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Патент USA US2118605

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May 24, 1938. . '
2,118,605
L. c. HUFF
PROCESS FOR CRACKING HYDROCARBONOILS
Original Filed Nov. 13, 1950
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INVENTOR
LYMAN C. HUFF
ATTORNEY
Patented May 24, 1938
2,118,605
UNITED STATES PATENT OFFlCE
2,118,605
PROCESS FOR CRASIIEISNG HYDROC‘ARBON
Lyman O. Huff, Chicago, 111., assignor, by mesne
assignments, to Universal Oil Products Com
pany, Chicago, 111., a corporation of Delaware
Application November 13, 1930-, Serial No. 495,394
Renewed November 2, 1934
1 Claim.
(Cl. 196-48)
This invention relates to the cracking or ther
mal decomposition of hydrocarbon oils, and more
particularly refers to the treatment of relatively
heavy hydrocarbon oils under cracking condi
5 tions to produce maximum quantities of more
from the secondary fractionating column of the
primary or relatively low temperature cracking
system.
Oil of this character may, for exam
ple, be obtained from another cracking system
valuable products.
Primarily, the present invention comprises sub
using a secondary dephlegmator, or from the re- 5
distillation of pressure distillate. A portion of
this same oil, or similar product, may, if desired,
jecting intermediate products from a liquid-vapor
phase or relatively low temperature cracking sys
be fed directly into the heating element of the
vapor phase or relatively high temperature crack
10 tem to reconversion in a vapor phase or rela—
ing system, thereby increasing the total charge 10
tively high temperature cracking system and re
turning intermediate products from said rela
tively high temperature system to the heating ele
ment of the relatively low temperature system
fed to the system. This oil may also be employed
to assist fractionation of the vapors in the de
phlegmator of the secondary or vapor phase sys
tem.
for reconversion.
In its speci?c embodiment, the process of the
invention comprises subjecting an oil to liquid
vapor phase or relatively low temperature crack
ing conditions in a primary heating element, in
troducing the heated materials into an enlarged
reaction zone, subjecting vapors from said reac~
tion zone to fractionation in a primary dephleg
The accompanying drawing illustrates dia- 15
grammatically, and not to scale, one speci?c
form which‘ the apparatus of the present inven
mator, from which the heavier portion of the
vapors is returned as re?ux condensate to the
primary heating element for reconversion, and
light uncondensed vapors from which are sub
jected to further fractionation in the secondary
fractionating column, subjecting the light uncon
densed portion of the vapors from the secondary
fractionating column to condensation, cooling
and collection, returning the heavier condensed
portion of the vapors from the secondary frac
tlonating column to retreatment under vapor
phase or relatively high temperature cracking
“ conditions in a secondary or vapor phase heat
ing element, introducing heated products from
tion will assume.
Other features of the inven
tion will be apparent with reference to this draw
ing. Raw oil charging stock supplied through line
l and Valve 2 to pump 3 may be fed through
lines 4 and 5 and through valve 6 into dephleg
mator ‘l where it assists fractionation and cool
ing of the vapors in this zone by direct con
tact therewith, and may pass together with the
insuf?ciently converted portion of the vapors
which are condensed in dephlegmator 1, through
line 8 and valve 9, back into line It and thence
to pump 1. A portion or all of the raw oil charg
ing stock, instead of passing overhead to dephlegmator ‘I, may pass directly through valve H in
line 4 to pump 16. Pump l0 supplies the charg
ing stock and reflux condensate from dephleg
mator '1 through line I2 and valve 13 to heat
ing element 14. Heating element It is located
in a suitable form of furnace i5 and the oil
passing therethrough is brought to the desired
said secondary heating element into a separate,
enlarged reaction zone, vapors from which are conversion temperature, and passes through line
16, and valve ll into reaction chamber l8.
subjected to fractionation in a vapor phase de
Separation of vapors and liquid is permitted
phlegmator and their lighter constituents sepa
rately condensed and collected and returning the in chamber 18, the latter being withdrawn from
heavier condensed portion of the vapors from the the system or to further treatment through line
vapor phase dephlegmator to the primary or liq ' i9, controlled by valve 20, or, ‘if desired, condi
uid vapor phase heating element for reconversion. tions may be so maintained in chamber l8 such
that the residual product remaining therein is
As a feature of the present invention, I pro
vide for the introduction of an extraneous oil reduced to substantially dry coke, in which case
into the stream of reconverted oil discharging no liquid residue is withdrawn during the opera
tion, and the coke produced may be removed at
from the secondary or vapor phase heating ele
ment to partially cool the stream of heated oil the end of the run. Vapors from reaction cham
and prevent excessive formation of coke and ber l8 pass through line 2i and valve 22 into dephlegmator l, where they are subjected to frac
gas. Extraneous oil of any desirable charac
teristics from any source may be employed for tionation, their heavier, condensed portion re
turning, as already described, to heating element
this purpose, but preferably I utilize an oil simi
14 for reconversion, and their lighter, uncon
lar in characteristics to the re?ux condensate,
densed portion passing through line 23 and valve
55 commonly termed “pressure distillate bottoms”,
20
25
30
35
40
45
50
55
2
2,118,605
24 to fractionating column 25. The vapors are
subjected to further fractionation in column 25,
their lighter, uncondensed portion comprising
preferably material boiling within the range of
motor fuel withdrawn through line 26 and valve
21, is subjected to condensation and cooling in
condenser 28, thereafter passing through line
29 and valve 30 into receiver 3|, where it is col
lected as distillate and uncondensable gas. Dis
10 tillate may be withdrawn from receiver 3| through
line 32 and valve 33.
Gas is released from the
receiver through line 34, controlled by valve 35.
Re?ux condensate formed in fractionating col
umn 25, which in most cases will correspond in
15 characteristics to what is commonly termed
“pressure distillate bottoms”, is withdrawn from
this zone through line 36 and valve 3'! and fed
by means of pump 38 through line 39, valve 40
and line 4| into heating element 42. An ex
20 traneous oil or secondary charging stock, pref
erably similar in characteristics to the re?ux
condensate from fractionating column 25, and
supplied from any desirable source, for example,
another cracking system, through line 43 and
25 valve 44, may be fed by means of pump 45, through
valve 46 in line 4| into heating element 42.
Heating element 42 is located in a suitable
furnace setting 41 and the oils passing through
from through line 19 and valve 80 into line l2,
and thence to heating element M for reconver
sion. It will be understood that if extraneous
oil or secondary charging stock is fed through
line 64 to dephlegmator 63, as described, the ma
jor portion of this material thus fed will also be
supplied, together with a re?ux condensate from
dephlegmator 63, to heating element 54.
It will also be understood that the usual ex
pedients such as returning a portion of the ?nal 10
distillate from the system to the zone in which
it is produced may be employed to assist fraction
ation and to maintain the desired outlet tem
peratures from the various fractionating zones,
thus assisting in controlling the quality of the 15
?nished product. In this particular case, dis
tillate from receivers 3| and/or 1| may be re
turned to any or all of the dephlegmators l, 25,
and 63 by well-known means, not shown.
Pressures employed within the system may 20
range for subatmospheric to high superatmos
pheric pressures of 1500 pounds or more per
square inch. The primary and secondary crack
ing system may be operated under substantially
the same or under different pressures, and equal 25
ized or differential pressures may be maintained
between the various elements of each system.
Cracking temperatures employed may range
this heating element are raised to a conversion
30 temperature, preferably higher than that em
from about 750 to some 1200" F. more or less.
Preferably, milder cracking conditions are em 30
ployed in heating element l4, and are discharged
through line 48 and valves 49 and 50 into reaction
chamber 5|. Provision is made for the intro
duction of a portion or all of the extraneous oil
35 or secondary charging stock from pump 45 into
the stream of heated and. reconverted material
element 42.
As a speci?c example of the operation of the
process, such as above described, two charging
stocks are supplied to the system, one, a fuel oil 35
from heating element 42. This is accomplished
by diverting the oil from line 4|, through line
52 and valve 53 into line 48. This feature is pro
vided for the purpose of cooling the stream of
heated ?uid from heating element 42 to a point
where undesirable secondary cracking reactions
will not occur, thus eliminating or materially re
ducing the excessive coke and gas losses char
45 acteristic to vapor phase cracking reactions.
Separation of the liquid and vapor is permitted
in reaction chamber 5|. The liquid withdrawn
through line 54 and valve 55 to pump 56 may, all
or in part, be discharged from the system through
line 51 and valve 58, or may be fed through line
59 and valve 60 into line |2 and thence to heating
element l4 for reconversion. Vapors from re“
action chamber 5| pass through line 6| and
valve 62 into dephlegmator 63, where they are
subjected to fractionation, assisted, if desired,
by a portion of the extraneous oil or secondary
charging stock from line 43, supplied through
pump 45, line 64 and valve 65 to dephlegmator
63 into direct contact with the vapors in this
The lighter portions of the vapors from
60 zone.
dephlegmator 63, preferably comprising mate
rial boiling Within the range of motor fuel, are
withdrawn through line 66 and valve 61, sub
jected to condensation and cooling in condenser
65 68 and thence passed through line 69 and valve
10 to be collected in receiver 1|, distillate from
which is withdrawn through line 12 and valve
13, and uncondensable gas from which may be
released through line 14, controlled by valve 15.
Re?ux condensate from dephlegmator 63, com
prising the heavier or insu?iciently converted
portion of the vapors from the vapor phase or
relatively high temperature cracking reaction,
are withdrawn from dephlegmator 63 through
line 16 and valve 11 to pump 18 ‘and fed there
ployed in heating element l4 than in heating
of about 26° A. P. I. gravity, being the charging
stock to the primary or relatively low tempera
ture system, represents about 70% of the total
charge, while the secondary charging stock, fed
in part direct to the secondary or relatively high 40
temperature heating element and in part into
the stream of heated products discharging from
this same heating element, represents about 30%
of the total charge and corresponds in charac
teristics to the additional material supplied to 45
this heating element from the secondary frac
tionating column of the primary system. Re?ux
condensate from the dephlegmator of the pri
mary system is returned to the heating element
of the same system for reconversion, and re?ux 50
condensate from the dephlegmator of the sec
ondary system is also returned to the primary
heating element. A temperature of approxi
mately 925° F., and a pressure of about 230
pounds per square inch is maintained in the
heating element of the primary system. This
pressure is substantially equalized throughout the
reaction chamber and primary dephlegmator.
It is reduced to about 60 pounds per square inch
in the secondary fractionating column and in 60
succeeding parts of the primary system. A tem
perature of approximately 1100° F. is main
tained at the outlet from the secondary heating
element, but this temperature is reduced to ap
proximately 875" F. in the reaction chamber of
the secondary system by the introduction of sec
ondary charging stock into the stream of heated
material entering this chamber from the heat
ing element. A pressure of about 150 pounds per
square inch is maintained throughout the sec 70
ondary cracking system. In an operation such
as above outlined, a yield of approximately 65%
of ?nished motor fuel having anti-knock value
equivalent to a blend of 50% benzol with 50%
straight run Pennsylvania gasoline may be pro 75
3
2,118,606
duced. Based on the total charging stock, about
17% of substantially dry coke is produced in the
primary reaction chamber and about 6% of re
sidual oil is recovered from the reaction cham
ber of the secondary system. This latter may,
if desired, be returned to the primary heating
element, and when the process is so operated the
gasoline yield may be increased by a little less
than 4%, with a slight increase in coke and gas
10
formation.
7
Having thus described my invention, what I
claim is:
The process of treating hydrocarbon oils that
comprises subjecting hydrocarbon oil in a ?rst
cracking zone to a substantially liquid phase
cracking temperature’ to e?ect conversion of the
high boiling hydrocarbon oils into lower boiling
hydrocarbon oils, vaporizing the lower boiling
hydrocarbons of the cracked products, withdraw
20 ing the unvaporized oil from the system, frac
tionating the evolved vapors in a ?rst fraction
ating zone to form a gasoline-like vapor fraction,
a lighter reflux condensate and a heavier re?ux
condensate, returning the heavier condensate to
said liquid phase cracking operation, subjecting
said lighter condensate to a vapor phase cracking
temperature in a second cracking zone, contact
ing relatively heavy fresh charging stock with
the resulting vapors from the vapor phase crack
ing operation to thereby vaporize a portion of the
fresh charging stock, withdrawing the unvapor~ 1O
ized portion of the charging stock from the sys
tem, dephlegmating the combined vapors from
the vapor phase cracking operation and the va—
pors from the fresh charging stock in a second
fractionating zone to produce a vapor fraction 15
suitable for the production of gasoline and a re
flux condensate suitable as a clean cracking stock
and charging said clean cracking stock to the
liquid phase cracking operation.
20
LYMAN C. HUF'F.
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