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Oct. 15, 1946.
c. c. VAN NUYS
2,
SEPARATION_ OF THE CONSTITUENTS OF GASEOUS MIXTURES
Filed April 27, 1945
MEGRQ,.
,458
2,409,458
Patented Oct. 15, 1946
UNITED STATES PATENT OFFICE
2,409,458
SEPARATION OF THE CONSTITUENTS OF
GASEOUS MDITURES
Claude C. Van Nuys, Greenwich, Conn, assignor
to Air Reduction Company, Incorporated, New
York, N. Y., a corporation of New York
Application April 2'1, 1943, Serial No. 484,720
9 Claims.
(01.62-1755)
1
This invention relates to the liquefaction and
separation of the constituents of gaseous mix~
tures and particularly to a method of recovering
one of the constituents substantially free from
impurities and in the liquid phase.
The invention will be described in connection
with the liquefaction of air and the recovery of
liquid oxygen. It may be used, however, in the
treatment of other gaseous mixtures to recover
desired constituents thereof.
The liquefaction and separation of the con
stituents, particularly oxygen and nitrogen, of
atmospheric air, has been practised commercially
for many years. The constituents are ordinarily
withdrawn and stored as gases. For certain pur
2
.
est compartment, A, is provided with the usual
trays 5 having bubble caps l or other convene
ient means to effect maximum contact between
vapors rising throughthe compartment and liq
uids descending therein. The compartment B
comprises groups of tubes 8 and 9 through which
vapors may rise and then descend in heat ex
change relation with a liquid surrounding the
tubes. The compartment C includes a plurality
10 of trays 10 with the usual bubble caps I I or other
means to facilitate recti?cation.
‘
Air, after initial compression to a relatively
high pressure and subsequent cooling, is expand
ed in an expansion engine [2 of the usual type
1,5 employed in the well known “Claude process.”
poses, supplies of liquid oxygen are desirable. The
liquid can be obtained by compressing and cool
ing the gaseous product of the separation, but
The air, at a pressure somewhat above one at
the use and loss of‘ energy and hence permits
attainment of the object in a commercially eco
an expansion valve l8 to an intermediate level
mosphere, is delivered by a pipe 13 to the com
partment A and rises through the trays 6 in con
‘ this involves the application of additional energy
tact with liquid formed as hereinafter described.
and the construction and maintenance of elab 20 Lique?ed air is delivered by a pipe l4 controlled
orate equipment for compressing, drying and
by a valve IE to a coil I6 in the bottom of the
cooling.
compartment A in which it is surrounded by a
It is the object of the present invention to
liquid product of the separation consisting of
afford a simple, efficient and readily operable
approximately 38%-40% oxygen, the balance
method of prOduCing from a mixture of'gases a 25 being nitrogen. The lique?ed air is delivered
pure gas, such as pure oxygen, which minimizes
from the coil 16 through a pipe ll controlled by
of the compartment A from which it ?ows down
wardly over the trays 6 in contact with the air
Other objects and advantages of the invention 30 introduced through the pipe 13.‘
'
will be apparent as it is better understood ‘by
Vapors rising from the bottom of the compart
reference to the following specification and the
ment A and vapors formed therein, together with
accompanying drawing, which illustrates dia
the air introduced through the pipe. 13, enter the
grammatically an apparatus suitable for the prac
tubes 8 of the compartment B. In rising through
tice of the invention. Numerous details of the
the tubes, the air is subjected, by heat exchange
apparatus which are familiar in the art have
with liquid and vapors surroundingthe tubes, to
been omitted for the purpose of clarity. The in~
“backward return” condensation, thus providing
vention, moreover, is not limited to the use of
a liquid enriched in oxygen which descends
any particular apparatus or to the arrangement
through the trays 6 of the compartment A, and
thereof as illustrated in the‘drawing.
a vapor enriched in nitrogen which is delivered
I have discovered that it is possible to pro~
to the head l9. These vapors descend through
duce a lique?ed constituent such as oxygen in
the tubes 9 to a collector 20, and. being condensed
the operation of a liquefaction system by uti
in the tubes, afford a liquid enriched in nitro
lizing cold available in the products of the sys
gen which is withdrawn through the collector 20
tem and without expending additional energy for
by a pipe 2| controlled by an expansionvalve
.the'compression of the desired constituent in the
22 and delivered to the top of the column 5, where
gaseous phase. Furthermore, the procedure as
it serves as a’ re?ux liquid descending over the
described permits a further purification of the
trays l0 therein. Thus the low pressure air 15
desired constituent by eliminating therefrom im
purities, which may be present, during the liq- ’ separated into two liquid ‘portions, one enriched
in oxygen and the other in nitrogen. The liq
uefaction procedure.
uid enriched in oxygen from thebottom of the
The invention will be readily understood‘ by
compartment A_ is delivered through a pipe 23
_ reference to- the drawing, in which 5 indicates
controlled by an expansion valve 24 to an inter
a liquefaction and recti?cation column divided
mediate level of the compartment C and descends
into three compartments, A, B, and C. The low
nomical manner.
2,409,458
over the trays I0 therein in contact with vapors
rising through the compartment.
As the result of the operation as described,
the air in the liquid and vapor phases is ?rst
subjected by backward return condensation and
recti?cation, to partial enrichment in oxygen,
the balance of the vapor being condensed to af
ford the nitrogen re?ux. As the liquids descend
through the compartment C of the column, a
continuous exchange occurs as the result of rec
ti?cation to produce substantially pure oxygen
liquid which passes into the compartment B and
4
from the top of the column 5. The cold nitro
gen, by heat exchange with the liquid in the
coil 52, reduces the temperature thereof. The
nitrogen escapes through the pipe 37 to the tubes
36 of the lique?er 35. The sub-cooled liquid
oxygen from the coil 52 is delivered by a pipe 53
to a liquid pump 54 which forces the liquid un
der high pressure, such for example as 2,000
pounds per square inch, into an exchanger 55
10 where it surrounds tubes 56. A portion of the
high pressure air from the pipe 26 is delivered by
a pipe 5‘! controlled by a valve 58 to the tubes 56,
accumulates about the tubes 8 and 9 in the com
and being cooled by heat exchange with the
partment B and an effluent consisting principal
liquid oxygen at high pressure, is delivered to the
ly of nitrogen which escapes through the pipe 15 pipe 59 and thence to the pipe 32 from which it
25 at the top of the column.
is diverted in the desired proportions to the
The air entering the system, after being com
lique?er 35 and the expansion engine l2. The
pressed to high pressure and cooled in the usual
cold oxygen vaporized in exchanger 55 is with
manner, is introduced through a pipe 26. The
drawn through a pipe 60 and delivered to suit
major portion thereof is delivered through a pipe 20 able storage facilities.
2'! controlled by a valve 28 to an exchanger 29
As will be evident from the foregoing descrip
through which it passes in heat exchange rela
tion, all of the refrigeration required for the ulti
tion with gaseous products of the separation
passing through the tubes 30 and 3| of the ex
changer. The air is thereby further cooled and
is delivered through a pipe 32. A portion of the
air which is still at high pressure is delivered
through the pipe 33 to the expansion engine I2
as hereinbefore described. The balance of the
mate liquefaction of the oxygen product is sup
plied by the system without the necessity for ex—
ternal refrigeration or an additional input of
energy for compression except in respect to the
liquid pump 54. Furthermore, no waste of gas
eous constitutents introduced to the system is
possible because all of the gaseous mixture is ul
high pressure air passes through a pipe 34 to the 30 timately separated and the constituents nitrogen
lique?er 35 and circulates about tubes 38 therein
and oxygen are effectively separated and recov
to which cold nitrogen from the top of the col
ered. A portion of the recovered oxygen is in the
umn 5 is delivered by a pipe 3'! after the nitrogen
desired liquid phase and the balance is recovered
has been utilized as hereinafter described. The
in the vapor phase. The system is capable of e?i
nitrogen escapes through a pipe 38 to the tubes ‘
cient and economical operation because of the
30 of the exchanger 29 and is ?nally delivered
avoidance of losses with respect to products and
through a pipe 39 to the atmosphere or to stor
losses of energy through failure to utilize the re
age, as may be desired.
frigerating effect provided in the system.
The liquid from the lique?er 35 is withdrawn
As hereinbefore indicated, other gaseous mix
through a pipe 40, and a portion thereof is deliv 40 tures may be similarly treated to accomplish the
ered by the pipe M to the coil l6 as hereinbefore
recovery of one of the constituents in the liquid
described.
phase and the use of the invention for such pur
To obtain pure liquid oxygen, as the desired
poses comes within the scope of the invention.
product, I withdraw oxygen vapor from the com
Various changes may be made in the form and
partment B of the column 5 at a level above the .2. Cl arrangement of the apparatus and in the details
level of the liquid oxygen in the compartment
of procedure without departing from the inven
through a pipe 4|. A portion of the oxygen va
tion or sacri?cing the advantages thereof.
por can be diverted through a pipe 42 controlled
I claim:
by a valve 43 to the exchanger 29 wherein it pass
1. The method of separating air into its con
es through the tubes ill and is ?nally withdrawn bx) stituents, oxygen and nitrogen, which comprises
through a pipe 43' and delivered to suitable stor
compressing and cooling air at high pressure,
age facilities. The portion which is to be lique
liquefying a portion thereof at such high pres
?ed passes through a pipe M to a condenser 45
sure, subjecting the remainder of the air to a
wherein it passes upwardly through a plurality
reduction in pressure and liquefaction in two
of tubes 45 surrounded by liquid air from the
portions, one rich in oxygen and the other rich
lique?er 35 which is introduced through a pipe 4'!
in nitrogen, subsequently rectifying said portions
controlled by a valve 138. The liquid air is va
to produce separate fractions, one consisting es
porized in cooling the oxygen introduced through
sentially
of oxygen and the other consisting es
the pipe 44, and the vapor escapes through a pipe
sentially of nitrogen, Withdrawing oxygen from
49 and is delivered to an intermediate level of the (A) said one fraction in the gaseous phase and sub
compartment 0 in the recti?er wherein it is sub
jected to recti?cation with the descending liquid
to effect the desired separation of the constit
uents.
,
In passing upwardly through the tubes 46, the
oxygen is subjected to further “backward return”
liquefaction, thus eliminating any impurities such
as nitrogen which may remain in the vapor. The
vapor passing from the top of the condenser 45 is
delivered through a pipe 53 to the pipe 42 and
thus joins the oxygen which is withdrawn as a
gaseous product. The pure liquid oxygen de
scends through the tubes 135 into a collector 5i
and thence passes through a coil 52 which is sur
rounded by cold nitrogen supplied by the pipe 25
jecting it to backward return condensation by
heat exchange with at least a part of the portion
of the air lique?ed at said high pressure, and sep
arately withdrawing the liquid oxygen and the
uncondensed residue thereof from the Zone of
backward‘ return condensation.
2. The method of separating air into its con
stituents, oxygen and nitrogen, which comprises
compressing and cooling air at high pressure, liq
uefying a portion thereof at such high pressure,
subjecting the remainder of the air to a reduc
tion in pressure and liquefaction in two portions,
one rich in oxygen and the other rich in nitro
gen, subsequently rectifying said portions to pro
duce separate fractions, one consisting essen
2,409,458
6
,
tially of oxygen and the other consisting» essen
tially of nitrogen, withdrawing oxygen from said
the oxygen, to the zone of recti?cation for lique
one fraction in the gaseous phase and subjecting
it to backward return condensation by heat ex
stituents, oxygen and nitrogen, which comprises
compressing and cooling air at high pressure,
liquefying a portion thereof at such high pres
I change with at least a part of the portion of the
air lique?ed at said high pressure, separately
withdrawing the liquid oxygen and the uncon
densed residue thereof from the zone of back
faction of oxygen contained therein.
- r 6. The method of separating air into its con
sure, subjecting the remainder of the air to a re
duction in pressure and liquefaction in two por
tions, one rich in oxygen and the other rich in
ward return condensation and sub-cooling the
liquid oxygen by heat exchange with said other 10 nitrogen,‘ subsequently rectifying said portions
to produce separate fractions, one consisting es
sentially of oxygen and the other consisting es
3. The method of separating air into its con
sentially of‘nitrogen, withdrawing oxygen from
stituents, oxygen and nitrogen, which comprises
said one fraction in the gaseous phase and sub
compressing and cooling air at high pressure, liq
uefying a portion thereof at such high pressure, 15 jecting it to backward return condensation by
heat exchange with at least a part of the por
subjecting the remainder of the air to a reduc
tion of the air lique?ed at said high pressure,
tion in pressure and liquefaction in two portions,
separately withdrawing the liquid oxygen and
one rich in oxygen and the other rich in nitro
the uncondensed residue thereof from the zone
gen, subsequently rectifying said portions to pro
of backward return condensation, delivering the
20
duce separate fractions, one consisting essen
fraction.
‘
-
i
-
air vaporized in cooling the oxygen to the zone
of recti?cation for liquefaction of oxygen con
tially of oxygen and the other consisting essen
tially of nitrogen, withdrawing oxygen from said
one fraction in the gaseous phase and subjecting
tained therein, sub-cooling the liquid oxygen by
heat exchange with said other fraction, pump
it to backward return condensation by heat ex
change with at least a part of the portion of 25 ing the liquid oxygen from the zone of subcool
ing to a relatively high pressure, and utilizing the
cold of the liquid oxygen at high pressure to cool
the air lique?ed at said high pressure, separately
withdrawing the liquid oxygen and the uncon
densed residue thereof from the zone of back
a portion of the incoming high pressure air. ,
7. The method of separating air into its con
ward return condensation, sub-cooling the liquid
oxygen by heat exchange with said other frac
tion, pumping the liquid oxygen to a relatively
high pressure, and utilizing the cold of the liquid
stituents, oxygen and nitrogen, which comprises
compressing and cooling air at high pressure,
liquifying a portion of the compressed and cooled
air without substantial prior reduction of the
oxygen at high pressure to cool a portion of the
pressure thereof, reducing the pressure of the
incoming high pressure air.
4. The method of separating air into its con 35 remainder of the compressed and cooled air, sub
jecting the air at reduced pressure to liquefaction
stituents, oxygen and nitrogen, which comprises
and subsequent recti?cation to separate it into
compressing and cooling air at high pressure, liq
two fractions, one consisting essentially of oxy
uefying a portion thereof at such high pressure,
gen and the other consisting essentially of nitro
subjecting the remainder of the air to a reduc
tion in pressure and liquefaction in two portions, 40 gen, withdrawing oxygen in the gaseous form from
said one fraction and subjecting it to backward
one rich in oxygen and the other rich in nitro
return condensation by heat exchange, substan
gen, subsequently rectifying said portions to pro
tially solely with air lique?ed from the initially
compressed and cooled air, separately withdraw
duce separate fractions, one consisting essen
tially of oxygen and the other consisting essen
tially of nitrogen, withdrawing oxygen from said
one fraction in the gaseous phase and subjecting
it to backward return'condensation by heat ex
change with at least a part of the portion of the
ing the liquid oxygen and the uncondensed resi
due thereof from the zone of backward return
condensation, and delivering the air vaporized in
cooling the gaseous oxygen to the zone of recti
?cation for liquefaction of oxygen contained
therein.
8. The method of separating air into its con
stituents, oxygen and nitrogen, which comprises
air lique?ed at said high pressure, separately
withdrawing the liquid oxygen and the uncon
densed residue thereof from the zone of back
ward return condensation, and delivering the air
compressing and cooling air at high pressure,
liquefying a portion of the compressed and cooled
air without substantial prior reduction of the
pressure thereof, reducing the pressure of the
remainder of the compressed and cooled air, sub
jecting the air at reduced pressure to liquefac
vaporized in cooling the oxygen to the zone of
recti?cation for liquefaction of oxygen contained
therein.
5. The method of separating air into its con
stituents, oxygen and nitrogen, which comprises
compressing and cooling air at high pressure,
liquefying a portion thereof at such high pres
sure, subjecting the remainder of the air to a re
60
duction in pressure and liquefaction in two por
tions, one rich in oxygen and the other rich in
nitrogen, subsequently rectifying said portions to
produce separate fractions, one consisting essen
tially of oxygen and the other consisting essen
tially of nitrogen, withdrawing oxygen from said
one fraction in the gaseous phase and subjecting
it to backward return condensation by heat ex
change with at least a part of the portion of the
air lique?ed at said high pressure, separately ’
withdrawing the liquid oxygen and the uncon- -
densed residue thereof from the zone of back-v
ward return condensation, sub-cooling the liquid
oxygen by heat exchange with said other frac
tion, and delivering the air vaporized in cooling
tion and subsequent rectification to separate it
into two fractions, one consisting essentially of
oxygen and the other consisting essentially of
nitrogen, withdrawing oxygen in the gaseous form
from said one fraction and subjecting it to back
ward return condensation by heat exchange sub
stantially solely with air lique?ed from the in
itially compressed and cooled air, separately with
drawing the liquid/oxygen and the uncondensed
residue thereof from the zone of backward re
turn condensation, delivering the air vaporized
in cooling the gaseous oxygen to the zone of
recti?cation for liquefaction of oxygen contained
therein, and sub-cooling the liquid oxygen from
the zone of backward return condensation by heat
exchange with said other fraction. '
9. The method of separating air into its con
'7
2,409,458
stituents, oxygen and nitrogen, which comprises
compressing and cooling air at high pressure,
liquefying a portion of the compressed and
cooled air without substantial prior reduction
of the pressure thereof, reducing the pres
sure of the remainder of the compressed and
cooled air, subjecting the air at reduced pressure
air, separately withdrawing the liquid oxygen
and the uncondensed residue thereof fromthe
zone of backward return condensation, delivering
5
to liquefaction and subsequent recti?cation to
separate it into two fractions, one consisting ,es
sentially of oxygen and the other consisting es
sentially of nitrogen, Withdrawing oxygen in the
gaseous form from said one fraction and sub
jecting it to backward return condensation by
heat exchange substantially solely with air lique
?ed from the initially compressed and cooled 15
the air vaporized in cooling the gaseous oxygen to
the zone of recti?cation for liquefaction of oxy
gen contained therein, sub-cooling the liquid
oxygen from the zone of backward return con
densation by heat exchange with said other frac
tion, and pumping the liquid oxygen from the
zone of subcooling to a relatively high pressure
and utilizing the cold of the liquid oxygen at high
pressure to cool a portion of the incoming high
pressure air.
CLAUDE C. VAN NUYS.
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