4. A METHOD OF RECOVERING HYDROCARBONS FORM TAR SANDS WHICH COMPRISES MAINTAINING A FIRST ZONE CONTAINING A SUPPORTED BED OF SOLID MATERIAL AT A TEMPERATURE BETWEEN ABOUT 250*F. AND ABOUT 600*F.; INTRODUCING TAR SAND AGGLOMERATES HAVING AN AVERAGE PARTICLE SIZE RANGING FROM ABOVE ABOUT 1/2 INCH TO ABOUT 4 INCHES INTO SAID ZONE, INTRODUCING RELATIVELY HOT CONTACT MATERIAL OBTAINED FROM A SECOND ZONE AS HEREINAFTER DEFINED AND ADMIXING SUCH CONTACT MATERIAL AND AGGLOMERATES IN SAID FIRST ZONE UNDER TEMPERATURE AND PRESSURE CONDITIONS TO REDUCE THE VISCOSITY OF THE HYDROCARBON AND DRIVE OFF WATER FROM THE AGGLOMERATES THEREBY PROVIDING A FLUIDIZABLE MIXTURE OF
s 5 O m n@ y @N wwwa w @l W 1 ma r 2. kuxbk .I a. p. SRR 5 www, wm/ n? #La www N m May l5 w57 M. F. NATHAN ET AL FLUID COKING OF TAR SANDS Filed June l, 1965 United States Patent 3,320,152 FLUD COKNG 0F TAR SANDS Marvin F. Nathan, Westport, Conn., and George T. Slcaperdas, Westfield, and George C. Grubb, Little Silver, NJ., assignors to Pullman Incorporated, Chrcago, iii., a corporation of Deiavvare Filed .lune 1, 1%5, Ser. No. 460,366 6 Claims. (Cl. 28-11) The present invention relates to the recovery of hydrocarbons from tar sands, and, more particularly, the invention relates to the recovery of hydrocarbons from tar sands by fluid coking of the tar sands. Still more particularly, this invention relates to a novel and efficient method for introducing tar sands containing hydrocarbon as well as solid material into a iiuid coking zone.
Tar sands exist in various areas of the world and contain appreciable quantities of hydrocarbons. The Athabaska tar sands of Canada is one example of a deposit of such sands which comprise a vast reserve of hydrocarbon constituents. It is known that the oil content of such sands may vary from about 5% to about 21% by volume, the gravity of the oil ranging from about 6 to about 10 API. These sands may lie from about 200 to about 300 feet below an overburden and the beds may range from about 100 to about 400 feet in depth. As mined and received for processing, the tar sands are generally present as agglomerates or lumps consisting essentially of fine grain sand and clay, water, and viscous hydrocarbonaceous material called bitumin. These agglomerates may range in size from about 1/2 to 4 inches in diameter, depending upon the mining method and equipment employed. A`
typical oil recovered from the sands has an initial boiling point of about ElOOJ F., 1% distilled to 430 F., 20% distilled to 650 F. and 50% distilled to 980 F.
Unfortunately, the tar sands received from the mine in an agglomerated condition are apparently unsuited for direct introduction to a tluid bed conversion zone to recover the hydrocarbon values. Moreover, the Athabaska sands, for example, cannot be recovered readily by conventionai water techniques, since an amount of clay exists in the sands sufiicient to retard the recovery of the oil. For these reasons, prior art methods have proceeded by treating tar sands in accordance with solvent extraction techniques to prepare hydrocarbons for introduction to a suitable conversion zone. In accordance with one such solvent extraction technique, the tar sand agglomerates are -contacted with a suitable solvent such as a gas-oil boiling range fraction to produce a solution of bitumin and gasoil. Such solution is separated from the sand and is passed to a conventional hydrocarbon conversion unit, such as a fluid coking or cracking unit. Another extraction technique requires the addition of water to the tar sands and passage through a shearing-rnixing zone in order to separate an oil phase from -a water phase, the oil phase then being passed to a conventional hydrocarbon conversion unit. Unfortunately, the pretreatment of the tar sands by such techniques in order to separate an enriched hydrocarbon stream from the sand material substantially increases the recovery costs; and it is therefore desired to introduce tar sands directly into a suitable hydrocarbon conversion unit.
It is, therefore, an object of the present invention to overcome the inherent disadvantages of the prior art and to provide efficient method and means for the recovery of hydrocarbons from tar sands.
Another object of this invention is to provide an eicient method for the introduction of tar sands to a hydrocarbon conversion zone wherein a fluidized bed of solid material is maintained at an elevated temperature.
Another object of the present invention is to provide a method for introducing tar sands into a uid coking zone and maximizing the recovery of hydrocarbon oil.
3,320,152 Patented VMay 16, 1967 ICC Further objects and advantages of the present invention will become apparent to those skilled in the art from4 the following description and disclosure.
The objects are generally accomplished in accordance with the present invention by the introduction of tar sands agglomerates consisting essentially of sand particles and inert material, hydrocarbon material, and water, essentially as mined into a feed preparation zone, admixing relatively hot contact material with the agglomerates in the rst zone in order to drive oif water and reduce the viscosity of hydrocarbon material and thereby providing a liuidizable mixture of sand particles and hydrocarbon material. A portion of the fluidizable mixture is then passed through a pressure developing zone, e.g., such as a pressure developing column of the fluidizable mixture maintained in a standpipe, and introduced into a second zone, which is a reaction zone containing a tiuidized bed of solid particulate material, eg., such as a hydrocarbon conversion zone maintained under conditions suitable for carrying out thermal coking of the hydrocarbon material introduced thereto.
The term relatively hot contact material as employed in the specification includes solid contact material such as sand particles, for example, as well as gaseous material, such as hydrocarbon vapors, tlue gas, steam, or mixtures thereof, such contact material being at a substantially elevated temperature relative to the temperature of the tar sand agglomerates. The term tar sands agglomerates refers to the tar sands feed material essentially as it is received from the mining operation. The agglomerates consist essentially of sand particles and other inert material, eg., clay, held together in lu-mps of irregular size and shape Iby the -viscous hydrocarbon material and water.-
hot contact material in order to provide a uniform top` size which is prefer-ably about 1 inch in diameter. The temperature of the agglomerates fed into the feed prepa-ration zone is usually ambient temperature, although it is apparent that the feed can be preheated prior to introduction to the preparation zone. The term luidizable mixture employed in this specification to denote the y.
product of the feed preparation zone encompasses mixtures of hot contact material with sand and hydrocarbons derived from the feed agglomerates which have lost the characteristics of separate agglomerates having been owed together by the action of the elevated temperature con- Such iiuidizable mixtures can be iiowed` tact material. downwardly as a pressure developing column of solid material employing mechanical agitation as needed to Iprevent bridging in the column. It is pointed out that the term iiuidizable mixture, 'as employed herein, is not limited to those mixtures which maybe uidized by means of gaseous material, alone, but include owable mixtures of sand and hydrocarbons which are fluidizable by means of gaseous material in conjunction with mechanical fluidization aids, eg., such as hereinfater described, and by mechanical means, alone.
In accordance with a preferred embodiment of the method of the present invention, tar sands agglomerates are introduced into a feed preparation zone and admixed therein with relatively hot particulate material obtained from a reaction zone. The feed preparation zone is maintained under temperature conditions to convert the agglomerates and particulate material into a fluidizable mixture suitable for introduction as feed material into a yiuid coking zone and at a pressure suitable for introducing Iagglomerates into the feed preparation zone.
Mixing in the feed preparation zone is preferably carried out in a fixed bed agitated by suitable method and means to insure adequate intermixing of the agglomerates and hot particulate material, although it is within the scope of the present invention to employ a iiuid bed feed preparation zone. The relatively hot particulate material can be obtained at a suitable elevated temperature, which is preferably between about 400 and about 1400 F., from a hydrocarbon conversion zone, e.g., the coking zone, or from a heat generation zone employed in the process as hereinafter described. The ratio of relatively hot particulate material to agglomerates feed is preferably maintained between about 0.5:1 and 2.5:1 in order to regulate the temperature of the bed in the feed preparation zone at the desired level. Hot particulate material, such as sand, is a preferred hot contact material, since it serves as a fluidization promoting diluent for the sand-oil mixtures contained in the agglomerates feed as well as a heating medium to reduce the viscosity of the heavy hydrocarbons in the feed.
The temperature in the feed preparation zone is generally maintained at a level which is sufficiently high to cause reduction in the viscosity and expel water from the agglomerates feed such that the agglomerates are triturated, and yet, preferably, below the level at which any substantial percentage of the entering hydrocarbon material is converted to gaseous material which is not condensable under atmospheric pressure conditions, e.g., dry gas. It is important to minimize dry gas production at this point in order to minimize the cost of recovering hydrocarbon materials leaving the feeder as vapor. For these purposes, the preferred temperature range in the feed preparation zone is maintained between about 250 F. and about 600 F., and most preferably, between about 275 F. and about 450 F. The feed preparation zone is preferably maintained under essentially atmospheric pressure and most preferably under a subatmospheric pressure to prevent loss of gaseous material at the location where agglomerates are introduced. It has been found that agglomerates feed can be converted into a uidizable mixture employing relatively hot particulate material as the contact agent employing an agglomerates residence time in the feed preparation zone preferably between 1 and 10 minutes, it being understood, however, that a substantially longer or shorter residence time may be employed in such zone, depending upon the nature of the feed and conditions of operation of such zone.
The fluidizable mixture produced in the -first zone by the action of the relatively hot contact material admixed with the agglomerates feed is withdrawn from the feed preparation zone into a pressure developing zone for passage into a hydrocarbon conversion zone. The conversion zone preferably constitutes a coking zone containing a dense bed of uidized solids material operating at an elevated temperature and pressure substantially above the conditions in the feed preparation zone. Preferably, the feed preparation zone is situated at an elevation above that of the thermal coking zone such that the fluidizable mixture can be passed to the upper portion of a standpipe communicating between such zones for passage by gravity into the fluidized bed of the thermal coking zone. Suitable agitation means is provided preferably within the standpipe in order to prevent bridging of the standpipe. It is understood that when it is de'- sirable to locate the feed preparation zone and thermal coking zone in a side-by-side relation, the iluidizable mixture produced in the feed preparation zone can be owed therefrom into the coking zone by means of a transport line uidized, for example, by means of steam, air or other inert gaseous material.
The hydrocarbon conversion zone employed to convert the hydrocarbon material contained in the lluidizable mixture of tar sands and particulate material produced in the feed preparation zone comprises a iluidized bed 4. of particulate material maintained under thermal coking conditions which are well-known in the art. In the coking zone, heavy oil adhering to the solid particles undergoes pyrolysis, evolving lighter hydrocarbon vapors and leaving carbonaceous residue denoted as coke on the solids. Temperatures between about 850 F. and about 1100 F. and pressures between about atmospheric and about 40 p.s.i.g. are preferable. Particulate material bearing coke at the surface thereof is passed from the coking zone into a heat generation zone in which coke is burned thereby raising the temperature of the particulate material to an elevated level. Heated particulate material at a temperature preferably about 200 F. to 300 F. above the temperature in the conversion zone and in the range from about 1050o F. and about 1400o F. is passed from the heat generation zone into the coking zone to supply heat required for the coking operation.
For a better understanding of the present invention, reference is now made to the drawing which shows, diagrammatically, in elevation, a preferred embodiment of the method of the present invention which is described in conjunction with a working example of the operation thereof. Conveyor 10 introduces feed material into hopper 12 situated in an upper portion of mixing vessel 14. The feed material consists of tar sands agglomerates which have been reduced in size and screened such that the maximum diameter thereof is about 1 inch. The temperature of the feed is about 32 F. and the bulk density is about pounds per cubic foot. The feed composition is about 85% solids, 12% 'hydrocarbon and 3% free moisture on a weight basis. The diameters of the lsand particles in the agglomerates range between about 1-200 microns, and clay particles in the feed may have diameters even below 1 micron.
The agglomerates are introduced into feed preparation zone 14 at the rate of 4,166,500 pounds per hour and -are distributed about the periphery of a xed bed 26 by means of a conical distributor plate 16. Solid particulate material comprising sand particles bearing a small amount of coke on the surfaces thereof is withdrawn from a bottom portion of coking zone 42 at a temperature of 930 F., and is passed upwardly through risers 30 at a rate of 2,716,000 pounds per hour. The solid particulate material in conduits 30 pass into enlarged conduit sections 30A for discharge at a reduced velocity above distributor plate 16. An opening is provided between conduits 30 and 30A to permit free movement of rake 24. The hot sand is mixed with agglomerates at the periphery of bed 26 which is maintained at a temperature of about 300 F. A vacuum of about l inch Hg is maintained above bed 26 by the evacuation of gaseous material as hereinafter described.
The water and some of the hydrocarbons in the agglomerates are vaporized by the contact of hot solids with the incoming feed in feed preparation zone 14. Vaporized material, entrained solids, and air leakage through hopper 12 are withdrawn overhead of zone 14 by means of conduit 38 and are passed into cyclone 39 wherein solids material is separated and returned to bed 26 by means of dipleg 40. Gaseous material separated from cyclone 39 is passed into condenser 127 in line 125 to condense water and hydrocarbons in the gaseous material. A gas-liquid mixture thus obtained is owed into separator 130 operated at F. and about 14 p.s.i.a. Gaseous material, which comprises inerts, is withdrawn from the separator in purge line 126, which can be connected to a steam jet ejector, for example, in order to maintain a vacuum. A water layer is separated and discarded in line 128 and the condensed hydrocarbon oil is recycled to coking zone 42 in line 132.
Returning to the description of feed preparation zone 14, rake 24 is provided for mixing hot sand withdrawn from zone 42 with the cold feed. Prongs 24A depend from the rake and are preferably made plow-shaped in order to induce the material of bed 26 to llow inwardly toward standpipe 32. Rake 24 is rotated by means of the motive force supplied by an electric motor 20 connected to gear box 23 through rod 22. The rake 24 is rigidly attached to elongated rod 27 which is rotatably connected to gear box 23. Floor 25 is pitched toward the center of zone 14 such that the material in bed 26 flows generally toward the center under the inuence of prongs 24A. Shroud 18 is provided to protect gear box 23. Zone 14 is 35 feet in diameter and bed 26 is maintained at a depth of about 4 feet. The average holding time in bed 26 is about 3.2 minutes which is sufficient to reduce the agglomerate feed material to a mixture of uidizable particulate and hydrocarbon materials. The mixture flows from bed 26 over the upper edge 2.8 of standpipe 32 for passage downwardly therethrough.
Standpipe 32, centrally disposed within zone 14, provides a passageway for the fluidizable material obtained from fixed bed 26 into the dense bed of lluidized particulate material 46 maintained in coking zone 42. The standpipe comprises means for owing a pressure developing column of fluidized solids material from a feed mixing zone 14 operated at essentially atmospheric pressure into a fluid coking zone 42 operated at a relatively higher pressure. In this example, the standpipe has an inside diameter of about 4 feet. Elongated rod 27 rotatably connected to gear box 23 rotates within the standpipe 32. A plurality of bars 29 are angularly mounted on rod 27, although other suitable agitation means for the prevention of solids bridging of the standpipe can be employed such as, e.g., a screw feeding means. The aforementioned uidizable tar sands mixture is discharged from standpipe 32 into dense fluid bed 46. In this example, bed 46 is operated under coking conditions including a temperature of about 930 F. which is maintained by the introduction of solids material obtained from two separate heat generation zones, such as zone 60, at the rate of 10,675,000 pounds per hour per generator through valved conduits 75. The temperature of the solids introduced from the heat generators is about 1200 F. The pressure above dense bed 46 in vessel 42 is maintained at about 10 p.s.i.g. while the pressure below battles 48 is about 30.8 p.s.i.g. Residence time of about 5.2 minutes is provided in dense bed 46 and further residence time is provided in the region of baffles 48 in the lower portion of coking zone 42. Fluidization gas is provided below baffles 48 by the introduction of steam through distributor rings 51. Additional uidization is provided in bed 46 by reason of dry gas generated during the coking operation. Bafes 4S which can be made in any suitable shape and arrangement, such as the staggered inverted V-shaped bailles shown in the drawing, aid in stripping hydrocarbon vapors from the outlet solids and in minimizing by-passing of fresh feed material to the outlet at the bottom of zone 42.
Risers 30 depending into the lower baffled portion of zone 42 comprise means for conveying stripped hot contact material into the feed preparation zone. Lift steam is supplied to the base of risers 30 by means of injection lines 47 situated at the bottom thereof. Vertical baile 49 disposed Within the bottom central portion of zone 42 divides the baffled section into essentially two equal parts. Stripped solid particulate material having coke deposited on the surface thereof is withdrawn to the heat generators 60 through valved standpipes 50 and transport lines 55. Aeration steam is introduced into standpipes 50 by means of lines 52 and lift air is introduced into transport lines 55 by means of lines 54.
Staged cyclones 43 are provided in the upper portion of coking zone 42 to reduce the solids content of the gaseous effluent of the reactor. Solid material is returned to bed 46 bv means of diplegs 44. Effluent vapors and entrained solid material pass from cyclones 4.3 into plenum chamber 45 and then through withdrawal conduit 140 for passage to the vapor recovery system. Conduit 140 is heated by means of steam jacket 142. Superheated steam is introduced into steam jacket 42 by means of line 144. To
minimize the formation of coke in the cyclones and vapor outlet line 140, the superheated steam in jacket 142 is injected by means of line 146 into cyclone inlet 147. The steam injection is regulated such that steam introduced reduces the partial pressure of the heavy hydrocarbons in the effluent, i.e., the 850+hydrocarbons in the coker eluent vapor, from saturation to a condition about 30 F. above the dew point. In this example, about 63,000 pounds per hour of steam at about 930 F. and 600 p.s.i.g. are introduced by means of line 144 into jacket 142 and then into the cyclones via line 146.
The coker eflluent vapors are passed from conduit into effluent scrubbing zone 150 wherein the eluent is contacted with circulating oil introduced at about 600 F. in line 152 in lorder to cool the etiluent and to remove solids therefrom. The circulating oil consists essentially of 850+material- Scrubbing is achieved by flowing the circulating oil downwardly over bafilesv 154 in intimate countercurrent contact with the upflowing eluent vapors.
Substantially all of the entrained solids are scrubbed from the effluent Vand are withdrawn with the circulating oil fraction at the bottom `of scrubber 150 in lines 156. The circulating oil which is heated to about 700 F. in scrubber 150 is cooled in a steam generator 160 which generates 600 p.s.i.g. saturated steam in line 161 from boiler feed water introduced in line 159. The cooled circulating oil is recycled to the scrubbing Zone in lines 162 and 152. Make-up oil is added in line 163 as needed. A portion of the oil from line 156 is recycled for conversion into reactor 42 by means of lines 164 and 165. In this example, the quantity of recycle oil comprises 125,000 pounds per hour, and the solids content of this recycle oil is approximately 5 weight percent. Another portion of the 850-l-oil is fed to the heat generators in line 166 for use as torch oil.
Product eluent Vapor is withdrawn from scrubber 150 by means of withdrawal conduit and passed in line 172 into an electrostatic precipitator 174 to insure substantially complete removal of the solids from the product vapor feeding the product fractionator (not shown in the drawing). Water is introduced to the b-ase of the electrostatic precipitat'or in line 178 at 70 F. and water containing solids material is withdrawn from the base of the precipitator and passed to waste in line 180. Product vapors are withdrawn from precipitator 174 in line 176 lat `a temperature of about 600 F. and a pressure of about 9 p.s.i.g. The composition and flow rate of the feed to the product fractionator is shown below in Table 1.
TABLE 1 Product sent t0 final fractionation Components: Pounds per hour Dry gas y57,500 C4S 8,800 C5-380I 53,700 S80-850 248,950 850+ 74.050 Recycle oil 125,000 H2O 129,000
The coke make in reactor 42 is about 57,000 pounds per hour.
In this example, two heat generation zones 60 are employed to supply the heat requirements for coking zone 42. In order to supply the required heat for the process, the heat generators combust coke formed in the coker introduced in transport line 55, a portion of the 850+ liquid product introduced in line 166, and about 20% of the dry gas product introduced in line 79. The heat generators, in this example, are maintained at a temperature of about 1200 F. by the combustion and at a pressure of about 7 p.s.i.g. In order to provide iluidiz-ation gas in dense bed 64, and oxygen for combustion yof coke and hydrocarbonaceous material in the heat generation zone, air is preheated to about 944 F. and introduced by means of line 115 to distributor ring 66 situated in the bottom portion of the heat generators. The coke content of the solids is reduced to about 0.4 weight percent operating at an oxygen concentration in the iiue gas of about 0.5 mol percent. Since 0.4 weight percent of the solids represents about of the total coke make, it is desirable to employ a secondary coke burner 81 to reduce coke loss to about .2 weight percent or about 12 Weight percent of the total coke make. The air feed in line 116 to the secondary gas distributor ring 84 comprises about 10% of the total combustion air while `about 85 percent is fed to distributor 66. The remaining air is introduced into the heat exchangers, hereinafter described, and the transport lines 55. Entrance slots 82 are provided in the upper portion of the walls of secondary coke burner 81 to permit egress -of the solids from bed 64 into secondary coke burner 81. Combustion gases rising from the secondary coke burner pass upwardly through grid 80 into the lower portion of dense bed 64. To control the temperature of the secondary burner at the desired temperature, which in this example, is about 1050 F., cooling coil 83 is provided in the secondary burner. Preferably, coil 83 is employed to generate steam at an elevated temperature.
A portion of the solids in dense bed 64 are passed into stripping zone 70 through slot 71. Steam is introduced in line 76 through distributor ring 73 situated in a lower portion of the stripping zone and the steam passes upwardly through baffles 72 to strip inerts from the solid material. Employing the above-described stripping operation, the concentration of inerts recycled with solids to the reactor are Vreduced such that they represent about 1 mol percent in the nal dry gas product. Hence, such stripping operation is advantageous where hydrogen production is contemplated.
Spent solids flow by gravity downwardly from second- -ary coke burner 81 through conduits 86 into fluidized solids heat exchangers 88 containing tubes 90 -to recover high temperature level heat imparted to the solids. Cooled solids are withdrawn from the system in valved lines 99. The iiue gas produced at an elevated temperature in heat generators 60 is separated from solids in cyclone 62 having dipleg 63 depending therefrom. It is to be understood that any number of cyclones may be employed as needed in staged or parallel arrangement to reduce the solids content of the flue gas to an acceptable level.
In accordance with another exa-mple of operation, tar sands agglomerates at 32 F. are introduced into a feed mixing zone at the rate of 4,166,500 pounds per hour. The agglomerates -are contacted with flue gas from a heat generation zone at about 950 F. in the feed preparation zone. The composition and ow `rate of the iiue gas are indicated in Table 2 below:
TABLE 2 Components: Flow rate, lbs/hr. N2, O2, CO, CO2 1,777,540 H2O 201,000 Solids 500,000
A uidizable mixture of oil and solids is obtained at about 300 F. in the feed mixing zone and is withdrawn through `a standpipe downwardly into a fiuid coking zone. Such mixture consists of about 3,541,500 pounds per hour of solids, and about 500,000 pounds per hour of oil. Gaseous material is separated overhead of the fluid mixing zone Iat the rate of about 2,603,540 pounds per hour at about 300 F.
It is, likewise, contemplated that other hot contact materials in the gaseous state can be employed in the operation of the feed preparation method of the present invention such as, for example, hydrocarbon vapor condensable under conditions in the feed preparation zone 60 and steam. Many modifications and alterations will become apparent to those skilled in the art from the foregoing description and disclosure of the present invention which should be limited in scope, however, only by the claims.
What is claimed is:
1. A method `of recovering hydrocarbons from tar sands which comprises maintaining a first zone containing a supported bed of solid material at a temperature between about 250 F. and about 600 F.; introducing tar sand agglomerates having an average particle size ranging from above about 1/2 inch to about 4 inches into said zone and admixing Irelatively hot contact material therewith under conditions to reduce the viscosity and expel water from the agglomerates thereby producing a fluidizable mixture comprising sand and hydrocarbons, preferentially withdrawing a portion of said mixture having the smallest particle size, flowing said portion of such iluidizable mixture int-o a reaction zone containing a uidized bed of solid material, and passing solids material withdrawn from the uidized bed into said first zone as hot contact material.
2. A method of recovering hydrocarbons from tar sands which comprises maintaining a rst zone containing a supported bed of solid material at a temperature between about 250 F. and about 600 F.; introducing tar sand `agglomerates having an average particle size ranging from above about 1/. inch to about 4 inches into said zone and admixing relatively hot contact material therewith under conditions to reduce the viscosity land expel water from the agglomerates thereby producing a uidizable mixture comprising sand and hydrocarbons, preferentially withdrawing a portion of said mixture having the smallest particle size, flowing said portion of such iiuidizable mixture through a pressure developing column of such uidizable mixture into a `reaction zone containing a fluidized bed of solid material under temperature and pressure conditions above such conditions in said first zone, and passing solids material withdrawn from the fiuidized bed into said first zone as hot contact material.
3. A method of recovering hydrocarbons from tar sands which comprises maintaining a irst zone containing a supported bed of solid material at a temperature -between labout 250 F. and about 600 F.; introducing tar sand agglomerates having an average particle size ranging from above about 1/2 inch to about 4 inches into said zone and ladmixing relatively hot contact material therewith under conditions to reduce the viscosity and expel water from the agglomerates thereby producing a. uidizable mixture comprising sand and hydrocarbons, preferentially withdrawing a portion of said mixture having the smallest particle size, flowing said portion of such iiuidizable mixture into la pressure developing column of such fiuidizable mixture and communicating between said first zone and a reaction zone, providing agitation of such column and flowing the uidizable mixture into said reaction zone containing a dense fluidized bed of solid material, and passing solids material withdrawn from the uidized bed into said rst zone as hot contact material.
4. A method of recovering hydrocarbons from tar sands which comprises maintaining a iirst zone containing a supported bed of solid material at a temperature between about 250 F. and about 600 F.; introducing tar sand agglomerates having an average particle size ranging from above about 1/2 inch to about 4 inches into said zone, introducing relatively hot contact material obtained from a second zone as hereinafter defined `and admixing such contact material and agglomerates in said first zone under temperature and pressure conditions to reduce the viscosity of the hydrocarbon and drive off Water from the agglomerates thereby providing a uidizable mixture of sand and hydrocarbon material, preferentially withdrawing a portion of said fluidizable mixture having the smallest particle size into the upper portion of a pressure developing column of such uidizable mixture, flowing the mixture in the column into a second zone containing a dense fluidized bed of solids material maintained under hydrocarbon coking conditions including an elevated temperature and pressure, and passing solids material withdrawn from the dense fluidized bed at an elevated temperature into said first zone as said hot contact material.
5. The method of claim 4 in which relatively hot contact material is admixed with tar sand agglomerates in a ratio between about 0.5:1 and about 2.5: 1.
6. The method of claim 4 in which said rst zone is maintained under a pressure below atmospheric pressure.
References Cited by the Examiner UNITED STATES PATENTS 10 DANIEL E. WYMAN, Primary Examiner.
P. E. KONOPA, Assistant Examiner'.