US2421651A - Conversion of hydrocarbon oils - Google Patents

Description

Hume 3 E947. 1E. D. REEVES CONVERSIONv OF HYDROCARBON OILS 4 Sheets-Sheet l Original Filed Feb. 16, 1939 Wm www W MW mw lu o lnx@ U was Rhume@ June 3, i947, E. D. REEVES CONVERSION OF HYDROCARBON OILS Original Filed Feb. 16, 1.939 4 Sheets-Sheet 2 June 3, 194% E. D. REEVES 2,421,651

CONVERSION OF HYDROCARBON OILS Original Filed Feb. 16, 1939 4 Sheets-Sheet 3 ICMA/V653 A June 39 3947. E D, REEVES 2,421,651

CONVERSION OF HYDROCARBON OILS Original Filed Feb. 16, 1939 4 Sheets-Sheet 4 35 CNVE VOR `Patented June 3, 1947.

CONVERSION F HYDROCARBON OILS n Edward D. Reeves, Cranford, N. J., assigner to Standard Oil Development Company, a corporation of Delaware Original Aapplication February 16, 1939, Serial No. 256,630. Divided and this application October 14, 1942, Serial No. 461,916

3 Claims. (Cl. 196-52) This invention is directed to the conversion of hydrocarbon oils and pertains more particularly to a process of treating crude petroleum oil to produce as a primary product motor fuel having a high octane rating.

The present invention forms a division of apl plication Serial No. 256,630, filed February 16, 1939.

The invention in its entirety comprehends the processing of crude petroleum oils in which the crude oil is initially segregated into separate fractions and the separate fractions so segregated thenseparately treated under selective conditions for the conversion of such fractions into motor fuel products of high anti-knock value. The invention is concerned primarily with the treatment of said selective fractions in the presence of a pulverized contact material which in the cases of the lighter fraction, such as naphtha or gas oils, preferably has catalytic action whereas the pulverized material employed in the treatment of the heavier residual stocks may or may not have catalytic activity.

It has heretofore been proposed to crack hydrocarbon oil in the presence of a solid contact mass having catalytic activity, such as, for example, naturally active or activated clays and certain synthetic compounds of similar adsorbent nature.

According to one of the better known methods of carryingout the catalytic process, the oil in vapor form preheated to the desired cracking temperature is passedv through a reaction zone containing a solid mass of contact material. 'Ihe rate of flow of the oil vapors is controlled to obtain the desired conversion into lower boiling distillate products and the reaction products are then passed into a conventional fractionating equipment for the separation of desired motor fuel products from the unconverted o il.

During the cracking operation, thecatalytic material gradually becomes fouled with carbonaceous deposits which reduces the activity of the catalyst until eventually a point is reached where it becomes necessary to regenerate the Y catalyst to restore its activity. When operating according to the method above described, the cracking operationis continued for a predetermined period until the activity of the catalyst is dropped to a point where it becomes no longer capable of effecting the-desired conversion. The cracking cycle is then interrupted, the catalyst purged of residual oil and carbonaceous deposits are burned from the catalyst by passing an oxidizing gas through the catalyst. After completing'the regeneration of the catalyst, the mass is then purged of regenerating gases and subjected to another cracking cycle. When operating in this manner, it has also been proposed Lto mold the catalyst into small cylinders, discs, pills or other shapes of uniform size to insure more uniform distribution of the loil vapors through the mass and reduce the resistance of the contact mass to the flow of gases and vapors therethrough.

This method of operating has a number' of obijections. First, because of the necessity oi' frequently interrupting the cracking cycle to effect regeneration of the catalyst, it is necessary to provide a number of reaction chambers in order to operate the process continuously, so that one chamber may be undergoing the cracking cycle while others are undergoing regeneration. The original investment, therefore, necessary for providing an apparatus capable of operating atcommercial capacities becomes relatively large. Secondly, since the conditions for carrying out the cracking cycle and for carrying out regeneration are widely different, a. design capable of most effectively carrying out/the cracking cycle is not particularly adapted for effecting rapid regeneration of the catalyst mass. On the other hand, if the reaction chamber is designed so as to obtain rapid regeneration of the catalyst mass, it may not be particularly suitable for carrying out the catalytic cracking operation.

The present invention has for one of its broader objects the provision of" an improved method of treating hydrocarbon oils in the presence of a pulverized contact mass.

A further object of the invention is to provide a complete and unitary process for treating crude petroleum stocks for the production of motor fuels therefrom.

A further important object of the invention is to provide a method of treating certain selective fractions of crude petroleum products.

With the above objects inview, the invention will be better understood by reference to the accompanying drawing, wherein Fig. 1 is a dagrammatic illustration of an apparatus adapted for processing crude petroleum stock; Fig. 1A is a continuation of Fig. 1 on lines IA-IA; Fig. 2 is a diagrammatic illustration of an apparatus suitable for regenerating the catalytic mass employed in the treatment of such oils, and Fig. 3

is a sectional view of an apparatus adapted for preconditioning the powdered catalytic material for injection into the oil stream.

Referring to Fig. l, the oil to be processed,

,coil 29Y passes through'transfer line which is preferably a crude petroleum product, is introduced into the apparatus through charge line I0, provided with pump Il which forces the oil through a preheating coil I2 located in furnace I3. I'he oil during its passage through the heating coil I2 is preferably heated to incipient cracking temperature sufficient to vaporize all constituents vaporizable without decomposition. The outlet temperature of the oil after passing through the heating coil I2 and preheated to vaporize the major constituents thereof is transferred through transfer line I4 to a crude dis' tilling and fractionating tower I5. The crude fractionating tower I5 is provided with suitable fractionating elements, such as discs and doughnuts, baflies, bubble trays, Raschig rings or the like for fractionating vapors liberated in the bottom section of the tower.

The tower I5 is preferably provided with a trapout tray I6 for collecting condensate formed in the intermediate section of the tower I5.. This condensate is preferably a gas oil fraction having an initial boiling point between 400 and 500 F. and a final boiling point between 650 and '750 F. Products collected in the bottom section of the tower I5 comprising unvaporized residue and vapors condensed below the trap-out tray I6 are withdrawn from the tower I5 through line I7 and treated as hereinafter described. Condensate collected on trap-out tray I6 is Withdrawn through line f8' and further processed as later described.

Vapors remaining uncondensed in the fractionating tower I5 and which may or may not contain all or part of the gasoline constituents liberated from the crude petroleum pass overhead through line I9 to a condenser 20 wherein the light normally liquid constituents are condensed. Products from the condenser 20 pass to a receiver 2I wherein the liquids condensed in the condenser20 separate from the uncondensed constituents. Uncondensed normally gaseous constituents liberated in the fractionating tower I5 are removed from the receiver 2| through line 22. Liquid distillatel collected in the receiver 2l is withdrawn therefrom through line '23 and may be removed from the system through line 24, or it may be passed through lines 25 and 26 and subjected to catalytic treatment as later described. If desired, a. portion of such distil-' late may be lreturned to the top of the fractionator I5 as reflux therefor.

According to one phase of the invention, the fractionating tower I5 'is provided with a second trap-out tray 21 having a draw-ofi line 28, and the top temperature thereof is controlled to condense a naphtha fraction for further treatment to improve the octanev number thereof. This naphtha fraction may comprise the total gasoline fraction of the crude charge, but preferably comprises a heavy naphtha fraction having an initial boiling point between' 200-250 F. and a final boiling point between 400-500 F. The straight run I heavy naphtha fraction collected von the trapout tray 21 is withdrawn through linef28 and passed the catalyst feeding mechanism due to formation of coke therein and to obtain more intimate dispersion of catalyst and oil vapors, it is desirable to first inject into vthe powdered catalyst a heat stable gaseous stream, such as steam, nitrogen. hydrogen or low molecular weight hydrocarbon gases, for example, methane -and ethane, before contacting the catalyst with the oil vapors. The gas so introduced into the catalyst forms a gaseous shield between the feeding mechanism and the oil vapors and thus prevents the oil vapors from contacting the feeding mechanism. Fig. 3 is a cross section of an apparatus combining the powdered catalytic material with the oil vapors.

Referring to Fig. 3, the numeral 33 designates a hopper containing the powdered catalyst 34. The bottom of the hopper 33 is provided with a screw conveyor 35 which feeds the catalyst from the hopper 33 through conduit 36 into a chest or chamber 31. The conveyor 35 is preferably provided with a compression screw having the spaces between the flights of progressively decreasing size toward the outlet. Extending through the wall of chamber 31 and preferably opposite the end of the screw conveyor 35 is a nozzle 38 through which is introduced an inert gas, such as steam, nitrogen, hydrogen, light hydrocarbon gases or the like. This stream of inert gases impinges upon the product issuing from the conveyor 35 and breaks up lumps which may be formed by passing through the conveyor 35. A heavy dense dispersion of powdered material and inert gas forms within the chamber 31 and is passed through a nozzle 39 and conduit 40 to the injection chamber 32.

The oil vapors introduced into the injection chamber 32 are intimately dispersed within the powdered material and the suspension or dispersion of oil vapors, inert gas and powdered material is passed from the injection chamber 32 through une 4|, (see Fig. 1).

The apparatus above described and the method of accomplishing the dispersion of catalyst in the oil stream forms the subject matter of a separate application Serial No. 284,892, filed July 17, 1939, now issued to Patent No. 2,296,309.

Returning now to Fig. 1 the pulverized catalyst introduced into the injector 32 may be any suitable reforming catalyst such as active or activated clays, mixed oxides of silica and alumina, bauxite or themixed oxides of the third and sixth groups of the periodic system. A particularly desirable catalyst is a co-precipitated mixture of chromium oxide and aluminum oxide. The catalyst employed is preferably a finely-divided pulverized material having a particle size ranging, for example, between 200 and 400 standard mesh.

'I'he oil vapors and inert gases with the powdered catalyst dispersed therein passes from the injection chamber 32 through a line 4I to a reaction zone 42. For illustrative purposes, I have shown the reaction zone 42 in the form of a heating coil disposed within the furnace`setting 43. The reaction zone may, however, be of any to a heating coil 29: located in furnace 30. The oil during its passagel through the heating coil 29 is vaporiz'ed and preferablyheated to the desired reforming temperature'gsuch as from 70D-10009 F. to improve the octane"v number thereofgggflhe naphtha, .after passing. through the., .fpr'ehea'tingf jector 32 wherein-it is injected into powderedv catalyst.

'lof

faiheated orunheated reaction chamber provided desired construction providing an elongated restricted passageway. so that the velocity of the vapors-passing through the reaction zone is sufficient to. maintain the powdered catalyst in suspension therein.: For-example, in lieu of a heated coilsuch asshown, an unheated tubular coil or with.,suitable'baiilesvto-maintain the gases at sufl' 'cientvelocityfto holdthe catalyst in suspension ymay be'exjnployed Thej-.relativef`proportion of catalyst and oil the nature of the naphtha to be treated, the

amount of octane improvement desired and other factors, so thatlt is impossible to specify specific condition of operation which will be suitable for all cases. For obtaining an anti-knock improvement of from -15 octane number` on the virgin heavy naphtha having a boiling rangeof from :Z50-500 F. from an East Texas crude oil, the relative proportion of catalyst and oil vapors may be of the order of .5 to 3 lbs. of catalyst per pound of naphtha treated, the temperature between 900-1000 F., and the time of contact may be from to 80 seconds. This process is preferably operated at substantially atmospheric pressure, but sub-atmospheric or mild super-atmospheric pressure, such as from 2 to 20 atmospheres may be employed.

The products from the reaction zone 42, after having undergone the desired reforming treatment therein, are transferred through line 44 to a suitable separator for removal of solid from gases, such as a cyclone separator 45 (see Fig. 1-A) for separation of the powdered catalyst therefrom. The powdered catalyst separated in the separator 45 passes downwardly through a baille tower 46 preferably located directly below the separator, countercurrent to a stream of inert gas such as steam, introduced in the bottom section of the tower. The inert gas stream serves to strip the lseparated catalyst of residual oil constituents remaining on the catalyst. 'Ihe separated catalyst after passing through the bafile tower 46 is collected in a catalyst vreceiver 41 from whence it is passed Lthrough a suitable pressure sealed conveyor, such as a star conveyor 48 to a regenerating circuit later described.

The oil vapors and gases after having been freed of at least the bulk of the catalyst material in the cyclone separator 45 are removed therefrom through line 43 and may be passed to conventional fractionating equipment for the fractionation of the oil vapors therein. However, ac- .cording to a more specific phase of the invention and particularly when steam is employed as an inert gas for dispersing the catalyst into the oil vapor and for stripping the separated catalyst of residual oil vapors, it is preferred to first separate the steam from the oils before fractionation.v

To this end, the gases removed from the separator 45 through line denser 5I wherein normally liquid products including steam are condensed. Products from the condenser 5l then pass to a gas separator 52 wherein normally gaseous constituents separate from the liquid. 'I'he normally gaseous constituents pass from the separator 52 through line 53 and may be sent to a suitable adsorption system for the recovery of gasoline constituents therefrom. v

Liquid separated in the separator drawn therefrom through line 54 a water separator 55 wherein the phases are allowed to stratify.. The water is removed from the water separator 55 through line 56 and the oil is passed through line 51 to a combined distilling and fractionating tower 58 for distilling and fractionating the products so separated. If desired, a heat exchanger 59 may be placedin the line 51 leading from the water separator 55 to the distilling and fractionating tower 58 to preheat the oil prior to introduction into the fractionating tower.

Any powdered catalyst not separated in the 52 is withand passed to water and oilV 49 are passed to a conseparator 45 will'accumulate in the water phase `of the water separator 55 and be withdrawn through line 56. It is preferred to effect substantially complete removal of the powdered catalyst while the oil products are in vapor form,

so that the water withdrawn through line 56 willbe substantially'free of catalyst and can be discarded. If one cyclone separator is not sufficient to effect substantially complete removal of the powdered catalyst from the oil vapors, additional separators may be inter-connected in ,series with the separator 45. Y

It is Within the purview of my invention, however, to remove only the bulk of the catalyst material in the cyclone separator 45 in relatively dry form and to separate the remainder of the powdered catalyst in the form of a water catalyst slurry in the water separator 55. In the latter case, the water removed through line 516 containing powdered catalyst may be sent to a filtering device (not shown) of any suitable construction for separation of the powdered catalyst therefrom. The residue from the filtering operation may be then dried and subjected to regeneration and returned to the process.

'I'he distillate introduced into the distilling and fractionating tower 58 is subjected to distillation' and fractionation therein to separate a` desired motor fuel distillate from remaining higher and lower boiling constituents. Higher boiling distillate undesired in the final motor fuel product may be collected in the bottom of the fractionating tower 5B and may be withdrawn therefrom through line 60 and subjected to further treatment as hereinafter described. The motor fuel constituents in vapor form are removed from the fractionating tower 58 through line 6l vto a condenser 62 wherein the motor fuel distillate is condensed. The products from the condenser 62 pass to a distillate receiver 63` wherein the distillate separates from any gases liberated during the distillation thereof. The liquid distillate collected in the receiver 63 is withdrawn through line 64' and ,may be subjected to any further finishing treatment desired. Gases separated in the receiver 63 are removed overhead through line 65 and may be sent to a suitable adsorption system for recovery of gasoline constituents therefrom. l

According to one phase of the invention, a part or all of the gases separated in the receiver 63 is recycled to the reaction zone through lines 66. 61, blower 68, and lines 69 and 'l0 (see Fig. 1), to the inlet side of the reaction coil. These gases will normally containa relatively high percentage of. hydrogen, which will serve to reduce the amount of coke formed on the-catalyst, during the process and other constituents which may be polymerized or reacted with the oil to improve the gasoline yield. When operating in this manner, it is preferred to also recyclethe gases removed from the initial gas separator 52 through line 53. These gases may be passed through lines' 53 and 1I to recycle line GBand there combined with recycle gases from receiver 63, or, if desired, gases from separator 52 may be introduced into the fractionating tower 58 through line 12 to assist the distillation and fractionation therein. If desired, additional hydrogen may be added to the recycle gas through line 61'.

In lieu of carrying out reforming of heavy naphtha or total naphtha fraction within the rectly through lines I9, I9 and 26 to the inlet side of the heating coil 29 or the light naphtha fraction collected in receiver 2l may be passed through lines 23, 25 and 26 to the inlet side of the heating coil 29.

When processing this type of stock the temperature, time of contact and nature of the catalyst employed, will be regulated to accomplish condensation or polymerization fof low molecular weight hydrocarbons into higher boiling products. Any suitable polymerizing or condensing catalysts, such as activated clays, aluminum chloride or complex salts of aluminum chloride, for example, sodium aluminum chloride, maybe .employed alone or supported on a suitable carrier. The temperatures for carrying out this type of reaction may be the same or somewhat lower than that employed for reforming, such as from 400-1000 F. f

Returning to the crude fractionating tower I5 (see Fig. 1) the gas oil fraction collected in the trap-out tray I6 and removed through line I8 is forced by means of pump 1-5 through a preheating and vaporizing coil 16 located in furnace 11. The oil during its passage through the heating coil 16 is vaporized and preferably heated to the desired reaction temperature for carrying out catalytic cracking treatment. This temperature, may, for example, be of the order of from '15G-900 F.

The oil after passingthrough the heating coil 16 is passed through line 18 r-to a separator 19 wherein any unvaporized constituents entrained in the oil passing through the preheating coil are separated. Liquids separated in the separator 19 are withdrawn through line 80 and may be 'rejected from the systemand may be treated as hereinafter described. Vapors from the separator 19 pass overhead through line 8I to an in,

jector 82 wherein they are dispersed in a suspension of powdered cataylst and inert gas. The

method of and apparatus for injecting the pow-A dered .catalyst into the gas -oil vapor lstream 'are For example, when cracking a virgin East Texas gas oil having an A. P. I. gravity of from to 40 vemploying activated clay known as Superltrol, the relative proportions of catalyst and oil vapors are preferably between the range of .5 parts to 3 parts of catalyst per part of oil byv weight and particularly between one and two parts of catalyst per part of oil. 'I'he temperature may range between 800 and 1000, preferably between 875 and 925 F. The pressure employed may be atmospheric or a mild super-atmospheric pressure, such as from 2 to 20 atmospheres. The time of contact of the oil vapors within the reaction zone in such case is preferably from 10 to 90 seconds. The velocity of the oil vapors catalyst suspension passing through the reaction zone should be sufficient to maintain the powdered catalyst dispersed within the vapors.

The oil vapors and catalyst after being maintained within the reaction coil 85 for a period suicient to obtain the desired conversion thereof, is passed through transfr line 81 to a separator 88 (see Fig. l-A) wherein the powdered material is separated from the cracked products. This separator may be the conventional cyclone separator, such as previously described, or any other type of separator capable of removing the same as that employed for injecting powdered 4 y catalyst into the naphtha stream hereinbefore described. For more complete details, therefore,

reference is made'to the preceding description.

In case the gas oil charged to the preheating coil 16 is relatively fre'e of unvaporizable constituents, the separator 19 may be omitted or thel oil vapormay be by-passed around the separator through line 83.

The dispersionof oil vapors and catalyst from vvthe injection chamber 82 passes through line |84 to a reaction coil V85 located in the furnace 88.

They catalyst employed for the cracking of the gas oil may be any suitable cracking catalyst,v

such as, for example, active or' activatedV clays -or synthetic gels consisting principally of silica and alumina. The catalyst is preferably in finely pulverized condition, having a particle size, for example, ranging between 200-400 standard mesh. The relative proportions of catalyst and oil vapors employed, the temperature, velocity and time of contact may vary over a substantial range depending upon the nature 0f the gas oil cracked, the amount of conversion desired and other factors.

solids from gases. The catalyst separated in the cyclone separator 88 is charged into the top Aof a vertical baille tower 89 and passes downwardly therethrough in countercurrent contact with an inert gaseous medium, such as steam introduced at 90. The inert gaseous medium tends to strip the separated catalyst of residual oil vapors remaining absorbed thereon. The stripped catalyst from the vertical tower 89 discharges into a catalyst receiver 9I. Separated catalyst collected in the receiver 9| is removed therefrom by means of suitable pressure type feeding mechanism, such as a rotary star conveyor 92 and is passed to suitable regeneratingA equipment hereinafter described.

Gases separated in the'cyclone separator 88 comprisingthe cracked oil products together with inert constituents introduced as a dispersing medium for the catalyst and for purging the separated catalyst in the tower 89 pass from the cyclone separator through line 93 and may be passed directly to suitable fractionating equipment for the separation of the desired motor fuel products therefrom. It is preferable, however, when steam is used as a diluent, to first cool the product so 'as to condense the steam before subjecting the product to fractionation. To this end, as shown on the drawing, the products from the line 93 pass to a condenser 94 whereinA the products are cooled to a temperature below the boiling point of water so as to condense steam contained therein. Products from the condenser 94 pass to a gas separator 95 wherein normally gaseous constituents formed in the process are separated froml the-liquid condensed in the condenser 94. Gases separated in the gas separator 95 are passed overhead through line96 having a valve for imposing the desired back pressure on the system. These gases may be passed to a suitable absorption equipment for the recovery of gasoline constituentstherefrom or may be recycled directly to the cracking zone as later described.

Liquid collected in the gas separator 95 comprising the oil products together with condensed is withdrawn through line 99'and the oil fraction passed through line and pump |02 to a fractionating column |03 wherein the oil products are subjected to a combined distilling and fractionating process. If desired, the oil prior to being introduced into the fractionating column |03 may be preheated by passing through a suitable heat exchanger |04.

' The temperature of the combined distilling and fractionating tower |03 may be controlled to vaporize and fractionate only the lower boiling motor fuel distillate without vaporizing any substantial amount of the higher boiling Icondensate fraction, or the temperature may be such as to vaporize the total oil fraction so as to permit segregation of such fraction into a plurality of individual cuts for further treating as hereinafter described. The total higher boiling fraction boiling above the desired motor fuel products may be withdrawn from the fractionating tower |03 through line |00 and a portion thereof passed through lines |07, |08 and heat exchanger |09 back to the bottom of the tower to supply the necessary heat for effecting the distillation. Liquid collected in the bottom of the tower |03 and not recycled through a suitable heat exchanger may be withdrawn from the system through line or passed through lines 2 or ||3 (see Fig. l) for further processing as later described.

As before mentioned, the liquid products collected in the bottom of the fractionating tower |03 may comprise the total higher boiling constituents of the oil boiling above the motor fuel products. However. in some cases, it may be desirable to separate the heavy condensate into separate fractions. To this end, the fractionating tower |03 may be provided with trap-out trays for separately collecting individual fractions of such condensate. For example, a trap-out tray H0 may be provided adjacent the bottom of the tower so that the liquid collected in the bottom of the tower comprises, for example, from 5-10% of the total condensate formed in the tower. The product collected in the trap-out tray H0, comprising, for example, a heavy gas oil fraction boiling between the ranges of 550 to 750 F. may be withdrawn from the trap-out tray lili through line H0 and subjected to further processing as later described.

,Alsd the tower |03 may be provided with a second trap-out tray lill positioned in the upper' `section of the tower for separately collecting a light gas oil fraction which may be withdrawn from a trap-out tray through line i l0 and rejected from the system or subjected to further treatment as later described.

Vapors remaining uncondensed or separately vaporized in the fractionating tower |03 pass overhead therefrom through line il@ into a condenser |20 wherein the desired motor fuel products are condensed. Products from the condenser |20 may pass to a receiver l2| wherein any normally gaseous constituents liberated during the distillation and fractionated within the fraction- 65 ating tower |03 may be separately removed through line |22 having a valve for imposing the desired back pressure on the fractionating tower. These gases may be passed to a suitable absorption system for the recovery of gasoline constitu- 70 ents therefrom. Motor fuel distillate collected in receiver |2| may be withdrawn through line |23 and subjected to any further finishing desired for the production of the final marketable product.

'I-'his product may be blended with the reformed 75 The pulverized material introduced into the product collected in receiver 63 and if desired, a portion thereof may be returned to the top of the fractionating tower |03 as reflux therefor. Gases separated in receiver |2| and withdrawn through line |22 may be rejected from the system through line |24 or may be passed through line |25 to recycle line 66 and returned to the process. Ii desired, a portion of the recycle gas may be passed through lines 66, 61, blower 63, lines 69, |26 and |21 to the inlet side of the reaction coil 85,.

As previously described in connection with the reforming process, it is preferred to substantially completely remove all of the powdered catalyst within the separator BB prior'to passing the vapors to the condenser 94. If the single cyclone,

separator 88 is ineffective to completely remove 'the powdered catalyst from the oil vapors, additional separators may be interconnected in the vapor line 93 for effecting further removal..

The invention further contemplates, however, the removal of the bulk of the catalyst powdered material by means of the separator` 88 While the reaction products are in vapor form and then removing the remainder by filtering the water phase separated in the water separator 98. The water withdrawn through line 99, for example, may be passed to a suitable filter for the separation of any powdered catalyst contained therein and the filtered residue dried and subjected to regeneration before returning to the operation.

Returning again to the crude fractionating tower l5 (see Fig. 1) the bottoms withdrawn therefrom through line are forced by means of pump |30 to a viscosity breaking unit wherein these products are converted into vapors and coke. Bottoms from the tower l5 are forced by means of pump i3@ through line |3| to a pre' heating coil |32 located in furnace |33. The oil during its passage through the heating coil |32 is preferably heated to the maximum temperature permissible without involving coking difficulties. If desired, steam may be introduced through line |30 to assist in vaporization and further treatment of the oil as later described.

In lieu of steam, residual gases formed in the processes and separated in receivers 03 and l2! may be passed through lines 6l and |26 and introduced into the heavy oil stream at the inlet side of the heating coil |32. A portion oi' such residual gases may also be passed through line |26' and introduced into either or both of the heating coils 29 and l0. As previously mentioned, a part or all of the residual gases may be injected directly into the dry catalyst before contacting the same with the oil vapors. The outlet temperature of the oil from theheating coli |32 may, for example, be of the order of from G-900 IE'. v

Products from the heating coil |32 pass through line |35 to an injection chamber |36 wherein they are injected into a stream oi? powdered material suspended in a stream of inert gas. If desired, a portion or al1 of the oil from the bottom of the chamber I5 may be by-passed around the furnace |32 through line |31 and passed directly into the injection chamber |36. The method of and apparatus employed is the same as that described for suspending the catalyst into the stream of naphtha vapors for carrying out the reforming operation earlierI described. The suspension or dispersion of oil and powdered material formed in the injection chamber |36 passes through line |38 to a reaction coil |39 preferably located in the furnace |40.

,il y

oil in injection chamber |36 may be an active cracking catalyst but is preferably a relatively inactive cracking catalyst or an inert material such as pumice, kieselguhr, spent clay or any other type of solid adsorbent material. In this case, the powdered material is intended to serve primarily as a carrier for the coke formed during the viscosity-breaking operation.

The relative proportions of powdered material and oil, the temperature and length of treatment within the reaction coil |36 in this case are regulated to convert the oil into vapors and coke within the reaction zone.

\ The primary objective of the reaction within coil |30 is to reduce the viscosity of the heavy oil and convert it into a gas oilsuitable for catalytic cracking along with the virgin gas oil from the crude fractionator rather than to convert` said heavy oil directly into gasoline. The conditions within the reaction coil are controlled to attain this objective. It will be understood, of course, that minor amounts of gasoline are normally formed in carrying out the viscositybreaking treatment but this is incidental.

The products from the reaction coil |36 pass through line 4| to a cyclone separator |42 or other suitable apparatus for separating the powdered material from the cracked products. Powdered material separated in the separator |42 is passed to a vertical tower |43 containing suitable bailies for effecting intimate contact between the vseparated material and an inert gaseous stream pass/ing countercurrently therethrough. The inert gaseous stream may be steam introduced through line |44. The powdered material after being stripped of volatile residual oil during its passage through the tower |43 is charged into a catalyst receiver |45 having a conveyor |46 for transferring the material to the suitable regenerating unit later described.

Cracked or viscosity-broken products separated' in the separator 42 are withdrawn through line |41. Products from the line |41 are preferably passed through lines |41 and |48 and combine-d with the virgin gas oil from the crude fractionator I on the inlet side of the preheating coil 16 or through lines |41 and |49 to the outlet side of the coil 16, and cracked with the virgin gas oil as previously described. It may be desirable in Some cases to subject the products from the separator |42 to fractionation to segregate a gas oil fraction therefrom. To this end, the products from line |41 may be passed through line |50 and combined with overhead products from separator 88 for further fractionation therewith.

As a second alternative, the overhead from the separator |42 may be subjected to separate condensation to remove the lnal traces of powdered material therefrom before combining the oil products with the virgin gas oil. To this end, the products from the separator 42 may be passed through lines |41, |50, |5| to a separate condenser |52 wherein normally liquid products are condensed.

Products from the condenser |52 pass to a gas separator |53 wherein any normally gaseous products formed in the viscosity-breaking processare separated. The gases so separated are removed from the separator |53 through line |54 having a valve which may be operatedto impose the desired back pressure on the process.

f Liquid collected in the gas separator |54 passes through line |55 to a water separator |56 wherein the water and oil phases are allowed to stratify.

The water may be withdrawn through line |51b.

The oil phase is withdrawn from the water separator |56 through line |58 which merges with line |48 leading to the inlet side of the preheating coil 16 where it is combined with the virgin gas oil withdrawn from the trap-out tray I6 of the crude fractionating tower |5.

'The separate condensation of the products from the separator |42 is of particular advantage in cases where a final portion of the powdered material is separated out in the form of a slurry in the water separator |52. As previously described, the invention contemplates two methods of separating the powdered material from the cracked products. In the one case, the total powdered material is separated in a relatively dry state from the oil vapors prior to condensation. the second case, the bulk of the powdered material is .separated out in the dry state and the nal portion is separated by a wet method, or, in other words, by the condensation of the cracked products and the steam to form a Water slurry which may be later filtered and regenerated.

In case a trap-out tray ||4 is provided in the tar separator 13 may be passed to the inlet side.

of the preheating furnace |32 processing crude residual stock by merging line with line ||2 as shown. VCycle stock collected in trap-out tray ||4 and withdrawn therefrom through line |I6 or the total cycle from the bottom of the fractionating tower |03 may be recycled through line IIB to the inlet side of the heating coil 16 and combined with crude gas oil from the crude fractionator |5. Bottoms from the fractionating tower 58 may also be recycled by merging line 60 with line ||6.

A part or all of the light cycle'stock collected in trap-out tray I1 and withdrawn through line |I8 may be passed through line I21a to line ||2 and employed for reducing the viscosity of the oil passing through the preheating coil |32 and to assist in vaporizing the oil.

The catalyst or powdered material separated from the reaction products in the three operations above described is preferably regenerated to remove carbonaceous deposits contained thereon as a result of the treatment and returned to the catalyst hoppers for further use. Figure 2 illustrates an apparatus suitable for effecting the regeneration of the powdered material. Referring to Fig. 2, the numeral |60 designates a receiver for catalysts separated from the reaction products and corresponds to receivers 41, 9| and |45 of Fig. 1 A. The catalyst collected in the receiver |60 is transferred by means of suitable conveyor mechanism capable of maintaining a pressure seal, such as, for example, a star conveyor. |6I, and is injected into a stream of hot regenerating gases passing through line |62. The regenerating gases are heated to a temperature sufilcientto ignite the carbonaceous deposits contained on the catalyst. The regenerating gas containing the powdered catalyst passes from line |62 through a regenerating zone |63. This regenerating zone may be in the form of a tubular coil located within a waste heat boiler |64 for the recovery of heat liberated during the regenerating process. Air or other oxidizing gas capable of supporting combustion within the regenerating zone is introduced through line |65 and is forced by means of blower |66 to any one or more of a number of different points in the regenerating circuit. For example, a part or all of the air necessary to regenerate the catalyst may be introduced into the regenerating stream before introduction of the' powdered material therein, or it may be introduced at spaced points in the regenerating zone.

After completion of the regeneration in the regenerating zone, the regenerated products pass through line |61 to a separator |68 for the separation of the regenerated powder from the regenerating gases. The powder separated in the separator |68 is charged downwardly through a vertical tower |69 containing suitable bailies for effecting intimate contact between the regenerated catalyst and the inert gaseous medium passing upwardly through the tower counter-current to said powdered material. This inert medium is introduced into the bottom section of the tower and serves to strip the regenerated catalyst of regenerating gases adsorbed thereon. 'I'he regenerated powdered material, after being stripped of residual regenerating gases in the tower |69, is passed into a catalyst receiver 'Ill from whence it is transferred by suitable conveyor mechanism into the various catalyst hoppers in the reforming, cracking and viscosity-breaking circuit. In order to make unnecessary mechanical means for transfer of the regenerated catalyst into the hopper, the separators |68 and stripping tower |69 may be super-imposed upon each of the catalyst hoppers shown in Fig. 1. When the same type of catalyst is employed in the reforming, cracking and viscosity-breaking operation, one regenerating circuit may be employed for regenerating all of the catalysts from the three operations. When different catalysts are employed for the three operations, a separate regenerating unit for each circuit should be provided.

The regenerating gases separated in the separator itt of the regenerating circuit (see Fig. 2) are removed from the separators through line |12 and may be rejected from the system through line $73. It is preferred, however, to recycle a portion of the gases so separated to the regenerating zone as a diluent for the air employed for burning the carbonaceous deposits. For example, a part of the gases separated in the separator |58 may be passed through lines |72, l'l, heat exchanger il, linesilS, il? and blower |18 to the line it?. In event it is desired to use a diluent other than spent regenerating gases for controlling the regenerating temperature within the regenerating zone, said diluent may be combined with the air and introduced through line |65 or it may be introduced through line |19.

In many cases, temperatures during regeneration must be carefully controlled to avoid diminishing the absorptive or catalytic properties of the powdered or pulverized material. The apparatus illustrated in Fig. 2 permits careful regulation of the temperature obtained during regeneration. By locating the regenerating zone within a heat exchanger or waste heat boiler, by introducing the air at spaced points within the regenerating zone and by diluting the air with inert diluent, such as recycled regenerating gases, a careful regulation of the temperature within the regenerating zone can be obtained. During regeneration it may be desirable to maintain the stream of regenerating gas and powdered material suspended therein under a substantial superatmospheric pressure, such as from 2-20 atmospheres. By the use of pressure, a lower ignition temperature ofthe powdered material can `be employed and the capacity of the regeneration zone increased.

Having thus described the invention, it will be understood that it embraces such other variations and modifications that come within the spirit and scope thereof.

What is desired to be protected by Letters Patent is:

1. A process for the conversion oi' heavy residual `oils to convert the same into lower boiling hydrocarbons which comprises intermixing with said heavy residual oil a solid absorbent contact material, passing the resulting mixture through a conversion zone maintained at a temperature suiilcient to convert a portion of said oil into lower boiling hydrocarbons, maintaining said oil within said zone for a period suiiicient to convert a substantial portion thereof into lower boiling hydrocarbons, thereafter removing conversion products from said conversion zone, fractionating the conversion products to segregate a light condensate fraction boiling above the motor fuel boiling range, an intermediate condensate fraction and a heavy condensate fraction, combining at least a portion of said light condensate fraction with said heavy condensate fraction, returning said mixture to said conversion zone, and subjecting said intermediate condensate fraction to separate cracking treatment in the presence of a finely divided cracking catalyst.

2. A process for the conversion oi? hydrocarbon oils to form lower boiling hydrocarbons suitable for motor fuel which comprises intermixing a heavy residual oil with a finely-divided solid absorbent contact material, passing the resulting mixture to a conversion zone maintained] at a temperature sufficient to convert a substantial portion of said heavy residual oil into lower boiling hydrocarbons, keeping said residual oil within said conversion zone for a period suiiicient to effect a substantial conversion thereof into lower boiling hydrocarbons, thereafter removingl conversion products from said conversion zone, separating said absorptive material from said conversion products so'removed, lcombining at least a portion of the conversion products removed from said conversion zone with a condensate oil boiling above the desired motor fuel boiling range, intermixing a finely-divided cracking catalyst with said mixture of conversion products and condensate oil, passing the resulting mixture through a cracking zone maintained at active cracking temperature, keeping said oil within said cracking zone forV a period suicient to convert a substantial portion thereof into motor fuel constituents, thereafter removing the cracked products from the cracking zone, fractionating the cracked products to segregate a motor ,fuel fraction therefrom, and a light condensate fraction boiling above the desired motor fuel boiling range and returning said light condensate fraction to said first-named conversion zone.

3. A process for the conversion of hydrocarbon oils to form lower boiling hydrocarbons, suitable for motor fuel which comprises intermixing a heavy residual oil with a finely-divided solid absorbent contact material, passing the resulting mixture to a conversion zone maintained at a temperature suicient to convert a substantial portion of said heavy residual oil into lower boiling hydrocarbons, keeping said residual oil within said conversion zone for a period sufcient to eiect a substantial conversion thereof into lower boiling hydrocarbons, thereafter removing conversion products from said conversion zone, separating said absorptive material from said conversion products so removed, combining at least a, portion of the conversion products removed from said conversion zone rwith a condensate oil boiling above the desired motor fuel boiling range, intermixing a nely-divided cracking catalyst with said mixture of conversion products and condensate oil, passing the resulting mixture through a cracking zone maintained at active cracking temperature, keeping said oil within said cracking zone for a period suicient to convert a substantial portion thereof into motor fuel constituents, thereafter removing the cracked products from the cracking zone, fractionatin'g the cracked products to segregate a motor fuel fraction therefrom, and a. light condensate fraction boiling above the desired motor fuel boiling range, an intermediate condensate fraction and a heavy condensate 16 fraction, combining saidlight condensate fraction with said heavy condensate fraction, and passing the resulting mixture to said rst-named conversion zone.

EDWARD D. REEVES.

REFERENCES CITED The following references are of record in the le of this patent:

Watson Jan. 19, 1943

Images