U.S. patent application number 14/101628 was filed with the patent office on 2014-04-03 for cryogenic separation of synthesis gas.
This patent application is currently assigned to AIR PRODUCTS AND CHEMICALS, INC.. The applicant listed for this patent is AIR PRODUCTS AND CHEMICALS, INC.. Invention is credited to Brian Alfred McNeil, Andrew Weaver, David Graham Winter.
Application Number | 20140090416 14/101628 |
Document ID | / |
Family ID | 42237148 |
Filed Date | 2014-04-03 |
United States Patent
Application |
20140090416 |
Kind Code |
A1 |
McNeil; Brian Alfred ; et
al. |
April 3, 2014 |
Cryogenic Separation of Synthesis Gas
Abstract
A process and apparatus for separating a feed containing
hydrogen, carbon monoxide, methane, and optionally nitrogen to form
a product gas having a desired H.sub.2:CO molar ratio and
optionally a hydrogen product gas and a carbon monoxide product
gas. The feed is partially condensed to form a hydrogen-enriched
vapor fraction and a carbon monoxide-enriched liquid fraction. The
hydrogen-enriched vapor fraction and carbon monoxide-enriched
liquid fraction are combined in a regulated manner to form an
admixture, which is cryogenically separated to form the product
mixture having the desired H.sub.2:CO molar ratio.
Inventors: |
McNeil; Brian Alfred;
(Surrey, GB) ; Weaver; Andrew; (Surrey, GB)
; Winter; David Graham; (Surrey, GB) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
AIR PRODUCTS AND CHEMICALS, INC. |
Allentown |
PA |
US |
|
|
Assignee: |
AIR PRODUCTS AND CHEMICALS,
INC.
Allentown
PA
|
Family ID: |
42237148 |
Appl. No.: |
14/101628 |
Filed: |
December 10, 2013 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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12640435 |
Dec 17, 2009 |
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14101628 |
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12416439 |
Apr 1, 2009 |
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12640435 |
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Current U.S.
Class: |
62/618 |
Current CPC
Class: |
F25J 3/08 20130101; F25J
2205/30 20130101; F25J 2200/76 20130101; F25J 2270/24 20130101;
F25J 3/0261 20130101; C01B 2203/046 20130101; C01B 3/506 20130101;
C01B 2203/147 20130101; F25J 3/0233 20130101; C01B 2203/048
20130101; C01B 2203/047 20130101; F25J 2270/04 20130101; F25J
2215/02 20130101; C01B 2203/0415 20130101; F25J 2245/02 20130101;
F25J 3/0252 20130101; F25J 2200/74 20130101; F25J 3/0271 20130101;
F25J 2205/04 20130101; F25J 2270/02 20130101; F25J 3/0223 20130101;
C01B 2203/145 20130101; F25J 3/0257 20130101; C01B 2203/146
20130101; F25J 2200/94 20130101 |
Class at
Publication: |
62/618 |
International
Class: |
F25J 3/08 20060101
F25J003/08 |
Claims
1-12. (canceled)
13. An apparatus for separating a feed comprising hydrogen, carbon
monoxide, methane, and optionally nitrogen, comprising: a first
heat exchanger for partially condensing the feed to form a
partially condensed feed; a phase separator for separating the
partially condensed feed into a hydrogen-enriched vapor fraction
and a carbon monoxide-enriched liquid fraction; a means for feeding
the partially condensed feed to the phase separator from the first
heat exchanger, the means for feeding the partially condensed feed
configured so that no portion of the partially condensed feed
passes through an expander when feeding the partially condensed
feed to the phase separator from the first heat exchanger; a means
for combining a portion or all of the carbon monoxide-enriched
liquid fraction with a regulated portion of the hydrogen-enriched
vapor fraction to form a two-phase admixture, the means for
combining operatively disposed to receive the hydrogen-enriched
vapor fraction from the phase separator without any other phase
separator operatively disposed between the means for combining and
the phase separator; a means for feeding at least one of the
portion or all of the carbon monoxide-enriched liquid fraction and
at least a portion of the two-phase admixture to the first heat
exchanger; a first fractionator for cryogenically separating the at
least a portion of the two-phase admixture to form a first product
gas and a hydrogen-depleted liquid fraction; and a means for
feeding the at least a portion of the two-phase admixture to the
first fractionator.
14. The apparatus of claim 13 further comprising: a methane wash
column for scrubbing a second portion of the hydrogen-enriched
vapor fraction, or a vapor portion from phase separation thereof,
with a liquid methane wash stream to provide a hydrogen product gas
and a carbon monoxide-loaded methane liquid; and a means for
feeding the second portion of the hydrogen-enriched vapor fraction,
or a vapor portion from phase separation thereof, to the methane
wash column from the phase separator.
15. The apparatus of claim 14 further comprising: a second
fractionator for stripping hydrogen from a second portion of the
carbon monoxide-enriched liquid fraction and at least a portion of
the hydrogen-depleted liquid fraction to form a second
hydrogen-enriched vapor fraction and a hydrogen-freed liquid
fraction; a means for feeding the second portion of the carbon
monoxide-enriched liquid fraction to the second fractionator from
the phase separator; a means for feeding the at least a portion of
the hydrogen-depleted liquid fraction to the second fractionator
from the first fractionator; a carbon monoxide/methane fractionator
for separating an intermediate feed (36, 36') to form a carbon
monoxide product gas and a methane-enriched liquid fraction; and a
means for feeding at least a portion of the hydrogen-freed liquid
fraction to the carbon monoxide/methane fractionator from the
second fractionator.
16. The apparatus of claim 14 further comprising: a second
fractionator for stripping hydrogen from a second portion of the
carbon monoxide-enriched liquid fraction and at least a portion of
the hydrogen-depleted liquid fraction to form a second
hydrogen-enriched vapor fraction and a hydrogen-freed liquid
fraction; a means for feeding the second portion of the carbon
monoxide-enriched liquid fraction to the second fractionator from
the phase separator; a means for feeding the at least a portion of
the hydrogen-depleted liquid fraction to the second fractionator
from the first fractionator; a third fractionator for separating at
least a portion of the hydrogen-freed liquid fraction to form a
nitrogen-enriched vapor fraction and a nitrogen depleted liquid
fraction; a means for feeding the hydrogen-freed liquid fraction to
the third fractionator from the second fractionator; a carbon
monoxide/methane fractionator for separating at least a portion of
the nitrogen-depleted liquid fraction to form a carbon monoxide
product gas and a methane-enriched liquid fraction; and a means for
feeding the at least a portion of the nitrogen-depleted liquid
fraction to the carbon monoxide/methane fractionator from the third
fractionator.
17. The apparatus of claim 15 further comprising: a means for
feeding a portion of the methane-enriched liquid fraction to the
methane wash column from the carbon monoxide/methane
fractionator.
18. An apparatus for separating a feed comprising hydrogen, carbon
monoxide, methane, and optionally nitrogen, comprising: a first
heat exchanger for partially condensing the feed to form a
partially condensed feed; a phase separator for separating the
partially condensed feed into a hydrogen-enriched vapor fraction
and a carbon monoxide-enriched liquid fraction; a means for feeding
the partially condensed feed to the phase separator from the first
heat exchanger, the phase separator operatively disposed to receive
the partially condensed feed from the first heat exchanger via the
means for feeding the partially condensed feed to the phase
separator without any other phase separator operatively disposed
between the first heat exchanger and the phase separator; a means
for combining a portion or all of the carbon monoxide-enriched
liquid fraction with a regulated portion of the hydrogen-enriched
vapor fraction to form a two-phase admixture, the means for
combining operatively disposed to receive the hydrogen-enriched
vapor fraction from the phase separator without any other phase
separator operatively disposed between the means for combining and
the phase separator; a means for feeding at least one of the
portion or all of the carbon monoxide-enriched liquid fraction and
at least a portion of the two-phase admixture to the first heat
exchanger; a first fractionator for cryogenically separating the at
least a portion of the two-phase admixture to form a first product
gas and a hydrogen-depleted liquid fraction; and a means for
feeding the at least a portion of the two-phase admixture to the
first fractionator.
19. The apparatus of claim 18 further comprising: a methane wash
column for scrubbing a second portion of the hydrogen-enriched
vapor fraction, or a vapor portion from phase separation thereof,
with a liquid methane wash stream to provide a hydrogen product gas
and a carbon monoxide-loaded methane liquid; and a means for
feeding the second portion of the hydrogen-enriched vapor fraction,
or a vapor portion from phase separation thereof, to the methane
wash column from the phase separator.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a divisional of U.S. application Ser.
No. 12/640,435, filed Dec. 17, 2009, which is a
continuation-in-part of U.S. application Ser. No. 12/416,439, filed
Apr. 1, 2009, (abandoned) whose contents of which are hereby
incorporated by reference.
BACKGROUND
[0002] The present invention relates to the preparation of a
gaseous mixture containing a desired molar ratio of hydrogen and
carbon monoxide from a feed containing these components in a
different molar ratio. It has particular, but not exclusive,
application to the provision of synthesis gas containing hydrogen
and carbon monoxide in a molar ratio of, for example 1:1.
[0003] Synthesis gas (syngas) is a gaseous mixture consisting
essentially of hydrogen and carbon monoxide, which, depending upon
the level of purity, can contain small amounts of argon, nitrogen,
methane and other trace hydrocarbon impurities. Usually, it is
obtained by catalytic conversion or partial oxidation of coal,
coke, natural gas, or other hydrocarbon feeds. The primary uses of
syngas are in the synthesis of methanol (requiring a
hydrogen:carbon monoxide (H.sub.2:CO) molar ratio of 2:1) and in
reactions to produce oxo-alcohols (requiring a H.sub.2:CO molar
ratio of at least 1:1).
[0004] For many of these applications, it is necessary to control
the relative proportions of hydrogen and carbon monoxide.
Typically, this is achieved by cryogenically separating crude
syngas into hydrogen-rich and carbon monoxide-rich product streams
and then combining them in the appropriate ratio to produce the
required syngas composition. The level of impurities, especially
methane and other hydrocarbons, in the crude syngas usually also is
reduced during the cryogenic separation.
[0005] Industry wants to efficiently produce a purified syngas
having a desired H.sub.2:CO molar ratio at high pressure from a
cryogenic separation without additional compression.
[0006] Industry wants to reduce power requirements for compressing
syngas product streams.
[0007] Industry wants to reduce the amount and/or size of capital
equipment and associated costs for syngas production.
[0008] Industry wants to efficiently produce syngas having a
desired H.sub.2:CO molar ratio along with a hydrogen product gas
and/or a carbon monoxide product gas.
[0009] Related disclosures include: U.S. Pat. Nos. 4,217,759,
4,488,890, 4,525,187, 4,566,886, 5,351,491, 5,609,040, 5,832,747,
and 6,161,397, incorporated herein by reference in their
entirety.
BRIEF SUMMARY
[0010] The present invention relates to a process and apparatus for
separating a feed comprising hydrogen, carbon monoxide, methane,
and optionally nitrogen to form a product gas having a desired
H.sub.2:CO molar ratio. The process and apparatus may also form a
hydrogen product gas and a carbon monoxide product gas.
[0011] The process comprises: [0012] partially condensing the feed
to provide a hydrogen-enriched vapor fraction and a carbon
monoxide-enriched liquid fraction; [0013] combining at least a
portion of the carbon monoxide-enriched liquid fraction with a
regulated portion of the hydrogen-enriched vapor fraction to form a
two-phase admixture having a vapor fraction and a liquid fraction;
and [0014] cryogenically separating at least a portion of the
two-phase admixture in a first fractionator to form a first product
gas and a hydrogen-depleted liquid fraction, [0015] wherein the
first product gas has a H.sub.2:CO molar ratio between 0.5 and 2.5,
or between 0.9:1 and 1.5:1, or between 0.9:1 and 1.1:1; [0016]
wherein at least one of the liquid fraction of the two-phase
admixture and the at least a portion of the carbon
monoxide-enriched liquid fraction are partially vaporized.
[0017] The step of cryogenically separating at least a portion of
the two-phase admixture may comprise: [0018] separating the at
least a portion of the two-phase admixture in the first
fractionator to form a methane-depleted vapor fraction and the
hydrogen-depleted liquid fraction; [0019] partially condensing the
methane-depleted vapor fraction to form the first product gas and a
condensate; and [0020] introducing at least a portion of the
condensate into the first fractionator as reflux.
[0021] The first product gas may be withdrawn from the first
fractionator at a pressure of 15 to 40 MPa.
[0022] The process may further comprise: [0023] scrubbing a second
portion of the hydrogen-enriched vapor fraction, or a vapor portion
from phase separation thereof, with a liquid methane wash stream to
provide a hydrogen product gas and a carbon monoxide-loaded methane
liquid.
[0024] Alternatively or additionally, the process may further
comprise: [0025] stripping hydrogen from a second portion of the
carbon monoxide-enriched liquid fraction and at least a portion of
the hydrogen-depleted liquid fraction in a second fractionator to
form a second hydrogen-enriched vapor fraction and a hydrogen-freed
liquid fraction; and [0026] separating an intermediate feed
comprising carbon monoxide and methane in a carbon monoxide/methane
fractionator to form a carbon monoxide product gas and a
methane-enriched liquid fraction, wherein the intermediate feed is
formed from at least a portion of the hydrogen-freed liquid
fraction.
[0027] Alternatively, or additionally, the process may further
comprise: [0028] condensing a CO-containing vapor feed to provide a
CO-containing condensate; and [0029] introducing at least a portion
of the CO-containing condensate into the first fractionator as
reflux.
[0030] Alternatively, additionally, the process may further
comprise: [0031] condensing a CO-containing vapor feed to provide a
CO-containing condensate; and [0032] introducing a first portion of
the CO-containing condensate into the carbon monoxide/methane
fractionator as reflux and introducing a second portion of the
CO-containing condensate into the first fractionator as reflux.
[0033] Alternatively, or additionally, the process may further
comprise: [0034] stripping hydrogen from a second portion of the
carbon monoxide-enriched liquid fraction and at least a portion of
the hydrogen-depleted liquid fraction in a second fractionator to
form a second hydrogen-enriched vapor fraction and a hydrogen-freed
liquid fraction; [0035] separating an intermediate feed comprising
carbon monoxide and methane in a carbon monoxide/methane
fractionator to form a carbon monoxide product gas, a
methane-enriched liquid fraction, and a second methane-enriched
liquid fraction, wherein the intermediate feed is formed from at
least a portion of the hydrogen-freed liquid fraction; and [0036]
vaporizing the second methane-enriched liquid fraction by indirect
heat exchange with the feed to partially condense the feed.
[0037] Alternatively, the process may further comprise: [0038]
stripping hydrogen from a second portion of the carbon
monoxide-enriched liquid fraction and at least a portion of the
hydrogen-depleted liquid fraction in a second fractionator to form
a second hydrogen-enriched vapor fraction and a hydrogen-freed
liquid fraction; [0039] separating at least a portion of the
hydrogen-freed liquid fraction in a third fractionator to form a
nitrogen-enriched vapor fraction and a nitrogen-depleted liquid
fraction; [0040] forming an intermediate feed from at least a
portion of the nitrogen-depleted liquid fraction; and [0041]
separating the intermediate feed in a carbon monoxide/methane
fractionator to form a carbon monoxide product gas and a
methane-enriched liquid fraction.
[0042] Alternatively the process may further comprise: [0043]
stripping hydrogen from a second portion of the carbon
monoxide-enriched liquid fraction and at least a portion of the
hydrogen-depleted liquid fraction in a second fractionator to form
a second hydrogen-enriched vapor fraction and a hydrogen-freed
liquid fraction; [0044] separating at least a portion of the
hydrogen-freed liquid fraction in a third fractionator to form a
nitrogen-enriched vapor fraction and a nitrogen-depleted liquid
fraction; [0045] dividing the nitrogen-depleted liquid fraction
into a first nitrogen-depleted stream and a second
nitrogen-depleted stream; [0046] partially vaporizing the first
nitrogen-depleted stream to form a partially vaporized
nitrogen-depleted stream; and [0047] separating the partially
vaporized nitrogen-depleted stream and the second nitrogen-depleted
stream in a carbon monoxide/methane fractionator to form a carbon
monoxide product gas and a methane-enriched liquid fraction.
[0048] The methane-enriched liquid fraction may be used to form at
least a portion of the liquid methane wash stream.
[0049] The apparatus for separating a feed comprising hydrogen,
carbon monoxide, methane, and optionally nitrogen, comprises:
[0050] a first heat exchanger for partially condensing the feed to
form a partially condensed feed; [0051] a phase separator for
separating the partially condensed feed into a hydrogen-enriched
vapor fraction and a carbon monoxide-enriched liquid fraction;
[0052] a means for feeding the partially condensed feed to the
phase separator from the first heat exchanger; [0053] a means for
combining a regulated portion of the hydrogen-enriched vapor
fraction with a portion or all of the carbon monoxide-enriched
liquid fraction to form a two-phase admixture, [0054] a means for
feeding at least one of the portion or all of the carbon
monoxide-enriched liquid fraction and at least a portion of the
two-phase admixture to the first heat exchanger; [0055] the first
fractionator for cryogenically separating the at least a portion of
the two-phase admixture to form a first product gas and a
hydrogen-depleted liquid fraction; and [0056] a means for feeding
the at least a portion of the two-phase admixture to the first
fractionator.
[0057] The apparatus may further comprise: [0058] a methane wash
column for scrubbing a second portion of the hydrogen-enriched
vapor fraction, or a vapor portion from phase separation thereof,
with a liquid methane wash stream to provide a hydrogen product gas
and a carbon monoxide-loaded methane liquid; and [0059] a means for
feeding the second portion of the hydrogen-enriched vapor fraction,
or a vapor portion from phase separation thereof, to the methane
wash column from the phase separator.
[0060] The apparatus may further comprise: [0061] a second
fractionator for stripping hydrogen from a second portion of the
carbon monoxide-enriched liquid fraction and at least a portion of
the hydrogen-depleted liquid fraction to form a second
hydrogen-enriched vapor fraction and a hydrogen-freed liquid
fraction; [0062] a means for feeding the second portion of the
carbon monoxide-enriched liquid fraction to the second fractionator
from the phase separator; [0063] a means for feeding the at least a
portion of the hydrogen-depleted liquid fraction to the second
fractionator from the first fractionator; [0064] a carbon
monoxide/methane fractionator for separating an intermediate feed
to form a carbon monoxide product gas and a methane-enriched liquid
fraction; and [0065] a means for feeding at least a portion of the
hydrogen-freed liquid fraction to the carbon monoxide/methane
fractionator from the second fractionator.
[0066] Alternatively, the apparatus may further comprise: [0067] a
second fractionator for stripping hydrogen from a second portion of
the carbon monoxide-enriched liquid fraction and at least a portion
of the hydrogen-depleted liquid fraction to form a second
hydrogen-enriched vapor fraction and a hydrogen-freed liquid
fraction; [0068] a means for feeding the second portion of the
carbon monoxide-enriched liquid fraction to the second fractionator
from the phase separator; [0069] a means for feeding the at least a
portion of the hydrogen-depleted liquid fraction to the second
fractionator from the first fractionator; [0070] a third
fractionator for separating at least a portion of the
hydrogen-freed liquid fraction to form a nitrogen-enriched vapor
fraction and a nitrogen-depleted liquid fraction; [0071] a means
for feeding the hydrogen-freed liquid fraction to the third
fractionator from the second fractionator; [0072] a carbon
monoxide/methane fractionator for separating at least a portion of
the nitrogen-depleted liquid fraction to form a carbon monoxide
product gas and a methane-enriched liquid fraction; and [0073] a
means for feeding the at least a portion of the nitrogen-depleted
liquid fraction to the carbon monoxide/methane fractionator from
the third fractionator.
[0074] The apparatus may further comprise a means for feeding a
portion of the methane-enriched liquid fraction to the methane wash
column from the carbon monoxide/methane fractionator.
BRIEF DESCRIPTION OF SEVERAL VIEWS OF THE DRAWINGS
[0075] FIG. 1 illustrates a process flow diagram for producing a
product gas having a desired H.sub.2:CO molar ratio.
[0076] FIG. 2 illustrates an exemplary process flow diagram 100 for
producing a product gas having a desired H.sub.2:CO molar ratio as
well as a hydrogen product gas and a carbon monoxide product
gas.
[0077] FIG. 3 illustrates another process flow diagram for
producing a product gas having a desired H.sub.2:CO molar
ratio.
[0078] FIG. 4 illustrates another exemplary process flow diagram
200 for producing a product gas having a desired H.sub.2:CO molar
ratio as well as a hydrogen product gas and a carbon monoxide
product gas.
DETAILED DESCRIPTION
[0079] The articles "a" and "an" as used herein mean one or more
when applied to any feature in embodiments of the present invention
described in the specification and claims. The use of "a" and "an"
does not limit the meaning to a single feature unless such a limit
is specifically stated. The article "the" preceding singular or
plural nouns or noun phrases denotes a particular specified feature
or particular specified features and may have a singular or plural
connotation depending upon the context in which it is used. The
adjective "any" means one, some, or all indiscriminately of
whatever quantity.
[0080] The phrase "at least a portion" means "a portion or
all."
[0081] For the purposes of simplicity and clarity, detailed
descriptions of well-known devices, circuits, and methods are
omitted so as not to obscure the description of the present
invention with unnecessary detail.
[0082] As used herein a "fractionator" includes such devices as
distillation columns, flash drums, rectification columns, stripping
columns and the like.
[0083] The present invention will be better understood with
reference to FIGS. 1 through 4.
[0084] A process and apparatus are for producing a product gas
having a desired H.sub.2:CO molar ratio from a feed comprising
hydrogen, carbon monoxide, methane, and optionally nitrogen. The
feed may contain small amounts of other components.
[0085] With reference to FIG. 1 and FIG. 2, the feed 1 is partially
condensed in heat exchanger 101 to form partially condensed feed 3
and separated in phase separator 102 to form hydrogen-enriched
vapor fraction 4 and carbon monoxide-enriched liquid fraction 5.
The phase separator 102 is in downstream fluid flow communication
with heat exchanger 101. The phase separator 102 is connected to
heat exchanger 101 by a means for feeding the partially condensed
feed 3 to the phase separator 102 from heat exchanger 101. The
means for feeding the partially condensed feed may include any
known means for conveying a fluid, for example conduits, pipes,
tubes and the like, as well as valves and other vessels.
[0086] The term "enriched" means having a greater mole %
concentration of the indicated gas than the original stream from
which it was formed. Then, the hydrogen-enriched vapor fraction has
a greater hydrogen mole % concentration than the feed. Likewise,
the carbon monoxide-enriched liquid fraction has a greater carbon
monoxide mole % concentration than the feed.
[0087] Since the articles "a" and "an" as used herein mean one or
more when applied to any feature, more than one hydrogen-enriched
vapor fraction 4 and more than one carbon monoxide-enriched liquid
fraction 5 may be formed from feed 1.
[0088] A portion or all of the carbon monoxide-enriched liquid
fraction 5 is combined with a regulated portion of the
hydrogen-enriched vapor fraction 4 to form two-phase admixture 6
having a vapor fraction and a liquid fraction. The portion or all
of the carbon monoxide-enriched liquid fraction 5 and the regulated
portion of the hydrogen-enriched vapor fraction 4 may be combined
using any means for combining said streams, for example, pipe T
junctions, tanks, vessels or other device having at least two
inlets and at least one outlet.
[0089] At least a portion of the liquid fraction of the two-phase
admixture 6 and/or at least a portion of the carbon
monoxide-enriched liquid fraction 5 are partially vaporized in the
heat exchanger 101 to convert a portion thereof to the vapor
fraction. These streams may be fed to heat exchanger 101 by a means
for feeding said streams, for example, conduits, pipes, tubes and
the like, valves, vessels or other known means for conveying
fluids.
[0090] At least a portion of the two-phase admixture 6 is
cryogenically separated in fractionator 103 to form a
methane-depleted vapor fraction 7 and a hydrogen-depleted liquid
fraction 15. The two-phase admixture 6 is fed to fractionator 103
by a means for feeding the two-phase admixture 6, for example
conduits, pipes, tubes and the like, valves, vessels or other known
means for conveying fluids. Methane-depleted vapor fraction 7 is
partially condensed in heat exchanger 101 and the resultant stream
is separated to form the product gas 9 and a condensate 31. At
least a portion of the condensate 31 is introduced into
fractionator 103 as reflux. The benefit of using fractionator 103
is to decrease the methane concentration in the product gas 9 and
allows for higher concentrations of methane in the feed 1.
[0091] The term "depleted" means having a lesser mole %
concentration of the indicated gas than the original stream from
which it was formed. Then, the methane-depleted vapor fraction 7
has a lesser methane mole % than the two-phase admixture 6 and the
hydrogen-depleted liquid fraction 15 has a lesser hydrogen mole %
than the two-phase admixture 6.
[0092] As used in this application, the terms "cryogenic
separation," "cryogenically separating" mean that a mixture is
separated by a separation process, for example condensation,
distillation and/or fractionation, operating with a minimum
temperature below the temperature required to condense at least one
component from the mixture at operating pressure. Usually, said
minimum temperature will be below -60.degree. F. (-50.degree. C.),
preferably below -150.degree. F. (-100.degree. C.).
[0093] Non-cryogenic separation includes other forms of separation,
for example sorption and membrane separation.
[0094] At least a portion of the two-phase admixture 6 is
cryogenically separated in fractionator 103 to form a product gas 9
and a hydrogen-depleted liquid fraction 15. Product gas 9 has the
desired H.sub.2:CO molar ratio, which may be between 0.5:1 and
2.5:1 or between 0.9:1 and 1.5:1 or between 0.9:1 and 1.1:1. The
desired H.sub.2:CO molar ratio is generally different to the
H.sub.2:CO molar ratio of the feed 1. The pressure of the product
gas 9 leaving the fractionator 103 may be from 15 to 40 MPa, thus
suitable for downstream processing without further compression. An
advantage of the present process and apparatus is to provide a
product gas with a desired H.sub.2:CO molar ratio at a suitable
pressure without further compression.
[0095] The portion of the hydrogen-enriched vapor fraction 4 is
regulated (i.e. adjusted) to affect the H.sub.2:CO molar ratio of
the product gas 9. The total flow rate of the product gas 9 may be
controlled by adjusting the quantity of carbon monoxide-enriched
liquid fraction 5 and the H.sub.2:CO molar ratio may be controlled
by adjusting the quantity of hydrogen-enriched vapor fraction 4.
Flow rates may be regulated by valves or other known means. The
composition of the product gas 9 may be measured, a signal sent to
a controller where the controller provides a signal to the valve(s)
to adjust the flow rates in a prescribed manner. The flow rate of
the carbon monoxide-enriched liquid fraction 5 is increased when an
increase in the total flow rate of the product gas 9 is desired.
The flow rate of the hydrogen-enriched vapor fraction is increased
when an increase in the H.sub.2:CO molar ratio is desired. The flow
rate of the hydrogen-enriched vapor fraction is decreased when a
decrease in the H.sub.2:CO molar ratio is desired. Product gas 9
may exchange heat with other process streams as shown before being
withdrawn from the system.
[0096] Production of a hydrogen product gas and carbon monoxide
product gas in addition to the product gas having the desired
H.sub.2:CO molar ratio is described with reference to FIG. 2.
[0097] A second portion 11 of hydrogen-enriched vapor fraction 4 is
scrubbed with a liquid methane wash stream 26 in methane wash
column 104 to provide hydrogen product gas 12 and carbon
monoxide-loaded methane liquid 32. Heat of absorption is removed in
heat exchanger 111 using liquid carbon monoxide as refrigerant. The
second portion 11 of hydrogen-enriched vapor fraction 4 is fed to
methane wash column 104 by a means for feeding the second portion
11 for example, conduits, pipes, tubes and the like, valves,
vessels or other known means for conveying fluids. Hydrogen product
gas 12 may exchange heat with various process streams as shown
before being withdrawn from the system. Optionally, a small portion
of the stream withdrawn to form the hydrogen product gas 12 may be
taken off and blended to form the purge gas stream 17.
[0098] Liquid washing is a well-known unit operation or process
step where a liquid, for example methane, is used to absorb a
preferentially absorbed component from a feed stream. For example a
liquid methane wash may be used to preferentially absorb carbon
monoxide from a stream containing hydrogen and carbon monoxide so
that substantially pure hydrogen may be removed as a gaseous
product. A wash column is a device in which liquid washing
occurs.
[0099] Hydrogen is stripped from a second portion 14 of the carbon
monoxide-enriched liquid fraction 5 and hydrogen-depleted liquid
fraction 15 in fractionator 105 to form hydrogen-enriched vapor
fraction 16 and hydrogen-freed liquid fraction 18. The
hydrogen-enriched vapor fraction 16 is reduced in pressure and
mixed with other reject streams, warmed in heat exchangers and
leaves the process as purge gas stream 17. Fractionator 105 is
reboiled in part of heat exchanger 101. The hydrogen-freed liquid
fraction 18 is subcooled in heat exchanger 101, and reduced in
pressure. Fractionator 105 is in downstream fluid flow
communication of phase separator 102. Fractionator 105 is connected
to phase separator 102 by a means for feeding the second portion 14
of the carbon monoxide-enriched liquid fraction 5. Fractionator 105
is in downstream fluid flow communication of fractionator 103.
Fractionator 105 is connected to fractionator 103 by a means for
feeding hydrogen-depleted liquid fraction 15 to fractionator 105
from fractionator 103. The means for feeding the second portion 14
of the carbon monoxide-enriched liquid fraction 5 and the means for
feeding hydrogen-depleted liquid fraction 15 may include any known
means for conveying a fluid, for example conduits, pipes, tubes and
the like, as well as valves and other vessels. Carbon
monoxide-enriched liquid fraction 14 may be heated in heat
exchanger 101 prior to being introduced into fractionator 105.
[0100] As used herein, "hydrogen-freed" means containing less than
1 mole hydrogen.
[0101] At least a portion of the hydrogen-freed liquid fraction 18
may be further processed to form an intermediate feed 36, 36' which
is separated in carbon monoxide/methane fractionator 106 to form a
carbon monoxide product gas 34 and a methane-enriched liquid
fraction 35. Carbon monoxide/methane fractionator 106 is in
downstream fluid flow communication of fractionator 105. Carbon
monoxide/methane fractionator 106 is connected to fractionator 105
by a means for feeding hydrogen-freed liquid 18 to carbon
monoxide/methane fractionator 106 from fractionator 105. The means
for feeding hydrogen-freed liquid fraction 18 may include any known
means for conveying a fluid, for example conduits, pipes, tubes and
the like, as well as valves and other columns and vessels.
[0102] Optionally, in case it is desired to remove nitrogen,
hydrogen-freed liquid fraction 18 may be separated in fractionator
107 to form a nitrogen-enriched vapor fraction 40 and a
nitrogen-depleted liquid fraction 41. If used, fractionator 107 is
in downstream fluid flow communication of fractionator 105.
Fractionator 107 is connected to fractionator 105 by a means for
feeding the hydrogen-freed liquid fraction 18. The means for
feeding the hydrogen-freed liquid fraction 18 may include any known
means for conveying a fluid, for example conduits, pipes, tubes and
the like, as well as valves and vessels. A portion of
nitrogen-depleted liquid fraction 41 may be heated and introduced
into fractionator 107 as reboil.
[0103] At least a portion of nitrogen-depleted liquid fraction 41
is used to form intermediate feed 36, 36', which is introduced into
and separated in carbon monoxide/methane fractionator 106 to form
carbon monoxide product gas 34 and methane-enriched liquid fraction
35. Carbon monoxide/methane fractionator 106 is connected to
fractionator 107 by a means for feeding the intermediate feed 36,
36'. The means for feeding intermediate feed 36, 36' may include
any known means for conveying fluid, for example conduits, pipes,
tubes and the like, as well as valves and vessels.
[0104] A portion of nitrogen-depleted liquid fraction 41 may be
divided into a first nitrogen-depleted stream 21 and a second
nitrogen depleted stream 20. The first nitrogen-depleted stream 21
may be partially vaporized in heat exchanger 101 and fed to carbon
monoxide/methane fractionator 106 as part of intermediate feed 36,
36'. The partially vaporized nitrogen-depleted stream and the
second nitrogen-depleted stream 20 are separated in carbon
monoxide/methane fractionator 106 to form carbon monoxide product
gas 34 and methane-enriched liquid fraction 35.
[0105] A portion of methane-enriched liquid fraction 35 is heated
to provide vapor boil-up, which is returned to carbon
monoxide/methane fractionator 106 to provide stripping vapor. A
portion of methane-enriched liquid fraction 35 may be used to form
at least a portion of liquid methane wash stream 26. The benefit of
forming the liquid methane wash stream from the liquid bottoms of
carbon monoxide/methane fractionator 106 is that little methane
from outside the system is required and the methane is already
cold. Methane wash column 104 is in downstream fluid flow
communication of the carbon monoxide/methane fractionator 106.
Methane wash column 104 is connected to carbon monoxide/methane
fractionator 106 by a means for feeding a portion of the
methane-enriched liquid fraction 35. The means for feeding a
portion of the methane-enriched liquid fraction 35 may include any
known means for conveying fluid, for example conduits, pipes, tubes
and the like, as well as valves and vessels.
[0106] A CO-containing vapor feed 23 may be condensed to provide a
CO-containing condensate 24. At least a portion of the
CO-containing condensate 24 may be introduced into the carbon
monoxide/methane fractionator 106 as reflux.
[0107] A slight variation to the process and apparatus for
producing a product gas having a desired H.sub.2:CO molar ratio
from a feed comprising hydrogen, carbon monoxide, methane, and
optionally nitrogen is described with reference to FIG. 3 and FIG.
4. With reference to FIG. 3 and FIG. 4, the feed 1 is partially
condensed in heat exchanger 101 to form partially condensed feed 3
and separated in phase separator 102 to form hydrogen-enriched
vapor fraction 4 and carbon monoxide-enriched liquid fraction 5.
The phase separator 102 is in downstream fluid flow communication
with heat exchanger 101. The phase separator 102 is connected to
heat exchanger 101 by a means for feeding the partially condensed
feed 3 to the phase separator 102 from heat exchanger 101. The
means for feeding the partially condensed feed may include any
known means for conveying a fluid, for example conduits, pipes,
tubes and the like, as well as valves and other vessels.
[0108] A portion or all of the carbon monoxide-enriched liquid
fraction 5 is combined with a regulated portion of the
hydrogen-enriched vapor fraction 4 to form two-phase admixture 6
having a vapor fraction and a liquid fraction. The portion or all
of the carbon monoxide-enriched liquid fraction 5 and the regulated
portion of the hydrogen-enriched vapor fraction 4 may be combined
using any means for combining said streams, for example, pipe T
junctions, tanks, vessels or other device having at least two
inlets and at least one outlet.
[0109] At least a portion of the liquid fraction of the two-phase
admixture 6 and/or at least a portion of the carbon
monoxide-enriched liquid fraction 5 are partially vaporized in the
heat exchanger 101 to convert a portion thereof to the vapor
fraction. These streams may be fed to heat exchanger 101 by a means
for feeding said streams, for example, conduits, pipes, tubes and
the like, valves, vessels or other known means for conveying
fluids.
[0110] At least a portion of the two-phase admixture 6 is
cryogenically separated in fractionator 103 to form the product gas
9 and a hydrogen-depleted liquid fraction 15. The two-phase
admixture 6 is fed to fractionator 103 by a means for feeding the
two-phase admixture 6, for example conduits, pipes, tubes and the
like, valves, vessels or other known means for conveying fluids. A
CO-containing vapor feed 23 is condensed to provide a CO-containing
condensate 24. At least a portion of the CO-containing condensate
24 is introduced into fractionator 103 as reflux. The benefit of
using fractionator 103 is to decrease the methane concentration in
the product gas 9 and allows for higher concentrations of methane
in the feed 1.
[0111] At least a portion of the two-phase admixture 6 is
cryogenically separated in fractionator 103 to form a product gas 9
and a hydrogen-depleted liquid fraction 15. Product gas 9 has the
desired H.sub.2:CO molar ratio, which may be between 0.5:1 and
2.5:1 or between 0.9:1 and 1.5:1 or between 0.9:1 and 1.1:1. The
desired H.sub.2:CO molar ratio is generally different to the
H.sub.2:CO molar ratio of the feed 1. The pressure of the product
gas 9 leaving the fractionator 103 may be from 15 to 40 MPa, thus
suitable for downstream processing without further compression. An
advantage of the present process and apparatus is to provide a
product gas with a desired H.sub.2:CO molar ratio at a suitable
pressure without further compression.
[0112] The portion of the hydrogen-enriched vapor fraction 4 is
regulated (i.e. adjusted) to affect the H.sub.2:CO molar ratio of
the product gas 9. The total flow rate of the product gas 9 may be
controlled by adjusting the quantity of carbon monoxide-enriched
liquid fraction 5 and the H.sub.2:CO molar ratio may be controlled
by adjusting the quantity of hydrogen-enriched vapor fraction 4.
Flow rates may be regulated by valves or other known means. The
composition of the product gas 9 may be measured, a signal sent to
a controller where the controller provides a signal to the valve(s)
to adjust the flow rates in a prescribed manner. The flow rate of
the carbon monoxide-enriched liquid fraction 5 is increased when an
increase in the total flow rate of the product gas 9 is desired.
The flow rate of the hydrogen-enriched vapor fraction is increased
when an increase in the H.sub.2:CO molar ratio is desired. The flow
rate of the hydrogen-enriched vapor fraction is decreased when a
decrease in the H.sub.2:CO molar ratio is desired. Product gas 9
may exchange heat with other process streams as shown before being
withdrawn from the system.
[0113] Production of a hydrogen product gas and carbon monoxide
product gas in addition to the product gas having the desired
H.sub.2:CO molar ratio is described with reference to FIG. 4.
[0114] A second portion 11 of hydrogen-enriched vapor fraction 4 is
scrubbed with a liquid methane wash stream 26 in methane wash
column 104 to provide hydrogen product gas 12 and carbon
monoxide-loaded methane liquid 32. Heat of absorption is removed in
heat exchanger 111 using liquid carbon monoxide as refrigerant. The
second portion 11 of hydrogen-enriched vapor fraction 4 is fed to
methane wash column 104 by a means for feeding the second portion
11 for example, conduits, pipes, tubes and the like, valves,
vessels or other known means for conveying fluids. Hydrogen product
gas 12 may exchange heat with various process streams as shown
before being withdrawn from the system. Optionally, a small portion
of the stream withdrawn to form the hydrogen product gas 12 may be
taken off and blended to form the purge gas stream 17.
[0115] Hydrogen is stripped from a second portion 14 of the carbon
monoxide-enriched liquid fraction 5 and hydrogen-depleted liquid
fraction 15 in fractionator 105 to form hydrogen-enriched vapor
fraction 16 and hydrogen-freed liquid fraction 18. The
hydrogen-enriched vapor fraction 16 is reduced in pressure and
mixed with other reject streams, warmed in heat exchangers and
leaves the process as purge gas stream 17. Fractionator 105 is
reboiled in part of heat exchanger 101. The hydrogen-freed liquid
fraction 18 is subcooled in heat exchanger 101, and reduced in
pressure. Fractionator 105 is in downstream fluid flow
communication of phase separator 102. Fractionator 105 is connected
to phase separator 102 by a means for feeding the second portion 14
of the carbon monoxide-enriched liquid fraction 5. Fractionator 105
is in downstream fluid flow communication of fractionator 103.
Fractionator 105 is connected to fractionator 103 by a means for
feeding hydrogen-depleted liquid fraction 15 to fractionator 105
from fractionator 103. The means for feeding the second portion 14
of the carbon monoxide-enriched liquid fraction 5 and the means for
feeding hydrogen-depleted liquid fraction 15 may include any known
means for conveying a fluid, for example conduits, pipes, tubes and
the like, as well as valves and other vessels. Carbon
monoxide-enriched liquid fraction 14 may be heated in heat
exchanger 101 prior to being introduced into fractionator 105.
[0116] At least a portion of the hydrogen-freed liquid fraction 18
may be further processed to form an intermediate feed 36, 36' which
is separated in carbon monoxide/methane fractionator 106 to form a
carbon monoxide product gas 34 and a methane-enriched liquid
fraction 35. Carbon monoxide/methane fractionator 106 is in
downstream fluid flow communication of fractionator 105. Carbon
monoxide/methane fractionator 106 is connected to fractionator 105
by a means for feeding hydrogen-freed liquid 18 to carbon
monoxide/methane fractionator 106 from fractionator 105. The means
for feeding hydrogen-freed liquid fraction 18 may include any known
means for conveying a fluid, for example conduits, pipes, tubes and
the like, as well as valves and other columns and vessels.
[0117] Optionally, in case it is desired to remove nitrogen,
hydrogen-freed liquid fraction 18 may be separated in fractionator
107 to form a nitrogen-enriched vapor fraction 40 and a
nitrogen-depleted liquid fraction 41. If used, fractionator 107 is
in downstream fluid flow communication of fractionator 105.
Fractionator 107 is connected to fractionator 105 by a means for
feeding the hydrogen-freed liquid fraction 18. The means for
feeding the hydrogen-freed liquid fraction 18 may include any known
means for conveying a fluid, for example conduits, pipes, tubes and
the like, as well as valves and vessels. A portion of
nitrogen-depleted liquid fraction 41 may be heated and introduced
into fractionator 107 as reboil.
[0118] At least a portion of nitrogen-depleted liquid fraction 41
is used to form intermediate feed 36, 36', which is introduced into
and separated in carbon monoxide/methane fractionator 106 to form
carbon monoxide product gas 34 and methane-enriched liquid fraction
35. Carbon monoxide/methane fractionator 106 is connected to
fractionator 107 by a means for feeding the intermediate feed 36,
36'. The means for feeding intermediate feed 36, 36' may include
any known means for conveying fluid, for example conduits, pipes,
tubes and the like, as well as valves and vessels.
[0119] A portion of nitrogen-depleted liquid fraction 41 may be
divided into a first nitrogen-depleted stream 21 and a second
nitrogen depleted stream 20. The first nitrogen-depleted stream 21
may be partially vaporized in heat exchanger 101 and fed to carbon
monoxide/methane fractionator 106 as part of intermediate feed 36,
36'. The partially vaporized nitrogen-depleted stream and the
second nitrogen-depleted stream 20 are separated in carbon
monoxide/methane fractionator 106 to form carbon monoxide product
gas 34 and methane-enriched liquid fraction 35.
[0120] A portion of methane-enriched liquid fraction 35 is heated
to provide vapor boil-up, which is returned to carbon
monoxide/methane fractionator 106 to provide stripping vapor. A
portion of methane-enriched liquid fraction 35 may be used to form
at least a portion of liquid methane wash stream 26. The benefit of
forming the liquid methane wash stream from the liquid bottoms of
carbon monoxide/methane fractionator 106 is that little methane
from outside the system is required and the methane is already
cold. Methane wash column 104 is in downstream fluid flow
communication of the carbon monoxide/methane fractionator 106.
Methane wash column 104 is connected to carbon monoxide/methane
fractionator 106 by a means for feeding a portion of the
methane-enriched liquid fraction 35. The means for feeding a
portion of the methane-enriched liquid fraction 35 may include any
known means for conveying fluid, for example conduits, pipes, tubes
and the like, as well as valves and vessels.
[0121] A CO-containing vapor feed 23 may be condensed to provide a
CO-containing condensate 24. A first portion of the CO-containing
condensate 24 may be introduced into the carbon monoxide/methane
fractionator 106 as reflux and a second portion of the
CO-containing condensate 24 may be introduced into the first
fractionator 103 as reflux.
Example
[0122] The process shown in FIG. 2 was simulated using Aspen
Plus.RTM. 2004.1. Table 1 summarizes the mass balance for streams
referred to in the process flow diagram of the FIG. 2. For the
vapor fraction, 1 means all vapor, and 0 means all liquid.
[0123] Modeling studies have shown that there is a significant
power savings (about 20%) compared to blending hydrogen and carbon
monoxide product streams.
[0124] The process of the present invention reduces the cost and
improves the efficiency of syngas production by reducing the size
of a carbon monoxide heat pump/product compressor.
TABLE-US-00001 TABLE 1 Stream Parameter 1 2 3 4 5 6 7 H.sub.2 (mole
%) 64.97 64.97 64.97 85.79 5.55 32.75 34.94 N.sub.2 (mole %) 0.40
0.40 0.40 0.24 0.85 0.64 0.80 CO (mole %) 29.28 29.28 29.28 13.58
74.07 53.57 64.19 CH.sub.4 (mole %) 5.35 5.35 5.35 0.38 19.53 13.04
0.06 Flow rate (kgmol/h) 5522.2 5522.2 5522.2 4089.2 1433.0 1276.7
1221.4 Pressure (MPa) 3.07 3.04 2.99 2.99 2.99 2.89 2.89
Temperature (.degree. C.) 14.0 -139.7 -179.3 -179.3 -179.3 -147.2
-156.7 Vapor fraction (mole) 1.0000 1.0000 0.7403 1.0000 0.0000
0.8619 1.0000 Stream Parameter 8 9 10 11 12 13 14 H.sub.2 (mole %)
34.94 51.20 51.20 85.79 99.01 99.01 5.55 N.sub.2 (mole %) 0.80 0.69
0.69 0.24 0.03 0.03 0.85 CO (mole %) 64.19 48.09 48.09 13.58 0.00
0.00 74.07 CH.sub.4 (mole %) 0.06 0.02 0.02 0.38 0.96 0.96 19.53
Flow rate (kgmol/h) 1221.4 785.3 785.3 3656.4 3040.1 3040.1 589.0
Pressure (MPa) 2.88 2.88 2.85 2.99 2.97 2.92 0.69 Temperature
(.degree. C.) -162.8 -162.8 23.4 -179.3 -180.6 23.4 -172.0 Vapor
fraction (mole) 0.6429 1.0000 1.0000 1.0000 1.0000 1.0000 0.1779
Stream Parameter 15 16 17 18 19 20 21 H.sub.2 (mole %) 3.26 91.53
38.65 0.01 6.76 0.00 0.00 N.sub.2 (mole %) 0.57 1.41 1.08 0.51
71.70 0.40 0.34 CO (mole %) 62.32 2.51 1.62 44.12 21.54 44.16 40.79
CH.sub.4 (mole %) 33.85 4.55 58.65 55.36 0.00 55.44 58.87 Flow rate
(kgmol/h) 491.4 117.9 453.8 2801.7 4.5 1319.2 1376.6 Pressure (MPa)
0.69 0.66 0.21 0.66 0.45 0.46 0.28 Temperature (.degree. C.) -165.2
-175.5 23.4 -160.6 -180.5 -166.6 -173.1 Vapor fraction (mole)
0.2479 1.0000 1.0000 0.0000 1.0000 0.0000 0.0000 Stream Parameter
22 23 24 25 26 27 H.sub.2 (mole %) 0.00 0.00 0.00 0.00 0.00 0.00
N.sub.2 (mole %) 0.90 0.90 0.90 0.90 0.00 0.00 CO (mole %) 99.10
99.10 99.10 99.10 0.00 1.89 CH.sub.4 (mole %) 0.01 0.01 0.01 0.01
100.00 98.11 Flow rate (kgmol/h) 3110.7 1423.1 396.3 786.4 1290.7
181.4 Pressure (MPa) 0.23 2.72 2.58 2.58 3.08 0.28 Temperature
(.degree. C.) 11.1 40.0 -180.2 -180.2 -181.0 -150.3 Vapor fraction
(mole) 1.0000 1.0000 0.0000 0.0000 0.0000 0.0000 Stream Parameter
28 31 32 33 34 H.sub.2 (mole %) 0.00 5.68 3.48 0.05 0.00 N.sub.2
(mole %) 0.90 1.01 0.44 0.56 0.90 CO (mole %) 99.10 93.19 33.30
46.36 99.10 CH.sub.4 (mole %) 0.01 0.13 62.78 53.02 0.01 Flow rate
(kgmol/h) 444.6 436.1 1481.1 2962.2 1639.3 Pressure (MPa) 0.94 2.88
2.99 0.66 0.28 Temperature (.degree. C.) 40.0 -162.8 -174.2 -161.9
-181.6 Vapor fraction (mole) 1.0000 0.0000 0.0000 0.0000 1.0000
Stream Parameter 35 36 36' 40 41 H.sub.2 (mole %) 0.00 0.00 0.00
0.15 0.00 N.sub.2 (mole %) 0.00 0.46 0.34 71.16 0.54 CO (mole %)
0.00 47.42 40.79 28.70 51.80 CH.sub.4 (mole %) 100.00 52.12 58.87
0.00 47.66 Flow rate (kgmol/h) 1936.9 1420.7 1376.6 596.2 3379.6
Pressure (MPa) 0.28 0.28 0.28 0.45 0.46 Temperature (.degree. C.)
-147.6 -173.1 -162.2 -179.2 -168.4 Vapor fraction (mole) 0.0000
0.1352 0.4997 1.0000 0.0000
[0125] Although the present invention has been described as to
specific embodiments or examples, it is not limited thereto, but
may be changed or modified into any of various other forms without
departing from the scope of the invention as defined in the
accompanying claims.
* * * * *