U.S. patent number 3,682,346 [Application Number 05/021,574] was granted by the patent office on 1972-08-08 for liquid cryogen storage tank for shore, ship or barge.
Invention is credited to Eugene L. Sterrett.
United States Patent |
3,682,346 |
Sterrett |
August 8, 1972 |
LIQUID CRYOGEN STORAGE TANK FOR SHORE, SHIP OR BARGE
Abstract
A container for cryogenic fluids is described wherein a first
layer of insulating blocks completely lines the interior of the
container and at least a portion of one face of each block is
bonded to the interior of the container by a cryogenic adhesive.
The sides of the insulating blocks have a contractable insulating
material completely surrounding them. At least a second layer of
insulating blocks is bonded to the first layer of blocks; at least
about 2 percent of the areas common to the faces of the first and
second layers of blocks are bonded. The sides of the second layer
of blocks are surrounded by a contractable insulating material. The
face areas common to the blocks that are not bonded preferably have
a substantially non-friction material attached thereto. The layers
of blocks are arranged so that there are no direct heat paths to
the walls of the container. A membrane of Invar completely covers
the interior of the container and is sufficiently bonded to the
interior layer of blocks to support the Invar. Optionally, another
layer of insulating blocks can be bonded to the Invar and then
another layer of Invar bonded to this layer of blocks--this is
preferred for containers useful in transporting cryogen. Where the
container is stationary, the top of the container does not have to
have the membrane of Invar.
Inventors: |
Sterrett; Eugene L. (Hacienda
Heights, CA) |
Family
ID: |
26694850 |
Appl.
No.: |
05/021,574 |
Filed: |
March 23, 1970 |
Current U.S.
Class: |
220/562; 114/74A;
220/901; 220/560.04 |
Current CPC
Class: |
B65D
81/3811 (20130101); F17C 13/001 (20130101); F17C
2203/032 (20130101); F17C 2223/033 (20130101); F17C
2270/0105 (20130101); Y10T 428/249985 (20150401); F17C
2270/011 (20130101); F17C 2203/0639 (20130101); F17C
2203/0678 (20130101); F17C 2221/033 (20130101); F17C
2260/033 (20130101); F17C 2203/066 (20130101); F17C
2203/035 (20130101); F17C 2223/0161 (20130101); Y10T
428/249981 (20150401); Y10S 220/901 (20130101) |
Current International
Class: |
B65D
81/38 (20060101); F17C 13/00 (20060101); B65d
025/18 () |
Field of
Search: |
;220/9LG,9F,10,9A
;114/74A |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Wood, Jr.; M. Henson
Assistant Examiner: Culp, Jr.; Thomas C.
Claims
What is claimed is:
1. a container for the confinement of cryogenic fluids
comprising:
1. an outer shell,
2. a first layer of a plurality of insulating blocks lining the
interior of the shell, at least about 2 percent of the face area of
one side of each block is bonded with a cryogenic adhesive to the
interior of the shell and the blocks arranged side by side, the
blocks having sufficient space between the sides of the blocks to
permit expansion and contraction of the blocks over the operating
temperature range of the container without shearing the blocks from
the interior of the shell,
3. a contractable and expandable insulating material completely
surrounding each block and filling at least a portion of the space
between the sides of the blocks,
4. at least a second layer of a plurality of insulating blocks
lining the interior of the first layer of blocks and arranged over
said first layer so that no direct path of heat loss is permitted
to the shell of the container, the blocks arranged side by side as
in (2) and at least 2 percent of the face area of each block
contiguous to the face of the block within the first layer are
bonded with a cryogenic adhesive to the first layer of blocks,
5. a contractable and expandable insulating material surrounding
the second layer of insulating blocks and filling at least a
portion of the space between the blocks,
6. a membrane of Invar lining at least the walls and the bottom of
the interior of the second layer of the insulating blocks and
attached thereto by bonding with a cryogenic adhesive at least a
sufficient portion of the area common to the blocks and the Invar
to support the Invar.
2. The container of claim 1 wherein at least three layers of
insulating blocks are attached to the interior of the shell.
3. The container of claim 2 wherein a membrane of Invar is
sandwiched between the second and third layers and is bonded to
portions of each insulating block face common to the Invar.
4. The container of claim 1 wherein the contractable and expandable
insulating material completely surrounds each insulating block and
is flush with the sides of the blocks.
5. The container of claim 1 wherein the insulating block is either
foamed polyvinyl chloride, foamed glass, or foamed urethane.
6. The container of claim 1 wherein the insulating blocks closer to
the Invar are smaller in area than the first layer of insulating
blocks.
7. The container of claim 1 wherein the operating temperature range
of the container is about 72.degree. F. to about -350.degree.
F.
8. The container of claim 1 wherein the operating temperature range
of the container is about 72.degree. F. to about -260.degree.
F.
9. The container of claim 1 wherein the Invar completely lines the
interior of the second layer of insulating blocks.
10. A container for the confinement of cryogenic fluids
comprising:
1. a shell
2. a first layer of insulating blocks completely lining the
interior wall of the shell, at least a portion of one face of each
block bonded by a cryogenic adhesive to the interior of the shell
and the blocks arranged side by side, the blocks having sufficient
space between them to permit expansion and contraction of the
blocks over a temperature range of about 72.degree. F. to about
-350.degree. F. without shearing the blocks from the interior
wall,
3. a second layer of insulating blocks completely lining the
interior of the first layer of insulating blocks and arranged over
said first layer so that no direct path of heat loss is permitted
to the shell of the container, the blocks arranged side by side
with sufficient space as defined in (2),
4. a third layer of insulating blocks completely lining the
interior of the second layer of insulating blocks and arranged over
said second layer of insulating blocks so that no direct path of
heat loss is permitted to the shell of the container, the blocks
arranged side by side with sufficient space as defined in (2),
5. a contractable and expandable insulating material completely
surrounding each block within the first, second, and third layers
of blocks and filling at least a portion of the space between the
blocks within these layers,
6. at least about 2 percent of the face areas of each block within
the first, second, and third layers of blocks that are common to
each other are bonded with a cryogenic adhesive, and
7. a membrane of Invar completely lining the interior of the third
layer of the insulating blocks and attached thereto by bonding with
a cryogenic adhesive at least a sufficient portion of the area
common to the third layer of blocks and the Invar to support the
Invar.
11. The container of claim 10 wherein the operating temperature
range is about 72.degree. F. to about -260.degree. F.
12. The container of claim 10 wherein the contractable and
expandable insulating material that completely surrounds the blocks
is flush with the sides of the blocks.
13. The container of claim 10 wherein the insulating blocks are
composed of either polyvinyl chloride, foam glass or foam
urethane.
14. The container of claim 10 wherein the insulating blocks closest
to the Invar are smaller in area than the insulating blocks adhered
to the interior of the shell.
15. The container of claim 10 wherein a membrane of Invar is
sandwiched between the second and third layers of insulating blocks
and at least 2 percent of the areas common to each face of the
blocks and Invar are bonded with a cryogenic adhesive.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to internally insulated containers for the
confinement of cryogenic fluids and more specifically to a
load-bearing insulating material that does not permit direct heat
path to the container walls. On the interior of the insulating
blocks, a membrane of Invar is bonded to the insulating blocks. The
container can be used to transport cryogen or contain cryogen in a
stationary position.
2. Description of the Prior Art
U.S. Pat. No. 2,859,895 to Beckwith teaches a method of insulating
the shell of a methane storage tank. The insulation is defined as
"a wall made of a multiplicity of separate blocks or strips or
panels of a light, permeable, preferably straight-grained, natural
or synthetic wood-like material having a high insulating factor."
The blocks are mounted on the walls by glue and are staggered so
that the glue planes are not uninterrupted.
U.S. Pat. No. 3,106,307 to Morrison teaches a combination of a
layer of air-laden polystyrene protecting an inner layer of
freon-laden polyurethane.
U.S. Pat. No. 3,136,135 to Rigby et al. teaches the use of foamed
polyvinyl chloride or foamed polystyrene to insulate a tanker for
shipping liquefied natural gas.
U.S. Pat. No. 3,367,492 to Pratt et al. teaches insulating the
inner wall of an LNG tanker with foam encapsulated in fiberglass
reinforced urethane material. The encapsulated foam is partitioned
to form blocks and the blocks attached to the wall by mechanical
means. The blocks are joined together by a joint assembly fastened
to the blocks with grooves and adhesive.
U.S. Pat. No. 3,367,527 to Darlington teaches a cryogenic container
internally insulated with moisture-free insulating blocks (blocks
can be encapsulated in a plastic material, e.g., polyurethane). The
blocks lie in juxtaposition with adjoining faces abutting. One face
of the block is secured to the interior of the shell and the
remaining faces are independent of the adjoining insulating
blocks.
SUMMARY OF THE INVENTION
Applicant has discovered a novel method of designing a cryogen tank
that provides for differential expansion between insulating
materials and at the same time supports an interior layer of Invar.
This is accomplished by lining the inside of the container
with:
1. a first layer of insulating blocks, one face of the blocks
bonded to the interior wall of the container and the blocks
arranged side by side, the blocks having sufficient space between
them to provide for expansion and contraction over a temperature
range of about 72.degree. to about - 350.degree. without shearing
the blocks from the wall,
2. a contractable and expandable insulating material filling at
least a portion of the space between the sides of the blocks,
3. at least a second layer of insulating blocks arranged over said
first layer so that no direct paths of heat loss are permitted to
the shell of the container, the blocks arranged side by side and
spaced as in (1),
4. a contractable and expandable insulating material filling at
least a portion of the space between the second layer of
blocks,
5. the faces common to the blocks within the first and second
layers bonded with a cryogenic adhesive on at least 2% of the area
common to the faces, and
6. a membrane of Invar completely lining the exposed face of the
second layer of blocks and attached thereto by adhering with a
cryogenic adhesive at least 2 percent of the area common to the
blocks and the Invar.
The insulating blocks are self-supporting. Differential expansion
of the insulating blocks is accommodated by the contractable and
expandable insulating material placed between the sides of the
blocks. The Invar is supported by the insulating blocks.
BRIEF DESCRIPTION OF THE FIGURES
FIG. 1 is a cross section of the container wall with layers of
insulating blocks and a layer of Invar.
FIG. 2 is a side view of the insulating blocks showing how the
blocks overlap other insulating blocks so that no direct paths of
heat are permitted to the container wall.
FIG. 3 illustrates a preferred way of bonding layers of Invar
together.
FIG. 4 is a cross sectional view of a preferred container wherein
one layer of Invar is sandwiched between insulating blocks and then
a final layer of Invar is attached to the exposed layer of
insulating blocks.
FIG. 1 is a cross section of the container wall. Wall 2 can be
steel, concrete or like material. Such is representative of the
container wall of, for instance, an ocean-going tanker to transport
LNG (liquefied natural gas). Interior of the wall 4 is connected to
the face of the first layer of insulating blocks 6 by cryogenic
adhesive bond 5. Space 8 between blocks 6 is filled with a
contractable and expandable insulating material such as sponge
urethane, strips of fiberglass, or like materials. The second layer
of insulating blocks 10 is attached to the first layer of
insulating blocks 6 by cryogenic adhesive bond 5. Also, the spaces
8 between the second layer of insulating blocks 10 are filled with
the insulating material. The areas common to the faces between the
blocks that are not bonded can be coated with a substantially
nonfriction material at 7, e.g., Teflon or like material, to
prevent abrasion between the blocks when thermal expansion and
contraction moves the blocks. Optionally, a third layer of
insulating blocks 12 are attached to the second layer of insulating
blocks 10, via bonding at 5 the faces common to the blocks. Again,
the space 8 between insulating blocks 12 is filled with the
insulating material. The layers of blocks 6, 10, and 12 are placed
such that no direct heat passes are permitted to wall 4 of the
container. Attached to the exposed face of insulating blocks 12 is
a membrane or layer of Invar 14. The membrane of Invar 14 is
attached at 5 to the inside of insulating blocks 12 by a cryogenic
adhesive. Invar 14 can be connected to other layers of Invar by
overlapping as shown at 20. The overlap of Invar is attached to the
underlap of Invar by a cryogenic adhesive. Suction cups 16 can be
previously countersunk flush to the face of insulation blocks 12
and bonded to the blocks, the cups useful to hold the Invar in
place until the adhesive cures.
Optionally, the Invar can be attached to other layers of Invar by
folding back about one-half inch at the edge of each Invar sheet
and then locking these 180.degree. folds together as shown in FIG.
3. Locking of the folds can be effected by cryogenic adhesive or by
mechanical means.
FIG. 2 is an inside view of the insulating blocks before the Invar
is attached to the exposed face of insulating blocks 12. FIG. 2
shows that the insulating blocks are arranged side by side and that
they have space 8 between the sides of the blocks. The third layer
of insulating blocks 12 is staggered over the second layer of
insulating blocks 10 and the latter blocks staggered over the first
layer of insulating blocks 6 such that no direct pass of heat leak
is permitted to wall 4. Fastening means such as wood pegs 18 in
FIG. 1 can be used to adjoin or fasten the faces of insulating
blocks to each other and hold the blocks in place during the curing
of the cryogenic adhesive. A preferred embodiment of the invention
is that blocks 12 are smaller in area than blocks 10 and the latter
blocks are smaller in area than blocks 6.
FIG. 4 represents a preferred embodiment of the invention. A first
layer 6, second layer 10, and third layer 12 of insulation blocks
and a membrane of Invar 14 are arranged as in FIG. 1, except that
an additional membrane of Invar 15 is sandwiched between layer 10
and layer 12. The faces of insulation blocks 10 and 12 that are
common to the Invar are bonded to the sandwiched Invar layer 15.
This embodiments is preferred when the container is used to
transport LNG, e.g., a ship.
BRIEF DESCRIPTION OF PREFERRED EMBODIMENTS
Applicant's invention teaches a novel method of cryogenic tank
fabrication. This method provides a means for differential
expansion between insulating blocks and also provides a means of
fastening the insulating blocks to the inside of the container. The
insulating blocks are arranged in such a manner to prevent direct
pass of heat leaks to the container wall. Invar (36 percent nickel
and 64 percent steel) or a like material, completely covers the
interior of container when the container is used to transport
cryogen. When the container is a stationary insulation, the
container top may only need the insulation, i.e., the membrane of
Invar is not necessary. The insulating blocks support the
Invar.
The insulating blocks can be made of any material which has good
insulating characteristics and which has a relatively low
temperature coefficient of expansion. Examples of preferred
materials include foamed polyvinyl chloride (this material has a
low conductivity of heat and has high strength), foamed glass,
foamed urethane, encapsulated perlite, and like materials. The
insulating material may be encapsulated by a protective covering,
e.g., plywood, etc. The insulating material must be absolutely free
of water vapor. Optionally, a positive pressure of an inert gas
(the gas is dehydrated) can be maintained within the space
containing the insulating blocks.
The insulating blocks are adhered or bonded to the inside wall of
the container, to adjoining insulating blocks and to the Invar by a
cryogenic adhesive. Preferably, the adhesive has a high tensile
strength, e.g. 8,000 psi and higher at the cryogenic temperature.
Examples of useful cryogenic adhesives include (1) a two part
polyurethane mixture marketed by the Narmco Division of the
Whittaker Corp. and composed of 90 percent by weight formulation
No. 7343 and 10 percent by weight of formulation No. 7139; (2) a
two part polyester mixture marketed by DuPont composed of 97
percent by volume formulation No. 96990 and 3 percent by volume
formulation No. RC805; (3) a two part polyurethane mixture marketed
by the CPR Division of the Upjohn Company composed 90 percent by
weight formulation CPR 2050 and 10 percent by weight formulation
MOCA; (4) formula No. G207 marketed by Goodyear, and like
materials.
The areas between the container walls and the faces of the
insulation blocks and between the faces of the blocks that need be
bonded are only the areas needed to support the insulation blocks
and the Invar. All of the area, i.e., 100 percent, is desirably not
bonded since such would not permit much freedom of movement during
thermal expansion and contraction. It is preferred that at least
about 2 percent of the areas common to the interior wall and first
layer of blocks and to the layers of blocks and to the insulating
blocks and Invar be bonded. Also, each block must be bonded to the
wall of the container and thereafter each block bonded to at least
one block it overlays.
The insulating blocks are attached one to the other by the
cryogenic adhesive. Sufficient bonding is needed to transfer the
load (weight of Invar and blocks) from the outer-tank to the
inner-tank.
The spaces between the blocks are filled with contractable and
expandable insulation material, e.g., sponged urethane, fiberglass,
etc. Such accommodates the differential expansion of the blocks.
The space should be sufficiently wide to permit expansion and
contraction of the blocks over the operating temperature range of
the container without shearing the blocks from the walls of the
container or other blocks. Examples of temperature ranges include
ambient temperature (e.g., 72.degree. F.) to about -350.degree. F.
and preferably about 72.degree. F. to about -320.degree. F. and
more preferably about 72.degree. F. to about -260.degree. F. at
atmospheric pressure.
The blocks are arranged one over the other, or the layers of blocks
staggered so that no direct pass of heat is permitted in case of a
leak. That is, the second layer of blocks is placed onto the first
layer of insulating blocks is an "offset pattern" such that the
joints do not line up with each other, see FIG. 2. Also, each block
within the second layer is bonded to at least one block in the
first layer of insulating blocks. As mentioned earlier, at least
about 2 percent of each face area of the blocks is bonded. The
non-bonded surfaces of the face areas common to the insulating
blocks can be coated with a substantially non-friction material,
e.g., Teflon film or like material to prevent abrasion between the
layers of insulating blocks as they expand and contract due to
temperature changes, i.e., as the blocks move relative to each
other.
After the insulating blocks are attached, the exposed face of the
last layer of insulating block is covered with a membrane of Invar.
Also, a membrane of Invar may be sandwiched between the insulating
blocks. The Invar is preferably about 10 to about 35 mils thick.
The Invar may be joined together by overlapping one Invar layer
over another layer of Invar and then bonding the contiguous surface
with a cryogenic adhesive. Besides lapping the joints of Invar and
then bonding them, it may be advantageous to use mechanical means
to join the Invar. Such can be accomplished by folding back about
one-half inch on the edge of each Invar sheet and then locking the
180.degree. folds together as shown in FIG. 3. The locking can be
effected by mechanical means, or a cryogenic adhesive or any
suitable means. The Invar can be securely held in position by
suction cups countersunk into the insulating blocks and flush with
the insulating blocks, the cups supporting the Invar while the
cryogenic adhesive is curing. Only a portion of the area contiguous
to the layer of insulating blocks and Invar is coated with the
adhesive, the minimum area being that which is needed to support
the Invar. At least about 2 percent of the Invar area is
sufficient.
The insulating blocks can be joined with wood pegs. Also, the
insulating blocks contiguous to the interior of the tank can be
joined with wood pegs, e.g., such pegs may be previously bonded to
the interior of the wall. Such is helpful in temporarily supporting
the blocks while the adhesive cures.
The container can be any building material which provides
sufficient structural strength to contain the cryogenic material.
Examples include reinforced concrete, steel, alloys, synthetic
materials such as plastics, etc. Reinforced concrete is the
preferred construction material for barges since the weight of the
concrete provides ballast. Also, the barge can substitute for shore
storage and the cryogen replenished merely by shuttling barges.
A minimum of two layers of the insulating blocks is recommended
with this invention. However, three layers is preferred and more
than three layers are useful for certain cases. It is evident that
the temperature differential between the outside of the container
and cryogen will govern the number of insulating block layers as
well as the thickness of the insulating blocks. Preferably, the
insulating blocks closer to the cryogen are smaller in area than
the blocks contiguous to the shell of the container--such a design
will permit a larger degree of thermal expansion and contraction
next to the cryogen. The larger insulating blocks, i.e., the blocks
contiguous to the shell of the container, will still have
sufficient capability to expand and contract although the degree of
expansion and contraction will not be as great as the insulating
blocks closer to the cryogen. Preferably the intermediate layer of
blocks has an area intermediate in size of the smaller and larger
area blocks. This is preferred since the insulating blocks closer
to the cryogen will necessarily have a larger degree of expansion
and contraction than the insulating blocks removed from the
cryogen.
Where the container is to be used on a ship, it is preferred that a
membrane of Invar be sandwiched between the layers of insulation
blocks and then a membrane of Invar completely line the exposed
face of the first layer of insulating blocks. For example, FIG. 4
is a preferred design.
It is intended that all equivalents obvious to those skilled in the
art be incorporated within the scope of the invention as defined
within the specification and appended claims.
* * * * *