KR20140023687A - Cryogenic liquid storage tank with composite material reinforcement, composite material reinforcement and fabrication method of composite material reinforcement - Google Patents

Abstract

The present invention relates to an ultra low temperature liquid storage tank and more specifically, to a composite material reinforcement, a manufacturing method thereof, and an ultra low temperature liquid storage tank in order to improve the internal pressure performance of a first protective wall which is directly in contact with ultra low temperature liquid. The ultra low temperature liquid storage tank including the composite material reinforcement by the present invention includes: a tank inner wall; an insulating panel which is combined with the tank inner wall in order to prevent a heat transfer between the tank inner wall and a storage space; and the first protective wall which is combined with the insulating panel in order to seal the storage space, wherein the first protective wall has a crease part formed in a bulgy form in the direction of the storage space. The present invention more includes the composite material reinforcement which is arranged in a space between the crease part and the insulating panel in order to support the crease part. The composite material reinforcement includes a reinforcement fiber and a matrix resin and is a hollow body which has a curved surface which corresponds to the crease part and a plane which corresponds to the insulating panel. An acute angle which the reinforcement fiber of the composite material reinforcement forms with the length direction of the composite material reinforcement is 40° or more. The yield strain rate of the composite material reinforcement is not less than the yield strain rate of the crease part of the first protective wall. The buckling load of the composite material reinforcement is not less than the buckling load of the crease part of the first protective wall. The ultra low temperature liquid storage tank which has the composite material reinforcement according to the present invention has a high pressure-resistant performance about compressive force by a sloshing and a cavitation phenomenon.

Description

TECHNICAL FIELD [0001] The present invention relates to a cryogenic liquid storage tank, a composite material reinforcing material, and a composite material reinforcing material provided with the composite material reinforcing material. BACKGROUND ART < RTI ID = 0.0 >

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cryogenic liquid storage tank, and more particularly, to a composite material reinforcement for improving the pressure resistance of a primary barrier in direct contact with a cryogenic liquid, a method of manufacturing the same, and a cryogenic liquid storage tank having the same.

Cryogenic liquids such as Liquefied Natural Gas (LNG), Liquid Argon, Liquid Nitrogen, and Liquid Oxygen are used in storage tanks with an insulating structure to minimize evaporative losses. Stored or transported.

An example of a cryogenic liquid storage tank is a cargo containment system of an LNG carrier. The LNG carrier cargo holds are designed to store and transport cryogenic LNG at -163 ° C. It has a spherical type and a membrane type. It has a membrane type tank that is larger in capacity and easier to manufacture than a spherical type tank. Is preferred.

A gas transport system and a technigaz system developed by the company Gas Transport Et Technigaz (GTT, France) in France are used for the cooling system of the membrane type LNG carrier have. The Gaz Transport system is called GTT No96, and the Technigaz system is called the GTT Mark-III system.

Invar (36% nickel steel), which has a very low coefficient of thermal expansion, is used as the material of the first and second barriers of the Gaz transport system. A heat insulating box filled with pearlite is used between the first and second walls.

A stainless steel sheet having a corrugated shape is used as a first barrier of the Technigaz system to absorb shrinkage and expansion due to thermal deformation and a second barrier is made of aluminum foil Triplex, in which glass fiber composite is bonded on both sides, is used. And a polyurethane foam serving as a heat insulating material is mounted between the first and second barrier walls.

Although the gas evacuation rate (BOR) of the gas transport system and the technigaz system are known to be similar, the cost of stainless steel sheets and triplexes is relatively low compared to the in-bar membrane, the construction is simple and the insulation effect of the polyurethane foam The Technicon system is preferred.

The primary barrier of the Gaz Transport System and the Technigaz System is formed by welding in-bar steel or stainless steel sheet to each other, and the welded portion is subjected to stress due to hydrothermal reaction occurring when the primary barriers contact the cryogenic liquefied natural gas It can be broken. Because of this problem, the primary barriers have a convex corrugation structure to have low in-plane stiffness. The crease reduces the thermal stress at the welded area by deforming a certain amount when heat shrinkage occurs.

United States Patent No. 7,540,395 Korean Patent No. 10-1019192

As described above, a wrinkle portion for reducing thermal stress is formed in the primary barrier of the Gaz Transport System and the Technique System. However, these wrinkles are vulnerable to breakage.

Waves may be generated on the surface of the stored LNG due to movement such as rolling or pitching of the ship during the operation of the ship carrying the LNG. Such a wave is called sloshing, and this slushing applies a large compressive force to the primary walls. If the compressive force due to slushing exceeds the yield strength (Yield Strength) or buckling strength of the primary barriers, the wrinkles most susceptible to deformation may be permanently deformed and the safety of the primary barriers may deteriorate.

In addition, the corrugation has a problem in that cavitation occurs due to a pressure change in the LNG flowing at a temperature close to the vaporization point, and the stress due to cavitation can permanently deform the corrugation of the primary barrier .

It is an object of the present invention to provide a cryogenic liquid storage tank in which a composite stiffener is disposed in a space between a corrugation of the primary barrier and a thermal barrier joined to the primary barrier .

Another object of the present invention is to provide a composite material reinforcement disposed in a space between a corrugated structure of a primary barrier and a heat insulating layer bonded to a primary barrier.

Still another object of the present invention is to provide a method of manufacturing the composite reinforcement.

In order to achieve the above object, a cryogenic liquid storage tank having a composite material reinforcement according to the present invention comprises a heat insulating panel coupled to an inner wall of a tank, a heat insulating panel coupled to an inner wall of the tank to prevent heat transfer between the inner wall of the tank and the storage space, And a primary barrier coupled to the insulating panel to seal the primary barrier, the primary barrier having a corrugated portion bulging in the storage space direction.

The composite material reinforcing member may include a reinforcing fiber and a matrix resin. The composite material reinforcing material may be disposed in a space between the corrugation and the heat insulating panel to support the corrugation, And a plane corresponding to the heat insulating panel, wherein an acute angle formed by the reinforcing fibers of the composite material reinforcement with the longitudinal direction of the composite material reinforcement is 40 ° or more, and a yield strain of the composite material reinforcement is And the buckling load of the composite material reinforcing material is not less than a buckling load of the first barrier rib portion.

Preferably, the composite material reinforcement of the cryogenic liquid storage tank has a heat transfer coefficient smaller than the heat transfer coefficient of the primary barrier rib.

In order to achieve the above object, a composite material reinforcing material according to the present invention is a hollow cylinder including a reinforcing fiber and a matrix resin, and has a curved surface corresponding to the corrugated portion and a plane corresponding to the heat insulating panel, Wherein a yield angle of the reinforcing fiber of the composite material reinforcing member with respect to a longitudinal direction of the composite material reinforcing member is 40 ° or more and a yield strain of the composite material reinforcing member is greater than a yield strain of the first barrier rib portion, And is not less than the buckling load of the car barrier wrinkle portion.

According to another aspect of the present invention, there is provided a method of manufacturing a composite reinforcing material, the method comprising: winding the reinforcing fiber on the mandrel such that an acute angle formed by the reinforcing fiber and the rotating shaft of the mandrel is 40 ° or more; Comprising the steps of: impregnating the reinforcing fibers with a matrix resin before or after winding the mandrel on the mandrel; placing and pressing the mandrel and the preform within the mold; .

The cryogenic liquid storage tank having the composite material reinforcement according to the present invention has a high pressure resistance performance against compressive force by slushing and cavitation.

1 is a schematic cross-sectional view of one embodiment of a cryogenic liquid storage tank having a composite stiffener in accordance with the present invention.
2 is a cross-sectional view showing the corrugation of the primary barrier shown in Fig.
Figure 3 is a perspective view of the composite stiffener shown in Figure 1;
4 is a graph showing the withstand voltage performance of the composite reinforcing material with respect to the angle between the longitudinal direction of the reinforcing fiber and the composite stiffener.
5 and 6 are views for explaining an embodiment of a method of manufacturing a composite reinforcement according to the present invention.
FIGS. 7 and 8 are views for explaining another embodiment of the method for manufacturing a composite material reinforcement according to the present invention.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

The following embodiments are provided by way of example so that those skilled in the art can fully understand the spirit of the present invention. Therefore, the present invention is not limited to the embodiments described below, but may be embodied in other forms. And in the drawings, the width, length, thickness, etc. of the components may be exaggerated for convenience. Like numbers refer to like elements throughout.

1 is a schematic cross-sectional view of one embodiment of a cryogenic liquid storage tank having a composite stiffener in accordance with the present invention.

Referring to FIG. 1, an embodiment of the cryogenic liquid storage tank according to the present invention includes a tank inner wall 110 having a storage space for storing cryogenic liquid therein, a heat transfer between the tank inner wall 110 and the storage space, And a heat insulating structure 120 coupled to the tank inner wall 110 to prevent the heat transfer. The heat insulating structure 120 is composed of heat insulating panels 121, 122 and 123, a primary barrier 124 and a secondary barrier 125 arranged in a multilayered manner.

The heat insulating panels 121, 122 and 123 are divided into an outer heat insulating panel 121 coupled to the tank inner wall 110 and an inner heat insulating panel 122 and a bridge thermal insulating panel 123 covering the outer heat insulating panel 121. [ . The bridge-insulating panel 123 is disposed between the inner insulating panels 122 to cover the gap between the two outer insulating panels 121.

The heat insulating panels 121, 122 and 123 are covered with a protection plate 129 made of a plywood or a composite material or the like on one side of a heat insulating material 126, 127 or 128 such as a polyurethane foam. ) 130 and 131 are combined with each other. The outer heat insulating panel 121 is fixed to the tank inner wall 110 by an adhesive 115 or a stud bolt (not shown), and the inner heat insulating panel 122 and the bridge heat insulating panel 123 are bonded to each other And is fixed to the outer heat insulating panel 121 by a method.

The primary barrier 124 is for sealing the storage space so that the cryogenic liquid stored in the storage space is not leaked. An anchor strip (not shown) installed on the inner heat insulating panel 122 or the bridge heat insulating panel 123, And a plurality of barrier sheets 132 made of a metal and welded and fixed. The barrier sheet 132 constituting the primary barrier 124 may be made of various metal materials such as stainless steel or aluminum that does not cause deterioration of physical properties due to brittleness at a cryogenic temperature.

The primary barrier 124 has a plurality of corrugations 133 for suppressing the generation of thermal stress due to heat shrinkage. The corrugated portion 133 is formed to be convex in the storage space direction. The corrugated portion 133 is intended to prevent the welded portion from being damaged by the stress due to the hot water generated when the primary barrier contacts the liquefied natural gas at a very low temperature. However, the wrinkle portion 133 has a problem that is vulnerable to breakage when sloshing or pupil phenomenon occurs. Therefore, a composite material reinforcing member 10 for improving the withstand pressure performance is disposed between the corrugated portion 133 and the inner heat insulating panel 122 and the bridge heat insulating panel 123.

  The secondary barrier 125 covers the outer heat insulating panel 121 to seal the cryogenic liquid secondarily when the primary barrier 124 is broken. The secondary barrier 125 is composed of a plurality of barrier sheets 134 covering the gap between the upper surface of the outer heat insulating panel 121 and the outer heat insulating panels 121. The barrier sheet 134 is made of a metal or a mixed material of a metal and a composite material and adhered to each other by an adhesive 135 such as a polymer adhesive or a film type adhesive.

2 is a cross-sectional view showing the corrugation of the primary barrier shown in Fig.

1 and 2, a composite material stiffener for supporting the corrugation 133 is provided between the corrugated portion 133 of the primary barrier 124 and the inner heat insulating panel 122 and the bridge thermal insulation panel 123 10 are disposed. The composite stiffener 10 prevents the corrugations 133 of the primary barrier 124 from being permanently deformed by stresses due to slushing or cavitation.

Figure 3 is a perspective view of the composite stiffener shown in Figure 1;

2 and 3, the composite material reinforcement 10 is obtained by impregnating the reinforcing fibers 11 with the matrix resin 12 and curing the same. As the reinforcing fiber 11, it is preferable to use glass fiber, aramid fiber, nylon fiber, polyethylene fiber, polyester fiber or the like having a low heat transfer coefficient. When such fibers are used as the reinforcing fibers 11, the thermal conductivity of the composite reinforcing material 10 can be lowered, and the composite reinforcing material 10 can also serve as a heat insulating material. As the matrix resin 12, a thermosetting resin such as a phenolic resin, an epoxy resin, or a polyester resin can be used.

The composite stiffener 10 includes a curved surface 14 corresponding to the inner surface shape of the corrugations 133 of the primary barrier 124 and a plane 15 contacting the inner and outer heat insulating panels 122 and 123 (13). The composite material reinforcing material 10 has a change in mechanical properties such as strength and stiffness depending on the arrangement of the reinforcing fibers. It is preferable that the reinforcing fibers 11 of the composite material reinforcing member 10 are wound so that an acute angle formed with the longitudinal direction of the composite material reinforcing member 10 is 40 degrees or more. As shown in FIG. 4, when the angle between the reinforcing fibers 11 and the longitudinal direction is less than 40 degrees, the pressure resistance performance of the composite material reinforcing member 10 is deteriorated.

The yield strain of the composite material stiffener 10 is not less than the yield strain of the wrinkles 133 of the primary barrier 124 and the buckling load of the composite material stiffener is less than the yield strain of the wrinkles 133 of the primary barrier 124, Load or more.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of a method of manufacturing a composite material reinforcing member will be described with reference to the accompanying drawings.

5 and 6 are views for explaining an embodiment of a method of manufacturing a composite reinforcement according to the present invention.

First, referring to FIG. 5, a step of manufacturing a preform by a filament winding method will be described.

The rotating mandrels 1 are wound with pre-impregnated reinforcing fibers 21 previously impregnated with a matrix resin. The reinforcing fibers 21 can be automatically wound by using a winding machine having a rotating mandrel 1 and a carriage that linearly moves in the axial direction of the mandrel 1. [

The tensile force applied to the reinforcing fibers 21 when winding the reinforcing fibers 21 and the angle at which the reinforcing fibers 21 are wound determine the pressure resistance performance of the composite material reinforcement. The larger the tensile force, the greater the strength and stiffness of the composite stiffener, and the lower the tensile strength, the greater the flexibility.

As described above, since the composite material stiffener 10 can obtain sufficient pressure resistance performance only when the longitudinal direction of the composite material stiffener 10 and the acute angle formed by the stiffening fibers 11 are 40 degrees or more, The reinforcing fibers 21 should be wound so that the acute angle formed by the shaft and the reinforcing fibers 21 is 40 ° or more.

At this time, a resin tank in which the resin is contained on the path of the reinforcing fiber is disposed in advance without using the reinforcing fiber 21 impregnated with the matrix resin, and the reinforcing fiber is impregnated with the matrix resin immediately before winding on the mandrel, A wet method of impregnating a matrix resin after winding on a mandrel is also possible. However, in order to keep the amount of the matrix resin constant, it is preferable to use a reinforcing fiber impregnated with a matrix resin in advance.

Next, the step of curing the preform will be described with reference to Fig. The composite stiffener 10 according to the present invention must have accurate external dimensions because it directly contacts the corrugations 133 of the primary barrier 124. Therefore, unlike a typical filament winding method, the resin is cured in a precise shape. 6, after the preform 20 is inserted into the cavity of the lower mold 2, the upper mold 3 is covered and the upper mold 3 is pressed to catch the outer shape of the preform 20, Curing is carried out by heating in the state.

At this time, if the preform 20 is rotated in the pressing process, the thickness of the composite material stiffener 10 becomes uneven, so that the mandrel 1 should be prevented from rotating with respect to the molds 2 and 3. To this end, a protrusion 5 is formed on the side surface of the mandrel 1 in a vertical manner and the side mold 4 having the groove 6 corresponding to the protrusion 5 is formed on the side surface of the upper and lower molds 2 and 3 By coupling to the mandrel 1, rotation of the mandrel 1 can be prevented.

7, after the preform 20 is wrapped by the vacuum bag 7, air in the vacuum bag 7 is removed by using a vacuum pump, and the vacuum bag 7 The thickness of the composite reinforcement member can be made uniform by pressurizing the preform 20 supported by the mandrel 1 uniformly.

8, the preform 20 is placed in the cavity of the mold 8, the pressure bag 9 is inserted into the hollow of the preform 20, and then the pressure bag 9 is expanded The preform 20 supported by the mold 22 may be cured while applying pressure. A high temperature gas is injected into the pressure bag 9 and the metal mold 8 is heated.

While the above has been shown and described with respect to preferred embodiments of the present invention, the present invention is not limited to the specific embodiments described above, it is usually in the technical field to which the invention belongs without departing from the spirit of the invention claimed in the claims. Various modifications can be made by those skilled in the art, and these modifications should not be individually understood from the technical spirit or prospect of the present invention.

10: composite stiffener 11: reinforcing fiber
12: matrix resin 13: hollow
100: liquid storage tank 110: tank inner wall
120: heat insulating structure 121: outer heat insulating panel
122: Inner insulation panel 123: Bridge insulation panel
124: primary barrier 125: secondary barrier
132, 134: barrier sheet 133:

Claims (10)

Insulation panel coupled to the tank inner wall to prevent heat transfer between the tank inner wall and the tank inner wall and the storage space and a primary barrier coupled to the insulation panel to seal the storage space, the primary barrier is In the cryogenic liquid storage tank having a pleat formed in the direction of the storage space,
Further comprising a composite material reinforcement disposed in the space between the wrinkles and the insulation panel to support the wrinkles,
The composite reinforcing material includes a reinforcing fiber and a matrix resin, and is a hollow cylinder having a curved surface corresponding to the corrugation portion and a plane corresponding to the heat insulating panel, wherein the reinforcing fiber of the composite reinforcing material is the composite reinforcing material. Acute angle with the longitudinal direction of is 40 ° or more,
The yield strain of the composite reinforcement is greater than or equal to the yield strain of the primary barrier crease, and the buckling load of the composite reinforcement is greater than or equal to the buckling load of the primary barrier crease. . The method of claim 1,
The reinforcing fiber is a cryogenic liquid storage tank having a composite reinforcing material, characterized in that at least one selected from glass fiber, aramid fiber, nylon fiber, polyethylene fiber, polyester fiber. The method of claim 1,
Cryogenic liquid storage tank having a composite reinforcement, characterized in that the heat transfer coefficient of the composite reinforcement is less than the heat transfer coefficient of the primary barrier corrugation. In the composite material reinforcement disposed between the corrugated portion and the insulation panel to support the corrugated portion of the primary barrier for sealing the storage space of the cryogenic liquid storage tank,
It is a hollow cylinder including a reinforcing fiber and a matrix resin, and having a curved surface corresponding to the corrugated portion and a plane corresponding to the heat insulating panel, wherein the reinforcing fiber of the composite reinforcing material is formed in the longitudinal direction of the composite reinforcing material. Acute angle is over 40 °
The yield strain of the composite reinforcement is greater than or equal to the yield strain of the primary barrier crease, and the buckling load of the composite reinforcement is greater than or equal to the buckling load of the primary barrier crease. 5. The method of claim 4,
The reinforcing fiber is a composite material reinforcing material, characterized in that at least one selected from glass fibers, aramid fibers, nylon fibers, polyethylene fibers, polyester fibers. 5. The method of claim 4,
And a heat transfer coefficient is smaller than a heat transfer coefficient of the primary barrier corrugation portion. Winding the reinforcing fiber onto the mandrel and impregnating the reinforcing fiber with the matrix resin before or after winding the reinforcing fiber to the mandrel such that an acute angle formed by the revolving axis of the reinforcing fiber and the mandrel is 40 ° or more. And a preform manufacturing step comprising a,
Arranging and pressing the mandrel and the preform inside the mold;
Method for producing a composite material reinforcement comprising the step of curing the preform. The method of claim 7, wherein
Placing and pressurizing the mandrel and the preform inside the mold comprises preventing the mandrel from rotating relative to the mold. Winding the reinforcing fiber onto the mandrel and impregnating the reinforcing fiber with the matrix resin before or after winding the reinforcing fiber to the mandrel such that an acute angle formed by the revolving axis of the reinforcing fiber and the mandrel is 40 ° or more. And a preform manufacturing step comprising a,
Pressurizing the preform by removing the air in the vacuum bag after wrapping the preform and the mandrel with a vacuum bag;
Method for producing a composite material reinforcement comprising the step of curing the preform. Winding the reinforcing fiber onto the mandrel and impregnating the reinforcing fiber with the matrix resin before or after winding the reinforcing fiber to the mandrel such that an acute angle formed by the revolving axis of the reinforcing fiber and the mandrel is 40 ° or more. And a preform manufacturing step comprising a,
Disposing the preform inside the mold;
Arranging a pressure bag in the hollow of the preform;
Pressurizing the preform supported by the mold by expanding the pressurized bag;
Method for producing a composite material reinforcement comprising the step of curing the preform.

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