KR20100003614U - Lng storage tank having an anti-sloshing structure - Google Patents

Abstract

The present invention relates to a liquefied gas storage tank of a ship or floating structure having a sloshing suppressing means therein so as to suppress the occurrence of sloshing.

According to the present invention, a liquefied gas storage tank which is installed in a floating offshore structure which is used in the floating or used in the sea or floating state to store the liquefied gas which is a liquid cargo, arranged in the upper portion of the storage tank in the storage tank A liquefied gas storage tank is provided, comprising sloshing suppression means capable of reducing the flow of the received liquid cargo.

Liquefied gas, liquid cargo, storage tank, slotting, containment, grating, opening

Description

LNG storage tank with sloshing suppression means {LNG STORAGE TANK HAVING AN ANTI-SLOSHING STRUCTURE}

The present invention relates to a liquefied gas storage tank installed on a vessel or a floating structure for transporting or storing liquefied gas such as liquefied natural gas (Liquefied Natural Gas) and liquefied petroleum gas (LPG). Specifically, the present invention relates to a liquefied gas storage tank having a sloshing suppressing means therein so as to suppress the occurrence of sloshing.

Natural gas is transported in a gaseous state through onshore or offshore gas piping, or to a distant consumer while stored in an LNG carrier in the form of liquefied liquefied natural gas (LNG). 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 transporter for loading and unloading LNG to land requirements by operating the sea with LNG, or LNG RV (Regasification) that reloads LNG after unloading the sea with LNG for recharging the stored LNG The vessel includes a storage tank (commonly referred to as a cargo hold) that can withstand the cryogenic temperatures of liquefied natural gas.

Recently, there is a growing demand for floating offshore structures such as LNG Floating, Production, Storage and Offloading (FPSO) or LNG Floating Storage and Regasification Units (FSRUs). Includes a storage tank installed.

The LNG FPSO is a floating offshore structure used to liquefy the produced 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, LNG FSRU is a floating offshore structure that stores LNG unloaded from LNG carriers in a storage tank at sea far from the land, and then vaporizes LNG as needed to supply land demand.

As described above, a storage tank for storing LNG in a cryogenic liquid state is installed in an offshore structure, such as an LNG carrier, LNG RV, LNG FPSO, or LNG FSRU, which transports or stores liquid cargo such as LNG.

These storage tanks can be classified into independent tank type and membrane type depending on whether the load of cargo is directly applied to the insulation. As shown in Table 1 below, membrane type storage tanks are generally divided into GT NO 96 type and TGZ Mark III type, and independent tank type storage tanks are divided into MOSS type and IHI-SPB type.

The GT and TGZ tank structures described above are described in U.S. Patent Nos. 6,035,795, 6,378,722, 5,586,513, and U.S. Patent Publication Nos. 2003-0000949 and the like, and Korean Patent Publication Nos. 10-2000-0011347 and 10-2000- 0011346 and the like. In addition, the structure of the independent tank type storage tank is described in Korean Patent Nos. 10-15063 and 10-305513.

As shown in Figures 1 and 2, the GT NO 96 type storage tank, the primary sealing wall 10 and the secondary sealing made of Invar steel (36% Ni) of 0.5 ~ 0.7mm thickness The wall 15 and the primary heat insulating wall 11 and the secondary heat insulating wall 16 made of plywood boxes, perlites, etc. alternately on the inner surfaces 1 and 2 of the hull. Lamination is made.

In the case of the GT NO 96 type, the primary sealing wall 10 and the secondary sealing wall 15 have almost the same liquid-tightness and strength, so that the secondary sealing wall 10 is leaked for a considerable period of time. Only the sealing wall 15 can safely support the cargo. In addition, since the membranes of the GT NO 96 type 10 and 15 have a straight membrane, welding is easier than that of the TGZ Mark III type waveform membrane, and the automation rate is higher, but the overall welding length is longer than that of the TGZ Mark III type. In the case of the GT NO 96 type, a double couple 17 is used to support the heat insulation boxes (ie, the heat insulation walls 11 and 16).

On the other hand, as shown in Figure 3 and 4, the TGZ Mark III type storage tank is composed of a primary sealing wall 20 and a triplex made of a 1.2 mm thick stainless steel membrane (Membrane) The secondary sealing wall 25 and the primary insulating wall 21 and the secondary insulating wall 26 made of polyurethane foam or the like are alternately stacked on the inner surfaces 1 and 2 of the hull. It is done.

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

When liquefied gas such as LNG or LPG is filled inside the storage tank, the impact of sloshing on the storage tank side wall and ceiling structure due to the flow of liquid, Rarely delivered. Sloshing refers to a phenomenon in which a liquid substance, ie, LNG, flows in a storage tank when a vessel or a floating structure moves in various sea conditions. When there is an empty space inside the storage tank, that is, when liquefied gas is filled in some spaces, the wall and the ceiling of the storage tank are severely impacted by the sloshing caused by the flow of the fluid.

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

In order to reduce the impact due to sloshing, as shown in FIG. 5, the upper chamfer 31 and the lower chamfer 32 are inclined at an angle of approximately 45 degrees to the upper and lower sides of the storage tank 30. A method of forming is proposed. Conventional membrane type storage tanks with upper and lower chamfers 31 and 32 have been able to withstand some loads by modifying the shape of the storage tanks, but they can only be operated under standard loading conditions, Even under conditions, it is recognized that additional measures are required to withstand the impact force due to sloshing sufficiently safely.

This sloshing phenomenon occurs more severely during partial loading. In addition, since LNG contained in the storage tank is evaporated by heat transferred from the outside of the storage tank, a certain amount of Boil Off Gas (BOG) is generated inside the storage tank.

As described above, in a state in which boil-off gas is generated in the storage tank or LNG is partially loaded, gas having a low specific gravity is collected in the upper space of the storage tank, and liquid flow occurs relatively severely in this portion.

The present invention for solving the above problems, by installing a structure for preventing sloshing at least partially on the side wall and the ceiling of the membrane-type storage tank to reduce the flow of the liquid cargo contained in the storage tank to suppress the occurrence of sloshing phenomenon To provide a liquefied gas storage tank.

According to the present invention for achieving the above object, as a liquefied gas storage tank which is installed in a floating offshore structure that is operated in the sea or used in a floating state to store the liquefied gas which is a liquid cargo, the upper portion of the storage tank A liquefied gas storage tank is provided, comprising sloshing suppression means arranged to reduce the flow of liquid cargo contained within the storage tank.

The sloshing suppressing means includes a longitudinal restraining means extending in the longitudinal direction of the storage tank and a transverse restraining means extending in the transverse direction of the storage tank, wherein the longitudinal restraining means and the transverse restraining means. It is preferable that it is arranged in this lattice form.

Preferably, the sloshing suppressing means includes horizontal suppressing means extending in the horizontal direction of the storage tank.

The sloshing suppressing means is preferably formed over the entire area of the ceiling of the storage tank.

The sloshing suppressing means is preferably formed only from the predetermined height of the storage tank to the ceiling.

Preferably, the sloshing suppressing means is formed at an upper edge where the ceiling and the four sidewalls of the storage tank abut.

The sloshing suppressing means, the portion attached to the ceiling is formed only from the predetermined height of the storage tank to the ceiling, the portion attached to the four-sided side wall is formed to extend further down, and is formed stepwise from the side It is preferable.

The longitudinal restraining means and the transverse restraining means preferably comprise openings formed to partially permit movement of the liquid cargo and thereby reduce resistance due to the liquid cargo.

In the portion where the longitudinal restraining means and the transverse restraining means come into contact with the ceiling of the storage tank, holes are formed to allow the movement of the boil-off gas generated by evaporation of the liquefied gas to prevent concentration of the boil-off gas at a specific point. It is preferable to be.

The liquefied gas storage tank is preferably a membrane tank.

According to the present invention as described above, the liquefied gas storage tank can be provided by reducing the flow of the liquid cargo contained in the storage tank by installing a structure for preventing sloshing at least partially on the side wall and the ceiling of the membrane-type storage tank.

As described above, according to the liquefied gas storage tank of the present invention, a structure for suppressing sloshing is installed in the upper space of the storage tank, so that the occurrence of the sloshing phenomenon can be suppressed at the source.

Hereinafter, a liquefied gas storage tank according to a preferred embodiment of the present invention will be described in detail with reference to the drawings.

FIG. 6A shows a cross sectional view of a liquefied gas storage tank having sloshing suppressing means according to the first preferred embodiment of the present invention, and FIG. 6B shows a partial cross-sectional view taken along the line A-A of FIG. 6A. 7A shows a cross-sectional view of a liquefied gas storage tank having sloshing suppressing means according to a second preferred embodiment of the present invention, and FIG. 7B shows a partial cross-sectional view taken along line B-B in FIG. 7A.

6A and 6B, the liquefied gas storage tank 40 according to the first embodiment of the present invention has a sloshing suppressing means arranged at the top. The sloshing suppressing means includes a longitudinal restraining means 41 extending in the longitudinal direction of the storage tank 40 and a transverse restraining means 43 extending in the transverse direction of the storage tank 40.

According to the first embodiment of the present invention, the longitudinal suppressing means 41 and the transverse suppressing means 43 are arranged in a lattice form to form a sloshing suppressing means. The sloshing suppressing means arranged in a lattice form is preferably formed over the entire area of the ceiling of the storage tank 40.

Further, the sloshing suppressing means according to the first embodiment of the present invention is formed only from the predetermined height of the storage tank 40 to the ceiling. The impact due to sloshing becomes larger when the storage tank is in an intermediate loading state or when boil-off gas is generated, but according to the first embodiment of the present invention, the sloshing suppression means is provided at a portion or more of a predetermined height of the storage tank 40. This installation can effectively reduce the flow of the liquid cargo.

Further, the longitudinal suppressing means 41 and the transverse suppressing means 43, which are sloshing suppressing means, are provided with openings 41a and 43a for partially allowing the movement of the liquid cargo to reduce resistance due to the liquid cargo. It is preferable.

In portions where these longitudinal suppression means 41 and the transverse suppression means 43 abut the ceiling of the storage tank, holes 41b and 43b for allowing the movement of the evaporated gas to prevent concentration of the evaporated gas at a specific point. ) Is formed.

According to the first embodiment of the present invention, the lower chamfer 45 is formed at the lower edge of the storage tank 40, but because the sloshing suppression means is formed on the upper portion of the storage tank 40, the chamfer is not formed. You don't have to.

As shown in Figs. 7A and 7B, the liquefied gas storage tank 50 according to the second embodiment of the present invention has a sloshing suppression means arranged at an upper edge portion where the ceiling and the four side walls abut. Similar to the first embodiment, the sloshing suppressing means of the second embodiment includes a longitudinal suppressing means 51 extending in the longitudinal direction of the storage tank 50 and a transverse extending in the transverse direction of the storage tank 50. Direction suppressing means (53).

On the other hand, unlike the first embodiment, the sloshing suppressing means of the first embodiment may include a horizontal direction suppressing means 52 extending in the horizontal direction.

According to the second embodiment of the present invention, the longitudinal suppression means 51, the transverse direction suppression means 53 and the horizontal direction suppression means 52 are arranged in a lattice form to form a sloshing suppression means. The sloshing suppressing means arranged in a lattice form may be formed over the entire area of the ceiling of the storage tank 50, or may be formed only at the edge portion of the ceiling as shown in FIG. 7A.

In addition, the portion attached to the ceiling of the sloshing suppression means according to the second embodiment of the present invention is formed only from the predetermined height of the storage tank 50 to the ceiling, while the sloshing suppression means according to the second embodiment of the present invention Among the portions attached to the four-sided side wall is formed to extend further down. Accordingly, as shown in FIG. 7A, the sloshing suppressing means of the second embodiment is formed to have a step in a stepwise manner when viewed from the side.

The impact due to sloshing becomes larger when the storage tank is in an intermediate state or when boil-off gas is generated. According to the second embodiment of the present invention, the sloshing suppressing means is provided at the upper edge portion of the storage tank 50. Installed, the flow of liquid cargo can be effectively reduced.

In addition, the longitudinal suppressing means 51, the transverse restraining means 53 and the horizontal restraining means 52, which are sloshing suppressing means, have an opening for partially allowing the movement of the liquid cargo to reduce resistance due to the liquid cargo. It is preferable that 51a and 53a be formed (the opening formed in the horizontal direction suppressing means 52 is not shown).

In addition, in the part where these longitudinal restraining means 51 and the transverse restraining means 53 contact | abut the ceiling of a storage tank, the hole 51b for allowing the movement of boil-off gas and preventing concentration of a boil-off gas at a specific point. , 53b).

According to the second embodiment of the present invention, although the lower chamfer 55 is formed at the lower edge of the storage tank 50, the chamfer is not formed because the sloshing suppressing means is formed on the upper portion of the storage tank 50. You don't have to.

The liquefied gas storage tanks 40 and 50 of the present invention are for accommodating cryogenic liquids such as LNG or LPG, and can be installed and used in various kinds of floating offshore structures. In the present specification, a floating offshore structure is a concept including both a structure 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 LNG carriers and LNG Regasification Vessels (RVs) as well as offshore structures such as LNG Floating, Production, Storage and Offloading (FPSO) or LNG Floating Storage and Regasification Units (FSRUs).

As described above, the storage tank structure of the floating offshore structure according to the present invention has been described with reference to the illustrated drawings, but the present invention is not limited to the embodiments and drawings described above, and within the scope of utility model registration claims. Various modifications and variations can be made by those skilled in the art to which the present invention pertains.

1 and 2 are a cross-sectional view and a perspective view of the structure of the GT NO 96 storage tank structure of the LNG storage tank according to the prior art,

3 and 4 is a cross-sectional view and a perspective view of the structure of the Mark III type storage tank of another LNG storage tank according to the prior art,

5 is a partial cutaway perspective view of an LNG storage tank having a chamfer according to the prior art,

6A is a cross-sectional view of a liquefied gas storage tank having sloshing suppressing means according to a first preferred embodiment of the present invention;

FIG. 6B is a partial cross-sectional view taken along the line A-A of FIG. 6A;

7A is a cross-sectional view of a liquefied gas storage tank having sloshing suppressing means according to a second preferred embodiment of the present invention, and

FIG. 7B is a partial cross-sectional view taken along the line B-B in FIG. 7A.

Description of the Related Art

40, 50: liquefied gas storage tank 41, 51: longitudinal restraining means

41a, 41b, 51a, 51b: openings 43, 53: transverse restraining means

43a, 43b, 53a, 53b: opening 45, 55: lower chamfer

52: horizontal direction restraining means

Claims (10)

It is a liquefied gas storage tank that can be stored in a floating offshore structure used in the sea or used in a floating state to store liquefied gas, which is a liquid cargo. And a sloshing suppressing means arranged on an upper portion of the storage tank to reduce a flow of the liquid cargo contained in the storage tank. The method according to claim 1, The sloshing suppressing means includes a longitudinal restraining means extending in the longitudinal direction of the storage tank and a transverse restraining means extending in the transverse direction of the storage tank, wherein the longitudinal restraining means and the transverse restraining means. A liquefied gas storage tank, characterized in that arranged in a grid form. The method according to claim 2, The sloshing suppressing means, the liquefied gas storage tank, characterized in that it comprises a horizontal direction suppressing means extending in the horizontal direction of the storage tank. The method according to any one of claims 1 to 3, The sloshing inhibiting means is formed over the entire area of the ceiling of the storage tank liquefied gas storage tank, characterized in that. The method according to any one of claims 1 to 3, The sloshing suppressing means, the liquefied gas storage tank, characterized in that formed only from a predetermined height of the storage tank to the ceiling. The method according to any one of claims 1 to 3, The sloshing inhibiting means is formed on the upper edge of the four sides of the ceiling and the storage tank is in contact with the liquefied gas storage tank. The method according to claim 6, The sloshing suppressing means, the portion attached to the ceiling is formed only from the predetermined height of the storage tank to the ceiling, the portion attached to the four-sided side wall is formed to extend further down, and is formed stepwise from the side Liquefied gas storage tank, characterized in that. The method according to claim 2, Wherein said longitudinal containment means and said transverse containment means comprise openings formed to partially permit movement of the liquid cargo and thereby reduce resistance due to the liquid cargo. The method according to claim 2 or 8, In the portion where the longitudinal restraining means and the transverse restraining means come into contact with the ceiling of the storage tank, holes are formed to allow the movement of the boil-off gas generated by evaporation of the liquefied gas to prevent concentration of the boil-off gas at a specific point. Liquefied gas storage tank characterized in that the. The method according to any one of claims 1 to 3, The liquefied gas storage tank is a liquefied gas storage tank, characterized in that the membrane tank.

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