JPS6014959B2 - Distortion-free low temperature tank - Google Patents

Description

[Detailed description of the invention] TECHNICAL FIELD The present invention relates to an improvement of an inner tank type cryogenic tank.

Conventionally, in internal tank-type low-temperature tanks that store low-temperature liquids such as liquefied gas, the inner tank that directly stores the liquid can easily absorb cooling strain, unless an extremely expensive metal with an extremely small coefficient of thermal expansion is used. In order to avoid destruction due to cooling, the inner tank is not simply a container made of flat plates; for example, as shown in Figs. Corrugations 2' and triangular corrugations 3' are orthogonal to each other, and a four-sided pyramid 4' is protruded from the long intersection of the corrugations. Corrugations for absorbing strain are combined in various geometric patterns to create a flat plate. was installed to absorb cooling strain in two-dimensional directions. However, these conventional corrugations have the following problems in common.

○} Corrugations must be installed in two directions, vertically and horizontally, in order to absorb two-dimensional distortions, but if the orthogonal parts become unreasonable and one is made continuous, the distortion in the linear direction cannot be absorbed. Therefore, the continuity of the corrugations in each direction must be broken at the orthogonal part, and the structure must not only be broken but also absorb the strain in the straight direction (continuous direction). Because orthogonal lines are processed, complex undulations occur, and the material inevitably expands and contracts (distorts) along the undulation lines.
In the stretched area, the thickness of the plate becomes thinner and its strength decreases.

■ The stretched portion of the flat plate not only becomes thinner, but also generates large residual stress, which results in a lack of margin for the cooling distortion stress by the amount of residual tensile stress, resulting in a significant deterioration of cooling resistance.

'3} Residual stress in the stretched portion of the flat plate causes stress corrosion. Since expansion and contraction occurs in the '4' flat plate, press forming is always required, which increases equipment costs.

The present invention aims to provide a low-temperature tank consisting of an inner tank having corrugations that eliminates the above-mentioned problems, and its structure consists of a triangular corrugation with a triangular cross section, and a triangular corrugation that is perpendicular to the triangular corrugation. A trapezoidal corrugation having a ladder-shaped cross section, and a triangular corrugation erected on the top surface of the trapezoidal corrugation at the same orthogonal portion, sandwiching the triangular corrugation,
A pair of opposing triangular faces with their tops meeting, and each 3
Two pairs of parallelogram-shaped fours formed by bending and connecting both sides of the square and the triangular corrugation without excess or deficiency in area.
The present invention is a fish strain cryogenic tank characterized by comprising a molded plate body having an angular surface.Since the present invention is configured as described above, the triangular corrugation and the trapezoidal corrugation each have a direction perpendicular thereto. At the same time, the cooling strain along the triangular corrugation is absorbed by the opening of the two pairs of parallelogram-shaped faces at the orthogonal part, and the cooling strain along the trapezoidal corrugation is absorbed by the pair of triangular faces at the orthogonal part. Since each absorption is absorbed by the opening of the surface and the two pairs of parallelogram-shaped surfaces, no problems occur due to cooling, and no expansion/contraction (distortion) in absolute value occurs during the formation, so it is different from conventional corrugation. It has the following advantages compared to a combination of:

Since there is no expansion or contraction in the absolute value of the flat plate (no expansion or contraction in the neutral axis), the wall thickness is always kept constant, and there is no problem such as thinning of the wall and decrease in strength.

Since there is no expansion or contraction in the absolute value of the flat plate, there is no residual stress greater than that produced by simple bending, and therefore the cooling resistance does not deteriorate due to residual stress.

- Since no residual stress is generated, stress corrosion does not occur.

〇 Each corrugation can be formed by simple bending without expansion or contraction in the absolute value of the flat plate, so press forming is not necessarily required, reducing equipment costs.

■ In order to prevent stored liquid from accumulating in corrugations and corrugation intersections, the shape is convex upward and a flow path leading to the flat part is formed.
Allows for smooth cool-down and warm-up. Next, one embodiment of the present invention will be described with reference to the drawings.

In FIG. 3, 1 is a sheet metal serving as the base of the molded plate of the present invention, 2 is a trapezoidal corrugation whose cross section is a ladder shape, and 3 is a trapezoidal corrugation whose cross section perpendicular to the trapezoidal corrugation 2 is triangular.
The square corrugation 4 stands on the top surface of the trapezoidal corrugation 2 at the orthogonal part between the triangular corrugation and the trapezoidal corrugation 2, sandwiching the triangular corrugation 3, and is a pair of opposing triangular corners whose tops meet. surface, 5 is both sides of triangular surface 4 and 3
These are two pairs of parallelogram-shaped four-sided surfaces that are bent and formed to connect the corner corrugation 3 so as not to cause excess or deficiency with the area of the sheet metal 1.

Next, the effects of the above embodiment will be explained.

First, looking at the cooling strain, when the sheet metal 11 comes in contact with the storage, the sheet metal 1 shrinks on cooling in two dimensions, but one contraction occurs due to the opening of the triangular corrugations 3, and the other contraction occurs due to the opening of the trapezoidal corrugations 2. Since this is compensated for by At that time, "Triangular corrugation 3
The contraction along the trapezoidal corrugation 2 is caused by the opening of the opposing four-sided surface 5, and the contraction along the trapezoidal corrugation 2 is caused by the opening of the opposing triangular surface 4.
Also, since the adjacent four corners 5 each open to absorb the energy, problems at orthogonal portions do not occur. Therefore, an inner tank made of a molded plate body made up of a series of such units will not cause any problems due to thermal distortion caused by the injection and removal of stored liquid. Next, regarding processing points, the triangular corrugation 3 and the trapezoidal corrugation 2 are formed by bending and forming the sheet metal 1, so the absolute value (neutral axis of the cross section) of the sheet metal 1 expands and contracts, causing distortion. It is clear that this will not happen.

If expansion and contraction occurs, it is at the orthogonal intersection between the triangular corrugation 3 and the trapezoidal corrugation 2, but the triangular surface 4 is a triangle that simply stands up from the top surface of the trapezoidal corrugation 2, and the top surface that rises at that time. Since the height from 1 to 3 corresponds to the height at which the trapezoidal corrugation 2 is compressed in the longitudinal direction and naturally rises due to the formation of the triangular corrugation 3, no expansion or contraction of the sheet metal 1 occurs. The four corners 5 are raised 3
Since it is a parallelogram-shaped surface that is necessarily formed between both sides of the corner surface 4 and the triangular corrugation 3 by a polygonal line formed so as not to cause an excess or deficiency in area, no expansion or contraction will naturally occur.

Therefore, the sheet metal 1 does not expand or contract at any point during processing, causing its thickness to become thinner or thicker. Therefore, there is no decrease in strength or residual stress, and residual stress on the tensile side is prevented. It also does not cause stress corrosion. In addition, since it can basically be formed only by bending (even if it is actually formed using a press), there is no processing restriction that requires press forming as in the past. Alternatively, even if press-forming is used, the energy required for simply bending the sheet metal is sufficient, and a huge amount of energy for expansion and contraction is not required, and an extremely small press-forming machine is sufficient, reducing equipment costs. Although the above embodiments have been shown for the bottom of the tank inner tank, it is of course possible to use it for the side wall as well.

Also, even if it is used on the bottom, it does not need to be used on the entire surface, and may be used in combination with other appropriate patterns.
The present invention has three embodiments as specifically described above with respect to the embodiments.
Square corrugation and trapezoidal corrugation are orthogonally arranged 2
At the same time, a pair of triangular faces and two pairs of parallelogram-shaped quadrangular faces are formed at the orthogonal part so as to absorb the cooling strain in the dimensional direction, so that cooling along each corrugation is achieved. Since it also absorbs strain, problems caused by shrinkage when cooled by the stored liquid do not occur, and it is also easy to process, which has the advantages W to A explained at the beginning compared to the conventional example.

Brief description of the drawings Figure 1 is a plan view of the bottom of a conventional tank, and Figure 2 is a plan view of the bottom of a conventional tank.
FIG. 3 is a detailed view of an embodiment of the present invention shown in correspondence with FIG. 2. FIG.

1... sheet metal, 2... trapezoidal corrugation,
3...triangular corrugation, 4...3
Corner surface, 5...4 corner surface.

Figure 1 Figure 2 Figure 3

Claims (1)

[Claims] 1. A triangular corrugation with a triangular cross section, a trapezoidal corrugation with a trapezoidal cross section orthogonal to the triangular corrugation, and a trapezoidal corrugation that is erected on the top surface of the trapezoidal corrugation at the orthogonal section with the triangular corrugation sandwiched between the above-mentioned triangular corrugations; The faces of a pair of opposing triangles that meet, both sides of each triangle, and the above 3
A strain-free low-temperature tank characterized by comprising a molded plate body having two pairs of parallelogram-shaped four-sided faces which are bent and formed to connect with a corner corrugation without excess or deficiency in area.