JPS6121885A - Liquefied gas carrier - Google Patents

Abstract

PURPOSE:To diminish the rocking of a tank by providing plural number of diaphragm type supporting members having wave-shaped grooves and minute holes, between the outer periphery of a spherical LNG tank and the inner wall of a tank supporting part provided in a hull structure, and supporting said tank by a fluid. CONSTITUTION:A spherical gas tank 3 containing a liquefied gas is housed in a container 2 as a supporting part provided in a hull structure part, and supported by a fluid 9. Plural number of diaphragm type supporting members 14 having wave-shaped grooves 16 and minute holes 15 are provided between the outer periphery of the tank and the inner wall of the container 2. Thereby, the fluid 9 is restrained from freely moving when a hull rocks, preventing the spherical tank 3 from being subjected to rocking to a great extent.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a liquefied gas carrier.

[Conventional technology]

In conventional spherical tank type liquefied gas carriers, the second
As shown in the cross-sectional view of the figure, a spherical tank 3 containing liquefied gas is supported by a spherical tank welded to the circumference near its equator and a Cuscart upper part 6, which combines the weight of the tank and the weight of the liquefied gas inside. , and the upper part of the spherical tank skirt 6
is supported by the hull internal structure 2 via the spherical tank skirt lower part 7, the outside of the spherical tank 3 is covered with a heat insulating material 4, the upper surface is further covered with a spherical tank cover 5, and , the outside of the hull internal structure 2 becomes a hull external structure 1 and constitutes the main hull.

[Problem that the invention seeks to solve]

However, in such a spherical tank, since the entire weight of the spherical tank 3 and its built-in liquefied gas is supported by the spherical tank skirt upper part 6, the supporting point, that is, the vicinity of the weld between the skirt upper part 6 and the spherical tank 3, is supported by the spherical tank. In addition to increasing the thickness of the plate to withstand the weight, it is also necessary to support the fluctuating lateral forces caused by the movement of the built-in liquefied gas in the tank when the ship is rocking at the support point. It is necessary to design the strength near the support point with a considerable margin, and since liquefied gas is generally stored at low temperatures, spherical tanks need to be made of expensive materials such as aluminum. Skirt upper part 6
Also, since aluminum and steel cannot be welded, they must be made of the same material, such as aluminum, so thick materials must be used to support large loads, which increases material costs. In order to prevent this, the lower part 7 of the spherical tank skirt should be made of steel, and at the connection part 8 with the upper part, aluminum and steel should be connected using a special connection method such as explosive bonding.

It was filed by the applicant as Patent Application No. 44500 in 1982.

To explain Fig. 3, Fig. 3 is a cross-sectional view corresponding to Fig. 2, and in the same figure (*, the same symbols as in Fig. 2 indicate the same members as in Fig. 2). , 2' is a container provided inside the hull, 9 is a buoyancy generating liquid, 10 is a free surface of the buoyant force generating liquid 9, 11 is a liquefied gas built in a tank, 1
2 is a free surface of the liquefied gas 11, and 13 is a tank support member.

In such a tank, a container 2' provided inside the hull is made watertight so as to wrap around the outside of the spherical tank 3, and a buoyancy generating liquid 9 is placed between the two so as to have a free surface 10. The buoyancy generating liquid 9 is generally water or seawater, but a liquid with a specific gravity greater than 1 and a freezing point as low as possible is advantageous.

The spherical tank 3 is not supported by a skirt as shown in FIG. 2, but is supported by the hull internal structure 2 by elastic support members 13 that can expand and contract to some extent at several locations near the equatorial plane.

Therefore, the spherical tank 3 is supported in the vicinity of its equator by the tank support member 13 so that it can move up and down, and the total weight of the spherical tank 3 and the liquefied gas 11 is evenly supported by the buoyancy generating liquid 9. Therefore, the plate thickness of the spherical tank and its supporting members can be reduced, leading to savings in material costs and man-hours.
It offers many advantages.

However, in the case shown in Fig. 3, when the ship oscillates, especially when it rolls sideways, the buoyant force generating liquid 9 oscillates, and as a result, the free surface 10 moves up and down in front, back, left and right, the direction of buoyancy changes, and the spherical tank This has the disadvantage that the spherical tank 3 and the hull internal structure 2 may collide.

The present invention is an attempt to solve these problems of conventional liquefied gas carriers.In a liquefied gas carrier in which the liquefied gas tank is supported by the buoyancy of the liquid, the liquefied gas tank is damaged by the rolling and pitching of the hull. The purpose of the present invention is to provide a liquefied gas carrier that reduces vibration and prevents collision damage between the liquefied gas tank and the hull structure.

[Failure to solve the problem]

For this reason, the liquefied gas carrier of the present invention is provided with a container for housing a substantially spherical tank containing liquefied gas inside the hull, and a liquid is placed between the tank and the built-in container so that there is a free surface between the tank and the container. In a ship that supports and transports part or all of the weight of liquefied gas by the buoyancy of the liquid,
The present invention is characterized in that a plurality of diaphragm-shaped supports having wave-shaped grooves and minute openings are provided between the outer periphery of the tank and the inner wall of the container, and are arranged concentrically with the horizontal cross section of the tank. .

[Effect]

According to the above-mentioned liquefied gas carrier, the outer surface of the liquefied gas tank and the inner wall of the container are connected by a diaphragm having concentric corrugated grooves, and the diaphragm is made with minute holes, so that the buoyancy-generating liquid flows through the diaphragm. The tank passes through the liquefied gas tank slowly to cope with changes in buoyancy during cargo handling, but it cannot move at a speed that would normally cause the liquefied gas tank to oscillate, which reduces the oscillation of the liquefied gas tank and prevents damage from collision with the ship's hull structure. can do.

〔Example〕

Hereinafter, a liquefied gas carrier will be described as an embodiment of the present invention with reference to the drawings. Fig. 1 is the same as that described above in Fig. 3. 16 is a concentric wave-shaped groove, and 15 is a minute aperture.

In this embodiment, the hull internal structure 2 is made watertight to form a container that wraps around the outside of a spherical tank 3, and a buoyancy generating liquid 9 is placed between the two so as to have a free surface 10. . A diaphragm-shaped support member 14 having a corrugated groove 16 concentric with the horizontal cross section of the spherical tank 3 is provided at several locations on the outer circumference of the spherical tank 3. The supporting material 14 is provided with minute openings 15 through which the buoyancy generating liquid 9 can pass through at a very low speed.

The effects of the buoyant force generating liquid 90 in this embodiment are almost the same as those in FIG. To move freely between bodies 2,
It is limited by diaphragm-like supports 14 provided at several locations. Since the diaphragm-shaped support member 14 has elasticity due to the concentric wave-shaped grooves 16 provided thereon, it is possible to move the spherical tank 3 up and down, but against the buoyancy-generating liquid 9, When the ship is rocking, it functions in the same way as a watertight wall. Therefore, the movement of the buoyant force-generating liquid 9 is limited to the area between the free surface 10 and the diaphragm-like support member 14 immediately below, so that large movements of the spherical tank 3 are prevented.

In addition, during cargo handling, the buoyancy generating liquid 9 is applied to the diaphragm-shaped support material 14 depending on the amount of liquefied gas 11 in the spherical tank 3.
However, since the amount of movement and the speed of movement in this case are small, it is possible to move through the minute apertures 15 provided in the diaphragm-shaped support member 14.

〔Effect of the invention〕

As detailed above, according to the liquefied gas carrier of the present invention, the horizontal cross section of the tank is formed between the outer periphery of the approximately spherical tank containing the liquefied gas and the inner wall of the container provided in the hull for accommodating the tank. With a simple configuration consisting of multiple concentrically arranged Guyaflam support members with corrugated grooves and micro-holes, it is possible to reduce the movement of the tank when the ship oscillates from front to back or from side to side. It has the advantage of being able to completely prevent collisions between the trout tank and the hull structure.When the hull tilt change is small, such as when loading cargo in a trench, the buoyancy generating liquid flows through the micro holes provided in the diaphragm support. Because it moves, it has the advantage of being able to maintain the tank attitude in line with a predetermined hull attitude.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of an embodiment of a liquefied gas carrier according to the present invention. FIG. 2 is a cross-sectional view of a known spherical tank type liquefied gas carrier, and FIG. 3 is a cross-sectional view of a liquefied gas carrier according to an earlier application filed by the applicant of the present application.

Claims (1)

[Claims] A container containing a substantially spherical tank containing liquefied gas is provided inside the hull, and the liquid is filled so that there is a free surface between the tank and the container, so that part or all of the weight of the tank and the built-in liquefied gas exceeds the above. In a ship that is supported and transported by the buoyancy of a liquid, a plurality of diaphragm-shaped supports having corrugated grooves and minute openings arranged concentrically with a horizontal cross section of the tank between the outer periphery of the tank and the inner wall of the container. A liquefied gas carrier characterized by having: