JP2014201241A - Lng carrier - Google Patents

Abstract

A self-contained tank that has a large tank volume with respect to a ship size and can reduce material costs can be adopted, and an economical hull structure is obtained. SOLUTION: A substantially rectangular tank 30 is installed in a hold without being integrated with a hull structure material 33, and left and right with respect to the center line direction of the ship at the bottom of the tank. , An angle θ intersecting the horizon is formed with an inclined surface of 4.0 degrees or less, and a support body 34 integrated with the hull structural member 33 is provided corresponding to at least these inclined surfaces, and the tank 30 is An LNG ship characterized by being installed on a support 30. [Selection] Figure 3

Description

  The present invention relates to a liquefied natural gas (LNG) ship.

Since LNG emits less nitrogen oxide and sulfurous acid gas during combustion, demand for LNG is increasing year by year as clean energy. LNG is a natural gas cooled to about -162 ° C and liquefied, and the tank of the LNG carrier that transports this gas at sea uses low-temperature materials to withstand a wide range of temperature changes. It has a structure that takes stress into consideration. In addition, since LNG carriers have a mission of high-speed and mass transportation, they are usually equipped with a navigation speed of around 20 knots, and the hulls tend to be larger and have a tank capacity exceeding 200,000 m ^3. Currently planned.

  In the conventional LNG carrier, the LNG tank mounted on the LNG carrier is roughly divided into two types, one is a moss type spherical tank system, and the other is a membrane system (for example, US Pat. Nos. 5,697,312 and 7,137,345). .

  In the moss type spherical tank system, a spherical tank made of an aluminum alloy is installed in the hold through a skirt-like support structure extending downward from its equator. In this tank, the weight of the liquid loaded therein and the dynamic force acting on the liquid loaded by the ship's sway are all carried by the tank itself and transmitted to the hull via the skirt. The heat insulating material for the tank is, of course, provided on the outer surface of the tank.

  On the other hand, the membrane tank is provided with a heat insulating material inside the double hull structure of the hull, and its surface is liquid-tightly covered with a membrane. In this type of tank, the liquid pressure of LNG is transmitted to the hull structure via a heat insulating material. The membrane is made of stainless steel or a nickel alloy (Invar) with a small thermal expansion coefficient.

  However, since the shape of the hold is almost box-shaped, if a moss-shaped spherical tank is housed therein, it is inevitable that a useless space is generated around the spherical tank. For this reason, the moss type spherical tank has a drawback that the tank volume is small for the size of the hull.

  On the other hand, since the membrane tank can be made in a shape along the hold, a large tank space can be obtained and volume efficiency is good. On the other hand, when a membrane tank encounters stormy weather when the load is half-loaded, the shaking of the hull and the shaking of the LNG liquid level synchronize, and a sloshing phenomenon in which excessive pressure is applied to the inner wall of the tank, that is, the hull shaking As a result, the liquid load in the tank swells violently and the impact may damage the membrane and heat insulating material. In a spherical tank, the tank wall is curved, so that it can receive impacts, and since the heat shield is outside the tank, sloshing is hardly a problem. Therefore, with respect to the membrane tank, it is required to keep the tank at a full load or close to it so that the LNG of the cargo does not wave.

  Most of the cargo tanks of LNG ships are moss type and membrane type. However, as mentioned above, there are merits and demerits, and the selection of the ship type that fully considers the advantages and disadvantages is important for the use of LNG ships. is there. Based on these advantages and disadvantages, an independent square tank was developed by a major shipyard in Japan as an ideal LNG cargo tank. An example is the SPB tank of IHI.

US Pat. No. 5,697,312 US Pat. No. 7,137,345

The independent square tank is an ideal system without the disadvantage that the tank volume is reduced for the size of the hull, unlike the spherical tank.
However, the material of the plate used is limited to the material having the strength characteristics in the cryogenic region, and stainless steel and aluminum are mainly used as the material. A few swords cannot be beaten, and only a few ships have been built.

  LNG is a liquid and is greatly affected by the behavior of the free surface in the tank. In particular, sloshing of the liquid level of the LNG ship tank under wave conditions is a phenomenon that the membrane type must absolutely avoid from its tank structure.

  A main object of the present invention is to obtain an economical hull structure by adopting an independent rectangular tank that has a large tank volume with respect to a ship size and can reduce material costs.

  Another object of the present invention is to obtain a hull structure that can appropriately cope with sloshing of the tank liquid level.

  Other issues will become apparent from the following description.

  The present invention that has solved the above problems is as follows.

<Invention of Claim 1>
It has a structure in which a substantially rectangular tank is installed in the hold without being integrated with the hull structural material.
On the bottom surface of the tank, an inclined surface having an angle of intersecting with the horizontal line of 4.0 degrees or less is formed on the left and right sides of the center line direction of the ship.
Corresponding to these inclined surfaces, a support body integrated with a hull structure material is provided, and the tank is installed on the support body.

(Function and effect)
If the tank is installed in the hold without integrating it with the hull structure (eg double hull structure) (no welded structure), expensive materials are unnecessary and economical. It becomes. Also, since the tank is substantially square, the volumetric efficiency of the tank is greater than the spherical tank.
On the other hand, on the bottom of the tank, left and right sides of the center line direction of the ship are formed as inclined surfaces with an angle of 4.0 degrees or less intersecting the horizontal line, and at least corresponding to these inclined surfaces, integrated with the hull structural material The support body which became becomes, and the said tank was installed on the said support body.
As a result, the side of the tank tends to occur as the hull undergoes thermal deformation due to fluctuations in the amount of LNG in the tank. This thermal deformation skidding is suppressed or prevented by the frictional resistance between the tank bottom surface and the support whose upper surface is inclined.
In addition, as a tank structure, in order to provide resistance to the sloshing phenomenon like the membrane structure, it is not necessary to use a special structure, and it is only necessary to select according to a structural material such as an oil tanker or an LPG tanker. It becomes a factor which raises economy in the selection of the material and structure.

<Invention of Claim 2>
The flat surface is formed in the center part of the tank bottom, a receiving body integrated with the hull structure material is provided corresponding to the flat surface portion, and the flat surface portion is installed on the receiving body. LNG ship.

(Function and effect)
Although it is possible not to form a flat surface on the bottom of the tank, it is advantageous in designing the strength of the tank by installing the flat surface of the tank on the body and supporting it with the main load of the tank. Become.

<Invention of Claim 3>
3. The LNG ship according to claim 1, wherein a plurality of the support bodies are provided on the left and right sides of the center line direction of the ship at intervals in the ship width direction.

(Function and effect)
If a plurality of support bodies are provided on the left and right sides at intervals in the ship width direction, the sideslip of the tank is smoothed and the weight is reduced.

<Invention of Claim 4>
3. The LNG ship according to claim 1, wherein a plurality of the support bodies are provided along the longitudinal direction of the ship at a distance in the ship width direction on the left and right sides of the center line direction of the ship.

(Function and effect)
If the support is provided along the longitudinal direction of the ship, the tank can be supported stably.

<Invention of Claim 5>
3. The LNG ship according to claim 1, wherein a plurality of the support bodies are provided in a dotted shape on each of the left and right sides of the center line direction of the ship.

(Function and effect)
A plurality of supports can also be provided in the form of dots on the left and right sides of the center line direction of the ship.

<Invention of Claim 6>
2. The LNG according to claim 1, wherein a key portion is integrally provided so as to protrude from the center upper portion of the tank, and a detent chock is provided on the hull structure material side in front of and behind the center line of the ship corresponding to the key portion. boat.

(Function and effect)
In order to make the upper center of the tank the center point of thermal deformation of the tank in the front-rear direction, a detent chock with a width in the ship width direction is provided on the hull side to minimize the movement of the tank in the front-rear direction. The point is the center of thermal deformation. Thereby, the stress of the connection part of the expansion joint of the tank and the tank-connected LNG pipe and the tank and the pipe outside the tank can be minimized.

<Invention of Claim 7>
The LNG ship according to claim 1, wherein the material of the rectangular tank is selected from aluminum alloy, 9% nickel steel, and stainless steel.

<Invention of Claim 8>
The LNG ship according to claim 1, wherein the LNG ship includes an LNG carrier ship, a FLNG ship, an FSRU ship, and an SRV ship.

(Function and effect)
The term “LNG ship” in the present invention is used in a broad sense including LNG carrier, FLNG ship, FSRU ship, SRV ship and the like.

As described above, according to the present invention, it is possible to employ an independent rectangular tank that has a large tank volume with respect to the ship size and can reduce material costs, and an economical hull structure can be obtained.
In addition, it is possible to suppress or prevent a side slip or a side shift of the tank due to the waves by a frictional resistance between the inclination of the bottom surface of the tank and the support body having the inclined upper surface.

It is a front view of an LNG ship. It is a top view of an LNG ship. It is a cross-sectional view of an LNG ship. It is a 4-4 line arrow directional view. It is a fragmentary top view which shows the other example of a support body. It is a cross-sectional view of another shape example of the tank. It is a cross-sectional view of another shape example of the tank.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

  As shown in FIGS. 1 and 2, this LNG tanker is connected in order of the bow portion 10, the tank compartment 12, the engine room 14, and the stern part 16 from the front. A chamber 20 is provided. The tank section 12 is partitioned into a plurality of sections by a horizontal partition wall 22. Reference numeral 23 denotes a partition wall with the bow portion 10.

In the present invention, it is an LNG ship having a structure in which a substantially rectangular independent tank 30 is installed in the hold without being integrated with the hull (double hull) structural members 32 and 33.
In addition, inclined surfaces 30A having an angle θ intersecting with the horizontal line H of 4.0 degrees or less are formed on the bottom surface of the independent rectangular tank 30 on the left and right sides of the center line direction of the ship, and correspond to these inclined surfaces 30A and 30A. Are provided integrally with the hull structural member 33, and the tank 30 is installed on the supports 34, 34,.

  Further, a flat surface 30B is formed at the center of the bottom surface of the tank 30, and a receiving body 35 integrated with the hull structure material 33 is provided corresponding to the flat surface 30B, and the flat surface 30B is provided as the receiving body 35. It is installed above. The supports 34, 34... Are provided along the longitudinal direction of the ship.

  In the present invention, the tank 30 is an independent rectangular tank, and is a structure installed in the hold without being integrated with the hull structure (for example, double hull structure) materials 32 and 33 (no welding structure is adopted). Expensive materials are unnecessary and economical. Further, since the tank 30 is substantially square, the volumetric efficiency of the tank 30 is larger than that of the spherical tank.

  On the other hand, inclined surfaces 30A having an angle θ intersecting with the horizontal line H of 4.0 degrees or less are formed on the bottom surface of the cubic tank 30 on the left and right sides of the center line direction of the ship, and correspond to these inclined surfaces 30A and 30A. Are provided integrally with the hull structural member 33, and the tank 30 is installed on the supports 34, 34, so that the hull is thermally deformed due to fluctuations in the amount of LNG in the tank. Along with this, the skidding of the tank 30 tends to occur. This thermal deformation skid is suppressed or prevented by the frictional resistance between the bottom surface 30A of the tank 30 and the support 34 whose upper surface is inclined.

  The inclination angle θ of the bottom surface 30A of the tank 30 that intersects the horizontal line H is not limited. However, if the inclination angle θ is increased, the amount of liquid is reduced and there is a possibility of extreme skidding. θ is preferably 4.0 degrees or less, and more preferably 0.5 to 2.5 degrees.

  On the other hand, a key portion 40 is provided so as to protrude integrally at the center upper portion of the tank 30, and detents (chock) 41, 41 are provided on the hull structural material side in front of and behind the center line direction of the ship corresponding to the key portion 40. It is desirable. Thereby, it can restrict | limit about the thermal deformation sliding movement of the front-back direction of a tank.

  Although not shown, a heat insulating material can be provided on the outer surface of the tank 30.

  In the above example, the supports 34, 34... Are provided along the longitudinal direction of the ship. However, an appropriate arrangement is possible. For example, as shown in FIG. is there.

  The “substantially square independent tank” in the present invention may be a square as a whole in cross section, and does not need to be strictly square. For example, as shown in FIG. 6, the tank 30C may have a chamfered portion 30a, a rounded portion 30b at the corner portion, and an inclined surface 30c at the upper surface.

  Further, as shown in FIG. 7, a tank 30D having a small tank 30d in the upper portion and a main body tank 30e in the lower portion may be used.

  As a material of the tank 30, aluminum alloy, 9% nickel steel, stainless steel, or the like can be used.

  The above embodiments can be further appropriately combined and employed.

  The present invention is applied to FLNG ships (LNG-FPSO (Floating Production, Storage and Off-loading system)), FSRU ships, and SRV ships, which have a problem of dealing with the sloshing phenomenon in addition to LNG carriers. it can.

  In the FLNG ship (LNG-FPSO), on the ship or barge with LNG storage capacity, the natural gas produced from the marine gas field is removed and liquefied to produce and store the LNG, and the LNG is transported to the LNG ship for transportation. To ship. Compared to the construction of a liquefaction plant on land, it is possible to reduce the construction of submarine pipelines from offshore gas fields to onshore, and to reduce the environmental burden because it does not involve coastal development. Since LNG-FPSO can be constructed and towed in the area, it is possible to secure workers relatively easily.

  The LNG ship of the present invention includes a regasification facility, and examples thereof include FSRU (Floating Storage and Re-gasification Unit) and SRV (Shuttle and Re-gasification Vessel). The FSRU is equipped with a regasification device, a ship with LNG storage capacity is fixed offshore, and LNG is received from other LNG ships. The natural gas regasified by the FSRU is sent to an onshore pipeline. SRV does not transfer LNG from other LNG ships, but transports LNG loaded on the liquefaction base to the receiving point, regasifies it on the deck, and sends gas to the onshore pipeline.

DESCRIPTION OF SYMBOLS 10 ... Bow part, 12 ... Tank section, 14 ... Engine room, 16 ... Stern part, 18 ... Living area, 20 ... Steering room, 30, 30A-30D ... Independent square tank, 30A ... Inclined surface, 30B ... Flat surface, 32, 33 ... hull structural material, 34 ... support, 35 ... receptacle, θ ... inclination angle.

Claims (8)

It has a structure in which a substantially rectangular tank is installed in the hold without being integrated with the hull structural material.
On the bottom surface of the tank, an inclined surface having an angle of intersecting with the horizontal line of 4.0 degrees or less is formed on the left and right sides of the center line direction of the ship.
Corresponding to these inclined surfaces, a support body integrated with a hull structure material is provided, and the tank is installed on the support body.   The flat surface is formed in the center part of the tank bottom, a receiving body integrated with the hull structure material is provided corresponding to the flat surface portion, and the flat surface portion is installed on the receiving body. LNG ship.   3. The LNG ship according to claim 1, wherein a plurality of the support bodies are provided on the left and right sides of the center line direction of the ship at intervals in the ship width direction.   3. The LNG ship according to claim 1, wherein a plurality of the support bodies are provided along the longitudinal direction of the ship at a distance in the ship width direction on the left and right sides of the center line direction of the ship.   3. The LNG ship according to claim 1, wherein a plurality of the support bodies are provided in a dotted shape on each of the left and right sides of the center line direction of the ship.   2. The LNG according to claim 1, wherein a key portion is integrally provided so as to protrude from the center upper portion of the tank, and a detent chock is provided on the hull structure material side in front of and behind the center line of the ship corresponding to the key portion. boat.   The LNG ship according to claim 1, wherein the material of the rectangular tank is selected from aluminum alloy, 9% nickel steel, and stainless steel.   The LNG ship according to claim 1, wherein the LNG ship includes an LNG carrier ship, a FLNG ship, an FSRU ship, and an SRV ship.

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