KR100547986B1 - Manufacturing method of rib type membrane for lng storage tank - Google Patents

Abstract

The present invention relates to a method for manufacturing a new rib-type membrane that can be applied to an enlarged liquefied natural gas storage tank that is not applicable to a general flat membrane, the cross-sectional shape of the upper rounding portion, the upper and lower portions of the upper rounding portion It is divided into a side rounding part, a bottom rounding part below the side rounding part, and a plurality of ribs formed in a concave round shape at a predetermined interval along a length direction of the side rounding part are formed in parallel in a plurality of ribs. ; The cross-sectional shape is divided into an upper rounding portion, side rounding portions of both lower portions of the upper rounding portion, and a bottom rounding portion of the lower portion of the side rounding portion, and a small wrinkle portion having a size smaller than the large wrinkle portion is orthogonal to the large wrinkle portion. While being formed in plurality in parallel; A method of manufacturing a rib-type membrane for a liquefied natural gas storage tank, wherein the major wrinkle portion and the small wrinkle portion intersect to form an intersection portion, the method comprising: preparing a flat membrane to be formed; Forming a large wrinkle portion on the prepared flat membrane, but forming only the upper and lower round portions of the large wrinkle portion and not forming the side round portion; The small wrinkles are formed on the flat membrane formed through the formation of the large wrinkles, and the upper rounding portion, the side rounding portion, and the bottom rounding portion are formed in the whole small wrinkle portion, and at the same time, the upper rounding portion of the large wrinkle portion is secondary molded. And forming a small wrinkle portion to form an intersection between the large wrinkle portion and the small wrinkle portion; The side rounding portion and the rib portion of the large wrinkle portion are first formed on the flat membrane formed through the small wrinkle portion forming step, and at the same time, the small wrinkle portion and the large wrinkle portion are finally corrected to form the small wrinkle portion and the large wrinkle portion. Deadline to complete the process; Characterized in that comprises a.

LNG, storage tank, ribs, membrane, large wrinkles, small wrinkles

Description

Ribbed Membrane Manufacturing Method for Liquefied Natural Gas Storage Tank {MANUFACTURING METHOD OF RIB TYPE MEMBRANE FOR LNG STORAGE TANK}

1 is a perspective view of a flat membrane for a liquefied natural gas storage tank according to the prior art,

2 is a cross-sectional shape of a large wrinkle portion and a small wrinkle portion according to the prior art,

3 is a partial top view of the ribbed membrane,

4 is a partially enlarged perspective view of FIG. 3;

5 is a cross-sectional view taken along line A-A of FIG.

B-B cross-sectional view of Figure 3 of Figure 6,

7 is a cross-sectional view taken along line C-C of FIG.

8 is a photograph of the large wrinkle portion 100 formed by the present comparative example,

9a to 9c are photographs of the large wrinkle portion 100 formed by the embodiment according to the present invention,

10a and 10b are photographs of the mold used in the finishing step to implement the embodiment according to the present invention,

11A to 11C are photographs for showing the working process of this embodiment.

<Description of Symbols for Main Parts of Drawings>

100: large wrinkle portion 110: rib portion

200: small wrinkles 300: intersection

R1: upper rounding part R2: side rounding part

R3: Bottom rounding part

The present invention relates to a method for manufacturing a ribbed membrane for a liquefied natural gas storage tank.

In general, natural gas maintains its liquid state when it reaches a temperature of minus 162 ℃ at atmospheric pressure, so it can be stored as a liquid in a storage tank having a thermal insulation function. The storage structure of the LNG storage tank is composed of a material that effectively blocks heat transfer and a membrane having a LNG sealing function. As the metal material constituting the membrane, a material resistant to low temperature brittleness is used. Membranes are designed and manufactured to expand and contract in response to changes in temperature and load generated when injecting or removing liquefied natural gas into a storage tank.

The membrane consists of a thin membrane with a thickness of about 0.5 to 1.2 mm.

Membrane used in liquefied natural gas storage tanks are widely known as the TECHNIGAZ method with wrinkles formed as a measure of thermal expansion and contraction for thermal expansion and thermal contraction, and the GAZTRANSPORT method employing a flat membrane using the characteristics of INVAR.

The present invention relates to a method for manufacturing a membrane to which the TECHNIGAZ method is a membrane formed wrinkles.

1 is a perspective view of a flat membrane for a liquefied natural gas storage tank according to the prior art.

FLAT MEMBRANE is a sheet-shaped membrane installed on the inner wall of the LNG storage tank.

In the flat membrane, a plurality of large corrugation (LC) 100 are formed in parallel in a sheet-like flat membrane, and a small corrugation (SC) 200 is orthogonal to the large corrugation part 100. It is formed in plurality in parallel.

In addition, the intersection portion 300 having a shape for preventing stress concentration is formed at a portion where the large wrinkle portion 100 and the small wrinkle portion 200 intersect.

Figure 2 shows the cross-sectional shape of the large wrinkle portion 100 and the small wrinkle portion 200 according to the prior art.

As shown, each of the large wrinkle portion 100 and the small wrinkle portion 200, the side rounding portion (R2), the side rounding portion extending downward from both lower portions of the upper rounding portion (R1) and the upper rounding portion (R1) It consists of a bottom rounding portion (R3) extending from the bottom of (R2) to meet the flat surface of the bottom.

The upper rounding part R1, the side rounding part R2, and the bottom rounding part R3 each have roundness, and the rounding part depends on whether the major wrinkle part 100 or the small wrinkle part 200 is present. The size of is different. In addition, the upper rounding part R1 and the side rounding part R2 have a convex round shape, and the bottom rounding part R3 has a concave round shape.

The large wrinkle portion 100, the small wrinkle portion 200, the intersection portion 300 all form a shape that can correspond to the thermal expansion and contraction, and is also produced by plastic molding of the flat membrane.

However, forming the wrinkles of the plate membrane is a very demanding task requiring that the plate be plastically deformed into the shape of the wrinkles but no deformation of its thickness is required.

For example, when processing a pleated part in a 1.2 mm thick flat membrane, the pleated part must maintain a thickness of 1.2 mm. The tolerance for this is only 60 microns.

On the other hand, in the case of the flat membrane as described above can be used only for liquefied natural gas storage tank having a capacity of 145 km ³ It is known that it is difficult to use more than that.

However, liquefied natural gas storage tanks are required to be larger in size due to the rapid increase in the use of liquefied natural gas, and thus, a technology for manufacturing new membranes that can be applied to such large scale natural liquefied natural gas storage tanks. This is very necessary.

An object of the present invention is to propose a method for fabricating a new ribbed membrane that can be applied to an enlarged liquefied natural gas storage tank that is not applicable to a general flat membrane.

According to the present invention, the cross-sectional shape is divided into an upper rounding part, side rounding parts of lower and lower parts of the upper rounding part, and a bottom rounding part of the lower part of the side rounding part, and a plurality of ribs formed in a concave round is formed in the side rounding part. A plurality of large wrinkle portions formed at predetermined intervals along the longitudinal direction are formed in plural in parallel; The cross-sectional shape is divided into an upper rounding portion, side rounding portions of both lower portions of the upper rounding portion, and a bottom rounding portion of the lower portion of the side rounding portion, and a small wrinkle portion having a size smaller than the large wrinkle portion is orthogonal to the large wrinkle portion. While being formed in plural in parallel; A method of manufacturing a rib-type membrane for a liquefied natural gas storage tank, wherein the major wrinkle portion and the small wrinkle portion intersect to form an intersection portion, the method comprising: preparing a flat membrane to be formed; Forming a large wrinkle portion on the prepared flat membrane, but forming only the upper and lower round portions of the large wrinkle portion and not forming the side round portion; The small wrinkles are formed on the flat membrane formed through the formation of the large wrinkles, and the upper rounding portion, the side rounding portion, and the bottom rounding portion are formed in the whole small wrinkle portion, and at the same time, the upper rounding portion of the large wrinkle portion is secondary molded. And forming a small wrinkle portion to form an intersection between the large wrinkle portion and the small wrinkle portion; The side rounding portion and the rib portion of the large wrinkle portion are first formed on the flat membrane formed through the small wrinkle portion forming step, and at the same time, the small wrinkle portion and the large wrinkle portion are finally corrected to form the small wrinkle portion and the large wrinkle portion. Finishing steps to complete; Characterized in that comprises a.

Prior to the description of the present invention, the ribbed membrane which is the object of the present invention will be described first.

3 is a partial top view of the ribbed membrane, FIG. 4 is a partially enlarged perspective view of FIG. 3, FIG. 5 is a cross-sectional view taken along line AA of FIG. 3, FIG. 6 is a cross-sectional view taken along line BB of FIG. 6, and FIG. .

Such shaped membranes are referred to as ribbed membranes above and below.

Comparing the characteristics of the ribbed membrane with the conventional standardized flat membrane, the ribbed membrane has a rib portion having a rounded concave at a predetermined interval along the longitudinal direction in the side rounding portion R2 of the large wrinkle portion 100. 110 is formed.

This new shaped ribbed membrane is not a newly created part of the Applicant and therefore the present invention is not directed to such a ribbed membrane product itself.

Applicant has newly developed a method for producing such ribbed membranes, and the present invention relates to a method for producing such ribbed membranes of this new shape.

Comparative example:

First, the comparative example which can be compared with this invention is demonstrated first.

This comparative example is a method tested by the applicant of the present invention to produce ribbed membranes.

(1) Preparation

Prepare a flat membrane to be molded.

In general, the prepared flat membrane is coated with a vinyl sheet or the like to protect the surface.

(2) formation of large wrinkles

It is a step of forming a large wrinkle portion 100 on the prepared flat membrane.

At this time, only the upper rounding part R1 and the bottom rounding part R3 of the large wrinkle part 100 are molded, and the side rounding part R2 is not molded.

(3) small wrinkles forming step

First, the small wrinkles 200 are formed on the flat membrane in which the large wrinkles 100 are formed.

At this time, the whole of the small wrinkles 200, that is, the upper rounding portion (R1), the side rounding portion (R2), the bottom rounding portion (R3) is formed.

Meanwhile, at the same time, the small wrinkle part 200 is molded, and the upper rounding part R1 and the rib part 110 of the large wrinkle part 100 are molded, and the cross part 300 is also molded.

(4) finishing stage

Finally, the molding of the small wrinkle part 200 and the large wrinkle part 100 of the plate membrane undergoing the small wrinkle part forming step is finally corrected.

At this time, at the same time as the final molding of the small wrinkle portion 200 and the large wrinkle portion 100 was completed, the side rounding portion R2 of the large wrinkle portion 100 was molded.

8 is a photograph of the large wrinkle portion 100 manufactured by the comparative example.

As shown in FIG. 8, the deformation caused by the concentration of stress in the upper rounding part R1 on the upper part of the rib part 110 resulted in a failure in the straightness of the straight part of the upper rounding part. Therefore, it was confirmed that the rib-type membrane according to this comparative example could not be used as a membrane for the liquefied natural gas storage tank.

Example:

Hereinafter, an embodiment according to the present invention will be described.

This embodiment is also a method attempted by the applicant of the present invention to fabricate a ribbed membrane.

(1) Preparation

Prepare a flat membrane to be molded. This manufacturing process is the same as the comparative example.

(2) formation of large wrinkles

It is a step of forming a large wrinkle portion 100 on the prepared flat membrane.

At this time, only the upper rounding part R1 and the bottom rounding part R3 of the large wrinkle part 100 are molded, and the side rounding part R2 is not molded.

The large wrinkle part forming step is also the same as the comparative example.

(3) small wrinkles forming step

First, the small wrinkles 200 are formed on the flat membrane in which the large wrinkles 100 are formed.

At this time, the whole of the small wrinkles 200, that is, the upper rounding portion (R1), the side rounding portion (R2), the bottom rounding portion (R3) is formed.

Meanwhile, at the same time, the small wrinkle part 200 is molded, and the upper rounding part R1 of the large wrinkle part 100 is secondarily molded, and the cross part 300 is also molded.

That is, at this stage, the part different from the comparative example in this embodiment is that the rib part 110 of the large wrinkle part 100 is not molded.

(4) finishing stage

Finally, the molding of the small wrinkle part 200 and the large wrinkle part 100 is finally corrected on the flat membrane formed through the small wrinkle part.

At this time, the final rounding of the small wrinkle portion 200 and the large wrinkle portion 100 is molded together with the side rounding portion R2 and the rib portion 110 of the large wrinkle portion 100.

That is, at this stage, the part different from the comparative example in this embodiment is that the rib part 100 and the side rounding part R2 of the large wrinkle part 100 are first molded and molded together.

Table below shows the molding state of the large wrinkle portion and the small wrinkle portion produced by the present embodiment step by step, the results of the actual measurement for the sample produced by the applicant.

The sign of the main part was prepared based on FIG. 5, R1, R2 and R3 described the radius of each round, and E and H described the length of the straight line. The unit is mm. The part marked with "x" is the part in which shaping | molding operation is not performed.

division Main part Immediately after the formation of large wrinkles Immediately after the small wrinkle formation step After deadline Large wrinkle shape R1 (r) 9.6701 10.1831 10.3018 R2 (r) x x 69.940 R3 (r) 7.1922 7.3529 6.9084 E 39.3498 39.1696 38.7749 H 55.1195 55.7658 54.9820 Small wrinkle shape R1 (r) x 8.9103 8.9038 R2 (r) x 38.7966 38.9173 R3 (r) x 6.8954 6.9123 E x 25.8436 26.0747 H x 36.0910 36.0981

9A to 9C are photographs of the large wrinkle part 100 manufactured according to the present embodiment.

9A to 9C, the straight part of the upper rounding part R1 on the upper part of the rib part 110 maintains a smooth straight line, and the deformation of the upper rounding part R1 due to the rib part 110 occurs. It can be confirmed that the rib-type membrane manufactured by the present embodiment can be applied to the membrane for the LNG tank.

10A and 10B are photographs of molds used for forming ribs in a finishing step in order to carry out this embodiment, FIG. 10A is a photograph of a lower mold, and FIG. 10B is a plan photograph (left) of an upper mold; The bottom photograph (right) is shown.

11A to 11C are photographs for showing a working process of the present embodiment, and FIG. 11A is a photograph immediately after a large wrinkle portion is formed in a large wrinkle portion forming step, and FIG. 11B is immediately after a small wrinkle portion is formed in a small wrinkle portion forming step. 11c is a photograph immediately after the final calibration is completed in the finishing step.

Each of the above steps may be completed in one mold for the entire membrane sheet, but in practice, as shown in the above photographs, several operations are performed per sheet of membrane sheet.

For example, in the case of the membrane sheet having five major wrinkles, the forming operation of the flat membrane sheet in the major wrinkle forming step is performed five times. That is, after preparing a mold capable of forming only one large wrinkle portion, five mold operations are performed while advancing the flat membrane by the pitch of the large wrinkle portion. This work method is applied by the same principle in the small wrinkle forming step and finishing step.

However, this repetitive operation is basically only for one molding step, and no two molding operations are performed on the same portion of the plate membrane in one step.

As such, each step is clearly distinct from one another in operation.

As described above, the rib-type membrane according to the present embodiment may be manufactured in a form capable of minimizing stress generation even though the rib part 110 is formed, and thus, may be used in a membrane for a large LNG tank. It became.

The above embodiments are merely preferred embodiments of the present invention, and the technical spirit of the present invention may be variously modified or adjusted by those skilled in the art. Such modifications and adjustments fall within the scope of the present invention if they use the technical idea of the present invention.

According to the present invention, a method for fabricating a new ribbed membrane that can be applied to a liquefied natural gas storage tank that has been enlarged (about 250 km ³ or more) is provided.

Claims (1)

The cross-sectional shape is divided into an upper rounding portion, side rounding portions of both lower portions of the upper rounding portion, and a bottom rounding portion of the lower portion of the side rounding portion, and a plurality of ribs formed in a concave round shape along the longitudinal direction of the side rounding portion. A plurality of large wrinkle parts formed at predetermined intervals are formed in parallel; The cross-sectional shape is divided into an upper rounding portion, side rounding portions of both lower portions of the upper rounding portion, and a bottom rounding portion of the lower portion of the side rounding portion, and a small wrinkle portion having a size smaller than the large wrinkle portion is orthogonal to the large wrinkle portion. While being formed in plural in parallel; In the manufacturing method of the rib-type membrane for liquefied natural gas storage tank to form an intersection when the major wrinkle portion and the small wrinkle portion intersect: A preparation step of preparing a plate membrane to be molded; Forming a large wrinkle portion on the prepared flat membrane, but forming only the upper and lower round portions of the large wrinkle portion and not forming the side round portion; The small wrinkles are formed on the flat membrane formed through the formation of the large wrinkles, and the upper rounding portion, the side rounding portion, and the bottom rounding portion are formed in the whole small wrinkle portion, and at the same time, the upper rounding portion of the large wrinkle portion is secondary molded. And forming a small wrinkle portion to form an intersection between the large wrinkle portion and the small wrinkle portion; The side rounding portion and the rib portion of the large wrinkle portion are first formed on the flat membrane formed through the small wrinkle portion forming step, and at the same time, the small wrinkle portion and the large wrinkle portion are finally corrected to form the small wrinkle portion and the large wrinkle portion. Finishing steps to complete; Rib-type membrane manufacturing method for a liquefied natural gas storage tank comprising a.

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