CN1910079B - A lng-carrier with spherical tanks and double bottom - Google Patents

Abstract

A transport vessel having at least one cargo tank, preferably spherical or nearly spherical, for transporting liquefied gas, preferably liquefied natural gas (LNG). The transport vessel has an outer bottom (4) and an inner bottom (3) forming a double bottom, with cavities (5) in the inner bottom (3) spaced apart along the axial direction of the transport vessel. Each cavity is designed to accommodate a portion of each cargo tank, and the distance from the inner bottom to the centerline of the transport vessel is approximately 25% (15%-30%) of the distance from the outer bottom to the main deck.

Description

A double-bottom LNG carrier with spherical tanks

technical field

The invention relates to a liquefied natural gas (LNG) carrier according to the preamble of claim 1 . the

Background technique

Hereinafter, a ship that transports liquefied natural gas (LNG) is referred to as a transport ship or an LNG carrier. Those of ordinary skill understand that the expression transport ship should be understood equally as ships, ships, etc. the

Displacement tonnage is often used to describe the size of a vessel, such as an LNG carrier. The tonnage of a ship is calculated based on the total enclosed volume of the hull and most of the effective compartments of the ship. When calculating tolls and tolls in port and across canals, the tonnage of the ship is used. Because of the various rules and conventions of shipping throughout the world, the method of calculating a vessel's tonnage varies from official to official. the

A separate method for calculating the tonnage of ships is extremely important for special ships, for example, when determining fiscal tariffs for ships to pass through canals. This is especially true for ships entering a canal such as the Suez Canal, as Suez Canal officials have instituted a special method of calculating ship tonnage. According to this method, the calculated volume of the vessel is reduced if the vessel is built with a double bottom structure. When this method is used, and the ship's design includes a true double bottom, the characteristic tonnage of the ship, defined by the total volume of the ship minus the volume of the double bottom, is reduced. the

Ships can choose not to enter the entrance of the Suez Canal, but travel long distances around Africa, thus increasing the overall sailing time and ship operating costs. the

These special Suez regulations have led to the construction of new LNG carriers, which are especially adapted to meet the needs of Suez regulations on the calculated tonnage of ships. It also brings a well-defined double-bottom structure that is clearly acceptable within the definition of a double-bottom and that meets the safety requirements for a double-bottom set by officials. However, the double bottom must be suitable for the transport ship ensuring the loading capacity of the transport ship. the

Contents of the invention

It is an object of the present invention to provide an LNG carrier in which the need for a well-defined double bottom that helps reduce the displacement tonnage of the ship is balanced against the need for a double bottom that provides the carrier with sufficient strength and is suitable for supporting LNG cargo tanks. bottom demand. the

From a purely commercial or economic point of view, there is a need to provide an LNG carrier with the most possible double bottom to reduce financial tariffs when crossing the canal. However, this need must be weighed against the need for a stable hull structure with sufficient compartments and sufficient strength. the

The object of the invention is achieved by a carrier vessel according to claim 1, wherein these aforementioned requirements are balanced. the

According to the invention, the transport ship has at least one cargo tank for transporting liquefied gas, preferably liquefied natural gas (LNG). Preferably, the transport vessel has a plurality of spherical or nearly spherical cargo tanks. The transport vessel is designed with an outer bottom and an inner bottom forming a double bottom. There are a plurality of hollows in the inner bottom, and the hollows are arranged at intervals in the axial direction of the transport vessel, wherein each hollow is designed to accommodate the lower portion of each cargo tank. The distance from the inner bottom to the central axis of the transport vessel accounts for about 25% of the distance from the outer bottom to the main deck (the depth of the vessel). The distance from the insole to the central axis can vary, so the percentage can vary between 15%-30%. the

Preferably, the carrier has side tanks for ballast separated from the double bottom and supporting a double bottom roof on each axial side of the carrier. The space between the inner bottom and the outer bottom (double bottom) is closed and preferably empty or used for ballast. In a preferred embodiment of the invention, the axial bulkhead divides the space of the double bottom into a port side space, an intermediate space and a starboard space. the

The transport vessel has a skirt for supporting the cargo tanks. The skirt is connected to the cargo tank and the inner bottom. the

Each cavity is a structure arranged in the inner bottom to ensure that the space between the inner bottom and the outer bottom is closed, and each cavity goes deep into the space of the double bottom. the

The horizontal section of each cavity varies with the depth of the cavity. Nevertheless, the surface of the inner bottom is greater than the combined surface of the horizontal section of the cavity at the level of the inner bottom. In a preferred embodiment of the cavity, the horizontal section of the cavity decreases towards the bottom of the cavity. The cavity can be a hemispherical structure, or a semi-polygonal structure, and the horizontal section of the cavity can be octagonal, polygonal, circular, etc. the

Description of drawings

Below, an embodiment of the preferred embodiment of the present invention is described in detail with reference to the accompanying drawings, wherein:

Fig. 1 is a perspective view of the double bottom structure of the new transport ship. the

Fig. 2 is a cross-sectional view of the new transport ship in the middle of the hollow. the

Figure 3 is a cross-sectional view of a transport vessel according to a prior design. the

Figure 4 is a perspective view of the lower part of a transport vessel according to a prior art design. the

Detailed ways

The carrier shown in FIGS. 1 and 2 is a new type of LNG carrier 1 designed with a double bottom 2 consisting of an inner bottom 3 and an outer bottom 4 . The main deck of the transport ship is indicated by 23 . The inner bottom 3 has a plurality of cavities 5 corresponding to the number of cargo tanks 6 arranged on the LNG carrier 1 . The LNG carrier 1 also has a skirt 7 to support cargo tanks. the

The horizontal section of the cavity 5 can change the shape and size of the horizontal section along with the depth of the cavity. It can be seen in FIG. 1 that the surface of the insole 3 is larger than the combined surface of the horizontal sections of each cavity 5 . The horizontal section of the cavity 5 at the level of the inner bottom 3 is shown as an octagon. Each hollow 5 is arranged in the inner sole 3 so as to penetrate into the space between the inner sole 3 and the outer sole 4 . A void 5 is incorporated in the insole 3 to ensure that the space between the insole and the outsole remains closed. the

The cavity 5 can be designed as a part of the inner bottom 3 or as an independent structure connected to the inner bottom 3 . The shape of the cavities 5 can vary as long as each cavity 5 can accommodate part of the cargo tank 6 . In FIG. 1 , each void 5 includes a plurality of surfaces that slope down toward the center of the outsole 4 and void 5 . The bottom of the cavity 5 is positioned horizontally parallel to the inner bottom 3 . the

The new inventive design of the LNG carrier shown in FIGS. 1 and 2 will be described below and compared with the existing design shown in FIGS. 3 and 4 . the

A conventionally designed LNG carrier as shown in cross-section in FIG. 3 includes an outer shell 9 and an inner shell 8 . The inner shell 8 is shaped to accommodate the lower portion of the cargo tank 22 . The structure 8a is rectangular to form a support for the cargo tank. The shell is divided into individual spaces or compartments by axial bulkheads 10 , 11 and transverse boxes 12 , see FIG. 4 . The spaces 13a, 13b serve as side deep tanks for ballast water, and the space 13c is a tunnel for piping. Skirts 21 for supporting the cargo tanks are connected to platforms integrally formed with the side tanks. the

In Fig. 2 is shown an LNG carrier according to the present invention. The double bottom 2 is composed of an inner bottom 3 and an outer bottom 4 , and in the inner bottom 3 a cavity 5 for accommodating the lower part of a cargo tank 6 is arranged. Each cavity 5 is constructed by an inclined element 5a and a horizontal element 5b. Axial bulkheads 14 , 15 divide the space of the double bottom into a port side space 16 , an intermediate space 17 and a starboard side space 18 . Side tanks 19 , 20 for ballast water are arranged on the inner bottom 3 and a skirt 7 for supporting the cargo tank is connected to the inner bottom 3 . the

When comparing the structure of the hull in Fig. 3 with the structure of the LNG carrier hull of the present invention in Fig. 2, it is obvious to those of ordinary skill in the art that the LNG carrier in Fig. 3 is not constructed with a double bottom, whereas in Fig. 2 The LNG carrier of the present invention has a well-defined double bottom. In FIG. 3, the tanks 13a, 13b for ballast water are so-called water storage tanks, and each tank fills part of the space located at the bottom and side of the LNG carrier. In FIG. 2 , the double bottom 2 is separated from the spaces 19 and 20 at the sides of the LNG carrier by the inner bottom 3 . The spaces 19, 20 located at the sides function as tanks for ballast water, while the spaces 16, 17, 18 of the double bottom can be used for ballast water or as empty spaces. the

In FIG. 3 , the structure 8 a on top of the water storage tank is rectangular to form a support for the cargo tank, as shown in FIG. 4 . In Fig. 2, the inner bottom 3 of the new LNG carrier is provided with a cavity for accommodating the cargo tank 6, so that the surface of the inner bottom 3 is larger than the combined surface of the horizontal section of each cavity. This proportion does not apply to the top of the water storage tank, see FIG. 4 , where the overhang is rectangular to accommodate the lower portion of the cargo tank 22 . This structure does not work well as a double bottom. the

In FIGS. 2 and 3 , the central axis is indicated by NA. In order to minimize the deflection of the lower part of the supporting skirt, the insole 3 should be positioned close to the central axis. When the distance from the inner bottom 3 to the central axis NA of the transport ship accounts for approximately 25% of the distance from the outer bottom 4 to the main deck 23, the present invention achieves both aspects of the object of the invention; the transport ship and cargo tank support have Sufficient strength and clearly defined double bottoms, and satisfying the safety aspects of the prescribed definition and setting of double bottoms. Furthermore, it is obvious that when calculating the tonnage of a transport ship to enter eg the Suez Canal, the capacity of the double bottom is subtracted. the

Claims (12)

1. carrier with at least one ball-shaped cargo tank, this carrier is used for transport liquefied gases, wherein; The interior end and outer bottom that said carrier has main deck and forms Double bottom; In the interior end, have a plurality of cavities, arrange along the axially spaced-apart of carrier in this cavity, wherein; Each cavity is used to hold the part of each cargo tank, and wherein the distance from the interior end to the carrier axis accounts for the 15%-30% of the distance from the outer bottom to the main deck.

2. carrier according to claim 1, wherein, this carrier is used for conveying liquified natural gas.

3. carrier according to claim 1, wherein, the distance from the interior end to the carrier axis accounts for 25% of distance from the outer bottom to the main deck.

4. according to any described carrier in the claim 1 to 3, wherein, the side jar and the Double bottom that are used for ballace are separated, and are supported in the top of Double bottom.

5. according to any described carrier among the claim 1-3, wherein, the skirt section that is used to support cargo tank is connected to the interior end of Double bottom.

6. according to any described carrier among the claim 1-3, wherein, the space between the interior end and outer bottom is an osed top, and as slack tank or ballast tanks.

7. according to any described carrier among the claim 1-3, wherein, axially bulkhead is port space, intermediate space and right string space with the separated by spaces of Double bottom.

8. carrier according to claim 7, wherein, each cavity be osed top with the space between the end in guaranteeing and the outer bottom, and each cavity is deep in the space of Double bottom for the structure at the end in being arranged in.

9. according to any described carrier among the claim 1-3, wherein, the horizontal section in cavity changes with the degree of depth in cavity, and the surface at the interior end is greater than the horizontal section sum that is positioned at end horizontal surface in each cavity.

10. according to any described carrier among the claim 1-3, wherein, the cavity is semisphere or half polygonized structure, and the horizontal section in cavity is polygon, circle.

11. carrier according to claim 10, wherein, the horizontal section in said cavity is an octagon.

12. according to any described carrier among the claim 1-3, wherein, successively decrease to the bottom in cavity in the horizontal section in cavity.

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