JPS5839114B2 - Low temperature liquefied gas carrier - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a low temperature liquefied gas carrier having a semi-membrane tank structure.

In general, the tank structure of a normal-pressure low-temperature liquefied gas carrier is as follows:
We focused on two points: how to provide heat insulation to minimize the amount of gas that evaporates due to heat intrusion from the outside, and how to disperse tank contraction at low temperatures to reduce thermal stress. It is designed to be highly economical and safe.

Tank types include independent type, membrane (thin film) type, and semi-membrane type, which is an intermediate between the two types.

In the independent system, the tank is made of thick plates that can support the weight and pressure of the liquid inside the tank, making it a strong, self-supporting structure.

In the membrane system, the tank is made of a thin plate with wrinkles for temperature contraction, and the tank itself only serves to prevent liquid and gas from leaking to the outside.The weight and pressure of the liquid inside is determined by the heat shield on the outside of the tank. It is supported by the hull structure through timber.

In the semi-membrane system, the tank plate thickness takes a value between the above two, and although the tank itself cannot support the weight and pressure of the liquid inside, it does have a certain degree of rigidity.

By the way, the top of the tank is affected by sloshing (
However, in a carrier ship 2 equipped with a semi-membrane type tank 1 as shown in Fig. 3, this load is applied through the heat insulating material 3 because the tank 1 does not have the rigidity of an independent type tank. Generally, it is supported by the upper surface portion 4a of the hull 4 having a double shell structure.

However, a double shell structure, in which the two shells are connected by connecting bones, increases the weight and requires welding between the connecting bones and the inner shell within the narrow double shell. Therefore, workability is poor.

In addition, for thermal insulation construction, it is necessary to inject a liquid thermal insulation material between the inner shell and the tank 1 and foam it on-site, so in order to obtain a highly reliable and homogeneous thermal insulation material 3, careful care must be taken. This requires more work and makes the heat insulation work more troublesome.

This invention provides a low-temperature liquefied gas carrier equipped with semi-membrane tanks, which eliminates the upper surface of the hull to reduce the weight of the vessel, facilitate heat insulation work, and facilitate maintenance and inspection. The purpose is to

An embodiment of the present invention will be described below with reference to FIGS. 1 and 2.

The bottom part 5, the side part 6, and the hull transverse bulkhead part I have a double shell structure, but the deck part 8 has a single shell structure, that is, a structure in which the upper surface part of the hull 9 is excluded.

The low-temperature liquefied gas tank 10 is housed inside the hull having the above structure, and is covered with a heat insulating material 11.

Large bones 12a and small bones 12b are arranged, for example, in a planar grid pattern inside the tank top surface portion 10a, and the planar position of the large bones 12a is determined by adjusting the position of the large bones 12a on the lower surface of the deck portion 8 having a single shell structure. The reinforcing bones 15 are made to almost match the reinforcing bones 15.

The heat insulating material 11 of the tank top surface portion 10a is formed by fixing a large number of pre-formed panels along the outer surface of the tank top surface portion 10a, and the reinforcing large ribs are connected to the top surface of this heat insulating material 11 by means of adhesive. connected by means.

In the above configuration, the weight and pressure of the liquid in the tank 10 are supported by the hull 9 having a double shell structure through the heat insulating material 11.

In addition, sloshing (undulation) of the liquid occurs at the tank top surface 10a.
However, this load is reliably collected by the small bones 12b and large bones 12a provided in a planar lattice shape, and therefore does not locally generate excessive stress on the tank top surface portion 10a.

The load thus collected is ultimately applied to the large bone 1.
It is transmitted through 2a to the reinforcing large bone 15 of the deck section 8 having a single shell structure, and is supported.

Here, since the plane position of the large bone 12a substantially coincides with the reinforcing large bone 15, the load can be transmitted smoothly.

As described above, this invention is capable of preventing liquid sloshing (ripples).
The load acting on the top of the tank is collected by the large bones and small bones provided inside the top of the tank, and is transmitted to the reinforcing large bones of the deck of the single-layered shell structure, and these reinforcing large bones perform the above-mentioned sloshing. By supporting the load, the upper surface of the hull can be eliminated, greatly reducing the ship's weight and work hours.

In addition, thermal insulation work can be performed using a panel method in which a quality-guaranteed standard heat insulation material 11 (thermal insulation panel) is attached to the top surface of the tank, making it easier to perform thermal insulation work, maintenance, and inspection around the tank. Can be done.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional front view of a carrier according to an embodiment of the present invention, FIG. 2 is a longitudinal sectional side view of the same, and FIG. 3 is a longitudinal sectional front view of a conventional carrier. 5... Bottom of the ship, 6... Side part of the ship, 7...
...Hull transverse bulkhead section, 8... Deck section, 10.
...Low-temperature liquefied gas tank, 10a...tank top, 11...heat insulating material, 12a...
...Dog bone, 12b...Small bone, 15...
Large bones for reinforcement.

Claims (1)

[Claims] 1 Double shell structure for the bottom, side and hull transverse bulkheads,
A semi-membrane type low-temperature liquefied gas tank is housed inside the hull with a single-layer deck structure, and large bones and small bones are arranged in a planar lattice pattern inside the top of this tank, and
The position of the large bone on the plane is approximately aligned with the reinforcing large bone of the deck of the single-shell structure, and this reinforcing large bone is connected to the upper surface of the heat insulating material covering the outer surface of the top surface of the tank. A low-temperature liquefied gas carrier, characterized in that the tank internal load applied to the top part is supported by the reinforcing large bones.