U.S. patent application number 11/132058 was filed with the patent office on 2006-11-23 for gas separation liquefaction means and processes.
Invention is credited to Leslie C. Kun.
Application Number | 20060260358 11/132058 |
Document ID | / |
Family ID | 37431991 |
Filed Date | 2006-11-23 |
United States Patent
Application |
20060260358 |
Kind Code |
A1 |
Kun; Leslie C. |
November 23, 2006 |
Gas separation liquefaction means and processes
Abstract
Single or double column cryogenic gas-separation/liquefaction
devices, where refrigeration to the device is supplied by a
cryocooler alone or by a combination of a cryocooler and by a
Joule-Thompson throttling process, where the gas condensation may
occur directly on the cold portion of the cryocooler which may be
located inside of the thermally insulated space of the distillation
column(s) are disclosed. The system is particularly useful for
medical applications, such as providing for safe and economical
high-purity oxygen for at-home use. The invention principles
include a combined column embodiment for simultaneous production of
high-purity liquid or gaseous oxygen and nitrogen. Another double
column design offers reduced temperature and pressure separation
with easy switching between oxygen and nitrogen extraction or
single component extraction. If both gaseous and liquid oxygen are
required, oxygen purity of approximately 95% can be produced with
good recovery, i.e., with nitrogen purity of approximately 91%.
Inventors: |
Kun; Leslie C.;
(Williamsville, NY) |
Correspondence
Address: |
PATRICIA M. COSTANZO;PATS PENDING
P.O. BOX 101
ELMA
NY
14059
US
|
Family ID: |
37431991 |
Appl. No.: |
11/132058 |
Filed: |
May 18, 2005 |
Current U.S.
Class: |
62/643 ; 62/51.2;
62/611; 62/912 |
Current CPC
Class: |
F25J 2290/62 20130101;
F25J 3/04975 20130101; F25J 2205/04 20130101; F25J 3/04351
20130101; F25J 3/04412 20130101; F25J 2220/40 20130101; F25J 3/044
20130101; F25J 2205/84 20130101; F25J 3/04424 20130101; F25J
2200/52 20130101; F25J 3/04242 20130101; F25J 2200/54 20130101;
F25J 3/04872 20130101; F25J 2205/02 20130101; F25J 2270/90
20130101; F25J 3/04878 20130101; F25J 3/04278 20130101; F25J
2200/50 20130101; F25J 3/04945 20130101 |
Class at
Publication: |
062/643 ;
062/912; 062/611; 062/051.2 |
International
Class: |
F25B 19/02 20060101
F25B019/02; F25J 3/00 20060101 F25J003/00; F25J 1/00 20060101
F25J001/00 |
Claims
1. A high-purity cryogenic gas-separation/liquefaction device for
the production of liquid gases, comprising: a) at least one means
for supplying a feed gas; b) at least one counterflow heat
exchanger to cool the incoming feed gas against the outgoing waste
and/or product gas; c) at least one cryogenic means having a cold
portion means for providing refrigeration for at least a process of
condensing; d) at least one condensation means for condensing at
least one enriched component of the feed gas, said condensation
means thermally connected to said cold portion means; or directly
on the cold portion means. e) at least one distillation means for
providing for distillation of the condensed at least one component
of the gas; f) at least one insulating means for thermally
insulating said device, and g) liquid collecting means to collect
and store one or two liquid products, as desired, wherein the
refrigeration to the cryogenic gas-separation/liquefaction process
may be provided by said at least one cryogenic means alone and
where gas condensation may occur at least partially directly on the
cold portion means of said at least one cryogenic means which may
be located inside of the thermally insulated space of the said at
least one distillation means.
2. The high-purity cryogenic gas-separation/liquefaction device, as
recited in claim 1, further comprising: a) wherein at least one
cryogenic means is a cryocooler, b) wherein at least one
condensation means is a condenser, or directly on the cold portion
of the cryocooler. c) wherein at least one distillation means is a
distillation column, and d) wherein at least one insulating means
is a thermally insulated container, wherein the refrigeration to
the cryogenic gas-separation/liquefaction process may be provided
by said at least one cryocooler alone and where gas condensation
may occur directly on the cold portion of said at least one
cryocooler which may be located inside or outside of the thermally
insulated space of the said at least one distillation column.
3. The high-purity cryogenic gas-separation/liquefaction device, as
recited in claim 2, further comprising: a) wherein said cryogenic
means is a cryocooler, b) wherein said condensation means is a
standard condenser thermally related to the cold portion of a
cryocooler, or where the condensing means is a cold finger of the
cryocooler. c) wherein said distillation means is a distillation
column, and d) wherein said insulating means is a Dewar flask,
wherein the refrigeration to the cryogenic
gas-separation/liquefaction process may be provided by said
cryocooler alone and where gas condensation may occur directly on
the cold portion of said cryocooler which may be located inside or
outside of the Dewar flask of said distillation column.
4. The high-purity cryogenic gas-separation/liquefaction device, as
recited in claim 1, further comprising wherein refrigeration to the
cryogenic gas-separation/liquefaction device may be provided by a
combination of said cryogenic means and a Joule-Thompson throttling
process.
5. The high-purity cryogenic gas-separation/liquefaction device, as
recited in claim 1, further comprising wherein said feed gas may
comprise ambient air or any other gas mixture of interest.
6. The high-purity cryogenic gas-separation/liquefaction device, as
recited in claim 1, further comprising wherein water and carbon
dioxide are removed from said feed gas.
7. The high-purity cryogenic gas-separation/liquefaction device, as
recited in claim 1, further comprising wherein said feed gas is
driven into said device by a fan or compressor means.
8. The high-purity cryogenic gas-separation/liquefaction device, as
recited in claim 1, further comprising wherein said feed gas passes
through a multi-pass heat exchanger means for cooling.
9. The high-purity cryogenic gas-separation/liquefaction device, as
recited in claim 1, further comprising wherein said cooled feed gas
is introduced to said at least one distillation means at an
appropriate composition point.
10. The high-purity cryogenic gas-separation/liquefaction device,
as recited in claim 1, further comprising wherein an Interior
volume of said at least one distillation means is kept at an
elevated pressure by a compressor.
11. A high-purity cryogenic gas-separation/liquefaction process for
the production of liquid gases, comprising the steps of: a)
supplying a feed gas; b) at least one counterflow heat exchanger to
cool the incoming feed gas against the outgoing waste and/or
product gas; c) providing at least one cryogenic means having a
cold portion means for providing refrigeration for at least a
process of condensing; d) condensing at least one enriched
component of the feed gas using at least one condensation means
thermally connected to said cold portion means or condensing at
least one enriched component of the feed gas directly on the cold
portion means. e) distilling said at least one component of the
condensed gas using at least one distillation means; f) insulating
said device using at least one thermally insulating means, and g)
collecting liquid in liquid collecting means to collect and store
one or two liquid products, as desired, wherein providing the
refrigeration to the cryogenic gas-separation/liquefaction process
may be by said at least one cryogenic means alone and where gas
condensation may occur at least partially directly on the cold
portion means of said at least one cryogenic means which may be
located inside or outside of the thermally insulated space of the
said at least one distillation means.
12. The high-purity cryogenic gas-separation/liquefaction process,
as recited in claim 11, further comprising wherein providing
refrigeration to the cryogenic gas-separation/liquefaction device
may be by a combination of said cryogenic means and a
Joule-Thompson throttling process.
13. The high-purity cryogenic gas-separation/liquefaction process,
as recited in claim 11, further comprising wherein said feed gas
may comprise ambient air or any other gas mixture of interest.
14. The high-purity cryogenic gas-separation/liquefaction process,
as recited in claim 11, further comprising removing water and
carbon dioxide from said feed gas.
15. The high-purity cryogenic gas-separation/liquefaction process,
as recited in claim 11, further comprising driving said feed gas
into said device by a fan or compressor means.
16. The high-purity cryogenic gas-separation/liquefaction process,
as recited in claim 11, further comprising passing said feed gas
through a multi-pass heat exchanger means for cooling.
17. The high-purity cryogenic gas-separation/liquefaction process,
as recited in claim 11, further comprising introducing said cooled
feed gas to said at least one distillation means at an appropriate
composition point.
18. The high-purity cryogenic gas-separation/liquefaction process,
as recited in claim 11, further comprising wherein an interior
volume of said at least one distillation means is kept at an
elevated pressure by a compressor.
19. The high-purity cryogenic gas-separation/liquefaction process,
as recited in claim 11, further comprising utilizing at least one
boiler to produce an enriched vapor to operate said at least one
distillation column.
20. A high-purity double column cryogenic
gas-separation/liquefaction device for the simultaneous collection
of a plurality of high-purity liquid gases, comprising: a) at least
one means for supplying a feed gas; b) at least one counterflow
heat exchanger to cool the incoming feed gas against the outgoing
waste and/or product gas; c) a plurality of cryocoolers wherein
each cryocooler has a cold portion to provide refrigeration, d) a
plurality of condensers wherein each condenser is thermally related
to the cold portion of a cryocooler, e) a plurality of distillation
columns; f) at least one insulating means for insulating said
device, and g) liquid collecting means to collect and store one or
two liquid products, as desired, wherein refrigeration to the
cryogenic gas-separation/liquefaction process may be provided by
said cryocoolers alone and where gas condensation may occur at
least partially directly on the cold portions of the cryocoolers
which may be located inside or outside of the thermally insulated
space of the distillation column.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] Not Applicable
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR
[0002] DEVELOPMENT
[0003] Not Applicable
REFERENCE TO SEQUENCE LISTING, A TABLE OR A COMPUTER PROGRAM
LISTING COMPACT DISK APPENDIX
[0004] Not Applicable
BACKGROUND
[0005] The present invention relates generally to
gas-separation/liquefaction and, more particularly, to a single and
double column high-purity cryogenic gas-separation/liquefaction
devices, where the refrigeration to the cryogenic
gas-separation/liquefaction process is supplied by either a
cryocooler alone or by a combination of a cryocooler and by a
Joule-Thompson throttling process, and where the gas condensation
may occur at least partially directly on the cold portion of the
cryocooler which may be located inside of the thermally insulated
space of the distillation column.
[0006] The background information discussed below is presented to
better illustrate the novelty and usefulness of the present
invention. This background information is not admitted prior
art.
[0007] Cryogenic separation of gas mixtures is a well-established
art. The processes used to separate the gaseous constituents of
ambient air are well-known and understood. Although all of air's
valuable components such as argon, neon, and xenon may be presently
extracted from air in high-purity concentrations, the mainstay of
the separation industry is the production of nitrogen and oxygen in
various purities in gaseous or liquid form, as demanded by the
particular application.
[0008] The first air separation plant for the commercial production
of oxygen was designed and built by Dr. Carl von Linde in 1902. The
plant had a single distillation column and refrigeration was
obtained by throttling. Due to the plant's dependence on
ineffective throttling and other inefficiencies, gaseous oxygen
production required pressures of over 30 atmospheres, or higher. In
the same year, Georges Claude improved on the Linde process by
adding an expansion engine to the process. The expansion engine,
however, proved to be an unreliable component. Therefore, in the
late 1930's P. L. Kapitsa proposed and developed expansion turbines
for the separation of oxygen that proved to be far more reliable
than the expansion engine. Moreover, the ability of the expansion
turbines to handle large volumetric flow provided for cryogenic
processing at much lower pressures, thus reducing the plant
investment cost. Since that time, many variations and improvements
have been made on these devices and their related processes.
[0009] A process for the synthesis of methane-oxygen mixtures gas
has been described whereby the feeding natural gas and (preferably
dry) compressed air into a distillation column at appropriate
locations and at appropriate temperatures, produces nitrogen and
heavier hydrocarbons as by-products. In this process, refrigeration
is provided by multiple expansion machines and an expansion
valve.
[0010] Soon after, a low temperature, single column, distillation
process, where the refrigeration is provided by a reciprocating
expansion machine and by a throttle valve both external to the
distillation column, was described.
[0011] Gas-fractionating devices that provide the reflux for the
distillation process and that have external refrigeration for
condensation where the gas stream that provides the refrigeration
and the gas stream to be separated are distinct, have been
discussed, although, the design of such devices was not
described.
[0012] A process of providing reflux in the distillation column in
a reflux condenser that is refrigerated by a conventional
Joule--Thompson throttling--work expanding, oxygen rich stream,
external to the distillation column, was also taught.
[0013] Cryogenic separation of ethylene from a gaseous mixture at
various temperature levels using refrigeration provided by an
unspecified external refrigeration system was disclosed.
[0014] A process for the recovery of nitrogen from air within a
single column, where refrigeration is provided by a turbo-expander,
Joule-Thompson throttling, has been described.
[0015] A device providing for nitrogen rejection from a natural gas
stream that utilizes a series of Joule-Thompson throttle valves to
provide the necessary cooling, instead of external refrigeration,
has also been introduced into the art. The use of a mixed
refrigerant in a single loop refrigeration system providing for at
least part of the heat duty of the reboiler is also known.
[0016] Most recently, a dephlegmator type separator where the
refrigeration is also supplied by an external supply, was
introduced.
[0017] It should be noted that even today the irreversible
throttling process and the reversible, minus the losses, adiabatic
expansion for cryogenic gas-separation/liquefaction, are still
practiced almost exclusively. Moreover, it appears that for large
tonnage capacity, cryogenic gas-separation/liquefaction plants will
be using this technology for some time to come.
[0018] This is not the case, however, in the field of small-scale
production of high-purity gases, such as therapeutic oxygen where
the immense need for low-cost, small-scale production of
high-purity breathing oxygen is currently generating interest in
developing small-scale cryogenic-based gas-separation/liquefaction
plants.
[0019] Until recently small-scale cryogenic-based
gas-separation/liquefaction plants had to rely on periodic
cryogenic liquid addition for their refrigeration needs. This type
of refrigeration, however, is quite expensive. Lately, however,
reliable cryocoolers of various designs capable of supplying
refrigeration at, or below, the liquefaction temperature of
nitrogen have been made available. These cryocoolers could be
eminently suitable for small scale air separation as they eliminate
the need for liquid nitrogen to be delivered to the
gas-separation/liquefaction facility.
[0020] Applicant is not aware of any device or method wherein at
least part of the refrigeration required to remove the heat of
condensation from the distillation column reflux is achieved by a
cryocooler wherein, in normal operation, a portion of the separated
component(s) are condensed at least partially directly on the cold
portion of the cryocooler.
SUMMARY
[0021] Accordingly, the present invention provides for means and
processes that satisfy the hereto unmet need for small scale
cryogenic air and/or other gas mixture separation where the needed
refrigeration is provided wholly, or at least partially, by a
cryocooler wherein during normal operation a portion of the
enriched or separated component condenses at least partially
directly onto the cold portion of the cryocooler.
[0022] Both single or double column high-purity cryogenic
gas-separation/liquefaction devices are embodied within the
principles of the invention where the refrigeration to the
cryogenic gas-separation/liquefaction device is supplied by either
a cryocooler alone or by a combination of a cryocooler and by a
Joule-Thompson throttling process, and where the gas condensation
may occur at least partially directly on the cold portion of the
cryocooler which may be located inside of the thermally insulated
space of the distillation column(s).
[0023] Using the embodiments described herein, gases, such as
high-purity oxygen may be separated from, for example, ambient air
in a device of the present invention, wherein that device is much
smaller than presently available gas separation/liquefaction
devices. Thus, these gas-separation/liquefaction systems made
according to the principles of the present invention are
particularly useful for medical applications, and especially for
providing for safe and economical high-purity oxygen for at-home
use.
[0024] The principles of the invention as taught herein include a
combined column embodiment for the simultaneous production of
high-purity liquid or gaseous oxygen and nitrogen. Another double
column design offers a reduced temperature and pressure separation
with an easy switch between oxygen and nitrogen extraction or
single component extraction. If both gaseous and liquid oxygen are
required, an oxygen purity of approximately 95% can be produced
with good recovery i.e., with nitrogen purity of approximately
91%.
[0025] These advances in the art and the benefits they provide are
accomplished by providing for a high-purity cryogenic
gas-separation/liquefaction device for the production of liquid
gases that comprises:
[0026] a) at least one means for supplying a feed gas;
[0027] b) at least one cryogenic means having a cold portion means
for providing refrigeration for at least a process of
condensing;
[0028] c) at least one condensation means for condensing at least
one component of the feed gas, the condensation means thermally
connected to the cold portion means;
[0029] d) at least one distillation means for providing for
distillation of the condensed at least one component of the gas,
and
[0030] e) at least one insulating means for thermally insulating
the device,
[0031] wherein the refrigeration to the cryogenic
gas-separation/liquefaction process may be provided by the at least
one cryogenic means alone and where gas condensation may occur at
least partially directly on the cold portion means of the at least
one cryogenic means which may be located inside of the thermally
insulated space of the at least one distillation means. It should
be understood that in all contemplated applications the cold
portion of the cryocooler may be equipped with extended surfaces
for enhanced heat transfer.
[0032] It is further contemplated that the high-purity cryogenic
gas-separation/liquefaction device further comprises:
[0033] a) wherein at least one cryogenic means is a cryocooler,
[0034] b) wherein at least one condensation means is a condenser,
or the cold portion of the cryocooler.
[0035] c) wherein at least one distillation means is a distillation
column, and
[0036] d) wherein at least one insulating means is a thermally
insulated container,
[0037] wherein the refrigeration to the cryogenic
gas-separation/liquefaction process may be provided by the at least
one cryocooler alone and where gas condensation may occur at least
partially directly on the cold portion of the at least one
cryocooler which may be located inside or outside of the thermally
insulated space of the at least one distillation column.
[0038] It is still further contemplated that the high-purity
cryogenic gas-separation/liquefaction device further comprises:
[0039] a) wherein the cryogenic means is a cryocooler,
[0040] b) wherein the condensation means is a condenser, or the
cold portion of the cryocooler.
[0041] c) wherein the distillation means is a distillation column,
and
[0042] d) wherein the insulating means is a Dewar flask,
[0043] wherein the refrigeration to the cryogenic
gas-separation/liquefaction process may be provided by the
cryocooler alone and where gas condensation may occur directly on
the cold portion of the cryocooler which may be located inside or
outside of the Dewar flask of the distillation column.
[0044] Additionally it is contemplated that the high-purity
cryogenic gas-separation/liquefaction device also may comprise
wherein the feed gas, which may be ambient air or any other gas
mixture of interest, may be driven into the device by a fan or
compressor means, and further wherein water and carbon dioxide may
be removed from the feed gas. The refrigeration to the cryogenic
gas-separation/liquefaction device may be provided by a combination
of the cryogenic means and a Joule-Thompson throttling process.
[0045] Moreover it is contemplated that the high-purity cryogenic
gas-separation/liquefaction device, as recited above may further
comprise wherein the feed gas passes through a multi-pass heat
exchanger means for cooling and further where the cooled feed gas
is introduced to the at least one distillation means at an
appropriate composition point. It is also contemplated that an
Interior volume of the at least one distillation means may be kept
at an elevated pressure by a compressor.
[0046] Another contemplation comprises using the gas
separation/liquefaction devices of this invention to achieve a
high-purity cryogenic gas-separation/liquefaction process for the
production of liquid gases, comprising the steps of:
[0047] a) supplying a feed gas;
[0048] b) providing at least one cryogenic means having a cold
portion means for providing refrigeration for at least a process of
condensing;
[0049] c) condensing at least one component of the feed gas using
at least one condensation means thermally connected to the cold
portion means; or directly on the cold portion means.
[0050] d) distilling the at least one component of the condensed
gas using at least one distillation means, and
[0051] e) insulating the device using at least one thermally
insulating means,
[0052] wherein providing the refrigeration to the cryogenic
gas-separation/liquefaction process may be by the at least one
cryogenic means alone and where gas condensation may occur at least
partially directly on the cold portion means of the at least one
cryogenic means which may be located inside or outside of the
thermally insulated space of the at least one distillation
means.
[0053] Furthermore, a high-purity double column cryogenic gas
separation/liquefaction device for the simultaneous collection of a
plurality of high-purity liquid gases is contemplated, wherein such
a device comprise:
[0054] a) at least one means for supplying a feed gas;
[0055] b) a plurality of cryocoolers wherein each cryocooler has a
cold portion to provide refrigeration,
[0056] c) a plurality of condensing means wherein each condenser
means is a standard condenser thermally related to the cold portion
of a cryocooler, or where the condensing means is a cold finger of
the cryocooler.
[0057] d) a plurality of distillation columns, and
[0058] at least one insulating means for insulating the device,
[0059] wherein refrigeration to the cryogenic
gas-separation/liquefaction process may be provided by the
cryocoolers alone and where gas condensation may occur at least
partially directly on the cold portions of the cryocoolers which
may be located inside or outside of the thermally insulated space
of the distillation column.
[0060] Still other benefits and advantages of this invention will
become apparent to those skilled in the art upon reading and
understanding the following detailed specification and related
drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0061] In order that these and other objects, features, and
advantages of the present invention may be more fully comprehended
and appreciated, the invention will now be described, by way of
example, with reference to specific embodiments thereof which are
illustrated in appended drawings wherein like reference characters
indicate like parts throughout the several figures. The invention
will be described and explained with additional specificity and
detail using the accompanying drawings, in which:
[0062] FIG. 1 is a schematic of a first embodiment of the present
invention.
[0063] FIG. 2 is a schematic of a second embodiment of the present
invention.
[0064] FIG. 3 is a plan view of a distillation column functionally
situated inside of a cryogenic Dewar flask.
[0065] FIG. 4 is a schematic of another embodiment of a gas
separation device, made according to the principles of the
invention described herein, where two cryocoolers are used for
cooling and condensation.
[0066] FIG. 4a is a schematic of a coil evaporator that may be used
as an alternative to a conventional condenser.
[0067] FIG. 4b is a schematic of an optional design for a combined
cooling source to reduce total energy consumption.
[0068] FIG. 4c is a schematic of a more effective heat exchange
where the condenser-evaporator is placed at the bottom section of
column B.
[0069] FIG. 4d is a schematic of an alternative heat bridge that
may be used in place of condenser 48.
[0070] FIG. 4e is a schematic of the optional use of direct
blow-through flow, in which case the condenser could be
eliminated.
[0071] FIG. 5 is a schematic, in plan view, of double column design
for the simultaneous production of high-purity oxygen and nitrogen
according to the principle of the present invention.
[0072] FIG. 6 is a schematic, in plan view, of a variation in
design of a double column gas separator device according to the
present invention.
[0073] FIG. 7 is a schematic, in plan view, of another variation in
design of a double column gas separator device according to the
present invention.
REFERENCE NUMERALS AND THE PARTS OF THE INVENTION TO WHICH THEY
REFER
[0074] 1 Conduit through which air may be driven into a gas
separation device of this invention by a fan or compressor means
located in an operative position. [0075] 2 Multi-pass heat
exchanger having a warm end (the top part of exchanger, as
illustrated) and a cold end (the bottom part of the exchanger, as
illustrated). [0076] 3 Distillation column. [0077] 4 Insulation
about distillation column 3. [0078] 5 Cryocooler (see FIGS. 1, 5,
and 7). [0079] 6 Condensing means as exemplified is the cold finger
of cryocooler 5. [0080] 7 Expansion value providing for
Joule-Thompson expansion. [0081] 8 Conduit for nitrogen-rich
stream. [0082] 9 Compressor keeping interior volume 12 of
distillation column 3 at appropriate pressure. [0083] 10 Heat
exchanger for removing heat of compression. [0084] 11 Boiler.
[0085] 12 Elevated pressure volume of distillation column 3. [0086]
13 Exit point of the gaseous product. [0087] 14 Exit point of
liquid product. [0088] 20 Phase separator. [0089] 22 Indicates, in
FIG. 2, where air is driven into a gas separation device of this
invention (equivalent to 9). [0090] 23 Heat exchanger for the
removal of the heat of compression. [0091] 24 Humidity removal
device. [0092] 25 Dew point reduction and removal of carbon dioxide
device. [0093] 26 Multi-pass heat exchanger having a warm end (the
top part of exchanger, as illustrated) and a cold end (the bottom
part of the exchanger, as illustrated). [0094] 26a Exit pathway of
gaseous nitrogen enriched stream. [0095] 26b Exit pathway of the
gaseous oxygen from vapor space above reboiler 28. [0096] 26c Exit
pathway of liquid oxygen that passed through valve V2 on its way
from the liquid pool of reboiler 28. [0097] 27 Compressed air
conduit through which gas passes to reboiler (same function as seen
in FIGS. 2, 3, and 5). [0098] 27a Point where gas stream is
separated into two parts. [0099] 27b Conduit through which one part
of stream is fed to heat exchanger 26a. [0100] 27c Conduit through
which one part of stream is fed to boiler 50. [0101] 27d Point
where the separated gas streams are rejoined. [0102] 28 Reboiler to
vaporize liquid oxygen for operating distillation column 30. [0103]
29 Expansion value providing for Joule-Thompson expansion (same
function in FIGS. 2 and 3). [0104] 30 Distillation column. [0105]
32 Tube located inside distillation column 30. [0106] 33 Annular
fitting bonded to both tube 32 and to conduit 27. [0107] 34 Filter
through which compressed air enters the lower section of the tube
32. [0108] 35 Upper annular fitting. [0109] 36 Center tube. [0110]
37 Liquid distributor. [0111] 38 Spiral guide of packing section.
[0112] 40 Indicates, in FIG. 4, compressor to drive air into a gas
separation device of this invention. [0113] 41 Dew point reduction
and removal of carbon dioxide device. [0114] 42 Multi-pass heat
exchanger having a warm end (the bottom part of exchanger, as
illustrated in FIG. 4) and a cold end (the top part of the
exchanger, as illustrated in FIG. 4). [0115] 43 Boiler for
vaporizing liquid oxygen. [0116] 44 Condensing means as exemplified
is the cold finger of cryocooler 45. [0117] 44a Condensing means as
exemplified is the cold finger of cryocooler 45a. [0118] 45 First
cryocooler. [0119] 45a Second cryocooler. [0120] 46 Collector
section of column A. [0121] 47 Filter for liquid air. [0122] 48
Condenser/evaporator. [0123] 48a Detail of condenser/evaporator.
[0124] 49 Conduit for enriched oxygen. [0125] 49A Conduit for
enriched nitrogen. [0126] 50 Boiler of distillation column A.
[0127] 51 Boiler of distillation column B. [0128] 52 Conduit
through which liquid from boiler 51 travels. [0129] 53 Conduit
through which non-condensed vapor travels. [0130] 54 Collectors of
column B. [0131] 55 Collectors from which high-purity liquid
nitrogen may be removed. [0132] 56 Conduit through which highly
enriched nitrogen vapor travels. [0133] 60 Condenser. [0134] 61
Liquid conduit. [0135] 62 Collector. [0136] 70 Liquid pump. [0137]
71 First conduit line providing flow connection between column A
and column B. [0138] 72 Second conduit line providing flow
connection between column A and column B. [0139] A First column.
[0140] B Second column. [0141] BR Heat bridge. [0142] V1 Valve to
periodically drain CO.sub.2 impurities. [0143] V2 Valve for
collection of oxygen gas containing most of the argon gas component
of feed air. [0144] V3 Valve for collection of nitrogen liquid.
[0145] V4 Valve. [0146] V5 Throttling valve. [0147] V6 Valve shown
in FIG. 5 through which enriched liquid oxygen flows from
collectors 54 of column B to enter the top of column A. [0148] V7
Throttling valve. [0149] S Coil evaporator used in place of
condenser/evaporator 48. [0150] Cross-hatching denotes separation
devices, such as trays, packing, etc.
Definitions
[0150] [0151] Cold finger, as used herein, refers to a
finger-shaped cooled and cooling protruding member. Where the
cryocooler has adequate cooling capacity, condensation can be
carried out on the cold portion of the cryocooler itself, without
employing a separate condenser. [0152] Condensation, as used
herein, refers to the conversion of a substance from its vapor or
gaseous state to its liquid or solid state usually initiated by a
reduction in temperature of the vapor. [0153] Condenser, as used
herein, refers to that part of a distillation apparatus that cools
vapor until it becomes a liquid. There are several types of
condensers. One is simply an inner tube that is cooled by an outer
jacket filled with a liquid like water, for example. The other type
has the inner tube filled with small (usually glass) beads or other
shaped small bits of material. The distillate is taken from the
top. This type of condenser in effect does thousands of tiny
condensations (they occur on each bead) and produces a much more
pure product. To achieve a similar effect with the other type, you
need to do multiple distillations. Where the cryocooler has
adequate cooling capacity, condensation can be carried out on the
cold portion of the cryocooler itself, without employing a separate
condenser. [0154] Cryocooler, as used herein, refers to any device
that can produce cryogenic temperatures with significant capacity
for useful application. The term cryocooler may denote any of the
following: Gifford-McMahon cryocoolers and any related variations,
Stirling cryocoolers of the crank or linear motor driven variety,
the many variations of the Pulse Tube cryocoolers and combinations
of these with the Stirling refrigerators, reverse Brayton Cycle
cryocoolers, Multi component Vapor Compression cryocoolers, and the
like.
[0155] Note that providing reflux in the distillation column by
condensing a portion of the at least partially separated gas(s) on
the cold part of the cryocooler would be a common characteristic
for any cryocooler. [0156] Cryogenics, as used herein, refers to
the science concerned with low-temperature phenomena. Temperatures
less than -40 degrees Celsius are usually classified as cryogenic.
[0157] Dephlegmator, as used herein, refers to a part of a
distilling apparatus in which the separation of the vapors (gases)
is effected. [0158] Dewar or Dewar flask, as used herein, refers to
a glass or metal container made like a vacuum bottle that is used
especially for storing liquefied gases. [0159] Distillation, as
used herein, refers to the process of purifying, or separating the
components of, a mixture by successive evaporation and
condensation. [0160] Joule-Thompson expansion, as used herein,
refers to the cooling that gas undergoes as it expands.
[0161] It should be understood that the drawings are not
necessarily to scale. In certain instances, details which are not
necessary for an understanding of the present invention or which
render other details difficult to perceive may have been
omitted.
DETAILED DESCRIPTION
[0162] Referring now, with more particularity, to the drawings, it
should be noted that the disclosed invention is disposed to
embodiments in various sizes, shapes, and forms. Therefore, the
embodiments described herein are provided with the understanding
that the present disclosure is intended as illustrative and is not
intended to limit the invention to the embodiments described
herein. FIG. 1 schematically illustrates one device design and a
related process of the present invention.
[0163] In the schematic shown in FIG. 1, ambient air, or any other
gas mixture of interest, from which water and carbon dioxide have
been removed, is driven into conduit 1, by a fan or compressor
operatively located proximal to the entrance of conduit 1. Conduit
1 connects to the warm end of multi-pass heat exchanger 2 (which
warm end is located at the top of heat exchanger 2, as
illustrated). Low temperature air exits from the cold end of
multi-pass heat exchanger 2 (which cold end is located at the
bottom portion of heat exchanger 2, as illustrated) and is
introduced to distillation column 3 at the appropriate composition
point.
[0164] Distillation column 3 is insulated by insulator 4.
Cryocooler 5 is operatively installed about the top of distillation
column 3, as shown. The cold portion of cryocooler 5 is thermally
connected to cold finger 6. In the embodiment illustrated, the
temperature of cold finger 6 is between about 77 K and about 88 K
(roughly between the boiling point of liquid nitrogen, about 77 K,
and the boiling point of liquid oxygen, about 90 K), or for other
gases of interest, between the boiling points of the low and high
boiling components of the other gas mixtures. The thermal design
geometry and the insulation at the insertion of cryocooler 5 into
column 3 should be carefully optimized to minimize heat input from
the ambient.
[0165] Interior volume 12 of distillation column 3 is kept at an
elevated pressure by compressor 9 which is fed a nitrogen-enriched
stream as its working fluid. The path of travel of the
nitrogen-enriched stream is indicated by reference numeral 8. The
heat of compression is removed from stream 8 by heat exchanger 10
before stream 8 enters the warm end of heat exchanger 2 where it is
cooled to an intermediate temperature between the warm and cold end
of the exchanger, as required by balancing (not shown). Stream 8
then enters boiler 11 to produce the oxygen-rich vapor that is used
to operate distillation column 3. Exiting boiler 11, stream 8 is
introduced into volume 12 of distillation column 3 where stream 8
condenses at least partially on cold finger surface 6 of cryocooler
5. The condensate then undergoes a Joule-Thompson expansion in
valve 7 and the liquid reflux is distributed to the top of the
distillation column. The nitrogen-enriched stream exits
distillation column 3 from the space between the low-pressure end
of the Joule-Thompson expansion valve 7 and the top of the packing
or trays of the distillation column (denoted by hatching) via
conduit 8 and enters the cold end of the heat exchanger 2. Heat
exchanger 2 acts as a counterflow heat exchanger to cool the
incoming feed gas against the outgoing waste and/or product gas;
this heat exchanger may be of the regenerator type. Alternatively,
high-pressure vapor space 12 at the top end of the distillation
column may be connected to the cold end of conduit 8, through which
the nitrogen-enriched stream passes via an appropriately-sized
capillary.
[0166] Oxygen-rich, gaseous product leaves the vapor space of
reboiler 11, enters the cold end of heat exchanger 2 at an
appropriate temperature point, and is discharged at room
temperature through exit 13. Liquid oxygen product is discharged
from boiler 11 at exit 14 through V2.
[0167] Although not shown, it will be readily appreciated by those
skilled in the art, all of the cold conduits and the low
temperature points of the heat exchanger 2 are kept well-insulated.
The cold parts of heat exchanger 2 also may be positioned inside
the Dewar flask that may also contain distillation column 3.
Conversely, the distillation column may be located inside of one
Dewar while the heat exchanger and the cold conduits are kept in
another Dewar.
[0168] In works by R. A. Gaggioli et al., K. D. Timmerhaus et al.,
and A. M. Arkharov et al. one, who is well-versed in the art, will
find the fundamental physics and physical chemistry required for
constructing one of the above described novel cryogenic separation
systems according to the principles taught herein and will also
find the procedures necessary for balancing the system around a
given component, such as a cryocooler.
[0169] Another contemplated embodiment for the cryogenic separation
of air using a cryocooler is illustrated schematically in FIG. 2.
Ambient air, or any other gas mixture of interest, is compressed to
a relatively low-pressure, typically, but not necessarily, less
than around 0.8 MPa, by compressor 22. The heat of compression is
removed in heat exchanger 23 and the condensed humidity is removed
in humidity exchanger 24. The cooled and dried compressed air then
enters dew point reduction device 25 (suggested types of available
dew point reduction devices are given below) to reduce the dew
point of the cooled and dried compressed air to a desired low level
and to remove CO.sub.2 to prevent plugging in the low temperature
parts of the system. The humidity and carbon dioxide removal can be
effected by any known, or yet to be known, device, such as
semi-permeable membranes, adsorption devices, or by any combination
of the known methods. After leaving device 25, the compressed,
clean air enters the warm end of heat exchanger 26 where it will be
cooled down against the cold outgoing product and waste gases. The
cooled air is then introduced through conduit 27 to reboiler 28
where liquid oxygen is vaporized and collected in the bottom of the
distillation column to enable proper functioning of the same.
Partially condensed in the reboiler 28, the compressed air
undergoes a Joule-Thompson expansion in valve 29 where the
temperature will be reduced further causing the liquid mass
fraction to increase. The liquid and gas phases will be separated
in phase separator 20, and introduced into the distillation column
30 at the appropriate composition points. Cold finer 6 of
cryocooler 5 will provide part of the liquid required for the
operation of distillation column 30. The gaseous nitrogen enriched
stream is withdrawn from the gas space at the top of the column
along pathway 26a, gaseous enriched oxygen is withdrawn from the
vapor space above reboiler 28 along pathway 26b, and liquid oxygen
from the liquid pool of the reboiler, after passing through trough
valve V2, is withdrawn through pathway 26c. The separated gases
(enriched oxygen and enriched nitrogen) will be warmed up
concurrently against incoming air in heat exchanger 26. If both
gaseous and liquid oxygen are required, an oxygen purity of
approximately 95% can be produced with good recovery i.e., with
nitrogen purity of approximately 91%.
[0170] FIG. 3 illustrates a distillation column functionally
positioned inside of insulating cryogenic Dewar flask 4, which
flask may be made of metal or glass. Compressed air enters the
device via conduit 27 (having the same function as the conduit 27
in FIG. 2) at the top of the flask, which conduit is in close
proximity to the length of distillation column 30. The compressed
air travels down conduit 27 forming a spiral in the liquid pool
affecting reboiler 28. Distillation column 30 is constructed in an
annular fashion with tube 32 located inside distillation column 30.
As illustrated in FIG. 3, the packing (denoted by hatching) is
divided into two portions. Compressed air from conduit 27 enters
tube 32 near the bottom of the distillation column. Annular fitting
33 is bonded to both tube 32 and to conduit 27 so that compressed
air enters the lower section of the tube 32 first through filter
34, which is optional, then through upper annular fitting 35 to
finally enter into center tube 36. Tube 36 ends in capillary
fitting 29 (same function as mentioned in discussion relating to
FIG. 2) and will discharge a mixture of gaseous vapor and liquid
into elevated pressure volume 12 of the distillation column. The
liquid phase will join the condensate obtained on cold finger 6 of
cryocooler 5 and will be distributed through sieve 37 to provide
the reflux. The gaseous phase will be returned downward in the
annulus formed by tube 32 and the center tube 36 to an appropriate
concentration location of the distillation column packing or trays.
Drillings or slots provided in tube 32 (not shown) will let this
gas portion join the gas phase of the distillation column at the
appropriate concentration height.
[0171] Compactness of the unit is achieved by the optional use of
spiral guide 38 of packing sections in the distillation columns. In
such a design the vapor goes upward along a spiral path as the
reflux is distributed downward through each loop by gravity and
capillary forces.
[0172] Yet another embodiment, as illustrated in FIG. 4, offers a
double column design for the simultaneous production of high-purity
oxygen and nitrogen, where enhanced performance of the system is
achieved using two cryocoolers for cooling and condensation. Here,
feed air is compressed by 40. Water vapor and carbon dioxide are
then removed from the compressed air in device 41. The cleaned and
compressed air then travels through multi-pass heat exchanger 42,
which exchanger has a warm end (the bottom part of exchanger, as
illustrated in FIG. 4) and a cold end (the top part of the
exchanger, as illustrated in FIG. 4) (these parts are similar to
parts 22, 25, and 26 of FIG. 2, respectively). The air is then
conveyed to boiler 43 where the liquid oxygen is vaporized in the
bottom section of column B. The partially condensed stream is fed
to cold finger 44 at the upper section of column A where additional
condensate will be formed. Cold finger 44 is part of the cold end
of first cryocooler 45. Alternatively, condensation may occur at
least partially directly on the cold end of cryocooler 45. The
condensed air with the remaining CO.sub.2 impurities will drip down
into the collector section 46 of column A wherefrom it may be
periodically drained through valve V1. The liquid air, after
passing through filter 47 will be introduced to the
condenser-evaporator 48 (which may be of the common type, as
illustrated in as 48A) of column B where it is partially vaporized.
The gaseous phase is fed to the appropriate concentration point of
the upper section of column B through V4 and separated in a
gas-liquid contacting device due to rectification with the
downstream liquid. The liquid stream/ vapor balance in column B is
maintained by cold finger 44a which is cold part of second
cryocooler 45a. Alternatively, condensation may occur at least
partially directly on the cold end of cryocooler. Separated oxygen
gas containing most of the argon gas component of the feed air and
nitrogen liquid may leave the column through valves V2 and V3,
respectively. Enriched oxygen and nitrogen gas flows through
conduits 49 and 49A respectively and will be utilized in heat
exchanger 42 to pre-cool the incoming air. This design allows
high-purity co-production of oxygen in gaseous and liquid form and
of nitrogen.
[0173] FIGS. 4a, 4b, 4c, 4d, and 4e show alternate designs for
selected structural parts of the invention as described in
connection with FIG. 4. FIG. 4a illustrates coil evaporator S used
in place of condenser/evaporator 48 (as illustrated in FIG. 4).
FIG. 4b illustrates the use of a combined cooling source which will
reduce the total energy consumption. More effective heat exchange
could be achieved using the alternative design illustrated in FIG.
4c where the condenser-evaporator is placed at the bottom section
of column B. Condenser 48 (as illustrated in FIG. 4) may be
replaced by heat bridge BR as depicted in FIG. 4d or completely
eliminated from the device if direct blow-through flow is utilized
per FIG. 4e. The schemes presented in 4d and 4e may necessitate
utilization of a heat bridge 43a.
[0174] FIG. 5 illustrates a double column design for the
simultaneous production of high-purity oxygen and nitrogen, using
any cooling device wherein the cold portion of the cooling device
is installed directly into the distillation column. H.sub.2O and
CO.sub.2 are first removed from compressed air as described above.
The cleaned and compressed air then enters the system through
conduit 27 and is then sent through a two part heat exchanger,
having sections 26 and 26a. At point 27a between heat exchanger
sections 26 and 26a, the air stream is split into two streams. One
stream is fed through conduit 27c to boiler 50 of distillation
column A where it is partially condensed. The second stream is fed
through conduit 27b to heat exchanger 26a where it will exchange
heat with the countercurrent flow of enriched nitrogen vapor that
travels through conduit 56 before entering boiler 51 of
distillation column B. The first and second streams then will be
rejoined at 27d and fed into column B at the appropriate
concentration point. Liquid from boiler 51, travels through conduit
52 to throttling valve V5 entering cold finger 44 at the top of
column B (cold finger 44 part of the cryocooler cooling device 45
is functionally the same as the cold finger 44a in FIG. 4). Liquid
reflux generated by valve V5 and cold finger 6 will irrigate the
packing or the feed trays, as appropriate. The non-condensed vapor
in conduit 53 will be fed to the appropriate concentration section
of column B. The liquid from collectors 54 of column B travels
through valve V6 to enter the top of column A. High-purity liquid
oxygen will be removed from the bottom of column A and high-purity
liquid nitrogen may be removed from collectors 55. Column A is
operated at near atmospheric pressure while column B is at the
pressure provided by the compressor.
[0175] FIG. 6 shows another combined column embodiment designed for
the simultaneous production of liquid or gaseous oxygen and
nitrogen. After the temperature of the compressed and purified feed
air is appropriately reduced in heat exchanger 26, the air is fed
to the mid-section of distillation column B by conduit line 27.
Distillation columns A and B, in this embodiment are combined into
one, two-par, unit where the two parts are separated by condenser
60, which is functionally positioned on the bottom section of
column A. Condensate from high-pressure distillation column B
passes through liquid line 61 and throttle valve V7 to the
mid-section of low-pressure distillation column A. Enriched
nitrogen gas is withdrawn from the top of column A trough conduit 8
and exchanges heat in heat exchanger 26 against the incoming
compressed, purified air. High-purity liquid oxygen exits at the
bottom section of column A through valve V2 and liquid nitrogen
passes through collectors 62 to exit through valve V3 located in
this example near the top of column B.
[0176] Another double column design is illustrated in FIG. 7. The
main advantage of this design is that this system provides for a
reduction of both temperature and pressure process conditions, as
well as an easy switch between the production of both oxygen and
nitrogen or single component extraction. Condenser 60 is
operatively placed at the bottom section of column A. Liquid pump
70 located on conduit line 72 provides the flow connection between
condenser 60 and distillation column B. Products are extracted in
the same manner as described above in the discussion relating to
the embodiment illustrated in FIG. 6.
[0177] The foregoing description, for purposes of explanation, uses
specific and defined nomenclature to provide a thorough
understanding of the invention. However, it will be apparent to one
skilled in the art that the specific details are not required in
order to practice the invention. Thus, the foregoing description of
the specific embodiment is presented for purposes of illustration
and description and is not intended to be exhaustive or to limit
the invention to the precise form disclosed. Those skilled in the
art will recognize that many changes may be made to the features,
to the way that some of the parts of the device may be arranged
relative to one another creating various embodiments, as well as
methods of making the embodiments of the invention described herein
without departing from the spirit and scope of the invention. Thus,
it is to be understood that the present invention is not limited to
the described exemplary methods, embodiments, features or
combinations of features but include all the variation, methods,
modifications, and combinations of features within the scope of the
appended claims. The invention is limited only by the claims.
* * * * *