KR20090080464A - Ship and marine structure with a plurality of cargo tanks having different strength - Google Patents

Abstract

A vessel or a floating marine structure equipped with plural storage tanks having different strength is provided to satisfy the required strength to manufacture a vessel or a marine structure sufficiently, and to restrain the increase in the manufacturing cost to the maximum. A vessel(30) or a floating marine structure equipped with plural storage tanks having different strength includes plural storage tanks(31,32,33,34) for transporting or keeping liquid freight on the sea, wherein the storage tanks arranged in the location, where bearing strength for supporting an upper structure installed on an upper deck of the vessel or the floating marine structure is required, are composed of storage tanks having higher strength than the storage tanks arranged in the location where bearing strength for supporting an upper structure is not required, and the storage tanks arranged in the location, where bearing strength for supporting an upper structure installed on an upper deck of the vessel or the floating marine structure is not required, are composed of storage tanks requiring the lower manufacturing cost than the storage tanks arranged in the location where bearing strength for supporting an upper structure is required.

Description

SHIP AND MARINE STRUCTURE WITH A PLURALITY OF CARGO TANKS HAVING DIFFERENT STRENGTH}

The present invention relates to a ship or a floating offshore structure for transporting or storing a liquid cargo such as LNG at sea, and a method of manufacturing the ship or the floating offshore structure, and more particularly to the offshore on which the ship or offshore structure is operated. A ship or floating offshore structure having a plurality of storage tanks having different strengths and having different strengths according to the environmental conditions of the storage tank and the location of the storage tank, etc. It is about how to make.

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 The vessel includes a storage tank (commonly referred to as a cargo hold) that can withstand 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.

LNG FPSOs are floating offshore structures that are used to liquefy the produced natural gas directly from the sea and store it in storage tanks and, if necessary, to transport LNG stored in the storage tanks to LNG carriers. 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 state is installed in an offshore structure such as an LNG carrier, an LNG RV, an LNG FPSO, or an LNG FSRU that transports or stores a 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. Among them, membrane type storage tanks are divided into GTT NO 96-2 type and Mark III type as shown in Table 1, and independent tank type storage tanks are divided into MOSS type and IHI-SPB type.

GTT NO 96-2 type and GTT Mark III type were formerly called GT type and TGZ type. In 1995, Gaz Transport (GT) and Technigaz (TGZ) were renamed to GTT (Gaztransport & Technigaz). The GTT NO 96-2 type and the TGZ type are renamed and used as the GTT Mark III 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 GTT NO 96-2 type storage tank, the primary sealing wall 10 and 2 made of Invar steel (36% Ni) of 0.5 ~ 0.7mm thickness The primary sealing wall 15 and the primary heat insulating wall 11 and the secondary heat insulating wall 16 made of a plywood box, perlite, etc. are formed on the inner surfaces 1 and 2 of the hull. It is made up of alternately stacked.

In the case of the GTT NO 96-2 type, the primary sealing wall 10 and the secondary sealing wall 15 have almost the same liquid-tightness and strength, so that during the leakage of the primary sealing wall 10 for a considerable period of time. Only the secondary sealing wall 15 can safely support the cargo. In addition, the sealing walls 10 and 15 of the GTT NO 96-2 type have a straight membrane, and thus, welding is easier than that of the Mark III type waveform membrane, so the automation rate is high, but the overall welding length is longer than the Mark III type. In addition, in the case of the GTT NO 96-2 type, a double couple 17 is used to support the heat insulation box (ie, the heat insulation walls 11 and 16).

On the other hand, as shown in Figures 3 and 4, the Mark III type storage tank is composed of a primary sealing wall 20 made of a 1.2 mm thick stainless steel membrane (Membrane) and a triplex (triplex) The primary 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. Is done.

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 96-2 type secondary sealing wall due to the characteristics of secondary sealing wall.

By the way, the membrane-type liquefied natural gas storage tank is limited to the sloshing problem because there is a limitation in the installation of the reinforcement in the storage tank due to the structural characteristics. Sloshing refers to a phenomenon in which a liquid substance, ie, LNG, flows in a storage tank when a vessel moves in various sea conditions, and the wall surface of the storage tank is severely impacted by sloshing.

Since the sloshing phenomenon occurs more lightly during partial loading, it is necessary to design the storage tank structure to have sufficient strength to withstand the load due to the sloshing in the case of offshore structures such as LNG FPSO or LNG FSRU.

In addition, in the case of offshore structures such as LNG FPSO or LNG FSRU, various devices are installed on the upper part of the storage tank, so it is necessary to strengthen the strength of the storage tank so as to support the heavy upper structure.

However, the relatively high strength independent tank type storage tank is inferior in price competitiveness to the membrane type storage tank, and thus, the manufacturing cost is excessively increased when all the storage tanks included in the offshore structure are manufactured as independent tank types. .

On the other hand, considering that the size of storage tanks is gradually increasing with the recent increase in the size of ships or offshore structures, membrane type storage tanks have more competitive price than independent tank type storage tanks, There is a problem that the verification of the strength of the saw and the support strength of the superstructure has not yet been made.

Accordingly, the present invention is to solve the problems of the prior art, the object of the present invention is to operate a ship or a marine structure in a ship or a marine structure for transporting or storing a liquid cargo such as LNG at sea By installing different types of storage tanks according to the environmental conditions of the sea and the location of the storage tanks, a plurality of storage tanks having different strengths can be prepared by varying the strength of the storage tanks included in the ship or the offshore structure as necessary. It is to provide a ship or offshore structure provided and a method of manufacturing the ship or offshore structure.

According to an aspect of the present invention for achieving the above object, a ship or offshore structure including a plurality of storage tanks for transporting or storing liquid cargo at sea, the plurality of storage tanks contained in the ship or offshore structure Ships or offshore structures are provided that have different strengths from each other.

At least one storage tank of the plurality of storage tanks is preferably a different type of storage tank having a different strength from the remaining storage tanks.

Among the plurality of storage tanks included in the ship or offshore structure, as the at least one storage tank installed at the position where the pressure for sloshing is greatest, it is preferable that a storage tank having a higher strength than the remaining storage tanks is used. At this time, the ship or offshore structure is preferably any one selected from LNG transport ship, LNG RV, LNG FPSO and LNG FSRU.

In addition, as at least one storage tank installed below the position where the support strength for the upper structure is required among the plurality of storage tanks included in the offshore structure, it is preferable that a storage tank having a higher strength than the remaining storage tanks is used. Do. At this time, the ship or offshore structure is preferably any one selected from the LNG carrier, LNG RV, LNG FPSO and LNG FSRU.

The at least one storage tank is an independent tank type storage tank, and the remaining storage tank is preferably a membrane type storage tank.

When the vessel or floating offshore structure is an LNG carrier or LNG RV, the second storage in front of the plurality of storage tanks included in the vessel or floating offshore structure is the position where the pressure against sloshing is greatest The tank is an independent tank type storage tank, and the remaining storage tank is preferably a membrane type storage tank.

In addition, when the ship or the floating offshore structure is LNG FPSO or LNG FSRU, the first and the front from the front of the plurality of storage tanks contained in the ship or the floating offshore structure is required position for the support structure for the upper structure and The third storage tank is an independent tank type storage tank, and the remaining storage tank is preferably a membrane type storage tank.

Further, according to another aspect of the present invention, a method for manufacturing a ship or a marine structure comprising a plurality of storage tanks for transporting or storing liquid cargo at sea, the plurality of storage contained in the ship or the marine structure Calculating the strength required for the tank; A storage tank having a higher strength than the remaining storage tanks is used as at least one storage tank installed at a position where strong strength is required by the calculation among the plurality of storage tanks; There is provided a method of manufacturing a ship or offshore structure comprising a.

The calculating of the strength preferably includes calculating a pressure on sloshing for the plurality of storage tanks included in the vessel or the offshore structure.

In addition, the step of calculating the strength, preferably comprising the step of calculating the support strength for the upper structure for the plurality of storage tanks contained in the vessel or offshore structure.

As described above, according to the present invention, in a ship or offshore structure that transports or stores a liquid cargo such as LNG on the sea, it is different depending on the environmental conditions of the sea where the ship or offshore structure is operated and the location of the storage tank. By providing a storage tank of a kind, the vessel or the marine structure having a plurality of storage tanks having different strengths and the vessel or the marine structure having different strengths, the strength of the storage tank included in the vessel or the marine structure is different from each other as needed. A method of making is provided.

According to the ship or offshore structure of the present invention, an independent tank having a relatively high strength as a storage tank installed at a position where sloshing is strongly generated in a ship or offshore structure or a support strength for supporting the upper structure is required. Type storage tanks can be used, and membrane-type storage tanks can be used for other locations.

Accordingly, according to the present invention, a ship or offshore structure can be provided that can satisfactorily increase the manufacturing cost while satisfactorily satisfying the strength required in manufacturing the ship or offshore structure.

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

FIG. 5 schematically shows a vessel or floating offshore structure having a plurality of storage tanks having different strengths according to a first preferred embodiment of the present invention. The vessel 30 shown in FIG. 5 is, for example, an LNG carrier or LNG RV for transporting LNG at sea.

Therefore, in the case of the ship 30 (ie, LNG carrier or LNG RV) of FIG. 5, since the flow of the ship inevitably occurs at sea, the interior of the plurality of storage tanks 31 to 34 for transporting the cargo in the liquid state. The sloshing phenomenon is caused.

As described above, sloshing refers to a phenomenon in which a liquid substance contained in a storage tank, that is, LNG, flows when a vessel moves in various sea conditions, and the wall surface of the storage tank is severely impacted by sloshing. . Since the sloshing phenomenon inevitably occurs during operation of the ship, in the case of offshore structures 30 such as LNG carriers or LNG RVs that transport LNG, the storage tank 31 has sufficient strength to withstand the load due to sloshing. 34) It is necessary to design the structure.

In particular, when calculating the sloshing pressure through the experiment, it appears that the sloshing pressure of the storage tank located in front of the vessel (offshore structure 30) is large, usually at the most forward side of the vessel (most right side in FIG. 5). In the case of the storage tank 31 is located, because the size of the bow structure of the ship is small in size, the largest sloshing pressure actually occurs in the storage tank 32 located second from the front.

According to the present invention, in the case of the ship 30 as described above, only the storage tank 32 in which the sloshing pressure is most likely to be produced is made of an independent tank type having a strong structure, and the remaining storage tanks 31 and 33. And 34) are fabricated in a cost competitive membrane type.

In FIG. 5, four storage tanks 31 to 34 are included in the ship 30, and the storage tank 31 located at the foremost front is shown to have a small size, but the present invention is limited to this. Of course not. When the present invention is applied to the vessel 30, according to the magnitude of the sloshing pressure to produce a storage tank located in the place where the largest sloshing pressure occurs in an independent tank type.

FIG. 6 schematically shows a vessel or floating offshore structure with a plurality of storage tanks having different strengths according to a second preferred embodiment of the present invention. The floating offshore structure 40 shown in FIG. 6 is, for example, an LNG floating, production, storage and offloading (FPSO) or LNG floating storage and regasification unit (FSRU) for temporarily storing and processing LNG at sea. It is a floating offshore structure.

As described above, the LNG FPSO is a floating offshore structure used to directly liquefy the produced natural gas in the sea and store it in a storage tank, and, if necessary, to transfer the 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.

Therefore, unlike LNG carriers or LNG RVs that transport LNG, in the case of the floating offshore structure 40 (ie, LNG FPSO or LNG FSRU) of FIG. 6, various devices are installed on the upper portions of the storage tanks 41 to 44. Therefore, it is necessary to increase the strength of the storage tank to support the heavy upper structure (45, 46). In addition, since the floating offshore structure 40 of FIG. 6 is also used at sea, it is affected by sloshing like LNG carriers or LNG RVs, and the strength of the storage tank can be supported to support the pressure caused by the sloshing. You need to be strong.

According to the present invention, in the case of such a floating marine structure 40, only the storage tank (41, 43) installed in the lower portion of the position where the heavy upper structure (45, 46) is installed independent tank type having a strong structure And, the remaining storage tanks (42, 44) can be produced in a cost-effective membrane type.

6 includes four storage tanks 41 to 44 of the same size in the floating offshore structure 40, and the first and third storage tanks located at the front (right side in FIG. 6) ( It is shown that the heavy upper structure (45, 46) is installed on top of the 41, 43, of course, the present invention is not limited to this. When the present invention is applied to the floating offshore structure 40, in consideration of the weight of the upper structure (45, 46) and the pressure due to the sloshing storage tank located in the position where the greatest support strength is required as an independent tank type To make.

On the other hand, it has been described by taking an independent tank type storage tank as an example of a strong storage tank, and described as an example of a membrane type storage tank as a cost competitive storage tank, the present invention is not limited to only this type of storage tank. Of course.

In addition, although the independent tank type storage tank is installed at a position where high strength is required, and the membrane type storage tank is installed at other positions, it is described that the different types of storage tanks are arranged according to the required strength. In the case where the same kind of storage tank is made to have different strengths, the storage tank having the same strength can be used.

While the invention has been described above with reference to specific embodiments, various modifications, changes or modifications may be made in the art within the spirit and scope of the appended claims, and thus, the foregoing description and drawings It should be construed as illustrating the present invention rather than limiting the technical spirit of the present invention.

1 and 2 are a cross-sectional view and a perspective view of a GTT NO 96-2 type storage tank structure which is a storage tank structure of the LNG carrier 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 transport vessel according to the prior art,

5 is a schematic view of a vessel or floating offshore structure having a plurality of storage tanks having different strengths according to a first preferred embodiment of the present invention;

6 is a schematic view of a vessel or floating offshore structure having a plurality of storage tanks having different strengths according to a second preferred embodiment of the present invention.

<Description of Symbols for Main Parts of Drawings>

30 LNG carrier or LNG RV as a ship

31 ~ 34: Storage tank

40 LNG FPSO or LNG FSRU as floating offshore structures

41 ~ 44: Storage tank

45, 46: superstructure

Claims (1)

A ship or floating offshore structure comprising a plurality of storage tanks for transporting or storing liquid cargo at sea, Of the plurality of storage tanks, the storage tank arranged in a position where the support strength for supporting the upper structure installed on the upper deck of the ship or floating offshore structure is required, the support strength for supporting the upper structure is not required. It consists of a storage tank having a higher strength than the storage tank arranged in a non-position, Of the plurality of storage tanks, the storage tank arranged in a position where the support strength for supporting the upper structure installed on the upper deck of the ship or floating offshore structure is not required, the support strength for supporting the upper structure is required. Ship or floating offshore structure, characterized in that consisting of a storage tank having a lower manufacturing cost than the storage tank arranged in a position.

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