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Патент USA US2130313

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Sept )13, ì938„
2,130,313
J. M. BARRON
CONVERSION OF HYDROCARBON OILS
Filed Ap ril 7 ,
mh
1937
Om
d
h
JOSEPH M. BARRoN
INVENTOR
‘_
BY
ATToRNEY
i
Patented Sept. 13, 1938
l _ 2,130,313
TAT '1.'. s
Prem“ ori-"lcs
2,130,313
.
yCÜNVEJRSIÓN 0F HYDROCARBQN OILS
`l'oseph M. Barron, Port Arthur, Tex., assigner to
'li‘he Texas Company, New York, N. Y., a corpo
ration of Delaware
Application April 7, w37, Serial No. 135,377 Y
‘î Claims.
rI'his invention relates to conversion of hydro
carbon oils and has to do particularly with the
cracking of hydrocarbon oils to lower boiling
’ products, such as gasoline, in a cracking operation
5 involving the principle of gas reversion.
in the cracking of higher boiling oils to lower
boiling products, it has been found advantageous
to carry out the cracking of the heavier oils in
the presence of normally gaseous hydrocarbons.
10 Une source of suchnorrnally gaseous hydrocar
bons is the gases evolved in the cracking opera
tion. In order to recover the normally gaseous
hydrocarbons evolved in the cracking process, it
is advantageous to use a scrubbing medium which
r may conveniently be charging stock to the system.
rThis charging stockenriched with the normally
gaseous hydrocarbons may then be charged to the
cracking zone wherein the higher boiling oil
undergoes cracking in the presence of gaseous
20
hydrocarbons. During the cracking operation
the normally gaseous hydrocarbons enter into the
conversion reactions to produce increased amounts
_ of the desired low boiling liquid hydrocarbons.
‘In accordance with the present invention, the
25 iced stock enriched with the gaseous hydrocar
bons may be charged to the heating and cracking
zone and preferably the gaseous hydrocarbons are
separated from the enriched feed stock and the
gaseous hydrocarbons so separated charged to an
.3 (i intermediate point in the cracking zone.
'
and drum.
.
Referring to the drawing, numeral l represents
the cracking furnace, 2, 3 and ä a series of soak
ing drums, ä a primary fractionator, 6 a second- 5
ary fractionator, ‘l a naphtha stabilizer and t a
gas absorber. The furnace is shown as a vertical,
circular type and the soaking drums as a series
of vertical stills. It is to be understood, how
ever, that any well known type of furnace may lo
be used and one, or more than one, reaction
drum may be employed. The furnace contains
two coils, lil and l2, for cracking the clean oil
and dirty oil respectively. It is intended that
the invention shall not be limited to a two-coil lo
cracking system but instead a single coil may
be used, for example as in semi-clean or super-y
clean circulation; the semi-clean in which the re
cycle stock and charge are cracked in the same
coil; the super-clean in which the distillate re- 2o
cycle stock is cracked in a separate coil and then
combined with the dirty recycle stock or mixture
of charge and dirty recycle stock and sent to a
soaking or coking zone. -lin any of these types
of operation the recycle stock may be combined 25
with the rich oil containing normally gaseous
hydrocarbons, preferably recovered from the sys
tem, the mixture flashed and the normally gase
ous hydrocarbons introduced into the soaking
zone.
More particularly, according to the invention, it
is preferred to employ a cracking operation in
which the cracking is carried out in zones of heat
ing and soaking. A feature of the present in
vention is mixing an oil enriched with the> gase
ous hydrocarbons recovered from the cracking
system with a condensate recycle stock and the
hashing from this mixture the normally gaseous
hydrocarbon fraction which is returned to the
soaking zone of the cracking system.
lThe invention will be more fully understood
from the following description taken in connec
tion with the accompanying drawing which shows
in elevation a‘sketch of‘one form of apparatus
45 for carrying out the process.
(Cl. 15m-9)
out in cracking and soaking zones, such as coil
.
ln practicing the invention with the apparatus
shown, the charging stock, such as gas oil, crude
oil, naphtha, crude residuum etc., is introduced
through the line i5 and forced by the pump i@
through the line il to a heat exchange coil it, 35
located in a reflux condenser section i d, superim
posed on the secondary fractionator t. A, por
tion or all oi the charge may be by-passed
through the line E@ and conducted through the
line 2i to the top of the absorber d as a scrub- 4o
hing medium.
c
v
'
.
In some cases it may be desirable to use a
second oil, such as a special gas oil or naphtha,
as an absorbent or scrubbing medium, and in this '
case such an oil would be introduced through the e5
-
line 23 and forced by the pump 2li through the
line 2i to the absorber 8 by suitable regulation
described for carrying out the process in which a ‘ of the Valve 25 in the line 2i and the valve to
clean and dirty recycle stock are cracked in sep
in the line 2l.’ A portion of this oil may be sent
arate coils, the two streams combined and passed directly through the line di to the heat exchange so
through a soaking'zone. It is to be understood,
ri‘he gases introduced into the absorber d are
however, that the principle of the present inven
tion may be applied to any well known type of l principally butane and lighter and may be- de
cracking operation, for example one operating on rived from the stabilizer l oraccumulator 3U, ,
a recycle basis in which the cracking is carried .both of which communicate with the absorber
In the following description an apparatus is
coil
id.
,
.
.
-
2,130,313
8 through the lines 3| and 32 respectively. These
gases are scrubbed countercurrently with the oil
introduced through the line 2l andthe desired
gases absorbed in the scrubbing medium while
these liquids are continuously withdrawn so as to
maintain a low liquid level in this drum. The
the unabsorbed or iixed gases are released from
liquid products so withdrawn are discharged
through the line 69 by automatic control valve 16
and discharged from the system or further treat
the top of the absorber through the line 34. It
is intended that the Cs and C4 hydrocarbons and
a portion of the C2 hydrocarbons, if desired, may
be absorbed. The rich oil is withdrawn from the
ed, as desired, for example in a tar stripper.
'I‘he vapors are withdrawn from the drum 4
through the line 12 to the fractionator 5. In
the fractionator 5 a heavy condensate is pro-
10 bottom of the absorber through the line 35 in
which is located a pump 36, and combined with
the remainder of the charge in the line I1, if any,
and the mixture conducted to the heat exchange
coil I8, where they pass in indirect heat exchange
15 with the cracked vapors from the system.
The oil is conducted from the coil I8 through .
the line 40 to another heat_exchange coil 4I,
located in the lower portion of the fractionator 6.
'I_’he preheated oil is transferred from the coil 4I
through the _line 42 to a flash drum 44. In the
coil I8 the oil is preheated to a temperature of
about 3D0-325° F. and further heated in the coil
4I to a temperature of ‘15G-500° F. There is also
drawn into the flash drum 44 a dirty cracking
- or recycle stock from theeprimary fractionator 5
through the line 45, in which is located a pump
46. 'I‘he latter oil may be at a temperature of
about 830-860° F. The ñash drum is maintained
under relatively high pressure which may be 400
30 600 pounds per square inch or higher. The pres
sure may be regulated by the valve 41 in the
line 48. It is preferable' to regulate the pressure
to around 420-450 pounds per square inch and at
this pressure gases are released 'through the valve
35 41 and passed through the line 48 to the entrance
of the soaking drum 2. The unvaporized oil in
the flash drum 44 is withdrawn from the bottom
thereof through the line 58 in which is located
a pump 5I. Any proportion of this oil may be
40 introduced into theupper portion of the frac
tionator 5 as a dephlegmating medium through
the branch line 52 controlled by valve 53. 'I‘he
remainder of the charge is conducted through
the line 54 to the dirty oil cracking‘coil Í 2. The
45 temperature of this oil entering the coil I2 is
usually around 750-800° F. In the coil i2 the
oil is raised to a temperature of about S30-890° F.
and then discharged into the line 56 leading to
the soaking drum 2.
A clean recycle stock is withdrawn from the
bottom of fractionator 6 through the line 60 and
forced by the pump 6i to the clean oil heating
coil I0. A portion of the clean recycle stock may
be withdrawn from the line 60 through the by
55 pass line 62, cooled in the cooling coil 63 and the
cooled product by-passed through the line 64 to e
the upper portion of the fractionator 5 as a re
flux medium. The recycle stock is heated to a
temperature. of about S50-1000*’ F. and then
60 mixed with the hot products from the residuum
heating coil I2. The mixture at a temperature
of about SOO-910° F. is then passed through the
line 58 wherein it is mixed with gases from the
line 48 and the mixture introduced into the top
65 of the soaking drum 2. The products pass seri
ally through the soaking drums which are con
nected by lines 66 and 61. About 30G-600 pounds
pressure, or more, may be maintained on the re
action drums and preferably around 400 pounds
70 pressure. The temperature in the reaction
drums may vary considerably but a satisfactory
temperature mayl be about 900° F. on soaking
. drum 2, about 885° Ff' on soaking drum 3 and
about 870° F. on soaking drum 4. Liquid prod
75 ucts collect in the bottom of soaking drum 4 and
duced and collects with the reflux mediums intro 10
duced through lines 52 and 64 to form a mixture
of dirty oil which is Withdrawn from the bottom
of the fractionator 5 vthrough the line 45 and
forced by the pump 46 into a flash drum 44, the
operation of which has been described above. 15
The vapors from the' fractionator 5 are with’
drawn through the line 14, and conducted to the
lower portion of the secondary fractionator 6.
In the fractionator 6, substantially all the hy
drocarbons of higher boiling point than the de
sired ñnal distillate are condensed and collected
in the lower portion of the fractionator as a
clean distillate recycle stock which is withdrawn
from the bottom of the fractionator through the
line 60, as described heretofore.
In order to obtain adequate separation of the
vapors, a reiiux condenser I9 is shown super
imposed upon the secondary Iractionator 6. The
vapors from fractionator 6 pass from the upper
portion of the fracticnator 6 through the vapor 30
line 15 to the reiìux condenser, wherein addi
tional reiiux condensate forms and ñows from
the reflux condenser through the line 16 into the
top of the fractionator 6. The vapors contain
ing the motor fuel hydrocarbons are withdrawn
from the top of the reiiux condenser through the
vapor line 18, condensed in the condenser 19 and»
the condensate collected in the accumulator 30.
The accumulator 30 may be maintained under
about 150-200 pounds pressure and uncondensed 40
vapors and gases are released through the valve
controlled line 32 and conducted to the absorber
8, the operation of which has been described
heretofore.
The condensate in the accumulator 30 is with 45
drawn through the liquid draw-off line 8I and
introduced into the lower portion of the stabilizer
1. In the stabilizer the undesired normally gase
ous hydrocarbons are stripped from the distil
late. The liquid collecting in the bottom of 50
the stabilizer comprises stabilized naphtha which
is drawn from the bottom of the stabilizer through
the line 82. The normally gaseous hydrocarbons,
including Ca and C4 hydrocarbons, are conducted
from the top of the stabilizer through the line 55
3I to the lower portion of the absorber 8.
In practicing the invention charging a crude
residuum, and recycling about 35% by weight of
C3 and C4 hydrocarbons, a 7% increase in
naphtha yield may be obtained.
The present invention provides a convenient
means of obtaining the beneñts of gas reversion
without substantial loss in fresh charge capacity
and no materially increased tendency toward coke
formation in the heating coil.
65
Obviously many modifications and variations
of the invention, as hereinbefore set forth, may
_be made without departing from the spirit and
scope thereof and therefore only such limitations
should’ be imposed as are indicated in the ap 70
pended claims.I claim:
i. A process for the conversion of hydrocar
bons to produce motor-fuel, which comprises sub
jecting a higher boiling hydrocarbon oil to crack 75
2,130,313
ing conditions of temperature and pressure
whereby lower boiling hydrocarbons are formed,
passing the cracked products to a so-aking zone
to undergo further conversion, separating the
cracked products into vapors and residuum, frac
tionating the vapors to separate therefrom a
fraction containing insuiiiciently 'cracked hydro
carbons, passing said insumciently cracked hy
drocarbons to a flashing zone, also introducing
into said ñashing zone charging stock containing
normally gaseous hydrocarbons, separating in
the flash zone a vapor fraction containing said
normally gaseous hydrocarbons, passing 'said
vapor fraction to the soaking zone and charging '
the residual fraction from the ñashing zone to
the cracking operation.
_
2, A process for ‘the conversion of hydrocar
bons to produce motor fuel, which comprises sub
jecting a hydrocarbon oil to conversion tempera
tures in zones of heating and soaking, separating
the cracked products into vapors and a residual
oil, dephlegmating the vapors to form a reflux
condensate and an uncondensed vapor fraction,
transferring the reñux condensate to a ñashing
25 zone, fractionating the uncondensed vapor frac
tion to separate the motor fuel from normally
gaseous hydrocarbons, absorbing the higher
boiling portion of said normally gaseous hydro
carbons in a hydrocarbon oil, introducing said
30
hydrocarbon oil and absorbed gaseous hydro
carbons into said hashing zone, separating in
said flashing zone normally gaseous hydrocar
bons, passing said normally gaseous hydrocar
bons so separated to the soaking zone and charg
ing oil from the flashing zone to the cracking
_ zone.
40
3. A process for. conversion of higher boiling
hydrocarbon oils into lower boiling hydrocarbon
oils, vcomprising subjecting the oil to- cracking
temperatures in zones of heating and soaking,
separating the cracked products into vapors and
a residual oil, fractionating the vapors to form a
dirty cracking stock, a clean recycle stock, a
motor fuel condensate and normally gaseous hy
drocarbons, returning the clean recycle stock
to said heating zone, scrubbing the normally
gaseous hydrocarbons with a lean absorbent oil
to absorb the higher boiling constituents of said
normally gaseous hydrocarbons, combining the
50 resultant rich absorbent oil with said dirty crack
3
arate a reflux condensate, commingling said re
ñux condensate and fresh charge containing
normally gaseous hydrocarbons, flashing said
mixture to form residual oil and a fraction con
taining normally gaseous hydrocarbons, charg
ing said residual oil to the conversion operation
and introducing said fraction containing normal
ly gaseous hydrocarbons into the conversion op
eration at an intermediate point thereof.
5. A process for the conversion of hydrocar 10
bons to produce motor fuel, which comprises sub
jecting hydrocarbon oils to a conversion opera
tion whereby motor fuel hydrocarbons are
formed, separating the products of reaction into
vapors and residuum, fractionating the vapors to 15
produce a recycle stock and an imstabilized mo
tor fuel, subjecting said unstabilized motor fuel
to stabilization thereby forming a stabilized mo
tor fuel and normally gaseous hydrocarbons, con
tacting said _normally gaseous hydrocarbons with 20
a cracking stock thereby absorbing higher boil
ing constituents of the normally gaseous hydro
carbons, preheating the resultant enriched crack
ing stock with the aid of heat from said recycle
stock, ñashing the preheated product to form a
volatile fraction containing normally gaseous hy
drocarbons and a residual oil, charging said re
cycle stock and residual oil to said conversion
operation and introducing said volatile fraction>
containing normally gaseous hydrocarbons into 30
the conversion operation at an intermediate point
thereof.
6. A process for the treatment of hydrocarbons
which comprises preheating' a charging stock
containing normally gaseous hydrocarbons, flash 35
ing the preheated mixture to produce a volatile
fraction containing normally gaseous hydrocar
bons and a residual oil, subjecting said residual
oil to a conversion operation in zones of heating
and soaking to form motor fuel products, passing 40
said volatile fraction containing normally gase
ous hydrocarbons to said soaking zone, separat
ing from the reaction products a recycle stock,
subjecting said recycle stock tocracking tempera
tures, and introducing the hot products into the
soaking zone.
'1. A process for the treatment of hydrocar
bons which comprises scrubbing residual gases .
from the conversion of hydrocarbon oils with a
cracking stock thereby enriching'the cracking 50
stock with normally gaseous hydrocarbons, sep
arating the enriched cracking stock into a volatile
a fraction containing normally gaseous hydro
carbons, introducing said fraction containing fraction containing normally gaseous hydrocar
normally gaseous hydrocarbons into said soaking‘ bons and residual oil, subjecting the residual oil
zone,
subjecting the bottoms from the flashing to conversion in zones of heating and soaking,
CH G1
operation to cracking temperatures and intro- ' charging said volatile fraction to the soaking
ducing the cracked product into said soaking zone, separating from the products of reaction
a recycle stock, a motor fuel fraction and residual
zone.
gases, heating the recycle stock to cracking tem
4. A process for the conversion of hydrocar
peratures,
passing the hot products to the soak
bons to produce motor fuel, which comprises sub
jecting hydrocarbon oils to a conversion opera-_ ing zone, and conducting the residual gases to
tion whereby motor fuel hydrocarbons are formed, the ñrst mentioned scrubbing operation.
separating the products of reaction into vapors
JOSEPH M. BARRON.
and residuum, fractionating the vapors to sep
ing stock, flashing from the resulting mixture
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