CA1320924C - Heavy oil catalytic cracking - Google Patents
Heavy oil catalytic crackingInfo
- Publication number
- CA1320924C CA1320924C CA000593136A CA593136A CA1320924C CA 1320924 C CA1320924 C CA 1320924C CA 000593136 A CA000593136 A CA 000593136A CA 593136 A CA593136 A CA 593136A CA 1320924 C CA1320924 C CA 1320924C
- Authority
- CA
- Canada
- Prior art keywords
- catalyst
- temperature
- stripping
- riser
- regenerator
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
Links
Classifications
-
- C—CHEMISTRY; METALLURGY
- C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
- C10G—CRACKING HYDROCARBON OILS; PRODUCTION OF LIQUID HYDROCARBON MIXTURES, e.g. BY DESTRUCTIVE HYDROGENATION, OLIGOMERISATION, POLYMERISATION; RECOVERY OF HYDROCARBON OILS FROM OIL-SHALE, OIL-SAND, OR GASES; REFINING MIXTURES MAINLY CONSISTING OF HYDROCARBONS; REFORMING OF NAPHTHA; MINERAL WAXES
- C10G11/00—Catalytic cracking, in the absence of hydrogen, of hydrocarbon oils
- C10G11/14—Catalytic cracking, in the absence of hydrogen, of hydrocarbon oils with preheated moving solid catalysts
- C10G11/18—Catalytic cracking, in the absence of hydrogen, of hydrocarbon oils with preheated moving solid catalysts according to the "fluidised-bed" technique
-
- C—CHEMISTRY; METALLURGY
- C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
- C10G—CRACKING HYDROCARBON OILS; PRODUCTION OF LIQUID HYDROCARBON MIXTURES, e.g. BY DESTRUCTIVE HYDROGENATION, OLIGOMERISATION, POLYMERISATION; RECOVERY OF HYDROCARBON OILS FROM OIL-SHALE, OIL-SAND, OR GASES; REFINING MIXTURES MAINLY CONSISTING OF HYDROCARBONS; REFORMING OF NAPHTHA; MINERAL WAXES
- C10G11/00—Catalytic cracking, in the absence of hydrogen, of hydrocarbon oils
- C10G11/14—Catalytic cracking, in the absence of hydrogen, of hydrocarbon oils with preheated moving solid catalysts
- C10G11/18—Catalytic cracking, in the absence of hydrogen, of hydrocarbon oils with preheated moving solid catalysts according to the "fluidised-bed" technique
- C10G11/187—Controlling or regulating
Abstract
HEAVY OIL CATALYTIC CRACKING
ABSTRACT
A fluid catalytic cracking process and apparatus is described which includes a high temperature stripper (hot stripper) to control the carbon level and sulfur on spent catalyst, followed by catalyst cooling to control the regeneration inlet temperature.
The high temperature stripper operates at a temperature between 55°C
(100°F) above the temperature of a catalyst-hydrocarbon mixture exiting a riser and 816°C (1500°F). The regenerator inlet temperature is controlled to obtain the desired regeneration temperature 9 regenerator outlet temperature, and degree of regeneration. The regenerator is maintained at a temperature between 55°C (100°F) above that of the catalyst in the high temperature stripper and 871°C (1600°F). The present invention has the advantage that it separates hydrogen from catalyst to eliminate hydrothermal degradation, and separates sulfur from catalyst as hydrogen sulfide and mercaptans which are easy to scrub. The catalyst cooler enables the regenerator and high temperature stripper to be run independently at respective desired temperatures.
ABSTRACT
A fluid catalytic cracking process and apparatus is described which includes a high temperature stripper (hot stripper) to control the carbon level and sulfur on spent catalyst, followed by catalyst cooling to control the regeneration inlet temperature.
The high temperature stripper operates at a temperature between 55°C
(100°F) above the temperature of a catalyst-hydrocarbon mixture exiting a riser and 816°C (1500°F). The regenerator inlet temperature is controlled to obtain the desired regeneration temperature 9 regenerator outlet temperature, and degree of regeneration. The regenerator is maintained at a temperature between 55°C (100°F) above that of the catalyst in the high temperature stripper and 871°C (1600°F). The present invention has the advantage that it separates hydrogen from catalyst to eliminate hydrothermal degradation, and separates sulfur from catalyst as hydrogen sulfide and mercaptans which are easy to scrub. The catalyst cooler enables the regenerator and high temperature stripper to be run independently at respective desired temperatures.
Description
1~2~92~
~AVY OIL CATALY~IC CRAC~ING
This invention is concerned with a fluidized catalytic cracking process wherein coked deactivated catalyst is subject to high temperature stripping to control the carbon ~evel on spent catalyst. r~ore particularly, the concept employs a high temperature stripper to control the carbon level on the spent catalyst, followed by catalyst cooling to control the temperature of the catalyst to regeneration.
The field of catalytic cracking has undergone progressive development since 194n. The trend of development of the fluid catalytic cracking process has been to all riser cracking, use of zeolite-containing catalysts and heat balanced operation.
. Other major ~rends in fluid catalytic cracking processing have been modifications to the process to permit it to accommodate a wider range of feedstocks, in particular, feedstocks that contain more metals and sulfur than had previously been permitted in the feed to a fluid catalytic cracking unit.
Along with the development of process modifications and catalysts, which could accommodate these heavier, dirtier feeds, there has been a growing concern about the amount of sulfur contained in the feed that ends up as Sx in the regenerator flue gas. ~igher sulfur levels in the feed, combined with a more complete regeneration of the catalyst in the fluid cataly-tic cracking regenerator tends to increase the amount of SO contained in the regenerator flue gas. Some attempts have been made to minimize the amount of Sx discharged to the atmosphere through the flue gas hy providing agents to react with the Sx in the flue gas. These agents pass along with the regenerated catalyst back to the fluid catalytic cracking reactor, and then the reducing atmosphere releases the sulfur compounds as H2S. Suitable agents for this purpose have been described in U. S. Patent ~os. 4,071,436 and 3,834~031. Use of a cerium oxide agent for this purpose is shown in U. S. Patent ~To. 4,001,375.
.
.
132~9~
F-373~ --2~-Unfortunately, the conditions in most fluid catalytic cracking regenerators are not the best for Sx adsorption. The high temperatures encountered in modern fluid catalytic crackin~
regenerators (up to 870C (1600F)) tend to discourage Sx adsorption. Gne approach to overcome the problem of Sx in flue gas is to pass catalyst from a fluid catalytic cracking reactor to a long residence time steam stripper. After the long residence time steam stripping, the catalyst passes to the regenerator, as disclosed by U. S. Patent ~To. 4,4~1,1Q3 to Krambeck et al. ~lowever, this process preferably steam strips spent catalyst at 5noo~50OC
(~32 to lQ22F), which is not sufficient to remove some undesirable sulfur- or hydrogen-containing components. Furthermore, catalyst passing from a fluid catalytic cracking stripper to a fluid catalytic cracking regenerator contains hydrogen-containing components, such as coke, adhering thereto. This causes hydrothermal degradation when the hydrogen reacts with oxygen in ~he regenerator to form water.
U. S Patent ~!o. 4,336,160 to ~ean et al atten~pts to reduce hydrothermal degradation by staged regeneration. ~owever, the flue gas from both stages of regeneration contains ~x which is ; difficult to clean.
Another need of the prior art is to provide improved means for controlling fluid catalytic cracking regeneration temperature.
Improved regenerator temperature control is desirable, because regenerator -temperatures above 871C (1600F) can deactivate fluid cracking catalyst. Typically, the temperature is controlled by adjusting the CO/CC2 ratio produced in the regenerator. This control works on the principle that production of C0 produces less heat than production of C02. I~owever, in some cases, this control is insufficient.
It would be desirable to separate hydrogen from catalyst to eliminate hydrothermal degradation. It would be further advantageous to remove sulfur~containing compounds prior to ~32~2~
F-3734 ~
regeneration to prevent Sx from passing into the regenerator flue gas. Also, it would be advantageous to hetter control regenerator temperature.
U. S. Paten~ ~o. ~,353,812 to Lomas et al discloses cooling catalyst from a regenerator by passing it through the shell side of a heat-exchanger with a cooling medium through the tube side. The cooled catalyst is recycled to the regeneration zone. This process is disadvantageous, in that it does not control the temperature of catalyst from the reactor to the regenerator.
The prior art also includes fluid catalytic cracking ~r processes which utilize dense or dilute phase regenerated fluid catalyst heat removal zones or heat-exchangers that are remote from, and external to, the regenerator vessel to cool hot regenerated catalyst for return to the regenerator. Fxamples of such processes are found in U. S. Patent 1~70s. 2,970,117 to Harper; 2,873,175 to Owens; 2,~62,798 to ~cKinney; 2,5~6,7~ to Watson et al, 2,515,156 to Jahnig et al; 2,~92,9~8 to ~erger; and 2,506,123 to ~'atson. The processes disclosed in these patents have the disadvantage that the regenerator operating temperature is affected with the temperature Z0 of catalyst from the stripper to the regenerator.
Accordinglyg the present invention comprises a fluid catalytic cracking process and apparatus which employs a high temperature stripper, followed by cooling of the stripped catalyst to control a regenerator inlet temperature.
The present invention provides a process for controlling ~;~ the fluid catalytic cracking of a feedstock containing hydrocarbons, comprising the steps of:
passing a mixture comprising catalyst and the feedstock through a riser conversion zone under fluid catalytic cracking conditions to crack the feedstock;
passing the mixture, having a riser exit temperature, from the riser into a fluid catalytic cracking reactor vessel;
separating a portion of catalyst from the mixture, with the remainder of the mixture forming a reactor vessel gaseous stream;
F-373~ -74-._ 132~92~
heating the separated catalyst portion by combining the separated catalyst portion with a portion of regenerated catalyst from a fluid catalytic cracking regenerator vessel to form combined catalyst;
stripping the combined catalyst, by contact with a stripping gas stream, at a stripping temperature between 55C
(lQ0F) above the riser exit temperature and 816C (1500F), the regenerated catalyst portion having a temperature between 55C
(lQ0F) above the stripping temperature and ~71C (16Q0F~ prior -to heating the separated catalyst;
.. cooling the stripped catalyst, prior to passing it into the regenerator vessel, to a temperature sufficient to cause the regenerator vessel to be maintained at a temperature between 55C
~ (100F~ above the stripping temperature and ~71~ (16nQF); and -~ 15 regenerating the cooled catalyst stream in the fluid catalytic cracking regenerator vessel by contact with an oxygen-containing stream at fluid catalytic cracking regeneration conditions.
The riser exit temperature is defined as the temperature of the catalyst-hydrocarbon mixture exiting from the riser. The riser -~ exit temperature may be at any suitable temperature. ~owever, a riser exit temperature of 482-593C (900 to 1100F) is preferred, and 538~566C (1000 to 1050F) is ~ost preferredO
~lore particularly the present invention provides a process for controlling the fluid catalytic cracking of a feedstock containing hydrocarbons and sulfur-containin~ compounds, comprising the steps of:
passing a ~ixture comprising catalyst and the feedstock through a riser conversion zone at fluid catalytic cracking conditions to crack the feedstock;
passing the mixture, having a riser exit temperature between 53~~566C (1000 and 105QF), from the riser conversion zone to a closed cyclone system located within a fluid catalytic cracking reactor vessel;
~32~
separating a portion of catalyst from the mixture in the closed cyclone system, with the remainder of the mixture forming a reactor vessel gaseous stream;heating the separated catalyst portion by combining the separated catalyst portion in the reactor vessel, with a portion of regenerated catalyst from a fluid catalytic cracking regenerator vessel to form combined catalyst;
stripping the combined catalyst, by contact with a stripping gas stream in the reactor vessel, under stripping conditions comprising a stripping temperature between 83C (150F) above the riser exit temperature and 760C (1400F) and a residence .. ti~e of a gaseous stream from 0.5 to 5 seconds, the regenerated catalyst portion having a temperature between 83C (lSnF) above the stripping temperature and 871C (1600F~ prior to heating the ~ separated catalyst, wherein the separated catalyst portion comprises ; lS sulfur-containing compounds and hydrocarbons derived from thefeedstock, the stripping conditions are sufficient to separate 45 to ; 55% of the sulfur-containing compo~mds and 70 to 80~ of hydrogen ~, from the hydrocarbons in the separated catalyst portion of the combined catalyst to produce the gaseous stream, and the gaseous stream comprises stripping gas and molecular hydrogen, hydrocarbons and the sulfur-containing hydrocarbons separated from the separated catalyst;
cooling the stripped catalyst strea~ to between 2~-~3C
: (50 and 150F) below the s~ripping temperature by indirect heat-exchange with a heat-exchange medium in a heat~exchanger located outside the reactor vessel, causing the regenerator vessel to be maintained at a temperature between 83C (150F) above the ~:~ stripping temperature and 871C (1600~), thereby maintaining said regenerator vessel temperature independently of the stripping step temperature; and regenerating the cooled catalyst stream in the fluid catalytic cracking regenerator vessel, by contact with an oxygen~containing stream under fluid catalytic cracking regeneration conditions.
F-373~ 2~2~
In its apparatus respects, the present invention provides an apparatus for controlling the fluid catalytic cracking of a feedstock comprising hydrocarbons, comprising:
means defining a riser conversion zone through which a mixture comprising catalyst and the feedstock passes at fluid catalytic cracking conditions to crack the feedstock;
: a fluid catalytic cracking reactor vessel;
means for passing the mixture from the riser into the fluid catalytic cracking reactor vessel, the mixture having a riser exit temperature as it passes into the reactor vessel;
.. means for separating a portion of catalyst from the mixture, with the remainder of the mixture forming a reactor vessel : gaseous strea~;
means for heating the separated catalyst portion, comprising means for combinir-g the separated catalyst portion with a portion of regenerated catalyst to form combined catalyst;
: means for stripping the combined catalyst by contact with a stripping gas stream to form a stripped catalyst stream;
a fluid catalytic cracking regenerator vessel for producing the portion of regenerated catalyst; and ~: a heat~exchanger for cooling the stripped catalyst stream, the heat~exchan~er being located outside the reactor vessel, the fluid catalytic cracking regenerator vessel thereby regenerating the cooled catalyst stream hy contact with an oxygen-containing stream at fluid catalytic c-racking regenerator conditions.
: In its more particular apparatus aspects, the present invention provides an apparatus for controlling the fluid catalytic cracking of a feedstock comprising hydrocarbons and sulfur~containing compounds, comprising:
means defining a riser conversion zone through which a mixture comprising catalyst and the feedstock passes at fluid catalytic cracking conditions to cracX the feedstock;
a fluid catalytic cracking reactor vessel, ~3~a~2~
F~3734 --7--means for passing the mixture from the riser conversion zone to a closed cyclone system located within the fluid catalytic cracking reactor vessel, the mixture having a riser exit temperature hetween 538-566C (1000 and 1050F) as it passes from the riser to the closed cyclone system, the closed cyclone system including means : for separating a portion of catalyst from the mixture and forming a reactor vessel gaseous stream from the remainder of the mixture;
means for heating the separated portion of catalyst, comprising means for combining a portion of regenerated catalyst with the separated catalyst portion to form a comhined catalyst ;.n .. the reactor vessel;
~ means for stripping the combined catalyst by contact with i~; stripping gas in the reactor vessel, thereby maintaining the~: ~ combined catalyst in the means for stripping at a stripping ~ 15 temperature between 83C (150F) above the temperature of the ~ mixture exiting the riser and 760C (1400F) and a residence time of ~` gas in the means for stripping from n.5 to 5 seconds, the separated catalyst portion comprising hydrocarbons and sulfur-containing . compounds derived from the feedstock, the means for stripping thereby separating 45 to 55% of the sul~ur-containing compounds and 70 to 80% of hydrogen from the hydrocarbons in the separated catalyst portion;
`~ a stripped catalyst effluent conduit, attached to the reactor vessel for passing the stripped catalyst strea~ therethrough;
a fluid catalytic cracking regenerator vessel ~or producing the portion of regenerated catalyst at a temperature between 83C
(150F) above the stripping te~perature and 871C (1600F); and an indirect heat~exchanger attached to the reactor effluent conduit, whereby the indirect heat~exchanger is sufficiently sized ~or cooling the stripped catalyst stream to a te~perature between 28~83C (50 and 150F) below the stripping temperature, thereby causing the catalyst in the regenerator vessel to be maintained at a temperature between 83C (150F) above the stripping temperature and ~2~
F~373~
871C (1600F), causing the temperature of the catalyst in the regenerator vessel to be maintained independently of the stripping temperature, the regenerator vessel regenerating the cooled catalyst stream by contacting it with an oxygen~containing stream under fluid ca~alytic cracking regeneratlon conditions.
The present invention strips catalyst at a temperature higher than the riser exit temperature to separate hydrogen, as molecular hydrogen or hydrocarbons from the coke which adheres to catalyst, to eliminate hydrothermal degradation, which typically occurs when hydrogen reacts with oxygen in a flllid catalytic . cracking regenerator to form water. The high temperature stripper (hot stripper~ also removes sulfur from coked catalyst as hydrogen sulfide and ~ercaptans, which are easy to scrub. In contrast, removing sulfur from coked catalyst in a regenerator produces SOx, which passes into tlle regenerator flue gas and is more difficult to scrub. Furthermore, the high te~.perature stripper removes additional valuable hydrocarbon products to prevent burning -these hydrocarbons in the regenerator. ~n additional advantage of the high temperature stripper is that it quickly separates hydrocarbons from catalyst. If catalyst contacts hydrocarbons for too long a time at a temperature greater than or equal to 538C (1000F), then diolefins are produced which are undesirable for do~nstream processing 9 such as alkylation. However, the present invention allows a precisely controlled, short colltact time at 53~C (1000F) or greater to produce premium, unleaded gasoline with high selecti.Yity .
The heat~exchanger (catalyst cooler) controls regenerator temperature. This allows the hot stripper to run at a desired temperature to control sulfur and hydrogen without interfering with a desired regenerator temperature. It is desired to run the regenerator at least 55C (100F) hotter than the hot stripper.
However, the regenerator temperature should be kept below 871C
(1600F) to prevent deactivation of the catalys-t.
F~3734 9 ~ ~ ~2~2~
The drawing is a schematic representation of a high \ temperature stripper and catalyst cooler of the present invention.
The figure illustrates a fluid catalytic cracking system of the present invention. In the figure, a hydrocarbon feed passes from a hydrocarbon feeder l to the lower end of a riser conversion zone 4. Regenerated catalyst from a standpipe 102, having a control valve 104, is combined with the hydrocarbon feed in the riser ~, such that a hydrocarbon~catalyst mixture rises in an ascending dispersed stream and passes through a riser effluent conduit 6 into a first reactor cyclone ~. The riser exit temperature, ~efined as .. the temperature at which the mixture passes from the riser 4 to conduit 6, ranges between 482 and 593C (900~ and 1100F~, and ~; preferably between 538 and 566C (1000 and 1050F). The riser exit temperature is controlled by monitoring and adjusting the rates and temperatures of hydrocarbons and regenerated catalyst into the riser 4. ~iser effluent conduit 6 is attached at one end to the riser 4 and at its other end to the cyclone 8.
~ The first reactor cyclone 8 separates a portion of catalyst - from the catalyst-hydrocarbon ~ixture and passes this catalyst down a first reactor cyclone dipleg 12 to a stripping zone 30 located therebelow. The remaining gas and catalyst pass from the first reactor cyclone 8 through a gas effluent conduit 10. The conduit lQ
is provided with a connector 24 to allow for thermal expansion. The catalyst passes through the conduit lQ, then through a second reactor cyclone inlet conduit 22, and into a second reactor cyclone 14. The second cyclone 14 separates the stream to form a catalyst stream, which passes through a second reactor cyclone diple~ 18 to the stripping zone 30 located therebelow, and an overhead stream .The second cyclone overhead stream, which contains the remaining gas and catalyst, passes through a second cyclone gaseous effluent conduit 16 to a reactor overhead port 20. ~ases from the atmosphere of the reactor vessel 2 may pass through a reactor overhead conduit 22 into -the reactor overhead port 20. The gases ~ 3~2~
F~3734 ~ 107~
which exit the reactor 2 through the second cyclone gaseous effluent conduit 16 and the reactor overhead conduit 22 are combined and exit through the reactor overhead port 20. It will be apparent to those skilled in the art that although only one series connection of cyclones 8, 14 is shown in the embodiment, more than one series connection and/or more or less than two consecutive cyclones in series connection could be employed.
The mixture of catalyst and hydrocarbons passes through the first reactor cyclone overhead conduit lQ and the second reactor n cyclone inlet conduit 22 without entering the reactor vessel 2 ,. atmosphere. ~owever~ the connector 24 may provide an annular port to admit stripping gas from the reactor vessel 2 into the conduit 10 to aid in separating catalyst from hydrocarbons adhering thereto.
' The closed cyclone system and annular port is described more fully ; 15 in U. S. Patent ~o. 4,502,9~7 to lladdad et al.
The separated catalyst from cyclones 8, 14 pass through respective diplegs 12, 18 and are discharged therefrom after a suitable pressure is generated within the diplegs hy the buildup of the catalyst. The catalyst falls from the diplegs into a bed of catalyst 31 located in the stripping zone 3n. The first dipleg 12 is sealed by being extended into the catalyst bed 31. The second dipleg 18 is sealed by a trickle valve 19. The separated catalyst is contacted and combined with hot regenerated catalyst from -the regenerator 80 in the stripping zone 30. The regenerated catalyst has a temperature in the range between 55C (100F) above that of the stripping zone 30 and 871C (1600F) to heat the separated catalyst in bed 31. The regenerated catalyst passes from the regenerator 80 to the reactor vessel 2 throllgh a transfer line 106 attached at one end to the regenerator vessel 80 and at another end to the reactor vessel 2. The transfer line 106 is provided with a slide valve 108. Combining the separated catalyst ~ith the regenerated catalyst promotes the stripping at a temperature in the range between 55C (100~) above the riser exit temperature and ~3209~
816C (1500F). Preferably, the catalyst strippin~ zone operates at a temperature between R3C (150F) above the riser exit temperature ; and 760C (1400F).
The catalyst 31 in the stripping zone 30 is contacted at high temperature, discussed above,~ith a stripping gas, such as steam, flowing co~mtercurrently to the direction of flow of the catalyst. The stripping gas is introduced into the lower portion of the stripping zone 30 by one or more conduits 34 attached to a stripping gas header 36. The catalyst residence time in the stripping zone 30 ranges from 2.5 to 7 minutes. The vapor residence time in the catalyst stripping zone 30 ranges from 0.5 to 30 seconds, and preferably 0.5 to 5 seconds. The stripping zone 3Q
removes coke, sulfur and hydrogen from the separated catalyst which has heen combined with the regenerated catalyst. The sulfur is removed as hydrogen sulfide and mercaptans. The hydrogen is removed as ~olecular hydrogen, hydrocarbons, and hydrogen sulfide. ~ost preferably, the stripping zone 30 is ~aintained at temperatures between ~3C (150F) above the riser exit temperature, which are sufficient to reduce coke load to the re~enerator by at least ~0%, remove 70~80~ of the hydrogen as molecular hydrogen, light hydrocarbons and other hydrogen~containing compounds, and remove 45 to 55% of the sulfur as hydrogen sulfide and mercaptans, as well as a portion of nitrogen as ammonia and cyanides.
The catalyst stripping zone 30 may also be provided with trays (baffles) 32. The trays ~ay be disc~ and doughnut-shaped and may be perforated or unperforated.
Stripped catalyst passes through a stripped catalyst effluent conduit 38 to a ca~alyst cooler 40. The catalyst cooler 40 is a heat~exchanger which cools the stripped catalyst from the reactor vessel 2 to a temperature sufficient to maintain the regenerator vessel 80 at a temperature between 55C (100F) above the temperature of the stripping zone 30 and 871C (1600F).
Preferably, the catalyst cooler ~0 cools the stripped catalyst ~32~92~
stream to a temperature sufficient to control the regenerator vessel 8Q at a temperature to between 83C (150F) above the temperature of the stripping zone 30 and 871C (1600F). Most preferahlv, the stripped catalyst stream is cooled between 28 and R3C (50 and : 5 150F) below the stripping zone temperature, so long as the cooled catalyst temperature is at least 593C (1100F).
The catalyst cooler 40 is preferably an indirect : heat~exchanger located outside the reactor vessel 2. A
heat-exchange medium, such as liquid water (boiler feed water), passes throllgh a conduit 50, provided with a valve 54~ into a set of ~r tubes 48 within the catalyst cooler 40. The catalyst passes through the shell side 46 of the catalyst cooler 40. The catalyst cooler 40 is attached to an effluent conduit 42 provided with a slide valve 44. The cooled catalyst passes through the conduit 42 into a regenerator inlet conduit 60.
In the regenerator riser 60, air and cooled catalyst combine and pass upwardly through an air catalyst disperser 74 into a fast fluid bed 62. The fast fluid bed 62 is part of the regenerator vessel 80. In the fast fluid bed 62, combustible materials, such as coke which adheres to the cooled catalyst, are burned off the catalyst by contact with lift air. Air passes through an air supply line 66 ~hrough a control valve 68 and an air transfer line 68 to the regenerator inlet conduit 60. ~ptionally~
if the temperature of the cooled catalyst from the conduit 42 is less than 593C (1100F), a portion of hot regenerated catalyst from the standpipe 102 passes ~hrough a conduit 101, provided with a control valve 103, into the fast fluid bed 62. The fast fluid bed 62 contains a relatively dense catalyst bed 76. The air fluidizes the catalyst in bed 76, and subsequently transports the catalyst continuously as a dilute phase throu~h the regenerator riser R3.
The dilute ph.ase passes upwardly through the riser 83, through a radial arm 84 attached to the riser 83, and then passes downwardly to a second relatively dense bed of catalyst ~2 located within the regenerator vessel. 80.
F-3734 --13-~ 1 3 ~
The major portion of catalyst passes downwardly through the radial arms 84, while the gases and remaining catalyst pass into the atmosphere of the regenerator vessel 80. The gases and remaining catalyst then pass through an inlet conduit 89 and into the first regenerator cyclone 86. The first cyclone 86 separates a portion of catalyst and passes it through a first dipleg 90, while remaining catalyst and gases pass through an overhead conduit 88 into a second ; regenerator cyclone 92. The second cyclone 92 separates a ~ortion of catalyst and passes the separated portion through a second dipleg 96 having a trickle valve 97, with the remaining gas and catalyst .. passing through a second overhead conduit 9~ into a regenerator vessel plenum chamber 9~. A flue gas stream 110 exits from the regenerator plenum chamber 98 through a regenerator flue gas conduit 100 .
The regenerated catalyst settles -to form the bed ~2, which is dense compared to the dilute cata]yst passing through the riser 83. The regenerated catalyst 'ned 82 is at a substantially higher temperature than the stripped catalyst from the stripping zone 30, due to the coke burning which occurs in the regenerator 80. The catalyst in bed 82 is at least 55C (100F) hotter than the temperature of the strippin~ zone 30, preferably at least 83C
(150F) hotter than the temperature of the stripping zone 30. The regenerator temperature is, at most, 871C (1600F) to prevent deactivating the catalyst. Coke burning occurs in the regenerator inlet conduit 60, as well as the fast fluid bed 62 and riser 83.
Optionally, air may also be passed from the air supply line 64 to an air transfer line 70, provided with a control valve 72, to an air header 78 located in the regenerator 80. The regenerated catalyst then passes from the relatively dense bed 82 through the conduit 106 to the stripping zone 30 to provide heated catalyst for the stripping zone 30.
Any conventional fluid catalytic cracking catalyst can be used in the present invention. ~Tse of zeolite catalysts in an 132~2~
F-3734 --14 ~
amorphous base is preferred. Many suitable catalysts are discussed in U. S. Patent ~To. 3,926,778 to Owen et al.
One example of a process which can be conducte~ in accordance with the present invention begins with a 343 to 593C
(650 to 1100F) boiling poin-t hydrocarbon feedstock ~hich passes into a riser conversion zone 4, where it combines with hot regenerated catalyst at a temperature of about 815C (1500F) from a catalyst standpipe 102 to form a catalyst~hydrocarbon mixture. The catalyst~hydrocarbon mixture passes upwardly through the riser conversion zone 4 and into a riser effluent conduit 6 at a riser .. exit temperature of about 538C (1000F). The catalyst passes from the conduit 6 into -the first reactor cyclone 8, where a portion of catalyst is separated from the mixture and drops through a dipleg 12 to a bed of catalyst 31 contained within a stripping zone 30 therebelow. The stripring zone 30 operates at about 704C
(1300F). The remainder of the ~ixture passes upwardly through the first overhead conduit lQ into a second reactor cyclone 14. T,he second cyclone 14 separates a portion of catalyst from the first cyclone overhead stream and passes the separated catalyst down the second dipleg 18. The remaining solids and gases pass upwardly as a second cyclone overhead stream through conduit 16 into the reactor vessel overhead port 20.
In the stripping zone 30, the catalyst from diplegs 12, 18 combines with catalyst from regenerator 80, which passes through a conduit 106 and is stripped by contact with steam from a steam header 36. me regenerated catalyst from the conduit 106 is at a temperature of about ~15C (1500F) and Frovides heat to maintain the stripping zone 30 at about 704C (1300F). The stripped catalyst passes through a conduit 38 into a catalyst cooler 40 at a temperature of about 704C (1300F). The catalyst cooler 40 cools the 704C (1300F) catalyst to about 621C (1150F). The cooling occurs by indirect heat~exchange o~ the hot stripped catalyst with boiler feed water, which passes through a conduit SO to form steam which exits through a conduit 52.
F-3734 ~15-- ~32~2~
The cooled catalyst, at a temperature of about 621C
(1150F), combines with lift air from a conduit 66 in a regenerator inlet conduit 60 to form an aircatalyst mixture. The mixture passes upwardly through the conduit 60 into fast fluid hed 76. The catalyst continues upwardly from fast fluid bed 7fi through the regenerator riser 83 and into a regenerator vessel 80. The catalyst is then separated from gases by the radial arm 84, as wel] as cyclones 86 and 92, and passes downwardly through the regenerator to form a relatively dense bed R2. The coke adhering to the strip~ed catalyst burns in the conduit 60, the fast fluid bed 62, the riser .. ~3, and the regenerator vessel ~n. riue to the coke burning, the catalyst in bed 82 is heated to a temperature of about P,15C
(1500F). Catalyst bed ~2 then supplies catalyst for -the standpipe ' 102, which combines with the hydrocarbon feedstock. ~ed ~2 also provides catalyst for conduit 106 which passes to the stripping zone 30. Gaseous effluents pass through a first cyclone g6 and second cyclone 92 and leave the regenerator 80 as a flue gas stream 110 through a flue gas conduit lQ0.
Operating the stripping zone as a high temperature (hot) stripper, at a temperature between 55C (100F) above a riser exit temperature and 816C (1500~), has the advantage that it separates hydrogen, as molecular hydrogen as well as hydrocarbons, Erom catalyst. ~Iydrogen removal eliminates hydrothermal degradation, which typically occurs when hydrogen reacts with oxygen in a fluid catalytic cracking regenerator to form water. The hot stripper also removes sulfur from coked catalyst as hydrogen sulfide and mercaptans, which are easy to scrub. ~y removing sulfur from coked catalyst in the hot stripper, the hot stripper prevents formation of Sx in ~le regenerator. It is more difficult to remove Sx from regenerator flue gas than to remove hydrogen sulfide and mercaptans from a hot stripper effluent. The hot stripper enhances removal of hydrocarbons from spent catalyst, and thus prevents burning of valuable hydrocarbons in the regenerator. Furthermore, the hot F~3734 ~ 32~92~
stripper quickly separates hydrocarbons from catalyst to avoid overcracking.
Preferably the hot stripper is maintained at a temperature between 83C (150F) above a riser exit temperature and 760C
(14~0F) to reduce coke load to the regenerator by at least ~%, and strip away 70 to 80% of the hydrogen as molecular hydrogen, light hydrocarbons and other hydrogen-containing compounds. ~he hot stripper is also maintained within the desired temperature conditions to remove 45 to 55~ of the sulfur as hydrogen sulfide and mercaptans, as well as a portion of nitrogen as ammonia and cyanides.
This concept advances the development of a heavy oil (residual oil) catalytic cracker and high temperature cracking unit for conventional gas oils. The process combines the control of catalyst deactivation with controlled catalyst carbon contamination level and control of te~perature levels in the stripper and regenerator.
The hot s-tripper temperature controls the amount of carbon removed from the catalyst in the hot stripper. Accordingly, the hot stripper controls the amount of carbon (and hydrogen, sulfur) remaining on the catalyst to the regenerator. This residual carbon level controls the te~perature rise between the reactor stripper and the regenerator. The hot stripper also controls the hydrogen content of the spent catalyst sent to the regenerator as a function of residual carbon. Thus, the hot stripper controls the temperature and amount of hydrothermal deactivation of catalyst in the regenerator. This concept may be practiced in a ~ulti-sta~e, multi~temperature stripper or a single stage stripper.
Fmploying a hot stripper, to re~ove carbon on the catalyst, rather than a regeneration stage reduces air pollution, and allo~s all of the carbon made in the reaction to be burned to C02, if desired.
; The stripped catalyst is cooled (as a function of its carbon level) to a desired re~enerator inlet temperature to control :~2~
F~3734 ~17~
the degree of regeneration desired, in combination with the other variables of C0/CO2 ratio desired, the amount oE carbon burn~off desired, the catalyst recirculation rate from the regenerator to the hot stripper, and the degree of desulfurization/
denitrification/decarbonization desired in the hot stripper.
Increasing CO/C~2 ratio decreases the heat generated in the regenerator, and accordingly decreases the regenerator temperature.
~urning the coke, adhering to the catalyst in the regenerator, to C0 removes the coke, as would burning coke to CO2, but kurning to C0 produces less heat than burning to C02. The amount of carbon (coke) burn-off affects regenerator temperature, because greater carbon burn-off generates greater heat. The catalyst recirculation rate from the regenerator to the hot stripper affects regenerator ' temperature, because increasing the amount of hot catalyst rrom the regenerator to the hot stripper increases hot stripper temperature.
Accordingly, the increased hot stripper temperature removes increased amounts of coke so less coke need burn in the regenerator;
thus, regenerator temperature can decrease.
The catalyst cooler controls regenerator temperature, thereby allowing the hot stripper to be run at temperatures between 55C (100F) above a riser exit temperature to 816~C (1500F)~ which facilitate controlling sulfur and hydrogen, while allowing the regenerator to be run independently at temperatures at least lQ0F
hotter than the stripper, while preventing regenerator temperatures greater than 871C (1600F) which deactivate catalyst.
Use of the catalyst cooler on catalyst exiting the stripper also allows circulation of catalyst to the regenerator riser to increase catalyst density in the regenerator riser, while controlling the regenerator temperature. This reduces catalyst deactivation and provides additional control.
While specific embodiments of the method and apparatus aspects of the invention have heen shown and describedS it should be apparent that the many modifications can be made thereto without departing from the spirit and scope of the invention~ Accordingly, the invention is not limited by the foregoing description~ but is only limited by the scope of the claims appended thereto.
~AVY OIL CATALY~IC CRAC~ING
This invention is concerned with a fluidized catalytic cracking process wherein coked deactivated catalyst is subject to high temperature stripping to control the carbon ~evel on spent catalyst. r~ore particularly, the concept employs a high temperature stripper to control the carbon level on the spent catalyst, followed by catalyst cooling to control the temperature of the catalyst to regeneration.
The field of catalytic cracking has undergone progressive development since 194n. The trend of development of the fluid catalytic cracking process has been to all riser cracking, use of zeolite-containing catalysts and heat balanced operation.
. Other major ~rends in fluid catalytic cracking processing have been modifications to the process to permit it to accommodate a wider range of feedstocks, in particular, feedstocks that contain more metals and sulfur than had previously been permitted in the feed to a fluid catalytic cracking unit.
Along with the development of process modifications and catalysts, which could accommodate these heavier, dirtier feeds, there has been a growing concern about the amount of sulfur contained in the feed that ends up as Sx in the regenerator flue gas. ~igher sulfur levels in the feed, combined with a more complete regeneration of the catalyst in the fluid cataly-tic cracking regenerator tends to increase the amount of SO contained in the regenerator flue gas. Some attempts have been made to minimize the amount of Sx discharged to the atmosphere through the flue gas hy providing agents to react with the Sx in the flue gas. These agents pass along with the regenerated catalyst back to the fluid catalytic cracking reactor, and then the reducing atmosphere releases the sulfur compounds as H2S. Suitable agents for this purpose have been described in U. S. Patent ~os. 4,071,436 and 3,834~031. Use of a cerium oxide agent for this purpose is shown in U. S. Patent ~To. 4,001,375.
.
.
132~9~
F-373~ --2~-Unfortunately, the conditions in most fluid catalytic cracking regenerators are not the best for Sx adsorption. The high temperatures encountered in modern fluid catalytic crackin~
regenerators (up to 870C (1600F)) tend to discourage Sx adsorption. Gne approach to overcome the problem of Sx in flue gas is to pass catalyst from a fluid catalytic cracking reactor to a long residence time steam stripper. After the long residence time steam stripping, the catalyst passes to the regenerator, as disclosed by U. S. Patent ~To. 4,4~1,1Q3 to Krambeck et al. ~lowever, this process preferably steam strips spent catalyst at 5noo~50OC
(~32 to lQ22F), which is not sufficient to remove some undesirable sulfur- or hydrogen-containing components. Furthermore, catalyst passing from a fluid catalytic cracking stripper to a fluid catalytic cracking regenerator contains hydrogen-containing components, such as coke, adhering thereto. This causes hydrothermal degradation when the hydrogen reacts with oxygen in ~he regenerator to form water.
U. S Patent ~!o. 4,336,160 to ~ean et al atten~pts to reduce hydrothermal degradation by staged regeneration. ~owever, the flue gas from both stages of regeneration contains ~x which is ; difficult to clean.
Another need of the prior art is to provide improved means for controlling fluid catalytic cracking regeneration temperature.
Improved regenerator temperature control is desirable, because regenerator -temperatures above 871C (1600F) can deactivate fluid cracking catalyst. Typically, the temperature is controlled by adjusting the CO/CC2 ratio produced in the regenerator. This control works on the principle that production of C0 produces less heat than production of C02. I~owever, in some cases, this control is insufficient.
It would be desirable to separate hydrogen from catalyst to eliminate hydrothermal degradation. It would be further advantageous to remove sulfur~containing compounds prior to ~32~2~
F-3734 ~
regeneration to prevent Sx from passing into the regenerator flue gas. Also, it would be advantageous to hetter control regenerator temperature.
U. S. Paten~ ~o. ~,353,812 to Lomas et al discloses cooling catalyst from a regenerator by passing it through the shell side of a heat-exchanger with a cooling medium through the tube side. The cooled catalyst is recycled to the regeneration zone. This process is disadvantageous, in that it does not control the temperature of catalyst from the reactor to the regenerator.
The prior art also includes fluid catalytic cracking ~r processes which utilize dense or dilute phase regenerated fluid catalyst heat removal zones or heat-exchangers that are remote from, and external to, the regenerator vessel to cool hot regenerated catalyst for return to the regenerator. Fxamples of such processes are found in U. S. Patent 1~70s. 2,970,117 to Harper; 2,873,175 to Owens; 2,~62,798 to ~cKinney; 2,5~6,7~ to Watson et al, 2,515,156 to Jahnig et al; 2,~92,9~8 to ~erger; and 2,506,123 to ~'atson. The processes disclosed in these patents have the disadvantage that the regenerator operating temperature is affected with the temperature Z0 of catalyst from the stripper to the regenerator.
Accordinglyg the present invention comprises a fluid catalytic cracking process and apparatus which employs a high temperature stripper, followed by cooling of the stripped catalyst to control a regenerator inlet temperature.
The present invention provides a process for controlling ~;~ the fluid catalytic cracking of a feedstock containing hydrocarbons, comprising the steps of:
passing a mixture comprising catalyst and the feedstock through a riser conversion zone under fluid catalytic cracking conditions to crack the feedstock;
passing the mixture, having a riser exit temperature, from the riser into a fluid catalytic cracking reactor vessel;
separating a portion of catalyst from the mixture, with the remainder of the mixture forming a reactor vessel gaseous stream;
F-373~ -74-._ 132~92~
heating the separated catalyst portion by combining the separated catalyst portion with a portion of regenerated catalyst from a fluid catalytic cracking regenerator vessel to form combined catalyst;
stripping the combined catalyst, by contact with a stripping gas stream, at a stripping temperature between 55C
(lQ0F) above the riser exit temperature and 816C (1500F), the regenerated catalyst portion having a temperature between 55C
(lQ0F) above the stripping temperature and ~71C (16Q0F~ prior -to heating the separated catalyst;
.. cooling the stripped catalyst, prior to passing it into the regenerator vessel, to a temperature sufficient to cause the regenerator vessel to be maintained at a temperature between 55C
~ (100F~ above the stripping temperature and ~71~ (16nQF); and -~ 15 regenerating the cooled catalyst stream in the fluid catalytic cracking regenerator vessel by contact with an oxygen-containing stream at fluid catalytic cracking regeneration conditions.
The riser exit temperature is defined as the temperature of the catalyst-hydrocarbon mixture exiting from the riser. The riser -~ exit temperature may be at any suitable temperature. ~owever, a riser exit temperature of 482-593C (900 to 1100F) is preferred, and 538~566C (1000 to 1050F) is ~ost preferredO
~lore particularly the present invention provides a process for controlling the fluid catalytic cracking of a feedstock containing hydrocarbons and sulfur-containin~ compounds, comprising the steps of:
passing a ~ixture comprising catalyst and the feedstock through a riser conversion zone at fluid catalytic cracking conditions to crack the feedstock;
passing the mixture, having a riser exit temperature between 53~~566C (1000 and 105QF), from the riser conversion zone to a closed cyclone system located within a fluid catalytic cracking reactor vessel;
~32~
separating a portion of catalyst from the mixture in the closed cyclone system, with the remainder of the mixture forming a reactor vessel gaseous stream;heating the separated catalyst portion by combining the separated catalyst portion in the reactor vessel, with a portion of regenerated catalyst from a fluid catalytic cracking regenerator vessel to form combined catalyst;
stripping the combined catalyst, by contact with a stripping gas stream in the reactor vessel, under stripping conditions comprising a stripping temperature between 83C (150F) above the riser exit temperature and 760C (1400F) and a residence .. ti~e of a gaseous stream from 0.5 to 5 seconds, the regenerated catalyst portion having a temperature between 83C (lSnF) above the stripping temperature and 871C (1600F~ prior to heating the ~ separated catalyst, wherein the separated catalyst portion comprises ; lS sulfur-containing compounds and hydrocarbons derived from thefeedstock, the stripping conditions are sufficient to separate 45 to ; 55% of the sulfur-containing compo~mds and 70 to 80~ of hydrogen ~, from the hydrocarbons in the separated catalyst portion of the combined catalyst to produce the gaseous stream, and the gaseous stream comprises stripping gas and molecular hydrogen, hydrocarbons and the sulfur-containing hydrocarbons separated from the separated catalyst;
cooling the stripped catalyst strea~ to between 2~-~3C
: (50 and 150F) below the s~ripping temperature by indirect heat-exchange with a heat-exchange medium in a heat~exchanger located outside the reactor vessel, causing the regenerator vessel to be maintained at a temperature between 83C (150F) above the ~:~ stripping temperature and 871C (1600~), thereby maintaining said regenerator vessel temperature independently of the stripping step temperature; and regenerating the cooled catalyst stream in the fluid catalytic cracking regenerator vessel, by contact with an oxygen~containing stream under fluid catalytic cracking regeneration conditions.
F-373~ 2~2~
In its apparatus respects, the present invention provides an apparatus for controlling the fluid catalytic cracking of a feedstock comprising hydrocarbons, comprising:
means defining a riser conversion zone through which a mixture comprising catalyst and the feedstock passes at fluid catalytic cracking conditions to crack the feedstock;
: a fluid catalytic cracking reactor vessel;
means for passing the mixture from the riser into the fluid catalytic cracking reactor vessel, the mixture having a riser exit temperature as it passes into the reactor vessel;
.. means for separating a portion of catalyst from the mixture, with the remainder of the mixture forming a reactor vessel : gaseous strea~;
means for heating the separated catalyst portion, comprising means for combinir-g the separated catalyst portion with a portion of regenerated catalyst to form combined catalyst;
: means for stripping the combined catalyst by contact with a stripping gas stream to form a stripped catalyst stream;
a fluid catalytic cracking regenerator vessel for producing the portion of regenerated catalyst; and ~: a heat~exchanger for cooling the stripped catalyst stream, the heat~exchan~er being located outside the reactor vessel, the fluid catalytic cracking regenerator vessel thereby regenerating the cooled catalyst stream hy contact with an oxygen-containing stream at fluid catalytic c-racking regenerator conditions.
: In its more particular apparatus aspects, the present invention provides an apparatus for controlling the fluid catalytic cracking of a feedstock comprising hydrocarbons and sulfur~containing compounds, comprising:
means defining a riser conversion zone through which a mixture comprising catalyst and the feedstock passes at fluid catalytic cracking conditions to cracX the feedstock;
a fluid catalytic cracking reactor vessel, ~3~a~2~
F~3734 --7--means for passing the mixture from the riser conversion zone to a closed cyclone system located within the fluid catalytic cracking reactor vessel, the mixture having a riser exit temperature hetween 538-566C (1000 and 1050F) as it passes from the riser to the closed cyclone system, the closed cyclone system including means : for separating a portion of catalyst from the mixture and forming a reactor vessel gaseous stream from the remainder of the mixture;
means for heating the separated portion of catalyst, comprising means for combining a portion of regenerated catalyst with the separated catalyst portion to form a comhined catalyst ;.n .. the reactor vessel;
~ means for stripping the combined catalyst by contact with i~; stripping gas in the reactor vessel, thereby maintaining the~: ~ combined catalyst in the means for stripping at a stripping ~ 15 temperature between 83C (150F) above the temperature of the ~ mixture exiting the riser and 760C (1400F) and a residence time of ~` gas in the means for stripping from n.5 to 5 seconds, the separated catalyst portion comprising hydrocarbons and sulfur-containing . compounds derived from the feedstock, the means for stripping thereby separating 45 to 55% of the sul~ur-containing compounds and 70 to 80% of hydrogen from the hydrocarbons in the separated catalyst portion;
`~ a stripped catalyst effluent conduit, attached to the reactor vessel for passing the stripped catalyst strea~ therethrough;
a fluid catalytic cracking regenerator vessel ~or producing the portion of regenerated catalyst at a temperature between 83C
(150F) above the stripping te~perature and 871C (1600F); and an indirect heat~exchanger attached to the reactor effluent conduit, whereby the indirect heat~exchanger is sufficiently sized ~or cooling the stripped catalyst stream to a te~perature between 28~83C (50 and 150F) below the stripping temperature, thereby causing the catalyst in the regenerator vessel to be maintained at a temperature between 83C (150F) above the stripping temperature and ~2~
F~373~
871C (1600F), causing the temperature of the catalyst in the regenerator vessel to be maintained independently of the stripping temperature, the regenerator vessel regenerating the cooled catalyst stream by contacting it with an oxygen~containing stream under fluid ca~alytic cracking regeneratlon conditions.
The present invention strips catalyst at a temperature higher than the riser exit temperature to separate hydrogen, as molecular hydrogen or hydrocarbons from the coke which adheres to catalyst, to eliminate hydrothermal degradation, which typically occurs when hydrogen reacts with oxygen in a flllid catalytic . cracking regenerator to form water. The high temperature stripper (hot stripper~ also removes sulfur from coked catalyst as hydrogen sulfide and ~ercaptans, which are easy to scrub. In contrast, removing sulfur from coked catalyst in a regenerator produces SOx, which passes into tlle regenerator flue gas and is more difficult to scrub. Furthermore, the high te~.perature stripper removes additional valuable hydrocarbon products to prevent burning -these hydrocarbons in the regenerator. ~n additional advantage of the high temperature stripper is that it quickly separates hydrocarbons from catalyst. If catalyst contacts hydrocarbons for too long a time at a temperature greater than or equal to 538C (1000F), then diolefins are produced which are undesirable for do~nstream processing 9 such as alkylation. However, the present invention allows a precisely controlled, short colltact time at 53~C (1000F) or greater to produce premium, unleaded gasoline with high selecti.Yity .
The heat~exchanger (catalyst cooler) controls regenerator temperature. This allows the hot stripper to run at a desired temperature to control sulfur and hydrogen without interfering with a desired regenerator temperature. It is desired to run the regenerator at least 55C (100F) hotter than the hot stripper.
However, the regenerator temperature should be kept below 871C
(1600F) to prevent deactivation of the catalys-t.
F~3734 9 ~ ~ ~2~2~
The drawing is a schematic representation of a high \ temperature stripper and catalyst cooler of the present invention.
The figure illustrates a fluid catalytic cracking system of the present invention. In the figure, a hydrocarbon feed passes from a hydrocarbon feeder l to the lower end of a riser conversion zone 4. Regenerated catalyst from a standpipe 102, having a control valve 104, is combined with the hydrocarbon feed in the riser ~, such that a hydrocarbon~catalyst mixture rises in an ascending dispersed stream and passes through a riser effluent conduit 6 into a first reactor cyclone ~. The riser exit temperature, ~efined as .. the temperature at which the mixture passes from the riser 4 to conduit 6, ranges between 482 and 593C (900~ and 1100F~, and ~; preferably between 538 and 566C (1000 and 1050F). The riser exit temperature is controlled by monitoring and adjusting the rates and temperatures of hydrocarbons and regenerated catalyst into the riser 4. ~iser effluent conduit 6 is attached at one end to the riser 4 and at its other end to the cyclone 8.
~ The first reactor cyclone 8 separates a portion of catalyst - from the catalyst-hydrocarbon ~ixture and passes this catalyst down a first reactor cyclone dipleg 12 to a stripping zone 30 located therebelow. The remaining gas and catalyst pass from the first reactor cyclone 8 through a gas effluent conduit 10. The conduit lQ
is provided with a connector 24 to allow for thermal expansion. The catalyst passes through the conduit lQ, then through a second reactor cyclone inlet conduit 22, and into a second reactor cyclone 14. The second cyclone 14 separates the stream to form a catalyst stream, which passes through a second reactor cyclone diple~ 18 to the stripping zone 30 located therebelow, and an overhead stream .The second cyclone overhead stream, which contains the remaining gas and catalyst, passes through a second cyclone gaseous effluent conduit 16 to a reactor overhead port 20. ~ases from the atmosphere of the reactor vessel 2 may pass through a reactor overhead conduit 22 into -the reactor overhead port 20. The gases ~ 3~2~
F~3734 ~ 107~
which exit the reactor 2 through the second cyclone gaseous effluent conduit 16 and the reactor overhead conduit 22 are combined and exit through the reactor overhead port 20. It will be apparent to those skilled in the art that although only one series connection of cyclones 8, 14 is shown in the embodiment, more than one series connection and/or more or less than two consecutive cyclones in series connection could be employed.
The mixture of catalyst and hydrocarbons passes through the first reactor cyclone overhead conduit lQ and the second reactor n cyclone inlet conduit 22 without entering the reactor vessel 2 ,. atmosphere. ~owever~ the connector 24 may provide an annular port to admit stripping gas from the reactor vessel 2 into the conduit 10 to aid in separating catalyst from hydrocarbons adhering thereto.
' The closed cyclone system and annular port is described more fully ; 15 in U. S. Patent ~o. 4,502,9~7 to lladdad et al.
The separated catalyst from cyclones 8, 14 pass through respective diplegs 12, 18 and are discharged therefrom after a suitable pressure is generated within the diplegs hy the buildup of the catalyst. The catalyst falls from the diplegs into a bed of catalyst 31 located in the stripping zone 3n. The first dipleg 12 is sealed by being extended into the catalyst bed 31. The second dipleg 18 is sealed by a trickle valve 19. The separated catalyst is contacted and combined with hot regenerated catalyst from -the regenerator 80 in the stripping zone 30. The regenerated catalyst has a temperature in the range between 55C (100F) above that of the stripping zone 30 and 871C (1600F) to heat the separated catalyst in bed 31. The regenerated catalyst passes from the regenerator 80 to the reactor vessel 2 throllgh a transfer line 106 attached at one end to the regenerator vessel 80 and at another end to the reactor vessel 2. The transfer line 106 is provided with a slide valve 108. Combining the separated catalyst ~ith the regenerated catalyst promotes the stripping at a temperature in the range between 55C (100~) above the riser exit temperature and ~3209~
816C (1500F). Preferably, the catalyst strippin~ zone operates at a temperature between R3C (150F) above the riser exit temperature ; and 760C (1400F).
The catalyst 31 in the stripping zone 30 is contacted at high temperature, discussed above,~ith a stripping gas, such as steam, flowing co~mtercurrently to the direction of flow of the catalyst. The stripping gas is introduced into the lower portion of the stripping zone 30 by one or more conduits 34 attached to a stripping gas header 36. The catalyst residence time in the stripping zone 30 ranges from 2.5 to 7 minutes. The vapor residence time in the catalyst stripping zone 30 ranges from 0.5 to 30 seconds, and preferably 0.5 to 5 seconds. The stripping zone 3Q
removes coke, sulfur and hydrogen from the separated catalyst which has heen combined with the regenerated catalyst. The sulfur is removed as hydrogen sulfide and mercaptans. The hydrogen is removed as ~olecular hydrogen, hydrocarbons, and hydrogen sulfide. ~ost preferably, the stripping zone 30 is ~aintained at temperatures between ~3C (150F) above the riser exit temperature, which are sufficient to reduce coke load to the re~enerator by at least ~0%, remove 70~80~ of the hydrogen as molecular hydrogen, light hydrocarbons and other hydrogen~containing compounds, and remove 45 to 55% of the sulfur as hydrogen sulfide and mercaptans, as well as a portion of nitrogen as ammonia and cyanides.
The catalyst stripping zone 30 may also be provided with trays (baffles) 32. The trays ~ay be disc~ and doughnut-shaped and may be perforated or unperforated.
Stripped catalyst passes through a stripped catalyst effluent conduit 38 to a ca~alyst cooler 40. The catalyst cooler 40 is a heat~exchanger which cools the stripped catalyst from the reactor vessel 2 to a temperature sufficient to maintain the regenerator vessel 80 at a temperature between 55C (100F) above the temperature of the stripping zone 30 and 871C (1600F).
Preferably, the catalyst cooler ~0 cools the stripped catalyst ~32~92~
stream to a temperature sufficient to control the regenerator vessel 8Q at a temperature to between 83C (150F) above the temperature of the stripping zone 30 and 871C (1600F). Most preferahlv, the stripped catalyst stream is cooled between 28 and R3C (50 and : 5 150F) below the stripping zone temperature, so long as the cooled catalyst temperature is at least 593C (1100F).
The catalyst cooler 40 is preferably an indirect : heat~exchanger located outside the reactor vessel 2. A
heat-exchange medium, such as liquid water (boiler feed water), passes throllgh a conduit 50, provided with a valve 54~ into a set of ~r tubes 48 within the catalyst cooler 40. The catalyst passes through the shell side 46 of the catalyst cooler 40. The catalyst cooler 40 is attached to an effluent conduit 42 provided with a slide valve 44. The cooled catalyst passes through the conduit 42 into a regenerator inlet conduit 60.
In the regenerator riser 60, air and cooled catalyst combine and pass upwardly through an air catalyst disperser 74 into a fast fluid bed 62. The fast fluid bed 62 is part of the regenerator vessel 80. In the fast fluid bed 62, combustible materials, such as coke which adheres to the cooled catalyst, are burned off the catalyst by contact with lift air. Air passes through an air supply line 66 ~hrough a control valve 68 and an air transfer line 68 to the regenerator inlet conduit 60. ~ptionally~
if the temperature of the cooled catalyst from the conduit 42 is less than 593C (1100F), a portion of hot regenerated catalyst from the standpipe 102 passes ~hrough a conduit 101, provided with a control valve 103, into the fast fluid bed 62. The fast fluid bed 62 contains a relatively dense catalyst bed 76. The air fluidizes the catalyst in bed 76, and subsequently transports the catalyst continuously as a dilute phase throu~h the regenerator riser R3.
The dilute ph.ase passes upwardly through the riser 83, through a radial arm 84 attached to the riser 83, and then passes downwardly to a second relatively dense bed of catalyst ~2 located within the regenerator vessel. 80.
F-3734 --13-~ 1 3 ~
The major portion of catalyst passes downwardly through the radial arms 84, while the gases and remaining catalyst pass into the atmosphere of the regenerator vessel 80. The gases and remaining catalyst then pass through an inlet conduit 89 and into the first regenerator cyclone 86. The first cyclone 86 separates a portion of catalyst and passes it through a first dipleg 90, while remaining catalyst and gases pass through an overhead conduit 88 into a second ; regenerator cyclone 92. The second cyclone 92 separates a ~ortion of catalyst and passes the separated portion through a second dipleg 96 having a trickle valve 97, with the remaining gas and catalyst .. passing through a second overhead conduit 9~ into a regenerator vessel plenum chamber 9~. A flue gas stream 110 exits from the regenerator plenum chamber 98 through a regenerator flue gas conduit 100 .
The regenerated catalyst settles -to form the bed ~2, which is dense compared to the dilute cata]yst passing through the riser 83. The regenerated catalyst 'ned 82 is at a substantially higher temperature than the stripped catalyst from the stripping zone 30, due to the coke burning which occurs in the regenerator 80. The catalyst in bed 82 is at least 55C (100F) hotter than the temperature of the strippin~ zone 30, preferably at least 83C
(150F) hotter than the temperature of the stripping zone 30. The regenerator temperature is, at most, 871C (1600F) to prevent deactivating the catalyst. Coke burning occurs in the regenerator inlet conduit 60, as well as the fast fluid bed 62 and riser 83.
Optionally, air may also be passed from the air supply line 64 to an air transfer line 70, provided with a control valve 72, to an air header 78 located in the regenerator 80. The regenerated catalyst then passes from the relatively dense bed 82 through the conduit 106 to the stripping zone 30 to provide heated catalyst for the stripping zone 30.
Any conventional fluid catalytic cracking catalyst can be used in the present invention. ~Tse of zeolite catalysts in an 132~2~
F-3734 --14 ~
amorphous base is preferred. Many suitable catalysts are discussed in U. S. Patent ~To. 3,926,778 to Owen et al.
One example of a process which can be conducte~ in accordance with the present invention begins with a 343 to 593C
(650 to 1100F) boiling poin-t hydrocarbon feedstock ~hich passes into a riser conversion zone 4, where it combines with hot regenerated catalyst at a temperature of about 815C (1500F) from a catalyst standpipe 102 to form a catalyst~hydrocarbon mixture. The catalyst~hydrocarbon mixture passes upwardly through the riser conversion zone 4 and into a riser effluent conduit 6 at a riser .. exit temperature of about 538C (1000F). The catalyst passes from the conduit 6 into -the first reactor cyclone 8, where a portion of catalyst is separated from the mixture and drops through a dipleg 12 to a bed of catalyst 31 contained within a stripping zone 30 therebelow. The stripring zone 30 operates at about 704C
(1300F). The remainder of the ~ixture passes upwardly through the first overhead conduit lQ into a second reactor cyclone 14. T,he second cyclone 14 separates a portion of catalyst from the first cyclone overhead stream and passes the separated catalyst down the second dipleg 18. The remaining solids and gases pass upwardly as a second cyclone overhead stream through conduit 16 into the reactor vessel overhead port 20.
In the stripping zone 30, the catalyst from diplegs 12, 18 combines with catalyst from regenerator 80, which passes through a conduit 106 and is stripped by contact with steam from a steam header 36. me regenerated catalyst from the conduit 106 is at a temperature of about ~15C (1500F) and Frovides heat to maintain the stripping zone 30 at about 704C (1300F). The stripped catalyst passes through a conduit 38 into a catalyst cooler 40 at a temperature of about 704C (1300F). The catalyst cooler 40 cools the 704C (1300F) catalyst to about 621C (1150F). The cooling occurs by indirect heat~exchange o~ the hot stripped catalyst with boiler feed water, which passes through a conduit SO to form steam which exits through a conduit 52.
F-3734 ~15-- ~32~2~
The cooled catalyst, at a temperature of about 621C
(1150F), combines with lift air from a conduit 66 in a regenerator inlet conduit 60 to form an aircatalyst mixture. The mixture passes upwardly through the conduit 60 into fast fluid hed 76. The catalyst continues upwardly from fast fluid bed 7fi through the regenerator riser 83 and into a regenerator vessel 80. The catalyst is then separated from gases by the radial arm 84, as wel] as cyclones 86 and 92, and passes downwardly through the regenerator to form a relatively dense bed R2. The coke adhering to the strip~ed catalyst burns in the conduit 60, the fast fluid bed 62, the riser .. ~3, and the regenerator vessel ~n. riue to the coke burning, the catalyst in bed 82 is heated to a temperature of about P,15C
(1500F). Catalyst bed ~2 then supplies catalyst for -the standpipe ' 102, which combines with the hydrocarbon feedstock. ~ed ~2 also provides catalyst for conduit 106 which passes to the stripping zone 30. Gaseous effluents pass through a first cyclone g6 and second cyclone 92 and leave the regenerator 80 as a flue gas stream 110 through a flue gas conduit lQ0.
Operating the stripping zone as a high temperature (hot) stripper, at a temperature between 55C (100F) above a riser exit temperature and 816C (1500~), has the advantage that it separates hydrogen, as molecular hydrogen as well as hydrocarbons, Erom catalyst. ~Iydrogen removal eliminates hydrothermal degradation, which typically occurs when hydrogen reacts with oxygen in a fluid catalytic cracking regenerator to form water. The hot stripper also removes sulfur from coked catalyst as hydrogen sulfide and mercaptans, which are easy to scrub. ~y removing sulfur from coked catalyst in the hot stripper, the hot stripper prevents formation of Sx in ~le regenerator. It is more difficult to remove Sx from regenerator flue gas than to remove hydrogen sulfide and mercaptans from a hot stripper effluent. The hot stripper enhances removal of hydrocarbons from spent catalyst, and thus prevents burning of valuable hydrocarbons in the regenerator. Furthermore, the hot F~3734 ~ 32~92~
stripper quickly separates hydrocarbons from catalyst to avoid overcracking.
Preferably the hot stripper is maintained at a temperature between 83C (150F) above a riser exit temperature and 760C
(14~0F) to reduce coke load to the regenerator by at least ~%, and strip away 70 to 80% of the hydrogen as molecular hydrogen, light hydrocarbons and other hydrogen-containing compounds. ~he hot stripper is also maintained within the desired temperature conditions to remove 45 to 55~ of the sulfur as hydrogen sulfide and mercaptans, as well as a portion of nitrogen as ammonia and cyanides.
This concept advances the development of a heavy oil (residual oil) catalytic cracker and high temperature cracking unit for conventional gas oils. The process combines the control of catalyst deactivation with controlled catalyst carbon contamination level and control of te~perature levels in the stripper and regenerator.
The hot s-tripper temperature controls the amount of carbon removed from the catalyst in the hot stripper. Accordingly, the hot stripper controls the amount of carbon (and hydrogen, sulfur) remaining on the catalyst to the regenerator. This residual carbon level controls the te~perature rise between the reactor stripper and the regenerator. The hot stripper also controls the hydrogen content of the spent catalyst sent to the regenerator as a function of residual carbon. Thus, the hot stripper controls the temperature and amount of hydrothermal deactivation of catalyst in the regenerator. This concept may be practiced in a ~ulti-sta~e, multi~temperature stripper or a single stage stripper.
Fmploying a hot stripper, to re~ove carbon on the catalyst, rather than a regeneration stage reduces air pollution, and allo~s all of the carbon made in the reaction to be burned to C02, if desired.
; The stripped catalyst is cooled (as a function of its carbon level) to a desired re~enerator inlet temperature to control :~2~
F~3734 ~17~
the degree of regeneration desired, in combination with the other variables of C0/CO2 ratio desired, the amount oE carbon burn~off desired, the catalyst recirculation rate from the regenerator to the hot stripper, and the degree of desulfurization/
denitrification/decarbonization desired in the hot stripper.
Increasing CO/C~2 ratio decreases the heat generated in the regenerator, and accordingly decreases the regenerator temperature.
~urning the coke, adhering to the catalyst in the regenerator, to C0 removes the coke, as would burning coke to CO2, but kurning to C0 produces less heat than burning to C02. The amount of carbon (coke) burn-off affects regenerator temperature, because greater carbon burn-off generates greater heat. The catalyst recirculation rate from the regenerator to the hot stripper affects regenerator ' temperature, because increasing the amount of hot catalyst rrom the regenerator to the hot stripper increases hot stripper temperature.
Accordingly, the increased hot stripper temperature removes increased amounts of coke so less coke need burn in the regenerator;
thus, regenerator temperature can decrease.
The catalyst cooler controls regenerator temperature, thereby allowing the hot stripper to be run at temperatures between 55C (100F) above a riser exit temperature to 816~C (1500F)~ which facilitate controlling sulfur and hydrogen, while allowing the regenerator to be run independently at temperatures at least lQ0F
hotter than the stripper, while preventing regenerator temperatures greater than 871C (1600F) which deactivate catalyst.
Use of the catalyst cooler on catalyst exiting the stripper also allows circulation of catalyst to the regenerator riser to increase catalyst density in the regenerator riser, while controlling the regenerator temperature. This reduces catalyst deactivation and provides additional control.
While specific embodiments of the method and apparatus aspects of the invention have heen shown and describedS it should be apparent that the many modifications can be made thereto without departing from the spirit and scope of the invention~ Accordingly, the invention is not limited by the foregoing description~ but is only limited by the scope of the claims appended thereto.
Claims (18)
1. A process for controlling the fluid catalytic cracking of a feedstock containing hydrocarbons, comprising the steps of:
passing a mixture comprising catalyst and the feedstock through a riser conversion zone under fluid catalytic cracking conditions to crack the feedstock;
passing the mixture, having a riser exit temperature, from the riser into a fluid catalytic cracking reactor vessel;
separating a portion of catalyst from the mixture, with the remainder of the mixture forming a reactor vessel gaseous stream;
heating the separated catalyst portion by a heat step consisting essentially of combining the separated catalyst portion with a portion of regenerated catalyst from a fluid catalytic cracking regenerator vessel to form combined catalyst;
stripping the combined catalyst, by contact with a stripping gas stream, consisting essentially of stream at a stripping temperature between 55°C above the riser exit temperature and 815°C, the regenerated catalyst portion having a temperature between 55°C above the stripping temperature and 871°C prior to heating the separated catalyst to produce a stripped catalyst;
cooling the stripped catalyst, prior to passing it into the regenerator vessel, to a temperature sufficient to cause the regenerator vessel to be maintained at a temperature between 55°C
above the stripping temperature and 871°C wherein the cooling step comprises passing the stripped catalyst stream to a heat exchanger located outside the reactor vessel; and regenerating the cooled catalyst stream in the fluid catalytic cracking regenerator vessel by contact with an oxygen-containing stream at fluid catalytic cracking regeneration conditions.
passing a mixture comprising catalyst and the feedstock through a riser conversion zone under fluid catalytic cracking conditions to crack the feedstock;
passing the mixture, having a riser exit temperature, from the riser into a fluid catalytic cracking reactor vessel;
separating a portion of catalyst from the mixture, with the remainder of the mixture forming a reactor vessel gaseous stream;
heating the separated catalyst portion by a heat step consisting essentially of combining the separated catalyst portion with a portion of regenerated catalyst from a fluid catalytic cracking regenerator vessel to form combined catalyst;
stripping the combined catalyst, by contact with a stripping gas stream, consisting essentially of stream at a stripping temperature between 55°C above the riser exit temperature and 815°C, the regenerated catalyst portion having a temperature between 55°C above the stripping temperature and 871°C prior to heating the separated catalyst to produce a stripped catalyst;
cooling the stripped catalyst, prior to passing it into the regenerator vessel, to a temperature sufficient to cause the regenerator vessel to be maintained at a temperature between 55°C
above the stripping temperature and 871°C wherein the cooling step comprises passing the stripped catalyst stream to a heat exchanger located outside the reactor vessel; and regenerating the cooled catalyst stream in the fluid catalytic cracking regenerator vessel by contact with an oxygen-containing stream at fluid catalytic cracking regeneration conditions.
2. The process of claim 1, wherein the stripped catalyst stream is indirectly heat-exchanged with a heat-exchange medium in the heat exchanger.
3. The process of claim 1, wherein the riser exit temperature ranges between 482° and 593°C, and the heat-exchanger cools the stripped catalyst stream to cause the catalyst in the regenerator vessel to be maintained at a temperature between 83°C
above the stripping step temperature and 871°C.
above the stripping step temperature and 871°C.
4. The process of claim 1, 2 and 3 wherein the heating step and the stripping step occur within the reactor vessel and the stripping step occurs at a stripping temperature between 83°C above the riser exit temperature and 760°C and a residence time for the gaseous stream from 0.5 to 5 seconds.
5. The process of claim 1, 2 or 3, wherein the separating step comprises separating the mixture from the riser conversion zone in a closed cyclone system in communication with the riser conversion zone.
6. The process of claim 1, 2 or 3, wherein the riser exit temperature ranges from 538° to 565°C and the stripped catalyst stream is cooled in the heat-exchanger to between 28° and 83°C below the stripping temperature, the heat-exchanger thereby causing the regenerator vessel temperature to be maintained independently of the stripping temperature.
7. The process of claim 1, 2 or 3, wherein the separated catalyst portion of the combined catalyst contains sulfur-containing compounds and hydrogen-containing compounds derived from the feedstock, and the stripping step removes 45 to 55%
of the sulfur-containing compounds and 70 to 80% of the hydrogen-containing compounds in the separated catalyst portion.
of the sulfur-containing compounds and 70 to 80% of the hydrogen-containing compounds in the separated catalyst portion.
8. The process of claim 1, 2 or 3, wherein the combined catalyst passes countercurrently to the stripping gas during the stripping step.
9. An apparatus for controlling the fluid catalytic cracking of a feedstock comprising hydrocarbons, comprising:
means defining a riser conversion zone through which a mixture comprising catalyst and the feedstock passes at fluid catalytic cracking conditions to crack the feedstock;
a fluid catalytic cracking reactor vessel;
means for passing the mixture from the riser into the fluid catalytic cracking reactor vessel, the mixture having a riser exit temperature as it passes into the reactor vessel;
means for separating a portion of catalyst from the mixture, with the remainder of the mixture forming a reactor vessel gaseous stream;
means for heating the separated catalyst portion, by a heating step consisting essentially of combining the separated catalyst portion with a portion of regenerated catalyst to form combined catalyst;
means for stripping the combined catalyst by contact with a stripping gas stream to form a stripped catalyst stream;
a fluid catalytic cracking regenerator vessel for producing the portion of regenerated catalyst; and a heat-exchanger for cooling the stripped catalyst stream, the catalyst cooler being located outside the reactor vessel, the fluid catalytic cracking regenerator vessel thereby regenerating the cooled catalyst stream by contact with an oxygen-containing stream at fluid catalytic cracking regenerator conditions.
a stripped catalyst effluent conduit, attached to the means for stripping catalyst stream from the means for stripping to the heat-exchanger.
means defining a riser conversion zone through which a mixture comprising catalyst and the feedstock passes at fluid catalytic cracking conditions to crack the feedstock;
a fluid catalytic cracking reactor vessel;
means for passing the mixture from the riser into the fluid catalytic cracking reactor vessel, the mixture having a riser exit temperature as it passes into the reactor vessel;
means for separating a portion of catalyst from the mixture, with the remainder of the mixture forming a reactor vessel gaseous stream;
means for heating the separated catalyst portion, by a heating step consisting essentially of combining the separated catalyst portion with a portion of regenerated catalyst to form combined catalyst;
means for stripping the combined catalyst by contact with a stripping gas stream to form a stripped catalyst stream;
a fluid catalytic cracking regenerator vessel for producing the portion of regenerated catalyst; and a heat-exchanger for cooling the stripped catalyst stream, the catalyst cooler being located outside the reactor vessel, the fluid catalytic cracking regenerator vessel thereby regenerating the cooled catalyst stream by contact with an oxygen-containing stream at fluid catalytic cracking regenerator conditions.
a stripped catalyst effluent conduit, attached to the means for stripping catalyst stream from the means for stripping to the heat-exchanger.
10. The apparatus of claim 9, wherein the heat exchanger is upstream of the regenerator vessel.
11. The apparatus of claim 9 or 10, wherein the riser conversion zone accommodates the feedstock which further comprises sulfur-containing compounds, and the means for stripping accommodates a residence time of gas in the means for stripping from 0.5 to 30 seconds, the means for stripping maintaining the combined catalyst therein at a temperature between 55°C above the riser exit temperature and 815°C, thereby removing molecular hydrogen, hydrocarbons and sulfur-containing compounds derived from components of the feedstock in the separated catalyst portion of the combined catalyst, wherein said removed sulfur-containing compounds consist essentially of hydrogen sulfide and mercaptans..
12. The apparatus of Claim 11, wherein the catalyst cooler is an indirect heat-exchanger for cooling the stripped catalyst stream to a temperature sufficient to cause the regenerator vessel to be maintained at a temperature between 55°C above the stripping temperature and 871°C, thereby producing the regenerated catalyst portion having a temperature between 55°C above the stripping temperature and 871°C.
13. The apparatus of claim 12, whereby the riser conversion zone maintains a temperature of mixture exiting the riser between 538° and 565°C, and the heat-exchanger is sized to cool the stripped catalyst stream sufficiently to thereby cause the catalyst in the regenerator vessel to be maintained at a temperature between 83°C above that of the means for stripping and 871°C.
14. The apparatus of claim 13, wherein the stripping gas consists essentially of stream, wherein the means for heating and the means for stripping are located in the reactor vessel, and the means for stripping allows a residence time for the gas in the means for stripping from 0.5 to 5 seconds, thereby causing the stripping temperature to be maintained at a temperature between 83°C above that of the riser exit temperature and 760°C.
15. The apparatus of claim 14, wherein the means for separating the mixture from the riser conversion zone comprises a closed cyclone system in communication with the riser conversion zone.
16. The apparatus of claim 15, whereby the riser conversion zone maintains the temperature of mixture exiting the riser between 538° and 565°C, wherein the catalyst cooler is sizedto cool the reactor vessel catalyst stream to a temperature between 28° and 83°C below the stripping temperature, the catalyst cooler thereby maintaining the regenerator vessel temperature independently of stripping temperature.
17. The apparatus of claim 16, wherein the separated catalyst portion contains the sulfur-containing compounds and hydrogen-containing compounds derived from the feedstock, and whereby the means for stripping removes 45 to 55% of the sulfur-containing compounds and 70 to 80% of the hydrogen-containing compounds in the separated catalyst portion of the combined catalyst.
18. The apparatus of claim 17, wherein the means for stripping comprises means for passing the combined catalyst countercurrently to the s-tripping gas.
5114h/0477h
5114h/0477h
Priority Applications (5)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US07/014,964 US4820404A (en) | 1985-12-30 | 1987-02-17 | Cooling of stripped catalyst prior to regeneration in cracking process |
| PCT/US1989/001012 WO1990009842A1 (en) | 1985-12-30 | 1989-03-03 | Heavy oil catalytic cracking |
| EP89903557A EP0415935B1 (en) | 1985-12-30 | 1989-03-03 | Heavy oil catalytic cracking |
| AU32807/89A AU633480B2 (en) | 1985-12-30 | 1989-03-03 | Heavy oil catalytic cracking |
| CA000593136A CA1320924C (en) | 1985-12-30 | 1989-03-08 | Heavy oil catalytic cracking |
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US81471485A | 1985-12-30 | 1985-12-30 | |
| CA000593136A CA1320924C (en) | 1985-12-30 | 1989-03-08 | Heavy oil catalytic cracking |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1320924C true CA1320924C (en) | 1993-08-03 |
Family
ID=25672511
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000593136A Expired - Fee Related CA1320924C (en) | 1985-12-30 | 1989-03-08 | Heavy oil catalytic cracking |
Country Status (3)
| Country | Link |
|---|---|
| EP (1) | EP0415935B1 (en) |
| CA (1) | CA1320924C (en) |
| WO (1) | WO1990009842A1 (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5462717A (en) * | 1989-09-13 | 1995-10-31 | Pfeiffer; Robert W. | Processes using fluidized solids and apparatus for carrying out such processes |
| CN110325278B (en) * | 2017-02-28 | 2024-02-20 | 环球油品有限责任公司 | Compact two-stage regenerator and method of use thereof |
| US20220250022A1 (en) * | 2019-07-31 | 2022-08-11 | Sabic Global Technologies B.V. | Heating plates riser reactor |
Family Cites Families (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2518693A (en) * | 1941-07-24 | 1950-08-15 | Standard Oil Dev Co | Process and apparatus for contacting finely divided solids and gases |
| US2477042A (en) * | 1943-03-10 | 1949-07-26 | Standard Oil Dev Co | Method of heat exchange in fluidized hydrocarbon conversion systems |
| US3392110A (en) * | 1965-09-02 | 1968-07-09 | Mobil Oil Corp | Method for the utilization of highly active hydrocarbon conversion catalysts |
| US3821103A (en) * | 1973-05-30 | 1974-06-28 | Mobil Oil Corp | Conversion of sulfur contaminated hydrocarbons |
| US4435281A (en) * | 1980-09-15 | 1984-03-06 | Standard Oil Company (Indiana) | Catalytic cracking with reduced emission of noxious gas |
| US4353812A (en) * | 1981-06-15 | 1982-10-12 | Uop Inc. | Fluid catalyst regeneration process |
| US4419221A (en) * | 1981-10-27 | 1983-12-06 | Texaco Inc. | Cracking with short contact time and high temperatures |
| US4574044A (en) * | 1982-03-31 | 1986-03-04 | Chevron Research Company | Method for spent catalyst treating for fluidized catalytic cracking systems |
| US4693809A (en) * | 1985-12-05 | 1987-09-15 | Engelard Corporation | Hydrocarbon conversion process |
-
1989
- 1989-03-03 EP EP89903557A patent/EP0415935B1/en not_active Expired - Lifetime
- 1989-03-03 WO PCT/US1989/001012 patent/WO1990009842A1/en active IP Right Grant
- 1989-03-08 CA CA000593136A patent/CA1320924C/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| EP0415935B1 (en) | 1993-09-15 |
| EP0415935A1 (en) | 1991-03-13 |
| WO1990009842A1 (en) | 1990-09-07 |
| EP0415935A4 (en) | 1991-05-15 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US4820404A (en) | Cooling of stripped catalyst prior to regeneration in cracking process | |
| AU627306B2 (en) | Heavy oil catalytic cracking process and apparatus | |
| US5248408A (en) | Catalytic cracking process and apparatus with refluxed spent catalyst stripper | |
| CA2087275C (en) | Process and apparatus for control of multistage catalyst regeneration with partial co combustion | |
| CA1137908A (en) | Control of emissions in fcc regenerator flue gas | |
| US5000841A (en) | Heavy oil catalytic cracking process and apparatus | |
| US5032252A (en) | Process and apparatus for hot catalyst stripping in a bubbling bed catalyst regenerator | |
| WO1992000139A1 (en) | Process and apparatus for dehydrogenating alkanes | |
| EP0493932B1 (en) | Heavy oil catalytic cracking process and apparatus | |
| US5128109A (en) | Heavy oil catalytic cracking apparatus | |
| US4973452A (en) | Heavy oil catalytic cracking | |
| US5160426A (en) | Process and apparatus for indirect heating of catalyst stripper above a bubbling bed catalyst regenerator | |
| CA1320924C (en) | Heavy oil catalytic cracking | |
| CA1178229A (en) | Fcc regeneration process | |
| CA1261774A (en) | Fluid catalytic cracking method and apparatus | |
| AU633480B2 (en) | Heavy oil catalytic cracking | |
| CA2000824A1 (en) | Resid cracking process and apparatus | |
| WO1992001511A1 (en) | Process and apparatus for control of multistage catalyst regeneration with full co combustion | |
| WO1993000674A1 (en) | A process for stripping and regenerating fluidized catalytic cracking catalyst | |
| EP0639216A1 (en) | Catalytic cracking process and apparatus therefor | |
| JPH03505594A (en) | Heavy oil catalytic cracking | |
| AU8221391A (en) | A process for stripping and regenerating fluidized catalytic cracking catalyst |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKLA | Lapsed |