DE1963652C3 - Storage tank for low-boiling liquefied gases - Google Patents

Abstract

1,270,728. Liquefied gas tankers. BRIDGESTONE ERIKA GAS K.K. 12 Dec., 1969 [26 Feb., 1969], No. 60861/69. Headings B7A and B7S. [Also in Division F4] In a liquefied gas storage container having an outer rigid shell, 1 which may be the double hull of a ship, lined with insulating material 2 and an inner tank 3, the tank 3 is connected to the shell 1 by a rigid trunk 5 and is self sustaining by virtue of hanging from the trunk and the rigidity of its edges and corners when assembled. The trunk, insulated by material 8, is fastened to the centre of the top plate of the tank 3 and to the shell 1 via sealings 7 and 6, and the manner of attachment allows the inner tank to contract and expand without causing undesirable stress therein. The tank 3 comprises thin steel, or nickel-steel plates, and on initial loading undergoes a contraction, on being loaded further the tank walls are pressed against the insulation lining. The tank maintains a stable shape in the " no-load " condition, and may be of any suitable cross-sectional shape. The container is charged and exhausted via pipes passing through a central orifice in the trunk closed by a gas tight seal.

Description

The invention relates to a storage tank for low-boiling liquefied gases with a self-supporting structure Inner container to hold the liquefied gas and a rigid one, the inner container surrounding outer jacket as well as a pressure-resistant, heat-insulating layer on which the filled inner container is flexibly supported.

Such a storage tank is already known. The one is attached in the middle of the upper tank wall Filler neck movably arranged relative to the outer container. This relative freedom of movement the filler neck is necessary because the inner tank is inside the heat insulating layer is floating, namely the inner tank rests in both loaded and unloaded Condition on a liquid between the inner tank and the heat-insulating layer. Will the tank loaded and thereby cooled to a temperature corresponding to the temperature of the liquefied gas, the liquid rises between the inner tank wall and the heat-insulating layer on the side walls of the inner tank according to the load, this liquid from the lower Area is displaced so that the altitude of the inner tank decreases relative to the outer tank. So there from the area between the bottom surface of the inner tank and the bottom surface of the heat insulating Layer when the inner tank is loaded, the liquid is displaced and thus the inner tank in the outer container drops, the filler neck must be in the middle of the upper tank wall relative to the outer Container be movably arranged. However, this known storage tank construction is bad for Suitable for the transport of liquefied gases, as it is known that shocks and rocking movements occur. which permanently deform the inner tank due to its floating suspension (USA ^ Patent 3,319,430).

In another known storage tank construction, the inner tank consists of a film, the Wall thickness is in the order of a few tenths of a millimeter. The inner tank is therefore not self-supporting and must be suspended by special constructive measures. this happens either on the ceiling of the outer »container or the heat-insulating layer, or in the case of an inner tank that is completely open at the top, by a special one Suspension of the upper rim of the inner tank from the ceiling of the outer container. Also at this known storage tank construction occur in particular with rocking movements, as they occur in transport on ships often causes material stresses in the wall of the inner tank (French patent 1,538,578).

The object on which the invention is based is to create a storage tank of the type m defined at the outset, in which, in the loaded state and at a low temperature, no more material stresses occur in the inner tank.

This object is achieved according to the invention in that the walls of the inner container when empty Inner container have a concave shape towards the interior of the inner container, which when filled inner container is formed convexly towards the outside.

In contrast to the prior art, the inner container is no longer floating in the outer Containers stored or hung in several places on the outer jacket, but designed to be self-supporting, however, part of the wall of the inner container in the unloaded state and at room temperature sags slightly, while in the loaded state Condition of the inner container and, at low temperature, a firm attachment of the inner container the pressure-resistant, heat-insulating layer. Therefore, no relative Movement between the inner container and the outer container occur. You also get the Advantage that the edges and corners of the inner container are not due to the low temperature due to contraction of the material are lifted from the pressure-resistant, heat-insulating layer, because the material contraction is completely compensated for by the slack.

A storage tank constructed according to the invention has a comparatively simple structure and can be therefore also produce relatively cheap.

The inner container can have the shape of a polygon in cross section, the carrying capacity of the Inner container increases with increasing number of corners. In a preferred manner, the inner container in Cross-section have the shape of a rectangle. Here, too, it is ensured that the inner container essentially free to shrink and revolve around the stationary point which is in the center of the lid section lies, can expand freely.

In the following the invention will be explained with reference to a Ausfühningsbeispiels with reference to the drawing whose only illustration sehe- '<matically shows a SchnittdarsteHung through the storage tank according to the invention.

The storage tank can be attached to a ship, for example, which is used to transport liquefied Gases is used. The ship has a double-walled hull, which has the rigid outer shell 1 of the Forms storage tanks. Closes to this outer jacket

calibrate inside to form a pressure-resistant, heat-insulating edge Layer 2, for example made of resin or polystyrene foam An inner container 3, which is stable at low temperatures and for example Can be made from nickel steel plates or stainless steel plates is on the inside as a lining used pressure-resistant, heat-insulating layer 2 arranged.

The inner container 3 consists of gradually and gently curved walls 3 a and curved edges 3 b, which merge into one another at the spherical corners 3 c. The thickness of the walls of the inner container is chosen so that the inner container 3 essentially supports itself. It is yielding, but does not collapse.

An upper plate of the inner container 3 is connected to a shaft 5 which is reinforced by struts 4. A flange formed by the lower end of the shaft 5 is gas-tightly attached to the central portion of the upper plate. Another flange, which is formed by the upper end of the shaft 5, is firmly connected to the double-walled outer jacket. This is done with the help of pads 6 and 7, respectively. A heat-insulating part 8 is pushed between the outer jacket 1 and the shaft 5 so that the low temperature in the inner container 3 cannot be transferred to the ship's hull.

Various pipelines are led into and out of the inner container 3 through the shaft 5. A 3 " The cover (not shown) serves to seal the opening of the shaft 5 in a gas-tight manner, with the tubes can be passed through the lid.

When low-boiling liquefied gas is filled into the inner container 3, it begins to shrink in the area of the shaft 5 fixed in the middle of the upper plate, starting from the position at room temperature door (solid line), and then under no load , but already at a low temperature assumes a position as shown by the dash-dotted line 3 ', without stress concentrations occurring. When the inner container 3 is filled with low-boiling liquefied gas, the radii of curvature of the edges 3 b and the corners 3 c in the upper area of the inner container have changed somewhat, so that the profile of the inner container at low temperature and load looks as it is due to the Dashed line 3 "is shown. Even now there is no stress or stress concentration. In the position that is assumed at low temperature and stress (line 3"), the wound of the inner container 3 is pressed against the pressure-resistant, heat-insulating layer 2 by the internal pressure , but with the exception of the upper edges 3 b and the upper corners 3 c. This puts the mechanical load on the inner container 3 on the outer shell! 1 transferred.

In this way, the inner container 3 of the storage tank assumes a stable shape when it is subjected to an internal pressure due to the filling with low-boiling liquefied gas at a low temperature. Furthermore, the inner container 3 essentially retains its shape, that is to say it does not collapse when not under load. This is due to the relatively solid structure of the inner container and the suspension of the inner container on the rigid shaft. The strength and rigidity of the edges 3 b and the corners 3 c is selected taking into account the relatively low strength of the walls 3 α , so that the inner container 3 essentially retains its shape even under load, with a uniform shrinkage and expansion depending on the Temperature and exposure to the filled liquefied gas is ensured.

The inner container 3 has a substantially rectangular cross section. The inner container 3 can also have other shapes.

In all embodiments, however, the soft or gradual curvature is the fundamentally flat one Walls of the inner container chosen so that the walls in when loaded and low temperature be brought smooth and intimate contact with the pressure-resistant, heat-insulating layer 2, so that the mechanical stability of the inner container is improved.

1 sheet of drawings

Claims (1)

Patent claims: 1, storage tank for low-boiling liquefied gases with a self-supporting Inncnbc- S holder for receiving the liquefied gas and a rigid, the inner container enclosing outer jacket and a pressure-resistant, heat-insulating layer arranged between this and the inner container, on which the gc- ιυ filled inner container resiliently supported because - \ , characterized in that the walls. (3 a) of the inner container (3) when the inner container (3) is empty have a shape which extends concavely towards the interior of the inner container (3) and which is convex outwards when the inner container (3) is filled. 2, storage tank according to claim 1, characterized in that that the inner container (3) has the shape of a polygon in cross section, 3, storage tank according to claim 1, characterized in that that the inner container (3) has the shape of a rectangle in cross section.