JPS59147192A - Liquefied-gas carrying vessel and method and device for heat-insulating tank for said vessel - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] Thermal method and apparatus.

BACKGROUND OF THE INVENTION The technical field of the present invention is the construction technology of ships carrying liquefied gases, in particular liquefied petroleum gases.Today, two techniques are used for thermally isolating the tanks of ships used for transporting liquefied gases.

It is known that the tank is a rectangular, self-supporting tank whose bottom rests on a support, so that there is a gap of 450 to 500 M below the bottom of the tank.

Similarly, the vertical side walls of the tank are separated by a circumferential gap on the order of 600 degrees from vertical bulkheads that generally limit the capacity of the last or may form part of the outer hull.

According to the first technique, the insulation of the bottom and vertical side walls is achieved by adding a powder or granular insulation material, such as expanded nitrite, or thermal insulation or similar properties, to the free space below the bottom and the surrounding space. This is achieved by filling it with motsu-zeta-mickeylite or other substances such as glass powder.

In this technique, perlite or similar material is poured in loose form into a tank tank until it fills the space.

According to a second technique, the insulation of the bottom and side walls is provided by a coating of thermal insulation material, for example boards of foamed polyurethane, foamed polystyrene or other foams with similar properties or flannel of mineral or synthetic fibers. 9 by fixing by pasting, pasting or other similar means.

The first technique is mostly expensive. Expanded nocrite is a low-cost substance and can be transferred to a desired location using compressed air or the like, which greatly reduces operating costs and filling time.

On the other hand, the thickness of the insulation material is equal to the size of the free space under the bottom or the surrounding space, i.e. from 450 to 600 cm, which results in a very good insulation effect with low loss of heat. This reduces the capacity of the cooling system, saving equipment investment, and reducing the cost per year on a 70,000ηI ship.
0 0 0 0 It is possible to save energy consumption amounting to a very significant amount on the order of USD 0.00.

In addition, zoolite is an absolutely inert mineral substance that does not require special precautions during filling and is not a fire hazard.

Despite these advantages, insulating with loose perlite has the disadvantage that the perlite fills the entire space located under the bottom of the perlite, making it difficult to place it anywhere. exist.

As a result, it is not possible to approach or inspect the supports and struts that prevent horizontal movement of the tank unless the armlight is removed and the tank is accessed below the tank.

Insulation by sheathing is more expensive because it requires more time and labor to install. Moreover, since a passage is required between the tank and the hull for its installation, the thickness of the coating is limited to about 10α, which reduces the heat insulation effect. However, since it can freely enter the space under and around the tank, it is possible to periodically inspect the condition of the stands and supports supporting the tank.

The object of the present invention is to develop an insulation technique for tanks of liquefied gas carriers that combines the advantages of the two conventional insulation techniques and partially eliminates their disadvantages.

This objective is achieved by the insulation method and device described below.

The method of insulating the tanks of a liquefied gas carrier according to the present invention includes: fixing a coating of insulating material on the outer surface of the bottom of the tank to insulate the bottom of the tank; - free space surrounding the vertical side walls of each tank; a flexible partition made of knitted fabric is installed laterally in the lower part, and a pair of flexible partitions made of knitted fabric are placed in the free space spaced apart from each other to form a chimney-like passage; , one insulating the vertical side walls of the tank by filling said free space other than said chimney-like passage with particles of insulating material;
Contains each operation.

The insulation device according to the invention applies to a self-supporting tank having a horizontal bottom placed on a horizontal support creating a free space under the bottom of the tank, side walls surrounded by surrounding free space, and a ceiling. Applicable.

The insulation device according to the invention consists of an insulating covering consisting of cellular foam or fibers fixed to the outer surface of the bottom and ceiling of the knee tank; - a flexible partition of knitted fabric fixed longitudinally over the entire height of the free space and forming a passageway into and out of the space below the tank;
and - a particulate insulating material filled in the surrounding free space except for the passage.

According to the invention, it is possible to capture vessels carrying liquefied gas, in particular liquefied petroleum gas, with a very effective and inexpensive insulation device, which allows access to and inspection of supports or supports under tanks. .

Filling the space around each tank with expanded perlite offers the advantages of conventional insulation techniques consisting only of expanded perlite.

The perlite is prevented from filling the space under the tank by a flexible partition that closes off the lower part of the surrounding space, and 2
- Vertical passages installed over the entire height of the light allow the operator to enter under the tank and therefore remove perlite.Inspect the condition of supports or supports under the tank and prevent accidental damage. leaks can be found, localized, and repaired.

The nature of the flexible partition, placed horizontally or vertically below the surrounding space, to dam the perlite and define the vertical passageway constitutes an important feature of the invention. Their composition (polyamide fibers, e.g. 'Kevlar' (
Thanks to the fabrics of synthetic fibers, such as (Trade Mark) fibres, knitted fabrics of synthetic fibers, knitted fabrics of glass fibers or carbon fibers, or stainless steel wire mesh), these partitions have a mechanical resistance that supports the weight of the perlite. , and is resistant to corrosion and other damaging factors such that it does not need to be replaced during the life of the ship. Thanks to the flexibility of these partitions, they follow the expansion and contraction of the tank and the elastic deformation of the hull structure without forcing.

These partitions are gas permeable and thus allow the passage of scavenging inert gas which is blown under the tank bottom.

These sweetened partitions can allow liquid to pass through. Thus, in the event of a leakage, the accumulation of water in the P-light is avoided, and the outflow of liquid can be easily localized in the event of damage.

These partitions do not allow the particles of salite to pass through.

Figures 1 and 2 show liquefied gases, such as butane, propane or other hydrocarbons or ammonia;
1 schematically depicts a hull I of a carrier vessel.

The hull 1 is equipped with vertical and horizontal bulkheads 2 on the inside defining a paralast volume 3θ which is filled with water for loading with paralast on the return journey when the cargo is emptied.

The ship is equipped with a plurality of self-supporting tanks 3, generally in the form of a parallelepiped.

The tank 3 is placed on a wooden horizontal support 4 supported on the horizontal bulkhead 2a, so that there is a free space 5 between the bottom 3a of the tank and the horizontal bulkhead. In addition, the bottom of the tank is supported by a support 6 that prevents horizontal movement of the tank in the lateral and longitudinal directions.

The vertical side walls of the tank 3 are separated from the bulkhead 2 by a space 7 of approximately 5 m to 70 m in size, which surrounds all the tanks as shown in Figure 2. It contains a liquefied gas kept in a liquid state, and the side walls of the tank must be thermally very well insulated.

The bottom of the tank is insulated by a foam material, for example foamed polyurethane or foamed polystyrene, or a textile covering 8. Space 5 is K 50 t so that humans can approach it.
Since the sheathing 8 has a size of about yn and a thickness of about 10α, it is possible to fit between this heat insulating material and the horizontal partition wall 2a. The coating 8 is applied to the bottom of the tank, to the outer surface of 3a, or otherwise secured in a similar manner. The tank ceiling 3b is likewise insulated by a foam or fiber insulation covering 8b.

The surrounding space 7 is filled with loosely injected particles 9 of an insulating material, which is preferably expanded perlite, but may also be an equivalent material, for example expanded ζ-miculite or expanded glass particles. .

The problems to be solved are: ・The light does not fill space 5, and in order to enter space 5, ・A passage 10 that traverses the light
It is to establish.

To solve this problem, partitions with sufficient mechanical resistance to resist the weight of the pearlite and thus the pressure on the surroundings were employed.

In addition, these partitions must be sufficiently flexible and pliable to follow movements of the tank due to significant changes in temperature, etc. without forcing.

These partitions must retain the smallest pearlite particles with dimensions on the order of 50-100 microns.

These partitions must be liquid permeable so that in case of water ingress or leakage of liquefied gas, liquid can flow out of space 5I/C without accumulating in the /4'-light. Likewise, these partitions must be gas permeable.

In fact, on these ships, nitrogen is used to remove flammable gases originating from liquefied gas leaks and to sweep away dust around the tanks in order to eliminate the risk of the formation of explosive gas mixtures. An inert gas such as gas or carbon dioxide is injected into the space 5. Therefore, the inert gas must be able to freely circulate from space 5 toward space 7 and be light.

In order to satisfy all these conditions, polyamide fibers, preferably those designated by the trademark 'Kevlar',
Glass fiber, carbon #! A flexible partition II made of a very fine mesh (50-100 micron) knitted fabric or net of fiber or metal wire, such as stainless steel wire, was employed. Multiple sheets of partitions can also be used stacked to increase mechanical resistance.

When using a metal mesh, it is possible to overlap a fine-mesh mesh made of extremely thin wires with a large-mesh mesh made of thick wires to reinforce this and provide mechanical strength. It is.

FIG. 1 shows two possible positions for these partitions.

In the right part of FIG. 1 there is shown a partition 11a arranged horizontally across the lower part of the surrounding space 7, which partition has one part attached to the vertical side wall of the tank 3 and the other part attached to the vertical side wall of the tank 3. It is fixed to a vertical partition wall 2.

Also shown on the left side of the figure is a partition 11b arranged vertically across the edge of the space 5, with one part at the bottom 3tLK of the tank and the other part at the horizontal partition wall 2a.
are fixed respectively.

In these two cases, a partition 11h or llb separates the lower part of the surrounding space 7 from the space 5 and holds the substance 9.

As can be seen from Figure 2, 1 is installed vertically in the surrounding space 7 at intervals of about 1 m to allow people to pass through.
Pair of flexible partitions 12PL.

Each vertical passage 10 is defined by 12b.

These passages 10 are equipped with closures (not shown). Preferably, these passages 10 are arranged along the vertical edges of the tank, so that the passages have a larger cross-section and can be insulated and require very little tank surface.

Furthermore, FIG. 2 shows a flexible intermediate partition 13 fixed vertically in the middle of the substance 9 in the surrounding space, so that
The aggregate of light is divided into a plurality of sections separated by intermediate partitions 13. Because of this division, in the event of a leak, it is sufficient to check the compartment where the leak is occurring and empty that compartment for repairs.

The intermediate partition 13 and the partitions 12a and 12b are the partition 1 described above.
It can be constructed from the same knitted fabric as 1a and Ilb.

FIG. 3 is a partially enlarged view showing the fixed portion of the partition 11a.

Components corresponding to those in FIGS. 1 and 2 are given the same reference numerals.

A wooden beam 14 is fixed to the side wall by a member 4a joined to the lower edge of the side wall 3 of the tank or by similar means. Waterproof putty is interposed between the beam 14 and the side wall of the tank,
In the event of a liquid leakage, the liquid that runs down on the outer surface of the side wall is prevented from penetrating directly into the polyurethane coating 8. The partitioning net 11h is attached to the partition wall 2 on one side and the beam 4 on the other side.

FIG. 4 shows that the partition 11a is connected to the vertical side wall 3 or bulkhead 2 of the tank.
Another way to fix it is to enlarge it.

The wooden beam 15 is fixed to the vertical side wall 3 along its lower edge by any means. To support this beam 15, a counterpart I6 or similar member is joined to the side wall 3.

The partition 11th is held between a wooden beam 16 and a second wooden beam 12. Small beam 17 has shrubbery on site 19?
It is pressed against the beam 15 to tighten the bolt 18. - A note band 2o is interposed between the partition 11a and the beam 15 to ensure airtightness at the junction to the light.

3 and 4, the sheet of the partition 11a is larger than the size of the surrounding space 7, so that when fixed, this sheet is bent and the tank is free to expand or contract.

FIG. 5 shows another embodiment of fixing the partition 11a.

In this embodiment, an angle iron 21 is joined to the partition wall 2. A wooden beam 22 extends from the lower edge of the side wall and is fixed on the outer surface of the tank 3.

A separate angle iron 23 is fixed to the outer surface of this beam 22 by bolts 24 and nuts 25.

The sheets of the partition 11a are fixed to a frame made of wooden beams 26, 27 placed on the angle irons 2.1, 23, respectively. Each beam consists of two overlapping parts, and the respective ends of the partition sheet are sandwiched between these two parts, and these may also be attached.

Another partition 28 is pasted between the bulkhead and the top of the beam 26 to ensure its retention with respect to the passage of perlite. Similarly, another partition 29 is pasted between the top of the beam 27 and the beveled top of the beam 22.

Along the lower line of the vertical side wall of the tank are wooden clasps 14,1.
By arranging the granular insulation material 9 and the thermal insulation coating 8, the granular insulation material 9 and the thermal insulation coating 8 can be combined without interrupting the thermal insulation and without subjecting it to mechanical stress that risks damaging the thermal insulation coating 8. A good connection between the two is guaranteed.

[Brief explanation of the drawing]

FIG. 1 is a schematic sectional view of a liquefied gas carrier and its tank. FIG. 2 is a plan view of the tank. FIGS. 3, 4, and 5 are diagrams illustrating a method of fixing a partition for holding a heat insulating material. 2... Partition wall, 3... Tank, 8.8b... Heat insulating material coating, 9... Granular heat insulating material, IQ... Passage, 11a
. 11b, No2a, 12b - Partition.

Claims (1)

[Claims] 1. A covering of a heat insulating material is fixed to the outer surface of the bottom of the tank of the liquefied gas carrier to insulate the bottom of the tank; installing a flexible partition made of knitted fabric in the free space; installing a pair of flexible partitions made of knitted fabric spaced apart from each other in said free space to form a chimney-like passage; and said chimney; A method for insulating a tank of a liquefied gas carrier, comprising: insulating the vertical side walls of the tank by filling said free space other than the shaped passage with particles of an insulating material. 2. A flexible intermediate partition is vertically installed in the free space to divide the aggregate of the granular heat insulating material into a plurality of separate sections.
The method described in section. 3. Insulating the tank of a liquefied gas carrier with a horizontal bottom of the tank resting on a support that provides free space under the tank bottom, vertical side walls surrounded by surrounding free space, and a ceiling. an insulating covering of cellular foam or fibers fixed to the outer surface of the bottom and ceiling of the tank; a knitted fabric fixed laterally to the lower part of the free space around the tank; a flexible partition consisting of a knitted fabric fixed longitudinally over the entire height of the free space and forming a passageway into and out of the space below the tank; A heat insulating device for a tank as described above, comprising: a granular heat insulating material filled in the free space around the tank. 4. A patent characterized in that a flexible intermediate partition is installed vertically in the free space to divide the mass of granular insulating material filling the free space into a plurality of separate sections. The method according to claim 3. 5. The method according to any one of claims 3 to 4, characterized in that the flexible partition and the intermediate partition are made of polyamide wire, carbon fiber or glass fiber. 6. The method according to any one of claims 3 to 4, characterized in that the flexible partition and the intermediate partition are made of a mesh of metal wire. 7. The particulate heat-insulating material and the heat-insulating coating are connected to each other and include a wooden beam fixed to the outer surface of the tank, and the flexible partition is fixed to the outer surface of the beam. A method according to any one of claims 3 to 6. 8. The partition comprises a horizontal wooden beam fixed along the lower edge of the side wall of the tank, and a pair of angle irons fixed respectively to the outer surface of the beam and to the ship's bulkhead; 7. A method according to any one of claims 3 to 6, characterized in that the ends are clamped in wooden frames placed on these angle irons. 9. Liquefied gases of the type comprising a self-retaining tank mounted on a support so that there is a free space below the bottom of the tank and the tank is surrounded by the free space. A liquefied gas carrier as described above, wherein the tank includes a heat insulating device according to any one of claims 3 to 8.