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Патент USA US2411680

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Nov. 26, 1946.‘
I
vw. DENNIS
2,411,680
SEPARATION OF THE CONSTITUENTS OF GASEOUS vlIVX'JfIJRE-S
~ Filed larch 7, ‘1944
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INVENTOR
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BY
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ATTORNEYS
‘2,411,680 "
Patented Nov. 26, 1946
UNITED STATES PATENT orrlcs _
. SEPARATION OF THE CONSTITUENTS OF
GASEOUS MIXTURES
.
Wolcott Dennis, Darien, Conn.,.assignor_ to Air’
Reduction Company, Incorporated, New York, ,
N. Y., a corporation of New York
'
Application Miami 7, 1944, Serial No. 525,385
a claim.
(oi 62-4755) ’
i
the possibility that impurities and particuiarly
This invention relates to the separation of the
constituents of gaseous mixtures by liquefaction
and recti?cation and particularly to the recovery
of oxygen and nitrogen from the atmosphere.
oil andhydrccarbcns derived therefrom can be
concentrated at a point where oxygen or vapors
materially enriched in oxygen occur is eliminated.
The products are free from such impurities. No
substantial loss of the constituents or of refrig
erative e?ect results from the procedure as de
scribed. A similar procedure can be utilized to
Although described hereinafter in more detail
with reference to the treatment of air, the meth
od ‘may be utilized in separating the constituents
v of other gaseous mixtures.
>
prevent accumulation of impurities present in
trogen'from air, the problem of removing carbon 10 other gaseous mixtures which are to be separated
for thepurpose of recovering the constituents
dioxide, water, oil and hydrocarbons present
thereof.
therein introduces certain di?lculties. Scrubbers
In the commercial recovery of oxygen and ni
may be utilized to treat the air before or after
compression, but such devices are not completely
effective, particularly in connection with oil and
In order to avoid material loss of recti?cation
e?iciency in the recti?cation column, the liquid
15 fraction carrying impurities should be evaporated
decomposition products thereof. Oil introduced
by heat exchange with vapors at the highestpos
by oil-lubricated compressors and hydrocarbons
derived therefrom by decomposition are particu
larly troublesome. The accumulation of oil and
other hydrocarbon compounds at points where
sonable' temperature difference for operation.
'In a column separating high purity oxygen from
'air, a considerable number of trays is required
oxygen or gases enriched in oxygen occur, is un
desirable. Various procedures designed to pre
vent such accumulation have been suggested.
sible level in the column which will afford a rea
in the lower portion of the low pressure recti?er
to separate oxygen from argon. This separation
' is quite dimcult compared with the separation
These are generally complicated or introduce sub
of nitrogen from oxygen which is carried out
stantial losses in emciency.
mainly in the upper portion of the low pressure
rectifier. An appropriate location for the evapo
ration of the impure liquid fraction by condensa
tion of vapors in the column would be that point
where‘the concentration of nitrogen in the va
pors is low and just above that portion of the low
-
It is the object of the present invention to af
ford a simple and e?ective method whereby ‘un
desirable impurities in the gaseous mixture treat- .
ed may be eliminated readily without interfering '
materially in the proper and emcient function-'
ing of the desired separation and recovery of the
constituents. Other objects and advantages of
the invention will be apparent as it is better un
derstood by reference to the following speci?ca
tion and the accompanying drawing, which dia
grammatically illustrates an apparatus suitable
for the practice of the invention. Details of the
. pressure rectifier in which the main separation
is between oxygen and argon. By choosing such
a location sumcient temperature di?'erence is
made available
without material interference ‘
with the di?lcult separation of oxygen and argon.
Referring to the drawing, K5 indicates a recti
' ?cation column having a lower section 6, a con
apparatus which are well known in the art have
denser section 1, two recti?er sections 8 and 9
been omitted for the purpose of clarity.
and an intermediate vaporizer section It. The
I have discovered that the impurities present 40 sections 8, 8' and 9 are provided with the usual
in air which is su'ppliedto a system designed to
trays H and bubble caps If to facilitate intimate
separate and recover oxygen and nitrogen there
contact of vapors and liquids ?owing there
from may be concentrated in a liquid fraction of
through. At the top of the section 8, a pipe it
the air treated and ‘that the refrlgerative effect of
permits‘the withdrawal of the e?luent which in
the liquid can be recoverede?ectively by trans
the case of air is principally nitrogen; The other
ferring the liquid to an appropriate level of the
product, for example oxygen, is withdrawn
recti?cation column and there, evaporating it by
through a pipe I‘ which is connected to the con
indirect heat exchange with vapors in the column
denser section 1.
v
v
at a point such that little if any loss of recti?
The gaseous mixture to be treated, for example
cation e?lclency results. The vapors from the liq 50 air, after compression to a suitable pressure, for
example 15-20 atmospheres absolute, drying in
uid can be introduced to the column in order to
the usual equipment to remove substantially all
retain the valuable constituents thereof. By
withdrawing a portion of the liquid in which the
‘of the moisture, ‘and cooling, is introduced
impurities are concentrated, the latter may be
through, a pipe It to an exchanger l6 and after
removed from the system. By this procedure, 55 circulating-about tubes l1 and‘ I8 therein, carry
2,411,680
‘.3
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4
.
.
iler and thence through a pipe 43 to the tubes ll
of the exchanger. It may be, withdrawn through
a pipe 50 and discharged to the atmosphere or
ins cold products of the separation. the air is de
livered to a pipe l3. A pipe 20 delivers the cooled
air to a lique?er 22 wherein it circulates about
to any suitable receptacle for storage. The oxy
tubes 23 and 24' carrying cold products of the
gen which is evaporated from the. liquid in the
separation. The‘ {air is lique?ed and the liquid is ‘
delivered through a pipe 25 and pressure reducing - condenser ‘I’ and withdrawn through the pipe
it passes through the tubes 23 of the liqueiier '
valve 26 to a separator 21 having trays 28 and
and thence through a pipe ii to the tubes it of
bubble caps 29.
'
' the exchanger. It may be withdrawn through
The remainder of the air is delivered through
a pipe 80 tom expansion engine 3| of the usual 10 a pipe 52 and delivered to any suitable storage
receptacle.
By the procedure as described, the‘ impurities
and particularly oil and hydrocarbon derivatives,
type wherein the air is expanded with external
Wul‘k, and thereby cooled. After expansion, the
air is delivered through a pipe 32 to the separator
21. The air passes upwardly through the trays
are removed from the gaseous mixture which is
15 to undergo liquefaction and accumulated in
23, of which any suitable number may be pro
a liquid. Refrigeration losses are avoided by
vaporizing this liquid at an appropriate level in
the rectifier. The refrigeration is thus conserved
vided, in contact with the lique?ed air ?owing
downwardly thereover. Impurities present in
the liquid and the vapor phase air are accumu
lated in the liquid'that collects in the bottom of
the separator. The air freed from such impuri
ties is delivered through a pipe 33 to the section
6 of the ‘column. It passes upwardly through
the trays II in contact with liquid produced as
the air ?ows through tubes 34 of the condenser
section ‘I in heat exchange with liquid surround
ing the tubes. As the result, a liquid accumulates in the bottom of the section 6 which is sub
stantially enriched in oxygen, usually containing
approximately 40% of that constituent. This
liquid is delivered through a pipe 35 and valve 38
to an intermediate level of the section 3 of the
column.
_
That portion of the air which is not lique?ed
in the tubes 3t continues to the head 31 and
and the vapors from the liquid are likewise re
20 tained and separated to recover the desired con
stituents.
-
Various changes may be made in the form and
arrangement of the apparatus and in the de
tails of the‘ procedure without departing from
25 the
‘
invention or sacri?cing the advantages
thereof.
I claim:
-
‘
' 1. The method of separating the constituents
of gaseous mixtures which comprises liquefying
30 a portion of the compressed and cooled gaseous
mixture, preliminarily scrubbing the remainder
of the gaseous mixture with the liquid portion
thereof to provide a vapor free from impurities
and a liquid in which the impurities are con
thence downwardly through the tubes 38. The 35 centrated, subjectng said vapor to liquefaction
to provide a liquid substantially free from im
liquid formed therefrom is gathered in a col
purities and separate from the liquid previously
lector 33 from which it is withdrawn through a
pipe at and valve M and delivered to the top of ' formed during the preliminary scrubbing opera
tion, subjecting said second liquid to recti?cation,
the section 9 of the column. This liquid is sub
stantially pure nitrogen and affords the reflux 40 bringing the liquid in which the impurities are
concentrated into indirect heat exchange with
liquid necessary to complete the separation of
vapors produced during the recti?cation to there
the constituents of the‘ gaseous mixture by recti—
by liquefy a portion of such vapors, and adding
?cation.
.
the liquid thus produced to the recti?cation as
The, liquid from the separator 21 is withdrawn
,
through a pipe 52 controlled by a valve 43 and 45 re?ux.
2. The method of separating the constituents
delivered to the vaporizer section ill of thecol
of gaseous mixtures which comprises liqueiying
umn where it surrounds tubes 44 through which
a portion of the compressed and cooled gaseous
vapors rising through the column must pass.
mixture, preliminarily scrubbing the remainder
I The vaporizer it! may be disposed externally of
the column and connected thereto so that vapors 50 of the gaseous mixture with the liquid portion
thereof to provide a vapor free from impurities
from the desired level will be delivered thereto
- for heat exchange with liquid supplied from the
separator 27. The vapors are partially con
and a liquid in which the impurities are concen
trated, subjecting said vapor to liquefaction to
provide a liquid substantially free from impuri
densed by heat exchange with the liquid in the
vaporizer section it! and the liquid product flows 55 ties and separate from the liquid previously
formed during the preliminary scrubbing opera~
downwardly onto the trays of the section 8 of
tion, subjecting said second liquid to recti?ca
the column, thus a?ording additional liquid en
tion, passing the liquid in which the impurities
riched in oxygen to facilitate the recti?cation‘.
Liquid from the section 9 of the column is deliv
are concentrated into an intermediate level of
ered to the section 8 through a pipe 45. The im 60 the recti?cation and there maintaining it in in
direct heat exchange with vapors present to
pure liquid in the vaporizer section III is vapor
liquefy a portion of such vapors and provide re
ized, except for the portion hereinafter men-'
?ux liquid for use in the recti?cation.
tioned, and the vapor is delivered by a pipe 46 to
the section 9 of the column Where it mingles with
3. The method of separating the constituents
vapors rising through the section and with the 65 of gaseous mixtures which comprises liquefying
liquid ?owing downwardly therethrough. A por
a portion of the compressed and cooled gaseous
tion of the liquid‘ is withdrawn from time to time
mixture, preliminarily scrubbing the remainder
through a pipe #7 controlled by a valve 48. By
of the gaseous mixture with the liquid portion
such withdrawal the impurities which have accu
thereof to provide a vapor free from impurities
mulated in the liquid are eliminated from the sys 70 and a'liquid in which the impurities are concen
tem. It is necessary to withdraw only a relatively
trated, subjecting said vapor to liquefaction to
small amount of liquid in order to effect the pri
provide a liquid substantially free from impuri
_
ties‘ and separate from the liquid previously
formed during the preliminary scrubbing opera
The eiiiuent nitrogen withdrawn through the
pipe 83 passes through the tubes 24 of the lique 75 tion, subjecting said second liquid to recti?ca
mary purpose of the invention.
2,411,050
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5
.
tion, subjecting vapors from an intermediate
tion, subjecting said second liquid to recti?ca
level of the recti?cation to backward return con
' tion, subjecting vapors from an intermediate
densation by indirect heat exchange with the
liquid in which the impurities are concentrated,
to thereby liquefy a portion of such vapors, and
adding the liquid thus formed to the recti?ca
tion as re?ux.
4. The method of separating the-constituents
of gaseous mixtures which comprises liquefying
level of the recti?cation to backward return con
densation by indirect heat exchange with the
liquid in which the impurities are concentrated,
to thereby liquefy a portion of such vapors, add
ing the liquid thus produced'to the recti?cation
as re?ux, and adding vapors produced by result
ant vaporization of a part of the liquid in which
a portion of the compressed and cooled gaseous 10 the impurities are concentrated to the recti?
mixture, preliminarily scrubbing the remainder
of the gaseous mixture with the liquid ‘portion
thereof to ‘provide a vapor free from impurities
and a liquid in which the impurities are con- '
cation.
'
7. The method of separating the constituents
of gaseous mixtures which comprises liquefying
a portion of the compressed and cooled gaseous
centrated, subjecting said vapor to liquefaction 15 mixture, preliminarily scrubbing the remainder
_ of the gaseous mixture with the liquid portion
to provide a liquid'substantially free‘from im
thereof to provide a vapor free from‘ impurities
purities and‘ separate from the liquid previously
and a liquid in which the impurities are con
formed‘ during the preliminary scrubbing opera
centrated. subjecting said vapor to liquefaction
tion, subjecting said second liquid to recti?ca
to provide a liquid substantially ‘free from im
tion, bringing the liquid in which the impurities‘ 20 purities and separate from the liquid previously
are concentrated into indirect heat exchange
with vapors produced during the recti?cation to‘
thereby liquefy a portion of such vapors, adding
the liquid thus produced to the recti?cation as 25
re?ux, and adding vapors produced by resultant
vaporization of a part of the liquid in which the
impurities are concentrated to the recti?cation.
5. The method of separating the constituents
of gaseous mixtures which comprises liquefying 30
a portion of the compressed and cooled gaseous
formed from the preliminary scrubbing opera
tion, subjecting said second liquid to recti?ca
tion, subjecting vapors from an intermediate
are concentrated into an intermediate level of
portion to provide a vapor free of impurities -
the recti?cation and there maintaining it iniin
direct heat exchange with vapors present to
centrated, subjecting said vapor to liquefaction
level of the recti?cation to indirect heat ex~
change'with the liquid in which the impurities
arevconcentrated, to thereby .liquefy a portion
of such vapors, adding the liquid thus formed
to the recti?cation as re?ux, adding vapors pro
duced by resultant vaporization of a part of'the
liquid in which the impurities are concentrated
mixture, preliminarily scrubbing the remainder
to the recti?cation, and discarding the balance
of the gaseous mixture ‘with the liquid portion
of the liquid containing the impurities.
thereof to provide a'vapor free from impurities
8. The method of separating the constituents
and a liquid in which the impurities are con 35 of gaseous mixtures by liquefaction and recti?
centrated, subjecting said vapor to liquefaction _ cation which comprises cooling the compressed
to provide a liquid substantially free from im-'
gaseous mixture, liquefying a portion thereof by
purities and separate from the liquid previouslyv
heat exchange with cold products of the separa
‘formed during the preliminary scrubbing opera- I
tion, expanding the "remainder of the gaseous
tion, subjecting said second liquid to recti?ca 40 mixture to a lower pressure, preliminarily scrub
tion, passing the liquid in which the impurities
hing the expanded portion‘ with the liqui?ed
and a liquid in which the impurities are con
liquefy a portion of such vapors, adding the liquid 45 in two fractions separate from the liquor pre
viously formed during the preliminary scrubbing
adding vapors produced by resultant vaporiza
operation and respectively enriched in the higherv
thus produced to‘ the recti?cation as re?ux, and .
tion of a part of the liquid in which the im
purities are concentrated to the recti?cation.
and lower boiling constituents of the gaseous
mixture and to recti?cation, subjecting vapors
6. The method of separating the constituents 60 from an intermediate level of the recti?cation to
of gaseous mixtures which comprises liquefying
indirect heat exchange with the liquid in which
a‘ portion of the compressed and cooledv gaseous
the impurities are concentrated to thereby lique
ty a portion or such vapors and to vaporize a
mixture, preliminarily scrubbing the remainder
- of the gaseous mixture with the liquid portion
portion of the liquid containing the impurities,
thereof to provide a vapor free from impurities 55 adding the liquid thus formed to the recti?cation
as re?ux, adding the vapor produced by the
and a liquid in‘which the impurities are con
partial vaporization of the liquid containing the
impurities to the recti?cation, and withdrawing
purities and separate from the liquid previously
the balance of the liquid containing impurities.
formed during the preliminary scrubbing opera- ‘0'
WOLCO'IT DENNIS.
oentrated, subjecting said vapor to liquefaction
to provide a liquidv substantially‘ free from im
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