US2512308A

US2512308A - Storage reservoir for liquefied gases

Info

Publication number: US2512308A
Application number: US571804A
Authority: US
Inventors: Howell C Cooper
Original assignee: PITTSBURGH DES MOINES Co
Current assignee: PITTSBURGH DES MOINES Co; PITTSBURGH-DES MOINES Co
Priority date: 1945-01-08
Filing date: 1945-01-08
Publication date: 1950-06-20
Anticipated expiration: 1967-06-20

Description

June 20, 1950 H. c. COOPER STORAGE RESERVOIR FOR LIQUEFIED GASES Filed Jan. 8, 1945' 3 Sheets-Sheet 1 INVENTOR INVENTOR Go r v wag 3 Sheets-Sheet 2 I I I T 1| -I I I II I I II III IIIII.IIIIIIII" n l I I I hfH Jll'h" III llI l Lb Ol II I l l ll IIII I I l I I June 1950 H. c. COOPER STORAGE RESERVOIR FOR LIQUEFIED GASES Filed Jan. 8, 1945 June 20, 1950 H'. c. COOPER STORAGE RESERVOIR FOR LIQUEF'IED GASES 3 Sheets-Sheet 3 Filed Jan. 8, 1945 fNVEN TOR F'atentecl June 20, 1950 21512363 s'i o imoi j'nl jsrznvoinron LIQUEFIE'fi GASES o. ouster; Sewickley', Pa,- assigrior to Bittsburgh-Ds Moines company, a corpora emanation January 8, 1945, Serial No. 571,80;

for gas, in somemaceswne norh'ialaiid- -in some places the peak demands; arfsi'ich" that the existinglines-and*gais umrerig-racniti aremaeequat'e to" supply-siiificient gas; Although it has been proposed te-meet"trfiscoaemen byiiquerseng natural gasat or near gasweus and tra iispc irt- 1;

ing it to points or corrsuni'etion a'sfa liq uid anol also by liquefyi-ng-at ornear points of cons tion the gas that is' n0't required -at'ldw demand periods and la turning-it-to the linesasgas during highde a'fid 'periGdS; I'havenokrrowledge o'f any facilities,- prior to m invention,- that are capable of storing l'iquefied-natural gas in the manner necessary to meet the safety; em oiency and other requirernerrts incidentto trim supplyingofsupplementing the" supply of natural gas; I

The-general object of this invention is'to pro"- vide a: reservoir o'i large capacity f'or" liquefied natural gasin which it may be stored safel y anti With little loss due to evaporation or gasification, and a specialobject is to provide a statinaryr reservoir" of the type stated wh'ic'h is particularly suitable for storing liquefiedmatural gas atornear'its' place of consumption.

The invention is illustrated in the" accentpanyin'g drawings inwhich Fig. 1 is a side'view in elevation or a; reservoir of this J invention ror storing liquefied' natural gas;

Fig. 2 is a topvplan 'view of Fig; 1;

Fig 3'is an'enlarged"fragmentary'view partially in elevation and partially in section, the section beingi taken through the'center of-the container adjacent the inlet-and outletsttucture shown-in Fig;- 1;-

Fig. 4 adetail view 01' the outeiend portion of the inlet andoutlet structure shown in 'el'evathe reservoir of tion in Fig; 1- and in -section in Fig; 3'; looking at lthe attachmentof one-of the supporting columns 7,

2 thereof and the i elation between the inner tank andthe outer ca g adjac'ent such mid porti'on.

There are sev'e a'rknown procedures for liquefying natural g' 'as' whos'e I iduefaction "temperature is about 250 F; at atmospheric pressure, one of such procedures being that use'dior' recovering helium from natural gas containing it. Any of such prooedures'rh ay beused for liqueiying natural gas for storage in the'res r'voir" provided according to my" iiwenti'o'rr. Such reservoir includes an inner tank'andan outer-casing wlios'e walls are spaced from each -other' throughout. The space between those walls-isfilled with a body 0': insulationwh'ich rerms' the soie su port for the inner tank by tlie outer casing, thus avoiding the use of sueri -metai structural sueports as wouldreadilyconduct heat to the tank. The outer o'a'sifi is supported exteriorly'asby columns, in such a w'ay'thait the reservoir and its ap u tenances are fio'si tidfied above or out or contact-with heat Gfidutbrslwhen averylarge capacity is desired, the reservoir is-pre'ferabl y spherical in form, the inner tank bein-g substantially concentric with the'outeicasing.

Liquefied fiaj'tilral gisis"introduced into and withdrawn" rrom the' reservoir by a conduiteirtending through the bottom of; andwh'ieh preferably extends laterally beneath; the'res'ervo'ir. Regardless oi theffctiveinessof the insulation of the tank, tirere is' rfioriiially some evaporation or gasification of the liquefied natural gas dile to some infiltration or neat, 'ir i ViW'Of whicfipr'dvision is made-for the-eseaeeor such gas by causing it to flOW'th'I'GiigIi-B C'Ofidfiit having an inlet near the top of the J tank" and extending downwardly through the bottofii of are reservoir. Preferably this waste gas' conduit surrounds the liquid conduit so that the' low temperature waste as in effect insulates the liquefied gas conduit. For further insulating the latter, a shell surrounds and is spaced rrom it',-'th'e* shel'lpreferably being attached tothb'ottoni-of the casing; and the space betwe'iii and the waste gas conduit being filled with 'i illlfiiOI'lI Other feature ofthe invention will be explained' with referei'ice' to -thereservoir shown" "in the accompanying" drawings which includes an inner tankl and-ano'uter caSingL'each'of which 'is' preferably formed of shaped-plates of steel whose edges arewelded to form a securely sealed structure." Because of the very low temperature working conditionsof'the inner tank; it maybe formed of a low caii'bon nickel steel containing about .OB-p'er cent'carbonand about 315 per cent'niclcels- 'Other metals such as copper,

aluminum and alloys of various kinds, which retain sufficient ductility at low temperatures, may also be used for forming the tank.

In the space between the tank and casing below the mid section of the reservoir there is insulating means which has sufficient strength to itself support the tank substantially concentric within the casing when the tank is filled with liquefied natural gas, and which insulating means has a relatively low thermal coefficient of expansion so that it will not prejudicially contract when cooled by the liquefied natural gas.

This insulating means provides a member in the form of a segment of a hollow sphere which not only serves as a cradle for supporting the tank during its construction, but as a foundation for supporting the tank and its contents of liquefied gas by the casing.

It has been found that this cradle in the form of a hollow spherical segment of insulation can be built up from blocks or slabs of foam glass, blocks of balsa or other wood having a low thermal conductivity, or of cork board.

If foam glass is used, it can be sawed into blocks or slabs which, when laid up in staggered joint fashion, will substantially conform to the curvature of the casing shell. If wood blocks are used, they are also preferably arranged in layers with the joints staggered. They are so arranged that the grain of the wood extends substantially perpendicular to the inner surface, of the casing shell, since wood is of lower thermal conductivity lengthwise of the grain than across the grain. When cork board is used, it is also laid in layers in staggered joint fashion.

It has been found that among the materials now available cork board is the most satisfactory. Wood, such as balsa wood, is the next most satisfactory and foam glass is least satisfactory of these three materials from the standpoint of thermal conductivity.

All three of these materials, however, are characterized by their ability to withstand temperatures below -100 F. without progressive compacting during low temperature use of the reservoir and without material increase in capacity to conduct heat.

Cork board has a lower thermal conductivity than balsa or any other wood with which I am familiar, and balsa wood has a lower thermal conductivity than foam-glass. These three materials, however, have sufficient strength for use in forming the cradle for supporting and holding the inner tank shell substantially concentric with the outer casing.

Instead of extending the cradle up to the mid section of the container, it will function satisfactorily if it only extends up 45 from the center of the lower polar region of the casing, since this will be sufficient to support the load made up of the tank and its contents and hold the tank concentric with the casing.

In constructing the reservoir, the outer casing is first welded upon suitable forms up to about the mid section of the reservoir, and thereafter the layers of insulating material in the form of slabs or blocks are progressively laid with the joints between the blocks or slabs in one layer staggered with relation to those in the adjacent layers. These layers are laid upon the inner wall of the casing beginning from the bottom center and working upwardly in all directions. When the entire thickness of-the cradle is thus formed, the metal plates forming. the, inner tank are laid upon the cradle and the plates are welded to- 4 gether in place, the cradle being thus firmly held in place between the outer and inner walls of the reservoir.

Above the cradle the inner tank wall is built up before building the outer casing. Thereafter the space between the tank and casing above the cradle is filled with granular or loose fibre forms of insulation 4, preferably granulated cork, which is compacted between the walls.

The entire reservoir shown in the drawings is supported solely by a plurality of columns which hold it otherwise out of contact with any heat conducting surface or structure. As shown in Fig. 6, columns 5, which may be in the form of H-sections, are welded to the mid section of the outer casing, the flanges of each H-section being cut to conform with the curvature of the casing and being welded to it through suitably curved angles 6. At the mid section of the reservoir a working platform 1, extending entirely around the reservoir, is conveniently attached to columns 5. Also, for strengthening the upper portion of the outer casing it is provided with ribs 8, as shown in Figs. '1 and 2, and for stabilizing the columns their tops and bottoms are cross connected to each other by tie rods 9.

For the discharge of waste gas, which is normally formed in the tank due to an unavoidable small infiltration of heat, a waste gas conduit 10 extends from near the top of the tank downwardly through the bottom of the reservoir. 1 At its top, tank I is provided with an opening which receives a hood II that surrounds the top of con duit l0 and has its outer face welded to the wall of the opening formed in tank I. As shown in Fig. 5, the upper end of conduit [0 is slidably positioned in hood H to permit movements of the end of the conduit within the hood due to thermal expansion and contraction of the conduit. This hood is provided with a plurality of openings l2 for the passage of waste gas from the tank into the top of conduit in in the manner generally indicated by the arrows in the hood. The lower end of conduit l0 extends through the bottom of the reservoir and projects laterally beneath it, as shown in Figs. 1 and 3, it being provided with expansion joints l3 which, as indicated, may be of the Sylphon tube type. The outer end of conduit I0 is provided with a fitting l5 for attachment to a conduit [4 leading to a pipe line from which the gas can be used, or the gas can be reliquefied.

As an emergency measure, provision is made for venting waste gas from conduit 10 in the event of such rapid generation of gas in the tank :that a material increase in internal tank pressure ensues. For this purpose-a conduit I8 maybe attached to the outer endof conduit l0 and extend upwardly to the upper portion of the'reservoir where waste gas may be safely vented to the atmosphere through'asuitable weighted or otherwise controlled check valve l1.

A conduit 20 for conducting liquefied natural gas to and discharging itfrom tank I extends concentrically through waste gas conduit 10- and is adapted at its outer end to be connected to -a conduit l9 disposed inconduit l4 and leading from suitable liquefaction apparatus. At its iriner end, beneath the reservoir, conduit 20 preferably projects through the elbow of conduit I0 and upwardly to a position a short distance above the bottom of the tank. Surrounding the portion of waste gas conduit l0 immediatel'yabov'e the bottom of tank I there is a perforated drum 2! within which liquefied gas is discharged from sacrifice 22 sttheupperenderecndult zc, and from which it-fiowsin't'o tank I'. For controlling flow throughv conduit 20 its ormceM is pro vi'ded witha valve zli"which is adapted to be raised and-lowered; as 'desiredy by -a cable--24 whose upper end is attached toa rod-that ex tends upwardly through suitably packed joints ixfthmtops ofthe tank andcasing \iIa-llsi.

Surrounding-conduit I0 and-spaced-from it a substantial distance, there} is a shell 3'0 which; as

shown in Fig. 3, hasan inneropen" end welded at, 3 I tocasing 2 whosebottom" is-provided with an. opening to receive conduits 1'0 and 20. The space=betweenconduit -l0-and shell-'30 isfilled wlthinsulationto insulate liquid'gas conduits l-0 'and 20i To-prevent the accumulation of gas pressure'in the e'vent of leakage 'ofgas through the wall o'ftank l or its pipe connections -20, thetop of casing 2 is provided with suitable relief valves fi which'are connected to aninverted -cup-shape:d structure 35 whose outer face is welded to the wall of an opening formed in casing 2 toreceiveit." Thus if gas-pressure-build's *up in the insula tionbetween tank I and casing 2, pressure will berelieved before'anydamage' to-tanks l and 2 occurs.

Further features of the reservoir here provided will now be explained" with reference to the preparation'of' the reservoir for use, andthe de= scription of its operation. After the reservoir has "been fully constructed'andinsulated, theinsul'ation is preferably dried and its-voids supplied with a gas having low liquefaction and freezing points so-that it will-remain in its gaseous form, and which is inert to preclude c'ombusti0n in'the event of accidental-accinnulation of gas in the insulation space. For "this purpose dry air or other gas may be forced' through-the insulation* by a pump- 40, diagrammatically shown in Fig. 1, having a conduit 41 connected to its inlet and a conduit 42 extending from its outlet to one side of a dehydrator 43, from theother sideof which a conduit 44 extends tothe outer endpf; shell 30. Conduit 44 may contain a heater '39 for heating the air supplied by pump 40 to the insulation between waste gas conduit 10: and shell 30. The heated air-then-passes from-athe shell upwardly through the-body of insulation between the walls of tank l-andcasingZ to remove moisture from the insulation and'to expel moist air and other gases and vapors from it, such air and gases escaping-through manholes 45, which are then openpinzthe top of easing 2; Thereafteran inert gasrhavingwlow liquefaction and freezing points, such as nitrogen or products of combustion, may be similarly pumped into and through the insulation so that its voids will ;be sufiiciently free from oxygen that combustion will not take place in the insulation in the event of leakage of gas through the wall of tank I. If desired, the drying of the insulation may be efiected by the inert gas instead of first pumping heated air into and through the insulation. To maintain a predetermined static pressure within the insulation space, pump 40 may later be used to supply additional gas to that space to compensate for changes in the volume of the space due to thermal contraction of the tank and of the insulation when the tank is supplied with liquefied natural gas.

When the insulation is dried and supplied with inert gas, the reservoir is in condition to be filled with liquefied natural gas which flows into it through conduit 20 from the last stage of a.

liqueractiefiapparatus which" the iiquehedlggg may be at a temperature of about f -lm wand under-a pressure of- 600 pounds; The reduction of the high pressur-on thel-iqiiid to atmospheric pressureresmts iii-vaporization *or 'gasification of a pertien-= fth liq'iiid='-and-a *r'eduction'ob he temperature'pFthe remaining-liquid to about E4260F321t which remains liquid under-sub; 'stanti'aiiy atmospheric pressure; The-gasthus formed flows through waste-gasconduit-l0; and at its low temperature is fled to the compressor of the qiciueraction apparatus in "which 1 it again liquefied? v I During the filling of the tank with liqiiefied gas, *valve"23-' is ra ised from' orifice 22' at tHe 'top ofonduit 20 and-isreturnedto 'itsfseait'to' close the orffice when-liquefied g'as noes owing into tII'BtaIIk. The of""1"iquid"and*gas then remaining in conduit 20 may be withdrawn-as -a safety precaution to preventt'he building up; of pressure" witliin that conduit: When it 'de=- sired to remove liquefied natural gas from tank I' for supplying'i has gas to a lineyvalve fi is raised. Near the"endpf-iconduiti'fl a conduit 50, is attached to it for the di'sclfargeo'f liquefied gas;-rcdnduit 50 extending withinithe gas'; relief 'fihrbligh its Side. .Thefliqujii TBh'n fi "'s'toa haterfor converting it "into gas which is disc:h a'rg'e'd' intoa supplyfii'ne;

1 h "511113 storing gliqiie'fid fl'lat'lll'al gas," it ,iS li ighlyid'sirableffth'it'itl'ire be a minimum infiIT-Y ti'atibfi of Heat in the tank. To this "ndL-anini portant feature bftli invention .I'eSidEs in .Sllp

, porting-the.tankflsolely 'bythebody of insulation.

between 'it'jandl the casingasuirounding. and. turn supportinget'h casing solely by. coluinnsor other mea'ns so. thatrtheireseryoinand .theifilling and. dischargev instrumental flies. connected .toLi-ts bottom be free.,'from-. contact. with-anything: that wouldafioid a path for relatively, rapid .conduc, tiongof heat; Further important features, reside in. the -;construction and. arrangement of. .the liquid and gas filling, and discharge instrumem tal-itiess and, in the Ycharacterv 10f .the "insulation.

Byways of example,. [but .-.wi-thout l-imita-tiom mi invention, {a reservoir ether .-same. herein shown and describedsands-constructed. ,for..;.the purpose herein explained,ehasazbeena built; The diameter of the inner. tank is approximately 57 :feet and that ofthe outer, casing is approximately feet, with a space of about! feet'in'thickness between them filled with" insulation. The tank has'a liquefied gas capacity suificient to form approximately fifty million cubic feet. of gas at :a. temperature of 60 -F. under arlpressure of-BO inches of mercury. Thus in one..--reservoir there may be stored more than five times as much gas as can be held in a modern ten million cubic foot gas holder, the cost of constructing which materially exceeds that of this reservoir. In this reservoir the waste gas conduit 10 is eighteen inches in diameter, which is sufiiciently large to remove gas from the tank as rapidly as the gas could be formed in the inner tank if that tank were uninsulated.

The weight of the tank shell is approximately 160,208 pounds and the weight of the liquefied gas stored in such tank is approximately 2,160,000 pounds; the total load supported by the insulat- :lng cradle is, therefore, approximately 2,320,208 pounds, and since the temperature of the lique- :fied natural gas and therefore of the tank shell :is in the neighborhood of about 250 F. at at- ;mospheric pressure, it will be appreciated that 7 thisinsulatlng cradle is an 'importantzieature of this invention I 1 According to the provisions ofthe patentstat utes I have explained the principle and opera tion of my invention and have illustrated and described a typical commercial embodiment of. it.

However, I desire to have it understood that,

within the scope of the appended claims, the invention may be practiced otherwise than herein illustrated and described. U f 3 i' This is a continuation in part of my cope'nding applicationSerial No. 367303 filed by' me on November 27, 1940, now abandonedi Iclaim: l I 1. A reservoir for storing liquefied natural gas for discharge as gas into a supply line, saidires er-l voir comprising an inner spherical tank and an outer spherical casing whose Wallis substanq tlally concentric with that of the tank, means for supporting said casing from its exterior, and a body of insulation consisting of. cork board in lower and granular corkin'theupperportiqn of the space between thewalls of said tank and casing, the corkboard forming the sole support of the tank by the casing. I j 2. A reservoir for storing a relatively'great quantity of liquefied gas, comprising an 'inne r substantially spherical tank, an outer substan-jtially spherical casing concentrically arranged with relation to such tank and spaced a substan tial distance therefrom, means for supporting such casing above the ground and a cradle for supporting the tank from the casing, hav ing' the form of a circular section of a hollow sphere the center of the surface of which coincideswith the center of the lower polar regionof the cas ing, and extends upwardly therein at least'fif from such center; such cradle being formedirom pieces of slab-like material of low thermal con-j ductivity arranged in a number of superimposed layers with the joints between the pieces forming one such layer staggered with relation tdthdse between the pieces forming the adjacent layers; such material being characterized by its' ability to withstand temperatures below -l00 Fi with out progressive compacting and without any material increase in its capacity to condilct'h'at when subjected to the weight of the tank and-it's contents of liquefied gas.

3. A reservoir'asdefined in'claim 2, in which the'slab'like material from which the cradle -is formed is corkboard. 4. A reservoir as defined in c1ai m 2, in which the slab-like material from which the cradle-is formed is balsa Wood having its grainent'ending substantially perpendicular to the inner surface of the casing. a

8 T 5. A-res ervoiras;defined in claim-2, inwhich the slab -like -material from the which the cradle is formed is ,foam glass.

:6. A reservoir for storing a relatively great quantity of liquefied gas, comprising an inner substantially spherical metal tank, an outer substantially spherical metal casing concentrically arrangedwithrelation to such tank and spaced a substantial distance therefrom, means for sup porting such casing above the ground, means located within the bottom portion of the casing, having the form of a circular section of. ahollow sphere and forming a cradle upon which the tank is constructed and which constitutesrthe sole means for. supporting within the casing:v the tank and its contents of liquefied gas, and finely divided insulating materialsubstantially filling the space between suchtank and casing, above such cradle; such cradle being formed of sec tions of slab-like material of lowv thermal conduc tivity arranged in a number-of superimposed lay ers with the joints between sections in eachlayer staggeredwith relation to those in theadjacent layers; such cradle being characterized by its ability towithstand temperatures below -l00 .F. without progressive compacting and without anymaterial increase in its capacity to conduct heat during use of the reservoir..

'7. A reservoir as defined in claim 6, in which the slab like material from which the cradle is formed is corkboard. Y

8.A reservoir as defined in claim 6, in which the slab-like material from which the cradle is formed is balsa wood having its grainextending substantially perpendicular to the inner surface of the casing. I I w j 9. A reservoir as defined in claim 6, in which the slab-like material from which the cradleis formed is foam glass.

. HOWELL c. COOPER, 5

REFERENCES siren 1 The following references are of record in file of this patent:

, UNITED STATES PATENTS Number Name Date 644,259 Ostergren Feb. 27-, 1900 1,755,176 Feidmeier Apr. 22, 1-930 1,918,335 Heylandt July 18, 1933 2,195,077 Brown Mar. 26, 1 940 FOREIGN PATENTS Number Country Date 319,821 Great Britain Sept. 30, 192 9