US3107498A

US3107498A - Portable insulated storage tanks and valve means

Info

Publication number: US3107498A
Authority: US
Inventors: Elmer S Messer
Original assignee: Conch International Methane Ltd
Current assignee: Conch International Methane Ltd
Priority date: 1961-03-13
Filing date: 1961-03-13
Publication date: 1963-10-22
Anticipated expiration: 1980-10-22

Description

E. s. MESSER 3,107,498 PORTABLE INSULATED STORAGE TANKS AND VALVE MEANS 2 Sheets-Sheet l Oct. 22, 1963 Filed March 13 ,1961

FIG. l

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- o a 7 P o l// INVENTOR. Elmer S. Messer 1 9M A'r'i'orneqs Oct. 22, 1963 E. s. MESSER 3,107,498

PORTABLE INSULATED STORAGE TANKS AND VALVE MEANS Filed March 13 1961 2 Sheets-Sheet 2 INVENTOR. Elmer S. Messer Y A KW United States Patent 3,107,498 PQRTABLE INSULATED STORAGE TANKS AND VALVE MEANS Elmer S. Messer, Tulsa, can, assignor to Conch international Methane Limited, Nassau, Bahamas, :1 corporation of the Bahamas Filed Mar. 13, 1961, Ser. No. 95,103 18 (Claims. (Cl. 62-45) This invention relates to the storage and transportation of a liquid having a temperature difi'ering widely from the ambient temperature and it relates more particularly to a portable container of relatively small capacity for use in the storage and transportation of such liquefied gas and to means employed in combination therewith for support of the container and for control of liquid flowing into and out of the container.

The invention will be described with reference to containers or tanks for the storage and transportation of natural gas in a liquefied state but it will be understood that the concepts of this invention will have application also to containers or tanks for the storage and transportation of other liquids and liquefied gases, such as liquefied nitrogen, oxygen, air and the like. The containers of this invention are addressed to facilities substantially larger than the small tanks used for commercial distribution of L.P.G. gas but smaller than the tanks of 30 ,000 to 60,000 barrels capacity used in transportation of such liquefied gases by specially constructed tankers.

A number of advantages can be made available by the use of containers of smaller capacity by comparison with large tanks of the type heretofore employed in the storage and overwater transportation of natural gas in a liquefied state from a source of plentiful supply to an area where a deficiency exists, at which point the liquefied 4 gas is reconverted to the gaseous state for use.

Such tanks of smaller capacity can be constructed independently of the ship for use with any type of ship in the transportation of the liquefied gas as distinguished from the need specially to construct a ship with an insulated hold in which tanks of large capacity are installed to become a permanent part of the ship and thereby to limit the use of the ship.

Such tanks of smaller capacity eliminate the necessity to provide the ship with fluid displacement means and piping for introduction of the liquid into the tank for storage and transportation or for discharge of the liquid from the tank to storage facilities on shore or at the station of use.

The portable tanks can be used for land storage as well as ship storage thereby to eliminate the need for piping for the over-land transportation of the liquid and thereby to minimize the need for the construction of additional land storage facilities for housing the liquid upon delivery.

Such portable tanks of smaller dimension can be transported over land by rail, truck or the like thereby to make such liquefied natural gas available inland as well as near shore facilities and thereby to eliminate the need for transmission lines for delivery of the gas in a liquefied or gaseous state. I

otherwise occasioned by pump failures or failures of one or more fluid handling or storage means.

Thus it is an object of this invention to produce a portable tank or container for use in the storage and/ or transportation of a liquid having a temperature differing widely from the ambient temperature and it is a related object to produce an insulated tank of the type described for the storage and/or transportation of a liquefied gas such as liquefied natural gas.

More specifically, it is an object of this invention to produce a tank of the type described which can be eco nomically and efliciently constructed'of readily available and low cost materials; which is structurally strong and dimensionally stable to enable stacking for most efficie-nt use-of space available for storage and transportation; which can be stacked into a compact pile for disposition into a hold space of a ship 'for over-water transportation or for land storage at the site of use or for over land transportation to stations of use; which is insulated to minimize heat loss to the liquid contained therein; which embodies valve means for enabling charging or discharging of the liquid without'the need for a self-contained pump; which can be handled by conventional cargo handling equipment for loading and unloading onto carrier means for transportation; which embodies safety means for the release of excessive pressures which might be built up within the tank, and which provides for rapid and uniform delivery of liquid from within the tank during discharge.

These and other objects and advantages of this inventionwill hereinafter appear and for purposes of illustration, but not of limitation, embodiments of the invention are shown in the accompanying drawings, in which ,FIG. 1 is a schematic sectional elevational view of one modification of a tank embodying the features of this invention;

FIG. 2 is a sectional view through a wall of the tank of FIG. 1 showing the construction thereof;

FIG. 3 is a perspective view of a support element adapted for use with a tank ofthe type shown in FIG. 1;

FIG. 4 is a schema=ticsectional view illustrating the use of the support elements of FIG. 3 with'a tank of FIG. 1; 1 i

' FIG. 5 is a schematic sectional elevational view of a further modification in a tank embodying the features of this invention, and

The ability to transport and to make use of such tanks equipment minimizes the interferences with operations FIG. 6 is a sectional view of a valve assembly which may be employed in the tanks of this invention,

Referring now to FIG. 1, a tank embodying the features of this invention is constructed with an inner shell 10 and an outer shell 12 with the space in between occupied by a thermal insulating structure '14 to minimize heat loss through the walls of the tank. The inner shell 10, which is adapted to be directly in contact with the liquid :16, is formed of a substantially continuous membrane or sheet of a fluid and vapor impervious material which does not experience excessive loss in strength or ductility when exposed to the cold temperature of the liquid. For this purpose, use can be made of such materials as aluminum and alloys of aluminum, stainless or the like high nickel or austenitic steels, copper and brass, or some of the synthetic plastics, with or without glass fiber reinforcement, such .as polyesters, polytetrafluoroethylene, etc.

The outer shell 12, which is not exposed to the cold of the liquid, can be constructed of conventional, prefbe drawn. The construction described is particularly Well adapted to make use of a type of insulation hereinafter referred to as a multiple layer vacuum type, shown in H6. 2, consisting of alternate layers of glass fiber mats or fabrics 17 and thin reflective sheets 18 of metal, such as aluminum, wherein the alternating layers are built up to the desired thickness and evacuated to produce a relatively compact insulation having a high degree of structural strength. An insulation layer suitable for use in a tank of the type described and characterized by negligible heat transfer through the wall of the tank can be secured in a thickness of about 3 inches built up upon evacuation of a structure formed of about 120 layers of 0.005 ,inch glass fiber mat and 0.003 inch aluminum reflective sheets. It will be understood that the foregoing is given only by way of illustration and not by way of limitation since the number of layers can vary widely as can the size or dimension of the glass fiber mats and the reflective metal sheets. When the inner and outer shells and 12 are fluid and vapor impervious, the vacuum can be drawn in the insulation layer through a valve 20 in the outer shell. When one or the other of the shells is not fluid and vapor impervious, then it will be desirable to enclose the layers in a casing or enclosure to enable vacuum to be drawn thereon.

For stabilization of the tank walls, the tank is provided with a structural member extending throughout the length thereof, as illustrated by the rigid tubular member 22 to which rings 24 are secured in longitudinally spaced apart portions for support of spiders 26 which extend outwardly to the inner shell for attachment to bracing rings or members 28 fixed, as by welding or other attachment means, to the inner surface of the inner shell in longitudinally spaced apart portions.

The tubular supporting column 22 is formed with a plurality of openings 30 along the length thereof to provide passages communicating the interior of the tank with the interior of the column for the escape of liquids or vapors that may be trapped, as by drainage back into the tank.

Near the exit portion of the tubular member, the tank is provided with a discharge line 32 having one end portion 34 extending into the bottom of the tank while the other end 36 terminates in the outlet end portion of the tubular member. As illustrated, the openings 30 are not formed beyond the end 36 since this end portion seals off this part of the tubular member from the remainder. The tank is also provided with a pressurizing means, such as an elongate pipe section 38, located in the upper portion or the vapor space of the tank for the introduction of a gas under pressure to force the liquid in the tank into the discharge line for passage to the tank outlet. In the illustrated modification wherein the tank is laying on its side, the elements will be arranged as illustrated in FIG. 1. However, when the tank is positioned to stand on end, the discharge line 32 will extend downwardly at the bottom at one end while the pressurizing means will be arranged at the top at the other end.

It will be apparent that the tank described will be characterized by walls which will be capable of deformation as required in response to change in dimension of the interior shell due to expansion and contraction in response to temperature change. All of the elements located within the inner shell in contact with the liquid should be formed of material of the type used for the inner shell.

A tank of the type described can be constructed to various shapes but it is preferred to construct the tank to cylindrical shape as illustrated. For movement with conventional cargo handling equipment, it is desirable to maintain the tank within reasonable dimension and weight. By way of example, a tank embodying the features of this invention may be described as having a dimension of 20 feet in length and 6% feet in diameter which will have a capacity of 5,000 gallons of liquid and can be easily moved from place to place for storage or transportation, even when fully loaded.

It is desirable, though not essential, to make use of elements for stabilizing and supporting the tank, especially when arranged in or on a carrier which is subject to varied movements, such as in the pitching and rolling movements of a ship, or when the containers are adapted to be stacked for most efiicient utilization of storage space.

One such stabilization means, illustrated in FIGS. 3 and 4, comprises cushioning segments 40 in the form of pads of curvilinear shape to correspond with the curvature of the containers or tanks and with the pads having a back wall 41 preferably of larger dimension mounted upon supporting plates 42 which can be secured at specified intervals to structural members, such as I beams 44 used to define the space in which the tank is to be mounted. The padded plates may be mounted in vertically spaced apart relation on the surrounding structural members when the tank is stood on end, as in FIG. 4, or they may be secured on horizontally disposed structural members if the tank is to lie on its side on the support, as in FIG. 1 to support the inner shell or tank in spaced relation from the supporting members. The pads may be provided with valves 46 for inflation or deflation, depending upon the dimension of the tanks or change in dimension due to expansion or contraction, firmly to support the tanks in a stabilized position.

In another modification, a self-sufficient tank capable of its own support may be constructed, as shown in FIG. 5, of an inner shell 50 and an outer shell 52 with the space in between being thermally insulated, as by the means previously described or preferably by evacuation of the space filled with a powdered or particulate insulation. The outer shell 52 is reinforced or strengthened and stiffened by main members in the form of metal beams and the end Walls are provided with aligned

metal channels

54 and 56 with the channels in one end having a span or outer Wall to wall dimension which is slightly less than the inner wall to wall dimension of the channel members 56 on the opposite end so that the channels on one end can be received in fitting relationship in the channels in the other end for stabilizing the positions of the tanks as they are stacked one upon the other.

When, as in the construction shown in FIG. 5, the insulation does not form a structurally strong element with the inner and outer shells, it is essential to support the inner shell in a stabilized position within the outer shell while permitting freedom for relative movements of the inner shell with reference to the outer shell in expansion or contraction due to temperature change but without permitting uncontrolled relative movements due to movement of the container. For this purpose, the inner shell 50 is suspended within the outer shell as by means of cables 58 and 60 which extend from a brace 62 about the center of the inner shell to brackets 64 on the inner surface of the outer shell spaced in opposite directions from the center. Such suspension means are provided not only in the side walls but also between the end walls as illustrated by the cables 66 extending from the center brace 62' to the outer brackets 64 on the outer shell.

A tank of rectangular shape dimensioned to be 10 X 8 x 31 feet will have a capacity to hold about 2500 cubic feet of liquid and will weigh about 62,000 pounds when fully loaded with liquefied natural gas.

In tanks of the type described, it is desirable to embody a valve communicating the interior with the exterior of the tank for the release of pressure and for connection thereto to effect passage of liquid into the tank for filling and use of the tank for discharge. A valve connection which may be embodied in one of the walls of the tanks of this invention is illustrated in FIG. 6 wherein a short tubular section 61, which may be a part of support column 22, secured at its outer end to the

tank wall

50 or 10, is closed at its inner end by a plug 63 having a central opening 65 surrounded by a valve seat 66 lined with a sealing member 68. The outer end of the tubular section is formed with an inwardly extending annular flange 70 covered by an end plate 72 with a sealing member 71 inbetween and having an opening 74 extending therethrough for the insertion of a pressure gauge pipe 76 and another central opening 78 of larger dimension adapted to enable a tubular fitting 80 to be inserted therethrough for the passage of liquid into and out of the tank. The end plate 72 is removably secured onto the outer end of the tubular section, as by means of bolts 82.

The openings through the end plate 72 and flange 76 lead into an annular gas chamber 84 defined by a pair of outer and

inner sleeve sections

86 and 88 respectively sealed at the inner end by an annular disc member 90. The outer sleeve 86 has an opening 92 extending into communication with an annular distributing chamber 94 sealed by O-rings 96 on opposite sides thereof to minimize escape of pressurized gas. An opening 98 in the tubular section 61, which communicates with the distributing chamber, is provided with a fitting 100 for attachment of a tubing 102. which leads to the pressure distributing member 38 in the vapor space of the tank and it is also provided with a relief valve 194 for the release of vapors from the tank into the gas chamber when the pressure within the tank exceeds a predetermined maximum.

Mounted within the tubular section for axial displace ment between blocking and unblocking position is a plunger res shaped at its inner end to conform with the seat 66 to seal the opening when the plunger is displaced to blocking position. The plunger 1% is constantly urged towards blocking position by resilient means, such as coil springs 198 having one end bearing against a stepped portion on the back side of the plunger 106 while the other end bears on a ring plate 110 fixed to extend inwardly from an intermediate portion of the inner sleeve section 88. Means are provided releasably to latch the plunger in seated or blocking position and to release the plunger for retraction to unblocking position to enable movement of liquid into and out of the tank. One such latching means comprises a lever member 112 pivotally mounted intermediate its ends on a stud 114 fixed to an upper portion of the inner sleeve 38 with one end of the lever arm 112 being formed with a hook 116 to engage the back side of the plunger when in seated position while the other handle end 118 of the lever engages a rod 120 on the outer end of a bellows 122 fixed to the disc plate 96 in registry with an opening 124 extending through the disc plate to communicate the bellows with the gas pressure chamber 84.

The latching lever 112 is held in latching position to prevent inadvertent disengagement of the plunger until the tubular fitting is inserted into position of use within the valve. For this purpose, use is made of a locking lever 126 in the form of a bell crank lever pivoted intermediate its ends on the disc plate lit with one arm 128 extending inwardly to engage the back side of the hook 116 when the latching lever is in latching position while the other arm 13% extends laterally into the path of the tubular fitting to be engaged thereby as the fitting is displaced into position of use. The locking lever is constantly urged toward locking position by a coil spring 132 disposed between the arm 128 and the adjacent portion of the inner sleeve 88.

Means are also provided releasably to secure the tubular fitting 8%) when inserted into position or" use. For this purpose, the valve is provided with an annular block 13 having a central bore 136 dimensioned to correspond with the outer wall to wall dimension of the tubular fitting for enabling the latter to be displaced therethrough. The block is formed with one of more and preferably four openings 133 arranged 90 apart in which a ball M is positioned for radial displacement in response to bellows M2 which are sealed onto the outer surface of the inner sleeves 88 in registry with openings 144 extending through the sleeve for communicating the bellows 142 with the pressure chamber 84. The tubular fitting is also provided with an annular recess 146 adapted to be aligned with the portion of the tubular fitting to shut off the fitting when removed from the valve. For this purpose, the end of the fitting is provided with a valve seat 148 about the opening 150 for receiving a plunger 152 in seated relationship thereon responsive to the constant urging by springs 154 or to the resilient members disposed between the back side of the plunger and an annular stop 156 extending inwardly from a rearward portion of the fitting. The plunger is slidably mounted within a cylindrical section 158 having ports 160 to unseat the plunger responsive to the flow of fluid under pressure from within the tubular fitting into the tank.

'In operation to discharge liquid from the tank, the tubular fitting is inserted into the bore 136 of the block 1-34 until the locking balls 140 enters the recess 146. Upon movement to position of use, the end of the fitting engages the arms of the locking lever 126 to rock the lever about its pivot to unlocking position thereby to withdraw the arm 1128 from thepath of the hook 116 of the latching lever. Thereafter, when the pressure gas a pipe 76 is inserted into the opening 74 and sealed by O- nings 1-62, the pressure gas released into the chamber will have a number of functions. In one instance, it will expand the bellows 2142 to displace the balls into the recess 1146 to lock the tubular fitting in position of use in the valve. It will expand the bellows 122 to rock the latching lever 1112 about its pivot to release the plunger 106. Pressure gas will flow through the openings 92 and 98 into the line 162 to provide pressure within the tank which, when added to the liquid load, will be sufficient to overcome the force of the springs M8 to unseat the plunger 1% so that liquid can flow freely from the tank through the opening 65 into the tubular fitting 80.

When the'pressure gas is inactivated, the balls 144) will be released to enable removal of the tubular fitting. Upon removal of pressure from the liquid, the springs 154 will become effective to displace the plunger 152 to sealed position to block the opening in the tubular fitting. The spring 108 will become effective to I displace the plunger 106 to sealed position to block the opening 65. While in this position, the latching lever .112 can be rocked tolatching position and upon clearance of the hook end, the locking arm 128 will be rocked by the spring 132 to locking position thereby to positively lock the plunger in blocking position.

The same reactions will be caused to take place upon insertion of the described elements to fill the tank.

.It will be apparent that the valve structure described can be somewhat simplified, when desired, to effect the desired sealing relationship of the tank to permit the flow of liquid into and out of the tank for filling and discharge.

It will be apparent also that the valve system described can be effectively employed in tanks embodying the various concepts of this invention to eliminate the need for providing each tank with a pump, while at the same time sealing the interior of the tank with pressure relief means in the event that the pressure within the tank rises to beyond a predetermined maximum.

-It will be understood that changes may be made in the details of construction, arrangement and operation without departing from the spirit of the invention, especially as defined in the following claims.

1. A portable, insulated tank for housing a liquid having a temperature differing widely from the ambient temperature comprising a fluid and vapor impervious inner shell fiormed of a material which is relatively insensitive to the temperature of the liquid to be contained therein, an outer shell spaced from the inner-shell with an insulating space inbetween, a thermal insulation having a low coetficient of thermal conductivity in the insulation space between the inner and outer shells, pressure responsive means communicating the interior of the tank with the exterior for the release of vapor-s from within the tank when the pressures therein exceed a predetermined maximum, a port extending through said inner and outer shells and insulation space for the passage of liquid therethrough into and out of the tank, a valve in communication with said port for the control of liquid flow through; said port, and means for supporting the inner and outer shells with the insulation space therebetween, said last mentioned means comprising an elongate tubular member extending lengthwise through the interior of the tank and struts extending outwardly from the tubular member to the inner shell, said tubular member communicating with the said port and with a discharge line having one end near the bottom of the inner shell and the other end in the tubular member for passage of the liquid through the tubular member into and out of the tank.

2. A storage tank as claimed in claim'l in which the inner shell comprises a relatively thin membrane of a fluid and vapor impervious material which is free from attack by the liquid and capable of retaining strength and ductility at the temperature of the liquid.

3. A storage tank as claimed in claim 1 in which the outer shell comprises a sheath of a resilient, fluid and vapor impervious material.

4. A storage tank as olairned in claim 1 in which the insulation within the insulation space comprises a compact evacuated layer of alternate lamina of inorganic fiber mats and reflective metal sheets.

5. A storage tank as claimed in claim 4 in which the mats of inorganic fibers comprise glass fiber mats of small thickness.

6. A storage tank as claimed in claim 4 in which the refiective metal sheets comprise aluminum sheets of small thickness.

7. A storage tank as claimed in claim 4 in which the layers of alternating mats of inorganic fibers and reflective metal sheets are enclosed Within a bag of vapor impervious material and evacuated.

8. A storage tank as claimed in claim 1 in which the insulation comprises a particulate substance in the insulation space and which includes means for suspending the inner shell within the outer shell in a manner to stabilize the position of the inner shell while the inner shell remains free for movement relative to the outer shell in expansion and contraction due to temperature change.

9. A storage tank as claimed in claim 8 in which the means suspending the inner shell Within the outer shell comprises a plurality of elongate resilient members secured at one end to the inner shell and at the other end to a lengthwise spaced portion of the outer shell.

10. A storage tank as claimed in claim 8 in which the means suspending the inner shell Within the outer shell comprises cables secured to the inner shell at about the mid-portion thereof and to the outer shell at about the opposite end portions thereof.

11. A storage tank as claimed in claim 1 in Which the tubular member defines a plurality of spaced openings for free how of liquid into and out of said tubular member.

12. A storage tank as claimed in claim 1 in which the supporting means additionally comprises stifi structural members fixed to the outer surfaces of the outer shell.

13. A storage tank as claimed in claim 12 which includes spaced channel members on opposite fiat Walls of the outer shell with the channels on one wall being dimensioned to receive the channels on the opposite wall in inter-fitting relationship to enable the tanks to be stacked one upon the other.

14. A storage tank as claimed in claim 1 which includes pressurizing means within the upper portion of the tank for introducing vapor under pressure into the tank.

15. A storage tank as claimed in claim 1 in which the valve comprises a chamber having a passage extending therethrough communicating the interior of the tank with the exterior, means for releasably holding a fitting within an outlet end portion of said passage, a plunger shiftable in said passage between passage blocking and unblocking positions, means constantly urging said plunger towards blocking position, latching means releasably engaging said plunger when in said blocking position for holding said plunger in said blocking position, and means for inactivating said latching means to free said plunger for movement to unblocking position.

16. A storage tank as claimed in claim 15 which includes means *within the valve for releasably locking said latching means in latching position, and means for inactivating said locking means responsive to the insertion of the fitting in position of use Within said passage.

17. A storage tank as claimed in claim 16 in which the valve includes a pressure chamber and means responsive to pressure within said chamber for inactivating said latching means, means responsive to pressure within said chamber for activation of said means for releasably holding the fitting to lock the fitting in position of use and means responsive to pressure Within said pressure chamber for pressurizing the interior of the tank.

18. A portable insulated tank for housing a liquefied gas having a low boiling temperature comprising a fluid and vapor impervious inner shell formed of a resilient material which is relatively insensitive to the cold of the liquid, an outer shell spaced from the inner shell with an insulation space inbetween, a thermal insulation within said insulation space formed of a multiplicity of alternate layers of an inorganic fibrous mat and reflective sheets of metal with the insulation space being evacuated whereby the insulation layer is engaged by the inner and outer shells to form a part of a structural tank wall, a tubular member extending lengthwise through the interior of the tank, spiders extending outwardly from the tubular member into engagement with the inner surface of the inner shell for support thereof, an outlet opening in the tank in communication with the tubular member at one end, a discharge line having one end near the bottom of the inner shell and the other end in the tubular member for communicating the interior of the tank with said outlet opening, and valve means within the opening for the control of liquid flow into and out of the tank.

References Cited in the file of this patent UNITED STATES PATENTS 2,858,136 Rind Oct. 28, 1958 2,863,297 Johnston Dec. 9, 1958 2,900,800 Loveday Aug. 25, 1959 2,908,145 Haumann -1 Oct. 13, 1959 2,916,060 Hanson et a1 Dec. 8, 1959 2,916,061 Hahn et al. Dec. 8, 1959 2,970,452 Beckman et a1 Feb. 7, 1961 OTHER REFERENCES Advances In Cryogenic Engineering (Timmerhaus), published by Plenum Press, Incorporated (New York), 1960", volume 1, Proceedings of 1954 Cryogenic Engineering Conference (pages 23-26 relied on).

Claims

1. A PORTABLE, INSULATED TANK FOR HOUSING A LIQUID HAVING A TEMPERATURE DIFFERING WIDELY FROM THE AMBIENT TEMPERATURE COMPRISING A FLUID AND VAPOUR IMPERVIOUS INNER SHELL FORMED OF A MATERIAL WHICH IS RELATIVELY INSENSITIVE TO THE TEMPERATURE OF THE LIQUID TO BE CONTAINED THEREIN, AN OUTER SHELL SPACED FROM THE INNER SHELL WITH AN INSULTING SPACE INBETWEEN, A THERMAL INSULATION HAVING A LOW COEFFICIENT OF THERMAL CONDUCTIVITY IN THE INSULATION SPACE BETWEEN THE INNER AND OUTER SHELLS, PRESSURE RESPONSIVE MEANS COMMUNICATING THE INTERIOR OF THE TANK WITH THE EXTERIOR FOR THE RELEASE OF VAPORS FROM WITHIN THE TANK WHEN THE PRESSURE THEREIN EXCEED A PREDETERMINED MAXIMUM, A PORT EXTENDING THROUGH SAID INNER AND OUTER SHELLS AND INSULATION SPACE FOR THE PASSAGE OF LIQUID THERETHROUGH INTO AND OUT OF THE TANK, A VALVE IN COMMUNICATION WITH SAID PORT FOR THE CONTROL OF LIQUID FLOW THROUGH SAID PORT, AND MEANS FOR SUPPORTING THE INNER AND OUTER SHELLS WITH THE INSULATION SPACE THEREBETWEEN, SAID LAST MENTIONED MEANS COMPRISING AN ELONGATE TUBULAR MEMBER EXTENDING LENGTHWISE THROUGH THE INTERIOR OF THE TANK AND STRUTS EXTENDING OUTWARDLY FROM THE TUBULAR MEMBER TO THE INNER SHELL, SAID TUBULAR MEMBER COMMUNICATING WITH THE SAID PORT AND WITH A DISCHARGE LINE HAVING ONE END NEAR THE BOTTOM OF THE INNER SHELL AND THE OTHER END IN THE TUBULAR MEMBER FOR PASSAGE OF THE LIQUID THROUGH THE TUBULAR MEMBER INTO AND OUT OF THE TANK.