The present invention relates to a hull support structure of a liquefied gas tank such as a spherical tank, and a liquefied gas carrier (transportation vessel) comprising the hull support structure.
Conventionally, to carry (transport) a liquefied gas such as a liquefied natural gas (hereinafter this will be referred to as “LNG”), a liquefied gas carrier (transportation vessel) including liquefied gas tanks is used. For example, as the liquefied gas carrier which carries the LNG, there is a liquefied gas carrier of a MOSS type, including a plurality of spherical liquefied gas tanks (cargo tanks: hereinafter this will be simply referred to as “spherical tanks”). Hereinafter, this liquefied gas carrier of the MOSS type will be exemplarily described.
As shown in
Further, an inner bottom plate 115 extending in the hull length direction is provided below the spherical tank 130. The both end portions of the inner bottom plate 115 in the hull width direction are connected to the foundation deck 111 via a pair of bilge hopper plates 117, respectively.
In the above-described conventional hull structure of
As an exemplary prior art of the above-described hull structure, there is a hull support structure which supports a skirt extending downward from the equatorial segment of a spherical tank, on the upper surface of a foundation deck provided at a predetermined height position of the hull (see e.g., Patent Literature 1). In this hull support structure, foundation deck support sections of the skirt are partially located outward in the hull width direction relative to locations at which the bilge hopper plates are connected to the foundation deck.
Patent Literature 1: Japanese Laid-Open Patent Application Publication No. Hei. 9-226682
In the case of the above-described hull support structure of
As shown in
Since the reinforcement members 125 are disposed on the inner side of the bilge hopper plate 117, and the reinforcement members 126 are disposed on the outer side of the bilge hopper plate 117, considerable time is required to make the reinforcement member 125 and the reinforcement member 126 coplanar with each other, at an intersection of the reinforcement member 125 and the bilge hopper plate 117, and an intersection of the reinforcement member 126 and the bilge hopper plate 117. In particular, the outer region of the bilge hopper plate 117 is commonly used as a ballast tank section. This ballast tank section is in a highly corrosive environment, and is subjected to a heavy-duty coating. For this reason, considerable time and labor are required to perform a work for coating the reinforcement members 126 provided below the skirt 135.
In view of the above-described circumstances, an object of the present invention is to provide a hull support structure of a liquefied gas tank and a liquefied gas carrier (transportation vessel), which can simplify the hull support structure of the liquefied gas tank to reduce members of the hull support structure, and to allow a work to be performed more easily.
To achieve the above-described object, a hull support structure of a liquefied gas tank of the present invention, comprises a foundation deck disposed around a liquefied gas tank; a skirt which supports the liquefied gas tank on the foundation deck; an inner bottom plate extending in a hull length direction, at a location that is below the liquefied gas tank; and a pair of bilge hopper plates each of which is provided between the foundation deck and corresponding one of both end portions of the inner bottom plate, wherein a plate connection section at which each of the pair of bilge hopper plates is connected to the foundation deck is disposed outward in a hull width direction, relative to a skirt connection section at which the skirt is connected to the foundation deck.
In accordance with this configuration, the plate connection section at which each of the pair of bilge hopper plates is connected to the foundation deck is disposed outward in the hull width direction, relative to the skirt connection section at which the skirt is connected to the foundation deck, and these connection sections do not cross each other. This makes it possible to dispose reinforcement members provided below the skirt only on the inner side of each of the bilge hopper plates. Therefore, it is not necessary to dispose the reinforcement members provided below the skirt on the outer side of each of the bilge hopper plates. As a result, the number of members can be reduced. In addition, the structure of the reinforcement members supporting the skirt, and the like, can be simplified, and hence the hull structure can be simplified. Further, the number of work steps can be reduced.
The hull support structure of the liquefied gas tank may further comprise: a pair of longitudinal bulkheads extending in the hull length direction along side shells, respectively, wherein the plate connection section at which each of the pair of bilge hopper plates is connected to the foundation deck may conform in a position in the hull width direction to a bulkhead connection section at which each of the pair of longitudinal bulkheads is connected to the foundation deck.
In accordance with this configuration, the longitudinal bulkhead included in the hull structure and the bilge hopper plate included in the hull structure are connected to the foundation deck at the same position in a vertical direction. This makes it possible to improve the continuity of the hull structure, and the strength of the hull structure.
Each of the pair of bilge hopper plates may be configured to linearly connect the inner bottom plate to the foundation deck.
In accordance with this configuration, the stiffness of the bilge hopper plate included in the hull structure can be improved, and the number of work steps can be reduced.
A liquefied gas carrier (liquefied gas transportation vessel) of the present invention, comprises any one of the above-described hull support structures of the liquefied gas tank; and a plurality of liquefied gas tanks arranged in the hull length direction, each of the plurality of liquefied gas tanks being as recited above.
In accordance with this configuration, the hull support structure of the liquefied gas tank can be simplified, the weight of the hull and the number of work steps can be reduced, and manufacturing cost of the liquefied gas carrier can be reduced.
The foundation deck may be provided at an equal height over an entire hull cargo hold in the hull length direction.
In accordance with this configuration, the continuity of the hull structure can be secured. In addition, the height of the skirt can be reduced, and the weight of the hull can be reduced.
In accordance with the present invention, the hull support structure of the liquefied gas tank can be simplified, the members of the hull support structure can be reduced, and the work for supporting the liquefied gas tank on the hull can be performed more easily.
Hereinafter, the embodiment of the present invention will be described with reference to the drawings. In the embodiment described below, a liquefied gas carrier (transportation vessel) of a MOSS type, including a plurality of spherical tanks, will be exemplarily described.
As shown in
Since the entire foundation deck 11 in the hull length direction is set at the equal height H10 which is higher than that of the conventional hull structure, in the above-described manner, a continuity of the hull structure between a first spherical tank 31 and a second spherical tank 32 can be secured. Specifically, in the above-described conventional hull structure of
In addition, an additional deck 141 provided continuously with the foundation deck 111 at the location of the first spherical tank 131 in the conventional hull structure may be omitted. Because of the omission of the additional deck 141, the weight of the hull, including reinforcement members used for connection of these decks, and the like, can be reduced.
Further, since the foundation deck 11 is disposed at the higher location, skirts (skirt structures) 35 for supporting the spherical tanks 30, including the skirt (tank skirt) 35 of the first spherical tank 31, can be disposed to be at an equal and reduced height. This makes it possible to reduce the weight of the skirt 35 having a large plate thickness. In this respect, the weight of the hull can also be reduced.
The foundation deck 11 is provided around the spherical tank 30 to support the spherical tank 30. The foundation deck 11 is provided to connect the pair of side shells 12 to each other in the hull width direction. A circular opening 16 with a size which is substantially equal to the inner diameter of the cylindrical skirt 35 is provided at a location at which the spherical tank 30 is provided. The pair of longitudinal bulkheads 13 are connected to the upper surface of the foundation deck 11.
A pair of bilge hopper plates 17 are provided in such a manner that each of them is disposed between the corresponding one of the both end portions of the inner bottom plate 15 in the hull width direction, and the lower end portion of the corresponding one of the pair of longitudinal bulkheads 13. The bilge hopper plates 17 also extend in the hull length direction. The bilge hopper plates 17 are inclined outward in the hull width direction, as they extend from the both end portions of the inner bottom plate 15. In the present embodiment, plate connection sections 20 at which the bilge hopper plates 17 are connected to the foundation deck 11 conform in positions in the hull width direction to bulkhead connection sections 21 at which the longitudinal bulkheads 13 are connected to the foundation deck 11, respectively. In this configuration, the bilge hopper plates 17 of the hull structure are connected to the longitudinal bulkheads 13 of the hull structure, respectively, via the foundation deck 11. As a result, the continuity of the hull structure and the strength of the hull structure can be improved.
In the present embodiment, the foundation deck 11 and the inner bottom plate 15 are connected to each other via the pair of bilge hopper plates 17 extending linearly (having a linear shape). In other words, the inner bottom plate 15 and the foundation deck 11 are linearly connected to each other via the pair of bilge hopper plates 17 of a flat plate shape. By linearly connecting the bilge hopper plates 17 to the bulkhead connection sections 21, respectively, at which the longitudinal bulkheads 13 are connected to the foundation deck 11, in the above-described manner, the stiffness of the hull structure can be improved, and the number of work steps can be reduced. Alternatively, the bilge hopper plates 17 may be connected to the bulkhead connection sections 21, respectively, in a manner which is different from the linear manner. For example, the bilge hopper plates 17 may be curved or bent several times.
The skirt 35 which is the cylindrical structure extending downward from the equatorial segment of the spherical tank 130 is supported on the foundation deck 11.
As shown in
As shown in
Since the skirt 35 and each of the bilge hopper plates 17 are connected to the foundation deck 11 in the above-described manner, reinforcement members 25 provided below the skirt 35 are disposed only on the inner side of the bilge hopper plate 17. In other words, since the skirt 35 is not located on the outer side of the bilge hopper plate 17, it is not necessary to provide the reinforcement members 25 on the outer side of the bilge hopper plate 17. Therefore, the reinforcement members 25 can have a simple structure, and the number of members can be reduced. As a result, it becomes possible to obtain advantages in that the hull structure can be simplified, and the number of members of the hull structure can be reduced.
As shown in
In brief, it is sufficient that the plate connection section 20 at which each of the bilge hopper plates 17 is connected to the foundation deck 11 is disposed outward in the hull width direction, relative to the skirt connection section 22 at which the skirt 35 is connected to the foundation deck 11. With the above-described hull support structure 5, the reinforcement members 25 provided below the skirt 35 may be disposed only on the inner side of the bilge hopper plate 17, and it is not necessary to provide the reinforcement members 25 on the outer side of the bilge hopper plate 17. This makes it possible to significantly improve the work efficiency. Although only the right part of the hull is shown in
Therefore, the reinforcement members 25 provided below the skirt 35 in the hull width direction are disposed only on the inner side of the pair of bilge hopper plates 17, and the reinforcement members 25 can be easily provided between the upper surfaces of the bilge hopper plates 17 and the foundation deck 11, by a work from the side of the upper surfaces of the bilge hopper plates 17. In addition, the reinforcement members 25 can have a simple structure. Thus, the work for providing the reinforcement members 25 can be carried out more efficiently. As a result, the work can be performed more easily, and work time and labor can be reduced.
As described above, in accordance with the above-described hull support structure 5, the hull structure such as the reinforcement members 25 provided below the skirt 35 supporting the spherical tank (liquefied gas tank) 30 can be simplified, and the members of the hull support structure 5 can be reduced. In addition, since the height of the skirt 35 supporting the spherical tank 30 can be reduced, the weight of the hull can be reduced.
Because of the reduction of the materials, material cost can be reduced. As a result, it becomes possible to construct the liquefied gas carrier (transportation vessel) 1 which can achieve reduction of the weight and reduction of the cost.
Although in the above-described embodiment, the foundation deck 11 is provided at an equal height over the entire hull cargo hold in the hull length direction, it is not necessary to extend the foundation deck 11 continuously at an equal height, and the configuration of the foundation deck 11 is not limited to the configuration of the above-described embodiment.
In the above-described embodiment, the liquefied gas carrier (transportation vessel) 1 of the MOSS type is exemplarily described, and the spherical tank 30 is exemplarily described as the liquefied gas tank. However, the present invention is applicable in the same manner to, for example, a liquefied gas tank of the MOSS type which is other than the spherical tank, so long as the liquefied gas tank is supported on the foundation deck 11 by the skirt 35, and the bilge hopper plates 17 are connected to the foundation deck 11. The shape or the like of the liquefied gas tank is not limited to the shape of the above-described embodiment.
Further, the above-described embodiment is merely exemplary, and can be changed in a variety of ways within the scope of the invention. The present invention is not limited to the above-described embodiment.
The hull support structure of the liquefied gas tank of the present invention can be utilized to realize, for example, reduction of the number of work steps of assembling the hull support structure of the liquefied gas tank, and reduction of the weight of the hull support structure.
Number | Date | Country | Kind |
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2014-101525 | May 2014 | JP | national |
Filing Document | Filing Date | Country | Kind |
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PCT/JP2015/002169 | 4/21/2015 | WO | 00 |