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Feb. l, 1949.,
J. w. WARD
2,460,464
CATALYTIC CONVERSION. 0F HYDROCARBONS
Filed Sept. 50, .1943
NN.
¿aß
Q
Patented Feb. 1, 1949
¿ 2,460,404
UNITED sTATEs PATENT _oFFlcE
2,460,404
CATALYTIC CONVERSION 0F
HYDROCARBONS
John W. Ward, Chicago. Ill., aslignor to Universal
Oil Products Company, Chicago, Ill.. a corpora
tion of Delaware
Application September 30, 1943, Serial No. 504.460
l'l Claims. (Cl. 196-52)
l
.
2
,
The invention relates to an improved process
zone of the series, and thencewith the initial>
for the catalytic cracking of hydrocarbon oils to
produce high yields of good quality motor gaso
charging oil through the third reaction zone
above mentioned. Vapors and gases from the
lineor gasoline fractions suitable as base stock
aforementioned -fractionating step are further
fractionated to separate light components, in
cluding normally gaseous fractions, from selected
for aviation gasoline.
The invention embodies a plurality of inter
related and concomitantly operated cracking
higher boiling fractions thereof. and the latter _
steps through which the catalyst employed for
are supplied to the first ‘cracking step of the
promoting the cracking reaction is passed serially
from which the` resulting conversion prod
without intermediate regeneration. The hydro 10 series,
ucts pass'through the second and third cracking
carbons to be converted comprise a plurality of
steps, as previously mentioned.
normally liquid cracking stocks possessing differ
In the specific operation above described, the '
ent degrees of susceptibility to catalytic crack
stock supplied-to the _ñrst cracking step of the
ing treatment. The cracking zone or step to which
the least susceptible or most refractory cracking 15 series consists of or comprises fractions boiling
within the range of gasoline which are retreated
stock is supplied receives fresh or freshly re
generated catalyst; oi relatively high activity.
In the one or more succeeding steps, the iluid
conversion products, resulting from the cracking
treatment aiïorded said relatively refractory
cracking stock, are further contacted with the 20
under suitable conditions in the presence of the
freshly regenerated and relatively highly active
catalyst to improve their characteristics and par
ticularly to reduce their oleñn content and make
them more susceptible to improvement in anti
knock
value by the addition of antlknock agents,
same catalyst which now has a somewhat reduced
such as lead tetraethyl, for example. 'I'he term
activity due to the deposition of a deleterious
“catalytic cracking” as herein used is intended
contaminants thereon in the initial step. In ad
to
include a retreating operation of this type,
dition, a cracking stock which is more susceptible 25
although
it involves other reactions in addition
to cracking treatment than that first mentioned
to cracking.
is also suppiled to the subsequent cracking step
The invention is, of course, not limited to the
andcontacted with the partially contaminated
specific
operation above outlined and I specili
catalyst to eiïect cracking of said less refractory
cally contemplate an operation in which two or
stock.
Two or more successive cracking steps through 30 more cracking >stocks of different refractivity to
cracking are catalytically cracked in the succes
which the catalyst is passed in series before be
sive reaction zones of the system through which
ing regenerated may be employed within they
the catalyst is passed. The various cracking
scope of the invention and the contaminated
stocks may be from any source and each or any
catalyst from the ilnal step of the series is re
of them may consist of fresh charging oil for the
generated to remove combustible contaminants . process
or may .comprise mixtures of fresh charg
therefrom and restore its activity, following which ' ing
oil and intermediate liquid conversion prod
it is returned to the initial cracking step.
ucts of the process of similar cracking suscep
As an example of one specific mode of opera
tibility. The reaction zone of the series to which
tion provided by the invention, a _reaction vessel
each individual cracking stock is supplied will
in which the cracking reactions are conducted is
depend upon the cracking susceptibility of that
divided into three separate reaction zonesv
particular stock. The most active catalyst is
through which subdivided solid cracking catalyst
used to promote the conversion of the most re
is passed in series. A iluid-like bed of the crack
ing catalyst is maintained in each of the reaction 45 fractory stock and vice versa. In other words,
catalyst of decreasing activity ls contacted with
zones and an initial charging stock, comprising
the vvarious cracking stocks in the order of their
a virgin hydrocarbon oil, is passed only through
increasing susceptibility to :catalytic cracking.
the last zone of the series, together with fluid
The'relative refractiveness or cracking sus
conversion products from the two preceding
zones. Resulting fluid conversion products from l50 ceptibility of the oil supplied to each of the re
action zones is preferably determined on the basis
the last zone of the series are fractionated to
of its characterization factor. The characteriza
separate gasoline or naphtha fractions of the
tion factor of an oil is a numerical designation '
desired end-boiling point and gases from selected
'now commonly understood in the art, indicat
higher boiling fractions which are condensed in
ing the relative paraiiinicity of the oil.` As ap
the fractionating step as reñux condensate.
plied to pure individual hydrocarbons, the charac
This selected reflux condensate, which is more re
fractory. to cracking than the initial charging
oil, is supplied to the second reaction zone of the
terization factor (K) may be defined as the
cube root of the absolute boiling point of the`
hydrocarbon, in degrees Rankin, divided by its
series, through which it passes in -commingled
specific gravity at 60° F. However, in dealing
state with ñuid >products from ythe ñrst reaction 60 with complex mixtures
of the nature of most-
2,460,404
cracking stocks, the characterization factor of
the oil may be defined as the cube root of its
cubic average boiling vpoint in degrees Rankin,
divided by its specific gravity at 60° F. The cubic
average boiling point can be estimated from the
volumetric average boiling -point by subtracting
successfully cracked with catalysts of interme
diate activity. For example, the total redux con
densate formed by fractionation of the vaporous
products resulting from the cracking of a highly
paraftlnic oil may be successfully further con
verted to produce additional yields of good quality
gasoline, using a catalyst containing from 1% to
from the latter a correction factor obtained by a
3% by weight of deposited contaminants.
correlation between the volume average boiling
The invention takes advantage of the above
point and the slope of the Engler distillation curve
findings by operating the regenerating step of the
10
for the oil (see article by Smith & Watson, In
process to reduce the catalyst deposits to a rel
dustrial & Engineering Chemistry, Dec. 1937).
atively low value suitable for promoting cracking
When the oil has a characterization factor of 12
of the most refractory cracking stock to be con
or more. it is considered predominantly paraillnic.
verted therein and using the resulting partially
spent
catalyst to promote the conversion of one
. rafiinicity of the oil also decreases and its re 15
or more less refractory stocks before it is again
fractivity to cracking increases. For example, an
regenerated.
oil having a characterization factor of 12 is ma
Another _important feature of the invention
terially more susceptible to cracking than an
resides in the provision for passing ñuid con
oil having a characterization factor of say 11.80
version products resulting from the cracking
and an oil having a characterization factor of say 20 treatment of a relatively refractory stock through
11.87 has an intermediate cracking susceptibility.
the successive reaction zone or zones ofthe series
Assuming then that- the present process is op
with the additional less refractory stock or stocks
erated employing three different cracking stocks
supplied thereto. This not only affords more pro
having the characterization factors 12.25, 11.80
longed
conversion time for the more refractory
and 11.72, for example, using the same catalyst 25 cracking stock, as compared with that afforded
successively in the several cracking steps without
those of a less refractoryanature. but also in
intermediate regeneration, the fresh or freshly re
creases the space velocity in those reaction zones
generated catalyst is first employed in the reac
of the series to which the less refractory stocks
tion zone to which the cracking stock having the
are supplied, as compared with the space velocity
K value of 11.72 is supplied. It is next used in the 30 employed in the preceding reaction zone wherein
reaction zone handling the cracking stock having
the more refractory stock is converted. This ap
the K value of 11.80 and then is employed to crack
plies, of course, to operations in which the cata
the stock having the K value of 12.25, following
lyst bed in each reaction zone contains substan
which the catalyst is regenerated and returned to
tially the same quantity of catalyst, and the rela
35
the first mentioned cracking step. This general
tive space velocities in the several zones may be
principle of employing catalyst of increasing
varied within reasonable limits to suit require
cracking activity for stocks of decreasing crack
ments by ~varying the catalyst inventory therein.
ing susceptibility is employed in the preferred
The term “space velocity" as herein used refers
embodiment of the invention regardless of the
to the quantity of hydrocarbons contacted in a
40
source of the particular stock being treated in the
given time with the unit quantity of catalyst in
As the characterization factor decreases, the
respective cracking steps.
_ ‘
It will be understood, of course, that the de
creasing activity of the catalyst passing through
the reaction zone.
It can conveniently be ex
pressed as pounds of hydrocarbons passed through
the reaction zone per hour, per pound of catalyst
the successive reaction zones is due principally to
present in the reaction zone. ,
45
the accumulation thereon in each zone of dele
The feature of increasing space velocity in the
terious combustible conversion products result
successive reaction zones is advantageous in that
ing from the cracking reaction conducted there
the relatively refractory cracking stocks are ad
in. When, as in the preferred embodiment of the
vantageously converted at a relative low space
invention, the catalyst bed in each zone is main
velocity, while higher space velocities can be suc
tained in a fluid-like condition, the activity of the 50 cessfully employed to advantage on less refrac
catalyst throughout each individual bed .of the
tory stocks. For example, the retreatment of
series will be substantially uniform due to the
oleflnic gasoline and naphtha fractions to reduce
turbulence and mixing obtained therein, but its
their bromide number and increase their lead
average activity will be somewhat lower in each
susceptibility, not only requires a relatively active
successive bed due to the accumulation of con 55 and clean cracking catalyst, but also requires rel
taminating deposits thereon.
atively low space velocities, preferably within the
With catalyst of the preferred type ëmployed
range of 0.25 to 1, or thereabouts. Highly paraf
- in the present process, I have found that cata
finic higher boiling oils on the other hand are ad
lyst which carries a substantial deposit of the
vantageously cracked at higher space velocities
60
heavy combustible products known as “catalyst
which may range, for example, from l to 8, or
coke” are entirely satisfactory for promoting the
conversion of oils having a relatively high char
acterization factor.
For example, catalyst con- o
taining 3 to 4% by weight or thereabouts of such
deposits is still active for promoting the conver
sion of oils having a characterization factor of
thereabouts, depending upon their characteriza
tion factor and the type of product desired.
The passage of fluid hydrocarbon conversion
products from the reaction zone in which a rela
tively refractory stock is converted through the
successive zone in which a less refractory stock
is converted, offers the further advantage of re
having a relatively low characterization factor,
ducing the effective operating pressure in the zone
such as, for example, oleiinic gasoline fractions
handling the stock which is most susceptible to
70
and naphtha, require for best results in their
cracking, thus reducing thermal cracking of the
cracking or retreatment a relatively clean and
stock which is most susceptible thereto. Thermal
more highly active catalyst containing, for ex
cracking is detrimental in that it degrades the
ample, not more than about 1% by weight of
quality of the gasoline product as compared with
say 11.80 to 12 or more. On the other hand, oils
“catalyst coke" and preferably less. Oils having
that obtained by catalytic cracking.
an intermediate characterization factor can be 75
2,460,404
The cracking catalyst preferably employed in
ence of catalyst which has previously served to
promote the cracking reaction in reaction- zone
A, as the oil passes with the conversion products
from the latter zone through the fluid-like bed in
reactor B.
Another stream of hydrocarbons to be con-_
verted is supplied to the upper portion of reac
the present process is of the siliceous type com
prising a composite of silica with one or more
metal -oxides of which alumina, zirconia and mag
nesia are the most commonly employed. Such
catalyst and various satisfactory methods of pre
paring the same are now well known in _the art
and the present invention is not concerned with _
tion zone B beneath the third member 4 through
their specific composition or method of prepara
tion, except that they are‘preferably low in or
substantially free of alkali metal compounds.
Either a treated natural clay or similar alumino
line I3 and commingles therein with the vaporous
and gaseous hydrocarbon conversion products
passing from the iluid bed in this zone and the
mixture transports catalyst particles from the
- silicate or a catalyst prepared by any of the sev
-eral synthetic methods may be employed within
the scope of the invention. Removal of all or
substantially all alkali metal compounds con
tained in the raw materials during some stage
inthe preparation of the catalyst is necessary to
avoid rapid degradation or destruction of its ac
tivity by regeneration at the relatively high tem
fluid bed in reaction zone B through member 4
into the iluid'~1ike bed of catalyst maintained in
reaction zone C. The hydrocarbons supplied
through line I3 are of a less refractory nature
or’more susceptible to cracking treatment than
those» supplied through line I2 and suitable con
` peratures commonly employed.
The accompanying drawing diagrammatically
illustrates one speciflc form of apparatus em
bodying the features of the invention and in
which the improved process may be conducted. 25
Referring to the drawing, reactor I is a ver
tically elongated, substantially cylindrical vessel
ditions of temperature, pressure and space ve
locity for cracking the same are maintained in
the reaction zone C as they pass upwardly
through the fluid bed in this zone in contact with
the catalyst which has been previously used for
promoting the conversion reaction in reaction
zones A and B.
-
'I'he lifting action of the vapors and gases on
the catalyst particles is largely overcome by the _
force of gravity in the upper portion of zone C
closed at its opposite ends by the respective ‘bot
tom and top heads 2 and 3. The interior of the
and a light phase I0, of materially lower cata
vessel is divided into the reaction zones A, B and
C by the spaced perforate partition members 4 30 lyst particles concentration than that prevailing
which may be Àperforate platesv or other suitable ,
in the fluid beds, is maintained above the upper
extremity, indicated approximately at 1, of the
grid-like structures .extending over the _cross- '
sectional area of the vessel at spaced points in its
height and secured to the cylindrical shell of the
reactor. The members 4 also serve as distributing
means for substantially evenly distributing cata
lyst particles and fluid reactants `and conversion
products over the horizontal cross-section of the
vessel.
fluid bed in reaction zone C. Vaporous and
gaseous conversionl products of the cracking re
'_' action conducted in reaction zones A, B and C
are directed with entrained catalyst particles
from the light phase Ill in reaction zone C
through line I4 to suitable catalyst separating
40
-A bed of subdivided solid catalyst is disposed
within the reactor above the partitioning and dis
tributing mem-bers 4 in each of the reaction zones
A, B and C. In the embodiment of the invention
here illustrated, these catalyst beds are each kept 45
i _ in a fluid-like condition by passing fluid hydro
carbon reactants to rbe converted and resulting
fluid conversion products upwardly therethrough
at-a velocity suillcient to partially counteract the
equipment, such as, for example, the cyclone
separator indicated at I5, wherein at least a
major portion of the entrained catalyst is sepa
rated from the hydrocarbon vapors and gases.
The separated catalyst particles are returned
from separator i5 through standpipe I 6 to the
fluid-like catalyst bed in reaction zone C, in the
case illustrated. However, when desired, cata
lyst from separator I5 may be returned to any
or in part to each of the fluid beds in the
force of gravity on the catalyst particles.
60 reaction zones A, B and C or it may be supplied
A stream of fresh catalyst particles or catalyst
directly to the'regenerating step of the process
regenerated. as will be later described, is supplied c
by well known means, not illustrated. Hydro
to the space within the cone bottom 2 beneath the
carbon vapors and gases are directed from the
lowermost member 4 and is picked up and carried
upper portion of lseparator I5 through line i1
into the iluid bed in reaction zone A by an in 55
coming stream of hydrocarbons to be converted,
which is supplied to the lower portion of the re
to fractionation, as will be later> described, in
fractionator I8.
.
-A stream of catalyst particles containing con
actor through line I I. Conditions of temperature,
taminating deposits accumulated thereon in re-_
pressure and space velocity, suitable for substan
tial cracking of the oil supplied through line II 60 action zones A, B and C is withdrawn from the
are maintained in zone A as it passes upwardly ’ fluid-like bed in the latter zone beneath the
dense phase level 'l and directed through trans
through the fluid-like catalyst bed in this zone.
fer line I9 and the adjustable oriilce or flow
Another stream of hydrocarbons to be con
control valve 20 to the catalyst regenerating step
verted, of a less refractory nature than the oil
of
the process. In the case illustrated, transfer
supplied through line II, is introduced into the 65
line I9 extends into the space 33 provided within
upper portion of reaction zone A beneath the sec
the cone-like bottom head of the regenerating
ond perforate member 4 through line I2 and com
vessel 2i and is picked up by an incoming> stream
mingles with the hydrocarbon vapors and gases
of air or other oxidizing gas employed for effect
passing fromthe fluid bed in this zone and the
mixture carries catalyst particles from the latter 70 ing regeneration of the catalyst. 'I'he oxidizing
gas is supplied to the lower portion of the re
through the perforate member r4 into the fluid
generator through line 22 and valve- 23 and
like bed maintained in reactor B. Suitable con- .
transports Ythe catalyst particles from line I9
ditions of temperature, pressure and space veloc
ity are maintained in reaction zone B for crack
ing the oil supplied through line i2, in the pres
through the perforate distributing member 24,
provided adjacent the juncture of the conical
75 lower head with the cylindrical shell of vthe re
2,460,404
7
The arrangement here illustrated permits the
generator, into the fluid-like bed 25 of catalyst
particles maintained within the regenerating
use of any one or several selected intermediate
liquid products as all or a portion of the crack
zone. The approximate upper extremity of this
ing stock supplied through lines II and I2 to the
fluid bed is indicated at 25 and a light phase 21
respective reaction zones A and B. For example,
of materially reduced catalyst particle concen
a selected relatively heavy fraction of the reflux
condensate formed in fractionator I8 and with
drawn from the lower portion of this zone
plied to the lower portion of the regenerator,
through line 42 to pump 44 may be directed, all
transfer line I9 may terminate at any desired 10 or in part, through valve 58 in line 45 and
through line 59 to heater 68, and thence through
point Within the ñuid bed 25.
'
Combustion gases resulting from the regener
line I2 into reaction zone B in the manner previ
tration is maintained above the fluid bed in the
regenerator. When desired, instead of being sup
ating operatlon and entrained catalyst particles
ously described. Alternatively, a selected'light
are directed from the light phase 21 in the re
fraction of the reflux condensate formed in frac
tionator I8' and withdrawn through line 38 to
generator through line 28 to the catalyst sepa
-rator 29 wherefrom separated catalyst particles.
pump 38 may be directed, all or in part, from
are returned through standpipe 30 to the fluid
line 39 through line 5I, valve 52 and line 59 to
bed 25 in the regenerator. The combustion gases
heater 50 and thence through line I2 to reaction
are directed from the upper portion of the sepa
zone B, or a regulated quantity or all of the light
rator through line 3| and valve 82, preferably
reñux condensate may be directed through valve
to suitable heat recovery equipment, not illus 20 53 in line 39 and through line 54 to heater 55
and thence through line I I into reaction zone A.
trated.
A stream of regenerated catalyst is withdrawn
Another alternative mode of operation is to with
draw the total reflux condensate formed in frac
-from the fluid `bed 25 in the regenerator and
directed through transfer line 34 and the adjust I3 ,al tionator I8 through line 42 and return all or a
regulated portion thereof via pump 44, line 45,
able orifice or flow control valve 35 into the low
er portion of reactor I, wherein itis picked up by
valve 58, line 59, heater 58 and line I2 to reac
the incoming stream of hydrocarbons from line
tion zone B.
4
,
A similar arrangement is provided, in the case
II and passes in series, as previously described,
through the fluid beds in reaction zones A, 30 illustrated, for supplying a portion or all of the
reflux condensate formed in fractionator 48 to
B and C.
further conversion in reaction zone A. Selected
The fractionation afforded the vaporous and
heavy fractions of the reflux condensate formed
gaseous conversion products from line I1 in frac
tionator I8 separates normally gaseous com
in fractionator 49 may be directed from the lower
ponents and light normally liquid fractions of 35 portion thereof through line 55 and valve 51 to
pump 58 and thence through line 59, valve 10,
the desired end-boiling point from the higher
boiling fractions which are condensed as reflux
condensate in this zone. In the case illustrated,
line 54, heater 55 and line II to reaction zone A.
Selected light fractions of the reflux condensate
formed in fractionator 49 may be ' directed
different boiling range characteristics are with- . 40 through line 1I and valve 12 to pump 13 and
two selectedvstreams of reiiux condensate of
drawn from fractionator I8. The lighter stream
is directed through line 35 and valve 31 to pump 38
thence through line 14, valve 15, line 84, heater
55 and line II to reaction zone A. Alternatively,
the total reflux condensate formed in fraction
from which it is directed through line 39 and may,
ator 49 may be withdrawn from the lower por
when desired, be discharged, all or in part, from
tion of this zone to pump 68 and supplied, all or
the system to cooling and storage, or elsewhere as
in part, when desired, to reaction zone A. Pro
desired, through line 48 and valve 4I. Heavier
vision is also made for removing all or a portion
fractions of the reñux condensate formed in
of the total or the heavy reflux condensate
fractionator I8 are directed from the lower por
formed in fractionator 49 from the system
tion of this zone through line 42 and valve 43
to pump 44 wherefrom they are directed through 50 through line 15 and valve 11 `communicating
with line 59. Similarly, a portion or all of any
line 45 and may, when desired, be discharged,
light reñux condensate withdrawn from frac
all or in part, from the system through line 45
tionator 49 may be supplied to cooling and stor
and valve 41 to cooling and storage or elsewhere,
age or elsewhere, as desired, through line 18 and
as desired.
Fractionated vapors and gases of thev desired 65 valve 19 communicating with line 14.
end-boiling point, preferably including substan
tially all of the gasoline fractions, are directed
from the upper portion of fractionator I8
through line 48 to fractionator 49, wherein a
When desired, regulated quantities of the dis
tillate, comprisinggasoline fractions of the de
sired end-boiling point collected in receiver 53,
may be supplied to reaction zone A for retreat
further separation between light and heavy com- _ 00 ment to improve their quality.` When this mode
ponents thereof is effected. The'lighter frac
tions, preferably including substantially all of the
normally gaseous products and light gasoline
fractions, are directed from the upper portion
of the fractionator through line 58 to condenser
5I wherefrom the resulting distillate and un
condensed and undissolved gases are directed
through line 52 to collection and separation in
receiver 53. The uncondensed and undissolved
of operation is employed, distillate may be sup
plied from receiver 53 through line 88 and valve
8I to pump 82 from which it is supplied through
line 83, valve 84, line 54, heater 55 and line II
to the reaction zone A.
Fresh charging oil for the process, which is
preferably a straight-run distillate, such as gas
oil or the like, having a relatively high charac
terization factor as compared with the other oils
gases are discharged from the receiver through a.' O converted within the system, is supplied through
line 54 and valve 55 to storage or preferably to
line 85 and valve 85 to pump 81 wherefrom it is
suitable gas concentrating and recovery equip
fed through line 88, valve 89, heater 98 and line
ment, not illustrated. Distillate, such as selected
I3 to cracking treatment in reaction zone C.
light gasoline fractions, may be directed from re
When desired, in addition to or instead of sup
ceiver 53 through line 55 and valve 51 to storage
plying selected intermediate liquid products of
or elsewhere, as desired.
2,460,404
the process to cracking treatment in reaction
ployed in the present process. The weight hourly
zone `B, another cracking stock from an external
source, having a lower characterization factor
v
than that supplied through line B5, is directed
through line 9| and valve 92 to pump 93 by means
of which it is fed through line 94, valve 95, line
59, heater 60 and line I2 to cracking treatment
space velocities employed in the.reaction zones
may range from 0.25 to 8 or thereabouts. Space
velocities of a relatively low order, say 0.5 to 1,
are preferred for highly refractory stocks (those
having a low characterization factor), While
higher space velocities are advantageously em
in reaction zone B.
ployed in stocks having higher characterization
The invention also contemplates the use of
another stream of extraneous oil as all or apor 10 factors. Also space velocities of a somewhat high
er order may be employed for the production of
tion of the cracking stock supplied to reaction
motor gasoline, as compared with those most
zone A. This material may be supplied through
suitable for the production of aviation base stock.
line 96 and valve 91 to pump 98 wherefrom it is
I'claim:
'
fed through line 99, valve |00, line 84, heater
~65 and line II to reaction zone A.
The purpose of heaters 65, 60 and 90 is to pre»
1. A catalytic cracking process which com
prises introducing relatively clean and active sub- .
cracking stock supplied to the.resp'ective reac
tion zones A, B and C through lines- I I, I2 and I3
and, in the preferred embodiment of the inven
tion, heaters 60 and 90 also preferably supply to 20
series of at least three reaction zones maintained
divided solid cracking catalyst to the ñrst of a
heat and preferably substantially vaporize the
the respective cracking stocks passing there
under cracking conditions, passing catalyst from
the first to the second and from the second to
the third zone of the series whereby to maintain
a continuous flow of catalyst through said series
of zones, introducing to said third zone a hydro
through the heat necessary to bring them to or
carbon charging oil heavier than gasoline and
somewhat above the reaction temperature em
therein'cracking a substantial portion thereof in
ployed in the particular reaction zone to which
this oil is supplied. The hot regenerated catalyst 25 contact with used catalyst from said second zone,
supplied to the reactor through line 34 Will fur
nish a substantial portion of the required heat
for conducting the cracking reactions in zones
A, B and C and may, when desired, also furnish 30
heat for vaporizing and/or for bringing the
cracking stock supplied to zone A to the desired
reaction temperature. Thus, heater 65 may be
eliminated, when desired. The heaters 60, 65 and
90 may be of any suitable form and are illus
trated only in a conventional manner in the
drawing.
-
.
Preferably, the stream of catalyst particles
passing through line I9 is substantially stripped
of occluded light hydrocarbons,- prior to its in
removing cracked vapors and catalyst from the
third zone and fractionating the vapors to con
dense and separate hydrocarbons heavier than
gasoline, introducing at least a portion of the
last-named hydrocarbons to said second zone
and therein subjecting the same to further crack
ing in contact with used catalyst from said ñrst
zone, passing resultant cracked vapors from the
second zone to the third zone for further treat
ment therein, and passing an oleñnic gasoline
fraction serially through said first, second and
third zones in the order named under conditions
to reduce the oleñn content thereof.
2. A catalytic cracking process which com
troduction into the regenerating zone. This is 40 prises introducing relatively clean and active sub
‘ divided solid cracking catalyst to the first of a
accomplished inthe case illustrated by introduc
ing regulated quantities of`steam or other suit
able relatively inert or non-combustible gas into
series of at least three reaction zones maintained
under cracking conditions, passing catalyst from
line I9 through line IOI and valve |02 on the 45
upstream yside of the adjustable orifice >or ñow
control valve 20. Similarly, steam or other rela
tively inert gas is supplied in regulated amounts
to line 34 on-the upstream side of the adjustable
A oriñce or ñow control valve 95 through line I 03 50
and vvalve |04, to substantially strip the stream
of catalyst passing through this line of _oxidizing
gas and combustion gases. The gas thus'supplied
to lines I9 and 34 also serves vto aerate and pre
vent excessivey compaction of the catalyst col
55
umns in the transfer lines, so as to> insure the
ing a substantial portionV thereof, removing from
the third zone the vaporous conversion products
of said distillate and charging oil and fractionat
ing the same to condense and separate fractions
continuous flow of catalyst particles there
thereof heavier than gasoline, and introducing-
, temperature, pressure, space velocity, etc., for
ñuidized beds of subdivided solid cracking catalyst
through.
at least a portion of the last-named fractions to
A detailed recitation of operating conditions
sultable for conducting the process with speciñc
treatment therein.
- ,
cracking stocks of various characterization fac 60
3.
A
catalytic
cracking
process
which
com
tors is considered unnecessary to an understand
prises maintaining a series oi’ vertically disposed
ing of the invention, since suitable conditions of
cracking various types of oils are known to those 65 under cracking conditions, supplying relatively
active catalyst particles to the lowermost bed of
familiar with the art. In general, however, tem
peratures ranging from 850 to 1050° F. are most
commonly employed with the silica-alumina type
cracking catalysts in common use. The operating
pressure in the reaction zones may range from
substantially atmospheric »to several hundred
pounds, superatmospheric, and a moderately
fractionating the same to separate insuñiciently
converted fractions thereof, introducing at least
superatmospheric pressure of from 5 to 50 pounds
a portion of said fractions to a bed of said series
gauge, or thereabouts, is preferred in operations
of the fluid bed type such as preferably em 75 below said uppermost bed for further conversion
therein, and introducing resultant vaporous con
2,460,404
11
version products containing suspended catalyst
particles to the uppermost bed.
4. A catalytic cracking process which comprises
maintaining a series of reaction zones under
12
product from said cracking zone by fractionation
a lowe boiling product fraction, a high boiling
fractio and an intermediate fraction consisting
largely of uncracked and partially cracked prod
ucts of said feed, contacting at least a portion of
said intermediate fraction with the hot freshly
cracking conditions, supplying relatively active
subdivided solid cracking catalyst to the first zone
regenerated catalyst from said regeneration zone
’ of the series and removing contaminated catalyst
. and passing the mixture to said cracking zone by .
particles from the last zone ofthe series, intro-~`
ì
introducing said mixture at the bottom of said
ducing a virgin petroleum oil to said last zone of
bed of iluidized _nnely divided cracking catalyst,
the series and therein eñecting substantial> crack
ing thereof, removing the cracked vapors and
fractionating the same to separate insufficiently
converted fractions thereof, introducing at least
thereby to simultaneously crack said fresh hydro
carbon feed and said recycled fraction in the'
same bed of fiuidized finely divided cracking
a portion of said fractions to a zone of the series
ing contact of'thesaid fresh hydrocarbon feed
with said hot freshly regenerated catalyst.
catalyst at differentv space velocities while avoid- '
preceding said last zone for further conversion
therein, and introducing resultant vaporous con
7. In a process for the catalytic cracking of a
version products containing suspended catalyst
hydrocarbon oil> to produce
particles to said last zone of the series.
5. In a process for the catalytic cracking of a
- ucts of lower molecular weight and boiling point Y
hydrocarbon oil to produce valuable normally
gaseous and normally liquid hydrocarbon prod
yucts of lower molecular weight and boiling point
in a catalytic cracking system using a iluidized
finely divided cracking catalyst, the method of
operation comprising the steps of introducing a
in a catalytic .cracking system using a fluidized
finely divided cracking catalyst, the method of
operation comprising the steps of introducing the
valuable normally .
gaseous and normally liquid -hydrocarbon prod
straight run gas oil at one or more intermediate
of continuously replenished
fiuidized finely divided cracking catalyst consti
` points into a bed
fresh hydrocarbon oil feed to be cracked at one
tuting the cracking zone wherein it is catalytically
cracked in the presence o_f recycle stock intro
or more intermediate points into a bed of con
tinuously replenished iluidized finely divided
cracking catalyst constituting the cracking zone
wherein it is catalytically cracked in the presence
duced as hereinafter specified, continuously with
drawing spent catalyst from said fluidized bed
and continuously regenerating said spent catalyst
of recycle stock introduced as hereinafter speci
in a separate regeneration zone by burning car
fled, continuously withdrawing spent catalyst
bonaceous deposits therefrom, separating from
from said nuidized. bed and continuously re
the product from said cracking zone by fraction
generating said withdrawn spent catalyst in a 35 ation a lower boiling product fraction and a
separate regeneration zone by burning carbon
higher boiling fraction consisting largely of un
aceous deposits therefrom, separating from the
cracked and partially cracked products of said
product from said cracking zone by fractionation
feed, contacting at least a portion of said higher
a lower boiling product fraction and a higher
boiling recycle fraction consisting largely of un
-li
cracked and partially cracked products of said
feed, contacting at least a portion of said higher
boiling fraction with the hot freshly regenerated
catalyst from said regeneration zone and passing
the mixture to said cracking zone by introducing
said mixture at the bottom of said bed of ñuidized
nnely divided cracking catalyst, thereby to simul
taneously crack said fresh hydrocarbon feed and
said recycled fraction in the same bed of fiuidized
finely divided cracking catalyst at different space
velocities while avoiding contact of the said fresh
hydrocarbon feed with said hot freshly regener
ated catalyst.
Ã
.
6. In a process for the catalytic cracking of a
'
produce valuable normally
gaseous and normally liquid hydrocarbon prod
hydrocarbon oil to
boiling fraction with thekhot freshly regenerated
catalyst from said regeneration zone and passing
the mixture to the cracking zone by introducing
said mixture at the bottom of said bed of fluidized
finely divided cracking catalyst, thereby to simul
taneously crack said hydrocarbon feed and said
recycled fraction in the same bed of ñuidized
velocities while avoiding -contact of the fresh
hydrocarbon feed with said hot freshly'regener
ated catalyst.
JOHN W. WARD.
REFERENCES CITED
The following references are of record in the
tile of this patent:
1,367,341
Joseph ........... _- July 19, 1932
ucts of lower molecular weight and boiling point
2,235,133
Zimmerman ______ _- Mar. 13, 1941
in a catalytic cracking system using a fluidized
2,296,722
Marancik, et al ___-- Sept. 22, 1942
finely divided cracking catalyst, the method of
operation comprising the steps of introducing the
2,298,355
2,300,032
Viiiglcii' ____________ __ oct. 13, 1942
Kassel ____________ __ oct. 27, 1942
fresh hydrocarbon oil feed to be cracked at one or
more intermediate points into a bed of con
2,304,128
Themas ____ _; ..... __ Dec. a, 1942
2,322,794
Egioir ___________ _. June 29, 1943
2,326,705
2,327,175
2,328,754
Thiele, et a1 ______ -_ Aug. 10, 1943
Conn ____________ __ Aug.'17, 1943
Thomas __________ -_ sept. 7, 1943
2,356,697
Rial ____________ -_ Aug. 22, 1944`
2,339,573
2,377,613
creelman __________ _- Jaa 4, 1944
Conn ............. -_ June 5, 1945
2,379,711
Hemminger ........ __. July 3, 1945
tinuously replenished ñuidized finely divided
cracking catalyst constituting the cracking zone
wherein it is catalytically cracked in the presence
of recycle stock introduced as hereinafter speci
fied, continuously withdrawing spent catalyst
fromV said ñuidized bed and continuously re
withdrawn spent catalyst in a
separate regeneration zone by burning carbon
aceous deposits
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