US2895885A - Shale retorting apparatus - Google Patents

Description

July 21,y 1959 w. l.. BEWLEY ET AL 2,895,885

sHALE RETORTING APPARATUS Filed March 22, 1956 United States Patent O SHALlE RETORTING APPARATUS William L. Bewley, John L. Hotz, and Robert L. Switzer, Long Beach, Calif., assignors to Union Oil Company of California, Los Angeles, Calif., a corporation of California Application March 22, 1956, Serial No. 573,287

4 Claims. (Cl. 202-91) This invention relates to improvements in solids uid contacting and particularly to an improved process and apparatus for the production of hydrocarbon gases and oils from solids by thermal means. Applicable solids include such oil-producing and oil-containing materials as oil shale, tar sand, oil-saturated diatomite, bituminous and sub-bituminous 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 efciency 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 oxygencontaining gas into the bottom of the kiln to burn the carbonaceous residue from the spent shale. This generates hot flue gases needed to heat the rock. However, some diificulties 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 at the top of the kiln, it must be removed as a vapor and thus the process requires extensive cooling and condensing facilities.

Other shale eduction processes have successfully avoided the large fuel and condensing water requirements by utilizing an upllow of shale rock and a downflow of heating gas. The shale is fed upwardly successively through a perforated product fluid-shale rock disengaging section and a heat treating and kiln section. Air or other oxygen-containing gas enters the top 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. The whole vapor phase passes downwardly in direct contact Iwith the raw shale, and is cooled thereby condensing the hydrocarbon oil and preheating the raw shale. The liquid and gaseous products are `drawn off at the top o f the disengaging section and are thus separated from the upwardly moving shale rock. A solids feeder passes the shale rock upwardly through the disengaging and heat treating sections and displaces the shale ash out the top of the unit. The process supplies its own fuel in the form of carbonaceous spent shale. It cools and partially condenses its own product in preheating the raw shale rock.

One principal problem of these processes involves the presence of solids lines in the solids to be thermally Vice treated and in the present illustration these fines are exemplified by shale nes in the feed. In the downliowy solids processes, a screening step is required to separate from the rock fed to the process the shale fines whose, average dimensions are less than about 0.25 inch. In the upflow shale process, the problem is aggravated with screw feeders, and non-vertically acting piston feeders; are employed. With such solids feeders it has beenl found that the quantity of lines in the feed increases as much as or more when such solids feeders are employed and that up to about 50% of the feed is re duced to fines. In the present invention a vertical reciprocating piston feeder, hereinafter more fully described, is used. This piston feeder successfully passes shale rock upwardly through the apparatus of this invention With-` out the formation of substantial quantities of additional lines, The process and apparatus are also capable of a substantialll complete retorting of valuable products from those lines which naturally occur in the unscreened feed and thus they accomplish what all the previous retorting processes were incapable of accomplishing.

The present invention is therefore directed to an m-` proved upow shale retorting process as illustrative of those solids heat treating processes in which the solids; are passed upwardly countercurrent to a downilow of heat treating fluid and in which process steps and appa-` ratus elements are utilized to avoid the necessity of solidsV fines separation from the feed and to obtain a complete and uniform heat treatment of all solids including the lines.

It is thus a primary object of this invention to provide an improved solids-huid contacting process.

It is an additional object to provide a particularly improved solids upow and fluid downilow heat treating process especially adapted to the production of hydro-Y carbon 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 objects.

Other objects and advantages of this invention become apparent to those skilled in the art as the description thereof proceeds.

The present invention Will be more readily understood by reference to the accompanying drawings in which:

Figure 1 is a side elevation view in partial cross section of the improved apparatus of this invention shown in conjunction with a schematic flow diagram of the process,`

Figure 2 is an end elevation view of the central portion of the apparatus shown in Figure l, and

Figure 3 is a cross section plan view of the intermediate section shown in Figure 2.

Referring now more particularly to Figure l, the proc-l ess of the present invention will be described in terms of a specific example of the present invention as applied to the retorting of oil shale to produce shale oil and shale gas. The apparatus of the present invention consists essentially of three parts; namely an upper heat treating or eduction kiln 10, an intermediate solids-Huid disengaging section 12, and a lower reciprocating piston shale feeder contained within feeder housing 14.

Shale feeder housing 14 contains a vertically reciprocating feeder piston 16 contained within feeder cylinder 18. Cylinder 18 oscillates in a vertical plane about trun nion 20a so that it may be moved between the vertical feeding position shown and an inclined cylinder chargfl ing position not shown but in which the upper outlet opening of cylinder 18 is disposed to the left and imniediately below the lower outlet opening of shale feed hopper 20. A hydraulic actuating cylinder 22 disposed within cylinder 18 reciprocates feeder piston 16 in cylinder 18. A second hydraulic cylinder 24 contained within feeder case 14 oscillates feeder cylinder 18 between the filling and feeding positions. A V-shaped trough 15 runs' along the bottom of the case and has a screw conveyor 17 at its apex to move settled fines toward outlet 19. A stream of oil is introduced into case 14 through line 23 controlled by valve 25 and serves to flush the nes slurry from outlet 19 through line 27. This slurry is returned to hopper 20 by pump 29 and line 31 to recycle fines.

A Raw shale is introduced by any convenient conveyor means not shown in the direction indicated into feed hopper 20. With feeder piston 16 disposed at its upper extremity immediately after its up stroke, cylinder 18 is moved to a point in alignment with feed hopper 20. Cylinder 22 retracts piston 16 drawing a charge of shale rock into the upper part of feeder cylinder 18. Hydraulic cylinder 24 is then extended returning feeder cylinder 18 to the vertical position shown. Then hydraulic cylinder 22 is extended forcing piston 16 upwardly thereby moving the charge of rock into disengaging section 12 and displacing the rock therein and in kiln upwardly. This cycle is repeated thereby continuously feeding fresh shale at the bottom of the structure and displacing cool shale ash from the top.

The shale ash is displaced as described from the top of kiln 10 and inside housing 26. It falls by gravity through the paths indicated as by arrows 28 and 30 downwardly on to the bottom 30 of housing 26 and discharges through outlet 32 into ash disposal conveyor 34.

Kiln 10 is provided with a plurality of radial ns 36 disposed on its outside surface. Jacket 38 surrounds the outer edges of the fins providing a series of adjacent nearvertical paths for cooling air which passes by natural or forced convection upwardly within jacket 38, into manifold 40, and then out through stack 42 to the atmosphere. If desired, this warm air may at least in part be introduced into the top of the kiln through line 44 together with other gases subsequently described.

The raw shale is passed by means described above upwardly through gas and liquid disengaging section 12 in which the cool ue and shale gases and the condensed shale oil are disengaged from the upwardly moving mass of shale. In vkiln 10 the upwardly moving shale passes successively through a fresh shale preheating and product cooling and condensing zone, a shale eduction zone, a spent shale combustion zone, and a shale ash cooling and gas preheating zone. At this point the ashes are expelled as described from the top of kiln 10. In order to support the carbonaceous spent shale combustion, an oxygen-containing gas such as air is introduced through line 44 at a rate controlled by valve 46. With this gas may be mixed steam or water or a portion of the cool mixture of shale and flue gas produced from the product separator 58. This gas passes downwardly through the aforementioned zones in the reverse order. In the uppermost or shale ash cooling zone this gas is preheated by direct contact with the shale ash thereby cooling the ash to approximately atmospheric temperature. The preheated gas then moves downwardly through the spent shale combustion zone in which hot ue gases are generated and the carbonaceous shale is burned forming the shale ash. In the next lower or eduction zone the hot llue gases contact and educt shale oil and gases from preheated fresh shale forming the spent carbonaceous shale and a vapor mixture of shale oil and gas together with the ilue gas. In the next lower zone, the fresh shale is preheated by direct contact with the products of eduction thereby cooling and partially condensing them forming a liquid oil phase and the preheated fresh shale. The now cool gas phase continues downwardly and the liquid product runs downwardly by gravity filling the lower portion of dis'rigagin'g section 12 approximately to level 50 at the lower extremities of slots 52 which extend around the upper periphery of disengaging section 1.2. This liquid product fills feeder case 14 and stands up to level 50 in shale feed hopper 20 sealing it against entry of air. The diterence between these levels 5() and 59 corresponds to the pressure differential existing by virtue of gas flow through the shale rock bed in the apparatus. In other words, the apparatus is operated under a partial vacuum created by exhaust blower 52a.

By means of blower 52a the cool product gases pass from the upwardly moving shale bed through slots 52 into eiluent manifold 54 surrounding the disengaging section and therefrom directly into integrally attached product vapor liquid separator and nes settler 5S. Herein the gases are separated from the condensed oil. The gas phase containing small quantities of separated oil and unagglomerated mists, iows from separator 58 under the influence of blower 52a through line 60 at a rate controlled by valve 64 and differential pressure recorder controller 66 into a centrifugal separator 68. From this separator the agglomerated oil phase is removed through line 70 and combined with the liquid product produced through line 62 or pumped into settler 58. The remaining gas phase flows under the pressure exerted by blower 52a through line 70 into any sort of nal separator 72. This latter separator may comprise an oil wash such as in an absorber, an electrostatic or ultrasonic treatment to clean up any residual dusts and oil mists, or other suitable separators. Oil recovered is removed through line 73. Through line 74 of oil-free gas is discharged to the atmosphere, or recirculated in part to the kiln as previously described.

The oil phase overowing from disengaging section 12 through slots 52 ows through manifold 54 directly into the integrally attached settler 58, and in a serpentine path around bailes 56. The oil temperature is about 120 F. and sucient settling time is provided to permit gravitation of all solids fines larger than microns. These solids are collected in screw conveyors 82, 84, and 86 and are returned in the manner described below to hopper 20. Settler S8 is provided with overflow Weir box 57 and Weir 59 into which the product oil ows. It is pumped therefrom through line 60' by pump 64 at a rate suicient to supply all oil recycle streams through line 65, such as that to feeder case 14, and produce a net oil product through line 62 at a rate controlled by valve 66 and liquid level controller 68.

A small quantity of shale fines is invariably present in the unscreened raw shale fed to the unit. Further, a small quantity of additional nes is unavoidably formed during the feeding of shale upwardly to the apparatus. For the most part these fines in the present apparatus pass upwardly together with the oil-wet shale rock successively through disengaging zone 12 into retort 10 wherein the vshale fines are retorted along with the larger shale particles. However a minor portion of the fines associated with the upwardly moving bed of rock nearest the periphery of the bed discharge at least in part with the oil and gas through slots 52 into eiiluent manifold 54. This quantity of fines so entering manifold 54 is only about 5% of the fines introduced upwardly from feeder case 14 with the upwardly moving mass of rock.

In the present apparatus the shape of manifold 54 and the separator-settler vessel S8 surrounding the perforated disengaging section 12 is especially designed to provide for the natural gravity settling of these fines downwardly through the body of oil contained therein so as to accumulate in a pair of horizontal parallel primary feeder screws 82 and 84 and a secondary screw 86. The feeder screw case 84 is apparent in Figure l, and all three are readily apparent in Figures 2 and 3 to which reference will subsequently be made. The separator-settler vessel bottom is W-shaped and consists of a pair of adjacent V-shaped troughs with the primary feeder screws 82 and 84 disposed horizontally along the bottom or apex of each trough. These troughs are closed at each end and the disengaging section 12 which is conical in fonm passes upwardly through the adjacent connecting sides of these troughs in the manner shown in the drawings. Thus the ines which fall through the slots in one side of disengaging section 12 settle in one trough and the nes falling from the other side settle in the other trough. By gravity they progress toward the primary screws 82 and 84 and are moved thereby in the same direction to a collection or secondary screw 86 disposed at right angles to the primary troughs at a point adjacent and above feed hopper 20. Fines falling through slots 52 above the hopper fall directly into the secondary screw conveyor 86.

The slurry of shale iines discharges from the end of each primary feeder screw 82 and 84 into the outside ends of the collection screw 86. The collection screw 86 consists of approximately equal lengths of right-hand and left-hand screws disposed on a common shaft so that rotation of the shaft in the proper direction brings each of these slurries discharged from the primary screw feeders toward a central point along the length of the collection screw. This slurry at this point drops by gravity through dip leg S8 directly into the feeder trough 20. Dip leg 88 is sealed against inliow of air by means of liquid level S0. The raw shale moves into hopper 20 around dip leg 88 and is fed as previously described upwardly with the recirculated ines through the apparatus by means of the oscillating reciprocating piston feeder.

Referring now more particularly to Figure 2, a view taken toward hopper 20 in Figure l is shown, showing the upper portion of feeder case 14, the whole vertical extent of disengaging section 12, and the lower portion of kiln including jacket 38 and fins 36. The slots 52 of disengaging section 12 is indicated in broken lines. Weir box 57 shown in Figure l is also indicated with outlet line 60. The double V-shaped trough structure of settler 58 communicating with the eluent manifold 54 of Figure 1 is clearly shown in this figure. Primary screw feeders 82 and 84 run lengthwise along the lower edges of these two troughs as indicated and discharge the slurry of fines through connections 92 and 94 into each extreme end of of collection screw 86. Depending from a central point along the length of collection screw feeder 86 is dip leg 88 which is sealed at its lower end in liquid product oil in shale hopper 20. The nes slurry is thus returned for re-introduction into the apparatus.

Referring finally to Figure 3, a plan view of the apparatus of Figure 2 is shown looking downwardly from a level just below the perforations 52. In this ligure feeder case 14, the piston 16, lower part of disengaging section 12, and shale hopper are apparent at the bottom of the apparatus. Primary screw feeders 82 and 84 are shown running parallel along the lower apex of each of the V-shaped troughs. The end closures 96, 98, and 100 of separator-settler 58 are shown. To facilitate illustration small arrows indicate in Figure 3 the ow direction of iines settling on the inner surfaces 104, 106, 108, and 110 and the ends of the two V-shaped troughs. The central curve 112 is the line of intersection of conical disengaging section 12 with the two adjoining surfaces 106 and 108 of the V-shaped troughs.

'I'he discharge ends 114 and 116 of primary feeder screws 82 and 84 are shown disposed above the extreme ends of collection feeder screw 86. The long arrows 118 and 120 indicate the direction of fines slurry movement in the primary feeder screws and long arrows 122 and 124 indicate the direction of slurry movement toward a central point in collection screw feeder 86. The upper inlet opening of dip leg 88 is indicated at 126.

The apparatus of the present invention employed a feeder piston 5.5 feet in diameter and the rated shale capacity was 350 tons per day. The disengaging section and an upper diameter of .15 feet. The kiln section 10` was 12 feet high, with diameters of l5 feet at the bottom and 18 feet at the top. The efhuent manifold 54 and separator-settler 58 vessel according to this invention in this installation was constructed substantially as shown in Figure 2 and Was provided with two V-shaped troughs coinciding at their nearest edges and closed at their extreme ends. An area of 70 square feet for fines settling was provided and no fines larger than 120 microns appeared in the oil product. The settler was provided along the lower apex axes with two primary screws which were l0 inchesl in diameter and 20 feet long. These screws turned at approximately 5 r.p.m. discharging shale fines slurry into a collection screw feeder of the same diameter and 10 feet long turning at 5 r.p.m. The screw conveyor in feeder case 14 was 6 inches in diameter and l5 feet long and turned at 5 r.p.m. The fines slurry was successfully returned at a rate corresponding to about 5 percent of the rate at which the apparatus processed shale fines. The operation was completely successful and no accumulation of shale fines in the apparatus was noted.

It is important in the construction of this apparatus to maintain the downward slope of the sides and of the end closures of the W-shaped and V-shaped troughs in the separator-settler and feeder case suiciently high so as to eliminate completely the possibility of nes settling and hanging up on these surfaces. To insure that the nes so contacting these surfaces will slide downwardly toward the primary screws, these surfaces should describe an angle with respect to a horizontal plane of at least 45 degrees and preferably above about 55 degrees. Angles greater than about degrees however are unnecessary and will only unduly increase the height of the apparatus.

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 Huid and in which solids fines rnust 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 sub-bituminous 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 by those skilled in this particular art without departing from the spirit and scope of this invention as set forth in the appended claims.

We claim:

1. In an apparatus wherein fines-containing solids are passed downwardly through a hopper and upwardly successively through a feeder, a perforated disengaging section and a contacting section; and fluids comprising liquids and gases are passed downwardly in countercurrent contact with said solids through said contacting section and said disengaging section, the improvement which comprises a manifold-settling section surrounding the perforations in said disengaging section and extending laterally in a direction away from said hopper, said manifold-settling section having a substantially horizontal W- shaped bottom consisting of a pair of adjacent V-shaped troughs extending along substantially the entire length of said manifold-settling section from the lateral extension thereof to the end adjacent said hopper, the troughs having sides describing an angle of at least 45 with the horizontal so as to permit nes escaping from said perforations to settle directly to the bottom of said troughs, fines conveyor means at the bottom of each trough for transferring settled lines to a yines outlet, and a plurality of vertical baifles in the lateral extension of said mani- 12 was 8 feet high having a lower diameter of 5.5 feet 75 fold-settling section, said baffles being displaced with respect to each other so as to form a serpentine path for liquid flow from the disengagng section toward a liquid outlet near the extended end of said manifold-settling section.

2. An apparatus according to claim 1 in combination with means for separating said liquids from said gases in said manifold settling section.

3. An apparatus according to claim 1 in combination a feeder enclosure case provided with a V-shaped trough extending along the bottom of said feeder case toward an outlet therefrom, a screw conveyor disposed along the bottom of said trough, and means for pumping a slurry of lines from the end of said trough to said hopper.

4. An apparatus according to claim 1 wherein the means for transferring nes to said outlet for recycle to 15 2,640,019

8 said hopper comprises a collection conveyor provided with a left-hand screw through one half of its length and a right-hand screw through the remaining length, and an outlet line from said collection screw opening from adjacent the point at which said left-hand and right-hand screws meet and discharge directly to said hopper.

References Cited in the tile of this patent UNITED STATES PATENTS 1,404,873 McGee Jau. 31, 1922 2,210,362 Devenish Aug. 6, 1940 2,501,153 Berg Mar. 21, 1950 2,640,014 Berg u May 26, 1953 Berg May 26, 1953

Claims (1)

1. IN AN APPARTUS WHEREIN FINES-CONTAINING SOLIDS ARE PASSED DOWNWARDLY THROUGH A HOPPER AND UPWARDLY SUCCESSSIVELY THROUGH A FEEDER, A PERFORATED DISENGAGING SECTION AND A CONTACTING SECTION; AND FLUIDS COMPRISING LIQUIDS AND GASES ARE PASSED DOWNWARDLY IN COUNTERCURRENT CONTACT WITH SAID SOLIDS THROUGH SAID CONTACTING SECTION AND SAID DISENGAGING SECTION, THE IMPROVEMENT WHICH COMPRISES A MANIFOLD-SETTLING SECTION SURROUNDING THE PERFORATION IN SAID DISENGAGING SECTION AND EXTENDING LATERALLY IN A DIRECTION AWAY FROM SAID HOPPER, SAID MANIFOLD-SETTLING SECTION HAVING A SUBSTANTIALLY HORIZONTAL WSHAPED BOTTOM CONSISTING OF A PAIR OF ADJACENT V-SHAPED TROUGHS EXTENDING ALONG SUBSTANTIALLY THE ENTIRE LENGTH OF SAIDD MANIFOLD-SETTLING SECTION FROM THE LATERAL EXTENSION THEREOF TO THE END ADJACENT SAID HOPPER, THE TROUGHS HAVING SIDES DESCRIBING AN ANGLE OF AT LEAST 45* WITH THE HORIZONTAL SO AS TO PERMIT FINES ESCAPING FROM SAID PERFORATIONS TO SETTLE DIRECTLY TO THE BOTTOM OF SAID TROUGHS, FINES CONVEYOR MEANS AT THE BOTTOM OF EACH TROUGH FOR TRANSFERRING SETTLED FINES TO A FINES OUTLET, AND A PLURALITY OF VERTICAL BAFFLES IN THE LATERAL EXTENSION OF SAID MANIFOLD-SETTLING SECTION,SAID BAFFLES BEING DISPLACED WITH RESPECT TO EACH OTHER SO AS TO FORM A SERPENTINE PATH TOR LIQUID FLOW FROM THE DSIENGAGING SECTION TOWARD A LIQUID OUTLET NEAR THE EXTENDED END OF SAID MANIFOLD-SETTLING SECTION.

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