U.S. patent number 3,558,000 [Application Number 04/781,060] was granted by the patent office on 1971-01-26 for metallic liner system.
This patent grant is currently assigned to Institute of Gas Technology. Invention is credited to John L. Cranmer, Jr., Bertram E. Eakin, Eugene P. McCann, Eugene P. McCann.
United States Patent |
3,558,000 |
McCann , et al. |
January 26, 1971 |
METALLIC LINER SYSTEM
Abstract
A liner system for retaining liquid in a storage tank. The liner
system includes a continuous metallic liner which has sides which
are substantially coextensive with the sidewalls of the tank and a
bottom which is substantially coextensive with the floor of the
tank. Upright expansion joints, provided in the sides of the liner,
compensate for expansion and contraction of the sides in a
circumferential direction and expansion joints, provided in the
bottom of the liner, compensate for expansion and contraction in
the bottom of the liner. Hanger members are secured to the upper
portion of the tank and are resiliently mounted thereto. The upper
end of the sides of the liner engage the resiliently mounted
hangers so as to compensate for expansion and contraction of the
liner in a vertical direction.
Inventors: |
McCann; Eugene P. (Tewksbury,
MA), Eakin; Bertram E. (Naperville, IL), Cranmer, Jr.;
John L. (Chicago, IL), McCann; Eugene P. (Tewksburg,
MA), Eakin; Bertram E. (Naperville, MA) |
Assignee: |
Institute of Gas Technology
(N/A)
|
Family
ID: |
25121546 |
Appl.
No.: |
04/781,060 |
Filed: |
December 4, 1968 |
Current U.S.
Class: |
220/560.06;
220/565 |
Current CPC
Class: |
F17C
3/022 (20130101); F17C 3/005 (20130101); F17C
2223/033 (20130101); F17C 2203/0646 (20130101); F17C
2223/0161 (20130101); F17C 2260/011 (20130101); F17C
2203/0678 (20130101); F17C 2203/0639 (20130101); F17C
2221/033 (20130101); F17C 2203/0604 (20130101); F17C
2203/0333 (20130101) |
Current International
Class: |
F17C
3/02 (20060101); F17C 3/00 (20060101); B65d
025/14 () |
Field of
Search: |
;220/9A--1,9A,63,18
;62/45 ;61/.5 ;220/9,15 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Schwartz; Raphael H.
Claims
We claim:
1. A system for retaining liquid in a storage tank structure, said
system comprising a storage tank having an upper portion,
sidewalls, and a floor, continuous liner means having sides
substantially coextensive with said sidewalls and having a bottom
substantially coextensive with said floor, upright expansion joint
sections integrally joined to said sides of said liner means
compensating for circumferential expansion and contraction of said
sides, ringlike expansion joint sections integrally joined to said
bottom of said liner means compensating for expansion and
contraction of said bottom, hanger members resiliently secured to
said upper portion of said tank structure, and means secured to the
upper end portions of said sides of said liner means for engaging
said hanger members whereby said sides are suspended in a position
substantially coextensive with said sidewalls and said bottom is
maintained in a position substantially coextensive with said
floor.
2. The system of claim 1 wherein said upright expansion joint
sections in said sides extend to intersect said ringlike expansion
joint sections in said bottom so as to allow for movement of said
liner means in all directions at the intersection between said side
and said bottom.
3. The system of claim 1 wherein the upper portion of said storage
tank is above the ground and said hanger members extend outwardly
above said upper portion.
4. The system of claim 1 wherein the upper portion of said storage
tank structure is below the ground and the said hanger members are
enclosed within said storage tanks and extend downwardly from said
upper portion.
5. The system of claim 1 wherein said hanger members include spring
means for resiliently supporting said sides in a vertical direction
to compensate for vertical expansion and contraction of said sides
of said liner means.
6. The system of claim 5 wherein said upright expansion joint
sections and said ringlike expansion joint sections intersect so as
to compensate for expansion and contraction in all directions at
the intersection of said side and said bottom, thereby avoiding
excessive stresses in said bottom of said liner means.
7. The system of claim 1 wherein said liner means is a flexible
metallic material, said expansion joint means generally comprising
corrugated sections.
8. The system of claim 1 wherein the said liner means comprise a
plurality of planar substantially flexible metallic material
sections welded together in a desired configuration so as to
provide continuous liner means, and said expansion joint sections
comprises unitary corrugated metallic members united to the planar
portions of said liner means.
9. The system of claim 1 wherein said first expansion joint
sections comprise substantially upright metallic corrugations, said
second expansion joint sections integrally joined to said bottom of
said liner means, said upright corrugations extend into said
ringlike sections, and the outermost of said ringlike portions
intersect the said extending portions of said upright corrugations
in said sides.
10. The system of claim 1 wherein said hanger members comprise
support members resiliently mounted in a vertical direction to
compensate for expansion and contraction of said sides in a
vertical direction.
Description
BACKGROUND OF THE INVENTION - FIELD OF THE INVENTION
AND DESCRIPTION OF THE PRIOR ART
This invention relates to a liner system for retaining liquid in a
storage tank and it particularly relates to such a liner system
which is particularly useful in storing liquid gas at cryogenic
temperatures.
Normally the only problem that is encountered with the storage of
liquids at atmospheric pressure is the prevention of the liquid
from escaping from the container in which it is stored, a large
storage tank, for example. Problems of retaining liquid in a
storage tank are normally greater when storage is at
superatmospheric pressures, but nevertheless, significant problems
are encountered even when the liquid is stored at atmospheric
pressure. Such problems include the selection of a construction
material which will not permit the passage of the liquid by
seepage. For example, storage tanks are often constructed of
concrete and the inside of the tank must be treated so as to
prevent any loss of the liquid from the tank. Such loss of liquid
can be caused by the permeability of the material from which the
tank is constructed, by stresses imparted to the storage container
or a liner material which ultimately will cause cracks or apertures
to form, or by a combination of these two factors.
Particularly difficult problems are encountered in the storage of
large quantities of liquid gas stored at cryogenic temperatures and
at atmospheric pressures. Because of the extremely cold cryogenic
storage temperatures which must be withstood by the storage tank
material and because of the insulation which must be used in such
tank structures, separate liners for the interior of the storage
tanks are used in order to prevent the loss of the stored liquid
gas from the tank. In U.S. Pat. application Ser. No. 526,983, now
U.S. Pat. No. 3,418,812, there is shown and described an insulating
system for a storage tank for retaining liquid natural gas at
cryogenic temperatures. In this particular insulating system the
insulation is of a porous, foamed material. The innermost surface
of the material is formed of separate blocks of insulated foam
which are joined together in close proximity. Because of the
porosity of the material and because of the spaces between the
individual blocks, it is essential that a liner be used in the
interior surface of the blocks to prevent the egress of the stored
liquid from the cryogenic storage tank. A flexible liquid and gas
barrier or liner is formed as an integral part of the insulating
panels wherein such liners may be a laminated material of MYLAR
(polyethylene terephthalate fiber) having a backing of lightweight
fiber cloth and aluminum foil. Although once installed, this
material is quite satisfactory, great care must be exercised during
this installation of the laminate so as to prevent creasing of the
material, which will ultimately form pinholes therein. Such small
holes cannot be tolerated because it will cause leakage of the
liquid gas from the tank.
Because of the discussed inherent problems with the plastic
film-metal film-fibrous laminate, metal liners, such as aluminum
foil, may be used on the inside of a tank for retaining the liquid.
Although the aluminum or metallic liners are not subject to the
same difficulties encountered with the laminated type of liner,
other difficulties are encountered. The interior of the cryogenic
tanks must be capable of withstanding temperatures cycling between
extreme cold and normal temperatures. Thus, means must be provided
for compensating for expansion and contraction of the metal liner
while it is within the storage tank. If any undue stress is set up
in the material during use, cracks may develop and the liquid
natural gas can escape from within the liner. It is therefore
necessary to construct the metallic liner in such a manner that it
will avoid stresses of expansion and contraction of the liner so as
to avoid cracks forming. In prior metallic liner systems, the
expansion joints have been of complex and expensive design. For
example, it has been necessary to use a complex three-dimensional
expansion joint at the intersections between the sides and
floor.
SUMMARY OF THE INVENTION
It is therefore an important object of this invention to provide an
improved liner system for the inside of storage tanks for storing
liquids wherein the liner system avoids problems of prior art liner
systems.
It is also an object of this invention to provide an improved liner
system for the interior of storage tanks used for storing liquid
natural gas at cryogenic temperatures wherein the liner is of a
metal material so as to provide durability and ease of
construction, but at the same time substantially avoids complex
expansion joints normally required with other metal liner
systems.
It is another object of this invention to provide an improved liner
system for storing liquid natural gas at cryogenic temperatures
wherein the liner system compensates for vertical expansion and
contraction by the use of special hangers resiliently mounted to
the upper portion of the storage tank.
It is yet another object of this invention to provide an improved
liner system for storing liquid natural gas at cryogenic
temperatures wherein expansion joints are located in an upright
position along the sides of the liner and in ringlike configuration
in the bottom of the liner and the upper end of the sides of the
liner are resiliently mounted.
Further purposes and objects of this invention will appear as the
specification proceeds.
The foregoing objects are accomplished by providing a liner system
which comprises a continuous liner having sides which are
substantially coextensive with the sidewalls of the storage tank
and having a bottom which is substantially coextensive with the
floor of the storage tank, first upright expansion joint portions
in the sides of the liner to compensate for expansion and
contraction of the sides, second expansion joint portions in the
bottom of the liner to compensate for expansion and contraction of
the bottom, hanger members resiliently secured to the upper portion
of the tank, and means secured to the upper end of the sides of the
liner to engage the hanger members to compensate for vertical
expansion and contraction, whereby the sides are suspended in a
position substantially coextensive with the sidewalls and the
bottom is maintained in a position substantially coextensive with
the floor.
BRIEF DESCRIPTION OF THE DRAWINGS
Particular embodiments of the present invention are illustrated in
the accompanying drawings wherein;
FIG. 1 is a top plan cross-sectional view through a tank using our
improved liner system;
FIG. 2 is a vertical cross-sectional view taken through a tank
construction of the type shown in FIG. 1;
FIG. 3 is an enlarged fragmentary plan view showing the expansion
joints used in a liner system;
FIG. 4 is a cross-sectional view taken along the line 4-4 of FIG. 3
showing a detailed view of the expansion joints of the liner;
FIG. 5 is a detailed cross-sectional view taken along the line 5-5
of FIG. 4;
FIG. 6 is a fragmentary cross-sectional view taken along the line
6-6 of FIG. 3;
FIG. 7 is an alternate embodiment of our liner system, when the
tank structure is located entirely below the ground;
FIG. 8 is an enlarged cross-sectional view taken along the line 8-8
of FIG. 7;
FIG. 9 is an enlarged detailed view showing the construction of the
hanger member used in the embodiment of FIG. 7; and
FIG. 10 is a fragmentary detailed view taken along the line 10-10
of FIG. 8 .
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The liner system for retaining liquids in a storage tank, which
will be hereinafter described in detail, may be used in any type of
tank used for the storage of liquids. The tank structure may be
entirely above the ground, partially above the ground and partially
below the ground, or completely below the ground. The tank
structure may store liquids at atmospheric conditions, at
atmospheric pressure and cryogenic temperatures, etc. It is to be
understood, however, that the greatest utility of the liner systems
described hereinafter is in the storage of liquid gases at
cryogenic temperatures because of the various expansion joints and
resilient hangers used in our liner system to compensate for
expansion and contraction of the liner.
Liquid natural gas is commonly stored in large storage containers
at substantially atmospheric pressures but at cryogenic
temperatures. The purpose of the storage of liquid natural gas at
these conditions is to store the maximum quantity of gas in a
minimum space so that on peak demand days, such as during cold
weather, sufficient gas is available for heating purposes. It is in
such storage tanks that our liner system finds its greatest
utility.
In the accompanying drawings, two preferred embodiments of our
liner system are illustrated. In the first embodiment, shown in
FIGS. 1--6, hanger members, used for suspending the liner, project
upwardly from the upper portion or top of the tank when the tank
structure is either completely above the ground or partially above
the ground. In the embodiment of FIGS. 7--10, the tank structure is
completely below the ground so that the hanger members are located
entirely within the tank and are suspended downwardly from the top
or upper portion of the tank. Each of these embodiments will be
described in detail below.
Referring to the embodiment of FIGS. 1--6, the storage tank 10 is
located partially above the ground. In the description of this
embodiment, as well as in the description of FIGS. 7--10, the walls
of the tanks will be shown as being of solid concrete construction.
It is to be understood, however, that in the storage of liquid
natural gas at cryogenic temperatures the walls will generally
comprise an outer supporting concrete section, an outer liner which
acts as a water barrier, and multiple layers of insulating
material, such as foamed polyurethane (not shown). Specific
examples of tanks having such construction are found in U.S. Pat.
application Ser. No. 526,983, now U.S. Pat. No. 3,418,812, U.S.
Pat. application Ser. No. 527,158, now U.S. Pat. No. 3,407,606,
U.S. Pat. application Ser. No. 702,293, filed Feb. 1, 1968, and
U.S. Pat. application Ser. No. 702,471, filed Feb. 1,1968. Since
the liner system used for the retention of the liquid is the
subject of the present invention, the tank structure 10 will only
be described in general terms.
The tank 10 includes upwardly extending outer walls 12, a roof 14,
and a floor 16. The liner, generally 18, is supported inside the
tank and retains the liquid in place within the tank 10 so as to
prevent the egress thereof from the tank.
The liner 18 has a bottom 20 which is substantially coextensive
with the floor 16 of the tank 10 and also has upright sides 22
which are maintained substantially coextensive with the walls 12 of
the tank 10. The upper end of the sides 22 includes integral strap
members 24 which engage a resiliently mounted ringlike support
member 26.
Because the liner 18 is designed particularly for use with tanks
for storing liquid natural gas at cryogenic temperatures, the liner
18 is constructed to avoid stresses which may be caused by
expansion and contraction of the liner material, when the tank 10
is cycled between cryogenic temperatures for storing the liquid gas
and higher normal temperatures when the tank 10 must be repaired or
serviced. The liner 18 is designed so as to compensate for
expansion and contraction of its bottom 20 and of its sides 22,
both circumferentially and vertically.
In the preferred embodiment, the bottom 20 of the liner 18 is
formed by integrally joining planar sections, such as the central
portion 28, with a plurality of expansion joints 30 and 32. The
planar portions, such as the central portion 28 are formed by
integrally joining, as by welding, sheets of metal such as from
rolls of aluminum or steel sheeting. As shown in FIGS. 3 and 5, the
expansion joints 30 are integrally joined, as by welding, to the
planar portions of the bottom 20. The expansion joints 30 generally
comprise thermal expansion metal which has the general
configuration of corrugated sections. The corrugated expansion
joints 30 expand when the temperature in the tank is raised and
contract when the temperature is lowered, so that regardless of the
temperature, the bottom 20 of the liner 18 remains substantially
coextensive at all times with the floor 16 of the tank 10 without
undue stresses being set up in the liner bottom. Preferably, a
multiplicity of expansion joints 30 are provided in the bottom 20.
The bottom expansion joints are preferably ringlike and
substantially concentric with each other such as shown in FIG.
1.
The sides 22 of the liner 18 are maintained in close proximity to
the walls 12 of the tank 10 and generally comprise a plurality of
substantially planar upright sections 32 which are spaced apart by
a plurality of upright expansion joints 34. The expansion joints 34
extend from the upper edge of the liner sides 22 downwardly to the
intersection between the bottom 20 and the sides 22. Preferably,
the lower or terminal portion of the upright joints 34 is brought
into intersecting, united relationship with the outermost ringlike
expansion joint 36 in the bottom 20. The intersection between the
upright joints 34 and the outermost joint 36 provides a far simpler
construction than structures used in the prior art, which involve
using three dimensional expansion joints for avoiding excessive
stresses at the intersection of a vertical liner section with the
floor liner section. The intersection between the upright expansion
joint 34 and the floor joint 36 is accomplished by a V-shaped
intersection between these joints 34. As shown clearly in FIGS. 3
and 5, the planar sections 32 are joined to the upright expansion
joint section 34 by suitable means, as by welding at the joint 38.
A plurality of metal sheet sections may be welded or joined
together by other suitable means to form the planar sections 32 in
a manner similar to that used for forming the central portion 28 of
the bottom 20 of the liner 18. The upright expansion joints 34
compensate for circumferential expansion and contraction of the
sides of the liner 22.
The resiliently mounted support member 26 is desirably a ringlike
structure which is rigidly joined at a plurality of spaced
locations to upright rods or tubes 40. The hanger members 42 are
mounted on the upper surface of the roof 14 of the tank 10. The
hangers 42 are located in direct alignment above the support member
26. The support member 26 is constructed so as to be in close
proximity to the walls 12 of the tank 10 and so as to provide
assurance that the sides 22 of the liner 18 remain substantially
coextensive with the tank walls 12 at all times.
The hanger members 42 each include a flange portion 44 which is
rigidly secured on the upper surface of the roof 14. An outer
tubular member 46 is threadably secured to the threaded portion of
the flange 44 and extends upwardly therefrom. The upper end of the
tube 46 is closed by a cap 48 which is threadably secured to the
upper end of the tube 46. The tubular member 46 defines a housing
for a compression spring 50 which is located in the annular space
between an upright rod or tube 40 and the outer tube 46. A collar
52 is removably secured to the upper end of the upright tube 40 by
means of a pin 54. The upper end of the compression spring 50
engages the collar 52 and the lower end of the compression spring
50 engages the upper end of the flange 44.
The hanger members 42 thereby provide resilient support for the
support member 26 and thereby for the liner 18. The weight of the
liner 18 and the weight of the liquid contained within the liner 18
cause downward movement of the support member 26. This downward
movement compresses the spring 50 because the spring 50 is trapped
between the collar 52 and the flange 44. The compression springs 50
provide resilient mounting of the liner 18 and thus compensate for
vertical expansion and contraction of the sides 22 to accommodate
for height variation depending upon the depth of the liquid
contained within the liner 18, without creating any significant
stresses in the liner material which could ultimately cause breaks
to form therein. Preferably a packing gland 56 is interposed
between the flange 44 and the outer surface of the upright tube 40
so as to prevent gas leakage from the tank storage area.
The compression spring 50 is designed so as to allow for the
contraction of the liner material. Thus, with the proper spring
constant, when the wall material cools and contracts or heats and
expands, excessive stresses will not be set up in the material
which can ultimately lead to failure of the liner. The compression
spring has a load due to the weight of the liner material itself
and due to the weight of the liquid contained therein, and it also
has a load due to the contraction of the wall material. The spring
constant is chosen so that the force required to compress the
spring an amount necessary to allow for the contraction of the wall
material is only a relatively small percentage of the proportional
stress limit of the material. Since the loading due to contraction
is only a small percentage of the loading due to the material
weight, the compression spring is relatively long. In order to keep
the length of the total assembly within reasonable limits, it is
desirable to precompress the spring to about 90--95 percent of the
material weight load before it is installed.
Referring now to the embodiment of FIGS. 7--10, the tank 70 shown
therein is located entirely below the ground so that the upwardly
projecting hanger members 42 of the embodiment of FIGS. 1--6 cannot
be used. The essential differences between the embodiment of FIGS.
1--6 and the embodiment of FIGS. 7--10 lie in the construction of
the hanger members, although it is to be understood that the
principle of both liner systems is substantially the same. The
construction of the liner 72 in the tank 70 is substantially the
same as liner 18 for the tank 10. The only difference between the
embodiment of FIGS. 7--10 and of FIGS. 1--6 is that the liner 72
uses a different type of strap member 74 for engaging the ringlike
support 76, which is resiliently mounted from a plurality of hanger
members 78. It is noted that each strap 74 is elongated and
constitutes a continuation of the liner material which is folded
upon itself and welded in place over the ringlike support 76.
A peripheral beam 80 is rigidly secured to the underside of the
roof 82 of the tank 70 by use of bolts 84. The underside of the
peripheral ringlike beam 80 has a plurality of downwardly extending
tubes or rods 86 projecting therefrom. These tubes are equally
spaced at a plurality of locations therearound. The lower end of
the tube 86 includes a bearing plate 88 which is rigidly secured
thereto by suitable means, as by welding. An outer tubular member
or housing 90 is slidably mounted around the downwardly extending
tube 86. An upper bearing plate 92 is threadably secured to the
upper end of the tubular housing 90. A compression spring 94 is
interposed between the bearing plate 92 and the bearing plate 88
and is contained within the annular space between the tubular
member 86 and the outer housing 90.
The lower end of the tubular housing 90 is rigidly secured, as by
welding, to the ringlike support member 76 around which the strap
members 74 are passed to provide support for the liner 72. It is
thus seen that the compression springs 94 provide for the same type
of support for the liner 72 as is provided by the compression
springs 50 for the liner 18. As the liquid depth is varied within
the liner 72, less load is applied to the resiliently mounted
support 76 and the compression springs 94 tend to lift the support
76 upwardly through the outer housing 90 and the bearing plate 92.
The hanger members 78 thus compensate for vertical expansion and
contraction of the sides of the liner 72.
It is seen from the foregoing description that we have provided a
liner system of relatively simple construction which compensates
for expansion and contraction thereof due to great variations in
temperature. The construction provides for expansion joints in the
floor for radial expansion and contraction. Both the embodiments
also provide for circumferential expansion and contraction of the
sides, and provide for vertical expansion and contraction of the
sides. All this is accomplished in a relatively simple, but highly
effective manner. The same basic principles are used in the support
of the liner regardless of whether the tank structure is contained
entirely above the ground or partially above the ground and
partially below the ground. The only variation is in the specific
design of the hanger members which are supported by the roof of the
tank for the purpose of vertically supporting the liner sides in a
resilient manner.
* * * * *