UNITED` `STATES PATENT OFFICE

‘ Patented Mar. 3, 1,931
1,794,371
UNITED‘ ‘STATES PATENT OFFICE
RUDOLPH LEONARD HASCHE AND vVVILLIANI
BARGAIN’, OF ELIZABETH, NEW JERSEY,
’ ASSIGNOBS -'1‘O AMERICAN SMELTING- AND ~ REFINING COMPANY, OF NEW YORK,
N. Y., A CORPORATION OF NEW JERSEY '
‘SEPARATION or GASES
No Drawing.
Application ?led August 25, 1927. Serial No. 215,527.
This invention relates to the separation its objects and advantages, the mode of its
and recovery of gases and vapors from a operation and the manner of its organization
mixture thereof, and more particularly to a may be better understood by referring.to the
method of adsorbing and liberating gases by following description in which a particular
meansof a solid adsorption material.‘
commercial embodiment thereof is disclosed.
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Various solid adsorption materials such It will be understood however, that the
as silica gel, activated charcoal iron oxide processes and the steps thereof may be modi~
gel and alumina, are capable of selectively ?ed in various respects without departing
adsorbing and removing, various gaseous from the broad spirit and scope of the inven- .
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substances from mixtures in which these sub
?OIl.
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stances are present in varied proportions.
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In the following description and in the
In order, however, to drive o?f the adsorbed claims the various steps in the‘ process and
gases from the adsorption material it is nec the details comprising the invention will be‘
essary to subject the same to conditions dif identi?ed by speci?c names for convenience
fering from those under ‘which adsorption but they are intended'to be as generic in their
application as ‘the art will permit.
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For example, the gases may be adsorbed _ The process in accordance with the present
_ by the material while the. latter is in a com invention is based upon certain well known
occurred.
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paratively cool condition‘ and later desorbed and established principles of behavior of
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by means of heat. Since adsorption mate
rials'are ‘frequently poor conductors of heat
however, this operation may be slow and at
times ine?icient; jFurthermore, a consider
gaseous substances. For example, in accord 70'
ance with the law of partial pressures, in a
mixture of gases each gas exerts the same
pressure as it would exert if it were alone
able temperature .di?'erence is required'be present, in the volume occupied by the gas
tween the adsorption and desorption points mixture. Furthermore, the solubility of a, 75
~Which necessitates applying a substantial gas contained in‘ a gas mixture depends upon
amount of heat to the material and subse thepartial pressure of that gas.
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quently arti?cially cooling the same before Considering these two gas laws, it is evi
further adsorption.
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dent that the ability of an adsorbent to dis
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In accordance with the present invention, solve a certain gas from a mixture in which
a method of treating adsorption material is it is contained is dependent-‘entirely upon
providedin which the temperature is main
tained constant for both the__adsorption and
desorption steps, the 1 required properties
being obtained by varying the pressure of the
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the pressure of that gas in said mixture and
is not dependent upon the relative purity
thereof. Assuming that the temperature is
maintained constant, the amount of gas re 85
gases within the material. The process may, moved from the mixture will be proportional
therefore, be described as substantially 1so-' to the pressure which is maintained on the ad
thermal and utilizes the property of the ads sorbing material and the rate at which the
sorptive material whereby the amount of
adsorbed gas is liberated at reduced pressure
tional to the vaseous pressure.
adsorption and desorption pressures.
gases held therein is ‘substantially propor will depend upon the difference between the
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The invention further consists in the new
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Considering, for example, a gas mixture
and novel features of operation and the new which ‘contains, at atmospheric pressure, 10%
and original arrangements and combinations
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of a particular gaseous ingredient such as
of steps in the process hereinafter described sulphur dioxide, it is evident-that the sul
and more particularly set forth in the claims. phur dioxide itself will exert a pressure ‘of
Although the novel features which are-be one-tenth of an atmosphere and that the ad—
lieved to be characteristic of this invention sorbent material will adsorb the same amount
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will be particularly pointed out in the claims thereof from an air mixture containing 10%
50 appended hereto, the invention itself, as to of sulphur dioxide as from a pure sulphur 10°
1,794,877
dioxide at the same partial pressure-namely, leaving the relief valve unadsorbed, the rich
one-tenth of an atmosphere. As a'further compressed gases are shunted to a second ad
example, the adsorbent material should ad sorber and the ?rst adsorber is opened to the
' 'sorb approximately as much sulphur dioxide low pressure side of a compressor. The ad
from a gas'mixture containing 10% of sul sorbed gases are then liberated at reduced 70
phur dioxide by volume at a pressure of 20 pressure and recovered. If desired, the dis
atmospheres as from pure sulphur dioxide at tillation of gas from the adsorber may be
a pressure of 2 atmospheres.
, speeded up during the desorption part of the
It is evident from the above that by main cycle, by applying some heat to the water
taining
the pressure of a gaseous mixture coils within the gel bed to balance the cool 75
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containing 10% sulphur dioxide at approxi ing effect due to the evaporation of the sul
mately 20 atmospheres during the adsorption phur dioxide from the pores of the adsorbent.
The liberated gases may be cooled by suit
process and subsequently reducing the pres
sure to atmospheric, approximately half the able refrigerating coils to a temperature at
which they may be readily lique?ed by pres 80
15 adsorbed sulphur dioxide will be liberated.‘
By reducing the pressure below atmospheric, sure. Suitable pressure ma then be applied
a greater proportion thereof may be de-‘ to bring the sulphur dioxi e into the liquid
state and the liquid allowed to ?ow by gravity
sol-bed and recovered;
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In carrying on this process, a gaseous sub into storage tanks.
In accordance with the present invention,
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nitrogen ‘dioxide, carbon dioxide, chlorine sulphur dioxide may be separated from the. >
and others may be adsorbed by a suitable
material such as silica gel, activated char
/ coal, iron oxide gel or alumina, and may be
25 liberated from said material and recovered
gaseous mixture as by means of silica el and
distilled from said gel without change in tem
perature. A greater ei?ciency is consequent
ly obtained since a given weight of adsorbent
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by merely changing the pressures, preferably will recover more sulphur dioxide per cycle
While the temperature is maintained constant. than when changes in temperature are relied
The invention will be described as applied upon for the adsor tion and desorption steps.
The method re uces the moisture content
to the recovery of sulphur dioxide from
smelter gases by the use of silica gel as an of the gases to a degree corresponding to the
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adsorbent material although these substances pressure employed, since the moisture content
depends upon the temperature and volume.
are chosen by way of illustration only.
The gaseous mixture, for example, smelter Consequently by keeping the temperature
gases containing sulphur dioxide should ?rst constant and reducing t e volume to one
be cleaned to remove fumes and dust. Any tenth of the-original volume, a gas will be 100
standard method of cleaning may be em formed having a moisture content only ten
ployed, the details of which form no part oi‘: per cent of that of the original gas.
Although certain novel features of the in
the present invention. The cleaned gas may
then enter a compressor where it is com vention have been shown and described and
pressed to such a pressure that the adsorbable are pointed out in the annexed claims, it will 105
constituent, in this case sulphur dioxide, has be understood that various omissions, substi
a partial pressure above atmospheric but be tutions and changes in the several steps of the
low its own critical pressure. In the case of process and in its operation may be made by
sulphur dioxide, a partial pressure of about those skilled in the art without departing
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two atmospheres has been found satisfactory. from the spirit of the invention.
The heat of compression may be removed by What is claimed is:
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cooling coils or other suitable means and the . 1. The method of separating a gas from
>mist composed of water vapor may bev re a gas mixture which comprises subjecting
moved by passing thea gas through a suitable said mixture to a su?iciently high pressure so
that the partial pressure of the gas to be sepa
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The gas may then enter the adsorption rated is substantially above atmospheric,
chamber which is pressure-tight exce t for a passin said mixture under said ressure
so separator.
relief valve which is set to blow at t e pres
sure selected for the adsorption. The
stri ped gases are thus vented continuously
or mtermittentlythrough the relief 'valve.
The adsorbent should preferably be cooled
during the adsorption as by cold water circu
throug a material capable of adsor ing the
gas to be separated whereb
a substantial
part of said gas'is separated and adsorbed
thereby and removed from the mixture, de
sorbing said gas by reducing the pressure on
said adsorbent material whereby said gas is
lating through pipes in the adsorbent bed. liberated, supplying su?icient heat to said
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The stripped gases may be utilized to assist adsorbent material uring desorption to bal
in compressing-the incoming gases if desired ance the latent heat of vaporization of said
as by being applied to the low pressure side gas and to maintain the temperature of said
material substantially constant whereby the
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When the adsorption part of the cycle is ; process is carried out substantially isother
complete as evidenced by sulphur dioxide mally and recovering the liberated gas.
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of the compressor.
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14,794,877
2. The method of separating a gas from
a gas mixture which comprises subjecting
said mixture to a sufficiently high pressure
so that the partial pressure of the gas to be
separated is approximately two atmospheres,
passing said mixture under said pressure
_ through a material capable of adsorbing the
gas to be separated whereby a substantial part
of said gas is separated and adsorbed there
by
and removed from the mixture, desorb
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ing said gas by reducing the pressure on said
adsorbent material to approximately'atmos
pheric whereby said gas is liberated, sup
plying su?icient heat to said adsorbent ma
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terial during desorption to balance the latent
heat of vaporization of said gas and to main
tainthe temperature of said material sub-.~
stantially constant whereby the process is
carried out substantially isothermally and
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recoverinir the liberated gas.
In testlmony whereof we have hereunto
set our hands.
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RUDOLPH LEONARD HASCHE.
WILLIAM H. DARGAN.
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