US2366218A - Catalytic combination process - Google Patents

Description

R. F. RUTHRUFF GATALYTIC COMBINATION PROCESS `original Filed May 15, 1940 Jan, 2, 1945.

Patented Jan. 2, n1945 2,366,218 CATALYTIC COMBINATION PROCESS Robert F. Ruthrutl, Chicago, Ill.

Original application May 13, 1940, Serial No. 334,741. Divided and this application January s, 194s, seria1N0.471,4zs

(ci. 19e- 49) 14 Claims.

This invention relates to a process for the conversion of hydrocarbon mixtures of wide boiling range into hydrocarbons of high utility and value boiling within the usual motor fuel range. More particularly, this invention relates to a process forthe conversion of crude oils into hydrocarbons of high utility and value boiling within the usual motor fuel range. Still mo-re particularly, this invention relates to a process for the conversion of hydrocarbon mixtures lof Wide boiling range into hydrocarbons of high utility and value boiling within the usual motor fuel range wherein said hydrocarbonl mixtures of wide boiling range are separated into a plurality of fractions, some or all of which are then subjected separately but in cooperative combination to catalytic conversion conditions suitable for transforming said fractions into hydrocarbons of high utility and value boiling within the usual motor fuel range. Still more particularly, this invention relates to a process for the conversion of crude oils into hydrocarbons of high utility and value boiling within the usual motor fuel range wherein said crude oils are separated into a plurality of fractions, some or all of which are then subjected separately but in cooperative combination to catalytic conversion conditions suitable for transforming said fractions into hydrocarbons of high utility and value boiling within the usual motor fuelrange.

This application is a division of my copending application, Serial Number 334,741, filed May 13, 1940, now U. S. Patent 2,312,445, issued May 2, 1943.

A primary object of my invention is to provide an improved unitary combination cracking process for processing hydrocarbon mixtures of Wide boiling range, for example, crude oils, whereby a maximum, yield of motor fuel of superior antiknock quality is obtained.

A `further object of my invention is to provide a combination cracking process wherein hydrocarbon mixtures of wide boiling range,` for example, crude oils, are subjected to a distillng operation to separate a plurality of fractions, some or all of which are subjected to separate but cooperative catalytic conversion processes so as to obtain a maximum yield of motor fuel of superior antiknock quality.

Another object of my invention is to provide a combination cracking process wherein hydrocarbon mixtures of wide boiling range, for example, crude oils, are subjected to a distilling operation to separate a plurality of fractions, some or all of which are subjected to separate catalytic conversion processes -wherein byproducts from some of nevertheless these processes are far from perfect.

The ultimate gasoline produced is only of moderate octane rating and considerable improvement in this respect is highly desirable. Also, the gaso` line yield is not as high as could be desired because of the loss of potential gasoline as gas and tar. Because of these, and other disadvantages too numerous to mention, within the lastfew years attention has been directed to the replacing of thermal conversion methods by catalytic conversion methods. For example, catalytic methods for the reforming of naphtha `show great advantages over thermal conversion processes. Operating pressures are low, ranging from 'a little above atmospheric t0 a maximumof some 300 pounds per square inch, more or less. Operating temperatures are usually slightly lower than those employed in thermal reforming. The yield and quality of the catalytically reformed naphtha :are much higher than with thermally reformed naphtha. The catalytically reformed naphtha is rich in aromatics and accordingly has an octane rating considerably higher than that shown by any thermally reformed naphtha. Additionally, the gas formed in catalytic reforming consists largely of hydrogen and as a result the yields of catalytically reformed naphtha are much higher than are obtained in thermal reforming processes Where the gas consists largely of gaseous hydrocarbons.

Similarly, the catalyticcracking of gas oil shows many advantages over thermal processes. Op-K erating pressures are moderate, ranging from say 50 pounds per square inch downward while the usual operating temperature is in the range 775 to 975 F. The yield and quality of the gasoline obtained by the catalytic cracking of gas oil are much higher than with thermal conversion processes. The gasoline from catalytic cracking of gas oil has a much higher octane number than thermally cracked material and due to the lower gas ,yield and zero conversion of the charge to liquidsof higher boiling point, the theoretical ultimate yield of gasoline by catalytic cracking of gas oil is higher than that obtained in thermal processes.

While catalytic viscosity breaking has been studied t a certain extent, the results obtained to date are not such as to put the process on a firm commercial foundation. The reason for this is twofold. In the rst place, catalytic conversion processes as applied to ,hydrocarbons preferably and almost of necessity are conducted in the vapor phase and reduced crudes are hard to vaporize completely. Secondly, because of the high carbon to hydrogen ratio of reduced crudes any catalysts used foul very rapidly and hence require regeneration at frequent intervals. Accordingly, in processing reduced crudes by catalytic methods, it is usually preferable to rst convert the reduced crude into gas oil and tar (by viscosity breaking) or into gas oil and coke (by coking) and then further process the gas oil thus formed in a catalytic process similar to that described in the previous paragraph.

As far as I am aware no one has previously suggested a combination process for the conversion of hydrocarbon mixtures of wide boiling range, crude oil for example, wherein the usual fractions treated in the now familiar thermal combinations processes of the prior art are subjected to separate but cooperative catalytic conversion processes to produce a maximum yield of motor fuel of superior antiknock quality. I have found that by employing catalytic methods in a combination process for the conversion of hydrocarbon mixtures of wide boiling range, crude oil for example, the various catalytic zones cooperate with one another in a unique and highly beneficial manner and as a consequence, the overall results are markedly superior to those obtained by conducting the various operations separately.

Manyyariations are possible in the practice of my invention and accordingly it is impossible to encompass all of them in a brief exposition thereof. However, to indicate the spirit, but not the scope, of my invention the following brief description thereof is included:

Crude oil is fractionated to produce light naphtha, heavy naphtha, gas oil and reduced crude. 'I'he heavy naphtha is catalytically reformed, the resulting reaction products are separated into gas (mostly hydrogen), catalytically reformed naphtha (largely aromatics) and a small amount of material having a higher boiling range than the charge. Preferably, hydrogen formed in the catalytic reforming reaction is in part added to fresh heavy naphtha charge prior to entering the catalytic reforming zone. However, this recycling of a portion of the hydrogen is not essential and it is to be understood that the catalytic reforming process furnishes net hydrogen in large volumes. The reduced crude is subjected to once through viscosity breaking under thermal conditions. The resulting products are separated into gas, viscosity breaker gasoline, light viscosity breaker gas oil (which is added to the virgin light gas oil) and heavy viscosity breaker gas oil. The mixture of virgin light gas oil and light viscosity breaker gas oil is catalytically cracked and the resulting products are separated into gas, gasoline and bottoms. The bottoms are added to the heavy viscosity breaker gas oil and the mixture is also catalytically cracked and the resulting products are separated into gas, gasoline and bottoms. These last mentioned bottoms are mixed with a portion of the hydrogen produced in catalytic reforming and are then catalytically hydrogenated, the resulting products being returned to the crude oil fractionator. The several gasoline fractions are combined to produce the desired ultimate product.

For la more complete understanding of my invention, reference may be had to the accompanying single sheet of drawings forming a Dart of the instant specification and wherein,

The figure is a diagrammatic illustration, partly in section and partly in elevation, of an apparatus suitable for carrying out the process of my invention.

Turning now to the aforementioned figure, hot crude passes through line lto the lower portion of fractionating tower 2. The crude, prior to lentering fractionating tower 2; is heated by any suitable means (not shown), for example, by being brought into indirect heat exchange relationship with one or more hot streams followed by passage through an ordinary pipe still. Fractionating tower 2 is provided with means for promoting intimate liquid-vapor Contact therein, for example, bubble trays 3, although any other suitable means for the purpose may be employed, for example, the tower may be lled with packing material such as Raschig rings. Fractionating tower 2 is also provided with suitable cooling means. This may take the form of one or more closed coils (not shown) disposed in the upper portion of the tower, through which cold fluid, for example, cold crude, is passed. Or, cold liquid of suitable boiling point may be introduced into the tower at one or more points to provide cooling therein as will hereinafter be more fully explained. Obviously, either or both cooling means may be employed or other suitable procedures may be resorted to for the purpose. Fractionating tower 2 is also provided, if desired, with bottom heating means. This may take the form, for example, of an open or closed coil 4 positioned in the lower portion of the tower through which hot fluid is passed. Specifically, fractionating tower 2 may be provided with an open steam coil 4, steam introduced also aiding in stripping lower boiling components from material collecting in the bottom of the tower. Y Fractionating tower 2 preferably operates at atmospheric or slightly elevated pressure, for example, in the neighborhood `of 25 pounds per square inch gage.

A plurality of streams are withdrawn from fractionating tower 2, for example, light naphtha may be taken overhead through line 5, heavy naphtha may be taken from a trapout tray in the upper portion of the tower through line 6, gas oil may be taken from a lower positioned trapout tray through line 1 while reduced crude bottoms may be removed by means of line 8. In general the light naphtha may be taken to represent those portions of the crude boiling up to about to 300 F. Heavy naphtha may be taken to represent material boiling from the nal boiling point of the light naphtha up to about 350 to 500 F. Gas oil represents material boiling from the final boiling point of the heavy naphtha up to 650 to '750 F., while the still higher boiling portions of the crude are eliminated as reduced crude bottoms.

If desired, to provide cooling or additional cooling to the upper portion of fractionating tower 2, the light naphtha vapors may be partially or completely condensed in exchanger 9, passed to separator'l from which a portion of the liquid is moved by pump Il through line l2 and valve I3 to fractionating Vtower 2.

Remaining light naphtha may I4 and line I5 to be after be described.

the crude as well as light naphtha may |6 and line I1 to be after be described.

Reduced crude leaving fractionating tower 2 through line 8 is moved by pump |8 to coil I9 in furnace setting 20. Pump I8 raises the pressure of the reduced crude stream to some convenient moderate pressure, for example, 50 to 300 pounds per square inch gage. more or less, while the temperature of this stream is brought up to the neighborhood of 850 to 900 F., more or less, during passage through coil I9 in furnace setting 20. Under the conditions imposed a considerable portion of the reduced crude is viscosity broken, that is, is converted into gas oil with the simultaneous formation minor proportions of gasoline and gas.

Instead of being thermally viscosity broken, the reduced crude may be coked by known means. the liquid products from this operation being processed as will be described in connection with the products from viscosity breaking furnace 20. If coked, the reduced crude may, for example. be heated to a temperature in the range 875 to 925 F., more or less, during passage through coil I9 in furnace setting 20. The heated material is then discharged into one or more of a plurality of coke drums (not shown) where lthe material cokes due to its contained heat. Overhead from the coke drums may be passed to a suitable evaporating tower, for example a tower capable of separating heavy gas oil as bottoms. the overhead passing to fractionator 11. While on stream the coke drums operate at a rather low pressure, for example, 25 to 60 pounds per square inch gage or less. For continuous oberation, a plurality of coke drums is employed, one or more drums being on stream while one or more other drums is being cleaned. Or, if de sired, the reduced crude may be catalytically hydrogenated to render the material more amenable to subsequent treatment, the resulting liquid products from this operation being processed as will be described in connection with the products from visc'sity breaking furnace 20. If hydrogenated, the reduced crude may for example be mixed with a suitable catalyst, for example, tin oxalate or the suldes or oxides of molybdenum or tungsten and a large excess of hydrogen addbe removed through valve disposed of as will herein- Any small amount of gas in any vaporous portions of the be removed through valve disposed of as will hereinmed, the resulting slurry being heated to a temperature of 850 to 950 |9 in furnace setting 20, the pressure being rather high, for example, 1000 to 3000 pounds per square inch gage, more or less. The charge is sent to a reactor (not shown), vapors therefrom being suitably fractionated while bottoms there- F., more or less, in coil from are recycled.

Material from viscosity breaking coil I9 passes through valve 2| and enters fractionator 22 which preferably operates at somewhat lower pressure than coil I9, for exam-ple. at 25 to 75 pounds per square inch gage. Fractionator 22 is -provided with bubble trays 23 or other suitable means to promote liquid-vapor contact. Fractionating tower 22 may be provided with upper disposed cooling means and may lower disposed heating means (not shown) Bottoms from tower 22 leave through line 24 and valve 25 to vacuum asher 26. Vacuum flasher 26 is provided with disc and doughnut trays 21 or other suitable means for promoting of relatively liquid-vapor contact and upper disposed cooling means and lower dis-posed heating means 28 which may take the form of an open steam coil to aid in vaporizing the lighter components of the liquid bottoms in vacuum asher 2li.V Vacuum flasher 26 preferably operates at subatmospheric pressure, for example 0.1 atmosphere, more or les's. Bottoms from vacuum flasher 26 leave through line 29 and are moved by pump 30 to storage. Overhead from vacuumasher 26 leaves through line 3|; is cooled in exchanger 32 and condenser 33 and then passes to separator 34. Liquid from separator 34 leaves through line 35 and is moved by Ipump 36 to line 31, A portion of the liquid passes through valve 38 to the upper portion o cooling therein, the remainder is heated in exchanger 32 and passes through line 39 to fractionator 22. Separator 34 is connected by means of line of 40 to vacuum pump 4| which preferably takes the form of a barometric condenser.

It will be evident that the tar removed through line 29 will Abe very heavy and practically worthless as a source of gasoline. Many other methods may be used to secure the elimination of tar having a very low charging stock value. For example, the lighter and accordingly more valuable tar eliminated through line 24 may, if desired.

be coked by a method similar to that previously described or, if desired, it may be hydrogenated by a method similar to that previously described. Ory if desired, this lighter and accordingly more valuable tar may be Ipropane dea'sphalted. To

accomplish this, the cooled tar is mixed with liqp uid propane and the resulting mixture is heated to precipitate asphalt, the heavy liquid-propane mixture being passed to a suitable fractionating tower. Obviously, if desired, vacuum ashed tar from line 29 may be coked, hydrogenated or propane deasphalted. However, thegasoline Value of this material is so low that such treatment is rarely justified.

Heavy viscosity breaker an intermediate through line 42. 22 leave through line 16 and valve 48 and pass to fractionating tower 11. Fraetionating tower 11 is provided with means to facilitate liquidvapor contact, for example, bubble trays 18, with bottom heating means 19 and upper disposed cooling means. `Gasoline and lighter products leave tower 11 through line 80, are partially condensed in heat exchanger 8| and the products are passed to separator 82. Liquid products are moved from separator 82 by pump 83 and are in part passed through valve 84 and line 85 to the upper part of tower 11 to provide open reflux therein, the remainder passing through line 86 and valve 81 to be disposed of as will hereinafter be explained. Gaseous products leave separator 82 through valve 88 and line 89. The disposition of these will be explained subsequently. Part or all of the liquid in line 86 may be sent through valve |99 if desired for reasons that will hereinafter be explained.

Bottoms from tower 11, comprising light viscosity breaker gas oil, are moved by pump 90 into line 9| where they are of approximately the same boiling range which leaves tower 2 by line 1 and is moved by pump 92 into line 9|. The combined streams pass to point of fractionating tower 22 heated to a temperature of from '150 more or less, preferably 800 to 900 sure being quite moderate, say 50 vacuum flasher 26 to provide` gas oil is drawn from u Overhead products fro-m tower square inch gage or thereabouts. The material leaving coil 93 is passed to a catalytic cracking section.

Catalytic reactors may take several different forms. Among these may be mentioned the following:

1. Single reactors containing a stationary :bed of catalyst.

2. Plural reactors containing a stationary bed of catalyst.

3. Reactors designed for use with moving catalysts. i

4. Reactors designed for use with powdered catalysts.

While for any given set of conditions, one of the above types of reactors is usually preferable to the others, these types are more or less interchangeable. Simply for purposes of Variety and with no intent to limit the description to the particular type selected for any given application, an example of each type of reactor mentioned will be included in the instant description. For the catalytic cracking of the light virgin gas oillight vscosity breaker gas oil mixture, a reactor designed for use with moving catalysts will be described.

The heated and vaporized charge from coil 93 passes to reactor 95 wherein it is contacted with a suitable catalyst. A quite active cracking catalyst is preferably used in reactor 95. A catalyst such as is made by impregnating silica gel with aluminum nitrate or other thermally decomposable aluminum salt and then igniting may be employed. Or, if desired, catalysts such as are described in `my copending applications Serial No. 305,472, filed November 2l, 1939 and Serial No. 300,390, filed October 2l, 1939, now U. S. Patent 2,278,590, may -be employed in reactor 95.

Reactor 95 may take any convenient form. In the gure it is shown as being of similar construction to a taubular boiler or heat exchanger. Catalytic materialis introduced into the top of the reactor through conduit 96, passes downward through the tubes inreactor 95 and is removed from the reactor via conduit 91. If desired, the tubes in reactor 95 may be heated by surrounding them with hot fluid, for example, hot combustion gas from a source later to be revealed, entering through line 98 and leaving by line 99 or vice-versa. Vaporous reaction products leave reactor 95 through line |00.

The descent of the catalyst through the tubes in reactor 95 may be facilitated by means of shakers or other similar devices (not shown). The rate of catalyst addition to and removal from or'all of these may be introduced into line 98 to supply heat to the tubes in reactor 95. Necessary make up air is introduced through valve |06. Regenerated catalyst falls to the bottom of regenerator I0|, .is picked up by conduit 9B and is returned to reactor 95.

For a fuller description and more detailed illustration of reactor-multiple hearth regenerator systems reference may be had to my copending application, Serial No. 277,885, filed June 7, 1939.

Vaporous reaction products from reactor 95 are conducted by line |00 to fractionating tower |01. This tower is provided with bottom heating means |08, means to promote liquid-vapor contact such as bubble trays |09, and with top cooling means. through line ||Il, is cooled in exchanger and passes to separator H2. Liquids are removed from separator I I2 by pump l I3, part are passed through valveA I I4 and line I|5 back to the top of tower |01 to provide cooling therein while the remainder pass through line I I 1 and valve I I6 to reactor 95 is so regulated that the catalyst removed is exhausted or' nearly so. This material is moved through conduit91 to regenerator |0I. The catalyst is moved in conduit 91, as well as in conduit 96, either mechanically or pneumatically, the term pneumatically being employed in its broadest sense. Regenerator IDI preferably takes the form of a multiple hearth furnace, for example, the furnace known in the art 'as the Herreschoi furnace. In its descent through the multiple hearths of the furnace the catalyst is contacted with a rising stream of air or preferably inert gas containing air introduced through line |02. Carbonaceous deposits are burned from the catalyst in regenerator |0| and hot combustion gases leave through line |03 and are reci'rcu` lated by turbine |04. Part of these combustion gases are discharged through valve |05 and part be disposed of as will hereinafter be described. Gaseous products are removed from separator |2 by valve I|8 and line l I9. The treatment of these will be described shortly. Bottoms from tower |01 are removed through line |20 and passed by pump |14 through line |15 to mix with heavy viscosity breaker gas oil introduced through line 42, pump 43 and valve |16, the blend passing to coil 44 in furnace setting 45.

The liquid in coil 44 Vis heated to an elevated temperature. If desired, to aid in the vaporization of this material, a fluid having a lower crit: ical temperature than said heavy viscosity breaker gas oil and substantially unreactive therewith, for example, steam or a gas stream made in the process being described, may be added thereto by means not shown. Also, if desired,l the heated material may be passed through a separator (not shown) to remove any unvaporized components prior to processing. An ordinary separator similar to those well known in the art may be employed wherein the substantially completely vaporized charge is passed to a well insulated drum preferably provided with bales or other suitable deentraining means,

vapors being taken overhead while unvaporizedv material is removed as bottoms. Or, if desired, a centrifugal separator may be used, similar, for

example, to that described in United States Patent 2,192,214. 1n any event, to aid in vaporization, the pressure in coil 44 and in subsequent elements should preferably be as little above atmospheric as is consistent with satisfactory operation. The material leaving coil 44 is passed to a catalytic cracking section.

For the catalytic cracking of the heavy viscosity breaker gas oil-bottoms mixture, a reactor designed for powdered catalyst operation will be described.

The heated material from coil 44 is passed through line 46 and is then mixed with powdered catalyst introduced through line 41. This catalyst preferably comprises a silica-alumina complex` either natural or synthetic, and for reasons that will hereinafter become apparent is in a highly heated state. On mixing with the heated material entering through line 46, said material is immediately brought up to reaction temperature and vaporized. If desired, the powdered catalyst may be slurried into the liquid feed prior to entering coil 44 but generally it is preferable to mix Overhead from tower' |01 leaves 'active (comparatively) catalyst is desirable.

catalyst and feed at the point shown. For the catalytic cracking of this stock a somewhat in- A portion of this stock is high boiling and as it is desirable to operate in the vapor phase or substantially vapor phase a high temperature is required. If the' most active cracking catalysts are employed at the high temperatures required for vaporization, it is difficult to control the reaction so as to avoid considerable secondary decomposition. The low boiling portion of the charge is somewhat refractory but cracks at a satisfactory rate at the high temperatures employed. When such comparatively inactive catalysts are used, operating temperatures in the neighborhood of 950 F. may safely be employed, charging about 1 to 3 pounds of catalyst per pound of oil charged to the unit. Suitable catalysts for the purpose include activated montmorillonitic clays, the commercial materials known as Super Filtrol and Tonsl being particularly useful. Other suitable catalysts, `comprising synthetic silica-alumina complexes have been described in my copending applications, Serial No. 305,473, filed November 21, 1939; Serial No. 313,898, led January 15, 1940, now U. S. Patent 2,323,728, issued July 6, 1943, and Serial No. 317,770, filed February 7, 1940, now U. S. Patentzaonse, issued June 1, 1943. If desired, catalysts described in connection with reactor 95 may be employed here while the preferred catalysts of reactor 49 may be used in reactor 95.

However, best results are obtained if the preferred scheme is followed.

It may be mentioned in passing that powdered catalyst operation offers the most convenient method to accurately control reaction temperature and contact time and accordingly is the most suitable method to employ if a highly active catalyst is used. For the same reason, with an inactive catalyst, a higher temperature may be employed when using the powdered catalyst technique than with any other means for contacting catalyst and charge, without running the risk of secondary decomposition.

The catalyst, suspended in the vaporized charge, passes through reactor 49 which preferably takes the form of an elongated conduit wherein the cracking reaction occurs. The reaction products leave reactor 49 through line 50, following which the gaseous reaction products are separated from the solid, suspended catalyst. This may be accomplished by any suitable known means or any combination thereof, a cyclone separator 5I being shown in the figure. Separated catalyst leaves cyclone separator 5l through line 52 and passes to the regeneration element. Prior to regeneration, the separated catalyst is preferably steamed or otherwise treated to remove any adsorbed or absorbed reaction products therefrom by suitable means not shown. The used catalyst in line 52 is suspended in a stream of air or dilute air introduced through line 53 and the suspension is passed through regenerator 54 which preferably takes the form of an elongated conduit wherein regeneration of the catalyst b'y combustion of carbonaceous residues on the surface thereof occurs. If desired, regenerator 54 may take the form of a pluralityl of regenerators in series with an intel-cooler between each pair in order to better control the heat evolved during regeneration. If desired, reactor 49 and regenerator 54 may each take the form respectively of a plurality of reactors in series and a plurality of regenerators in series, an intercooler being interposed between each pair of regenerators, an interheater being interposed between each pair of reactors. As the catalytic cracking reaction is endcthermic while the regeneration reaction is exothermic, partial reaction products may be reheated in the interheaters by indirect heat exchange with partial regeneration products which are simultaneously cooled. Thus the interheaters on the one hand and the intercoolers on the other may both be combined in the form of indirect heat exchangers.

The regenerated catalyst suspension leaves rgenerator 54 through line 55 following which the gaseous products are separated from the regenerated suspended catalyst by any suitable known `means or any combination thereof, a cyclone separatorv 56 being shown in the figure. Separated catalyst leaves cyclone separator 56 through line 41 for recycling to the cracking zone. Obviously the catalyst is highly heated and a portion of the heat content may be employed to heat and vaporize the charge as previously described. Prior to recycling, the catalyst may be steamed if desired or otherwise treated to remove any adsorbed air from the surface thereof by means not shown. Separated regeneration gas leaves cyclone separator 56 through line 51 and is in part eliminated from the system through valve 58 and is in part recycled by turbine 59 to line 53, necessary makeup air being added through valve 60. Eliminated combustion gas may, if desired, be employed to supply the endothermic heat of reaction to reactor 49 by-indirect heat exchange.

Hydrocarbon reaction products leave cyclone separator 5I through line El and pass to fractionator 62. This tower is Erovided with means to facilitate liquid-Vapor c ntact, for example, bubble trays 63 and is also provided with bottom heating means 6,4 and upper disposed cooling means. The hydrocarbon reaction products are fractionated in tower 62, products heavier than gasoline leaving through line 65 to be further processed as will hereinafter be described, gasoline and lighter products leaving through line 66. Gasoline and lighter products in line 66 are partially condensed in heat exchanger 6l and pass tc separator 68. Liquid products are moved by pump 69 and are in part passed through valve `l0 and line 'Il to the upper portion of tower 62 to provide open reflux therein, the remainder pass ing through valve 12 and line 13 to be utilized as will hereinafter be described. Gas from separator 68 leaves through valve 'I4 and line l5 to be utilized as will hereinafter be described.

If desired, heavy viscosity breaker gas oil catalytic cracking may be eliminated entirely. This is accomplished by closing valve |16 and opening valve |95, the heavy viscosity breaker gas oil passing then to coil I9 via line |96. By this means all heavy viscosity breaker gas oil is ultimately converted into viscosity breaker gasoline, light viscosity breaker gasoil, gas and tar.

If desired, the reducedcrude leaving tower 2 through line 8 may be catalytically viscosity broken. To accomplish this, the reduced crude is heated to a temperature in the range 850 to 925 F., more orless, in coil i9, the pressure being comparatively low, for example, 50 pounds or less per square inch gage. The heated and substantially vaporized charge may or may not then be subjected to a separating step, using any suitable means, for example, a drum separator or a centrifugal separator similar to devices already described Also, if desired, a uid of lower critical temperature than the reduced crude charge and substantially unreactive therewith, for example, steam or gas made in the process, may be added to the reduced crude charge to facilitate the va-` porization thereof. The heated, substantially completely vaporized reduced crude charge is then passed to one or more of a plurality of catalytic reactors (not shown) containing comparatively inactive catalytic material, for example, montmorillonitic argillaceous material, pumice, porous earthenware or the like. Reaction products are passed to a tower (not shown) eliminating heavy 4viscosity breaker gas oil as bottoms, the overhead from said tower passing to fractionator 11. of catalytic reactors is employed, one or more being on stream while the catalytic material in one or more others is being regenerated by procedures known to those skilled in the art and which will be described in somewhat more detail'hereinafter.

To insure continuous operation a plurality I Heavy naphtha is removed from the upper por- 4 tion of fractionating tower 2 through line 6 and is moved by pump |2| to heating coil |22 in furnace setting |22A. If desired, part or all of the viscosity breaker gasoline from tower 11 may be added to the naphtha charged to heating coil |22. This may be accomplished by partially or completely closing valve 81 and partially or completely opening valve |99 in line 200. If it is desired to treat only theheavier portions ofthe viscosity breaker gasoline, line 16 may pass over to tower 2 through line 20| and valve 202 rather than to tower 11, valve 48 being closed. In this way, light viscosity breaker gas oil leaves, Ymixed with light virgin gas oil, through line 1, heavy viscosity breaker gasoline leaves, mixed with heavy virgin naphtha, through line 6 and light viscosity breaker gasoline and light virgin naphtha leave through line 5. By this mode of procedure, obviously tower 11 with all of its auxiliary equipment is unnecessary. Also, if desired, allefyirgin gasoline may be passed to coil |22. To accomplish this, line 6 is omitted and all components in the crude of gasoline boiling range pass overhead from tower 2, the liquid portions thereof being transferred via line |5 to coil |22 by a line not shown. In this modification, the total viscosity breaker gasoline may be processed in conjunction with the total virgin gasoline by the scheme already described.

The naphtha charge is heated to a temperature of from 875 to 1050 F., more or less, preferably to a temperature within the range 925 to 1000o F. The naphtha may be under a pressure of from atmospheric or somewhat above up to a pressure of 200 to 300 pounds per square inch or higher. The heated and vaporized naphtha passes through line |23 and valve |24 to catalytic reactor |25. Preferably, before entering the catalytic reactor, the naphtha is mixed with hydrogen at a rate of, for example, l to 5 moles per mole of naphtha, said hydrogen being introduced, for example, through line |26, this hydrogen being obtained from compressor |8|.

Reactor |25 may take any desired form, for example, the tubular form shown and described with respect to reactor 95. The catalyst in reactor |25 may comprise chromium oxide gel but preferably comprises alumina, especially the variety of aluminum oxide known commercially as Activated Alumina, bearing thereon a relatively minor portion, say 1 to 40%, preferably 5 to 10% of a sixth group metal oxide, particularly chroasada-1s mium oxide or molybdenum oxide'. Vaporous reaction products leave reactor |25 through Valve |21 and travel by line |28 to fractionator |29.

Fractionating tower |29 is provided with bottom heating means |30, means for promoting liquid-vapor contact, for example bubble trays |3|, and top cooling means. Overhead from tower |29 leaves through line |32, is cooled in exchanger |33 and passes to separator |34. Liquid products are removed from separator |34 by pump |35, part passing through valve |36 and line |31 to the top of tower |29 to provide cooling \therein, the remainder passing through line |36 and valve |39 to be further'processed as will hereinafter be described. Gaseous products are removed from separator |34 by valve |40 and line |4|, the further treatment of these being described immediately hereafter. Bottoms from fractionating tower |29 are removed through line |42 and are utilized as described subsequently.

The gas eliminated through line |4| consists essentially of hydrogen but is diluted with more or less gaseous hydrocarbons. If desired, this gas may be subjected to any suitable separation process to give more nearly pure hydrogen. This may be accomplished, for example, by absorbing the greater part of the gaseous hydrocarbons in a suitable liquid. To accomplish this, the gas stream in line |4| may be moved to the lower portion of absorber |43. Absorber |43 is preferably provided with liquid-vapor contact means, for example, bubble trays |44. The ascending gas stream meets a descending stream of absorber oil introduced through line |45 and concentrated hydrogen leaves through line |46. ARich absorber oil is taken from thebottom of absorber |43 by pump |41, is heated in indirect heat exchanger |48 and passes through line |49 to stripper |50. bottom heating means |5| and means for prolmoting liquid-vapor contact, for example, bubble trays |52. Gas comprising predominantly gaseous hydrocarbons is eliminated'through line |53 and valve |54 to be further processed as will be described. Stripped absorber oil is removed from the bottom of stripper by line |55, is moved by pump |56 through indirect heat exchanger |48, cooler |51 and line |45 back to absorber |43. y

Returning 'now to reactor |25: When the catalyst in reactor |25 becomes exhaustedfthe reactor is removed from stream by closing valves |24`.and |21, twin reactor |58 being simultaneously put on stream by opening valves |59 and |60. The catalyst in reactor |25 is then regenerated by burning carbonaceous residues therefrom by introducing air or dilute air through line |6| and valve |62, combustion products being Y taneously opening valves |24 and |21.

removed from reactor |25 via line |64 and valve |63. When the catalyst in reactor |58 is exhausted that in reactor |25 is restored and the functions of the two reactors are then reversed by closing valves |50,y |60, |62 and |63, simul- Exhausted catalyst in reactor |58 is then regenerated by introducing air or dilute air through line |6| and valve |65, removing combustion products through valve |66 and line |64.

It is a characteristic of catalytic conversion processes that the cycle stocks are quite refractory and accordingly are generallyV not suitable for recycling to the same catalytic reactor. Accordingly, bottoms from towers 62 andV |29 are hydrogenated to render them amenable to fur- Stripper |50 is provided withl ther processing. If desired, only bottoms from tower 62, or only bottoms from tower |29 may be so treated.

While various possible combinations for treatment of bottoms have been described it should be pointed out that in general, one of the two systems of working up bottoms is generally followed. In general, bottoms from tower 82 are hydrogenated. Bottoms from tower |29 are small in `quantity and have many uses with little or no further processing. i

Bottoms from tower 82 are removed through line and are moved by pump |61 through valve |68 and line |69 to line |13. bottoms from tower 29 are removed through line |42 andare moved by pump |10 through valve |1| and line |12 to line |13. \Material in line |13 passes through line |11 Aand is moved by pump |18 to furnace |19, the charge passing through elongated conduit |80 disposed in furnace |19. Prior to entering the furnace coil, the charge in line |11 is mixed with hydrogen fed by compressor |8| to line |82.

Heated material from furnace coil |80 passes by line |83 to catalyticreactor |84. Reactor |84 is provided with a suitable hydrogenation catalyst such as an oxide or sulfide of molybdenum or tungsten, a mixture of suldes of molybdenum, zinc and manganeseor any other suitable hydrogenation catalyst. Operating conditions are so adjusted in reactor-1, 84 that hydrogenation rather than destructive hydrogenation is the predominant reaction occurring therein. ln other Words, an attempt is made to convert the refractory tower bottoms to materials of approximately the same boiling range but more amenable to catalytic conversion processes. No attempt is made to convert these tower bottoms into gasoline through destructive hydrogenation although normally a small amount of material in the gasoline range is produced. To accomplish this desired end operating conditions in reactor |84 are relatively mild. The operating pressure is low,

If desired,

for example, in the range 500 to 1500 pounds per square inch and the operating temperature is in the range 850 to 900 F., more or less. About one to ten moles of hydrogen per mole of" charge are employed.

Obviously, destructive hydrogenation may be employed if desired. Many factors however militate against its use. In the rst place, operating conditions must vbe quite severe result- Iing in large equipment and processing costs.

Also, large amounts of hydrogen are consumed and this usually necessitates the construction of a hydrogen producing element which is charged, for example, with gaseous hydrocarbons made in the process.

' Reaction products from tower |84 pass viaI line |85 through cooler |86, through reducing valve |81 to separator |88. Hydrogen and other gaseous products are passed by pump |89 and 4line |90 to absorber |43 for purication as previously described. Liquid products from separator |88 are moved by pump 19| through line |92 to line I. These enter line I-preferably prior to the heating means (not shown) used to preheat the crude charge in line As the catalyst employed in reactor |84` has an extremely long active life only one reactor is shown. When, after many months, the catalyst becomes inactive the unit may be shut down, the catalyst removed from reactor |84 and replaced by fresh material.

If desired, part or all of the bottoms from tower 62 may be removed to storage or otherwise through line |93 and valve |94 while part or all ofthe bottoms from tower |29 may be removed via line |91 and valve |98.

. The various predominantly hydrocarbon gas streams, for example, the gas discharged through valve I6 and line l1, the gas discharged through valve 14 and line 15, the gas discharged through valve 88 and line 89, the gas discharged through valve ||8 and line ||9 and the gas discharged through valve |53 and line |54 or any suitable carbons therein togetherwith lower boiling hydrocarbons.' For example, virgin light naphtha discharged through valve I4 and lline I5, viscosity breaker gasoline discharged through line 86 and valve 81, catalytically cracked gasoline discharged through valve ||6 and line ||1, catalytically cracked gasoline discharged through valve 12 and line 13,and catalytically reformed naphtha discharged through line |38 and valve |39 or any combination of these streams, may be combined and stabilized.

As has been mentioned previously, heavy vis-` cosity breaker gas oil is catalytically converted at temperatures higher than is employed in the catalytic conversion of light gas oil. Cycle stock from the catalytic conversion of light gas oil, while too refractory to be converted at `a satisfactory rate is recycled to the light gas oil catalytic cracking zone, can be further processedV catalytically in a satisfactory manner if sent instead to the heavy viscosity breaker gas oil catalytic conversion zone where higher temperatures prevail. The cycle stock from this last named operation is too refractory for further processing by means of catalytic cracking so it is upgraded through hydrogenation, the necessary hydrogen being obtained asa byproduct from another part of the combination. It is obvious that by means of my invention, a plurality of hydrocarbon fractions is subjected to separate catalytic conversion processes wherein byproducts from some of said separate catalytic conversion processes are introduced into other of said separate catalytic conversion processes whereby a maximum yield of motor fuel of superior antiknock quality is produced and thereby one of the major objects of my invention is accomplished;

I claim:

l. In the conversion of a hydrocarbon mixture of wide boiling range into hydrocarbons boiling within the usual motor fuel range, the` process comprising fractionating said hydrocarbon mixture in a rst fractionating zone to form a plurality of fractions, including a fraction at least the major portion of which boils Within the usual motor fuel range and a fraction at least the major portion of which -boils above the usual motor fuel range; subjecting said higher boiling fraction, in a first catalytic cracking zone and in the presence of a cracking catalyst, to a conversion temperature under catalytic cracking conditions to effect the formation of a high yield of gasoline components; fractionating catalytically cracked products from said first catalytic cracking zone in a second fractionating zone to form a residue and a condensate comprising gasoline; subjecting said residue, in a second catalytic cracking zone and in the presence of a cracking catalyst, toa conversion temperature under catalytic cracking conditions to eect the formation of a high yield of gasoline components; fractionating catalytically cracked products from said second catalytic cracking zone to form a second residue and a fraction comprising gasoline;- blending the lower boiling condensate from said first fractionating zone with hydrogen from a source hereinafter described; subjecting the blend, in

Athe presence of a reforming catalyst, to a conversion temperature under catalytic reforming conditions, to effect the formation of a high yield of aromatics within the usual motor fuel boiling range and hydrogen; separating catalytically reformed products to form a condensate comprising aromatics within the usual'motor fuel boiling range and a gas comprising hydrogen; recycling a portion of said hydrogen to the catalytic reforming zone; subjecting the second residue, in the presence of a hydrogenating catalyst and a portion of said hydrogen, to a conversion temperature under hydrogenating conditions to effect the upgrading of said second residue and passing upgraded second residue to the first fractionating zone.

2. In the conversion of a hydrocarbon mixture of Wid'e boiling range into hydrocarbons boiling within the usual motor fuel range, the process comprising fractionating said hydrocarbon mixture in a rst fractionating zone to form a plurality of fractions, including a fraction of the nature of heavy naphtha and a fraction at least the major portion of which boils above the usual motor fuel range; subjecting said higher boiling fraction, in a first catalytic cracking zone and in the presence of a cracking catalyst, to a conversion temperature under catalytic cracking conditions to effect the formation of a high yield of gasoline components; fractionating catalytically cracked products from said rst catalytic cracking zone to form a residue and a condensate comprising gasoline; subjecting said residue,

in a second catalytic cracking zone and in the presence of a cracking catalyst, to a conversion temperature under catalytic cracking conditions to effect the formation of a high yield of gasoline components; fractionating catalytically cracked products from said second catalytic cracking zone in a third fractionating zone to form a second residue and a condensate comprising gasoline; blending the fraction of the nature of heavy naphtha from said first fractionating zone with hydrogen from a source hereinafter described; subjecting the blend, in the presence of a reforming catalyst, to a conversion temperagraded second residue to the first fractionating Zone.

3. In the conversion of a hydrocarbon mixture of wide boiling range into hydrocarbons boiling within the usual motor fuel range, the process comprising fractionating said hydrocarbon mixture in a first fractionating zone to form a residue and a plurality of condensatesincluding a condensate at least the major portion of which boils above the usualmotor fuel range and a condensate at least the major portion of which boils within the usual motor fuel range; subjecting said residue to a decomposition temperature to effect the formation of a high yield of light gas oil components and a loW yield of gasoline components; fractionating the resulting lproducts in a,second fractionating zone to form a plurality of condensates comprising said light gas oil components and said gasoline components; blending the higher boiling condensate from the first fractionating zone and said light gas oil components; subjecting the blend, in a first catalytic cracking zone and in the presence of a cracking catalyst, to a conversion temperature under catalytic cracking conditions to effect the formation of a high yield of'gasoline components; fractionating catalytically cracked products from said first catalytic cracking zone in a third fractionating zone to form a second residue and a condensate comprising gasoline; subjecting said second residue, in a second catalytic cracking Zone and in the presence of a cracking catalyst, to a conversion temperature under catalytic cracking conditions to effect the formation of a high yield of gasoline components; fractionating catalytically cracked products from said second catalytic cracking Zone in a fourth fractionating Zone to form a third residue and a condensate comprising gasoline; blending the lower boiling condensate from said first fractionating zone with hydrogen from a source hereinafter described; subjecting the blend, in the presence of a reforming catalyst, to a conversion temperature under catalytic reforming conditions to effect the formation of a high yield of aromatics within the usual motor fuel boiling range and hydrogen;- separating catalytically reformed products to form a condensate comprising aromatics within the usual motor fuel boiling range and a gas comprising hydrogen; recycling a portion of said hydrogen to the catalytic 'reforming zone; subjecting the third residue, in the presence of a hydrogenating catalyst and a portion of said hydrogen, to a conversion temperature under hydrogenating conditions to effect the upgrading of said third resi-due and passing upgraded third residue to the first fractionating zone.

4. The process in accordance with claim 3, further characterized by the fact that gasoline components from the second fractionating zone are catalytically reformed in admixture with the lower boiling condensate from the first fractionating zone.

5. The process in accordance with claim 3, further characterized by the fact that gasoline components from the second fractionating zone are separated into light naphtha and heavy naphtha and said heavy naphtha is catalytically reformed in admixture with the lower boiling condensate from the first fractionating zone. 6. In the conversion of a hydrocarbon mixture of wide boiling range into hydrocarbons boiling within the usual motor fuel range, the process comprising fractionating said hydrocargasoline components;l fractionating the resulting products in a second fractionating zone to form va plurality of condensates comprising said light gas oil components and said gasoline components; blending the gas oil condensate from the rst fractionating zone and said light gas oil components; subjecting the blend, in a first catalytic cracking zone and in the presence of al cracking catalyst, to a conversion temperature under catalytic cracking conditions to effect the formation of a high yield of gasoline components;,fractionating catalytically cracked prod- 4 ucts from said first catalytic cracking zone in a third fractionating zone to form a second resi` due and a condensate comprising gasoline; subjecting said second residue, in a second catalytic cracking zone and in the presence of a cracking catalyst, to a conver'sion temperature under catalytic cracking conditions to effect the formation of. a high yield of gasoline components; fractionating catalytically cracked products from said .second catalytic cracking zone in a fourth fractionating zone to form a third residue and a condensate comprising gasoline; blending the heavy naphtha from said first fractionating zone with hydrogen from a source hereinafter described; subjecting the blend, in the presence of a reforming catalyst, to a conversion temperature under catalytic reforming conditions to effect the formation of a high yield of aromatics within the usual motor fuel boiling range and hydrogen; separating catalytically reform-ed products to form a liquid comprising aromatics within the usual motor` fuel boiling range and a gas corn-` prising hydrogen; recycling'a portion of said hydrogen to the catalytic reforming zone; subjecting the third residue, in the presence of a hydrogenating catalyst and a portion of said hydrogen, to a conversion temperature under hydrogenating conditions to effect the upgrading of said third residue and passing upgraded third residu-e to the first fractionating zone.

'l` The process in accordance with claim 6, further characterized by the fact that gasoline components from `the second fractionating zone are catalytically reformed in admixture with the heavy naphtha from the first fractionating zone.

8. The process in accordance with claim 6, further characterized by the fact that gasoline components from the second fractionating zone are separated into light naphtha and heavy naphtha and said heavy naphtha is catalytically reformed in admixture with heavy naphtha from the first fractionating zone.

9. In the conversion of a hydrocarbon mixture of wide boiling range into hydrocarbons boiling within the usual motor fuel range, the process comprising fractionating said hydrocarbon mixture in a first fractionating zone to form a residue and a plurality of condensates including a condensate at least the major portion of which boils above the usual motor fuel range and a condensate at least the major portion boils within the usual motor fuel range; subjecting said residue to a decomposition temperature to effect the formation of a high yield of gas oil `components and a low yield of gasoline cornof fractions comprising heavy gas oil, light gas oil and gasoline; blending the higher boiling condensate from the first fractionating zone with said light gas oil; subjecting the resulting blend,

in a first catalytic cracking zone and in the` presence of a cracking catalyst, to a conversion temperature under catalytic cracking conditions to effect the formation of 'a high yield of gasoline components; fractionating catalytically cracked products from said first catalytic cracking zone in a third fractionating zone to form a second residue and a condensate comprising gasoline; blending said second residue with heavy gas oil from said secondfractionating zone; subjecting the blend, in a second catalytic cracking zone and in the presence of a cracking catalyst, to a conversion temperature under catalytic cracking conditions to effect the formation of a high yield of gasoline components; fractionating catalytically cracked products from said second catalytic cracking zone in a fourth fractionating zone to form a third residue and a condensate comprising gasoline; blending the lower boiling condensate from said first fractionating zone with hydrogen from a source hereinafter described; subjecting the blend, in the presence of a reforming catalyst, to a conversion temperature under catalytic reforming conditions to effect the formation of a high yield of aromatics within the usual motor fuel boiling rang-e and hydrogen; separating catalytically reformed products to form a liquid comprising aromatics Within the usual motor fuel boiling range. and a gas comprising hydrogen; recycling a portion of said hydrogen to the catalytic reforming zone; subjecting the third residue, in the presence of a hydrogenation catalyst and a portion of said hydrogen, to a conversion temperature under Vhydrogenating conditions to effect the upgrading of said third residue and passing upgraded third residue to the first fractionating zone.

10. The process in accordance with claim 9, further characterized by the fact that gasoline from the second fractionating zone is catalytically reformed in admixture with the lower boiling condensate from the first fractionating zone.

1l. The process in accordance with claim 9, further characterized by the fact that gasoline from the second fractionating zone is separated into light naphtha and heavy naphtha and said heavy naphtha is catalytically reformed in ad- `mixture with the lower boiling condensate from the first fractionating zone.

l2. I n the conversion of a hydrocarbon mixture of wide boiling range into hydrocarbons boiling within the usual motor fuel range, the process comprising fractionating said hydrocarbon mixture in a first fractionating zone to form a residue -and a plurality of condensates comprising gas oil,

heavy naphtha and light naphtha; subjecting said residue to a decomposition temperature` to effect the formation of a high yield of gas oil components and a low yield of gasoline components; fractionating the resulting products in a second fractionating zone to form a plurality of fractions comprising heavy gas oil, light gas oil and gasoline; blending the gas oil from the first fractionating zone with said light gas oil; subjecting the resulting blend, in a first catalytic cracking zone and in the presence of a cracking catalyst, to a conversion temperature under catalytic cracking conditions to effect the formation of a high yield of gasoline components; fractionating catalytically cracked products from said rst catalytic,

form a second residue and a condensate comprising gasoline; blending said second residue with said heavy gas oil from the second fractionating zone; subjecting the blend, in a second catalytic cracking zone and in the presence of a cracking catalyst, to a conversion temperature under catalytic cracking conditions to effect the formation of a high yield of gasoline components; fractionating catalytically cracked products from s aid second catalytic cracking zone in a fourth fractionating zone to form a third residue and a condensate comprising gasoline; blending the heavy naphtha from the first fractionating zone with hydrogen from a source hereinafter described; subjecting the blend, in the presence of a reforming catalyst, to a conversion temperature under catalytic reforming conditions to effect the formation of a high yield of aromatics within the usual motor fuel boiling range and hydrogen; separating catalytically reformed products to form a liquid comprlsing aromatcs within the usual motor fuel boiling range and aggas comprising hydrogen:

recycling a portion of said hydrogen to the catalytic reforming zone; subjecting the third residue, in the presence of a hydrogenating catalyst and a portion of said hydrogen, to a conversion temperature under hydrogenating conditions to effect the upgrading of said third residue and passing upgraded third residue to the first fractionating zone.

13. The process in accordance with claim l2, further characterized by the fact that gasoline from the second fractionating zone is catalytically reformed in admixture with the heavy naphtha from the first fractionating zone.

14. The process in accordance with claim l2. further characterized by the fact that gasoline from the second fractionating zone is separated into light naphtha and heavy naphtha and, said heavy naphtha is catalytically reformed in admixture with the heavy naphtha from the rst fractionating zone.

ROBERT F. RUTHRUFF.

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