Sewage discharge pipeline for secondary insulating layer of LNG (Liquefied Natural Gas) ship

Abstract

An LNG (liquefied natural gas) ship secondary insulating layer sewage discharge pipeline is characterized in that an embedded butt welding mode of an ultralow-temperature discharge pipeline is adopted at a cabin penetration part, single-side welding operation is only carried out outside a sewage well, full penetration welding and double-side forming are carried out, and a worker does not need to enter the sewage well to carry out welding operation. And in addition, the butt welding compound plate and the protection pipe are subjected to nail welding in the pipe prefabricating stage, adjustment of accumulated errors caused by manufacturing, construction and the like in the later period is facilitated, and the problem that the installation precision is not high is solved. The ultralow-temperature discharge pipeline is connected with the cabin penetration compound plate and the butt welding elbows in a welded mode, leakage of liquid or boil-off gas of the liquid cargo tank is effectively avoided, danger is avoided, the 1.5-time-length butt welding elbows are more beneficial to smooth discharge of ultralow-temperature discharge objects, the problem that maintenance is inconvenient is effectively solved, and the service life of the ultralow-temperature discharge pipeline is prolonged. Meanwhile, the installation of the tightness test device at the end part is more convenient. And the problem of liquid accumulation in the pipeline is solved, later maintenance is facilitated, and the design quality is improved.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of offshore ship design and construction, and particularly relates to a secondary insulation layer sewage discharge pipeline of an LNG ship. BACKGROUND

[0002] An LNG transport ship is a ship specially used for transporting liquefied natural gas, is a "super refrigeration vehicle on sea" carrying LNG at minus 163 degrees Celsius, and is known as the "crown jewel" of the shipbuilding industry. Due to the particularity of the LNG transport ship, the safety and sealing requirements are extremely high, and therefore, the design and construction of the pipeline system and equipment have higher requirements. The isolation air chamber is a partition chamber between the front and rear liquid tanks of the LNG ship, and the main function thereof is to prevent fire, explosion and leakage. The secondary insulation layer sewage well of the secondary insulation layer of the LNG ship is arranged in the isolation air chamber, and a discharge pipeline needs to be arranged to realize the communication between the secondary insulation layer and the secondary insulation layer.

[0003] In order to effectively solve the problems of the narrow space of the sewage well, the inability to realize double-sided welding of the access piece, the easy corrosion of the pipeline after a long time, and the like, and to improve the welding quality, improve the installation precision of the low-temperature pipeline, reduce corrosion and avoid leakage, multiple schemes and multiple angles are used to improve the safety and effectiveness of the discharge of the secondary insulation layer sewage well and the isolation air chamber sewage well. SUMMARY

[0004] To solve the above problems, the present application provides a secondary insulation layer sewage discharge pipeline of an LNG ship, and the technical scheme adopted is as follows:

[0005] A secondary insulation layer sewage discharge pipeline of an LNG ship, wherein a secondary insulation layer sewage well is arranged below an isolation air chamber, a secondary insulation layer discharge pipe is connected to the secondary insulation layer at one end and penetrates a side wall of the secondary insulation layer sewage well into the secondary insulation layer sewage well at the other end.

[0006] An opening with a diameter of 820mm is opened on the side wall of the secondary insulation layer sewage well. The opening has a 35° bevel with the bevel angle facing outward. The passage sleeve is welded to the bevel. The passage sleeve consists of a protective pipe located in the center and a cover plate outside the protective pipe. The connection between the cover plate and the protective pipe has a 35° bevel with the bevel angle facing outward.

[0007] During installation, the protective tube and the cryogenic tube are welded together in the prefabrication stage, and the cladding plate and the protective tube are nailed together in the prefabrication stage. First, the cladding plate and the secondary insulation layer of the sewage well sidewall are aligned accurately. After positioning, the cladding plate and the secondary insulation layer of the sewage well sidewall are welded first, and then the cladding plate and the protective tube are welded. Both of these welds are welded using the single-sided welding and double-sided forming method.

[0008] The discharge pipe adopts an upward suction type. The end of the discharge pipe penetrates the top plate of the secondary insulation layer sewage well and extends downward into the secondary insulation layer sewage well. A right-angle check valve is installed at the corner of the discharge pipe. The check valve is connected to the pneumatic diaphragm pump unit through a straight-through shut-off valve.

[0009] Furthermore, in the aforementioned LNG ship insulated wastewater discharge pipeline, a current of 120A is used for welding when the protective pipe is welded to the cladding plate and when the web plate is welded to the side wall of the wastewater well.

[0010] Furthermore, in the aforementioned LNG ship insulation layer sewage discharge pipeline, the diameter of the cladding opening is 3mm larger than the diameter of the protective pipe.

[0011] Furthermore, in the aforementioned LNG ship secondary insulation layer sewage discharge pipe, a filter screen is installed at the end of the secondary insulation layer discharge pipe located inside the sewage well, and the end is 400mm away from the side wall of the sewage well.

[0012] Furthermore, in the aforementioned LNG ship insulation layer sewage discharge pipeline, the filter screen is fixed by a flange clamp.

[0013] Furthermore, in the aforementioned LNG ship secondary insulation layer sewage discharge pipeline, the end of the discharge pipe is 30±5mm from the bottom of the secondary insulation layer sewage well.

[0014] Furthermore, in the aforementioned LNG ship secondary insulation layer sewage discharge pipeline, a hatch cover is provided at the connection between the secondary insulation layer discharge pipe and the secondary insulation layer.

[0015] Furthermore, in the aforementioned LNG ship insulation layer sewage discharge pipeline, the other end of the pneumatic diaphragm pump unit is connected to a hose via a pipeline, hose connector valve, and hose.

[0016] This invention employs an embedded butt-welded type of cryogenic venting pipe at the through-hole component, allowing for single-sided welding only on the outside of the sludge well, achieving full penetration and double-sided forming, eliminating the need for personnel to enter the sludge well for welding. Furthermore, the butt-welded cladding plate is studded to the protective pipe during the prefabrication stage, facilitating adjustments for accumulated errors from manufacturing and construction, and resolving issues of low installation precision. The cryogenic venting pipe, connected to the through-hole cladding plate and with butt-welded elbows, effectively prevents leakage of liquid or evaporated gas from the cargo tank, avoiding potential hazards. The 1.5 times longer butt-welded elbows further ensure smooth discharge of cryogenically released substances. The 400mm distance between the end of the cryogenic venting pipe and the sludge well wall effectively solves the problem of inconvenient maintenance and servicing, while also facilitating the installation of a leak test device at the end. This invention also solves the problem of liquid accumulation inside the pipe, further facilitating later maintenance and servicing, improving design quality, ensuring the pipeline system can be maintained without hot work throughout its entire lifecycle, enhancing safety, and increasing the operational value of the ship. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the secondary insulation layer, the isolation chamber, and the secondary insulation layer sewage well structure;

[0018] Figure 2 This is a schematic diagram of the structure of the present invention;

[0019] Figure 3 yes Figure 2 A magnified structural diagram of circle I in the middle;

[0020] Figure 4 This is a schematic diagram of the through-hole casing structure;

[0021] Among them, 1-secondary insulation layer discharge pipe, 1.1-through chamber cover plate, 1.4-cover plate, 1.5-sewage well sidewall, 1.6-protective pipe, 1.8-flange, 2.1-discharge pipe, 2.2-right angle check valve, 2.3-straight-through shut-off valve, 2.4-pneumatic diaphragm pump unit, 2.5-hose connector valve, 2.6-hose, F-isolation chamber, G-cryogenic liquid tank, H-secondary insulation layer sewage well. Detailed Implementation

[0022] The invention will be further described with reference to the accompanying drawings.

[0023] A wastewater discharge pipeline for LNG ship insulation, such as Figure 1 As shown, the secondary insulation layer sewage well is located below the isolation chamber. One end of the secondary insulation layer discharge pipe is connected to the secondary insulation layer. A chamber access plate is provided at the connection between the secondary insulation layer discharge pipe and the secondary insulation layer. The other end passes through the side wall of the secondary insulation layer sewage well and enters the secondary insulation layer sewage well.

[0024] like Figure 2 ,3 As shown in Fig. 4, an opening with a diameter of 820 mm is formed on the side wall of the secondary insulation layer sewage well, a 35° bevel is arranged at the opening, the bevel angle is outward, a through-cabin sleeve is welded at the bevel, the through-cabin sleeve is composed of a protection pipe in the center and a double plate outside the protection pipe, a 35° bevel is arranged at the connection between the double plate and the protection pipe, the bevel angle is outward. The opening diameter of the double plate is 3 mm larger than the outer diameter of the protection pipe, and the opening of the secondary insulation layer sewage well side wall is 2 mm larger than the outer diameter of the double plate.

[0025] During installation, the protection pipe and the ultra-low temperature pipe are welded as a whole in the prefabrication stage, the double plate and the protection pipe are riveted in the prefabrication stage, the double plate is first adjusted to be accurately aligned with the secondary insulation layer sewage well side wall, after the position is fixed, the double plate is first welded with the secondary insulation layer sewage well side wall, and then the double plate is welded with the protection pipe. Both the two welding openings are welded by using the method of single-sided welding and double-sided forming.

[0026] An upward suction type discharge pipe is used, the end of the discharge pipe penetrates the top plate of the secondary insulation layer sewage well downward and extends into the secondary insulation layer sewage well, a right-angle check valve is arranged at the corner of the discharge pipe, and the check valve is connected with a pneumatic diaphragm pump unit.

[0027] The end of the secondary insulation layer discharge pipe located in the sewage well is provided with a filter screen, and the end is 400 mm away from the side wall of the sewage well.

[0028] Due to the narrow space of the sewage well, the welding conditions and requirements cannot be met, and the present application solves this problem.

[0029] In the present application, the secondary insulation layer discharge pipe is discharged to the secondary insulation layer sewage well, a right-angle check valve and a straight-through valve are arranged on the discharge pipe to form a double-valve isolation, the double valve is opened to suck the medium into the pipeline by the action of the pneumatic diaphragm pump unit and discharge it to the collection device. After the medium in the secondary insulation layer sewage well is discharged, the blow-off valve arranged in front of the diaphragm pump discharge port is connected with compressed air for purging to remove the liquid accumulated in the pipeline. When the present application is used, no medium is stored in the secondary insulation layer sewage well discharge pipeline of the entire isolated empty cabin.

Claims

1. An LNG carrier secondary insulation layer bilge line characterized by, The secondary insulation layer sewage well is arranged below the isolation air chamber, and the secondary insulation layer discharge pipe is connected with the secondary insulation layer at one end and penetrates the side wall of the secondary insulation layer sewage well into the secondary insulation layer sewage well at the other end; An opening with a diameter of 820 mm is formed in the side wall of the secondary insulation layer sewage well, and a 35° bevel is arranged at the opening, the bevel angle is outward, a through-chamber sleeve is welded at the bevel, the through-chamber sleeve comprises a protection pipe located at the center and a double plate outside the protection pipe, a 35° bevel is arranged at the connection between the double plate and the protection pipe, and the bevel angle is outward; An upward suction type discharge pipe is adopted, the end of the discharge pipe penetrates the top plate of the secondary insulation layer sewage well downward and extends into the secondary insulation layer sewage well, a right-angle check valve is arranged at the corner of the discharge pipe, the check valve is connected with a pneumatic diaphragm pump unit, and the other end of the pneumatic diaphragm pump unit is connected with a hose through a pipeline and a hose joint valve.

2. A secondary insulation layer contaminated water discharge pipe for an LNG carrier according to claim 1, characterized by When the protection pipe and the double plate are welded and the web plate and the side wall of the sewage well are welded, a current of 120 A is adopted for welding.

3. A secondary insulation layer contaminated water drain pipe for an LNG carrier according to claim 1, wherein The diameter of the opening of the double plate is 3 mm larger than the diameter of the protection pipe.

4. The LNG carrier secondary insulation layer effluent pipe according to claim 1, wherein The end of the secondary insulation layer discharge pipe arranged inside the sewage well is provided with a filter screen, and the end is 400 mm away from the side wall of the sewage well.

5. A secondary insulation layer contaminated water discharge pipe for an LNG carrier according to claim 4, characterized by The filter screen is fixed in a flange pair clamping mode.

6. The LNG carrier secondary insulation layer effluent pipe according to claim 1, wherein The end of the discharge pipe is 30±5 mm away from the bottom of the secondary insulation layer sewage well.

7. The LNG carrier secondary insulation layer effluent pipe according to claim 1, wherein A through-chamber double plate is arranged at the connection between the secondary insulation layer discharge pipe and the secondary insulation layer.

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