JP6277554B2 - Carrier ship - Google Patents

Description

  The present invention relates to a transport ship that transports liquefied gas.

A transport ship that transports a liquefied gas such as LNG (liquefied natural gas) or LPG (liquefied petroleum gas) includes a tank that stores the liquefied gas. During transportation, a part of the tank is gasified by natural heat input from the outside. The pressure in the tank rises due to this gasification. Therefore, the vaporized gas (evaporated gas) is withdrawn from the tank and used as marine fuel.
The amount of the evaporated gas decreases as the composition of the liquefied gas that is the cargo changes according to the amount of the evaporated gas. Therefore, it is desired to further suppress the heat input to the tank from the outside.

  Patent Document 1 discloses a configuration in which a spherical tank is covered with a heat insulating material by fixing the heat insulating material on the outside of the spherical tank in a transport ship having a liquefied gas built in the spherical tank.

JP 58-164493 A

In the case where the heat insulating material is fixed to the outside of the spherical tank described above, it is necessary to increase the thickness of the heat insulating material in order to further suppress heat input from the outside to the tank. However, the weight increases as the thickness of the heat insulating material is increased, and the bending load generated on the heat insulating material when a temperature difference occurs is increased. Therefore, the burden of support members, such as a stud bolt for fixing a heat insulating material to a tank, may become large.
Even if the thickness of the heat insulating material is increased, the present invention stably fixes the heat insulating material to the tank, suppresses heat input to the tank from the outside, and reduces the amount of liquefied gas that is the load. An object is to provide a transport ship capable of suppressing the decrease.

According to the first aspect of the present invention, the carrier ship has a tank for storing liquefied gas, a hull having a tank housing portion for housing the tank, a panel-shaped base material, and the base material on the side close to the tank. A heat insulating material fixed to the surface of the tank and covering the upper part of the tank, and the pressure in the first gap outside the heat insulating material in the tank housing portion is the tank and the heat insulating material. A differential pressure generating section that generates a differential pressure between the first gap and the second gap so as to be larger than the pressure of the second gap between the first gap and the second gap. The second gap communicates with the lower end portion of the heat insulating material in the tank housing portion .
With this configuration, the heat insulating material provided so as to cover the tank is pressed to the surface side of the tank by the differential pressure between the first gap and the second gap. Thereby, a heat insulating material can be fixed with respect to a tank. Therefore, since a support member for supporting the heat insulating material on the tank is not required, the heat insulating material can be stably supported even if the heat insulating material is thickened to increase the weight of the heat insulating material or the temperature load is increased. For example, when it has fixing tools, such as a stud bolt which fixes a heat insulating material to a tank, the required intensity | strength can be reduced. Therefore, it is possible to reduce heat transfer by using a dissimilar joint (metal or resin) having a low heat transfer coefficient as the fixture, and for example, heat input to the tank via the fixture can be suppressed.

According to the second aspect of the present invention, in the transport ship, the differential pressure generating unit in the first aspect may generate a negative pressure in the second gap.
By comprising in this way, the atmospheric | air pressure of the 2nd clearance gap between the surface of a tank and a heat insulating material becomes small, and a heat insulating material can be attracted | sucked to the surface side of a tank.

According to the third aspect of the present invention, in the transport ship, the differential pressure generating section in the first or second aspect may pressurize the first gap.
By comprising in this way, the atmospheric | air pressure of the 1st clearance gap between a tank cover and a heat insulating material increases, and a heat insulating material can be pressed on the surface side of a tank.

According to the fourth aspect of the present invention, in any one of the first to third aspects, the transport ship may include a support member that supports the heat insulating material from below under the tank.
By comprising in this way, the heat insulating material which covers the downward direction of a tank can be pressed against the surface of a tank, and can be supported.

  According to the carrier, since the heat insulating material can be stably supported along the outer surface of the tank even if the thickness of the heat insulating material is increased, the heat input to the tank from the outside is further suppressed and the cargo is loaded. It is possible to suppress a decrease in the amount of liquefied gas.

It is a schematic diagram which shows the whole structure of the carrier ship which concerns on embodiment of this invention. It is sectional drawing which shows the heat insulation structure of the tank in 1st embodiment of the said transport ship. It is sectional drawing which shows the heat insulation structure of the tank in 2nd embodiment of the said transport ship. It is sectional drawing which shows the other example of a shape of the tank of the said transport ship.

Hereinafter, a transport ship according to an embodiment of the present invention will be described with reference to the drawings.
(First embodiment)
FIG. 1 is a schematic diagram showing the overall configuration of a transport ship according to an embodiment of the present invention. FIG. 2 is a cross-sectional view showing the heat insulating structure of the tank in the first embodiment of the carrier ship.
The transport ship 10 of this embodiment carries liquefied gas, such as liquefied natural gas (LNG) and liquefied propane gas (LPG).
As shown in FIGS. 1 and 2, the transport ship 10 includes at least a hull 11, a tank 12, heat insulators 20 </ b> A and 20 </ b> B, and a negative pressure generator (differential pressure generator) 30.

The hull 11 includes a tank housing portion 14 that forms a so-called hold space for housing the tank 12. The tank housing part 14 includes a housing recess 15 and a tank cover 13.
The accommodation recess 15 is recessed toward the lower ship bottom 11b with respect to the upper deck 11a and opens upward.

The tank cover 13 mainly covers the upper part of the tank 12. The tank cover 13 is provided on the upper deck 11 a of the hull 11. The tank cover 13 is formed in a convex shape upward. The tank cover 13 includes a rising portion 13a and a top plate portion 13b.
The rising portions 13a and 13a are provided so as to rise upward from the upper decks 11a and 11a located on both sides in the width direction of the hull 11 with the accommodating recess 15 in between.
The top plate portion 13b is formed so as to connect the contact portions 13a and 13a.
Further, the tank cover 13 is formed so that the height thereof gradually decreases at each end of the hull 11 on the bow 11c side and the stern 11d side (see FIG. 1).
Such a tank cover 13 is configured by combining a plurality of polygonal planar members 13p.

In the housing recess 15, a plurality of tanks 12 are arranged side by side from the bow 11 c side of the hull 11 toward the stern 11 d side. These tanks 12 store therein liquefied gas to be transported. These tanks 12 are made of, for example, an aluminum alloy, and have a spherical shape or a shape corresponding thereto. For example, the tank 12 may have a cylindrical shape with a certain diameter at the middle in the vertical direction, a hemispherical shape at the top and bottom, and an elliptical shape with a vertical cross-sectional shape that is long in the vertical direction.
Each tank 12 has an upper portion 12 a protruding upward from the upper deck 11 a of the hull 11. These tanks 12 are supported on a foundation deck portion 16 provided in the housing recess 15 via a cylindrical skirt 17. The tanks 12 are provided in the tank housing portion 14 between the inner circumferential surface 13 f of the tank cover 13 and the inner circumferential surface 15 f of the housing recess 15 with a space therebetween.

  The heat insulators (heat insulating materials) 20A and 20B are provided so as to cover the upper 12a side and the lower 12b side of the tank 12. Each of these heat insulators 20A and 20B is configured by laminating a heat insulating material 21 and a base material 22.

  As the heat insulating material 21, phenol resin foam, polyurethane foam, polystyrene foam, glass wool or the like can be used. The heat insulating material 21 may be provided by laminating a hard material such as phenol resin foam, polyurethane foam, polystyrene foam, and a soft material such as glass wool. In this case, the hard material and the soft material indicate relative hardness.

  The base material 22 is formed of a material having required strength and liquid-tightness, such as a metal such as an aluminum alloy, an aluminum resin composite plate, and a resin-based material. Such a base material 22 is formed, for example, by arranging a plurality of rectangular panels. Adjacent panels are joined by a joint material or the like to form a liquid-tight structure. At this time, between adjacent panels may be sealed with a plastic tape with aluminum foil or the like. The heat insulating material 21 is integrated with the base material 22 by adhesion or the like. When laminating a combination of a hard material and a soft material as the heat insulating material 21, one surface of the hard material as the heat insulating material 21 may be attached to the base material 22 and the soft material may be laminated on the other surface of the hard material. .

  The heat insulator 20A is curved and formed along the outer peripheral surface 12f of the tank 12 so as to cover the upper portion 12a of the tank 12. The heat insulator 20B is curved and formed along the outer peripheral surface 12f of the tank 12 so as to cover the lower portion 12b of the tank 12. In the heat insulators 20A and 20B, a heat insulating material 21 is disposed on the inner peripheral surface side that is concave. These heat insulators 20 </ b> A and 20 </ b> B are arranged to face the outer peripheral surface 12 f of the tank 12.

  At least one of the heat insulators 20 </ b> A and 20 </ b> B and the tank 12 includes a spacer (not shown) that keeps the heat insulating material 21 slightly separated from the outer peripheral surface 12 f of the tank 12. The gap maintained by this spacer is the second gap S2 in this embodiment. On the other hand, a first gap S1 is formed between the tank cover 13 and the heat insulator 20A. The first gap S1 is formed outside the heat insulating material 20A in the tank accommodating portion 14. The second gap S2 communicates with the first gap S1 at the lower end 20e of the heat insulator 20A. The second gap S2 is formed sufficiently narrower than the first gap S1. The second gap S2 formed between the heat insulator 20A and the heat insulator 20B and the tank 12 is to collect the liquid below the south pole by its own weight if the liquefied gas leaks from the tank 12. It becomes this flow path.

  The negative pressure generator 30 generates a differential pressure in the first gap S1 and the second gap S2 so that the pressure in the first gap S1 is larger than the pressure in the second gap S2. As the negative pressure generator 30, a vacuum pump can be used. The negative pressure generator 30 is provided outside the tank cover 13. The negative pressure generator 30 in this embodiment is connected to the top 20t of the heat insulator 20A. The negative pressure generator 30 sucks air in the second gap S2 between the base material 22 of the heat insulator 20A and the outer peripheral surface 12f of the tank 12. Therefore, the air pressure in the second gap S2 is relatively lower than the air pressure in the first gap S1. Here, the heat insulator 20A described above has a certain degree of airtightness in the thickness direction.

  That is, the heat insulator 20A provided so as to cover the upper portion of the tank 12 is pressed toward the outer peripheral surface 12f of the tank 12 by the differential pressure between the first gap S1 and the second gap S2.

The transport ship 10 further includes a support member 25. The support member 25 supports the heat insulator 20B that covers the lower portion 12b of the tank 12 from below. The support member 25 is provided with heat insulating properties in addition to the strength capable of supporting the support member 25 such as, for example, polystyrene foam.
At least three support members 25 are arranged at the bottom of the tank housing recess 15. These support members 25 support the lower portion 12b of the tank 12 at a plurality of locations spaced around the vertical axis.
By comprising in this way, the heat insulation body 20B which covers the downward direction of the tank 12 can be pressed against the outer peripheral surface 12f of the tank 12, and can be supported.

  Therefore, according to the carrier ship 10 of the first embodiment described above, the negative pressure generator 30 can generate a differential pressure in the first gap S1 and the second gap S2. 20A can be pressed to the outer peripheral surface 12f side of the tank 12. Thereby, the heat insulator 20A can be fixed to the tank 12.

  In addition, the transport ship 10 further includes a support member 25 that supports the heat insulator 20B from below under the tank 12, so that the heat insulator 20B that covers the tank 12 is pressed against the outer peripheral surface 12f of the tank 12 to support it. can do.

  Thereby, even if the weight of the heat insulators 20A and 20B increases or the bending load due to the temperature difference increases by thickening the heat insulators 20A and 20B to enhance the heat insulation, the heat insulators 20A and 20B are surely secured. Can be supported. As a result, by increasing the heat insulating properties of the heat insulators 20A and 20B, heat input to the tank 12 from the outside can be further suppressed, and a decrease in the amount of liquefied gas that is a cargo can be suppressed.

(Second embodiment)
Next, a second embodiment of the transport ship according to the present invention will be described. In the second embodiment described below, since only the configuration of the differential pressure generating device is different from that of the first embodiment, the same parts as those in the first embodiment are denoted by the same reference numerals, and redundant description is omitted. .
FIG. 3 is a cross-sectional view showing a heat insulating structure of a tank in the second embodiment of the carrier ship.
As shown in FIG. 3, the transport ship 10 in this embodiment includes a pressurizing device (differential pressure generating unit) 40 that generates a differential pressure in the first gap S <b> 1 and the second gap S <b> 2.

  In the pressurizing device 40, the air pressure in the first gap S1 between the tank cover 13 and the heat insulator 20A is larger than the air pressure in the second gap S2 between the outer peripheral surface 12f of the tank 12 and the heat insulator 20A. Thus, a differential pressure is generated between the first gap S1 and the second gap S2.

  A pressurizing pump can be used as the pressurizing device 40. The pressurizing device 40 is provided outside the tank cover 13. The pressurizing device 40 is connected to the top plate portion 13 b of the tank cover 13. On the other hand, a pipe (not shown) for discharging the air in the second gap S2 to the outside of the tank cover 13 is communicated with the second gap S2.

  When the pressurizing device 40 is operated, the atmosphere of the first gap S1 between the tank cover 13 and the heat insulator 20A is pressurized. Therefore, the air in the first gap S1 tends to flow toward the second gap S2. The second gap S2 is sufficiently narrower than the first gap S1. Therefore, the air pressure in the first gap S1 between the tank cover 13 and the heat insulator 20A is sufficiently larger than the air pressure in the second gap S2 between the outer peripheral surface 12f of the tank 12 and the heat insulator 20A. The heat insulator 20A is pressed toward the outer peripheral surface 12f of the tank 12 by this differential pressure.

  Therefore, according to the carrier ship 10 of the above-described second embodiment, even if the weight of the heat insulator 20A increases or the bending load due to the temperature difference increases by increasing the heat insulation by thickening the heat insulator 20A, The heat insulator 20A can be reliably supported. As a result, similarly to the first embodiment, heat input to the tank 12 from the outside can be suppressed, and a decrease in the amount of liquefied gas that is a cargo can be suppressed.

(Other variations)
In addition, this invention is not limited to each embodiment mentioned above, In the range which does not deviate from the meaning of this invention, what added the various change to embodiment mentioned above is included. That is, the specific shapes, configurations, and the like given in the embodiment are merely examples, and can be changed as appropriate.
For example, the negative pressure generating device 30 and the pressurizing device 40 generate negative pressure so that a differential pressure within a predetermined range is obtained while monitoring the atmospheric pressure in the first gap S1 and the second gap S2 with a pressure sensor or the like. You may control operation | movement of the apparatus 30 and the pressurization apparatus 40 with a controller.

  Further, in the heat insulator 20A, the heat insulating material 21 is exposed between the base 22 of the heat insulator 20A and the outer peripheral surface 12f of the tank 12 at the lower end portion 20e, but the lower end portion 20e of the heat insulator 20A is blocked. You may make it do.

  Further, a fixing tool such as a stud bolt can be used for fixing the heat insulators 20A and 20B to the tank 12. Even in such a case, the structure shown in each of the above embodiments can surely fix the heat insulators 20A and 20B to the tank 12, so that it is not necessary to make the stud bolts thicker than necessary. In addition, a fixing tool such as a stud bolt can be formed of a material such as a metal or a resin having a lower heat transfer coefficient than that of the tank 12, whereby heat transfer to the tank 12 can be suppressed.

  Further, when stud bolts are used for fixing the heat insulators 20A and 20B to the tank 12, the adsorption of the heat insulators 20A and 20B due to negative pressure or pressurization exceeds the load allowable by the stud bolts, for example, It may be generated as necessary when the acceleration due to the hull motion is large or when the temperature difference is large. Therefore, the operations of the negative pressure generating device 30 and the pressurizing device 40 may be controlled by a controller according to the operational status of the hull.

Further, the tank 12 is not limited to a spherical shape, and may have a shape corresponding to a spherical shape.
FIG. 4 is a cross-sectional view showing another example of the shape of the tank 12.
For example, the tank 12 may have a shape shown in FIG. In the tank 12 shown in FIG. 4, the middle part in the vertical direction is a cylindrical part 12g having a constant diameter in the vertical direction. In the upper part of the tank 12, a torus-shaped portion 12h and a spherical-shaped portion 12i are successively formed from the cylindrical portion 12g upward. A lower part of the tank 12 is formed with a spherical part 12j, a torus shape part 12k, and a spherical part 12m successively in order from the cylindrical part 12g downward.

Furthermore, in each embodiment mentioned above, the case where the several tank 12 was accommodated in the tank accommodating part 14 of the carrier ship 10 was demonstrated. However, the present invention is not limited to this configuration, and for example, the present invention can be applied to a transport ship including a plurality of tank housing portions that individually accommodate the tanks 12. Further, it may be a transport ship having only one tank 12.
The configurations shown in the above embodiments can be appropriately selected and combined.

DESCRIPTION OF SYMBOLS 10 Carrier 11 Hull 11a Upper deck 11b Bottom 11c Bow 11d Stern 12 Tank 12a Upper part 12b Lower part 12f Outer peripheral surface (surface)
12g Cylindrical parts 12h, 12k Torus-shaped parts 12i, 12j, 12m Spherical-shaped part 13 Tank cover 13a Standing part 13b Top plate part 13f Inner peripheral surface 14 Tank accommodating part 15 Accommodating recess 15f Inner peripheral surface 16 Foundation deck part 17 Skirt 20A Insulator (Insulation)
20B Insulator (Insulation)
20e Lower end part 20t Top part 21 Thermal insulation material 22 Base material 25 Support member 30 Negative pressure generation device (differential pressure generation part)
40 Pressurizer (Differential pressure generator)
S1 First gap S2 Second gap

Claims (4)

A tank for storing liquefied gas;
A hull having a tank accommodating portion for accommodating the tank;
A heat insulating material fixed to the surface of the base material close to the tank-like base material and the tank, and a heat insulating material covering the upper part of the tank;
The first gap in the tank housing portion so that the air pressure in the first gap outside the heat insulating material is larger than the air pressure in the second gap between the tank and the heat insulating material. A differential pressure generating section for generating a differential pressure with the second gap;
With
The transport ship in which the first gap and the second gap are communicated with each other at a lower end portion of the heat insulating material in the tank housing portion .   The transport ship according to claim 1, wherein the differential pressure generating unit generates a negative pressure in the second gap.   The transport ship according to claim 1, wherein the differential pressure generating unit pressurizes the first gap.   The transport ship as described in any one of Claim 1 to 3 further equipped with the supporting member which supports the said heat insulating material from the downward direction of the said tank.

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