US2723225A - Shale retorting method and apparatus - Google Patents

Description

Nov. 8, 1955 K. M. ELLIOTT SHALE RETORTING METHOD AND APPARATUS Filed Sept. 13, 1951 fry/W 5y/#Lf H 7' TOR/VE Y 2,723,225 Epatented Nov. 8, 1955 United States Patent @Ence SHALE RETORTING METHOD ANTI) APPARATUS Kenneth M. Elliott, Woodbury, N. J., assigner to Socony Mobil OilCompanyJnei, a@ corporation, of N ew York Application September 13, 1951, Serial No. 246,462`

9 Claims. (Cl. 202-6) This invention relates to'- ay method and apparatus for obtaining valuable hydrocarbons from` shale and; the like. More particularly, the present invention is-.concerned with an improved process and apparatus: in which shale is retorted in an eiicient manner rutilizingthe coldk shale feedl as a medium for effecting condensation' of oil vapors emitted upon roasting the shale.

It is common practice in the art to. recover oils from solid oil-bearing or oil-producing materials ands particularly to recover shale oil from oil shale. As is well recognized, ordinary oil shale does not contain oil assuch but a solid bitumen type material known asl kerogen which, when heated, breaks down into gases, petroleum-like liquids, and carbon.

The recovery of oil from oily shalehasheretofore been accomplished by heating the shale at; elevated-- temperatures suiiicient to educt the oil and separate it from residual mineral matter. However, commercial: shale retorting operations previously employed have been generally cumbersome and` expensive, involving large equipment and operating costs per unit ofL shalev throughput.

vimportant factors contributing to these economic burdens have been poor heat recovery in thelretort systems, and

the expense, equipment, and timei'consumedin subsequently recovering the products of retortation.

A major object of this invention, accordingly, is the provision of a method and apparatus inwhichV oil shale and the like may be efliciently retorted without the excessive heat loss which has been. generally prevalent in the processes and equipment heretofore used. A further object is to provide amethod and apparatusfor retorting oil shale wherein intimate contact betweenvaporous shale oil products and condensed liquidl shale oil is obtained. A still further object is the provision of a compact; apparatus for retorting oil shale affording convenient means for subsequent recovery of. the liquid shaleoil. These and other objects which will be apparent to those skilled in the art are accomplishedl in accordance with the present invention. f

`Operation of the process and apparatus` described herein comprises the continuous passage of crushed shale downwardly as a solid movingbed'through an elongated vertical vessel having a condensing zone wherein gaseous products rising from a lower retorting zone ofsaid vessel undergo condensation While flowing countercurrently to said solid moving bed, said crushed shale and gaseous products passing through'a zone of said vessel intermediate said condensing and said retorting zones in which a gas seal is maintained by the introduction of a= stream of an inert gas in an. amount suicient to prevent the downward iiow of condensed liquid shale oil therethrough without substantially inhibitingl thev downward passage of crushed shale.

It has been found, in accordance with the present invention, that the provision ofk a gas seal by introduction of a high velocity stream of inert gas between the retorting and condensing zones of a shale retort wherein shale oil is condensedk on cold` shaley feed provides an effective means for supporting andV maintainingfthe liquid' shale oilso obtained in the condensingzone of the retorting vessel and thus preventing its downward flow by gravity intocthe retorting zone of said vessel; The gaseous stream conducted to the gas seal zone may be any gas inert under the operating conditions of the retort. Typical examples of suitable gases are flue gas, steam, and nitrogen. The gas seal zone may also be maintained by the introduction at, a point intermediate the condensing and retorting zones of a liquid capableofI ashing to an inert vapor under the temperature-conditions maintained inthe retort. A-particularly feasible liquid for such purpose is water. In a preferred embodiment,` of` the invention, the-gas seal Zone is provided by recycling a stream of ,retorty gas withdrawn from the, upper portion ofthe retorting vessel and introduced at a point intermediate the retorting and condensing zones thereof.V lt will; be under,- stood that the amount and velocity of gas introduced into-the gas seal zone of the shale retorting vessel employed herein is such as to prevent condensed shale oil from passing into the retorting zone of the vessel but insufficient to prevent the downward passage of crushed shale therethrough.

The invention may be further understood by reference to the attached drawing, which represents a schematic arrangement of apparatus for carrying out the process of the invention. Referring more particularly to the drawing, cold, crushed, raw oil shale is introduced into hopper 10. The shale moves by gravity from hopper 1) through feed leg 11 provided with a Asuitable flow control means not shown and passes into the upper portion of retorting vessely 12. A. gas, such. as flue gas or steam,` is desirably introduced into feed leg 111 through conduit 13 to forestall the upward ow of gaseous. retort products therethrough. As the shale descends; through the retorting vessel, it passes rst through a condensing zone where liquid shale oil condensed from gases. generated during retorting is collected in .av relatively static pool. The liquid product, together withV noncondensable gases, is withdrawn from this pool through outlet pipe 14. leading to a liquid-gas separator 15. Liquid shale oil collects in, the bottom of separator 15 and is withdrawn therefrom through draw-off pipeA 16. Non-condensable gases are removed from separator 15 through pipe17. A b afe 1S is affixed to the interior wall of retorting.l vesself12, overlying the outlet connection lof pipe 14, to prevent entrainment of granular, solid shale particles in the product oil. y

The descending shale, now wet with shale oil, passes from the condensing zone of retorting vessel 12, through a gas seal zone into which a high velocity gas stream, is conducted through conduit 19. The amount and velocity of gas passing upwardly through the gas seal Zone is such as to prevent the downward flow of condensed liquid shale. oil but insuicient to prevent the downward passage of crushed shale. As set forth hereinabove, the stream conducted to the gas seal Zone through conduit 19.may. be, any inert gas or liquid capable of flashing to inert vapor under the temperature conditions maintained in the retort. In a preferred lembodiment of the; invention, a stream of retorting gas is withdrawn froml the upper portion of the gas seal Zone through outlet` pipe. 20. A baffle plate 21 aiixed to the interior wall of the retort overlying the outlet connection` of pipe 2G. prevents withdrawal of granular solid shale particles at this point. After separating any liquid shale oil from' said stream in liquidgas separator 22, the gas. is passed through conduit 23 to blower 24 and then recycled under pressure to the retorting vessel through pipe 19. Shale oil which collects in separator 22 is removed from the bottom thereof through outlet pipe 25. Instead of employing recycle gas, water may beI introduced throughv conduit 1.9 by means ofA pipe.

26 and sprayed into the retorting vessel, the resulting steam providing the high velocity gas required in the gas seal zone. It is also within the purview of this invention to jointly employ a stream of recycle gas and water to provide the high velocity gas stream required in the gas seal zone. Likewise, other fluids or mixtures thereof which are inert under the operating conditions of the retort may be employed in providing the desired gas seal.

The downwardly moving shale is further heated in the gas seal zone by countercurrent heat exchange with the hot vapors rising from the retorting zone immediately below. As the rising hot vapors give up their heat to the descending shale passing through the gas seal zone, the condensable portion of the vapors is liquicd. It is for the purpose of minimizing the natural downward flow of this condensate and of preventing the pool of liquid in the overlying condensing zone from flowing down into the retorting zone that the above-mentioned gas seal zone is maintained at a point intermediate the condensing zone and retorting zone.

Upon emerging from the gas seal zone, the preheated shale continues its downward passage through a retorting zone and a burning zone wherein it is contacted with an oxygen-containing gas, such as air, introduced through conduit 27. Upon contact of the oxygen-containing gas with hot shale, residual combustible matter is burned from the shale, thereby providing the heat required for retorting. The combustion products flow upward in admixture with the vapors resulting from decomposition of the kerogen content of the shale and said combustion products ultimately leave the top of retorting vessel 12 along with noncondensable retort gas and liquid shale oil through outlet pipe 14.

The hot shale flows downwardly from the burning zone and is further cooled by the introduction of a cooling medium such as water, steam, or the like, suitably introduced through conduit 28 provided with control Valve 29.

For initially heating the shale, hot flue gas is introduced through conduit 30, Valve 29 being closed and valve 31 being open. After operation of the retort is begun, valve 31 is closed and valve 29 is opened as the introduction of cooling medium is desired. Spent shale flows out the bottom of retorting vessel 12 through outlet pipe 32, the

rate of llow being conveniently controlled by valve 33. The introduction of a cooling medium is not considered essential to successful operation of the instant retort but is advantageous in that it assists in upward transfer of heat to the retorting zone and further provides a seal by some downward leakage on outlet pipe 32, thereby serving to facilitate the desired upward movement of gaseous retort products.

It is essential in accordance with the present method of operation that a gas seal zone be maintained intermediate the retorting zone and condensing zone and that the velocity and amount of gas introduced into the gas seal zone be such as to prevent the downward flow of liquid shale oil through the retorting vessel while permitting crushed shale to pass downwardly through the retorting vessel. The gas seal zone further serves the purpose of affording a heat transfer zone where the product gases are cooled and cold descending shale is preheated.

The amount of gas introduced to the gas seal zone should, in addition, be correlated with the cross-sectional area of the retorting vessel employed. The vessel utilized in the present process has a cross-section substantially uniform throughout the condensing, gas seal and retorting zones thereof. As will be realized, the larger the crosssectional area of the retorting vessel employed, the greater is the quantity of gas required to maintain the desired seal. In general, it is preferred to introduce the high velocity gas stream to the gas seal zone in a uniform manner through a plurality of nozzles spaced at predetermined intervals extending horizontally across a section of the retorting vessel.

Various other modifications and refinements of; the.' i013?- going process may be made, depending largely upon the nature of the shale oil product desired. Thus, in some instances, it may be desirable to control the heat release during combustion by adjustment of the incoming stream of air or other oxygen-containing gas to cause the condensing zone to operate at a temperature suiciently above the pour point of the product oil to prevent deposition of wax or other solid hydrocarbons in said condensing zone. Also, it may be advantageous in some instances, where the presence of water in the retort is considered detrimental, to preheat the raw shale being introduced into hopper 10 to a temperature above the dew point of the retort gas to obviate possible condensation of water in the condensing zone.

In practice of this invention, the shale is suitably crushed. The preferred size should pass a 2-inch mesh sieve and be retained on a 1t-inch mesh sieve. However, crushed shale outside of this preferred mesh size may also be used. The temperature in the retorting zone is generally between about 800 F. and about l500 F. depending upon the type of shale employed and the nature of the products desired.

It is to be understood that the crushed shale flows downward through the apparatus of this invention as a compact moving bed and that the unit is so designed that vapor velocities do not reach a Value sufliciently high to cause the descending solidsto boil to any appreciable extent. The use of a gaseous stream of high velocity in only a restricted portion of the equipment, namely, in the gas seal zone, affords Several advantages. Thus, adequate time for combustion and retorting can thereby be provided without making the apparatus unduly large, particularly in height. Moreover, erosion of equipment and shale is minimized by substantial elimination of high vapor velocities other than in the aforementioned gas seal zone.

Collection of the liquid shale oil in a pool inside the retorting vessel is also advantageous in that a high degree of contact between the rising vapors and the liquid oil is achieved, resulting in greater heat recovery and improved adsorption of light hydrocarbons from the retort gas.

While the method and apparatus described herein have been particularly directed to the recovery of shale Oil from oil shale, the present invention may be adapted for the recovery of oils from any solid substance. ingly, it is to be understood that the above description is merely illustrative of preferred embodiments of the invention, of which manyvariations may be made within the scope of the following claims by those skilled in the art without departing from the spirit thereof.

I claim:

1. A process for the recovery of shale oil from oil shale, which comprises feeding crushed raw oil shale to an elongated vertical retort, passing said shale downwardly through said retort while bringing the same to ignition temperature, contacting the resulting hot shale with a stream of oxygen-containing gas to. effect combustion of combustible matter present therein, flowing hot vaporous products emitted from the heated shale upwardly through a zone wherein a gas seal is maintained in the retort by the introduction thereto of a high velocity gas stream, passing said vaporous products upwardly from said zone and immediately condensing a portion thereof to liquid shale oil by contacting with cold, crushed, raw shale feed, maintaining a static pool of the liquid shale oil so obtained, passing said cold, crushed, raw shale, wet with oil, through the aforementioned gas seal zone, the introduction of said gas stream to said zone being suflicient to prevent the downward ow of said pool of liquid shale oil through said zone but insulcient to inhibit the downward passage of crushed oil shale therethrough, removing a stream of non-condensable gases liquid shale oil from the upper portion of said retort and. withdrawing a stream portion of'fsaid-` retort;

2.; kIn a method for producingqshal'e oil"I from voil shale byheating a downwardly moviugrbed of crushed oil shale and flowing the vaporous products so produced upwardly through said downwardlyl moving bed'su'ch that vaporous products rising from a lower retorting zone undergo condensation upon coming into contact with cold, crushed shale in an overlying condensing zone, the improvement which comprises the introduction of a gas stream at a point intermediate said retorting zone and said condensing zone of velocity suiiicient to prevent condensed shale oil from passing into said retorting zone but insullicient to prevent the downward passage of crushed oil shale therethrough.

3. In a method for producing shale oil from oil shale by heating a downwardly moving bed of crushed oil shale and owing the vaporous products so produced upwardly through said downwardly moving bed such that vaporous products rising from a lower retorting zone undergo condensation upon coming into contact with cold, crushed shale in an overlying condensing zone, the improvement which comprises recycling a stream of retort gas to a point intermediate said retorting zone and said condensing zone of velocity suicient to prevent condensed shale oil from passing into said retorting zone but insuicient to prevent the downward passage of crushed shale oil therethrough. n

4. In a method for producing shale oil from oil shale by heating a downwardly moving bed of crushed oil shale and owing the vaporous products so produced upwardly through said downwardly moving bed such that vaporous products rising from a lower retorting zone undergo condensation upon coming into contact with cold, crushed shale in an overlying condensing zone, the improvement which comprises spraying water at a point intermediate said retorting zone and said condensing zone to provide lan amount of steam sucient to prevent condensed shale oil from passing into said retorting zone but insuicient to prevent the downward passage of crushed oil shale therethrough.

5. A process for the recovery of shale oil from oil shale, which comprises feeding crushed, raw oil shale to an elongated vertical retort, passing said shale downwardly through said retort while bringing the same to ignition temperature, contacting the resulting hot shale with a stream of oxygen-containing gas to effect. combustion of combustible matter present therein, flowing hot vaporous products emitted from the heated shale upwardly through a zone wherein a gas seal is maintained in the retort by the introduction thereto of a water spray affording a high velocity stream of steam, passing said vaporous products upwardly from said zone and immediately condensing a portion thereof to liquid shale oil by contacting with cold, crushed, raw shale feed, maintaining a static pool of the liquid shale oil so obtained, passing said cold, crushed, raw shale, wet with oil, through the aforementioned gas seal zone, the introduction of water to said zone being sutlicient to afford an amount of steam adequate to prevent the downward flow of said pool of liquid shale oil through said zone but insufiicient to inhibit the downward passage of crushed oil shale therethrough, removing a stream of non-condensable gases and shale oil from the upper portion of said retort and withdrawing a stream of spent shale from the lower portion of said retort.

6.A process for the recovery of shale oil from oil shale, which comprises co-mingling crushed oil shale with hot ue gas to heat said shale to ignition temperature, contacting the hot shale with a stream of an oxygen-containing gas to etect combustion of combustible matter present in the shale, flowing hot vaporous products rising from the heated shale, together with gases formed during combustion, through a gas seal zone maintained by the introduction thereto of a high velocity stream of gas of'lspent shalefrom the lower produced as hereinafter described, condensing a portion of said vaporous productsv upon emergence from said zoieto-liquid shale-oil bycontactinget'hesame with cold, ci''shed, raw shale, maintaining a p'ooly of liquid. shale oilz 'so obtainedy immediately overlying said gas seal zone, sidf pool being supported bythe high gas velocity Allow through said zone, passing said cold, crushed, raw shale downwardly through said pool and then passing the shale, wet with oil, through said zone countercurrent to the ow of hot vaporous products therethrough, whereby the shale becomes heated during its passage through said zone and the hot counter-flowing vaporous products are cooled by heat exchange, withdrawing a stream of retort gas and recycling the same under pressure to the aforementioned gas seal zone, withdrawing heated shale from said zone, bringing the same into contact with the aforementioned stream of oxygen-containing gas to produce a further quantity of said vaporous products and residual spent shale, removing a stream of shale oil from said pool and withdrawing a stream of said spent shale.

7. In a retorting apparatus for producing shale oil from oil shale, the combination of an elongated vertical retorting vessel having a lower retorting zone and an overlying condensing zone, means for introducing o-il shale into said retorting vessel, means for introducing hot ilue gas into said retorting vessel, means for introducing an oxygen-containing gas into said retorting vessel, means for withdrawing and recycling a stream of retort gas from the upper portion of said vessel to a point intermediate the retorting zone and the condensing zone of said vessel, an outlet pipe for withdrawing a stream of liquid shale oil from said condensing zone, means for cooling shale after combustion thereof, and means for removing cooled spent shale from said retorting vessel.

8. In a retorting apparatus for producing shale oil from oil shale, the combination of a retorting vessel provided with a lower retorting and an overlying condensing zone, a conduit for introducing oil shale into said retorting vessel, an inlet pipe for the introduction of a hot flue gas into said retorting vessel, an inlet pipe for the introduction of oxygen-containing gas into said retorting vessel, means for spraying water into said retorting vessel at a point intermediate said condensing zone and said retorting zone, an outlet pipe for the withdrawal of liquid shale oil from said condensing zone and an outlet conduit for removing spent shale from said retorting vessel.

9. In a retorting apparatus for producing shale oil from oil shale, the combination of a retorting vessel having a lower retorting zone and an upper condensing zone, a conduit for introducing crushed oil shale into said retorting vessel, an inlet pipe for the introduction of hot flue gas into said retorting vessel, an inlet pipe for the introduction of oxygen-containing gas into said retorting vessel, an outlet pipe for withdrawing a stream of retort gas from the upper portion of said retorting vessel, a liquid-gas separator for removing liquid shale oil from said stream, a blower for recycling said stream substantially freed of liquid shale oil to said retorting vessel at a point intermediate the retorting zone and the condensing zone thereof, an outlet pipe for the withdrawal of liquid shale oil from said retorting vessel and an outlet conduit for removing spent shale from said retorting vessel.

References Cited in the tile of this patent UNITED STATES PATENTS 1,130,001 Maclurin Mar. 2, 1915 1,509,667 Catlim Sept. 23, 1924 1,631,637 Loughrey June 7, 1927 (Other references on following page) i UNITED STATES PATENTS Wallace Aug. 16, 1927 Herrick Dec. 29, 1931 Snyder May 17, 1932 Karrick Mar. 14, 1933 5 8 Warner Jan. 7, 1936 Karrick July 4, 1939 Kaufmann June 13, 1944 Barr et a1. Jan. 20, 1953 Kassel May 5, 1953

Claims (1)

1. 2. IN A METHOD FOR PRODUCING SHALE OIL FROM OIL SHALE BY HEATING DOWNWARDLY MOVING BED OF CRUSHED OIL SHALE AND FLOWING THE VAPOROUS PRODUCT SO PRODUCED UPWARDLY THROUGH SAID DOWNWARDLY MOVING BED SUCH THAT VAPOROUS PRODUCTS RISING FROM A LOWER RETORTING ZONE UNDERGO CONDENSATION UPON COMING INTO CONTACT WITH COLD, CRUSHED SHALE IN AN OVERLYING CONDENSING ZONE, THE IM-PROVMENT WHICH COMPRISES THE INTRODUCTION OF A GAS STREAM AT A POINT INTERMEDIATE SAID RETORING ZONE AND SAID CCONDENSING ZONE OF VELOCITY SUFFICIENT TO PREVENT CONDENSED SHALE OIL FROM PASSING INTO SAID RETORTING ZONE BUT INSUFFICIENT TO PREVENT THE DOWNWARD PASSAGE OF CRUSHED OIL SHALE THERETHROUGH.

Images