Riser separation systems

Abstract

To provide an apparatus for separating a gaseous mixture from a particle stream entering from a riser reactor used for cracking a hydrocarbon feedstock using the particle stream.SOLUTION: A riser reactor 501 defines a longitudinal axis A, includes a riser reactor inlet 502 at one end and at least one riser reactor outlet 504 at an opposite end, and includes a separation vessel 506 including separation chambers 508 and collection chambers 510 alternately distributed about the longitudinal axis. Each separation chamber comprises two vertical lateral walls 512 that are also walls of an adjacent collection chamber, and a lateral separation chamber outlet is defined in at least one of the vertical lateral walls to provide fluid and particle communication from the separation chamber to the adjacent collection chamber. The separation vessel includes a collection chamber deflector 520 positioned within the collection chamber.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] (CROSS-REFERENCE TO RELATED APPLICATIONS) This application claims the benefit of priority to U.S. Patent Application No. 17 / 330,354, filed May 25, 2021, the contents of which are incorporated herein by reference in their entirety.

[0002] FIELD OF THE INVENTION This disclosure relates to any steam particle operation that uses a high velocity dilute phase lift line (or riser reactor), such as a Fluid Catalytic Cracking (FCC) process. [Background technology]

[0003] The FCC process is well established in the petroleum refining industry for converting low-value, high-boiling range petroleum fractions into high-value, low-boiling products, particularly gasoline, propylene and other light olefins.

[0004] In the FCC process, finely divided solid catalyst particles drive the cracking reaction by providing both heat and catalytic activity for the reaction. The finely divided form of the catalyst can be made to behave like a fluid (hence the term fluid catalytic cracking), flowing in a closed cycle between a cracking zone (riser reactor) and a separate regeneration zone connected to a transfer line, commonly referred to as a standpipe or lift line.

[0005] The reaction zone of an FCC unit generally consists of two parts: a riser reactor and a reaction device for rapid separation of catalyst and reaction products, known to those skilled in the art as a Riser Termination Device (RTD). The RTD system is generally located at the outlet of the riser reactor and is housed within the reactor vessel for mechanical considerations, which also contains other devices important to the operation of the process. Once separated from the catalyst, the reaction products are routed away from the vessel, quenched, and split into desired fractions.

[0006] In the riser reactor, a hot catalyst contacts and vaporizes the liquid oil feedstock, driving the desired gas-phase cracking reaction, which forms various hydrocarbon products as well as solid coke deposits on the catalyst. At the end of the riser reactor, rapid separation of the catalyst from the hydrocarbon products is desirable to control the reaction time to avoid over-cracking of the hydrocarbon vapors. Limiting the hydrocarbon conversion time to the riser reactor is desirable because this zone is designed to ensure intimate mixing of the vapors and the solid catalyst. Once the mixture exits the riser reactor, less intimate contact may occur within the containment / separation vessel, and undesirable thermal cracking reactions may occur, leading to the loss of valuable products and the generation of low-value by-products. By containing the hydrocarbon vapors in the RTD and routing them as directly as possible out of the system, residence time at high temperatures, which can lead to thermal degradation, is minimized. Rapid and complete separation of the hydrocarbon vapors from the catalyst is also desirable to terminate the catalytic cracking reaction. To achieve very high catalyst recovery, a two-stage vapor catalyst separation is required; the RTD is considered the primary stage of separation, and the secondary separation stage consists of multiple high-efficiency cyclones. During primary separation, the hydrocarbon vapors are separated from the majority of the catalyst and exit the RTD through a gas outlet pipe directly connected to the secondary separation stage. The separated catalyst flows down another chamber, known as the dipleg, at the lower end of the primary separator and enters the stripping bed. As the catalyst flows down the dipleg, it entrains some hydrocarbon vapors. The catalyst and entrained hydrocarbons exit the RTD and enter the stripping bed. The catalyst flows into the stripping zone where it is further separated. As the catalyst passes through the stripping zone, hydrocarbon vapors between and within the particles are removed by a countercurrent of stripping vapor. The catalyst, free of gaseous hydrocarbons but contaminated with solid hydrocarbon coke, exits the stripping zone and enters the regeneration zone.

[0007] Following primary gas catalyst separation, the catalyst flows into the stripper bed below the RTD, where it is countercurrently contacted with stripping gas to remove any residual volatile hydrocarbons entrained with the catalyst. The hydrocarbon-stripped catalyst, typically referred to as spent catalyst, containing solid coke deposits is sent to a catalyst regeneration zone, where the coke is burned off and catalytic activity is restored. The regeneration process releases energy and raises the catalyst temperature, and after the coke deposits are burned off, the hot regenerated catalyst flows back to the reaction zone. Hydrocarbon vapors separated from the catalyst flow to a downstream distillation system for fractionation into several products. FCC units containing a riser-reactor-regenerator assembly are autothermal equilibrium in that the heat generated by coke combustion in the regenerator matches the heat required for feed vaporization and the cracking reactions.

[0008] Prior art riser separation systems typically have two separation chambers with associated diplegs and a series of gas collection chambers for separating gas and catalyst material, respectively. U.S. Patent No. 6,296,812 to Gauthier et al. provides an apparatus for separating a mixture of gas and particles, having an envelope containing a separation chamber and a circulation (e.g., gas collection) chamber associated with the riser separation system. The upper portion of each separation chamber has an inlet opening communicating with the riser reactor, a middle zone for rotating the mixture in a vertical plane, and a lower zone known as a dipleg for collecting separated catalyst particles. Each separation chamber has two side walls that also serve as walls for the circulation chamber, and at least one of the walls of each chamber has a side outlet opening for mixing the gas and particles into the adjacent circulation chamber. The gas collection chamber has two additional openings, one at the top connected to a gas outlet pipe, which is further connected to a secondary separator, and a lower opening communicating with the so-called dilute phase of the reactor vessel above the lower stripper bed. The application of this device is the fluid catalytic cracking of hydrocarbons in a riser, but it can be applied to other similar processes as well.

[0009] The device of Gauthier et al. has multiple separation and circulation chambers, each with its own dipleg containing a particle outlet opening that connects to the stripper bed below the separation chamber. In the device of Gauthier et al., the riser vapor and catalyst mixture is forced to change direction before entering the separation chamber through a window at the top of the riser, making a quarter turn before separating from each other. The vapor then makes another 180° turn under the deflector of the separation chamber before entering the collection chamber. The catalyst flows down the separation chamber into a dipleg designed for low mass flux to maximize gas separation. This device is primarily used as a primary separation device for catalyst and vapor for an internal riser system housed within a reactor / stripper vessel. Stripping gas and hydrocarbon vapor are entrained into the reactor from the separation chamber dipleg, enter the collection chamber through a lower conduit, mix with the riser vapor from the separation chamber before entering the gas outlet pipe / collector, and then flow into a cyclone secondary separator for final gas / catalyst separation. While the Gauthier device addresses the separation and transport objectives, solids collection rates are lower than expected. The inlet to the separation chamber has a severe 90° turn from the top of the riser, providing only a quarter turn for the gas and catalyst to separate, which is not sufficient to cleanly separate the gas and catalyst from each other. The severe 90° change in direction creates turbulent catalyst flow conditions at the inlet, and the subsequent quarter turn does not allow enough time for the flow structure necessary to develop to achieve good separation of the cracked gas from the solid catalyst particles. There is no connection between the separation chambers, creating the potential for uneven pressure distribution and resulting stress on each chamber. This results in uneven loading and therefore low separation efficiency.

[0010] Another type of riser separation system, for example, U.S. Patent No. 10,731,086 to Marchant et al., includes an RTD design with additional features within the separation chamber that provide improved gas-solid separation and gas containment. These features include a contoured riser top to provide a smooth 180° turn for the gas catalyst flow and a single (common) dipleg for the separation chamber to minimize flow disturbances at the riser top and promote gas catalyst separation. Marchant et al. also provides a more compact design that reduces overall volume and post-riser residence time, and the balanced flow distribution to each separation window improves operational stability. Marchant et al. also describes disk- or donut-shaped baffles on the catalyst bed within the separation chamber dipleg to deflect the momentum of separated catalyst particles and reduce re-entrainment of separated catalyst.

[0011] Another type of riser separation system, such as U.S. Patent No. 4,664,888 to Leonce F. Castagnos, includes a deflection device. Castagnos's patent describes a rough-cut catalyst vapor separator for a fluidized catalytic cracking riser, located at the riser outlet and forcing the oil-catalyst mixture to make a 180° downward turn. The separator is equivalent to a semi-turn inside the cyclone, moving most of the catalyst to the wall. Most of the hydrocarbon vapor is squeezed out from the wall. At the end of the separator is a scraping scoop positioned to separate the primarily catalyst phase from the primarily hydrocarbon vapor phase. The scraping scoop directs the catalyst phase away from the center of the vessel, depositing it near the vessel wall, where it continues its downward flow under the influence of gravity. The vapor phase continues its downward flow for a period of time, after which it must undergo a 180° turn and flow upward to exit the vessel through a series of conventional cyclone separators. However, a second 180° turn of the oil vapor can re-entrain the separated catalyst, which negates the initial gas-solids separation.

[0012] Castagnos also discloses an open, semi-dornut-shaped deflection device in which the gas / catalyst mixture exiting the riser impinges on the surface of a deflector, where the catalyst particles are compressed against it, and the separated gas phase enters an open area below the edge of the deflector. As the gas separates from the particle phase, the solids tend to decelerate, and the effects of gravity counteract the initial separation achieved. Any remaining compressed particle phase flows onto a collection surface, and the particles then flow down and away from the surface toward the vessel wall. The separated gas is believed to flow upward through the conduit without re-contacting the particle phase. Thus, the pressure below the impingement and collection surfaces is higher than the pressure above them. This pressure difference forces the gas not only through the conduit but also through the open area below the edge of the deflector and the collection surface, further counteracting the separation already achieved. The separated gas then enters the vessel, where it experiences a significant residence time and undergoes significant post-riser cracking, making it "uncontained."

[0013] The prior art has been considered satisfactory for its intended purposes. However, there is a need for an apparatus that improves separation of the catalyst and vapor phases at the riser reactor outlet. The present disclosure provides a solution to this need. The inventors have discovered a method and means for achieving improved catalyst and vapor phase separation, as well as improved gas collection efficiency, by utilizing a riser separation system having a novel design that provides improved flow profiles that promote gas-solids separation and improve operational stability. Summary of the Invention

[0014] An apparatus for separating a gaseous mixture from a particulate stream entering from a riser reactor used to crack a hydrocarbon feedstock with the particulate stream includes a reactor vessel having a lower stripping bed region and an upper secondary separator region. The apparatus includes a riser reactor within the reactor vessel. The riser reactor defines a longitudinal axis and receives the hydrocarbon feedstock and the particulate stream at one end. The apparatus includes a riser reactor inlet for discharging the cracked gas and solid particle mixture at an opposite end, and at least one riser reactor outlet for discharging the cracked gas and solid particle mixture at an opposite end. The apparatus includes a separation vessel defined proximate to the at least one riser reactor outlet. The separation vessel includes at least one separation chamber and at least one collection chamber alternately distributed about a longitudinal axis. Each separation chamber includes two vertical side walls that also include walls of an adjacent one of the at least one collection chamber. The at least one separation chamber includes a separation chamber inlet in an upper region thereof that communicates with the riser reactor. A side separation chamber outlet is defined in at least one of the vertical side walls to provide fluid and particle communication from the side separation chamber to an adjacent one of the at least one collection chamber. The separation vessel includes at least one collection chamber deflector positioned within the at least one collection chamber.

[0015] In some embodiments, the at least one separation chamber includes two separation chambers. One of the at least one collection chambers is positioned between the two separation chambers. The at least one collection chamber deflector extends between one of two vertical side walls of a first of the two separation chambers and one of two vertical side walls of a second of the two separation chambers. Each collection chamber may include a collection chamber outer wall including a stripping gas inlet window that allows stripping gas from at least one stripping gas injector adjacent to the lower stripping bed region to enter the collection chamber. Each collection chamber may include a collection chamber floor that defines the collection chamber together with the collection chamber outer wall, the vertical side wall, and the riser reactor. The collection chamber deflector may include a concave surface facing the collection chamber floor. The collection chamber deflector may include a downward-facing pointed portion. The pointed portion may be centered between two of the vertical side walls.

[0016] In some embodiments, the chamber deflector can include a dividing baffle extending from the concave surface of the collection chamber deflector. The dividing baffle can extend beyond the lower edge of the deflector in a direction parallel to the longitudinal axis. The apparatus includes at least one collection chamber conduit in an upper region of the collection chamber for discharging the cracked gas and a small portion of the solid particles from the collection chamber to a gas outlet collector. The at least one collection chamber conduit can extend downward through the collection chamber deflector. Each collection chamber can include a collection chamber outer wall extending from the side separation chamber outlet into the lower stripping bed region. Each collection chamber can include a collection chamber floor. The collection chamber floor, the collection chamber outer wall, the vertical side walls, and the riser reactor can together define the collection chamber. The collection chamber outer wall can be a common collection chamber outer wall extending in a continuous circumferential direction around the riser reactor toward the lower stripping bed. The collection chamber outer wall may include a sloped portion toward the riser reactor and a vertical wall below the sloped portion.

[0017] In some embodiments, each separation chamber may further include a separation chamber outer wall extending from the separation chamber inlet toward the lower stripping bed region. The separation chamber outer wall and the collection chamber outer wall may terminate at the same vertical position relative to the longitudinal axis. The collection chamber outer wall may have a diameter equal to or less than the diameter of the separation chamber outer wall. At least one of the at least one separation chamber may include a separation chamber deflector positioned at least partially above the side separation chamber outlet. The at least one separation chamber deflector is positioned at least partially above the side separation chamber outlet.

[0018] According to another aspect, an apparatus for separating a gaseous mixture from a particulate stream entering from a riser reactor used for cracking a hydrocarbon feedstock in the particulate stream is provided, the apparatus comprising: a lower stripping bed region; and an upper secondary separator region. The apparatus includes a riser reactor within the reactor vessel. The riser reactor defines a longitudinal axis and includes a central riser reactor inlet at one end for receiving the hydrocarbon feedstock and particle stream and at least one riser reactor outlet at an opposite end for discharging a mixture of cracked gas and solid particles. The apparatus includes a separation vessel defined adjacent to the at least one riser reactor outlet. The separation vessel includes at least one separation chamber and at least one collection chamber alternately distributed about the longitudinal axis. Each separation chamber includes two vertical side walls that also include an adjacent collection chamber wall. The separation chamber includes a separation chamber inlet at an upper region of the separation chamber that communicates with the riser reactor. A side separation chamber outlet is defined in at least one of the vertical side walls to provide fluid and particle communication from the separation chamber to an adjacent one of the at least one collection chamber. Each collection chamber includes a collection chamber outer wall that extends from the side separation chamber outlet into the lower stripping bed region.

[0019] In some embodiments, the collection chamber outer wall is a common collection chamber outer wall that extends in a continuous circumferential direction around the riser reactor toward the lower stripping bed. The collection chamber outer wall can be similar to those described above.

[0020] In some embodiments, the apparatus may include at least one collection chamber deflector positioned within the adjacent gas collection chamber at least partially above the side separation chamber outlet. The at least one collection chamber deflector may include a concave surface facing the lower stripping bed region. The at least one collection chamber deflector may be positioned at least partially above the side separation chamber outlet. The at least one separation chamber may be two separation chambers. One of the at least one collection chambers may be positioned between the two separation chambers. The at least one collection chamber deflector may extend between one of two vertical side walls of a first of the two separation chambers and one of two vertical side walls of a second of the two separation chambers. The at least one collection chamber deflector may be the same as that described above. The collection chamber deflector may include a dividing baffle similar to that described above. The apparatus may include at least one collection chamber conduit similar to the collection chamber conduit described above. At least one of the at least one separation chambers can include a separation chamber deflector positioned at least partially above the lateral separation chamber outlet. The separation chamber deflector can be integrally formed with the collection chamber deflector.

[0021] These and other features of the systems and methods of the present disclosure will become more readily apparent to those skilled in the art from the following detailed description of the preferred embodiments taken in conjunction with the drawings. [Brief explanation of the drawings]

[0022] Preferred embodiments of the present disclosure are described in detail herein below with reference to certain figures so that those skilled in the art to which the present disclosure pertains will readily understand, without undue experimentation, how to make and use the devices and methods of the present disclosure. [Figure 1]FIG. 1 is a schematic perspective view of an apparatus for separating a gaseous mixture from a particulate stream entering from a riser reactor used to crack a hydrocarbon feedstock, constructed in accordance with the present disclosure, showing a separation vessel with alternating separation and collection chambers. [Figure 2A] FIG. 2 is a schematic cross-sectional side view of the device of FIG. 1, showing two separation chambers spaced 90° apart. [Figure 2B] FIG. 2 is a schematic cross-sectional side view of the apparatus of FIG. 1 showing two collection chambers each having a collection chamber deflector such that gas from the separation chamber must turn 180° below the separation chamber before exiting through the outlet tube. [Figure 3A] FIG. 1 is a schematic cross-sectional side view of another embodiment of an apparatus for separating a gaseous mixture from a particle stream entering from a riser reactor used to crack a hydrocarbon feedstock, constructed in accordance with the present disclosure, showing two separation chambers 90° apart, each including a riser with a concave deflector at the riser outlet to provide a smooth 180° turn for gas and catalyst particles exiting the riser reactor and entering an RTD. [Figure 3B] FIG. 3B is a schematic cross-sectional side view of the embodiment of FIG. 3A showing two collection chambers each having a collection chamber deflector, from which gas must turn 180° under the separation chamber before exiting through the outlet tube. [Figure 4A] FIG. 1 is a schematic cross-sectional side view of another embodiment of an apparatus for separating a gaseous mixture from a particle stream entering a riser reactor used to crack a hydrocarbon feedstock, constructed in accordance with the present disclosure, showing two separation chambers 90° apart, each including a riser with a concave surface deflector at the riser outlet to provide a smooth 180° turn for gas and catalyst particles exiting the riser reactor and entering an RTD, and showing a common separation chamber outer wall, e.g., a separation chamber dipleg, terminating in a stripping catalyst bed. [Figure 4B]FIG. 4B is a schematic cross-sectional side view of the embodiment of FIG. 4A showing two collection chambers, each having a collection chamber deflector where gas from the separation chamber must turn 180° before exiting through the outlet pipe, and showing the collection chambers having a common collection chamber outer wall, e.g., a collection chamber dipleg, that terminates in a stripping catalyst bed, the collection chamber dipleg surrounding the separation chamber dipleg. [Figure 5] FIG. 1 is a schematic perspective cutaway view of an apparatus for separating a gaseous mixture from a particulate stream entering from a riser reactor used to crack a hydrocarbon feedstock constructed in accordance with the present disclosure, showing a separation vessel with alternating separation and collection chambers, one of the collection chamber outer walls shown semi-transparent and one of the separation chamber outer walls shown partially cut away. [Figure 6] 6 is a schematic perspective view of the apparatus of FIG. 5, showing a collection chamber deflector extending from the separation chamber deflector and a dividing baffle positioned below the collection chamber deflector. [Figure 7] FIG. 6 is a schematic top view of the apparatus of FIG. 5, showing the flow of fluid / particles from the riser reactor to the separation chamber and then to the collection chamber. [Figure 8] FIG. 1 is a schematic perspective view of another embodiment of an apparatus for separating a gaseous mixture from a particulate stream entering from a riser reactor used to crack a hydrocarbon feed, constructed in accordance with the present disclosure, showing a collection chamber deflector having a central cusp. [Figure 9] FIG. 1 is a schematic perspective view of another embodiment of an apparatus for separating a gaseous mixture from a particulate stream entering from a central riser reactor used to crack a hydrocarbon feed, constructed in accordance with the present disclosure, showing a conduit passing through the collection chamber underflow baffle as a means of transporting gas directly to a gas outlet tube. [Figure 10] FIG. 1 is a schematic cross-sectional side view of another embodiment of an apparatus for separating a gaseous mixture from a particulate stream entering from a riser reactor used to crack a hydrocarbon feedstock, constructed in accordance with the present disclosure, showing a collection chamber outer wall including a stripping gas inlet conduit and a vent pipe. DETAILED DESCRIPTION OF THE INVENTION

[0023] Referring now to the drawings, where like reference numbers identify like structural features or aspects of the present disclosure. For purposes of explanation and illustration, and not limitation, a partial view of an embodiment of an apparatus for separating a gaseous mixture from a particulate stream entering from a central riser reactor according to the present disclosure is shown in FIG. 1 and generally designated by reference numeral 500. Other embodiments of systems according to the present disclosure or aspects of the present disclosure are provided in FIGS. 2-11 as described. The systems and methods described herein can provide a separation vessel, e.g., an RTD, where the gas collection chamber is modified by creating a dipleg that extends into the catalyst bed, and / or the gas collection chamber includes a deflector baffle.

[0024] As shown in FIGS. 1-2B , an apparatus 500 for separating a gaseous mixture from a particle stream entering a central riser reactor 501 used to crack a hydrocarbon feedstock using the particle stream includes a reactor vessel 534 with a lower stripping bed region 10 and an upper secondary separator region 12. The riser reactor 501 is centrally positioned within the reactor vessel 534. The riser reactor 501 defines a longitudinal axis A and includes a riser reactor inlet 502 at one end for receiving the hydrocarbon feed and particle stream (schematically indicated by arrows, e.g., flow arrow 591) and at least one riser reactor outlet 504 at an opposite end for discharging a mixture of cracked gas and solid particles to a separation chamber 508. The apparatus 500 includes a separation vessel 506 defined adjacent the riser reactor outlet 504. The separation vessel 506 includes alternating separation chambers 508 and collection chambers 510 distributed about the longitudinal axis A. The apparatus 500 includes a plurality of separation chamber outer walls 519 (shown semi-transparently in FIG. 1 ), each extending from a respective separation chamber inlet 514 in the upper region 516 of a separation chamber 508 into the lower stripping bed region 10. Each separation chamber 508 includes its own separation chamber outer wall 519 (shown semi-transparently in FIG. 1 ). The apparatus 500 includes a collection chamber outer wall 524 (shown semi-transparently in FIG. 1 ) of each collection chamber 510, which extends from a lateral separation chamber outlet 518 toward and into the lower stripping bed region 10. The walls 524 and 519, which form the separation chamber dipleg region 509 and the collection chamber dipleg region 531, respectively, are recessed into the lower stripping bed region 10.

[0025] 1-2B , each collection chamber outer wall 524 includes a sloped portion 528 converging toward the riser reactor 501 and a substantially vertical wall portion 530, e.g., a dipleg, below the sloped portion 528. Each vertical wall portion 530 forms a separate dipleg region 531 for each collection chamber 510. The substantially vertical wall portion 530 of the collection chamber outer wall 524 terminates in the lower stripping bed region 10. The vertical wall portions 530 of each separation chamber outer wall 519 and the collection chamber outer wall 524 terminate at the same vertical position relative to the longitudinal axis A. The collection chamber outer wall 524 has a diameter that is the same as or smaller than the separation chamber outer wall 519. Because the vertical wall portion 530 of the collection chamber outer wall 524 dips into the lower stripping bed region 10, the apparatus 500 includes an open slip unit vent 548 to provide a flow path for stripping gas and entrained hydrocarbons to escape from the reactor to a gas outlet pipe 546 and on to the second-stage separator. The dipleg (e.g., the vertical wall portion of the collection chamber outer wall 524 and separation chamber outer wall 519 that extends into the catalyst bed) ensures that all hydrocarbons are contained within the RTD and that hydrocarbon vapors do not leak into the reactor, which results in maximum gas containment and potentially eliminates reactor coking.

[0026] 2A and 2B, each separation chamber 508 includes two substantially vertical side walls 512 that also include walls of the adjacent collection chamber 510. The separation chambers 508 (two of which are shown in FIG. 2A) include a separation chamber inlet 514 at an upper region 516 of the separation chamber 508 that communicates with the riser reactor 501. Gas / particles (schematically represented by flow arrows 591) from the riser 501 first turn 90° from the riser reactor 501 (e.g., 90° from axis A) and then turn another 90° about the separation chamber deflector 527. The gas and entrained catalyst (schematically represented by flow arrows 591a) then turn another 180° below the separation chamber deflector 527, while the catalyst particles (schematically represented by flow region 591b) separate from the gas and fall into the catalyst bed 10. The apparatus 500 includes a side separation chamber outlet 518 defined in each of the vertical side walls 512 to provide fluid and particle communication from the side separation chamber 508 to the adjacent collection chamber 510. The apparatus 500 includes at least one collection chamber deflector 520 positioned at least partially within the gas collection chamber 510 above the side separation chamber outlet 518. Each collection chamber deflector 520 extends between two of the vertical side walls 512 (similar to deflector 120 in FIG. 4). The collection chamber deflectors 520 further increase gas catalyst separation and act to ensure that riser hydrocarbon vapors and entrained catalyst do not have a direct path to the RTD outlet 525 toward the gas outlet tube. A gas collection chamber dipleg 530 submerged in the stripping catalyst bed 10 ensures that riser hydrocarbon vapors cannot escape through the gas collection chamber outlet 523, which is open to the reactor. The collection chamber dipleg 530 also ensures that fines returning from the cyclone dipleg 515 cannot be re-entrained directly through the gas collection chamber outlet 525 .

[0027] As shown in FIGS. 2A and 2B, the collection chamber deflector 520 acts to add another separation stage within each gas collection chamber 510. Current RTDs allow the gas-solids stream to flow directly from the separation chamber outlet 518 to the main outlet duct connecting the RTD to the cyclone inlet. In an embodiment of the present disclosure, the deflector 520, similar to the deflector 527 used in the separation chamber 508, further redirects the gas entering from the side separation chamber outlet 518 by 180°, as shown schematically by flow arrow 537. The difference in momentum between the gas and catalyst results in further separation and lower loading on the cyclone. This tends to improve the separation efficiency of the overall system. In the embodiment of FIGS. 2A and 2B, the collection chamber deflector 520 and the deflector 527 terminate at the same vertical position. The concave surface 526 of the deflector 520 faces the stripping bed 10.

[0028] 3A and 3B, another embodiment of an apparatus 600 for separating a gaseous mixture from a particle stream entering from a central riser reactor 601 is shown. Separation chambers 608 (two of which are shown in FIG. 3A) each include a separation chamber inlet 614 in an upper region 616 of the separation chamber 608 that communicates with the riser reactor 601. Gas / particles (schematically represented by flow arrows 691) from the riser 601 first turn 90° from the riser reactor 601, then turn another 90° about a separation chamber deflector 627, and the gas and entrained catalyst (schematically represented by flow arrows 691a) turn another 180° below the separation chamber deflector 627, while the catalyst particles (schematically represented by flow arrows 691b) separate from the gas and fall into the catalyst bed 10. Apparatus 600 is similar to apparatus 500, except that the collection chamber outer wall 624 of each collection chamber 610 extends from the lateral separation chamber outlet 618 toward and into the lower stripping bed region 10. Because the collection chamber outer wall 624 dips into the lower stripping bed region 10, apparatus 600 includes an open slip unit vent 648 to provide a flow path for stripping gas and entrained hydrocarbons to escape from the reactor to a gas outlet pipe 646. Apparatus 600 differs from apparatus 500 in that the riser 601 includes a parabolic concave cone-shaped deflector 653 at the riser outlet 604, where the apex of the deflector 653 faces downward toward the riser inlet 602. Apparatus 600 also includes a baffle 607 within the separation chamber 608. The baffle 607 may be, for example, an annular section positioned about the riser reactor 601.

[0029] 4A and 4B, another embodiment of an apparatus 700 for separating a gaseous mixture from a particulate stream entering from a central riser reactor 701 is shown. The apparatus 700 is similar to the apparatus 600, except that the collection chamber outer wall 724 includes a sloped portion 728 that converges toward the riser reactor 701 and a substantially vertical cylindrical wall portion 730 that forms a common dipleg region 731 below the sloped portion 728. The substantially vertical cylindrical wall portion 730, or skirt, below the sloped portion 728 is a continuous cylinder that forms the annular common dipleg region 731 around the riser reactor 701, such that the stripping gas outlet windows 750 of each collection chamber 710 are all in fluid communication with the common dipleg region 731. The substantially vertical wall portion 730 extends into and toward the lower stripping bed region 10. Gas / particles (schematically represented by flow arrows 791) from riser 701 make an initial 90° turn out of riser reactor 701, followed by another 90° turn around separation chamber deflector 727, and the gas and entrained catalyst (schematically represented by flow arrows 791a) make another 180° turn below separation chamber deflector 727, while catalyst particles (schematically represented by flow arrows 791b) separate from the gas and fall into catalyst bed 10. Apparatus 700 is similar to apparatus 100, except that instead of outer wall 724 stopping above each exit window 750, a single cylindrical wall 730 begins at the lower edge of each sloped portion 728 and extends downward into the catalyst bed, as does outer wall 124 and equivalent sloped portions of outer wall 124 that stop above each exit window 150, as described below.

[0030] 4A and 4B , the apparatus 700 includes a separation chamber outer wall 719 extending therein from a lateral separation chamber outlet 718 toward the lower stripping bed region 10. The separation chamber outer wall 719 is common to each separation chamber 708 such that the separation chamber dipleg region 709 extends continuously circumferentially about the longitudinal axis A. The collection chamber outer wall 724 is concentric with the separation chamber outer wall 719. A substantially vertical wall 730 has a diameter D1 that is greater than the diameter D2 of the lower portion 719a of the separation chamber outer wall 719 that defines the separation chamber dipleg region 709. The apparatus 700 includes an open slip unit vent 748 to provide a flow path for stripping gas and vapor from the reactor to escape to a gas outlet pipe 746, where the collection chamber 710 is bounded at the bottom by the vertical wall 730.

[0031] As shown in Figures 5-7, an apparatus 100 for separating a gaseous mixture from a particulate stream entering a central riser reactor 101 used to crack a hydrocarbon feedstock using the particulate stream includes a reactor vessel 134 including a lower stripping bed region 10 and an upper secondary separator region 12. The riser reactor 101 is positioned within the reactor vessel 134. The riser reactor 101 defines a longitudinal axis A and includes a riser reactor inlet 102 at one end for receiving the hydrocarbon feed and the particulate stream and at least one riser reactor outlet 104 at an opposite end for discharging a mixture of cracked gas and solid particles. The apparatus 100 includes a separation vessel 106 defined adjacent the riser reactor outlet 104. The separation vessel 106 includes alternating separation chambers 108 and collection chambers 110 distributed about the longitudinal axis A.

[0032] 5-7 , each separation chamber 108 includes two substantially vertical side walls 112 that also include walls of the adjacent collection chamber 110. The separation chamber 108 includes a separation chamber inlet 114 at an upper region 116 of the separation chamber 108 that communicates with the riser reactor 101. Each separation chamber 108 includes a separation chamber outer wall 119 that extends downwardly into the catalyst bed 10. The separation chamber outer wall 119 includes a vertically extending skirt 173 that forms a common dipleg region 109 for each of the separation chambers 108. The common dipleg region 109 is in fluid communication with each of the separation chambers 108. The separation chamber dipleg region 109 extends continuously circumferentially about the longitudinal axis A. A lateral separation chamber outlet 118 is defined in each of the vertical side walls 112 to provide fluid and particle communication from the side separation chamber 108 to the adjacent collection chamber 110. The apparatus 100 includes at least one collection chamber deflector 120 positioned at least partially within the gas collection chamber 110 above the side separation chamber outlets 118. Each collection chamber deflector 120 extends between two of the vertical side walls 112. The collection chamber deflectors 120 further increase gas catalyst separation and act to ensure that there is no direct path for riser hydrocarbon vapors to reach the gas collection chamber outlet 125.

[0033] As shown in FIG. 6 , the collection chamber deflectors 120 act to add another stage of separation within each gas collection chamber 110. The separation chamber includes deflector “curved plates” 27, generally referred to as separation chamber deflectors 27. Side separation chamber outlets 118 are located below the separation chamber deflectors 27, one at each end, and connect to the gas collection chamber 110. The separation chamber deflectors 27 and the collection chamber deflectors 120 are connected to each other, integrally formed, or the like, so that the deflectors 27 and the collection chamber deflectors 120 form a ring around the riser 101. This extension of the separation chamber deflector 27 into the collection chamber 110 as the collection chamber deflector 120 allows the gas and catalyst particles to undergo an additional redirection within the gas collection chamber, promoting gas particle separation. Current RTDs have the potential for the gas-solids stream to flow directly from the separation chamber outlets 118 to the main outlet duct connecting the RTD to the cyclone inlet. In the embodiment of the present disclosure, the deflector 120, similar to the separation chamber deflector 27 used in the separation chamber 108, forces the gas entering from the lateral separation chamber outlet 118 to turn an additional 180°, i.e., redirect the flow, as shown schematically by the flow arrow 137. The difference in momentum between the gas and the catalyst results in further separation and lower loading on the cyclone. This tends to improve the overall separation efficiency of the system. The chamber deflector 120 can include a dividing baffle 136 extending from the concave surface 126 for the collection chamber deflector. In the embodiment of FIGS. 5-7, the dividing baffle 136 does not extend beyond the lower edge 138 of the deflector 120 in a direction parallel to the longitudinal axis A. Those skilled in the art will readily appreciate that the baffle 136 can also extend to a vertical position below the lower edge 138.

[0034] 5-7 , the embodiment of apparatus 100 differs from the embodiment of apparatus 700 in that, instead of extending downward into catalyst bed 10, collection chamber outer wall 124, like outer wall 724 and its cylindrical wall 730 extending therefrom, stops in front of catalyst bed 10. The forward-facing collection chamber outer wall 124 in FIG. 5 is shown translucent so that deflector 120 can be easily seen. In apparatus 100, each collection chamber 110 includes collection chamber outer wall 124, vertical side walls 112, and a collection chamber floor 122 that, together with central riser reactor 101, define collection chamber 110. A stripping gas exit window 150, e.g., a collection chamber window, is provided between the collection chamber outer wall 124 and the chamber floor 122 to allow stripping gas and entrained hydrocarbons to exit the reactor stripper section into the gas collection chamber 110 and then to the chamber outlet 125. The concave surface 126 of the deflector 120 faces the collection chamber floor 122. Although the collection chamber deflector 120 is shown with an extended wall 142 (compared to the separation chamber deflector 27 in the separation chamber 108), one skilled in the art will readily appreciate that various lengths for the wall 142 can be used.

[0035] As shown in Figure 8, another embodiment of an apparatus 200 for separating a gaseous mixture from a particulate stream entering from a central riser reactor 201 is shown. The apparatus 200 is the same as the apparatus 100, except that, as shown, the apparatus 200 includes another embodiment of a collection chamber deflector 220. The collection chamber deflector 220 is the same as the collection chamber deflector 120, except that instead of being open or including a dividing baffle, the collection chamber deflector 220 includes a downwardly pointed portion 221 at the intersection of two deflector portions 220a and 220b. The pointed portion 221 is centrally located between two of the vertical side walls 212. Each deflector portion 220a and 220b is generally indicated by a flow arrow 242 in Figure 8. 136. The downwardly sloping shape of each deflector portion 220a and 220b may obviate the need for a divider, such as divider 136.

[0036] Referring now to FIG. 9, another embodiment of an apparatus 800 for separating a gaseous mixture from a particle stream entering from a central riser reactor 801 is shown. The apparatus 800 is similar to the apparatus 100, except that the apparatus 800 includes a collection chamber conduit 844 in an upper region 843 of each collection chamber 810 for discharging the cracked gas and a small portion of the solid particles from the collection chamber 810 to a gas outlet pipe (shown in FIG. 4 as 146). Each collection chamber conduit 844 extends downwardly through a collection chamber deflector 820 similar to the collection chamber deflector 120. The collection chamber outer wall 824 and the separation chamber outer wall 819 are shown partially removed to show the interiors of the collection chamber 810 and the separation chamber 808. The collection chamber 810 is similar to the collection chamber 110 of FIG. 5. Each collection chamber includes a respective stripping gas outlet window 850, similar to the stripping gas outlet window 150. Separation chamber 808 includes a common dipleg region similar to common dipleg region 109 .

[0037] 10 , another embodiment of an apparatus 400 for separating a gaseous mixture from a particulate stream entering from a central riser reactor 401 is shown. The apparatus 400 is generally similar to the apparatus 500. The apparatus 400 includes a plurality of separation chambers 408 and collection chambers 410. A collection chamber outer wall 424 of each collection chamber 410 extends from a side separation chamber outlet 418 toward and submerges into the lower stripping bed region 10, e.g., the catalyst bed. The apparatus 400 includes a stripping gas conduit 417 configured and adapted to provide an additional flow path through the outer wall 424 for a stripper gas to exit the reactor apparatus 400 via a gas outlet pipe 446 to one or more cyclones.

[0038] The method and system of the present disclosure, as described above and shown in the drawings, achieves increased gas-catalyst separation by utilizing a gas collection chamber to further separate the gas from the catalyst. While the apparatus and method of the present disclosure have been shown and described with reference to preferred embodiments, it will be readily apparent to those skilled in the art that changes and / or modifications may be made therein without departing from the scope of the present disclosure.

Claims

1. 1. An apparatus for separating a gaseous mixture from a particulate stream entering from a riser reactor used for cracking a hydrocarbon feedstock using said particulate stream, said apparatus comprising: a reactor vessel comprising a lower stripping bed region and an upper secondary separator region; a riser reactor within the reactor vessel, the riser reactor defining a longitudinal axis and including a riser reactor inlet at one end for receiving the hydrocarbon feedstock and the particle stream, and at least one riser reactor outlet at an opposite end for discharging a mixture of cracked gas and solid particles; a separation vessel defined adjacent to the at least one riser reactor outlet, the separation vessel comprising: at least one separation chamber and at least one collection chamber alternately distributed around the longitudinal axis, each separation chamber comprising two vertical side walls that also comprise walls of an adjacent one of the at least one collection chamber, the at least one separation chamber including a separation chamber inlet in an upper region thereof that communicates with the riser reactor, and a side separation chamber outlet defined in at least one of the vertical side walls to provide fluid and particle communication from the side separation chamber to the adjacent one of the at least one collection chamber; at least one collection chamber deflector positioned within the at least one collection chamber.

2. 2. The apparatus of claim 1, wherein the at least one separation chamber includes two separation chambers with one of the at least one collection chamber therebetween, and the at least one collection chamber deflector extends between one of the two vertical side walls of a first of the two separation chambers and one of the two vertical side walls of a second of the two separation chambers.

3. 10. The apparatus of claim 1, wherein each collection chamber comprises a collection chamber outer wall including a stripping gas inlet window that allows stripping gas from at least one stripping gas injector adjacent the lower stripping bed region to enter the collection chamber.

4. 4. The apparatus of claim 3, wherein each collection chamber comprises a collection chamber floor that together with the collection chamber outer walls, the vertical side walls, and a central riser reactor define the collection chamber.

5. The apparatus of claim 4 , wherein the at least one collection chamber deflector includes a concave surface facing the collection chamber floor.

6. The device of claim 1 , wherein the at least one collection chamber deflector includes a downwardly pointed point.

7. 7. The device of claim 6, wherein the pointed portion is centered between two of the vertical side walls.

8. The apparatus of claim 1 , wherein the collection chamber deflector includes a dividing baffle extending from a concave surface of the collection chamber deflector.

9. The dividing baffle extends beyond the lower edge of the deflector in a direction parallel to the longitudinal axis.

9. The device of claim 8, wherein the

10. 10. The apparatus of claim 1, further comprising at least one collection chamber conduit in an upper region of said collection chamber for discharging said decomposed gas and a minor portion of said solid particles from said collection chamber to a gas outlet collector.

11. The apparatus of claim 10 , wherein the at least one collection chamber conduit extends downwardly through the collection chamber deflector.

12. 10. The apparatus of claim 1, wherein each collection chamber comprises a collection chamber outer wall extending from the side separation chamber outlet into the lower stripping bed region.

13. 13. The apparatus of claim 12, wherein each collection chamber includes a collection chamber floor, and wherein the collection chamber floor, the collection chamber outer wall, the vertical side walls, and a central riser reactor together define the collection chamber.

14. 13. The apparatus of claim 12, wherein each collection chamber outer wall extends to form a single common dipleg extending in a continuous circumferential direction about the riser reactor and into the lower stripping bed.

15. 13. The apparatus of claim 12, wherein each collection chamber outer wall extends to form a respective dipleg that extends into the lower stripping bed.

16. 10. The apparatus of claim 1, wherein each collection chamber is surrounded by a common collection chamber floor, and wherein the collection chamber floor, the collection chamber outer walls, the vertical side walls, and the central riser reactor together define the collection chamber.

17. The apparatus of claim 1 , wherein at least one of the at least one separation chambers further comprises a separation chamber deflector positioned at least partially above the lateral separation chamber outlet.

18. 18. The apparatus of claim 17, wherein the separation chamber deflector is integrally formed with the collection chamber deflector.

19. The apparatus of claim 1 , wherein the at least one collection chamber deflector is positioned at least partially above the lateral separation chamber outlet.

20. The apparatus of claim 1 , wherein the riser reactor comprises a parabolic concave cone-shaped riser deflector at the at least one riser reactor outlet.

21. 1. An apparatus for separating a gaseous mixture from a particulate stream entering from a riser reactor used for cracking a hydrocarbon feedstock using said particulate stream, said apparatus comprising: a reactor vessel comprising a lower stripping bed region and an upper secondary separator region; a riser reactor within the reactor vessel, the riser reactor defining a longitudinal axis and including a riser reactor inlet at one end for receiving the hydrocarbon feedstock and the particle stream, and at least one riser reactor outlet at an opposite end for discharging a mixture of cracked gas and solid particles; a separation vessel defined adjacent the at least one riser reactor outlet, the separation vessel comprising at least one separation chamber and at least one collection chamber alternately distributed about the longitudinal axis, each separation chamber being adjacent to the adjacent collection chamber; a separation vessel having two vertical side walls, each of which also comprises a wall of a riser reactor, the separation chamber including a separation chamber inlet in an upper region of the separation chamber communicating with the riser reactor; a lateral separation chamber outlet defined in at least one of the vertical side walls to provide fluid and particle communication from the separation chamber to an adjacent one of the at least one collection chamber, each collection chamber comprising a collection chamber outer wall extending from the lateral separation chamber outlet into the lower stripping bed region, and each separation chamber further comprising a separation chamber outer wall extending from the separation chamber inlet into the lower stripping bed region.

22. 22. The apparatus of claim 21, wherein the collection chamber outer wall is a common collection chamber outer wall that extends in a continuous circumferential direction about the riser reactor toward the lower stripping bed.

23. 22. The apparatus of claim 21, wherein the collection chamber outer wall includes a sloped portion toward the riser reactor and a vertical wall below the sloped portion.

24. 22. The device of claim 21, wherein the collection chamber outer wall has a diameter equal to or less than the diameter of the separation chamber outer wall.

25. 22. The apparatus of claim 21, further comprising at least one collection chamber deflector positioned at least partially within the adjacent gas collection chamber above the lateral separation chamber outlet.

26. 26. The apparatus of claim 25, wherein the at least one collection chamber deflector is positioned at least partially above the lateral separation chamber outlet.

27. 26. The apparatus of claim 25, wherein the at least one collection chamber deflector includes a concave surface facing the lower stripping bed region.

28. 26. The apparatus of claim 25, wherein the at least one separation chamber is two separation chambers, and the at least one collection chamber deflector extends between one of the two vertical side walls of a first of the two separation chambers and one of the two vertical side walls of a second of the two separation chambers.

29. 26. The apparatus of claim 25, wherein the at least one collection chamber deflector includes a downwardly pointed point.

30. 30. The device of claim 29, wherein the pointed portion is centered between two of the vertical side walls.

31. 26. The apparatus of claim 25, wherein the collection chamber deflector includes a dividing baffle extending from a concave surface for the collection chamber deflector.

32. 32. The apparatus of claim 31 , wherein the dividing baffle extends beyond a lower edge of the deflector in a direction parallel to the longitudinal axis.

33. 26. The apparatus of claim 25, further comprising at least one collection chamber conduit in an upper region of the collection chamber for discharging the decomposed gas and a minor portion of the solid particles from the collection chamber to a gas outlet collector.

34. 34. The apparatus of claim 33, wherein the at least one collection chamber conduit extends downwardly through the collection chamber deflector.

35. 26. The apparatus of claim 25, wherein at least one of the at least one separation chamber further comprises a separation chamber deflector positioned at least partially above the lateral separation chamber outlet.

36. 36. The apparatus of claim 35, wherein the separation chamber deflector is integrally formed with the collection chamber deflector.

37. 22. The apparatus of claim 21, wherein the riser reactor comprises a parabolic concave cone-shaped riser deflector at the at least one riser reactor outlet.

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