US2726996A - Conversion of heavy oils by means of hot pebbles along a spiral path - Google Patents

Description

Dec. 13, 1955 1.. c. BEARER ET AL 2,726,996 CONVERSION OF HEAVY OILS BY MEANS OF HOT PEBBLES ALONG A SPIRAL PATH Filed April 28 1950 2 Sheets-Sheet l FIG. 5. INVENTORS.

L.C. BEARER R. R. GOINS BYWMW ATTORNE KS Dec- 3, 1955 L. c. BEARER ET AL 2,726,996

CONVERSION OF HEAVY OILS BY MEANS OF HOT PEBBLES ALONG A SPIRAL PATH Filed April 28 1950 2 Sheets-Sheet 2 STEAM TO PRODUCT 75 RECOVERY 62 5 I 5 OIL 6 i 6 OIL ELEVATOR PRODUCT TO QUENCH AND SEPARATION ZONE FIG. 6.

INVENTORS. L. C. BEARER R. R GOINS ATTORNEYS United States Patent huh CONVERSION OF HEAVY GIL-S BY MEAN S OF HGT PEBBLES ALQNG A SPIRAL PATH Louis C. Bearer Robert E. Gains, Bartlesville, Okia, assignors to Phillips Petroleum Company, a corporation of Delaware Application April 2S, 3350, Serial No. 158,716

8 Claims. (Cl. 196-55) This invention relates to the conversion of residuum oil stocks. In one embodiment this invention relates to process and apparatus for the utilization of a contiguous movingmass of particulate solids in cracking heavy hydrocarbon oils.

Hydrocarbon oil residuum stocks are by-product heavy residual or bottoms fractions, obtained from distillation of crude petroleum, or resulting from certain refining operations. When any further treatment of these stocks is attempted, such as distillation, or cracking, or the like,

excessive decomposition of the heavy material to carbon or heavy carbon-rich materials generally occurs, resulting in a rapid accumulation of carbonaceous deposits and necessitating shut-down of equipment after very short operating periods. Such short operating periods are uneconomical fro: l the standpoint not only of the cost of shutting down and subsequently starting up, but also with respect to the time and manpower requirements for removing the carbonaceous deposits and for readying the equipment for start-up. Furthermore, any desirable cracking product obtained is often of low quality and has it is often referred to, usually comprises a series of substanti'ally vertically-extending zones, often in vertical alignment with each other. Usually two such zones are employed and are connected by a relatively narrow interconnecting zone, or throat. The top or upper zone is commonly referred to as the pebble heating chambenand the lower zone as the gas reaction or gas heating chamber. A combustion zone, or chamber, is positioned adjacent or in close proximity to the sides of the lower portion of the heating chamber. Combustion gas from the combustion chamber is passed through the mass of pebbles in the pebble heating chamber. A hot gas source other than a combustion chamber is sometimes employed. A contiguous mass of particulate contact material, often referred to as pebbles, fills the pebble heating zone, the interconnecting zone or throat, and the gas reaction or heating zone, and flows downwardly through these zones by gravity. Pebbles are discharged from the bottom of the gas reaction zone at a controlled rate and returned, usually by elevating means, to the inlet in the upper portion of the pebble heating zone. A contiguous moving pebble mass thereby fills the pebble heating zone, gas heating zone, and the interconnecting zone, or throat, at all times.

The term pebble as used throughout the specification denotes any solid refractory material of fiowable form and size that can be utilized to carry heat from one zone 2,726,996 Fat-tented. Dec. 13, 1955 to another. Pebbles are preferably substantially spherical and about inch to 1 inch in diameter, the preferred range being about inch to /2 inch. Pebbles are formed of a refractory material which will withstand tempera tures at least as high as the highest temperature attained in the pebble heating chamber, and must be capable also of withstanding temperature changes within the apparatus. Refractory materials such as metal alloys, ceramics, or other satisfactory material may be utilized to form such materials. Silicon carbide, alumina, periclase, thoria, beryllia, stellite, zirconia, and mullite may be satisfactorily used to form such pebbles or may be used in admixture with each other or with other materials. Pebbles formed of such materials, when properly fired, serve very well at high temperatures. Some pebbles withstand temperatures up to about 3500 F. Pebbles which are used may be either inert or catalytic, as used in any selected process.

Pebble heater apparatus is generally employed in the thermal treatment or conversion of reactant materials, often hydrocarbons. Operation of such a pebble system generally involves circulating a contiguous pebble mass through the pebble heating chamber, interconnecting throat and reaction charnber. That portion of the pebble mass descending through the heating chamber is heated to a suitable predetermined temperature above a desired treating or conversion temperature in heat exchange relation with combustion gas or other hot gases from any desired source. Pebbles are often heated in the heating chamber to temperatures as high as from 2,000 to 3,000 F., and in some cases higher, dependent upon the temperature requirements of the subsequent treating step. The thus heated pebbles passing through the reaction chamber are contacted directly with the material to be treated or converted for a suitable contacting time to effect the desired treatment. The pebble mass having given up heat to the material treated in the treating zone, descends through the bottom of the reaction chamber and is fed to an elevator for further handling, generally for transfer to an inlet at the top of the pebble heating chamber for reheating and recirculation through the system.

In cracking oil residuum stocks in pebble heater apparatus in accordance with conventional methods, a considerable amount of agglomeration of pebbles with accumulated carbon and carbon-rich byproduct takes place after being on stream for only a short period with the result that pebble circulation is impaired, and often stopped entirely. This occurs particularly at the higher cracking temperatures required, in many instances being as high as from 1,000 to 1,7G0 F.

In introducing an oil residuum feed into contact with a mass'of pebbles, great difliculty is experienced in uniformly contacting all the pebbles in the mass, so that each pebble'is coated with an equal amount of oil. Instead,

-. disproportionately large amounts of oil reach only a relatively small portion of the hot pebble mass, with the result that large quantities of free flowing oil move through that small proportion of pebble mass contacted, while the remaining portion of the pebble mass passes through the system unutilized. Furthermore, considerable coking of the free flowing oil to form carbonaceous lay-product takes place, thus reducing efficiency of the conversion to a level not economically feasible; and agglomeration of pebbles and carbonaceous by-product thus formed, takes place. Such agglomeration of carbonaceous matter and pebbles is, of course, undesirable since the pebble system must then be shut-down for an extended period for removal of the agglomerate and for readying the equipment for re-start-up.

Our invention, in a broad embodiment, is concerned with the utilization of a contiguous moving mass of particulate solids in the treatment of residual oil stocks, particularly in a pebble heater system, under conditions preventing the agglomeration of the particulate contacting materials with carbonaceous by-product and providing for the conversion of the heavy charge material to valuable hydrocarbons, over periods of long duration.

An object of this invention is to provide for the conversion of hydrocarbons.

Another object is to provide an improved pebble heater apparatus.

Another object is to provide a process for utilizing a contiguous moving mass of particulate solids in the conversion of residual hydrocarbon stocks to lighter materials.

Another object is to provide an apparatus for uniformly coating all the solid particles in a contiguous moving mass of particulate solids, with an oil.

Another object is to provide process and apparatus for cracking oil residuum stocks in a pebble heater system, and for continuously removing from the system carbon and carbon-rich materials formed therein as by-products of the cracking.

Other objects will be apparent to those skilled in the art from the accompanying discussion and disclosure.

In accordance with one embodiment of our invention, we provide process and apparatus for introducing a hydrocarbon oil residuum stock into contact with pebbles in a pebble heater system in a manner such that all pebbles entering the conversion chamber have initially been uniformly coated with oil feed. In this manner some of the lighter components may be immediately vaporized upon contacting the hot pebbles, and such vapors are immediately withdrawnyheavier oil components remaining on the hot pebble surfaces are converted as the pebble mass moves downwardly through the conversion chamber as a result of the increased residence time in the pebble mass. Gaseous conversion products are withdrawn from the conversion chamber. As the pebble mass moves downwardly, the more refractory feed components remaining on the pebble surface are gradually converted to desired product as a function of the prolonged residence time. Finally, as pebbles approach the pebble discharge point in or near the bottom of the conversion chamber, the refractory carbonaceous by-product remaining on their surfaces is substantially dry as a result of the reaction of substantially all reactive components on the pebble surfaces to form conversion product. Pebbles carry the dry carbonaceous matter from the conversion chamber adhered to their surfaces, and are recycled to the heating chamber where they are reheated, burned free of carbonaceous matter, and recirculated.

The pebbles in the pebble mass are uniformly coated with the oil feed, by constricting the crosssectional dimension of the pebble stream at the point or points of contact of the oil and pebble mass, and by regulating the relative flow rates of pebbles and oil at those points. The pebbleoil contacting is eifected prior to entry of pebbles into the conversion chamber proper. All pebbles entering the conversion chamber are uniformly coated with oil, and the amount of oil introduced is limited to that coating the pebbles, so that agglomeration of pebbles with carbonaceous by-product, ordinarily taking place when there is free flowing oil in the pebble mass, is avoided. In this manner agglomeration of pebbles and oil is prevented and free flow of the pebble mass is maintained. Carbon or carbon-rich by-product materials thus formed adhere to the pebble surfaces, there being no other carbon containing by-product in the system. In this manner available surface area is provided for converting the more refractory feed components to cracking product and for continuously removing the final carbon residue in a most reduced form, from the conversion system.

Broadly, our invention provides for constricting the flow of a contiguous moving mass of particulate solids and introducing an oil feed stock in contact with the par- 4 ticulate solids from within that portion of the moving mass, at arate dependent upon the rate of solids flow and the cross-sectional dimension of the constricted moving solids mass.

Our invention, in a preferred embodiment, provides for introducing the oil feed into contact with pebbles in a pebble heater apparatus, at predetermined points within an interconnecting conduit or pebble throat, and for regulating the number of oil inlets with respect to the crosssectional dimension of the pebble mass moving through the throat, and then regulating the oil charge rate in relation to the rate of flow of the pebble mass through the throat. We have found that when we pass a stream of a contiguous mass of pebbles having a thickness or crosssectional dimension not exceeding 30 pebble diameters into contact with a single stream of hydrocarbon oil feed in a weight ratio of pebbles to oil feed of at least 14:1, at temperatures required for cracking such oil stocks, generally from 800 to 1700 F., the pebbles in the moving stream can be initially uniformly coated with oil and that agglomeration of pebbles and carbonaceous by-product is prevented. Accordingly, after contacting pebbles with oil feed, as described above, some lighter components of the feed may immediately vaporize, in which case such vapors are withdrawn immediately. The remainingfeed components are gradually converted to lighter product, as a function of prolonged residence time, as the pebbles pass downwardly through the conversion chamber, such product being withdrawn as formed. The conversion of the feed components in the conversion chamber is more extensive than can be obtained when employing pebble heater apparatus in accordance with conventional cracking methods. Consequently, in addition to the advantages discussed above, our invention provides for a more efficient process for cracking heavy oil residuum cracking stocks, both with respect to the high yields of desired products, and to the concomitantly lower yields of undesirable carbonaceous by-products that are obtained.

The accompanying diagrammatic drawings illustrate preferred forms of apparatus and process of our invention, and are discussed in terms of converting heavy hydrocarbons in a pebble heater system. It is to be understood however, that our invention is well applied also to the utilization of a contiguous moving mass of flowable solid particulate heat transfer materials of any type in converting oils, and that various modifications of the process and apparatus illustrated can be made and still remain within the scope of our invention.

Figure l is an elevation in cross section of one embodiment of apparatus of our invention, providing for injection of oil feed into the pebble throat of a pebble heater apparatus, at a plurality of points onto a layer of pebbles of regulated thickness passed downwardly over a conical surface, and then downwardly and away from the conical surface to provide pebbles uniformly coated with oil feed at the inlet to the conversion chamber. Figure 2 is a cross-sectional elevation of an embodiment of apparatus illustrative of a fixed screw member axially disposed in a pebble throat of a pebble heater apparatus, providing for limiting the thickness of a downwardly moving pebble layer and for uniformly contacting the pebbles with oil feed; Figure 3 is a cross-sectional elevation of an embodiment of apparatus of our invention, providing for passing the pebble stream through the pebble throat along a zig-zag path defined by alternate down-' wardly extending baffle members positioned to limit the thickness of the pebble layer, as discussed, and for introducing oil feed into contact with the pebble layer thus formed. Figure 4 is a plan view in cross section of an arrangement of apparatus providing for directly contact-'- the apparatus of Figure 4 taken along the line 55. Figure 6 is a cross-sectional view of the apparatus of Figure '1 taken along the line 66. Figure 7 is a crosssectional view of the apparatus of Figure 3 taken along the line 7-7. Figure '8 is a diagrammatic illustration of one manner in which the apparatus of our invention can be utilized in conjunction with conventional pebble heater apparatus, in the conversion of hydrocarbons.

Referring to Figure l, downwardly extending conduit 10 in communication at its upper end with pebbles in a pebble heater apparatus (not shown) extends vertically into housing, or shell, 11, and terminates therein at a distance of at least 4 pebble diameters above cylindrical baflie member 12 having an open bottom 13 and a perforate conical top 14, and axially disposed with respect to conduit 10. Conduit 16 is axially disposed with respect 'to baffle 12, in the bottom member 17 of housing member 11. Bottom member 17 is preferably conically shaped so that the contour of its interior wall portion simulates a cone. Vapor outlet conduits 18 are disposed in the top of housing 11. Oil inlet conduits 19 extend into housing 11 and terminate in a downward direction therein, at a point above the lower end 21 of conduit 10. Oil inlet conduits 22 extend into housing 31 and into cylindrical baffie member 12 and terminate therein in a downward direction, at points above open bottom end 13.

In the operation of the embodiment of Figure 1, the oil feed is injected into contact with flowing pebbles moving as a layer over conical surface 14, and downwardly from surface 14 through annulus 23, described hereafter. The thickness of the pebble layer on surface 14 preferably does not exceed 30 pebble diameters. The Width of annulus 23 is limited to that at which no bridging of pebbles takes place, generally a minimum of about 4 pebble diameters. Operating in this manner, substantially all pebbles passed over surface 14 and on through annulus 23, are completely coated with oil and no free flowing oil is present in the pebble mass. However, in some instances all of the oil may not immediately coat the pebbles, in which case the small amount of free moving oil will eventually cover them as a result of the intermixing or" oil and pebbles that takes place. The annular space formed by baflie member 12 and housing 11 is preferably of about the same dimension as the distance between conduit end portion 21 and the top of baffle member 12, so that the pebbles flowing from conduit 10 across the top of the conical surface 14 and on downwardly through annular space 23 and below cylindrical baflle member 12 into conduit 16, are moving at a relatively high rate to provide for uniformly contacting the oilwith the pebbles by virtue of the mixing and intermingling of pebbles and oil that takes place along this line of pebble flow. In order to prevent the presence of excess free moving oil in the pebble mass as it passes downwardly through housing 11, the weight ratio of pebbles to oil introduced into contact therewith is maintained at a value not lower than 14:1, such ratios-preferably being higher, often from about :1 to :1. Although higher ratios can be employed in the practice of our invention, a portion of that flowing pebble mass would pass through the system without being contacted with oil feed. The total oil introduced into contact with pebbles, whether through all the conduits 19 and conduits 22, or only some of these conduits, is the amount of oil referred to in the weight ratio of pebbles to oil discussed above. In some instances it may be advantageous to introduce all of the oil feed through conduits 19, but in many instances uniform contact of oil with pebbles can more easily be achieved by employing conduits 22 in conjunction with conduits 19, or through conduits 22 alone.

With reference to Figure 2, upright cylindrical conduit, or shell, 31, connected at its upper end with a pebble heating chamber and at its lower end with a reaction chamber of a pebble heater apparatus, contains stationary screw 32 axially disposed with respect to chamber 31 and i having a diameter less than that o'f'chamb'er 3'1,"but only by less than one pebble diameter. The pitch of screw member '32 is such that pebbles passed on to the rib portions will continue to pass downwardly by gravity instead of forming a stationary pile, the pitch being necessarily above the angle of repose of the pebble mass, which angle is often from about 28 to 35, dependent on the size and shape of the pebbles and the characteristics of their surfaces. A plurality of oil inlets 33 extend through the side wall of chamber 31 and terminate above separate rib portions of screw member 32. The ribs of screw 32 "are; spaced apart a minimum distance of 4 pebble diameters and preferably not greater than 30, so that bridging of pebbles will not occur and all pebbles will be initially coated with oil. As stated above, a layer of pebbles hav-;

ing a thickness exceeding 30 pebble diameters can be employed, but under such conditions some pebbles may pass through the system Without being contacted with oil feed. In the operation of the embodiment of Figure 2 the total amount of oil introduced through oil inlets 33 is.

regulated to conform with the total amount of pebbles passed through chamber 31 to a value above the pebble to oil weight ratio discussed above. In introducing oil in contact with pebbles passing along the spiral path as determined by screw member 32, a large amount of mixing and churning of pebbles takes place to absorb all the oil added, so that pebbles leaving chamber 31 are all uni: formly coated with oil feed. Any vapors formed in chamber 31 as a result of initial contact of oil with hot pebbles are withdrawn from chamber 31 through at least one of a plurality of conduits 34. Pebbles leaving chamber "31. are uniformly coated with oil feed and are introduced into a reaction chamber of a pebble heater apparatus (not shown). 7

Referring to Figure 3, upright elongated conduit, or shell, 41 is connected at its upper end with a pebble heat ing chamber and at its lower end with a reaction chamber of a pebble heater apparatus (not shown). 'Bafile' members 42 comprise a series of battles alternately disposed along the length of chamber 41 so as to slope laterally and downwardly from opposite sides thereof, the

lower end 43 of each baffle being spaced from the wall ofchamber 41 a minimum distance of 4 pebble diameters and being spaced above the other also at a minimum dis-' tance of 4 pebble diameters, and preferably not more than 30 pebble diameters, for the same reason discussed above.

minate at a point within the chamber, preferably in a downward direction, each above a separate bafile member 42.

In the operation of the embodiment of Figure 3, hot pebbles from the pebble heating chamber are passed first. onto the topmost bafiie member 42, then from theend 43 thereof onto the next bafile member and continuously along a zig-zag path through chamber 41. The pebblesmoving on each of the bafile members are contacted with fresh oil feed, and the ratio of total pebbles to' total oil introduced into chamber 41 is maintained above the minimum weight ratio of 14:1, discussed above. In this man-- ner, pebbles moving along the bafiie members through contacting hot pebbles in chamber 41, and are removed through one or more of conduits 44.

Referring to Figure 4, a cylindrical upright conduit, or

shell, 51 is connected at its upper end with a pebble heating chamber and at its lower end with a conversion cham ber of a pebble heater apparatus (not shown). Oil'inlets 52 extend through the side wall of chamber51'an'd are disposed to terminate at points within the mass of pebbles 3 Vapor outlet conduits 44 extend from within chamber 41 to an outside point, at points directly under the upper end of each baffle member. Oil inlet conduits: 46 extend through the side wall of chamber 41 and ter-.

7 passing through chamber 51. A preferred arrangement of oil inlet conduits 52 is further illustrated with respect to the cross-sectional elevation of Figure 5, taken along the line 5 of Figure 4. i

Operating in accordance with the embodiment of Fig ure 4, the Weight ratio of total pebbles passed through chamber 51 to oil introduced into contact therewith is maintained above the minimum ratio of 14:1, discussed hereabove, and by disposing oil inlets 52 to terminate Within the pebble mass passing through chamber 51 at predetermined selected points pebbles are uniformly contacted with oil feed, and no free flowing oil is present in the pebble mass leaving chamber 51.

Figures 6 and 7 further illustrate the arrangement of apparatus in each of Figures 1 and 3 respectively, Figure 6 representing a cross-sectional view of Figure 1 taken along the line 6-6, and Figure 7 representing a crosssectional view of the apparatus of Figure 3 taken along the line 77.

With reference to Figure 8, operation of a pebble heater system in conjunction with apparatus and process of our invention is diagrammatically illustrated. In the operation of the pebble heater apparatus of Figure 8, a contiguous moving mass of pebbles is circulated through pebble heater chamber 61, pebble throat 60, and conversion chamber 63, pebbles being withdrawn from chamber 63 through conduit 64 and introduced into elevating means 66 for recycle through line 67 to the heating chamber. Pebble flow through the pebble heater system is regulated by means of star valve 70, or other suitable means well known in the art. Pebbles introduced into pebble heating chamber are passed downwardly in contact with upwardly flowing hot heat transfer gases introduced through line 68. Optionally, gases introduced into chamber 61 through line 68 may comprise components of a combustible fuel gas mixture which is then burned on the pebble surfaces in chamber 61, or burned in a separate combustion chamber immediately subjacent chamber 61 (not shown) to form hot combustion gases, which are then passed upwardly in contact with pebbles in chamber 61. In either case, pebbles passing downwardly through chamber 61 are heated in heat transfer relation with hot gases, to a level above'a predetermined conversion temperature required in chamber 63, discussed hereafter. Heat transfer gases, having imparted heat to pebbles in chamber 61, are discharged through line 69.

62, disposed in throat 60, comprising an apparatus of our invention such as illustrated in Figures 1, 2, 3, or 4, and further illustrated in Figures 5, 6, and 7. Throat 60 can be considered as comprising oil-feed contacting zone 62, with line 60 providing for conducting flow of pebbles into zone 62, and from zone 62, as illustrated in Figure 8. Oil is introduced into contact with pebbles in zone 62 through lines 65 in a total overall weight ratio of pebbles to oil above the minimum of 14:1. Pebbles and oil are intermingled in zone 62 in a manner described hereabove such that no free moving oil is present in the pebble mass discharged from throat 60 through zone 62, into conversion chamber 63. Upon contacting oil with pebbles in zone 62, some vapors immediately form and are withdrawn from zone 62 through line 75. Pebbles passing from throat 60 into conversion chamber 63 are coated uniformly with the total oil feed, except for any vaporization of lighter feed components that may take place upon initial contact of oil and pebbles. The temperature of pebbles moving through chamber 63 is controlled by the heating step in chamber 61, wherein the pebbles are heated to a temperature sufiiciently high to compensate for pebble heat losses that occur between zone 61 andzone 63, and to provide for introduction of pebbles into chamber 63 at a requisite conversion temperature. Generally the temperature of oil-pebbles entering chamber 63 will be within the limits of about 800 to 1700 F. As pebbles pass downwardly through chamber 63, the less refractory components of oil feed on the pebble surfaces are the first to react to form cracking product. As the pebbles continue downwardly through chamber 63 the more refractory components react to form cracking product as a function of the extended residence time, until pebbles approaching the lower end of chamber 63 contain only the most refractory oil components, most of which are finally reacted and remain as dry carbonaceous residue on the pebble surfaces. Pebbles discharged from chamber 63 through line 64 carry with them the residual carbonaceous by product in a dry form. Pebbles leaving line 64 are elevated to conduit 67 and returned therethrough into chamber 61, where they are reheated and burned free of carbonaceous matter, the burning being supported by the introduction of excess oxygen for that purpose through line 68.

Operating in accordance with the apparatus and process discussed with reference to Figure 8, there is substantially no free flowing liquid in the pebble mass, thereby preventing undue carbonization of masses of oil feed to form large pieces or chunks which would then agglomerate with pebbles to form large slow moving or stationary masses, and ultimately stop pebble flow entirely. In accordance with our invention as illustrated in Figure 8, the amount of oil with respect to pebbles, is regulated, and the intermixing of pebbles and oil is efiected in a manner so that pebbles are uniformly coated with the oil, and any carbon by-product remains on the pebble surface as residue and is continuously removed with the pebbles, from the conversion chamber.

Advantages of this invention are illustrated by the following example. The reactants and their proportions and other specific ingredients are presented as being typical and should not be construed to limit the invention unduly.

A heavy hydrocarbon oil residuum having an API gravity of 16, is charged into the interconnecting throatof a pebble heater apparatus having a throat diameter of 4 inches, at a'rate of 71 pounds per hour. Pebbles are circulated through the unit at a rate of 1850 pounds per hour, and seal steam is introduced into the bottom of the reaction chamber at 65 pounds per hour and into the top of the pebble throat at 20 pounds per hour. Efiluent gases and vapors are withdrawn from the space above the reactor pebble bed at a temperature of 1140 F. and are immediately quenched. Pebbles enter the reaction chamber at a temperature of 1180 F.

On the basis of the weight of oil feed, gaseous and liquid cracking products obtained amount to 91 per cent, 36% being recovered as gaseous product. The remaining 9 per cent is carbon, which is removed continuously from the system on the surfaces of pebbles withdrawn from the reaction chamber. No agglomeration of carbonaceous by-product with pebbles takes place. The total gaseous product has the following composition:

The following distillation and gravity characteristics Mol .percent' 9 further identify the charge stock employed and the liquid cracking product obtained.

4. The process of claim 3 wherein a plurality of streams of oil feed are introduced into said contacting zone in Original Feed Gasoline ght Gas Heavy Gas ASTM Distillation, F rap-400 011, 490 on, rgo 5 9 193 Vacuum Flash F. F.-750 F. F.900 F Evaporated .l 985 990 224 496 30 Cracked 1, 075 282 570 End Point-- 409 Rev 98. 0 930 Res 1. 0 6. 1

API Gravity, at 60 F 16.0 38.0 20.4

Sp. G. 79 F .l

As will be evident to those skilled in the art, various modifications can be made or followed, in the light of the foregoing disclosure and discussion, without departing from the spirit or scope of the disclosure or from the scope of the claims.

We claim:

1. A process for cracking a hydrocarbon oil residuum by contacting same in heat exchange relation with pebbles, comprising heating a mass of pebbles to a temperature above a predetermined requisite temperature for cracking said residuum, gravitationally passing pebbles thus heated downwardly through an initial oil-pebble contacting zone along a spiral path as a layer having a depth of from 4 to 30 pebble diameters, introducing a plurality of streams of liquid oil residuum into direct contact with hot pebbles at points from within said contacting zone disposed along said spiral path in a weight ratio of total pebbles to total oil thus contacted of from 14:1 to 30:1, removing vapor from said oil-pebble contacting zone at a plurality of points along said spiral path of pebbles, passing resulting hot oil-coated pebbles from said initial contacting zone to an oil cracking zone at said predetermined cracking temperature under time conditions to crack oil coated on said pebbles, and recovering vaporous oil cracking product from said cracking zone as a product of the process.

2. The process of claim 1 wherein pebbles are withdrawn from said cracking zone containing carbon on their surfaces and are recycled to said heating and burned free of carbon prior to being passed to said oil-contacting zone.

3. In a process for cracking a liquid hydrocarbon oil in heat exchange with hot pebbles, the improvement comprising passing a stream of pebbles, heated to a temperature at least as high as that required in said heat exchange, along a spiral path through an oil'pebble contacting zone, introducing at least one stream of liquid oil feed onto surfaces of pebbles in said contacting zone, coating pebbles with a film of said liquid oil feed in said contacting zone by maintaining pebble stream thickness therein of at least 4 pebble diameters and passing pebbles and oil into said contacting zone in a pebble to oil weight ratio of at least 14:1, thereby preventing undue carbonization of oil with concomitant agglomeration of pebbles and carbonaceous materials and impairment of pebble flow.

spaced apart relationship.

5. The process of claim 4 wherein a portion of hydrocarbon feed is vaporized in said contacting zone and wherein vapors are immediately withdrawn from said zone at a plurality of points each in spaced relation with points at which feed is introduced into said zone.

6. In a process for cracking a hydrocarbon oil residuum upon contacting same with hot pebbles, wherein the pebbles are first heated in a pebble heating zone to pro vide a cracking temperature when contacted with said oil residuum as described hereinafter, and then gravitated to a reaction zone through a throat inter-connecting said heating and reaction zones, and in said reaction zone contacting said oil residuum with said pebbles at said cracking temperature, the improvement comprising passing a stream of pebbles having a thickness of at least 4 pebble diameters, from said heating zone, along a spiral path through said inter-connecting throat, introducing at least one stream of said oil residuum onto surfaces of pebbles in said throat in a weight ratio of total pebbles to total oil of at least 14:1, thereby preventing undue carbonization of oil with concomitant agglomeration of pebbles and carbonaceous materials and impairment of pebble flow.

7. The improvement of claim 6 wherein said thickness of pebbles is in the range of 430 pebble diameters and said weight ratio is in the range of 14:1 to 30:1.

8. The improvement of claim 7 wherein said weight ratio is at least 20:1.

References Cited in the tile of this patent UNITED STATES PATENTS 1,702,738 Manley Feb. 19, 1929 1,976,000 Apgar et al. Oct. 9, 1934 2,338,573 Creelman Ian. 4, 1944 2,362,621 Fahnestock Nov. 14, 1944 2,389,399 Alther Nov. 20, 1945 2,438,261 Utterback Mar. 23, 1948 2,444,128 Anderson June 29, 1948 2,448,334 Watson Aug. 31, 1948 2,534,752 Beckberger Dec. 19, 1950 2,614,824 Weber Oct. 21, 1952

Claims (1)

1. A PROCESS FOR CRACKING A HYDROCARBON OIL RESIDUUM BY CONTACTING SAME IN HEAT EXCHANGE RELATION WITH PEBBLES, COMPRISING HEATING A MASS OF PEBBLES TO A TMEPERATURE ABOVE A PREDETERMINED REQUISITE TEMPERATURE FOR CRACKING SAID RESIDUUM, GRAVITATIONALLY PASSING PEBBLES THUS HEATED DOWNWARDLY THROUGH AN INITIAL OIL-PEBBLE CONTACTING ZONE ALONG A SPIRAL PATH AS A LAYER HAVING A DEPTH OF FROM 4 TO 30 PEBBLE DIAMETERS, INTRODUCING A PLURALITY OF STREAMS OF LIQUID OIL RESIDUUM INTO A DIRECT CONTACT WITH HOT PEBBLES AT POINTS FROM WITHIN SAID CONTACTING ZONE DISPOSED ALONG SAID SPIRAL PATH IN A WEIGHT RATIO OF TOTAL PEBBLES TO TOTAL OIL THUS CONTACTED OF FROM 14:1 TO 30:1, REMOVING VAPOR FROM SAID OIL-PEBBLE CONTACTING ZONE AT A PLURALITY OF POINTS ALONG SAID SPIRAL PATH OF PEBBLES, PASSING RESULTING HOT-COATED PEBBLES FROM SAID INITIAL CONTACTING ZONE TO AN OIL CRACKING ZONE AT SAID PREDETERMINED CRACKING TEMPERATURE UNDER TIME CONDITIONS TO CRACK OIL COATED ON SAID PEBBLES, AND RECOVERING VAPOROUS OIL CRACKING PRODUCT FROM SAID CRACKING ZONE AS A PRODUCT OF THE PROCESS.

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