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July 9, 1946.
H’.- V. ATWELL ET AL
2,403,485
SEPARATION 9F AnoMATIc HYnRocARBoNs FROM HYDROCARBON MIXTURES
Filed March 8, 1941
` INTERFACE LEVEL
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Du Bols EAsTMAN
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l-lAlzoLovA‘rw/ELL
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INVENTORS
BY l YÍXMW.
A TTORNEYS
2,403,485
Patented July 9, 1946
UNITED STATES PATENT OFFICE
2,403,485
SEPARATION OF AROMATIC HYDROCAR
BONS FROM HYDROCARBON MIXTURES
Harold V. Atwell, Beacon, N. Y., and Du Bois East
man, Port Arthur, Tex., assignors, by mesne as
signments, to The Texas Company, New York,
N. Y., a corporation of Delaware
Application March 8, 1941, Serial No. 382,328
6 Claims. (Cl. 196--13)
l
This invention relates to the separation of aro
matic hydrocarbons from hydrocarbon mixtures
and particularly from hydrocarbon mixtures such
as derived from petroleum and which contain
aromatic and non-aroma-tic hydrocarbons in
cluding aliphatic and alicyclic hydrocarbons.
The invention broadly contemplates separat-y
2
weight of the solvent mixture and preferably
will range from about 5 to 25% by weight.
The invention has particular application to
the extraction of aromatics such as benzol, toluol
and xylol from hydrocarbon fractions derived
from petroleum or obtained in the thermal or
catalytic treatment of petroleum hydrocarbons.
For example, it is useful in extracting benzol
and toluol from cracked naphtha produced in
a solvent consisting essentially of water at a tem 10 either catalytic or pyrolytic cracking of hydro
carbons. Other naphtha or hydrocarbon mix
perature considerably above the normal boiling
tures to which the invention may be applied com
point of water, and under a pressure suñ‘icient to
prise hydroformed naphtha, pyrolytically or cat
maintain the solvent and hydrocarbons substan
alytically reformed naphtha, polyformed naph
tially in the liquid phase during the extraction.
As a result of the extraction a solvent phase is 15 tha and theilike. It is also applicable to the ex
traction of aromatic hydrocarbons from straight
formed comprising aromatic hydrocarbons dis
run naphthas or gasolines such as distilled from
solved in the major portion of the solvent liquid
certain crudes.
while a hydrocarbon phase is formed comprising
While the treatment of hydrocarbon mixtures
non-aromatic and other hydrocarbons mixed with
a miner portion of the solvent. The two phases 20 derived vfrom petroleum sources has been specili
cally mentioned, nevertheless it is contemplated
are separated and separately subjected to cooling
that the process may be employed for extracting
and settling, without substantial reduction in
valuable aromatic hydrocarbons from hydrocar
pressure, so that separation between hydrocar
bon mixtures derived from other sources.
bons and solvent occurs. The separated hydro
carbons are withdrawn,'while the solvent from 25 An object of the invention is to provide a
continuous method of extracting aromatic hy
which the hydrocarbons have been separated is
drocarbons from a mixture of aromatic and ali
recycled Afor extracting fresh feed mixture.
phatic or other hydrocarbons with a solvent
It is also contemplated that the solvent may
which can be separated and recovered from the
comprise water and a small amount of inorganic
salts, acids or bases, or organic substances ca 30 solvent and hydrocarbon phases obtained in the
extraction merely by reduction in temperature
pable of favorably iniiuencing the solvent prop
thereby avoiding resort to fractional distillation.
erties of the water and permitting extraction in
Ar further object is to provide a continuous
the liquid phase at temperatures and pressures
method of extraction in a substantially closed
lower than otherwise necessary when employing
36 circuit through which the solvent medium cir
water alone as the extracting medium.
culates and from which the separated hydrocar
The proportion of added substance which may
bons can be separately withdrawn without sub
be employed is such that the mixture of water
stantial reduction in the pressure within the cir
and added substance Iwill exert substantial sol
cuit or extraction system.
vent action upon aromatic hydrocarbonsat tem
peratures of 200° F. and above but will exert 40 In order to describe the invention in more de
tail reference will now be made to the figures
substantially little solvent action upon aromatic
of the accompanying drawing showing methods
hydrocarbons at ordinary temperatures, for ex
of practicing the extraction process of the in
ample, from about room temperature to about
vention.
y
159° F. In other words, the proportion of added
substance and water in the solvent mixture is 45 As shown in Figure 1 a hydrocarbon feed such
as cracked naphtha or a fraction of cracked
such that when the solution of desired aromatic
naphtha containing aromatic, alicyclic and ali
hydrocarbons in the solvent is separated from
ing aromatic hydrocarbons from mixtures con
taining them by extraction with water or with
phatic hydrocarbons is conducted from a source
not shown through a pipe I communicating with
carbons can be substantially entirely separated
from the solvent merely by reducing the tem 50 branch pipesl 2 and 3 leading to the lower portion
of an extraction tower 4.
perature of the solution to a temperature >in the
The extraction tower 4 advantageously com
range about 70 to 150° F.
prises a vertical vessel containing a suitable pack
Thus, the proportion of above-mentioned add
ing or contact `material `5 such as Raschig rings.
ed substance contained in the water may range
A stream of water is continuously introduced
from a fraction of a per cent to 56% or more by 55
the extraction zone the desired aromatic hydro
2,403,485
3
4
to the upper portion of the extractionV tower
through a pipe 6. The water flows downwardly
over the packing material within the tower, while
the feed hydrocarbons ñow upwardly there
aliphatic and naphthenic hydrocarbons which are
through, so that countercurrent contact between
water and hydrocarbon is realized.
The water is introduced to the tower at an
elevated temperature of about 40G to 600° F. and
preferably about 475 to 525°` F.
_
The hydrocarbon feed is likewise introduced to
the lower portion of the tower in a heated con
discharged from the system through a valve con
trolled pipe 23. The lower layer in the settler 22
will comprise Water which is drawn oli" through
a valve controlled pipe 2d. Since the amount
of water present in the mixture entering the
settler 22 will usually be quite small, the water
separated at this point may be discharged from
the system. On the other hand instead of pass»
ing the hydrocarbon phase to settler 22 it may be
dition, for example, at a temperature substan
passed directly to a still or other means wherein
the pressure is reduced and the hydrocarbons re
tially the same as that at which the water solvent
is introduced. In some cases it may be advan
covered for such further treatment as may be
tageous to introduce the feed hydrocarbon at a
somewhat lower temperature, for example, 25
or 50° below the temperature at which the solvent
desired.
The upper layers withdrawn from the settlers
I2 and 22 may be distilled separately to distil oil?
the small amount of retained water and also to
is introduced, thereby maintaining a temperature
gradient within the tower.
individual aromatic constituents as the case may Y
eiïect separation between benzol and toluol or the
As indicated at the outset the extraction tower 20 be. If desired these hydrocarbon layers may be
is operated under a pressure suiiiciently elevated
subjected to drying by filtration.
to maintain the solvent and hydrocarbons under
'I‘he water drawn oir from the settling vessels
going treatment substantially in the liquid phase.
through the pipe Iii, and including that from pipe
Thus, the pressures will depend upon the par
24 if so desired, is conducted through the pipe
ticular temperatures maintained within the 25 '(25 by means of a pump 25 to a heater 2l', wherein
tower as well as upon the volatility of the liquids
the temperature of the water is raised to the
within the system and may range from 1000 to
desired point, and thereafter conducted from the
5500 pounds per square inch gauge, for example.
heater through the previously mentioned pipe 6
As a result of the countercurrent contact be
for return to the upper portion of the extraction
tween solvent and hydrocarbons there will be 30 tower. Makemp Water or solvent can be added
formed a solvent rich phase or solution which will
to the pipe 25 through a pump 28.
comprise aromatic hydrocarbons dissolved in the
Thus, as indicated in the drawing the system
bulk of the solvent. The undissolved hydrocar
comprising the extraction tower, the coolers I I
bons or hydrocarbon rich phase will comprise
and 2l, settlers I2 and 22, the heater 2l' and the
aliphatic and alicyclic hydrocarbons mixed with 35 pipes affording ñuid communication therebe
a small amount of solvent.>
tween provides a closed circuit through which
The hydrocarbon rich phase is removed from
the solvent medium circulates continuously. Ad
the top of the tower while the solvent rich phase
vantageously the pressure is substantially equal
is removed from the bottom of the tower.
ized throughout the entire circuit and which in
As indicated in Figure 1 the interface level be 40 volves effecting the cooling and settling of the
tween solvent and hydrocarbon phases may be
phases withdrawn from the top and bottom of
maintained near the bottom of the tower, pro
the extraction tower without reduction in the
vision being made forv observing the level with
pressure.y
either a sight glass or a differential float control
In carrying out the extraction the volume of
not shown in the drawing.
water circulated through the extraction tower is
The solvent phase accumulating in the bottom
usually greater than the volume of feed hydrocar
of the tower is drawn off through a pipe Iii and a
bons passing therethrough. Thus, the ratio of
cooling coil II and from there conducted to a
water to hydrocarbon feed may range from l to
settling vessel I2.
_
In passing through the cooling coil Il the tem
perature of the solvent phase is reduced to a
temperature below 200° F. for example in the
range about 70 to 150° F., so that upon introduc
tion to the settler I2 separation into layers or
phases occurs due to the relative insolubility of
the aromatic hydrocarbon in the solvent at the
reduced temperatures.
12 parts or more of water'to l part of hydrocarw
bon feed.
Figure 2 illustrates an alternative method of
operation wherein the extraction tower is main
tained substantially iilled with a body of water
and circulation of water through the system is
effected by thermo-Siphon action. -
Thus, the tower 30 is substantially similar to
the tower 4 described in Figure 1 and may like
wise be provided with packing material 3 I.
The water or solvent consisting essentially of
off through a Valve controlled pipe I3. The 60
water is introduced to the upper portion of the
lower layer or phase will comprise water satue
tower through pipe 32 while the naphtha or mix
rated with, or containing a very low content of
ture of hydrocarbons containing aromatics, after
aromatic hydrocarbons at the temperature pre
passage through a heater 33, is introduced to the
vailing within the settler I2, and this water is
lower portion of the tower through a pipe 34.
drawn oiï through a Valve controlled pipe I4.
The operation is regulated so that the interface
Likewise the hydrocarbon phase accumulating
level 35 is maintained near the top of the tower.
in the top of the extraction tower is drawn off
Thus, the heated naphtha after introduction to
through a pipe 20 and passed through a cooling
the lower portion of the tower bubbles upwardly
coil 2| to a settler 22 similar to the settler I2.
In passing through the cooler 2| the temperature 70 through the body of water contained within the
tower. The unabsorbed hydrocarbons accumu
of the hydrocarbon phase may be reduced to
The upper layer or phase in the settler I2 will
comprise aromatic hydrocarbons which are drawn
about 70° F.
Likewise in the settler 22 a small amountY of
late as a layer or hydrocarbon rich phase in the
top of the tower and are removed therefrom
phase separation will occur as a result of reduc
through a pipe 35. From the pipe 3S the with
tion in temperature, the upper phase comprising 75 drawn hydrocarbons are passed through a cooler
2,403,485
5
6
31 and conducted to a separating vessel 38 sim
ilar to the vessel 22 referred to in Figure 1.
A stream of water containing the dissolved
of about 0.8613 relative to water at 68° F. The
olefins used in the mixture comprise a fraction
having a boiling range of about 200 to 250° F.
aromatic hydrocarbons is continuously drawn off
from the bottom of the tower through a pipe 39
leading to a heater 40.
The mixture after heating in the heater 40
rises through a vertical pipe 4I leading to a cooler
42 ‘placed at an elevation somewhat higher than
the top of the tower.
separated from polymer naphtha obtained in the
catalytic polymerization of normally gaseous ole
The mixture passing through the previously
mentioned heater 40 is sufficiently heated so that
the density is reduced thereby causing the liquid
to rise through the pipe 4|.
In the cooler 42 the temperature is reduced to
some point in the range about 70 to 150° F. so that
upon introduction of the cooled mixture to a
V
.
iins. The parañins comprise a fraction having a
boiling range from 200 to 250° F. separated from
a gasoline obtained by catalytically alkylating
gaseous isoparaiìns and oleñns.
Water is continuously charged to the upper
portion of the tower in the proportion of about
6 parts of water to 1 part of naphtha charge.
The temperature at the top of the tower is
maintained at about 530° F. while the tempera
ture at the bottom of the tower is about 519° F.
The average pressure maintained within the
tower is about 2500 pounds.
separator 43 separation into phases occurs. The
The extract phase comprising aromatic hy
upper phase will comprise aromatic hydrocarbons
drocarbons dissolved in the water is continuously
which were extracted from the naphtha feed
while the lower phase will comprise water from
which the aromatic hydrocarbons have been sep
arated.
This water phase is continuously drawn off
from the bottom of the separator 43 through a
pipe 44 and passed through a heater 45 wherein
the water or solvent is heated to the desired
temperature for eifecting extraction within the
extraction tower. The so heated and recycled
water or solvent is returned to the upper portion 30
withdrawn from the bottom of the tower while
the raflinate phase comprising non-aromatic hy
drocarbons is continuously withdrawn from the
top of the tower.
The water free extract will have an average
specific gravity of .8142 relative to water at 60°
F., this extract will contain an average of about
66% by weight of toluene, which amounts to
about 46% by volume of the toluene contained in
the charge mixture.
Where it is desired to obtain toluene sub- I
of the tower through the previously mentioned
pipe 32.
The separated aromatic hydrocarbons are dis
charged from the top of the separator 43 through
stantially free from olefìns the extract hydro
drocarbon layers removed from the separating
vessels of Figures 1 and 2 may be subjected to
subsequent and separate re-extractions in sepa
rate stages.
The following example illustrates the results
elevated to effect desulfurizing of the hydrocar
bon mixture. Thereafter, the treated hydrocar
bon mixture is subjected to extraction with water
similar to that already described. The naphtha
obtained in a continuous countercurrent tower
hydrocarbons from which the desired aromatics
extraction such as described in Figure 1, when
have been extracted can be run to gasoline or
continuously charging to the lower portion of
motor fuel production.
the tower naphtha comprising a mixture of 20%
While the invention has been described in con
nection with the recovery of aromatic hydro
carbons from naphtha it is contemplated that the
carbons may be subjected to treatment with a
suitable agent such as sulfuric acid for the pur
v pose of removing the oleñns. The acid treat
a pipe 46.
ment may also be employed for the purpose of
removing sulfur compounds such as mercaptans
As previously mentioned in connection with
Figure 1 the water drawn off from the bottom of
as well as other impurities. Other reagents may
the separator 38 may be discharged from the sys
be employed for this purpose including solid ad
tem since it is relatively small in amount. In
sorptive material Such as acid treated clay,
any case it is necessary to continuously add a 40
In extracting aromatic hydrocarbons such asv
small amount'Í of makeup water to the system and
toluene from naphtha the light naphtha frac
this can be done by means of a pump 41, by
tion may be subjected to extraction with water
which means additional water is injected into the
followed by distillation of the resulting extract
pipe 39.
hydrocarbons to segregate a fraction rich in the
It is contemplated that inert gas may be in
desired aromatic constituents. As an alterna
troduced to the pipe 39 or the pipe 4l to serve
tive ,procedure the naphtha may be fractionated
as a gas lift or to reduce the density of the fluid
to segregate a fraction rich in the desired aro
rising through the pipe 4l so that positive and
matic constituents, i. e., toluene or consisting es
rapid flow of fluid through the pipe 4l is se
sentially of hydrocarbons having a boiling range
cured. In such case provision is made for sepa 50 of about 200 to 250° F. and this fraction then sub
rately discharging the gas from. the separating
jected to solvent extraction in order to separate
vessel 43.
the toluene.
Instead of introducing extraneous gas it is con
It is contemplated that the naphtha or naph
templated that the heating in the heater 40 may
tha fraction rich in the desired aromatics may
be such as to generate a small amount of steam
be subjected to preliminary treatment to remove
or vapor thereby serving substantially the same
gum forming bodies and sulfur compounds prior
function of reducing the density of the fluid in
to extraction with water. For example, the
the pipe 4|. The resulting vapors would be sub
naphtha or suitable fraction thereof may be
stantially condensed in the cooler 42.
passed directly from the fractionating tower of
While a single extraction tower has been de 60 the conversion unit in which the naphtha is vpro
scribed above nevertheless it is contemplated
duced to a conventional clay treating tower for
that the extraction may be carried out in a multi
the removal of dioleñns or gum forming bodies.
stage operation employing a plurality of extrac
This clay treatment or a separate clay treatment
tion towers. Also it is contemplated that the hy
may be carried out at temperatures sufñciently
toluene, 20% oleñns and 60% paramns by weight.
The toluene in the mixture has a specific gravity
to remove the aromatic constituents in a manner
2,403,485
7
invention may be applied in the extraction of
other hydrocarbon fractions such as the higher
boiling portions of cracked or reformed gasoline
and also to kerosenes and lubricating oils.
In addition to the foregoing the process has
application to the extraction of high antiknock
aromatic blending stocks from wide boiling range
naphthas or naphtha mixtures. It may also be
applied to the treatment of high boiling petrole
8
tom of said tower, heating the withdrawn stream
without substantial reduction in pressure to a
temperature suii'icient to reduce its density, dis
charging the so heated stream into a vertically
disposed conduit having a discharge outlet at an
elevation substantially above the top of the tower,
discharging the heated stream without substan
tial reduction in pressure into a ,cooling zone,
cooling the discharged ñuid and passing the
um fractions to obtain raliinates of desired prop
cooled fluid to a separating zone without sub
erties, for example, Diesel fuel having a high
cetane number, kerosene having superior burning
properties or lubricating oils of high viscosity
stantial reduction in pressure, effecting separa
tion between dissolved hydrocarbons and solvent
in said separating zone, discharging the sepa
index.
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
pended claims.
rated hydrocarbons, reheating the substantially
hydrocarbon free solvent without substantial re
duction in pressure, and returning the reheated
solvent to the upper portion of said tower.
3. A continuous process for extracting aromatic
hydrocarbons from a hydrocarbon mixture con
20 taining aromatic and non-aromatic hydrocarbons
We claim:
l. A continuous process for extracting aro
matic hydrocarbons from a hydrocarbon mix
ture containing aromatic and non-aromatic hy
drocarbons by contact with a solvent in continu
by contact with a solvent in continuous counter
current flow in an extraction tower, which com
prises maintaining a substantial body of solvent
ous countercurrent flow in an extraction tower
F. and under a pressure such that the hydrocar
bons and solvent are substantially in the liquid
which comprises maintaining a substantial body
of solvent consisting essentially of water within
consisting essentially of water within the tower
ata temperature in the range about 475 to 525°
phase, continuously injecting a naphtha hydro
carbon mixture of aromatic and non-aromatic
normal boiling point of said solvent and under a 30 constituents to the lower portion of said tower to
` the tower at a temperature sufficiently above the
pressure surñciently high that aromatic hydro
rise upwardly therein through the body of solvent,
carbons are substantially soluble in the solvent
and such that the hydrocarbons and solvent are
continuously withdrawing a stream of solvent and
dissolved aromatic hydrocarbons from the lower
portion of said tower at a point below the point
substantially in the liquid phase, continuously in
jecting feed hydrocarbon mixture to the lower 35 oi hydrocarbon injection, heating the withdrawn
portion of said tower to rise upwardly therein
through the body of solvent, continuously with
drawing a stream of solvent and dissolved hydro
carbons from said tower at a point below the
point of feed hydrocarbon injection, heating the
stream without substantial reduction in pressure
to a temperature sufficient to reduce its density,
discharging the so-heated stream into a verti
`cally disposed conduit having a discharge outlet
at an elevation suiiiciently high to permit ñow
by gravity from said discharge outlet into the
withdrawn stream without substantial reduction
upper portion of the tower, discharging the heat
in pressure to a temperature suñicient to reduce
its density, discharging the so-heated stream into
ed stream without substantial reduction in pres
sure from said outlet into a cooling zone, cooling
a vertically disposed conduit having a discharge
outlet at an elevation sufñciently high to permit 45 the discharged fluid and, without substantial re
duction in pressure, effecting separation between
iiow by gravity from said discharge outlet into
the upper portion of the tower, discharging the
aromatic hydrocarbons and solvent as a result
of said cooling, discharging the separated aro
heated stream without substantial reduction in
matic hydrocarbons, reheating the substantially
pressure from said outlet into a cooling zone,
cooling the discharged fluid and passing the 50 hydrocarbon-free solvent without substantial re
duction in pressure, and returning the reheated
solvent to the upper portion of said tower by
tial recluction in pressure, effecting separation be
tween dissolved hydrocarbons and solvent in said
gravity flow.
separating zone, discharging the so separated hy
4.. A continuous process for effecting fractional
drocarbons, reheating and recycling the reheated 55 separation of oil mixtures by extraction with a
solvent in which a component of said mixture is
solvent from which hydrocarbons have been sep
substantially soluble while remaining components
arated to the upper portion of said tower and con
tinuously withdrawing undissolved hydrocarbons
are substantially insoluble therein at an elevated
temperature and pressure, which comprises con
from the top of said tower.
2. A continuous process for extracting aro 60 tinuously maintaining a substantial body of said
matic hydrocarbons from a hydrocarbon mixture
solvent within the tower under said elevated tem
perature and pressure, continuously injecting a
containing aromatic and non-aromatic hydrocar
bons by contact with a solvent in continuous
stream of said oil mixture to the lower portion of
said tower to rise upwardly therein through the
countercurrent now in an extraction tower which
body of solvent, continuously withdrawing a
comprises maintaining a substantial body of solv
ent consisting essentially of water within the
stream of solvent and dissolved oil from the lower
portion of said tower at a point below the point
tower under elevated temperature and pressure
of oil injection, heating the withdrawn stream
such that` aromatic hydrocarbons are substan
without substantial reduction in pressure to a
tially soluble in the solvent and such that the
hydrocarbons and solvent are substantially in 70 temperature sufñcient to reduce its density, dis
charging the so-heated stream into a vertically
the liquid phase, continuously injecting feed hy
disposed conduit having a discharge outlet at an
drocarbon mixture to the lower portion of said
elevation sufñciently high to permit liow by grav
tower to risel upwardly therein through the body
ity from said discharge outlet into the upper
of solvent, continuously withdrawing a stream of
solvent and dissolved hydrocarbons from the bot 75 portion of the tower, discharging the heated
cooled duid to a separating zone without substan
2,403,485
'
9
10
stream without substantial reduction in pressure
from said outlet into a cooling zone, cooling the
discharged iiuid and, without substantial reduc
tion in pressure, effecting separation between dis
the reheated solvent from which hydrocarbons
have been separated to the upper portion of said
tower and continuously withdrawing undissolved
hydrocarbons from the top of said tower.
6. A continuous process for extracting toluene
from a hydrocarbon mixture containing toluene
and non-aromatic hydrocarbons by contact with
solved oil and solvent as a result of said cooling,
discharging the separated oil, reheating the sub
stantially oil-free solvent without substantial re
duction in pressure, and returning the reheated
a solvent in continuous countercurrent ñow in an
solvent to the upper portion of said tower by
extraction tower, which comprises maintaining a
gravity flow.
10 substantial body of solvent consisting essentially
of water within the tower at a temperature in
5. A continuous process for extracting toluene
from a naphtha hydrocarbon mixture containing
the range about 475 to 525° F. and under a pres
sure such that the hydrocarbons and solvent are
toluene and non-aromatic hydrocarbons by con
substantially in the liquid phase, continuously in
tact with a solvent in continuous countercurrent
ñow in an extraction tower which comprises 15 jecting a naphtha hydrocarbon mixture boiling
in the range about 200 to 250° F. containing tolu
maintaining a substantial body of solvent con
ene and non-aromatic hydrocarbons to the lower
sisting essentially of water within the tower at a
portion of said tower to rise upwardly therein
temperature suñiciently above the normal boil
through the body of solvent, continuously with
ing point of said solvent and under a pressure
sufficiently high that toluene is substantially sol 20 drawing a stream of solvent and dissolved tolu
ene from the lower portion of said tower at a
uble in the solvent and such that the hydrocar
point below the point of hydrocarbon injection,
bons and solvent are substantially in the liquid
phase, continuously injecting feed naphtha to the
heating the withdrawn stream without substan
tial reduction in pressure to a temperature suf
lower portion of said tower to rise upwardly there
ñcient to reduce its density, discharging the so
in through the body of solvent, continuously
heated stream into a vertically disposed conduit
withdrawing a stream of solvent and dissolved
hydrocarbons from said tower at a point below f having a discharge outlet at an elevation suñi
ciently high to permit flow by gravity from said
the point of feed hydrocarbon injection, heating
discharge outlet into the upper portion of the
the withdrawn stream without substantial reduc-~
tion in pressure to a temperature sun‘ìcient to 30 tower, discharging the heated stream without
substantial reduction in pressure from said out
let into a cooling zone, cooling the discharged
stream into a vertically disposed conduit having
a discharge outlet at an elevation suiiîciently
fluid and, Without >substantial reduction in pres
high to permit ñowby gravity from said dis
sure, effecting separation between toluene and
charge outlet into the upper portion of the tower, 35 solvent as a result of said cooling, discharging
reduce its density, discharging the so-heated
discharging the heated stream without substan
the separated toluene, reheating the substantial
tial reduction in pressure from said outlet into a
cooling zone, cooling the discharged fluid and
ly hydrocarbon-free solvent without substantial
reduction in pressure, and returning the reheated
passing the cooled fluid to a separating Zone
solvent to the upper portion 0f said tower by ‘
without substantial reduction in pressure, eiîect 40 gravity ilow.
ing separation between dissolved toluene and sol
vent in said separating zone, discharging the so
separated hydrocarbons, reheating and recycling
HAROLD V. ATWELL.
DU BOIS EASTMAN,
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