US2861943A

US2861943A - Hydrocracking process with the use of fluidized inert particles

Info

Publication number: US2861943A
Application number: US299114A
Authority: US
Inventors: Jr James A Finneran; Frederick B Grosselfinger
Original assignee: Hydrocarbon Research Inc
Current assignee: Hydrocarbon Research Inc
Priority date: 1952-07-16
Filing date: 1952-07-16
Publication date: 1958-11-25
Anticipated expiration: 1975-11-25

Description

.A m. z,

FLUIDIZED INERT PARTICLES Filed July 16, 1952 PRODUCTS J. A, FINNERAN, JR., ETAL HYDROCRACKING PROCESS WITH THE USE OF PRODUC T5 Nov. 25, 1958 5TEAM+02 fFLU/D/Z/NG GAS United States Patent AOtice 2,861,943 Patented Nov. 25, 1958 HYDRUCRACKING PROCESS WITH THE USE'OF FLUIDIZED INERT PARTICLES James A. Finneran, Jr., Westbury, and Frederick B.

'Grosselfnger, New York, N. Y., assignors to Hydrocarbon Research, Inc., New York, N. Y., a corporation of New Jersey Application `luly 16, 1952, Serial No. 299,114 14 Claims. (Cl. 208-76) This invention relates to the high-temperature treatment of hydrocarbons and is more particulary concerned with a process and apparatus for the eficient production of high octane gasoline from heavy oils, especially those which have a high content of sulfur, nitrogen or metal compounds.

In modern petroleum refining practice, it is highly advantageous to convert part or all of the higher boiling fractions of crude oil to materials boiling in the gasoline range. This is effected by processes which involve the cracking of higher boiling hydrocarbons into hydrocarbons boiling in the gasoline range. However, available cracking processes, which are effective in the treatment of ordinary heavy oil fractions, are of limited effectiveness in producing gasoline of commercially acceptable quality from low grade, heavy hydrocarbon oils, such as sour crudes, petroleum residues, shale oil, coal tar and the like, which have a high content of sulfur and/or nitrogen and/ or metal compounds.

Various processes have been proposed for treating such stocks to produce commercially acceptable gasoline and lsome of these proposed processes have been commercially used with varying effectiveness. None of these processes has, however, been wholly satisfactory. Thus, a process which involves so-called delayed coking has been proposed and, in fact, occasionally utilized for processing heavy residues, serving in effect as a process for preparing a feed stock for subsequent conventional catalytic cracking. However, this processing scheme for heavy residues has several disadvantages. Primarily, the delayed coker is expensive with respect to both capital and operating costs, and produces large quantities of coke which is diliicult to market. In addition, the yield of hydrocarbons in the gasoline rangeis low, and this gasoline is relatively poor in octane rating, so that when it is added to the total pooled renery gasoline, over-all octane number is decreased significantly. Further, delayed coking does not effect adequate desulfurization of the charge and, as a result, the coker distillate which is used as feed for the catalytic cracker is of excessively high sulfur content, re-

sulting in inefficient and expensive operation of the cracker. ln many cases, a finished gasoline product of commercially acceptable sulfur content cannot be pre-V pared at all.

Propane deasphalting has likewise been proposed and commercially employed as a process for the preliminary treatment of the crude oil to provide a feed for a subsequent catalytic cracking operation. This processing scheme offers very few advantages over the delayed coking-catalytic cracking scheme described above, and is completely unsatisfactory for processing total or reduced crudes of high sulfur content.

As a result of the lack of a processing procedure which will economically produce gasoline from such heavy crude stocks, it has been customary practice to market many heavy sour crudes or petroleum residues of this character as Bunker C fuel oil or as asphalt, where possible. The Bunker C fuel oil market is, however, limited by reason of the difiiculty of selling a product of high sulfur content and the asphalt market is small relative to the large amounts of such stocks available. Thus many wells which would produce heavy sour crudes are shutin.

Since heavy crude oils of the type mentioned are forming an ever greater proportion of the total crudes available for gasoline production, the satisfactory processing of this type of crude, and particularly the processing of such crudes to produce high octane gasoline, are technical and economical problems of increasing importance.

In general, this invention is particularly applicable to the conversion of charge stocks which cannot be economically treated by conventional processes. It can eciently convert reduced crudes of high Ramsbottom carbon residue into economic yields of high octane gasoline. It can also be used on crudes which, regardless of carbon content, would produce a coke salable only for low grade fuel purposes by reason of its sulfur and/or nitrogen and/or metal content. It can be used on lighter oil stocks which contain catalyst poisons such as metals and, therefore, are unsuitable for direct charging to catalytic crackers.

A principal object of the invention is to convert hydrocarbon oils to gasoline with high yields.

A` further object is to provide a high-temperature treating process by means of which gasoline of high octane number s produced even from low grade, heavy hydrocarbon oils.

Another important object of the invention is the production of gasoline continuously and eiiiciently in a single reactor system.

Additional objects and advantages of the invention will be apparent from the description which follows.

In accordance with the invention, hydrocarbon oil is subjected to treatment at elevated temperatures in the presence of a particulate contact material or carrier and in a gaseous atmosphere produced by the reaction of carbon with oxygen and steam at temperatures above about 1600" F. and containing an amount of hydrogen which provides a hydrogen partial pressure of 35 to 200 p. s. i. (pounds per square inch), preferably tot 150 p. s. i., in the hydrocarbon treatment or reaction zone. The hydrocarbon oil, preferably preheated, is fed into the reaction zone (hereinafter designated as the primary cracking zone) containing the comminuted solid carrier in uidized condition. The primary cracking zone is superposed on and in communication with a higher temperature zone of restrained fluidization (hereinafter designated as the secondary cracking zone). Fluidization of the particulate carrier is restrained in the secondary cracking zone in the sense that the vertical movements of the uidized particles are restricted to the extent that a temperature gradient is established along the vertical dimension of the secondary cracking zone, ranging from the temperature of the primary cracking zone which is contiguous with the upper end of the secondary cracking zone to the higher temperature of the carrier regeneration zone which is contiguous with the lower end of the secondary cracking zone. Such restrained liuidization is obtained by filling the secondary cracking zone with coarse packing bodies of the type of Raschig rings and Berl saddles.

In the primary cracking zone, a deposit of heavy hydrocarbons and carbon forms on the carrier particles and these particles are passed with restrained liuidization downwardly through the secondary cracking zone countercurrently to a gaseous stream containing steam and the gaseous products of reacting carbon with oxygen and steam at a temperature above about l600 F., the gaseous stream thus contacting the carrier particles in intimate thin film relationship. From the secondary lcracking zone,

the particulate carrier passes into a subjacent regeneration zone wherein carbonaceous matter on the carrier is react-ed with steam and oxygen at a temperature in the range of 1600 to 2500 F. to produce the previously mentioned gaseous atmosphere required in both the primary and the secondary cracking zones. Besides hydrogen, this gaseous atmosphere contains carbonmonoxide, carbon dioxide and steam. The thus vregeneratedpar.- tieulate carrier is then returned to the primary cracking zone. The regeneration product gases, after passing yup,- wardly through the secondary cracking zone, enter the primary cracking zone to provide the atmosphere for the hydrocarbon conversion and are withdrawn together with the hydrocarbon conversion products from the top of the primary cracking zone.

From this gaseous effluent is recovered a high yield of high octane gasoline, even when the feed stock is a heavy crude or :residual *oil* containing large quantities of sulfur, nitrogen and metal compounds. This high yield of high octane gasoline is obtained with minimum formation of gaseous hydrocarbons and with an ecient recovery of liquidi hydrocarbons boiling above the gasoline range (i. e., boiling above Y400" F.) which may be recycled to provide additional gasoline or utilized as feed for a catalytic cracker or sold as fuel.

Inmo'st cases, the gasoline produced by the process of this invention'has a sulfur content within commercially desirable limits and is in other respects an acceptable product.V n those cases where, because of the excessively poor quality of the oil treated, the gasoline produced although'of much reduced sulfur content still contains more sulfur than is desirable or has less than the desired stability characteristics, the sulfur content and the stability characteristics can be brought to more desirable values by4 known refining processes7 e. g., catalytic treatment with hydrogen at elevated temperatures.

The particulate carrier which is employed in the process of the Ainventionis any solid heat-resistant material which may be fluidized, such as sand, quartz, alumina, myagnesia, zircon, beryl, bauxite or other like material, which will withstand the desired regeneration conditions including a temperature above 1600 F. without physically disintegrating or fusing.

The entirereaction system, i. e., the primary cracking zone, the secondary cracking zone and the regeneration zone, is maintained at a total pressure in the range of 150 to 800 p. s. i. g. (pounds per square inch gage), preferably at 2.50 to 80.0 p. s. i. g. Under these conditions, the desired hydrogen partial pressure of 35 to 2,00 p. s.l i., preferably 75 to 150 p. s. i., is maintained in the primary and secondary cracking zones. A hydrogen partial pressure in excess of 200 p. s. i. is not necessary since maxi mum benefits from the presence'of hydrogen are obtained in the indicated range and there is little or no economic justification for employing a hydrogen partial pressure above 200 p. s. i. The usel o'f'total pressures in the indicatedlrange -also provides a high oxygenpartial pressure in the regeneration zone, increasingwthe ratev of 'rcgeneraf tion Yand consequently decreasing thenheight of this zione and that of the over-all system. The` indicated range` of total pressures .also allows efficient recovery of the nor-` mally liquid hydrocarbon products from the primary cracking zone effluent.

In the primary. cracking zone, the particulate carrier is maintained in freely uidized condition; a superficial linear gas velocity of 0.2 to 2.5, preferably of 0.4 to 1.0, feet per second .is generally provided vin the primary cracking zone. The temperature of the primary crackingL zone is maintained in the range of VS50/to 1 100 F., pref,` ferably in the range of 900 to 1050 F., by control of the temperature and quantity of carrier transferred from the, regeneration zone, and by control of the temperature toy which the hydrocarbon oil feed is preheated. The feed rate of hydrocarbon oilvisl desirably maintained at 0.2.toy 3.0, preferably 0.5 to 1.5, volumes of liquid oil peri/hour.

per volume of the primary cracking zone. The oil partial pressure, determined essentially by the rate of hydrocarbon oil feed and the volume of regeneration gas, may vary from about 5 to 100 p. s. i., preferably from 10 to 50 p. s. i. It is a feature of the invention that the preferred range of temperature is higher and the preferred range of oil partial pressure lower than generally employed in thermal cracking processes, and as a consequence the gasoline which is produced is considerably higher in octane number than that produced in such processes, approximately 90 CFRR octane number without use of tetra-ethyl lead or other anti-knock additives.

In the subjacent secondary cracking zone, the particulate carrier is subjected to restrained uidization by the presence of a fixed bed of packing bodies, e. g., Z-inch Raschig rings, so that the carrier particles are only per mitted limited vertical and lateral movements while they continuously progress downwardly and are progressively heated by the upflowing regeneration product gases. Materials or devices of the type designated as packing or trays, as are commonly utilized in fractionation, absorption or solvent extraction, are effective in providing the restrained uidization of the solid carrier which is desired in the secondary cracking zone. The selected packing must withstand the reaction conditions in the secondary cracking zone. Obviously, undue restriction of the ow of the carrier through the secondary cracking zone would adversely affect the transfer carrier particles vfrom the primary cracking zone to the regeneration zone and thus interfere with the eiciency of the entire process. It has Abeen yfound that the free horizontal area in the secondary cracking zone should for best results be 50 to 80% of the total horizontal area. This is particularly so when Raschig rings are employed.

As a consequence of the type of flow or particulate carrier which is obtained,y a temperature gradient is established in the secondary cracking zone, with the top of this zone essentially at the temperature of the primary cracking zone and the bottom essentially at theA temperature of the'regeneration zone. It is a feature of the invention that heavy hydrocarbons which are not fully converted to volatile products in the primary cracking zone and remain as a deposit on the surfaces of the carrier particles Vpass downwardly with the carrier through the secondary cracking zone and there are converted at increasing temperatures in contact with the hot gases from the regeneration zone. Thus, there is achieved efficient conversion of heavy hydrocarbons into more volatile products which are desorbed from the particulate carrier Vand are carried upwardly into the primary cracking zone for further conversion and thence recovery of an increased yield of hydrocarbons in the gasoline range. Accordingly, not only is a minimum of the adsorbed heavy hydrocarbons permitted to form a carbonaceous deposit but also the carbonaceous deposit to be burned in the regeneration zone is relatively dry, i. e., is relatively low in hydrogen content,` so that the oxygen rc-v quirernent's of the process are materially reduced. The carbonaccous deposit on the carrier entering the regenera tion zone usually amounts to about V5 to 15% by weight of the carrier.

While it is not desired to be bound by any particular theory of operation, experimental studies indicate that in the secondary cracking zone the steam and carbon monoxide present in the effluent from the regeneration zone undergo, the reaction:

H2O -1- COZiHZ-I-Coz As the temperature of the steam and carbon monoxide is decreased in passing upwardly through the secondary cracking zone, the equilibrium of the above reaction is shifted towardV the right to evolve an ever increasing.

2,se1,94a

Conversion of the oil to a carbonaceous residue even at relatively low hydrogen partial pressures. It has been determined that material benefits from the presence of nascent hydrogen are realized at a hydrogen partial pressure as low as 35 p. s. i.

In the regeneration zone, the non-volatile carbonaceous deposit on the particulate carrier is reacted with regenerating gas consisting essentially of steam and oxygen, at a temperature of at least 1600 F., more particularly in the range of 1600 to 2500 F. and preferably in the range of 1700 to 2000 F. The regeneration of the carrier results in the production of a gaseous mixture comprising essentially hydrogen, carbon monoxide, carbon dioxide and excess steam. The principal reactions by which the carbonaceous deposit is removed from the carrier include:

The regenerating gas contains a preponderance of steam and a minor proportion of high purity oxygen, the latter, more specifically containing at least about 90% by volume of oxygen, preferably at least 95% by volume of oxygen, and obtained, for example, by air liquefaction and rectification. The composition of the regenerating gas insures a maximum yield of hydrogen in accordance with the foregoing reactions. Steam-to-oxygen volume ratios in the range of 1.5 :l to :1 are generally satisfactory for generating the required quantity of hydrogen. It is preferable, as a practical matter, to employ a steamto-oxygen volume ratio of the order of 2:1 to 3:1 and thereby avoid a veryhgh `regeneration temperature. As a general rule, it is advisable to conduct the regeneration at a temperature approaching the maximum permissible with the carrier and reactor materials employed, utilizing the smallest steam-to-oxygen volume ratio which will provide the desired temperature control.

. The effluent gas mixture from the regeneration zone passes through the secondary and primary cracking zones, serving as the atmosphere for the hydrocarbon conversion reactions andas the principal medium for carrier fluidization.

An up-transport zone serves to return hot regenerated carrier to the primary cracking zone. In the up-transport zone which is fed with carrier particles from the regeneration zone, the carrier particles flow upwardly because of the lower fluid-static head extant in this zone. The gas velocity in the up-transport zone is generally over 0.5 foot per second and not above 5 feet per second, depending to a great extent on the particle size and densityy of the comminuted carrier utilized as well as the gas velocities in the other zones. The gas gelocity in the 11p-transport zone is preferably supplied by a stream of steam or, in some cases, by a stream of product gas from which all hydrocarbons containing more than two carbon atoms have been removed. In any case, the velocity employed is the lowest possible to obtain adequate circulation of carrier. The rate of circulation of the carrier is controlled to maintain the desired temperature in the primary cracking zone by regulation of the fluid-static heads in the various zones and/or by suitable valving between zones.

In another embodiment of the invention, there is provided a third cracking zone (hereinafter designated as the recycle cracking zone) which is in communication with and intermeidate the primary and secondary cracking zones. In this embodiment, .the recycle cracking zone is maintained at a temperature of at least F. higher than that in the primary cracking zone; the temperature in the recycle cracking zone rarely exceeds 1450 The additional recycle cracking zone is vemployed when it is `desirable. to recycle liquid products of the process boiling above the gasoline range in order to increase the yield of gasoline. Since the liquid hydrocarbon oil fed to the recycle cracking zone is more refractory than that fed to the primary cracking zone, the former is operated at a higher temperature. With a recycle cracking zone, there is also provided a second 11p-transport zone, through `which regenerated carrier is transported from the regeneration zone directly to the recycle cracking zone at a rate to obtain the desired temperature. Temperatures above 1250" F. are employed in the recycle cracking zone when it is desired to recycle to extinction liquid products boiling above the gasoline range so that the only recovered products of the process are gasoline and gas. This mode of operation, which permits the production of large amounts of gaseous fuel of high heating valve when the demand for such4 fuel is greater than that for low grade Bunker C fuel, is a feature of the invention which is made possible by the high regeneration temperatures utilized in the process.

The hydrocarbon conversion products of the process are separated from the primary cracking zone effluent by conventional methods. The gasoline product, which has a clear research octane rating of about 90, may be further treated, as previously mentioned, to effect additional desulfurization and to improve gum stability, when desired. Higher boiling products, if not recycled to extinction, are conventionally utilized as furnace oils or may be catalytically cracked. The normally gaseous portion ofthe total effluent may be used as fuel or utilized in syntheses requiring hydrogen and carbon monoxide as reactants.

To describe and explain this invention more fully, reference is made to the accompanying drawings wherein:

Figure 1 is a -diagrammatic vertical section of a reactor embodying features of the invention and adapted forA carrying out the above-described process; and

Figure 2 is a similar view of another reactor embodying features of the invention and particularly adapted for an operation involving the recycling of some of the liquid products.

The apparatus illustrated in Figure l comprises an upright cylindrical vessel 10 having opposed ends 12 and 14. In the lower portion of vessel 10 is disposed a concentric tubular shell 16 formed from a refractory insulating material such as fire brick, Alundum or the like, the outer surface of shell 16 being spaced from the inner surface of vessel 10 to define an annular dead space therebetween which is lled with the particulate carrier used in vessel 10. The shell 16 holds the regeneration zone 18 and the secondary cracking zone 20, which are separated by a perforated plate or grid 22. Shell 16 protects the metal walls of vessel 10 from the high temperatures which are attained in the regeneration zone and the secondary cracking zone. Secondary cracking zone 20 is filled with packing 23 to give restrained iiuidization of the carrier particles in zone 20. When the apparatus is in operation, it is filled with fluidized carrier to level 24 in primary cracking zone 26. The carrier is maintained in continuous circulation throughout vessel 10, moving downwardly from primary cracking zone 26 through secondary cracking zone 20 into regeneration zone 18 and thence returning to primary cracking zone 26. For the return of regenerated carrier there is provided an axial up-transport tube 28 extending upwardly from en-d 14 of vessel 10 through regeneration zone 18 and secondary cracking zone 20 with an outlet end 30 discharging into the bottom of primary cracking zone 26. Passage of regenerated carried into up-transport tube 28 is effected by means of a valve arrangement comprising an inlet aperture 32 in the wall of up-transport tube 2S and a valve body 34 mounted on a tube 36 which is exteriorly adjusted by turning threaded handle 35 to move tube 36 and valve body 34 in a vertical direction. Depending on the position of valve body 34, the inlet aperture 32 may vary from completely open to corn-,v`

7 pletely closed. Movement of the carrier upwardly through tube 28 is eifected by supplying a stream of fluidizing gas through tube 36 into up-transport tube 2S.

Steam yand oxygen are introduced into regeneration zone18 through an inlet conduit 38 provided with distributing means 40. The oil feed is in like manner introduced into primary cracking zone 26 through inlet conduit 42 provided with distributing perforations 44. The oil conversion products together with regeneration product gases are removed from vessel 10 through top outlet 46, a cyclone 48 being advantageously provided to remove at least some of the carrier which may be entrained in the efuent gases. The exterior of vessel 10 is, of course, suitably provided with` insulation (not shown) to prevent undue heat loss.

t Figure 2 shows a modifie-d form of the apparatus of Figure l particularly suited for operation with continuous or intermittent recycle of high boiling hydrocarbons. The apparatus of Figure 2 comprises a Vessel 110, a tubular shell 116 and

inlet conduits

138 and 142. Packing 123 is supported on grid 122 and extends to a level substantially below the top of shell 116. The space between the top of packing 123 and the top of shell 116 forms recycle cracking Zone 127 which is provided with recycle oil inlet conduit 131. There are two up-

transport tubes

128 and 129, extending upwardly into primary cracking zone 126 and recycle cracking zone 127, respectively. Since recycle cracking zone 127 is maintained at a higher temperature than that of primary cracking zone 126, the two uidization zones are separated by how-restricting means such as a grill, perforated plate or bafes. Figure 2 illustrates the flow-restricting means as a series of baffles 135. For a large temperature difference between zones 126. and 127, a shallow bed of packing bodies like Raschig rings may be supported on bafiles 135. When the apparatusl of Figure 2 is in operation, the total eifluent is treated to separate high-boiling hydrocarbons which are recycled to the apparatusy through inlet conduit 131.

The` following examples illustrate the invention more specifically without, however, being intended as limitative thereof.

EXAMPLE l Referring to Figure l, vessel 10 is charged with bauxite of 2,0 to 325 mesh size with 90% between 40 and 200 mesh, and steam is introduced through pipe 36 to fluidize this carrier. The oil feed is supplied through inlet conduit 42 while steam and oxygen of 95% by volume purity are introduced through inlet conduit 38. The oil feed is a East Texas residuum having the following characteristics:

Gravity, degrees API 14.0 Sulfur, wt. percent 0.82 Carbon, Ramsbottom, wt. percent 10.4

The total pressure in vessel 10 is maintained at 400 p. s. i. g., with a hydrogen partial pressure of 75 p. s. i.

The oil feed is preheated to about 800 F. and 'fed into.

primary `cracking Zone 26 at the rate of 0.5 volume of oil per hour per volume of primary ycracking zone. The temperature in primary cracking Zone 26 is 980 F. 4and the temperature in regeneration Zone 1S is l750 F. The temperature at the top of secondary cracking Zone is slightly above the temperature of zone 26 and progressively increases through zone 20 until the temperature at the bottom of secondary cracking zone 20 is slightly below the temperature of zone 18. The volume ratio of steam to oxygen introduced through inlet conduit 3S is 2:1. Duringbperation, the bauxite particles are in continuous circulation, passing from primary cracking Zone 26 downwardly through secondary cracking zone 20 into regeneration Zone 13 and thence being transported upwardly through up-transport tube 23 back to primary cracking zone 26. The flow of steam and oxygen through inlet conduit 38 and the iiow of steam through tube 36 and the setting valve 34 are controlled to obtain the specied pressures, and temperatures.

For purposes of comparison, another run is made -i-n the apparatus of -Figurel as used in Example l except thatthe Raschig ring packing 23 is removed. All of the operating conditions of Example l are repeated except that, in the absence of packing in the secondary cracking zone, the regeneration temperature does not rise above 1400o F. and heavy hydrocarbons carried by the bauxite leaving the primary cracking zone are not effectively converted into valuable hydrocarbon products in the secondary cracking zone. Thus, it is necessary to use twice as much oxygen as is used in Example 1. The conversion products of this example are shown in the second column o'f Table l. The coke and gas yields are materially higher than those for Example l and the production of valuable liquid productsy is correspondingly reduced.

EXAMPLE 3 A West Texas-New Mexico residuum is processed substantially las set forth in Example l. The specific. gravity, sulfur content and Ramsbottom carbon residue of this residuum are 7.5 API, 2.95% by weight and 20.2% by weight, respectively. The product yields are shown in the third column of Table l. The gasoline contains 0.44% `by weight of sulfur and has a clear CFRR octane rating. It is noteworthy that the coke yield is only about 70% of the Ramsbottom carbon residue of the feed, whereas in conventional processes such as delayedl coking, from which relatively low yields of relatively lowoctane rating gasoline are, obtained, the coke yields are approximately 120% of the Ramsbottom carbon residue of the feed.

EXAMPLE 4 Boscan (Venezuela) crude is treated in apparatus as shown in Figure 2. This crude is extremely heavy (10.5' API gravity) and has high contents of sulfur (5.0% -by weight), asphaltenic materials (13% by weight Ramsbottorn carbon residue), and Vanadium and other inorganic matter (ca. 0.3% by weight). When the apparatus of Figure 2 is operated with Ia primary cracking zone temperature of 985 F., a recycle cracking zone temperature of l000 F. and a regeneration temperature of 1800 F., andby recycling' hydrocarbons boiling in the range of 400 to 750 F. at the rate of 65 barrels per 100 barrels of crude fed to the primary cracking zone, the total recovered liquid yield corresponds to 79 barrels composed of 5 3 barrels of gasoline and 26 `barrels of heavier hydrocarbons.

The regenerating gas consists of steam and oxygen of by volume purity, the steam-to-oxygen volume ratio being 2.5:1. After-recovering from the total eflluent 79- barrels of liquid hydrocarbons per barrels of charged crude, there remains a gas having the followingl approximate composition (volumes are given in millions of standard cubic feet):

. 9 The clear research octane number of the gasoline obtained in this recycle operation on Boscan crude exceeds 90.

In view of the various modifications of the invention which will occur to those skilled in the art upon consideration of the foregoing disclosure without departing from the spirit or scope thereof, only such limitations should be imposed Ias are indicated by the appended claims.

Table 1 Example 1 2 3 Charge Stock 1 A 1 A l B Gravity, API 14. 0 14.0 7. 5 Operating Temperatures,

Primary Cracking Zone 980 980 970 Regeneration Zone 1, 760 1, 400 1, 750 Yields, Percent of Charge:

Gasoline (04400o F. E. P.), Vol. Percent. 85. 2 31. 4 36.1 Light Gas Oil (40G-650" F.) Vol. Percent.. 28. 5 28` 7 28. 3 Heavy Gas Oil (650 F. Vol.A Percent- 23. 6 15. 5 21. 4 Gas (O1-C3), Wt. Percent 10.1 15.6 8. 9 Coke,2 Wt. Percent 10.7 17.5 14.6

1 A=ast Texas Reslduum. B=West Texas-New Mexico Residuum. 2 Calculated from the carbon monoxide and carbon dioxide in the product gas.

What is claimed is:

1. The process of converting a heavy hydrocarbon oil to gasoline which comprises converting said oil directly to gasoline at an elevated temperature not exceeding about ll F. in a primary cracking zonev in the presence of heated particulate contact material maintained in a free fluidized state and in a hydrogen-containing atmosphere, passing said contact material from said primary cracking zone downwardly through a secondary cracking zone in countercurrent contact with a hydrogen-containing atmosphere in a restrained fluidized state whereby the temperature in said secondary cracking zone increases in the downward direction, regenerating said contact material after passage through said secondary cracking Zone by reacting the carbonaceous deposit formed on said contact material during conversion of said oil with steam and oxygen at a temperature of at least 1600 F. thereby forming regeneration product gases containing hydrogen and simultaneously heating said contact material, flowing said regeneration product gases through said secondary and primary cracking zones to provide therein a hydrogen-c-ontaining atmosphere las aforesaid, and returning thus heated contact material to said primary cracking zone.

2. The process of claim 1 wherein the elevated temperature in the primary cracking zone is in the range of about 850 to 1100 F.

3. The process of claim 1 wherein the hydrogen of the hydrogenacontaining atmosphere in said primary and secondary cracking zones exerts a partial pressure in the range of about 75 to 150 p. s. i.

4. The process of claim 1 wherein the steam and oxygen used in regenerating the contact material are supplied in a steam-to-oxygen volume ratio in the range of about 1.5 :1 to 5:1.

5. ln the process for the conversion of hydrocarbons wherein the hydrocarbons contact a uidized mass of solid particles at an elevated conversion temperature not exceeding about 1100 F. and oxygen contacts said solid particles at a regeneration temperature higher than said conversion temperature to consume carbonaceous matter deposited on said solid particles by said hydrocarbons, the improvement of stripping adsorbed hydrocarbons from said solid particles prior to regeneration, which comprises passing said solid particles with adsorbed hydrocarbons downwardly through a iixed bed of coarse packing bodies in countercurrent contact with a hydrogen-containing gaseous stream initially at a temperature of at least 1600 F. thereby progressively increasing the temperature of said solid particles in their downward passage through said xed bed and eifectively stripping I adsorbed hydrocarbons from said solid particles, regenerating thus stripped solid particles by reacting residual carbon on said stripped solid particles at a temperature of at least 1600 F. with steam and oxygen supplied in a steam-to-oxygen volume ratio of at least 1.5:1 whereby the resulting regeneration product gases contain a substantial pr-oportion of hydrogen, carbon monoxide and steam, and flowing said regeneration product gases through said ixed bed as said hydrogen-containing gaseous stream.

6. The process of claim 5 wherein the operating pressure is in the range of to 800 p. s. i. g.

7. The process of converting a hydrocarbon oil to gasoline which comprises converting said oil directly to gasoline at a temperature of about 850 to 1100 F. in a primary cracking zone in the presence of hydrogen and particulate contact material maintained in a free fluidized state, passing said contact material from said primary cracking zone downwardly through a secondary cracking zone in countercurrent contact with a hydrogenecontaining gaseous stream in a restrained fluidized state whereby the temperature at the top of said secondary cracking zoneis close to that of said primary cracking Zone and increases downwardly through said secondary cracking Zone to a temperature at the bottom of said secondary cracking zone close to that of the regeneration Zone, passing said contact material from the bottom of said second ary cracking zone into said regeneration zone to consume carbonaceous matter on said contact material by reaction at a temperature of about 1600 to 2500 F. with steam and oxygen supplied in a steam-to-oxygen volume ratio in the range of 1.5:1 to 5:1 thereby forming regeneration product gases containing a substantial proportion of hydrogen, carbon monoxide and steam, flowing said regeneration product gases through said secondary cracking zone as said hydrogen-containing gaseous stream and into said primary cracking zone to provide said hydrogen therein, and maintaining an elevated operating pressure such that the hydrogen exerts a partial pressure of about 35 to 200 p. s. i. in said primary and secondary cracking zones.

8. The process of converting a heavy hydrocarbon oil to gasoline which comprises converting said oil directly to gasoline at an elevated temperature not exceeding about 1100 F. in a primary cracking zone in the presence of heated particulate contact material maintained in a free iluidized state and in an atmosphere of steam and regeneration product gases, including hydrogen resulting from the regeneration with steam and oxygen, in a regeneration zone maintained at a temperature of at least 1600 F., of the carbonaceous deposit formed on said contact material during conversion of said oil, separating from the resulting conversion products gasoline hydrocarbons and higher-boiling hydrocarbons, returning at least a portion of said higher-boiling hydrocarbons to a :recycle cracking zone containing said contact material in a liuidized state and said atmosphere of steam and regeneration product gases, maintaining said recycle cracking zone at a higher temperature than said elevated temperature in said primary cracking zone, passing said contact material from said primary and recycle cracking zones downwardly through a secondary cracking zone in countercurrent contact with said atmosphere of steam and regeneration product gases in a restrained uidized state whereby the temperature in said secondary cracking zone increases in the downward direction, passing said contact material from said secondary cracking zone into said regeneration zone to effect said regeneration with steam and oxygen of the carbonaceous deposit on said contact material at a temperature of at least 1600 F. thereby forming said atmosphere of steam and regeneration product gases and simultaneously heating said contact material, and returning thus heated contact material from said regeneration zone to said primary and recycle cracking zones.

9. The process of claim 8 wherein the hydrogen of said atmosphere in said primary, recycle and secondary cracking zones exerts a partial pressure in the range of about 35 to200 p. s. i. Y

10. The process :of claim 8 wherein the elevated temperature in the primary cracking zone is in the range of 900 to 1050 F. and the higher temperature in said recycle cracking zone does not exceed 1450 F.

1.1. The process .of claim 10 wherein the operating pressure is in the range of 250 to 650 p. s. i. g.

12. Apparatus for converting a hydrocarbon oil in contact with a fluidized mass of `particulate lcontact material, which comprises an upright elongated vessel, a iixed bed of packing bodies disposed in an intermediate portion of said vessel and supported by a foraminous member extending horizontally across said vessel, the top of s -aid bed communicating -with a hydrocarbon conversion zone in said vessel and the bottom of said bed along with said foraminous member being disposed in open communication for ow therethrough of a gasfrom a 4contact material regeneration zone in said vessel, an inlet for the introduction of regenerating gas into said regeneration zone, means for injecting a hydrocarbon oil into said conversion zone, an outlet for gaseous products at .the top of said vessel, a conduit communicating at its lower end with said regeneration zone and at its upper end with said conversion zone, and means for injecting a transport gas into the lower lend of said conduit 12 to lift contact material from said regeneration zone to said conversion zone.

13. The apparatus of claim 12 wherein a dow-restricting baffle structure extends horizontally across the conversion zone above the means for injecting a hydrocarbon oil, anda second Vmeans is provided for injecting a hy-v drocarbon oil into said vessel above said bae structure.rv

14. The apparatus of claim 13 wherein a second conduit communicates at its llower end with said regenerationv zone and at its upper end-with the portion of said conversion zone above said baie structure, and a second means is provided for injecting a transport gas into theY lower end of said second conduit to lift. Contact r'nateriall from said regeneration zone to the portion of said conversion zone above said bafe structure.

References Citedin lthe le of this patent UNITED STATES PATENTS 2,388,055 Hemminger Oct. 30, 1945 21,459,824 Leer Jan. 25, 1949 2,533,026 Matheson Dec. 5, 1950 2,557,680 VOdell June 19', 1951n 2,585,238 Gerhold Feb. 12, 1952 2,606,862 Keith Aug. v12, 1952 2,655,464 Brown et a1 Oct. 13, 1953 2,655,465 Martin Oct. 13, 1953 2,702,267 Keith ..2 Feb. 15, 1955 2,738,307 Beckberger Mar. 13, 1936

Claims

1. THE PROCESS OF CONVERTING A HEAVY HYDROCARBON OIL TO GASOLINE WHICH COMPRISES CONVERTING SAID OIL DIRECTLY TO GASOLINE AT AN ELEVATED TEMPERATURE NOT EXCEEDING ABOUT 100*F. IN A PRIMARY CRACKING ZONE IN THE PRESENCE OF HEATED PARTICULATE CONTACT MATERIAL MAINTAINED IN A FREE FLUIDIZED STATE AND IN A HYDROGEN-CONTAINING ATMOSPHERE, PASSING SAID CONTACT MATERIAL FROM SAID PRIMARY CRACKING ZONE DOWNWARDLY THROUGH A SECONDARY CRACKING ZONE IN COUNTERCURRENT CONTACT WITH A HYDROGEN-CONTAINING ATMOSPHERE IN A RESTRAINED FLUIDIZED STATE WHEREBY THE TEMPERTURE IN SAID SECONDARY CRACKING ZONE INCREASES IN THE DOWNWARD DIRECTION, REGENERATING SAID CONTACT MATERIAL AFTER PASSAGE THROUGH SAID SECONDARY CRACKING ZONE BY REACTING THE CARBONACEOUS DEPOSIT FORMED ON SAID CONTACT MATERIAL DURING CONVERSION OF SAID OIL WITH STEAM AND OXYGEN AT A TEMPERATURE OF AT LEAST 1600*F. THEREBY FORMING REGENERATION PRODUCT GASES CONTAINING HYDROGEN AND SIMULTANEOUSLY HEATING SAID CONTACT MATERIAL, FLOWING SAID REGENERATION PRODUCT GASES THROUGH SAID SECONDARY AND PRIMARY CRACKING ZONES TO PROVIDE AND RETURNING THUS HEATED CONTACT MATERIAL TO SAID PRIMARY CRACKING ZONE.