Fluid catalytic cracking process and apparatus for maximizing light olefin yield

Abstract

The apparatus and method of the present disclosure provide for the conversion of a hydrocarbon feed into light olefins and other hydrocarbons. In some embodiments, the method and apparatus include feeding a hydrocarbon, a first catalyst, and a second catalyst into a reactor, wherein the first catalyst has a smaller average particle size and is less dense than the second catalyst. A first portion of the second catalyst can be recovered as a bottoms product from the reactor, and a cracked hydrocarbon effluent, a second portion of the second catalyst, and the first catalyst can be recovered as a tops product from the reactor. The second portion of the second catalyst can be separated from the tops product, providing a first stream comprising the first catalyst and the hydrocarbon effluent and a second stream comprising the separated second catalyst, allowing the separated second catalyst in the second stream to be returned to the reactor.

Description

Technical Field

[0001] Embodiments disclosed herein generally relate to systems and methods for improving the productivity and / or flexibility of a hybrid catalyst system. Some embodiments disclosed herein relate to apparatuses and methods for maximizing the conversion of heavy hydrocarbon feeds such as vacuum gas oil and / or heavy oil residue into light olefins with extremely high yields such as propylene, ethylene, aromatics, and gasoline with high octane numbers. Background Art

[0002] Recently, the production of light olefins by the fluid catalytic cracking (FCC) process has been considered one of the most attractive proposals. In addition, the demand for petrochemical base materials such as propylene, ethylene, and aromatics (benzene, toluene, xylene, etc.) has been increasing continuously. Moreover, due to both economic and environmental reasons, the integration of refineries and petrochemical complexes has become the first choice.

[0003] Global trends also show that the demand for middle distillates (diesel) has increased more than the demand for gasoline products. To maximize the middle distillates from the FCC process, it is necessary to operate the FCC at a lower reactor temperature and also use different catalyst formulations. The disadvantage of this change is that the production of light olefins is reduced and the feedstock for the alkylation unit is decreased because the FCC unit is operated at a lower temperature.

[0004] In the past two decades, several fluidized bed catalytic processes have been developed to meet the changing market demands. For example, US7479218 discloses a fluid catalytic reactor system in which the riser reactor is divided into two parts with different radii to improve the selectivity for light olefin production. The first part of the riser reactor with a smaller radius is used to crack heavy feed molecules into the naphtha range. The enlarged radius part, i.e., the second part of the riser reactor, is used to further crack the naphtha range products into light olefins such as propylene and ethylene. Although the reactor system concept is quite simple, the degree of selectivity for light olefins is limited for the following reasons: (1) the naphtha range feed stream partially contacts coked or deactivated catalyst; (2) due to the endothermic nature of the reactions in both parts, the temperature in the second part of the reaction section is much lower than that in the first zone; and (3) the high activation energy required for light feed cracking is lacking compared to heavy hydrocarbons.

[0005] US6106697, US7128827, and US7323099 use a two-stage fluid catalytic cracking (FCC) unit to achieve a high degree of control over the selective cracking of heavy hydrocarbon and naphtha-range feed streams. In the first-stage FCC unit, which includes a riser reactor, a stripping column, and a regenerator, gas oil / heavy hydrocarbon feed is converted to naphtha-boiling-range products in the presence of a Y-type large-pore zeolite catalyst. A second-stage FCC unit with a set of similar vessels / configurations is used to catalytically crack the naphtha stream recovered from the first stage. Of course, the second-stage FCC unit employs a ZSM-5 type (small-pore zeolite) catalyst to improve the selectivity to light olefins. Although, in general, this scheme provides a high degree of control over feed, catalyst, and operating window selection and optimization, the second-stage treatment of the naphtha feed produces very little coke, insufficient to maintain the heat balance. This requires external heat to achieve a high enough temperature in the regenerator for good combustion and to provide heat for feed vaporization and endothermic reactions. Typically, torch oil is burned in the second-stage FCC regenerator, which results in higher catalyst particle temperatures and hot spots, and thus excessive catalyst deactivation.

[0006] US7658837 discloses a method and apparatus for optimizing the production of FCC products by using a portion of a conventional stripping column bed as a reactive stripper. This reactive stripping concept for the second reactor somewhat compromises the stripping efficiency and can thus lead to an increased coke load in the regenerator. Product yield and selectivity may also be affected due to the contact of the feed with coked or deactivated catalyst. In addition, since the riser top temperature is directly controlled to maintain a series of required conditions in the riser, the reactive stripper temperature cannot be changed independently.

[0007] US2007 / 0205139 discloses a method for maximizing gasoline production by injecting hydrocarbon feed through a first distributor located in the bottom section of the riser. When the aim is to maximize light olefins, the feed is injected through a similar feed distribution system in the upper section of the riser, aiming to reduce the residence time of hydrocarbon vapors in the riser.

[0008] The aim of WO2010 / 067379 is to increase the production of propylene and ethylene by injecting C4 and olefinic naphtha streams in the riser section of the riser below the heavy hydrocarbon feed injection zone. These streams not only increase the light olefin production but also replace steam as the medium for catalyst transport. This concept helps to reduce the degree of catalyst thermal deactivation. However, it does not allow for flexible variation of operating conditions such as temperature and WHSV in the riser section, which are crucial for cracking such light feed streams. This may result in poor selectivity to the desired light olefins.

[0009] US6869521 discloses contacting a feed derived from FCC products, particularly naphtha, with a catalyst in a second reactor operating in a fast fluidization regime, which is beneficial for promoting hydrogen transfer reactions and for controlling catalytic cracking reactions.

[0010] US7611622 discloses an FCC process that uses dual risers to convert a C3 / C4-containing feedstock into aromatics. A first and a second hydrocarbon feed are supplied to respective first and second risers in the presence of a gallium-rich catalyst, and the second riser is operated at a higher reaction temperature than the first riser.

[0011] US5944982 discloses a catalytic process for producing low-sulfur and high-octane gasoline using dual risers. A second riser is used to process the recovered heavy naphtha and light cycle oil after hydrotreating to maximize petroleum production and octane number.

[0012] US20060231461 discloses a method for maximizing the production of light cycle oil (LCO) or middle distillate products and light olefins. The method uses a dual reactor system where a first reactor (riser) is used to primarily crack a gas oil feed into LCO, and a second co-current dense bed reactor is used to crack the naphtha recovered from the first reactor. Since the first reactor operates at a significantly lower reaction temperature, the method is limited by catalyst selectivity and lacks the desired olefin level in the naphtha.

[0013] US6149875 relates to using an adsorbent to remove feed contaminants such as Conradson carbon residue and metals. The difference in the transport / terminal velocity between the FCC catalyst and the adsorbent is used to separate the FCC catalyst from the adsorbent.

[0014] US7381322 discloses an apparatus and method for separating a catalyst from a metal adsorbent in a stripping column cum separator prior to a regeneration step for eliminating the adverse effects of contaminant metals deposited on the adsorbent. The patent uses the difference in the minimum / bubbling velocity and is mainly applied to separating the FCC catalyst from the adsorbent. SUMMARY OF THE INVENTION

[0015] It has been found that hydrocarbon cracking can be carried out using a dual reactor scheme, including cracking C4, lighter C5 fractions, naphtha fractions, methanol, etc., for the production of light olefins, where the dual reactor scheme has no restrictions on selectivity and operability, meets the heat balance requirements, and also maintains a low piece count. The selected embodiments disclosed herein use a conventional riser reactor in combination with a mixed flow (e.g., catalyst flow including both countercurrent and cocurrent flows) fluidized bed reactor designed to maximize light olefin production. The effluents from the riser reactor and the mixed flow reactor are processed in a common catalyst disengaging vessel, and the catalysts used in the riser reactor and the mixed flow reactor can be regenerated in a common catalyst regeneration vessel. As will be described in more detail below, this flow scheme effectively maintains high cracking activity, overcomes the heat balance problem, and also increases the light olefin yield and selectivity from various hydrocarbon streams, and simplifies product quenching and plant hardware.

[0016] In one aspect, embodiments disclosed herein relate to a method for the conversion or catalytic cracking of hydrocarbons. The method may include feeding a hydrocarbon, a first particle, and a second particle to a reactor, where the first particle has a smaller average particle size and / or density than the second particle, and the first and second particles may be catalytic or non-catalytic. A first portion of the second particle may be recovered as a bottoms product from the reactor; and, a cracked hydrocarbon effluent, a second portion of the second particle, and the first particle may be recovered as an overhead product from the reactor. The second portion of the second particle may be separated from the overhead product to provide a first stream including the first particle and the hydrocarbon effluent and a second stream including the separated second particle, such that the separated second particle in the second stream can be returned to the reactor.

[0017] In another aspect, embodiments disclosed herein relate to a system for the catalytic cracking of hydrocarbons. The system may include a first reactor for contacting a first and a second cracking catalyst with a hydrocarbon feedstock to convert at least a portion of the hydrocarbon feedstock to lighter hydrocarbons. An overhead product line is provided for recovering from the first reactor a first stream including the first cracking catalyst, a first portion of the second cracking catalyst, and the hydrocarbon. A bottoms product line is provided for recovering from the first reactor a second stream including a second portion of the second cracking catalyst. The second cracking catalyst may be separated from the first stream using a separator, producing a hydrocarbon effluent including the hydrocarbon and the first cracking catalyst. A feed line is provided for returning the separated second cracking catalyst from the separator to the first reactor.

[0018] The system for catalytic cracking of hydrocarbons may further include a riser reactor for contacting a mixture of a first cracking catalyst and a second cracking catalyst with a second hydrocarbon feedstock to convert at least a portion of the second hydrocarbon feedstock into lighter hydrocarbons and recover a riser reactor effluent comprising the lighter hydrocarbons and the mixture of the first cracking catalyst and the second cracking catalyst. A second separator may be provided for separating the second cracking catalyst from the hydrocarbon effluent and separating the first and second cracking catalysts from the riser reactor effluent. A catalyst regenerator may also be used for regenerating the first and second cracking catalysts recovered from the second separator and a second portion of the second cracking catalyst recovered from the bottoms product line.

[0019] In another aspect, embodiments disclosed herein relate to a method for converting hydrocarbons. The method may include: feeding a first catalyst to a reactor; feeding a second catalyst to the reactor, wherein the first catalyst has a smaller average particle size and / or density than the second catalyst; and feeding a hydrocarbon feedstock to the reactor. A top effluent may be recovered from the reactor, the top effluent comprising cracked hydrocarbons, the first catalyst, and the second catalyst. The second catalyst may be separated from the top product to provide a first stream comprising the first catalyst and the hydrocarbon effluent and a second stream comprising the separated second catalyst, such that the separated second catalyst in the second stream may be returned to the reactor.

[0020] In another aspect, embodiments disclosed herein relate to a separator that separates catalysts or other particles based on size and / or density differences. The separator may have at least one inlet and may also have at least two outlets for separating the particles from the carrier gas. The carrier gas carries the particles into the separator, and inertial, centrifugal, and / or gravitational forces may be applied to the particles such that a portion of the particles and the carrier gas are collected at a first outlet and a portion of the particles along with the carrier gas are collected at a second outlet. The combination of forces in the separator may have the effect of making the outlet streams more concentrated in particle size and / or density relative to the inlet concentration. The separator may have additional carrier gas distribution or fluidization in a vessel / chamber to apply additional forces to the particles, which may facilitate enhanced classification.

[0021] In another aspect, embodiments disclosed herein relate to an inertial separator that separates catalysts or other particles based on size and / or density. The inertial separator can include an inlet for receiving a mixture including a carrier gas, a first particle type, and a second particle type. Each particle type can have an average particle size and a particle size distribution (which can be different or overlapping) as well as an average density. The second particle type can have a larger average particle size and / or average density than the first particle type. The inertial separator can include a U-shaped tube that includes a first vertical leg, a U-shaped bottom, and a second vertical leg. The U-shaped tube can fluidly connect the inlet to a first outlet and a second outlet via the first vertical leg, the first outlet being connected near the bottom of the U-shaped tube, and the second outlet being connected to the second vertical leg. The U-shaped inertial separator can be configured to separate at least a portion of the second particle type from the carrier gas and the first particle type, recover the second particle via the first outlet, and recover the carrier gas and the first particle type via the second outlet. The separator can further include a distributor disposed within or near the second outlet for introducing a fluidizing gas to facilitate additional separation of the first particle type and the second particle type. In some embodiments, the separator can be configured such that the cross-sectional area of the U-shaped tube or a portion thereof is adjustable. For example, in some embodiments, the separator can include movable baffles disposed within one or more sections of the U-shaped tube.

[0022] In another aspect, embodiments disclosed herein relate to an inertial separator that separates catalysts or other particles based on size and / or density as above. The inertial separator can include an inlet horizontal tube that passes through a chamber before being deflected by a baffle. The chamber is connected to a first vertical outlet and a first horizontal outlet. The baffle can be located in the middle, can be near the inlet or near the outlet of the chamber. The baffle can be at an angle or movable such that it deflects more or fewer catalyst particles. The baffle chamber separator can be configured to separate at least a portion of the second particle type from the carrier gas and the first particle type, recover the second particle type via the first vertical outlet, and recover the carrier gas and the first particle type via the first horizontal outlet. The separator can further include a distributor disposed within or near the first vertical outlet for introducing a fluidizing gas to facilitate additional separation of the first particle type and the second particle type.

[0023] In another aspect, embodiments disclosed herein relate to an inertial separator that separates catalysts or other particles based on size and / or density as described above. The inertial separator can include a vertical inlet connected to a chamber, where one or more vertical sides of the chamber are equipped with slit outlets that can be described as movable louvers. The number of movable louvers can vary according to the application, and the angle of the movable louvers can be adjustable to control the amount of vapor exiting the louver outlets. The chamber is also connected to a first vertical outlet at the bottom of the chamber. The louver separator can be configured to separate at least a portion of a second particle type from the carrier gas and a first particle type, recover the second particle type via the first vertical outlet, and recover the carrier gas and the first particle type via the louver outlets. The separator can also include a distributor disposed within or near the first vertical outlet for introducing a fluidizing gas to facilitate additional separation of the first particle type from the second particle type.

[0024] The above separator can also be used in combination with a reactor, a regenerator, and a catalyst feed system to enhance system performance and flexibility.

[0025] In one aspect, embodiments disclosed herein relate to a method for hydrocarbon conversion. The method can include regenerating a catalyst mixture comprising a first catalyst and a second particle in a regenerator, where the first catalyst has a smaller average particle size and / or density than the second particle, and where the second particle can be catalytic or non-catalytic. The catalyst mixture and hydrocarbon can be fed to a riser reactor to convert at least a portion of the hydrocarbon, and a first effluent comprising the catalyst mixture and the converted hydrocarbon can be recovered. The catalyst mixture can also be fed to a second reactor. Feeding the hydrocarbon feedstock to the second reactor and fluidizing the catalyst mixture can cause the hydrocarbon feedstock to contact the catalyst mixture to convert the hydrocarbon and provide a recovery of an overhead product from the second reactor comprising the second particle, the first catalyst, and the reacted hydrocarbon product. The second particle can then be separated from the overhead product to provide a first stream comprising the first catalyst and the reacted hydrocarbon product and a second stream comprising the separated second particle, and the separated second particle in the second stream can be returned to the reactor.

[0026] In another aspect, embodiments disclosed herein relate to a method for the conversion of hydrocarbons. The method can include withdrawing a mixture comprising a first catalyst and a second catalyst from a catalyst regenerator and feeding the mixture and hydrocarbons to a riser reactor to convert at least a portion of the hydrocarbons and recover a first effluent comprising the catalyst mixture and the converted hydrocarbons, wherein the first catalyst has a smaller average particle size and / or density than the second catalyst. The method can further include withdrawing a mixture comprising the first catalyst and the second catalyst from the catalyst regenerator and feeding the mixture to a catalyst separation system, fluidizing the mixture comprising the first catalyst and the second catalyst with a fluidizing medium, and separating the first catalyst from the second catalyst in the catalyst separation system to recover a first stream comprising the first catalyst and the fluidizing medium and a second stream comprising the second catalyst. Then, the hydrocarbon feedstock and the first stream or the second stream can be fed to a reactor to react at least a portion of the hydrocarbons to produce converted hydrocarbons.

[0027] In another aspect, embodiments disclosed herein relate to a method for the conversion of hydrocarbons. The method can include feeding a hydrocarbon feedstock and a catalyst mixture comprising a first catalyst and a second catalyst to a riser reactor, wherein the first catalyst has a smaller average particle size and / or density than the second catalyst. Then, the effluent from the riser reactor can be separated to recover a first stream comprising the first catalyst and the converted hydrocarbon feedstock and a second stream comprising the second catalyst, and the second stream can be fed to the riser reactor.

[0028] In another aspect, embodiments disclosed herein relate to a method for the conversion of hydrocarbons. The method can include withdrawing a mixture comprising a first catalyst and a second catalyst from a catalyst regenerator and feeding the mixture to a catalyst feed / separation system, wherein the first catalyst has a smaller average particle size and / or density than the second catalyst. The first catalyst can be separated from the second catalyst in the catalyst feed / separation system to produce a first stream comprising the first catalyst and a second stream comprising the second catalyst. Then, the hydrocarbon feedstock and the first stream or the second stream can be fed to a riser reactor to react at least a portion of the hydrocarbons to produce converted hydrocarbons.

[0029] In another aspect, embodiments disclosed herein relate to a system for converting hydrocarbons. The system may include a catalyst regenerator, and a first catalyst feed line for withdrawing a mixture comprising a first catalyst and a second catalyst from the catalyst regenerator and feeding the mixture to a riser reactor, wherein the first catalyst has a smaller average particle size and / or density than the second catalyst. The system may further include a second catalyst feed line for removing a mixture comprising the first catalyst and the second catalyst from the catalyst regenerator and feeding the mixture to a catalyst separation system; and a fluidizing medium feed line for fluidizing the mixture withdrawn via the second catalyst feed line using a fluidizing medium and separating the first catalyst from the second catalyst in the catalyst separation system to recover a first stream comprising the first catalyst and the fluidizing medium and a second stream comprising the second catalyst. A reactor may be provided for contacting a hydrocarbon feedstock with the first stream or the second stream to cause at least a portion of the hydrocarbons to react to produce converted hydrocarbons.

[0030] In another aspect, embodiments disclosed herein relate to a system for converting hydrocarbons. The system may include a riser reactor for contacting a hydrocarbon feedstock with a catalyst mixture comprising a first catalyst and a second catalyst, wherein the first catalyst has a smaller average particle size and / or density than the second catalyst. A catalyst separation system is provided for separating the riser reactor effluent to recover a first stream comprising the first catalyst and the converted hydrocarbon feedstock and a second stream comprising the second catalyst. A flow line feeds the second stream to the riser reactor.

[0031] In another aspect, embodiments disclosed herein relate to a system for converting hydrocarbons. The system may include a catalyst withdrawal line for withdrawing a mixture comprising a first catalyst and a second catalyst from the catalyst regenerator and feeding the mixture to a catalyst feed / separation system, wherein the first catalyst has a smaller average particle size and / or density than the second catalyst. The catalyst feed / separation system separates the first catalyst from the second catalyst in the catalyst feed / separation system to produce a first stream comprising the first catalyst and a second stream comprising the second catalyst. A riser reactor contacts a hydrocarbon feedstock with the first stream or the second stream to cause at least a portion of the hydrocarbons to react to produce converted hydrocarbons.

[0032] The apparatuses and methods disclosed herein use techniques that are significantly different from those disclosed in the above-mentioned patents (such as US6149875 and US7381322) to separate particulate mixtures. The objectives of the present disclosure are also different; the prior art disclosures focus on removing contaminants from catalysts by introducing adsorbents. However, the present invention aims to improve conversion, selectivity, and thermal balance by concentrating selected catalysts in a reactor, for example, concentrating ZSM-5 / 11 in a second reactor.

[0033] A method for hydrocarbon conversion. The method may include feeding a mixture of first particles and second particles from a regenerator to a transport vessel or a riser reactor. The first particles may have a smaller average particle size and / or density than the second particles, and the first particles and the second particles may independently be catalytic or non-catalytic particles. The method may further include feeding a reactive and / or non-reactive carrier fluid to the transport vessel or the riser reactor, and recovering an overhead product comprising the carrier fluid and / or the reaction product of the carrier fluid, the second particles, and the first particles from the transport vessel / riser reactor.

[0034] The overhead product may be fed to an integrated separation vessel. The integrated separation vessel may include an outer shell. A solid separation device may be provided within the outer shell for separating the second particles from the overhead product to provide a first stream comprising the first particles and the carrier fluid and / or the reaction product of the carrier fluid, and a second stream comprising the separated second particles. One or more cyclone separators may also be provided within the outer shell, and the cyclone separators are used for separating the first stream to recover a solid fraction comprising the first particles and a vapor fraction comprising the carrier fluid and / or the reaction product of the carrier fluid. In addition, an inner container may be provided within the outer shell for receiving the second stream comprising the separated second particles. An annular region may be formed between the outer shell and the inner container for receiving the solid fraction comprising the first particles. The separation vessel may further include a vapor outlet for recovering the vapor fraction, a first solid outlet for recovering the solid fraction from the annular region, and a second solid outlet for recovering the separated second particles from the inner container.

[0035] The method may further include recovering the solid fraction from the annular region through the first solid outlet. In addition, the separated second particles may be recovered through the second solid outlet.

[0036] In some embodiments, the solid fraction comprising the separated first particles may be fed from the annular region to the regenerator. The separated second particles from the inner container may be fed to the transport vessel or the riser reactor, where the separated second particles are mixed with the mixture of the first particles and the second particles from the regenerator.

[0037] In some embodiments, the separated second particles may be fed from the inner container to the regenerator. The solid fraction comprising the separated first particles may be fed from the annular region to the transport vessel or the riser reactor, where the separated second particles are mixed with the mixture of the first particles and the second particles from the regenerator.

[0038] In other embodiments, the separated second particles may be fed from the inner container to an additional reactor. The separated second particles may contact a hydrocarbon feedstock in the additional reactor to crack the hydrocarbon feedstock.

[0039] In another aspect, embodiments disclosed herein relate to a method for hydrocarbon conversion. The method can include feeding a mixture of first particles and second particles from a regenerator to a riser reactor, where the first particles have a smaller average particle size and / or density than the second particles, and where the first particles and the second particles can independently be catalytic or non-catalytic particles. A hydrocarbon fraction can be fed to the riser reactor, and the method includes contacting the hydrocarbon fraction with the mixture of first particles and second particles to convert at least a portion of the hydrocarbon fraction. An overhead product comprising the converted hydrocarbon fraction, the second particles, and the first particles can be recovered from the riser reactor. The overhead product can then be fed to an integrated disengaging vessel that includes: an outer shell; a solid separation device disposed within the outer shell for separating the second particles from the overhead product to provide a first stream comprising the first particles and a carrier fluid and / or reaction products of the carrier fluid, and a second stream comprising the separated second particles; one or more cyclone separators disposed within the outer shell for separating the first stream to recover a solid fraction comprising the first particles and a vapor fraction comprising the carrier fluid and / or reaction products of the carrier fluid; an inner vessel disposed within the outer shell for receiving the second stream comprising the separated second particles; an annular region between the outer shell and the inner vessel for receiving the solid fraction comprising the first particles; and a vapor outlet for recovering the vapor fraction. The solid fraction can be fed from the annular region to the regenerator. Additionally, the method can include increasing the concentration of the second particles within the riser reactor by feeding the separated second particles from the inner vessel to the riser reactor, where the separated second particles are mixed with the mixture of first particles and second particles from the regenerator.

[0040] The method can further include feeding a second hydrocarbon feedstock as well as the mixture of first particles and second particles to a second reactor. In the second reactor, the mixture of first particles and second particles can contact the second hydrocarbon feedstock to crack the second hydrocarbon feedstock and form a second reactor effluent comprising lighter hydrocarbons as well as the mixture of first particles and second particles. The second reactor effluent can be fed to a separator to separate the first particles and second particles from the lighter hydrocarbons and the converted hydrocarbon effluent, and the hydrocarbon product can be recovered from the separator.

[0041] In other embodiments, the method can further include feeding the vapor fraction recovered through the vapor outlet as well as the hydrocarbon product recovered from the separator to a fractionation system that is configured to separate the hydrocarbon product therein into two or more hydrocarbon fractions, including a naphtha fraction. The naphtha fraction can be fed as a hydrocarbon feedstock to the riser reactor.

[0042] In other embodiments, the method can include adjusting a vapor split ratio in the solid separation device to carry a portion of the second catalyst in the first stream.

[0043] In another aspect, embodiments of the present disclosure relate to a system for cracking hydrocarbons. The system may include a regenerator, a riser reactor, and an integrated disengaging vessel. The riser reactor may be configured to receive a mixture of a first particle and a second particle from the regenerator, wherein the first particle has a smaller average particle size and / or density than the second particle, and wherein the first particle and the second particle may independently be catalytic or non-catalytic particles. The riser reactor may also be configured to contact a hydrocarbon fraction with the mixture of the first particle and the second particle to convert at least a portion of the hydrocarbon fraction and produce an overhead product from the riser reactor that includes the converted hydrocarbon fraction, the second particle, and the first particle.

[0044] The integrated disengaging vessel is configured to receive the overhead product. The integrated disengaging vessel may include a housing. A solid separation device may be disposed within the housing, and the solid separation device may be configured to separate the second particle from the overhead product to provide a first stream that includes the first particle and a carrier fluid and / or a reaction product of the carrier fluid, and to provide a second stream that includes the separated second particle. One or more cyclone separators may also be disposed within the housing, and the cyclone separators are configured to separate the first stream to provide a solid fraction that includes the first particle and a vapor fraction that includes the carrier fluid and / or the reaction product of the carrier fluid. An internal container may also be disposed within the housing, and the internal container is configured to receive the second stream that includes the separated second particle. An annular region may be formed between the housing and the internal container, and the annular region is configured to receive the solid fraction that includes the first particle. The integrated disengaging vessel may further include: a vapor outlet for recovering the vapor fraction; a flow line for feeding the solid fraction from the annular region to the regenerator; and a flow line for increasing the concentration of the second particle within the riser reactor by feeding the separated second particle from the internal container to the riser reactor, wherein the separated second particle is mixed with the mixture of the first particle and the second particle from the regenerator. In some embodiments, the system may further include a controller configured to adjust a vapor split ratio in the solid separation device to carry a portion of the second catalyst in the first stream.

[0045] In summary, most of the current technologies include dual riser / reactor configurations or two-stage fluid catalytic cracking process schemes / units. The second / parallel reactor for processing light feeds (naphtha or / and C4 streams) is either a co-current pneumatic flow riser reactor or a dense bed reactor. In the art, it is well known that ZSM-5 is a preferred catalyst / additive for converting naphtha / C4 streams into propylene and ethylene. However, in the method using two reactors, the second reactor also receives a Y-zeolite catalyst with a small amount of ZSM-5 additive. In other process schemes, the FCC-type reactor-regenerator concept is used to maximize light olefins from naphtha / C4 streams. This scheme causes heat balance problems due to insufficient coke production. The methods and systems disclosed herein contemplate separating the catalysts in the mixture (e.g., separating ZSM-5 or ZSM-11 additives from Y-zeolite & ZSM-5 / ZSM-11) to optimize the concentration of ZSM-5 or ZSM-11 in the second reactor for processing light feeds. Additionally, the integration of the additional / second reactor with a conventional FCC unit substantially helps to overcome these drawbacks of the prior art (especially product selectivity and heat balance), and substantially increases the total conversion and light olefin yield, and increases the ability to process heavier feeds.

[0046] Other aspects and advantages will be apparent from the following detailed description and the appended claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Figure 1 is a simplified process flow diagram of a system for cracking hydrocarbons and producing light olefins according to one or more embodiments disclosed herein.

[0048] Figures 2 to 5 is a simplified process flow diagram of a separator in a system according to one or more embodiments disclosed herein.

[0049] Figure 6 is a simplified process flow diagram of a system for cracking hydrocarbons and producing light olefins according to one or more embodiments disclosed herein.

[0050] Figure 7 is a simplified process flow diagram of a system for cracking hydrocarbons and producing light olefins according to one or more embodiments disclosed herein.

[0051] Figure 8A is a simplified process flow diagram of a system for cracking hydrocarbons and producing light olefins according to one or more embodiments disclosed herein.

[0052] Figure 8B is a simplified process flow diagram of a system for cracking hydrocarbons and producing light olefins according to one or more embodiments disclosed herein.

[0053] Figure 8C is a simplified process flow diagram of a system for cracking hydrocarbons and producing light olefins according to one or more embodiments disclosed herein.

[0054] Figure 9A is a simplified process flow diagram of a system for cracking hydrocarbons and producing light olefins according to one or more embodiments disclosed herein.

[0055] Figure 9B is a simplified process flow diagram of a system for cracking hydrocarbons and producing light olefins according to one or more embodiments disclosed herein.

[0056] Figure 10 is a simplified process flow diagram of a system for cracking hydrocarbons and producing light olefins according to one or more embodiments disclosed herein.

[0057] Figure 11 is a simplified process flow diagram of a system for cracking hydrocarbons and producing light olefins according to one or more embodiments disclosed herein.

[0058] Figure 12 is a simplified process flow diagram of a system for cracking hydrocarbons and producing light olefins according to one or more embodiments disclosed herein. Detailed Description

[0059] As used herein, the terms "catalyst" and "particle" and similar terms may be used interchangeably. As described above and further described below, the embodiments herein separate mixed particulate materials based on size and / or density to achieve advantageous effects in a reactor system. Particles or particulate materials for promoting catalytic or thermal reactions can include, for example, catalysts, absorbents, and / or heat transfer materials that are not catalytically active.

[0060] In one aspect, embodiments herein relate to fluid catalytic cracking units and methods for converting heavy hydrocarbon feeds such as vacuum gas oil and / or heavy oil residues into very high yields of light olefins (e.g., propylene, ethylene, aromatics, and gasoline or middle distillates with high octane numbers), while minimizing the yield of heavier bottoms products. To achieve this, a secondary reactor, which can be a mixed flow reactor (including both co-current and counter-current flow of particles relative to vapor flow) or a catalyst concentration reactor, can be integrated with a conventional fluid catalytic cracking reactor such as a riser reactor. In the riser reactor, the heavy hydrocarbon feed is catalytically cracked into naphtha, middle distillates, and light olefins, and the riser reactor is a gas flow co-current type reactor. To increase the yield and selectivity of light olefins (ethylene and propylene), cracked hydrocarbon products from the riser reactor such as C4 and naphtha-range hydrocarbons (olefins and paraffins) can be recycled and processed in the secondary reactor (mixed flow reactor or catalyst concentration reactor). Alternatively, or additionally, an external feed stream (e.g., C4, naphtha, or other hydrocarbon fractions from other processes such as steam crackers, metathesis reactors, or delayed coking units, and naphtha-range streams such as straight-run naphtha or from delayed coking, visbreaking, or natural gas condensates, as well as other hydrocarbon feeds) can be processed in the secondary reactor to produce light olefins such as ethylene and propylene. Integrating the secondary reactor with a conventional FCC riser reactor according to the embodiments disclosed herein can overcome the disadvantages of existing processes, can significantly increase the overall conversion and light olefin yield, and / or can increase the ability to process heavier feeds.

[0061] The integration of the secondary reactor with the conventional FCC riser reactor according to the embodiments disclosed herein can be facilitated by: (a) using a common catalyst regeneration vessel; (b) using two types of catalysts, one for selectively cracking heavier hydrocarbons and the other for selectively cracking C4 and naphtha-range hydrocarbons to produce light olefins; and (c) using a mixed flow reactor or a catalyst concentration reactor, the flow pattern of which partially separates the two types of catalysts, facilitating the contact of C4 or naphtha feeds with the corresponding selective catalyst to crack and produce light olefins.

[0062] To enhance the operating window of the secondary reactor and to provide greater process flexibility, the secondary reactor can be operated in a flow pattern that entrains a catalyst for selective cracking of heavier hydrocarbons and entrains at least a portion of a catalyst for selective cracking of C4 and naphtha-range hydrocarbons. The cracked hydrocarbon product and the entrained catalyst are then fed to a separator to separate the catalyst for selective cracking of C4 and naphtha-range hydrocarbons from the cracked hydrocarbon product and the catalyst for selective cracking of heavier hydrocarbons. The solid separation vessel is an external vessel of the reactor and is operated with such hydrodynamics as to enhance their separation based on the physical properties (e.g., particle size and / or density) of the two catalysts. The separated catalyst for selective cracking of C4 and naphtha-range hydrocarbons can then be returned to the reactor for continuous reaction, enhancing the concentration of the catalyst for selective cracking of C4 and naphtha-range hydrocarbons within the reactor, improving the selectivity of the overall process, and also improving the flexibility of the overall process due to the enhanced operating window.

[0063] As described above, the cracking system can utilize two types of catalysts, each catalyst being favorable for a different type of hydrocarbon feed. The first cracking catalyst can be a Y-zeolite catalyst, an FCC catalyst, or other similar catalyst for cracking heavier hydrocarbon feeds. The second cracking catalyst can be a ZSM-5 or ZSM-11 type catalyst or other similar catalyst for cracking C4 or naphtha-range hydrocarbons and selectively producing light olefins. To facilitate the dual reactor scheme disclosed herein, the first cracking catalyst can have a first average particle size and density and can be smaller than the average particle size and density of the second cracking catalyst such that the catalysts can be separated based on density and / or size (e.g., based on terminal velocity or other characteristics of the catalyst particles).

[0064] In the catalyst regeneration vessel, the spent catalysts recovered from the riser reactor and the secondary reactor are regenerated. After regeneration, a first portion of the mixed catalyst can be fed from the regeneration vessel to the riser reactor (co-current flow reactor). A second portion of the mixed catalyst can be fed from the regeneration vessel to the secondary reactor.

[0065] In the co-current flow reactor, a first hydrocarbon feed contacts the first portion of the regenerated catalyst to crack at least a portion of the hydrocarbons to form lighter hydrocarbons. The effluent can then be recovered from the co-current flow reactor, the effluent comprising a first cracked hydrocarbon product and a spent mixed catalyst fraction.

[0066] In some embodiments, the secondary reactor is operated in a fluidized state sufficient to entrain the first cracking catalyst and the second cracking catalyst in the hydrocarbon product recovered as the effluent from the top outlet of the secondary reactor. The effluent is then fed to a separator to separate the cracked hydrocarbon product and the first cracking catalyst from the second cracking catalyst.

[0067] The vapor / first cracking catalyst stream recovered from the separator can then be sent out for separation. As described above, the second cracking catalyst recovered from the separator can be recycled back to the secondary reactor for continued reaction.

[0068] Both the first effluent (cracked hydrocarbons and spent mixed catalyst from the riser reactor) and the second effluent (cracked hydrocarbons and separated first cracking catalyst from the secondary reactor) can be fed to a disengaging vessel to separate the spent mixed catalyst fraction and the separated first cracking catalyst from the first and second cracked hydrocarbon products. The cracked hydrocarbon products (including light olefins, C4 hydrocarbons, naphtha-range hydrocarbons, and heavier hydrocarbons) can then be separated to recover the desired product or product fraction.

[0069] Accordingly, the method disclosed herein combines a secondary mixed-flow or catalyst-concentrating reactor, an external solid separator, and a riser reactor with conventional product separation and catalyst regeneration, wherein the catalyst for the secondary reactor highly selectively cracks C4 and naphtha-range hydrocarbons to produce light olefins. Conventional catalyst regeneration provides heat balance, and conventional product separation (such as a disengaging vessel and / or a product fractionation system, etc.) provides operational simplicity, reduced number of parts, and other advantages.

[0070] Now referring to Figure 1 , a simplified process flow diagram of a system for cracking hydrocarbons and producing light olefins according to an embodiment disclosed herein is shown. The system includes a dual-reactor configuration for maximizing the yields of propylene and ethylene produced from a petroleum resid feedstock or other hydrocarbon stream. For example, the first reactor 3 can be a riser reactor for cracking heavier hydrocarbon feeds. The second reactor 32 is a fluidized bed reactor, which can be equipped with baffles or internals. C4 olefins and / or light naphtha products from the first reactor 3 or similar feed streams from an external source can be processed in the second reactor 32 to increase the yields of light olefins including propylene and ethylene as well as aromatics / high-octane gasoline.

[0071] The heavy petroleum resid feed is injected through one or more feed injectors 2 located near the bottom of the first reactor 3. The heavy petroleum feed contacts the hot regenerated catalyst introduced through the J - bend 1. The catalyst fed to the first reactor 3 is a catalyst mixture, including a first catalyst (e.g., Y - zeolite - based catalyst) for the selective cracking of heavier hydrocarbons, and a second catalyst (e.g., ZSM - 5 or ZSM - 11) for the selective cracking of C4 and naphtha - range hydrocarbons to produce light olefins. This catalyst mixture can also be used in combination with other catalysts. The first and second catalysts can differ in one or both of particle size and density. The first catalyst (e.g., Y - type zeolite - based) can have a particle size in the range of 20 - 200 microns and an apparent bulk density in the range of 0.60 - 1.0 g / ml. The second catalyst (e.g., ZSM - 5 or ZSM - 11) can have a particle size in the range of 20 - 350 microns and an apparent bulk density in the range of 0.7 - 1.2 g / ml.

[0072] The heat required for feed evaporation and / or raising the temperature of the feed to the desired reactor temperature (e.g., in the range of 500 °C to about 700 °C) and the endothermic (heat of reaction) can be provided by the hot regenerated catalyst from the regenerator 17. The pressure in the first reactor 3 is typically in the range of about 1 barg to about 5 barg.

[0073] After most of the cracking reactions are completed, the mixture of products, un - converted feed vapors, and spent catalyst flows into a two - stage cyclone separator system housed in the cyclone collection vessel 8. The two - stage cyclone separator system includes a main cyclone separator 4 for separating the spent catalyst from the vapors. The spent catalyst is discharged through the main cyclone dipleg 5 into the stripping column 9. The fine catalyst particles entrained in the separated vapors from the main cyclone separator 4 and the product vapors from the second reactor 32 introduced through the flow line 36a and the single - stage cyclone separator 36c are separated in the second - stage cyclone separator 6. The collected catalyst mixture is discharged via the dipleg 7 into the stripping column 9. The vapors from the second - stage cyclone separator 6 are discharged through the secondary cyclone outlet 12b (which can be connected to the plenum chamber 11) and then sent to the main fractionator / gas fractionator unit (not shown) for product recovery (including the desired olefins). If needed, light cycle oil (LCO) or steam is introduced via the distributor line 12a as a quench medium to further cool the product vapors.

[0074] The spent catalyst recovered via the diplegs 5, 7 is stripped in the stripper 9 to remove the interstitial vapor (hydrocarbon vapor trapped between the catalyst particles) by countercurrent contact with steam, which is introduced into the bottom of the stripper 9 through the steam distributor 10. Then, the spent catalyst is transferred to the regenerator 17 via the spent catalyst standpipe 13a and the lift line 15. The spent catalyst slide valve 13b located on the spent catalyst standpipe 13a is used to control the catalyst flow from the stripper 9 to the regenerator 17. A small portion of combustion air or nitrogen can be introduced through the distributor 14 to assist in the smooth transfer of the spent catalyst.

[0075] The coked or spent catalyst is discharged through the spent catalyst distributor 16 at the center of the dense phase regenerator bed 24. Combustion air is introduced by the air distributor 18 located at the bottom of the regenerator bed 24. Then, the coke deposited on the catalyst is burned off in the regenerator 17 by reaction with the combustion air. For example, the regenerator 17 can be operated at a temperature in the range of about 640 °C to about 750 °C and a pressure in the range of about 1 barg to about 5 barg. The catalyst fines entrained in the exhaust gas are collected in the first stage cyclone separator 19 and the second stage cyclone separator 21 and discharged into the regenerator catalyst bed through the respective diplegs 20, 22. The exhaust gas recovered from the outlet of the second stage cyclone separator 21 is directed via the regenerator plenum 23 to the exhaust gas line 50 for downstream waste heat recovery and / or power recovery.

[0076] The first portion of the regenerated catalyst mixture is discharged through the regenerated catalyst standpipe 27 in fluid communication with the J-bend 1. The catalyst flow from the regenerator 17 to the reactor 3 can be regulated by the slide valve 28 located on the regenerated catalyst standpipe 27. The opening of the slide valve 28 is adjusted to control the catalyst flow to maintain the desired top temperature in the reactor 3.

[0077] In addition to the lift steam, a feed stream of external flows such as C4 olefins and naphtha or the like is provided as a lift medium and injected into the J-bend 1 through the gas distributor 1a located in the Y-section to enable the smooth transfer of the regenerated catalyst from the J-bend 1 to the reactor 3. The J-bend 1 can also be used as a dense phase bed reactor for cracking the C4 olefin and naphtha streams into light olefins under conditions favorable for such reactions (e.g., a WHSV of 0.5 to 50 h -1 -1, a temperature of 640 °C to 750 °C, and a residence time of 3 to 10 seconds).

[0078] A second portion of the regenerated catalyst mixture is discharged into the second reactor 32 via the riser 30. The slide valve 31 can be used to control the catalyst flow from the regenerator 17 to the second reactor 32 based on the vapor outlet temperature set point. The C4 olefin and naphtha streams are injected into the bottom of the catalyst bed in liquid or vapor phase through one or more feed distributors 34 (34a, 34b). The second reactor 32 operates in a mixed flow mode, where a portion of the regenerated catalyst flows downward (from the top to the bottom of the reactor bed), and a portion of the regenerated catalyst mixture and the feed hydrocarbon stream flow upward (from the bottom to the top of the reactor bed).

[0079] The second reactor 32 can be equipped with baffles or structured internals (not shown) that assist in the intimate contact and mixing of the catalyst and feed molecules. These internals can also help to minimize channeling, bubble growth, and / or coalescence. The second reactor 32 can also be expanded along different portions of its length to maintain a constant or desired superficial gas velocity within these portions.

[0080] After the reaction is complete, the catalyst is stripped at the bottommost portion of the second reactor 32 using steam introduced through the distributor 35 as a stripping medium to separate the entrained hydrocarbon feed / product. Then, the spent catalyst recovered at the bottom of the reactor 32 is transferred to the regenerator 17 via the riser 37 and the lift line 40 through the spent catalyst distributor 41. Combustion air or nitrogen can be introduced through the distributor 39 to enable the smooth transfer of the catalyst to the regenerator 17. The slide valve 38 can be used to control the catalyst flow from the second reactor 32 to the regenerator 17. The spent catalyst from both reactors 3, 32 is then regenerated in the common regenerator 17 operating in the full combustion mode.

[0081] As described above, the second reactor 32 uses two different catalysts, which can differ in one or both of particle size and density, such as a lighter and smaller Y-zeolite or FCC catalyst and a larger and / or denser ZSM-5 / ZSM-11 shape-selective pentasil-type small pore zeolite. The superficial gas velocity in the second reactor 32 is maintained such that substantially all or most of the lighter, smaller catalyst (e.g., Y-zeolite / FCC catalyst) and a portion of the heavier, larger catalyst (e.g., ZSM-5 / ZSM-11) are carried out of the reactor together with the cracked hydrocarbons and steam recovered through the flow line 45. As described above, a portion of the larger and / or denser catalyst can be retained within the reactor 32, forming a dense phase bed towards the lower portion of the reactor.

[0082] Accordingly, the effluent from the reactor 32 recovered via the flow line 45 can include cracked hydrocarbon products, unreacted hydrocarbon feedstock, steam (stripping medium), and a catalyst mixture that includes substantially all of the lighter and / or smaller catalysts introduced into the reactor and a portion of the larger and / or denser catalysts. The effluent can then be conveyed via the flow line 45 to the solid separator 47. The separator 47 can be a separator configured to separate the two types of catalysts based on their physical properties (i.e., particle size and / or density). For example, the separator 47 can use differences in inertial forces or centrifugal forces to separate the FCC catalyst from the ZSM-5. The solid separation vessel 47 is an external vessel of the second reactor 32 and operates with hydrodynamic characteristics that enhance its separation based on the physical properties of the two types of catalysts.

[0083] After separation in the separator 47, the smaller and / or lighter catalysts (Y-type zeolite / FCC catalyst) are then conveyed from the separator 47 via the outlet line 36a to a common disengager or holding vessel 8 that houses the riser reactor cyclone and / or the reaction termination system. The larger and / or denser catalysts (ZSM-5 / ZSM-11) can be returned via the flow line 49 to the hybrid flow reactor 32 to continue reacting with the hydrocarbon feed introduced via the distributor 34.

[0084] Substantially all of the lighter / smaller catalysts and a portion of the larger and / or denser catalysts are entrained, and the subsequent separation and recycle of the larger and / or denser catalysts to the reactor 32 can cause significant accumulation of the larger and / or denser catalysts in the reactor 32. Since this catalyst is more selective for cracking C4 and naphtha-range hydrocarbons, the accumulation of the larger and / or denser catalysts can provide selectivity and yield advantages. Additionally, as described above, operating the reactor in a fluidized flow manner to entrain both types of catalysts can provide enhanced reactor operability or flexibility in operation.

[0085] Hydrocarbon feeds such as heavy vacuum gas oil or heavy residue feed, light cycle oil (LCO), or steam as a quench medium can be injected into the outlet line 36a via the distributor 36b. The flow rate of this quench medium can be controlled by setting the temperature of the flow entering the holding vessel 8. All of the vapors from the second reactor 32, including the vapors fed via the distributor 36b, are discharged into the dilute phase of the holding vessel 8 via the single-stage cyclone separator 36c. Using a hydrocarbon feed as the quench medium is preferred because it serves the dual purpose of cooling the product from the second reactor 32 and enhancing the production of middle distillates.

[0086] The first-stage reactor 3 (e.g., a riser reactor) can be operated in a fast fluidization mode (e.g., with a gas superficial velocity in the range of about 3 to about 10 m / s at the bottom section) and a pneumatic conveying mode (e.g., with a gas superficial velocity in the range of about 10 to about 20 m / s at the top section).

[0087] The WHSV in the second reactor 32 is typically in the range of about 0.5 h -1 to about 50 h -1 ; the vapor and catalyst residence times can vary between about 2 and about 20 seconds. When introducing different feeds, the C4 feed is preferably injected at a height lower than the injection of the naphtha feed. However, an exchange of the feed injection positions is possible.

[0088] If necessary, make-up catalyst can be introduced via one or more flow lines 42, 43. For example, fresh or make-up FCC or Y zeolite catalyst or a mixture of both can be introduced into the regenerator 17 through the flow line 42, and fresh or make-up ZSM-5 / ZSM-11 catalyst can be introduced into the second reactor 32 via the flow line 43. For example, the overall system catalyst inventory can be maintained by withdrawing the mixed catalyst from the regenerator 24. As will be described below, the catalyst inventory and the accumulation of the preferred catalyst in the reactor 32 can be controlled by controlling the operation of the reactor and the separator 47.

[0089] In some embodiments, a first portion of the regenerated catalyst is discharged from the regenerator 17 into the regenerated catalyst (RCSP) hopper 26 through a draw line 25 that is in fluid communication with the regenerator 17 and the regenerated catalyst riser 27. The catalyst bed in the RCSP hopper 26 floats at the same level as the bed in the regenerator 17. The regenerated catalyst is then transferred from the RCSP hopper 26 to the reactor 3 through the regenerated catalyst riser 27 that is in fluid communication with the J-bend 1. The catalyst flow from the regenerator 17 to the reactor 3 can be regulated by an RCSP slide valve 28 located on the regenerated catalyst riser 27. A pressure balance line 29 can also be provided.

[0090] The separator bypass line 60 can also be used to facilitate the transfer of particles from the top of the reactor 32 to the vessel 8, as Figure 1 shown. As referred to above with reference to Figure 1As described above, the second reactor 32 utilizes two different catalysts that may differ in one or both of particle size and density, such as lighter and / or smaller Y-zeolite or FCC catalysts and larger and / or denser ZSM-5 / ZSM-11 shape-selective pentasil-type small-pore zeolites. The superficial gas velocity in the second reactor 32 can be maintained such that substantially all of the lighter, smaller catalysts (e.g., Y-zeolite / FCC catalysts) and a portion of the larger and / or denser catalysts (e.g., ZSM-5 / ZSM-11) are carried out of the reactor together with the cracked hydrocarbons and steam recovered via the flow line 45.

[0091] Accordingly, the effluent from the reactor 32 recovered via the flow line 45 can include cracked hydrocarbon products, unreacted hydrocarbon feedstock, steam (stripping medium), and a catalyst mixture that includes substantially all of the lighter, smaller catalysts introduced into the reactor and a portion of the larger and / or denser catalysts. The effluent can then be conveyed via the flow line 45 to a solid separator 47. The separator 47 can be a separator configured to separate the two types of catalysts based on their physical properties (i.e., particle size and / or density). The separator 47 operates under hydrodynamic conditions that enhance its separation based on the physical properties of the two catalysts.

[0092] After separation in the separator 47, the smaller / lighter catalysts (Y-zeolite / FCC catalysts) are then conveyed from the separator 47 via an outlet line 36a to a common disengager or holding vessel 8, which houses the riser reactor cyclone and / or reaction termination system. The larger and / or denser catalysts (ZSM-5 / ZSM-11) can be returned to the mixed-flow reactor 32 to continue reacting with the hydrocarbon feed introduced through the distributor 34.

[0093] Continuously or intermittently, a portion of the effluent containing the two types of catalysts conveyed via the flow line 45 can be diverted to bypass the separator 47. The diverted portion of the effluent can flow through the separator 47 via a flow line 60, which can include a diverter or flow control valve 62. The effluent can then continue back to the disengager 8 via a flow line 64 to separate the hydrocarbon products from the catalyst. The flow line 64 can be combined with the effluent and smaller catalysts recovered from the separator 47 via the flow line 36a and can be introduced either upstream or downstream of the quench 36b. Alternatively, the diverted effluent in the line 60 can be fed directly to the disengager / holding vessel 8.

[0094] Although in Figure 1The diverter valve 62 is shown, but embodiments herein contemplate using a Y-shaped flow conduit or similar device to continuously send a portion of the effluent containing catalyst particle types to the stripper 8 while continuously sending a portion of the effluent to the separator 47, thereby allowing for the desired accumulation of larger and / or denser catalyst particles within the reactor 32. As Figure 1 shown, the catalyst from the second reactor can also be transferred to the regenerator 17 via line 37, slide valve 38, and transfer line 40. Blower air serves as the carrier gas 39 to transfer the catalyst to the regenerator 17. This catalyst transfer equipment not only helps control the catalyst bed level in the reactor 32 but also facilitates more frequent catalyst regeneration.

[0095] As described above, the use of an increased carrier fluid flow rate and / or the use of a flow distributor can advantageously provide for the accumulation of catalyst for the selective cracking of naphtha-range hydrocarbons in the second reactor 32. In some embodiments, it has been found that the reactor 32 can be operated in a manner that provides regenerated catalyst and maintains sufficient activity within the catalyst bed of the reactor 32 such that the catalyst transfer lines (flow lines 37, 40) and associated equipment can be omitted from the flow scheme (as Figure 6 shown) without compromising the selectivity and throughput of the reactor and with the added benefits of reduced mechanical complexity and lower capital and operating costs.

[0096] Now referring to Figure 6 , a simplified process flow diagram of a system for cracking hydrocarbons and producing light olefins according to embodiments disclosed herein is shown, where like reference numerals represent like parts. Similar to the process scheme Figure 1 shown above, the system Figure 6 shown will have a dual reactor scheme and introduce two types of particles (e.g., lighter and / or smaller Y-type or FCC catalyst and larger and / or denser ZSM-5 or ZSM-11 catalyst) into the secondary reactor 32. The larger and / or denser catalyst additive (e.g., ZSM-5 or ZSM-11) can be added directly to the secondary reactor vessel 32 via flow line 32. The regenerated catalyst mixture is transferred from the regenerator 17 to the reactor vessel 32 via line 30.

[0097] ​It is expected that the catalyst bed in the secondary reactor vessel 32 operates in a turbulent bed, bubbling bed, or fast fluidization regime. As shown, a light naphtha feed 34a (e.g., the light naphtha product from the primary reactor or riser reactor 3) can be fed into the secondary reactor 32 and converted to light olefins in the presence of the mixed catalyst. The lift gas together with the product gas in the vessel 32 lifts the solids (including the two catalysts) through the conduit 45 to the solid separation vessel 47 and then returns to the regenerator 17. Due to the difference in size and / or density of the two catalyst particles, most of the ZSM-5 or ZSM-11 catalyst particles will be separated from the Y-type or FCC catalyst in the solid separation vessel 47 and returned to the reactor 32 through the return line 49. Most of the Y-type or FCC catalyst particles will be transferred back to the stripping column 8 for gas-solid separation.

[0098] Compared with the other embodiments discussed above, the main difference is that there is no catalyst return line and associated control valves and equipment returning from the bottom of the secondary reactor vessel 32 to the regenerator vessel 17. As briefly discussed above, this process configuration can still provide effective catalyst regeneration, as well as the accumulation and concentration of the larger and / or denser ZSM-5 or ZSM-11 catalyst required within the reactor 32. It is expected that even when the return line 37 is removed, a higher concentration of the larger and / or denser catalyst can result in better performance in the secondary reactor vessel 32. This design with the removal of the return line 37 also reduces mechanical complexity and lowers capital and operating costs.

[0099] The embodiment without the return line 37 ( Figure 6 ) also includes steam as the lift gas. Since there is no catalyst outlet at the bottom of the reactor 32, the catalyst will fill the reactor 32, and in some embodiments, no catalyst bed layer is observed. The lift gas together with the product gas in the vessel 32 lifts the solids (including the two catalysts) through the conduit 45 to the solid separation vessel 47. Due to the difference in size and / or density of the two catalyst particles, the ZSM-5 or ZSM-11 catalyst particles will be separated from the Y-type or FCC catalyst in the solid separation vessel 47 and transferred back to the reactor 32 through the return line 49. Most of the Y-type or FCC catalyst particles will be transferred back to the stripping column 8 for gas-solid separation. Compared with Figure 1 , this design without the return line 37 may result in a much higher concentration of the larger and / or denser catalyst, which will lead to better reaction performance in the reactor 32. Although not shown, the vessel 32 may include a bottom flange or outlet to allow the vessel to be purged of catalyst. If needed, such an outlet can also be used to periodically remove the larger and / or heavier catalyst particles that may accumulate within the vessel 32.

[0100] As described above, the system according to embodiments herein may include a separator 47 configured to separate two types of catalysts based on their physical properties such as particle size and / or density. The separator 47 may be a cyclone separator, a screen separator, a mechanical sieve, a gravity chamber, a centrifugal separator, a baffle chamber, a louver separator, an in-line or pneumatic classifier, or other types of separators effective for separating particles based on size and / or hydrodynamic characteristics.

[0101] Examples of separators or classifiers useful in embodiments herein are shown in Figures 2 - 5 In some embodiments, as Figure 2 shown, the separator 47 may be a U-shaped inertial separator to separate two solid particles or catalysts having different particle sizes and / or particle densities. The separator may be constructed in the form of a U with an inlet 70 at the top, a gas outlet 84 at the other end of the U, and a main solid outlet 80 at the bottom of the U-shaped separator.

[0102] A mixture 72 of solid particles or catalysts of different sizes is introduced through the inlet 70 with a carrier gas stream, and an inertial separation force is applied to the solid particles by no more than one turn to separate the solid particles of different sizes. Larger and / or denser solid particles 78 preferentially move downward in sections 74 / 76 into a riser or downcomer 80 connected to the bottom of the U, while lighter or smaller solid particles are preferentially carried with the gas stream to the outlet 82 where a mixture 84 of small particles and gas can be recovered. The solid outlet 80 at the bottom of the U-separator (for returning the larger and / or denser catalyst particle stream to the inlet of the riser or downcomer of the second reactor 32) should be large enough to accommodate the normal solid / catalyst flow.

[0103] By controlling the gas flow rate entering the downcomer and leaving the main gas outlet, the overall separation efficiency of the U-shaped inertial separator and the selectivity of separating smaller and / or less dense particles from larger and / or denser particles can be manipulated. This extends to a fully sealed downcomer where the only gas flow leaving the downcomer is that entrained by the exiting solid / catalyst stream. When the U-shaped inertial separator provides the ability to manipulate the separation efficiency, medium-sized particles that may accumulate in the system as described above can be periodically or continuously entrained by the hydrocarbon product recovered from the separator 47 for separation in the vessel 8 and regeneration in the regenerator 24.

[0104] In some embodiments, a gas distributor 75 or additional steam / inert gas can be provided near the top of the outlet section 80 (e.g., near the top of the riser inlet). The additional lift gas provided within the separator can further facilitate the separation of larger and / or denser solid particles from less dense and / or smaller solid particles, as the additional gas can preferentially lift the lighter solid particles to the gas outlet 84, resulting in better solid classification.

[0105] The inlet 70, the outlet 82, and the U-shaped separator cross-sectional area of the entire U-shaped separator (including regions 74, 76) can be adjusted to manipulate the apparent gas velocity within the device to control the separation efficiency and selectivity. In some embodiments, the position of one or more separator walls can be adjustable, or movable baffles can be provided within one or more portions of the separator, which can be used to control the separation efficiency and selectivity. In some embodiments, the system can include a particle size analyzer downstream of the outlet 82, enabling real-time adjustment of the flow configuration through the U-shaped separator to achieve the desired separation.

[0106] Using a series-connected U-type inertial separator or a combination of a U-type inertial separator and a cyclone separator can provide flexibility to allow simultaneous achievement of a target overall separation efficiency and a target selectivity of larger and / or denser particles relative to smaller and / or less dense particles.

[0107] The secondary reactor 32 can also be equipped with baffles or structured internals, such as the modular grids described in U.S. Patent 7,179,427. Other types of internals that enhance contact efficiency and product selectivity / yield can also be used. The internals can enhance the distribution of the catalyst throughout the reactor and improve the contact between the feed vapor and the catalyst, resulting in an increase in the average reaction rate, an improvement in the overall activity of the catalyst, and optimization of the operating conditions to increase the production of light olefins.

[0108] The embodiments disclosed herein use Y zeolite or a conventional FCC catalyst to maximize the conversion of a heavy hydrocarbon feed. The Y zeolite or FCC catalyst has a smaller and / or lighter particle size than ZSM-5 or a similar catalyst used to enhance light olefin production in a countercurrent flow reactor. ZSM-5 or a similar catalyst has a larger particle size and / or is denser than the Y zeolite or FCC catalyst used to enhance catalyst type separation in each of the mixed flow reactor and the solid separator. The superficial gas velocity of the vapor in the second reactor is maintained such that it allows the entrainment of the Y zeolite or FCC catalyst and a portion of the ZSM-5 or ZSM-11 catalyst out of the mixed flow reactor, and the solid separator can utilize the difference in the single particle terminal velocity or the difference between the minimum fluidization / minimum bubbling velocity to separate and return the ZSM-5 / ZSM-11 to the mixed flow reactor. This concept allows the elimination of a two-stage FCC system, resulting in a simplified and efficient method. The catalyst used in this method can be a combination of Y zeolite / FCC catalyst and ZSM-5 or other similar catalysts, such as the catalysts mentioned in US5043522 and US5846402.

[0109] The entrainment of the two catalysts from the mixed flow reactor, subsequent separation, and the recycle and accumulation of the ZSM-5 / ZSM-11 catalyst in the mixed flow reactor eliminate any potential limitations on the superficial gas velocity in the secondary reactor. Thus, the use of a solid separation vessel provides process flexibility in the secondary reactor, allowing the secondary reactor to operate in a bubbling bed, turbulent bed, or fast fluidization regime, rather than restricting the operation to only the bubbling bed regime. The solid separation vessel can be a cyclone separator or other vessel where solids and gas are introduced at a common inlet, and by degassing, inertial forces, and centrifugal forces, the particles are separated based on size and / or density, with most of the smaller FCC-type particles entrained with the vapor outlet, and the larger and / or denser ZSM-5 or ZSM-11-type particles returned to the secondary reactor vessel 32 through a dense phase riser or downcomer.

[0110] In addition to the Figure 2 U-type particle separator described Figures 3 - 5 various additional particle separation devices for the embodiments herein are shown. Refer to Figure 3, a baffle chamber separator 900 for separating catalysts or other particles based on size and / or density may include an inlet 910, such as a horizontal pipe. The vapors and particles contained in the horizontal pipe then enter the chamber 912 before being deflected by the baffle 914. The chamber 912 is connected to a first vertical outlet 916 and a first horizontal outlet 918. The baffle 914 may be located in the middle of the chamber 912, near the inlet 910, or near the horizontal outlet 918 of the chamber. The baffle may have an angle or be movable such that the baffle can be used to deflect more or fewer catalyst particles and can be configured for a specific particle mixture.

[0111] The methods herein may utilize the baffle chamber separator 900 to separate larger and / or denser particles from smaller and / or less dense particles in a carrier gas (such as a hydrocarbon reaction effluent). The baffle chamber separator 900 may be configured to: separate at least a portion of a second particle type from the carrier gas and a first particle type, recover the second particle type via the first vertical outlet 916 and recover a mixture comprising the carrier gas and the first particle type via the first horizontal outlet 918. The separator may also include a distributor (not shown) disposed within or near the first vertical outlet for introducing a fluidizing gas to assist in further separating the first particle type from the second particle type.

[0112] Now referring to Figure 4 , a louver separator used in accordance with embodiments herein is shown. Similar to other separators illustrated and described, the louver separator 1000 may be used to separate catalysts or other particles based on size and / or density. The louver separator 1000 may include a vertical inlet 1010 connected to a chamber 1012, wherein one or more vertical sides 1014 of the chamber are equipped with slit outlets 1016, which may be described as louvers. The number of louvers may vary depending on the application (such as the desired particle mixture to be separated), and the angle of the louvers may be adjustable to control the amount of vapor passing through and exiting the louver outlets. The chamber 1012 is also connected to a first vertical outlet 1014 at the bottom of the chamber.

[0113] The methods herein may utilize the louver separator 1000 to separate larger and / or denser particles from smaller and / or less dense particles contained in a carrier gas (such as a hydrocarbon reaction effluent). The louver separator 1000 may be configured to: separate at least a portion of a second particle type from the carrier gas and a first particle type, recover the second particle type via the first vertical outlet 1014 and recover the carrier gas and the first particle type via the louver outlets 1016. The separator may also include a distributor (not shown) disposed within or near the first vertical outlet for introducing a fluidizing gas to facilitate additional separation of the first particle type from the second particle type.

[0114] Now referring toFigure 5 shows an inertial separator 1100 used in accordance with embodiments herein. Similar to other separators described and illustrated, the inertial separator 1100 can be used to separate catalysts or other particles based on size and / or density. The separator can include an inlet 1110 located at the top of a chamber 1112 and extending into the chamber 1112. In some embodiments, the height or arrangement of the inlet 1110 within the chamber 1112 can be adjustable. The separator can also include one or more side outlets 1114, 1116 (e.g., one to eight side outlets) and a vertical outlet 1118. The separator can also include a distributor (not shown) disposed within or near the vertical outlet 1118 for introducing a fluidizing gas.

[0115] A mixture 1172 of solid particles or catalysts having different sizes is introduced into the inlet 1110 along with a carrier gas stream. The gas in the mixture 1172 is preferentially directed to the outlets 1114, 1116 based on a pressure differential, and an inertial separation force is applied to the solids by turning the particles and the carrier gas from the inlet 1110 extending within the chamber 1112 to flow towards the outlets 1114, 1116. The inertial force separates the particles of different sizes / densities. Larger and / or heavier solid particles 1174 preferentially enter downward in section 1118 into a riser or downcomer (not shown) connected to the bottom of the separator, while lighter or smaller solid particles 1176 are preferentially carried with the gas stream to the outlets 1114, 1116, where a mixture of the small particles and the gas can be recovered.

[0116] In each separator described herein, by controlling the gas flow rate entering the downward riser / separation chamber and leaving the main gas flow outlet, the overall separation efficiency of the separator and the selectivity of separating heavier and / or larger particles from lighter or smaller particles can be manipulated. This extends to a fully sealed downcomer, where the only gas flow leaving the downcomer is that entrained by the exiting solid / catalyst stream.

[0117] In some embodiments, a gas distributor or additional steam / inert gas can be provided near the top of the heavy / dense particle outlet section (e.g., near the top of the riser inlet). The additional lift gas provided within the separator can further facilitate the separation of heavier and / or larger solid particles from lighter or smaller solid particles, as the additional gas can preferentially lift the lighter solid particles to the gas outlet, resulting in better solid classification.

[0118] The particle separators described herein can be disposed either outside or inside a container. Additionally, for example, in some embodiments, the large / dense particle outlet of the particle separator can be fluidly connected to an external container, providing for selectively recycling or feeding the separated particles into a desired reactor to maintain a desired catalyst balance.

[0119] The embodiments disclosed by the above method significantly increase the concentration of the required catalyst in the secondary reactor (vessel 32), thereby improving the light olefin yield. In addition, this method is also used as a method to separate the withdrawal and addition of ZSM-5 and ZSM5-11 from the withdrawal and addition of FCC catalyst. In summary, the FCC method proposed in the present disclosure produces a desired ZSM-5 or ZSM-11 catalyst additive-rich environment in the secondary reactor 32, which can preferentially convert light naphtha products (such as those derived from the primary reactor) to improve the yield of light olefins, while maximizing the middle distillate yield by applying optimal operating conditions in the primary reactor or riser.

[0120] Another advantage of the embodiments disclosed herein is that the integrated dual reactor scheme overcomes the thermal balance limitations in the independent C4 / naphtha catalytic cracking method. The secondary (mixed flow) reactor serves as a heat sink due to its integration with the catalyst regenerator, minimizing the requirements for a catalyst cooler when processing residue feedstocks.

[0121] The product vapors from the secondary reactor are transported to the first-stage reactor / disengaging vessel or reaction termination device, where these vapors are mixed and quenched with the products from the first stage and / or an external quench medium (such as LCO or steam) to minimize unwanted thermal cracking reactions. Alternatively, the product outlet line of the secondary reactor / solids separator can also be used to introduce an additional amount of heavy feed or recycle a portion of the feed from the first-stage reactor (riser reactor). This serves two purposes: (1) the catalyst in the solids separator vapor outlet line is mainly Y-type zeolite / conventional FCC catalyst, which preferably cracks these heavy feed molecules into middle distillates, and (2) this cracking reaction is endothermic, helping to reduce the temperature and residence time of the exiting product vapors.

[0122] In some embodiments disclosed herein, existing FCC units can be retrofitted with a secondary reactor as described above. For example, a reactor of appropriate size can be fluidly connected to an existing catalyst regeneration vessel to provide catalyst feed and return from the mixed flow vessel, and fluidly connected to an existing disengaging vessel to separate hydrocarbon products and catalyst. In other embodiments, a mixed flow reactor can be added to a grassroots FCC unit designed to operate in gasoline mode, light olefin mode, or diesel mode.

[0123] As described above regarding Figure 1 and Figure 6 The reactor systems described mainly relate to the production of light olefins, as well as the favorable concentration of catalysts in a mixed catalyst system to enhance the reactivity and selectivity of the system. Such reactor systems can also be used in other mixed catalyst systems where the concentration of one catalyst may be beneficial.

[0124] For example, in some embodiments, the reaction system can be used for gasoline desulfurization, where the catalyst mixture can include a smaller and / or less dense FCC catalyst (such as zeolite Y) and a larger and / or more dense catalyst (such as a gasoline desulfurization additive). Regarding Figure 7 such a method is described.

[0125] Now referring to Figure 7 , a simplified process flow diagram of a system for cracking and desulfurizing hydrocarbons according to embodiments disclosed herein is shown. The system includes a dual reactor configuration for producing olefins such as propylene and ethylene from a petroleum feedstock or other hydrocarbon stream. For example, the first reactor 3 can be a riser reactor for cracking heavier hydrocarbon feeds. The second reactor 32 is a fluidized bed reactor, which can be equipped with baffles or internals. The cracked hydrocarbon product including olefins and / or light naphtha product from the first reactor 3 and / or a similar feed stream from an external source can be processed in the second reactor 32 to improve the quality of the product, such as reducing the total sulfur content of the hydrocarbons processed in the second reactor.

[0126] The heavy petroleum residue feed is injected through one or more feed injectors 2 located near the bottom of the first reactor 3. The heavy petroleum feed contacts the hot regenerated catalyst introduced through the J-bend 1. The catalyst fed to the first reactor 3 is a catalyst mixture that includes a first catalyst (such as a Y-zeolite based catalyst) for selectively cracking heavier hydrocarbons and a second catalyst for selectively desulfurizing naphtha range hydrocarbons, which can also be used in combination with other catalysts. The first and second catalysts can differ in one or both of particle size and density.

[0127] The heat required to evaporate the feed and / or raise the feed temperature to the desired reactor temperature (such as in the range of 500 °C to about 700 °C) and the endothermic (heat of reaction) can be provided by the hot regenerated catalyst from the regenerator 17.

[0128] After most of the cracking reactions are completed, the mixture of product, unconverted feed vapor, and spent catalyst flows into a two-stage cyclone separator system housed in a cyclone containment vessel 8. The two-stage cyclone separator system includes a primary cyclone separator 4 for separating the spent catalyst from the vapor. The spent catalyst is discharged through the primary cyclone dipleg 5 into a stripping column 9. Fine catalyst particles entrained by the separated vapor from the primary cyclone separator 4 and product vapor from the second reactor 32, introduced through flow line 36a and a single-stage cyclone separator 36c, are separated in a secondary cyclone separator 6. The collected catalyst mixture is discharged through a dipleg 7 into the stripping column 9. The vapor from the secondary cyclone separator 6 is discharged through a secondary cyclone outlet 12b (which may be connected to a plenum 11) and then sent to a fractionator / gas fractionation unit 410 for product recovery (including the desired olefins). If desired, light cycle oil (LCO) or steam is introduced as a quench medium through a distributor line 12a to further cool the product vapor.

[0129] The fractionator 410 can be, for example, the main fractionator of an FCC unit and can produce various hydrocarbon fractions including a light olefin-containing fraction 412, a naphtha fraction 414, and a heavy fraction 416, as well as various other hydrocarbon fractions. The product delivered to the fractionator / gas unit 410 can include other light gases such as hydrogen sulfide that may be produced during desulfurization; separators, absorbers, or other unit operations may be included where it is necessary to separate these impurities upstream of the main fractionator / gas unit.

[0130] The spent catalyst recovered through diplegs 5, 7 is stripped in the stripping column 9 to remove interstitial vapor (hydrocarbon vapor trapped between catalyst particles) by countercurrent contact with steam, which is introduced through a steam distributor 10 to the bottom of the stripping column 9. The spent catalyst is then transferred to a regenerator 17 through a spent catalyst riser 13a and a lift line 15. A spent catalyst slide valve 13b located on the spent catalyst riser 13a is used to control the catalyst flow from the stripper 9 to the regenerator 17. A small portion of combustion air or nitrogen can be introduced through a distributor 14 to assist in the smooth transfer of the catalyst.

[0131] The coked or spent catalyst is discharged through a spent catalyst distributor 16 at the center of the dense-phase regenerator bed 24. Combustion air is introduced by an air distributor 18 located at the bottom of the regenerator bed 24. The coke deposited on the catalyst is then burned off in the regenerator 17 by reaction with the combustion air. Catalyst fines carried with the flue gas are collected in a primary cyclone separator 19 and a secondary cyclone separator 21 and discharged through respective diplegs 20, 22 into the regenerator catalyst bed. The flue gas recovered from the outlet of the secondary cyclone separator 21 is directed through a regenerator plenum 23 to a flue gas line 50 for downstream waste heat recovery and / or power recovery.

[0132] A first portion of the regenerated catalyst mixture is discharged through a regenerated catalyst riser 27 that is in fluid communication with the J-bend 1. The catalyst flow from the regenerator 17 to the reactor 3 can be regulated by a slide valve 28 located on the regenerated catalyst riser 27. The opening of the slide valve 28 is adjusted to control the catalyst flow to maintain the desired top temperature in the reactor 3.

[0133] In addition to the lift steam, a feed stream of external flows such as C4 olefins and naphtha or the like is provided as a lift medium and injected into the J-bend 1 through a gas distributor 1a located in the Y-section to enable the smooth transfer of the regenerated catalyst from the J-bend 1 to the reactor 3. The J-bend 1 can also be used as a dense-phase bed reactor for cracking C4 olefin and naphtha streams into light olefins under conditions favorable for such reactions.

[0134] A second portion of the regenerated catalyst mixture is discharged into a second reactor 32 through a riser 30. A valve 31 can be used to control the catalyst flow from the regenerator 17 to the second reactor 32 based on a vapor outlet temperature set point. One or more hydrocarbon fractions (such as a naphtha stream) can be injected into the bottom of the catalyst bed in a liquid or vapor phase through one or more feed distributors 34 (34a, 34b). In some embodiments, the naphtha feed can include some or all of the naphtha 414 from the fractionation column 410. The second reactor 32 operates in a mixed flow mode, where a portion of the regenerated catalyst flows downward (from the top to the bottom of the reactor bed) and / or circulates within the vessel 32, and a portion of the regenerated catalyst mixture and the feed hydrocarbon stream flow upward (from the bottom to the top of the reactor bed, with the smaller / less dense particles being carried out of the reactor top with the effluent hydrocarbon).

[0135] The second reactor 32 can be equipped with baffles or structured internals (not shown) that assist in the intimate contact and mixing of the catalyst and the feed molecules. These internals can also help to minimize channeling, bubble growth, and / or coalescence. The second reactor 32 can also be enlarged along different portions of its length to maintain a constant or desired superficial gas velocity within each portion.

[0136] After the reaction is complete, the catalyst is stripped at the bottommost portion of the second reactor 32 using steam introduced through a distributor 35 as a stripping medium to separate the entrained hydrocarbon feed / product. Then, the spent catalyst recovered at the bottom of the reactor 32 can be discharged through a catalyst discharge line 418. Alternatively, the spent catalyst recovered at the bottom of the reactor 32 can be transferred to the regenerator 17, as described above with respect to Figure 1(via riser 37 and lift line 40 through spent catalyst distributor 41, where combustion air or nitrogen can be introduced through distributor 39 to enable smooth transfer of the catalyst to regenerator 17). A valve (not shown) can be used to control the flow of catalyst from the second reactor 32.

[0137] As described above, the second reactor 32 uses two different catalysts, which can differ in one or both of particle size and / or density, such as less dense and / or smaller Y-zeolite or FCC catalyst and larger and / or denser desulfurization catalyst. The superficial gas velocity in the second reactor 32 is maintained such that substantially all or most of the lighter, smaller catalyst and a portion of the larger and / or denser catalyst are carried out of the reactor with the hydrocarbon product and steam recovered through effluent flow line 45. As described above, a portion of the larger and / or denser catalyst can remain within the reactor 32, forming a dense bed towards the lower part of the reactor.

[0138] Thus, the effluent from reactor 32 recovered through flow line 45 can include a desulfurized hydrocarbon product, unreacted hydrocarbon feedstock, steam (stripping medium), and a catalyst mixture that includes substantially all of the lighter and / or smaller catalyst introduced into reactor 32 and a portion of the heavier and / or larger catalyst. The effluent can then be conveyed via flow line 45 to solid separator 47. Separator 47 can be a separator configured to separate the two types of catalysts based on their physical properties (i.e., particle size and / or density). For example, separator 47 can use differences in inertial forces or centrifugal forces to separate the smaller and / or lighter catalyst from the larger and / or heavier catalyst. Solid separation vessel 47 is an external vessel of the second reactor 32 and operates with hydrodynamic characteristics that enhance its separation according to the physical properties of the two types of catalysts.

[0139] After separation in separator 47, the smaller and / or lighter catalyst (Y-zeolite / FCC catalyst) is then conveyed from separator 47 through outlet line 36a to a common disengager or holding vessel 8 that houses the riser reactor cyclone and / or reaction termination system. The larger and / or heavier desulfurization catalyst can be returned to the mixed flow reactor 32 through flow line 49 to continue reacting with the hydrocarbon feed introduced through distributors 34a / b.

[0140] Entrainment of substantially all of the lighter / smaller catalysts and a portion of the heavier and / or larger catalysts, subsequent separation, and recycle of the heavier and / or larger catalysts back into reactor 32 can allow for significant accumulation of the larger and / or heavier desulfurization catalysts in reactor 32. Since this catalyst is more selective for the desulfurization of naphtha-range hydrocarbons, the accumulation of the larger and / or heavier catalysts can provide selectivity and yield advantages. Additionally, as described above, operating the reactor in a fluidized flow mode to entrain both types of catalysts can provide enhanced reactor operability or flexibility in operation.

[0141] A hydrocarbon feed such as heavy vacuum gas oil or heavy residue oil feed, light cycle oil (LCO), or steam can be injected as a quench medium into the outlet line 36a through distributor 36b. The flow rate of this quench medium can be controlled by setting the temperature of the stream entering the holding vessel 8. All vapors from the second reactor 32, including those fed through distributor 36b, are discharged into the dilute phase of the holding vessel 8 through a single-stage cyclone separator 36c. Using a hydrocarbon feed as the quench medium is preferred because of its dual purpose of cooling the product from the second reactor 32 and enhancing the production of middle distillates.

[0142] The first-stage reactor 3 (e.g., a riser reactor) can be operated in a fast-fluidization mode (e.g., with a gas superficial velocity of about 3 to about 10 m / s in the bottom section) and a pneumatic conveying mode (e.g., with a gas superficial velocity in the range of about 10 to about 20 m / s in the top section).

[0143] The WHSV in the second reactor 32 is typically in the range of about 0.5 h -1 to about 50 h -1 ; the vapor and catalyst residence times can vary between about 2 and about 20 seconds. When necessary, additional catalyst can be introduced through one or more flow lines 42, 43. For example, fresh or supplementary FCC or Y-zeolite catalyst or a mixture of the two can be introduced into the regenerator 17 via flow line 42, and fresh or supplementary gasoline desulfurization additive can be introduced into the second reactor 32 via flow line 43. For example, the overall system catalyst inventory can be maintained by withdrawing the mixed catalyst from the regenerator 24 and / or the reactor 32. As described above, the catalyst inventory and accumulation of the preferred catalyst within the reactor 32 can be controlled. Additionally, in some embodiments, as described above, the catalyst hopper 26 can be used in combination with the catalyst withdrawal line 25, the pressure balance line 29, and the riser 27.

[0144] Similarly, Figure 7The reactor system can be used for the beneficial treatment of heavy hydrocarbon feeds, including heavy crude oil or virgin crude oil. In such an embodiment, the mixed catalyst system can include, for example, smaller and / or less dense FCC catalysts (such as zeolite-Y) and larger and / or more dense heavy oil treatment additives. For example, the heavy oil treatment additive can be an active matrix catalyst, a metal trapping additive, a coarse and / or dense Ecat (equilibrium catalyst), a matrix or binder type catalyst (such as kaolin or sand), or a high matrix / zeolite ratio FCC catalyst, etc. The heavy oil treatment additive may have minimal catalytic activity for the cracking of heavy hydrocarbons and may simply provide the surface area required for the thermal cracking reaction to occur. The heavy hydrocarbon feed can be introduced into the reactor 32 through distributors 43a / b, and the system can be operated as described above to enhance the treatment of heavy hydrocarbon feeds.

[0145] When operating under heavy hydrocarbon processing conditions, the WHSV in the second reactor 32 is typically in the range of 0.1 - 100 h -1 ; the steam and particle residence times can vary between 1 - 400 seconds. Supplementary particles can be introduced via one or more lines 42, 43 as needed; it may be advantageous to add FCC or Y-type catalyst to the regenerator 17 through line 42 and add the heavy oil treatment additive to the second reactor 32 via line 43. The overall system activity is maintained by withdrawing particles from the second reactor 32 and the regenerator 24 via line 418. The solid inventory and accumulation of the preferred heavy oil treatment additive in the second reactor 32 can be controlled by addition via line 43 and withdrawal via line 418. The operating temperature in the second reactor 32 is controlled using the catalyst from the regenerator 17 line 30 via valve 31 and can be in the range of 400 - 700 °C. In some embodiments, the product of the second reactor 32 can be substantially the feed to the primary riser reactor 3. Additionally, in some embodiments, as described above, the catalyst hopper 26 can be used in combination with the catalyst withdrawal line 25, the pressure equalization line 29, and the riser 27.

[0146] Typically, Figure 1 、 6The process flow diagrams shown in FIGS. 6 and 7 use catalyst / particle separation technology to process additional or recycled hydrocarbon feedstock in a secondary vessel. The catalyst mixture recycled through the system can include catalysts selective for specific reactions (such as cracking, desulfurization, demetallization, denitrification, etc.), as described above, where the catalysts in the mixture are selected to have different physical properties such that the desired catalyst can be concentrated in the secondary reactor. The regenerated catalyst is fed into the secondary reactor / vessel, which can operate in fast fluidization, bubbling, or turbulent bed operation (depending on the application). The effluent from the secondary reactor / vessel enters separator 47, where the primary and secondary catalysts are separated based on size and / or density, and the separator bottoms rich in the secondary catalyst are recycled back to the secondary reactor / vessel. The secondary reactor / vessel has an optional catalyst draw-off, which may be advantageous depending on the application and the different hydrocarbon feeds according to the application. The concentration of the secondary catalyst can improve the operability, flexibility, and selectivity of the entire reaction system.

[0147] As previously referenced Figure 2 Separator 47 described above can be used to increase the productivity and flexibility of the mixed catalyst hydrocarbon processing system, where separator 47 can be located at other advantageous positions within the system. These methods and systems are further described below with reference to FIGS. 8 - 11, where like reference numerals represent like parts.

[0148] Now referring Figure 8A , a simplified process flow diagram of a system for converting hydrocarbons and producing olefins according to an embodiment disclosed herein is shown, where like reference numerals represent like parts. Figure 8A The process scheme of FIG. 12 adds a catalyst holding vessel 510, which is supplied with regenerated catalyst from the FCC regenerator through a catalyst draw-off line 30 and valve 31. The holding vessel 510 can be fluidized with a fluidizing medium (such as air, nitrogen, or steam) introduced, for example, through a flow line 516. The holding vessel effluent 45 is sent to separator 47, where the catalyst mixture is separated. The separator bottoms 49 rich in the larger and / or heavier catalyst are recycled back to the catalyst holding vessel 510, and the concentration of the larger and / or denser catalyst will increase when recycled back to the catalyst holding vessel 510. In this embodiment, the remaining stream 514 from separator 510 returns to disengaging vessel 8. The bottoms 512 of the holding vessel can be coupled to a slide valve (not shown), which can control the feed of catalyst into the secondary reactor / vessel 32, which can operate in a similar manner as described above with respect to Figure 1 , 6 , 7. Advantageously, the catalyst concentrated in vessel 510 is not saturated with hydrocarbons and allows for a lower contact time with the catalyst in the secondary reactor / vessel 32.

[0149] Figure 8B shows a system similar to Figure 8A , except that the catalyst recovered from the separator 47 via the flow line 514 is returned to the catalyst regenerator 17 instead of being sent to the disengaging vessel 8. The vessel to which the catalyst in the flow line 514 is sent can depend on the type of fluidizing gas introduced via the flow line 516 and the ability of the system to receive flow from the regenerator 17 or the vessel 8 via the flow lines 50 and 12b respectively. For example, in the case where the fluidizing gas is steam, the catalyst in the flow line 514 is preferably sent to the vessel 8; for example, in the case where the fluidizing gas is air or nitrogen, the catalyst in the flow line 514 is preferably sent to the regenerator 17.

[0150] Figure 8A and 8B shows that the smaller particles recovered via the flow line 514 are sent to the regenerator 17 or the disengaging vessel 8, and the larger and / or heavier particles are returned to the secondary reactor 32 via the flow line 512. The embodiments herein also contemplate returning the smaller and / or lighter particles recovered via the separator 47 and the flow line 514 to the secondary reactor 32, while recycling the larger and / or heavier particles to the regenerator 17 or the stripper 9.

[0151] Figure 8A and 8B also shows a system having a vessel 510 that accumulates / concentrates large particles for the secondary reactor. If single-pass separation is sufficient, as Figure 9A and 9B shown (where the same reference numerals represent the same parts), the containment vessel 510 can be excluded from the system. In these embodiments, the catalyst mixture is fed directly from the catalyst regenerator 17 to the separator 47 via the dipleg 30. Air or other fluidizing gas can be supplied via the streamline 610 at a flow rate sufficient for inertial separation. Smaller / lighter particles can be recovered via the flow line 612, and larger and / or heavier particles can be recovered via the flow line 614. Figure 9A shows that the larger and / or heavier particles are sent to the secondary reactor 32, while Figure 9B shows that the smaller and / or lighter particles are sent to the secondary reactor 32.

[0152] Figure 9A and 9B shows that a portion of the particles is returned to the regenerator 17. Similar to the above description regarding Figure 8A and 8B , the particles not fed to the reactor 32 can be returned to the regenerator 17 or the disengaging vessel 8, and this can depend on the fluidizing medium and / or the downstream processing capacity.

[0153] Figure 9A and9B The process scheme shown uses a single-pass version of the separator rather than those versions that introduce recycle to increase concentration. In this scheme, the regenerated catalyst is directed to the separator, where the bottoms or tops of the separator can be directed to a secondary reactor. If the bottoms are to be directed, the catalyst will be enriched based on larger and / or denser particles. If the tops of the separator are directed to the secondary reactor, the catalyst will be enriched in smaller and / or less dense particles. This scheme can also be arranged such that there is no secondary reactor and the separator is located between the regenerator and the main riser reactor, and the separator concentrates a catalyst similar to that described in the method below Figure 11 as described.

[0154] Figure 8A The embodiment of 6A / B separates the recycle catalyst from the secondary reactor, achieving a higher concentration of the desired catalyst in the secondary reactor, but requires additional capital costs. The embodiment of 6A / B also separates the recycle catalyst from the secondary reactor, achieving a modest increase in the concentration of the desired catalyst compared to, for example Figure 7 the flow chart shown, but at a lower capital cost than the embodiment in Figure 9A / B.

[0155] Now referring to Figure 10 , a simplified process flow diagram of a system for processing hydrocarbons according to an embodiment disclosed herein is shown, where like reference numerals represent like parts. This process flow removes the secondary reactor and causes the separator 47 to receive the effluent from the main riser 3. The riser effluent containing the mixed catalyst can be directed to the separator 47, where a portion of the catalyst is recycled from the separator bottoms 710 to the riser 3, thereby enriching the concentration of the larger and / or heavier catalyst in the riser reactor 3. The tops 712 of the separator 47 will continue to the stripper vessel 8, where the hydrocarbon product will be separated from the remaining catalyst. This configuration can also be used as a method for recycling spent catalyst to the riser 3 with a catalyst mixture that is not graded.

[0156] The enriched catalyst fraction 710 can be introduced into the riser 3 upstream or downstream (as shown) of the regenerated catalyst feed inlet from the standpipe 27, and in some embodiments can be introduced at one or more points along the length of the riser reactor 3. The inlet point can be based on the secondary hydrocarbon feed, the temperature of the recycle catalyst 710, and other variables available to advantageously process the hydrocarbons in the riser reactor 3.

[0157] The hydrocarbon product recovered from the separation vessel 8 / stripper 9 can be sent to the fractionator / gas plant 720 as described above for separation and recovery of one or more hydrocarbon fractions 722, 724, 726, 728, 730. In the embodiments herein, one or more hydrocarbon fractions recovered from the fractionator / gas plant can be recycled to the riser reactor 3 or secondary reactor 32 for further processing.

[0158] A simplified process flow diagram of a system for treating hydrocarbons according to embodiments disclosed herein is shown, where like numbers represent like parts. In this process scheme, the regenerator catalyst hopper 26 is fluidly connected to the riser reactor 3. The regenerated mixed catalyst (which contains smaller and / or less dense catalyst and larger and / or more dense catalyst) flows from the regenerator 17 to the regenerated catalyst hopper 26. The hopper 26 is fluidized with steam and / or air provided by the distributor 810. The overhead effluent 816 of the hopper flows into the separator 47. The catalyst is separated in the separator 47 as the aforementioned separation device, and the bottoms 814 rich in larger and / or more dense catalyst can be sent back to the regenerated catalyst hopper 26 (e.g., when fluidized with air) or the separation vessel 8 (e.g., when fluidized with steam). This will increase the concentration of larger and / or more dense catalyst in the regenerated catalyst hopper 26. The overhead 812 of the separator 47 can be directed to the regenerator or stripper vessel. The bottoms 27 of the regenerator catalyst hopper has a draw with a slide valve 28 that controls the flow of catalyst rich in larger and / or more dense catalyst to the riser 3. In this way, the riser 3 operates at an effective catalyst concentration higher than the inventory in the system, creating a preferred product according to the nature of the catalyst.

[0159] The above regarding Figure 11 The catalyst concentration in the regenerated catalyst hopper described can be carried out intermittently. The system can circulate the catalyst mixture through the riser, stripper, and regenerator when the hopper 26 is not sufficiently fluidized to entrain the catalyst to the separator 47. When the desired product mixture, hydrocarbon feed, or other factors change (where it may be advantageous to operate with a higher concentration of a particular catalyst in the catalyst mixture), the catalyst in the regenerated hopper 26 can be fluidized and separated using the separator 47. When the factors change again, the fluidization of the catalyst hopper can be aborted. In this way, the flexibility of the system in terms of products and feeds can be increased.

[0160] Although Figure 10 and 11 Shown with a single riser, solid separation devices can be used to enhance the performance of a multi-riser system. For example, a dual-riser system can benefit from the concentration of one catalyst in the riser, which can process a different feed than the second riser.

[0161] Embodiments of the present disclosure can utilize various types of catalysts or particles to perform the desired reactions, where a common regenerator can be used to regenerate a mixture of catalysts, and a separator is positioned advantageously to enrich a particular catalyst contained in the catalyst mixture in one or more reactors. Embodiments of the present disclosure can be used to improve unit operations and enhance the selectivity and flexibility of the reaction system, for example, for applications including light olefin production, gasoline desulfurization, and heavy oil processing.

[0162] As described above, light olefin production can include various light, medium, and heavy hydrocarbon feeds to the riser. The feed to the second reactor 32 can include naphtha (e.g., straight-run naphtha or recycled catalytic naphtha) and other feeds. The catalyst mixture for light olefin production can include a combination of smaller and / or less dense catalysts (e.g., FCC catalysts (e.g., zeolite Y)) and heavier / more dense catalysts (e.g., ZSM-5 or ZSM-11, etc.). Other cracking catalysts can also be used. Various catalysts for hydrocarbon cracking are disclosed in U.S. Patent Nos. 7,375,257, 7,314,963, 7,268,265, 7,087,155, 6,358,486, 6,930,219, 6,809,055, 5,972,205, 5,702,589, 5,637,207, 5,534,135, and 5,314,610, etc.

[0163] As described above, embodiments for gasoline desulfurization can include various light, medium, and heavy hydrocarbon feeds to the riser. The feed to the second reactor 32 can further include naphtha (e.g., straight-run naphtha or recycled catalytic naphtha) and other feeds. The catalyst mixture for light olefin production can include smaller and / or less dense catalysts (e.g., FCC catalysts (e.g., zeolite Y)) and larger and / or more dense catalysts with desulfurization functionality (e.g., MgO / Al2O3 promoted with various metals). Other desulfurization catalysts as disclosed in U.S. Patent Nos. 5,482,617, 6,482,315, 6,852,214, 7,347,929, etc. can also be used. In some embodiments, the catalyst mixture can include a cracking catalyst composition having desulfurization activity, such as those disclosed in US5376608.

[0164] As described above, embodiments for heavy oil treatment may include various light, medium, and heavy hydrocarbon feeds to the riser. The feed to the second reactor 32 may include hydrocarbons or hydrocarbon mixtures having a boiling point or boiling point range above about 340 °C. Hydrocarbon feeds that may be used with the methods disclosed herein may include various refinery and other hydrocarbon streams such as petroleum atmospheric or vacuum residua, deasphalted oil, deasphalted tower bottoms, bottoms from hydrocracking atmospheric or vacuum columns, straight run vacuum gas oil, hydrocracked vacuum gas oil, fluid catalytic cracking (FCC) slurry oil, vacuum gas oil from ebullated bed hydrocracking processes, shale-derived oil, coal-derived oil, tar sand bitumen, tall oil, biologically-derived crude oil, black oil, and other similar hydrocarbon streams or combinations thereof, each of which may be straight run, process-derived, hydrocracked, partially desulfurized, and / or partially demetallized streams. In some embodiments, the resid hydrocarbon fraction may include hydrocarbons having a normal boiling point of at least 480 °C, at least 524 °C, or at least 565 °C. Catalyst mixtures for heavy hydrocarbon treatment may include smaller and / or less dense catalysts (such as FCC catalysts (such as zeolite Y)) and larger and / or more dense catalysts (such as active matrix catalysts, metal trapping catalysts, coarse / dense Ecat (equilibrium catalyst), matrix or binder type catalysts (such as kaolin or sand), or high matrix / zeolite FCC catalysts). Other cracking catalysts may also be used, such as one or more disclosed in US5160601, US5071806, US5001097, US4624773, US4536281, US4431749, US6656347, US6916757, US6943132, and US7591939, etc.

[0165] The systems herein may also be used to pretreat heavy crude oil or virgin crude oil, such as crude oil or bitumen recovered from tar sands. For example, prior to further processing the treated heavy crude oil in downstream operations, such as Figure 1 or the reactor 32 in 9, etc., may be used to pretreat the bitumen, and the downstream operations may include separation in a downstream separation system and recycle of one or more fractions for further conversion in reactor 3. The ability to pretreat heavy crude oil with preferred particles in a particulate or catalyst mixture may advantageously allow for the integration of heavy crude oil treatment that would otherwise be detrimental to catalyst and overall system performance.

[0166] Embodiments of the present disclosure describe effective and preferred concentration of a catalyst mixture separated by a separator and a catalyst within a mixture in a reactor. As shown, the catalyst concentrated in the reactor is illustrated as returning from a separator near the top of the reactor or vessel. Embodiments of the present disclosure also contemplate returning the catalyst from the separator to the middle or lower part of the reactor, and where the catalyst returns can depend on the hydrocarbon feed being processed, the type of catalyst in the mixture, and the catalyst gradient desired within the reactor vessel. Embodiments of the present disclosure also contemplate returning the catalyst to multiple locations within the reactor. While providing the ability to enhance the concentration of a particular catalyst or particle within a mixture in a given reactor, embodiments of the present disclosure can also be used for a catalyst system; the particle separator and system described herein can increase the catalyst / oil ratio, which increases the catalytic contact time.

[0167] As described above, various embodiments of the present disclosure use a secondary reactor that operates in a fluidized state sufficient to entrain a first cracking catalyst and a second cracking catalyst in a hydrocarbon product recovered as an effluent from the top outlet of the secondary reactor. In some embodiments, for example Figure 12 as shown, the secondary reactor can be a secondary riser reactor that operates in a fluidized state sufficient to entrain a first cracking catalyst and a second cracking catalyst in a hydrocarbon product recovered as an effluent from the top outlet of the secondary reactor. In other embodiments such as Figure 12 shown, the secondary reactor can be a bubbling or fluidized bed reactor that operates in a fluidized state sufficient to entrain a first cracking catalyst, a portion of the second cracking catalyst, and a hydrocarbon product. The effluent can then be fed to a solid separation vessel to separate the cracked hydrocarbon product and the first cracking catalyst from the second cracking catalyst. The solid separation vessel can be an external vessel of the reactor and can operate under hydrodynamic characteristics that enhance its separation based on physical properties of the two types of catalysts such as particle size and / or density. The separated catalyst is selective for cracking C4 and naphtha range hydrocarbons and can then be returned to the reactor to continue the reaction, enhancing the concentration of the catalyst within the reactor for selectively cracking C4 and naphtha range hydrocarbons, improving the selectivity of the overall process, and also improving the flexibility of the overall process due to the enhanced operating window.

[0168] Now referring to Figure 12 , Figure 12 there is shown another process scheme according to an embodiment of the present disclosure, where like numerals represent like parts. Similar to other process schemes, such as Figure 1 and 6 those shown, two catalyst / solid particles are used, the first catalyst being a smaller and / or lighter conventional FCC catalyst, while the second catalyst is a larger and / or heavier catalyst such as ZSM-5 or ZSM-11.

[0169] The mixed first catalyst and second catalyst can be fed from a common regenerator 17 via a flow line 30 through a control valve 31 to the bottom of a secondary riser reactor 171. At the bottom of the secondary riser reactor 171, the catalyst is mixed with the catalyst fed via a flow line 174a, the flow rate of which can be adjusted by a control valve 174. The catalyst in the flow line 174a can have a higher concentration of larger and / or heavier second cracking catalysts, such as ZSM-5, which is beneficial for the naphtha cracking reaction to produce light olefin products, such as propylene.

[0170] Then the mixed catalyst having a higher concentration of larger and / or heavier second cracking catalysts than in the mixture provided from the regenerator 17 can be contacted with hydrocarbons in the secondary riser reactor 171. For example, the naphtha feed can be introduced through a flow line 143, and the lift steam can be fed through a flow line 135. The naphtha feed can be naphtha from a downstream product fractionator, as described above, or can be a naphtha feed from other units, such as coker naphtha, etc. If desired, the naphtha feed can also be fed or withdrawn from different locations not shown in Figure 12 the figure.

[0171] The naphtha cracking reaction occurs in the secondary riser reactor 171, and the naphtha feed and steam feed are sufficient to entrain the cracked hydrocarbon products with the first cracking catalyst and the second cracking catalyst. The product stream enters a solid separation device (SSD) 47 together with the catalyst mixture, which can be used to promote the concentration of denser and / or larger second cracking catalysts. The SSD 47 can separate the effluent from the secondary riser reactor 171 into a vapor / first cracking catalyst stream 147a and a second cracking catalyst stream 147b. As described above, the second cracking catalyst recovered from the separator can be recycled back to the secondary reactor to continue the reaction.

[0172] Then the cracked hydrocarbons from the secondary riser reactor and the separated first cracking catalyst can be fed to a disengaging vessel 170, and the first cracking catalyst is from the cracked hydrocarbon products. The cracked hydrocarbon products, including light olefins, C4 hydrocarbons, naphtha-range hydrocarbons, and heavy hydrocarbons, can be recovered through a flow line 180 (as further described below), and then can be separated to recover the desired products or product fractions. In some embodiments, the cracked hydrocarbon products recovered via the flow line 180 can be combined with the hydrocarbons in the flow line 12 and fed to a common separation system for the combined processing and recovery of the desired products or product fractions.

[0173] In some embodiments, as Figure 12As shown, the SSD 47 can be located within the stripping vessel 170. The stripping vessel 170 can accommodate an inner vessel 173 that receives a larger and / or denser second cracking catalyst from the SSD 47. An annular region 178 located between the inner wall of the stripping vessel 170 and the outer wall of the inner vessel 173 can receive a smaller and / or less dense first cracking catalyst.

[0174] In the SSD 47, as described above, the secondary riser reactor effluent can be separated into a vapor / first cracking catalyst stream 147a and a second cracking catalyst stream 147b. Based on density and / or particle size, the catalyst stream 147b having a concentrated larger and / or heavier ZSM-5 second catalyst can be fed to the riser 172, then into the inner vessel 173 and ultimately fed back to the secondary riser reactor 171 through the control valve 174. The inner vessel 173 can be open such that any entrained gas that can be recovered with the catalyst stream 147b can be separated from the catalyst in the inner open vessel 173, exit the top of the open vessel 173, mix with the vapor in the vessel 170, and be recovered with the product through the flow line 180.

[0175] The level of the catalyst in the inner vessel 173 can be controlled by the control valve 174 and an associated controller or control system, and the level indication can also be used to adjust the vapor split ratio of the SSD 47 to control the separation efficiency of the larger and / or denser second cracking catalyst particles. In this way, the conditions can be adjusted such that a portion of the second cracking catalyst particles can be carried into the cyclone separator and recovered in the annular region for return to the regenerator for regeneration.

[0176] The vapor / first cracking catalyst stream 147a enters the cyclone separator 176, which can separate the first cracking catalyst from the product gas. Then, the separated particles having a concentrated smaller and / or lighter FCC catalyst can be fed to the annular section 178 through the dipleg 177. The catalyst in the annular section 178 can be fed to the regenerator 17 through the flow line 175a, and its flow rate can be controlled by the control valve 175. The level of the catalyst in the annular region 178 can be controlled by the control valve 175. Similar to the primary and secondary cyclone separators 4, 6, in the stripping vessel 8, the vessel 170 can also accommodate additional cyclone separators (not shown) to completely separate or recover the product gas from the catalyst in the vessel 170. The product gas, including the entrained gas emitted from the inner vessel 173 and the annular region 178, and those gases recovered from the cyclone separator 176, can be recovered via the plenum 179 and fed to the product fractionation via the flow line 180.

[0177] In addition to boosting the steam 135, a feed stream, such as C4 olefins and naphtha or similar external logistics, can be injected as a boosting medium into the secondary riser reactor 171 through the gas distributor 171a, which can be located in the Y-section for the smooth transfer of the regenerated catalyst from the flow lines 174a and 30 to the secondary riser reactor 171. The lowermost part of the secondary riser reactor 171 can also be used as a dense bed reactor for cracking the C4 olefins and naphtha streams into light olefins under favorable conditions. For such reactions, the favorable conditions are, for example, a WHSV of 0.5 h -1 to 50 h -1 , a temperature of 640 °C to 750 °C, and a residence time of 3 seconds to 10 seconds.

[0178] The integration of the transport zone 171 and the disengaging vessel 170 can also be used in other embodiments described herein. For example, referring to Figure 8A and Figure 8B , the secondary vessel 510 and the SSD 47 can be arranged similarly to the transport zone 171 and the separation vessel 170 to provide a vapor product stream 180 (514) and a concentrated second cracking catalyst stream 174a (512), which can be provided to the secondary reactor 32. For example, Figure 8C such an embodiment is shown in Figure 11 . As another example, a similar integration of the transport zone 171 and the disengaging vessel 170 can equally be used in the

[0179] embodiments. Figure 9A and Figure 9B In addition, as in the embodiments of

[0180] the outlets 75a, 74a can be configured such that the lighter / smaller particles are concentrated in the second riser reactor 71. For example, the heavier / larger particles in the inner vessel 73 can be returned to the regenerator 24, while the lighter / smaller particles in the annular region 78 can be fed into the second riser reactor 71. In this way, the particles most suitable for converting the feed entering the second riser reactor 71 can be concentrated within the reactor.

[0181] Embodiments of the present disclosure may employ two types of catalyst particles, such as Y-zeolite / FCC catalysts having a smaller particle size and / or a smaller density and ZSM-5 particles that are larger in size and / or denser than the former. A separator with selective recycle may be used to preferentially separate the Y-zeolite from the ZSM-5 catalyst. Using such a catalyst system allows for the entrainment of the lighter and smaller particles, thereby retaining the ZSM-5 type particles within an additional new reactor bed. In the presence of a ZSM-5 type catalyst preferably used to maximize the yield of light olefins from C4 and naphtha feed streams, the reactants undergo selective catalytic cracking. A separator is a device capable of facilitating the separation of the two catalysts due to the difference in their particle size and / or density. Examples of separators with selective recycle may be cyclones, screen separators, mechanical sieves, gravity chambers, centrifugal separators, in-line or pneumatic classifiers, or other types of separators that can be used to effectively separate particles based on size and / or hydrodynamic properties. The separator is connected to the top of the second reactor, which is in fluid communication with the second reactor, as well as the regenerator and the first reactor / stripper.

[0182] In some embodiments, the reactor may be provided with baffles or modular grid internals. This provides intimate contact between the catalyst and the hydrocarbon feed molecules, helps to break up the gas bubbles, and avoids the growth of gas bubbles due to coalescence, channeling, or bypassing of the catalyst or the feed.

[0183] Typically, a fresh catalyst make-up used to maintain catalyst activity is introduced into the regenerator bed using plant air. Instead, it is recommended to use steam or nitrogen as the transport medium to directly inject the required high concentration of catalyst / additive into the second reactor bed. This helps to create an increasing concentration and favorable selectivity.

[0184] The reactor configurations described herein provide sufficient flexibility and operating windows to adjust operating conditions such as weight hourly space velocity (WHSV), catalyst and hydrocarbon vapor residence time, reaction temperature, catalyst / oil ratio, etc. For example, in some embodiments, the temperature at the top / bed of the second reactor is controlled by adjusting the catalyst flow in the regenerator that indirectly controls the catalyst / oil ratio. While the reactor bed can be controlled by manipulating the flow of spent catalyst from the reactor to the regenerator, which controls the WHSV and catalyst residence time.

[0185] Although the present disclosure includes a limited number of embodiments, those skilled in the art who benefit from the present disclosure will understand that other embodiments can be designed without departing from the scope of the present disclosure. Therefore, the scope of protection of this application should be defined only by the appended claims.

Claims

1. A method for hydrocarbon conversion, comprising: feeding a mixture of first particles and second particles from a regenerator to a transport vessel or a riser reactor, wherein the first particles have a smaller average particle size and / or density than the second particles, and wherein the first particles and the second particles are independently catalytic or non-catalytic particles; feeding a reactive and / or non-reactive carrier fluid to the transport vessel or the riser reactor; recovering an overhead product from the transport vessel or the riser reactor, the overhead product comprising the carrier fluid and / or a reaction product of the carrier fluid, the second particles, and the first particles; feeding the overhead product to an integrated separation vessel, the integrated separation vessel comprising: a housing; a solid separation device disposed within the housing for separating the second particles from the overhead product to provide a first stream comprising the first particles and the carrier fluid and / or a reaction product of the carrier fluid, and a second stream comprising the separated second particles; one or more cyclone separators disposed within the housing for separating the first stream to recover a solid fraction comprising the first particles and a vapor fraction comprising the carrier fluid and / or a reaction product of the carrier fluid; an internal container disposed within the housing for receiving the second stream comprising the separated second particles; an annular region between the housing and the internal container for receiving the solid fraction comprising the first particles; a vapor outlet for recovering the vapor fraction; a first solid outlet disposed below the solid separation device and in fluid communication with the annular region; and a second solid outlet disposed below the solid separation device and in fluid communication with the internal container; recovering the solid fraction from the annular region through the first solid outlet; and recovering the separated second particles through the second solid outlet.

2. The method according to claim 1, further comprising feeding the solid fraction comprising the separated first particles from the annular region to the regenerator.

3. The method according to claim 2 further comprises feeding the separated second particles from the internal vessel to the transport vessel or the riser reactor, wherein, The separated second particles are mixed with the mixture of first particles and second particles from the regenerator.

4. The method according to claim 1, further comprising feeding the separated second particles from the internal container to the regenerator.

5. The method according to claim 4, further comprising feeding the solid fraction comprising the separated first particles from the annular region to the transport vessel or riser reactor, wherein, The separated second particles are mixed with the mixture of first particles and second particles from the regenerator.

6. The method according to claim 1, further comprising: feeding the separated second particles from the internal container to a reactor; contacting the separated second particles with a hydrocarbon feedstock to crack the hydrocarbon feedstock.

7. A method for hydrocarbon conversion, comprising: feeding a mixture of first particles and second particles from a regenerator to a riser reactor, wherein the first particles have a smaller average particle size and / or density than the second particles, and wherein the first particles and the second particles are independently catalytic or non-catalytic particles; feeding a hydrocarbon fraction to the riser reactor and contacting the hydrocarbon fraction with the mixture of first particles and second particles to convert at least a portion of the hydrocarbon fraction; Recover an overhead product comprising a converted hydrocarbon fraction, the second particles, and the first particles from the riser reactor; Feed the overhead product to an integrated separation vessel, the integrated separation vessel comprising: A housing; A solid separation device disposed within the housing for separating the second particles from the overhead product to provide a first stream comprising the first particles and a carrier fluid and / or a reaction product of the carrier fluid, and a second stream comprising the separated second particles; One or more cyclone separators disposed within the housing for separating the first stream to recover a solid fraction comprising the first particles and a vapor fraction comprising the carrier fluid and / or a reaction product of the carrier fluid; An internal vessel disposed within the housing for receiving the second stream comprising the separated second particles; An annular region between the housing and the internal vessel for receiving the solid fraction comprising the first particles; and A vapor outlet for recovering the vapor fraction; Feed the solid fraction from the annular region to the regenerator; and Increase the concentration of the second particles within the riser reactor by feeding the separated second particles from the internal vessel to the riser reactor, wherein the separated second particles are mixed with a mixture of the first particles and the second particles from the regenerator.

8. The method according to claim 7, further comprising: Feeding a second hydrocarbon feedstock and a mixture of the first particles and the second particles to a second reactor; Contacting the mixture of the first particles and the second particles with the second hydrocarbon feedstock to crack the second hydrocarbon feedstock and form a second reactor effluent comprising lighter hydrocarbons and a mixture of the first particles and the second particles; Feeding the second reactor effluent to a separator to separate the first particles and the second particles from the lighter hydrocarbons and the converted hydrocarbon effluent; and Recovering a hydrocarbon product from the separator.

9. The method according to claim 8, further comprising: Feeding fresh second particles to the riser reactor; And Feeding fresh first particles to the regenerator.

10. The method according to claim 8, further comprising: Feeding the vapor fraction recovered through the vapor outlet and the hydrocarbon product recovered from the separator to a fractionation system for separating the hydrocarbon product therein into two or more hydrocarbon fractions including a naphtha fraction; and Feeding the naphtha fraction as a hydrocarbon feedstock to the riser reactor.

11. The method according to claim 7, further comprising adjusting a vapor split ratio in the solid separation device to carry a portion of the second catalyst in the first stream.

12. A system for cracking hydrocarbons, comprising: A regenerator; A riser reactor configured to: Receive a mixture of first particles and second particles from the regenerator, wherein the first particles have a smaller average particle size and / or density than the second particles, and wherein the first particles and the second particles are independently catalytic or non-catalytic particles; Contact a hydrocarbon fraction with the mixture of the first particles and the second particles to convert at least a portion of the hydrocarbon fraction; and Produce an overhead product comprising the converted hydrocarbon fraction, the second particles, and the first particles from the riser reactor; An integrated disengaging vessel configured to receive the overhead product, the integrated disengaging vessel comprising: A housing; A solid separation device disposed within the housing for separating the second particles from the overhead product to provide a first stream comprising the first particles and the carrier fluid and / or the reaction product of the carrier fluid, and a second stream comprising the separated second particles; One or more cyclone separators disposed within the housing for separating the first stream to recover a solid fraction comprising the first particles and a vapor fraction comprising the carrier fluid and / or the reaction product of the carrier fluid; An internal vessel disposed within the housing for receiving the second stream comprising the separated second particles; An annular region between the housing and the internal vessel for receiving the solid fraction comprising the first particles; and A vapor outlet for recovering the vapor fraction; A flow line for feeding the solid fraction from the annular region to the regenerator; and A flow line for increasing the concentration of the second particles in the riser reactor by feeding the separated second particles from the internal vessel to the riser reactor, wherein the separated second particles are mixed with the mixture of the first particles and the second particles from the regenerator.

13. The system according to claim 12, further comprising: A second reactor configured to receive a second hydrocarbon feedstock and a mixture of the first particles and the second particles from the regenerator, wherein the mixture of the first particles and the second particles contacts the second hydrocarbon feedstock to crack the second hydrocarbon feedstock and form a second reactor effluent, the second reactor effluent comprising lighter hydrocarbons and a mixture of the first particles and the second particles.

14. The system according to claim 12, further comprising: A flow line for feeding fresh second particles to the riser reactor; And A flow line for feeding fresh first particles to the regenerator.

15. The system according to claim 12, further comprising: A fractionation system configured to receive the vapor fraction recovered through the vapor outlet and the hydrocarbon product recovered from the separator, and for separating the hydrocarbon product therein into two or more hydrocarbon fractions including a naphtha fraction; and A flow line for feeding the naphtha fraction as a hydrocarbon feedstock to the riser reactor.

16. The system according to claim 12, further comprising a controller configured to adjust the vapor split ratio in the solid separation device to carry a portion of the second catalyst in the first stream.

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