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US 4,797,262 AGranted
Downflow fluidized catalytic cracking system
AssigneeShell Oil Company
InventorThomas S. Dewitz
Life of this patent
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Abstract
This invention discloses an integral hydrocarbon conversion apparatus having a downflow hydrocarbon reactor, an upflow riser regenerator and a horizontal cyclone separator to permit the conversion of hydrocarbonaceous materials to hydrocarbonaceous products of lower molecular weight in a near zero pressure drop environment. A leg seal is provided surmounted to the downflow reactor to insure that the pressure is at least 0.5 psi higher than the upper portion of the downflow reactor (higher than the loop seal valve) vis-a-vis the pressure in the lower portion of the downflow reactor.
Claims19
An integral hydrocarbon catalytic cracking conversion apparatus for the catalytic conversion of a hydrocarbon feed material to a hydrocarbon product material having smaller molecules which comprises:
- (a) an elongated catalytic downflow reactor having a top and bottom portion comprising a hydrocarbon feed inlet at a position juxtaposed to said top portion of said downflow reactor, a regenerated catalyst inlet at a position juxtaposed to said top portion of said downflow reactor and a product and spent catalyst withdrawal outlet at a position juxtaposed to said bottom portion of said downflow reactor;
- (b) an elongated upflow catalytic riser regenerator having a top and bottom portion for regeneration of spent catalyst passed from said catalytic downflow reactor having a spent catalyst inlet at a position juxtaposed to said bottom portion of said regenerator, a regeneration gas inlet means for entry of an oxygen-containing gas at a position juxtaposed to said bottom portion of said regenerator, a uniform fast fluidized or entrained bed of regenerating catalyst situated from near said bottom to near said top of said riser regenerator and a regenerated catalyst and vapor phase outlet at a position juxtaposed to said top portion said regenerator, said outlet having a means to remove regenerated catalyst and vapors resultant from the oxidation of coke, present on said spent catalyst, with said oxygencontaining regeneration gas;
- (c) a horizontal cyclonic separator for separating spent catalyst from hydrocarbon product material, said horizontal cyclone separator being in communication with said bottom portion of said catalytic downflow reactor and said bottom portion of said upflow riser regenerator and comprising:
- (i) a horizontal elongated vessel having a body comprising a top having a center line, a first imperforate sidewall, a bottom and a perforate second side wall for penetration of a hydrocarbon product outlet withdrawal conduit, said top of said vessel body communicating with said catalytic downflow reactor to form a point of communication at a location off center from the center line of said top of said vessel as defined by a vertical plane through the diameter of said horizontal body, said point of communication being sufficient to provide passage of an admixture of spent catalyst and hydrocarbon products in a downward direction into said elongated vessel;
- (ii) a downcomer elongated relatively vertical conduit interconnecting said vessel bottom at the relatively opposite extreme end of said vessel from said communication of said vessel with said catalytic downflow reactor for passage downward through said downcomer vertical conduit of a relatively minor amount of spent catalyst;
- (iii) a hydrocarbon product withdrawal conduit situated in said second side wall of said vessel beneath and to the side of said point of communication of said catalytic downflow reactor with said top of said vessel for the continuous removal of said hydrocarbon product after a secondary centrifugal separation from spent catalyst;
- (iv) an inclined slot solid dropout means interconnecting said bottom of said vessel at a position at least 90.degree. separated from said catalytic downflow reactor point of communication with said top of said vessel as measured by an angle around the horizontal circumference of said vessel where 360.degree. degrees equal one complete revolution around said circumference, said dropout means receiving spent catalyst by primary mass separation of spent catalysts from said hydrocarbon product by centrifugal acceleration of spent catalyst about said angle of at least 90.degree. degrees in said horizontal vessel, wherein spent catalyst is accelerated against said horizontal circumference to cause primary mass flow separation and to thereby pass the majority of spent catalyst through said inclined solid dropout means to said downcomer vertical conduit;
- (v) wherein said horizontal cyclonic separator and said catalytic downflow reactor are constructed to insure that the diameter of said hydrocarbon product withdrawal conduit is smaller than the diameter of said horizontal vessel and said off center ingress of said admixture of said hydrocarbon product and spent catalyst are constructed to develop a swirl ratio of greater than 0.2 defined by the tangential velocity of said hydrocarbon product across the cross section of said catalytic downflow reactor divided by the superficial axial velocity of fluid through the cross section of said hydrocarbon product withdrawal conduit to produce a vortex of hydrocarbon product with entrained minor quantities of spent catalyst in a helical path extending from said imperforate wall opposite said hydrocarbon product withdrawal conduit to cause said secondary centrifugal separation and disengagement of a minor amount of entrained spent catalyst from said helical hydrocarbon product and thereby passage of a disengaged minor amount of disentrained spent catalyst to the point of interconnection of said vessel with said downcomer vertical conduit to pass disengaged and separated spent catalyst through said downcomer conduit to a stripping zone;
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- (vi) a stripping zone communicating with said downcomer vertical conduit and said bottom portion of said upflow riser regenerator, said stripping zone comprising a dense bed of spent catalyst received from both 1) said primary mass flow separation via said inclined slot solid dropout means and 2) said secondary centrifugal separation via said downcomer vertical conduit, wherein stripping gas is passed to said stripping zone by means of a stripping gas inlet means and wherein said helical flow path of said hydrocarbon product material extending from said second side wall to said hydrocarbon product material withdrawal outlet prohibits at least a portion of stripping gas from passing upward through said downcomer vertical conduit and into said horizontal vessel;
- (d) a connection separation means communicating with said top of said upflow riser regenerator and said top of said catalytic downflow reactor to separate regenerated catalyst, derived from said upflow riser regenerator, from spent oxidation gases, said connection separation means providing a relatively dense phase of catalyst intermediate said top of said catalytic downflow reactor and said top of said upflow regenerator;
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- (e) a pressure reduction means to attain a higher pressure in said relatively dense phase in said connection separation means immediately upstream of said catalytic downflow reactor compared with the pressure in said top portion of said catalytic downflow reactor.
10 more elements
An apparatus for the continuous conversion of a hydrocarbon feed material to a hydrocarbon product material having smaller molecules which comprises:
- (a) an upflow riser regenerator having a top and bottom portion and a spent catalyst and regeneration gas inlet in said bottom for entry of spent catalyst having deactivating coke deposited thereon and an oxygen-containing regeneration gas, wherein said upflow riser regenerator has a first relatively dense phase of regenerating catalyst in said bottom portion thereof and a relative dilute phase of regenerating catalyst in said top portion thereof;
- (b) an elongated catalytic hydrocarbon downflow reactor having a length of not more than the height of said upflow riser regenerator for converting said hydrocarbons therein to said hydrocarbons of smaller molecules and a hydrocarbon feed inlet at an upper extremity of said reactor;
- (c) a cyclone stripping zone communicating with said upflow riser regenerator and a second horizontal cyclone separator, possessed with a stripping fluid entry means for entry of a stripping fluid to said cyclone stripping zone;
- (d) a first horizontal cyclone separation zone for separation of regenerated catalyst and spent oxidation gas intermediate said top portion of said upflow riser regenerator and said top portion of said hydrocarbon catalytic downflow reactor and having a second relatively dense phase of regenerated catalyst therebeneath;
- (e) a second horizontal cyclone separation zone for separation of spent catalyst and hydrocarbon product intermediate said bottom of said downflow reactor and said upflow riser regenerator comprising:
- (i) a horizontal elongated vessel having a body comprising a top having a center line, a first imperforate sidewall, a bottom and a perforate second side wall for penetration of a hydrocarbon product outlet withdrawal conduit, said top of said vessel body communicating with said catalytic downflow reactor to form a point of communication at a location off center from the center line of said top of said vessel as defined by a vertical plane through the diameter of said horizontal body, said point of communication being sufficient to provide passage of an admixture of spent catalyst and said hydrocarbon products in a downward direction into said elongated vessel;
- (ii) a downcomer elongated relatively vertical conduit interconnecting said vessel bottom at the relatively opposite extreme end of said vessel from said communication of said vessel with said catalytic downflow reactor for passage downward through said downcomer vertical conduit of a relatively minor amount of spent catalyst;
- (iii) a hydrocarbon product withdrawal conduit situated in said second side wall of said vessel beneath and to the side of said point of communication of said catalytic downflow reactor with said top of said vessel for the continuous removal of hydrocarbon product after a secondary centrifugal separation from spent catalyst;
- (iv) an inclined slot solid dropout means interconnecting said bottom of said vessel at a position at least 90.degree. separated from said catalytic downflow reactor point of communication with said top of said vessel as measured by an angle around the horizontal circumference of said vessel where 360.degree. degrees equal one complete revolution around said circumference, said dropout means receiving spent catalyst by primary mass separation of spent catalysts from said hydrocarbon product by centrifugal acceleration of said spent catalyst about said angle of at least 90.degree. degrees in said horizontal vessel, wherein spent catalyst is accelerated against said horizontal circumference to cause primary mass flow separation and to thereby pass the majority of spent catalyst through said inclined solid dropout means to said downcomer vertical conduit;
- (v) wherein said horizontal vessel and said catalytic downflow reactor are constructed to insure that the diameter of said hydrocarbon product withdrawal conduit is smaller than the diameter of said horizontal vessel and said off center ingress of said admixture of said hydrocarbon product and spent catalyst are constructed to develop a swirl ratio of greater than 0.2 defined by the tangential velocity of hydrocarbon product across the cross section of said catalytic downflow reactor divided by the superficial axial velocity of fluid through the cross section of said hydrocarbon product withdrawal conduit to produce a vortex of hydrocarbon product with entrained minor quantities of spent catalyst in a helical path extending from said imperforate wall opposite said hydrocarbon product withdrawal conduit to cause said secondary centrifugal separation and disengagement of said minor amount of entrained spent catalyst from the helical hydrocarbon product and thereby passage of the disengaged minor amount of disentrained spent catalyst to the point of interconnection of said vessel with said downcomer vertical conduit to pass disengaged and separated spent catalyst through said downcomer conduit to a stripping zone;
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- (vi) a stripping zone communicating with said downcomer vertical conduit and said bottom portion of said upflow riser regenerator, said stripping zone comprising a dense bed of spent catalyst received from both (1) said primary mass flow separation via said inclined slot solid dropout means and (2) said secondary centrifugal separation via said downcomer vertical conduit, wherein stripping gas is passed to said stripping zone by means of a stripping gas inlet means and wherein said helical flow path of hydrocarbon product material extending from said second side wall to said hydrocarbon product material withdrawal outlet prohibits at least a portion of stripping gas from passing upward through said downcomer vertical conduit and into said horizontal vessel;
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- (f) a pressure differential means communicating with said second relatively dense bed of regenerated catalyst in said first horizontal cyclone to insure passage of regenerated catalyst from said second relatively dense bed of regenerated catalyst to said downflow reactor, wherein the pressure at the dense bed side of said pressure differential means being higher than the pressure on the hydrocarbon catalytic downflow reactor side of said pressure differential valve means.
11 more elements
Dependencies are inferred from the claim text.