Process and apparatus for fluid bed catalytic cracking
First Claim
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1. A process for catalytically cracking a liquid hydrocarbon charge in a fluidized bed reaction zone having an upper and lower part wherein the charge and the catalyst flow co-currently in a downward direction, and for regenerating the catalyst in first and second regeneration zones, said process comprising:
- injecting the liquid charge at the upper part of the reaction zone through at least one line which is subdivided into a plurality of substantially vertical first ducts with each of said first ducts being provided at its lower end with spray means for dispensing the liquid charge as droplets, introducing into an enclosure located within the upper part of the reaction zone catalyst particles having a temperature which is in a range from 600°
to 950°
C., the catalyst particles being introduced through at least one second duct into the enclosure so as to define a catalyst fluidized bed in said enclosure,circulating a gas through said fluidized bed so as to downwardly drive the catalyst particles of the fluidized bed through a plurality of substantially vertical third ducts thereby introducing the catalyst particles into the reaction zone itself, each vertical first duct being coaxial with one of the third ducts, each means for spraying the liquid charge being juxtaposed with an upper end of said third duct, so as to obtain in said third duct a flow of liquid charge and entrained catalyst particles in order to completely vaporize the liquid charge and intimately admix the charge with the catalyst particles,maintaining contact in said reaction zone between the liquid charge and the catalyst, with a residence time of the charge from 0.1 to 10 seconds and at a temperature in the range of 450°
-700°
C. to produce a reaction effluent stream,increasing the velocity of the catalyst and the reaction effluent in the lower part of the reaction zone, said lower part being funnel shaped and convergingdownwardly at a half apex angle ranging from about 5 to 30°
,separating 50 to 90% of the catalyst particles from the reaction effluent stream in a generated spiral within at least one first separation zone having an inlet and outlet and having a residence time lower than one second, the velocity of the gaseous portion of the reaction effluent at the inlet of said first separation zone being from 10 to 40 meters per second so as to produce a helical flow of vapor without reversal of the generated spiral, with the major part of the remaining catalyst particles being driven along with the gaseous effluent and then being separated from the reaction effluent within at least one second separation zone which includes the reversal of a spiral stream generated by the injection of the gaseous flow into said second separation zone,removing the major part of the hydrocarbons from the catalyst particles by the introduction of a stripping gas,conveying the catalyst particles upwardly through a fourth duct to a first fluidized bed regeneration zone by means of a first carrier gas,performing a first catalyst regeneration step, within said first regeneration zone at a temperature T1 ranging from about 500°
to 750°
C., with a fluidizing gas which comprises oxygen or a molecular oxygen-containing gas, so as to cause the combustion of at least 90% of the hydrogen and so as to oxidize 10-60% by weight of the carbon present on the catalyst,removing the major part of the gases from the first regeneration zone,withdrawing the partially regenerated catalyst from said first regeneration zone, feeding it upwardly through a first transfer line, by means of a second carrier gas comprising a molecular oxygen-containing gas to a lower part of a second regeneration zone, the second regeneration zone having the shape of a substantially vertical and elongate tube having a length L, and diameter φ
, whose ratio L/O ranges from 3 to 90, the catalyst being further regenerated in the second regeneration zone by being treated with the second carrier gas at temperature T2 from 650°
to 1000°
C., with T2 being higher than T1, in order to obtain a regenerated catalyst containing no more than 0.04% by weight of coke, the catalyst having this been driven upwardly through the second regeneration zone by means of said second carrier gas, andwithdrawing from the second regeneration zone a gas-catalyst mixture, separating the catalyst particles from the gases and feeding these regenerated particles, which have a temperature from 600°
to 950°
C., into said at least one second duct.
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Abstract
A fluid bed catalytic apparatus and process for cracking a hydrocarbon charge and regenerating the catalyst where hot particles are contacted at the top of the cracking zone (1) with the sprayed liquid charge to be treated and thus produce (a) the vaporization of the charge in lines 10 and (b) an intimate charge-catalyst particles mixture. The catalyst particles are then withdrawn from the lower part of the cracking reactor (1), separated from the reaction effluent, stripped in reactor (17) and successively subjected to two regeneration steps, respectively in zones (22) and (37), zone (37) being a tubular reactor where the catalyst particles are driven upwardly by a carrying gas.
16 Citations
17 Claims
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1. A process for catalytically cracking a liquid hydrocarbon charge in a fluidized bed reaction zone having an upper and lower part wherein the charge and the catalyst flow co-currently in a downward direction, and for regenerating the catalyst in first and second regeneration zones, said process comprising:
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injecting the liquid charge at the upper part of the reaction zone through at least one line which is subdivided into a plurality of substantially vertical first ducts with each of said first ducts being provided at its lower end with spray means for dispensing the liquid charge as droplets, introducing into an enclosure located within the upper part of the reaction zone catalyst particles having a temperature which is in a range from 600°
to 950°
C., the catalyst particles being introduced through at least one second duct into the enclosure so as to define a catalyst fluidized bed in said enclosure,circulating a gas through said fluidized bed so as to downwardly drive the catalyst particles of the fluidized bed through a plurality of substantially vertical third ducts thereby introducing the catalyst particles into the reaction zone itself, each vertical first duct being coaxial with one of the third ducts, each means for spraying the liquid charge being juxtaposed with an upper end of said third duct, so as to obtain in said third duct a flow of liquid charge and entrained catalyst particles in order to completely vaporize the liquid charge and intimately admix the charge with the catalyst particles, maintaining contact in said reaction zone between the liquid charge and the catalyst, with a residence time of the charge from 0.1 to 10 seconds and at a temperature in the range of 450°
-700°
C. to produce a reaction effluent stream,increasing the velocity of the catalyst and the reaction effluent in the lower part of the reaction zone, said lower part being funnel shaped and converging downwardly at a half apex angle ranging from about 5 to 30°
,separating 50 to 90% of the catalyst particles from the reaction effluent stream in a generated spiral within at least one first separation zone having an inlet and outlet and having a residence time lower than one second, the velocity of the gaseous portion of the reaction effluent at the inlet of said first separation zone being from 10 to 40 meters per second so as to produce a helical flow of vapor without reversal of the generated spiral, with the major part of the remaining catalyst particles being driven along with the gaseous effluent and then being separated from the reaction effluent within at least one second separation zone which includes the reversal of a spiral stream generated by the injection of the gaseous flow into said second separation zone, removing the major part of the hydrocarbons from the catalyst particles by the introduction of a stripping gas, conveying the catalyst particles upwardly through a fourth duct to a first fluidized bed regeneration zone by means of a first carrier gas, performing a first catalyst regeneration step, within said first regeneration zone at a temperature T1 ranging from about 500°
to 750°
C., with a fluidizing gas which comprises oxygen or a molecular oxygen-containing gas, so as to cause the combustion of at least 90% of the hydrogen and so as to oxidize 10-60% by weight of the carbon present on the catalyst,removing the major part of the gases from the first regeneration zone, withdrawing the partially regenerated catalyst from said first regeneration zone, feeding it upwardly through a first transfer line, by means of a second carrier gas comprising a molecular oxygen-containing gas to a lower part of a second regeneration zone, the second regeneration zone having the shape of a substantially vertical and elongate tube having a length L, and diameter φ
, whose ratio L/O ranges from 3 to 90, the catalyst being further regenerated in the second regeneration zone by being treated with the second carrier gas at temperature T2 from 650°
to 1000°
C., with T2 being higher than T1, in order to obtain a regenerated catalyst containing no more than 0.04% by weight of coke, the catalyst having this been driven upwardly through the second regeneration zone by means of said second carrier gas, andwithdrawing from the second regeneration zone a gas-catalyst mixture, separating the catalyst particles from the gases and feeding these regenerated particles, which have a temperature from 600°
to 950°
C., into said at least one second duct. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. An apparatus for performing a catalytic cracking and catalyst regeneration process comprising:
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a first substantially vertical elongate reactor having an upper and lower part, and a reservoir defined above a horizontal wall located within the upper part, at least one first inlet line for admission of a liquid charge into the upper part of said first reactor, each of said first lines being subdivided into a plurality of substantially vertical first ducts, each first duct being provided at its lower end with a first nozzle for spraying said charge, at least two substantially vertical second inlet lines for introducing the catalyst particles into said reservoir, at least one distributor of a gaseous fluid, located above said horizontal wall, a plurality of catalyst particles discharge tubes connecting said reservoir to said first reactor, said discharge tubes being arranged so that each of the first ducts is coaxial with one of the discharge tubes and so that each first nozzle is located in the vicinity of the upper end of a discharge tube, with all of the first nozzles, first ducts and discharge tubes thus defining a contact and mixing zone for the liquid charge with the catalyst, with the lower part of the reactor including a bottom portion comprising at least one funnel which converges downwardly and has a half apex angle which is in the range from about 5°
to 30°
,means defining at least one primary separation zone located beneath the funnel including at least one cyclone separator and at least one first outlet line for the removal of the catalyst particles from said primary separation zone, means defining at least one secondary separation zone wherein the reaction effluent is separated from the remaining catalyst particles, including at least one second outlet line for the removal of catalyst particles from said secondary separation zone and at least one third outlet line for the removal of the reaction effluent, means for stripping the catalyst particles by means of a gas introduced through at least one stripping gas inlet line, said means being fed with catalyst through said first and second outlet lines, and a first conduit for conveying catalyst particles discharged from said stripping means, a first substantially vertical transfer line connected to said first conduit for lifting the catalyst particles supplied through said first conduit, by means of a lifting gas thus conveying the catalyst particles to the inside of a first regeneration vessel, the first regeneration vessel comprising means for supporting a catalyst bed, a regeneration gas feeding line, and means comprising at least one cyclone for separating the gases from the catalyst particles, a second duct for discharging gases and a third duct for withdrawing the catalyst from the first regeneration vessel, a second conduit communicating with said third duct for flowing the catalyst downwardly, a second vertical ascending catalyst transfer line connected at a lower end to said second conduit and also to a lifting gas inlet, a second substantially vertical tubular reactor for catalyst regeneration, having a length, L, and diameter, 0, whose ratio L/O ranges from 3 to 90, said second reactor including at least one second nozzle for injecting a regeneration gas, wherein said second reactor is connected to an upper end of said second transfer line, a third conduit for discharging a gas-catalyst mixture from said second reactor and, a first means for separating the catalyst from the gases, the first separation means comprising at least two cyclone separators, and a fourth conduit for conducting the catalyst from said first separation means into said second inlet lines. - View Dependent Claims (9, 10, 11, 12, 13, 14, 15, 16, 17)
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Specification
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Current AssigneeInstitut Francais Du Petrole
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Original AssigneeInstitut Francais Du Petrole
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InventorsGaltier, Pierre, Busson, Christian
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Primary Examiner(s)Richman, Barry S.
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Assistant Examiner(s)Johnson, William R.
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Application NumberUS06/762,073Time in Patent Office781 DaysField of Search422/140, 422/144, 422/145, 422/147, 208/113, 208/120, 208/148, 208/161, 208/164, 34/10, 34/57 AUS Class Current208/113CPC Class CodesC10G 11/18 according to the "fluidised...
