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Патент USA US2135356

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Nov. 1, 1938.
Filed Dec. 11, 1935
Patented Nov. 1, 1938
Adolf Schmalenbach, Essen-on-the-Ruhr, Ger- 7
many, assignor, by mesne assignments, to Kop
pers Gompany,.Pittsburgh, Pa., a corporation of
Application December 11, 1935, Serial No. 53,986
In Germany February 9, 1934
3 Claims.
The invention relates to the extraction of
benzene and its homologues or other hydrocar
bons from gases containing ammonia, more par
ticularly coal distillation gases or the like, where
in benzene and its homologues are Washed out
the extraction of the benzene and homologues.
ample coal-tar oil has hitherto presented con
The usual iron apparatus
which is commonly used on account of its cheapness cannot be used with the treatment of gases
containing ammonia as it very quickly corrodes
through the action of the hot ammonia'liquor
which cannot be prevented from being extracted
from the gas by the washing oil. It was there
fore always necessary hitherto to separate the
ammonia from the gases before the extraction
of the benzene. On this account the extraction
25 of benzene is often unpro?table and it is to be
noticed that the separation of ammonia involves
considerable cost if it is not accompanied with
the production of crystallized ammonium sul
phate or concentrated ammonia liquor. Both
30 methods for utilizing the ammonia require how
ever substantially expensive apparatus (saturat
ing or separating apparatus) as well as a large
This settling. process is preferably accompanied
by a washing of the oil with water. With nor
mal washing oil, the separation of the Water takes '
place at about 60° C.
The drawing illustrates a side elevation of the
apparatus serving to carry out the process ac
cording to the invention.
In the device illustrated the raw washing oil
coming from the benzene washers is stored in a
container I. This container is connected by
means of a pipe 2 with a cooler 3, the purpose of 20
which will be explained later. The crude wash
ing oil serves as a cooling means in the cooler 3,
and is thus heated. The heated washing oil
passes out from the pipe 4, which is connected
by means of stop cocks 5, 6', ‘I, 8,with the pipes‘ .
9, l5, H and I2. These pipes can be connected
with each other by means of a suitable adjust
ment of the regulating valves so that the crude
Washing oil ?rst of all flows out from. the pipe ll.
into the pipe 9, or through ‘the circulating pipe 30
I!) into the pipe ll.
The pipes 9 and» II are connected with a sub
operating sta? so that they are only practical for stantially cylindrical separating apparatus $3,
the pipe Sbeing connected to the vessel l3 near
The costs resulting from the separation of the bottom and the pipe H to the top of the
ammonia from gases and the accompanying ex
same; In addition the vessel I3 is connected
with the pipes l4 and I5 through which water
penses are so considerable that as a rule where
it is a question of preparing only a relatively can be supplied to the vessel l3 as required. ,
small quantity of gas, the benzene and ammonia
The pipe [2 leads to an oil heater It. The
pre-heated oil is supplied by means of a pump 40
are not extracted, although the benzene, particu
larly nowadays, is a valuable product which Ila through the pipe I‘! into the heating device
considerably increases the economical operation l8 in which the oil is heated by means of steam.
of a coal distillation plant. As a matter of fact The resulting steam and the hot washing oil
at the present day only a very small number of pass through the pipes I9 or 20 into the sepa
gas works of small output extract benzene.
rating apparatus 2|.
The object of the present invention is to en
In the device illustrated in the drawing the
able the extraction of. benzene from coal distilla
separating apparatus consists of a column, pro
tion gases and the like containing ammonia to vided with several floors, in which steam is intro- '
duced at the bottom through the pipe 22, and
be carried out with the use of the known Wash
ing oil process, without previous separation of the serves to heat the washing oil directly.
. 50v
In the treatment in the column 2! benzene and
homologues are separated from the washing oil
The process according to the invention con
sists in that the washing oil which in addition together with the steam; the steam ?ows through
to benzene and homologues also contains a de?- - the pipe 23 and then passes into the pre-heated
nite quantity of ammonia liquor, is maintained cooling device 3. This cooling device is con 55
the preparation of. large quantities of ammonia.
large that the two liquids separate from each
15 siderable dif?culties.
at a temperature at which the difference in the
speci?c gravity of the washing oil on one hand
and of the ammonia liquor on the other is so Cl
other, whereafter the washing oil freed of. am
monia liquor is conveyed into the apparatus for
washed out by means of a washing oil, for ex
for a de?nite time, before its introduction into
the distillation apparatus of the benzene plant,
of the gas by means of a washing oil from which
the benzene and the homologues are extracted
by means of distillation treatment after pre
The treatment of gases’ containing ammonia
with the usual benzene extraction process used
in coke and gas plants in which the benzene is
(Cl. 260-674)
structed as an indirect tube cooler. The cooling
is carried out by means of the untreated washing
oil from the container l. A part of the distilla
tion product condenses there and ?ows through
the pipes 24 and 25 to a separating apparatus
device I 3 is reversed. By means of a suitable
adjustment of the valvesr5, 6, ‘I and 8, crude
washing oil is introduced through the pipe 9 into
passes through the tube 21 to a rectifying device,
water is then reversed and'fresh water is in
the lower end of the pipe l3 and the washing
oil ‘freed from water is .removedrthrough .the V pipe
25, whilst the uncondensed distillation product ‘ll, similarly the direction-poi flow of the washing
The upper end_[ "troduced through the pipe l5, and water con
not illustrated in the drawing.
of the separating apparatusZB is also connected '
with this rectifying device'by “meansof the .‘pipe
In the separating apparatus '26 ‘the 'water
‘ separates from thebenzene and homologues. The
benzene and-homologues ?oat -on the "water so
that they can be removed without vdifficulty
15 through the’ top pipe 28.
The water ~?ows
through the pipe 29 into the trench 30.
taining ammonia isfgremoved through the pipe H.
‘I have L'described-my- invention above, with ref
erence‘to one example of construction but with
out limiting the‘invention to the above descrip
tion The invention may however, be varied as
desired within the ‘scope of the'following claims.
The right '.to make :'further claims is strictly re
This means that the washing *oil z-freed ‘from
.1. In aprocess for recovering benzene and its
benzene and. homologues in the apparatus 2:] is
conveyed through the pipe 3| connected to the homologues and ammonia from coal distillation »
containing the same, which comprises:
'20 bottom of the column 2| to the heateror heat ‘gases
exchange apparatus IS in which it gives up its washing the-coal gas while it still contains its
~ heat‘to the .undistilled washing oil. .The cooled ammonia and benzol iand homologues with a
‘washing oil'?nally ?ows throughthe pipe 372 and benzol absorbent wash oil so as toconcurrently
is then conveyed into'the benzene washing, plant remove in a single scrubbing step both the
ammoniaand the benzol and its homologues by
the medium-of the benzol absorbent wash oil;v
The method of operation of the plant illus
trated in'the drawing is carried out as follows:-— ‘
The crude washing oil coming from the con
tainer I is pre-heated in the device, 3 to about
60°. It then ?ows throughthe pipes 4, l0 and
V 'I I to the device l3 which is‘of such dimensions
' that the'oil is maintained at a temperature of 60°
for a de?nite time in the device 13. As required
by the circumstances the temperature of the oil
in‘ the device l3 can "be maintained by means of
a suitable heating, and heat insulation of the
a container.
In the "container I3 the water sepa
heating thevspent labsorbentrvoil, after it’ leaves
the gas but while still containing the absorbed
ammoniaand benzol and homologues, to a'tem
perature at which the ammonia liquor and the
absorbent oil with itsabsorbed benzol and homo
,logues oil will separate from each other'by grav
ity; maintaining absorbent oil at this tempera; '
ture while separatingithe ammonia liquor vfrom
the absorbent oil by gravitational separation by 35
their di?erencesin speci?c gravity, and then re
moving them from each other; thereafterdis
tilling the removed absorbentoil to liberate the
benzol and homologues therefrom; and thereafter
returning the benzol absorbent wash oil, freed ,40
of ammonia and benzol, to the aforesaid single
gas Washing step.
-2. A process as claimed in claim .1‘ and in
separation of ‘water, 'fresh Water is preferably
introduced through the'pipe, M ‘to the device which the benzol absorbent wash oil‘is‘ consti
l3. In this vway it is possible to separate prac
tutedof-coal-tar oil,~and in .which the aforesaid 545
rates from the 'oil.
The water ?oats on the oil
‘and is removed from the pipe l5 whilst oil free
40 from water is conveyed through‘the pipes 9 and
'7 l2 into the heat ‘exchange apparatus !6 ‘and from
there to the. distillation apparatus. ‘During the
tically all the ‘ammonia, or as much ofrthe same
as can cause corrosion in the ‘separating ap
g-temperaturelof approximately 60°‘ C. a
' ‘ ‘
.3. A process’ as \claimed in claim '"1 ‘and in
The treatment of ‘the washing oil in'vthe de ‘which-the spent benzol absorbent washcll '‘ is
vice I3 is preferably carried out continuously. . washed with water during the gravitational sepa- {50'
Similarly the washing water also .is' preferably ration to more completely separatethe ammonia ’ '
from the absorbent‘oilbefore the'subsequent dis
supplied through thepipe I4
a steady?ow.
If an oil having a speci?c gravity lighter .than tillation thereof to liberate the benzol thereof. j
water‘is used to wash out the benzene from. the
’ 50
.heating_for thespentcoal tar oil is efiected'to a
gas, the direction of ?ow of the liquids of the
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