Abstract: This FCC process suspends a layer of catalyst in a riser proximate or above the riser outlets. The density at the riser outlets is higher than the flowing density in the riser. The suspended catalyst provides a disengagement zone that enhances the separation of catalyst from product vapors. The riser operates in a manner that prevents any discharge of catalyst from its end. The arrangement also provides a convenient method for vetoing stripping vapors into a closed reactor cyclone system.

Abstract: In this invention a cyclonic separation method and apparatus discharges particulate solids and gaseous fluids into a separation vessel from a discharge opening of a central conduit and withdraws separated gaseous fluids from the separation vessel that contacts the catalyst in the separation vessel with redistributed gases from outside the separation vessel. The invention increases the effective utilization of available stripping medium in an FCC process.

Abstract: In this invention a cyclonic separation method and apparatus discharges particulate solids and gaseous fluids into a separation vessel from a discharge opening of a central conduit and withdraws separated gaseous fluids from the separation vessel with a recovery conduit having an inlet located below the discharge opening. Recovery of separated gases using cyclonic separation is improved by the specific location of the recovery piping inlet which reduces the entrainment of fine particles with the gases.

Abstract: A side-by-side reactor vessel and stripping vessel arrangement uses a rejection vessel to collect the catalyst from the bottom of a reactor vessel and eliminate stagnant layers of catalyst within the reactor vessel while increasing the efficiency of a stripper vessel located to the side of the reactor. Catalyst containing entrained and sorbed hydrocarbons pass from the bottom of a reactor vessel into the small diameter rejection vessel that provides a hydrocarbon rejection zone and uses a fresh stripping medium to maintain a dense fluidized bed from which entrained hydrocarbons are quickly disengaged from the catalyst and travel upward into the reactor vessel. Partially stripped catalyst flows through a passageway that extends horizontally to a stripping vessel that contains a conventional stripping zone. In the stripping vessel, catalyst counter-currently contacts additional stripping medium which removes sorbed hydrocarbons from the catalyst surface.

Abstract: Disclosed is a fluid catalytic cracking process in which the catalytic cracking reaction takes place in a dilute phase, and the reaction product contains a reduced volume of off gas having a low concentration of SO.sub.x and NO.sub.x. The use of off gas, which is produced during a regeneration step, to strip entrained vapor from spent catalytic cracking catalyst acts to reduce SO.sub.x and NO.sub.x byproducts, and eliminates the need to separately recover and treat the off gas stream from the regenerator portion of the system. The entire process, including the reaction step, the stripping step and the regeneration step, can be performed in a single vessel, and the stripping and reaction steps take place entirely in the dilute phase.

Abstract: An FCC process and apparatus operates with closed reactor cyclones and a catalyst stripper using H2 or recycled stripper vapor for stripping gas. Preferably stripper vapor is removed, cooled and condensed, and some vapor recycled to the stripper. Isolation of the stripper from the cracked product vapors permits use of large amounts of stripping steam, or stripping gases such as hydrogen.

Abstract: A cyclone and process for fluidized catalytic cracking of heavy oils is disclosed. Gas and entrained solids are added tangentially around a vapor outlet tube in a cylindrical tube cyclone body. Solids and some gas is withdrawn via a plurality of openings radially and longitudinally distributed in the cylindrical sidewall of the cyclone body. Distributed withdrawal replaces or reduces conventional underflow of solids from an end of cyclone outlet and reduces solids reentrainment. 0-5 micron particle removal is enhanced by reducing eddy formation and particle bouncing near the cyclone sidewall. The device may be used as an FCC regenerator third stage separator.

Abstract: A side-by-side reactor vessel and stripping vessel arrangement uses a rejection vessel to collect the catalyst from the bottom of a reactor vessel and eliminate stagnant layers of catalyst within the reactor vessel while increasing the efficiency of a stripper vessel located to the side of the reactor. Catalyst containing entrained and sorbed hydrocarbons pass from the bottom of a reactor vessel into the small diameter rejection vessel that provides a hydrocarbon rejection zone and uses a fresh stripping medium to maintain a dense fluidized bed from which entrained hydrocarbons are quickly disengaged from the catalyst and travel upward into the reactor vessel. Partially stripped catalyst flows through a passageway that extends horizontally to a stripping vessel that contains a conventional stripping zone. In the stripping vessel, catalyst counter-currently contacts additional stripping medium which removes sorbed hydrocarbons from the catalyst surface.

Abstract: The method of controlling the flow of a fluidizable particulate solid, e.g., FCC catalyst, which comprises: (a) passing a fluidized stream of the particulate solid downwardly from a source of the particulate solid, e.g., an FCC regenerator, in a first conduit to a junction with a second conduit where the solid particulate is mixed with a stream of a fluid transport medium from a third conduit; (b) passing a stream of the resulting mixed solid particulate/transport medium upwardly in the second conduit at an angle less than 90.degree. from the first conduit for a distance at least as great as the diameter of the first conduit at the junction into a fourth conduit; (c) transporting the particulate solid/fluid transport medium stream in the fourth conduit to a desired location; and (d) controlling the mass flow of the particulate solid in the fourth conduit by setting the flow rate of the transport medium in the third conduit.

Abstract: An inertial/filtering separator in a single vessel and FCC process using same as a third stage separator are disclosed. Gas and fines are added tangentially to an annulus formed by a cylindrical insert in a vessel. Gas flows over the insert and down to filters in the vessel. Solids are withdrawn from the base of the annulus and periodically from the filter. Three types of solids collection--inertial, gravity settling and filtration--are practiced in a single vessel.

Abstract: An FCC process mixes spent and regenerated catalyst to obtain thermal equilibrium of a blended catalyst stream before contacting feed with the blended catalyst stream. The spent and regenerated catalyst from the reactor and regenerator catalyst may be mixed in a blending vessel located at the bottom of an FCC riser that can also serve as a hot catalyst stripper.

Abstract: An FCC reactor achieves greater utilization of the space within the reactor vessel by using a vented riser arrangement having an inlet opening at the bottom of a vented riser collector. The inlet opening at the bottom of the vented riser collector allows plug flow of the catalyst and hydrocarbon vapors through the upper and lower section of the reactor vessel without any substantial degradation and separation efficiency between the catalyst and the hydrocarbon vapors. This permits almost the entire tangent length of the reactor vessel to be used for the purpose of catalyst and hydrocarbon contact.

Abstract: A reactor for refining resid includes an elongated vertical vessel containing a bed of catalyst which is expanded or ebullated by a liquid/gas mixture. The mixture rises in an updraft through the bed and then is recirculated with an increased velocity by an ebullating pump. To reduce gas holdup of the ebullated bed and to promote a more uniform flow, the gas is entrapped by two cascaded stages of baffles which have an internal conical shape to guide, direct, and entrap the gas. One of these two stages has a shape which creates a countercurrent in the flowing liquid to deflect any catalyst particles which might otherwise be elutriated by the increased velocity.

Abstract: An FCC process uses a highly efficient separation device to remove product from the catalyst so that the reactor vessel receives a low volume of feed hydrocarbons and riser by-products. The separation device encloses an upwardly directed outlet end of a ballistic separation device in low volume disengaging vessel that collects disengaged catalyst from the riser in a dense bed. Immediate contact of the dense bed with a stripping fluid minimizes the amount of hydrocarbons that are carried out of the disengaging vessel into the open volume of the reactor vessel.

Abstract: An FCC process uses a highly efficient separation device to remove product from the catalyst so that the reactor vessel receives a low volume of feed hydrocarbons and riser by-products. The separation device encloses an upwardly directed outlet end of a ballistic separation device in low volume disengaging vessel that collects disengaged catalyst from the riser in a dense bed. Immediate contact of the dense bed with a stripping fluid minimizes the amount of hydrocarbons that are carried out of the disengaging vessel into the open volume of the reactor vessel.

Abstract: A method of fluid catalytic cracking of hydrocarbon feed which for rapid separation of the fluid catalytic cracking catalyst from the mixture of gases and products, utilizes a U-turn inertial separator directly coupled to cyclone separation.

Abstract: A process for fluidized catalytic cracking of heavy feed using a low H.sub.2 S content lift gas in the base of a riser reactor. The lift gas is a recycled, ethylene rich stream obtained by removing H.sub.2 S from a compressed vapor stream intermediate the FCC main column receiver and the gas plant associated with the FCC unit. The low H.sub.2 S lift gas does not increase SO.sub.x emissions from the regenerator as much as a recycled vapor from the FCC main column. As the lift gas is not purified in the gas plant it does not overload it.

Abstract: In a direct-coupled cyclone system, the riser cyclone is positioned external to a containment vessel. The riser cyclone separator discharges separated catalyst to a catalyst stripper internal to the containment vessel. Means is provided for withdrawing stripping gas from the catalyst stripper and passing it under pressure control to the riser cyclone separator. The riser cyclone separator is inherently pressure stable relative to the catalyst stripper. The invention is particularly useful for retrofitting a direct-coupled cyclone separator to a preexisting containment vessel with limited free volume.

Abstract: A riser cyclone separator is positioned external to a containment vessel. The riser cyclone separator discharges separated catalyst to a catalyst stripper and separated vapor to a plenum, both positioned internal to the containment vessel. Means is provided for withdrawing stripping gas from the catalyst stripper and passing it via the riser cyclone separator to the plenum. The riser cyclone separator is inherently pressure stable relative to the containment vessel. The invention is particularly useful for retrofitting a direct-connected riser cyclone separator to a preexisting containment vessel with space limitations.

Abstract: A process and apparatus for controlling the flow of FCC catalyst around a catalyst regenerator, using a non-mechanical valve, is disclosed. The preferred non-mechanical valve provides a de-aeration section, addition of fluidizing gas, a "U" trap seal, and venturi gas outlet on the top of the trap, for reliable flow control of non-uniform settling particles such as FCC catalyst. Control of the flow of a fluidizing gas to such a valve changes the flow properties of the FCC catalyst and permits flow control without resort to plug valves, or other internal mechanical valves, which are difficult to use in the harsh environment experienced within FCC regenerators.

Abstract: A "leaking" cyclone and process for fluidized catalytic cracking of heavy oils is disclosed. Gas and entrained solids are added tangentially to swirl around a vapor outlet tube in a cylindrical tube cyclone body. A concentrated stream of solids and some gas is withdrawn from the device through openings in the cylindrical sidewall remote from the inlet. Tangential withdrawal via an offset slit in the sidewall, or withdrawal through holes in the sidewall, replaces or reduces conventional underflow of solids from an end of the cyclone body. Fine (0-5 micron) particles removal is enhanced by withdrawing solids as soon as solids reach the cylindrical sidewall. The device may be used as a third stage separator on an FCC regenerator.

Abstract: An FCC process and apparatus is arranged to provide a low volume dilute disengagement zone in a reactor vessel. A vented riser that provides an open discharge of catalyst and gaseous products is directly discharged into a reactor vessel. The interior of the reactor vessel is arranged such that the outlet of the reactor riser is located close to and directed at the top of the reactor vessel. The reactor vessel operates with a dense bed of catalyst having an upper bed level that is only a short distance below the outlet of the reactor riser. The cyclone separators are located to the outside of the reactor riser and circulate catalyst directly back to the reactor riser or directly to an independent stripping vessel that returns the catalyst to the regenerator.

Abstract: An open-bottomed cyclone separator with gas inlet tube is disclosed which minimizes the entrainment of separated solids in a process gas entering the separator. In some embodiments, the gas inlet tube directs the process gas into a solids-depleted region within a cyclonic separation chamber. In other embodiments, a gas inlet tube directs the process gas into a stream of solids-depleted gas withdrawn from the chamber. Methods for practicing the invention are also disclosed.

Abstract: A fluidized solid process for upgrading or converting a hydrocarbon feedstock wherein carbonaceous deposits accumulate on a particulate fluidized solid and are burned in a regenerator to regenerate the solid, the regenerated solid and entrained combustion products are introduced into a vertical lift pipe, a fluid lift medium is introduced into the lift pipe and the regenerated solid is separated from the lift medium and combustion products to improve the quality of the regenerated solid contacted with the hydrocarbon feedstock.

Abstract: An FCC process uses a tube sheet arrangement and a multiplicity of centrifugal separation devices in an FCC reactor to reduce the volume of the reactor vessel thereby minimizing uncontrolled reaction of feed hydrocarbons and the production of riser by-products. The separation arrangement encloses an upwardly directed outlet end of a ballistic separation device in a low volume disengaging vessel that transfers dilute catalyst and product vapors to a tube sheet arrangement of swirl tubes that removes catalyst and directs it downwardly into a stripper arrangement.

Abstract: A fluidized catalyst contacting apparatus improves the recovery of entrained hydrocarbon gases by providing a de-gassing zone upstream of a conventional stripping zone. The de-gassing zone has a downwardly increasing catalyst density gradient that reduces the void volume of the fluidized catalyst thereby de-gassing hydrocarbon vapors from the catalyst prior to entering a stripping zone. The de-gassing zone is particularly useful in a vented riser arrangement for an FCC reactor where catalyst concentrates along the wall of the reactor vessle as it flows downwardly into the stripping zone. By providing a de-gassing zone to collect the downwardly descending catalyst and remove hydrocarbon vapors, efficiency of a sub-adjacent stripping zone is significantly improved.

Abstract: A method and apparatus for an FCC process uses means for dissipating turbulent flow at the outlet of a disengaging vessel to provide a quick separation of catalyst from product vapors and to prevent reentrainment of catalyst into the disengaging vessel. The process and apparatus use a riser for the conversion of an FCC feedstock and direct the effluent from the riser directly into a disengaging vessel to separate catalyst from the product vapors. Catalyst is directed downwardly out of the outlet of the disengaging vessel and through a series of dissipator plates that dissipate turbulent flow by eliminating the tangential velocity that would be other-wise introduced by the vortex and would lead to reentrainment of catalyst. A stripping vessel is located immediately below the disengaging vessel outlet to receive catalyst as it leaves the dissipator plates.

Abstract: A method and apparatus for an FCC process uses dissipator plates at the outlet of a disengaging vessel to provide a quick separation of catalyst from product vapors and to prevent reentrainment of catalyst into the disengaging vessel. The process and apparatus use a riser for the conversion of an FCC feedstock and direct the effluent from the riser directly into a disengaging vessel to separate catalyst from the product vapors. Catalyst is directed downwardly out of the outlet of the disengaging vessel and through a series of dissipator plates that eliminate the tangential velocity that would be otherwise introduced by the vortex and would lead to reentrainment of catalyst. A stripping vessel is located immediately below the disengaging vessel outlet to receive catalyst as it leaves the dissipator plates. The apparatus and process are specifically suited for operation without a reactor vessel for containment of the disengaging vessel and cyclones.

Abstract: An FCC reactor achieves greater utilization of the space within the reactor vessel by using a vented riser arrangement having an inlet opening at the bottom of a vented riser collector. The inlet opening at the bottom of the vented riser collector allows plug flow of the catalyst and hydrocarbon vapors through the upper and lower section of the reactor vessel without any substantial degradation and separation efficiency between the catalyst and the hydrocarbon vapors. This permits almost the entire tangent length of the reactor vessel to be used for the purpose of catalyst and hydrocarbon contact.

Abstract: A process for short contact time cracking of heavy feed. A falling, annular curtain of hot regenerated FCC catalyst, or hot inert solids, is formed over a cone shaped plug valve. Hydrocarbons pass from under the cone, or via a hollow stem, in radial in to out flow to contact the falling curtain of solids. After 0.01 to 1.0 seconds of contact time, solids and cracked vapor are separated, preferably in a bell separator beneath the reaction zone. Downflow of reactants into a contiguous upflowing stripper minimizes attrition.

Abstract: This FCC process suspends a catalyst and a riser proximate or above the riser cyclone inlets at a density that is higher than the flowing density in the riser. The suspended catalyst provides a disengagement zone that enhances the separation of catalyst from product vapors. The riser operates in a manner that prevents any discharge of catalyst from its end. The arrangement also provides a convenient method for venting stripping vapors into a closed reactor cyclone system.

Abstract: A fluidized catalytic cracking process operates with a turbulent or fast fluidized bed (FFB) spent catalyst stripper. Higher vapor velocities in the stripper improve stripping. Preferably spent catalyst is added to the stripper via cyclone diplegs. Preferably most of the spent catalyst is added into the bed near the top of the FFB stripper is removed via the top of the stripper, to a contiguous, annular bubbling dense bed stripper surrounding the FFB stripper. Some catalyst may be removed from the base of the FFB stripper.

Abstract: Open-ended cyclone separators are disclosed which employ catalyst separation tubes to prevent separated solids discharged through an open cyclone end from being entrained in a countercurrently moving flow of process gas entering the separator through the open end. In several preferred embodiments, generally conical tubes are axially located within the cyclone open bottom. Methods for practicing the invention also are disclosed.

Abstract: This invention provides a method of reducing the sulfur oxide emissions from the regenerator of an FCC process that cracks a sulfur containing feedstream. The sulfur oxide emissions are reduced by using an essentially sulfur free lift gas stream to shift the sulfur concentration equilibrium between the product stream from the reaction zone and the flue gas stream from the regeneration zone. Sulfur compounds present in the FCC feed leave the reaction zone as volatile sulfurous gases in the product vapor stream or as adsorbed sulfur compounds on the catalyst. Sulfurous gas in the product vapors is mainly H.sub.2 S. By lowering the concentration of H.sub.2 S that enters the riser with the lift gas the equilibrium reaction of sulfur with hydrogen in the riser is favorably shifted to increase the production of H.sub.2 S and decrease the lay down of sulfur compounds in the coke that forms on the catalyst.

Abstract: A generally closed vapor path catalytic cracking reactor system is disclosed which includes a vented post-cyclone inertial separator. The inertial separator includes first and second conduit-like members and a vent located at the downstream end of the upstream member. Spent catalyst can be disengaged from a spent catalyst and cracked vapor mixture through the vent while cracked hydrocarbon vapors flow into the second separator member. The separator vent provides a path for stripping gas to enter the generally closed vapor path under routine operating conditions and provides a flow path for damping pressure surges into a surrounding disengagement vessel under transient quality conditions.

Abstract: Methods and apparatus are disclosed for separating solids from a mixture of solids and gases. An in-line cyclone separator cyclonically swirls the mixture as it exits a conduit concentrically located within a radially symmetric separation chamber. In some embodiments, stripping gas apertures direct stripping gas into the chamber to help maintain the angular momentum of the solids cyclonically swirling within the chamber.

Abstract: The invention is a process and apparatus for rapidly and efficiently separating a fluidized catalytic cracking mixture into cracking catalysts and hydrocarbon vapor. The invention decreases the production of unwanted hydrocarbon byproducts by decreasing the contact time between the separated hydrocarbon vapor and the cracking catalyst.

Abstract: A downcomer for use in ebullating bed reactors that is perforated along its length within the reactor. These perforations are sized slightly smaller that the solid catalyst particles used in the reactor in order to screen out these solid particles and prevent their flow or movement into the downcomer from the reactor. As a result of the perforated downcomer, any liquid separated from the fluidized medium and collected in the downcomer will flow back through these perforations and into the reactor when the ebullating bed is operating at its normal level; however, when the ebullating bed is operating at an upset level condition, the liquid in this fluidized medium will flow in the opposite direction and will pass through these perforations into the downcomer in order to maintain a minimum flow to the ebullating pumps.

Abstract: A riser cyclone separator for rapidly separating catalyst from cracked hydrocarbon vapors in a fluid catalytic cracking process. The riser cyclone is provided with an annular port for drawing stripping gas into the riser cyclone to separate entrained catalyst and vent stripper gas from the regenerator vessel. The cyclone is inherently negative pressure to the reactor vessel.

Abstract: In a fluid catalytic cracking (FCC) process riser reactor effluent is rapidly separated into spent catalyst and hydrocarbon product. The separated hydrocarbon product is immediately quenched to an unreactive temperature in the absence of quenching spent catalyst. An increase in debutanized naphtha yield is achieved. By avoiding catalyst quenching, heat duty is saved in the catalyst regenerator.

Abstract: A process and apparatus for the regeneration of spent FCC catalyst in a single vessel are disclosed. In one embodiment, catalyst is at least partially regenerated in a primary stage comprising a fast or turbulent fluidized bed. The flue gas is discharged up, with some and preferably most of the catalyst discharged laterally, through windows, into a second fluidized bed, preferably disposed as an annulus about the first. In another embodiment a cyclone separator is closely coupled to, but spaced from, the primary regeneration stage, to rapidly separate catalyst from first stage flue gas, and minimize thermal stress.

Abstract: A process and apparatus for multi-stage fluidized bed regeneration of spent FCC catalyst in a single vessel. At least two isolated relatively dense phase fluidized beds are disposed beneath a common dilute phase region. Spent catalyst discharged into a primary regeneration stage is regenerated to produce flue gas and partially regenerated catalyst, which preferably overflows into the second stage. Flue gas and entrained catalyst from each fluidized bed are processed in two trains of separation means, preferably cyclones. The inlets of each train are disposed above the isolated fluidized beds, and are effectively separated although sharing an open dilute phase region.

Abstract: Accordingly, the present invention, in one embodiment, encompasses an apparatus for the fluidized catalytic cracking of a hydrocarbon feed comprising: a riser which is generally vertically positioned within a catalyst disengaging zone and which has a plurality of openings around the circumference of the riser at its discharge end. The openings in the riser have a vertical stub portion that extends tangentially outwardly from the riser and communicates with a first end of an upwardly sloping curvilinear tunnel that terminates at a second end. The second end of the tunnel opens into a tangential opening in the primary cyclone. The area of the opening of the first end of the tunnel is larger than the area of the opening of the second end of the tunnel.

Abstract: A process and apparatus for fluidized catalytic cracking of heavy oils is disclosed using a modified high efficiency catalyst regenerator. A fast fluidized bed coke combustor, which is essentially free of gas/catalyst separation means, partially regenerates catalyst and discharges a steam laden flue gas and catalyst into a dilute phase transport riser. Closed cyclones separate catalyst from steam laden flue gas exiting the transport riser outlet. This flue gas is isolated from a second fluidized bed of catalyst maintained in a vessel containing the transport riser and closed cyclones. Coke combustion in the drier region of the second fluidized bed is possible. Catalyst deactivates less in the second fluidized bed because it is drier.

Abstract: A catalytic cracking process is provided for cost effectively separating and stripping hydrocarbon from catalyst while limiting the occurrence of undesired catalytic overcracking and thermal cracking reactions. The process includes the steps of contacting feed with catalyst, grossly separating the larger coked catalyst particles from the hydrocarbon, disengaging the smaller coked catalyst fines from the hydrocarbon, removing volatile hydrocarbon from the grossly separated and disengaged catalyst, and recycling the volatile hydrocarbon back to the gross separating step. The disengager step includes the steps of dampening the flow of grossly separated hydrocarbon and internally cyclone separating the smaller catalyst fines from the hydrocarbon product.

Abstract: A method and apparatus for an FCC process uses dissipator plates at the outlet of a disengaging vessel to provide a quick separation of catalyst from produce vapors and to prevent reentrainment of catalyst into the disengaging vessel. The process and apparatus use a riser for the conversion of an FCC feedstock and direct the effluent from the riser directly into a disengaging vessel to separate catalyst from the product vapors. Catalyst is directed downwardly out of the outlet of the disengaging vessel and through a series of dissipator plates that eliminate the tangential velocity that would be otherwise introduced by the vortex and would lead to reentrainment of catalyst. A stripping vessel is located immediately below the disengaging vessel outlet to receive catalyst as it leaves the dissipator plates.

Abstract: The use of lift gas for FCC risers is improved by the direct use of stripping vapors from a second stage of catalyst stripping as a lift gas. Reactor vapors recovered primarily from the stripping section of an FCC reactor/regenerator section provide an excellent source for lift gas material. These reactor vapors contain high concentrations of light paraffinic materials often with an equal weight percent amount of steam. The recovery of the stripping vapors independent from the product stream allows such gaseous mixtures to be readily used as lift gas. The lift gas material is obtained from a stripping section located subadjacent to a regenerator section so that it will have adequate pressure for use as a lift gas stream. The relatively high pressure of the lift gas stream eliminates processing requirements that would otherwise be necessary for the removal of particulate material and the compression of the gas to the pressure conditions at the bottom of the riser.

Abstract: A process and apparatus for regeneration of coked catalyst used in the fluidized cracking of heavy oils is disclosed. A high efficiency catalyst regenerator, with a fast fluidized bed coke combustor, dilute phase transport riser, and second fluidized bed is used but modified so that at least some coked catalyst is added directly to the second fluidized bed. The coked catalyst can be heated by direct contact heat exchange in the second fluidized bed and then charged to the coke combustor, or the coked catalyst can be regenerated in the second fluidized bed, or some combination of both. Adding catalyst to the second fluidized bed increases the coke burning capacity of these regenerators, and/or permits a drier regeneration.

Abstract: Disclosed is a method of and apparatus for reducing the level of extremely small catalyst particles ("fines") in an FCC system by temporarily retaining particles separated from the secondary cyclone separator in either a reactor vessel or catalyst regenerator. These particles can be withdrawn from the temporary retaining area, which takes them out of the active catalyst inventory within the reactor/regenerator system. The withdrawing of catalyst "fines" reduces the particulate contamination both in flue gas exhausted to the atmosphere from the catalyst regenerator and in the main column bottom (MCB) products from the fractionation stage. Preferred embodiments includes withdrawal of "fines" from either the regenerator or the reactor vessels and the secondary cyclones contained in each of these vessels.

Abstract: This invention relates to a process for the separation of fine catalyst particles from a hydrocarbon feedstock coming from a catalytic cracking unit by filtration through mineral barriers and a filtration loop.The process consists of filtering the feedstock through mineral barriers that are resistant to heat and have a porosity adapted to the minimum diameter of the particles to be retained. The porosity is generally between 0.1 and 100 microns.