US2895884A - Shale retorting apparatus and process - Google Patents

Description

July 21, 1959 R. L. swrrzER n SHALE-RETORTING APPARATUS AND PROCESS lFiled Maron 22. 195e' Uited States Patent Oil Company of California, Los Angeles, Calif., a cori porationy of California Application March 22, 1956, Serial No. 573,286

Claims. (Cl. 202--6)V This invention relates to improvements in solids-iiuid contacting and particularly to an improved process and apparatus for the production of hydrocarbon gases and oil's from solids by thermal means. Applicable solids include suchoil-producing and oil-containing materials as oil shale, tar sand, oil saturated diatornte, bituminous and sub-bituminousl coals, and the like. The description will be conducted in terms of the eduction of shale oil and gas from oil shale for the sake of simplicity and with the understanding that the process and apparatus, are applicable in general to other solids from which oils and gases can be produced, and to solids-fluid contacting processes in general.

Some processes for the eduction of shale oils and gases involve the downward passage of shale rock as a moving bed by gravity through a vertical heat treating kiln. During-this passage they are heated to eduction temperatures by direct or indirect means. From a thermal efficiency standpoint the direct heating means is preferred in which a countercurrent contact of hot gases with the shale rock is employed. To avoid the large -fuel consumption otherwise required, most of these processes involve the direct injection of air or other oxygen-containing gas into the bottom of the kiln to burn the carbonaceous residue from the spent shale. This generates hot liue gases needed to heat the rock. However, some diiculties are encountered with the fusion of the spent shale due to this burning and frequently the fused or partially fused rock plugs the air inlet requiring a shutdown. Since all of the hydrocarbon product is removed a't the top of the kiln, it must be removed as a vapor and thus the process requires extensive coolingand condensing facilities.

Other shale eduction processes have successfully avoided the large fuel and condensing water requirement by utilizing an upflow of shale rock and a downow of heating gais. The shale is fed upwardly successively through a perforated product Huid-shale rock disengaging section and a heat treating and kiln section. Air or other oxygen-containing gas enters thetop of the heat treating section, is preheated in cooling the hot shale ash, burns the carbonaceous residue from the spent shale, and the hot flue gases continue downwardly to heat the shale rock to eduction temperatures. The hydrocarbon oils and gases are thus evolved in the eduction zone, pass downwardly with the flue gas in direct contact with the raw shale, and are cooled thereby condensingthe hydrocarbon oil and preheating the raw shale. The liquid and gaseous products are drawn off at the bottom in the disengaging section and are thus separated from the upwardly moving shale rock. A solids feeder passes the' shale rock upwardly throughthe disengaging and heattreating sections and displaces the shale ash out the top of the unit. The processv supplies its own fuel in the form of carbona'ceousspent shale. It cools and partially condenses itsownhproductin preheating the raw shale rock;

principal problem ofthese processes involves the presence ofs'olids n'es in thesolids to be thermally 2,895,884 Patented July 21, 1959 treated and in the present illustration these-fines are exemplified by shale fines in the feed; In the downflow solids processes, al screening step is requiredv t separate from the rock fed to the process the shale'v fines whose average dimensions are less than about 0.25` inch.l In thel upow` shale process, the problem is aggravated when' screw feeders orv non-vertically acting piston feeders andcurved conduits for solids flow are'employed. With such'y solids feeders it has been found that fines are produce'd from as much as percent' of the feed; when such solids feeders are employed'. InV the present invention a vertical reciprocating piston feeder, hereinafter more fully described, is used. This piston feeder successfully passes shale rock upwardly through the appara-tusof this invention Without the formation of substantial quantities of additional fines, The process andapparatus is also capable of a substantially complete retorting of valuable products from those lines which naturally occur inthe unscreened feed and thus accomplishes what all' the pre-V vious retorting processes were incapable of accomplishlng.

The present invention is therefore directed tol an improved upflow shale retorting process as illustrative of those solids heat treating processes in which the solids are passed upwardly countercurrent to a d'ownow of heat treating lluid andy in which process steps and apparatus elements are utilized to avoidthe necessity of solids rines separation from the feed and to obtain a complete andvuniform heat treatment of all solids including the fines.

It isthus a primary object of this invention to provide an improved solids-fluid contacting process.

It is an additional object to provide a particularly im.- proved solids upow and fluid downflow heat treating process especially adapted to the production of hydrocarbon gases and oils from solids.

It is a more specific object of this invention to provide an improved process for the retorting of shale including shale nes to effect a substantially complete recovery of shale oil and gas from the shale rock including the shale fines.

It is also an object of this invention to provide an apparatus adapted to accomplish the aforementioned 0bjects.

Other objects and advantages of this invention will become apparent to those skilled in the art as the de-V scription thereof proceeds.

The present invention will be more readily understood byl reference to the accompanying drawing in which all elevation view in partial cross section of the apparatus of this invention is shown in conjunction with a ow sheet illustrating the process of this invention, The drawing is described by way of a speciiic example of the application of this invention to the heat treatment or ,retorting of oil shale to produce shale oil and gas andit is to be understood that this process is also applicable to other solids to produce hydrocarbon products as well as to other solids-fluid contacting processes` in general.

Referring now to particularly the drawing, the apparatus consists essentially of a lower. feeder case 10, supported approximately at ground level 12, an upwardly ared perforated solids-fluid disengaging section 14 disposed immediately above the feeder case, and a heat treating or kiln section 16` disposed above the disengagingl section. The raw shale is passed upwardly through the disengaging and kiln section by means of a vertical reciprocating piston feeder contained within feeder case feederl piston 24. Shaft 26v connects piston-24with the 3. hydraulic cylinder 2.2. Extending away from the top of feeder cylinder 18 in the directions in which the feeder is oscillated about trunnion 20 are yguards or shoes 28 and 30. These shoes are curved and are sections of a cylinder whose longitudinal axis runs horizontally through trunnion 20. The upper curved surface o f feeder case is also so curved and the two curved sections lit closely together to seal the apparatus against downow of solids as hereinafter indicated. A secondary hydraulic cylinder 32 supported from trunnion 34 is disposed within feeder case 10 and connected by means of shaft 36 and connection 38 to feeder cylinder 18. Extension and retraction of hydraulic cylinder 32 oscillates feeder cylinder 18 in a vertical plane between the retort feeding position shown in the drawing and the feeder cylinder charging position, not shown, but in which cylinder 18 is inclined to the left and aligned withshale inlet hpper 40.

A supply of raw shale is fed to hopper 40.V By means of the hydraulic cylinders 22 and 32 the feeder cylinder 18 is oscillated in a vertical plane and feeder piston 24 is reciprocated within cylinder 18 to receive shale rock from the hopper and inject it upwardly through sections 14 and 16 of the apparatus. Starting from the position shown in the drawing, hydraulic cylinder 32 is retracted moving piston 24 to a point immediately below hopper 40 while shoe 30` prevents downflow of shale from the lower opening of disengaging section 1'4. Hydraulic cylinder 22 is retracted, moving piston 24 downwardly allowing a charge of shale to enter the upper part of cylinder 18. Y Hydraulic cylinder 32 is then extended covering the lower opening of hopper 40 with shoe 28 so that the charge of fresh shale disposed above piston 24 is placed below the ylower opening of disengaging section 14. Then hydraulic cylinder 22 is extended forcing the volume of rock upwardly into disengaging section 14 and displacing the rock already presenty in sections 14 and 16 a corresponding distance upward. Hydraulic cylinder 32 is then retracted to return the feeder cylinder 18 to the charging position below hopper 40 to receive anadditional charge of shale. The vforegoing steps are repeated in succession to maintain the upow of shale. Y

The upper portion of disengaging section 14 is provided around its periphery with a plurality of perforations 42. Preferably these perforations are vertical slots having a width less than about one-half the average dimension of the smallest sized solid particle fed to the unit excluding the tine particles. A minor proportion of the perforations grouped together within between about 1 and about 20 of the perforated periphery of disengaging zone 14 is a plurality of deeper slots 44. The lowest extremity of these slots 44 extend lower than the lower extremities of slots 42. The purpose of this construction is to permit the liquid product produced within the apparatus to assume a highest level within disengaging section 14 at level 46 coinciding with the bottom of deep slots 44 so that all of the product shale oil will discharge only through the deep slots while the gas product will be disengaged more or less uniformly from all the slots. In this way a uniform downflow of 'gas in the apparatus and throughout its cross sectional area is maintained, but a nonuniform and localized overow discharge of liquid is realized only through the lower portion of deep slots 44. The purpose of this structure is immediately apparent from the following discussion.

Disposed coaxially around disengaging section 14 is a jacket 48 providing a shale oil and gas eiuent manifold 50 which communicates'through the shallow and deep slots 42 and 44 with the inside of the apparatus. The bottom or oor of effluent manifold 50 takes the form of a pair of ramps or inclines, each of which follows a path having a uniform absolute slope downwardly and around the opposite sides of the conical disengaging section 14.

Each of these sloping paths thus extend 180 around disengaging zone 414 in opposite directions from a high Y The higher slopes above about 25 are extremely disadvantageous because the height of the apparatus is unduly increased, shale pressures are increased, fines formation in the feeder occurs, and the capacity of the apparatus decreases.

The product liquid standing at level 46 within the disengaging zone flows locally outward through deep slots 44 only at the high point of the run-olf manifold, then splits at high point 52 into two streams of approximately equal volume, and ows downwardly around the inclined paths to low point 54.

The purpose of these flows is to carry hydraulically those solids fines which are not carried upwardly through the apparatus with the upwardly moving solids in the central portions of the upwardly moving bed, but which drop unavoidably through perforations 42 and 44 in the disengaging zone into eluent manifold 50. The fine solids so removed from the apparatus are recycled in a manner hereinafter described and of this amount approximately 95 percent ind their way into the central portion of the moving bed and only approximately 5 percent drop out through the slots and must be recycled.

Product receiver and fines settler 56 is disposed at a low point and immediately adjacent the apparatus de-` scribed before. A liquid rundown line 58 opens from low point 54 of manifold 50 into the product receiver 56 at or above liquid level 57 therein. A gas line 60 opens from the upper portion of manifold 50 into gas blower 62. It also causes liquid level 46 in disengaging zone 1'4 to stand above liquid level 46 vin hopper 40 by an amount equivalent to the pressure drop of Huid flowing through the upwardly moving shale bed. It is this blower which maintains the downward flow of air, the combustion of spent carbonaceous shale, and the removal of gas products through disengaging section 14.

The gas produced is discharged from blower 62 through line 64 into cyclone separator 66 wherein residual droplets or non-agglomerated mists of product liquid are separated from the gas. These are pumped by pump 69 through line 68 back to product receiver 56. The gases may, if desired, be passed through line 70 into separator 72 which may comprise an electrostatic or ultrasonic separator. Any additional liquid material recovered here is returned to rundown line 68 through line 74. The liquid-free gas phase is discharged through line 76 to the atmosphere, or used as fuel, or recycled with oxygen-containing gas through inlet line 78.

Product receiver 56 comprises also a solids lines settler in which the shale lines sluiced from eiuent manifold 50 are separated from the oil product phase and returned to the raw shale inlet. A body of oil 78 is maintained within receiver 56 by means of liquid level controller 80 which detects the position of level 57 and actuates valve 82 in the product draw-off line 84. Pump 86 removes fines-free shale oil from the down-stream side of secondary baflle 108 in receiver 56 through line 88 at a rate of about 33 gallons per minute in the present example. About 7 gallons per minute of this oil is removed, as described, through line 84 as a product of this process. A rst recycle stream is discharged throughV stream supplements the net flow of liquid product down lines from manifold 50; This primary recycle stream is utilizedonly with oil shale producing an. insullicient quantity;` of oil so that the net local product overllow is notenough to remove solids nes. With oil shales producing morey than about 50 gallons per ton, only a very small primary recycle stream is needed, and with richer oil shales it may be eliminated entirely.

A secondary recycle stream of shale oilv product is pumped through line 98 at a rate of about 6 gallons per minute controlled by valve 100.intor feeder case as'.r a purge. yThis secondary stream of oil is removed partly through line 102 at a rate of about one gallon per minute controlled by valve 104; This stream may be introduced to settler 56 for solids separation. This serves to remove settled. lines from inclined trough- Shaped baille 106 located. at .the bottom in feeder case 10.' Theremaining 5 gallons per minute llow upwardly through the clearance between shoes 28 and 30 and the upper cylindrical surface of feeder case 10. This prevents solids fines from settling through this spaceinto the feeder case. This oil goes .upwardly through disengaging section 14 and joins theproduct overflow into ellluent manifold 50 throughy the-lower part of deep slots 44, and may itself with richershales raise the oil overiloW rate sulliciently to eleminate the iirst recycle stream.

In product receiver and lines settler 56, on the upstream side of baille 103, the solids nes settle forming fines accumulation 1li) at the bottom of the vessel. A' primary baille 109 intersecting liquid level 57 prevents liquid short-circuiting across the surface to the oil outlet. An inclined bucket elevator or drag line 112, either continuously or intermittently actuated, extends upwardly from the low point in settler 56 and is provided with an upper discharge at 114 directly into shale hopper 40. The buckets pick up solids fines as they settle saturated with product oil and dump them into hopper 4i) into admixture with the dry raw shale rock. It has been found that the wet mixture of lines adheres quite tenaciously to the raw shale rock even While it passes through the body of liquid oil in hopper 40 below level 46. In this manner the solids lines which fall through the openings of disengaging section 14 and which `are sluiced out of eilluent manifold 50 by means of the product and recycle oil streams are recirculated directly into the feed shale and pass therewith upwardly through the equipment. lt is found that this lines recycle rate is only approximately 5 percent of therate at which lines are introduced into the apparatus andthus 95 percent of the fines so introduced iind their way upwardly through disengaging section 14 without falling through the disengaging section perforations.

The upper portion of the apparatus shown in the drawing consists of heat treating or kiln section 16 provided with a plurality of radial cooling fins 120. Surrounding the outer extremity of these tins is jacket 122 providing a plurality of paths for natural or forced convection cooling air around the outer surface of section 16. Cool atmospheric air enters below jacket 122, passes upwardly between the iins, collects in manifold 124, and is discharged to the atmosphere through stack 126. If desired, aportionl of thiswarm air may be introduced into the top of heat treating section 16 as through line 78.

The shale ash is discharged over the upper rim 126 ofsection life-inside housing 128; If desired, a seriesof mechanicalplows lis usedy to agitate the upwardly moving shale. The ashandV cindersso vdislodged fall by gravity onto the inside or upper inside surface of inclined plane 130 and discharge through chute 132 into ash disposal conveyor 134.

The process and apparatus briefly described above was employed in the retorting of Colorado oil shale at the rate of 350 tons per day. The solids feeder piston diameter was 5.5 feet. The disengaging section was conical having a lower diameter of 5.5 feet and an upper diameter of l5 feet. The disengaging section was" 8 feet high. The kiln or retorting 'section was also kcouical having a height of 12 feet. Its lower' diameter Was 15 feet and its upper diameter was l8'feet. The settling chamber provided a residence time for product oil of 2.5 Ihours during which time solids lines settled Sulliciently to give the product oil an ash analysis of 0.2 percent by weight. The raw shale analyzed by Fischer -assay indicated an oil productivity'of 30 gallons per ton. The product oil rate was 420 gallons per hour and constitutes an eduction efciency of 96.4 percent.

Very little lines were discovered in the effluent from the feeder case due to the existence of the secondary irecycle stream used as a purge therein.

Again it should be emphasized that although the foregoing detailed description has been conducted in terms of the production of shale oil and gas from oil shale, the present process and apparatus is clearly applicable to other solids-fluid contacting processes in which a liquid product is produced during a reaction or contact between moving solids and a fluid and in which solids lines must be thoroughly treated. As stated above, the process is applicable with advantage to the treatment of such solids as oil shale, tar sand, bituminous and subbituminous coals, bitumen-saturated diatomite, or `other solids.

A particular embodiment of the present invention has been hereinabove described in considerable detail by way of illustration. It should be understood that various other modifications and adaptations thereof may be made of those skilled in this particular art without departing from the spirit and scope of this invention as set forth in the appended claims.

I claim:

l. In a method for contacting fluids withfines-containing solids, which comprises passing said solids upwardly successively through a foraminate disengaging Zone and a contacting zone and passing a fluid-comprising a Iliquid and gaseous phase downwardly in countercurrent contact with said solids successively through said contacting zone and said disengaging zone, the improvement which comprises establishing a sloping manifold zone surrounding said disengaging zone `and a settling zone communicating with the lowest point of said manifold zone, and tlowing the liquid phase from said disengaging zone only into the highest point'of said manifold Zone, whereby lines passing from said disengaging zone are hydraulically sluiced from the entire manifoldV zone into said settling zone.

2. A method according to claim l in combination wit-hthe step of recirculating a portion of said clariedliquid,y from said settling Zone to the highest point of rsaid man-.i-

fold zone to supplement liquid overllow to said manifold zone from said disengaging zone. g

3. A method according to claim l in combinationrwith the step of recirculating a portion of said clarified liquid from said settling zone into said feeder zone so as lto flow therefrom upwardly into said disengaging zone, reducing flow of solids lines from said disengaging zone into said feeder Zone, said portion of claried liquid continuing in saiddisengaging zone Vand supplementing the product liquid flowing from said disengaging zone into said manifoldV zone.

4. In a process for producing hydrocarbon gases `and oils from oil shale which comprises passing said. shale downwardly by gravity through .a hopper zone into a feeder zone, passing said shale therefrom vertically `upward successively through a foraminate disengaging zone and a heat treating Zone, burning in a burning zone the carbonaceous residue remaining on said shale after passing upwardly through said heat treating zone, removing shale ash from the top of said burning zone, introducing oxygen-containing gas at the top of said burning zone, passing it downwardly through said successive zones thereby burning carbonaceous residue, and thereby heating and producing hydrocarbon gas and liquid from said shale, the improvement which comprises collecting said gas and liquid in a manifold zone surrounding said disengaging zone, flowing said liquid therefrom into a settling zone, removing settled granular shale fines from said settling zone to the exterior thereof, Aremoving a clarified hydrocarbon product from said settling zone, passing the gas phase from the whole periphery of said disengaging zone into said surrounding manifold zone while owing the liquid phase locally through a minor portion only of said periphery into said manifold zone and then downwardly by gravity along the bottom of said manifold zone into said settling zone at a rate sufcient to maintain said manifold zone substantially free of granular shale fines falling thereinto from said disengaging zone, and maintaining the liquid level in said settling zone below the lowest point in said manifold zone.

5. A process according to claim 4 in combination with the step of passing a first oil recycle stream from said settling zone into said manifold zone to supplement the overow thereinto `from said disengaging zone to remove solids iines.

6. A process according to claim 4 in combination with the step of separating non-agglomerated oil mists from the gas phase, and owing the separated oil into said settling zone.

7. A process -according to claim 4 wherein said minor portion of disengaging zone periphery wherein local overflow of oil occurs is between about 1 and 20 of said periphery.

8. A process according to claim 4 in combination with the step of pumping a recycle stream of clarified oil into said feeder zone and upwardly therefrom into said disengaging zone to prevent fines flow therefrom into said feeder zone and to supplement oil overow therefrom into said manifold zone.

9. In an apparatus for contacting fluids comprising liquids and gases with fines-containing solids which comprises a perforated disengaging section and a communicating contacting section, means for passing said solids upwardly successively therethrough and means for passing said fluids downwardly therethrough in countercurrent Contact with said solids, the improvement which comprises a manifold section surrounding the perforations of said disengaging section, said manifold section having a bottom which slopes continuously from the horizontal, a settling section communicating with the lowest point in said manifold section, and a set of perforations in said disengaging section which are at a lower elevation than any of the other higher perforations therein which are at the highest positions in said manifold section, whereby liquids leaving said disengaging section will pass through said lower perforations and serve to hydraulically sluice solids fines passing through said perforations from the manifold section into the settling section.

10. An apparatus according to claim 9 wherein said bottom of said manifold section has an absolute slope around said disengaging section of between about 5 and about 25 from horizontal.

11. An apparatus according to claim 9 wherein said set of perforations in said disengaging section which are at a lower elevation than any of the other perforations therein are grouped together within an angular section comprising between about 1 and about 20 of the periphery of said disengaging section.

12. In an apparatus as dened in claim 9 wherein said higher perforations within said manifold section are dis'- tributed substantially uniformly around the periphery of said kiln disengaging section, and there is provided a conveyor extending from the bottom of said settling section to the exterior thereof for removing settled solids fines,

13. An apparatus according to claim 12 wherein said sloping bottom has an absolute slope around said disengaging section of between about 5 and about 25 from the horizontal.

14. An apparatus according to claim 12 wherein said sloping bottom extends downwardly from said high point in both directions to said low point located around said disengaging section.

- 15. An apparatus according to claim 12 in combination with pumping means and conduits connecting it from said settling vessel to said manifold at said high point, and a fluid flow control means in said conduit means.

16. In an apparatus for solids-Huid contacting to produce a liquid product which comprises an oscillating reciprocating piston solids feeder, a feeder case surrounding the feeder, a solids inlet hopper opening angularly downward into said feeder, a disengaging section disposed vertically above said feeder in solids-receiving relation thereto and provided with a large plurality of perforations extending around the periphery thereof, a contacting section disposed above said disengaging section and open to gas entry at its top, the improvement which comprises, a jacket surrounding said disengaging section, a settling vessel connected in fluid receiving relation through a rundown to said jacket, and an outlet for clari-v ed liquid opening from said vessel, there being provided a downwardly sloping bottom surface in said jacket extending from a high point downwardly around said disengaging section to a low point, at least one of said perforations extending below the lower ends of the other perforations of said disengaging section at a point irnmediately above the high point of said downwardly sloping bottom surface, said rundown line opening from the low point of said jacket, said settling vessel being disposed at a lower level than said jacket, and means for conveying settled solids from the botom of said vessel to the exterior thereof for -removing settled solids.

17. An apparatus according to claim 16 in combination with pumping means and conduits connecting said means to said settling vessel and to said jacket at said high point for a recycle liquid stream.

18. An apparatus according to claim 16 in combination with pumping means and conduits connecting said means to said settling vessel and to said feeder case for a liquid recycle stream.

19. An apparatus according to claim 18 in combination with a conduit opening from the bottom of said feeder case into said settling vessel.

References Cited in the tile of this patent UNITED STATES PATENTS 2,501,153 Berg Mar. 2l, 1950 2,517,117 Komline Aug. 1, 1950 2,640,014 Berg May 26, 1953 2,640,019 Berg May 26, 1953

Claims (1)

1. IN A METHOD FOR CONTACTING FLUIDS WITH FINES-CONTAINING SOLIDS, WHICH COMPRISES PASSING SAID SOLIDS UPWARDLY SUCCESSIVELY THROUGH A FORAMINATE DISENGAGING ZONE AND A CONTACTING ZONE AND PASSING A FLUID COMPRISING A LIQUID AND GASEOUS PHASE DOWNWARDLY IN COUNTERCURRENT CONTACT WITH SAID SOLIDS SUCCESSIVELY THROUGH SAID CONTACTING ZONE AND SAIDD DISENGAGING ZONE, THE IMPROVEMENT WHICH COMPRISES ESTABLISHING AA SLOPING MANIFOLD

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