Abstract:
A baffle is installed on the wall of a regenerator vessel to push catalyst away from the wall to ensure adequate exposure to regeneration gas and complete combustion of coke from the catalyst. We have found that in deep beds, catalyst can flow down the walls and escape sufficient exposure to regeneration gas and undergo too little regeneration.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims priority from Provisional Application No. 62/220,128 filed Sep. 17, 2015, the contents of which are hereby incorporated by reference. 
     
    
     BACKGROUND 
       [0002]    The field is the regeneration of catalyst in a catalyst regenerator vessel. 
         [0003]    Fluid catalytic cracking (FCC) is a hydrocarbon conversion process accomplished by contacting hydrocarbons in a fluidized reaction zone with a catalyst composed of finely divided particulate material. The reaction in catalytic cracking, as opposed to hydrocracking, is carried out in the absence of substantial added hydrogen or the consumption of hydrogen. As the cracking reaction proceeds, substantial amounts of highly carbonaceous material referred to as coke is deposited on the catalyst. A high temperature regeneration operation within a regenerator zone combusts coke from the catalyst. Coke-containing catalyst, referred to herein as coked catalyst, is continually removed from the reaction zone and replaced by essentially coke-free catalyst from the regeneration zone. Fluidization of the catalyst particles by various gaseous streams allows the transport of catalyst between the reaction zone and regeneration zone. 
         [0004]    A common objective of these configurations is maximizing product yield from the reactor while minimizing operating and equipment costs. Optimization of feedstock conversion ordinarily requires essentially complete removal of coke from the catalyst. This essentially complete removal of coke from catalyst is often referred to as complete regeneration. Complete regeneration produces a catalyst having less than 0.1 and preferably less than 0.05 wt-% coke. In order to obtain complete regeneration, the catalyst has to be in contact with oxygen for sufficient residence time to permit thorough combustion. 
         [0005]    Regenerators typically include a vessel having a coked catalyst inlet, a regenerated catalyst outlet and a regeneration gas distributor for supplying air or other oxygen containing gas to the bed of catalyst that resides in the vessel. Cyclone separators remove catalyst entrained in the flue gas before the gas exits the regenerator vessel. 
         [0006]    In a bubbling bed regenerator, fluidizing regeneration gas forms bubbles that ascend through a discernible top interface of a dense catalyst bed. Only catalyst entrained in the gas exits the dense catalyst bed with the regeneration gas. The superficial velocity of the regeneration gas is typically less than 1.2 m/s (4.2 ft/s) and the density of the dense bed is typically greater than 320 kg/m 3  (20 lb/ft 3 ) depending on the characteristics of the catalyst. 
         [0007]    A bubbling bed regenerator may have just one chamber in which air is bubbled through a dense catalyst bed. Coked catalyst is added and regenerated catalyst is withdrawn from the same dense catalyst bed. Relatively little catalyst is entrained in the flue gas exiting the dense bed. Two-stage bubbling bed regenerators have two chambers. Coked catalyst is added to a dense bed in a first chamber and is partially regenerated with air. The partially regenerated catalyst is transported to a dense bed in a second chamber and completely regenerated with air. The completely regenerated catalyst is withdrawn from the second chamber. Some bubbling bed regenerators have deep bubbling beds in which the interface between the dense catalyst phase and the dilute catalyst phase can be at least 7.6 m (25 feet) high. 
         [0008]    Sufficient exposure of coked catalyst to regeneration gas is necessary to completely burn coke from the coked catalyst. Sufficient exposure requires thorough mixing of catalyst and regeneration gas and sufficient residence time for the coked catalyst and regeneration gas to be with each other. 
         [0009]    Improved methods are sought for ensuring coked catalyst is sufficiently exposed to the regeneration gas. 
       SUMMARY 
       [0010]    We have discovered that catalyst can flow down the walls of a regenerator. Baffles can be provided to push catalyst away from the walls to facilitate thorough catalyst regeneration. 
         [0011]    One embodiment is a process for combusting coke from catalyst comprising delivering coked catalyst to a regenerator vessel. Regeneration gas is delivered to the regenerator vessel for combusting coke from the catalyst to produce flue gas and regenerated catalyst. Catalyst is pushed away from a wall of the regenerator vessel to ensure thorough regeneration. Flue gas is separated from the regenerated catalyst and regenerated catalyst and flue gas are discharged from the regenerator vessel. 
         [0012]    An additional embodiment is a catalyst regenerator vessel for combusting coke from catalyst. The regenerator comprises a wall, a catalyst inlet for feeding catalyst to the vessel, a distributor for distributing regeneration gas to the vessel and a separator in communication with the regenerator vessel for separating gas from the catalyst. A baffle on the wall pushes catalyst away from the wall. A flue gas outlet discharges flue gas from the vessel and a regenerated catalyst outlet discharges regenerated catalyst from the vessel. 
         [0013]    In a further embodiment a wall of the regenerator vessel is at least 7.6 meters in height. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWING 
         [0014]    The FIGURE is a schematic, elevational view of an FCC unit. 
       
    
    
     DEFINITIONS 
       [0015]    The term “communication” means that material flow is operatively permitted between enumerated components. 
         [0016]    The term “downstream communication” means that at least a portion of material flowing to the subject in downstream communication may operatively flow from the object with which it communicates. 
         [0017]    The term “upstream communication” means that at least a portion of the material flowing from the subject in upstream communication may operatively flow to the object with which it communicates. 
         [0018]    As used herein, the term “T5” or “T95” means the temperature at which 5 volume percent or 95 volume percent, as the case may be, respectively, of the sample boils using ASTM D-86. 
         [0019]    As used herein, the term “initial boiling point” (IBP) means the temperature at which the sample begins to boil using ASTM D-86. 
         [0020]    As used herein, the term “end point” (EP) means the temperature at which the sample has all boiled off using ASTM D-86. 
         [0021]    As used herein, the term “separator” means a vessel which has an inlet and at least two outlets. 
       DETAILED DESCRIPTION 
       [0022]    Regenerators that have deep catalyst beds such as over about 7.6 meters (25 feet) are subject to flow distribution problems that can lead to incomplete regeneration of the catalyst. We have discovered that in these units a large downward annular flow of catalyst along the walls of the regenerator can lead to shorter residence time and insufficient contact of catalyst with the regeneration air. The coked catalyst returns to the reactor insufficiently active and does not convert feed as desired, so the unit suffers decreased yields. Understanding this phenomenon, a device to prevent downward catalyst flow along the walls of the regenerator will improve the catalyst regeneration and overall FCC performance. Deflector baffles attached to the walls of the regenerator will force the catalyst away from the wall and into the main section of the regenerator where the catalyst can be mixed with the air for complete regeneration. 
         [0023]    Although other uses are contemplated, the process and apparatus may be embodied in an FCC unit. The FIGURE shows an FCC unit that includes a reactor section  10  and a regenerator vessel  50 . A regenerated catalyst conduit  12  transfers regenerated catalyst from the regenerator vessel  50  at a rate regulated by a control valve  14  to a riser  20  of the reactor section  10 . A fluidization medium such as steam from a nozzle  16  transports regenerated catalyst upwardly through the riser  20  at a relatively high density until a plurality of feed injection nozzles  18  inject hydrocarbon feed across the flowing stream of catalyst particles. The catalyst contacts the hydrocarbon feed cracking it to produce smaller, cracked hydrocarbon products while depositing coke on the catalyst to produce coked catalyst. Process conditions typically include a cracking reaction temperature of 400° to 600° C. and a pressure preferably of about 173 to about 414 kPa (gauge) (25 to 60 psig). 
         [0024]    A conventional FCC feedstock and higher boiling hydrocarbon feedstock are suitable fresh hydrocarbon feed streams. The most common of such conventional fresh hydrocarbon feedstocks is a “vacuum gas oil” (VGO), which is typically a hydrocarbon material having a boiling range with an IBP of no more than about 340° C. (644° F.), a T5 between about 340° C. (644° F.) to about 350° C. (662° F.), a T95 between about 555° C. (1031° F.) and about 570° C. (1058° F.) and an EP of no less than about 570° C. (1058° F.) prepared by vacuum fractionation of atmospheric residue. Such a fraction is generally low in coke precursors and heavy metal contamination which can serve to contaminate catalyst. Atmospheric residue is a another suitable feedstock boiling with an IBP of no more than about 340° C. (644° F.), a T5 between about 340° C. (644° F.) and about 360° C. (680° F.) and a T95 of between about 700° C. (1292° F.) and about 900° C. (1652° F.) and an EP of no less than about 900° C. (1652° F.) obtained from the bottom of an atmospheric crude distillation column. Atmospheric residue is generally high in coke precursors and metal contamination. Other heavy hydrocarbon feedstocks which may serve as fresh hydrocarbon feed include heavy bottoms from crude oil, heavy bitumen crude oil, shale oil, tar sand extract, deasphalted residue, products from coal liquefaction, vacuum reduced crudes. Fresh hydrocarbon feedstocks also include mixtures of the above hydrocarbons and the foregoing list is not comprehensive. 
         [0025]    The resulting mixture continues upwardly through the riser  20  to a top at which a plurality of disengaging arms  22  tangentially and horizontally discharge the mixture of gas and catalyst from a top of the riser  20  through ports  24  into a disengaging vessel  26  that effects separation of gases from the catalyst. A transport conduit  28  carries the hydrocarbon vapors, including stripped hydrocarbons, stripping media and entrained catalyst to one or more cyclones  30  in a reactor vessel  32  which separates coked catalyst from the hydrocarbon vapor stream. The reactor vessel  32  may at least partially contain the disengaging vessel  26  and the disengaging vessel  26  is considered part of the reactor vessel  32 . A collection chamber  34  in the reactor vessel  32  gathers a separated hydrocarbon product vapor stream from the cyclones  30  for passage to an outlet nozzle  36  and eventually into a fractionation recovery zone that is not shown. Diplegs  38  discharge catalyst from the cyclones  30  into a lower portion of the reactor vessel  32  that eventually passes the catalyst and adsorbed or entrained hydrocarbons into a stripping section  40  of the reactor vessel  32  across ports  42  defined in a wall of the disengaging vessel  26 . Catalyst separated in the disengaging vessel  26  passes directly into the stripping section  40 . The stripping section  40  contains baffles  43 ,  44  or other equipment to promote mixing between a stripping gas and the catalyst. The stripping gas enters a lower portion of the stripping section  40  through a conduit to one or more distributors  46 . The coked catalyst leaves the stripping section  40  of the reactor vessel  32  through a reactor catalyst conduit  48  and passes to the regenerator vessel  50  at a rate regulated by a control valve  52 . The coked catalyst from the reactor vessel  32  usually contains carbon in an amount of from 0.2 to 2 wt-%, which is present in the form of coke. Although coke is primarily composed of carbon, it may contain from 3 to 12 wt-% hydrogen as well as sulfur and other materials. 
         [0026]    The regenerator vessel  50  may be a bubbling bed type of regenerator as shown in the FIGURE. However, other regenerator vessels and other flow conditions may also be suitable. Particularly, a two-stage bubbling bed regenerator would be suitable. The regenerator vessel includes an outer wall  51  that defines a lower section  62 , a frustoconical section  64  and an upper section  66 . The outer wall  51  may be at least about 7.6 meters (25 feet) tall and is tubular and preferably cylindrical. The reactor catalyst conduit  48  with an inlet  48   a  in downstream communication with the reactor vessel  32  may transport coked catalyst to a regenerator riser  54  to which air or other oxygen-containing regeneration gas may be added through an outlet of a regeneration gas line  55  via riser gas line  55   a.  It is also contemplated that other lift gases may be used to lift the coked catalyst up the regenerator riser  54 . In an embodiment, the coked catalyst descends the reactor catalyst conduit  48  to a bight which communicates with the regenerator riser  54 . The coked catalyst bends around the bight as it is picked up by the lift gas from riser gas line  55   a  with an outlet in upstream communication with the regenerator riser  54 . The coked catalyst then travels up the regenerator riser  54  and enters the lower section  62  of the regenerator vessel  50  through a coked catalyst inlet  56  into a dense catalyst bed  57 . Coked catalyst is delivered to a catalyst distributor  60  in downstream communication with the catalyst inlet  56  and the outlet from riser gas line  55   a.  The distributor  60  distributes coked catalyst to the regenerator vessel  50 . 
         [0027]    Oxygen-containing regeneration gas, typically air, from regeneration gas line  55  is primarily delivered to the regenerator vessel  50  by a regeneration gas distributor  80  below the catalyst distributor  60 . In an embodiment, regeneration gas distributor  80  distributes most or all of the regeneration gas to the regenerator vessel  50  and is fed by a distributor gas line  55   b  from regeneration gas line  55  regulated by a control valve. Flutes  82  in the regeneration gas distributor  80  are arranged to emit regeneration gas equally to the entire cross section of the regenerator vessel  50 . The oxygen in the regeneration gas contacts the coked catalyst and combusts carbonaceous deposits from the catalyst to regenerate the catalyst and produce regenerated catalyst and flue gas. 
         [0028]    The upper section  66  has a larger cross-sectional area than the lower section  62  of the regenerator vessel  50 , and the frustoconical section  64  has a gradually increasing cross section as its height increases to transition between the lower section and the upper section. As the catalyst and the flue gas ascend above a top of the lower section  62  into the frustoconical section  64  and the upper section  66  to a larger cross-sectional area, a superficial gas velocity decreases to generate dilute phase conditions. Consequently, a discernible interface  58  between dense bed and dilute phase conditions is demarked at a top of the dense bed  57 . Typically, the interface  58  generates in the frustoconical section  64  or in the bottom of the upper section  66 . Catalyst gets entrained with flue gas ascending in the regenerator vessel  50  in the upper section. The catalyst entrained in the flue gas will therefore enter cyclone separators  86 ,  88  which centripetally separate flue gas from heavier catalyst particles. Catalyst particles will fall down dip legs  87 ,  89  and enter dense catalyst bed  58  again. Cleaned flue gas will ascend from the cyclone separators  86 ,  88  through ducts into plenum  90  and discharge through flue gas outlet  92 . Regenerated catalyst will depart the dense catalyst bed  58  in the regenerator vessel  50  through a regenerated catalyst outlet  96 . Regenerated catalyst conduit  12  in downstream communication with the outlet  96  delivers regenerated catalyst back to the reactor riser  20  at a rate regulated by control valve  14 . 
         [0029]    Regeneration gas such as air may be used to lift coked catalyst up the regenerator riser  54  which may allow regeneration to occur within the regenerator riser. The regeneration gas to the regenerator riser  54  may be 10-20 wt-% of regeneration gas to the regenerator vessel  50 . If air is the regeneration gas, typically 12-15 kg (lbs) of air is required per kilogram (pound) of coke fed on catalyst to the regenerator. The temperature of the regenerator vessel  50  is about 500 to 900° C. and usually about 600 to 750° C. Pressure in the regenerator vessel  50  is preferably 173 to 414 kPa (gauge) (25 to 60 psig). The superficial velocity of the regeneration gas is typically less than 1.2 m/s (4.2 ft/s), but may be greater in some instances, and the density of the dense bed is typically greater than 320 kg/m 3  (20 lb/ft 3 ) depending on the characteristics of the catalyst. Preferably, the superficial velocity of the regeneration gas is typically less than 0.5 m/s (1.5 ft/s) and the density of the dense bed is typically greater than 640 kg/m 3  (40 lb/ft 3 ). The mixture of catalyst and gas is heterogeneous with pervasive vapor bypassing of catalyst. 
         [0030]    We have discovered by Computational Fluid Dynamics modeling that a high proportion of coked catalyst annularly flows down around the wall of the regenerator vessel in the dense catalyst bed and avoids sufficient contact with the regeneration gas. This downwardly flowing catalyst avoids regeneration and exits the regenerator vessel  50  through exit  96  and goes back to the riser  20  with less than full activity resulting in poor conversion of feed and yield for the FCC unit. The problem is especially found in deep regenerator vessels having dense beds that are at least 7.6 meters (25 feet) high and is more acute when the dense bed is at least about 15 meters (50 feet) high and particularly when the dense bed is at least about 23 meters (75 feet) high. 
         [0031]    With this problem discovered, a baffle  100  should be installed on the vessel wall  51  to ring the lower section  62  that contains the dense bed  57 . The baffle  100  may be disposed between the cyclone separators  86  and  88  and the regeneration gas distributor  80 . The baffle  100  may have an upper surface that pushes the downwardly flowing catalyst away from the wall  51  toward the center of the regenerator vessel  50  in the dense catalyst bed. A plurality  112  of baffles  100  may be used to push catalyst away from the wall  51 . 
         [0032]    The regenerator vessel  50  may have a lining that is not shown in an interior surface of the wall  51 . The wall is made of steel, but the lining thickness may vary with type of application and other factors. However, in many applications the lining thickness will be between about 5.1 and about 30.5 cm (about 2 and about 12 inches). The baffles  100  extend inwardly from the wall  51  into the regenerator vessel  50 . The baffles  100  extend circumferentially about the perimeter of the regenerator vessel  50  in the lower section  62  that contains the dense bed  57 . The baffles  100  are configured to disrupt the downward flow path of the catalyst as it falls along the wall  51  of the regenerator vessel  50 . 
         [0033]    The baffle  100  may have a variety of shapes and sizes. The baffle  100  extends inwardly toward the center of the regenerator vessel  50  away from the wall  51  from an upper edge  102  on the wall  51  to an innermost peak  104  to define an upper surface  106 . The baffle may have a horizontal upper surface but it may be sloped. Preferably, the upper surface is sloped downwardly, so catalyst is pushed away from the wall in a downwardly sloping direction. The baffle  100  may comprise a plate defining the upper surface  106 . The baffle  100  may comprise an additional plate extending from the first plate at a different angle than defined by the first plate with the wall  51 . Optionally, the baffle  100  may have a lower surface  108  that may be more than just a parallel bottom surface of the plate defining the upper surface  106 . The lower surface  108  may gradually retreat from the peak  104  toward the wall  51  to a lower edge of the baffle  100  on the wall  51  in a slope to facilitate upwardly moving catalyst and gas. For example, the baffle  100  may have a generally triangular cross section and generally geometrically favor a triangulated venturi style flow restriction. In some embodiments, the cross section of the baffle  100  defines a generally obtuse isosceles triangle. The peak  104  may be rounded or take other shapes. The baffle  100  may also have a trapezoidal cross sectional configuration comprising a side oriented closely to vertical between the top surface  106  and the lower surface  108 . In an embodiment, the upper surface  106  defines a larger internal angle with the wall  51  than an internal angle defined by the lower surface  108  and the wall. Additionally, baffles  100  may adopt different shapes than that described. The lining on the wall  51  may continuously cover the baffles  100  which can also be made of steel. 
         [0034]    In an embodiment, a baffle  100  should be disposed near the top of the dense bed  57  at a top  114  of the lower section  62  below or near the point where the cross section of the regenerator vessel  50  begins to enlarge. Specifically, a baffle  100  should be positioned in the top seventh of the lower section. Accordingly, catalyst is pushed away from the wall  51  near a top of the dense catalyst bed  57  and at a top of the lower section  62  of the regenerator vessel  50 . 
         [0035]    A plurality  112  of baffles  100  may be positioned at a plurality of levels in the lower section  62  where the dense bed  57  will be formed, so catalyst is pushed away from the wall  51  at a plurality of elevations. The baffles  100  may be evenly spaced apart or not evenly spaced. The baffles  100  may be spaced about 5 to about 7 meters (16 to about 23 feet) apart. Baffles may extend into the regenerator vessel  50  by about 0.3 to about 1 meter (1 to about 3 feet) from the wall  51 . 
         [0036]    The baffle  100  may comprise a continuous ring around the perimeter or circumference of the regenerator vessel  50 , so the catalyst is pushed away from the wall  51  around an entire perimeter or circumference of the regenerator vessel  50 . As such, the baffle  100  should extend around the entire lateral perimeter of the regenerator vessel  50 . In some cases, an obstacle  110  such as a man way on the wall  51  may hinder a baffle  100  from continuously ringing the entire perimeter. Nevertheless, a baffle  100  may comprise a series of segments  100   a  and  100   b  that together may extend around the entire horizontal perimeter of the regenerator vessel while the baffle segments  100   a  and  100   b  are positioned at different elevations on the wall  51  of the regenerator vessel  50 . Accordingly, the baffle segments  100   a  and  100   b  push the downwardly flowing catalyst away from the wall around the entire horizontal perimeter of the regenerator vessel  50  but at different elevations on the wall  51 . Ends of the baffle segments  100   a  and  100   b  may overlap vertically or may extend to the same vertical position. 
       SPECIFIC EMBODIMENTS 
       [0037]    While the following is described in conjunction with specific embodiments, it will be understood that this description is intended to illustrate and not limit the scope of the preceding description and the appended claims. 
         [0038]    A first embodiment is a process for combusting coke from catalyst comprising delivering coked catalyst to a regenerator vessel; delivering regeneration gas to the regenerator vessel for combusting coke from the catalyst to produce flue gas and regenerated catalyst; pushing catalyst away from a wall of the regenerator vessel; separating the flue gas from the regenerated catalyst; discharging regenerated catalyst from the regenerator vessel; and discharging flue gas from the regenerator vessel. An embodiment is one, any or all of prior embodiments in this paragraph up through the first embodiment in this paragraph further including allowing catalyst to flow downwardly along a wall of the regenerator vessel and pushing downwardly flowing catalyst away from the wall. An embodiment is one, any or all of prior embodiments in this paragraph up through the first embodiment in this paragraph wherein the regenerator is a bubbling bed regenerator. An embodiment is one, any or all of prior embodiments in this paragraph up through the first embodiment in this paragraph wherein the catalyst is pushed away from the wall in a dense catalyst bed. An embodiment is one, any or all of prior embodiments in this paragraph up through the first embodiment in this paragraph wherein the catalyst is pushed away from the wall near a top of the dense catalyst bed. An embodiment is one, any or all of prior embodiments in this paragraph up through the first embodiment in this paragraph further comprising pushing catalyst away from the wall around an entire perimeter of the regenerator vessel. An embodiment is one, any or all of prior embodiments in this paragraph up through the first embodiment in this paragraph further comprising pushing catalyst away from the wall around the entire perimeter but at different elevations. An embodiment is one, any or all of prior embodiments in this paragraph up through the first embodiment in this paragraph further comprising pushing catalyst away from the wall at different elevations. An embodiment is one, any or all of prior embodiments in this paragraph up through the first embodiment in this paragraph further comprising pushing catalyst away from the wall in a downwardly sloping direction. 
         [0039]    A second embodiment is a catalyst regenerator vessel for combusting coke from catalyst comprising a wall of the regenerator vessel; a catalyst inlet for feeding catalyst to the vessel; a distributor for distributing regeneration gas to the vessel; a baffle on the wall for pushing catalyst away from the wall; a separator in communication with the regenerator vessel for separating gas from the catalyst; a flue gas outlet for discharging flue gas from the vessel; and a regenerated catalyst outlet for discharging regenerated catalyst from the vessel. An embodiment is one, any or all of prior embodiments in this paragraph up through the second embodiment in this paragraph wherein the baffle is disposed between the separator and the distributor. An embodiment is one, any or all of prior embodiments in this paragraph up through the second embodiment in this paragraph wherein the baffle has a triangular cross section. An embodiment is one, any or all of prior embodiments in this paragraph up through the second embodiment in this paragraph wherein the baffle extends around the entire horizontal perimeter of the regenerator vessel. An embodiment is one, any or all of prior embodiments in this paragraph up through the second embodiment in this paragraph wherein the baffle comprises a series of segments that extend around the entire horizontal perimeter of the regenerator vessel and segments are positioned at different elevations. An embodiment is one, any or all of prior embodiments in this paragraph up through the second embodiment in this paragraph wherein the regenerator vessel includes a lower section and an upper section which has a cross-sectional area that is greater than the lower section and the baffle is located at a top of the lower section. An embodiment is one, any or all of prior embodiments in this paragraph up through the second embodiment in this paragraph further comprising a plurality of baffles on the wall. An embodiment is one, any or all of prior embodiments in this paragraph up through the second embodiment in this paragraph wherein the baffle has a sloped upper surface. An embodiment is one, any or all of prior embodiments in this paragraph up through the second embodiment in this paragraph further comprising a bubbling bed regenerator. An embodiment is one, any or all of prior embodiments in this paragraph up through the second embodiment in this paragraph wherein the lower section is at least 7.6 meters high. 
         [0040]    A third embodiment is a catalyst regenerator vessel for combusting coke from catalyst comprising a wall of the regenerator vessel of at least 7.6 meters in height; a catalyst inlet for feeding catalyst to the vessel; a distributor for distributing regeneration gas to the vessel; a baffle on the wall for pushing catalyst away from the wall; a separator in communication with the regenerator vessel for separating gas from the catalyst; a flue gas outlet for discharging flue gas from the vessel; and a regenerated catalyst outlet for discharging regenerated catalyst from the vessel. 
         [0041]    Without further elaboration, it is believed that using the preceding description that one skilled in the art can utilize the present disclosure to its fullest extent and easily ascertain the essential characteristics, without departing from the spirit and scope thereof, to make various changes and modifications and to adapt it to various usages and conditions. The preceding preferred specific embodiments are, therefore, to be construed as merely illustrative, and not limiting the remainder of the disclosure in any way whatsoever, and that it is intended to cover various modifications and equivalent arrangements included within the scope of the appended claims. 
         [0042]    In the foregoing, all temperatures are set forth in degrees Celsius and, all parts and percentages are by weight, unless otherwise indicated.