Note: Descriptions are shown in the official language in which they were submitted.
REG~NERATION OF CATl~LYST USED IN THE CONVERSION OF
CI~RBO-METALI.IC CONTAINING RESIDUAL OILS
The present invention is particularly concerned with the
5 method and technique for regenerating a cracking catalyst
comprising relatively high levels of deposited hydrocarbonaceous
materials and meta] contaminants. ',ulfur and nitrogen contaminants
are also included as deposited contaminants.
The well-known process of relatively clean gas oil feed fluid
10 catalytic crackin~ (FCC~ is not designed or tailored for use in the
catalytic conversion of carbo-metallic containing oil feeds known as
residual oils or reduced crudes comprising carbo-metallic high
molecular weight hydrocarbon components boiling above 522C
(1025F) and effecting regenera-tion of catalyst particles used
15 therein. Gas oil fluid catalytic cracking operations are generally
restricted to processing relatively clean feeds comprising less than
one weight percent of Conradson carbon and comprising small
amounts of metal contaminants of Ni, V, Fe and Cu in amounts
preferably less than about 0. 5 ppm. The zeolite containing
~0 catalysts employed currently in gas oil fluid catalytic cracking
operations are generally discarded when their catalytic MAT activity
if below about 70% and a contaminant metals loading has reached
from 1000 to 3000 Ni -~ V.
The development of fluid catalytic cracking was for the
25 conversion of select relatively clean fractions or portions obtained
from crude oils to produce particularly gasoline and heating fuels.
The select feedstock for FCC gas oil operations comprise
predominantly atmospheric and vacuum gas oils, generally boiling
below about 552C (1025F) and most desirably comprise a low
30 Conradson carbon content, below 1 wt%, a low metals content, below
0.5 ppm Ni + V and are also low in sulfur and nitrogen components
and obtained by prehydrogenation of the feed. More typical (GO)
gas oil feedstocks comprising atmospheric and vacuum gas oils
contain less than 0 . 5 wt% Conradson carbon and 0 .1-0 . Z ppm Ni -
~
35 V. The boiling range of gas oil is generally above about 221C
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(430F) up to about ~52C (1025F) but may go to 566C (1050F)
with some clean crude oils. The gas oil feed for an FCC operation
is preheated to a temperature in the range of 260-427C (500-800F)
and thus is substantially completely vaporized immediately upon
5 contact wi th hot regenerated catalyst at temperatures in the range
of 621-787C (1150-1450F). This complete vaporization of the Eeed
by the catalyst in a riser reactor results in a relatively high
conversion (>70%), high gasoline product selectivities (>70%~ and
most usually low carbon values (<1 wt% on catalyst, about 4 wt% on
10 feed). The catalyst so utilized gradually accumulates some metal
contaminants after an extended period of operation in the range of
about 500-3,000 ppm Ni + V before the catalyst is gradually and/or
continuously replaced with fresh catalyst added to maintain an
equilibrium state of conversion and metals level. The FCC process
15 as practiced today provides high coke and gas makes at the
elevated metal levels with a lowered gasoline selectivity, thus
necessitating considerable catalyst withdrawal and additions of fresh
catalyst as makeup. Secondly, the coke make or carbon deposition
as hydrocarbonaceous material on the catalyst in gas oil cracking is
20 relatively low by comparison with more severe operations such as
provided by reduced crude cracking operations. Also for
metallurgical reasons and preservation of catalyst activity, it is
desirable to restrict regeneration temperatures generally below
815C (1500F) and more usually in the range of 677 to 760C (1250
25 to 1400F). However, processing reduced crudes and residual oils
of high Conradson carbon under FCC operating conditions and
particularly restricted catalyst regeneration conditions with known
FCC catalysts is a most difficult problem because of the high levels
of carbonaceous material on the catalyst con trihuting to reduced
30 catalyst life and requiring relatively high catalyst inventory.
Reduced crude catalytic processing goes against substantially all
processing principles practiced in gas oil FCC technology in that
(1 ) reduced crudes charged for catalys~t contact are only partially
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vaporized; (2~ reduced crudes have a higher metals content
resulting in high metals deposition and rapid accumulation on
catalyst particles; (3) reduced crudes have a high Conradson
carbon value contributed by naphthenes and asphaltenes; and (4)
5 processing reduced crudes and residual oils comprising materials
boiling above 552C ~1025F) contributes to high deposition of
hydrocarbonaceous material on the catalyst and thus high
temperatures generated by oxygen combustion thereof during
regeneration is the norm in the absence of elaborate control
10 systems.
In reduced crude processing one must necessarily give
consideration to high metals loading on catalyst, high carbon and
hydrogen deposition on catalyst, maintaining unit heat balance,
avoiding catalyst inactivation temperatures, and more particularly
15 maintaining catalyst activity under the severity of conditions
encountered .
The processing of residual oils and reduced crudes comprising
carbo~metallic high molecular weight components such as
asphaltenes, polycyclic naphthenes and porphyrins in a reduced
20 crude cracking (RCC) operation deposits a large amount of coke in
the form of hydrocarbonaceous material on the RCC catalyst. Also
deposited are metal deposits of the cracking operations such as
nickel, vanadium, sodium, iron, copper, sulfur and nitrogen
compounds in various quantities depending upon feed source.
25 Following cracking of such reduced crude feeds and mechanical
separation of the vaporous products of cracking from catalyst, the
separated catalyst is stripped usually with steam to remove
entrained vaporous material before passing the stripped catalyst to
catalyst regeneration for removal of deposited hydrocarbonaceous
30 material by burning with an oxygen containing gas such as air.
A review of pertinent prior art having a bearing on reduced
crude cracking and particularly the regeneration of metals
contaminated catalyst comprising high levels of deposi ted
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hydrocarbonaceous materials has been less than lucrative for
teachings directed to dissapating high levels of carbon burning heat
to provide a regenerated cataly.st of low or no residual carbon
residue .
U . S . Patent 2,606,430 teaches high temperature carbonization
and gasification of coke produced by cracking to produce synthesis
gas. Temperatures of about 1093C (2000F) are contemplated in
the gasification zone.
U . S . Patent 3, 726, 791 teaches that high Conradson carbon
feeds are coked to lay down carbonaceous deposits on a gasification
catalyst. The catalyst so coked is then steam gasified to produce
hydrogen.
U . S . Patent 3, 433,732 teaches catalytic hycrocracking and
steam regeneration of the catalyst to produce hydrogen.
Canadian Patent 875,528 teaches contacting a coked catalyst
with oxygen and carbon dioxide to produce carbon monoxide. The
carbon monoxide is reacted with steam over a catalyst to form
hydrogen and carbon dioxide.
U . S . Patent 2,414,002 teaches a two-stage catalyst
regeneration operation which separates regeneration flue gases from
each stage of controlled oxygen regeneration. This patent does not
speak to the problems of regenerating catalyst comprising the hdavy
deposits of reduced crude cracking.
U.S. Patent 4,009,121 directed to the control of regeneration
temperatures relies upon the use of steam coils in the ca-talyst bed.
U.S. Patent 3,563,911 describes a two-stage catalyst
regeneration operation employing oxygen containing gas in each
stage to remove up to 65% of carbonaceous deposits in the first
stage .
U.S. Patent 3,821,103 discloses a two-stage regeneration
operation with oxygen containing gas such as air. The flue gas of
the second stage does not contribute heat to the first stage oE
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catalyst regeneration nor is the use of steam therewith contemplated
in the first stage of regeneration.
U . S . Patent 4 ,118, 337 discloses two stages of catalyst
regeneration with oxygen containing gas wherein hot regenerated
5 catalyst of the second sta~e is added -to the Eirst stage regeneration
to increase the heat level thereof.
U.S. Patent 4,276,150 teaches cracking of a reduced crude and
effecting a first partial regeneration thereof with steam and oxygen
in a gasifier at a temperature in the range of 593 to 1204C (1100
10 to 2200F). In this operation the second stage regeneration flue
gases are separated rather than contributing heat to the first stage
of regeneration by utilization with a steam air mixture in the first
regeneration step referred to as a stripper gasifier.
Summary of the Invention
The present invention is directed to the regeneration of fluid
catalyst particles contaminated with hydrocarbonaceous deposits,
metals, sulfur and nitrogen compounds such as obtained in reduced
20 crude cracking operations. In a particular aspect the present
invention is directed to a reyeneration technique which relies upon
two separate stages of fluid catalyst regeneration positioned one
above the other and following a catalyst stripping operation in
which the first stage of catalyst regeneration relies in substantial
25 measure upon the partial removal of hydrocarbonaceous materia] with
a steam oxygen mixture comprising hot flue gas combustion products
under conditions to form CO and hydrogen at least partially
combined therein in combination wi th a second stage of catalyst
regeneration relied upon to complete substantially complete removal
30 oE residual carbonaceous material (coke) with oxygen rich gas under
tempera-ture conditions restricted to preferably limit the temperature
below 815C (1500F) and more usually below about 760C (1400F).
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The use of steam in the presence of oxygen and combustion
flue gas products of the second stage of catalyst regeneration in a
firsl: stage of catalys t regeneration effectively provides
carbonaceous material removal temperatures up ~o about 732C
5 (1350F) and reduces the carbonaceous material level of the catalyst
by a~ least about 40 percent before being subjected to oxygen
regeneration higher temperature conditions in the second stage of
regeneration. The regeneration operating technique of this
invention permits restricting the overall regeneration temperatures
below about 815C (1500F) and preferably below 760C (1400F)
which is not possible in a single stage dense fluid bed catalyst
regeneneration operation for removal of high levels of
hydrocarbonaceous material deposit such as obtained in cracking
reduced crudes to provide catalyst particles of low residual coke.
15 Thus, the particular combination regeneration operation of this
invention because of temperature constraints provided by the
operation permits one to increase the amount of Conradson carbon
content of the feed that can be processed over the catalyst with
high levels of carbonaceous material deposition also permits one to
20 use poorer quality feeds under catalytic conversion conditions to
more suitable products.
The use of a relatively large quantity of steam in the first
stage of catalyst regeneration in combination with some oxygen
providing combustion heat is of such quantity and temperature when
25 combined with the hot flue gas products of the second stage of
regeneration at a temperature up to about 760C (1400F) to
effectively remove a substantial portion of the hydrocarbonaceous
deposits at temperatures up to '732C (1350F) by reacting steam
w:ith carbonaceous deposits to form carbon monoxide and hydrogen.
30 Thus, the hot flue gas components of CO, C02 and oxygen
recovered from the second stage of regeneration and charged with
steam as herein provided to the first regenera tion stage are
balanced to particularly promote the removal of hydrocarhonaceous
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material under controlled endothermic and exothermic reaction
conditions to achieve the results desired. That is, the flue gas
product stream of the first stage of catalyst regeneration will
include reaction products of restricted oxygen com~ustion including
5 steam reforming products, of CO and hydrogen in the presence of
C02 .
The removal of sulfur and nitrogen components in the
hydrocarbonaceous deposits will also accompany the flue gas
products of the first stage regeneration.
The processing of a reduced crude in a fluid catalytic cracking
reaction zone deposits relatively large amounts of coke on the
catalyst. The amount of coke deposited on the catalyst is observed
to be a function of the catalyst cracking activity and the Conradson
carbon content of the reduced crude feed. This can be expressed
15 as 4 wt% plus the feed Conradson carbon content. The ability of a
catalyst single stage regeneration opera tion to handle coke on
catalyst is considered limited to approximately an ~, Conradson
carbon or approximately ~4+8) 12 wt% coke on catalyst. To remove
such coke levels from catalyst particles in a single stage is most
20 difficult because of excessive regeneration temperature potentially
encountered above 815C (1500F), which can irreversably damage
the catalyst activity and selectivity of a crystalline zeolite catalyst
in the presence of steam as well as provide severe apparatus
metallurgical problems recIuiring the use of expensive alloys and
25 refractory linings.
In a two stage, stacked, one above the other, catalyst
regeneration operation or other arrangement, it is difficult to
control oxygen combustion regeneration conditions and such is
aggrevated when one zone is positioned above the other so that -the
30 flue gas products of the bottom second stage pass upwardly
through the catalyst in the first stage of catalyst regeneration and
necessarily contribu-te heat thereto. Also, if one charges all of the
oxygen required for coke combustion as air to the bottom
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regeneration zone, the quantity and velocities of regeneratîon gas
and flue gas products will necessarily be high in order to fluidize a
catalyst bed in the upper first regeneration zone and such high
velocities can entrain or transport an undesired substantial amount
5 of regenerated catalyst from the bottom bed up into the upper
catalyst l~ed comprising the first stage of re~eneration.
In order to reduce the problerns above identified and improve
the technique for removing high levels of carbonaceous material
cleposits in a sequence of at least two stacked regeneration zones as
10 herein provided, a portion of the required regeneration air if
introduced to a bottom portion o~ each of a dense fluid bed of
catalyst in each zone. Thus, the distribution of regeneration air to
each zone may be of equal portion or a higher or lower portion may
be employed in the lower catalyst bed than in the upper bed of
15 catalyst depending on condition desired. In the regeneration
arrangement of this invention it is contemplated employing a greater
portion of o~cygen containing regenera~ion gas such as air in the
lower most bed of catalyst being regenerated to remove residual
carbon of the first stage regeneration so that combustion products
20 thereof and any unreacted oxygen will pass upwardly into the
bottom portion of the upper catalyst bed being regenerated in the
presence of steam charged to the first stage of regeneration to
produce CO and hydrogen. Utili2ing an additional air inlet to the
upper bed of catalyst, added in admixtures with steam or separately
25 thereto, is provided in a volume sufficient to provide exothermic
combustion heat to support the endothermic steam partial
regeneration of the catalyst along with second stage hot combustion
products according to the concepts of this invention.
In one specific embodiment steam is added with some
30 supplemental air and charged for contact with a bo ttom portion of
the upper catalyst bed to be regenerated. Regeneration of catalyst
in the upper bed with oxygen (air) steam mixture is preferably
effected at a temperature withi~n the range of 677C to 732C
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(1250F to 1350F). The steam-air mixture has the dual function of
removal of large amounts of hydrocarbonaceous deposits and
comprising some high molecular weight polynuclear aromatic material
by the combination of partial combustion at a temperature up to
732C (1350F) and steam reforming to produce gaseous components
comprising CO and hydrogen partially combusted in the firs~ stage
of regeneration.
In a more particular aspect, the addition of steam performs the
function of removing heavy adsorbed hydrocarbons by endothermic
conversion to CO and hydrogen under restricted temperature
conditions. The overall effect of the two stage regeneration
operation is to lower the regenerator temperature by removing a
substantial portion of the oxidizable carbonaceous material under
endothermic temperature conditions as herein prov~ded. Thus,
regeneration of the catalyst at any given level of hydrocarbonaceous
deposits in the presence of heavy residual hydrocarbons can be
accomplished at lower temperatures than is possible with oxygen
regeneration alone. Furthermore, one can now effect catalytic
cracking of more higher Conradson carbon crudes without worrying
,20 about high regeneration temperatures in the absence of attendant
processes for removal of these coke producing materials as in now
the current practice t y propane deasphalting, coking, vacuum
distillation, hydrogenation and other processes suitable for the
purpose and combinations thereof. Thus, it is clear that one
following the concepts of this invention can process reduced crudes
and other portions of crude oils oE high Conradson carbon levels
above about 8 such as feed materials of Conradson carbon levels in
the range of 10 to 15 or more.
The fluid catalyst composition contemplated for use in this
invention is a high activity cracking catalyst comprising a
crystalline aluminosilicate or zeolite such as a crystalline "Y"
faujasite catalytically activated by exchange with ammonia or one or
more rare earth metals to remove sodium therefrom. The zeolite is
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dispersed in an amount in the range of about 5 to 60 wt% in a
ma trix material comprising one or more of silica, alumina, or silica
alumina to which matrix material is added a clay material selected
from the group consisting of kaolin, holloysite, montmorilonite, heat
5 and chemically modified clays such ,as meta kaolin and acid treated
holloysite and bentonite. One or more various large pore 2eolites
may be employed in lthe catalyst particle complex in combination with
providing a matrix material of large pore volume in excess of 0. 22
cc~gm and more usually at least about 0.3 cc/gm.
The combination operation of this invention is directed a
temperature controlled heat balance regeneration operation which
employs a novel combination of processing steps for removing high
levels of hydrocarbonaceous deposits of reduced crude cracking
from catalyst particles in the absence of significant hydrothermal
15 degradation of the catalyst particles.
Thus, it is has been found, contrary to the teachings of the
prior art that the high levels of carbonaceous material deposits can
be used to advantage as a protector of the catalyst, cracking
actively during partial removal thereof with steam under conditions
to form syngas compr ising CO and hydrogen . In this operating
environment it is found possible to remove from 40 to 60 wt% of the
deposited carbonaceous material in the first stage of regeneration
by the combination of steam reforming and oxygen combustion for
supplying the endothermic heat requirements of the steam reforming
operation without significantly contributing to hydrothermal
degradation of the catalyst cracking activity concommitantly with
maintaining desired low regeneration temperatures preferably below
about 760C (1400F).
In yet another embodiment, the present invention contemplates
30 the removal of at least a portion of the hydrocarbonaceous deposits
in the first s-tage regeneration operation at temperatures of at least
760C (1400F) by contact with steam and by the reactions of C02
with hydrogen and carbon in the hydrocarbonaceous deposits.
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Thus, the competing reactions of oxygen combustion of
carbonaceous deposits to provide a substantial portion of the
endothermic heat requirements of steam reforming and the reactions
of C02 with carbon and hydrogen in the first regeneration zone so
5 that a majority or greater than 50 wt% of the deposited
hydrocarbonaceous material is intended to be removed in the first
stage of catalyst regeneration wherein the catalyst contacted is
maintained in a dense fluid catalyst bed phase providing relatively
uniform temperature in this firs t regenerator dense catalyst phase
10 operation operates to minirrlize hydrothermal degradation of catalyst
particles not so guardedly contacted.
The catalyst thus partially regenerated and comprising residual
carbonaceous material and more appropriately referred to as residual
carbon is then contacted with an excess of oxygen con taining gas
15 such as air or oxygen modified regeneration gas relying upon a
second dense fluid catalyst bed phase contributing to uniform
temperature combustion of residual carbon on the catalyst particles.
It will be recognized by those skilled in the art that ~he
concentration of catalyst particles forming the dense fluid beds of
20 catalyst particles may be varied over a considerable range of about
20 pounds per cubic foot up to about 35, 40 or even more pounds
per cubic foot. Generally, the concentration of particles will be
within the range of 35 to 40 pounds per cubic foot. In the
regeneration sequence contemplated by this invention, it is intended
25 to reduce residual carbon of regenerated catalyst to a level of at
least 0 . 05 wt% or less without exceeding catalyst regeneration
temperatures of about 760C (1400F) or significantly
hydrothermally deactivating the catalyst.
Brief Description of the Drawings
Figure I is a diagramma tic sketch in elevation of one
arrangement of apparatus for practicing the catalytic concession of
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reduced crudes anà effecting regeneration of the catalyst so used
in a plurality of dense fluid catalyst beds following the concepts
and techniques of this invention.
Figure II is a graph depicting a first study directed to the
5 removal of coke from a catalyst with steam.
Figure III is a graph depicting the effect of steam at 787C
(1450lF) on surface area of a co~mercially available catalyst with
and without coke deposits identified as GRZ-1 by Davidson Chemical
Company .
~igure IV is a graph depicting the effect of steam contact time
on the catalyst zeolite intensity whether coked or not coked.
Discussion of Specific Embodiments
Referring now to Figure 1 by way of example, there is shown
a riser cracking zone, a catalyst disengaging and stripping zone
adjacent ~o a two stage catalyst regeneration arrangement stacked
one above the other so that flue gas products of the bottom
regeneration section can pass upwardly into the bottom portion of a
20 dense fluid bed of catalyst being regenerated in the upper
regeneration section.
In this arrangement of the drawing, Figure 1, a reduced crude
is charged by conduit 1 in admixture with one or more of steam
naphtha and water, as a diluent material, temperature adjustment
25 material, velocity providing material feed partial pressure reducing
material and a combination thereof to assure intimate rapid atomized
and vaporized contact of the reduced crude with charged finely
divided fluidizable catalyst particles to provide. an upwardly flowing
suspension at a temperature of at least about 510C (950F) and
30 sufficien tly elevated to provide a riser outlet temperature in the
range of 510C to 566C (950F to 1050F). The upwardly flowing
suspension in riser 4 is at a velocity to provide a hydrocarbon
residence time within the range of 0. 5 to 4 seconds and more
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usually in the range oE 1 to 2 seconds. Short residence time may
also be provided by charging the reduced crude through inlet
means above the riser bottom as by inlet 2 and 7 shown in the
presence of suitable diluent material. Steam, naphtha or other light
5 hydrocarbons may initially fluidize the catalyst charged to the riser
bottom before contact with reduced crude charge by ei$her conduit
2 or 7. At the riser exit 8, the suspension following traverse of
the riser is separated so that vaporous materials pass through
cyclones for removal by conduit 12 and separation in downstream
10 equipment not shown. Separated catalyst particles are collected in
an annular stripping zone 14 for countercurrent contact with
stripping gas such as steam introduced by conduit 16. Stripped
catalyst particles comprising a heavy load of hydrocarbonaceous
deposits and metal contaminants pass from stripper 14 by conduit 18
15 to a dense bed of catalyst 22 in the upper portion of regeneration
zone 20. Catalyst bed 22 comprises the first stage of regeneration
in accordance with the processing concepts of this invention. That
is, regeneration gas such as air introduced by conduit 24 is mixed
with steam introduced by conduit 25 and the mixed gasiform
material, predominantly steam at a temperature in the range of
143C to 238~C (290F to 460F) is charged to plenum chamber 26
and thence by distributor arms 27 to a bottom portion of bed 22 for
admixture with flue gases obtained as provided below and charged
through openings 29. That is, separator baffle means 28 is
provided with a plurality of small openings represented by 29 for
passage of flue gases therethrough and obtained from the second
stage of catalyst regeneration discussed below.
It is contemplated modifying the arrangement above discussed
so that the baffle 28 is now porous and the flue gases of the
30 second stage regeneration comprising bed 34 are caused to flow into
the plenum 26 for admixture with steam prior to entering bed 22 by
distributor arms 27. On the other hand flue gases from bed 34 may
be passed through external cyclones for removal of catalyst fines
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returned to bed 34 before passing the flue gases freed of catalyst
in admixture with steam to a bottom portion of bed 22.
In any of the above arrangements, the catalyst in dense fluid
bed 22 is partially regenerated with oxygen containing gases
5 furnished by the flue gases obtained from the lower bed 34 and
being enriched with an air-steam mixture added by gas distributor
arms 27 connected to plenum 2'7 . Par tial regeneration of the
catalyst in bed 22 is accomplished ~mder steam reforming conditions
at temperatures within the range of 677C to 815C (1250F to
10 1500F). Flue gas products of regeneration pass through cyclone
separator means 30 before being withdrawn by conduit 32 for use as
desired .
The partially regenerated catalyst in bed 22 is passed to
suitable withdrawal wells communicating with standpipes 36 and 40.
15 All or a portion of the catalyst may be passed by either one or
both of standpipes 36 and 40 to catalyst bed 40 in the lower
regenerator section. Heating or cooling of the catalyst in standpipe
36 may be accomplished in zone 38 as desired.
In the lower catalyst regeneration zone comprising bed 34,
20 complete regeneration of the catalyst to provide a residual carbon
content less than 0.1 wt% and preferably no more than 0.05 wt% is
accomplished with an oxygen containing regeneration gas such as
air, air modified with C02, C02 modified with oxygen and a
combination thereof as required to effect removal of residual
25 carbonaceous material without exceeding a temperature of 815C
(1500F) and preferably without exceeding a temperature of 760C
(1400F) .
The transfer of catalyst from upper bed 22 to lower bed 34
may also be accomplished by one or more internal standpipes rather
30 than by the external standpipes shown.
The catalyst regenerated to a desired low level of residual
carbon by the combination operation above discussed and at a
desired elevated temperature is passed from catalyst bed 34 by
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standpipe 44 to a lower portion of riser 4 for re-use in the system
as above described.
Referring now to Figure 2, by way of example, there is
provided a graph directed to presenting data directed to carbon
5 removal with steam from, a GRZ-l cracking catalyst (commercially
available catalyst from W. R. Grace & Co - Davidson Chemical
DiYision) which had been coke with Arabian Light Reduced Crude.
The graph shows that the reaction of steam to remove coke or
carbonaceous material is relatively just for significant amounts of
10 coke removal within a time span commensurate with that obtainable
in a dense fluid catalyst bed regeneration operation. For example,
a catalyst comprising about 5.8 wt~ carbon on catalyst is reduced to
a residual carbon level of about 1.0 wt% when contacted with 787~C
~1450F) steam for 2 hours. More significant, coke removal is
achievable with steam at temperatures of about 760C (1400F~ to
form CO and hydrogen which are combustible with added oxygen to
generate needed endothermic heat.
Figures 3 and 4 on the other hand show the effect of 787C
(1450F) steam on a coked and uncoked GRZ-1 catalyst with respect
20 to surface area and zeolite intensity. Zeolite intensity is identified
with the active zeolite component or the catalyst, the greater the
intensity, the more of the active crystalline 2eolite component. The
graphical data of Figures 3 and 4 show that steaming of the
uncoked catalyst gave a much larger drop in surface area and
25 zeolite intensity then obtained when contacting a coked catalyst with
high temperature steam. Thus, the coke on the catalyst guards the
deactivation of the ca talyst against high temperature steam . This
finding is used to advantage in pursuit of the concepts of this
invention which is directed to reducing the temperature of
30 regeneration of catalysts used in reduced crude cracking. Catalyst
so used are known to accumula te large amounts of carbonaceous
material attributable in substantial measure to the Conradson carbon
level of the feed being processed and such high levels of deposited
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carbonaceous materials are instrumental in causing high
temperatures to be encountered by burning removal thereof with
oxygen containing gas such as air in the absence of extreme
caution, heat dissipation and restrict temperature sequential
S burning in a plurality, of regeneration ~ones, all of which
techniques are less than desirable. It will be recogni2ed by those
skilled in the art that the regeneration combination of this invention
is not only a unique approach to the removal of relatively large
amounts OI carbonaceous deposits but so also is the amount of
carbonaceous material to be removed by burning with oxygen
containing gas sufficiently reduced to permit maintaining desired
temperature restrictions l~elow 760C (1400F) and more preferably
at the lowest temperature conditions promoting extended catalyst life
and usage. Perhaps more important is the realization that the
regeneration concept of sequence of performance permits the
processing oE higher Conradson carbon feeds than previously
considered possible at relatively low temperatures particularly
suitable for achieving desired hydrocarbon conversion resul~s.
Thus, the endothermic conversion of carbonaceous deposits (coke3
with s-team to a more favorable level for complete removal of residual
carbon with oxygen containing gas measurably improves the
economics restraints with respect to processing more oi the bottom
of the barrel of the crude oil and identified more particularly as a
reduced crude comprising carbo-metallic impurities.
Having thus generally described the new and novel concepts of
this invention with respect to regenerating catalyst particles to
reduce the temperature of the operation and discussed specific
examples in support thereof, it is to be understood that no undue
restrictions are to be imposed by reasons thereof except as defined
by the following claims.
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