JPS581317B2 - Ekikagasutiyozo Aruiha Yusouyouno Dannetsuyouki - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an insulated container for the storage or transportation of liquefied gases, particularly methane or natural gas, having a layer of polyurethane foam disposed on the inner surface of a rigid outer shell.

Liquefied gases are stored in containers of this type at fairly low temperatures (e.g. liquefied methane or liquefied natural gas is stored at about -160°C at atmospheric pressure).
There is therefore a risk that the polyurethane foam layer will crack and the liquefied gas will pass through these cracks and reach the rigid shell.

Since this rigid outer shell is usually made of steel which loses its malleability at the low temperatures of the stored liquefied gas, a drop in temperature of this rigid outer shell must be prevented.

The purpose of the invention is to reduce the risk of cracks forming in this polyurethane foam layer and propagating through this layer, and in particular to reduce the risk of cracks in the polyurethane foam layer allowing liquefied gases to pass through the solid outer layer. The aim is to reduce the risk of reaching the shell.

To achieve this objective, the insulating container according to the invention is characterized in that the polyurethane foam layer is provided with a barrier made of glass fiber material and an epoxy resin system, and this barrier is arranged within the polyurethane foam layer. do.

In suitable embodiments of the invention, this barrier is parallel or substantially parallel to the rigid shell.

In order to obtain a good quality solid barrier, the glass fiber content of the barrier should be within the range of about 30-50% by weight, for example about 40%.
Convert to weight%.

In an attractive embodiment of the invention, the barrier has one or more layers of glass fiber material.

Preferably, the fiberglass material of the barrier is in the form of a cloth, such as at least two layers of cloth.

Desirably, there is a plurality of said barriers within the polyurethane foam layer, each said barrier being located at a different distance from the rigid outer shell.

Furthermore, the present invention relates to a simple and inexpensive method for producing a barrier in an insulated container according to the invention.

The method involves applying an epoxy resin composition (consisting of an epoxy resin and a curing agent) onto a polyurethane foam that has already been applied onto the inner surface of a rigid outer shell;
applying a layer of glass fiber material to the epoxy resin composition and passing a roller over the glass fiber material and the epoxy resin composition to ensure that the glass fiber material is well wetted and compacted with the epoxy resin composition; The epoxy resin is cured and finally a polyurethane foam layer is applied on the formed barrier.

Desirably, the epoxy resin composition may include a thixotropic agent.

If necessary, a softening component such as a softening type epoxy resin is included in the epoxy resin composition.

If desired, it is also possible to arrange at least one reinforcing network of glass fiber material within the polyurethane foam layer parallel or substantially parallel to the rigid outer shell.

This reinforcing network or networks contributes to the original polyurethane foam layer to stop or slow down the propagation of cracks through the polyurethane foam layer.

The invention will now be explained in more detail with reference to the figures: FIG. 1 shows a sectional view of a marine tanker equipped with tanks according to the invention;

FIG. 2 is a cross-sectional side view of subsection A of a first embodiment of a tank wall according to the invention.

FIG. 3 is a side view in cross section of a subsection A of a second embodiment of a tank wall according to the invention.

FIG. 4 is an enlarged cross-sectional view of a small portion of an embodiment of a barrier according to the invention.

In FIG. 1, a marine tanker consists of an outer hull 12, an inner hull 1, and a cargo water space 13 between the outer hull and the inner hull.

This tanker is equipped with a main deck 14 and a trunk deck 15.

The inside of the hull 1 serves as a solid outer shell for the liquefied gas container,
This rigid shell 1 is usually made of steel, for example E grade steel.

A polyurethane foam layer 2 forms the inner surface 3 of the rigid outer shell 1
placed on top.

The polyurethane foam is preferably a rigid polyurethane foam with closed cells.

Layer 2 is preferably formed by a jetting method, e.g.
It is applied by a device such as that described in British Patent Application No. 1300352 published in Japan.

The inner surface 4 of the polyurethane foam 2 is loaded with a cargo of liquefied gas 16, e.g. at a pressure of about 1 kg/cm2 and a temperature of about -1
Adapted to direct contact with liquefied natural gas at 60°C.

A vapor space 18 is present above the liquid level 17.

At least one barrier 5 is arranged within the layer 2 .

For example, in the embodiment of FIG. 2 there is one barrier 5 within the polyurethane foam layer 2, and in the embodiment of FIG. 3 there are three barriers 5 within the polyurethane foam layer 2.

This barrier 5 is shown in a simplified form in FIG.

The barrier wall 5 is made of glass fiber material 2 impregnated with epoxy resin.
It has two layers 6 and 7.

This layer 6 and 7 is preferably in the form of a cloth of glass fiber material.

This fabric has a mesh size in the range of 0.2-0.75 mm (mesh size means the maximum distance of the mesh).

Two layers 6 and 7 of glass fiber cloth contain epoxy resin and are arranged at a small distance d from each other, between which there is a thin layer 8 of epoxy resin.

This distance d should be smaller than the critical crack size so that the crack cannot propagate through the epoxy, e.g. d
is 0.2 mm or less.

It is desirable that the total thickness T of the barrier wall 5 is within the range of 0.5 to 1 mm.

Barrier 5 is applied in the following manner.

Polyurethane foam 2 is applied to the inner surface 3 of the rigid shell 1 until a certain thickness is achieved depending on the desired position of the barrier 5, for example at a distance of 200-250 mm from the inner surface 3. Let's assume.

A thin layer of an epoxy resin composition comprising an epoxy resin and a curing agent is then applied onto the unobstructed surface of the polyurethane foam, preferably by spraying.

Desirably, the epoxy resin composition includes a chickentrope agent.

If desired, a softening component and/or a softening component may be added to the epoxy resin composition.
Alternatively, a suitable curing accelerator may be included.

Then apply a glass fiber cloth.

First the glass fiber cloth 6 is applied and then, if necessary, an additional amount of the epoxy resin composition described above is applied onto this glass fiber material, preferably by spraying.

a roller is then passed over the glass fiber material and the epoxy resin composition to better wet the glass fiber material;
and compressing the contained materials.

A glass fiber cloth 7 is then applied and again a further amount of epoxy resin composition is applied.

A roller is then passed over the glass fiber material and the epoxy resin composition to better wet the glass fiber materials 6, 7 with the epoxy resin composition and compress the contained material, after which the epoxy resin is cured. let

Finally, polyurethane foam is applied on top of the barrier 5 until the desired thickness of the polyurethane foam layer 2 is achieved.

If more than one barrier 5 is required, for example three barriers as shown in FIG.
Repeat more than once.

In order to obtain a good quality and reliable barrier 5, the glass fiber content of the barrier should be within the range of about 30 to 50% by weight, for example 40%.
Convert to weight%.

Epoxy resins (also called polyepoxides) have on average one or more epoxy groups per molecule.Polyepoxides can be saturated or unsaturated, aliphatic, aromatic, or heterocyclic, and can also contain halogen atoms, hydroxyl It may also contain substituents such as groups and ether groups.

Preferred polyepoxides include novolac, resol, resorcinol, 4,4'-dividroxydiphenyl sulfone, and 2,2-bis(4-hydroxyphenyl)propane and 2,2-bis(4-hydroxyphenyl)methane. These are glycidyl polyethers of polyhydric phenols such as diphenyloalkanes and the like.

Preferred glycidyl polyethers are those of 2,2-bis(4-hydroxyphenyl)propane having an epoxy equivalent weight of 170-300; is in a solid state.

The viscosity of such glycidyl polyethers is butyl glycidyl ether, phenyl glycidyl ether, stearyl glycidyl ether, or 9 to 11 per molecule.
It can be reduced by mixing a small proportion, i.e. 5 to 20% by weight, of a liquid monoepoxide, such as a glycidyl ester of a monocarboxylic acid, such as an aliphatic monocarboxylic acid having carbon atoms of .

Other polyepoxides include polyglycidyl ethers of aliphatic polyhydroxy compounds such as ethylene glycol, glycerol, and trimethylolmethane, and of phthalic acid, terephthalic acid, tetrahydrophthalic acid, hexahydrophthalic acid, and unsaturated fatty acid polymers. obtained by epoxidation of cyclohexene derivatives such as pentaerythritol polyglycidyl ester of polycarboxylic acids such as There are polyepoxides.

Mixtures of polyepoxides as mentioned above or mixtures of polyepoxides and liquid monoepoxides can also be used.

Epoxy resins can be converted into hard resinous materials by mixing and reacting with hardeners.

Hardener systems that cure at temperatures surrounding the epoxy resin, ie 10-40°C, are desirable.

In general, well-known curing agents include; aliphatic, cycloaliphatic, heterocyclic, aromatic amines {Examples of such amines include ethylenediamine, diethylenetriamine, triethylenetetraamine, N-hydroxyethyldiethylenetriamine , N-(aminoethyl)-piperazine,
N,N-(diethyl)aminopropylamine, triethylamine, triethanolamine, benzyldimethylamine, bis(4-aminocyclohexyl)methane, bis(3-methyl-4-aminophenyl)methane, inphoronediamine, 4,4' -diaminodiphenylmethane, 4
, 4'-diaminodiphenylsulfone, m-phenylenediamine}: Monoepoxide adducts of aromatic aliphatic amines, alicyclic amines, and polyamines; monoepoxide adducts of ethylenically unsaturated fatty acids and ethylenediamine or diethylenetriamine Amides of polycarboxylic acids and excess aliphatic primary polyamines, such as aminoamides derived by the polymerization of polyamines; amino compounds such as polyepoxide adducts of excess aliphatic polyamines.

Amine compounds having at least two amino hydrogen atoms per molecule are preferred, and this type of amine compound is generally used in the curing agent in an amount that provides at least one amino hydrogen atom per epoxy group of the epoxy resin. used as.

Mixtures of amines can also be used and, if desired, curing can be accelerated by the addition of accelerators, including hydroxy compounds such as phenols, cresols and C8-C12 alkylphenols. , salicylic acid and lactic acid are preferred.

Other useful curing agents include boron trifluoride and its amine, alcohol and ether adducts.

Solvents, diluents, extenders and fillers may also be present within the epoxy resin composition.

Desirably, a thixotropic agent is included in the liquid epoxy resin composition to avoid dripping or running after application onto non-horizontal surfaces.

Useful thixotropic agents include Aerosil (Ae
rosil” and “Cab-O-sil”
), such as finely powdered silica, bentonite, especially the commercially available product ``Bentone''.
There are amine-modified bentonites such as ``One''.

The epoxy resin composition desirably includes a softening component, which is a component that improves the flexibility of the cured composition.

Softening components include epoxides such as polyglycidyl esters of unsaturated fatty acid polymers or glycidyl ethers of long-chain fatty alcohols having 10 to 18 carbon atoms per molecule, aminoamides of unsaturated fatty acid polymers, or carboxylated polydienes and polyamines. external softeners such as pine oil, coal tar, asphalt, or natural or synthetic elastomers (the term refers to softeners that do not contain epoxy or amine groups). It's okay.

Possible suitable epoxy resin compositions are described in the following reference examples.

Reference Example 1 a) Epoxy resin: 2,2 having an epoxy equivalent of 182 to 194 and a viscosity of 100 to 150 poise at 25°C
- Glycidyl polyether of bis(4-hydroxyphenyl)propane.

b) Softening component: technical diglycidyl ester of unsaturated C8 fatty acid dimer.

c) Curing agent: N-(aminoethyl)piperazine.

d) Accelerator: Phenol.

e) Chicken trove agent: “AEROSIL
)380".

The weight ratio of the above components is a:b:c:d:e=25:75
:14:5:3.

Reference Example 2 a) Epoxy resin: 2,2 having an epoxy equivalent of 182 to 194 and a viscosity of 100 to 150 poise at 25°C
- Glycidyl polyether of bis(4-hydroxyphenyl)propane.

b) Softening component: Flexiblizer, which is a softening epoxy resin with an epoxy equivalent of 700.
ilizer) 151” (UK; commercially available from Procter & Gamble Limited).

c) Curing agent: Modified cycloaliphatic amine.

d) Chickentrope agent: “AEROSIL
)380".

The weight ratio of the above components is a:b:c:d=100:50:
46:5.

To improve the natural state of the polyurethane foam layer 2, if desired, it is possible to incorporate one or more reinforcing networks of glass fiber material within the layer 2.

For example, as shown in FIG. 2, two reinforcing nets 9, 10 are placed separately within the insulation layer on the barrier 5, located according to the resistance deficiency of the insulation layer, e.g. up to 10 mm and 30 mm, respectively, from the inner surface 4. It is possible to place it at a distance.

The position of the barrier 5 from the inner surface 4 also depends on the resistance deficit of the thermal insulation layer, for example located at a distance of 50 mm from the inner surface 4.

The purpose of the reinforcement network 9 close to the inner surface 4 is to stop or slow down the propagation of any cracks that occur on the surface 4 and originate from surface cracks in the layer 2.

The second reinforcing net 10 is present as a safety measure to slow down or stop the propagation of any cracks originating from any cracks buried within the layer 2.

Reinforcement net 10 also slows down or stops any cracks penetrating through reinforcement net 9.

Furthermore, 9 was installed according to the nature of the crack initiation mechanism of layer 2.
, 10 is a very effective measure to improve the original polyurethane foam layer.

The reinforcing net 11 functions to stop or slow down the progress of all fatigue cracks generated from the solid shell 1.

The reinforcing nets 9, 10 and 11 have a mesh size ranging from 6 to 15 mm.

Barrier 5 prevents cracks in layer 2 from passing through barrier 5 and suppresses the formation of cracks below.

Furthermore, when low-temperature liquefied gas penetrates into the layer 2 through cracks existing in the layer 2, the barrier wall 5 allows this liquefied gas to further penetrate and reach the solid outer shell 1 to cool it. to prevent

In normal use of the container according to the invention, cold liquefied gas is stored in the container on the side of the inner surface 4 of the layer 2.

The inner surface 4 is therefore approximately equal to the temperature of the liquefied gas within the container.

The rigid shell 1 normally has a temperature approximately equal to the ambient temperature.

The layer 8 or the barrier 5, acting in cooperation with the barrier 5, effectively prevents the rigid shell 1 from cooling down to unacceptably low temperatures.

The rigid shell 1 can be formed by the hull of a ship or by the inner hull of a ship with a double hull.

The container can also be used for storing liquefied gas on land.

The invention has the advantage that the conventional and expensive so-called internal tanks can be dispensed with (which means that the liquefied gas is always in direct contact with the insulation material 2 during normal storage).

In the case of tanks or tankers for liquefied natural gas,
This means a significant reduction in construction costs.

However, the invention can also be used for containers with an internal tank, in which case the liquefied gas comes into direct contact with the insulation material only if the internal tank is damaged and a leak occurs.

Preferably, the barrier 5 and the screens 9, 10, 11 are parallel or substantially parallel to the rigid shell 1.

If desired, the glass fiber material of the barrier and/or reinforcing mesh can be applied, for example by jetting action, in the form of glass fiber strands.

The use of glass fiber materials within the barrier 5 is very attractive for a number of reasons.

This is because, inter alia, glass fiber materials are cheap, readily available and safe to use due to their mechanical properties at low temperatures, ie high strength and low coefficient of thermal expansion.

The use of glass fibers for the mesh 9, 10, 11 has the following advantages.

That is, glass fibers are inexpensive, readily available, and can be easily knitted or woven into nets of the required composition.

Its mechanical properties at low temperatures, namely high strength and low coefficient of thermal expansion, make it safe to use.

If desired, the glass fiber mesh 9, 10.11 can be omitted.

As an example, three barriers 5 of the type shown in detail in FIG.
An example according to FIG. 3 may be mentioned, consisting of only a glass fiber mesh and without a glass fiber mesh.

[Brief explanation of drawings]

FIG. 1 shows a sectional view of a marine tanker equipped with tanks according to the invention. FIG. 2 is a cross-sectional side view of a subsection A of a first embodiment of a tank wall according to the invention. FIG. 3 is a cross-sectional side view of a subsection A of a second embodiment of a tank wall according to the invention. FIG. 4 is an enlarged cross-sectional view of a small portion of an embodiment of a barrier according to the invention. 1... solid outer shell, 2... polyurethane foam layer, 5... barrier, 6, 7...
- Glass fiber material layer, 8... Thin layer of epoxy resin composition, 9, 10, 11... Reinforced net of glass fiber material, 13... Leg cargo space .

Claims (1)

[Claims] 1 Insulating containers intended for the storage or transport of liquefied gases, in particular liquefied natural gas, having a continuous insulating layer 2 of rigid polyurethane foam arranged on the inner surface 3 of a rigid shell 1, in which the polyurethane foam layer 2 Therein, substantially parallel to said rigid shell 1, there is a continuous barrier 5, which barrier 5 is made of glass fiber material 6, 7.
and a cured epoxy resin 8, the glass fiber being impregnated with the epoxy resin.