Process for the fluidized-bed catalytic cracking of a weakly coking feedstock having a Conradson carbon residue equal to or less than 0.1% by weight and a hydrogen content equal to or greater than 12.7% by weight, comprising at least a step of cracking the feedstock, a step of separating/stripping the effluents from the coked catalyst particles and a step of regenerating said particles, the process being characterized in that at least one coking, carbonaceous and/or hydrocarbonaceous effluent having a content of aromatic compounds of greater than 50% by weight, comprising more than 20% by weight of polyaromatic compounds, is recycled to homogeneously distributed and weakly coked catalyst, before regeneration, in order to adjust the delta coke of the process.

In various aspects, systems and methods are provided for operating an oxygen-fired catalyst regenerator with flue gas recycle and CO.sub.2 capture. An oxygen-fired catalyst regenerator contrasts with an air-fired regenerator. The oxygen-fired catalyst regenerator substantially reduces nitrogen within the system, which facilitates CO.sub.2 capture by reducing the energy required to capture CO.sub.2. In various aspects, a first portion of the regenerator flue gas is passed to a CO.sub.2 capture system and a second portion is recycled to the regenerator. Before the flue gas is recycled or diverted to the CO.sub.2 capture, it is passed to various processes that remove and/or reduce SO.sub.x, NO.sub.x, particulate, and water content. In various aspects, a portion of the treated flue gas may be combined with substantially pure O.sub.2 and recycled to the regenerator.

A fluid coking unit for converting a heavy oil feed to lower boiling products by thermal has a centrally-apertured annular baffle at the top of the stripping zone below the coking zone to inhibit recirculation of solid particles from the stripping zone to the coking zone. By inhibiting recirculation of the particles from the stripping zone to the coking zone, the temperatures of the two zones are effectively decoupled, enabling the coking zone to be run at a lower temperature than the stripping zone to increase the yield of liquid products.

A system and a method for catalytically cracking hydrocarbons. The system includes a fluidized bed riser reactor, and a separation zone configured to separate the effluent from the riser reactor to produce a product stream and a spent catalyst. A stripping zone is fluidly coupled to the outlet of the separation zone such that the spent catalyst is stripped to remove the hydrocarbons adsorbed thereon. The stripping zone encompasses at least a portion of the riser reactor such that stripping internals in the stripping zone are used to provide reaction heat to the riser reactor.

Process for the fluidized-bed catalytic cracking of a weakly coking feedstock having a Conradson carbon residue equal to or less than 0.1% by weight and a hydrogen content equal to or greater than 12.7% by weight, comprising at least a step of cracking the feedstock, a step of separating/stripping the effluents from the coked catalyst particles and a step of regenerating said particles, the process being characterized in that at least one coking, carbonaceous and/or hydrocarbonaceous effluent having a content of aromatic compounds of greater than 50% by weight, comprising more than 20% by weight of polyaromatic compounds, is recycled to homogeneously distributed and weakly coked catalyst, before regeneration, in order to adjust the delta coke of the process.

An apparatus for separating solid particles from a stream of a mixture of gaseous fluids and solid particles has a separation vessel. A mixture conduit extends vertically into a central section of the separation vessel and defines a discharge opening located within the vessel and tangentially oriented for discharging the stream into an open interior of the vessel and imparting a tangential velocity to the stream. A gas recovery conduit within the separation vessel has an inlet for withdrawing gaseous fluids from within the open interior of the separation vessel at a location below the discharge opening and radially offset from the mixture conduit. An intermediate portion of the gas recovery conduit is located above the inlet within the separation vessel and has a diameter greater than a diameter of the inlet.

A method includes introducing one or more waste plastic feedstocks in neat form to a fluid catalyst cracking unit, and processing the one or more waste plastic feedstocks in neat form in the presence of a catalyst under fluidized catalytic cracking conditions.

A process for increasing the yield of C.sub.3 olefin in fluidized bed catalytic cracking of hydrocarbon feedstocks is disclosed. C.sub.4 fraction produced from the cracking of hydrocarbon feedstock in the primary reaction zone (riser), optionally with external source of C.sub.4 stream is fed into the stripper which acts as a secondary reaction zone at an elevated temperature and at an optimum WHSV. The elevated temperature is achieved by injecting a part of the regenerated catalyst from regenerator, which is at a higher temperature, directly into the stripper through a dedicated additional lift line. This raises the activity of catalyst inside the stripper. The direct injection of regenerated catalyst into the stripper, besides producing higher yields of propylene, improves the stripping efficiency leading to enhanced recovery of strippable hydrocarbons.

A fluidized bed reactor, a device, and a method for producing low-carbon olefins from oxygen-containing compound are provided. The fluidized bed reactor includes a reactor shell, a reaction zone, a coke control zone and a delivery pipe, where there are n baffles arranged in the coke control zone, and the n baffles divide the coke control zone into n sub-coke control zones which include a first sub-coke control zone, a second sub-coke control zone, and an nth sub-coke control zone; at least one catalyst circulation hole is provided on each of the n-1 baffles, so that the catalyst flows in an annular shape in the coke control zone, where n is an integer. The device and method can be adapted to a new generation of DMTO catalyst, and the unit consumption of production ranges from 2.50 to 2.58 tons of methanol/ton of low-carbon olefins.

A method for forming light olefins may include reacting a feed stream in the presence of a catalyst in a reactor to form a product stream, separating at least a portion of the product stream from the catalyst, and passing the catalyst to a catalyst processing portion of the reactor system and processing the catalyst to produce a processed catalyst and a flue gas. The catalyst may be heated, coke may be removed from the catalyst, or both, in a combustor in the catalyst processing portion. The method may further comprise separating the catalyst from the flue gas, and passing the flue gas though a heat exchanger system to cool the flue gas. Heat may be exchanged from the flue gas to an oxygen-containing gas in an inlet stream. The oxygen-containing gas may exit the heat exchanger system in a first stream and a second stream. The oxygen-containing gas in the first stream may have a temperature greater than that of the oxygen-containing gas in the second stream. The method may further comprise passing the oxygen-containing gas in the first stream directly to the combustor, and passing the oxygen-containing gas in the second stream to one or more of a catalyst transport pipe as a solid transport fluid, or an oxygen treatment zone.