US3169576A - Pipe line for conveying sulfur and other hot liquids - Google Patents

Description

Feb. 16, 1965 c. 0. LEE ETAL PIPE! LINE FOR CONVEYING SULFUR AND OTHER HOT LIQUIDS 3 Sheets-Sheet 1 Filed July 1, 1959 INVENTORS e 0. L 06 mCoCkJLelL zawwy jzr ATTI RNEYS' Feb. 16, 1965 c. 0. LEE ETAL PIPE LINE FOR CONVEYING SULFUR AND OTHER HOT LIQUIDS 3 Sheets-Sheet 2 Filed July 1, 1959 FIG.2

F I G 3 INVENTORS Clay: ence & Lee BY Cluffoad mCackfleLL Feb. 16, 1965 c. 0. LEE ETAL 3,159,576

PIPE LINE FOR convzyms SULFUR AND OTHER HOT LIQUIDS Filed July 1, 1959 3 Sheets-Sheet 3 am f ence c LLffouL mcif mu ATTORNEYS United States Patent 6 3,169,576 PIPE LINE FOR CONVEYING SULFUR AND OTHER HOT LIQUIDS Clarence 0.- Lee and Clifiord M. Cockrell, New Orleans, La., assignors to Freeport Sulphur Company, New York, N.Y.,.a corporation of Delaware FiledJuiy 1, 1959, Ser. No. 824,245 6 Claims. (Cl. 165-81) The present invention relates to the transportation of hot liquids and, more particularly, to an improved com posite pipeline and, method for transporting hot liquids underground or under water for long distances of several miles or more. The materials which can be transported in this manner. are those which are solid or viscous in their natural state but are free-flowing liquids when heated, such'as sulfur, asphalt, heavy. molasses and the like.

The mining of sulfur is economically achieved by changing it from a solid to a liquid at its source in Le mine, and conveying the molten sulfur under pressure through a conduit leading from the mine to ground level. While this method may. present some problems where the sulfur mine is beneath dry land and no substantial overland transportation is necessary, serious problems arise when the mine is beneath the sea, requiringtransportation of the molten sulfur long distances to shore.

One of the principal objects of this invention is to provide a method of, and apparatus'for mining a solid mate: rial capable of being melted by the application of heat and for transporting the material over great distances in a molten state.

Another principal object of this invention is to provide a method of, and apparatus for mining sulfur at sea and transporting the sulfur to the shore.

Another object of this invention is to provide such a system in which the material to be mined is changed to a liquid at its source and forced under pressure through a conduit buried beneath the ground or sea floor while maintaining the material in a liquid state. I

Another object of this invention is to provide such a system in which the buried conduit is a composite pipeline and includes no expansion joints.

Another object of the invention isto provide such a system including a mining station or a mining platform at sea at which mining equipment is provided and a prestressed, composite piping arrangement extending from the platform or station to a distant destination.

Another object of this invention is to provide such a system wherein the prestressed piping arrangement is buriedbeneaththe ground or sea floor from a point adjacent the platform or station to a distant destination.

. stretched to the sea-station.

Another object of this invention'is to provide such a i system wherein the prestressedcondition of I the composite piping arrangement is substantially relieved during the normal functioning of the system.

Although the principles of the invention are equally applicable. to the mining of meltable material and transporting it great distances over dry land or land incapable of accommodating surface transportation, they will be shown anddescribed as applied to; a' system for mining such a material as sulfur, where the sulfur dome is beneath a large body of water and at a great distance from shore. 1

In one aspect of the invention, an outeror main casing, adaptedto contain a line for conveying the molten material and aninsulatedjacket line surrounding the latter for tv'vo parallel sections of water line attached on opposite sides of the casing section in a mannerto provide a multiline' section of piping having a' relatively Wide bottom Patented Feb. 16,1965

. 2 surface'a're afor adequately supporting the piping arrangement withinthe soilat the sea bottom. A

The three portions of eachv composite section may. be welded. tosucceeding sections on shore, and the initial sections maybe attached to a vessel (or barge) sothat the pipeline is pulledout to sea as succeeding sections of the composite line are welded together. The assembled line may be pulled out. to. sea until theinitial sectionis spaced from a mining platform by. an amount substantially equal to the thermal strain to which the casing will be subjected during normal operation, or by an amount 50 to thereof. 7

A sea-station of platform may be provided containing mechanism for prestressing the main or outer casing by subjecting it to a tensile stress suflicient to strain the main casing until it reaches thev platform or mining location. This may be done by providing anchors, suitably of temporary nature, from which chains extend to sheaves attached to the offshore end of the main casing, thence vertically upwardy to the sea-station. The sea-station may extend from the mining platform to the ofishore end of the main casing and include a hydraulic jack mechanism mounted on sliding guide ways. With the shore end of the casingsecurely anchored, the ends of the chains opposite those connected to the seaward anchors may be raised by the jacking mechanism thereby applying an axial strain to the main outer casing, causing it to be Alternatively, the mechanism and power for prestressing maybe situated on shore or on a barge operating in-conjunction with anchors and cables.

After the main casing is prestressed, it is buried to'a predetermined deptlibelow the sea bottom. Not. only willthis insulate the casing against excessive heat losses, but when the back fill has developed sufiicient shearing strength, such casing will remain prestressed after the prestressing mechanism is removed or the anchor forming part of thetensile stressing. apparatus and the shore anchor are disconnected;

In another aspect of'the invention, the insulated hot fluid conveying line that surrounds the molten material conveying line within the main casing has mounted 'at each quadrant and externally thereof a series of rollers 'or other antifriction meansfor facilitating its movement axially of the main casing during assembly, during temperature changesof normal'use and during replacement.

The materialvconveying' line may be provided with radial pins at each of twoquadrants externally thereof for the purpose of spacing 'the inaterial-conveying line eccentrically within the hot water line, providing means for controlling buckling of the material-conveying line whenin Compression. Succeeding sections of these two lines may be'weid'ed on shore and guided into the trailing or shore end- 'of' the previously laidrnain casing or into each section of thegmain' casing before it. is laid. The roller means on the outer periphery of the hot fluid line maybe located at periodic intervals along the assembled lines,

thereby facilitating the movement of the .twojlines' within the main casing. r ln another aspect of the invention, the material-conveying and hot water lines when first assembled, may er:- tend into the main casing to a pointshort of the end ofithe main casing. Whenthe system is employedwith-sulfur, 'it Will be subjected to a temperature of about 300 F. because, although the melting point of sulfur is only 240 F its lowest viscosity occurs 'at about 300 F and becomes excessive above 320 F. Accordingly,-the sulfur may enter the sulfur lineat 320 F. at the mine and drop to about 280 F. at the shore or destination end of the. line. In order to minimize stresses due 'to the elevated operating temperatures, during assembly, water maybe circulated in these two lines within the main casing at a predeter minedtemperature, causing them to expand a predeter- 3 mined amount depending upon the prestress desired. These two interior lines may then be attached at each end to the main casing forming a composite prestressed arrangement. The main casing may be prestressed in tension to about 10,000 p.s.i. and'the hot Water and sulfur lines may be prestressed to any value up to their yield strength. These values are merely exemplary and comprise one set of satisfactory functioning conditions. Accordingly, when the lines go into operation at their higher operating temperatures, the main casing will have its tensile stress substantially relieved, while the hot fluid and sulfur lines will go into compression to a figure somewhat below their yield strength.

The above as well as other objects and novel features of the invention will become apparent from the following specification and accompanying drawings which are merely exemplary.

In the drawings:

FIG. 1 is a schematic diagram of a mining and transporting system of the invention;

FIG. 2 is a sectional elevational view of the multiline system taken substantially along line 2-2 of FIG. 1;

FIG. 3 is a section of the main casing and the internal pipe lines therein, of FIG. 2;

FIG. 4 is an elevational view of a prestressing apparatus which can be employed in performing a portion of the method of the invention; 7

FIG. 5 is a detail of the apparatus of FIG. 4; and

FIG. 6 is another detail of the apparatus of FIG. 4.

Referring to FIG. 1, a multi-pipe system 10 is laid along and in a trench 11 cut in the soil under the sea or other large body of water 12. Alternatively, the pipe system may be laid on the surface of the sea bottom and then buried by the action of a water jet and gravity. Referring to FIG. 2, this composite piping system includes an outer casing 13 of steel, which may be an A.P.I. 5L line pipe having a yield strength of 42,000 p.s.i. and may be provided with a protective corrosive resistant coating 14 about its outer surface. The casing 13 may be made up of random length sections having bell and spigot connections 15 (FIG. 3) at its ends forming means whereby succeeding sections may be welded together. Alternatively, the pipes may have butt ends over which sleeves may be welded. With either of these constructions, the joints are free of internal humps or projections. Inside the easing13, an insulated jacket line 17 may be located axially of the casing 13. The-line 17 may be made of a high tensile steel having a yield strength of 25,000 to 90,000 p.s.i. It preferably has a relatively thick insulation coating 18 around its outer surface, preferably composed of a non-rigid insulating material 18 having a relatively low thermal conductivity factor, such as bonded glass, mineral wool, asbestos, foam glass, insulating concrete, calcium silicate or the like.

Under the steel supporting bands 19, located at periodic intervals along the jacket line 17 there is, preferably, a rigid insulation material of. high strength, such as calcium silicate. If a non-rigid insulation material were used under these bands, these bands would'have to be rigidly secured to the pipe 17 through a rigid intermediate element. 'Each'quadrant of the supporting bands 19 may be provided with openings 20 therein for the reception of roller units 21 or other antifriction means. The roller units 21 in each quadrant tend to prevent'contact between the'inner surface of the outer casing 13 and either the bands or the insulation coating. The roller units 21 may be aligned and spaced apart sufficiently to straddle the bell and spigot joints 15 at the ends of the sections of the main casing 13. Each roller unit 21 may include a plate 22 having a box-like housing 23 of rectangular shape.

Rollers 24 may be tnmnioned in the sidewalls of the housing'23, and the plates may be welded or otherwise fastened to the supporting bands 19. Two rollers are preferably placed in tandem in each band spaced such that when one roller passes over the annular groove left at the joint, the other roller will support the internal pipes at a constant level. The construction may be such as to provide an annular space 25 between the casing 13 and the insulation 18 in which air or other inert gas under pressure above atmospheric may be maintained when the system is completed. This pressure will prevent the leaking of the water into the casing 13 and will maintain the insulation 18 in a dry atmosphere as well as provide a non-corrosive atmosphere for the rollers 24, the interior of casing 13 and the exterior of casing 17. If the structure and use is such as not to involve danger of leakage through the casing, a partial vacuum, instead of pressure,

, could be applied in the space 25, and it would reduce heat loss. Insulation blocks 26 of extremely low thermal conductivity, such as Johns Manvilles MIN-K (siliceous material with a resin hinder) or the like, may be mounted in back of each roller unit 21.

Inside of the jacket line 17, there is an axially extend ing conveying line 27 for passage of the molten sulfur or other hot liquid to be transported. It, too, may be made from a high tensile steel having a yield strength of 25,000 to 90,000 p.s.i. It may be of such diameter as to provide a space 28 between it and jacket line 17 for the circulation of a hot fluid of high heat capacity per unit of voltime, such as hot Water or" hot mineral oil, to maintain the material being conveyed through line 27 in a readily flowable state. In order to control buckling under compression, pins 29 may be welded or otherwise fastened to the outer periphery of line 27 at periodic intervals along its axial length. Where the space between the lines 17 and 27 can be sufiiciently small, the pins are not required.

When hot water is employed within the annular space 28, it must be highly treated in order to prevent the formation of scale and cori'osion and, therefore, is preferably recirculated with the addition thereto of'any required make-up water of suitable purity. Accordingly, a return pipe 30 having a protective anti-corrosion exterior shell 31 may be attached on one side of the casing 13 for the recirculation of the heated and treated water. Another pipe 32 having a similar coating 31 may be attached on the other side of casing 13 for the supply of utility and boiler feed water to the mining platform. This pipe may be protected from internal corrosion by means of a cement or other suitable lining 33. These two pipe lines 30 and 32 may be attached to the casing 13 by yoke members or bands 34 at periodic intervals along the system and straps 35 may be employed to bind the Lin 30 and 32 to the casing 13.

Successive sections of the casing 13 and of lines 30 and 32 may be welded or otherwise attached together on shore. Before the jacket line 17 and the inner line 27 have been introduced into the casing 13, the leading sec tion of the latter and of the lines 30 and 32, at the forward closed ends thereof, may be attached to a vessel and as the succeeding sections are welded to the shore ends, the three lines may be pulled seaward toward the sea platform at the sulfur dome.

With reference to FIGS. 4 and 5', when the leading end of the casing 13, to which an hermetically sealed chamber 34 has been attached, has reached a point shoreward from the seat platform a distance equal to from about one half up to the whole of the expected thermal growth of the casing 13 during normal use, a prestressing apparatus may be connected to it. Accordingly, the closed end 35 of chamber 34 may support a plurality of rigid brackets 36 to which brackets 37 may be fixed. The brackets 37 may have journal sheaves 38 for the reception of chains 39. Pipes 40 may extend vertically upwardly from the brackets 37 acting as chain guides- These chain guides 40 may extend to the surface of the.

42 for cooperation with links of the chains 39 to main-;

. tain each chain taut (FIG. 6). e

The jack station or platform 41 may include a base;

ployed with the guide members 44 to lock the carriage 45 at different points along the braces 43. m v

e The carriage 45 may include a base plate 46 through which the chain guides 4i extend; and to which, said guides are rigidly fixed. The plate 46 may support hydraulic jacks 47 and 48 on the top of which spaced cross beams 49 may be fixed. The, spacingof these cross beams 49 may be'such as to freely pass the chains 39 between them, and to permit locking the chains to the cross beams by crabfoot locks 50.

' The ends of the chains 39 opposite those on the platform 41 may be attached to piles 51 driven into the sea bottom, seaward of the mining station md in line with the axis of the casing 13, forming an anchoring arrangement. With the shore end of the casing 13 securely anchored, and by locking a chain 39 to the cross beams 49 as shown, application of hydraulic-pressure to the jacks 47 and 48 will apply a tensile strain tothe casing 13. The force producing this strain has a vertical component' that is resisted by the chain guides 40. Locking the jacked chain 39 to the top of its guide 40 by a lock vdition, lines 17 and 27 were welded to the. outer casing 13; Under these conditions, when the inner lines are placed in operation at temperature in the neighborhood of 309 F., they will go into compression to about onethird 011111611 yield strength. Should the lines 17- and 27 again cool 'down to ambient temperature, they will 'go into tension. If inner pipes 17 and 27 were not prestressed then they would operate solely under compression, but

under this provision material of would have to be used.

From the foregoing it is evident that during normal very high yield strength 7 operation substantially no stress from thermal causes at the seaward end of casing 13 may be provided with an opening in its end wall through which the casing 1 3,

"and its enclosed hot water line 17 and sulfur line 27,

42 as well as locking the carriage 45 to {the braces 43 will permit descent of the jacks 47 and 48 for attachment to another chain 39 as previously described. In this way, the carriage 45 is moved seaward toward the mining location along the braces 43 while applying a tensile stress to the casing 13. V

The amount of stretch of casing-13 can be such as to apply a tensile strain to the casing of an amount equal to the thermal. growth -of the casing '13 during normal use. In this wa the casing 13 during use willreceive its pr'e'stress and eliminate the need of expansion joints anchor and chains 3 may be removed fromgthe ends of the casing 13, the back fill maintaining the casing 13 in its prestressed condition.

Succeeding sections of line 17 "may be assembled andwelded, respectively, to-

gether and rolled seaward from shore through the casing 13, the rollerunit's 21 making this movement possible. the lines 17 and 27 may extend seaward to a point shortof the endof theprestressed'casing 13 anamount the sulfur line"?! and hot water 7 may pass and be-hermetically sealed to the walls of said opening The composite line including casing 13 may extend vertically upwardly along side of the chain guides V 459 and the lines 3% and 32, all of which may be encased within a casing 52. These lines may extend to the top may support all of the mining equipment necessary to a self-sustaining operation. It may include a -boiler 54,

such that they, too, may be prestressed pnior'to final v completion of the composite line. The method ofjprestressing lines 17 and 27, however, may bedone by circulating'hot water through themat a predetermined 7 temperature dep'ehdinguponithe prestress desired. Under.

an alternative procedure, units of random length are completely assembled on shore and the whole multi-pipe Should it be des red to operate these lines or eith er of them in tension at all times, say, to preventbuckling or' kinking, they or 'it 'may'either be heated to a tem- 1 perature slightly in excess of that during normal opera itiin a 'prestressed-condition when cool." On the other hand, should it be desiredt-o operate these-lines or: either. ef them in some compression, they o'ritrnay be heated l to a'temperaturebelowthe normal operating temperature. 1

'nrnre particulan embodimentdisclolsed; the inner lines q 17 and 27 were heated to 200"F. by passing hot water,

through them, causing them to expand injthe neighborhood-jot about thirty feet. a -Whilefin this expanded con -tion,-. or pulled, and whileheated, or pulled, they or it "maybe welded to the outer-casing 13 tojretain them or z the feed water 'of which may besupplied fromthe line 32. A branch leading from line 32 may,supply utility water for the crew living on the platform 53. a

As previously described, the lnghl'y treated, non-scale and non-corrosion producing water for maintaining the sulfur molten throughout the extent of the sulfur line 27 preferably should "be recirculated. Accordingly, the line.

31) may have therein a circulating pump ,56 on the platform ,(or a pump on shore); This pump '56 forces the water through a heat exchange unit 57 heated by. the V boiler 54. The outlet'58 of the unit 57 isconnected to the seaward end .of line 17. The shore end of line 17 connectsinto line 3%. which may contain a pump 59. An inlet linebfi with a check valve 61 therein; may be connected to line Sll'forsupplying treated water-from-a source (not shown.) to make up any losses within the system.

boiler 54. Suitable pressure pumps and otherconventional sulfur mining equipment are employed to force the sea water at atemperature of about 320 -F. downwardly through pipe 62, causing it tofmelt the solid sulfur within the mine. and to force, it upwardly through the sulfurline 27, thence with the aid of the pump 64, 1 through the composite buried pipe system including. casingv 13 and hot. waterline 17 to a receiver 65 at theshore' installation. which receivercan be an insulated sulfur barge. l I

Al ough thevarious' featuresofthe method. of, and, apparatus-for mining a solid .material'and transporting it in liquid form havje been described in detail todisclose fully one'embodim'ent of the invention, it willbe evident thatchangesmaybe made in such, detailsandcertain features may be employed without others withou't depart v 'ing from the principles ofthe invention. a I a r A composite pipingarrangement foriconveying hot i V 1 liquidmaterial long distances'which comprises arcentral pipe for conveying the hot liquid, an "insulated heating 7 line larger than and surrounding but unattached to said central pipe through which hot fluid can be circulated to maintain the hot condition of the liquid in said central pipe, an outside jacket casingsurrounding said heating line and spaced therefrom, anti-friction supporting means. mounted along and around said insulated heating line at intervals substantially throughout its length to support and permit longitudinal movement of the central pipe and heating line as a unit inside said outside casing, said central pipe and heating line being attached to said jacket casing only at the extreme ends of said casing, and said central pipe and heating line being prestressed so that they are under substantial compression at their normal temperature of operation. 7

2. The composite piping arrangement of claim 1 where-- in the anti-friction means are rollers mounted in housings, which housings are separated from the central pipe line by rigid insulation serving also to support said pipe line, the remainder of the insulation being non-rigid insulation of high efliciency.

3. A composite pipeline for conveying molten material that is solid in its natural state and capable of being melted by the'application of heat, said pipeline being designed to convey said molten material for a distance of several miles in a-straight line without the use of any expansion joints, said pipeline comprising lengths of pipe joined end to end to form a continuous outer casing, and an inner assembly with the inner assembly being attached to the outer casing only at the extreme ends of the entire pipeline and said assembly being otherwise freely movable inside and longitudinally of said outer casing, said inner assembly comprising lengths of pipe joined end to end to form a central pipe for conveying the molten material and being slidably supported inside a second pipe ,means for permitting free longitudinal movement of said entire inner assembly inside said outer casing, said outer casing being held under substantial tension at ambient temperatures, means for pumping molten material through said central pipe, and means for flowing a heating liquid through the space between saidcentral pipe and said second pipe in the same direction as the flow of said molten material through said central pipe.

4. A composite pipeline as defined in claim 3 in which a return pipe for the heating liquid is attached to the outside of the outer casing and connected at the ends of the pipeline to the space between the central pipe and the second pipe to provide a closed circuit for continuously circulating said heating liquid.

5. A composite pipeline for transporting a hot liquid for a distance of several miles while maintaining the temperature thereof substantially above the ambient temperature which comprises, an outer casing extending in a substantially straight line, an insulated assembly of pipes inside said outer casing and spaced therefrom, one pipe of the assembly carrying the hot liquid and anotherpipe of the assembly carrying an auxilliary heating fluid, said insulated assembly of pipes except at the ends of the pipe line being supported on anti-friction means inside said outer casing and completely free to move longitudinally relative to each other and relative to the outer casing, said inner assembly of pipes being anchored only at each end of the pipeline to the outer casing after being expanded to a length about 50% to of the total length to which such assembly would normally expand when heated to the temperature at which the hot liquid is transported, whereby said inner assembly is under substantial compression when the pipeline is transporting the hot liquid and is under substantial tension when the pipeline is cooled to or near the ambient temperature, and whereby said inner assembly of pipes can be readily cut free to relieve stresses whenever the pipeline is cooled to ambient tem peratures. 6. A composite pipeline as defined in claim 5 in which the outer casing is prestressed in tension and buried in soil before the inner assembly of pipes is stressed or heated to the temperature at which the hot liquid is transported.

References Cited by the Examiner UNITED STATES PATENTS 2/12 Roberts l37l3 1,287,878 12/18 Carmichael 262-3.1 1,293,902 2/19 Peters 262-31 1,528,822 3/25 Gilchrist l37l3 2,130,306 9/38 Lintern -134 2,531,658 11/50 Walsh 138-448 2,551,867 5/51 Bond l7428 X 2,650,801 9/53 Collito 165164 2,683,592 7/54 Birney 165143 2,706,496 4/55 Bond 138-113 2,707,095 V 4/55 Parsons 165-135 2,830,548 4/58 McElvany 111-5 2,859,717 11/58 Cummings 111-5 2,903,307 9/59 Peters et a1. 308-6 2,924,245 2/60 Wilson 2623.1 X

CHARLES SUKALO, Primary Examiner.

ISADOR WEIL, PHILIP ARNOLD, HERBERT L.

MARTIN, PERCY L. PATRICK, ROBERT A. OLEARY, Examiners. i

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,169,576 February 16, 1965 Clarence 0. Lee et a1. It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 5, line 36, for "receive" read relieve Signed and sealed this 3rd day of August 1965.

(SEAL) Attest:

ERNEST W. SWIDER EDWARD J. BRENNER Altcsting Officer Commissioner of Patents

Claims (1)

1. A COMPOSITE PIPING ARRANGEMENT FOR CONVEYING HOT LIQUID MATERIAL LONG DISTANCES WHICH COMPRISES A CENTRAL PIPE FOR CONVEYING THE HOT LIQUID, AN INSULATED HEATING LINE LARGER THAN AND SURROUNDING BUT UNATTACHED TO SAID CENTRAL PIPE THROUGH WHICH HOT FLUID CAN BE CIRCULATED TO MAINTAIN THE HOT CONDITION OF THE LIQUID IN SAID CENTRAL PIPE, AN OUTSIDE JACKET CASING SURROUNDING SAID HEATING LINE AND SPACED THEREFROM, ANTI-FRICTION SUPPORTING MEANS MOUNTED ALONG AND AROUND SAID INSULATED HEATING LINE AT

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