NO170342B - PROCEDURE FOR CONVERTING A REMAINDER OF RAW OIL WITH FLUIDIZED CATALYST PARTICULARS WITH HIGH TEMPERATURE - Google Patents

Description

The present invention relates to a method for converting a residual part of crude oil with fluidized catalyst particles at a high temperature, where the temperature for contact between the catalyst particles and the atomized residual oil feed is first increased sufficiently to break down the asphalt component in the residual oil and achieve up to 50% thermal conversion of the atomized oil feed, the temperature in a suspension formed with hot catalyst particles being sufficient to achieve thermal disintegration of feed constituents boiling above 552°C and comprising asphalt and asphaltenes to form mono-, di- and tri-aromatic constituents.

In the field, residual oils are identified as reduced crude residual oils, atmospheric column bottoms, topped crude oils, vacuum residues or simply heavy oils. Such high-boiling portions of crude oils are also known to include very heavy-flowing constituents, such as polycyclic aromatic compounds and asphaltenes, which are considered difficult to catalytically crack to form high yields of gasoline and low- and high-boiling hydrocarbon fractions, due to deposition of large amounts coke on the catalyst. Furthermore, metal contaminants in the heavy oil fractions of crude oil including vanadium, nickel, copper, iron, etc. are deposited on and/or in the pores of the catalyst, thereby further poisoning and/or inactivating the catalyst used. In the field, it is considered that the effect of the pre-coking tendencies of the heavy oil fractions plus the effect of the heavy metals is so overwhelming that the resulting product-yield structures are unacceptable from an industrial economic point of view.

In consideration of the known problems in the field of treatment of heavy crude oils and their bottom fractions, including such contaminants, it has previously been proposed to carry out a separation of materials comprising the residual or heaviest fractions or to carry out a preliminary conversion of the heaviest and most undesirable components. Various techniques for carrying out the desired separation, such as vacuum distillation, solvent extraction, hydrogenation or certain thermal cracking processes, have been used in the past in the field of separation or regulation of pollutants. Adsorption of undesirable constituents, especially metallic constituents, on particulate materials with little or no cracking activity has also been used. Thermal cracking, such as delayed and fluid coking, as well as viscosity-breaking operations, have been used to upgrade heavy residual oils. However, the resulting products boiling above 204°C have not proven to be very good starting materials for fluid catalytic cracking due to resulting high concentrations of polynuclear compounds.

Residual oils comprising relatively high-boiling fractions of crude oil obtained as atmospheric column bottoms and/or vacuum column bottoms contained therein are therefore considered by the petroleum industry as problem materials due to the fact that the oil contains large amounts of constituents which are generally considered to have coke-forming tendencies as well as heavy metal constituents. A residual oil can for example contain over 0.6% by weight of a carbon residue, and this property is considered by the industry to contribute to the formation of highly additive coke in a cracking operation and together with the high levels of metals this will act to quickly inactivate the cracking catalyst, which leads to uneconomic dividend results. In the field, there has therefore been a tendency to exclude these materials as raw materials for fluid cracking.

Residual oils for the purposes of the invention may include materials boiling from 204°C to the final end point of crude oil, above 982°C. Within this broad boiling range, the feedstocks may contain light gas oils boiling from 204°C to 371°C, medium gas oils boiling from 316 to 454°C, heavy gas oils boiling from 316 to 649°C and constituents boiling above 649°C up to the final boiling point of the crude oil, including carbon-producing constituents, such as polycyclic aromatic compounds, asphaltenes and metal impurities, as well as whole crude oils. Separately produced raw materials such as those produced by solvent extraction of hydrogenated raw materials can also be included as feed to the process.

The invention is characterized in that

(a) the suspension of high temperature catalyst particles is passed upward through a riser conversion zone (67, 12), (b) the residual oil feed is atomized to a droplet size consistent with or smaller than the suspended high temperature catalyst particles having a size in the range of 20 to 200 pm., (c) the atomized residual oil from step (b) at a velocity in the range of 90 to 390 m/sec. supplied in contact with the upward-flowing,. catalyst particle suspension, the catalyst particles being initially at a temperature that is at least equal to or above the pseudo-critical temperature of the residual oil feed, (d) catalytic conversion of oil vapors formed in the upward-flowing suspension is carried out, whereby the temperature in the suspension is reduced and (e ) vaporous hydrocarbon conversion groups from step (d) are separated from catalyst particles after passing through the riser zone (67, 12) within a time frame that is less than 2 f 5 sols • •

Further preferred features of the invention appear from the subclaims.

The present invention relates to the simultaneous conversion of both the high- and low-boiling components in residual oils with high selectivity to petrol and lighter components and with low coke production. The previous problems in connection with high regenerator and catalyst temperatures are essentially avoided by means of the treatment concepts according to the invention. The present invention uses high catalyst regeneration temperatures and utilizes these high temperatures at the catalyst to achieve the desired cracking reactions, with high conversion and high selectivity to gasoline and products that are gasoline precursors on a review basis, without excessive coke formation. Fluid catalytic cracking is successfully carried out with feedstocks obtained by distillation, solvent extraction and hydrogenation, up to destination areas capable of instantaneous vaporization with hot, regenerated catalyst. Attempts to crack the high-boiling residual hydrocarbon components have not produced the desired results largely due to the fact that the earlier researchers had significant limitations and did not realize that success was only possible if essentially instantaneous and complete atomization was achieved /evaporation at the first contact between the heavy oil feed and very hot catalyst particles at a temperature above the pseudo-critical temperature of the residual oil feedstocks. This means that when the boiling range for added gas oil is increased by mixing in residues, the catalyst temperature must also be increased. In the field, people have previously not realized this and thus ignored these facts, but have deliberately limited the process so that the necessary high catalyst temperatures could not be achieved due to two factors.

(1) Metallurgical limits of the regeneration equipment and

(2) the thermal stability of the catalyst.

In the field of fluid cracking, it is currently agreed that the maximum practical regeneration temperature and, therefore, the resulting regenerated catalyst temperature should be limited to within the range of 704 to 760°C, although temperatures up to 816 and 871°C are indicated. The temperature limitation of 704 to 760°C therefore in effect necessarily limits the oils and materials fed to catalytic crackers to distilled, solvent-extracted and hydrogenated gas oils and materials separated from residues boiling above 551°C to achieve desired conversion levels.

The present invention relates to providing an arrangement of device or equipment and techniques for use, which will, among other things, allow the temperature for catalyst regeneration to be extended up to at least 982°C without excessive thermal weakening of the catalyst activity. The invention also identifies an arrangement of equipment or device which can withstand the severe temperature operations according to the invention.

Thus, for example, the undistilled portion of crude oil boiling from 204°C or higher up to the crude endpoint as provided by peaked crude oils can be cracked under conditions whereby high conversions of the oil feed to lower-boiling materials including gasoline and lighter hydrocarbons are achieved, with gasoline yields -results comparable to previously known gas oil cracking including comparable coke formation. The need for expensive techniques and apparatus for purification or production of raw material in the form of distillation, solvent extraction, hydrogenation or various thermal processes is thus avoided.

The products produced by the method according to the invention will be similar to those obtained by the more conventional, fluid, catalytic cracking operations with relatively pure gas oil. That is C2 and lighter gases, C3 and C4 olefins and paraffins, gasoline boiling from C5 to the end point of 221°C 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 quality that they can be hydrogenated for sale as low sulfur oils, carefully hydrogenated and returned to the fluid catalytic cracker for more complete conversion to gasoline or, preferably, some or all of it can be more completely hydrocracked to produce gasoline-boiling components.

Hydrocracking of the cracked cycle oils obtained as described herein to form gasoline coupled with alkylation of the catalytic C3 and CA results in yields of gasoline per 158.8 1 of 204°C plus crude oil residue fed to the catalytic cracker of up to 125% plus 3-4% propane. Such a total processing sequence is in energy balance if not a net exporter of fuel gas and steam for other applications. The energy balance includes what is required for operation of the crude oil peak fraction.

A very important parameter for successful residual oil cracking is to be sure that the most intimate flash evaporation contact between fluid catalyst particles and heavy oil feed is achieved. That is to say, essentially complete atomization/evaporation of especially the components in the feed which have a high molecular weight significantly improves the conversion operation upon contact with the hot catalyst particles. The remaining high boiling portion of the feed together with the lower boiling gas oil portion should be substantially completely vaporized upon contact with the hot regenerated catalyst at a temperature above the pseudocritical temperature of the feed, because only upon more complete achievement of the atomized vaporization of the feed components more of the feed can be cracked more completely into gasoline-forming components. What is not vaporized remains essentially unconverted, resulting in significant yields of catalytic cycle oils, and/or is adsorbed on the hot catalyst surface and tends to be partially converted to coke, resulting in a loss of gasoline yield and a rapid lowering of the catalyst activity. To achieve the optimal desired conversion, the mixing temperature between oil feed and catalyst must be at least equal to and preferably above the pseudo-critical temperature for the residual oil feed that is supplied, but not so much higher that unwanted over-cracking occurs.

The preheat temperature of the feed, the temperature of the hot regenerated catalyst particles, the cracking activity of the catalyst, the volume of diluent such as steam injected with the feed, the residence time of the hydrocarbon vapor in contact with the catalyst, and the unit operating pressure are the most important operating variables readily available. for the petroleum refiner to achieve the reaction conditions necessary to carry out essentially complete vaporization of the feed and in turn achieve a conversion to gasoline and lighter hydrocarbons with high selectivity in combination with the production of heavier cycle oils of a quality that is suitable for hydrogenation or hydrocracking to form additional material in the gasoline boiling range.

A further desired operating parameter is the provision of an equilibrium temperature in the riser cross-section, essentially instantaneously with properly designed and arranged nozzles for the feed injection. An outlet speed for the feed at the outlet in the range 3 to 390 m/second and preferably approx.

150 m/second is particularly desired, as the feed nozzle outlet is arranged in relation to the cross-section of the riser so that circles of at least equal area of the cross-section of the riser are sprayed on. Each feed nozzle may or may not have a steam jacket if desired to reduce any potential coking of the hydrocarbon feed supplied through the nozzle barrel. A considerable amount

diluent, up to 7% by weight of the steam or other suitable diluent is also injected with the residual oil feed to reduce its flash temperature at equilibrium and provide the best obtainable oil atomization effect with a given nozzle design. Typical amounts of dispersion vapor or diluent for the oil feed vary from 1 to 15% by weight of the feed.

The above-mentioned factors relating to contact and mixing of the atomized oil feed with the fluid catalyst particles are intended to accelerate a mixture thereof relatively evenly and quickly through the evaporation zone in the riser in a minimum time frame and thus provide minimal if any loss of catalyst, whereby rapid heat transfer from the hot catalyst to the heavy atomized oil feed is increased and localized elevated catalyst-to-oil ratios representative of dense catalyst phase conditions are prevented. That is to say, the conditions are chosen so as to ensure dilute phase contact between catalyst and oil feed in the evaporation zone of the riser and co-flow parts thereof, in contrast to localized, tight phase contact conditions in the riser.

A reduced crude heavy oil feed typically contains from 10 to 12% hydrogen in the molecular structure. The lighter fractions generally have a greater content of hydrogen than the heavier fractions. The heavier and larger molecular structures are generally considered to lack hydrogen. The lighter, hydrogen-rich fractions are relatively heat-stable, but are relatively easily cracked catalytically with special catalyst mixtures such as, for example, zeolite-containing catalysts. The heavier or hydrogen-deficient fractions with a high molecular weight in the oil feed are considered thermally unstable and are easily thermally cracked in contact with solids at temperatures in the range from 538 to 982°C. The instantaneous and complete vaporization of heavy fractions discussed above simultaneously promotes thermo-cracking of high molecular weight constituents including some asphaltenes, leading to the eventual successful conversion of more of the total residual oil feed into high grade gasoline and cycle oil - yield with low coke and gas formation. Achieving complete vaporization, atomization of the heavy components of the residual oil feed substantially instantaneously upon contact with the fluid catalyst particles by means of sufficiently high catalyst temperature, low hydrocarbon partial pressure plus the use of a feed nozzle injection system with atomization of the oil is used to prevent localized, dense phase cracking~and thus promote the desired thermo-cracking of some of the large asphaltene-type structures to form low-boiling cycle oils at the expense of producing coke. Failure to do the above will lead to the "coke-shutdown" phenomenon. This is a phenomenon where heavy, hydrogen-deficient molecules are deposited and block the pores for active cracking positions in the catalyst and make the catalyst relatively ineffective in terms of a long, active shelf life for the production of high conversions of the heavy oil feed into desired products from either the light and/or heavy components in the feed.

In the construction and operation of a unit of the type that is conceived and described according to the invention, a basic consideration that is decisive for the operation is that the temperature during the regeneration operation for the fluid catalyst must be substantially carbon-burning unrestricted at least until a temperature of approx. 982°C. While the factors associated with the feed preheat temperature, the riser temperature, the hydrocarbon partial pressure, and the method of injection and distribution in the feed nozzle are important, they are all constrained by practical limitations" and as soon as one of them is optimized in terms of their practical limitations one must take into account the fact that the temperature of the catalyst regenerator must be unrestricted as far as carbon combustion is concerned, so that the temperature can be allowed to rise to a level suitable for the needs of a particular heavy oil feed mixture to thereby achieve the desired , instantaneous, atomized evaporation contact with catalyst particles that promote catalytic cracking and simultaneous thermal cracking of the large, less stable molecular structures in the feed.

Table 1 shows the effect on gasoline and coke formation when a particular atmospheric residue is cracked without a restriction of the regeneration temperature compared to cracking where the regenerator is restricted in terms of temperature. These operations are compared to the cracking of gas oil obtained from the same crude oil after vacuum reduction to remove asphaltene-type constituents and the cracking of the resulting gas oil under conditions previously known in the art.

Table 1 shows that when the regenerator or catalyst temperature is reduced in a residual cracking operation, the petrol yield decreases significantly and coke formation increases correspondingly strongly. It should also be noted that residues can be cracked to higher gasoline yields and with similar coking as is achieved with a conventional gas oil feedstock.

Table 2 emphasizes the same factors where gas oil cracking data is shown compared to 10 vol% and 20 vol% vacuum residues added to the same gas oil feedstock. This table shows that the presence of the residues under optimized conditions results in higher total conversions, higher gasoline yields and equal if not slightly lower coke formation than conventional gas oil cracking.

Analyzes of the products produced when cracking full atmospheric bottoms fractions are compared with gas oils only from the same crude oil show certain other interesting characteristics: (1) The liquid products produced have a higher average hydrogen content. (2) The theoretical octane number in the petrol is significantly higher. (3) The motor octane number in the petrols is significantly higher, which results in a much improved (R+M)/2 grade ring which is important in the production of unleaded petrol. (4) The cracked gas oil products commonly referred to as light and heavy cycle oils and decanted oils have a significantly greater content of di- and tri-condensed aromatic compounds in favor of 4-, 5- and 6-condensed aromatics calls. The high concentration of condensed two- and three-membered aromatic compounds in the cracked product makes these materials very desirable feed materials for hydrocracking to gasoline. (5) The coke produced under optimal operating conditions has a very low hydrogen content. Hydrogen amounts in the range of 3-6% by weight are observed compared to 8-10% by weight which is obtained by cracking operations of gas oil according to the state of the art. The lower hydrogen level in the coke produced can only be explained by the fact that the operating conditions used promote the polymerization of polycyclic compounds attached to the catalyst surface, thereby releasing significant amounts of additional hydrogen for use in hydrogen transfer reactions to achieve the observed, higher hydrogen content in the liquid products. This phenomenon is not observed in gas-oil cracking today. These reactions are exothermic and therefore significantly outweigh the endothermic heat of reaction in the primary cracking reaction. As a result, the total heat of reaction can be reduced by as much as 40 to 50%. This results in lower catalyst circulation rates and consequently lower coke formation. The low level of hydrogen in the coke is also a main factor that must be taken into account when catalyst regeneration is carried out using the embodiment according to the present invention. A high silicon content catalyst comprising one of alumina or magnesium oxide with or without a catalytically active crystalline aluminosilicate or crystalline zeolite and having a fluidizable particle size preferably in the range of 20 to 200 /Ltm can vary significantly in cracking activity and amounts of metal impurities accumulated during the cracking. If the build-up of the metals on the catalyst prevents maintenance of a desired conversion level, a continuous or semi-continuous catalyst cleaning and removal of contaminated catalyst can be used to maintain the desired cracking activity, apart from regeneration of the catalyst. The catalyst content can also be replaced substantially completely or partially as required by changing the conditions, after an extended period of operation or in response to changing the feed mixture as is most appropriate during the operation to achieve the desired conversion of the feed.

Metal poisoning has long been considered a major obstacle to the cracking of residual oils. However, it has been found that these metal contaminants can be passivated to a significant extent at a high regenerator temperature and their adverse effects are noticeably reduced when coke on recycled catalyst is kept below 0.05% by weight. It has been found that approx. 5% conversion is lost per 0.1 wt% coke on regenerated catalyst in addition to the expected coke inactivation, due to metal impurities. However, in the operation according to the invention when cracking reduced crude oil, metals such as nickel, vanadium and iron exhibit some advantageous properties, such as for example activation or increase of dehydrogenation, the hydrogen transfer reaction and promote CO combustion in the regenerator to achieve a lower amount of coke on recycled catalyst without any need for an added promoter. On the other hand, sodium and all the alkali metals are still considered serious contaminants especially for a zeolite-containing catalyst. It has thus been found that desalination of feed is a more economical method of solving the sodium problem than using "sodium drain" removers. With proper desalination of the feed, the sodium content in this can be regulated to well below one part per million.

In order to achieve the desired, high catalyst temperatures required to correctly carry out the successful cracking of oil containing residual oils, special regeneration techniques are required together with specially designed and used apparatus or work equipment. The technique according to the invention of cracking at high temperature promotes relatively large amounts of coke or hydrocarbon material to be deposited on the catalyst during its exposure to the oil feed. Amounts will occur which are normally not below 1% by weight and in some cases above 2% by weight. However, it is particularly desirable to regenerate the catalyst to carbon amounts below 0.1% by weight, preferably to at least 0.05 and more preferably to 0.02% by weight. Regeneration techniques and apparatus or equipment currently used for gas oil cracking are unsuitable for achieving the accuracy of catalyst regeneration required in residual oil cracking for the following reasons: (1) The large amounts of coke allowed to build up on the catalyst is promoted by low catalyst circulation rates, i.e. at low ratios between catalyst and oil. The combination of low catalyst to oil ratios and high carbon amounts automatically leads to high regeneration temperatures, temperatures that are above the normal limits of stainless steel used in regenerators today, in the case of concentration cyclone systems and catalyst withdrawal systems, etc. The temperatures that come into consideration are also above the current temperature limits for today's power recovery systems of 760°C. (2) The catalysts with high activity currently used in catalytic cracking are not structurally heat stable at the high regenerator temperatures according to the invention, if this powerful regeneration is carried out in a single step or even in a multi-stage regenerator where all steps take place in a single container. Two very decisive factors influence the catalyst stability during regeneration. With higher and higher amounts of coke on the used catalysts, higher and higher catalyst particle temperatures develop when the large amount of coke is burned in a single container even if a multi-stage, single-container regeneration is used. These high surface temperatures will in themselves make the catalyst ineffective. Second, the catalyst is rapidly inactivated at high temperatures when steam generated during the coke combustion from the associated molecular hydrogen is allowed to remain in contact with the catalyst as the catalyst reaches its peak temperature.

A special embodiment according to the invention is to carry out the regeneration of the spent catalyst in a system, of two containers, comprising a two-stage catalyst flow system in sequence which is constructed and which is used in such a special way that the difficulties of catalyst regeneration according to the state of the art is overcome. The catalyst regeneration arrangement according to the invention achieves an amount of coke on recycled catalyst preferably less than 0.02% by weight without exceeding undesirable metallurgical limitation or thermostability of the catalyst.

The method for catalytic cracking according to the invention concerns the cracking of high-boiling hydrocarbons which are generally referred to as residual oil and which initially boil at at least 204°C or higher, obtained from crude oil, shale oil and tar sands to produce gasoline and lower- and higher-boiling hydrocarbon components. The residual oil feed is mixed in a riser reaction zone with a highly active cracking catalyst which is recovered from a regeneration zone at a temperature preferably above the pseudo-critical temperature of the feed. The hydrocarbon feed is mixed at a temperature above 204°C with hot, regenerated catalyst at a temperature at least equal to the pseudo-critical temperature of the feed under conditions such that a highly atomized and generally vaporous hydrocarbon catalyst suspension is formed. A suspension separation device or arrangement used in the riser discharge separates from 70 to 90% of the catalyst from the vaporous material. A unique feature of a special suspension separation device used is that it allows relatively high surface vapor velocities during release from catalyst solids in the release vessel before the vapors enter the reactor cyclones for further separation of entrained catalyst solids. Hydrocarbons leaving the reactor cyclones are separated in a co-flow fractionation column. The spent catalyst particles recovered from the cracking operation in the riser are stripped at an elevated temperature in the range of 482 to 593°C, which includes the inactivation of residual carbon in the range of 1.0 to 2.5% or more by weight of coke. The stripped catalyst is fed to a first dense fluid catalyst bed in a first temperature limited catalyst regeneration zone which is maintained below 816°C and more commonly not above 760°C. The combustion of the hydrocarbon-containing material to be carried out in the first, temperature-limited step of the catalyst regeneration has a relatively low temperature which is sufficient to burn all the hydrogen present in the hydrocarbon-containing deposits and from 10 to 80% of the total carbon therein . The regenerator temperature is limited to within the range of 621 to 816°C and preferably to a temperature that does not exceed the hydrothermal stability of the catalyst or the metallurgical limits of a conventional low temperature regenerator operation. Combustion gases rich in CO are recovered from the first stage regenerator and usually directed to a CO reboiler, to generate steam by promoting more complete combustion of the CO available therein. They can be passed through a first power recovery section before being sent to a CO boiler. The mild, limited catalyst regeneration operation serves to limit localized hot spots in the catalyst in the presence of steam generated during the hydrogen combustion so that steam generated will not be at a temperature that substantially reduces the catalyst activity hydrothermally. A partially regenerated catalyst with limited temperature and extensive carbon residue is recovered from the first regenerator substantially free of hydrogen. The hydrogen-freed catalyst comprising residual carbon is passed to a second, separate, unconfined, high-temperature catalyst regeneration operation where the residual carbon is substantially completely burned to CO 2 , thereby achieving an elevated catalyst temperature within the range of 760 up to 982°C in a moisture-free atmosphere.

The second separate step comprising a high temperature catalyst regenerator is designed to limit the catalyst content and catalyst residence time therein at the high temperature while allowing a carbon burn rate to achieve a residual carbon on recycled hot catalyst particles of less than 0 .05% by weight and more preferably less than .02% by weight. Traditionally designed catalyst regenerators used in the prior art in fluid catalytic cracking operations have contained various internal components that are essential for successful operation of the process. These include cyclones, usually in several stages and designed to limit process losses of catalyst, catalyst return lines ("diplegs") from the cyclones to the catalyst bed and various support and clamping devices for the above-mentioned means. A container or similar device plus associated lines to enable collection and extraction of catalyst and passage back to the cracking stage of the process. Necessarily, these various necessary prior art means are of metallic construction, usually stainless steel, and are directly exposed to the combustion temperatures in the regenerator. It is the presence of these exposed metal means in the regeneration combustion zone that limits the maximum temperature that can be achieved or sustained in the regeneration of the catalyst. This generally leads to a maximum, upper operating temperature limit of approx. 760 or 816°C.

The second separate step in the embodiment of the high-temperature catalyst regenerator according to the invention eliminates problems associated with the above-mentioned limitations by placing all exposed metal devices such as cyclones, diplegs, extraction vessel or well and carrier systems outside the combustion zone and" practically outside the regenerator itself. The regenerator container, which is free of all the above-mentioned internal devices in the catalyst combustion zone, is lined with refractory materials as are also all connecting lines, external cyclones and "diplegs". The construction of such a regenerator- combination is considered to be a significant improvement compared to the state of the art. Regenerated catalyst at a desired, elevated temperature is extracted from a relatively dense, fluid catalyst bed in the regenerator in the second stage by means of an extraction line outside the regenerator vessel. The extracted catalyst is fed to a stripping zone before it is carried t il the riser reactor at the desired elevated vaporization temperature defined herein and in an amount sufficient to vaporize the remaining hydrocarbon feed added according to the operational techniques of the invention. Hot combustion gases obtained from the second regenerator are fed to external cyclones for recovery of entrained fine catalyst material before further use such as by being fed to a waste heat recovery system and then to an expansion turbine or released to the atmosphere. Due to the fact that the cyclones in the second regeneration stage with the highest temperature are located externally, certain large and significant advantages are obtained in addition to those cited above. Once the cyclone separators are moved from the interior of the catalyst regeneration device to the exterior, it is convenient to increase the diameter and/or length of the cyclone separator and improve its separation efficiency in such a way that a single-stage cyclone separator can be used instead a two-stage cyclone separator and still achieve improved separation efficiency. This is accomplished in part by the use of a straight, cylindrical tube or "obround" combustion gas transfer tube or one comprising a curved section therein outside the cyclone and generally coinciding with the curvature of the cyclone wall and tangentially connected to the cyclone. This curved flue gas transfer line induces an initial centrifugal motion to the hot suspension of flue gas catalyst particles and thereby initiates concentration of entrained particles and promotes substantially improved cyclone separation efficiency between gases and solids and therefore enables significant changes in cyclone design. But a very significant factor that favors the use of the outer cyclone is in addition that the cyclone's total length can be increased as it does not have to fit within a refractory lined regenerator container with limited dimensions and space and the cyclone separation efficiency can be significantly improved. The net effect of the combustion gas transfer line and cyclone shown above is that a single stage outer cyclone can be made equivalent to a two stage inner cyclone separation system arranged in sequence. Externally located, refractory-clad carbon steel cyclones can be manufactured even when they are used with a regenerator that operates at a temperature above 760°C and up to 982°C. Furthermore, the outer cyclones can be checked during use using an infrared camera and relatively easily repaired before being replaced during a stop or a turnaround.

The process for cracking residual oils according to the invention is considered a significant breakthrough compared to the more conventional FCC technology in the treatment of relatively clean gas oil feeds in that it allows more efficient conversion of the high-boiling residual constituents in the feed which boil above 538°C and more importantly allows the necessary and desired high catalyst temperatures to be used while at the same time providing an operating environment that is not particularly harmful to the catalyst used in the process compared to those found in FCC gas oil operations. The desired final high temperature catalyst regeneration operation of the invention is required to achieve the substantially instantaneous atomization/vaporization of the constituents of the heavy residual oil feed to the catalyst to substantially convert more of the bottoms fractions of a certain amount of crude oil, shale oil etc., or any other high molecular weight liquid hydrocarbon-containing material to form low-boiling materials including gasoline. This is considered a major step forward in the petroleum refining industry and reduces the dependence of the nations of the free world on imported crude oil. It enables the treatment of lower quality crude oils which are cheaper to obtain.

Further advantages achieved by the method for cracking residual oils according to the invention are related to achieving a reduction of energy consumption in the total treatment of the total crude oil and allow to achieve a reduction of both air and water pollution. Some of these savings are achieved by shutting down vacuum distillation units, asphalt extraction units and various heating processes such as delayed coking and thermal viscosity degradation in some cases. These and other prior art processes would normally be used to further treat atmospheric residues.

Typical energy savings in a crude oil unit operation by shutting down a vacuum unit is 0.6 to 1.0% by volume on the crude oil charge. Air and water pollution that is often associated with the above-mentioned omitted processes will also be eliminated.

A further, significant advantage of the residual oil cracking operation according to the invention lies in the fact that a sulfur removal in the range of 60-70% is achieved in the absence of substantial, separate hydrogenation treatment. The H2S formed in the cracking operation can be removed by amine stripping from the vaporous hydrocarbons and fed to a claus unit for recovery of elemental sulfur and sale as such, as opposed to carrying out substantial release as SO2 in regeneration combustion processes.

It will be appreciated by those skilled in the art that conversion of residual hydrocarbons can be carried out in a number of different apparatus arrangements preferably comprising a riser cracking zone equipped with multiple hydrocarbon feed inlets to achieve intimate contact with fluidized catalyst particles and the desired short contact time in a riser contact zone before they are exhausted in a separation zone which may or may not contain a relatively shallow, dense, fluid catalyst bed. Separation of hydrocarbon products from catalyst discharged from the riser can be promoted by mechanical means or any arrangement known in the art and suitable for the purpose. However, in any of these hydrocarbon conversion arrangements, regeneration of the catalyst employed therein is most effectively accomplished when the sequential regeneration technique of the present invention is employed. Therefore, the regeneration concepts and operational techniques specifically contemplated and defined according to the invention are used with considerable advantage in any catalytic cracking operation. Fig. 1 is a diagrammatic sketch in side view of a two-stage catalyst regeneration operation adjacent to and in combination with a riser hydrocarbon conversion operation. A limited cylindrical dimension catalyst recovery and collection zone around the riser outlet includes preliminary catalyst vapor separators expanding outward horizontally from a riser reactor outlet and near cyclone separators located in an upper portion of the collection vessel. Fig. 2 is a diagrammatic sketch in side elevation of a side-by-side catalytic cracking-catalyst-regeneration operation comprising a stacked arrangement of a two-stage catalyst-regeneration equipped with relatively large cyclone separators located outside the vessel for the second stage of a high-temperature catalyst regeneration. Fig. 3 shows in horizontal cross-section an arrangement of a rough-cut separator at the riser outlet in fig. 1 and 2. Fig. 4 is a more detailed sketch of the lower portion of the riser hydrocarbon conversion zone of Fig. 1 and 2 which show in detail the multiple feed inlet nozzles. Fig. 5 graphically shows the conversion achieved for two different systems of atomization of residual oil feed. System two used a more highly atomized feed than system one or the first system. Fig. 6 is a diagrammatic sketch in side elevation of a bottom portion of a riser cracking zone, with a regenerated catalyst inlet line, a fluidizing gas inlet line and a nozzle arrangement which forms a highly atomized oil feed which is then discharged into the riser at a relatively high rate .

In the processing schemes discussed below, apparatus arrangements are provided for carrying out the catalytic cracking of a residual oil at a relatively high temperature to produce materials that boil in the gasoline range and hydrocarbon materials that readily convert to gasoline boiling components and fuel oils. Regeneration of the cracking catalyst used in this way is carried out in particular in a two-stage catalyst regeneration operation which is carried out under temperature-limited conditions in a first, separate regeneration zone to particularly remove hydrogen deposited by hydrocarbon-containing products in the cracking operation . CO formation in the first regeneration zone is not particularly limited and inactivation of the catalyst by steam, which is formed in the hydrogen burning operation, is kept at a desired low level. Hydrogen-free residual carbon is then removed from the partially regenerated catalyst in a second, separate, relatively dense, fluid catalyst system at a more elevated temperature and a sufficiently high oxygen concentration that limits the formation of significant amounts of CO or steam when carrying out the combustion of residual carbon deposits on the catalyst. The temperature in the second catalyst regeneration stage is allowed to rise sufficiently high to provide a desired oil contact temperature. In general, the temperature range for the regenerated catalyst will be from 760 up to 982°C. The regeneration combustion gas from the second regeneration stage will therefore be substantially CO-free if not completely CO-free. Since the combustion gas from the second stage regeneration operation will be C02-rich, such C02-rich gas may or may not be used thereafter for steam generation, stripping of catalyst between steps in the process, and other uses for such gas as desired. The catalyst which is prepared in this way and comprises residual carbon on the catalyst of less than 0.20 weight percent and preferably less than 0.05 weight percent, is returned to the cracking operation.

It will be understood by those skilled in the art that the treatment scheme according to the invention reduces inactivation of the catalyst with high-temperature steam and is an energy-conserving arrangement which is particularly desirable in this age of energy restrictions. That is to say, the two-stage regeneration operation according to the invention reduces the air blower requirement compared to that in a one-stage regeneration operation while more complete coke removal and heating of catalyst particles to a desired elevated temperature is carried out. The first stage of the limited, relatively low temperature regeneration operation is not limited to CO formation where steam is usually formed, and the second stage of the high temperature regeneration operation is carried out in the absence of steam formed where only a residual part of the total carbon, which was originally deposited on the catalyst, is removed. These energy-conserving operating conditions have significant economic advantages for the cracking operation in that a smaller CO boiler can be used to produce process steam to treat the volume of combustion gas obtained in the first regeneration stage operation. The much higher temperature CO2 combustion gas recovered from the separate second-stage regeneration and without any significant combustion-supporting amount of CO can be cooled in a suitable device or heat exchanger which generates additional steam.

The residual oil treatment arrangement according to the invention provides further, significant energy savings by eliminating the addition of 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 that require significant amounts of energy. Steam generated by CO-rich combustion gas, as indicated above, and/or process-derived, normally gaseous hydrocarbons may be used with the feed as a diluent to improve atomization of the feed upon contact with the hot, regenerated catalyst.

The hot catalyst particles obtained as indicated herein and fed to the cracking operation may be at a desired higher temperature than is normally obtained in a one-stage, temperature-limited regeneration operation according to the state of the art. It is also achieved without causing steam and/or hydrothermal destruction to the high temperature catalyst. In addition, the regeneration sequence of the invention more economically adds more heat to the desired vaporization and endothermic catalytic conversion of the residual oil hydrocarbon batch provided herein. <y>further energy conservation benefits are achieved by virtue of the fact that a residual oil comprising objectionable constituents in the crude oil boiling above 551°C is processed to yield more desirable, lower boiling products including products boiling in the gasoline range and gasoline precursors by eliminating satellite operations that consumes a lot of energy, such as vacuum distillation, propane deasphalting, viscosity degradation, delayed coking, feed-hydrogen enrichment operations and combinations thereof as used to date in the petroleum refining industry.

The treatment combinations according to the present invention maintain the desired equilibrium catalyst in the system by replacing catalyst that is circulated in the system with catalyst particles with less metal coating that have been obtained, for example as fresh catalyst or as equilibrium catalyst from other cracking operations with clean feed. Thus, part of the catalyst particles separated from the first stage regeneration operation at low temperature or the second stage regeneration operation or both as normal catalyst loss or by means of special extraction devices can be replaced with newer catalyst particles with suitable high cracking activity which have smaller amounts of deposited metal contaminants.

The operational concepts according to the present invention are applicable to the construction of grassroots systems, and can be adapted to many different refining operations that exist now and which comprise a single regeneration operation in combination with a hydrocarbon conversion operation such as e.g. a riser cracking or a dense fluidized bed cracking operation. In any of these operations, it is believed that the regeneration temperature is necessarily limited to a first step at low temperature and a second, separate regeneration operation at high temperature in order to obtain the advantages of the present invention, particularly in terms of energy conservation and elimination of hydrothermal destruction of the cracking catalyst at high temperature in the presence of generated steam.

It is immediately clear that the sequential catalyst regeneration concepts according to the invention enable a significant improvement of any hydrocarbon conversion process, either in that the hydrocarbon fed to the cracking operation comprises difficult asphalt constituents and metal impurities or is simply a high coke producing batch material that is relatively free of significant amounts of metal contaminants and/or asphaltenes. However, as indicated herein, the benefits of the process innovations of the invention are enhanced as additional treatments of the crude hydrocarbon feed to remove these materials are reduced.

It will also be apparent to the person skilled in the art that the present, temperature-limited, catalytic cracking and regeneration apparatus can be modernized to carry out the operations according to the invention at a higher temperature with a minimum of capital outlay and stoppage of the processes, whether what is being modernized is a stacked, one -stage reactor-regenerator arrangement, a side-by-side, single-stage reactor-regenerator arrangement or one of the more modern units comprising a hydrocarbon conversion zone in a riser reactor in combination with a dense catalyst bed in open communication with a catalyst -regeneration operation with an upper riser.

As an example, reference must now be made to fig. 1 where spent catalyst particles recovered from a stripping operation after a residual oil-hydrocarbon conversion are fed through conduit 1 into a first densely fluidized bed of catalyst 3 inside the regeneration vessel 5. The regeneration vessel 5 is identified here as a relatively low temperature regeneration vessel where the temperature is kept below 816°C, and the concentration of oxygen supplied with regeneration gas in line 7 and distributor 9 is limited to limit the prevailing regeneration temperature, as desired, especially during combustion of hydrogen and carbon deposits associated with hydrocarbon deposits from residual oil- cracking. The combustion carried out in the first stage regeneration operation, as identified herein, is carried out under conditions such that steam and a CO-rich regeneration combustion gas are formed. The combustion gas thus formed is passed through cyclone separators represented by separators 11 and 13 to separate entrained catalyst particles therefrom before extraction through line 15. Catalyst which is thus separated from the CO-rich combustion gases by the cyclones is returned to the catalyst bed by suitable "diplegs" . In the regeneration vessel 5, it is particularly intended that the regeneration conditions are chosen so that the catalyst is only partially regenerated by removal of carbon deposits so that sufficient residual carbon remains on the catalyst to achieve high catalyst particle temperatures above 760 or 816°C upon more complete removal by combustion with an excess of oxygen - containing regeneration gas.

In the arrangement in fig. 1, the first stage of the catalyst regenerations in vessel 5 is carried out at a relatively low temperature, preferably limited to not exceeding 760 or 816°C and producing a CO-rich combustion gas. Partially regenerated catalyst in the absence of significant amounts of vapor-forming hydrogen is withdrawn from the catalyst bed in the first regeneration step through the withdrawal line 17 for passage to a nearby stripping zone or container 19. A downward-flowing, relatively dense, fluid mass of partially regenerated catalyst is obtained to flow through the container 19 in countercurrent to aeration and stripping gas introduced through line 21. The aeration gas is preferably relatively inert, at least in terms of inactivating the partially regenerated catalyst, and will preferably significantly limit the transfer of moisture forming components with the catalyst to a second stage of catalyst regeneration which is carried out at a temperature above 816°C. The air gases suitable for use in zone 19 include C02, combustion gas which is substantially free of moisture, nitrogen, dry air and combinations thereof.

The partially regenerated catalyst is extracted from the container 19 by means of a standpipe 23 which communicates with the catalyst transfer line 25 and the riser line 27. Gas, such as e.g. air, nitrogen, CO 2 and mixtures thereof, may be added to aid in the transport of catalyst through the gas inlet lines 29 and 31. A series of gas inlet lines represented by line 29 may be used in the line bend between lines 23 and 25 and downstream therefrom in the transport line to assist in the transport of catalyst through it. Regeneration gas, such as air or an oxygen-enriched gas vapour, is introduced by line 31 for contact with partially regenerated catalyst in riser line 27. Line 27 is discharged into a bed of catalyst 33 which is retained in the lower part of a regeneration zone or container 35 of relatively large diameter . Additional regeneration gas, such as air, is introduced to the lower part of the catalyst layer 33 by line 37 which communicates with an air distribution device which is suitable for the operation at high temperature which is to take place.

In the second stage of the regeneration operation carried out in regenerator 35, the temperature is within the range of 760 to 982°C and sufficiently much higher than in the first regeneration stage to effect substantially complete removal of residual carbon not removed in the first step. The regenerator container 35 is a container which is lined with refractory material and essentially free of exposed internal metals and cyclones so that the desired high temperature regeneration can be carried out. In this high temperature operation, residual carbon on the catalyst is preferably reduced to below 0.05 weight percent and a high temperature CO 2 combustion gas stream is recovered by means of external cyclone separators. Relatively large single-stage cyclone separators are preferably used, which are refractory-lined containers. The outer overpressure section 39 is equipped with radiating arms from which cyclone separators are suspended or arranged as shown graphically in the drawing by arms 41 and 43 which are connected to cyclones 45 and 47 respectively. On the other hand, the cyclone arrangement in fig. 2, which is discussed below, is used with regenerator 35. Catalyst which is thus separated from combustion gas at elevated temperatures up to 982°C is returned by means of supplied "diplegs". A high temperature CO 2 -rich combustion gas is recovered separately from each cyclone separator for further use as desired, or as a combined, hot combustion gas stream 49 for generating steam in equipment not shown. It will be clear to the person skilled in the art that more than one cyclone separator can be used together in sequence, and the number of cyclones in the sequence will be determined by the size of each and the arrangement used.

The catalyst regenerated in the second stage of the regeneration and heated to a temperature above the regeneration temperature in the first stage by burning residual carbon to a level below 0.1 weight percent and preferably below 0.05 weight percent carbon is withdrawn from bed 33 by means of line 51 and is led to a nearby container 53. The withdrawn catalyst is preferably aerated with moisture-free air introduced via line 55 or at least substantially moisture-free air in the nearby catalyst collection zone or container 53. Air gas is withdrawn through line 57 and is led to the upper part of the container 35. Hot, regenerated catalyst at a temperature above 760°C is drawn out from the zone 53 by a standpipe 59 comprising a flow control valve 61. The hot catalyst is then led through the transport line 63 to the lower bottom part 65 in a riser hydrocarbon conversion zone 67. Venting or lifting gas, such as light hydrocarbons recovered from a co-current recovery operation for light compounds, not shown, or another suitable fluidizing gaseous material is fed below the catalyst inlet to the riser via line 60.

In the hydrocarbon conversion operation specifically contemplated, the hot, low residual carbon catalyst is caused to flow upward and be mixed with a series of hydrocarbon streams in the riser cross-section supplied through a series of feed nozzles 71 arranged close to but spaced inward from the riser's refractory lining wall section. More particularly, the riser wall is provided with an expanded wall section 73 through which the plurality of horizontally spaced feed nozzles pass upwardly and inwardly through it. A dilution gas such as gas, light hydrocarbons or a mixture thereof is added with the residual oil supplied to increase its atomized dispersion and vaporized intermixing with the high temperature fluid catalyst particles. The riser section near the outlet of the feed injection nozzles is preferably expanded into a pair of larger diameter risers through which the vaporized oil and catalyst suspension passes. To further assist in achieving the desired intermixing and essentially instantaneous vaporization of the added residual oil components, a series of small, atomized oil feed streams are mixed with the supplied upstream catalyst. The vaporized hydrocarbon material comprising cracking products mixed with suspended particles of catalyst passes upwards through the riser 67 for discharge from the upper end of the riser through a suspension separator. Various devices which are used within the state of the art can be used for this purpose. The initial suspension separator referred to as a coarsening separator at the end of the riser hydrocarbon conversion zone appears as an outwardly expanding appendage from the riser resembling butterfly wing appendages in association with relatively large openings in the riser wall near its closed upper end. I.e. the roughing separator at the end of the riser when viewed from the side and top resembles a butterfly-shaped device. The appendages are open in their bottom portions to the surrounding container 87 for the discharge of hydrocarbon vapors which are substantially separated from catalyst particles. Pages 77, fig. 3, are solid, substantially vertical panels and the ends 79 near the wall of container 87 are solid, substantially vertical, curved panels. The top of each appendage is covered by a sloping roof 81 to minimize retention of deposited catalyst and coke particles thereon. The slope of the roof panel is preferably at least equal to the angle of repose of the catalyst used and more preferably greater to avoid retention of the catalyst on the suspended roof. Other arrangements which are known from the state of the art and which allow high vapor discharge rates can be used to effect initial separation of hydrocarbon vapor catalyst suspension which is discharged from the upper end of the riser.

In operation, the vaporous materials comprising hydrocarbons and diluent mixed with suspended catalyst are discharged through openings 75 in the riser and expanded within each of the appendage chambers A and B to reduce the velocity of the mixture, change the direction of the suspension components, and concentrate catalyst particles separated from vaporous material along the vertical, curved outer side wall 79 in each appendage. The catalyst particles thus concentrated or separated fall down the wall and are collected as an annular layer of catalyst 83 below comprising a catalyst stripping zone. Vaporous materials separated from catalyst particles pass downward through the open bottom in each appendage near the riser wall and from there flow upwards into one or more, such as a series of cyclone separators represented by separator 85 in the upper part of vessel 87. Hydrocarbon vapors, diluent and gaseous stripping material separated from the catalyst are withdrawn through conduit 89 for passage to a product recovery facility not shown. Catalyst that is separated in one or the many cyclones is fed by means of "diplegs" to the catalyst bed 83. Stripping gas such as e.g. steam is supplied to bed 83 through line 91. Stripped hydrocarbons join with product hydrocarbon vapors leaving the coarsening separator and entering the cyclone separator arrangement. The stripped catalyst comprising hydrocarbon-containing product from residual oil cracking and metal impurities is extracted through line 93 comprising valve 95 and is led from there by means of line 1 to the first regeneration stage.

In fig. 2 shows an arrangement of apparatus which differs from the arrangement of apparatus shown in fig. 1 in that the separate regeneration containers 2 and 4 are stacked on top of each other on a common axis with the highest temperature regenerator 4 as the top vessel. In addition, the hot combustion gases are drawn from regenerator 4 through refractory lined pipes 6 and 8 which are arranged to resemble a "T" with a large cyclone separator 10 in open communication with and suspended from each horizontal arm 8 of the "T" pipe section. In this apparatus arrangement, the riser reactor 12 for conversion of hydrocarbon with several feed inlets represented by means 14 and coarse separation device for the suspension 16 are shown to be the same as discussed in connection with fig. 1. However, it is desirable to use this system or other arrangements in combination with one, two or more large cyclone separators 18 in an upper portion of the catalyst collection vessel 20 near the riser discharge inside or outside the collection vessel 20. An arrangement similar to shown with regard to the upper regenerator 4 in the apparatus can also be used.

In the apparatus arrangement in fig. 2, hot, regenerated catalyst is supplied at a temperature above 760°C in line 22 and at least equal to the pseudo-critical temperature of the residual oil feed to the bottom of the riser 12 where it is mixed with lift or aeration gas introduced through line 24 to form an upward-flowing suspension . Catalyst thus aerated or suspended is then contacted with a series of atomized oil feed streams through a series of feed nozzles 14. In a particular embodiment there are 6 horizontally spaced nozzles (Fig. 4) extending through the riser wall near an expanded section thereof in the manner shown. Steam or other diluent may be injected along with the feed to atomize the dispersion as discussed above.

A vaporous hydrocarbon catalyst suspension passes upwardly through riser 12 for discharge through roughing attachment 16 in a manner discussed in connection with FIG. 1. Hydrocarbon vapors separated from catalyst particles pass through one or more cyclone separators 18 for further recovery of catalyst before the hydrocarbon-containing vaporous material is passed through line 26 to a product fractionation step not shown.

Catalyst which is separated by the device 16 and cyclone 18 is collected as a catalyst layer in a lower part of the container 20. Stripping gas, which e.g. steam, is introduced into the lower bottom part of the layer through line 28. Stripped catalyst is led through line 30 with valve 72 to a catalyst layer 32 which is regenerated in container 2. Regeneration gas, such as e.g. air is introduced to a bottom part of the bed 32 through the line 34 which communicates with an air distribution ring 36. The regeneration zone 2 is kept at a relatively low temperature below 816°C and under conditions chosen to achieve a partial removal of carbon deposits and all the hydrogen that is associated with deposited hydrocarbon-containing material from cracking. In this operation, a CO-rich combustion gas is formed which is separated from entrained finely divided catalyst by means of one or more cyclones, such as e.g. cyclones 38 and 40, in parallel or sequence arrangement with another cyclone. CO-rich combustion gases are recovered from the cyclone separator through line 42 for use as discussed herein.

Partially regenerated catalyst is withdrawn from a lower portion of bed 32 for transfer upward through riser 44 for discharge into the lower portion of a dense fluidized bed of catalyst 46 in an upper, separate, second stage of catalyst regeneration with an upper contact surface 48. Regeneration gas , like for example. air or oxygen-enriched gas, is supplied to the bottom inlet of the riser 44 through a hollow "stem plug" valve 54 comprising flow control device 74. Additional regeneration gas, such as e.g. air or oxygen-enriched gas, is supplied to the bed 46 through line 50 which communicates with air distribution ring 52. The regeneration vessel 4 is a vessel which is lined with refractory material which is freed from metal attachments as discussed above so that the temperature therein is not limited by metal attachments and can be allowed unlimited to reach a higher temperature or exceed 816°C and go up to as much as 982°C or that required to complete carbon combustion. In these catalyst regeneration environments, the second, unlimited temperature regeneration step substantially completely removes residual carbon remaining in the catalyst after the first, temperature-limited regeneration step. The temperature in the regenerator 4 is thus not particularly limited to an upper level, except that it is limited by the amount of carbon to be removed inside and that sufficient oxygen is supplied to provide CO2-rich combustion gas without combustion-supporting amounts of CO by burning residue -the carbon on the catalyst. The C02-rich combustion gas thus generated goes together with slightly entrained catalyst particles from the dense, fluid, catalyst bed 46 into a more dispersed catalyst phase above this from which the combustion gas is extracted through conduits 6 and 8 which communicate with more than one cyclone 10 The line 8 is either straight or horizontally curved before tangential communication with cyclone 10. The curvature of line 8 preferably partially coincides with the curvature of the cyclone wall so that an initial centrifugal separation of entrained catalyst particles is carried out in line 8 and before introduction into the cyclone separator. Catalyst particles are separated from the hot combustion gases with a high degree of efficiency by means of this arrangement and the efficiency of the cyclone separators can be further optimized by extending the conical bottom of the cyclone. Catalyst particles which have been separated in this way are fed through refractory-clad shafts 56 to the catalyst bed 46 in the high-temperature regenerator. C02-rich combustion gases without combustion-supporting amounts of CO are recovered through line 58 from the cyclone for use as described herein. Catalyst particles regenerated in zone or vessel 4 at a high temperature up to 982°C are withdrawn through refractory lined line 60 for passage to vessel 62 and thence through line 64 equipped with valve 66 to line 22 which communicates with riser reactor 12 as discussed above. Air gas is introduced to a lower part of the container 62 through line 68 which communicates with a distribution ring inside the container 62. Gaseous material extracted from the top of the container 62 through line 70 enters the upper, dispersed catalyst phase in the container 4.

The apparatus arrangement in fig. 2 is a compact, side-by-side system arranged in pressure balance to achieve the desired circulation of catalyst particles and the particularly desired treatment conditions as discussed herein. The operation of the system is improved by the use of spherically shaped particles of catalyst smaller than 200 µm and an average particle size can be selected within the range of 50 up to 120 µm. It is intended to modify the system in fig. 2 by placing outer cyclones on the vessel 20 at openings into it around the upper end of the outlet of the riser conversion zone. The outer cyclone separation device may also be arranged substantially similar to that shown at conduits 6 and 8 and cyclone 10 in regenerator 4 and may be attached to a vertically shortened container 20 and used in place of the inner cyclone 18. Kata -lysator particles separated in this way could be transferred by means of suitable diplegs which communicate with the layer of collected particles in the lower part of the container 20 which is in contact with stripping gas introduced through line 28.

As an example, reference is now made to fig. 4 where there is shown in more detail an arrangement of apparatus intended for separate supply of hot, regenerated catalyst and a residual oil feed to a lower part of the riser zone for hydrocarbon conversion 65 in fig. 1 or the riser 12 in fig. 2. The residual oil is fed through a series of pipes 71 which are either straight or curved. The tubes can be enclosed in a tube which forms an annular zone for a vapor blanket if desired. In the arrangement in fig. 4, hot catalyst is supplied at an elevated temperature as indicated above and above the residual oil's pseudo-critical temperature through a line 63 which is lined with refractory material to a bottom part 65 in the riser's hydrocarbon conversion line 67, each of which is lined with refractory material. Catalyst air or fluidizing gas is supplied through line 69 to a gas distributor in the bottom part of the riser. A hot suspension of catalyst and lift gas is formed in the bottom of the riser which then passes upwards through the riser into an expanded section thereof for contact with residual oil feed supplied through a series of feed inlet pipes 71. The oil feed supplied through pipe 71 is mixed with a diluent like for example. steam or light hydrocarbons supplied through line 109, whereby the partial pressure of the supplied hydrocarbon feed is significantly reduced. Steam to the casing for the oil supply nozzle is supplied to an annular section formed around tube 71 through a steam inlet 111. A number of such jacketed nozzles are arranged horizontally spaced from each other and discharge into the cross-section of the riser and there are preferably six such nozzles arranged to achieve high temperature contact between fluidized catalyst particles and oil which is added to achieve essentially instantaneous vaporization-atomization of the residual oil feed. The nozzle arrangement empties into an expanded section of the riser after passing through section 73 which in one arrangement is seen as a half pipe section in the riser wall which is filled with refractory material. The nozzles are arranged to discharge into equal area diameter portions of the riser cross-section to enhance intimate atomization-evaporation contact with the upward-flowing suspended catalyst particles rising through the riser. The multiple oil feed pipe outlets are preferably arranged in a circle and spaced from the riser wall within the expanded riser cross-section to achieve the desired mixing of oil feed with the hot catalyst particles sufficient to achieve substantially instantaneous vaporization of the supplied residual oil. It is clear that various prior art techniques including atomizing nozzles can also be used to ensure more complete and substantial atomization of the added residual oil feed for more intimate vaporizing contact with the hot catalyst particles at a temperature of at least 760°C and within the range of 816 to 982° C.

The residual oil cracking process according to the invention relies on very high temperature catalyst regeneration to provide a very low residual carbon catalyst at a temperature exceeding the pseudo-critical temperature of the residual oil fed to achieve, essentially instantaneous evaporation of the supplied oil charge. Another important aspect of the combination operation is to support the catalyst activity by replacing some of the metal-contaminated catalyst with new catalyst and carrying out an initial regeneration of the catalyst under limited temperature conditions that minimizes steam inactivation of catalyst particles during regeneration. The cracking according to the invention is essentially an operation with a review of the hydrocarbon feed in that there is no return of an oil hydrocarbon product to the cracking operation. On the other hand, light, normally gaseous hydrocarbon product, process generated steam and C0_ . , , , ... ^ ^ ^ ^ 2 are returned and used as indicated above. Alkylation of formed olefin constituents suitable for this purpose in a co-current plant not shown and hydrocracking of formed hydrocarbon product material and boiling higher than gasoline may further be carried out to produce additional gasoline and/or light oil products. The hydrocarbon product that boils at a higher temperature than gasoline can be hydrogenated to remove sulfur and nitrogen to produce an acceptable fuel oil material.

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

The methods discussed below are more specifically aimed at achieving a high degree of product selectivity in the cracking operations discussed above by paying more particular attention to another operational variable. This second operating variable applies in particular to achieving atomization of the heavy oil feed, as well as the nozzle injection system which is more suitable for the intended purpose.

In this method of operation, it is particularly desirable at the point of contact between a highly atomized oil feed and fluidized catalyst particles to achieve substantially instantaneous heat evaporation and catalyst conversion of atomized oil droplets. The suspension of hydrocarbon vapor and catalyst increases in velocity as it flows upward through the riser and provides a dilute catalyst concentration in the suspension within the range of from 0.016 to 0.16 kg/dm<3> and more commonly not exceeding 0.08 kg/dm<3>. The faster the instantaneous vaporization and conversion of the oil feed is achieved, the less of a pressure drop is experienced near the inlet of the atomized feed and co-current contact with upflowing catalyst particles through the riser reactor.

It is observed when working as described here, that the product selectivity for the converted residual oil by thermal and catalytic means can be varied significantly depending on the degree of atomization of the heavy oil feed which is brought into contact with catalyst particles at high temperature to achieve evaporation of the supplied oil feed. An important operational variable has to do in particular with the utilization of a suitable atomizing nozzle inlet device for the feed which provides a high degree of atomization of the residual oil feed and contact at a relatively high speed with upwardly flowing, hot catalyst particles which are suitable for the purpose. Thermal and catalytic conversion of the evaporated oil feed into desired products is thus achieved within a very short time frame accompanied by a reduction of the temperature in the formed suspension as described here. In this preferred operating environment, a highly atomized oil feed is supplied to the cracking zone in the riser at a velocity in excess of 91.5 m/sec. up to 396.4 m/sec. and is dispersed in a fan-shaped pattern of 10 or 15 degrees in the vertical direction of 90 to 120° or more in the generally horizontal direction relative to the cross-section of the riser. This helps ensure more intimate contact between an upwardly flowing fluid suspension of finely divided, hot catalyst particles with an initial particle concentration density in the range of 0.16 to 0.56 kg/dm<3>. This velocity of a formed suspension is substantially instantaneously velocity spread to form an upwardly flowing hydrocarbon vapor/dispersed catalyst particle phase suspension. The rate at which this is achieved minimizes the pressure drop resulting from the formation of a relatively high velocity suspension of product vapor and catalyst which is discharged from the riser reactor at a rate in the range of 18.3 - 36.6 m/sec. The catalyst concentration in the resulting suspension can be varied significantly as desired to optimize the conversion of the hydrocarbon feed. The catalyst concentration in the suspension may be less than 0.08 kg/dm<3> and may be as low as 0.016 or 0.032 kg/dm<3> at the riser outlet.

When essentially instantaneous vaporization of the oil droplets is achieved, as discussed herein, rapid thermal and catalytic conversion thereof is achieved in a short vertical space of the riser reactor within a time frame of very short duration. This may be associated with a small pressure drop in a vertical part of the riser above the supply inlet of up to 1.5 m, but no more than 3 m of this. The formed suspension temperature rapidly falls or is reduced to a level within the range of 500 to 538 or 566°C, measured below or at the riser outlet. In connection with instantaneous evaporation of the atomized oil supply, up to approx. 50% heat conversion of the atomized oil feed along with catalytic conversion thereof to form high yields of gasoline, gasoline precursors and cycle oils. It is observed that the cracking reaction combination takes place in the riser within a very short time frame within the range of 0.5 sec. up to 2.5 sec. and the essentially complete desired conversion that optimizes yield of gasoline product is assumed to take place from 0.5 sec. up to 1 or 1.5 sec. High yields of gasoline and light cycle oil products are achieved when a low pressure drop occurs inside the riser reactor above the inlet point for the atomized feed and when the contact between hydrocarbon vapors in the riser is limited to less than 1.5 sec. with suspended catalyst particles.

In developing the residual oil conversion concept expressed herein, it is further observed that atomizing the oil to a small droplet size consistent with or smaller than the fluid catalyst particle size used and comprising an average particle size selected from the range of 20 to 150 µm also helps achieve rapid vaporizing the residual oil feed at a relatively high rate to form a suspension thereof at low pressure drop in the riser reactor for flow through it discussed herein.

In the graphic arrangement in fig. 5, a comparison is made in terms of conversion achieved between a first system of residual oil atomization and a second system. The second system comprises the feed nozzle arrangement in fig. 6 and achieves a much higher degree of feed atomization than that achieved with the first system. Fig. 5 is essentially self-explanatory and clearly shows a significant improvement in catalytic conversion achieved between the first and second atomization systems even though each had the same thermo-conversion level. In the first system of fig. 5 which included less than desired conditions in terms of atomization of the residual oil feed, the result is reduced catalytic conversion to the desired gasoline product and thus less than desired product selectivity even if a heat conversion of at least 50% is achieved. This observation is compared to a second atomization nozzle system for the residual oil feed which provides a more highly atomized oil feed which in droplet size matches the catalyst particle size. This ensures a more complete steam distributed residual oil feed for intimate, instantaneous mixing with suspended catalyst particles at a high temperature sufficient to form a highly dispersed phase suspension therewith. It is shown graphically in fig. 5 that each of these treatment systems achieves equal heat conversion but different overall product selectivity. The second feed atomization system of FIG. 6 provides a higher total conversion which is attributed to the improved catalytic conversion operation of the atomized oil. When the catalyst activity is identified on the basis of catalyst surface area times the ratio of catalyst to oil, it is found that the second atomization feed system in FIG. 6 consistently gives higher conversion levels with the more highly atomized feed as shown graphically. In this hydrocarbon conversion environment of highly atomized and vaporized residual oil, it is preferred that the average surface area of the catalyst is maintained at a level of at least 40 m<2>/g by continuous or intermittent replacement by catalyst particles with a higher surface area and preferably the surface area of the catalyst is maintained at a higher level up to 80 or 120 m<2>/g depending on the desired hydrocarbon formation and the economy of the catalyst replacement.

The exact mechanism by which the improved residual oil conversion, product selectivity and yield is achieved by System 2 compared to System 1 as shown above is not fully understood, except that the more highly atomized oil feeds distributed generally horizontally over the cross-section of the riser using the nozzle devices in fig. 6 apparently results in very rapid vaporization of the fine oil droplets for intimate, vaporized contact with the high temperature fluid catalyst particles at a temperature equal to or above the pseudo-critical temperature of the atomized residual oil feed.

It therefore appears that, in the relatively strong contact environment between residual oil and catalyst in system 2, highly atomized oil droplets that are equal to or smaller than an average catalyst particle size of 100 £tm and thus uniformly dispersed at the pseudo-critical temperature of the feed, will be essentially completely vaporized in less than a fraction of a second if not thermally and catalytically, essentially completely converted. It is clear that such operating conditions comprising a highly atomized oil feed in contact with catalyst particles as defined above have a decidedly improved effect on the conversion and selectivity of the product obtained.

In a catalytic cracking operation that includes the operation defined here, the phenomenon of carrying out asphalt degradation and to at least tri-aromatic compounds and lower forms is new compared to the state of the art. This operational concept is particularly associated with the achievement of heat conversion at high temperature or breakdown of the asphalt component. This requires elevated catalyst temperatures above those normally used and can be achieved using the regeneration technique discussed above to effect the desired reduction of the asphalt molecules.

In this new residual oil catalytic cracking operation, it is considered critical to a successful operation to achieve relatively instantaneous degradation of the asphalt constituents and structures therein essentially at the feed injection point within a very short time frame of no more than a fraction of a second and before or simultaneously with the catalytic cracking of atomized gas oil components being particularly promoted. The breakdown of the asphalt component in the feed will necessarily enrich the gas oil part of the feed in terms of aromatic components comprising di- and tri-aromatic compounds and larger ring compounds, but preferably does not include substantial or significant amounts of aromatic compounds with 4 and 5 rings.

The driving force to achieve disintegration or molecular reduction in asphalt is essentially heat or temperature oriented and the obstacle to this can be traced back to the heat transfer rate from catalyst particles with high temperature to the asphalt molecule. The desired heat transfer rate increases exponentially as the particle or droplet size of the initiated oil spray decreases or decreases. When very hot catalyst particles come into contact with overatomized oil, the desired breakdown of the asphalt molecule into mono-di- and tri-aromatic compounds will be carried out with high efficiency, without condensation of polyaromatic rings as observed in coking processes that lead to high coke production. In this environment with asphalt degradation, the time frame for the implementation must be of sufficiently short duration so that the structure of the cracking catalyst is not unnecessarily masked by coke levels so high that normal conversion of the lighter gas oil components in the feed is prevented or unnecessarily limited. Thus, the main role of a catalyst to oil ratio outside of asphalt degradation is to support a mixing temperature that is sufficiently high or elevated to provide normal, endothermic, catalytic conversion of the 538°C minus crackable portion of the gas oil constituents in the residual oil feed. In this regard, it should be understood that a small catalyst circulation rate of extremely hot catalyst or low temperature catalyst particles will not provide this desired conversion goal as effectively as a greater circulation rate of catalyst particles with a sufficiently elevated temperature that provides a desired ratio between catalyst and oil .

It is observed that there is a catalyst temperature which is most suitable and desirable for carrying out the desired conversion of a given, asphaltic, residual oil feed material. This is referred to and is identifiable with the residual oil's pseudo-critical temperature. Furthermore, the conversion temperature must be increased when the percentage content of asphalt in the feed increases to achieve the desired, rapid or instantaneous evaporation of the heavy oil feed in the presence of heat catalyst particles to achieve the desired product selectivity and low coke yields. In this regard, the desired catalyst temperature occurs almost automatically in the special two-stage regeneration operation defined above when the asphalt content of the feed increases and when the catalyst-regenerator temperature in the second stage is not limited by burning or incineration of carbon deposits. This is because the coke level in the used catalyst increases with a higher asphalt content in the feed. This higher boiling catalyst fed to catalyst regeneration will cause the regenerated catalyst temperature to rise to higher levels. Regeneration of catalyst particles with higher than normal coke levels may cause some concern in protecting catalyst activity.

The process combinations identified here rely on rapid, high temperature degradation of the asphaltene constituents in a highly atomized residual oil feed as discussed above along with recovery and disposal which help to improve the yield of gasoline and cycle oil. The breakdown of the asphalt component in particular in the residual oil feed is of such a nature that significant amounts of di- and tri-aromatic compounds are provided together with some high-boiling, polycyclic compounds. These constituents that generally resist conversion in catalytic cracking respond to hydrocracking as hydrogenated products of lower ring configuration and favor mono- and di-cyclic rings that contribute to gasoline and/or low, poor, high cetane distillate material formation. In addition, the hydrogenated, high-boiling product material from hydrocracking is a hydrogen donor material for the residual oil feed when returning to the catalytic cracking operation.

The catalytic cracking of the residual oil catalyst regeneration process defined here is a significant breakthrough in catalytic cracking technology that economically removes metallurgical limitations on the regenerator equipment and the temperatures achieved. It performs molecular reduction of asphalt which helps to further improve gasoline yields and light fuel oil yields, especially when they are synergistically related to hydrogen operations involving hydrocracking of polycyclic constituents in the cycle oil product from the catalytic cracking step. The process combination described here can respond to and be adapted to changes in the properties of the feed raw material. Another important aspect is the discovery that no unusually elaborate instrumentation or control systems are required to maintain a smooth and stable operation.

The rate at which a residual oil is converted to gasoline, lower and higher boiling hydrocarbons by means of a high temperature catalyst as expressed above is further increased when greater emphasis is placed on the following operating parameters. It is achieved e.g. significantly improved conversion results when the riser cracking system in fig. 2 as described above, is modified so that it comprises the feed nozzle arrangement from fig.

6 for the production and supply of highly atomized droplets of residual oil feed in fan-shaped contact at high speed with an upwardly flowing suspension of fluid catalyst particles at high temperature in the riser. In this operation, it is desirable that the rising catalyst suspension has a concentration in the range of at least 0.16 up to 0.56 kg of catalyst particles per cubic decimeter to ensure rapid and intimate contact with the added, highly atomized oil charge identified here.

The improved riser conversion operation of residual oil according to the invention is based substantially on the supply of a highly atomized residual oil feed as identified here, at a relatively high velocity in contact with catalyst particles having an average particle size in the range of 20 to 150 or less /m such as e.g. not more than 120 µm and comprising a surface area in the range of 40 to 120 m<2>/g. Catalyst particles with an average particle size selected within the range of 60 to 120 µm are particularly relevant. The atomized oil feed droplet may be equal to or smaller than the average catalyst particle. However, it is preferred that the atomization of the oil feed produces a droplet size that coincides with the catalyst particle size distribution or is smaller than the average particle size.

A very significant aspect of a successful riser cracking operation of residual oils is associated with the achievement of rapid thermal cracking of especially asphaltenes, catalytic cracking of crackable, vaporous constituents and rapid achievement of a suspension temperature reduction, which will significantly reduce the thermal product degradation in the form of high coke yields. In an effort to more specifically identify the improved residual oil riser conversion operation of the invention, the following was developed.

It is clear from Table 1 that a reduced crude oil or residual oil atomized to a droplet size of 100 µm or less as specifically desired here requires a very short vaporization time equal to or less than 9 milliseconds when the catalyst particles are brought into contact. with the oil at a temperature that is at least equal to the pseudo-critical temperature for the oil feed.

The catalyst regeneration-riser cracking for the treatment of residual oil and reduced crude oils as identified herein is concerned with achieving a high degree of desired product selectivity at the expense of producing coke and less desired gaseous material.

It is clear from the above discussion that at the instant of atomized charge injection and contact with a suspension of high temperature catalyst particles as identified herein, all subsequent reactions occur within a very short time frame in the range of milliseconds up to 1 second, but less than 2 seconds depending on operating parameters such as temperature, feed atomization, catalyst activity expressed in terms of surface area and contact time. Further, all of these conditions undergo a transfer during the passage through the riser reactor in a manner conducive to obtaining the final desired products and comprising gasoline, cycle oil and an amount of coke consistent with providing a thermally balanced operation. A particularly important aspect to be avoided seems to be associated with prolonged contact between the products from the cracking comprising material of the type dixjg tri-cyclic aromatic compounds, and high temperature catalyst, since this tends to contribute to product breakdown and coke formation. A very rapid temperature reduction after evaporation and cracking of the feed which does not exceed 2 seconds and is preferably less than 1 second therefore seems to be important to optimize the yield of petrol and cycle oil products. This is particularly achieved by following the improved riser operations expressed above. A rapid temperature reduction to within the range 510 to 566°C is desirable.

The preferred operating concepts expressed above are followed by a rapid molar expansion of vaporous products from the cracking at the elevated temperature originally employed, which itself contributes to achieving a significant increase in the velocity of the suspension formed simultaneously with catalyst particle acceleration in within a fraction of a second. A cracking operation of a residual oil that is carried out within the operational concepts that have been identified minimizes radial misdistribution of the suspension in the riser and thus avoids catalyst agglomeration and other localized catalyst particle concentrations along the riser wall which lead to an undesired high ratio between catalyst and oil.

The rapid residual oil feed evaporation and its conversion under relatively high velocity conditions as described above is found to be associated with a very low pressure drop operation inside the riser in a limited, vertical space above the feed nozzle inlet which is less than approx. 3 meters. These low pressure drop conditions have been found to be the opposite of what occurred and was identified with poor mixing of oil feed and catalyst in original portions in a riser up to 1.5 or 3 meters from it. It is thus clear that a high degree of oil feed atomization is an essential operating parameter and its distribution over the riser cross-section is a pattern that promotes intimate, instantaneous vaporization contact with catalyst particles for conversion thereof as identified herein. A fan-shaped pattern of 10 or 15° in the vertical direction by 80 to 150° in a direction perpendicular to this has been found to provide a high degree of intimate contact.

The depletion of atomized oil supply at a high speed of approx. 150 m/sec. more or less as intended here, has not been found to be harmful to the process. I.e. that it has been established that the use of an atomized oil discharge velocity at the nozzle outlet of 390 m/sec. quickly changes at a distance from there of 2.5 cm to 200 m/sec. and to just 100 m/sec. at a distance of 5 cm from the nozzle tip. At 15 cm, the speed is reduced to 39 m/sec. The treatment concepts according to the invention for carrying out riser cracking of a residual oil supply are carried out within a very short time frame of approx. 2.5 or no more than 1.5 sec. depending on the residual oil feed supplied and the temperature provided by the catalyst, when preheating the feed below 427° and more commonly not above 260 to 316°C is used.

In the arrangement in fig. 6, the riser bottom section 82 has a smaller diameter than an upper part 80 thereof and is connected to a transfer section 84. Fluid catalyst particles are supplied to the lower diameter lower part of the riser through line 86. Fluidizing gas is supplied to the riser below the catalyst inlet line 86 via line 88 which is communicates with a distribution ring inside the riser cross-section. The line 90 which is equipped with the valve 92 allows extraction of catalyst from the bottom of the riser. The fluidizing gas supplied through conduit 88 may be gaseous products from catalytic cracking from which gasoline precursors are separated or steam may be used. A fluidizing material in gaseous form such as e.g. a low grade naphtha can be used alone or in admixture with recycled product hydrocarbon gases as a transfer fluidizing medium for effecting smooth direction change in fluid upward flow of hot catalyst particles as a suspension upward in a bottom portion of the riser up to the feed nozzle outlet in the expanded riser section. Instrument branches can be placed in the riser wall and especially above the transfer section 84 to determine pressure drop and temperature in the operating system.

The feed injection nozzle comprises a cylinder 94 with a narrowed slotted end opening 96 which is encased in a cylindrical heat dissipative jacket 98. The nozzle passes through the riser wall near but above the riser transfer section at an upwardly inclined, desired angle. An angle of approx. 30° has been found to be satisfactory in this particular embodiment. The oil supply is supplied to the atomization section in the nozzle with or without a diluting gaseous material, such as e.g. steam, light hydrocarbons, or other suitable material to reduce the partial pressure and/or viscosity of the oil supplied through conduit 100 in communication with the orifice 102 so that the heavy oil discharged through the orifice will impinge on a flat surface 104 to form small droplets, which are further cut to a finer droplet size by a high velocity gaseous material fed through 106 and communicating with orifice constriction 108. The atomized heavy oil feed of desired droplet size coinciding with the fluid catalyst particle size noted above, which is formed outside the riser reactor, passes through a cylindrical portion of the nozzle system at high velocity for discharge from the end thereof through a slotted opening 96. A single, narrowed slot opening can be used to produce a fan-shaped pattern of atomized oil droplets in the cross section of the riser. For example, there can be two slits, in a parallel arrangement at 90° in relation to each other. It is preferred that two or more such nozzle-system arrangements are used and placed equidistant from each other horizontally around the periphery of the riser. E.g. there may be 3, 4 or more such nozzle systems. It is also contemplated to vertically offset two or more of the discussed nozzle arrangements in a confined vertical space of the riser reactor above the transfer section to provide a highly turbulent, intimate contact section for highly atomized oil feed in contact with upwardly flowing particles of catalyst at the desired elevated temperature which is at least the pseudo-critical temperature of the oil supply.

It is intended to locate the oil feed nozzle arrangement discussed in an upper portion of the riser reactor wall that is no more than 3 meters below the riser outlet so that product vapor from thermal and catalytic cracking can be rapidly separated from catalyst by discharge from the riser upper outlet.

Having thus generally discussed the many operational concepts that contribute to the new combination operation according to the invention for upgrading heavy oil streams such as e.g. residual oil flows, reduced crude oils, tapped crude oils etc. and described specific examples relating thereto, it is to be understood that no unnecessary limitations shall be imposed thereon, except as defined by the following claims.

Claims (15)

1. Method for converting a residual part of crude oil with high-temperature fluidized catalyst particles, where the temperature for contact between the catalyst particles and the atomized residual oil feed is first increased sufficiently to break down the asphalt component in the residual oil and achieve up to 50% thermal conversion of the atomized oil feed, the temperature of a suspension formed with hot catalyst particles is sufficient to achieve thermal disintegration of feed constituents boiling above 552°C and comprising asphalt and asphaltenes to form mono-, di- and tri-aromatic constituents, characterized in that (a) the suspension of high temperature catalyst particles is passed upward through a riser transformation zone (67, 12), (b) the residual oil feed is atomized to a droplet size consistent with or smaller than the suspended high temperature catalyst particles by a size in the range 20 to 200 /im. , (c) the atomized residual oil from step (b) at a velocity in the range of 90 to 390 m/sec. supplied in contact with the upward-flowing, catalyst particle suspension, the catalyst particles initially being at a temperature that is at least equal to or above the pseudo-critical temperature of the residual oil feed, (d) catalytic conversion of oil vapors formed in the upward-flowing suspension is carried out , whereby the temperature of the suspension is reduced and (e) vaporous hydrocarbon conversion groups from step (d) are separated from catalyst particles after passing through the riser zone (67, 12) within a time frame of less than 2.5 sec.. 2. Method according to claim 1, characterized in that a discharge rate is used for the atomized oil supply of approx. 150 m/sec. 3. Method according to claim 1, characterized in that the mixing speed upon contact between atomized oil feed and the upward-flowing catalyst suspension limits the pressure drop in the riser (67, 12) downstream thereof to not exceed 0.21 kg/cm<2>. 4. Method according to claim 1, characterized in that the process conditions are chosen so that the pressure drop that occurs 3 m downstream from the atomized oil inlet (71, 14) is no more than 0.7 kg/cm<2> 5. Method according to claim 1, characterized in that atomized residual oil feed having a droplet size consistent with or smaller than a catalyst particle size selected within the range of 20 to 150 /Lim average particle size is supplied to the riser conversion zones (67, 12) as a series of separate fan-shaped droplet dispersions for intimate contact with upwardly flowing fluid particles of catalyst. 6. Method according to claim 1, characterized in that the average particle size of the catalyst is selected within the range of 20 to 120 µm and the atomized oil droplets are equal to or less than 100 µm. 7. Method according to claim 1, characterized in that atomization of the oil feed is carried out in at least 2 successive stages outside the riser cracking zone and the atomized droplets are then transferred through a narrowed, elongated confined zone which communicates with a slotted outlet opening (96) at the end thereof which is located inside in the cross-section of the riser (12) for emptying thereto. 8. Method according to claim 7, characterized in that the atomized oil feed is discharged from the slotted opening (96) in a fan-shaped droplet pattern which tends generally upwards in the riser. 9. Method according to claim 1, characterized in that thermal and catalytic conversion of the atomized residual oil feed is carried out within a time frame in the range of 0.5 to 1.5 seconds. 10. Method according to claim 1, characterized in that: catalyst that is separated from the riser suspension comprises hydrocarbon-containing deposits that are removed in two successive stages of catalyst regeneration, the first stage (5) being sufficiently temperature-limited to produce CO-rich combustion gas and minimize hydrothermal decomposition of formed steam and the second step (35) of the catalyst regeneration takes place at a temperature above the temperature of the first step to produce CO2-rich combustion gases in the presence of an excess of oxygen-containing gas sufficient to substantially completely decarbonizing the catalyst to produce catalyst particles at a temperature equal to or above the residual oil feed pseudo-critical temperature. 11. Method according to claim 10, characterized in that the catalyst regeneration operation is carried out in a stacked arrangement (2, 4) close to the riser conversion operation and the riser (12) has a larger diameter in an upper part than a lower part above the inlet for the atomized oil supply. 12. Method according to claim 1, characterized in that the atomized residual oil feed is brought into contact with catalyst particles having a surface area within the range of 40-100 m 2 /g under conditions to provide conversions thereof in accordance with. it. the upper curve in fig. 5. 13. Method according to claim 1, characterized in that the residual oil feed is atomized into droplets with a size of less than 100 µm. 14. Method according to claim 1, characterized in that the residual oil is atomized to a droplet size of 100 µm or less and that high-temperature evaporation thereof is sufficient to be carried out in less than 1 sec. 15. Method according to claim 1, characterized in that thermal and catalytic conversion of the highly atomized residual oil feed with suspended high temperature catalyst reduces the temperature of the formed vapor-product suspension to within the range of 492 to 566°C.