KR20200069578A - LNG Storage Tanks including an Emergency Discharging Device - Google Patents

Abstract

Disclosed is a liquefied natural gas storage tank including an emergency discharge device. According to the present invention, the liquefied natural gas storage tank including an insulation barrier comprising at least one sealing wall and at least one insulation wall includes an emergency discharge device forming a drain hole to discharge LNG in the storage tank by forcibly breaking a part of the insulation barrier. The emergency discharge device includes: a pipe inserted and fixed into the insulation barrier and having a hollow inside; at least one internal partition installed inside the pipe to seal the inside of the pipe; and a drilling member installed on one side of the pipe to be reciprocated to break the internal partition. As the internal partition is broken by the drilling member, a flow path for discharging the LNG in the storage tank is formed in the pipe. Therefore, the liquefied natural gas storage tank including the emergency discharge device can rapidly discharge LNG in the storage tank.

Description

LNG Storage Tanks including an Emergency Discharging Device}

The present invention relates to a liquefied natural gas storage tank including an emergency discharge device, and more specifically, by making the drain hole (drain hole) by forcibly damaging the insulating barrier of the intact storage tank in an emergency partly in normal times, It relates to a liquefied natural gas storage tank including an emergency discharge device for quickly discharging the liquefied natural gas stored in the outside.

In general, natural gas is transported in a gaseous state through gas piping on land or offshore, or stored in an LNG carrier in the state of liquefied natural gas (hereinafter referred to as'LNG') and transported to remote consumers.

LNG is obtained by cooling natural gas to about -163°C at a very low temperature, and its volume is reduced to about 1/600 than that of natural gas in a gas state, so it is very suitable for long-distance transportation through the sea. In addition to LNGC (LNG Carrier), LNG ships used for the transportation of LNG include LNG LNG (VL) (Regasification Vessel), which reloads the stored LNG and unloads it into natural gas after arriving at land destinations. In recent years, the demand for floating offshore structures such as LNG Floating, Production, Storage and Offloading (FPSO) or LNG Floating Storage and Regasification Unit (FSRU) is gradually increasing.

Such a ship or floating offshore structure is provided with a storage tank (also called a'cargo') that can store and store LNG liquefied in an ultra-low temperature state. These storage tanks are typically independent type and membrane type. type). Membrane type storage tanks are largely divided into GTT NO 96 type and Mark III type, and independent storage tanks are divided into MOSS type and SPB type.

On the other hand, in the case of membrane type storage tanks, it is not allowed to make pipes through the lower part of the tank in various international regulations and standards (IGF, BS EN 1473, etc.) for safety reasons. Here, the term'penetration' means to communicate with the outside without sealing by a barrier. Therefore, in this specification, even if the inlet is blocked by a valve or the like formed in the lower portion of the storage tank, it is assumed that a pipe structure passing through the lower portion of the tank exists.

Conventionally, in the event of an emergency such as leakage of LNG from a storage tank, in order to extract LNG inside the storage tank to the outside, a pump of a submerged type is placed inside the storage tank, or a deep well type pump having a long shaft Was installed in the upper dome of the storage tank and used in an emergency.

However, in the case of the fuel tank, the capacity of the pump used for fuel supply is too small, and there is a problem that it takes a long time (sometimes hundreds of hours) to empty the contents of the storage tank. However, having a separate large-capacity pump for emergency use is too inefficient in terms of space utilization and cost.

The technical problem to be achieved by the present invention is to create a drain hole by forcibly damaging a part of the insulating barrier of the storage tank in the event of an emergency, and quickly discharge the LNG inside the storage tank to the outside without having a large-capacity pump or the like. It is possible to provide an emergency discharge system for a liquefied natural gas storage tank.

In order to achieve the above object, the present invention in the liquefied natural gas storage tank comprising an insulating barrier consisting of one or more sealing walls and one or more insulating walls, a part of the insulating barrier by forcibly damaging a part of the storage tank inside Including an emergency discharge device for forming a drain hole (drain hole) through which the LNG can be discharged, The emergency discharge device is inserted and fixed to the heat insulating barrier, the hollow pipe inside; At least one internal plate installed inside the pipe to seal the inside of the pipe; And a perforated member installed to reciprocate on one side of the pipe to break the inner plate, and as the inner plate is damaged by the perforated member, LNG inside the storage tank is discharged inside the pipe. It provides a liquefied natural gas storage tank comprising an emergency discharge device, characterized in that the flow path can be formed.

Here, the insulating barrier is provided in a structure in which a secondary insulating wall, a secondary sealing wall, a primary insulating wall, and a primary sealing wall are sequentially stacked from the inner wall of the hull toward the inside of the storage tank. A pipe body which is inserted into the heat insulating barrier so as to reach the level of the primary sealing wall, and the other end extending outward of the storage tank; A first connection plate formed to protrude on the outer circumferential surface of the pipe body and connected to the primary sealing wall by welding on the same plane; And a second connecting plate formed to protrude on the outer circumferential surface of the pipe body, and connected by welding on the same plane as the secondary sealing wall, wherein the inner plate is provided in plural, and the plurality of inner plates are Inside the pipe, they are spaced apart from each other to form a layer, and spaces between the inner plates spaced apart from each other may be filled with glass wool as a heat insulating material.

The plurality of inner plates may include: a first inner plate disposed on the same plane as the primary sealing wall; A second inner plate disposed on the same plane as the second sealing wall; And a third inner plate disposed on the same plane as the bottom surface of the storage tank.

The perforated member, the screw is inserted through the insertion hole formed on one side of the pipe; And a wheel coupled to the other end of the screw to transmit rotational force to the screw, and the screw is able to enter the inside of the pipe by being screwed to the insertion hole.

The screw is positioned to penetrate the center of the inner plate, and one end can be processed into a drill bit or a pointed end.

In addition, the inner plate, the upper plate is provided with a thin plate of a metal material; And a lower plate provided with a thicker thickness than the upper plate and supporting the upper plate. The central portion penetrated by the screw in the lower plate may be formed to have a thickness thinner than other portions of the surroundings.

A plurality of holes may be formed around the center portion of the lower plate.

The upper plate is provided with an Invar membrane having a thickness of 1.0 mm, and the lower plate is provided with stainless steel (SUS) having a thickness of 10.0 mm, and the thickness of the central portion may be formed with 1.0 mm.

A flange for connection with another pipe may be formed at the other end of the pipe.

The liquefied natural gas storage tank including the emergency discharge device according to the present invention, an insulating barrier composed of at least one sealing wall and at least one insulating wall, a hollow pipe fixed to be inserted into the insulating barrier, and to be sealed inside the pipe In the liquefied natural gas storage tank including a plurality of internal plates installed, and a heat insulating material filled in the space between the plurality of internal plates, in the event of an emergency, the internal plate is forcibly damaged, and the LNG inside the storage tank is the pipe. It is characterized by forming a flow path that can be discharged through.

The liquefied natural gas storage tank according to the present invention does not have a concept of a pipe structure penetrating the lower portion of the storage tank at all times, so there is no fear of LNG leaking through the pipe or the pipe connection, and the LNG inside the storage tank When an emergency such as a leak occurs, a part of the insulating barrier of the storage tank is forcibly damaged to create a drain hole, so that the LNG inside the storage tank can be quickly discharged to the outside without a separate large-capacity pump.

1 is a view schematically showing the structure of a liquefied natural gas storage tank according to the present invention.
2 is a view showing a part of the emergency discharge device according to the present invention.
3 is a plan view of the lower plate among the configurations shown in FIG. 2.
4 is a view sequentially showing the operation of the emergency discharge device according to the present invention.

In order to fully understand the present invention, the operational advantages of the present invention, and the objects achieved by the practice of the present invention, reference should be made to the accompanying drawings and the contents described in the accompanying drawings, which illustrate preferred embodiments of the present invention.

Hereinafter, the present invention will be described in detail by explaining preferred embodiments of the present invention with reference to the accompanying drawings. The same reference numerals in each drawing denote the same members.

In the present invention, the use of the terms'primary' and'secondary' is a function to primarily seal or insulate LNG based on LNG stored in a storage tank, or to function to seal or insulate secondaryly. It was used as a criterion for classification.

In addition, by convention, the term'upper' or'up' applied to the elements of the tank refers to the direction toward the inside of the tank, regardless of the direction to gravity, and likewise, the term'lower' or'down' refers to gravity It refers to the direction toward the outside of the tank regardless of the direction.

1 is a view schematically showing the structure of a liquefied natural gas storage tank according to the present invention, FIG. 2 is a view showing a part of the emergency discharge device according to the present invention, and FIG. 3 is in the configuration shown in FIG. 2 It is a top view of the bottom plate. 4 is a view sequentially showing the operation of the emergency discharge device according to the present invention.

1 to 3, the liquefied natural gas storage tank according to the present invention is provided with a support wall by the inner wall (H) of the hull, and one or more sealing walls (200, 400) stacked inside the support wall It can be seen that it is made of a multi-layered structure comprising at least one insulating wall (100, 300).

That is, according to the present invention, the secondary insulating wall 100, the secondary sealing wall 200, the primary insulating wall 300, and the primary sealing wall 400 sequentially from the hull inner wall H to the inner direction of the storage tank. It can be preferably applied to a membrane-type storage tank including thermally insulating barriers constructed by being stacked with.

The present invention is a type made of an insulating box filled with perlite powder or the like in a plywood box, such as a NO 96 type storage tank, and an insulating wall (100, 300) like a MARK III type storage tank. ) This polyurethane foam (PUF) can be freely applied to all types of insulation panels made of plywood plywood on the top and/or bottom surfaces.

The primary and secondary sealing walls 400 and 200 may be made of a metal material having excellent low-temperature brittleness, for example, stainless steel (SUS), invar, or aluminum.

In the liquefied natural gas storage tank according to the present invention, since there is no pipe structure passing through the lower portion of the storage tank at all times, there is no fear of leaking LNG through the pipe or the pipe connection.

The liquefied natural gas storage tank according to the present invention, when an emergency situation in which the LNG in the storage tank has to be rapidly discharged, damages a part of the insulating barrier of the storage tank by force to drain the drain hole (drain hole) through which the internal LNG can be discharged It includes an emergency discharge device 500 to form a.

Emergency discharge device 500, the pipe 510 is inserted and fixed to the bottom of the storage tank, at least one or more inner plate 520 installed inside the pipe 510, and a reciprocating motion on one side of the pipe 510 It is installed to be possible and includes a perforated member 530 that breaks through a hole in the inner plate 520.

Pipe 510 is inserted into the insulating barrier of the storage tank so that one end reaches the level (level) of the primary sealing wall 400 is installed inside the storage tank, the other end can be extended to the outside of the storage tank. The pipe 510 may be made of stainless steel (SUS) material.

The pipe 510 is a pipe body 511 having an'b' shape as a whole by bending a pipe of a hollow cylinder vertically, and a first connection plate formed to protrude on an outer circumferential surface of the pipe body 511 512 and a second connection plate 513.

The first and second connection plates 512 and 513 may be plate-shaped members protruding along the outer circumferential surface of the pipe body 511, and may be provided integrally with the pipe body 511.

The first connection plate 512 is disposed on the same plane as the primary sealing wall 400 of the storage tank, and the second connection plate 513 is disposed on the same plane as the secondary sealing wall 200, and each other The abutting parts can be joined by welding.

Since the pipe 510 is a pipe through which LNG is transported in an emergency, an insulated construction may be provided on the outside of the pipe 510 exposed to the outside of the storage tank, or provided in a double pipe structure to block the transmission of heat from the outside.

Flanges 540 are formed at the other end of the pipe 510, and various pipes for transporting LNG discharged through the pipe 510 from the inside of the storage tank may be connected.

In addition, inside the pipe 510, as described later, a filter for preventing fragments of the internal plate 520 damaged by the perforated member 530 or debris of an insulating material from being mixed with LNG and discharged (not shown). Can be installed.

The inner plate 520 may be installed at least one inside the pipe 510, and when provided in plural, may be spaced apart to form a layer with each other as shown in the drawing.

In the present invention, the inner plate 520 is installed at one end of the pipe 510, the first inner plate 520-a disposed on the same plane as the primary sealing wall 400, and the pipe 510 It is installed so as to be spaced downward from the first inner plate 520-a on the inner side of the second inner plate 520-b disposed on the same plane as the second sealing wall 200, and the inner side of the pipe 510. It may be installed to be spaced downward from the second inner plate 520-b, and may include a third inner plate 520-c disposed on the same plane as the bottom surface of the storage tank.

The inner plate 520 is joined to the inner circumferential surface of the pipe body 511 by welding to seal the inside of the pipe 510. The inner plate 520 may be provided as a flat circular plate having the same diameter as the inner diameter of the pipe 510.

In the space between the inner plates 520 which are spaced apart from each other, in order to prevent external heat from being transferred to the storage tank through the inner space of the pipe 510, such as glass wool or foam. The insulation can be filled.

On the other hand, each inner plate 520 may be composed of a top plate 521 made of a thin thin plate made of a metal material, and a bottom plate 522 supporting the top plate 521.

The upper plate 521 is a member that is damaged by the perforated member 530, as described later, and may be provided as having a weaker brittleness than other members, and preferably has an invar membrane of approximately 1.0 mm in thickness. membrane).

The lower plate 522 is provided thicker than the upper plate 521, and may be made of a metal material having low in-plane stiffness, such as stainless steel (SUS), to reduce thermal stress at the welding site when heat contraction occurs. have. The preferred thickness of the lower plate 522 may be formed to approximately 10.0mm.

The upper surface of the upper plate 521 may be supported by being welded to the upper surface of the lower plate 522, and then, in order to be easily damaged, only the periphery along the edges of the upper plate 521 and the lower plate 522 are joined by welding. Can be.

The lower plate 522 may have a central portion c having a thickness thinner than other portions. This, as will be described later, in order to allow the screw 531 of the perforated member 530 to rise through the central portion c of the lower plate 522, the brittleness of the portion (center portion) through which the screw 531 penetrates is weakly provided. will be. The preferred thickness of the central portion (c) may be formed to a thickness similar to the top plate 521 to approximately 1.0 mm.

The central portion (c) is provided to have a larger cross-sectional area than the cross-section of the screw 531, and the central portion (c) of the lower plate 522 has gold (crossing or folding) that crosses the center to facilitate damage caused by the screw 531. (Full marks or marks) may be formed in advance.

The central portion (c) as described above may be formed of a thin plate made of an invar material and formed by welding to a hole formed in the center of the lower plate 522, or a central portion (c) of the lower plate 522 by press processing or the like It can be processed in a variety of ways, such as forming only different thicknesses.

A plurality of holes h may be formed around the central portion c of the lower plate 522.

The perforated member 530 serves to break the inner plate 520 as described above, the screw 531 inserted through one side of the pipe 510, and the screw 531 to rotate the screw 531 ) Includes a wheel (wheel 532) coupled to the other end.

An insertion hole 514 into which a screw 531 is inserted is formed at one side of the pipe body 511. Threads are respectively formed on the inner circumferential surface of the insertion hole 514 and the outer circumferential surface of the screw 531, and the screw 531 may enter the pipe 510 by being screwed to the insertion hole 514. The insertion hole 514 may be formed so that the center of the screw 531 and the center of the inner plate 520 coincide.

The screw 531 may reciprocate (elevate) in the vertical direction within the pipe 510 by rotation about the insertion hole 514, and is installed inside the pipe 510 by the rise of the screw 531 Plate 520 may be damaged. At this time, the center portion c of the lower plate 522 of the inner plate 520 is first damaged, and then the upper plate 521 supported on the upper portion of the lower plate 522 is broken.

The screw 531 is positioned so as to penetrate the center of the inner plate 520, and one end may be processed in the form of a drill blade or a pointed tip to penetrate the inner plate 520.

The rotational force to rotate the screw 531 can be transmitted by a wheel 532 coupled to the other end of the screw 531. The wheel 532 can be driven by a motor (not shown) because it has to be turned by a sufficient force, and can be remotely controlled if necessary.

Hereinafter, an operation of the emergency discharge device 500 according to the present invention will be described with reference to FIG. 4.

4(a) shows the normal state of the liquefied natural gas storage tank according to the present invention, that is, the state before the operation of the emergency discharge device of the present invention.

At this time, when the need to rapidly discharge the LNG inside the storage tank due to an emergency such as leakage of LNG from the storage tank, the present invention, as shown in Figure 4 (b), perforated member 530 By raising the screw 531 of the inner plate 520 installed in the pipe 510 is sequentially broken from the bottom.

The rise of the screw 531 may be achieved by rotating the wheel 532 coupled to the other end of the screw 531 in one direction.

When the screw 531 rises and reaches the inner plate 520 side, first the center portion c of the lower plate 522 is punched, and then the upper plate 521 is punched or crushed.

As shown in (b) of FIG. 4, when the first sealing plate 400 is disposed on the same plane as the primary sealing wall 400 by the raised screw 531, the wheel is broken. The screw 531 is lowered again by rotating the 532 in the opposite direction. This is to prevent the flow of LNG discharged to the hole formed in the inner plate 520 is not blocked by the screw 531.

When the lowering of the screw 531 is completed, as illustrated in FIG. 4C, a flow path through which the LNG can be discharged is formed inside the pipe 510 by the damaged inner plate 520.

In addition, as the upper plate 521 is permanently deformed by the rise of the screw 531, a spaced apart is formed between the upper plate 521 and the lower plate 522, and a plurality of holes h formed in the lower plate 522 ) Also allows LNG to be discharged smoothly.

LNG discharged from the storage tank through the pipe 510 may be discharged to the outside through various pipes (not shown) coupled to the flange 540 of the other end of the pipe 510. The coupling between the various pipes and the flange 540 may be made before the inner plate 520 is damaged by the perforated member 530.

On the other hand, if a pressure device such as a pump is provided at the rear end of the pipe 510, the present invention is possible as a concept of transferring LNG discharged through the pipe 510 to a pressure tank such as a tank lorry. . In the absence of a pressurization device, the LNG can be transferred to a predetermined outer zone where stability has been examined or another atmospheric pressure tank at a lower height.

As described above, the liquefied natural gas storage tank according to the present invention, the secondary insulating wall 100, the secondary sealing wall 200, the primary insulating wall 300 and the primary sealing on the inner wall (H) of the hull The wall 400 can be preferably applied to a membrane-type storage tank in which it is sequentially stacked.

However, the present invention is not limited to the type of storage tank. In the present invention, it is the core of the invention to damage the outer plate of the storage tank and a part of the insulating barrier to form a drain hole, so any storage tank equipped with a sealing and insulating barrier for the storage of LNG is free to go wherever it is. Can be applied. Therefore, it is obvious that the present invention can be applied to a membrane-type storage tank as well as a stand-alone storage tank.

In addition, the present invention is not limited to the installation location of the storage tank. In this specification, although the storage tank is formed on the inner wall H of the hull as a preferred embodiment, the present invention is not limited thereto, and the emergency discharge device 500 described in this specification may be installed. If sufficient space is available, the storage tank may be installed in other areas including the upper deck.

The present invention is not limited to the described embodiments, and it is obvious to those skilled in the art that various modifications and variations can be made without departing from the spirit and scope of the present invention. Therefore, such modifications or variations will have to belong to the claims of the present invention.

100: secondary insulating wall 200: secondary sealing wall
300: primary insulating wall 400: primary sealing wall
500: emergency discharge device 510: pipe
511: pipe body 512: the first connecting plate
513: Second connection plate 514: Insertion port
520: inner plate 521: top plate
522: lower plate 530: perforated member
531: screw 532: wheel
540: flange

Claims (11)

In the liquefied natural gas storage tank comprising an insulating barrier consisting of at least one sealing wall and at least one insulating wall,
Includes; emergency discharge device to form a drain hole (drain hole) through which the LNG inside the storage tank can be discharged by forcibly damaging a part of the insulating barrier;
The emergency discharge device,
A pipe which is inserted into and fixed to the insulating barrier and has a hollow inside;
At least one internal plate installed inside the pipe to seal the inside of the pipe; And
A perforated member is installed to enable reciprocation on one side of the pipe to break the inner plate,
As the inner plate is damaged by the perforated member, a flow path through which LNG in the storage tank can be discharged is formed inside the pipe,
Liquefied natural gas storage tank including an emergency discharge device. The method according to claim 1,
The insulating barrier is provided in a structure in which a secondary insulating wall, a secondary sealing wall, a primary insulating wall, and a primary sealing wall are sequentially stacked from the inner wall of the hull toward the inside of the storage tank,
The pipe,
A pipe body having one end inserted into the insulating barrier so as to reach the level of the primary sealing wall, and the other end extending outwardly of the storage tank;
A first connection plate formed to protrude on the outer circumferential surface of the pipe body and connected to the primary sealing wall by welding on the same plane; And
It is formed to protrude on the outer peripheral surface of the pipe body, and includes a second connecting plate connected by welding on the same plane as the secondary sealing wall,
Liquefied natural gas storage tank including an emergency discharge device. The method according to claim 2,
The inner plate is provided in a plurality, the plurality of inner plates are spaced apart from each other to form a layer inside the pipe,
In the space between the inner plate spaced apart from each other, characterized in that the glass wool (glass wool) is filled as a heat insulating material,
Liquefied natural gas storage tank including an emergency discharge device. The method according to claim 3,
The plurality of internal plates,
A first internal plate disposed on the same plane as the primary sealing wall;
A second inner plate disposed on the same plane as the second sealing wall; And
Characterized in that it comprises a third inner plate disposed on the same plane as the bottom surface of the storage tank,
Liquefied natural gas storage tank including an emergency discharge device. The method according to claim 1,
The perforated member,
Screws are inserted through the insertion hole formed on one side of the pipe; And
It is coupled to the other end of the screw and includes a wheel for transmitting a rotational force to the screw,
The screw is characterized in that it is possible to enter the inside of the pipe by being screwed to the insertion hole,
Liquefied natural gas storage tank including an emergency discharge device. The method according to claim 5,
The screw is positioned so as to penetrate the center of the inner plate, characterized in that one end is processed in the form of a drill or pointed end,
Liquefied natural gas storage tank including an emergency discharge device. The method according to claim 6,
The inner plate,
A top plate provided with a thin plate of a metal material; And
It is provided with a thicker thickness than the upper plate; a lower plate supporting the upper plate; includes,
In the lower plate, the central portion penetrated by the screw is characterized in that it is formed to a thickness thinner than other parts around,
Liquefied natural gas storage tank including an emergency discharge device. The method according to claim 7,
Characterized in that a plurality of holes are formed around the center of the lower plate,
Liquefied natural gas storage tank including an emergency discharge device. The method according to claim 8,
The top plate is provided with a 1.0 mm thick Invar membrane,
The lower plate is provided with stainless steel (SUS) having a thickness of 10.0 mm, characterized in that the thickness of the central portion is formed of 1.0 mm,
Liquefied natural gas storage tank including an emergency discharge device. The method according to claim 9,
On the other end of the pipe, characterized in that the flange (flange) for connection with the other pipe is formed,
Liquefied natural gas storage tank including an emergency discharge device. In the space between the insulating barrier made of at least one sealing wall and at least one insulating wall, a hollow pipe inserted and fixed to the insulating barrier, a plurality of inner plates sealed to be installed inside the pipe, and the plurality of inner plates In the liquefied natural gas storage tank comprising a heat insulating material to be filled,
In the event of an emergency, it is characterized in that the internal plate is forcibly damaged to form a flow path through which the LNG inside the storage tank can be discharged through the pipe.
Liquefied natural gas storage tank including an emergency discharge device.

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