CA1259579A - Method and apparatus for cracking residual oils - Google Patents

Abstract

Abstract A process is described for converting residual oil with fluid catalyst particles which comprises passing an upflowing suspension of fluid catalyst particles at an elevated temperature upwardly through a riser reaction zone; atomizing a residual oil feed to be converted to a particle size commensurate with the particle size of the catalyst particles in the upflowing suspension; discharg-ing the atomized residual oil at a velocity in excess of 300 ft./sec. for contact with said upflowing catalyst particle suspension; maintaining the temperature of contact between said catalyst particles and said atomized residual oil feed suspension sufficiently elevated to obtain up to 50 percent thermal conversion of the atomized oil feed and catalytic conversion thereof by an order of magnitude greater than obtainable with a less atomized oil feed; and separating the suspension vaporous products of the previous step from catalyst particles in a time frame less than two seconds.

Description

1;2~;9579 ME~THOD AND APPAR~TUS FOR CR~CKING
RESIDUAL _OILS

The prior art identifies residual oils as residual, reduced crude oils, atmospheric tower bottoms, topped crudes, vaccuum resids, or simply heavy oils. Such high boiling portions of crude oils are also known as comprising very refractory compo-nents, such as polycyclic aromatics and asphaltenes, which are considered difficult to catalytically crack to form high yields of gasoline plus lower and higher boiling hydrocarbon fractions because of the deposition of large amounts of coke on the cata-lyst. ~urthermore, metal contaminants in the heavy oil fractions of crude oil comprising vanadium, nickel, copper, iron, etc. are deposited on and/or in the pores of the catalyst, thereby further poisoning and/or inactivating the catalyst so employed. Indeed the prior art considers that the effect of the coking tendencies of the heavy oil fractions plus the heavy metals effect are so overpowering that the resulting product yield structures are unacceptable in terms of industry economics.

In view of prior art identified problems for processing heavy crudes and bottom fractions thereof, comprising such contaminants, it has been previously proposed to effect a separation of materials comprising the residual or heaviest fractions or to effect a preconversion of the heaviest and undesirable components. Differ-ent techniques to accomplish the desired separ~'ion, such as .

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vacuum ~ist~llatic~n, solvent extraction, hydr~genation or certain thermal cracking process, have been relied upon in the prior art fo- contaminant separation or control. Adsorption of undesired components, particularly me,al components, on particulate mate~ial of little or no cracking activity has also been employed. Thermal cracking, such as delayed and fluid coking, as well as visbreak-ing operations, have been employed to upgrade heavy residual oils, however, the resultant products boiling above 400 F have not proven to be particularly good feed stocks for fluid catalytic cracking due to resultant high concentrations of polynuclear com-pounds Residual oil comprlsing relatively high bolling fractions of crude oil obtained as atmospheric tower bottoms and/or vacuum tower bottoms contained theFein are, therefore, regarded as distress stocks by the petroleum industry because the o1ls contain large quantities of components generally considered to have coke form-ing tendencies as well as heavy metal components For example, a residual oil may contain a carbon residue in e~cess of 0.6% by weight, and thls characteristic is considered by the industry to contribute to producing high additive coke in a c:racking opera-tion and along with the high metals levels will operate to rapidly deactivate the cracking catalyst, leading to uneconomic yield results. Hence, the prior art has tended to exclude these materials from fluid cracking feeds.

Residual oils for the purpose of this invention can include materials boiling from 400F to the finai end point of c-ude oil, in excess of 1800P. Con~ained in this broad:boiling range feed stock caL be light gas oils boiling from about 400F to 700F, medium gas oils boiling from abo~t 600CP to 850F, heavy gas oils boilinc from abou, 60C~ to i200~'~, and components boiling bevond S7~

1200CF up to ~he inal b1_1ins point o the c-ud~ oil, including carbon producirlg componen+s such as polyeycl c aromatics, aspha~-tenes and metal contaminants, as well as whole crudes. Separately prepared stocks such as those prepared by solvent ext--ac-ion of hydrogenated stocks may also be included as feed to the process The Invention This invention relates to the simultaneous conversion of both the high and low boiling components contained in residual oilc with high selectivity to gasoline and lighter components and with low coke production. The past problems related to high regener-ator and catalyst temperatures are substantially obviated by the processing concepts of the invention. Indeed this invention encourages high catalyst regeneration temperatures and takes advantage of these high temperatures of the catalvst to cause the d~sired cracking reactions to occur, at high conversion ar.d high selectivity to gasoline and products which are gasoline precurso~s on a once through basis, without excessive coke formation. Fluid catalytic cracking is successfully practiced with feed stocks derived by distillation, solvent extraction and by hydrogenation, up to distillation ranges capable of instantaneous vaporization by hot regenerated catalyst. Experime~ts with cracking of the high boiling residual'hydrocarbon components have met with less than desired results due to substantial measure to the fact that the prior experimentors were considerably constrained and failed to appreciate that success is only possible i~ substantiallv instantaneous and complete atomization/vaporization is achieved by the initial contact of the heavy oil feec w_th very hot catalyst particles at a temperature above the pseudocritica' temperature of the residual oil feed. This means that as the boiling range of a gas oii feea is increased by inclusion of 5t79 residua, ~he catalyst temperature must also be increased. The prior art has not only failed to recognize this conce?t, and thus ignored these facts, but has deliberately restrained the process from achieving the necessary high catalyst temperature due to two factors.

(1) metallurgical limits of the regeneration equipment, and

(2) Thermal stability of the catalyst Current available fluid cracking art tends to agree that the maximum prac~ical temperature of regeneration and, therefore, the resultins regenerated catalyst temperature should be restricted to within the range of about 1300F - 1400F even though temper-atures up to 1500 and 1600F are broadly recited. The temperature restriction of 1300F - 1400 ~ in reality necessarily restricts therefore the oil feeds charged to catalytic crackers, to distilled, sclvent extracted and hydrogenated sas oil stocks separated from resldua boiling above 1025 F in order to achieve desired conver-sion levels The present invention deals with provid ng an arrangement of apparatus or equipment and techniques of using, which will permit among other things extending the temperatuxe of catalyst regener~-tion up to at least 1800F without unduly thermally impairing catalyst activity. The invention also identifies an array of equipment or apparatus means capable of withstanding the severe temperature operations contemplated by the invention.

Thus, for example, the undistilled portion of crude oil boiling from about 400F or higher, up to the crude oil end point such as prc~ided by topped crude oils can be cr~cked under co-d,tions ~sss~s~
achieving high conversions OL the oil feed to form lower boiling materials including gasoline and lighter hydrocarbons with gasoline yield results comparable to prior art gas oil cracking including comparable coke makes. The need for expensive feed clean up or preparation techniques and apparatu~ in the form of distillation, solvent extraction~ hydrogenation or various thermal processes i6 thUB obviated.

The present invention therefore relates to a method for converting residual oil with fluid catalyst particles which comprises:
(a) passing an upflowing suspension of fluid catalyst particles at an elevated temperature upwardly through a riser reaction zone;
(b) atomizing a residual oil feed to be converted to a droplet size commensurate with or smaller than the particle size of the catalyst particles in the upflowing suspension;
(c) discharging the atomized residual oil at a velocity in excess of 300 ft./sec. for contact with the upflowing catalyst particle suspension initially at a temperature at least equal to or above the residual oil feed pseudo critical temperature;
(d) maintaining the temperature of contact between the catalyst particles and the atomized residual oil fe~d suspension sufficiently elevated to obtain thermal conversion of the atomized oil feed and catalytic conversion thereof to produce vaporous products; and (e) separating the suspension vaporous products of step td) from catalyst particles following transverse of the riser zone in a time frame less than about 2 seconds.

The invention still further relates to a method for converting a residual portion of crude oil with high temperature fluid catalyst particles which comprises:

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(a) flowing a suspension of high temperature fluid catalyst particles upwardly through a riser conversion ~one;
(b) atomizing a resiaual oil feed to be converted to a droplet si~e commensurate with or smaller than the high temperature suspended catalyst particles of a size in the range of 20 to 200 microns;
(c) chargin~ the atomized residual oil of step (b) at a velocity in the range of 300 to 1300 ft./sec. into contact with the upwardly flowing hot catalyst particle suspension initially at a temperature at least equal to or above the residual oil feed pseudo-critical temperature;
(d) providing the temperature of contact between the catalyst particles and the atomized residual oil feed initially sufficiently elevated to shatter asphalt component in the residual oil and obtain up to 50 percent thermal conversion of the atomized oil feed, effecting catalytic conversion of oil vapors formed in the flowing suspension thereby reducing the temperature of the suspension; and (e) separating vaporous hydrocarbon conversion products of step (d) from catalyst particlas following transver6e of the riser zone in a time frame less than about 2 seconds.

The products produced from the proaeas o~ the invention ~ill be similar to those derived from the more conventional relatively clean gas oil fluid catalytic cracking operations. That is, C2's and lighter gases, C3 and C4 olefins, and paraffins, gasoline boiling from C5's to 430-F end point and cracked light and heavy cycle oils are obtained. The cracked cycle oils or gas oils thus obtained and known as light and heavy cycle oils or decanted oil are of such a quality that they can be hydrogenated for sale as low sulphur fue]. oils, mildly hydrogenated and returned to the fluid catalytic cracker for more complete conversion to gasoline or preferably some or all may be hydrocracked more completely to produce gasoline boiling components.

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Hydrocracking of the cracked cycle oils obtained as herein described to form gasoline coupled with alkylation of the catalytic C3's and C4's results in yields of gasoline per barrel of 400-F ~ crude oil residuum charged to the catalytic cracker of up to 125% plus 3-4% propane. Such an overall processing sequence is in energy balance if not a net exporter of fuel gas and steam to other applications. The energy balance includes that required for crude oil topping operation.

A most important parameter for successEul residual oil cracking -5b-7<3 is to bt~ sure that a most complete intimate ~lash vaporization con~act betwe~n -luid catalyst particles and heavy oil feed is achieved. That is providing substantially complete atomi~ation/
vapori~ation of particularly the high molecular weight components of the feed substantially upon contact with the hot catalyst particles improves 'he conversion operation. The residual higher boiling portion of 'he feed a-long with the lower boiling gas oil portion is encouraged to be substantially completely vaporized upon contact with the hot regenerated catalyst at a temperature above the feed pseudo-critical temperature because only by more completely achieving the atornized vaporlzation of the feed compo-nents can more of the feed be more completely cracked to gaso-line yielding components. What does not vaporize remains essen-tially unconverted resulting in considerable yields of catalytic cycle oils and/or is adsorbed on the hot catalyst surface and tends to be converted particularly to coke, thereby resulting in a loss of gasoline yield and a rapid lowering of catalyst activity.
For achieving optimum desired conversion, the mix temperature betwee~ oil feed and catalyst should be at least equal to and preferably above the pseudo-critical temperature of the residual oil feed charge~ b~t not so much higher that undesired over-cracking occurs.

The feed preheat temperature, the tempera.ure of the hot regen-erated catalyst particles, the catalyst cracking activity, the volume of diluent such as steam injectea with the feed, the hydrocarbon vapor residence time in contact with catalyst and the unit operating pressure re main operatins variables readily available to the petroleum refiner to achieve the reaction conditions necessary to accomplish sub~tantially complete vapo_i-S7~
zation of the feed and, iri turn, achie~e a hiqh selec-ivily con~ersion to gasoline and lighter hydrocarbons ir. com~ir,ation with the production of heavier cycle oils of a Guality suitable for hydroqenating or hydrocracking to form additional gasoline boiling range material.

An additional desired opera'ing parameter is that of providing an equilibrium temperature in the riser cross-section, sub-stantially instantaneously with well designed and arranged feed injection nozzles. A feed exit velocity at the outlet in the range of 10 to 1300 feet per second and preferably from 300 to 500 or more feet/second is particularly desired, with the feed nozzle outlet arranged with respect to the riser cross-section to spray at least equal area circles of the riser cross-section.
Each feed nozzle may or may not be steam jacketed as desired to reduce any potential coking of the hydrocarbon feed charged through the barrel of the nozzle. A substantial amount of dilue~t, up to about 7 weight percent of steam or o~her suita~le diluent material is also injected wlth the residual oil feed ~o reduce t~e equilibrium flash temperature thereo~ and to provide the best achievable oil atomizing effect with a given nozzle design. Typi-cal oil feed dispersion steam or diluent rates range from 1 to 15 weight percent on feed.

, The above identified facto-s relating to the con_acting and mixins i of the atomized oil feed with fluid catalyst particles are intended to accelerate a mixture thereor relatively uniformly and rapidl~-through the riser vaporiza-lon zone in a minimum time frame and thus provide minimum if any catalyst slippase thereby enhancing 1 rapid heat transfer from the hot catalyst to the heavy atomi.zed oil fee~ and prevent localized enrlanced catalyst to oil ratios ~2~i~3S79 represen~ati~re of dense cataiyst phase conditions. That is, con-ditions are se;ected to ensure dilute phase contact between catal~st and oil feed in the riser vaporization sec~ion and down steam portions thereof as opposed to localized dense phase contact conditicns within the riser.

Typically, a reduced crude heavy oil feed contains from 10 to 12% hydrogen in its molecular structure. The lighter fractions are generally richer in hydrogen than the heavier fractions.
Generally the heavier and larger molecular structures are con-sidered hydrogen deficient~ The lighter, hydrogen rich fractions are relatively thermostable but are relatively easily catalyti-cally cracked with special catalvst compositions such as zeolite containing catalysts. The heavier high molecular weight or hydrogen deficient fractions of the oil feed are viewed as thermo-unstable and readily thermocracked on contact with solids at temperatures in the range of from 1000-18~0~. Indeed the instantaneous and complete vaporization of the heavy fractions, discussed above, encourages simultaneous thermocracking of the high molecular weight components including some asphaltenes lead-ing to the ultimate successful conversion of more of the total residual oil feed to high gasoline and cycle oil yiel~s with low coke and gas make. Achieving complete atomization/vapori-zation of the heavy components of residual oil feed substantially instantaneously upon contact with the fluid catalyst particles thxough the-mechanisms of sufficiently high catalyst temperature, low bydrocarbon partial pressure plus the use of an atomizing oil feed nozzle injection system is relied upon to prevent localized dense phase cracki~g and thus encourages the desired thermocrack-ing of some of the large asphaltene type structures to form lower boiling cycle oi;s at the expense of pro~ucins coke.

l~S9579 Failure to acco~21ish the above will lead t~ the phenomenon o~
"coke shut-off". This is a phenomenon where heavy hydrogen defi-cient molecules are deposite~ and block the pores to active cracking sites of the catalyst rendering the catalyst relatively ineffective in terms of a lengthy active life for producing high conversions of the heavy oil feed to desired products from either the light and/or heavy components of the feed.

In the design and operation of a unit of the type contemplated and described by this invention, a basic consideration essential to the operation is that the temperature of the fluid catalyst regeneration operation must be essentially carbon burning unre-strained at least up to achieving a temperature of about 1800F.
While the factors associated with feed preheat temperature, riser temperature, hydrocarbon p~rtial pressure, and the method of feed nozzle injection and distribution are important, they each are restrained by practical limitations and once each is optimized with respect to their practical limitation one must recognize the fact that the temperature of the catalyst regenerator must be unrestrained with respect to carbon burning so that the temper-ature can be allowed to rise to a level which suit the needs of a particular heavy oil feed stock composition to achieve the here-in desired instantaneous atomized-vaporization contact with cata-lys. particles promoting catalytic cracking and simultaneous thermocracking of tne large, less stable molecular structures in the feed.

Table 1 shows the effect on gasoline and coke make when cracking a partlcular atmospheric resid without a regeneration tempera-ture restraint compared to cracking with the regenerator restrain-eQ with respect to temperature. These operations are compa-ed 12~'~357S~
to -racking 2 sas oil obtained from the sam~ crude oil following vacuum reductior~ to remove asphhl.ie type components and cra-k-ing the resultant gas oil under prior art conditions Table 1 shows that as the regenerator or catalyst temperature is restrained in a resid cracking operation gasoline yield decreases significantly and coke make increases rather corres-pondingly. It should also be noted that residua can be cracked to higher gasoline yields and at similar coke makes as obtained with a conventional gas oil feed stock.

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Table ~ emphasizes the same factors wherein gas oil cracking data is shown compared to 10 volume percent and 20 volume percent vacuum residua added to the same gas oil feed. This tabulation demonstrates that the presence of the residua under optimized conditions results in higher overall conversions, higher gasoline yields and equal if not slightly lower coke makes than conven-tional gas oil cracking.

Table 1 . . ~
Effect of Restraining Regenerator Temperature and Comparison of Atmospheric Bottoms With Gas O l Only ~eed ~ .. . . .. .
Atmospheric Bottoms Gas-Oil Onlv Regenerator Temp: High Low Conventional Gasoline Yield Vo. %: 67.7 63.5 61.~

Coke Wt. %. ~.3 8.0 6.1 .
.. : ..

~25~5~9 Table 2 Gas Oil Crackin Present Art ~7ersus Resid Crackin ~ q ~ _ g. ____ .__ Mild Conversion Operation _ _ _ Gas oil ~ Gas Oil ~
Gas Oil10% Resid 2i~% Resid .. ..
Conversion Vol. ~O fi6.~ 71.0 79.0 Gaso Yield Vo. % ~9~ 61 8 66.1 Coke Wt. % 3.0 3.6 5.6 Optimum Conversion ~peration _ _ Conversion Vol. % 76.5 77 79.~
Gaso. Yie~d Vol. % 61.5 67.4 67.7 Coke Wt. % 6.1 4.3 5.3 Analyses of the products produced when cracking full atmospheric bottoms compared to sas oils only from the same crude oil show cert~in other interesting properties;
(1) Liquid products proauced have higher average hydrogen contents.
(2) The researc~. octane of the gasolin~s is signifi-cantly higher.

(3) The motor octane of the gasolines is significantly higher resulting in a much improved (R~M)/2 rating important in unleaded gasoline production.

[4) The cracked gas oil products commonly referred to as light and heavy cycle oils and decantea oil - are substantially richer in di anc tri condensed aromatics in p-eference to 4, ~ and 6 condensed aromatic rings. The high concentration of two - and three member condensed aromatics in the cracked prod~ct makes these stocks highly desi-able ~2~9~79 feeds or hydrucrac};ing to gasoline.

(5) The coke produced u~der optim~m op~rating condi-tions is very low in hydrogen content~ Hydrogen levels in the 3-6 weight percent range are o~served versus &-10 weight percent obtained in prior art gas oil cracking operations. The lower hydrogen level of the coke produced is only explainabl~ by the fact that the operating conditions employe~ encourages polymerization of polycyclics attracted to the catalyst surface, thereby releasing significant amounts of additional hydrogen for utilization in hydrogen transfer reactions in or~er to obtain the observed higher hydrogen content of the liquid products. This phenomenon is not observed in the present day gas oil cracking.
These reactions are exothermic and hence signifi-cantly ofset the endothermic heat of reaction of the primary cracking reaction. As a result the overall heat of reaction may be reduced as much as 40 to S0/0.
This contrib~ltes to lower catalyst circulation rates and conse~uently lower coke m~kes. The low hydrogen level in the coke is also a major factor of consider-- ation when catalyst regeneration is conducted in the m~nner embodied in this invention.

A highly siliceous catalyst comprising one of alumina or magnesia with or without a catalytically a~tive crystalline aluminosilica+e or crystalline zeolite and of a fluid_zable p~rticle size pre-ferably in the range of about 20 to about 200 micron size may vary considerably in cracking activity and levels o~ metal contam-inants accumulated in the cracking operatior.. If the ~uild up ~2~3S79 of the metals on the catalyst p~ecludec maintaining a desired conversion level, ~t is contemplated employing a continuous or semi-continuous catalyst make up and removal or disp~sal of contaminated catalyst to maintain desired cracking activity aside from regeneration of the catalyst. The catalyst inven.ory may also be substantially completely or partially replaced as required at turn-around conditions, after an extended period of operation or in response tD a change in feed composition as is most con-venient to the operation tc achieve desired conversion of the feed.

Metals poisoning has long been recognized as a major obstacle to resid cracking. It has been found, however, that these melal contaminants can be passivated to some considerable extent at a high regenerator temperature and their adverse effects markedly reduced when the coke on recycled catalyst is maintained below about 0.05 weight percent. It has been found that about 5%
conversion is lost per 0.1 weight percent coke on regenerated catalyst in addition to the e~pected coke deacti~ation, because of metals contamination. However, in the reduced crude cracking operation of this invention metals like nickel, vanadium and iron, show some beneficial properties such as activating or enhancing dehydrogenation, hydrogen transfer reaction, and promote Co combustior. in the regenerator to achieve a lower coke on recycled catalyst without any need for an outside promoter.
~n the othe_ hand, sodium and all al~aline metals are still regarded as severe contaminants for par~icularly a zeblite containing catalyst. Th~s, it has been found that feed desalt-ing is a more economical approach to sol~ing the sodium problem than using "soda sink" scavengers. With proper desal~ing of the feed, sodium therein can be controlled well below 1 PPM~

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Catalvs~ Re~eneration _ .

In oraer to achieve the desired high catalyc, =em~e~atures re-quired to properly effect succersful cracking Gf oils compris-ing residual oils, special regeneration techniq~es are required along with specially designed and employed apparatus cr oper-ating equipment. The high temperatuxe cracking technique of the invention encouraaes relative high levels of coke or hydrocar-bonaceous material to be deposited on the catalyst during its exposure to the oil feed. Levels not normally below 1 weight percent and in some instances over 2 weight percent will occur It is particularly desirable, however, to regenerate the cata-lyst to carbon levels below 0.10 weight percent desirably to at least 0.05 and more preferably to about 0.02 weight percent Regeneration techniques and apparatus or eguipment employed in present day cracking of gas oils are unsuitable for achieving the severity of catalyst regeneration required in residual oil cracking for the following reasons:

(1) The high coke levels permitted to build on the catalyst are encouraged by low catalyst circula-tion rates, that is, by low catalyst to oil ratios.
The combination of :Low catalyst to oil ratios and hlgh carbon levels leads automatically to high regeneration temperatures. ~emperatures tha. are in excess of the normal limits placed upon the stainless steel employed in present day regener-ators, in the design of cyclone systems and cata'yst withdrawaL systems, etc. Also the temperatures contemplated are beyond the current temperature limits of present day power recovery systems of about 1400F.

~2S95~9 (2) The ~.igh activity catalysts presently empioyed in catalytic cracking are not structurally thermo-stable at the high regenerator temperatures of the invention if this severe regenerati~n is con-ducted in a single stage or even in a multi-stage regenerator where the multi-stages are contained in a single vessel. Two very basic factors effect the catalyst stability during regeneration. At higher and higher coke levels on the spent catalysts, higher and higher catalyst particulate temperatures are developed as the high level of coke is burned in a single vessel even if multi-stage single vessel regeneration is employed.
These high surface temperatures themselves will render the catalyst ineffective. Secondly, the catalyst deactivates rapidly at high temperatures when the steam formed during coke com~ustion from associated molecular hydrogen is allowed to remain in contact with the catalyst when the catalyst reàches its highest temperature.

A particular embodlment of this inventior is to conduct the regen-~eration of the spent catalyst in a two vessel system, comprising of two stage sequential catalyst flow system designed and oper-ated in such a particular manner that the prior art catalyst regeneration difficulties are w ercome. The catalyst regenera-tion arrangement of this invention achieves a coke on recycled catalyst level prefera~ly less than 0.02 weight percent withoat exceeding undesired metallurg~ical limitation or catalyst thermo-stability.

~2S95~3 .he ca alytic cracking process o, this invention relates to the cracking of high b~iling hydrocarbons generally refexred to as residual oils and boiling initially at least 400F or highe_ obtained from crude oil shale oil and tar sands to prod~ce gasoline lower and higher boiling hydrocarbon components. The residual oil feed is mixed in a rlser reaction zone with a highly active cracking catalyst recovered from a regeneration zone at a temperature preferably above the feed pseudo-critical temperat~re.
The hydrocarbon feed at a temperature above about 400F is mixed with hot regenerated catalyst at a temperature at least'equal to the feed pseudo-critical temperature under conditions to form a high atomized and generally vaporous hydrocarbon-catalyst s~spen-sion; A suspension separation device or a-rangement employed at the riser discharge separates from about 70-S0~/c of the cata-lyst from the vaporous material. A uni~ue feature of one parti-cular suspension separation device employed is that it allows relatively high vapor s~perficial velocities during disengagement from catalys' solids in the disengaging vessel before the vapors enter the reactor cyclones for further separation of entrained catalyst solids. Hydrocarbons leaving the reactor cyclones are separated in a downstream fractionation column. The spent catalyst particles recovered from the riser cracking operation are stripped at an elevated temperature in the range of about 900F to about 1100F comprise deactivating carbonaceous residue in the-range of 1 0 weight percent to abo~t 2.5 or more weight percent of coke The stripped cata'lyst is passed to a first dense fluid bed of catalyst in a first temperature restricted catalyst regeneration zone maintained below about 15C0F and . .
more usually nDt above about 1400F. The hydrocarbonaceous material combustion to be accomplished in the first temperature restrained s'age of catalyst regeneration is one of relatively S~3~7~
mild temperature su~ficient tc ~>ur. all the nydrogen present in hydroca~bonaceous depos~s and from about 10 to 80% of the total carbon therein. The regenerator temperature is restricted *o within the range of 1150F to 1500F and preferably to a temper-ature which does not exceed the hydrothermal stability of the catalyst or the me~allurgical limits of a conventional low temperature regenerator operation~ Flue gases r.ich in C0 are re-covered from the first stage regene~ator and usually are directed to a C0 boiler to generate steam by promoting more complete com-bustion of available C0 therein. They may be passed through a power recovery prime mover section prior to passage to a C~
boiler. The mild restrained catalyst regeneration operation serves to limit local catalyst hot spDts in the presence of steam formed during the hydrogen combustion so that formed steam will not be at a temperature to hydrothermally substantially reduce the catalyst activity. A partially regenerated catal~7st of limited temperature and comprising carbon residue is recovered from the first regenerator substantially free of hydrogen. The hydrogen freed catalyst comprising residual carbon is passed to a sec~nd separate unrestrained higher temperature catalyst regen-eration operation wherein the remaining carbon is substantially completely burned to C02 whereby an elevated catalyst temperature within the range of 1400F up to about 1800F is achieved in a moisture free atmosphere.

The second seprate stage comprising a high te~.perature cata1yst regenerator i5 designed to limit catalysl inventory and catalys_ residence time therein at the high temperature while permitting a carbon burning rate to achieve a residual carbon on recycled hot catalyst particles less than about 0.0~ weight percent and more preferably less than about 0.02 weignt percent.

~;9S~9 ~raditionally designed catalyst regenerators utilized in p_icr art fluid catalytic cracking operations have contained various internal components fundamental to the successful operating needs of the process. These include cyclones, ~sually of several stages and designed to limit process losses of catalyst, cata-lyst return conduits (diplegs) from the cyclones to the cata-lyst bed, vario~s support and brasing devices for the above mentioned means. A hopper or similar device plus associated conduits to enable collection and withdrawal of catalyst and passage back to the cracking step of the process. Of necessity, in prior art systems, these various above-mentioned means are of metallic construction, usually stainless steel, and exposed directly to the combustion .emperatures of the regenerator. It is the presence of these metal exposed means in the regeneration combustion zone that limit the maximum temperature that can be attained or supported in the regeneration of catalyst. Generally this leads to a maximum upper operating temperature limit of about 1400 F or 1500 F

The sec~nd separate stage high temperature catalyst regenerator embodiment of this invention eliminates problems ass~ciated with the above mentioned limitations by locating all metal exposed devices such as cyclones, diplegs, draw off hopper or well and support systems outside the combustion zone and indeed external to the regenerator itself. The regenerator vessel, void of any of the above mentioned internals in the catalyst combustion zone, is refractory lined as are all connecting`condu_ts, external cyclones and diplegs. The design of such a reyenerator combi-nation is considered to be a significant improvement over any known prior art. Regenexated catalyst at a desired elevated temperature is withdrawn from a xelatively dense luid catalyst -l~S9S79 bed in the sec~d stage regenerator by means cr a withdrawal cor,-duit external to the regenerator vessel. The withraw~ catalyst - is char~,ed to a stripping zone before being passed ~o the riser reactor at the desired elevated vaporization temperature herein identified and in an amo~n~ sufficient to vaporize the resid~al hydrocarbon feed charged according to the operatin~ techniques of this invention. ~ot fl~e gases obtained from the second regenerator are fed to external cyclones for recove~y of entrained catalyst fines before further utilization as by passing to a waste heat recover~ system and then to an expander turbine or dis-charged to the atmosphere. Due to the fact that the c~clo~es of the highest temperature second regeneration stage are exter-nally located some major and significant advantages aside 'rom 'those cited above are sained. Once the cyclone separators are moved from the interior of the catalyst regeneration device to the exterior, it is prac.ical to increase the diameter and/or length of the cyclone separation device and improve its separa-tion efficiency in such a way that a single stage cyclone separator means can be use~ in place of a two stage cyclone separation means and yet accomplish improved separation ef'i-ciency. This is accomplished in part by use of a straight cylin-drical pipe or obround flue gas transfer pipe or one including a curved section therein external to the cyclone and generally coinciding with the cyclone wall curvature and tangentially con-nected to the cyclone. This curved flue gas transfer conduit means induces an initial centrifugal motion to the hot flue gas catalyst partic~e suspension thereby iritiating entrained particle concentration and encouraging substantially improved cyclone separation efficiency between gases and solids thereby enabling significant changes in cyclone design. In addition, a most significant factor favoring the use of the external ~25~3579 cyclone is 'hat the cyclone overall length can be increased as it does not have to fit inside a refractory l,ined regenerator vessel of limited dimensions and space and the cyclone separa-ting efficiency can ~e sign;ficantly impr~ved. The net effect of the above flue gas txansfer conduit and cyclone means is that a single stage external cyclone may be made the operating equivalent of a two-stage sequentially arranged internai cyclone separation system. Externally located refractory lined cyclones can be fabricated of carbon steel even when employed with a regenerator operated at a temperature above 14~0F and up to lB~0F. ~urthermore, the external cycl~nes can be checked during on stream use with an infrared camera and relatively easily repaired before being replaced during a shutdown or turn axound.

The residual oll cracking process of this invention is considered a significant breakthrough over that more conventional FCC tech-noloyy processing relatively clean gas oil feeds in that it allows one to more efficiently convert the high boiling residual compo-nent6 of the feed boiling above 1000F and more importantly per-mits providing the necessary ana desired high catalyst tempera-tures while at the same time providing an operating environment not appre~iably thermally harmful to the catalyst employed in the process than encountered in gas oil FCC,operations. The desired ultimate high temperature catalyst regeneration operation of the invention is required to achieve the substantial instant neous atomization/vaporization of the heavy residual oil feed compo-nents by the catalyst to substant1ally convert more of the bot- , tom of a barrel of crude oil, shale oil, etc., or any other heavy high molecular weight liquid hydrocarbonaceous material to foxm lower boiling materials including gasoline. This is ~s~9 considered a major step ~orwa~d in the petroleum refining industry and reduces the dependence of 'free world na'ions' on imported crude oi.1. It permits processing the poorer quality crude oils which are less expensive to obtain.

Additional benefits resulting ~rom the resid cracking process of this invention are related to obtaining a red~ction in energy consumption in the overall processing of the total crude oil barrel and permits achieving and a red~ction in both air and water pollution.~ Some of these savings are achieved by sh~tting down vacuum dlstillation units, asphalt extraction units and various thermal processes such as delayed co~ing and thermal visbreaking in some instances, These and other known prior art processes would normally be used to further process atmos-pheric residua Typical energy savings in a crude unit operation by sh~tting down.a vacu~m unit is about 0.~ volume percent to 1.0 volume percen.t on crude charge. A1SO~ air and water p~l}ution ~re-quently associated with the aforementioned deleted processeswill be eliminated.

A further significant benefit of the resid.ual oil cracking opera-tion of the invention resides in obtaining a sulphur removal in the range of about 60-70% in the absence of substan~ial separate hydrogenation treatment. The H2S formed in the cra~king oper-ation may be removed by amine scrubbing from vapcrous hydro-carbons and fed to a claus unit for elemental sulphur recovery and sales as such, as opposed to effecting substantial release as S02 in the regeneration combustion processes.

~;~S~579 It will De recognized ~y ~;hose skilled in the art that the conversion of residual hydrocarbons may be effected in a number of different apparatus arrangements perferably comprising a riser cracking zone provided with multiple hydrocarbon feed inlet means thereto for achieving intimate contact with fluidized cata-lyst particles and desired short contact time in a riser contact zone befo-e discharging into a separa~ion zone which may or may not contain a relatively shallow dense fluid catalyst bed.
Separation of hydrocarbon products from catalyst discharged from the riser may be promoted by mechanical means or any arrange-ments identified ln the prior art and suitable for the purpose.
However in any of these hydrocarbon conversion arranqements regeneration of the catalyst ~sed therein is most effectively accomplished when using the se~uential regeneration techniq~es of this invention. Therefore the regeneration concepts and oper-ating techniques particularly contemplated and defined by this invention are ~sed with considerable responsive advantaae in any catalytic cracking operation.

FIG. I is a diagrammatic sketch in elevation of a two-stage cata-lyst regeneration operation adjacent to and in combination with a riser hydrocarbon conversion operation. A catalyst recovexy and collecting zone of restricted cylindrical dimension abo~t the riser discharge encompasses preliminary catalyst-vapoL separ-ating means expanding outwardly in a horizontal direction from a riser reactor outlet and adjacent to cyclone separating means positioned in an upper portion of the collecting vessel.

FIG. II is a diasrammatic sketch in elevation of a side~-by-side catalytic cracking-catalyst regeneration opera ion embodying a stacked arrangement of two-stage-catalyst regeneration provided 1~5~g wi,h relativelv large cyclone separators positioned ex.ernal to the vessel means for the second stage of high tempe-a~ure cata-lyst regeneration.

FIG. III is a horizontal cross-sectional view Of one arrangement of a rough cut separator means at the risPr outlet O r FIGS. I and II.

FIG. IV is a more detailed sketch of the lower portion of the riser hydrocarbon conversion zone of FIGS. I and II detailing particularly the multiple nozzle feed inlet means.

~IG. V is a graphical representation of the conversion achieved for two different systems of residual oil feed atomization.
System two employed a more highly atomized feed than system one or the first system.

PIG. VI is a diagrammatic sketch in elevation of a bottom por.ion of a riser cracking zone, with regenerated catalyst inlet conduit, a fluidizing gas inlet cond~it and a nozzle arrange~ent forming a highly atomized oil feed thereafter discharged within the riser at a relatively high velocity.

Discussion of Specific ~mbodiments In the processing schemes discussed below, arrangements of appar-atus are provided for accomplishing the relatively high tem~era-ture catalytic cracking of a residual oil to pxoduce gascline boiling range material and hydrocarbon material~ readiîy con-verted into gasoline ~oiling components and fuel oils. Regener-ation of the cracking catalyst so emploved is accomp'ished parti-c~lzrly in z two-stage catalyst regeneration ope-atior ma_ntained ~255~7~3 ~nder tempera~ure res.ricted conditions in a rirst separate regen-era'ior. zone to partic~larly remove hydrogen deposited by hydro-carbonaceous produc's of the crac~.ing operation. CO ormation in the -irst regeneration zone is not particularly restricted and deactivation of the catalyst by steam formed in the hydrogen burning operation is held to a desired low level Thereaf~er, hydrogen-free residual carhon is removed from the partially regenerated catalyst in a second separate relatively dense fluid catalyst system at a more elevated temperature and s~fficiently high oxygen concentration restricting the formation of any signi-ficant quantity of CO or steam by effecti.ng combustion of resi-dual carbon deposits on the catalyst. The temperature o f ,he second stage catalyst regeneration is allowed to rise sufficiently high to provide a desired oil contact temperature. Generally the temperature range of the regenerated catalyst will be from about 1400F up to 1800F. The regeneration flue gas of the second stage regeneration operation will therefore be s~hstantially CO free if not completely free of CO. Since the flue gas o~ the second stage regeneration operation will be CO2 rich, s~ch C02 rich gas may or may not be employed therear~er for steam genera-tion, stripping catalyst between stages of the process and other uses for such gas as desired. The catalyst th~s regenerated and comprising a resid~al carbon on catalyst of less than about 0.20 weight percent and preferably less than 0.05 weight percent is recycled to the cracking operation~

It will be recDgnized by those skilled in the art that the pro-cessing scheme of this invention minimizes hign temperature steam deactivation of the catalyst and is an ener~y conserving arrangement which is particularly desired in this day of ene_gy restrictions. That is, the two stage regeneration operation of ~2S~57~

this invention reduces 'he air blower requirement over tha' Or 2 single stage regenera.ion operation while accomplishing mo-e complete coke removal and heating of catalyst par~icles to a desired elevated temperature. The ~irst stage restricted rela-tively low temperature regeneration operation is not res,ricted to CO formation wherein steam is usually formed and the second stage higher temperature regeneration operation is accomplished in the absence of formed steam wherein only a residual portion of the total carbon initially deposited on the catalyst is removed. These energy conserving operating conditions are of considerable economic advantage to the crac~ing operation in that a smaller CO boiler for producing process utilized steam can be used to process the volume of flue sas oblained from the first stage regeneration operation. The much higher temperature C2 flue gas recovered from the separate second stage regenera-tion and absent any significant combustion supporting level of CO may be cooled in a suitable device or heat exchange means generating additional steam.

The residual oil processing arrangement of the invention provides further slgnificant energy conservation in that by charging an atmospheric residual oil feed portion of a crude oil to the cracking operation, energy intensive vacuum distillation, and deasphalting, delayed coking, and other forms of feed preparation requiring significant energy are eliminated. Steam gene~ated by CO rich flue gas as above identified and/or process obtained normally gaseous hydrocarbons may be used with .he feed as 2 diluent to improve atomization of the feed upon contact with the hot regenerated catalyst.

The hot catalyst particles obtained as herein provided and char~ed ~2~9579 to the cracking operalion can be at a desired higher temperature tnan is normall~ obtained in the prior art single stage tempera- -ture limited regeneration operation. Furthermore it is obtained witho~t effecting steam and/or hydro-thermal damage to the highe~
temperature catalyst. ln addition the regeneration sequence of the invention more economically contrib~tes more heat to the desired ~aporization and endothermic catalytic conversion of the residual oil hydrocarbon charge as herein provided. ~urther energy conservation advantages are achieve~ by virt~e of the fact that a residual oil comprising aistress components of the crude oil boiling above 102~~ are processe~ to more desirable lower boiling products including sasoline boiling range products and gasoline precursors through the elimination of satellite high energy consuming operations, such as vacuum distillation, pro-pane deasphalting, visbreaking, delayed coking, feed hydrogen en-riching operations and combinations thereof as employed heretofore in the petroleum refining industry.

The processing combinations of the present invention contemplate maintaining desired equilibrium catalyst in the system by re-placing catalyst circulated in the system with catalyst particles of a lower metals loading obtained, for example, as fresh cata-lyst or as equilibrium catalyst from other clean feed cracking operations. Th~s, a portion o~ the catalyst particles separated from the first stage low temperature regeneration operation or the second stage higher temperature regeneration operation or ~oth as normal catalyst loss or by special withdrawal means may be replaced with fresher catalyst particles of suitable higher cracking activity and comprising lower levels of deposited metal contaminants.

79~
~he operatins concepts of the present invention are useful in desisning g~ass roots systems and adaptable to many different refining operations now in existence and comprising a single regeneratlon operation in combination with a hydrocarbon conver-sion operation such as a riser cracking or a dense fluid bed cracking operation. In any of these operations it is intended that the regeneration temperature necessarily be restricted to a low temperature first stage and a second higher temperature sepa-ate regeneration operation in order to achieve the advan-tages of the present invention particularly with respect to energy conservation and eliminating high temperature hydrothermal damage to the cracking catalyst in the presence of formed steam.

It is immediately clear that the sequential catalyst regenera-ting concepts of this invention permit improving substantially any hydrocarbon conversion process whether or not the hydro-carbon charged to the cracking operation comprises distress as-phaltic componerts and metal contaminants or is merely a hi~h coke producing charge material relatively free of significant am~unt of metal contaminants and/or aspha]tenes. However, as provided herein, the advantages of the processing innovations of this invention su~stantially improve as satellite treatment o~ the crude hydrocarbon charge to remove these materials is reduced.

It will be further recognized by those skilled in tne prior art, that existing temperature restricted catalytic cracking and regeneration apparatus may be modernized to achie~e the higher temperature operations of this invention with a minimum capital expenditure and downtime whether or not one is modernizing a stacked single stage reactor regenerator arrangement, a si~e-by-side single s=age reactor regenerator arrangement or one o 'he more modern units c3mprising a riser reactor hydrocarbon conversior, zone in combinatior with a dense cata:~yst bed in open communication with an upper riser catalyst reqeneration ope-ation.

Referring now to FIG. I by way of e~ample, spent catalyst part-icles recovered rom a residual oil hydrocarbon conversion stri~
pin~ operation and comprising hydrocarbonaceous deposits is passed by conduit 1 into a first dense fluid bed o~ catalyst 3 housed in regeneration vessel 5. Regeneration vessel 5 is identi-1ed herein as a relatively low temperature regeneration vessel wherein the temperature is maintained below about 1500F and the concentration of oxygen charged by regeneration gas in conduit 7 and distributor 9 is restricted to limit regene ation tempera-ture encountered as desired during combustion or buxning parti-cularly of hydrogen and carbonaceous deposits associated with hyrocarbonaceous deposits of residual oil cracking. The com-bustion accomplished in the first stage regeneration operation herein identified is accomplished under conditions to form steam and a C0 rich regeneration flue gas. The flue gas thus gener-ated is passed through cyclone separators means represented by separators 11 and 13 to separate entrained catalyst particles therefrom before withdrawal by conduit 15. Catalyst thus separ-ated from the C0 rich flue gases by the cyclones is returned to the catalyst bed-by appropriate diplegs. In receneration vessel ~, it is part_cularly intended that regeneration conditions are selected so that the catalyst is only partially regenerated in the remotTal of carbonaceous deposi~s so that sufficient residual carbon remains on the catalyst to achieve higher ca'alvst particl~e temperatures above 1400F or above 150~F upon more complete removal by combustion with excess oxvgen containing regeneration ~ L259579 g~s .

In the arrangement of Figure I, the first stage of catalyst regenerations accomplished in vessel 5 is a relatively low tem-perature operation preferably restricted not to exceed about 1400F or 1500~ and produce a C0 rich product flue gas. Part-ially regenerated catalyst a~sent any significant amount of steam forming hydrogen is withdrawn from the catalyst bed of the first regeneration step by withdrawal conduit means 17 for pas-sage to an adjacent stripping zvne or.vessel 19. A downflowing relatively dense fluid mass of partially regenerated.catalyst is caused to flow through vessel 19 counter current to aera'ing and stripping gas introduced by conduit 21. The aerating gas is preferably one which wilI be relatively inert at least with res-pect to deactivating the partially regenerated catalyst and pre-ferably is one which will considerably restrict the transfer of moisture formed components with the catalyst to a second stage of ca~alyst regeneration effected at a temperature above 1500F.
Aerating sases suitable for ~se in zone 19 include C02, flue gas substantially moisture-free, nitrogen, dry air and combina-.tions thereof.

The partially regenerated catalyst lS withdrawn from vessel 19 by a stand pipe 23 communicating with catalyst transfer conduit 25 and riser conduit 27. Gas such as air, nitrogen, C~2 and mixtures thereo~ may be added to assist with transp~rting the catalyst by gas inlet conduits 29 and 31. A plurality of gas inlet conduits represented by conduit 29 may be employed in the conduit bend between conduits ,3 and 25 and downstream thereo~
in the transport conduit to aid transport of catalyst there-through Regeneration gas such as air or an oxygen enriched ~z~ 9 gas steam is introduced by conduit 31 fcr contac= with p~rtially regenerated catalyst in riser co~duit 27. Conduit 27 discharges into a bed ~f catalyst 33 maintained in the lower portion of a relatively large diameter regeneration zone or vessel 35 Addi-tional regeneration gas such as air is introduced to a lower portion of catalyst bed 33 by conduit 37 comm~nicating with air distributing means suitable for the high temperature operation to be encountered.

In the second stage regeneration operation effected in règener-ator 35, the temperature is within the range of 1400F to 1800~
and sufficiently higher than the first stage of regeneration to accomylish substantially complete removal of residua~ carbon not removed in the first stage. Regenerator vessel 35 lS a refractory lined vessel substantially ~ree of metal ex~osed inter-nals and cyclones so that the high temperature regeneration de-sired may be effected. In this high temperature operation, residual carbon on catalyst is preferably reduced below 0.0~
weight percent and a high temperature CO~ rl~e ~as sLream is recovered by external cyclone separators. Prefera~ly relatively large single stage cyclone separators are used which are refrac-tory lined vessels. ~hat is external plenum section 39 is pro-vided with radiating arms from which cyclone separators are hung or arranged as graphically shown in the drawing by arms 41 and 43 and connected to cyclones 4~ and 47 respectively. On the other hand, the cyclone arrangement of ~IG. II discussed below may be employed with regenerator 35. Catalvst thus separated from flue gas at eleva~ed temperatures up to 1800F is returned by diplegs provided. A high temperature CO2 rich flue gas is recovercd separately from each cvclone separator for further use as desired or 2S a com~ined hot fl~e gas stream 49 for gen-~S5a57~

erating steam in equipment not shown It will be recognized bythose skilled in the art that more than one cycione SQparator may be used together in sequence and the number of cyclones in the sequence will be determined by the size of each and the arrangement employed.

The catalyst regenerated in the second stage of regeneration and heated to a temperature above the first stage regeneration temp-erature by burning residual carbon to a level below 0.10 weight percent and preferably below 0.05 weight percent carbon is with-drawn from bed 33 by conduit 51 and passed to an adjacent vessel 53. The withdrawn catalyst is aerated preferably by a moisture free gas introduced by conduit 55 or at least one substantially moisture free in the adjacent catalyst collecting zone or vessel 53. Aerating gas is withdrawn by conduit 57 and passed to the upper portion of vessel 35. Hot regenerated catalyst at a temp-erature above 1400F is withdrawn from zone 53 by a standpipe 59 comprising flow control valve 61. The hot catalyst then passes by transport conduit 63 to the lower bottom portion 65 of a riser hydrocarbon conversion zone 67. Aerating or lift gas, s~ch as light hydrocarbons recovered from a downstream light ends recovery operation not shown or other suitable fluidizing gaseous material is charged beneath the catalyst inlet to the riser by conduit 60.

t In the hydrocarbon conversion operation particularly contemplated, the hot catalyst of low residual carbon is caused to flow upward-ly and become commingl~d with a multiplicity of hydrocarbon streams in the riser cross-section charged through a plurality of feed nozzles 71 arran~ed adjacent to but spaced inwardly from ~Q ~ r rQfractory lined wall section. More particularly the ~'3S~9 riser wal] is provided with an eY~panded wall section 73 through which the plurality of horizontally spaced apart ~eed nozzles pass upwardly and inwardly there through. A dlluent gas such as steam, light hydrocarbons or a mixture thereof is added with the residual oil charged to enhance its atomized dispersion and vaporized commingling with the high temperature fluid catalyst particles. The riser section adjacent to the outlet of the feed lnjection nozzles is preferably expanded to a larger diameter riser vessel through which the suspensio~ of vaporized oil and catalyst pass. To further assist with obtaining desired com-mingling and substantially instantaneous vaporization of the charged residual oil components, a number of small atomized oil feed streams are admixed with the charged upflowing catalyst.
The vaporized hydrocarbon material comprising products of crack-ing admixed with suspended particles of catalyst pass upwardly through the riser 67 for discharge from the upper end of the riser through suspension separator means. Various means in the prior art may be used for this purpose. The initial suspension separator referred to as a rough cut separator at the end of the riser hydrocarbon conversion zone is shown as an outwardly expanding appendage from the riser resembling butterfly-shaped wing appendages in association with relatively large openings in the wall of the riser adjacent the capped upper end there-of. That is, the rough cut separator at the riser end viewed from the side and top resembles a butterfly-shaped device. The appendages are open in the bottom portion thereof to the sur-rounding vessel 87 for discharging hydrocarbon vapor separated substantially from catalyst particles. The sides 77, FIG. III, are solid substantially vertical panels and the ends 79 adjacent the wall of vessel 87 are solid substantially vertical curved panels. The top of each appendage is capped by a sloping roof 1~25~3579 81 to mini~ize the hold-up of settled catalyst and co~e particles thexeon~ The slope of the roof panel is preferably at least equal to the ansle of repo~e of the catalyst employed and more preferably greater to avoid catalyst holdup on the appendage roof.
Other arrangements known in the prior art permitting high vapor discharge velocities may be employed for effecting initial separ-ation of the hudrocarbon vapor - catalyst suspension discharged from the riser upper end.

In operation, the vaporous materials comprising hydrocarbons and diluent in admixture with suspended catalyst is discharged through openings 75 in the riser and expanded within each appen-dage chambers A and B to reduce the velocity of the mixture, change the direction of the susp~nsion components and concen-trate catalyst particles separated from vaporous material along the outside vertical curved wall 79 of each appendage. The c~talyst particles thus concentrated or separated, fall down the wall and are collected as an annular bed of catalyst 83 there-below comprising a catalyst stripping zone. Vaporous materia~s separated from particles o~ catalyst pass downwardly through the open bottom of each appendage adjacent to riser wall and thence flow upwardly into one or m~re, such as, a plurality of cyclone separators represented by separator 85 in the upper portion of vessel 87. Hydrocarbon vapors, diluent and stripping gasiform material separated from catalyst is withdrawn by conduit 8c for passage to product re-overy equipment not shown. Catalyst separ-ated in the one or more cyclones is passed by diplegs provided to catalyst bed 83. Stripping gas such as steam, is charged to bed 83 by conduit 91. Stripped hydrocarbons pass with product hydrocarbon vapors leaving the rough cut separator an~ enter the cyclone separator arr~ngement. The stripped catalyst comprising r~

hydrocarbonaceous product of residual oil cracking and metal con-taminants s withdrawn by conduit 93 comprising valve 95 and thence is passed by conduit 1 to the first regeneration stage.

Referring now to FIG. II there is shown an arrangement of appar-atus differing from the apparatus arrangement of FIG. I in that the separate regeneration vessels 2 and 4 are stacked one above the other on a common axis with the highest temperature regener-ator 4 being the top vessel. In addition the hot flue gases are withdrawn from regenerator 4 through refractory lined piping 6 and 8 axranged to resemble a "T" with a large cyclone separator 10 in open communication with and hung from each horizontal arm 8 of the "T" pipe section. In this apparatus arrangement, the hydrocarbon converslon riser reactor 12 with multiple feed inlet represented by means 14 and suspension rough cut separating means 16 are shown the same as discussed with respect to ~IG. I. How-ever, it is contemplated using this system or other arrangements in combination with one, two, or more large cyclone separators 18 in an upper portion of the catalyst collecting vessel 20 adja-cent the riser discharge within or external to the collecting vessel 20. An arrangement resembling that shown with respect to the upper regenerator 4 of the apparatus may also be employed.

In the apparatus arrangement of FIG. II, hot regenerated cata-lyst at a temperature above 1400F in conduit 22 and at least equal to the residual oil feed pseudo-critical temperature is charged to the base of riser 12 where it is commingled with lift or aerating gas introduced by conduit 24 to form an upflowing suspension. Catalyst thus aerated or suspended is thereafter caused to be contacted wlth a plurality of atomized oil feed streams by a plurality of feed nozzle means 14. In a particular _~A _ ~;i9~7~
em`~odiment there are 6 horizontally spaced apart nozzle FIG. IV
e~tending through the ris~r wall adjacent an expanded section thereof in the manner shown. Steam or ~ther diluent material may be injected with the feed for atomizing dispersion purposes as discussed above.

A vaporous hydrocarbon catalyst suspension passes upwardly through riser 12 for discharge through ro~gh cut appendages 16 in a manner as discussed with respect to FIG. I. Hydrocarbon vapors separated from catalyst particles pa`ss through one or more cyclone separators 18 for additional recovery of catalyst before passing the hydrocarbon containing vaporous material by conduit 26 to a product fractionation step not shown.

Catalyst separated by means 16 and cyclone 18 is collected as a bed of catalyst in a lower portion of vessel 20. Stripping gas, such as steam, is introduced to the lower bottom portion of the bed by conduit 28. Stripped catalyst is passed by conduit 30 with valve 72 to a bed of catalyst 32 being regenerated in ves-sel 2. Regeneration gas, such as air, i9 introduced to a bottom portion of bed 32 by conduit means 34 communicating with air distributor ring 36 Regeneration zone 2 is maintained as a rela-tively low temperature regeneration operation below 1500F and under conditions selected to achieve a partial removal of carbon deposits and all of the hydrogen associated with deposited hydro-carbonaceous m~terial of cracking. In this operation a CO rich flue gas is formed which is separated from entrained catalyst fines by one or more cyclones, such as cyclones 38 and 40, in parallel or sequential arrangement with another cyclone. C0 rich flue gases are recovered from the cyclone separating means by conduit 42 for ~se as herein discussed.

1~5~3S79 Part:ially regenerclted ca~alys~_ is withdrawn from a lower portion of bed 32 for transfer upwardly through riser 44 for discharge into the lower portion of a dense fluid bed of catalyst 46 in an upper separate second s-tage of catalyst regeneration having an uppex interface 48. Regeneration gas, such as air or oxygen enriched gas, is charged to the bottom inlet or riser 44 by a hollow stem plug valve 54 comprising flow control means 7~.
Additional regeneration gas, such as air or oxygen enriched gas, is chaxged to bed 46 by conduit 50 communicating with air dis-tributor ring 52. Regeneration vessel 4 is a refractory lined vessel freed of metal appendages as discussed above so that the temperature therein is not restricted by metal appendages and may be allowed unrestrained to reach a higher temperature or exceed 1500 F and go up to as high as 1800F or as required to complete carbon combustion. In this catalyst regeneration envir-onment, residual carbon remaining on the catalyst following the first temperature restrained regeneration stage is substantially completely removed in the second unrestrained temperature regen-eration stage. Thus the temperature in regenerator 4 is not particularly restricted to an upper level except as limited by the amount of carbon to he removed there within and sufficient oxygen is charged to produce a C02 rich flue gas absent combus-tion supporting amounts of C0 by burning the residual carbon on the catalyst. The C02 rich flue gas thus generated passes with some entrained catalyst particles from the dense fluid catalyst bed 46 into a more dispersed catalyst phase thereabove from which the flue gas is withdrawn by conduits 6 and 8 communicating with more than one cyclone 10. Conduit means 8 is either straight or horizontally curved prior to tangential communication with cyclone 10. The curvature of conduit 8 is preferably commensur-ate in part with the curvature of the cyclone wall so that an lZ5~57~
initial centrifugal sepaxation of entrained catalyst pa~ticles is effected in conduit 8 and prior to entering the cyclone separ-ator. Catalyst particles are separated from the hot flue gases with a high degree of efficiency by this arrangement and the efficiency of the cyclone separating means can be more optimized by lengthening the conical bottom of the cyclone. Catalyst par-tlcles thus separated are passed by refractory lined leg means 56 to the bed of catalyst 46 in the high temperature regenerator.
C2 rich flue gases absent combustion supporting amounts of C~
are recovered by conduit 58 from cyclone 10 for use as herein described. Catalyst particles regenerated in zone or vessel 4 at a hi~h temperature up to 1800F are withdrawn by refractory lined conduit 60 for passage to vessel 62 and thence by conduit 64 provided with valve 66 to conduit 22 communica~ing with the rlser reactor 12 as above discussed. Aerating gas is introduced to a lower portion of vessel 62 by conduit means 68 communicat-ing with a distributor ring within the vessel 62. Gaseous material withdrawn from the top of vessel 62 by conduit 70 passes into the upper dispersed catalyst phase of vessel 4.

The apparatus arrangement of FIG. II is a compact side-by-side system arranged in pressure balance to achieve desired circula-tion of catalyst particles and the processing conditions parti-cularly desired as herein discussed. The operation of the system is enhanced by the use of spheroidal shaped particles of catalyst less than 200 microns and an average particle size may be selected from within the range of 50 microns up to 120 microns.
It is contemplated modifying the system of FIG. II by providing external cyclones on vessel 20 with openings thereto about the upper end of the outlet of the riser conversion zone. The exter-nal cyclone separating means may also be arranged substantially ~5~35~9 similarly to that shown by cond~its 6 and 8 and cyclone 10 of reg~erator 4 and may ~e at-tached to a vertically shortened vessel 20 and used in place of internal cycl~ne 18. Catalyst particles thus separa,ed would be conveyed by suitable diplegs communicatinq with the bed of collected particles in the lower portion of vessel 20 being contacted with stripping gas intro-duced by conduit 28.

Referring now to FIG. IV by way of example, there is shown in greater detail one arrangement of apparatus contemplated for separately charging hot regenerated catalyst and a residual oil feed to a lower portion of the hydrocarbon conversion riser zone 65 of FIG. I or riser 12 of ~IG. II. The residual oil is fed through a plurality of tubes 71 which are either straight or curved. The tubes may be jacketed in a tube providing an annular zone for steam blanketing if desired. In the arrange-ment of FIG. IV, hot catalyst at an elevated temperature above identified and above the residual oil feed pseudo-critical tem-perature is charged by refractory lined conduit 63 to a bottom portion 65 of the riser hydrocarbon conversion conduit 67 each being lined with refractory material. Catalyst aerating or fluidizing gas is charged by conduit 69 to a gas distributor in the bottom portion of the riser. A hot suspension of cata-lyst and lift gas is formed in the bottom portion of the riser which thereafter passes upwardly through the riser into an expanded section thereof for con~act with residual oil feed charged by plurality of feed inlet pipes 71. The oil feed charged by means 71 is mixed with a diluent such as steam or light hydrocarbons charged by conduit 109, thereby considerably reducing the partial pressure of the charged hydrocarbon feed.

~25~579 Jacket steam for the oil fee~ nozzle is charged to an annular section formed about pipe 71 by steam inlet means 111. A plur-ality of such jacketed nozzles horizontally displaced apart are provided which discharge in the cross-section of the riser and preferably there are six such nozzles positioned to achieve high temperature contact between fluidized catalyst particles and oil charged to achieve substantially instantaneous vaporization-atGmiZation of the residual oil feed. ~he nozzle arrangement discharges into an expanded all section of the riser after pass-ing through section 73 viewed in one arrangement as a half pipe section in the riser wall which is filled with refractory mater-ial. The nozzles are arranged to discharge in equal area diameter portion of the riser cross section so as to improve intimate atomization-vaporization contact with the upflowing suspended catalyst particles passing up the riser. The plurality of oil feed pipe outlets are preferably arranged in a circle and spaced from the riser wall within the expanded riser cross-section to achieved desired mixing of oil feed with the hot catalyst particles sufficient to achieve substantially instan-taneous vaporization of the charged residual oil. It is recog-nized that various techniques known in the prior art comprising atomizing nozzles may also be employed to assure more complete and substantial atomization of the charged residual oil feed for more intimate vaporizing contact with the hot catalyst particles at a temperature of at least 1400F and within the range of 1500F
to 1800F~

The residual oil cracking operation of this invention relies upon the very high temperature catalyst regeneration operation for providing a catalyst of very low residual carbon at a tempera-ture exceeding the pseudo-critical temperature of the residual _~q_ l~S'~579 oil feed charqed in order to achieve substantially instantaneous vaporization of ~he charqed oi] feed. Another important aspect of the combination operation is to sustain catalyst activity by replacing some ~etals contaminated catalyst with fresher cata-lyst and effecting an initial regeneration of the catalyst under limited temperature conditions minimizing steam deactivation of catalyst particles during regeneration. The cracking operation of the invention is essentially a once through hydrocarbon feed operation in that there is no recycle of a cycle oil hydrocarbon product to the cracking operation. On the other hand, light normally gaseous hydrocarbon product, process generated steam and C~2 may be recycled an~ used as above provided. It is further contemplated alkylating formed olefin components suitable for the purpose in downstream equipment not shown and hydro-cracking formed hydrocarbon product material boiling above gaso-line to produce additional gasoline and/or light oil product.
The hydrocarbon product boiling above gasoline may be hydrogen-ated to remove sulphur and nitrogen to produce acceptable fuel oil material.

The catalytic cracking-catalyst regeneration concepts above discussed are addressed particularly to achieving a high degree of product selectivity in the catalytic conversion of high boiling hydrocarbons, particularly residual oils, in the pro-duction of cracked gasoline, gasoline precursors and catalytic cycle oils.

The processing concepts hereinafter discussed are more parti-cularly directed to achieving a high degree of product select-ivity in the cracking operations above discussed by paying more particular attention to another operating variable. This other l~S~
operating variable is particularly concerned with achieving heavy oil feed atomization and the nozzle injection system more suitable for the intended purpose In this operating concept it is particularly desired to achieve at ~he point of ccntact of a highly atomized oil feed with fluidized catalyst particles substantially instantaneous vapor-ization-thermal and catalyst conversion of atomized oil droplets~
The hydxocarbon vapor-catalyst suspension increases the velocity, thereof flowing upwardly through the riser and provides a dilute catalyst concentration in the suspension within the range of 1 to 10 pounds per cubic foot and more usually not above about 5 pounds per cubic foot. Thus the more rapid the instantaneous vaporization and conversion of the oil feed is achieved the less of a pressure drop is experienced adjacent to the atomized feed inlet and downstream contact with upflowinq catalyst particles through the riser reactor.

It is observed when operating as herein disclosed that the pro-duct selectivity of the converted residual oil by thermal and catalytic means may be varied considerably depending upon the degree of heavy oil feed atomization brought in contact with the high temperature catalyst particles to achieve vaporization of the charged oil feed. One important operating variable is particularly concerned with utiliæation of a suitable atomizing nozzle feed inlet means providing a high degree of residual oil feed atomization and contact at a relatively high velocity with upflowing hot catalyst particles suitable for the purpose.

Thermal and catalytic conversion of the vaporized oil feed to desired products is thus achieved in a very short time frame concomitantly with reducing the temperature of the formed sus-lzsq3~7yl pension as herein discussed In this preferred operating envir-onment, a highly atomized oil feed is charged to tr,e r;ser cra~k-ing zone at a velocity above 300 feet/second up to 1300 feet~
second (fps) and dispersed in a fan shaped pattern of about 1~
or 15 degrees in a vertical direction by about 90 to 120 or more degrees in a generally horizontal direction to the riser cross-section~ This helps to assure more intimate contact between an upflowing fluid suspension of finely divided hot catalyst par-ticles of an initial particle concentration density in the range of from about 10 to about 35 lbs./cu ft. This velocity of a formed suspension is substantially immediately velocity dis-sipated and forms an upflow hydrocarbon vapor dispersed catalyst particle phase suspension. The rapidity with which this is achieved minimizes the pressure drop encountered in the formation of a relatively high velocity suspension of product vapDrs and catalyst discharged from the riser reactor at a velocity within the range of about 60 to about 120 ft./second. The catalyst concentration of the formed suspension may be varied considerably as re~ui.red to optimize conversion of the hydrocarbon feed. T~e suspension catalyst concentration may be less than 5 pounds per cubic foot and may be as low as 1 or 2 pounds per cubic foot at the riser outlet When achieving substantially instantaneous vaporization of oil droplet, as herein discussed, thermal and catalytic conversion thereof is rapidly achieved in a short vertical space of the riser reactor in a time frame of very short duration. This may be associated with a small pressure drop in a vertical portion of the riser above the feed inlet up to about 5 feet but not more than about 10 feet thereof. The formed suspension temper-ature rapidly drops or is reduced to a level within the range ~2S957~
of about ~35F to about 1000F or 1050F as measured below or at the riser o~tiet. In conjunction with achieving instantaneous vaporization of the atomized oil feed, up to about 50% thermal conversion of the atomized oil ~eed occurs along with catalytic conversion thereof to form high yields of gasoline, gasoline precursors, and cycle oils. The cracking reaction combination is observed to occur in the riser in a very short time frame within the range of 0~5 seconds up to about 2.5 seconds and substantially complete desired conversion optimizing yields of gasoline product is believea to occur from about 0.5 seconds up to a~out 1 or 1.5 seconds. High yield of gasoline and light cycle oil products are obtained when achieving a low.pressure drop within the riser reactor above the atomized feed inlet point and when restricting hydrocarbon vapors in the riser to less than 1.5 seconds in contact with suspended catalyst par-ticles.

It is further observed in developing the residual oil conversion concepts herein expressed that atomizing the oil to a droplet size commensurate with or smaller than the used fluid catalyst particle size and comprising an average particle size selected from within the range of about 20 to about 150 microns also contributes to achieving rapid vaporization of the residual oil feed at relatively high velocity to form a low pressure drop sus-pension thereof in the riser reactor for flow there through as herein discussed.

In the graphical arrangement of FIG. V a comparison is made with respect to the conversion achieved between a first system of residual oil atomization and a second system. The second system comprises the feed nozzle arrangement of FIG. VI and achieves a l~S957~
m~ch niyher degree of feed atomizatlon than achieve~ with a first system FIG, v is substantiall~ self-explanatory and clearly shows a substantial improvement in cataly~ic conversion achieved between the first and second atomization system even tho~gh each experienced the same level of thermo conversion. In the first system of FIG. V comprising less than desired atomized residual oil feed conditions results in reduced catalytic conversion to desired gasoline product and thus less than desired product selectivity even though thermal conversion of at least about 50%
is achieved. This observation is compared with a second residual oil feed atomizing nozzle system providing a more highly atomized oil feed commensurate in droplet size with the cataiyst particle size. This ass~res a more complete vapor distributed residual oil feed for intimate instantaneous admixture with high tempera~
ture suspended catalyst particles sufficient to form a highly dispersed phase suspension therewith. It is graphically shown in FIG. V that each of these processing systems achieve similar thermal conversion but different total product selectlvity The second feed atomizing system of FIG. VI provides a higher overall conversion attributed to the improve~ atomized oil catalytic con-version operation. That is, when identifying catalyst activity on a basis of catalyst surface area times the catalyst to oil ratio, the second atomizing feed system of FIG. VI consistently provides higher levels of conversion with the more highly atomized feed as graphically shown. In this highly atomized and vaporized resid~al oil hydrocarbon conversion environment, it is preferred that the catalyst average surface area be retained at a level of at least 40 sq. m~g by continuous or intermittent replacement with higher surface area catalyst particles ~and preferably the catalyst surface area is retained at a higher level ~p to about 80 or 120 sg. m/g depending on hydrocarbon conversion desired and ~Z5~57~
catalvst replas~ment ~conomics.

The ~xact mechanism by which improved residual oil conversion, product selectivity and yield is achieved by system 2 over system 1 above identiCied is not completely identifiable except to note that the more highly atomized oil feed distributed generally horizontally across the riser cross-section by the nozzle means of FIG. VI apparently accomplishes very rapid vapor-ization of the fine oil droplets for intimate vaporized contact with the high temperature fluid catalyst particles at a temper-ature equal to or above the pseudo-critical temperature of the atomized residual oil feed.

It thus appears that in the relatively severe residual oil-catalyst contact environment of system 2 that highly atomized oil droplets equal to or smaller than a catalyst average part-icles size of about 100 microns and uniformly dispersed there-with at t~e feed pseudo-critical temperature will be substan-tially completely vaporized in less than a fraction of a second if not thermally and catalytically substantially completely converted. It is apparent that such operating conditions comprising a highly atomized oil feed in contact with catalyst particles as above defined has a decidedly improved effect on the conversion and the selectivity of the product achieved.

In a catalytic cracking operation encompassing the operation herein identified, the phenomenon of accomplishing asphalt shattering to produce desired molecular reduction to at least tri-aromatics and lower forms is a new and novel operating concept over the prior art. This operating concept is parti-cularly associated with obtaining high temperature thermal :~S'1~579 conversion or shattering of the asphalt component. This requires elevated catalyst temperatures above those normally employed and achievable by the regeneration technique above discussed to accomplish the desired asphalt molecular reduction.

In this novel residual oil catalytic crac~ing operation, it is considered critical to successful operation to obtain relatively instantaneous shattering of the asphalt components and its structures substantially at the point of feed injection in a very -short time frame not more than a fraction of a second and in advance of or concommitantly with particularly promoting atom-ized gas oil component catalytic cracking. The shattering of the asphalt component of the feed will necessarily enrich the gas oil portion of the feed in aromatic constituents comprising di and tri-aromatics and larger ring compounds but preferably does not include any substantial or significant amounts of 4 and 5 ring aromatics.

The driving force for obtaining asphalt disintegration or mole-cular reduction is essentially thermal or temperat~1re oriented and the impedance thereto is attributed to the heat transfer rate from high temperature catalyst particles to the asphalt molecule.
The desired heat transfer rate increases exponentially as the particle or droplet size of the injected oil spray diminishes or decreases Thus if super hot catalyst particles contacts super atomized oil, then the desired shattering of the asphalt molecule to mono, di and tri-aromatics is accomplished with high efficiency, without condensation of polyaromatic rings as observed in coking processes leading to highër coke production.
In this asphalt shattering environment, the accomplishing time frame must be of sufficient short duration so that the crac~ing catalyst structure is not unduly masked by coke levels so high that normal conversior~ of the lighter gas oil compo~ent of the feed is discouraged or unduly restricted Thus a major role of the catalyst to oil ratio beyond asphalt shattering is to sup-port a mix temperature sufficiently high or elevated to provide normal endothermic catalytic conversion of the 1~0F minus crackable portion of the gas oil components of the residual oil feed. In this regard, it will be recognized that a small cata-lyst circulation rate of extremely hot catalyst or low tempera-ture catalyst particles will not achieve this desired conversion goal as effectively as a larger circulation rate of sufficiently elevated temperature catalyst particles providing a desired high catalyst to oil ratio.

It is observed that there is a catalyst temperature most suitable and desirable for effecting desired conversion of a given as-phalt content residual oil feed-stock. This is referred to and is identifiable with the residual oil pseudo-critical tempera-ture. ~urthermore, the conversion temperature must be increased as the percentage of asphalt in the feed increases to achieve ' desired rapid or instantaneous vaporization of the heavy oil feec, in the presence of hot catalyst particles in order to achieve desirable product selectivity and low coke yields. In this regard, the desired catalyst temperature occurs almost auto-matically in the special two-stage regeneration operation above defined as the asphalt content of the feed increases and wnen the second stage catalyst regenerator temperature is not res-trained in the burning or combustion of carbon deposits. This is because the co~e level on the spent catalyst increases with a hlgher asphalt content feed, :~S~5~S~
This hig~er coke l.evel. catalyst charged to eatalyst regenera~
-tion will cause the regenerated catalyst temperature to rise to higher level.s. Regeneration of catalyst particle-s of higher than normal coke levels is a matter of ccncern in protecti.ng catalyst`activity.

The processing combination herein identified relies upon high temperature rapid shattering of the asphaltic component in a highly atomi~ed resid~al oil feed as discussed above along with recovery and di~posal contributing to improve yields of gaso-line and light cycle oil. The shattering of particularly the asphalt eomp~ne~t of the residual oil feed is of such a nature as to provide signi~icant amounts of di and tri-aromatics along with some higher boiling multi-c~clic compounds. These eomponents which generally resist eonversion by catalytic crack-ing respond to hydroeracking in the form of hydrogenated produet of lower ring eonfiguration favoring mono and di-eyclic rings eontributing to gasoline an~/or low, poor, high cetane distil-late material formation. In addition, the hydrogenated higher boiling product material of hydroeraeklng i.s a hydrogen donor material for the residual oil feed upon reeyele to the eatalytie eracking operation.

The residual oil eatalytie craeking-eatalyst regeneration process herein identified is a substantial breakthrough in eatalytie cracking technology that economically removes metallurgical res-traints on regenerator equipment and temperatures aehieved. It accomplishes asphalt molecular reduction contributing to further improved gasoline yields and light fuel oil yields partieularly when synergistically related to hydrogenation operations includ-ing hydroeracking of multicyclic components in the eycle oil 1~2S~575~

prod~ct of the catalytic cracking step. ~he process combination hereir, described is responsive and adaptive to chances in feed stoc~ properties. In yet another important aspect is the find-ing that no unusual,ly elaborate instrumentation or control systems is required to maintain smooth and stable operation.

The rapidity with which a residùal oil is converted to form gas-oline, lower and higher boiling hydrocarbons by high temperature catalyst as above expressed is further enhanced when more empha-sis is placed on the following operating parameters~ That is, for example, when the riser cracking system of FIG. II above described is modified to include the feed nozzle arrangement of FIG. VI for preparing and charging highly atomized residual oil feed droplets in fan-shaped contact at high velocity with upflowing high temperature fluid catalyst particles suspension in the riser, significantly improved conversion result. In this operation it is desirable that the risin~ catalyst suspen-sion be of a concen.ration in the range of at least 10 up to about 35 or more pounds of catalyst particles per cubic foot to assure rapid and intimate contact with the ch~rged hi~hly atom-ized oil feed herein identified.

The improved residual oil riser conversion operation of this invention relies in substantial measure upon charging a highly atomized residual oil feed herein identified at a relatively high velocity in contact with catalyst particles of an average particle size in the range of about 20 to 150 or less microns such as not more than aboJt 120 microns and comprising a surface area in the range of 40 to 120 sq. m/g. ~atalyst particles of an average particle size selected from within the range of about 60 to about 120 microns are particularly contemplated. ~he S7~
atomiz~d oil feed droplet may be equal ~o or less than the cata-lyst average particle size. However, it is preferred that the atomization of the oil feed be of a droplet size commensurate with the catalyst particl.e size distribution or smaller than the average particle size.

A most significant aspect of a successful residual oil riser cracking operation is associated with achieving rapid thermal cracking of particularly asphaltenes, catalytlc cracking of crackable vaporous cDmponents and rapidly achieving a suspension temperature reduction which will substantially minimize thermal product degradation in the form of high coke yields. In pur-suit of more particularly identifying the improved residual oil riser conversion operation of this invention the following was developed.

Table 1 Vaporization Time for Atomized Reduced Crude Oil Droplet Size Vaporizat:ion Time (Microns~ _ .illiseconds~

It is clear from Table 1 that a reduced crude or residual oil atomized to a droplet size of 100 microns or smaller as herein particularly desired requires a ~ery short vaporization time equal to.or less than 9 milliseconds when contacting ~atalyst l'~S~3579 particles at a temperature at least equal to the pseudo-critical temperature of the oil feec.

The catalyst regeneration-riser cracking concepts for processing residual oil and reduced crudes as herein identified are con-cerned with obtaining a high degree of desired product selectiv-ity at the expense o~ producing coke and less desired gaseousmaterial.

It is clear from the discussion above presented that at the instant of-atomized feed injection and contact with a ~uspension of high temperature catalyst particles as herein identified, all consequentlal reactions and interactions occur in a very short time frame over the range of milliseconds up to about 1 second but less than about 2 seconds depending on the operating para-meters of temperature, feed atomization, catalyst.activity expressed in terms of surface area and contact time. Further-more, these conditions all pass through a transition during traverse of the riser reactor in a manner contributing to the ultimate products desired and comprisiny gasoline, cycle oil and an amount of coke consistent with providing a ~eat ~alanced operation. One particular important aspect to be avoided appears to be associated with prolonged contact of products of cracking comprising di and tri-cyclic aromatic type material to high temperature catalyst since this tends to contribute to product degradation and coke formation. Therefore, a very rapid tempera-ture reduction following vaporization and cracking of the feed not to exceed about 2 seconds and preferably less than about 1 second appears important to optimize the yield of gasoline and cycle oil products. This is particularly achieved by following - the improved riser operating concepts above expressed. A rapid ~Z59579 temperature reduction to witnin the range of 950 to about 1050 is des red.

The preferred operating concepts above expressed are accompanied by a rapid molar expansion of vaporous prod~cts of cracking at the elevated temperature initially employed which inherently contributes to achieving a substantial increase in the formed suspension velocity concurrently with catalyst particle acceler-ation in a fraction of a second. A residual oil cracking oper-ation accomplished within the operating concepts identified, minimizes radial maldistribution of the suspension in the riser and thus catalyst agglomeration and other localized catalyst particle concentrations along the riser wall contributing to undesired high catalyst to oil ratio are avoided.

The rapid residual oil feed vaporization and conversion thereof under relatively high velocity conditions as herein identified is found associated with a very low pressure drop operation within the riser in a limited vertical space above the feed nozzle inlet less than about ten feet. ~h:ls low pressure drop condition is found to be the opposite of that experienced and identified with poor oil feed catalyst mixing in initial por-tions oE a riser up to 5 or lO feet thereof. Thus it is clear that a high degree of oil feed atomization is an essential operating parameter and its distribution across the riser cross-section in a pattern which prornotes intimate instantaneous vaporization contact with catalyst particles for conversion thereof as herein identified. A fan-shaped pattern of lO or 15 degrees in a vertical direction by about 80 to 150 degrees in a direction perpendicular thereto is found to provide a high degree of intimacy of contact.

~LZS''35'~

The discharge of atomized oil feed at high velocity of a~out 5~ ft.~second more or less as hereir, contemplated is not found to be detrimental to the process. ~hat is, it has been deter-mined that employing an atomized oil discharge velocity at the noæzle outlet of 1300 ft./second is rapidly dissipated at a distance therefrom of one inch to about 650 ft./second and to only 35~ ft~/second at a distance of 2 inches from the nozzle tip. At 5iX inches the velocity is reduced t~ 130 ft./second.
The processing concepts of this invention fDr effecting riser cracking of a residual oil feed is accomplished in a very short time frame of a~out 2.5 or not more than a~out 1,5 seconds depending on the residual oil feed charged and the temperature provided by the catalyst when employing feed prehea~ below B00F and more usually not above about 50~ or 600F.

In the arrangement of FIG. VI, the riser bottom section 82 is of smaller diameter than an upper portion 80 thereof and are con-nected by a transition section 84. Fluid catalyst particles are charged to the lower bottom smaller diameter portion of the riser by conduit 8S. Fluidizing gas is charged to the riser beneath the catalyst inlet conduit 86 by conduit 88 communi.cat-ing with a distributing ring within the riser cross-section.
Conduit 9~ pro~ided with valve 92 permits withdrawing catalyst from the ~ottom of the riser. The fluidizing gas charged by conduit 88 may be gaseous products of catalytic cracking from which gasoline precursors are separated or steam may be employed.
A fluidizing gaseform material such as low quality naphtha may be used alone or in admixture with recycled prod~ct hydrocar~on gases as a transition f~uidizing medium for effecting smooth directional change in fluid upflow of hot catalyst particles as as a suspension upwardly in a bottom portion of the riser up to S~9 the fee~ nozzle outle~ in ~he expanded riser section. Instru-ment ~aps may be provided in the riser wall and particularly above transition section 84 for determining pressure drop and - temperature of the operating system.

The fee~ injection nozzle comprises a barrel 94 with a restricted slotted end opening 96 housed in a cylindrical heat dissipating shroud 98. The nozzle passes through the riser wall adjacent to but above the riser transition section at an upwardly slanted desired angle. An angle of about 30 degrees in this specific embodiment is found satisfactory~ The oil feed is charged to the atomizing section of the nozzle with or without a diluent gaseform material such as steam, light hydrocarbons or other suitable materia:L to reduce the partial pressure and/or viscosity of the oil charged by conduit 100 in communication with orifice opening 10~ so that the orifice discharged heavy oil will impinge upon a flat surface 104 to form droplets thereof which are further sheared to a finer droplet siæe by a high velocity gaseous material charged by conduit 106 communicating with ori-fice restri.ction 10~. The atomized heavy ~il feed of des:ired droplet size commensurate with the fluid catalyst particle size as above identified and formed exterior to the riser reactor passes through a barrel portion of the nozzle system at high velocity for discharge from the end thereof by a slotted open-ing 96. A single restricted slot opening may be relied upon for producing a fan-shaped pattern of atomized oil droplets in the riser cross-section. There may be two slots, for example, in parallel arrangement of 90 degrees to one another. It is preferred that two or more of such nozzle system arrangements be provided and e~ually spaced apart horizontally around the riser periphery from one another. For example,there may be 5~579 3, 4 or more of such nozzle systems. It is also contemplated vertically staggering 2 or more of the nozzle arrangements discussed in a restricted vertical space of the riser reactor above the transition section to provide a highly turbulent inti-mate contact section of highly atomized oil feed in contact with upflowing particles of catalyst of desired elevated temper-ature at least e~ual to the oil feed pseudo-critical temperature.

It is contemplated providing the oil feed nozzle arrangement discussed in an upper portion of the riser reactor wall not more than about ten feet below the riser outlet so that the product vapor of thermal and catalytic cracking can be rapidly separated from catalyst upon discharge from the riser upper outlet.

Having thus generally discussed the many operating concepts contributing to the novel combination operation of the invention for upgrading heavy oil streams such as residual oil streams, reduced crudes, tapped crude and the like and descr.ibed speci.fic examples pertaining thereto, it is to be understood that no undue restrictions are to be imposed by reasons thereof except as defined by the following claims.

Claims (30)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS.

1. A method for converting residual oil with fluid catalyst particles which comprises:
(a) passing an upflowing suspension of fluid catalyst particles at an elevated temperature upwardly through a riser reaction zone;
(b) atomizing a residual oil feed to be converted to a droplet size commensurate with or smaller than the particle size of the catalyst particles in the upflowing suspension;
(c) discharging the atomized residual oil at a velocity in excess of 300 ft./sec. for contact with said upflowing catalyst particle suspension initially at a temp-erature at least equal to or above the residual oil feed pseudo critical temperature;
(d) maintaining the temperature of contact between said catalyst particles and said atomized residual oil feed suspension sufficiently elevated to obtain thermal conversion of the atomized oil feed and catalytic conversion thereof to produce vaporous products; and (e) separating the suspension vaporous products of step (d) from catalyst particles following transverse of said riser zone in a time frame less than about 2 seconds.

2. The method of Claim 1 wherein the discharge velocity of the atomized oil feed is within the range of 300 to 1300 ft./sec.

3. The method of Claim 1 wherein the discharge velocity of the atomized oil feed is about 500 ft./sec.

4. The method of Claim 1 wherein the mixing velocity of contact between atomized oil feed and the upflowing catalyst suspension restricts the pressure drop in the riser downstream thereof not to exceed about 3 psig.

5. The method of Clam 1 wherein the pressure drop 10 feet downstream from the atomized oil inlet is not more than 1 psig.

6. The method of Claim 1 wherein atomized residual oil feed of a droplet size commensurate with a catalyst particle size selected from within the range of 20 to 150 microns average particle size is charged to the riser conversion zones as a plurality of separate fan-shaped droplet dispersions for intimate contact with upflowing fluid particles of catalyst at a temperature sufficiently elevated above the oil feed pseudo-critical temperature to thermally crack asphaltenes.

7. The method of Claim 1 wherein the catalyst average particle size is selected within the range of 20 to 120 microns and the atomized oil droplets are equal to or less than 120 microns.

8. The method of Claim 1 wherein atomization of the oil feed is accomplished external to the riser cracking zone and the atomized droplets are thereafter conveyed through an elongated confined zone communicating with a slotted discharge opening in the end thereof positioned horizontally to the riser cross-section for discharge thereto.

9. The method of Claim 8 wherein the atomized oil feed is discharged from said slotted opening at a high velocity in a fan-shaped droplet pattern inclined gener-ally upward in said riser.

10. The method of Claim 1 wherein thermal and catalytic conversion of the atomized residual oil feed is accomplished in a time frame within the range of 0.5 up to 1.5 seconds.

11. The method of Claim 1 wherein:
catalyst separated from the riser suspension com-prises hydrocarbonaceous deposits which are removed in two sequential stages of catalyst regeneration, the first stage being sufficiently temperature restricted to produce CO-rich flue gas and minimize hydrothermal degradation by formed steam; and the second stage of catalyst regeneration being above said first stage temperature sufficient to produce CO2-rich flue gases in the presence of oxygen sufficient to substantially complete removal of carbon on the catalyst to produce catalyst particles at a temperature equal to or above the residual oil feed pseudo-critical temperature.

12. The method of Claim 1 wherein the atomized residual oil feed is brought in contact with catalyst particles providing a surface area within the range of 40 to 100 sq. m/g under conditions sufficient to provide conversion thereof consistent with the upper curve of figure V.

13. The method of Claim 1 wherein atomization of the residual oil feed to small droplets and the tempera-ture of a suspension formed with hot catalyst particles is sufficient to obtain thermal disintegration of feed component boiling above 1025°F and comprising asphalt and asphaltenes to form mono-, di- and tri-aromatic components.

14. The method of Claim 1 wherein the residual oil is atomized to a droplet size of 100 microns or smaller and high temperature vaporization thereof is sufficient to be accomplished in less than a second.

15. The method of Claim 1 wherein thermal and catalytic conversion of the highly atomized residual oil feed with suspended high temperature catalyst and reduces the temperature of the formed vapor product suspension to within the range of about 935°F to about 1050°F.

16. The method of Claim 1 wherein the conversion temperature is increased as the asphalt content of the oil feed is increased and the regeneration of the catalyst is at a temperature satisfying the residual oil feed pseudo-critical conversion temperature.

17. A method for converting a residual portion of crude oil with high temperature fluid catalyst particles which comprises:
(a) flowing a suspension of high temperature fluid catalyst particles upwardly through a riser conversion zone;
(b) atomizing a residual oil feed to be converted to a droplet size commensurate with or smaller than the high temperature suspended catalyst particles of a size in the range of 20 to 200 microns;
(c) charging the atomized residual oil of step (b) at a velocity in the range of 300 to 1300 ft./sec. into contact with said upwardly flowing hot catalyst particle suspension initially at a temperature at least equal to or above the residual oil feed pseudo-critical tempera-ture;
(d) providing the temperature of contact between said catalyst particles and said atomized residual oil feed initially sufficiently elevated to shatter asphalt component in said residual oil and obtain up to 50 percent thermal conversion of the atomized oil feed, effecting catalytic conversion of oil vapors formed in said upflowing suspension thereby reducing the tempera-ture of the suspension; and (e) separating vaporous hydrocarbon conversion products of step (d) from catalyst particles following transverseof said riser zone in a time frame less than about 2 seconds.

18. The method of Claim 17 wherein the discharge velocity of the atomized oil feed into the catalyst suspension is about 500 ft./sec.

19. The method of Claim 17 wherein the velocity of contact between the charged atomized oil feed and the catalyst suspension restricts the pressure drop in the riser not to exceed about 3 psig.

20. The method of Claim 17 wherein the pressure drop about 10 feet downstream from the atomized oil feed inlet is not more than about 1 psig.

21. The method of Claim 17 wherein the atomized residual oil feed is charged to the riser conversion zone as a plurality of separate fan-shaped droplet dispersions across the riser zone for intimate contact with upflowing fluid particles of catalyst at a temperature sufficiently elevated above the oil feed pseudo-critical temperature to thermally crack asphaltenes in the oil feed.

22. The method of Claim 17 wherein the catalyst average particle size is within the range of 20 to 120 microns and the residual oil is atomized to droplets equal to or less than 100 microns.

23. The method of Claim 17 wherein atomization of the oil feed is accomplished external to the riser cracking zone and formed atomized oil droplets are thereafter conveyed through an elongated confined zone communicating with a narrow elongated opening in the cross-sectional end thereof positioned horizontally to the riser cross-section.

24. The method of Claim 23 wherein the atomized oil feed is discharged from said elongated opening at a velocity above 300 ft./sec. in a horizontal fan-shaped droplet pattern inclined generally upward in said riser.

25. The method of Claim 17 wherein thermal and catalytic conversion of the atomized residual oil feed with the suspended catalyst is accomplished in the riser in a time frame within the range of 0.5 up to 1.5 seconds.

26. The method of Claim 17 wherein:
the catalyst separated from hydrocarbon products and comprising hydrocarbonaceous deposits are passed through two sequential stages of catalyst regeneration, the first stage being sufficiently combustion temperature restricted to produce a CO-rich flue gas whereby hydrothermal degradation of the catalyst in the presence of formed steam is minimized; and the second stage of catalyst regeneration is combus-tion promoted sufficient to produce high temperature CO2-rich flue gases comprising oxygen whereby substantial-ly complete removal of carbon on the catalyst is achieved to produce catalyst particles at a temperature at least equal to or above the residual oil feed pseudo-critical temperature.

27. The method of Claim 17 wherein the catalyst particles provide a surface area within the range of 40 to 100 sq. m/g and temperature conditions sufficient to provide a conversion of the oil feed consistent with the upper curve of figure V.

28. The method of Claim 17 wherein atomization of the residual oil feed to form small droplets less than 100 microns and the temperature of the atomized oil catalyst suspension is sufficient to achieve thermal disintegration in a fraction of a second of feed com-ponent boiling above 1025°F comprising asphalt and asphaltenes to form mono-, di- and tri-aromatic com-ponents in the hydrocarbon product.

29. The method of Claim 17 wherein thermal and catalytic conversion of the highly atomized residual oil feed with the catalyst suspension reduces the temperature of the formed vapor catalyst suspension in the riser to within the range of about 935°F to about 1050°F.

30. The method of Claim 17 wherein the conversion temperature is increased as the asphalt content of the residual oil feed is increased and regeneration of the catalyst is completed at a temperature satisfying the higher asphalt content residual oil feed pseudo-critical conversion temperature.