KR20180013083A - Liquefied gas storage tank - Google Patents

Abstract

The present invention relates to a liquefied gas storage tank to improve insulating/cooling performance of liquefied gas. The liquefied gas storage tank according to an embodiment of the present invention comprises: a primary barrier which surrounds a space for accommodating liquefied gas; a primary insulating panel which surrounds the primary barrier, and insulates the space from the outside; a secondary barrier which surrounds the primary barrier; a secondary insulating panel which surrounds the secondary barrier, and insulates the space from the outside; a cooling gas pipe which includes at least one of a first cooling pipe inserted to a first corrugated portion formed on the primary barrier and a second cooling pipe inserted to a second corrugated portion formed on the secondary barrier, and provides a movement passage of cooling gas for cooling liquefied gas; and a cooling unit which injects the cooling gas to the cooling gas pipe, cools the cooling gas discharged from the cooling gas pipe, and injects the cooling gas to the cooling gas pipe. According to the embodiment of the present invention, it is possible to improve insulating/cooling performance of the liquefied gas storage tank.

Description

[0001] LIQUEFIED GAS STORAGE TANK [0002]

The present invention relates to a liquefied gas storage tank, and more particularly to a liquefied gas storage tank capable of improving liquefied gas insulation / cooling performance.

Liquefied natural gas (LNG) is a liquid state material in which natural gas containing methane as a main component is cooled to -163 ° C or lower and its volume is reduced to 1/600. The LNG storage tank for storing LNG is formed in a double-sealed structure including a primary barrier, an upper insulation panel, a secondary barrier, and a lower insulation panel in order to secure insulation performance of the LNG. The primary barrier contacts the LNG to seal the LNG first. The secondary barrier functions to seal the leaked LNG to prevent the LNG from touching the inner hull when the LNG leaks from the primary barrier. The upper insulation panel and the lower insulation panel perform an insulation function between the primary barrier and the secondary barrier, and between the secondary barrier and the inner hull, respectively.

Nitrogen gas is being injected between the primary and secondary walls to maintain and purge the pressure between the primary and secondary walls of the LNG cargo hold. The nitrogen gas is injected between the primary barrier and the secondary barrier of the cargo hold at normal temperature generated by the nitrogen generator. Since the nitrogen gas injected into the cargo hold is not only small in the volume of the gas to be injected but also injected at a normal temperature, it hardly affects the heat insulating performance.

The present invention provides a liquefied gas storage tank capable of improving liquefied gas insulation / cooling performance.

The present invention also provides a liquefied gas storage tank capable of improving liquefied gas insulation / cooling performance adaptively to thermal shrinkage / expansion of the primary barrier.

The problems to be solved by the present invention are not limited to the above-mentioned problems. Other technical subjects not mentioned will be apparent to those skilled in the art from the description below.

According to an aspect of the present invention, a liquefied gas storage tank includes a primary barrier surrounding a space for accommodating a liquefied gas; A primary insulation panel surrounding the primary barrier and insulated against the outside; A secondary barrier surrounding the primary barrier; A secondary insulation panel surrounding the secondary barrier and insulated against the outside; At least one of a first cooling pipe inserted in a first corrugation formed in the primary barrier and a second cooling pipe inserted in a second corrugation formed in the secondary barrier, wherein cooling for cooling the liquefied gas A cooling gas pipe providing a passage for gas; And a cooling unit for injecting the cooling gas into the cooling gas pipe, and cooling the cooling gas discharged from the cooling gas pipe and injecting the cooling gas into the cooling gas pipe.

The cooling gas may include nitrogen gas.

Wherein the cooling section comprises: a nitrogen gas generator for generating the nitrogen gas; A cooler for cooling the nitrogen gas discharged from the cooling gas pipe; A compressor for compressing the nitrogen gas cooled by the cooler; And an inflator for inflating the nitrogen gas cooled by the cooler to inject nitrogen gas having a temperature of -170 DEG C or lower into the cooling gas pipe.

The cooling gas pipe may be formed of a shrinkable and expandable pipe on at least one region side of a crossing region of a plurality of first corrugations formed on the primary barrier and a crossing region of a plurality of second corrugations formed on the secondary barrier.

According to an embodiment of the present invention, a liquefied gas storage tank capable of improving liquefied gas insulation / cooling performance is provided.

According to an embodiment of the present invention, a liquefied gas storage tank capable of improving liquefied gas insulation / cooling performance adaptively to thermal contraction / expansion of the primary barrier is provided.

The effects of the present invention are not limited to the effects described above. Unless stated, the effects will be apparent to those skilled in the art from the description and the accompanying drawings.

1 is a sectional view of a liquefied gas storage tank 10 according to an embodiment of the present invention.
2 is an exploded perspective view of the liquefied gas storage tank shown in Fig.
3 is a cross-sectional view of a liquefied gas storage tank 10 according to another embodiment of the present invention.
Fig. 4 is a perspective view showing a part of the liquefied gas storage tank shown in Fig. 3; Fig.

Other advantages and features of the present invention and methods for accomplishing the same will be apparent from the following detailed description of embodiments thereof taken in conjunction with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, and the present invention is only defined by the scope of the claims. Although not defined, all terms (including technical or scientific terms) used herein have the same meaning as commonly accepted by the generic art in the prior art to which this invention belongs. A general description of known configurations may be omitted so as not to obscure the gist of the present invention. In the drawings of the present invention, the same reference numerals are used as many as possible for the same or corresponding configurations. To facilitate understanding of the present invention, some configurations in the figures may be shown somewhat exaggerated or reduced.

The terminology used in this application is used only to describe a specific embodiment and is not intended to limit the invention. The singular expressions include plural expressions unless the context clearly dictates otherwise. In the present application, the terms "comprises", "having", or "having" are intended to specify the presence of stated features, integers, steps, operations, components, Steps, operations, elements, parts, or combinations thereof, whether or not explicitly described or implied by the accompanying claims.

The liquefied gas storage tank according to an embodiment of the present invention may include a first cooling pipe inserted in a first corrugation formed on a primary wall and / or a cooling pipe comprising a second cooling pipe inserted in a second corrugation formed on a secondary wall A gas pipe; And a cooling unit for cooling the cooling gas (supercooled nitrogen gas) discharged from the cooling gas pipe and injecting the cooling gas into the cooling gas pipe. According to the embodiment of the present invention, it is possible to improve the heat insulation / cooling performance of the LNG storage tank by injecting and circulating the cooling gas into the LNG storage tank.

In the embodiment of the present invention, the first cooling pipe and the second cooling pipe each have a knot of the first wrinkle portion of the primary barrier and a knot side of the second wrinkle portion of the secondary barrier are contracted and expanded It can be made of possible piping. According to the embodiment of the present invention, the cooling gas is injected / circulated through the first and second cooling pipes capable of expanding and contracting to improve the liquefied gas insulation / cooling performance adaptively to the thermal contraction / expansion of the primary barrier have.

The liquefied gas storage tank according to the embodiment of the present invention can be used to store liquefied gas such as liquefied natural gas (LNG), liquefied petroleum gas (LPG), and the like. Hereinafter, a liquefied gas storage tank according to an embodiment of the present invention will be described by taking a liquefied natural gas storage tank as an example. It should be noted, however, that the liquefied gas storage tank of the present invention may be applied to store liquefied gas such as liquefied petroleum gas in addition to liquefied natural gas.

1 is a cross-sectional view of a liquefied natural gas storage tank 10 according to an embodiment of the present invention. 2 is an exploded perspective view of the liquefied natural gas storage tank shown in Fig. 1 and 2, the LNG storage tank 10 includes a primary barrier 11, a primary insulation panel 12, a secondary barrier 13 ) And the secondary insulation panel 14 are sequentially stacked in this order.

The primary barrier 11 is formed to surround the space for accommodating the LNG to seal the LNG. The primary barrier 11 may be provided in a membrane structure formed of a metal resistant to low-temperature brittleness such as aluminum alloy, Invar, nickel steel, and stainless steel sheet. The primary barrier 11 may have a first corrugation 11a to accommodate the expansion and contraction of the LNG storage tank as the temperature changes. The primary barrier 11 may be installed on the primary insulation panel 12 by a method of welding with an anchor strip (not shown) provided on the upper surface of the primary insulation panel 12. [ The anchor strip can be fixed to the upper surface of the primary heat insulating panel 12 by a fixing member such as a rivet.

The primary insulation panel 12 surrounds the primary barrier 11 and insulates the liquefied natural gas against the outside. The primary insulating panel 12 may be provided as an insulating board positioned between the primary barrier 11 and the secondary barrier 13. [ The primary insulation panel 12 may be composed of an upper insulation member 121 provided on the secondary barrier 13 and an upper protection plate 122 attached to the upper insulation member 121. [

The secondary barrier 13 surrounds the primary insulation panel 12 and blocks the LNG from leaking to the inner hull 15 when the LNG leaks through the primary barrier 11. In one embodiment, the secondary barrier 13 may be provided in a triplex formed of a metal composite laminate with metal foil on both sides of the glass-fiber composite . The secondary barrier 13 is fixed to the secondary insulation panel 14 by bolts or the like or welded to the anchor strip provided on the upper surface of the secondary insulation panel 14 or by welding And can be fixed on the heat insulating panel 14.

The secondary insulation panel 14 surrounds the secondary barrier 13 and has a heat insulation function. The secondary insulation panel 14 may be provided as a heat insulating board positioned between the secondary barrier 13 and the inner hull 15. In one embodiment, the secondary insulation panel 14 includes a lower protection plate 142 fixed to the inner hull 15 by a fixing member (not shown), and a lower insulation member 141 attached to the lower protection plate 142 Lt; / RTI > In one embodiment, the secondary insulation panel 14 may be installed in the inner hull 15 via a mastic 15a.

The upper heat insulating member 121 and the lower heat insulating member 141 are formed of a material having excellent heat insulating property such as a polyurethane foam so as to provide heat insulation between the inner hull 15 and the LNG. The upper protective plate 122 and the lower protective plate 142 may be formed of plywood to impart mechanical rigidity to the primary thermal insulation panel 12 and the secondary thermal insulation panel 14, respectively.

The secondary insulation panels 14 are made of a pre-designed area and are arranged on the inner hull 15 at a distance from each other. The spacing of the secondary insulating panels 14 can be set within a range that absorbs the shrinkage and expansion of the heat insulating board. The primary insulation panels 12 are disposed on the secondary barrier 13 at a distance from each other. The spacing of the primary insulating panels 12 may be set within a range that absorbs shrinkage and expansion of the heat insulating board. The gap between the primary insulating panels 12 and / or between the secondary insulating panels 14 may be filled with a heat insulating material having elasticity such as glass wool.

The first corrugation 11a of the primary wall 11 is inserted with a cooling gas pipe constituted by a first cooling pipe 16 which provides a passage for the cooling gas for cooling the LNG. The cooling gas may include nitrogen gas that is supercooled by the cooling section 17. [ The cooling unit 17 injects the cooling gas into the first cooling pipe 16 and cools the cooling gas discharged from the first cooling pipe 16 and injects the cooling gas into the first cooling pipe 16 again.

The cooling section 17 includes a nitrogen gas generator 171 for generating nitrogen gas G1 at room temperature and a cooler 172 for cooling the nitrogen gas discharged from the first cooling pipe 16, A compressor 173 for compressing the nitrogen gas at room temperature generated by the nitrogen gas generator 171 and the nitrogen gas cooled by the cooler 172 and the nitrogen gas cooled by the cooler 172 are expanded And an expander 174 for injecting nitrogen gas G2 having a temperature of -170 DEG C or lower into the first cooling pipe 16. [

Since the temperature of the primary wall 11 is -163 占 폚 even if the temperature is increased while the subcooled nitrogen gas G2 passes through the first cooling pipe 16 under the primary wall 11, The temperature of the N2 gas (G3) at the time of discharging the N2 gas (G3) may be maintained at -170 DEG C or lower. According to the present embodiment, the N2 gas (G1) at room temperature is cooled to -180 DEG C or lower by the cooling section 17, the N2 gas whose temperature has risen while passing through the first cooling pipe 16 is cooled, And then passed through the expander 174 to inject a supercooled nitrogen gas G2 having a temperature lower than -180 DEG C into the first cooling pipe 16 below the primary barrier 11. This is then circulated to perform LNG insulation and cooling Effect can be obtained.

That is, according to the embodiment of the present invention, by keeping the temperature of N ₂ gas injected below the primary barrier 11 between -170 ° C. and -180 ° C., external heat is prevented from being injected into the LNG through the heat insulating layer , The BOR (Boil Off Ratio) of LNG can be lowered. Also, since this embodiment deals with only the N ₂ gas phase, the LNG cooling / insulation effect can be obtained without using a process used to treat two-phase fluids such as a process equipment for re-liquefying gas and a separator, 0.0 > 0.06% / day, < / RTI >

In one embodiment, the first cooling pipe 16 includes a first pipe 16a inserted into the inner space of the first corrugation 11a, and a second pipe 16b connected to the first pipe 16a, (16b). The second piping 16b is provided with an intersecting region of a plurality of first wrinkles 11a formed on the primary wall 11 so as to correspond to the contraction / expansion of the primary wall 11, that is, (Knot) 11b which is an intersection of the wrinkles in the transverse direction. According to the present embodiment, the second pipe 16b which expands and contracts in accordance with the heat shrinkage / expansion of the primary wall 11 is used for the LNG insulation by the supercooling nitrogen gas adaptively to the heat shrinkage / expansion of the primary wall 11 / Cooling performance can be obtained.

3 is a cross-sectional view of a liquefied gas storage tank according to another embodiment of the present invention. Fig. 4 is a perspective view showing a part of the liquefied gas storage tank shown in Fig. 3; Fig. In the description of the embodiments of FIGS. 3 and 4, redundant explanations of the same or corresponding components as those of the previously described embodiments may be omitted. 3 and 4 show that the second barrier 13 has the second corrugation 13a and the cooling gas tube is the second cooling tube 19 inserted in the second corrugation 13a There is a difference from the above-described embodiment.

In one embodiment, the primary insulation panel 12 includes a first lower stiffener 12c mounted on the secondary barrier 13 by a panel coupling 18 such as a stud bolt / nut, A first heat insulating member 12a coupled to the first heat insulating member 12c and a first upper reinforcing plate 12b coupled to the first heat insulating member 12a.

In one embodiment, the secondary insulation panel 14 includes a second lower stiffener 14c fixed to the inner hull 15 by a fixing member (not shown), a second lower stiffener 14c fixed to the second lower stiffener 14c And a second upper reinforcing plate 14a coupled to the car thermal insulating member 14b and the secondary thermal insulating member 14b.

The primary heat insulating member 12a and the secondary heat insulating member 14a are formed of a material having excellent heat insulating property such as a polyurethane foam to provide heat insulation between the inner hull 15 and the LNG. The first upper reinforcing plate 12b, the first lower reinforcing plate 12c, the second upper reinforcing plate 14a and the second lower reinforcing plate 14c may be formed of plywood, Thereby imparting mechanical rigidity to the heat insulating panel 12 and the secondary thermal insulating panel 14. [

The secondary barrier 13 may have a second corrugation 13a to accommodate the expansion and contraction of the LNG storage tank as the temperature changes. The panel coupling portion 18 may include a fixing strip to be coupled to the second upper reinforcing plate 14a by a rivet or the like, a fixing bolt protruding from the fixing strip, and a nut coupled to the fixing bolt. The fixing bolt may extend through the secondary barrier 13 and the first lower reinforcing plate 12c toward the through hole 18a formed through the primary heat insulating member 12a. After the primary heat insulating panel 12 and the secondary insulating panel 14 are combined, the heat insulating material 18b can be filled in the through hole 18a of the primary heat insulating member 12a.

A cooling gas pipe constituted by a second cooling pipe 19 for providing a passage for cooling the insulating gas (for example, nitrogen gas under supercooling) is inserted into the second corrugation 13a of the secondary barrier 13 . The cooling section 17 can be provided to inject the cooling gas into the second cooling pipe 19 and cool the cooling gas discharged from the second cooling pipe 19 to inject it again into the second cooling pipe 19 .

The second cooling pipe 19 is composed of a first pipe 19a inserted into the inner space of the second corrugation 13a and a second pipe 19b expandable and contractible to the first pipe 19a, . The second pipe 19b is provided with an intersecting region of a plurality of second corrugations 13a formed on the secondary barrier 13, that is, a vertical corrugation portion and a second corrugated portion 13b, so as to correspond to contraction / expansion of the secondary barrier 13 And can be formed on the knot which is an intersection area of the wrinkles in the transverse direction.

The first cooling pipe 16 is inserted into the first corrugation 11a of the primary wall 11 and the second cooling pipe 16 is inserted into the second corrugation 13a of the secondary wall 13 The second cooling pipe 19 can be inserted. In this embodiment, the cooling section 17 may be provided to circulate the cooling gas to the first cooling pipe 16 and the second cooling pipe 19, respectively, to heat / cool the LNG cargo hold.

It is to be understood that the above-described embodiments are provided to facilitate understanding of the present invention, and do not limit the scope of the present invention, and it is to be understood that various modifications are possible within the scope of the present invention. It is to be understood that the technical scope of the present invention should be determined by the technical idea of the claims and the technical scope of protection of the present invention is not limited to the literary description of the claims, To the invention of the invention.

10: liquefied natural gas storage tank 11: primary barrier
11a: first wrinkle portion 11b:
12: primary insulation panel 12a: primary insulation member
12b: first upper reinforcing plate 12c: first lower reinforcing plate
121: upper heat insulating member 122: upper shield plate
13: secondary barrier 13a: second wrinkle portion
14: secondary insulation panel 14a: second upper reinforcing plate
14b: secondary thermal insulating member 14c: second lower reinforcing plate
141: lower heat insulating member 142:
15: Inner hull 15a: Mastic
16: first cooling pipe 16a: first pipe
16b: second piping 17: cooling section
171: nitrogen gas generator 172: cooler
173: compressor 174: inflator
18: panel coupling portion 18a: through hole
18b: Insulating material 19: Second cooling pipe
19a: first pipe 19b: second pipe

Claims (4)

A primary barrier surrounding a space for receiving the liquefied gas;
A primary insulation panel surrounding the primary barrier and insulated against the outside;
A secondary barrier surrounding the primary barrier;
A secondary insulation panel surrounding the secondary barrier and insulated against the outside;
At least one of a first cooling pipe inserted in a first corrugation formed in the primary barrier and a second cooling pipe inserted in a second corrugation formed in the secondary barrier, wherein cooling for cooling the liquefied gas A cooling gas pipe providing a passage for gas; And
And a cooling unit for injecting the cooling gas into the cooling gas pipe, and cooling the cooling gas discharged from the cooling gas pipe to inject the cooling gas into the cooling gas pipe. The method according to claim 1,
Wherein the cooling gas comprises nitrogen gas. 3. The method of claim 2,
The cooling unit comprises:
A nitrogen gas generator for generating the nitrogen gas;
A cooler for cooling the nitrogen gas discharged from the cooling gas pipe;
A compressor for compressing the nitrogen gas cooled by the cooler; And
And an inflator for inflating the nitrogen gas cooled by the cooler to inject nitrogen gas having a temperature of -170 DEG C or lower into the cooling gas pipe. The method of claim 3,
Wherein the cooling gas pipe has a liquefied gas storing portion in which at least one region side of a crossing region of a plurality of first wrinkles formed in the primary barrier and a crossing region of a plurality of second wrinkles formed in the secondary barrier is a shrinkable and expandable pipe, Tank.

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