U.S. patent number 3,622,498 [Application Number 05/004,909] was granted by the patent office on 1971-11-23 for slurry processing for black oil conversion.
This patent grant is currently assigned to Universal Oil Products Company. Invention is credited to Laurence O. Stine, Frank Stolfa.
United States Patent |
3,622,498 |
Stolfa , et al. |
November 23, 1971 |
SLURRY PROCESSING FOR BLACK OIL CONVERSION
Abstract
A catalytic slurry process for effecting the conversion of a
hydrocarbonaceous charge stock containing asphaltenes and metallic
contaminants. The slurry constitutes the charge stock, hydrogen, a
portion of the previously produced product effluent and from about
1.0 to about 25.0 percent by weight of finely divided catalyst
particles. Preferred catalysts are the unsupported sulfides of the
metals from Groups V-B, VI-B and VIII. A series of product
separation steps facilitates catalyst circulation, catalyst
withdrawal, and recovery of a substantially catalyst-free
product.
Inventors: |
Stolfa; Frank (Park Ridge,
IL), Stine; Laurence O. (Western Springs, IL) |
Assignee: |
Universal Oil Products Company
(Des Plaines, IL)
|
Family
ID: |
21713130 |
Appl.
No.: |
05/004,909 |
Filed: |
January 22, 1970 |
Current U.S.
Class: |
208/108; 208/215;
502/31; 208/102; 208/251H |
Current CPC
Class: |
C10G
45/16 (20130101); C10G 49/22 (20130101) |
Current International
Class: |
C10G
45/02 (20060101); C10G 45/16 (20060101); C10G
49/00 (20060101); C10G 49/22 (20060101); B01j
011/74 (); C10g 013/06 (); C10g 023/16 () |
Field of
Search: |
;208/108,215
;252/414,439 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Gantz; Delbert E.
Assistant Examiner: Schmitkons; G. E.
Claims
We claim as our invention:
1. A process for converting an asphaltene-containing
hydrocarbonaceous charge stock which comprises the steps of:
a. forming a reactive slurry of said charge stock, hydrogen and a
finely divided catalyst containing at least one metal component
from the metals of Groups V-B, VI-B or VIII;
b. reacting said slurry in a reaction chamber at cracking
conditions including a pressure above about 1,000 p.s.i.g. and a
temperature above about 800.degree. F.;
c. separating the resulting cracked product effluent in a first
separation zone, at substantially the same pressure and a
temperature below about 900.degree. F., to provide a first vaporous
phase and a first catalyst-containing liquid phase;
d. separating said first vaporous phase in a second separation
zone, at substantially the same pressure and a lower temperature of
from 60.degree.to about 140.degree. F., to provide a second liquid
phase and a second vapor phase, recycling at least a portion of the
latter to combine with said charge stock and catalyst;
e. separating said first liquid phase in a third separation zone,
at substantially the same pressure and a lower temperature of from
500.degree.to about 850.degree.F., to provide a third liquid phase
and a catalyst-containing fourth liquid phase;
f. separating said second and third liquid phases, in a fourth
separation zone at conditions of temperature and pressure to
provide a heptane concentrate, a light cycle oil concentrate and a
catalyst-containing fifth liquid phase;
g. separating said fifth liquid phase and at least a portion of
said light cycle oil in a fifth separation zone, to provide a sixth
liquid phase substantially free from said catalyst and a
catalyst-containing seventh liquid phase; and,
h. removing the catalyst from said seventh liquid phase in a sixth
separation zone.
2. The process of claim 1 further characterized in that said
catalyst-containing fourth liquid phase is recycled to combine with
said charge stock.
3. The process of claim 1 further characterized in that said sixth
liquid phase is introduced into said fourth separation zone.
4. The process of claim 1 further characterized in that at least a
portion of said heptane concentrate is introduced into said sixth
separation zone.
5. The process of claim 1 further characterized in that said
catalyst is a sulfide of at least one metal from Groups V-B, VI-B
or VIII.
6. The process of claim 5 further characterized in that said
catalyst is a vanadium sulfide.
7. The process of claim 1 further characterized in that said
cracked product effluent is separated in said first separation zone
at a temperature of from 700.degree.to about 900.degree. F.
Description
APPLICABILITY OF INVENTION
The process described herein is applicable to the conversion of
petroleum crude oil residuals having a high metals content and
comprising a hydrocarbon-insoluble asphaltene fraction. More
specifically, our invention is directed toward a method for
effecting a catalytic slurry process, in the presence of hydrogen,
in order to convert atmospheric tower bottoms, vacuum column
bottoms, crude oil residuals, topped and/or reduced crude oils,
coal oil extracts, crude oils extracted from tar sands, etc., all
of which are commonly referred to in the art as "black oils."
Petroleum crude oils, and particularly the heavy residuals obtain
therefrom, contain sulfurous compounds in exceedingly large
quantities, nitrogenous compounds, high molecular weight
organometallic complexes principally comprising nickel and vanadium
as the metallic component, and hydrocarbon-insoluble asphaltenic
material. The latter is generally found to be complexed with
sulfur, and, to a certain extent, with the metallic contaminants. A
black oil is generally characterized in petroleum technology as a
heavy hydrocarbonaceous material of which more than about 10.0
percent (by volume) boils above a temperature of about
1,050.degree. F. (referred to as nondistillables) and which further
has a gravity less than 20.0.degree. API. Sulfur concentrations are
exceedingly high, most often in the range of about 2.0 percent to
about 6.0 percent by weight. Conradson carbon residue factors
generally exceed 1.0 percent by weight and the concentration of
metals can range from as low as 20 p.p.m. to as high as about 750
p.p.m. by weight.
The process encompassed by the present invention is particularly
directed toward the conversion of those black oils contaminated by
large quantities of insoluble asphaltenes and a high metals
content-- i.e. containing more than about 150 p.p.m. by weight.
Specific examples of the charge stocks to which the present
technique is adaptable, include a vacuum tower bottoms product
having a gravity of 7.1.degree. API and containing 4.1 percent by
weight of sulfur and 23.7 percent by weight of heptane-insoluble
materials; a "topped" Middle East crude oil having a gravity of
11.0.degree. API and containing about 10.1 percent by weight of
asphaltenes and 5.2 percent by weight of sulfur; and, a vacuum
residuum having a gravity of 8.8.degree. API, containing 3.0
percent by weight of sulfur and 4,300 p.p.m. by weight of
nitrogen.
The utilization of our invention affords the conversion of such
material into distillable hydrocarbons, heretofore having been
considered virtually impossible to achieve on a continuous basis
with an acceptable catalyst life. The principal difficulty,
heretofore encountered in a fixed-bed catalytic system, resides in
the lack of sufficient stability of the catalyst in the presence of
such relatively large quantities of metals-- i.e. from about 150
p.p.m. to as high as 750 p.p.m., computed as the elements-- and
additionally from the presence of large quantities of asphaltenic
material and other nondistillables. The asphaltic material
comprises high molecular weight coke precursors, insoluble in light
normally liquid hydrocarbons such as pentane and/or heptane. The
asphaltic material is generally found to be disbursed within the
black oil, and, when subjected to elevated temperature, has the
tendency to flocculate and polymerize whereby the conversion
thereof to more valuable oil-soluble products becomes extremely
difficult.
Candor compels recognition of the many slurry-type processes which
have heretofore been proposed. Regardless of the various operating
and processing techniques, the principal difficulty resides in the
separation of the reaction product effluent to provide
substantially catalyst-free distillable product, internal catalyst
circulation and "spent" catalyst withdrawal. Success has been
achieved only through the use of intricate equipment at
prohibitively high costs. An obvious alternative is to utilize the
black oil as the charge to a coking unit for the production of coke
and distillable hydrocarbons. In view of the steadily increasing
demand for distillable hydrocarbons, particularly motor fuels, jet
fuels and stocks for conversion into liquefied petroleum gas,
coking is no longer suitable because of its relatively low yield of
distillable hydrocarbons. Our invention provides a slurry process
having a series of separation steps integrated therein. There is
afforded, thereby, a more economical and less difficult process
from the standpoint of the desired product recovery, internal
catalyst recirculation and catalyst withdrawal.
OBJECTS AND EMBODIMENTS
A principal object of our invention is to convert nondistillable
hydrocarbonaceous material into lower boiling distillable
hydrocarbons. A corollary objective is to provide a catalytic
slurry process for the hydrogenative conversion of an
asphaltene-containing black oil charge stock.
Another object is to convert a black oil charge stock into
distillable hydrocarbons with minimum yield loss to unconvertable
asphaltic residuum.
Still another object of our invention is to provide a catalytic
slurry process which facilitates separation of the cracked product
effluent, internal catalyst circulation and catalyst
withdrawal.
Therefore, in one embodiment, our invention provides a process for
converting an asphaltene-containing hydrocarbonaceous charge stock
which comprises the steps of:
a. forming a reactive slurry of said charge stock, hydrogen and a
finely-divided catalyst containing at least one metal component
from the metals Groups V-B, VI-B, and VIII;
b. reacting said slurry in a reaction chamber at cracking
conditions including a pressure above about 1,000 p.s.i.g. and a
temperature above about 800.degree. F.;
c. separating the resulting cracked product effluent in first
separation zone, at substantially the same pressure and a
temperature below about 900.degree. F., to provide a first vaporous
phase and a first-catalyst containing liquid phase;
d. separating said first vaporous phase in a second separation
zone, at substantially the same pressure and a lower temperature of
from 60.degree. to about 140.degree. F., to provide a second liquid
phase and a second vapor phase, recycling at least a portion of the
latter to combine with said charge stock and catalyst;
e. separating said first liquid phase in a third separation zone,
at substantially the same pressure and a lower temperature of from
500.degree. to about 850.degree. F., to provide a third liquid
phase and a catalyst-containing fourth liquid phase;
f. separating said second and third liquid phases, in a fourth
separation zone at conditions of temperature and pressure to
provide a heptane concentrate, a light cycle oil concentrate and a
catalyst-containing fifth liquid phase;
g. separating said fifth liquid phase and at least a portion of
said light cycle oil in a fifth separation zone, to provide a sixth
liquid phase substantially free from said catalyst and
catalyst-containing seventh liquid phase; and,
h. removing the catalyst from said seventh liquid phase in a sixth
separation zone.
Other embodiments of our invention are directed toward particular
operating techniques and preferred ranges of operating variables
and conditions. Thus, the process is further characterized in that
the catalyst-containing fourth liquid phase is recycled to combine
with the charge stock. The catalyst concentration, within the
slurry being introduced into the reaction chamber, is in the range
of from about 1.0 to about 25.0 percent by weight, based upon fresh
feed charge stock, and preferably from 2.0 to about 15.0
percent.
SUMMARY OF INVENTION
The particular finely divided, solid catalyst utilized in the
present slurry process, is not considered to be essential. However,
it must be recognized that preferred catalytically active metallic
components possess both cracking and hydrogenation activity. In
most applications of our invention, the catalytically active
metallic component, or components, will be selected from the metals
of Groups V-B, VI-B and VIII of the Periodic Table. Thus, in
accordance with The Periodic Table of the Elements, E. H. Sargent
and Company, 1964, the preferred metallic components are vanadium,
chromium, iron, cobalt, nickel, niobium, molybdenum, tantalum
and/or tungsten. The noble metals of Group VIII, namely ruthenium,
rhodium, palladium, osmium, iridium, and platinum, are not
generally considered use in a slurry-type process in view of the
economic considerations involved with these relatively expensive
metals. The foregoing metallic components may be combined with a
refractory inorganic oxide carrier material, including alumina,
silica, zirconia, magnesia, titania, mixtures of two or more, etc.,
the final composite being reduced to a finely divided state. In
such a composite, the active metallic components may exist in some
combined form such as the oxide, sulfide, sulfate, carbonate, etc.
However, recent investigations and developments in catalytic slurry
processing of heavy hydrocarbon charge stocks have indicated that
the sulfides of the foregoing metals, and particularly those of
Group V-B, offer advantageous results. Furthermore, the process
appears to be facilitated when the sulfide of the metal is
unsupported, as contrasted to being combined with a refractory
inorganic oxide carrier material. For this reason, the preferred
unsupported catalyst for use in the process of the present
invention, comprises tantalum, niobium or vanadium sulfides, the
latter being particularly preferred. In the interest of brevity,
the following discussion will be limited to the use of vanadium
sulfides, in an amount of about 1.0 to about 25.0 percent by
weight, as the catalyst in the present slurry process.
Regardless of the character of the catalyst, it may be prepared in
any suitable, convenient manner, the precise method not being
essential to the present invention. For example, vanadium sulfides
may be prepared by reducing vanadium pentoxide with sulfuric acid,
sulfur dioxide and water to yield a solid hydrate or vanadyl
sulfate. The latter is treated with hydrogen sulfide at a
temperature of about 300.degree. C. to form vanadium tetrasulfide.
Reducing the vanadium tetrasulfide in hydrogen, at a temperature
above about 300.degree. C., produces the vanadium sulfide slurried
into the system. As hereinbefore set forth, the concentration of
vanadium sulfide is preferably within the range of about 2.0 to
about 15.0 percent by weight, calculated as the elemental metal.
Excessive concentrations do not appear to enhance the results, even
with extremely contaminated charge stock having exceedingly high
asphaltene contents.
DESCRIPTION OF DRAWING
In the accompanying drawing, illustrating one embodiment of the
present invention, a simplified flow diagram is utilized. Details
such as pumps, instrumentation and controls, heat exchange and heat
recovery circuits, valving, startup lines and similar hardware have
been omitted; these are considered nonessential to an understanding
of the techniques involved. The use of such miscellaneous
appurtenances, to modify the illustrated process flow, are well
within the purview of those skilled in the art. Similarly, it is
understood that the charge stock, stream compositions, operating
conditions, catalyst, design of fractionators, separators and the
like are exemplary only, and may be varied widely without departure
from the spirit of our invention, the scope of which is defined by
the appended claims.
The drawing will be described in connection with a Laguna reduced
crude having a gravity of about 9.8.degree. API, and initial
boiling point of 560.degree. F., a 10.0 percent volumetric
distillation temperature of 700.degree. F., a 30.0 percent
volumetric distillation temperature of 851.degree. F. and a 50.0
percent volumetric distillation temperature of 1,000.degree. F.
Contaminating influences include nitrogen in an amount of 5,190
p.p.m. by weight, 9.55 percent by weight of heptane-insoluble
material, 2.80 percent by weight of sulfur, about 438 p.p.m. by
weight of vanadium and about 74 p.p.m. by weight of nickel. The
crude oil indicates an average molecular weight of 598 and
carbon/hydrogen atomic ratio of about 7.95.
With reference now to the drawing, the reduced crude is introduced
into the process by a way of line 1, and is admixed with a
hydrogen-rich recycle vaporous phase in line 2 and a
catalyst-containing liquid phase from line 3. Following heat
exchange with hot effluent streams, which technique is not
illustrated, the mixture continues through line 1 into heater 4.
With respect to the total charge mixture, the hydrogen
concentration is in the range of about 1,000 to about 50,000
s.c.f./bbl. of fresh charge stock, and preferably from about 5,000
to about 20,000 s.c.f./bbl., and the catalyst concentration is in
the range of about 2.0 to about 15.0 percent by weight of vanadium
sulfide, calculated as elemental vanadium. Heater 4 increases the
temperature of the mixture to a level range of about 800.degree. F.
to about 1,000.degree. F., the heated mixture being introduced into
reaction chamber 6 by way of line 5 at a pressure in the range of
about 500 to about 4,000 p.s.i.g., and preferably from about 1,000
to about 3,000 p.s.i.g. The design of the internals of reaction
chamber 6 are not essential to our invention, and they may be
constructed utilizing well-known devices such as disc and donut
trays, side-to-side pans, etc. Similarly, in order to assure
intimate mixing and contacting of the reactants, a variety of
mechanical devices such as spray nozzles, bayonets, distributing
grids, etc., may be employed. Residence time, within the reaction
chamber depends upon a multitude of considerations. Not the least
of these considerations involve temperature, the degree of mixing,
catalyst concentration, charge stock characteristics, the degree of
conversion and the volumetric ratio of recycle material to fresh
feed. In most applications of our invention, the residence time
will range from about 30 seconds to about 4 minutes.
The reaction zone effluent is withdrawn through line 7 and,
following its use as a heat exchange medium, is introduced thereby
into hot separator 8 at a temperature in the range of about
700.degree. to about 900.degree. F. As utilized herein, the phrase
"pressure substantially the same as" is intended to indicate that
the pressure of a succeeding downstream vessel is the same as that
of the upstream vessel, allowing only for the pressure drop
normally experienced as a result of fluid flow through the system.
The hot separator serves to provide a first principally vaporous
phase, withdrawn as an overhead product by way of line 9,
containing the lighter components of the cracked product effluent,
primarily hydrogen, hydrogen sulfide, ammonia, normally gaseous
hydrocarbons and distillable hydrocarbons boiling below a
temperature of about 900.degree. F. A first principally liquid
phase is withdrawn from hot separator 8 by way of line 14. Hot
separator 8 functions in the manner which provides for the greater
proportion of catalyst being removed in this normally liquid phase.
The first vaporous phase in line 9 is cooled and condensed to a
temperature in the range of about 60.degree. to about 140.degree.
F., and passes therethrough into cold separator 10. A
hydrogen-rich, vaporous phase is withdrawn from cold separator 10
by way of line 2, and recycled therethrough to combine with the
charge stock in line 1. The recycled gaseous phase may be treated
by any means well known in the art for the purpose of removing
hydrogen sulfide and other gaseous components in order to increase
the concentration of hydrogen. Makeup of hydrogen, to supplant that
consumed in reaction chamber 6, is introduced into the process by
way of line 13. The second liquid phase, from cold separator 10, is
withdrawn by way of line 11 and introduced into fractionator
12.
Following its use as a heat exchange medium, the liquid phase
slurry in line 14, at a temperature in the range of about
500.degree. to about 850.degree. F. is introduced into a separation
zone 15. In the drawing, separation zone 15 is illustrated as being
a high-pressure slurry clarifier, and functions to concentrate the
catalyst particles in a liquid phase being withdrawn by way of line
3, and recycled therethrough to combine with the charge stock and
recycle hydrogen in line 1. The quantity of hydrocarbons being
recycled by way of line 3 is such that the combined liquid feed
ratio, to reaction chamber 6, is in the range of about 1.1 to about
6.0, and preferably from about 1.5 to about 3.0. The normally
liquid phase withdrawn as an overhead stream from high-pressure
slurry clarifier 15, by way of line 16, contains from about 0.1 to
about 0.4 percent by weight of catalyst particles, and is
introduced into fractionator 12, preferably at a locus below that
through which the liquid phase in line 11 is introduced.
Fractionator 12 functions at conditions of temperature and pressure
selected to provide (1) a heptane concentrate in line 19, (2) a
light cycle oil concentrate, boiling in the range of about
400.degree. to about 700.degree. F. in line 22 and (3) a
catalyst-containing concentrate boiling above a temperature of
about 700.degree. F. in line 26. In addition to these specifically
designated streams, there is illustrated a typical product recovery
including a normally gaseous overhead in line 17, containing
butanes and lower boiling normally gaseous products, a
pentane/hexane concentrate in line 18 and a heptane-400.degree. F.
boiling range fraction in line 21. The catalyst-containing bottom
stream in line 26, at a pressure of from atmospheric to about 100
p.s.i.g., continues therethrough into a low-pressure slurry
clarifier 27 at a temperature of from 600.degree. to about
800.degree. F. In order to facilitate the separation of the
catalyst particles in clarifier 27, a portion of the light cycle
oil stream is cooled and diverted by way of lines 23 and 25 into
the conical section of clarifier 27. Another portion of the light
cycle oil continues through line 23, being introduced thereby into
high pressure slurry clarifier 15 in the conical section thereof.
With respect to high pressure slurry clarifier 15, the hot
separator bottoms entering by way of line 14 has a density of
approximately 0.6 grams/ml. The catalyst particles settle into the
cone of the clarifier where they are taken up by the light cycle
oil entering the cone by way of line 23, the mixture being recycled
by way of line 3. Since this stream has a density of approximately
0.8 grams/ml., insignificant mixing occurs between the two
hydrocarbon streams, and little catalyst is removed from clarifier
15 by way of overhead line 16. Makeup catalyst is introduced into
the system by way of line 24 and the light cycle oil recycle in
line 23.
A gas oil concentrate is removed from low pressure slurry clarifier
27 by way of line 28. This stream constitutes a product of process,
and although not illustrated in the drawing, may be conveniently
introduced into a typical vacuum column for the purpose of
separating residuum therefrom. A light cycle oil,
catalyst-containing stream is withdrawn from low-pressure slurry
clarifier 27 by way of line 29, and is introduced therethrough into
catalyst separation zone 30. Any suitable means may be utilized to
separate solid catalyst particles from the liquid phase
hydrocarbons, including filtration, settling tanks, a series of
centrifuges, etc. In accordance with our invention, one feature
constitutes introducing a portion of the heptane concentrate from
line 19 into catalyst separation zone 30. The heptane concentrate
is employed to remove residual, soluble hydrocarbons from the
catalyst sludge, the heptane-containing stream subsequently being
introduced into fractionator 12 by way of line 32 and 11. The
catalyst sludge, containing about 2.0 to about 10.0 percent by
weight of the catalyst employed, is considered a drag stream and
may be treated in any manner which produces a vanadium sulfide for
reuse within the process. One such procedure involves burning the
sludge in air, thereby producing vanadium pentoxide. This is
subsequently reduced with sulfur dioxide, sulfuric acid and water
to produce vanadyl sulfate. The procedure then follows the
previously described scheme for the preparation of fresh vanadium
sulfide.
DESCRIPTION OF A PREFERRED EMBODIMENT
This preferred embodiment will be described in conjunction with a
commercially scaled unit processing about 25,000 barrels per day of
Laguna reduced crude. In describing the various separations being
effected, frequent reference will be made to the accompanying
drawing.
The fresh feed charge stock, in an amount of 696 moles/hr., is
admixed with 1,540 moles/hr. of a light cycle oil recycle (about
25,000 bbl./day, providing a combined liquid feed ratio of 2.0)
containing about 17,378 pounds of vanadium sulfide catalyst. The
charge is also admixed with 10,270 moles/hr. of a hydrogen-rich
recycle gas stream (about 8,611 moles of hydrogen) and 3,788
moles/hr. of makeup hydrogen (about 3,725 moles of hydrogen). The
mixture is heated to a temperature of about 825.degree. F., and
enters the reaction chamber 6 at a pressure of about 2,000 p.s.i.g.
After its use as a heat exchange medium, the reaction chamber
effluent is introduced into a hot separator at a temperature of
830.degree. F. and a pressure of about 1,975 p.s.i.g. Component
analyses of the total charge
---------------------------------------------------------------------------
(line 5) and the effluent (line 7), in moles/hr., is presented in
table I.
TABLE I
---------------------------------------------------------------------------
REACTION CHAMBER CHARGE AND EFFLUENT
Component Line 5 Line 7 Fresh Feed 696 -- Ammonia -- 27 Hydrogen
Sulfide 124 332 Hydrogen 12,336 9,223
Methane 1,406 1,658 Ethane 71 177 Propane 43 139
Butanes 13 75 Pentanes 2 2 Pentane--400.degree. F. -- 289
400.degree. f.-650.degree. f. 1,540 2,023 650.degree.
f.-1050.degree. f. -- 490 residuum -- 30
Catalyst 17,378 17,378 In pounds per hour.
__________________________________________________________________________
The vaporous phase from the hot separator (line 9) is cooled and
condensed to a temperature of about 100.degree. F., and is
introduced into a cold separator. The cold separator serves to
provide 10,270 moles/hr. of a hydrogen-rich recycle gas (line 2)
which is admixed with 3,788 moles/hr. of makeup hydrogen, and a
normally liquid phase (line 11) which is introduced into a
fractionator system. The liquid phase from the hot separator (line
14) is passed into a high-pressure (about 1,950 p.s.i.g.) slurry
clarifier at a temperature of about 825.degree. F. A principally
liquid phase (line 16) is introduced into the fractionation system.
Light cycle oil in an amount of 1,540 moles/hr., containing about
306 lbs./hr. of fresh catalyst, is introduced into the slurry
clarifier, at a temperature of 150.degree. F., and recycled (line
3) to combine with the fresh charge stock. Component analyses of
the separation effected in the cold separator 10 are presented in
the following table II:
---------------------------------------------------------------------------
table ii
---------------------------------------------------------------------------
cold separator separation
component Line 9 Line 2 Line 11 Ammonia 25 -- -- Hydrogen Sulfide
195 124 71 Hydrogen 8,747 8,611 136
Methane 1,532 1,406 126 Ethane 95 71 24 Propane 86 43 43
Butanes 20 13 42 Pentanes -- 2 -- Pentane--400.degree. F. 235
237 -- 235 400.degree. f.-650.degree. f. 1,239 -- 1,239 650.degree.
f.-1050.degree. f. 75 -- 75 residuum Tr. -- Tr.
The separation effected in the high slurry clarifier is presented
in table III. The light cycle oil recycle, 1,540 moles/hr. (line
23), introduced into the cone of the clarifier is not listed as
part of the feed (line 14).
---------------------------------------------------------------------------
TABLE III
Component Line 14 Line 16 Line 3
__________________________________________________________________________
Ammonia 2 2 -- Hydrogen Sulfide 137 137 -- Hydrogen 476 476 --
Methane 126 126 -- Ethane 82 82 -- Propane 53 53 --
Butanes 20 20 -- Pentane--400.degree. F. 54 54 --
400.degree. f.-650.degree. f. 784 784 1,540 650.degree.
f.-1,050.degree. f. 415 415 -- residuum 30 30 -- Catalyst * 17,378
306 17,378 **
The total charge to fractionator 12 has the composition presented
in table IV, inclusive of 10 moles/hr. of heptane introduced into
catalyst separation zone 30, and 39 moles/hr. of light cycle oil
introduced into clarifier 27.
TABLE IV
---------------------------------------------------------------------------
FRACTIONATOR FEED COMPOSITION
Component
__________________________________________________________________________
Ammonia 2 Hydrogen Sulfide 208 Hydrogen 612
Methane 252 Ethane 106 Propane 96
Butanes 62 Heptanes 10 Pentane--400.degree. F. 289
400.degree. f. -650.degree. f. 2,062 650.degree. f. -1,050.degree.
f. 490 residuum 30
__________________________________________________________________________
A butane-minus overhead stream, containing about 62 moles/hr. of
butane and 454 moles/hr. of C1-C3, is removed from fractionator 12
by way of line 17. The pentane/hexane concentrate, withdrawn by way
of line 18, is in an amount of 81 moles/hr. Heptane concentrate is
withdrawn by way of line 19, and 10 moles/hr. thereof is introduced
into catalyst separation zone 30, the remainder being diverted via
line 20 as part of the heptane-400.degree. F. product in line 21.
The total heptane-400.degree. F. product is recovered in an amount
of 213 moles/hr. Of the 2,062 moles/hr. of light cycle oil
(400.degree.-650.degree. F.) withdrawn from fractionator 12, 1,540
moles are introduced into high-pressure slurry clarifier 15, and 39
moles/hr. are introduced into low-pressure slurry clarifier 27.
The bottoms from fractionator 12, in the amount of 520 moles/hr.
containing 306 lbs./hr. of catalyst, are introduced into
low-pressure slurry clarifier 27. A gas oil containing stream is
removed by way of line 28, and introduced into a vacuum column (not
illustrated), from which 30 moles/hr. of residuum are removed
(containing about 41 lbs./hr. of catalyst) and 490 moles/hr. of
heavy vacuum gas oil are recovered.
The catalyst and light cycle oil are introduced into a centrifuge
system utilizing 10 moles/hr. of a heptane wash. Catalyst is
recovered in an amount of 265 lbs./hr. and sent to a metal recovery
system.
In summation, on the basis of 696 moles/hr. of fresh feed, or
353,775 lbs./hr., the yields of the various recovered streams are:
17,689 lbs./hr. of residuum, or about 5.0 percent by weight; 490
moles/hr. of a heavy vacuum gas oil; 483 moles/hr. of a light cycle
oil; 81 moles/hr. of a pentane/hexane concentrate; 62 moles/hr. of
a butane concentrate; and, 11,462 lbs./hr. of methane, ethane and
propane, or only about 3.2 percent by weight of the fresh feed
charge stock.
* * * * *