KR20100125873A - Floating structure having storage tanks arranged in three rows - Google Patents

Abstract

PURPOSE: A floating structure having storage tanks arranged in three rows is provided to reduce impact due to sloshing by the reduction in the width direction length of a storage tank. CONSTITUTION: A floating type structure comprises a center storage tank(3), a left storage tank(5), and a right storage tank(7). The center storage tank is arranged in the center of the inside of the hull(1). The left storage tank is arranged on the left side of the center storage tank. The right storage tank is arranged on the right side of the center storage tank. The center storage tank, the left storage tank, and the right storage tank are arranged in three rows. The width of the center storage tank is larger than the width of the right storage tank and the left storage tank.

Description

FLOATING STRUCTURE HAVING STORAGE TANKS ARRANGED IN THREE ROWS}

The present invention relates to a floating structure having a storage tank capable of storing liquefied gas, and more particularly, to a floating structure in which a membrane-type or standalone liquefied gas storage tank is arranged in three rows within the hull of the floating structure. will be.

Natural gas is transported in a gaseous state through onshore or offshore gas piping, or transported to a distant consumer while stored in a transport in the form of liquefied gas, such as LNG or LPG. Liquefied natural gas is obtained by cooling natural gas to cryogenic temperature (approximately -163 ℃), and its volume is reduced to about 1/600 than natural gas in gas state, so it is very suitable for long distance transportation through sea.

LNG carriers for loading LNG into the sea and loading and unloading LNG to land requirements include LNG storage tanks (commonly referred to as cargo holds) that can withstand the cryogenic temperatures of liquefied natural gas. LNG storage tanks installed inside LNG carriers can be classified into independent type and membrane type depending on whether the load directly affects the insulation.

Independent tank type storage tanks are either SPB type or Moss type storage tanks. These types of storage tanks use a large amount of non-ferrous metal as the main material, which greatly increases the manufacturing cost of the storage tanks. Currently, LNG storage tanks are the most frequently used membrane storage tanks. Membrane storage tanks are relatively inexpensive and have been proven in LNG storage tanks for a long time without causing any safety problems. .

Membrane type storage tanks are further divided into GTT NO 96 type and Mark III type, which are described in US Pat. Nos. 5,269,247, 5,501,359, and the like.

The GTT NO 96 type storage tank includes a primary sealing wall and a secondary sealing wall made of Invar steel (36% Ni) having a thickness of 0.5 to 0.7 mm, a plywood box and a perlite. The primary heat insulation wall and the secondary heat insulation wall which consist of) are alternately laminated on the inner surface of a ship body.

In the case of the GTT NO 96 type, the primary sealing wall and the secondary sealing wall have almost the same degree of liquid tightness and strength, so that when the leakage of the primary sealing wall occurs, the secondary sealing wall can support the cargo safely for a considerable period of time. . Also, the sealing wall of GTT NO 96 type is easy to weld than the Mark III type membrane because the membrane is straight type, so the automation rate is high, but the overall welding length is longer than Mark III type. In addition, in the case of GTT NO 96, a double couple is used to support an insulation box (that is, an insulation wall).

Meanwhile, the Mark III type storage tank includes a primary sealing wall made of a 1.2 mm thick stainless steel membrane, a secondary sealing wall made of a triplex, a polyurethane foam, and the like. The primary heat insulating wall and the secondary heat insulating wall formed are alternately provided on the inner surface of the hull.

In the case of Mark III type, the sealing wall has corrugated wrinkles, and shrinkage by the cryogenic LNG is absorbed by the corrugated wrinkles so that a large stress is not generated in the membrane. Mark Ⅲ type heat dissipation system is not easy to reinforce due to its internal structure, and its feature of preventing LNG leakage is weaker than that of GTT NO 96 type secondary sealing wall due to the characteristics of secondary sealing wall.

The liquefied natural gas storage tank of the membrane type described above is more vulnerable to sloshing problems because of its weak rigidity. Sloshing refers to a phenomenon in which a liquid substance contained in a storage tank, that is, liquefied gas such as LNG, flows when a vessel moves in various sea conditions. The wall surface of the storage tank is severely impacted by sloshing. .

Since the sloshing phenomenon inevitably occurs during the operation of the ship, it is necessary to design the storage tank structure to have a sufficient strength to withstand the impact force due to the sloshing.

A method of forming the upper and lower chamfers inclined at approximately 45 degree angles on the upper and lower sides of the storage tank to reduce the sloshing impact force of liquid cargo, such as LNG or LPG, especially in the left and right directions. Is being used.

In the case of the conventional storage tank having a chamfer, the problem caused by the sloshing phenomenon can be solved to some extent by forming a chamfer on the upper and lower portions of the storage tank, but as the ship is gradually enlarged, the size of the storage tank becomes larger The impact force due to sloshing was also greatly increased.

In addition to the problem that the impact force due to sloshing increases as the volume of the storage tank increases, the storage tank needs to be reinforced to support the load of the upper structure as the load of various devices installed on the upper portion of the storage tank increases. This has risen.

In particular, in recent years, as the demand for offshore plants such as LNG Floating, Production, Storage and Offloading (FPSO) or LNG Floating Storage and Regasification Units (FSRUs), that is, floating structures, has increased, In addition, it was required to solve the sloshing problem and the load problem of the superstructure.

LNG FPSO is a floating structure used to produce and liquefy natural gas directly from the sea and store it in a storage tank and, if necessary, to transfer LNG stored in the storage tank to an LNG carrier. In addition, the LNG FSRU is a floating structure that stores LNG unloaded from LNG carriers in a storage tank at sea far from the land, and vaporizes LNG as needed to supply land demand.

In the case of a floating structure in which various facilities are installed in the upper portion, such as LNG FPSO or LNG FSRU, there are problems in that the arrangement of the upper structure has many restrictions in consideration of the structure and strength of the storage tank installed in the hull.

As a result, the impact force due to sloshing can be reduced, and the floating structure can appropriately support the load of the upper structure and can increase the storage capacity of the liquefied gas and the space for the arrangement of the upper structure. Research needs to continue.

The present invention for solving these problems, by placing the membrane-type or independent liquefied gas storage tank in three rows in the hull, it is possible to reduce the impact force due to sloshing and to properly support the load of the upper structure At the same time it is to provide a floating structure that can increase the storage capacity of the space and liquefied gas for the arrangement of the upper structure.

According to an aspect of the present invention for achieving the above object, a storage tank for storing liquefied gas is disposed in the hull and used floating while floating at sea, the inside of the hull, the center of the hull The central storage tank disposed in the, and the left storage tank and the right storage tank respectively disposed on the left and right sides of the central storage tank is provided in a three-row arrangement is provided.

The width of the central storage tank is preferably longer than the width of the left storage tank and the right storage tank.

It is preferable that the upper and lower left and right side edges of the central storage tank, the left storage tank and the right storage tank are formed with a chamfer for reducing sloshing.

The chamfer provided on the left side of the left storage tank located farthest from the centerline of the hull and the chamfer provided on the right edge of the right storage tank include a chamfer provided on the right side of the left storage tank and a left side of the right storage tank. It is preferable to form longer than the chamfer installed in the corner.

A longitudinal cofferdam extending in the longitudinal direction of the hull is provided between the central storage tank and the left storage tank and between the central storage tank and the right storage tank, each storage tank having a sealing wall. It is desirable to be able to secure separate storage spaces sealed by the structure, respectively.

The reinforcing structure for supporting the load of the upper structure is preferably installed in the longitudinal cofferdam.

A partition wall is installed between the central storage tank and the left storage tank and between the central storage tank and the right storage tank, and each storage tank has a separate storage space sealed by a sealing wall structure. It is desirable to be able to secure it.

A chamfer is formed on the left side of the left storage tank and the right side of the right storage tank located farthest from the centerline of the hull, and a chamfer is not formed on the adjacent sides of the storage tanks and is perpendicular to the bottom surface or the ceiling surface. It is preferable to be connected to.

It is preferable that a lower passage through which the liquefied gas moves between the adjacent storage tanks is installed below the storage tank.

It is preferable that an upper passage through which the liquefied gas moves between the adjacent storage tanks is installed on the upper portion of the storage tank.

The floating structure is any one selected from the LNG FPSO, LNG FSRU, LNG transport ship and LNG RV, which is used in the floating state at the sea where the flow occurs while having a storage tank for storing the liquid cargo loaded in the cryogenic state desirable.

In addition, according to another aspect of the present invention, a storage tank for storing the liquefied gas is disposed inside the hull and used floating while floating at sea, the inside of the hull in three or more rows in the width direction The storage tank is arranged, and the floating structure is characterized in that the narrower storage tank is arranged as the farther away from the centerline of the hull than the storage tank located closer to the centerline of the hull.

In addition, according to another aspect of the invention, the storage tank is installed in the floating structure to store the liquefied gas, to reduce the effects of the sloshing phenomenon and at the same time to support the load of the upper structure of the floating structure Partitioned by a pair of longitudinal cofferdams installed in the hull and arranged in three rows in the width direction, wherein a distance between the pair of longitudinal cofferdams is longer than a distance from the longitudinal cofferdam to an adjacent sidewall of the hull. A storage tank having a three-row arrangement structure is provided.

According to the present invention as described above, there can be provided a floating structure in which the membrane-type or independent liquefied gas storage tank is arranged in three rows in the width direction in the hull.

According to the floating structure of the present invention, while the storage capacity of the liquefied gas can be increased while the widthwise length of each storage tank is shortened, the impact force due to sloshing can be reduced.

In addition, according to the floating structure of the present invention, it is possible to properly support the load of the upper structure by the cofferdam partition or reinforcing structure installed between the adjacent storage tanks in the width direction, sufficient space for the arrangement of the upper structure Can be secured.

Hereinafter, with reference to the accompanying drawings, a floating structure having a storage tank of a three-row arrangement structure according to a preferred embodiment of the present invention will be described in detail.

In the present specification, the floating structure is a concept including both an offshore plant and a vessel used while floating in an ocean where a flow occurs while having a storage tank for storing a liquid cargo loaded at a cryogenic state such as LNG. For example, it includes both offshore plants such as LNG Floating, Production, Storage and Offloading (FPSO) or LNG Floating Storage and Regasification Units (FSRUs), as well as vessels such as LNG carriers and LNG Regasification Vessels (RVs).

1 is a perspective view of main parts of a storage tank arranged in two rows. Figure 2 is a cross-sectional view of a floating structure having a storage tank arranged in three rows in accordance with the present invention, Figure 3 is a view for explaining the displacement of the fluid according to the separation distance from the center of the hull when lateral movement of the hull It is.

Referring to FIG. 1, an example in which the widths of the storage tanks arranged in two rows are the same is illustrated.

On the other hand, the floating structure according to the present invention, as shown in Figure 2, has a storage tank (3, 5, 7) arranged in three rows in the width direction for storing the liquefied gas inside the hull (1).

At this time, the central storage tank (3) disposed in the middle of the storage tanks arranged in three rows, compared to the left storage tank (5) and the right storage tank (7), respectively disposed on the left and right sides of the central storage tank (3) It is preferable that the width is long.

As shown in FIG. 3, the sloshing becomes more severe as it is farther away from the centerline of the hull. Accordingly, the impact force applied to the wall surface of the storage tank due to the sloshing is also worsened as farther from the centerline of the hull.

Therefore, the sloshing impact force in the left storage tank 5 and the right storage tank 7 becomes larger than the central storage tank 3 close to the centerline of the hull 1.

On the other hand, as the capacity of the storage tank is smaller and the width is smaller, the sloshing phenomenon is less likely to occur. As shown in FIG. 2, the widths of the left storage tank 5 and the right storage tank 7 are defined by the central storage tank 3. When the size of the left storage tank 5 and the right storage tank 7 is reduced by shortening the width, the sloshing phenomenon in the left storage tank 5 and the right storage tank 7 can be suppressed.

According to the invention, each of the storage tanks 3, 5, 7 may be a membrane type tank or may be a standalone tank.

In addition, according to the present invention, by installing only one pump tower each in two or more adjacent storage tanks in the width direction or longitudinal direction, reducing the total number of pump towers installed in the floating structure is required for manufacturing You can save money and time.

At this time, it is preferable that a lower passage 8a through which two or more adjacent storage tanks can move liquefied gas can be installed in the lower portion of the storage tank. In addition, the upper portion of the storage tank is preferably provided with an additional upper passage (8b) through which the boil-off gas can move. These lower passages 8a and upper passages 8b may be replaced by pipes.

Further, in order to withstand the impact force due to sloshing, chamfers may be formed at upper and lower left and right side edges of each storage tank, that is, the central storage tank 3, the left storage tank 5, and the right storage tank 7, respectively. have.

The chamfer formed by tilting the corner wall surface of the storage tank to approximately 45 degrees can change its size according to the magnitude of the sloshing impact force applied. For example, the upper right side of the chamfer 5a and the right storage tank 7 which are located farthest from the centerline of the hull 1 and are installed at the upper left corner of the left storage tank 5 where the sloshing impact force acts the most. It is preferable to form the chamfer 7a provided in the edge longer than the chamfer provided in another position.

Between each storage tank, ie between the central storage tank 3 and the left storage tank 5, and between the central storage tank 3 and the right storage tank 7 extends in the longitudinal direction of the hull 1 Longitudinal cofferdams may be installed.

Cofferdam is a grid-shaped structure in which a void space is provided therein, and a structure for installing a membrane-type storage tank in each compartment by vertically and horizontally dividing the internal space of the floating structure. Such a cofferdam is conventionally used as a cofferdam in a widthwise direction for partitioning between a plurality of storage tanks arranged in a row along the longitudinal direction of a floating structure.

The cofferdam installed between the storage tanks arranged in three rows according to the present invention may be divided into a longitudinal cofferdam and a width cofferdam. The widthwise cofferdam is a structure that allows the membrane-type storage tank to be arranged along the longitudinal direction by horizontally partitioning the inner space of the floating structure, and the longitudinal cofferdam vertically partitions the inner space of the floating structure. The structure is such that the membrane-type storage tank can be disposed along the width direction. The width cofferdam may form a front wall portion and a rear wall portion of the storage tank, and the longitudinal cofferdam may form a left or right wall portion of the storage tank.

In the present invention, a simple partition wall may be installed between each storage tank instead of the above-mentioned cofferdam. In addition, when the cofferdam is installed, a reinforcing structure such as a pillar for supporting the load of the upper structure may be installed inside the cofferdam.

In the field of floating structures having storage tanks for storing liquefied gas such as LNG, which is a cryogenic liquid cargo, the shape of the storage tank must be completely redesigned to achieve a three-row arrangement.

In a membrane type storage tank, the membrane, that is, the sealing wall cannot form a partition by itself, and when non-ferrous metal partitions are installed in the existing membrane type storage tank, the use of expensive nonferrous metals increases the price. In addition, when non-ferrous metal bulkheads are installed inside the membrane-type storage tank, special design considering the installation of bulkheads should be made. In addition, the inside of the storage tank may not be composed of a single membrane structure, and there is a potential risk of damage to the partition wall due to a discontinuity between the membrane structure and the partition wall.

According to the present invention, rather than simply dividing one storage tank into three, a structure for arranging three storage tanks each having a separate storage space in the width direction is proposed.

Longitudinal cofferdams or bulkheads are installed between the storage tanks arranged in three rows, and storage tanks formed to be arranged in three rows with the longitudinal cofferdams or bulkheads interposed therebetween are separately sealed by a sealing wall structure. Free up storage space.

Thus, according to the present invention, when viewed in the transverse direction of the floating structure, membrane storage tank, cofferdam (or bulkhead), another membrane storage tank, cofferdam (or bulkhead), and another membrane storage tank Is arranged in succession, it is possible to form a three-row arrangement structure by applying the proven manufacturing technology of the existing membrane-type storage tank (for example widthwise cofferdam), to install the intermediate longitudinal cofferdam Longitudinal cofferdam bulkheads (if necessary, additional reinforcement structures can be installed inside the cofferdam) serve to support the load of the upper structure at the same time.

The present invention can be applied to SPB type storage tanks as well as membrane type storage tanks. That is, when the present invention is applied to the SPB type storage tank, instead of simply installing a partition inside the SPB type storage tank, separate SPB type storage tanks may be arranged in three rows in the width direction.

In addition, a floating structure such as LNG FPSO is required to withstand such heavy loads because there are more upper facilities to be installed on the upper side than ships such as LNG carriers, the three-row arrangement structure of the storage tank as the present invention In the case of the thin partitions, rather than simply partitioning the tank by installing a longitudinal cofferdam, etc. between the separate membrane-type storage tanks, the cofferdam partition walls and the like can serve to support and distribute the upper load.

Meanwhile, according to the present invention, the upper and lower chamfers may be partially omitted to secure the storage capacity while arranging the storage tanks in three rows. That is, the chamfers 5a, 5b and 7a, 7b may be formed only at the upper left and lower side edges of the left storage tank 5 and the upper right and lower side edges of the right storage tank 7 in which the impact force due to sloshing is most strongly applied. have.

In this way, the storage capacity can be increased by arranging the storage tanks in three rows and by allowing the side surfaces to be connected substantially perpendicular to the bottom surface or the ceiling surface without forming a chamfer on adjacent sides of the storage tanks.

As described above, the structure in which the storage tanks are arranged in three rows according to the present invention is an important concept that breaks the existing concept that the membrane-type storage tanks are not suitable for producing floating structures supporting the partial stacking and superstructure. This is a change and allows for wider market entry of membrane storage tanks.

In addition, the present invention can be applied to arranging the storage tanks in four or more rows, in addition to the three rows arranged in the width direction.

Although the structure of the floating structure according to the present invention has been described with reference to the accompanying drawings as described above, the present invention is not limited to the embodiments and drawings described above, and the present invention belongs to the claims. Of course, various modifications and variations can be made by those skilled in the art.

1 is a perspective view of main parts of a storage tank arranged in two rows;

Figure 2 is a cross-sectional view of a floating structure having a storage tank arranged in three rows by applying the width of the tank differentially considering the distance from the hull centerline in accordance with the present invention, and

3 is a view for explaining the amount of displacement of the fluid in accordance with the separation distance from the center of the hull when lateral swing of the hull.

Description of the Related Art

1: hull 3: central storage tank

5: Left storage tank 5a, 5b: Chamfer

7: Right storage tank 7a, 7b: Chamfer

8a: Lower passage 8b: Upper passage

Claims (13)

As a storage tank for storing liquefied gas inside the hull and is used floating in the sea, The inside of the hull, the floating structure, characterized in that the central storage tank disposed in the center of the hull, the left storage tank and the right storage tank arranged on the left and right sides of the central storage tank are arranged in three rows. The method according to claim 1, Floating structure characterized in that the width of the central storage tank is longer than the width of the left storage tank and the right storage tank. The method according to claim 1, The upper and lower left and right side edges of the central storage tank, the left storage tank and the right storage tank is formed with a chamfer for reducing sloshing. The method according to claim 3, The chamfer provided on the left side of the left storage tank located farthest from the centerline of the hull and the chamfer provided on the right edge of the right storage tank include a chamfer provided on the right side of the left storage tank and a left side of the right storage tank. Floating structure, characterized in that formed longer than the chamfer installed in the corner. The method according to claim 1, A longitudinal cofferdam extending in the longitudinal direction of the hull is provided between the central storage tank and the left storage tank and between the central storage tank and the right storage tank, each storage tank having a sealing wall. Floating structure, characterized in that to secure each of the separate storage space sealed by the structure. The method according to claim 5, Floating structure, characterized in that the reinforcing structure is installed inside the longitudinal cofferdam for supporting the load of the upper structure. The method according to claim 1, A partition wall is installed between the central storage tank and the left storage tank and between the central storage tank and the right storage tank, and each storage tank has a separate storage space sealed by a sealing wall structure. Floating structure, characterized in that can be secured. The method according to claim 1, A chamfer is formed on the left side of the left storage tank and the right side of the right storage tank located farthest from the centerline of the hull, and a chamfer is not formed on the adjacent sides of the storage tanks and is perpendicular to the bottom surface or the ceiling surface. Floating structure, characterized in that connected to. The method according to claim 1, A floating structure, characterized in that the lower passage through which the liquefied gas can move between the adjacent storage tanks are installed in the lower portion of the storage tank. The method according to claim 1, Floating structure, characterized in that the upper passage for the liquefied gas is moved between the adjacent storage tank is installed on the upper portion of the storage tank. The method according to claim 1, The floating structure is any one selected from the LNG FPSO, LNG FSRU, LNG transport ship and LNG RV, which is used in the floating state at the flow of the flow while having a storage tank for storing the liquid cargo loaded in the cryogenic state Floating structure characterized by. A storage tank for storing liquefied gas is arranged inside the hull, and it is a floating structure that is used while floating at sea. The storage tank is arranged in three or more rows in the width direction in the hull, characterized in that the storage tank is narrower away from the centerline of the hull than the storage tank located closer to the centerline of the hull. Floating structure. A storage tank installed in the floating structure to store the liquefied gas, It is partitioned by a pair of longitudinal cofferdams installed in the hull of the floating structure and arranged in three width directions so as to reduce the influence of sloshing phenomenon and to support the load of the upper structure. And the distance between the pair of longitudinal cofferdams is longer than the distance from the longitudinal cofferdam to adjacent sidewalls of the hull.

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