Patent Description:
Catalyst regenerators are used in a number of chemical process operations, including fluid catalytic cracking and catalytic dehydrogenation of lower alkanes. Conventional regenerators typically include a vessel having a spent catalyst inlet, a catalyst outlet and a distributor for supplying oxygen containing gas to the catalyst bed in the vessel. Two stage regenerators typically comprise two vessels which complete the oxygen contacting in two distinct steps. In a two stage process, the partially spent catalyst along with a gas in which the catalyst particles are entrained enter the lower vessel and rise through a riser which is capped with a riser terminator. In an outer wall of a top portion of the riser are openings, or slots, which allow the spent catalyst and product gas to exit the riser. The riser terminator typically has a cap and a plurality of arms enclosing the slots. The cap of conventional riser terminators generally resides a predetermined distance above the slots, providing internal riser space above the slots into which some of the gas and entrained catalyst particles may enter and impinge upon refluxing catalyst and the terminator cap. Such impingement with other refluxing particles causes breaking, or attrition, of some of the catalyst particles. After leaving the riser through the slots and the arms, the catalyst and gas passes into one or more cyclone separators. It is desirable to obtain separation of the catalyst and gas prior to the gas entering the one or more cyclones which will, in turn, remove ><NUM>% of the catalyst particles from the gas.

<CIT> describes an improved process and an improved apparatus for minimizing attrition of catalyst particles, especially propane dehydrogenation catalyst particles, entrained in a combined flow of such particles and an entraining gas in a catalyst recovery means during separation of such particles from the entraining gas, by use of a pre-treatment step in which the combined flow is at a rate between <NUM> and <NUM> meters per second are provided.

<CIT> describes a gas-solids reaction system with termination devices to connect a riser with one or more separation devices. The termination devices have a radius of curvature that is at least <NUM> times as great as the diameter of the conduit forming the termination device. The termination devices can be openly or closely coupled to the separation device.

<CIT> describes a gas/solid separation system that can be applied to any type of FCC unit regenerators. It consists of a device for separating solid particles contained in a gas stream coming from the regeneration zone of a fluid catalytic cracking (FCC) unit bounded by an inner envelope of cylindrical shape centred about the vertical axis of the regeneration zone, and an outer envelope that has one approximately horizontal wall, followed by one curvilinear wall, and one approximately vertical wall, the set of said walls covering the inner envelope and forming a set of separation chambers radially distributed around the inner envelope in which the gas/solid suspension to be separated circulates.

In summary, there is provided a catalyst regenerator for combusting carbonaceous deposits from a catalyst according to claim <NUM>.

There is also provided a riser termination device according to claim <NUM>.

Referring to <FIG>, the catalyst regenerator <NUM> for combusting carbonaceous deposits from a catalyst is shown. The catalyst regenerator <NUM> includes a first chamber <NUM> including a catalyst inlet <NUM> and a second chamber <NUM>. The catalyst regenerator <NUM> also includes an oxygen-containing gas distributor <NUM> and a supplemental fuel distributor, <NUM>. A riser section <NUM> extends from the first chamber <NUM>. The second chamber <NUM> includes one or more cyclone separators and a reconditioning zone. As shown in <FIG>, a primary cyclone <NUM> and secondary cyclone <NUM> may be present. Reconditioning zone <NUM> is used to contact the further deactivated catalyst particles with oxygen. The top of riser section <NUM> includes a riser termination device <NUM>. A plurality of grids <NUM> may be present in a lower section of the second chamber <NUM>. The processes conditions for operating a catalyst regenerator for propane dehydrogenation catalyst as shown in <FIG> are generally described in <CIT>.

The riser section <NUM> has an outer wall <NUM>, at least one opening <NUM> in the topmost section of the outer wall <NUM>. Referring now to <FIG>, an elevational view of a top portion of the riser section <NUM> is shown. The riser section <NUM> further includes a riser termination device <NUM> which caps the riser section <NUM>. The riser termination device <NUM> includes a substantially internally flat cover plate <NUM>.

For each opening <NUM>, the riser termination device <NUM> includes at least one arm <NUM> which extends from the cover plate <NUM>. Each at least one arm <NUM> is formed from an outer shell <NUM> which has a top portion 31a and two side portions 31b, as seen in <FIG>. The outer shell <NUM> forms a partial cover over the opening <NUM>. As shown in <FIG>, no internal portion of the riser section <NUM> or cover plate <NUM> extends above the outer shell <NUM> of the at least one arm <NUM>, with the proviso that the riser shell <NUM> may have an upper lip at opening <NUM> onto which the at least one arm <NUM> is attached. Therefore, the catalyst particles in the riser section <NUM> do not pass internally in the riser above the level of the opening <NUM>.

As seen in <FIG>, external components of the riser section <NUM> may extend above the level of the openings <NUM>. Such external components may include a cap <NUM> which may be attached to the vessel <NUM> in order to stabilize and/or secure the riser section <NUM>. As further shown in <FIG>, the riser cap <NUM> may be held in place through one or more straps <NUM>. Straps <NUM> may be connected to either or both of the vessel <NUM> and the riser cap <NUM> in a hinged manner permitting longitudinal and radial expansion and contraction. As shown in <FIG>, each strap <NUM> comprises a tubular rod <NUM> having two open ends into which a metal strip <NUM> is inserted. Metal strips <NUM> are preferably sufficiently pliant to allow some flexion upon thermal expansion and contraction of the riser section <NUM>.

The at least one arm <NUM> extends tangentially or approximately tangentially from the cover plate, as shown in <FIG>. In an alternative example not according to the invention, the arm extends radially from the cover plate as shown in <FIG>. To further describe the angle that the arm may extend from the cover plate, each of <FIG> and <FIG> further denote point A as a centerpoint of between the two sides 31b of the arm <NUM>. From point A, a dotted line is drawn wherein the dotted line is parallel to the two sides 31b of the arm <NUM>. Where the dotted line intersect the outside edge of the cover plate <NUM> is point B. A dashed line is drawn tangential to cover plate <NUM> and passing through point B. The angle D between the dashed and dotted lines is shown in <FIG> and <FIG>. As used herein, angle D is defined as the "arm angle". The arm angle is from <NUM> to <NUM>°.

The at least one arm <NUM> may extend substantially horizontally outward from the cover plate <NUM> for a distance, as shown in <FIG> before turning downward. Alternatively, the at least one arm <NUM> may turn downward proximate to the cover plate <NUM> as shown in <FIG>.

<FIG> illustrates an alternative arm configuration wherein the arm includes an arm extension <NUM> which extends vertically below the side sections 31b of outer shell <NUM>. <FIG> similarly shows such alternative arm configuration. The arm extension <NUM> may be in the shape of a squared or rounded U. <FIG> further illustrates stiffening ribs <NUM> used to provide mechanical strength to the riser cap <NUM>. In an alternative embodiment, the arm extension <NUM> extends below a lower edge of opening <NUM>.

In one embodiment, the aspect ratio (height divided by width) of the at least one slot ranges from <NUM> to <NUM>. All individual values and subranges from <NUM> to <NUM> are included and disclosed herein; for example, the aspect ratio of the at least one slot may range from a lower limit of <NUM>, <NUM>, or <NUM> to an upper limit of <NUM>, <NUM>, <NUM> or <NUM> For example, the aspect ratio of the at least one slot may range from <NUM> to <NUM>, or in the alternative, from <NUM> to <NUM>, or in the alternative, from <NUM> to <NUM>, or in the alternative, from <NUM> to <NUM>.

The disclosure provides the catalyst regenerator and riser termination device according to any embodiment disclosed herein, except that the riser flux is from <NUM>/m<NUM> sec to <NUM>/m<NUM> sec (<NUM> to <NUM> lb/ft<NUM> sec). All individual values and subranges from <NUM>/m<NUM> sec to <NUM>/m<NUM> sec (<NUM> to <NUM> lb/ft<NUM> sec) are included and disclosed herein; for example, the riser flux may range from a lower limit of <NUM>/m<NUM> sec, <NUM>/m<NUM> sec, <NUM>/m<NUM> sec, <NUM>/m<NUM> sec, <NUM>/m<NUM> sec, or <NUM>/m<NUM> sec (<NUM>, <NUM>, <NUM>, <NUM>, <NUM>, or <NUM> lb/ft<NUM> sec to an upper limit of <NUM>/m<NUM> sec, <NUM>/m<NUM> sec, <NUM>/m<NUM> sec, <NUM>/m<NUM> sec, or <NUM>/m<NUM> sec (<NUM>, <NUM>, <NUM>, <NUM>, or <NUM> lb/ft<NUM> sec). For example, the riser flux may be from <NUM>/m<NUM> sec to <NUM>/m<NUM> sec (<NUM> to <NUM> lb/ft<NUM> sec), or in the alternative, from <NUM>/m<NUM> sec to <NUM>/m<NUM> sec (<NUM> to <NUM> lb/ft<NUM> sec), or in the alternative, from <NUM>/m<NUM> sec to <NUM>/m<NUM> sec (<NUM> to <NUM> lb/ft<NUM> sec), or in the alternative, from <NUM>/m<NUM> sec to <NUM>/m<NUM> sec (<NUM> to <NUM> lb/ft<NUM> sec), or in the alternative, from <NUM>/m<NUM> sec to <NUM>/m<NUM> sec (<NUM> to <NUM> lb/ft<NUM> sec).

The disclosure provides the catalyst regenerator and riser termination device according to any embodiment disclosed herein, except that the superficial velocity of the riser varies from <NUM>/s to <NUM>/s (<NUM> to <NUM> ft/s). All individual values and subranges from <NUM>/s to <NUM>/s (<NUM> to <NUM> ft/s) are included and disclosed herein; for example, the superficial velocity of the riser can range from a lower limit of <NUM>/s, <NUM>/s, <NUM>/s, <NUM>/s, <NUM>/s, or <NUM>/s (<NUM>, <NUM>, <NUM>, <NUM>, <NUM>, or <NUM> ft/sec) to an upper limit of <NUM>/s, <NUM>/s, <NUM>/s, <NUM>/s, <NUM>/s, <NUM>/s, or <NUM>/s (<NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, or <NUM> ft/sec). For example, the superficial velocity of the riser may be from <NUM>/s to <NUM>/s (<NUM> to <NUM> ft/sec), or in the alternative, from <NUM>/s to <NUM>/s (<NUM> to <NUM> ft/sec), or in the alternative, from <NUM>/s to <NUM>/s (<NUM> to <NUM> ft/sec), or in the alternative, from <NUM>/s to <NUM>/s (<NUM> to <NUM> ft/sec).

In a particular embodiment, the velocity of the stream exiting the arms is determined by X*(Ariser/Aopenings) wherein X is the velocity of the stream in the riser and (Ariser/Aopenings) is the ratio of the cross section area of the riser (Ariser) to the sum of the cross-sectional areas of the openings <NUM> which communicate with the arms <NUM> and which are located at the top of the riser (Aopenings). In one embodiment, Ariser/Aopenings is from <NUM> to <NUM>. All individual values and subranges from <NUM> to <NUM> are included and disclosed herein; for example, X may range from a lower limit of <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, or <NUM> to an upper limit of <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, or <NUM>. For example, X may range from <NUM> to <NUM>, or in the alternative, from <NUM> to <NUM>, or in the alternative, from <NUM> to <NUM>.

Claim 1:
A catalyst regenerator (<NUM>) for combusting carbonaceous deposits from a catalyst comprising:
a first chamber (<NUM>) which comprises
a catalyst inlet (<NUM>) for feeding spent catalyst with carbonaceous deposits to said first chamber (<NUM>),
a supplemental fuel gas distributor (<NUM>), and
a distributor (<NUM>) for an oxygen containing gas for distributing oxygen containing gas into said first chamber (<NUM>) to contact said spent catalyst and combust carbonaceous deposits and supplemental fuel which further deactivates the spent catalyst and generates flue gas;
a riser section (<NUM>) extending from said first chamber (<NUM>) for transporting the spent catalyst and the flue gas, the riser section (<NUM>) comprising an outer wall (<NUM>), at least one slot (<NUM>) in the outer wall (<NUM>), and a riser termination device (<NUM>) which comprises a substantially internally flat cover plate (<NUM>), at least one arm (<NUM>) extending from the cover plate (<NUM>), wherein the at least one arm (<NUM>) extends about the slot (<NUM>) from the outer wall (<NUM>) and the at least one arm (<NUM>) extends from the cover plate (<NUM>) at an arm angle (D) of from <NUM> degrees to <NUM> degrees, the at least one arm (<NUM>) comprising an outer shell (<NUM>) that encloses the arm (<NUM>), the outer shell (<NUM>) having a top portion (31a) and two side portions (31b), and wherein no internal portion of the cover plate (<NUM>) extends above an upper surface of the outer shell (<NUM>) of the at least one arm (<NUM>),
wherein the arm angle (D) is defined between a first line extending parallel to the two side portions (31b) of the arm (<NUM>) from a centrepoint (A) between the two side portions (31b) of the arm (<NUM>), and a second line tangential to the cover plate (<NUM>) and passing through a point (B) where the first line intersects an outside edge of the cover plate (<NUM>).