US2460219A - High-temperature hydrocarbon conversion process - Google Patents

Description

Jan.`25, '1949. s. c. EAsTwooD 2,460,219

HIGH TEMPERATURE HYDROCARBON CONVERSION PROCESS I riledFeb. 28, 194s FLUE HS OUTLET MHIWFQLD 60N VR TUE )lle/rr mr/msg f-Zwa naar EN TOR.

-GENT OR ATTORNEY M50/mwah aN y mes Patented Jan. 25, 1949 HIGH-TEMPERATURE HYDROCARBON CONVERSION PROCESS Sylvander C. Eastwood, Woodbury, N. J., assignor to Socony-Vacuum Oil Company, Incorporated, a corporation of New York Application February 28, 1948. Serial No. 11,893

9 Claims. A( Cl. 196- 52) 'This invention deals with a process for conducting the conversion of fluid hydrocarbons in the presence of a moving particle form solid contact material'which may or may not be catalytic in nature. The invention has particularly to do with a hydrocarbon conversion process wherein the reaction is endothermic and the heat of reaction is supplied into the reaction zone as sensible heat in the hot contact material charge whichenters the reactor at a temperature level which is substantially above the average conversion temperature and often above a safe level at which it is practical to mechanically convey the solid material in conventional conveyor equipment. Exemplary of such processes is the high temperature catalytic cracking conversion of hydrocarbons to form high percentages of aviation gasoline and C4 fractions at temperatures of the order of M100-1200* F. and pressures usually ranging upwards from atmospheric pressure. Another process is the dehydrogenation of butene to di-oleilns at temperatures of the order of 1000-1300 F. in the presence of a dehydrogenation catalyst such as chromlc oxide on activated alumina. Still another reactor is the pyrolysis of pentene-2 to butadiene at temperatures of the order of 12001300 F. Another process is thev manufacture of ethylene by the cracking of heavier hydrocarbons such as gas oils or by the cracking of propane or ethane at temperatures of the order of 1400 F.-1800 F. A process of particular importance is the catalytic cracking conversion of high boiling petroleum residuums and the like to lower boiling hydrocarbon products at average reaction temperatures of the order of 800-1000 F. In the case of the latter reaction it is desirable to supply in the catalyst feed not only the heat for the cracking reaction but also the latent heat required to vaporize the liquid hydrocarbon feed. This often requires an inlet catalyst temperature substantially above the average conversion temperature and substantially above a level at which it is practical to mechanically convey the catalysts.

A particularly desirable continuous process for converting hydrocarbons in the presence of a moving catalyst is one wherein the catalyst ows cyclically through a conversion zone in which it flows downwardly by gravity as a substantially compact column while being contacted with fluid hydrocarbons to elect the conversion thereof and then through a regeneration zone in which it also moves as a compact column while being contacted with a combustion supporting gas to burn off from the catalystla carbonaceous contaminant deposited thereon in the conversion zone.

An important practical difficulty arises in attempting to conduct such processes as enumerated above in the so-called moving bed type of processes. Such moving bed type processes for proper operation require the use of a granular or particle form contact material as distinguished from powdered contact material and it is of the utmost importance in moving bed processes to limit the amountof catalyst attrition to iines to an absolute minimum. In order to attain this objective it has been found necessary in such systems wherein cyclic ow of the contact material is involved to utilize mechanical conveyors to complete the cyclic event. One of the most satisfactory types of mechanical conveyors for this purpose is the continuous bucket elevator which is adapted to transfer solid particles from one level to another with a minimum of breakage and attrition of said solid particles. However, in processes of the type described hereinabove, the required contact material inlet temperature to the hydrocarbon convertor is often so high that attempts to mechanically convey the contact materials at such temperatures would result in failure and very rapid wear of the metal parts of the mechanical conveyor. It has been suggested heretofore that in processes of the type herein involved, the heat required for the hydrocarbon conversion may be economically provided by permitting the catalyst temperature to rise in the regeneration and by then passing the hot regenerated catalyst directly into the reaction zone. Prior art publications have shown diagrams of regenerators positioned vertically above hydrocarbon convertors so that the hot regenerated catalyst ows directly by gravity from the regenerator to the reactor. Such an arrangement has the serious disadvantage that on a practical commerclal scale the heavy regenerator vessel must be supported high in the air at elevations running into two and three hundred feet, thereby greatly increasing the cost of the structural support and vices are highly undesirable because they cause` crushing of the catalyst particles and rapid formation of nes.

Because of these serious dimculties it has been commercial practice to position the reactors and regenerators side by side and to employ mechanical conveyors to transport the catalyst to locations from which it may ow into these vessels. In such arrangements, the regenerated catalyst is mechanically conveyed to a surge hopper above the reaction zone from which it ows by gravity into the reaction zone. Because of the necessity of mechanically conveying the hot regenerated catalyst, it has been found to be infeasible to conduct many operations which would require a catalyst inlet temperature to the conversion zone which is above the practical mechanical convey- 'ing level. It has been found that a practical mechanical conveying temperature for conventional mechanical conveying equipment adapted for high temperature work should be preferably below about 1000 F. and in any event below about 1100 F.

A major object of this invention is the provision of a continuous catalytic process for conversion of hydrocarbons which overcomes the above mentioned difliculties.

A specic object is the provision of a process for conducting endothermic conversions of uid hydrocarbons in the presence of a moving mass of particle form solid contact material at temperatures which are at least partially substantially above those at which it has been heretofore found practical to convey solid particles.

Another specific object is the provision of an improved cyclic process for the high temperature conversion of saturated fluid hydrocarbons to ethylene containing products.

These and other objects of this invention will become apparent from the following discussion thereof.

The invention may be most readily under-` stood by reference to the single drawing attached hereto which shows diagrammatically an elevational view of a preferable continuous cyclic conversion system for conducting the method of this invention.

In the drawing we nd a vertical conversion vessel I0, having a vertical gravity catalyst feed leg II connecting into its upper end and a discharge conduit for catalyst I2 connecting into its lower end and bearing a catalyst flowy control valve I3. Alongside of the convertor I is a regeneration vessel I4 provided with a catalyst inlet duct I at its upper end and a catalyst outlet conduit I6, bearing a flow control valve at its lower end. A catalyst surge chamber I1 is positioned at the upper end of vessel I4 and a catalyst surge hopper I'8 is positioned at the upper end of the gravity feed leg I I for reactor supply. A suitable mechanical conveyor I9 is provided to carry spent catalyst from the convertor I0 to a location wherefrom it may flow by gravity via duct I5 to the regenerator catalyst surge chamber I1. Similarly a mechanical conveyor 20 is provided to convey hot regenerated catalyst from the regenerator I4 to a location above the convertor surge hopper I8 from which location catalyst may flow by gravity via duct 2l to the surge hopper I8. 'Ihe conveyors I9 and 20 are driven by motors 22 and 22 'respectively and should be of a type adapted for high temperature service and for conveying particle form catalyst without excessive attrition, crushing and breakage thereof. A continuous bucket elevator has been found to be very satisfactory for this purpose but the invention is not contemplated as being restricted to only this type of mechanical conveyor.

The regenerator I4 shown is of the multistage type consisting of alternate burning zones 22 and cooling zones 24. Air may be introduced from a manifold 25 into each burning zone 23 via pipes 26 and after :dow through the catalyst may be withdrawn via pipes 21 and manifold 2l. A cooling fluid may be introduced into each cooling zone from manifold 29 via pipes I0 into suitable heat transfer tubes (not shown) within the cooling zones. The cooling fluidv may be withdrawn from the heat transfer tubes via pipes 22 to a common outlet manifold 22. A regenerator of this type is described in United States Patent 2,417,399, which was issued on March ll, 1947, to Simpson et al. While this is a preferred form of regenerator, it is contemplated that within the scope ofthe present invention other regenerators adapted for burning regeneration of catalysts under controlled temperature conditions may be employed.

'I'he convertor I'II is provided with a reactant inlet 35 near its lower end and with a purge gas l inlet 31 a spaced distance below the inlet 26.

Suitable vapor distribution devices well known to the art may be provided to insure proper distribution of the inletvapors into the catalyst column within the vessel I9. Also suitable baffling may be provided near the bottom of the vessel I0 to promote uniformity of catalyst withdrawal from all portions of the vessel crosssectional area. A suitable battle system for this purpose is described in United States Patent 2,412,136, issued on December 3, 1946, to Evans et al. Across the upper section of vessel I0 are provided two vertically spaced horizontal partitions 39 and 40 which dene a seal chamber 4I and a catalyst final burning chamber 42. Uniformly distributed conduits 49 depend from partition 39 for flow of catalyst from final burning chamber 42 to seal chamber 4I and similar conduits 44 depend from partition 40 for flow of catalyst from seal chamber 4I to the reaction chamber 43. The conduits 44 also define a gassolid disengaging space 45 immediately below partition 40. A reaction product vapor outlet conduit 41 connects through the vessel wall into this disengaging space. A row of inverted gas inlet distributing troughs 5I (one being shown) is positioned within final burning zone and these troughs are supplied with air via a row of pipes 52. Spaced vertically above and below troughs 5| are rows of collector troughs 54 and 55 from which gas is Withdrawn via pipes 5B and 51 respectively. Similar distributing troughs 58 supplied by pipes 59 and collector troughs 50 and 5I with outlet pipes 52 and 53 respectively are provided in the surge hopper I8.

In operation hot regenerated catalyst passes from hopper I8 down through the elongated feed leg Il into the upper end of chamber 42 and then through seal chamber 4I into reaction chamber 43. The hopper I8 may be at substantially atmospheric pressure whereas the pressure in seal chamber 4I is somewhat above (say one half pound per square inch) that in the upper section of reaction chamber 42. The feed leg II should be of sufiicient length to overcome this pressure differential. Such a feed leg is described in United States Patent 2,410,309, issued to Simpson et al. on October 29, 1946. The catalyst flows by gravity downwardly through chambers 42, 4I and 43 as a substantially compact column. Fluid reactants introduced at 2l pass through the catalyst column to become converted to lower boiling hydrocarbons -and the gaseous products are withdrawn at 41. It will be understood that the term gaseous as used herein in describing and claiming this invention is used in a broad sense as meaning that the material involved exists in the gaseous phase under the conditions of temperature and pressure involved regardless of what may be its normal phase under ordinary atmospheric conditions. If the reactant charge Ais a high boiling liquid charge, for example a petroleum reslduum, it may be introduced into the upper section of chamber 43 through manifold 80, header 8i .and spray nozzles 82, and the gaseous products will in -that event be withdrawn from the lowersection of chamber 43 at 36. The reactions towards which this invention is directed are endothermic and in order to supply the heat of reaction the catalyst is introduced into chamber 43 above the desired average reaction temperature and is Withdrawn at l2 below the desired average reaction temperature. For example, in a high temperature conversion of a liquid residuum petroleum charge to lower boiling gaseous products the catalyst may enter the reaction chamber 43 at a temperature within the range 1100 to 1200 F. and the drop in catalyst temperature in passing through the conversion zone may vary from about 10D-300 F. or more depending upon the particular operating conditions, the severity of the reaction and the catalyst to oil ratio. In .a typical operation the catalyst may enter at 1200 F. and leave the convertor via conduit l24 atabout 950 F. This latter temperature is sufficiently low to permit mechanlcal conveying of the spent .catalyst particles without further cooling. so the spent catalyst may be directly transferred by mechanical conveyor I9 to the upper end of duct l5 through which it may ilow by gravity .to the regenerator catalyst surge zone il. The catalyst then passes downwardly through the regenerator I4 as a substantially compact vcolumn while being subjected to an oxygen containing gas such as air to burn off the carbonaceous contaminant deposited on the catalyst in the convertor. Heat is removed from the catalyst in the cooling zones 24 so as to maintain it at a temperature level below a heat damaging level and above that minimum required for practical contaminant burning rates. The heat damaging temperature will vary depending upon the nature of the contact material involved being abovey about 1150-1250 F. for many clay catalysts and above about 1350-1500" F. for synthetic silica-alumina Vgel catalysts. The rate of air introduction into the burning zones and/or the rate of catalyst ilow through the regenerator is so controlled that the catalyst discharging from the lowermost burning zone still contains a residual carbonaceous deposit which is within the range about 0.2 to 0.7 percent by weight contaminantbased on the catalyst over and above any deposit which ls normally left on the "freshly regenerated catalyst entering the reaction zone 43. The exact amount of contaminant left on the catalyst will depend upon the catalyst temperature rise desired in zones I8 or 42 as discussed hereinafter and upon the allowable residual contaminant on th-e freshly regenerated catalyst entering zone 43. Usually for catalytic cracking of gas oils or heavier hydrocarbons, the allowable residual carbon content on the freshly regenerated catalyst entering reaction zone 43 will be of the order of about 0.1 to 1.0% by weight of lthe catalyst depending upon the particular reaction and the operating conditions. s

In some operations the regeneration may be so controlled that the temperature of the catalyst may be at a level suitable for mechanical conveying in which event it may be passed directly to the mechanical conveyor 20 without intermediate cooling. This is usually the case also when single stage regenerators provided with cooling tubes throughout their length are employed. .)n the other hand the catalyst leaving the last burning zone 23 may be above a temperature at which it may be practically mechanically conveyed, for example 1200" F. or even higher, in

which event it is cooled in cooling zone lo to a suitable mechanical conveyingl temperature which is below about 1100 F. and preferably at or below about 1000 F. The catalyst at 1000 F., for example, is then mechanically conveyed to the inlet end of duct 2| through which it ilows into hopper i8. The catalyst entering hopper i8 at 1000 F. is because of the mechanical conveyor maximum temperature limitation below the temperature required for its introduction into lzone 43, namely 1200 F. in the exemplary operation under discussion. Air is introduced via pipes 59 and distributed into the catalyst bed by troughs 58, and is passed through thecatalyst bed in hopper I8 to the collectors 60 and 6l so as to accomplish burning of the 'residual contaminant in the absence of heat removal by any other heat exchange fluid. The catalyst temperature is thereby increased due to the heat liberated by contaminant combustion, and the rate of air introduction is controlled so as Ito burn sulcient contaminant deposit to heat the catalyst to the required temperature of 1200o F. As stated above, the amount of contaminant remaining on the catalyst entering hopper i8 is maintained equal to that required to accomplish this heatingT of the catalyst in hopper I8 over and above any allowable residual deposit on the catalyst entering the reactor zone 43. The required amount of residual contaminant on the catalyst entering hopper I8 may be easily calculated by methods known to those skilled in the art once the particular operating temperature conditions and the allowable residual deposit on the cataylst entering the hydrocarbon reaction zone have been set for the particular hydrocarbon conversion reaction involved. In general, it has been found that for most endothermic catalytic hydrocarbon conversion reactions the amount of contaminant on the catalyst leaving the principal regeneration zone should be within the range 0.2-0.7 percent by weight of the catalyst calculated as carbon over and above any residual deposit on the freshly regenerated catalyst as it enters the hydrocarbon conversion zone. The heated freshly regenerated catalyst then passes by gravity into the seal zone 4l and then into the reaction zone 43. An inert seal gas such as steam or flue gas is introduced into the seal zone 4| via pipe 15 at a rate controlled by diaphragm valve 16 and differential pressure controller Il which will maintain an inert gas pressure in seal zone 4I slightly higher (one quarter to one half pound per square inch) than the pressure within lthe upper section of zone 43, thereby preventing escape of reactants through the catalyst feed leg il. When the hopper i8 is employed as described hereinabove, the zone 42 may be eliminated, leaving a seal zone only at the upper end of vessel i0. t

It will be apparent that by the method of this V7 invention it becomespossible to conduct many reactions requiring catalyst reactor inlet temperatures substantially above the level at which conventional mechanical conveyors can be employed. and this without any increase in the overall height of the cyclic system and with an actual decrease in the required size of the regenerator. It will be noted that the catalyst surge hopper I8 is already employed in commercial cyclic conversion systems of the moving bed type so that present commercial units may be adapted for the method of this invention simply by adding gas distributing and collecting troughs and connecting pipes to the already existing reactor surge hopper.

When the reactor surge hopper is employed as a iinal burning zone as described hereinabove. the regeiieration pressure in the hopper is near atmospheric due to the fact that the conveyors are most conveniently operated at atmospheric pressure. In some operations it is desirable in order to obtain more rapid burning of the residual contaminant deposit to conduct the final burning step under pressure. In such operations. it is preferable to employ zoneV 42 as the ilnal burning zone instead of hopper I8, because the feed leg Il is then available to feed the catalyst into the regeneration zone operating under superatmospheric pressure. In this operation the air is introduced into zone I2 via pipes 52 and the gaseous regeneration products are withdrawn via pipes 56 and 51. When zone 42 is so employed it is important to maintain the inert gas pressure within seal zone Il not only above the pressure in reaction zone I3 as described hereinabove but also above the pressure within zone 42. 'I'his is accomplished by means of the auxiliary inert gas inlet 85 through which additional inert gas is introduced as controlled by diaphragm valve 88 and differential pressure controller 81 whenever the rate of inert gas introduction -through valve 16 is insuiilcient to maintain the pressure in zone 4i above that in zone I2.

It will be understood that the dimensions of the apparatus employed, the rates of reactant and solid flow, and the type of solid material and heat exchange gas employed are subject to wide variation depending upon the particular process to which this invention is applied. In general, the reaction zone should be of such size as will permit the proper time of reactant contact with the suitable solid material therein for any given process. The final burning zone should be of sutlicient volume to provide a catalyst residence time long enough to accomplish the desired heating of the catalyst by the contaminant burning. The required volume of final burning zone may be decreased by the use of pressure in this zone.

The reactant space velocity in the conversion zone will, of course, vary depending upon the particular operation involved. Where petroleum gas oils are to be converted to products containing high amounts of aviation gasoline and four carbon atom hydrocarbons the oil space velocity may vary from about 0.5 to 5.0 volumes of oil charge (measured as a liquid at 60 F.) per hour per volume of catalyst in the conversion zone (measured as a substantially compact flowing column). The catalyst to oil charge ratio to the convertor in such an operation may fall within the range about 1 to 10 parts by weight of catalyst per part by weight of oil charged. In the case the pyrolytic conversion of ethane to ethylene over refractory contact material particles at inlet solid material temperatures of the order of 1750-1800 F. at about 5-20 pounds per Square inch pressure, a solid material throughput amounting to about rto 15 pounds of solid per pound of ethane charge is satisfactory. 'I'he volume of the reaction zone 24 should be such as to provide a reactant residence time of about 1.0 to 1.7 seconds.

` The type of solid material used may vary from an inert solid such as corhart material. a fused alumina, which may be used for ethylene manufacture to an adsorbent type catalytic material vwhich may be used for catalytic dehydrogenation reactions and for catalytic cracking reaction. Such catalytic materials may take the form of natural or treated clays, bauxites, inert carriers containing deposited metallic oxides such as deposits of the oxides of molybdenum, chromium or tungsten, or certain synthetic associations of silica, alumina or silica or alumina to which small percentages of other materials such as metallic oxides may be added for special purposes. In general, it has been found that the particle size of such contact materials should fall broadly within -the range about .006 lto 1.0 inch average diameter and preferably within the range about 0.03 to 0.5 inch average diameter. It should be understood that the expression "suitable particle form contact material as used in describing and in claiming this invention is used in a sense sumciently broad to cover either socalled catalytic or non-catalytic materials which may be found suitable for the particular reaction involved. The term is to be considered as llmited, however, only to those solid materials which have physical 'and chemical characteristics making them suitable for the particular process involved. Thus, for example solids. which would enter substantially into the main reaction or which would be decomposed or otherwise damaged under the reaction conditions involved, are not intended to be included in the term.

In the claiming of this invention the expressions suitable conversion temperature and range of suitable conversion temperature" are intended to mean a temperature or range of temperatures which are suitable for conducting the particular reaction involved at a practical rate and to practical yields of the desired products.

- AIt should be understood that the foregoing description of the method of this invention and examples of its applications and of the apparatus to which it may be applied are merely exemplary in character and are not intended to limit the scope of this invention except as it is limited in the following claims.

I claim:

l. A continuous process for conducting endothermic conversions of fluid hydrocarbons at elevated temperatures in the presence of a suitable contact material consisting of particles of substantial size as distinguished from powdered material which process comprises: introducing said contact material into the upper section of a confined conversion zone at a temperature suitable for supporting the conversion of said fluid hydrocarbons and for supplying at least most of the heat of reaction, passing said contact material downwardly through said conversion zone while contactingit kwith said hydrocarbons to effect the conversion thereof with resultant deposition of a carbonaceous contaminant deposit on said contact material, withdrawing the used contact material from the lower section o'f said conversion zone and passing it to av mechanical conveying zone at a temperature at which it may be practil cally mechanically conveyed. maintaining a confined burning zone separate from said conversion zone, mechanically conveying said used contact material to a location from which it may flow into said burning zone, passing said contact material downwardly through said burning zone, passing a combustion supporting gas into contact with said contact material in said burning zone to effect burning of a substantial portion of butless than all of said contaminantdepositfrom said contactmaterial, passing the contact material bearing a residual portion of the original contaminant deposit from said burning zone to a conilned conveying zone and controlling the temperature of said contact material passing to said last named conveying zone at a level at which the contact material may be practically mechanically conveyed, maintaining a conflned final burning zone above said conversion zone, conveying said contact material bearing said residual portion of the original contaminant deposit to a location from which it may flow into said final burning zone, passing said contact material through said final burning zone and eiecting an increase in its temperature to a level which is suitable for supporting said hydrocarbon conversion and for supplying at least most of the heat absorbed by the hydrocarbon reaction by burning off at least a substantial portion of the residual contaminant deposit with an oxygen containing gas and passing the contact material by gravity ow 'from said final burning zone into the upper section of said conversion zone as aforesaid.

2. In a continuous process for endothermic conversions of fluid hydrocarbons at elevated temperatures in the presence of a moving particle form solid contact material, wherein the heat of reaction is supplied at least mostly by the contact material thereby requiring an initial contact material temperature substantially above that at which it can be practically mechanically conveyed the improved method which comprises: passing said contact material as a substantially com-pact column downwardly through a confined conversion zone while contacting it with said fluid hydrocarbons to effect the conversion thereof, whereby av carbonaceous contaminant is deposited on said contact material and the temperature of said contact material is decreased due to heat adsorption by said conversion to a level at which the contactmaterial may be practically mechanically conveyed, maintaining a coniined burning zone separate from and along side of said conversion zone, withdrawing spent contact material from said conversion zone and mechanically conveying said contact material upwardly to a location suitable for its flow into said burning yzone, passing said spent contact material as a substantially compact column downwardly through said burning zone, passing a combustion supporting gas into contact with said contact ma terial in said burning zone to effect burning of an version zone, mechanically conveying said contact material bearing said residual contaminant deposit to a location from which it may flow by gravity into said iinal burning zone, passing said contact material downwardly through said ilnal burning zone as a substantially compact column while contacting it with a combustion supporting gas to effect the burning off of said residual contaminant deposit, eilecting the removal of at least a major portion of the heat released by contaminant burning in said ilnal burning zone as increased sensible heat in the contact material so as to thereby increase the contact material temperature to a level suitable for supplying in the contact material at least the major part of the heat required for the endothermic hydrocarbon conversion in said conversion zone, said level being substantially above that at which the contact material can be practically mechanically conveyed and flowing said contact material fromsaid final burning zone by gravity to said conversion zone to supply said column of contact material therein.

3. In a continuous process for endothermic catalytic conversions of fluid hydrocarbons to lower boiling hydrocarbons at elevated temperatures in the presence of a moving particle form solid catalyst wherein at least the major portion of the heat of reaction is supplied as sensible heat in the catalyst charge thereby requiring a catalyst charge temperature substantially above that at which the catalysts can be practically mechanically conveyed the improved method which comprises: introducing freshly regenerated catalyst into the upper section of a confined conversion zone and passing said catalyst as a substantially compact column of gravltating particles downwardly through said confined conversion zone while contacting it with said fluid hydrocarbons to effect the conversion thereof to lowerwboiling hydrocarbons whereby a carbonaceous contaminant deposit forms on said catalyst and the temperature of said catalyst is decreased, due to absorption of heat therefrom for said hydrocarbon conversion, to a levelv at which the catalyst may be practically mechanically conveyed, maintaining a regeneration zone apart from said conversion zone, withdrawing spent catalyst from the lower section of saidl conversion zone and mechanically conveying it to a location from which it may iiow by gravity into the upper section of said regeneration zone, passing said catalyst as a substantially compact column downwardly through said regeneration zone, burning off contaminant deposit from said catalyst by contacting said catalyst moving through said regeneration zone with an oxygen containing gas until the amount of residual deposit on said catalyst is within the range about 0.2 to 0.7 percent by Weight of said catalyst in addition to any deposit left on the freshly regenerated catalyst entering said conversion zone, passing a fluid other than said combustion supporting gas in heat exchange relationship with said` catalyst during its passage through said regeneration zone to remove a substantial portion of the heat liberated by contaminant burning and to control the temperature of said catalyst below a level which would cause heat damage to said catalyst, withdrawing from the lower section of said regeneration zone the partially regenerated catalyst bearing a residual contaminant deposit of from about 0.2-0.7 percent by weight of the catalyst in addition to any deposit left on the freshly regenerated catalyst entering the conversion zone and passing said catalyst at a temperature at which it can be practically mechanically conveyed to a conilned mechanical conveying zone, maintaining a substantially compact column of said partially regenerated catalyst in a conilned ilnal burning zone above said conversion zone, mechanically conveying said catalyst to a location from which it may ilow by gravity to said iinal regeneration zone, ilowing said catalyst by gravity into said ilnal burning zone to supply said column there in, effecting an increase in the temperature oi' said catalyst to a level which is substantially above that at which it can be practically mechanically conveyed and which is sumciently high to insure supply of the heat required i'or said hydrocarbon conversion as sensible heat in the catalyst by contacting said catalyst in said ilnal burning zone with a combustion supporting gas in the absence of heat removed by any other iluid medium to burn oi! from said catalyst within the range of 0.2 to 0.7 percent of said residual deposit, and passing the heated, freshly regenerated catalyst as a gravity ilowing stream into the upper section of said conversion zone as aforesaid.

4. In a continuous process for endothermic conversions of fluid hydrocarbons at elevated temperatures in the presence oi a moving particle form solid contact material, wherein the heat of reaction is supplied at least mostly by the contact material thereby requiring an initial contact material temperature substantially above that at which it can be practically mechanically conveyed the improved method which comprises: passing said contact material as a substantially compact column downwardly through a confined conversion zone while contacting it with said fluid hydrocarbons toeect the conversion thereof, whereby a carbonaceous contaminant is deposited on said contact material and the temperature o i' said contact material is decreased due to heat adsorption by said conversion to a level below about 1100 F. maintaining a confined burning zone separate from and along side of said conversion zone, withdrawing spent contact material from said conversion zone and mechanically conveying said contact material upwardly to a location suitable for its flow into said burning zone, passing said spent contact material as a substantially compact column downwardly through said burning zone, passing a combustion supporting gas into contact with said contact material in said burning zone to effect burning of a substantial portion but less than all of said contaminant, passing. a separate heat exchange iluid in heat exchange relationship with said catalyst to control its temperature during the contaminant burning below a heat damaging level, withdrawing contact material from the lower section of said burning zone bearing a residual contaminant deposit amounting to at least 0.2 percent by weight of the contact material over and above that on said contact material entering said conversion zone, controlling the temperature of said contact material bearing said residual deposit at a practical mechanical conveying temperature which is below about 1100 F. and passing said contact material bearing said residual deposit to a mechanical conveying zone, maintaining a moving column of said contact material in a nal burning zone above said conversion zone, mechanically conveying said contact material bearing said residual deposit to a location above said inal burning zone from which it may flow by gravity into said nnal burning sone, ilowina said con.

tact material into the upper section of'said ilnal burning zone to supply said column therein, contacting said contact material in said final burning zone with a combustion supporting gas in the absence of substantial heat removal by a heat exchange iluid to eilect burning ot residual contaminant on said contact material amounting to at least about 0.2 percent by weight, thereby heating said contact material to a temperature substantially above 1100 l". which is suitable for supplying as sensible heat in the contact material at least the major portion of the heat required for the endothermic hydrocarbon conversion in said conversion zone and flowing said contact material as a coniined gravitating stream from said i'lnal burning zone to said conversion zone to supply said column of contact material therein.

5. In a continuous process i'or endothermic catalytic conversions oi' fluid hydrocarbons to lower boiling hydrocarbons at elevated temperatures in the presence of a moving particle form solid catalyst wherein at least the maior portion of the heat of reaction is supplied as sensible heat in the catalyst charge thereby requiring a catalyst charge temperature substantially above that at which the catalyst can be practically mechanically conveyed the improved method which comprises: introducing freshly regenerated catalyst into the upper section of a conilned conversion zone at a temperature above about 1000 F. and passing said catalyst as a substantially compact column of gravitating particles downwardly through said confined conversion zone while contacting it with said iiuid hydrocarbons to effect the conversion thereof to lower boiling hydrocarbons whereby a carbonaceous contaminant deposit forms on said catalyst and the catalyst is cooled to a temperature below about 1000 1". at which the catalyst may be practically mechanicallyponveyed, maintaining a regeneration zone apart from said conversion zone, withdrawing spent catalyst from the lower section of said conversion zone and mechanically conveying it to a location from which it may ilow by gravity into the upper section of said regeneration zone, passing said catalyst as a substantially compact column downwardly through said regeneration zone, passing a combustion supporting gas into contact with said catalyst to burn oi! a substantial portion but not all of said contaminant deposit while removing heat liberated by the contaminant burning by means of a separate heat exchange fluid, withdrawing partially regenerated catalyst from the lower section of said regeneration zone bearing more than about 0.2 percent by weight but less than about 0.7 percent by weight contaminant measured as carbon over and above any contaminant deposit on the freshly regenerated catalyst entering the'conversion zone, controlling the temperature oi the partially regenerated catalyst below about 1000 F. and passing it to a mechanical conveying zone, maintaining a moving column o! catalyst in a connned iinal burning zone above said conversion zone. mechanically conveying said catalyst bearing said residual deposit to a location above said nnal burning sone from which it may ilow by gravity to said ilnal burning zone. :lowing said catalyst into the upper section of said ilnal burning zone to supply said column therein, passing a combustion supporting gas into contact with said catalyst in said ilnal burning zone, in absence of substantial heat removal by any fluid heat exchange medium, at a controlled rate to effect burning of residual contaminant deposit from said catalyst amounting to less than 0.7 percent by weight but more than 0.2 percent by weight of the catalyst, measured as carbon, whereby the temperature of said catalyst is increased to a level above about 1000 F. which will insure supply of the heat of hydrocarbon conversion as sensible heat in said catalyst and flowing said catalyst into said conversion zone as said freshly regenerated catalyst as aforesaid.

6. A continuous process for conversion of high boiling liquid hydrocarbons to lower boiling hydrocarbon products in the presence of a moving particle form adsorbent catalyst which comprises: introducing freshly regenerated catalyst containing a small residual deposit of carbonaceous material into the upper section of a conned conversion zone at a temperature above about 1000 F. and Apassing said catalyst as a substantially compact column downwardly through said zone, introducing high boiling liquid hydrocarbons into said conversion zone in contact with said catalyst to effect conversion of said hydrocarbons to lower boiling gasiform products, whereby a carbonaceous contaminant is deposited on said catalyst and the temperature of said catalyst is decreased, due to heat absorption by said hydrocarbon conversion, to a. level at which the catalyst may be practically mechanically conveyed, maintaining a regeneration zone apart from said conversion zone, withdrawing spent catalyst from the lower section of said conversion zone and mechanically conveying it to a location from which it may flow by gravity into the upper section of said regeneration zone, passing said catalyst as a substantially compact column downwardly through said'regeneration zone, passing an oxygen containing gas under a back pressure vnear atmospheric pressure through said column of catalyst in said regeneration zone to burn off a substantial portion but not all of said contaminant deposit while removing heat liberated by contaminant burning by means of a separate heat exchange iluid, withdrawing partially regenerated catalyst from the lower section of said regeneration zone bearing more than about 0.2 percent by weight but less than about 0.7 percent by weight contaminant measured as carbon over and above any contaminant deposit on the freshly regenerated catalyst entering the conversion zone, passing the partially regenerated catalyst at a practical mechanical conveying temperature to a mechanical conveying zone, maintaining a moving column of catalyst in a confined nal burning zone above said conversion zone, mechanically conveying said catalyst bearing said residual deposit to a location above said final burning zone from which it may ow by gravity to said nal burning zone, flowing said catalyst into the upper section of said final burning zone to supply said column therein, passing a combustion supporting gas into contact with said catalyst in said final burning zone, in absence of substantial heat removal by any fluid heat exchange medium, at a controlled rate to effect burning of residual contaminant deposit from said catalyst amounting to less than 0.7 percent by Weight but more than 0.2 percent by weight of the catalyst, measured as carbon, whereby the temperature of said catalyst is increased to a level above about 1000 F. which will insure supply of the heat of hydrocarbon conversion as sensible heat in said catalyst, controlling a back pressure on the gas in said final burning zone substantially above atmospheric so as to increase the rate of contaminant 14 burning and flowing the catalyst from said nal burning zone into said conversion zone as said freshly regenerated catalyst as aforesaid.

7. A continuous process for conducting endothermic conversions of fluid hydrocarbons at elevated temperatures in the presence of a suitable contact material consisting of particles of substantial size as distinguished from powdered material which process comprises: introducing said contact material into the upper section of a confined conversion zone at a temperature suitable for supporting the conversion of said iiuid hydrocarbons and for supplying at least most of the heat of reaction, passing said contact material downwardly through said conversion zone while contacting it with said hydrocarbons to effect the conversion thereof with resultant deposition of a carbonaceous contaminant deposit on said contact material, With,- drawing the used contact material from the lower section ofv said conversion zone and passingit to a mechanical conveying zone at a temperature at which it may be practically mechanically conveyed, maintaining a confined burning zone separate from said conversion zone, mechanically conveying said used contact material to a location from which it may ow into said burning zone, passing said contact material downwardly through said burning zone, passing an oxygen containing gas into contact with said contact material at a low pressure which is near atmospheric pressure to burn off from said contact material in saidburning zone sulcient contaminant deposit to reduce the residualideposit on said contact .material at least below about 0.7 percent carbon by weight of contact material over and above the deposit on the contact material entering the conversion zone, passing the contact material bearing the residual deposit from the lower section of said burning zone to a confined conveying zone and controlling the .temperature of said contact material passing to said last named conveying zone at a y level at which the contact material may be practically mechanically conveyed, maintaining a conned final burning zone above said conversion zone, conveying said contact material bearing said residual portion of the original contaminant deposit to a location from which it may flow. into said final burning zone, passing said contact material through said final burning zone in the absence of substantial heat removal by any heat exchange iluid, passing an oxygen containing gas into contact with the contact material in said final burning zone andcontrolling the gaseous pressure throughout said zone substantially above the pressure in said first named regeneration zone, controlling the amount of such gas flow sufficiently high to burn off from said contact material a sufficient amount of residual contaminant deposit to heat said contact material to a temperature substantially'above the average conversion temperature in said hydrocarbon conversion zone and passing the'contact material without intermediate cooling and by gravity flow from said nal burning zone into the upper section of said conversion zone as aforesaid.

8. In a continuous process for endothermic catalytic conversions of iiuidhydrocarbons to lower boilingr hydrocarbons at elevated temperatures in the presence of a moving particle form solid catalyst wherein at least the major portion of the heat of reaction is supplied as sensible heat in the catalyst charge thereby requiring a catalyst charge temperature 'substantially above that at which the catalyst can be practically mechanically conveyed the improved method which comprises: introducing freshly regenerated catalyst bearing a small amount of residual carbonaceous deposit into the upper section of a coniined conversion zone at a temperature above about 1000 F. and passing said catalyst as a substantially compact column o! gravitating particles downwardly through said confined conversion zone while contacting it with said duid hydrocarbons to etlect the conversion thereof to lower boiling hydrocarbons whereby a carbonaceous contaminant deposit forms on said catalyst and the catalyst is cooled to a temperature below that maximum at above which it could not be practically mechanically conveyed, withdrawing spent catalyst i'rom the lower section of said conversion zone and mechanically conveying it to a catalyst surge zone maintained apart from said conversion zone, nowing the catalyst by gravity from said surge zone downwardly i through a series of burning zones as a substantially compact column, passing an oxygen containing gas into contact with said catalyst in each of said burning zones to burn oil' a portion of the contaminant deposit, passing a cooling heat exchange fluid in heat exchange relationship with said catalyst between burning zones to maintain the temperature oi' said catalyst below a heat damaging level, withdrawing catalyst from the lowermost burning zone still containing a residual deposit over and above that, amount on the catalyst entering said conversionzone, which deposit is within the range about 0.2 to 0.7 percent carbon by weight of the catalyst, cooling the partially regenerated catalyst to a practical mechanical conveying temperature, and mechanically conveying it to a location spaced above said conversion zone, flowing the catalyst by gravity as a substantially compact column downwardly through a conilned ilnal regeneration zone, passing a combustion supporting gas into contact with said catalyst in said ilnal burning 16 umn ot downwardly moving catalyst particles in a conned conversion zone, passing a iluid hydrocarbon reactant into contact with said catalyst to eilect its conversion to lower boiling hydrocarbon products whereby a carbonaceous contaminant deposit is formed on said catalyst and the temperature oi' said catalyst decreases to a suitable practical mechanical conveying temperature which is below about 1000 F., withdrawing said lower boiling hydrocarbon products from said conversion zone separately of said catalyst, withdrawing used catalyst from the lower section or said conversion zone. maintaining a regeneration zone apart from said conversion zone. withdrawing spent catalyst from the lower section oi' said conversion zone and mechanically conveying it to a location from which it may ilow by gravity into the upper section of said regeneration zone, passing said catalyst as a substantially compact column downwardly through said regeneration zone, passing an oxygen containing gas into contact with said catalyst in said regeneration zone to burn ott from said catalyst at least the major portion of but less than all of the contaminant 2.5 depositformed on said catalyst in each pass passing the partially regenerated catalyst from zone, in absence of substantial heat removal by 4 any iluid heat-exchange medium, at a controlled rate to effect burning of residual contaminant deposit from said catalyst amounting to less than 0.7 percent by weight but more than 0.2 percent by weight of the catalyst, measured as carbon, whereby the temperature of said catalyst is increased to a level above about 1000 F. which will insure supply of the heat of hydrocarbon conversion as sensible heat in said catalyst and ilowing said catalyst into said conversion zone as said freshly regenerated catalyst as aforesaid.

9. In a continuous process for endothermic catalytic conversions of iluid hydrocarbons to lower boiling hydrocarbons at elevated temperatures in the presence of a moving particle form solid catalyst wherein at least the major portion of the heat of reaction is supplied as sensible heat in the catalyst charge thereby requiring a catalyst charge temperature substantially above that at which the catalyst can be practically mechanically conveyed the improved method which comprises: maintaining a substantially compact colthe lower section of said regeneration zone cooled to a practical mechanical conveying temperature to a second conilned mechanical conveying zone. maintaining a confined supply bed of catalyst a spaced vertical distance above said conversion zone, mechanically conveying said partially regenerated catalyst to a location from which'it -may ilow onto said supply bed, passing an oxygen containing gas through said supply bed in absence of heat removal from said catalyst by separate cooling fluids to burn oi! a sufficient amount oi said residual deposit from said catalyst to heat said catalyst to a temperature substantially above the average conversion temperature in said hydrocarbon conversion zone and substantially above a practical mechanical conveying temperature, passing the catalyst without intermediate cooling downwardly from said supply bed into the upper section of said conversion zone as a substantially compact elongated confined stream of gravitating particles, and maintaining a seal blanket of inert gas adjacent the lower end of said stream to prevent escape of hydrocarbons through said stream.

SYLVANDER C. EASTW OOD.

REFERENCES CITED The following references are of record in the

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