipeline can adjust the pressure and flow of LNG in the inner pipe in real time, which is conducive to improving the stability of the LNG long-distance pipeline. Attached Figure Description

[0012] Figure 1 This is a schematic cross-sectional view of the high-vacuum insulated LNG long-distance pipeline described in the background section.

[0013] Figure 2 This is a schematic diagram of a pipe-type screen structure.

[0014] Figure 3 This is a diagram of a long-distance LNG transportation system that combines composite thermal insulation and dynamic cold preservation.

[0015] Explanation of reference numerals in the attached diagram: 1. Inner pipe; 2. Vacuum insulation panel; 3. Outer jacket pipe; 4. Propane-liquid nitrogen cold shield pipe; 5. Nano-aerogel composite insulation layer; 6. Polyurethane foam filling layer; 7. Outer pipe protective layer; 8. Inlet semi-circular cold pipe; 9. Outlet semi-circular cold pipe; 10. Direct cooling pipe; 11. Circular main pipe; 12. Upstream receiving station storage tank; 13. LNG long-distance pipeline; 14. Downstream receiving storage tank; 15. Propane-liquid nitrogen cooler; 16. Open-frame vaporizer; 17. Split-type pressure regulating valve assembly; 18. Fiber optic temperature sensor. Detailed Implementation

[0016] To make the objectives, technical solutions, and advantages of this utility model clearer, the present utility model will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present utility model and are not intended to limit the present utility model.

[0017] In the description of this utility model, it should be understood that the terms "length," "width," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the accompanying drawings and are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this utility model. Furthermore, in the description of this utility model, "a plurality of" means two or more, unless otherwise explicitly specified.

[0018] Please see Figure 1-3This utility model provides a technical solution: a long-distance LNG transportation system based on composite insulation and dynamic cold preservation, wherein the high-vacuum multi-layer composite insulation LNG long-distance pipeline includes an inner pipe 1, a vacuum insulation board 2, an outer jacket pipe 3, a propane-liquid nitrogen cold shield pipe 4, a nano aerogel composite insulation layer 5, a polyurethane foam filling layer 6, and an outer pipeline protective layer 7. An outer jacketed pipe 3 is fitted around the inner pipe 1. A vacuum insulation plate 2 is installed between the inner pipe 1 and the outer jacketed pipe 3 to form a relatively closed vacuum zone. A propane-liquid nitrogen cold shield pipe 4 surrounds the outer jacketed pipe 3 to form a propane-liquid nitrogen cold shield to block external heat from entering the inner pipe 1. A nano-aerogel composite insulation layer 5 is installed on the outside of the propane-liquid nitrogen cold shield pipe 4 to reduce heat exchange with the outside and prevent the loss of cold energy of the propane-liquid nitrogen mixed refrigerant. A polyurethane foam filling layer 6 is installed on the outside of the nano-aerogel composite insulation layer 5 to further block external heat from entering the inner pipe 1 and the propane-liquid nitrogen cold shield pipe 4, reducing the loss of cold energy of LNG in the inner pipe 1. An outer pipe protection layer 7 is installed on the outside of the polyurethane foam filling layer 6 to strengthen the protection of the internal pipe and insulation layer and avoid damage to the internal structure.

[0019] like Figure 2 As shown, an LNG long-distance transportation system based on composite insulation and dynamic cold preservation is disclosed. The propane-liquid nitrogen cold shield pipeline 4 adopts a pipe-type shield structure. At the end of the long-distance pipeline, there is an inlet semi-circular cold pipe 8 and an outlet semi-circular cold pipe 9, each connected to several straight cold pipes 10. At the initial end of the long-distance pipeline, there is a circular main pipe 11 connecting all the branch pipes. The straight cold pipes are evenly distributed around the circumference of the LNG transportation pipeline outside the outer jacket pipe 3. The pipe ends on the same side of each straight cold pipe 10 are simultaneously connected to the inlet semi-circular cold pipe 8, and the pipe ends on the other side of each straight cold pipe 10 are simultaneously connected to the outlet semi-circular cold pipe 9, forming a pipe-type shield structure.

[0020] like Figure 3 As shown, an LNG long-distance transportation system based on composite insulation and dynamic cold preservation is described. The cold source of the propane-liquid nitrogen cold shield pipeline 4 comes from the vaporization process of LNG. After LNG comes out of the upstream receiving terminal storage tank 12, it enters the downstream receiving storage tank 14 through the LNG long-distance pipeline 13. After being heated and vaporized by the propane-liquid nitrogen exchanger 15 and the open-frame vaporizer 16, it enters the natural gas pipeline network. The propane-liquid nitrogen exchanger 15 recovers and extracts the deep cryogenic fluid from the vaporized LNG, cools the propane-liquid nitrogen mixed refrigerant, and transports the low-temperature propane-liquid nitrogen mixed refrigerant to the LNG outlet of the upstream receiving terminal storage tank 12 through the propane-liquid nitrogen cold shield pipeline 4. Then, together with the LNG long-distance pipeline 13, it connects from the upstream receiving terminal storage tank 12 to the downstream receiving terminal storage tank 14. The propane-liquid nitrogen mixed refrigerant returns to the inlet of the propane-liquid nitrogen exchanger 15 for another cooling, forming a closed loop.

[0021] like Figure 3As shown, an LNG long-distance transportation system based on composite insulation and dynamic cold preservation is described. In this system, an optical fiber temperature sensor 18 is installed on the outer wall of the inner pipe 1 of the LNG long-distance pipeline 13. A split-type pressure regulating valve group 17 is installed every 500m in the propane-liquid nitrogen cold shield pipeline 4. Through the action of the optical fiber temperature sensor 18, the valve opening of the LNG split-type pressure regulating valve group 17 is dynamically adjusted according to the temperature of the inner pipe, thereby controlling the pressure of the mixed refrigerant in segments, regulating the flow rate of the mixed refrigerant, and ensuring stable low-temperature long-distance transportation of LNG.

[0022] The above are merely preferred embodiments of this utility model and are not intended to limit the utility model in any other way. Any person skilled in the art may make changes or modifications to the above-disclosed technical content to create equivalent embodiments for application in other fields. However, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of this utility model without departing from the technical solution of this utility model shall still fall within the protection scope of this utility model.

Claims

1. A LNG long distance transportation system based on composite insulation and dynamic cold preservation, characterized in that, The LNG long-distance transportation system equipment comprises: an upstream LNG receiving station storage tank, a LNG long-distance pipeline, a downstream LNG receiving station storage tank, a propane-liquid nitrogen cold exchanger and an open rack gasifier; The long-distance pipeline comprises an inner pipe, a vacuum heat insulation plate, an outer jacket pipe, a nano aerogel composite heat preservation layer, a polyurethane foam filling layer and an outer pipeline protection layer; An optical fiber temperature sensor is installed on the outer wall of the inner pipe, and a split type pressure regulating valve group is arranged every 500 meters of the propane-liquid nitrogen cold screen pipeline; The vacuum heat insulation plate, the nano aerogel composite heat preservation layer and the polyurethane foam filling layer are arranged between the inner pipe and the outer jacket pipe.

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