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Патент USA US2134507

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Patented 0a. 25, 1938
2,134,507’ ~
v _ ; _ ‘UNITED. STATES
I ".PATENT'OFFI-Clr‘.
_
2,134,501
7.
‘
I
Horace B. Cooke, Greenwich, Conn, assignor to
RElSSUED ‘
Process Management Company, Inc., New Yor
N. Y., a corporation of Delaware
.
-
3 Claims.
_
> FEB 2 o 1940
_Application February 12, 1936,’ Serial no. 63,493
’
_
(01. 23-3)
count of the'relatively low carrying capacity of
such solutions for, hydrogen ‘sulphide. 0n the
This invention relates to a method of purify
1118 gases and pertains more particularly to an
improved method for reinoving hydrogen sul
other hand, gas-purifying solutions, such as a
solution of sodium phenolate,rwhich are suitable
phide. from gases by means of an alkaline solution
5 such as sodium carbonate.
for noti?cation by heat, cannot be used for the 5 '
puri?cation of hydrocarbons in the liquid phase.
A principal object of my invention is to provide
an improved process which will require equip
While my invention ‘will have’more general
application, it ‘is of special advantage in the
puri?cation of, re?nery gases resulting from the
cracking of hydrocarbon oil; and wherein the
ment of smaller capacity per unit volume of gases
treated, which will reduce the amount of ‘alkaline 10‘
i0 puri?ed gases are subjected to further processing
for the formation ofv valuable products therefrom. solution necessary per unit volume of gases treat
_Until' recently these gases have been largely‘ ed and wherein the acti?cation or reactivation
may be accomplished in va simpler and more
waste products and'used as fuel in the oil-re?n
ing process'and elsewhere. Undermore modern
‘l5 practice, these gases, which contain a relatively
economical manner.
/
Other and more detailed objects-and advan- l5
tages of my invention will be' apparent from a
large proportion of ' unsatin'ated hydrocarbons,
'
have been subjected to polymerizationtreatment' more detailed description hereinafter.
In accordance with my invention, the hydro
to produce liquid polymers within a motor-fuel
carbon gas to be-puri?ed of hydrogen sulphide,
boiling range and having exceptionally high anti
20 knock characteristics. The presence of hydrogen such as re?nery gas, or re?nery gas which has 20'
sulphide in the re?nery gases delivered to the been-largely freed from hydrogen or'methane by
polymerization operation is objectionable for a any of the old and well known methods, or other
number of reasons. It tends to cause corrosion hydrocarbon gas largely composed of hydrocar
of apparatus, imparts a disagreeable odor to the bons having from two to four carbon atoms per
25 ?nished products, and may adversely affect the molecule,'while at a temperature at or below the as
‘polymerization reaction, particularly when cata
lysts are employed. Moreover, the hydrogen sul
phide may react with the hydrocarbons under
going treatment, thereby resulting in a ?nal prod
30 not dimcult or impossible to re?ne by ordinary '.
critical thereof, is subjected to a pressure ade
quate to convert it into a liquid. This liquid is
then contacted with a‘ dilute sodium carbonate
solution containing for example fro'mlto 6% of
sodium carbonate. Since the hydrogen sulphide 30
- is in liquid phase and is consequently more highly
It has heretofore been‘ proposed to remove hy- . concentrated than it would be in vapor phase, the
drogen sulphide from gases by‘ contacting the ‘reaction velocity of- the ?rst named reaction and
methods.
_
'
'
_ same with an aqueous alkaline solution, such as
' 35 a'dilute solution'of sodium carbonate. The pri
, mary reaction may be expressed as follows:
_ NazCOa+HaS->NaHS+NaHCOa
the proportion of sodium hydrosulphide resulting
therefrom is increased.
While the ?rst reaction 35 “
is believed to be the primary one taking place in
the purifying zone, other reactions tending to-in
crease the amount of hydrogen sulphide ab
The spent alkaline solution is then reacti?ed by > sorbediby the solution-“may take-place. vInany
40 subjecting the spent solution to conditions con
' ‘' ducive tov reversing the reaction as follows;
event, the amount of hydrogen sulphide absorbed 40 I
by a given volume of alkaline solution is higher
when the reaction is accomplished under the
' pressure required to maintain. the hydrocarbons
.
In practice this is usually accomplished by
in liquid phase.
'
~
45,_blowing the solution with air or other inert gas. ' - After contact with the hydrocarbons, the spent 45
In such operations the amountof air required in alkaline solution is separated from the puri?ed
the reactivation-may be from two to three times liquid and 'a'cti?edunder lower -pressure,‘for ex
ample, at atmospheric pressure. Under the 're
the amount of gas puri?ed.
ducedpressure the‘ concentration of hydrogen
Various other methods of--“actifying” foul solu
50 tions of this character have been suggested, but _ sulphide gas, will be reduced, thus reversing the 50
are open to various disadvantages. Vacuum ac-. reaction and'i‘e?ecting a removal of the absorbed
ti?cationis expensive, and has not, so ‘far’ as I
'hydrogen""su'lphide. i'wAdditional hydrogen sul-. ‘
know, been successful in this country. ’ Simple , phide removal may be accomplished by subject- f
alkaline solutions are not,. under ordinary condi
tions,'suitable for acti?cation by heating, on ac
'ing the solution to heat or by blowing with air, -
steam.v or other inert gas. During the removal of ‘55
2,134,507
2
the hydrogen sulphide in the acti?cation zone
carbon dioxide ‘may be released and where this
occurs, the solution should be replenished in CO:
withdrawn from the bottom of tower ll through
returned to the system. -
on spaced perforated trays 24.
line I! provided with reducing valve 20 and dis
charges under reduced pressure into the top of
- somewhere in the cycle in order to maintain the actifying tower 2 I. The actifying tower 2| pref
sodium carbonate solution at the desired erably contains solid contact material, which
strength. The reacti?ed alkaline solution is then may be in the form of loose brick 23 disposed
With the above general nature and principal
objects in view, the invention will be better un
'10 derstood from the more detailed description here
>
Air or other inert gas may be passed into the
tower 2| through line 26 and blown upwardly
through the tower by means of blower 21 coun
10
inafter, in which reference will be‘ made to the
accompanying drawing forming a part of this
tercurrent to the ?ow of the alkaline solution.
The acti?ed solution is withdrawn from the
description.
bottom of the actifying tower 2| through line
28 and passed to an accumulating tank 29 from
which it may be withdrawn through line 30 and 15
.
Referring to the drawing, the reference char
15 acter i0 designates a charging line for receiving
the gases to be treated to remove hydrogen sul
forced by means of a pump 3| to a cooler 32
phide therefrom. These gases are freed of hy
and thence to the spray nozzle IS in the purify
drogen and methane prior to entering line It! ing tower i4 and recycled through the system.
and a well known manner for removing the hy ' The hydrocarbons undergoing .treatment and the
20 drogen and methane will be brie?y described al
purifying solution in the tower M are preferably 20
though any other conventional method may be maintained at atmospheric temperature or there
employed. Hydrocarbon gases, such as re?nery
about.
gases, are conducted through line I having a
compressor 2 to a fractionating tower 3 having
25 suitable plates or fractionating trays 4.' The
fractionating tower 3 is maintained at a suffi
ciently low temperature and at a sufficiently high
pressure to effect separation of the hydrogen and
methane in gaseous condition from hydrocarbon
30 gas largely composed of constituents having from
, two to four carbon atoms per molecule in lique
?ed condition.
The hydrogen and methane in
gaseous condition are removed from the frac
cs
tionating tower 3 through line 5 having a valve
6 and the lique?ed hydrocarbons of from two
to four carbon atoms per molecule collect in the
lower portion- of the tower Ill. These lique?ed
hydrocarbons are withdrawn from tower 3
through line ‘I and are passed to a suitable ao
40 cumulator 8.
The normally gaseous hydrocar
bons from accumulator 8 are conducted through
line 9 to charging line it).
600 pounds per square inch is usually adequate.
The pressure side of compressor pump ll dis
charges through line 12 which terminates in a
nozzle ring l3 located near the bottom of the
absorption tower ill, from whence the lique?ed
gas passes upwardly through the tower counter
56 current to a flow of alkaline solution introduced
50
- into the top of the-tower through nozzle IS. The
invention preferably contemplates the use of di
lute solution of sodium carbonate containing
from 1 to 6% sodium carbonate although other
60 weak alkaline solutions may be employed.‘
The ?ow of lique?ed gas and alkaline solution
is regulated to give the desired purifying effect.
The tower It may, as shown, contain solid con
tact or packing material IT, for example loosely
spaced brick located on spaced trays within the
‘
'
-
tower 2i, in case such gas is introduced, is re
moved from actifying tower'2i through a vent
_pipe 33. Carbon dioxide to replenish that re-'
moved in the actifying tower, or steam, may be
introduced into the bottom of thetower' through
a line 34. An indirect heating coil 35 may be
provided as shown in the bottom of the tower II.
If desired carbon dioxlde'for replenishing the
solution may be introduced ,into the relatively
cooler reacti?ed solution on the high pressure side
of the cycle through line' 36__beyond the cooling
coil 32.
‘
,
The operability of the process is made possible
by relative reaction velocities of the following
reversible reaction under different temperature
and pressure conditions:
40
The charging line
it is provided with a compressor pump H for
compressing the gas below the vaporization pres
45 sure thereof. The pressure required will depend
upon ‘the nature of the gas and may range from
200 to 1200 or more pounds per‘square inch. In
case of re?nery gas a pressure between 300 and
tower.
v
The hydrogen sulphide liberated, combined
with inert gas introduced in the bottom of the
.
Preferably the rings l3 and I! are suf?ciently
spaced from the ends of the tower II to provide
for separating zones below and above ‘the same,
70 respectively.
The‘ puri?ed, lique?ed gas is withdrawn from
the top of tower ll through line I 8 and may be
passed to storage tanks (not shown) or directly
to further‘ processing equipmentv such as a poly
78 merization'unit. The fouled‘ alkaline solution is
lBy liquefying the gases to be treated the concen
tration of the hydrogen sulphide in the puri?er
is increased, thus shifting the reaction equilib 45
rium' to the right to form a relatively larger
proportion of sodium hydrosulphide, and by re
ducing the pressure in the actifier substantially
below that existing in the puri?er and below
the vaporizing pressure of hydrogen sulphide the 50
reaction equilibrium is shifted back to the left,
thus releasing the hydrogen sulphide as a gas.
It will be observed that according to my process,
liquid phase conditions prevail in the puri?er,
whereas in the acti?er the hydrogen sulphide is 55
in vapor phase and is removed from the system
as formed.
It will be understood that fresh solution should
be added to the system continuously or from time
to time to maintain the desired strength and to
replace that lost by unfavorable side reactions. '
Having ‘described the preferred embodiment,
it is understood that my invention embraces
such other modi?cations and variations as come
within the spirit and scope thereof and that it 65
is not my intention to unduly limit the inven-i
tion or dedicate any novel features thereof.
I claim:
1. A method of desulphurizing gases obtained
from oil re?nery operations which comprises sepa 70
rating hydrogen and methane from said gases
to obtain normally gaseous hydrocarbons con
taining at least two carbon atoms per molecule
therefrom, passing said normally gaseous hy
drocarbons through a treating'zone at a tempera- 76
3
lure sui?ciently low and at a pressure su?lciently
. high to maintain said gases in lique?ed condition,
intimately contacting said gases while in lique?ed
state in said treating zone with a sodium car-
bonate solution capable oi’ reacting with sulphur
containing compounds in said lique?ed gas, sepa
rating the thus treated lique?ed hydrocarbons
> from the sodium carbonate solution containing
the sulphur compounds,'passing the sodium car
10 bonate‘ solution containing the ' sulphur com
pounds to'an activation zone, removing said
sulphur'compounds therefrom in said-activation
zone to reactivate the sodium carbonate .tor
15
iurther
carbonate
use."solution
and returning
thus obtained
the reactivated
to said treat
ing zone.
'
,
n
-2. A method of desulphurizing gases obtained
from oil re?nery operations which comprises
I . separating hydrogen and methane from said gases
20 to obtain normally gaseous hydrocarbons con
taining at least two carbon atoms; per molecule
Y therefrom...
said normally saseous hydro
carbons through a treating zone ‘at a temperature .
sui?ciently low and at a pressure sumciently high
to maintain said gases in lique?ed condition, in
timately contacting said gases while in lique?ed
state in said treating ‘zone with a sodium car
bonate solution capable of reacting with sulphur
containing compounds in said lique?ed gas, sepa
rating the thus treated lique?ed hydrocarbons
from the sodium carbonate solution containing
the sulphur'compounds, passing the sodium car—
bonate solution containing the sulphur com
pounds to an activation zone, heating said sodium
carbonate solution containing the sulphur com
pounds in' said activation zone wherein said
solution is reactivated for further use, and re
turning said reactivatedsolution to said treating
zone. ‘
v
f
_
.
3. A method in accordance witnclaim lwhere
in carbon’dioxid'e is added to the solution to re
plenish that, lost during: reactivation thereof.
‘
‘
Homes-1 3’.
20
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