US2481051A - Process and apparatus for the recovery of volatilizable constituents from underground carbonaceous formations - Google Patents

Description

Sept, 6, M949.. L. c. UREN 2,481,05l

PROCESS AND APPARATUS FOR THE RECOVERY OF VOLATILIZABLE CONSTITUENTS FROM UNDERGROUND GARBVONACEOUS FORMATIONS Filed Dec. 15. 1945 2 Sheets-Sheet l Il Jl II u l y 5 j BY i 29 ATTORN Septu 6, 1949. L.. c. UREN PROCESS AND APPARATUS FOR THE RECOVERY OF VOLATILIZABLE CONSTITUENTS FROM UNDERGROUND CARBONACEOUS FORMATIONS Filed nec. 15, 1945 /ffrfi 6'. 'des/M BY A'r'ToR Y Patented Sept. 6, 1949 PROCESS AND APPARATUS FOR THE RE- COVE i OF VOLATI-LIZABLE CONSTITU- ENTS FROM UNDERGROUND CARBONA- CEOUS FORMATIONS Lester C. Uren, Berkeley, Calif., assignor to Texaco Development Corporation, New York, N. Y., a corporation of Delaware Application December 15, 1945, Serial No. 635,394

7 Claims. (Cl. 2GB-1) oil-shale, lignite, coal and the like. The inven-- tion contemplates a method of underground mining by which the source material is broken into fragments of suitable size and collected in underground rooms or stopes and in which the material collected in the stopes is subjected to distillation in situ. In accordance with the invention a gaseous fuel and air are directed into the stopes to effect retorting of the carbonaceous material and produce oil vapors and combustible gases which are withdrawn to the surface.

My process has a distinct advantage over the usual methods of producing oils and gases from oil shale and coal in that the process requires considerably less handling of the shale or coal and is consequently less costly. Furthermore, the process requires a minimum of timber and steel for mine supports, and in the case of oil shale, the spent shale is left in the stopes so that subsidence of the ground over and above the mine workings is prevented and the expense of spent shale disposal is avoided. The process is particularly adapted for the continuous, orderly and emcicnt exploitation of oil shale and certain types of coal deposits, permitting recovery of hydrocarbons vin the form of oils and combustible gases at minimum costi Moreover, it facilitates selective exploitation of the better grades of shale or coal in situations where the materials that may be mined profitably and treated are associated with barren or relatively low grade materials.

ln accordance with the invention a, combustion zone is established at the top of the mass of broken carbonaceous material in the stope and the products of combustion are withdrawn downwardly through the mass to thus establish a volatilizing zone beneath the combustion zone. The combustion zone is progressively moved downwardly with the result that the volatilizing zone is moved downwardly through the mass until the volatilizable constituents have been removed. The products of combustion together with the vapors and gases evolved fromthe carbonaceous material are withdrawn from the lower portion of the stope and the recovered products are brought to the surface.

The invention contemplates certain novel apparatus forl directing air and fuel gas to the stopes and for withdrawing the evolved products comprising an outer tube and an inner conduit telescoped or mounted within the outer tube for longitudinal translation therein, with air and gas ports in the inner conduit adapted, upon translation thereof, to register with ports in the outer tube so as to discharge air and gas 'at predetermined levels into the broken mass of carbonaceous material, while the lower ports of the outer tube serve to receive the combustion gases and evolved vapors and gases from the carbonaceous material which are being withdrawn from the stope.

In the following description of the process, it is applied to a deposit of oil shale consisting of a series of compact, argillaceous strata some hundreds of feet thick, for example, and containing variable amounts of kerogen which on application ofheat may be converted into shale oil and hydrocarbon gases, carbon monoxide and other gaseous products.

Access to the stratigraphic horizon in which the mining is to be done is by means of a mine shalt or adit tunnel from which mine drifts and raises may be driven under, over and through the body of source material selected for treatment. Waste material and excess shale produced in the driving of the drifts and raises and in stoping operations are removed to the surface through the shaft or adit tunnel. The invention has in view long range plans for mining operations over a large area from a central shaft about which facilities will be grouped, so as to provide for a systematic exploitation which will result in recovery of a maximum percentage of the material that can be profitably produced. Operations are conducted in a series of stopes or rooms within the body of source material of such size and shape as will result in the most eilicient operation of the process. Each stope is a production unit, the process being applied to each of the stopes in turn. For the purposes of this description, it will therefore be sumcient to describe in detail the application of the process to a single stope.

'The accompanying drawings show apparatus adapted for the practice of the invention and constituting an embodiment thereof, wherein:

Fig. i is a general diagrammatic plan view showing a plurality of stopes operated from a single shaft. l

Fig. 2 is an enlarged horizontal sectional view of a single stope taken on the line 2 2 of Fig. 3.

Fig. 3 is a vertical section taken on the line 3 3 0f Fig. 2.

Fig. 4 is a detailed partial section of a pipe unit for supplying air and gas to the stope and for removing the volatilized products.

Fig. 5 is an elevation of such pipe unit.

Referring to the drawings. levels or main haulage ways I and 2 are driven from shaft I. The levels are, for example. 150 feet apart, one being vertically above the other. At each level, the main haulage ways I and 2 are so disposed as to block out and provide access to the areas in which the stopes l are to be formed. Assuming the stopes 4 to be about 100 feet square in cross-section and 100 feet high. the distance between broken material being drawn through chutes into drifts below to leave suitable head room between the back and the top of the broken rock. In' this method of stoping, approximately 1/3 of the rock may be withdrawn and $5 remains in the stope.

From main haulage ways I and 2, cross drifts il and l are driven to provide access to the top and bottom of the stope. A plurality of chutes 8 are driven upwardly from the cross drifts S. As the work proceeds, surplus shale is trammed through the cross drifts 6 and haulage way I to the shaft 3 and hoisted to the surface. are -preserved through the broken shale while stoping is in progress in order to gain access to the working back, but these raises are nally filled with broken shale when the stoping operation is completed.

As stoping operations proceed, a plurality of vertical pipes I composed of short length sections are installed through the broken shale extending from level I to level 2. These pipes are 'preferably disposed in a corner of each chute 8 so that they will not'interfere with the withdrawal of broken shale. These pipes may conveniently be of 8 inch to 12 inch diameter. The stope is excavated upwardly to within about 2 5 feet of the floor of upper level 2 and the pipes i0 are extended up into level 2 from the roof of the stope through holes drilled from the upper level in positions accurately located by survey methods so that they' are vertically above the pipe positions in the stope below.

As shown in Fig. 5, the upper and lower ends of each of the pipes I0 is closed by a packed gland II through which a smaller diameter pipe I2 of, for example, 2 inch diameter passes with a gastight sliding contact. Each pipe I2 is made up of short sections and carries a piston I3 (see Fig. 4) which fits snugly withinthe surrounding pipe I0, but is capable of sliding thereon without excessive friction. The piston provides a barrier through which gases may not pass either inside the tubes I2 or through the annular space between the two tubes. The piston is formed with a chamber I4 at the upper end thereof and with a chamber I at the lower end thereof. Chamber I4 is adapted to receive gases from the upper section of pipe I2 and chamber I5 is adapted to receive gases from the lower section of pipe I2. Chamber I4 is provided with ports I6 and chamber I5 is provided with ports Il. The outer pipe I0 -ls provided with ports I8 spaced longitudinally Raises 9 are withdrawn from the at uniform intervals so as to register with the ports I! and II of the chambers-Il and Il. Thus when the position of the piston is accurately adjusted, compressed air may be passed down through the upper section of tube I2, thence into the chamber I4 and through the ports I6 and Il into the surrounding mass of broken shale. Simultaneously, a combustible'gas such as producer gas may be forced upwardly through the lower section of tube I2, thence into chamber II and through the ports." and I8 into the surrounding broken shale. Air and fuel gas meeting within the pore spaces of the shale body -is ignited and by supplying the air and gas in suitable proportions, combustion is maintained. By lowering the tube I2 and piston I3 mounted thereon from one set of ports to another combustible gas may be caused to burn at successively lower elevations in the surrounding shale body. As the tube I2 is lowered, short sections are added at the top in drifts 1 and detached at the lower end in drifts 8.

At the upper end of each pipe I2 a lateral connection I9 is provided for the introduction of compressed air and at the lower end of each pipe I2 a lateral connection 20 is provided for the introduction of a combustible gas from a suitable source, such for example as recycled gas which is hereinafter explained. At the lower end of each pipe I0 a lateral outlet 2| is provided for removing products of combustion and the products volatilized from the shale. The several outlet pipes 2i are connected through piping 22 to a vacuum pump 23 and condenser 24 which discharges into a tank or sump 25 which serves as an oil and gas separator. Thus as air is supplied through connection I9 to the upper section cf pipe l2 thence through chamber I4 and ports I6 and I8 and as combustible gas is supplied through connection 2li to the lower end of pipe I2 thence through chamber I5 and ports I'I and I8 combustion takes place in the shale body and the products of combustion and volatilized products from the shale are drawn in through ports I8 in the pipe i0 below the piston I3 and flow through the pipe III, thence through connections 2| and piping 22 to the vacuum pump 23 and condenser 24 and are discharged into the sump 25. Gases ump 25 through a suction line 26 by a compressor 21 which delivers the gases to the surface through-a line 28 which extends upwardly through the shaft 3. The line 28 is provided with a branch line 29 which communicates with the pipes 20 so that a portion of the gases may be recycled to the stopes to support combustion in the shale oil body therein.

The liquid products collecting in the sump 25 are withdrawn by a pump 30 and discharged to the surface through a line 3i extending upwardly through the shaft 3.

-When the stoping operation is completed in a given stope all openings into the stope except those through the control pipes are closed with cement'so that no gas leakage will occur. Fireproof bulkheads 32 may be built at the entrance of the chutes 8 beneath the stope. and around pipes' in the bore holes in the overlying drifts. 1. For added security, fire doors may be constructed at the entrance to all cross drifts 6 and I where they connect with the main haulage ways I and 2. Compressed air is introduced through a line 33, thence through connections I9 to the upper end of each of the pipes I2 and fuel gas either from sump 25 or from other source is admitted through connection 20 to each of the lower ends of the tubes i2. Vacuum pump connections are established with the lower end of each tube Il for withdrawing the shale oil vapors and gases and products of combustion from the annular spaces between the tubes i and I2.

The piston i3 is initially adjusted so that the iuel gas and air are discharged through ports in the tubes it at the top of the stope. A burning taper or small bundle of oil-saturated waste may be lowered from the upper end of tube i2 into chamber i4 in a gentle stream of compressed aire which will serve to ignite the fuel gas in the surrounding broken shale. Thereafter the ilre will be maintained as long as air and gas in suitable proportions are supplied. Combustion of the shale itself will take place in varying degree depending upon the amount of organic matter it contains. Once ignited, the richer shale will burn without the aidof combustible gas, ii air is supplied.

Combustion is thus initiated in the shale body across the entire top of the stope. the products of combustion are drawn downwardly through the broken shale through the ports it in the tube l! and thence through the tubevl and connections ti and piping 22 to the vacuum pump 23. Heat from the burning shale creates a zone of distillation in the shale immediately below (see Fig. 4). Kerogen in the shale is converted into oil vapor, hydrocarbon gases and water vapor by the heat of the burning overlying body of shale. The products of combustion flow downwardly and mix with these gases and vapors and all are withdrawn together through the lower tubes it. As the retorting proceeds the zone of retortlng, followed closely by the zone of burning shale. progresses downwardly through the shale body. The oil L onstituents are largely distilled from the shale beiore the :dre reaches it, the rc being sustained largely by the burning of ilxed carbon left in the spent shale. The air supply is controlled so that combustion is relatively slow and the products. of combustion from the fire zone are largely carlmn monoxide. From time to time or even continuously when necessary, fuel gas is introduced to the re none to maintain combustion. Finally, when the `lire zone reaches the lowerrnost shale layer in the bottom of the stope, the retorting process is complete. Steam may then be admitted to the heated spent shale from the upper levels i through the compressed air connections for tubes l2. Steam in the presence of incandescent carbon of the spent shale is in part converted into hydrogen, carbon monoxide and methane. Recovery or ammonia is also promoted through the use of steam.

The gaseous and vaporous products evolved irom the shale together with the .products oi combustion are withdrawn from the stope by the vacuum pump 23 and directed through condenser tt to the tank 25. Condensed oil and water are pumped to the surface by means of pump tu and the fixed gases are directed by the compressor 2 to points of utilization at the surface, except such gases as may be utilized as fuel to support combastion in the stopes.

The air supply to the burning shale in the stcpes is preferably adjusted so that the fire zonev will proceed slowly down through the shale mass.

. Thus, for example, in burning through a 100 foot stope of broken shale, a period of a week or more may be employed. Appropriate tests should be made to maintain an approximately horizontal and uniformly descending nre zone throughout the cross section of the stope. Thus, thermo- 6 couples may be placed in the pipe pistons i3 with wire connections to indicating apparatus in the upper drifts 1. Gas analysis of the products evolved at the lower end of the tubes l0 will also indicate the character and progress of combustion inthe shale mass.

With rich shales and coals the retorting operation may result in some, encroachment of the zone o! combustion into the walls, roof and bottom of the stope. This is advantageous in that it will add to the vapors and gases evolved and can do no harm so long as the zone .of combustion does not extend to the vicinity of the control drifts C and l.

The pillars 5 left between the stopes serve to protect against any too extensive encroachment of the ire zone. In the event of any burning of the pillars, the burning may be brought under control by sealing all outlets, excluding air. and if necessary. introducing water.

Although a preferred embodiment of the invention has been described herein, it will be understood that various changes and modiiications may be made therein, while securing to a greater or less extentsome or all of the benefits of the invention. without departing from the spirit and recting air and fuel gas to the top of the mass of carbonaceous material and initiating combustion at the top of the material, maintaining a down-draft on the products of combustion to thereby establish a volatilizing zone beneath the combustion zone, progressively moving the combustion zone downwardly through the mass .to thereby progressively move the volatilization zone downwardly through the mass and withdrawing the products of combustion and the volatilized constituents from the bottom of the stope.

2. Apparatus for recovering volatilizable constitutents from underground formations oi' carbonaceous material comprising an outer tube adapted for access to the formation and provided with a plurality oi' longitudinally spaced ports, a conduit telescoped within said tube for longitudinal translation therein and formed with separate sections for conveying airand fuel gas. a plurality ofports in each section of said conduit adapted upon translation thereof to register with the several ports in said outer tube.

3. Apparatus for recovering volatilizable constituents from underground formations of carbonaceous material comprising an outer tube adapted for access to the formation and provided with a plurality of longitudinally spaced ports,

an inner tube of smaller diameter than the outer tube and formed of two sections, an enlarged chamber for each of said sections adaptedv to t snugly within the outer tube and capable of translation within the outer tube, ports in each of said enlarged chambers adapted upon translation thereof to register with ports in said outer tube.

4. Apparatus for recovering volatilizable constituents from underground formations of car-` bonaceous material comprising an outer tube adapted for access to the formation and provided with a plurality of longitudinally spaced ports, a piston adapted for translation within the outer tube and formed to provide a pair of separate chambers, ports in said chambers adapted upon translation within the outer tube to register with ports m the outer'tubean inner tube or smaller diameter than the outer tube extending within the outer tube and communicating with one o! j said chambers to supply air thereto, a second inner tube of smaller diameter than the outer tube extending within the outer tube and communicat- `ing with the' other chamber to supply fuel gas thereto and means for withdrawing products from the annular spacewithin the outer tube.

5. The process of recovering volatllizable constituents from underground formations of carbonaceous material which comprises forming a stope in the formation containing the carbonaceous material'in fragmentary form, initiating combustion at'the top of the material, maintaininga down-draft on the products of combustion to thereby establish a volatilizing zone beneath the combustion zone, progressively moving the combustion zone downwardly through the mass to. thereby progressively move the volatilization zone downwardly through the mass and withfdrawing the products of combustion and the volatlzed constituents from the bottom of the stope.

6. The process of recovering volatilizable constituents from underground formations of carbonaceous material which comprises for a stope in the formation containing the carbonaceous material in fragmentary form, introducing air at the top of the material and initiating com# bustion, maintaining a down-draft on the products of combustion to thereby establish a volatilizing zone beneath the combustion zone, introducing air atprogress'ively lower points in the mass ing air and gas at the top of the material and initiating combustion, maintaining a dorm-draft on the products of combustion to thereby establish a volatilizing zone beneath the combustion zone. introducing air and gas at progressively lower points in the mass of material and progressively moving the combustion zone downwardly through the mass to thereby progressively move the volatilization zone downwardly through the mass and withdrawing the products of combustion and the volatilized constituents from the bottom of the stone.

ille of this patent:

STATES i Number Name Date 1,842,098 Howard Jan. 19, 1932 1,919,636 Karrick July 25, 1933

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