US2788637A - Underground storage systems and improved method of operating - Google Patents

Description

April 16, 1957 G, R BENZ 2,788,637i

. UNDERGROUND STORAGE SYSTEMS AND IMPROVED METHOD OF OPERATING Filedy Deo. 4, 1952 3 Sheets-Sheet l AT @NED/S April 16, '1957 2,788,637

G. R. BENZ UNDERGROUND STORAGE SYSTEMS AND IMPROVED METHOD OF' OPERATING Filed Deo. 4, 1952 3 Sheets-Sheet 2 g BY awPgIV;

AMM #JY April 16, 1957 Filed Dec. 4, 1952 G. R. BENZ 2,788,637 UNDERGROUND STORAGE SYSTEMS AND IMPROVED METHOD OF' OPERATING 3 Sheets-Sheet 3 A.United States Patent 0 r :UNDERGROUND STORAGE 'SYSTEMS A-N) `IMPROVED METHOD OF OPERATING George (R. Benz, Bartlesville, tOltla., assignor to Phillips Petroleum Company, a'corporation of `Delaware Application December 4, 1952Serial No. 324,074 9 Claims. (Cl. lf2-h1) This invention relates to an improved method of operating an underground storage system. In one of its aspects this 4invention relates to a novel underground `storage system.

Constantly expanding production of liquefied petroleum .gas has created a definite problem in providing suit- .lable storage facilities for this material. Due to the high vapor pressure of liquefied petroleum gas, particularly propane, the cost of storage in surface equipment, such as steel tanks, becomes excessive due to the massive construction required to withstand the vapor pressure of the stored material in `a safe manner. This problem becomes lextremely -acute where it is necessary to store large quantities of such 'materials during the off season. .In addition to the expense involved, the use of steel tanks is limited by shortages in production.

In order to overcome these difficulties it has been proposed to "store liquefied petroleum gas in porous waterbearing for-mations, in water-leached Caverns, in salt formations, -or .in abandoned mines in impermeable shale or llimestone formations. Further, underground concrete storage tanks and buried sections of pipe have been used to a limited extent inthe storage of liquefied petroleum gas.

It iswell known that a liquefied gas can be forced AVfrom a chamber by introducing compressed gas above the liquid. This method is widely used in unloading LPG "ttik cars. Vapor is"withdrawn yfrom the storage tank, compressed and` pumped in'to the vapor space of the tank car. VThus' liquid i's forced `from the tank car into "the stofage tank through a connecting line. A similar system "is Shown in U. S. `Patent '2,021,394 in which LPG is 'forced from 'an underground tank toa Vcontainer on the surface. i

liapplying` thiss'ystem to a large underground storage mine, however, a large investment in compressors and prime movers" is required due to the large amount of vapor that must be compressed in order to start the flow of fluid` to Ythe surface, andthe operation is inefficient 'due to -large heat losses to the surrounding earth. It is to overcome these two disadvantages that the present 'inventionis directed.

"il-.n accordance with this invention Van underground storage system for liquefied gases is provided which is capable of storing 'extremely large quantities of this maferial yat a very Asmall unit cost. Further., yin accordance with this invention an improved method of operating 'underground storage systems is provided whereby savings are effected in the amount of vapor which `must be compressed in fthe removal of liquefied gas from storage, and a lessening of Vheat loss to the surrounding earth is effected. The, storage system of my invention is not limited necessarily-to :the -storage of liquefied petroleum gas, but is .applicableto :the storage of liquefiable materials which do not atectand are not affected by the material of the cavern walls,A .as `for example, ammonia and the like.

.lt-israrlobject:of` this .invention to provide underground storage facilities of novel construction and arrangement,

2,788,637 Patented Apr. V16, 1.957

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said facilities providing storage at a minimum unitcost. lt is a further object of this invention to provide an improved method of operating yan underground storage system.

It is afurther object of this invention to provide a system in which liquefiable material can be easily introduced into the storage system and efficiently removed therefrom, and which provides safety from bomb attacks, and increased protection against fire.

It is yet another object of this invention. to provide au underground storage system capable of storing liquefied gases, such as propane, having a high vapor Apressure for an extended period with a minimum of operating dithculties.

Various other objects, advantages and features yof the invention will become apparent from the following detailed description taken in conjunction with the accompanying drawings, in which:

Figure l is a perspective View partly in section of one embodiment of my invention employing two compressors;

Figure 2 is ya perspective view partly in section of another embodiment of my invention employing a single compressor;

Figure 3 is a perspective view partly in section of a third embodiment of my invention employing two smaller Caverns in conjunction with a plurality of large main storage Caverns.

Referring now in detail to Figure 1 of the drawing the large caverns are divided by walls 10 and 11 into large chambers 12 and 13 and small chambers 14 and 15. The lower regions of large chambers 12 and 13 are connected with smaller chambers 14 and 15? by means of conduits 16 and .17 controllable from the surface by means of remotely controlled valves 20 yand 21, respectively. The upper regions of chambers 12 and 13 are connected with the upper regions of smaller chambers 1d and 15 by means of conduits 22 and 23 controlled by means of remotely controlled valves 24 and 25 respectively. The smaller chambers are separated from access shaft 26 by walls 27 and 28. The large chambers 12 `and 13 can be lled from pipeline connections 30 and Si through vertical filler pipes 32 and 33. The filling of the large chambers from the pipe line connections 30 Vand 31 can be controlled by means of valves 34 and 35, respectively.

In accordance with my invention the underground storage system can be operated cyclically. Assuming that small chamber i4 has been filled or partially filled with liquid from large chamber 12, liquid from small chamber 14 is forced to the surface through conduit 36 by means of` vapor withdrawn from small chamber 15 via lines 40, 4l, 42 and 43 through valves 39, 44, 45 and 46 which is pumped by compressor 56 to the upper region of smaller chamber 14 by means of lines 51 and 52 through valve 53. During this operation valves 21 and 24 will be closed and valves 20 and 25 open during which time liquid in larger chamber 13 may be allowed to flow through conduit 16 and valve 20 into smaller chamber 15. Normally this filling will be effected by gravity flow, until the level of liquid in small chamber 15 is equal to the level in large chamber 13. As an alternative method of operating the filling step, valve 25 may be kept closed andthe level of liquid in small chamber 15 allowed to rise above the level in large chamber 13 by virtue of the suction exerted upon the surface of liquid in smaller chamber 15. However, when operating in such a manner extra Work is required of compressor Sli once the level of liquid in the small chamber is equal to that in the large chamber.

By `the system of conduits shown in Figure `1 it is possible to withdraw vapor from larger chamber 13 exclusively, if for some reason it is not desired to till the 3 small chamber 15. In such a case valves 20 and 25 would be closed and vapor would be withdrawn through lines 33, 54, 55, 41, 42 and 43 through valves 56, 57, 58, 60, 44, 45 and 46.

After small chamber has been filled in either of the manners hereinabove described and small chamber 14 emptied, liquid therein is forced to the surface through conduit 61 by means of vapor withdrawn from smaller chamber 14 via lines 52, 62, 42 and 63 through valves 3S, 64, 65 and 66 pumped by means of compressor 70 down to the upper region of smaller chamber 15 via lines 71, 55 and 40 through valves 6i) and 39. During this operation valves and 25 will be closed and 21 and 24 will be open thus permitting liquid from larger chamber 12 to ilow into smaller chamber 14 to till or partially till same in the manner hereinbefore described. Also, it is possible when emptying small chamber 15 to withdraw vapor eX- clusively from larger chamber 12 via lines 32, 72, 51, 62, 42 and 63 through valves 73, 74, 53, 64, 65 and 66.

Referring to Figure 2 ofthe drawing in detail, illustrated is another embodiment of my invention wherein a modication of the conduit system is employed and only a single compressor utilized. ln operating the underground system in accordance with this modification of my invention, it is possible while emptying smaller chambers 110 or 111 through lines 112 and 113 respectively, to withdraw vapor from any ofthe other chambers, large or small, in the storage system. Thus, assuming small chamber 110 to be filled or partially filled with liquid from larger chamber 114, vapor with which to pressure small chamber 110 can be withdrawn from larger chamber 114 via lines 115, 117, 118, 120, 121, 122 through valves 123, 124, 125, 126 and 127, and pumped by compressor 139, to small chamber 110 Via lines 131, 132, 133 and 134 through valves 135 and 136. During said operation remotely controlled valves 140 and 141 will be closed. Also, during said operation any activity desired in the other portion of the system, viz, `small chambers 111 and large chamber 142, such as lling of smaller chamber 111 by the opening of remotely controlled valve 143 and 144, or the lilling of larger chamber 142 from pipe line connections 145 through line 146 and tiller pipe 147 through valve 148, or even repairs to said chambers, can be effected.

When emptying smaller chamber 110 it is also possible to withdraw vapor in a manner analogous to that described in the description of the operation of Figure l, namely, withdrawing vapor from smaller chamber 111 via lines 150, 151, 121 and 122 through valves 152 and 127, during which time remotely controlled valves 143 and 144 will be open thus effecting a filling of smaller chamber 111 from liquid in larger chamber 142. Alternatively, vapor for pressuring smaller' chamber 110 can lbe withdrawn from larger chamber 142 exclusively via lines 147, 118, 126 and 122 through valves 153, 126 and 127.

When emptying liquid from smaller chamber 111, it is again possible to withdraw pressuring vapor from any of the other chambers in the system in a manner analogous to that employed when emptying smaller chamber 110. Thus, pressuring vapor may be withdrawn from large chamber 142 via lines 147, 117, 155, 156, 132, 157, 158, 161i and 122 through valves 153, 125, 124, 161 and 162. 'The vapor is pumped by means of compressor 13) through lines 163, 164, 165, 121, 151 and 156 through valves 166 and 152. Valves 143 and 144 will be closed during such operation.

Alternatively vapor for pressuring small chamber 111 may bc withdrawn from small chamber 110 via lines 134, 133, 132, 157, 158, 166 and 122 through valves 136 and 162 and pumped by compressor' 130 through lines 131, 163, 164, 165, 121, 151, and 159 through valves 166 and 152. During such operation valves 140 and 141 can be either opened or closed. 1f they are opened, tilling of smaller chamber 110 from liquid in larger chamber 114 can bc effected. lt is also possible, to fill larger chamber 4 114 from pipe line connection 170 through'lines 1'15 and valve 171,

Alternatively vapor for pressuring smaller chamber 111 may be withdrawn exclusively from larger chamber 114 via lines 115, 155, 156, 132, 157, 158, 160 and 122 through valves 123, 161 and 162, and pumped by compressor 130 to smaller chamber 111 via lines131, 163, 164, 165, 121, 151 and 150 through valves 166 and 152.

Referring now in detail to Figure 3 of the drawing illustrated is another modiiication of my invention wherein two small chambers 210 and 211 are used for emptying `a plurality of larger chambers 212, 213, 214, and 215. The bottom region of each of the larger chambers connects with the bottom region of each of the smaller chambers by means of manifold 216 and conduits 220, 221, 222 and 223, the llow through which is controllable by means of valves 224, 225, 226 and 227. Liquid from any of the chambers may be directed into either of the smaller chambers 210 or 211 depending upon whether valve 230 or 231 is opened. A venting conduit system is illustrated connecting the upper regions of each of the larger chambers with the upper region of each of the smaller chambers by means of manifold 232 and conduits 233, 234, 235 vand 236 the ow through which is controlled by means of valves 240, 241, 242 and 243. Liquid from either of the smaller chambers 210 or 211 passes to the surface through manifold 244 and line 245 depending upon whether valve 246 or 247 is opened. Manifold 250 connecting the upper regions of smaller chambers 210 and 211 connects with the surface by means of line 251 which in turn connects with the suction end of compressor 252 by means of lines 253 and 254. Vapor can be withdrawn from the upper region of either chamber 210 or 211 by opening either valve 255 or 256. Vapor is pumped by means of compressor 252 to the upper region of either of the smaller chambers 210 or 211 via lines 260, 261, 262 and manifold 263. Pressuring vapor is passed to either smaller chamber 210 or l211 depending upon whether valve 264 or 265 is open.

Each of the larger chambers connect with the surface by means of ller pipe 270, 271, 272 and 273 controlled by valves 274, 275, 276 and 277 respectively. These filler pipes are connected to a common manifold 280 which can connect to pipe line connections 281 and 282 controllable l by valves 283 and 284 and which connects with the suction end of compressor 252 by means of lines 285, 253, and

254 and controlled byvvalve 286. v

The methods of operating the underground storage system illustrated in this ligure are extremely variable. lt is possible by the arrangement shown't'o ll eitherof the smaller underground chambers from any of the larger chambers. When emptying either of the smaller charn bers vapor can be withdrawn from anyother chamber in the entire system, large or small. Thus, according to one method of operation, assuming smaller chamber 210 has been tlled with liquid from any of the larger chambers, liquid in said small chamber 210 is forced to the surface through manifold 244 and line 245 through valve 246 by means of vapor withdrawn from smaller chamber 211 via manifold 250, lines 251, 253 and 254 through Valve 256 by compressor 252 and passed to chamber 210 via lines 260, 261, 262, manifold 263 and through open valve 264. During such operation small chamber 211 may be lled from any of the larger chambers 212, 213, 214 0r 215. The appropriate valves and vents can be opened accord'- ingly. In operating in this manner it is possible to ll any of the large caverns from the pipe line connections'. Iln such case valve 286 would be closed. It is also possible by this arrangement to store liqueable gases of different compositions in a single underground storage system.

By the arrangement of smaller and larger caverns shown in this gure of the drawing, a saving inthe num ber of smaller caverns necessary is elected and greater flexibility of operation is obtained. Further, all valves which need be controlled are more readily accessible` for avancer maintenance since they can "be placed at the bottom of access shaft"2l90. p

`In the ldescription of the figures of the drawing it has been pointed out that it is possible vto 'till a larger cavern from the pipe line at Vthe saine tir'ne that liquid is being withdrawn from storage. At Vtimes the pipeline delivers LPG `faster than it can vbe used and `there is a net gain in storage, `while at other times 'little LPG is available from the `pipe line while 'thereis a llarge demand for the fuel, this demand being satisfied by reducing storage. The systems which are shown in the drawings will operate satisfactorily lunder varying 'conditions since the two operations, `filling and emptying, are `independent and can be carried out simultaneously at different rates.

The size` of thesmafller cavern len'tployed from which storage is reduced will vary depending upon many factors, such as, the size of a batchneeded during a single filling operation at the surface, the most efficient amount of gas that can be compressed in order to Ystart the flow of liquid to the surface, and the amount of surrounding earth which will 'reduce to `economic limits -the amount o'f heat loss in 'the pressuring operation. Comparisons between 'the size of the larger chambers `and the smaller chambers would not 'be helpful in view of the foregoing considerations and since the 'size of large 'underground storage Caverns are almost without limit. Most of the advantages of my invention are present merely if the chamber which is pressured is smaller -than the main storage cavern.

While my invention has been described in terms of its preferred embodiments those skilled lin the art will appreciate that many modifications can be made without departing from the spirit and scope of my invention as defined herein.

I claim:

l. In an underground storage system, in combination, a large underground storage cavern; a smaller underground dispensing cavern; valved conduit means connecting the upper regions of both cavems; valved conduit means connecting the lower regions of both Caverns; conduit means connecting the lower portion of said dispensing cavern with the surface; a filler pipe connecting the upper portion of said large cavern to the surface; and compressor means communicating with the upper region of said smaller Cavern and with a source of pressurizing gas to supply compressed gas into the space above the liquid level of the smaller cavern, the capacity of said compressor means being minimized due to the small heat loss through the walls of the dispensing cavern.

2. In an underground storage system, in combination, a plurality of large underground Caverns; an equal number of small underground Caverns paired with each of said larger Caverns; valved conduit means connecting the upper region of each of said larger and smaller Caverns; valved conduit means connecting the lower region of each of said larger and smaller Caverns; conduit means connecting with the lower region of each of said smaller Caverns and extending to the surface; liller pipe means connecting with the upper region of each of said larger Caverns and extending to the surface; and compressor means connected to pressure any of the smaller Caverns while withdrawing vapor from any of the other Caverns in the underground storage system.

3. In an underground storage system, in combination, an underground storage Cavern; means within said underground storage Cavern dividing same into a larger section and a smaller section; valved Conduit means controllable from the surface connecting the upper regions of said larger and smaller sections; valved conduit means con trollable from the surface connecting the lower regions of said larger and smaller sections; Conduit means Connecting with the lower region of said smaller section and extending to the surface; liller pipe means connecting with the upper region of said larger section and extending to the surface; and compressor means connected to pressure the smaller `section of said cavern `'while withdrawing Avapor 'lower region of each of said^sma1lersections and extending to the surface; filler' pipe means connecting with theupprer region of each of said larger sections and extending to the surface; va valved conduit system interconnecting the upper regions of all of the sections in the underground `storage system; and compressor means connectedlin 'said conduit system 'to pressure any `of the smaller sections of the underground storage Caverns whilewithdrawing vvapor from any ofthe other sections' in the'undergroundstora'g'e system.

5. In an underground storage system, in combination, two underground storage Caverns; `means dividing each of said Caverns into "a larger sectionand a 'smaller section; valved conduit means controllable Vfrom the surface connecting the upper regions 'of each of saidlarger and smaller sections; similar means connecting the lower regions of each of said larger and smaller sections; conduit means connecting with the lower region of each of said smaller sections and Iextending 'to the surface; filler pipe means connecting with the upper region of each of said larger sections and extending to the surface; a valved conduit system interconnecting the upper regions of all of said sections in the underground storage system and including said filler pipe means; one compressor connected in said conduit system to pressure one of said smaller sections while withdrawing vapor from the other smaller section or the larger section adjacent thereto; and] a second cornpressor connected in said conduit system to pressure the other smaller section while withdrawing vapor from said rst-mentioned smaller section or the larger section adjacent thereto.

6. In an underground storage system, in combination, a plurality of larger underground storage Caverns; at least two Caverns smaller than any of the larger Caverns; valved conduit means connecting the bottom region of each of said larger Caverns with each of said smaller Caverns; valved conduit means connecting the upper region of each of said larger Caverns with the upper region of each of said smaller Caverns; filler pipe means connecting the upper region of each of said larger Caverns with the surface; a valved conduit system interconnecting the upper regions of all of the Caverns in the underground storage system; and compressor means connected in said conduit system to pressure any of the :smaller Caverns while withdrawing vapor from any of the remaining Caverns in the underground storage system.

7. In a process for removing volatile liquid from storage in a large underground cavern by displacement with gas under pressure, said gas being in heat exchange relation to the surrounding earth and at a temperature above the temperature of the surrounding earth and the average temperature of sai-d volatile liquid in storage so that if said gas is applied under pressure to said large under ground cavern, large heat losses would result from said gas to the surrounding earth and to said volatile liquid in storage thereby tending to lower the pressure of said gas and hence its displacement eiliciency, an improved method of removing said volatile liquid whereby said heat losses from said gas are considerably reduced thus conserving the energy in said gas, which comprises transferring volatile liquid from said large underground cavern to an underground dispensing chamber communicating therewith and having substantially less volume and surface area and hence offering less opportunity for heat transfer to the surrounding earth than said large underground cavern and communicating from the lower portion assess? of said dispensing chamber to the surface of the earth, 'closing communication with said underground cavern,

and pressurizing said underground dispensing chamber with said gas thereby displacing volatile liquid from vsaid ydispensing chamber to the surface of the earth.

8. In a process for removing liquefied gases from storage in an underground cavern by displacement with pressurized gas, the improved method of reducing heat losses from said pressurized gas to the surrounding earth which comprises passing said liquefied gases from said underground cavern to a first underground dispensing zone having less surface area and volume than said underground cavern, withdrawing vapors from a second underground dispensing zone, allowing liquefied gases to ow from an underground storage zone to said second underground dispensing zone while said vapors are withdrawn therefrom, compressing said vapors, and passing said vapors thus compressed to said first underground dispensing zone thereby displacing said liquefied gases therein to the surface of the earth.

9. in a process for removing liqueed gases from storage in an underground cavern by displacement with pressurized gas, the improved method of reducing heat losses from said pressurized gas to the surrounding earth which comprises passing ysaid liquefied gases from said underground cavern to a first underground dispensing zone having less surface area and volume than said underground cavern, withdrawing vapors `from a second underground dispensing zone, allowing liqueed gases to flow from an underground storage zone to said second underground dispensing zone while said vapors are withdrawn therefrom, said second underground dispensing zone having less surface area and volume than said undergroundy storage zone, accumulating liquefied gases in said second underground dispensing zone, compressing said vapors, passing said vapors thus compressed to said tirst underground dispensing zone thereby displacing said liquefied gases therein to the surface of the earth, thereafter passing liquefied gas from said underground cavern to said first underground dispensing zone again, withdrawing gases from said first underground dispensing zone, compressing said gases, and passing said gases thus compressed to said second underground dispensing zone thereby displacing liquefed gases therein to the surface of the earth.

References Cited in the file of this patent UNITED STATES PATENTS 2,075,678 Von Langen Mar. 30, 1937 2,296,598 Cook Sept. 22, 1942 2,387,894 Fannin Oct. 30, 1945 2,433,896 Gay Jan. 6, 1948 2,670,605 Van Zandt et al. Mar. 2, 1954 FOREIGN PATENTS 435,080 Canada June 4, 1946

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