A gas dome special for a thin film type LNG carrier and an LNG carrier

Abstract

This invention relates to a membrane-type gas dome for LNG carriers and the LNG carrier itself. The gas dome is arranged above a dome deck, with an inner deck below it, forming an isolated compartment between the dome deck and the inner deck. A cargo tank is located below the inner deck, and a containment system is installed outside the cargo tank below the inner deck. A cryogenic expansion pipe connects the gas dome and the cargo tank, passing through the dome deck, the inner deck, and the containment system. A connecting pipe connects the space between the cargo tank and the containment system to the gas dome. In the event of a cargo tank leak, the space between the cargo tank and the containment system and the gas dome are connected via the connecting pipe. When the cargo tank is not leaking, the connecting pipe is disconnected. The gas dome of this invention recovers gases volatilized from the cargo tank. In the event of a cargo tank leak, the connecting pipe balances the air pressure in the space between the containment system and the cargo tank, preventing damage to the hull.

Description

Technical Field

[0001] This invention relates to the field of LNG carriers, specifically to a membrane-type gas dome for LNG carriers and an LNG carrier. Background Technology

[0002] The gas dome is a key piece of equipment in membrane-type LNG carriers, used for the recovery and reuse of volatile gases from the cargo tanks. According to the IGC Code (International Code for the Construction and Equipment of Ships Carrying Liquefied Gases in Bulk), the gas dome, as a closed structure, needs to contain gaseous LNG and has high pressure resistance and thermal insulation performance. It ensures that the volatile gases generated during LNG transportation can be transported and circulated through the cargo system pipelines, reducing LNG evaporation and leakage. At the same time, it needs to withstand the pressure and vibration under marine conditions and resist harsh weather and marine environments. Therefore, the arrangement of the gas dome is a very important part of the design process of membrane-type LNG carriers.

[0003] Because the space between the cargo tank and the external containment system needs to be evacuated and filled with nitrogen, the air pressure in the space between the cargo tank and the containment system is lower than the air pressure inside the cargo tank. Once the cargo tank leaks, the high pressure inside the cargo tank enters the low pressure space between the cargo tank and the containment system, which can easily cause the air pressure inside the containment system to rise, leading to the rupture of the containment system. Once the containment system ruptures, the low temperature leakage can cause the ship's structure to become brittle. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention provides a membrane-type gas dome for LNG carriers and an LNG carrier in the event of a cargo tank leak. This dome can balance the gas pressure between the cargo tank and the containment system with the gas pressure inside the dome, thus preventing damage to the maintenance system.

[0005] The technical objective of this invention is achieved through the following technical solution:

[0006] A membrane-type gas dome for LNG carriers is provided, which is arranged above a dome deck. An inner deck is located below the dome deck, forming an isolated compartment between the dome deck and the inner deck. A cargo tank is located below the inner deck, and a containment system is installed outside the cargo tank below the inner deck. A cryogenic expansion pipe connects the gas dome and the cargo tank, passing through the dome deck, the inner deck, and the containment system. A connecting pipe connects the space between the cargo tank and the containment system and the gas dome. When the cargo tank leaks, the space between the cargo tank and the containment system and the gas dome are connected through the connecting pipe. When the cargo tank does not leak, the connecting pipe between the space between the cargo tank and the containment system and the gas dome is disconnected.

[0007] Furthermore, the connecting pipe includes a first connecting pipe, a second connecting pipe, and a third connecting pipe. One end of the first connecting pipe connects the liquid cargo tank and the containment system, and the other end of the first connecting pipe extends along the interior of the cryogenic expansion pipe to the gas dome and exits from the gas dome. A first flange joint is provided at the end of the first connecting pipe that exits from the gas dome. The second connecting pipe connects the inside and outside of the gas dome, and a second flange joint is provided at the end of the second connecting pipe that connects to the outside of the gas dome. The two ends of the third connecting pipe are respectively provided with third flange joints that mate with the first flange joint and the second flange joint.

[0008] Furthermore, when the liquid cargo tank leaks, the third connecting pipe is connected between the first and second connecting pipes via the third flange joint; when the liquid cargo tank does not leak, the third connecting pipe is not installed, and the first and second flange joints are respectively sealed with baffles.

[0009] Furthermore, the dome deck is also equipped with volatile gas pipelines for the liquid cargo system that are connected to the gas dome.

[0010] Furthermore, the gas dome and liquid cargo system evaporation pipelines are located on the midship side of the dome deck.

[0011] Furthermore, the distance between the gas dome and the midships is 1-1.5m.

[0012] Furthermore, the distance between the gas dome and the midships is 1.25m.

[0013] Furthermore, the gas dome and the dome deck are connected by fillet welds, which ensures that the weld strength between the gas dome and the dome deck meets the design requirements.

[0014] Furthermore, several gas domes are installed on the dome deck near the port side.

[0015] The present invention also provides a membrane-type LNG carrier, wherein the LNG carrier is provided with the above-mentioned gas dome.

[0016] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0017] 1. This invention provides a membrane-type gas dome for LNG carriers. On the one hand, the gas dome can recover and reuse the gas volatilized from the cargo tank; on the other hand, when the cargo tank leaks, it can balance the air pressure in the space between the containment system and the cargo tank through the connecting pipe, so as to avoid damage to the containment system and ensure that the hull structure is not affected by low temperature.

[0018] 2. By setting the gas dome on the dome deck on one side of the ship, the present invention facilitates connection with the liquid cargo system's volatile gas pipelines, thereby optimizing the pipeline layout on the dome deck. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the state of the membrane-type LNG carrier's special gas dome when the liquid cargo tank is not leaking, as described in this invention.

[0020] Figure 2 This is a schematic diagram of the state of the membrane-type LNG carrier's special gas dome when the liquid cargo tank leaks, as described in this invention.

[0021] Figure 3 This is a schematic diagram of the gas dome of the present invention installed on the hull.

[0022] In the diagram, 1. Gas dome; 2. Dome deck; 3. Inner deck; 4. Cargo tank; 5. Containment system; 6. Cryogenic expansion pipe; 7. First connecting pipe; 8. Second connecting pipe; 9. Third connecting pipe; 10. Midships. Detailed Implementation

[0023] The technical solution of the present invention will be further described below with reference to specific embodiments:

[0024] This embodiment provides an LNG carrier, such as Figure 1 As shown, a membrane-type gas dome specifically designed for LNG carriers is installed on this LNG carrier, such as... Figure 1 As shown, the gas dome 1 is arranged above the dome deck 2, and the gas dome 1 and the dome deck 2 are connected by fillet welds. An inner deck 3 is set below the dome deck 2, forming an isolated compartment between the dome deck 2 and the inner deck 3. A liquid cargo tank 4 is set below the inner deck 3, and a containment system 5 is set outside the liquid cargo tank 4 below the inner deck 3. A cryogenic expansion pipe 6 is connected between the gas dome 1 and the liquid cargo tank 4, and the cryogenic expansion pipe 6 passes through the dome deck 2, the inner deck 3, and the containment system 5. A connecting pipe is connected between the space between the liquid cargo tank 4 and the containment system and the gas dome 1. When the liquid cargo tank 4 leaks, the space between the liquid cargo tank 4 and the containment system 5 is connected to the gas dome 1 through the connecting pipe. When the liquid cargo tank 4 does not leak, the connecting pipe between the space between the liquid cargo tank 4 and the containment system 5 and the gas dome 1 is disconnected.

[0025] Specifically, the connecting pipe includes a first connecting pipe 7, a second connecting pipe 8, and a third connecting pipe 9. One end of the first connecting pipe 7 connects between the liquid cargo tank 4 and the containment system 5. The first connecting pipe 7 extends along the interior of the cryogenic expansion pipe 6 to the gas dome 1 and exits from the gas dome 1. A first flange joint is provided at the end of the first connecting pipe 7 that exits from the gas dome 1. The second connecting pipe 8 connects the inside and outside of the gas dome 1. A second flange joint is provided at the end of the second connecting pipe 8 that connects to the outside of the gas dome 1. The two ends of the third connecting pipe 9 are respectively provided with third flange joints that mate with the first flange joint and the second flange joint.

[0026] When there is no leakage in cargo tank 4, the third connecting pipe 9 is not installed, such as... Figure 1 As shown, obstruction plates are installed at the first flange joint and the second flange joint respectively.

[0027] When the liquid cargo tank 4 leaks, the third connecting pipe 9 is connected between the first connecting pipe 7 and the second connecting pipe 8 via the third flange joint, such as... Figure 2 As shown;

[0028] The dome deck 2 is also equipped with a liquid cargo system evaporation gas pipeline connected to the gas dome 1. The gas inside the gas dome is delivered to other systems on the ship via this pipeline. The gas dome 1 and the liquid cargo system evaporation gas pipeline are located on one side of the dome deck 2, amidships 10. In this embodiment, several gas domes are located on the port side of the dome deck, such as... Figure 3 As shown, the distance between the gas dome 1 and the midships is 1-1.5m. Specifically, the distance between the center of the gas dome and the midships 10 is 1-1.5m. In this embodiment, the distance between the center of the gas dome and the midships 10 is 1.25m.

[0029] This embodiment is merely a further explanation of the present invention and is not intended to limit the present invention. Those skilled in the art can make non-inventive modifications to this embodiment as needed after reading this specification, but such modifications are protected by patent law as long as they are within the scope of the claims of the present invention.

Claims

1. A membrane-type gas dome for LNG carriers, characterized in that, The gas dome is positioned above the dome deck, below which is an inner deck, forming an isolated compartment. Below the inner deck is a cargo tank, and below that, an enclosure system is installed outside the cargo tank. A cryogenic expansion pipe connects the gas dome and the cargo tank, passing through the dome deck, inner deck, and enclosure system. A connecting pipe connects the space between the cargo tank and the enclosure system to the gas dome. In the event of a leak in the cargo tank, the space between the cargo tank and the enclosure system and the gas dome are connected via the connecting pipe; when the cargo tank is not leaking, the connecting pipe is disconnected. The connecting pipe includes a first connecting pipe, a second connecting pipe, and a third connecting pipe. One end of the first connecting pipe connects the liquid cargo tank and the containment system, and the other end of the first connecting pipe extends along the interior of the cryogenic expansion pipe to the gas dome and exits from the gas dome. A first flange joint is provided at the end of the first connecting pipe that exits from the gas dome. The second connecting pipe connects the inside and outside of the gas dome, and a second flange joint is provided at the end of the second connecting pipe that connects to the outside of the gas dome. The two ends of the third connecting pipe are respectively provided with third flange joints that mate with the first flange joint and the second flange joint.

2. The membrane-type gas dome for LNG carriers according to claim 1, characterized in that, When the liquid cargo tank leaks, the third connecting pipe is connected between the first connecting pipe and the second connecting pipe through the third flange joint; when the liquid cargo tank does not leak, the third connecting pipe is not installed, and the first flange joint and the second flange joint are respectively sealed with baffles.

3. The membrane-type gas dome for LNG carriers according to claim 1, characterized in that, The dome deck is also equipped with volatile gas pipelines for the liquid cargo system that are connected to the gas dome.

4. A membrane-type gas dome for LNG carriers according to claim 3, characterized in that, The gas dome and liquid cargo system volatile gas pipelines are located on the midship side of the dome deck.

5. A membrane-type gas dome for LNG carriers according to claim 4, characterized in that, The distance between the gas dome and the midships is 1-1.5m.

6. A membrane-type gas dome for LNG carriers according to claim 5, characterized in that, The gas dome is 1.25m away from the midships.

7. A membrane-type gas dome for LNG carriers according to claim 1, characterized in that, The gas dome and the dome deck are connected by fillet welds.

8. A membrane-type gas dome for LNG carriers according to claim 4, characterized in that, Several of the aforementioned gas domes are located on the port side of the dome deck.

9. A membrane-type LNG carrier, characterized in that, The LNG carrier is equipped with a gas dome, which is the gas dome as described in any one of claims 1-8.

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