US2992975A - Carbonization of old shale in a compact moving solids bed - Google Patents

Description

July 18, 1961 E. v. MURPHREE CARBONIZATION OF OLD SHALE IN A COMPACT MOVING SOLIDS BED Filed March 20, 1958 3 Sheets-Sheet 1 TO PRODUCT 24 RECOVERY RAW SHALE SEPARATOR GAS SEPARATO FIGURE I Eger V. Mdrphree Inventor By M? Attorney July 18, 1961 E. v. MURPHREE CARBONIZATION OF OLD SHALE IN A COMPACT MOVING SOLIDS BED FiledMarch 20, 1958 3 Sheets-Sheet. 3

RAW SHALE Y m m M R T G ow a M a m E 7.. m n m n w 4. s w H 78 6S F m E E N 0 m N 0 Z N 0 MN MW 3 K m SGT WE S 6 m A WDM H 0 M M U o m w P R k w c P m w B tw w 0 n O 2 8 W fi 9 5 SEPARATOR Inventor t Eger V. Murphree FIGURE 11 M27? Attorney United States Patent i 2,992,975 CARBONIZATION OF OLD SHALE IN A COMPACT MOVING SQLIDS BED Eger V. Murphree, Summit, N.J., assign'or to Esso Research and Engineering Company, a corporation of Delaware Filed Mar. 20, 1958, Ser. No. 722,744 '17 Claims. (Cl. 202-6) The present invention is concerned with the treatment of oil-bearing solids, such as shale and other oil-bearing sands and/or minerals. More particularly, it deals with supplying heat to a retorting system by the application of entrainable hot, fine particles propelled as a gaseous suspension passing through a column of relatively coarse shale particles.

The present invention is a continuationdn-part of System for Recovering Oil from Solid Oil-Bearing Materials, S.N. 564,938, and now US. Patent No. 2,908,617, by the present inventor, filed February 13, 1956.

As is well known in the art, the recovery of oil from shale and similar oil-bearing materials requires pyrolitically treating the solids to break down their oil-forming matter, kerogens and the like. Hydrocarbons of suitable molecular weight and structure to find application as raw petroleum fractions are thus released. Generally, temperatures in the range of 7001800 F. or higher, preferably between 800-1200 F., have been found suitable for effecting this result. The released hydrocarbons are withdrawn either as vaporous material or as condensed liquid products.

Numerous modes of operation have been advanced for retorting oil shale. For example, it has previously been suggested to burn the carbonaceous residue on the spent shale solids, and thereafter introduce the hot flue gases formed into the retorting zone. Further, previous processes such as Peck, US. Patent 2,480,670, have employed shale as a heat transfer agent. Additionally, the use of large sized solid heat-carrying medium, i.e., shot, is known in the art.

However, the prior art systems have suffered from several fairly important disadvantages. In several previous proposals employing relatively fixed, non-turbulent shale solids flow, good heat transfer has been dificult to obtain. It has been felt that to have truly effective thermal conduction and highly turbulent mixing, fluid bed operations might be required. But proper fluidization of a solids mass so as to give the pseudo-liquid phase characteristic of a true fluid bed operation requires that the solids be of rather fine size, e.g. preferably below 1000 microns. Since oil-bearing solids such as shale, when withdrawn from natural deposits, are of the order of 0.25 to several inches in diameter, an expensive and cumbersome comminution operation may be necessitated. As is well appreciated by those skilled in the art, an appreciable size reduction step applied to thousands of tons of solids is an exceedingly costly operation. Moreover, since a fluid bed is essentially a single stage heat transfer zone, operating at substantially a single temperature, the beneficial aspects of counter-current heat exchange may not be realized.

The present invention sets forth a system whereby relatively coarse shale solids may be efiiciently subjected to preheating, retorting and combustion.

More particularly, the oil-shale is rctorted by flowing the shale solids as a relatively compact, moving solids column, e.g. void space of about 50%, counter-current to a gaseous suspension of hot entrainable solids. Both the advantages of truly counter-current flow heat treatment and fluidized solids operation are simultaneously obtained. Each of the hot, entrainable solid particles effectively sees a given horizontal section of the shale column only once as it passes through the interstices of the coarse shale Z,lid2,975 Patented July 18, 1961 bed. Nevertheless, there is intimate contact between the fine and coarse solids, thus insuring good solid-solid heat transfer. The actual velocity of propellant gas will, of course, depend upon the particle size and density of the fine solids utilized. Further, since the suspension-propellant gas utilized for conveying the fine solid particles will normally be at an elevated temperature, approximately equal to that of the solids, additional gas-solids heat exchange is realized.

It should be noted that the fine solids pass through and out of the shale column as a relatively dilute, rapidly flowing suspension. The relatively high interstitial velocity of the suspension, preferably ranging between 4 to 10 ft./sec. or greater, insures that no fines will be lost at the lower end of the treating zone along with downwardly moving coarse shale. The actual gas velocity employed is dependent upon the particle size and density of the fine solids used as the heat carrier media. Since large quantities of shale must be treated per unit of oil recovered, even a small percentage of fines carried along with the shale would result in excessive fine particle losses. Moreover, the rapidly flowing gases serve to sweep liberated oil from the surface of the shale solids, thereby serving to promote the thermal treatment of the kerogen constituents.

The use of a fairly rapidly moving solids-gas suspension to heat a shale column may be utilized for accomplishing any, or all, of the basic heat treatment steps in the retorting system. It may advantageously be used for the heat treatment operations of preheating the raw shale feed, retorting, transferring sensible heat from a combustion zone to other processing regions, recovering heat from spent shale, etc. While counter-current flow of fine and coarse solids is preferred, the use of transverse, or even co-current flow, should be construed as falling within the scope of the present invention.

With regards to fine solids suitable as heat transfer media, generally any relatively fine particle entrainable in a gas stream is suitable. Particles of less than about 1000 microns in diameter, preferably below 500 microns, are preferred. Among solids suitable are sand, ceramic materials, glass beads, spent shale fines, carbonaceous solids, metallic particles, etc. If desired, solid particles having catalytic properties may be utilized.

The various aspects of the present invention will become more clearly apparent by referring to the following description, examples, and accompanying drawings.

FIGURE I illustrates a system wherein a single vessel unit is employed for effecting retorting, fine solids being passed into the retorting zone along with the combustion gases.

FIGURE II depicts a particularly advantageous procedure wherein product oil contamination may be kept at a minimum.

FIGURE III shows an alternative mode of operation employing a separate, fine solids heating vessel.

Turning to FIGURE I, there is shown unitary reaction vessel 10. Within vessel 10, there is successively maintained preheating zone 11, retorting zone 12, combustion zone 13, and generally spent shale cooling zone 14. While the following description of this embodiment of the present invention is directed to a single vessel shell, multiple vessels, as in FIGURE III, may be adapted for this type of operation.

As indicated, relatively coarse, raw shale enters the upper portion 16 of vessel Ill by means of funnel-shaped member 15 or other suitable introduction means. The shale, generally at ambient temperature, will normally range in size from about 0.25 to 5 or more inches in diameter, and is introduced in amounts sufficient to form a relatively compact, freely moving coarse shale column progressively passing through the heat treating zones.

Oxygen-containing gas such as air is introduced into the lowermost section of combustion zone 13 and/or the upper portion of shale cooling zone 14 by distributor 34. Entrainable fine solids, preferably suspended in a propellant gas introduced through line 33, are injected into the air-preheating or shale cooling zone by conduit 19, the fine solids having previously been separated from overhead gases as will be later made more apparent.

In addition to air, other gases such as light hydrocarbons, make-gas from the retorting system, flue gas, inerts, or the like, may be injected into the lower section of vessel 10, thereby serving as a carrier gas and a means of independently controlling the oxygen supply and heat capacity of the gases introduced into the system. If desired, a substantial amount of combustible gas may be added to the combustion zone or below. It has been found that greater heat efficiency may be realized by injecting the air some distance above the point of introduction of the fines and carrier gases to the shale cooling zone. By thus limiting rapid ignition of recycle gases, increased heat recovery is realized in the shale cooling zone. However, if desired, the air may be introduced into a lower portion of the vessel, as for example, into cooling zone 14.

Generally, a major portion of the non-oxygen gases are introduced into shale discharge conduit 17 by line 37, thus upwardly removing fine solids from the descending shale lumps. By blowing fines from the spent shale, the fine solids inventory is kept relatively constant.

Various means can be used to introduce gases and fine solids, and to remove shale from the bottom of the column. One method, which is shown in the drawings, involves the use of a conical grid 20 operating in conjunction with shaker bars 35. The fine solids suspension is thus evenly distributed upwardly through the descending, moving bed of larger particles while permitting continuous withdrawal of the spent shale through outlet conduit 17. The downward movement of the shale is controlled by shaker bars 35 or other similar devices, and by means of valve 18 located in the solids discharge line. Of course, other methods well known to those skilled in the art of solids handling, for transferring solids out of the vessel may be alternatively employed.

The gases and fine solid particles are introduced at proper ratios so as to form an upwardly moving solidsgas suspension having a loading density, for example, in the range of 0.1 to 3.0 lbs/cu. ft., and traveling at an interstitial velocity in excess of 6 ft./sec. The spent shale is thus cooled to a temperature of the order of below 300 F.

The preheated suspension then passes into combustion zone 13 wherein carbonaceous material on the spent shale leaving the retorting zone is oxidized, substantially consuming all the oxygen. Generally, the solids suspension is thereby heated to temperatures greater than 1000 F. The entire hot, upflowing mass of fine solids, combustion flue gas, propellant gas, etc. then enters retorting zone 12 wherein it serves to supply the requisite thermal energy for the retorting step itself. The heavy oil-containing kerogen material is thu pyrolized and lighter oil fractions liberated. A retorting temperature in the neighborhood of 1000 F. is normally preferred.

In order to avoid condensation of desired oil products on the coarse shale descending from the preheating zone, the upflowing eflluent of the retorting Zone is removed from vessel 10. The drawing indicates a horizontal series of funnel-like entrances 21 leading into withdrawal conduit 22 for passage to separator 23. Of course, numerous other devices such as a partition element may be used to effect withdrawal of upflowing gas-solids stream.

Separator '23 removes the fine solids from the mixture of product oil and flue gas. The gases are then passed by line 24 to suitable recovery means, such as a fractionator or the like, wherein desired oil products are sep arated from the flue gases. Fine solids are recirculated 4 through standpipe 25, line 28, and injection means 29 for additional heat exchange in shale preheating zone 11. After recovery of the oil product, the flue gas drawn off the top of the retorting zone is returned to the vessel 10 by line 36. The flue gas also preferably serves as an aeration gas for conveying fine solids, by being introduced through lines 26 and 27. The re-IniXing of fine particles and flue gas may be readily performed before, or after, the flue gas is introduced into the reaction vessel 10.

The gas-solids suspension then continues up into the preheating zone 11, therein giving up its heat to shale passing downwardly. Raw shale may thus be preheated to temperatures in excess of 550 F.

The suspension is thereafter withdrawn from vessel 10 through outlet 30, and passed to separator 31, which may be one or more cyclones or other conventional units. Separated, relatively cool flue gas may be then discharged to the atmosphere through line 32, or preferably at least a portion thereof recycled to the retort. Additionally, it could be used as a fuel gas since this stream will contain some light ends from the retorting operation. Alternatively the light ends might be recovered as such. Normally, it is desirable to recirculate at least the major portion of fine solids to the lower sect-ion of the reaction Vessel 10 by means of line 19. Of course, a fine solids purge or fresh solids introduction line may be installed wherever desired in the fine particle cycle.

Broadly, FIGURE I is illustrative of a system employing the concept of the present invention wherein both fine entrainable solids and combustion flue gas are passed through the retorting zone. While numerous modifications of this system may be made, for example, as regards to the specific structure of vessel 10, precise point of solids and gas introduction and withdrawal, etc, they are to be construed as falling within the present teachings.

Referring to FIGURE ii, there is shown another mode of operation in accordance with the present invention. FIGURE II differs from FIGURE I in that at least a portion of the flue gas emanating from the combustion zone is withdrawn from the system so as not to be passed into the retorting section. Since more air is required to furnish heat than is necessary for the formation of an upflowing fine solids-gas suspension, there would otherwise be excessive product contaminating gases as compared to that required for propelling the hot, fine solids through the retorting zone. Thus, by withdrawing flue gases, the amount of gases in the higher section of the retort is decreased, and hence the amount of vapors that have to be cooled down and separated from desired oil products is reduced.

Basically, the system consists of a preheating zone 51, retorting zone 52 and a combustion and gas preheating zone 53. Separate vessels may be used to form one or more of these zones, although a single shell system 50, as illustrated, is normally preferred. Deflector 84 is pro vided to distribute the raw shale across the preheating zone. Similar devices may be used at the entranceway to the other treating sections. As shown, each zone terminates in a funnel-shaped member, eg 72, 70, leading into the zone below. As previously described, raw shale is introduced into the upper portion of the system and flows downwardly as a moving solids column. Other means of substantially horizontal, or even upward, movement of the shale column may be utilized.

The shale holdup is controlled by valve 57 and the rate of initial shale solids introduction. If desired, bafiles and the like may be inserted in the central portion of the various treating sections as a means of increasing solids holdup time.

Fine, en-trainable particles, either as recovered from the effluent of the preheating zone or from an external source, are introduced into zone 53 by line 53. Propellant gas such as inerts, hydrocarbons, recovered flue gas,

make gas from product recovery, etc. injected by line 59 serves as a conveying medium. As in FIGURE I, a substantial portion of the carrier gases is introduced into shale withdrawal conduit 56 by line 85 as a means of stripping fines from the spent shale column. Oxygencontaining gas such as air is introduced into the lower portion of the combustion zone and/or the upper section of the gas preheat section by inlet 60. As shown, the inlets terminate in gas dispersion means 61 which may take the form of nozzles, grids, etc. Of course, added diluent gas may be utilized. The coarse shale column flows downwardly through exit 56 whencefrom it may be totally discarded, stored, or burned as fuel material.

The heat of the spent shale serves to preheat the fine solids suspension to combustion temperatures, the oxidation of carbonaceous spent shale residue and combustible injected gases providing the basic thermal energy for the retorting step. Thereafter, the mixture of hot flue gas and fine solids is Withdrawn overhead by line 63 and passed to separator 64. Baflie elements 62 and 71 are advantageously provided in the upper portion of the treating zone so as to guide fine solids flow, reduce dead gas spaces, and limit erosion of structural walls. After separation and removal of flue gases by line 65, entrainable fines are then circulated through line 66 into the retorting zone. Conveying gas, introduced by lines 68, and 67, serves 'as a transporting medium and as a means of forming the requisite hot, fine particle suspension.

The drawing illustrates at least a portion of the flue gas being injected into the retorting zone by one or more lines 67 and 69, thus taking advantage of its sensible heat. However, it may be desired to avoid any recirculation of flue gas to the retorting section, so as to miniimize problems in recovering released oil products.

The suspension of hot, fine solids passes upwardly through the retorting section between the interstices of the downwardly moving coarse shale column, and is withdrawn overhead through exit passageway 73 together with liberated shale oil fractions. Hot fine solids are re covered and recirculated to preheating zone 51 by line 76 along with propellant gases introduced through taps 77, 78 and line 79. It may be desirable to use additional hot flue gas for this purpose, although other gaseous materials may be readily applied. Additionally, only the hot flue gas (no hot fines) may be used for the preheating step. Separated oil constituents are withdrawn from separator 74 by line 75 and passed to product recovery steps as is well known in the art.

In the preheating zone, additional counter-current heat exchange is efiected. Raw shale passes down entranceway 55 into zone 51, wherein it is contacted with the hot, solids suspension, thereafter flowing into the retorting zone 52.

The cooled suspension is then withdrawn through outlet 80 and passed to separator 81 wherein fine solids are recovered, the gas stream being normally vented to the atmosphere. Fine particles are returned through dipleg 83 and line 58 into zone 53, as previously described.

'I hus, oil shale may be effectively heated with a minimum of product oil contamination.

With reference to FIGURE III, illustrated is a system differing from that previously described in that the fine, entrainable solids to be used as heat-carrying medium are heated in an external heater vessel 103, and are never subjected to the combustion reaction of the spent shale in burner vessel 102.

As shown, the system consists primarily of preheater 100, retort 101, burner 102, and solids heater 103. Coarse shale is passed, preferably by means of gravity flow, successively through preheating, retorting and oxidation steps in the form of a moving packed bed. It should, however, be understood that all the procedures heretofore described could be operated in somewhat different manners while still employing the basic inventive concept of the present invention. For instance, a moving belt or chain grate might be utilized for aiding shale flow. Alternatively, the reaction vessel might take the form of a rotating chamber.

In the specific embodiment illustrated, raw oil shale is introduced into preheater vessel through entranceway 105, and flows continuously downward through columns 107 and 109 into the several treating zones. The treating vessels preferably contain shaker bars or distributing structures 106, 108 and 110 for insuring uniform continuous solids flow. Valve 111 provides a means of controlling shale solids buildup. While the shale treating vessels are shown as individual units, a common circumsciibing shell structure may unite the preheating, retorting and combustion vessels into a single unit.

Counter-current to the spent shale moving through burner 102, air or other oxygen-containing gas is introduced between the combustion and shale cooling zones by means of inlet 116. It may be desirable to recirculate a portion of the off-gases from preheater 100 or other gasesous media injected by line 115, through conduit 114 as a means of independently varying oxygen and overall gas rates. Conduit 114 is advantageously branched so as to ensure suflicient aeration of the discharging shale column, and stripping of fines therefrom.

The injected gases are preheated to combustion temperatures by contact with spent shale, and thereafter serve to oxidize the carbonaceous shale residue fractions. Hot flue gas is circulated through conduit 112 to solid heater 103 wherein there is maintained a mass of fine solid particles, e.g. sand. Heater 103 preferably has a distribution grid 113 or the like for uniformly contacting the flue gas and time solids. The heater may be operated as a fluid bed, transfer line, staged bed, raining solids zone, etc., in order to promote eflicient heat transfer. Suflicient heat is conveyed to normally raise the temperature of the entrainables to above 1000 F.

While not illustrated, requisite heat for the overall system may be supplied in whole or in part by combustion of a gaseous fuel such as the make-gas from the retorting operation, or extraneous hydrocarbons. For example, the combustion of shale residue may be entirely eliminated, and an auxiliary gas burner, supplied with fuel and oxygen, used in its place. The hot flue gases from the gas burner may be passed into and. through the solids heater 103 in much the same flow pattern as described in reference to the flue gas of vessel 102. Alternatively, solids heater 103 may itself operate as a combustion zone, combustible gases and air being supplied thereto in amounts to heat the fine solids to sufficiently high temperatures so as to enable them to supply the required thermal energy for the retorting process. Both the systems of FIGURE I and FIGURE II may be similarly adapted so that the combustion of fuel gases, e.g. recycle make-gas, rather than the spent shale provides the heat for the overall process. By burning fuels other than oil-shale, the shale is never exposed to high combustion temperatures, and thus heat consuming carbonate decomposition may be kept at a minimum consistent with good oil recovery. Additionally, non-combusted shale is of greater strength, and has less of a tendency to decrepitate than does shale from Which carbon has been removed. This means that high fines-suspension velocities can be used in the retorting zone since there is a decreased tendency for shale decrepitation into fines particles which might be entrained in the heat-carrying fine solids stream.

Returning to FIGURE III, the partially cooled flue gas, after having entrained solids removed in separator 117, is then passed through line 118 into preheater '100 wherein it additionally serves to preheat the raw shale. Multiple injection distributor 119 extending over the major portion of the cross section of vessel 100, is employed to insure good gas-solids contact across the full volume of the unit. The distributor may take the form of a group of pipes disposed in parallel fashion, the pipes having gas ejection holes at their lower surfaces. Other devices for uniform contacting of gases with solids, such as a grid arrangement, bubblecap type distributor, etc., could alternatively be employed. The cooled flue gas is then withdrawn overhead through exit passageway 120. It may be thereafter immediately discharged from the system by line 132. Normally, after purging or removing part of the flue gas from line 122 by means of line 123, the rest of the gas is recirculated through lines 124- and 114 back to the burner vessel 102. The drawing illustrates the use of a separator 121 in the path of the flue gas flow. Such a modification may be desirable when fine shale particles are suitable for serving as the heat transferring entrainable solids, the fines being formed in the preheater by the abrasion and decrepitation of the coarse shale solids. Separated fines may be then passed into the solids heater 103 by conduit 125. Additionally, it should be understood that fine solids may be directly employed as a means of preheating the coarse shale.

Turning to the operation of the retorting vessel 101, preheated coarse shale entering the unit by passageway 107 flows downwardly in the form of a moving solids column. A portion of the hot, fine heat-carrying particles is circulated to the retort by line 126, propellant gas being introduced by line 127 in sufiicient amounts to form a gas-solids suspension of relatively high, e.g. about 10 ft./sec., interstitial velocity. Additional propellant gas may be injected by line 128. The fine solids thus pass upwardly through the downwardly moving course shale bed, supplying sufi'lcient heat thereto to liberate contained oil constituents. The fines and oil products are moved overhead by exit 129 and circulated to separator 130. De-entrained solids are returned to the heater 103, separated hydrocarbons being sent by line 131 to additional product recovery steps, not shown.

The use of an external heater for the fine solids is advantageous in that the solids are not subjected to the high temperature combustion zone, wherein decrepitation and occlusion of waste materials tends to occur. Further, there is no problem of distributing solids through the combustion zone, and generally, the use of a closed solids circuit will bring fine solids losses to a minimum.

Table I below presents a compilation of pertinent data applicable to the present invention.

Table I Broad Preferred Example Range Range Temperature Conditions:

Raw Shale Inlet Temp., F. -500 50-100 70 Preheated Shale Temp, F. 300-800 550-750 650 Retort Temp, F 700-2, 500 800-1, 200 1,000 Combustion Temp, F 1, 000-2, 500 1, 200-1, 600 1,300 Fine Solids Temp. Upon Entering Retorting Zone, F 1 000-2, 500 1, 000-1, 300 l, 150 Solids Characteristics:

Average Diameter of Raw Shale, Inches. 0. -8 0. 25-5. 0 2.0 Average Diameter of Fine Solids, microns 0-1, 000 40-500 100 Bed Conditions:

Bulk Density of Shale C01- umn, lbs/it. 30-110 60-90 75 Loading Density of Fine Solids Suspension, lbs./ ft. 1 0. 02-5. 0 0.1-3.0 2.0 Minimum Interstitial Velocity of Fine Solids Suspension, ftJsec 3.0 4.0 10.0

1 Loading density being defined as the ratio of pounds of entrainable solids introduced/standard cubic feet of carrier gas passing through the treating zone, both taken for a given time interval.

It should be clearly understood that various modifications may be made to the present invention. Distribution means such as grids, baffles, nozzles or the like may be provided to insure good distribution of the fine solids suspension across the coarse shale column and to control solids holdup. Additionally, individual features discussed in connection with any of the illustrated systems may be applied to modifying other systems described. Basically, the present invention teaches supplying heat to a column of oil-bearing material by the use of a suspension of hot, entrainable solids, and is, as far as the art permits, to be construed as applying to all variations of this fundamental concept.

Having described the invention, what is claimed is as follows:

1. In a process for recovering oil from an oil-bearing solid shale material wherein said oil-bearing solid shale material is transported as a downwardly moving solids bed, the method of effecting heat treatment of said oilbearing shale solids which comprises introducing a suspension of entrainable fine solid particles and propellant fluid into the bottom portion of said bed for upward passage therethrough, said fine solid particles being at a higher temperature than said oil-bearing shale solids and passing said fine solid particles in fluid suspension upwardly through and out of said bed thereby ettecting heat treatment.

-2. The method of claim 1 where said oil-bearing shale material is relatively coarse shale ranging in size from 0.25 to 5 inches in diameter and said entrainable fine solid particles are sand ranging from 40-500 microns in size.

3. A process for recovering oil from oil-bearing shale solids which comprises the steps of preheating said shale solids in a preheating zone, passing the thus preheated solids in the form of a downwardly moving compact solids column into a retorting zone wherein they are retorted by countercurrent contact with an upwardly flowing hot gaseous suspension of fine entrainable solids, removing oil vapor from said retorting zone, continuing the downward passage of said oil-bearing solids, withdrawing at least a portion of said gaseous suspension of entrainable solids from said moving solids column in said preheating zone and separating said entrainable solids, subjecting said separated entrainable solids to heating in a heating zone, and circulating the thus heated entrainable solids to further contact said moving solids column in said retorting zone.

4. The process of claim 3 where said oil-bearing solids are heated in a preheating zone by contact with gaseous effluent of a combustion reaction.

5. The process of .claim 3 wherein said entrainable solids are heated in a burning zone, heat being generated by the combustion of carbonaceous matter of spent oilbearing solids.

6. The process of claim 3 wherein said entrainable solids are heated in a heating zone by means of the thermal energy liberated by the oxidation of a combustib'le gas.

7. A process according to claim 3 wherein said gaseous suspension of entrainable solids is withdrawn from the upper portion of said preheating zone.

8. A process according to claim 7 wherein said withdrawn gaseous suspension is heated in a combustion zone below and in communication with said retorting zone and said heated gaseous suspension is passed upwardly through said retorting zone.

9. A method for retorting oil-bearing solids which comprises progressively passing said solids as a gravity flowing moving compact bed downwardly through a preheating zone and a retorting zone countercurrent to an upflowing gaseous suspension of hot entrainable solids, heat for said preheating and retorting zones being supplied by said entrainable solids, said entrainable solids having been previously heated by means of the combustion of a combustible gas.

10. A thermal process for recovering oil from oilbearing shale solids which comprises flowing relatively coarse oil-bearing shale solids as a downwardly moving compact bed progressively through a preheating zone, retonting zone, and combustion zone, passing an oxygencontaining gas into said combustion zone so as to burn off carbonaceous residue on said oil-bearing solids, withdrawing hot flue gas produced thereby and passing said flue gas to a separate heating zone containing a mass of fine solids so as to heat said solids, introducing at least a portion of said heated fine solids from said heating zone into said retorting zone in the form of an upflowing gaseous suspension so as to supply thermal energy for the retorting operation, removing oil vapors from said retorting zone, withdrawing said gaseous suspension of fine solids from said retorting zone, and separating at least a portion of said fine solids and returning it to said heating zone.

11. The process of claim wherein at least a portion of the partially cooled flue gas is further circulated from said separate heating zone to said preheating zone for additional thermal exchange.

12. The process of claim 10 wherein at least a portion of said fine solids from said heating zone is passed through said preheating zone in the form of a gaseous suspension thus supplying heat thereto.

13. A process for recovering oil from shale particles which comprises feeding shale particles to the upper portion of a preheating zone, preheating the shale particles in said preheating zone, passing the preheated shale particles into a retorting zone and then to a combustion zone, said zones being arranged one above the other in the order named, said shale particles moving downwardly through said zones as a moving bed, passing a gaseous suspension of fine entrainable solids upwardly through said zones in countercurrent flow tosaid moving bed of shale particles, introducing air into said combustion zone for upward passage therethrough and for burning carbonaceous residue from spent shale particles moving from said retorting zone to and through said combustion zone, said gaseous suspension of fine entrainable solids being heated in passing upwardly through said combustion zone, passing said heated gaseous suspension of fine entrainable solids upwardly through said retorting zone to heat the shale particles and to remove oil from said shale particles, removing oil vapors and entrained solids from said retonting zone, passing the hot gaseous suspension of fine entrainable solids upwardly through said preheating zone, removing the gaseous suspension of fine entrainable solids from the upper portion of said preheating zone, and removing cooled spent snale particles from the bottom portion of said combustion zone.

14. A process according to claim 13 wherein fine entrained solids are separated from said gaseous suspension removed from the upper portion of said preheating zone and the separated fine solids are returned to said combustion zone below the region of introduction of the air.

15. A process according to claim 13 wherein the solids entrained in the oil vapors are removed and returned to the lower portion of said preheating zone.

16. Apparatus for recovering oil from relatively coarse oil-bearing solids which comprises, in combination, a re tort vessel, a preheating vessel above said retort vessel, 3; fine solids heating vessel, feed means for introducing oilbearing solids into said preheating vessel, means for passing preheated coarse solids from said preheating vessel into said retort vessel in the form of a downwardly moving bed, means for maintaining a mass of entrainable fine solids in said heating vessel, means for withdrawing said entrainable solids from said heating vessel and for introducing a gaseous suspension of said entrainable solids into said retort vessel, removal means for withdrawing gaseous material from said retorting vessel and separation means for separating entrained solids therefrom, conduit means for returning at least a portion of said separated solids to said heating vessel, passage means for removing said oil-bearing solids from said retort vessel, a combustion unit, means for supplying fuel and oxygen-containing gas to said combustion unit and conduit means for passing hot flue gas from said combustion unit to said heating vessel.

17. Apparatus according to claim 16 wherein said heating vessel is a combustion zone, and which further comprises conduit means for introducing a combustible fuel material and an oxygen-containing gas to said heating vessel.

References Cited in the file of this patent UNITED STATES PATENTS 2,480,670 Peck Aug. 30, 1949 2,680,091 Barr et al June 1, 1954 2,710,828 Scott June 14, 1955 2,776,935 Jahnig et a1. Jan. 8, 1957 2,889,267 Barr et a1. a- June 2, 1959 UNITED STATES PATENTOFFICE CERTIFICATE OF CORRECTION Patent No. 2,992,975 v July 18, 1961 Eger V. Murphree It is hereby certified that error appears in the above numbered petent requiring correction and that the said Letters Patent should read as corrected below.

In the heading to the printed specification, line 2, in the title of invention, for "OLD" read OIL in the heading to the drawings, Sheets 1, 2 and 3, in the title of invention, for "OLD" read OIL Signed and sealed this 2nd day of January 1962.,

(SEAL) Attest:

ERNEST W, SWIDER DAVID L. LADD At t e s t 1 ng Of 1? 1 c e r Commissioner f Patents

Claims (1)

1. IN A PROCESS FOR RECOVERING OIL FROM AN OIL-BEARING SOLID SHALE MATERIAL WHEREIN SAID OIL-BEARING SOLID SHALE MATERIAL IS TRANSPORTED AS A DOWNWARDLY MOVING SOLIDS BED, THE METHOD OF EFFECTING HEAT TREATMENT OF SAID OILBEARING SHALE SOLIDS WHICH COMPRISES INTRODUCING A SUSPENSION OF ENTRAINABLE FINE SOLID PARTICLES AND PROPELLANT FLUID INTO THE BOTTOM PORTION OF SAID BED FOR UPWARD PASSAGE THERETHROUGH, SAID FINE SOLID PARTICLES BEING AT A HIGHER TEMPERATURE THAN SAID OIL-BEARING SHALE SOLIDS AND PASSING SAID FINE SOLID PARTICLES IN FLUID SUSPENSION UPWARDLY THROUGH AND OUT OF SAID BED THEREBY EFFECTING HEAT TREATMENT.

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