Abstract: A process for producing a high VI/low volatility lubricating oil basestock and a lubricating oil basestock prepared by said process. The process comprises subjecting the raffinate from a solvent extraction step to a two step, single stage hydroconversion process wherein the first step involves severe hydroconversion of the raffinate followed by a cold hydrofinishing step.

Abstract: A process for producing a lubricating oil basestock having at least 90 wt. % saturates and a VI of at least 105 by selectively hydroconverting a raffinate from a solvent extraction zone in a two step hydroconversion zone followed by a hydrofinishing zone, and a lubricating oil basestock produced by said process.

Abstract: The invention relates to a process for converting cycle oils produced in catalytic cracking reactions into light olefin and naphtha. More particularly, the invention relates to a process for hydroprocessing a catalytically cracked light cycle oil in order to form a hydroprocessed cycle oil containing a significant amount of tetralins. The hydroprocessed cycle oil is then re-cracked in an upstream zone of the primary FCC riser reactor.

Abstract: The present invention is a fluidized catalytic cracking process that incorporates a zoned riser reactor. The process provides an in-situ method for feed upgrading in a riser reactor. The process assists in the removal of undesirable contaminants, such as nitrogen, from FCC feedstocks.

Abstract: The invention is related to a two step process wherein the first step comprises cracking an olefinic naphtha resulting in a cracked product having a diminished total concentration of olefinic species. The second step comprises hydroprocessing at least a portion of the cracked product, especially a naphtha fraction, to provide a hydroprocessed cracked product having a reduced concentration of contaminant species but without a substantial octane reduction.

Abstract: A process for producing propylene from a catalytically cracked or thermally cracked naphtha stream is disclosed herein. The naphtha stream is contacted with a catalyst containing from about 10 to 50 wt. % of a crystalline zeolite having an average pore diameter less than about 0.7 nanometers at reaction conditions which include temperatures from about 500° C. to 650° C. and a hydrocarbon partial pressure from about 10 to 40 psia. A separate stream containing aromatics may be co-fed with the naphtha stream.

Abstract: The present invention is a fluidized catalytic cracking process that incorporates a zoned riser reactor. The process provides an in-situ method for feed upgrading in a riser reactor. The process assists in the removal of undesirable contaminants, such as nitrogen, from FCC feedstocks.

Abstract: The present invention is a fluidized catalytic cracking process that incorporates a zoned riser reactor. The process provides an in-situ method for feed upgrading in a riser reactor. The process assists in the removal of undesirable contaminants, such as nitrogen, from FCC feedstocks.

Abstract: The present invention is a fluidized catalytic cracking process that incorporates a zoned riser reactor. The process provides an in-situ method for feed upgrading in a riser reactor. The process assists in the removal of undesirable contaminants, such as nitrogen, from FCC feedstocks.

Abstract: A process for producing polymers from olefins selectively produced by a two stage process for selectively producing C2 to C4 olefins from a gas oil or resid is disclosed herein. The gas oil or resid is reacted in a first stage comprising a fluid catalytic cracking unit wherein it is converted in the presence of conventional large pore zeolitic catalyst to reaction products, including a naphtha boiling range stream. The naphtha boiling range stream is introduced into a second stage comprising a process unit containing a reaction zone, a stripping zone, a catalyst regeneration zone, and a fractionation zone. The naphtha feed is contacted in the reaction zone with a catalyst containing from about 10 to 50 wt. % of a crystalline zeolite having an average pore diameter less than about 0.7 nanometers at reaction conditions which include temperatures ranging from about 500 to 650° C. and a hydrocarbon partial pressure from about 10 to 40 psia.

Abstract: A two-stage process for converting petroleum residua and other low value oils to high valued gasoline blendstocks and light olefins. The first stage is comprised of a thermal process unit containing a reaction zone comprised of a horizontal moving bed of fluidized hot particles operated at temperatures from about 500 to 600° C. and having a short vapor residence time, and the second stage is comprised of a catalytic conversion zone operated at a temperature of about 525° C. to about 650° C., and also having a short vapor residence time, preferably shorter than that of the first stage reaction zone.

Abstract: A high efficiency FCC process obtains the necessary regenerated catalyst temperature for a principally thermal cracking stage by cracking a light feedstock such as naphtha or a middle distillate in a first riser that principally performs thermal cracking and then cracks a heavy FCC feed in a second riser with a blend of catalyst from the principally thermal cracking step and recycle catalyst from the heavy feed to provide the necessary coke content on the catalyst that will produce high regenerated catalyst temperatures. The high temperature of the regenerated catalyst in the first riser provides a convenient means of cracking naphtha under high severity conditions and then using the remaining activity of the contacted catalyst for the principally catalytic reaction of the heavier feed. A separate thermal cracked product may be recovered from an intermediate blending vessel downstream of the first riser.

Abstract: C.sub.2 to C.sub.4 olefins are selectively produced from a gas oil or resid in a two stage process. The gas oil or resid is reacted in a first stage comprised of a fluid catalytic cracking unit wherein it is converted in the presence of conventional large pore zeolitic catalyst to reaction products, including a naphtha boiling range stream. The naphtha boiling range stream is introduced into a second stage comprised of a process unit containing a reaction zone, a stripping zone, a catalyst regeneration zone, and a fractionation zone. The naphtha feedstream is contacted in the reaction zone with a catalyst containing from about 10 to 50 wt. % of a crystalline zeolite having an average pore diameter less than about 0.7 nanometers at reaction conditions which include temperatures ranging from about 500 to 650.degree. C. and a hydrocarbon partial pressure from about 10 to 40 psia.

Abstract: A process for producing a lubricating oil basestock having at least 90 wt. % saturates and a VI of at least 105 by solvent extracting a feedstock to produce a raffinate, solvent dewaxing the raffinate, selectively hydroconverting the solvent dewaxed raffinate in a two step hydroconversion zone followed by a hydrofinishing zone and a dewaxing zone.

Abstract: A process for selectively producing C.sub.2 -C.sub.4 olefins from a catalytically cracked or thermally cracked naphtha stream. The naphtha stream is contacted with a catalyst containing from about 10 to 50 wt. % of a crystalline zeolite having an average pore diameter less than about 0.7 nanometers at reaction conditions which include temperatures from about 500 to 650.degree. C. and a hydrocarbon partial pressure from about 10 to 40 psia.

Abstract: The invention provides a process for improving the conversion of a hydrocarbon feedstock to light olefins comprising the steps of first contacting the hydrocarbon feedstock with a light olefin producing cracking catalyst and subsequently thermally cracking the unseparated stream to produce additional ethylene. Preferably the zeolite catalyst is selected from the group consisting of ferrierite, heulandite, phillipsite, faujasite, chabazite, erionite, mordenite, offretite, gmelinite, analcite, ZSM-5, ZSM-11, ZSM-25, gallium silicate zeolite, zeolite Beta, zeolite rho, ZK5, titanosilicate, zeolites having a silica to alumina molar ratio within the range of about 2.0:1 to 2000:1 ferrosilicate; zeolites such as those described in U.S. Pat. No. 4,238,318; borosilicate zeolites such as those described in Belgian Pat. No. 859656; zeolites designated by the Linde Division of Union Carbide by the letters of X, Y, A, L; zeolites such as those described in U.S. Pat. No.

Abstract: A continuous pyrolysis and decoking process and apparatus is described for the production of acetylenic compounds, in which hydrocarbons and steam are circulated in at least one tube (31) of a steam cracking reactor (30) and steam is circulated in at least one tube (32) of that reactor. The hydrocarbon effluent and steam then circulate in at least one row (1) of a pyrolysis reactor (40) and the decoking effluent comprising steam circulate in at least one other row (2) of that reactor (4) to effect decoking. A set of valves V1, V2, V11, V12 is used to alternate the pyrolysis step path and the decoking step path. The temperature in the steam cracking furnaces is lower than that in the pyrolysis reactor.

Abstract: A process for producing a lubricating oil basestock having at least 90 wt. % saturates and a VI of at least 105 by selectively hydroconverting a raffinate from a solvent extraction zone in a two step hydroconversion zone followed by a hydrofinishing zone and a dewaxing zone.

Abstract: In a process and apparatus for visbreaking a heavy hydrocarbon feedstock in the liquid state, whereby the feedstock is brought to an appropriate temperature to cause cracking of at least part of the hydrocarbons present, and is then introduced into the bottom of a soaker (3) wherein it travels from bottom to top, and is then discharged from the top of said soaker (3) and directed to a fractionation unit, the improvement wherein a preferably inert gas is injected into the hydrocarbon feedstock inside the soaker (3), in the vicinity of the soaker side walls, at least at the bottom of the soaker (3) and the gas is injected upward along the side walls of the soaker (3) and flows from bottom to top along said walls co-currently with the hydrocarbon feedstock.

Abstract: A two-stage process for obtaining a substantial amount of olefinic product from a residua feedstock. The first stage is comprised of a thermal process unit containing a reaction zone comprised of a horizontal moving bed of fluidized hot particles operated at temperatures from about 500.degree. to 600.degree. C. and having a short vapor residence time, and the second stage thermal conversion zone operated at a temperature of about 700.degree. C. to about 1100.degree. C., and also having a short vapor residence time.

Abstract: A two-stage process for obtaining a substantial amount of olefinic product from a residua feedstock. The first stage is comprised of a thermal process unit containing a reaction zone comprised of a horizontal moving bed of fluidized hot particles operated at temperatures from about 500.degree. to 600.degree. C. and having a short vapor residence time, and the second stage thermal conversion zone operated at a temperature of about 700.degree. C. to about 1100.degree. C., and also having a short vapor residence time.

Abstract: A technique of preparing oil from waste plastics, especially the one to which a mechanism of an extrusion molding machine is applied, is provided wherein an effective control of a decomposition process is conducted in order to effectively prevent the generation of carbon and to efficiently obtain recovered products having a desired composition. For this purpose, reactors 1a, 1b, and 1c having built in carrying means 3a, 3b, and 3c, respectively are used as connected in stages, in which reactors waste plastics are heated and decomposed into oil as carried. One or a series of reactors are used as a unit to form a melting zone and a decomposing zone in the carrying direction.

Abstract: There is provided a process and a device with a convection zone (A) and a radiation zone (B) in a furnace (10), whereby the process includes: a first stage of precracking a feedstock of light hydrocarbons (1) and a second stage of final co-cracking of the mixture that is composed of this precracked light feedstock (7) and a feedstock of heavy hydrocarbons (2). The process further includes: separate heating of the two feedstock streams (1 and 2) in the convection zone (A), in which the preheating temperature of each feedstock stream remains below the initial cracking temperature in each case; precracking (5) of the preheated light hydrocarbons; mixing of precracked light hydrocarbon stream (8) while a mixed stream (9) is formed; intense heating of mixed stream (9) to a temperature that is higher than the initial cracking temperature by virtue of the fact that the mixture is introduced into the radiation zone (B) of the furnace (10); and cooling (15) of cracked gases outside the furnace (10).

Abstract: Disclosed is a catalytic cracking process which includes more than one catalytic cracking reaction step. The process integrates a hydroprocessing process step between the catalytic cracking reaction steps in order to maximize olefins production, mid-distillate quality and naphtha octane level in the cracked products. Preferably, a first cracked hydrocarbon product is obtained from a first cracking stage and separated into a mid-distillate and gas oil containing fraction having an initial boiling point of at least 300.degree. F., the distillate and gas oil containing fraction is hydroprocessed, and a naphtha fraction and a gas oil containing bottoms fraction of the hydroprocessed material are cracked in a second cracking stage.

Abstract: Disclosed is a catalytic cracking process which includes more than one catalytic cracking reaction step. The process integrates a hydroprocessing step between the catalytic cracking reaction steps in order to maximize olefins production, distillate quality and octane level of the overall cracked product. Preferably, the hydroprocessing step is included between the reaction stages, and a portion of the hydroprocessed products, i.e., a naphtha and mid distillate fraction, is combined with cracked product for further separation and hydroprocessing. It is also preferred that the first catalytic cracking reaction step be a short contact time reaction step.

Abstract: A cyclone and process for fluidized catalytic cracking of heavy oils is disclosed. Gas and entrained solids are added around a clean gas outlet tube in a cyclone body. Solids and some gas are withdrawn via a solids outlet and discharged into a catch chamber. Some of the gas discharged with the solids into the catch chamber is returned to the interior of the cyclone body via an opening in the cyclone. Chaotic reflux of gas back into the cyclone via the solids outlet is eliminated. The device may be used as an FCC regenerator third stage separator or to improve other gas/solid separations.

Abstract: The instant invention relates to a process for the production of olefins from plastic waste, which comprises adjustment of a desired viscosity by thermal pretreatment of plastic waste in a temperature range of 350.degree. to 550.degree. C. and thermal treatment of the product obtained by the thermal pretreatment in a temperature range of 700.degree. to 1100.degree. C.

Abstract: Disclosed is a catalytic cracking process which includes more than one catalytic cracking reaction step. The process integrates a hydroprocessing step between the catalytic cracking reaction steps in order to maximize olefins production, distillate quality and octane level of the overall cracked product. Preferably, the hydroprocessing step is included between the reaction stages, and a portion of the hydroprocessed products, i.e., a naphtha and mid distillate fraction, is combined with cracked product for further separation and hydroprocessing. It is also preferred that the first catalytic cracking reaction step be a short contact time reaction step.

Abstract: The invention relates to a process for the conversion of petroleum hydrocarbons in the presence of catalyst particles in a fluidized phase in an essentially upflow or downflow tubular reaction zone. The process includes at least one stage of steam cracking of at least one light hydrocarbon fraction and a stage of catalytic cracking of at least one heavy hydrocarbon fraction. The steam cracking is carried out by contacting the light hydrocarbons and a quantity of steam equal to at least 20 percent by weight in a fluidized bed of the catalyst particles, the resulting temperature ranging from 650.degree. to 850.degree. C. The catalytic cracking of the heavy hydrocarbons is carried out by injection of the effluents from the upstream section of the reaction zone into the catalyst suspension in such a way that the temperature of the mixture ranges from 500.degree. to 650.degree. C. and is then reduced to a temperature ranging 475.degree. to 550.degree. C.

Abstract: The invention relates to a process for catalytic cracking and the associated apparatus in which the cracking reaction takes place in two substantially vertical and successive reaction zones, the loads being introduced into the first zone where it circulates from the top downwards, then at least a part of the product obtained is introduced into a second reaction zone in which it circulates in an ascending fashion. A supplementary hydrocarbonated phase is advantageously introduced into the product entering the second zone. The invention applies particularly to heavy loads, with a U-shaped apparatus.

Abstract: This invention relates to a process for cracking waste polymers in a fluidized bed reactor to produce vaporous products comprising primary products which can be further processed, eg in a steam cracker to produce olefins, characterized in that the vaporous products are treated to generate a primary product substantially free of a high molecular weight tail having molecular weights >700 prior to further processing. The removal of the high molecular weight tail minimizes fouling and prolongs the lifetime of the reactors used for further processing.

Abstract: A process and apparatus for low cracking or recracking of liquid hydrocarbons with FCC catalyst containing 0.2 to 1.5 wt % coke is disclosed. FCC naphtha, or a thermally or hydrocracked naphtha, contacts spent FCC catalyst in a naphtha recracking reactor for limited conversion to lighter products and an increase in octane number. Spent catalyst from the recracking reactor can be recycled to the FCC reactor without stripping or regeneration. Naphtha recracking products are preferably cooled, then used as an absorbent to recover gasoline boiling range products from the FCC main column overhead vapor. Use of spent catalyst and controlled conversion conditions minimizes overcracking of the light liquid and minimizes formation of heavy ends.

Abstract: The present invention provides a process for hydrodelayed thermal cracking in combination with hydrostripping, which comprises feeding crude oil from a surge tank to a crude oil stripper via a feed line; separating the crude oil into a lighter fraction and a heavier fraction in the crude oil stripper; subjecting the lighter fraction to hydrodesulfurization; feeding the heavier fraction from the crude oil stripper to a first storage tank; hydrothermally cracking the heavier fraction for at least 10 minutes under a hydrogen pressure in the first storage tank; introducing a bottom residue of the first storage tank into a second storage tank or the feed line, and subjecting a cracked and vaporized fraction of the first storage tank to hydrodesulfurization; hydrothermally cracking the residue introduced into the second storage tank under a higher hydrogen pressure than the hydrogen pressure of the first storage tank; subjecting a portion of a bottom residue of the second storage tank to hydrodemetallization, hydro

Abstract: The invention relates to a process for the conversion of petroleum hydrocarbons in the presence of catalyst particles in a fluidized phase in an essentially upflow or downflow tubular reaction zone, said process comprising at least one stage of steam cracking of at least one light hydrocarbon fraction and a stage of catalytic cracking of at least one heavy hydrocarbon fraction.The steam cracking is carried out by contacting the light hydrocarbons and a quantity of steam equal to at least 20 percent by weight in a fluidized bed of the catalyst particles, the resulting temperature ranging from 650.degree. to 850.degree. C.The catalytic cracking of the heavy hydrocarbons is carried out by contacting them with the effluents from the upstream section of the reaction zone and the catalyst suspension in such a way that the temperature of the mixture ranges from 500.degree. to 650.degree. C. and is then reduced to a temperature ranging from 475.degree. to 550.degree. C.

Abstract: Methods for the fluidized catalytic cracking of plural hydrocarbon feedstocks in a riser reactor are disclosed. The processes generally comprises contacting a relatively light hydrocarbon feedstock in a first reaction zone with a first catalyst stream comprising spent catalyst, contacting a relatively heavy hydrocarbon feedstock in a second reaction zone with a second catalyst stream comprising freshly regenerated catalyst, and introducing at least a portion of the effluent from the first reaction zone into the second reaction zone. The first reaction zone and the second reaction zone preferably comprise first and second riser reaction zones, respectively.

Abstract: The invention is directed to steam-cracking in a fluid bed reaction zone, of a charge of hydrocarbons having at least two carbon atoms per molecule.In this process the charge (3) circulates with steam (2) and inert solid particles, heated at a temperature T.sub.1 from 500.degree. to 1,800.degree. C., through at least one enclosure (7). A gas effluent is separated from the particles in the enclosure and fed to a quenching zone (8) opening into said enclosure. Said effluent is circulated with cooling second solid particles which are at a temperature T.sub.2 lower than T.sub.1 and at most equal to 800.degree. C. A steam-cracking effluent is then recovered through line (15).This process can be used in petrochemistry, particularly for producing ethylene and propylene.

Abstract: A fluid catalytic cracking (FCC) process and apparatus which employs relatively more elutriatable catalyst particles comprising intermediate pore zeolite, particularly ZSM-5, and relatively less elutriatable catalyst particles comprising large pore zeolite, preferably zeolite Y. The process and apparatus employ a first stripping vessel which also separates a more elutriatable first portion of catalyst from a less elutriatable second portion of catalyst. The more elutriatable first portion passes to a second stripping vessel, and subsequently recycles to a fluid catalytic cracking reactor riser. The second portion of less elutriatable catalyst passes from the first stripping vessel to a fluid catalytic cracking regenerator vessel and, after being regenerated, recycles to the reactor riser. The more elutriatable first portion contains a higher ratio of intermediate pore catalyst particles to large pore catalyst particles than does the second portion.

Abstract: The invention is a pyrolysis furnace for cracking heavy oils to olefins. The furnace includes a convection zone and a radiation zone. In parallel streams, the heavy stream and a stream diluent are heated in the convection zone to the point of partial thermal cracking while in the other stream a lighter oil and steam are cracked to produce olefins. The hot, olefinic light stream is then mixed with the heated heavy stream and further cracked in the radiation zone.

Abstract: Waste oil is treated in a tubular reactor having a length of up to and in excess of 2 km in a plurality of stages each of which involves heating the product to a different temperature and maintaining the product at a different pressure. The released fractions are evacuated from the path for the flow of waste oil and are immediately condensed and distilled to yield a variety of products from oil having a low boiling point to coke. One or more withdrawn fractions can be treated (for example, hydrogenated) in one or more discrete tubular reactors. The heating can involve raising the temperature of waste oil to several times the critical cracking temperature, and the regulation of pressure can involve a reduction of pressure to less than 1 mbar. The last stage of the reactor can be cleaned by abrasive particles, by vibration at high frequencies and/or by acceleration of the conveyed stream to an elevated speed.

Abstract: Liquid fuel products are produced at least partially from coal by passing into a progressive flow catalytic cracking zone a mixture stream of coal and carbometallic oil, forming mobile hydrogen within said zone under conditions including vapor residence time of up to about 10 seconds, at 900.degree.-1,400.degree. F., and total pressure of about 10 to about 50 pounds per square inch absolute introducing said mobile hydrogen into said mixture stream; contacting said stream with zeolite cracking catalyst to produce liquid products while laying down coke on said catalyst; and separating said coked catalyst from said liquid products.

Abstract: A catalytic cracking process is provided which comprises:(a) cracking a first heavy hydrocarbon feed in a first riser in the presence of a mixed catalyst composition comprising, as a first catalyst component, an amorphous cracking catalyst and/or a large pore crystalline cracking catalyst and, as a second catalyst component, a shape selective medium pore crystalline silicate zeolite, to provide gasoline boiling range material and one or more light hydrocarbons; and,(b) cracking a thermally treated second heavy hydrocarbon feed in a second riser in the presence of said mixed catalyst composition and in admixture with a gasiform material contributing mobile hydrogen species and/or carbon-hydrogen fragments at the reaction conditions employed to provide gasoline boiling range material in increased yield and/or of higher quality.

Abstract: In the catalytic processing of aromatic hydrocarbon compounds, a hydrocarbon oil is successively contacted at aromatic saturation conditions with a catalyst in a first reaction zone and contacted at a lower temperature with a second portion of the catalyst in the same reactor or in multiple reactors.

Abstract: A process of thermally cracking a heavy petroleum oil wherein the heavy petroleum oil is treated successively in a cracking furnace and then in a perfect mixing type tank reactor. The thermal cracking in the cracking furnace is performed at a temperature at the outlet of the cracking furnace of 450.degree.-520.degree. C. with a conversion of at least 60-75% of the overall conversion rate while the thermal cracking in the tank reactor is performed at a temperature of 400.degree.-450.degree. C. a pressure of from ambient pressure to 1 kg/cm.sup.2 for a period of time of less than 30 minutes but not less than 10 minutes while feeding steam having a temperature of 435.degree.-700.degree. C. to the tank reactor in an amount of 8-20% by weight of the heavy petroleum oil fed to the cracking furnace.

Abstract: There is provided a catalytic cracking operation featuring a single riser reaction zone having a lower and an upper section wherein a variety of hydrocarbon conversion reactions takes place, a stripping zone in which entrained hydrocarbon material is removed from catalyst and a regeneration zine in which spent cracking catalyst is regnerated, which comprises:(a) thermally cracking a C.sub.

Abstract: A catalytic cracking process is disclosed which comprises:(a) thermally and/or catalytically cracking a hydrogen-rich hydrocarbon feed in the lower region of a riser reactor in the presence of a catalyst composition comprising a first catalyst component, and, optionally, a second catalyst component, said first catalyst component being an amorphous cracking catalyst and/or large pore crystalline cracking catalyst, said second catalyst component being a shape selective medium pore crystalline silicate zeolite catalyst, to provide a gasiform material contributing hydrogen species and/or carbon-hydrogen fragments; and,(b) catalytically cracking a thermally treated heavy hydrocarbon feed in a higher region of the riser in the presence of said catalyst composition and gasiform material to provide gasoline boiling range material in increased yield and/or of higher quality.

Abstract: The invention describes a process for producing light products, such as engine and diesel fuels, and fuel oils for conventional use by thermal conversion of heavy metal- and sulfur-rich-crude oil residues. Thermal cracking of the residues is done by mild cracking in several stages, where the residue remaining after separation of the conversion products of the preceding stage is fed to the respective subsequent stage.

Abstract: A fluid catalytic cracking (FCC) process and apparatus which employs relatively more elutriatable catalyst particles comprising intermediate pore zeolite, particularly ZSM-5, and relatively less elutriatable catalyst particles comprising large pore zeolite, preferably zeolite Y. The process and apparatus employ a first stripping vessel which also separates a more elutriatable first portion of catalyst from a less elutriatable second portion of catalyst. The more elutriatable first portion passes to a second stripping vessel, and subsequently recycles to a fluid catalytic cracking reactor riser. The second portion of less elutriatable catalyst passes from the first stripping vessel to a fluid catalytic cracking regenerator vessel and, after being regenerated, recycles to the reactor riser. The more elutriatable first portion contains a higher ratio of intermediate pore catalyst particles to large pore catalyst particles than does the second portion.

Abstract: A process for producing improved yields of aromatics (benzene, toluene, xylene) by initially partially thermally cracking heavy hydrocarbon and thermally cracking ethane to high conversion and then completely cracking the partially cracked heavy hydrocarbon with the completely cracked ethane.

Abstract: There is provided a catalytic cracking operation featuring a single riser reaction zone having a lower and an upper section wherein a variety of hydrocarbon conversion reactions takes place, a stripping zone in which entrained hydrocarbon material is removed from catalyst and a regeneration zone in which spent cracking catalyst is regenerated, which comprises:(a) cracking a C.sub.

Abstract: A temperature control process is disclosed for a hydrocarbon conversion process wherein a feedstock is heated in a furnace and is partly converting in a first reactor, the effluent from the first reactor is cooled in a first heat exchanger and by adding a quench, then the cooled effluent is converted in a second reactor, and the effluent from the second reactor is cooled in a second heat exchanger. Part of the pre-furnace feedstock is used as coolant for the two heat exchangers, the amount of coolant being controlled by a first bypass valve for a line bypassing both heat exchangers and by a second bypass valve for a line bypassing only the second heat exchanger. The inlet temperature for the second reactor is controlled while maximizing the pre-furnace feedstock temperature by adjusting the valve for quench and the two bypass valves.