U.S. patent application number 10/776872 was filed with the patent office on 2005-04-28 for methods and apparatuses for integration of a blast furnace and an air separation unit.
Invention is credited to Brugerolle, Jean-Renaud, Ha, Bao.
Application Number | 20050087038 10/776872 |
Document ID | / |
Family ID | 26702532 |
Filed Date | 2005-04-28 |
United States Patent
Application |
20050087038 |
Kind Code |
A1 |
Ha, Bao ; et al. |
April 28, 2005 |
Methods and apparatuses for integration of a blast furnace and an
air separation unit
Abstract
The present invention generally relates to processes and
apparatuses for the integration of a blast furnace and an air
separation plant to increase blast furnace production. The present
invention recovers energy from the air separation through the
expansion of a product stream.
Inventors: |
Ha, Bao; (San Ramon, CA)
; Brugerolle, Jean-Renaud; (Paris, FR) |
Correspondence
Address: |
Linda K. Russell
Intellectual Property Department
Air Liquide
2700 Post Oak Boulevard, Suite 1800
Houston
TX
77056
US
|
Family ID: |
26702532 |
Appl. No.: |
10/776872 |
Filed: |
February 10, 2004 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
10776872 |
Feb 10, 2004 |
|
|
|
10027482 |
Dec 19, 2001 |
|
|
|
6692549 |
|
|
|
|
60301574 |
Jun 28, 2001 |
|
|
|
Current U.S.
Class: |
75/463 |
Current CPC
Class: |
F25J 3/04139 20130101;
F25J 3/04581 20130101; C21B 9/14 20130101; F25J 3/04557 20130101;
Y10S 75/958 20130101; F25J 3/04018 20130101; C21B 9/10 20130101;
F25J 3/04606 20130101; F25J 3/04115 20130101; F25J 3/04575
20130101; F25J 3/04612 20130101 |
Class at
Publication: |
075/463 |
International
Class: |
C21B 005/00 |
Claims
We claim:
1. A process for integrating a blast furnace and an air separation
unit comprising the steps of: feeding feed air to the blast
furnace; removing a first portion of feed air to the blast furnace;
separating at least one oxygen rich stream and at least a second
stream from the first portion in the air separation unit; heating
the second stream; expanding the second stream to recover energy;
and, feeding at least a portion of the oxygen rich stream to the
blast furnace.
2. The process of claim 1 wherein the oxygen rich stream is mixed
with feed air prior to being fed to the blast furnace.
3. The process of claim 1 wherein at least a portion of the energy
recovered is utilized to drive at least one compressor associated
with the air separation unit.
4. The process of claim 1 further comprising the step of removing a
low BTU off gas from the blast furnace.
5. The process of claim 1 wherein the second stream is heated by
indirect heat exchange.
6. The process of claim 1 wherein the second stream is heated by a
combustion product from a combustion chamber.
7. The process of claim 4 wherein the second gas is heated by a
combustion product of the off gas from a combustion chamber.
8. The process of claim 1 wherein the air separation unit further
comprises at least one distillation column producing an oxygen rich
stream having an oxygen content greater than 21.0% by volume.
9. The process of claim 1 wherein the second stream is a nitrogen
rich gas.
10. The process of claim 1 wherein the feed air is at a pressure
between about three (3) bar to about ten (10) bar.
11. The process of claim 1 further comprising linking the expansion
of the second gas to at least one compressor associated with the
air separation unit.
12. The process of claim 1 further comprising mixing additional air
with the first portion.
13. A system for recovering a portion of energy associated with an
air separation unit for supplying oxygen rich gas to feed air of a
blast furnace comprising: an air separation unit fed at least
partially with a first portion of a feed air to a blast furnace
from which an oxygen rich product is removed from the air
separation unit and mixed with a remaining portion of the blast
furnace feed air and fed to the blast furnace; removing a second
gas from the air separation unit and heating the second gas; and,
expanding the second gas to recover energy.
14. The system of claim 13 wherein the second gas is heated by heat
exchange with a combustion product.
15. The system of claim 13 wherein the second gas is mixed with a
combustion product.
16. The system of claim 13 wherein an off gas of the blast furnace
is a fuel for a combustion chamber to heat the second gas.
17. The system of claim 13 further comprising mixing additional air
with the first portion.
Description
RELATED APPLICATION
[0001] The application claims priority from provisional application
No. 60/301,574 filed on Jun. 28, 2001.
FIELD OF INVENTION
[0002] Embodiments of the present invention generally relate to
processes and apparatuses for the integration of a blast furnace
and an air separation unit to increase production of the blast
furnace.
BACKGROUND OF THE INVENTION
[0003] For purposes of this patent, the following terms are
defined. As used herein, the term "air separating unit" or "air
separation unit" means and refers to a facility, plant, location or
process for separating the components of air and may include both
cryogenic and non-cryogenic facilities. As used herein, the terms
"enhance," "enhanced," and/or "enhancing," means and refers to an
act of altering and/or changing. As used herein, the term "oxygen
supply" means and refers to an oxygen supply with a determinable
oxygen content and is not limited nor excluded from a pure supply,
but rather, may be any concentration of oxygen and/or oxygen
content. As used herein, the term "oxygen rich" and "oxygen rich
stream" means and refers to a gas or gases having an oxygen content
greater than about 21.0% by volume. As used herein, the term "blast
furnace air" or "blast furnace feed gas" means and refers to feed
to a blast furnace to enable reduction of ores, blast furnace feed
gas is not limited to one feed supply and may, in some cases,
incorporate several sources of feed. As used herein, the term
"nitrogen rich" and "nitrogen rich stream" means and refers to a
gas or gases having an nitrogen content greater than about 80% by
volume.
[0004] As well, the use of a particular structure, structures, or
embodiments is not meant to be limiting. For instance, the term
"apparatus" or "apparatuses" means and includes production
facilities, plants, and the like. Further, the term "process" or
"processes" means and includes "methods," "plans," "production
plans," and the like. The term "led out," "fed," "feeding," and
"feed" means and refers to allowing out, passing out, discharging,
releasing, and/or the like.
[0005] Air separation plants are common in the art. Typical air
separation units comprise at least one column in which components
of air are separated into an oxygen rich liquid and a nitrogen rich
gas. Feed gas, such as air, rising in the column is brought into
gas-liquid contact in a countercurrent state with a reflux liquid
flowing down from above. As a result, the downward liquid flow is
gradually enriched in components whose boiling points are higher
than that of nitrogen to become an oxygen rich liquid. In the same
manner, upward rising vapor is gradually enriched in nitrogen to
become a nitrogen rich gas. The degree of separation can be
controlled by numerous factors, such as, but not limited to, the
number of trays, height of column, number of columns, point of
extraction of product, conditions of separation, and the like.
[0006] Blast furnaces are common in the art and primarily used for
extraction of metals from ores, or the removal of oxygen from a
metal oxide to produce the metal. A process of this type is
commonly referred to as smelting. There are many different
structures and types of blast furnaces available for smelting and
each one may differ for its particular use or particular metal to
produce.
[0007] There are many methods of operation of a blast furnace.
Typical methods of operation of a blast furnace entail loading the
blast furnace with a charge. The charge typically, but not in all
cases, includes a quantity of ore, coke and a flux such as
limestone. The charge is loaded into an upper portion of the blast
furnace. At the same time, a gas, usually air, is introduced into
the blast furnace. Oxygen is necessary in the feed gas for proper
functioning of the blast furnace. The oxygen allows, as the feed
gas passes through the charge, for a portion of the charge to be
oxidized to carbon dioxide or carbon monoxide. The carbon monoxide
then reduces the ore and reverts to carbon dioxide.
[0008] The use of oxygen rich gas, such as air, in a blast furnace
is desirable for at least the following reasons: (1) with the use
of an oxygen enrichment it is possible to switch to powdered
charcoal and/or other fuels and to reduce coke consumption in the
blast furnace and (2) with the use of an oxygen enrichment,
production of the blast furnace may be increased. Accordingly, as
the prior art has illustrated, various attempts have been made to
facilitate the use of oxygen enrichment. A prior art example of a
modification to a blast furnace is described in U.S. Pat. No.
5,244,489. In this patent, an oxygen plant equipped with a mixing
column can efficiently treat a portion of blast furnace air to
produce oxygen, which is injected into the blast air stream to
yield the enriched feed gas. This allows for reducing the mass flow
of oxygen-contained gas sent to the furnaces for the reduction of
iron ore. More air can therefore be added to the furnace to
increase the output of the steel production without increasing the
system pressure drop.
[0009] Other prior art integrations are disclosed in U.S. Pat. Nos.
5,268,019 and 5,295,351. These patents describe various possible
configurations for integrating an air separation unit with a gas
turbine operated with low-BTU gas produced by a blast furnace. Air
is extracted from the gas turbine to feed the air separation
process. Low-BTU gas is compressed and heat exchanged with the
extracted air before feeding the combustion chamber of the gas
turbine. In a variant, the fuel is saturated with moisture prior to
the expansion step to further increase turbine output.
[0010] Another similar patent is U.S. Pat. No. 5,317,862 . This
patent describes a similar configuration as U.S. Pat. Nos.
5,268,019 and 5,295,351. However, in this patent, the nitrogen
stream from the air separation unit is heated, saturated with
moisture and expanded to recover energy.
[0011] Other examples exist in the prior art for the treatment of a
blast furnace, but do not combine various beneficial synergies of
an air separation unit and a blast furnace. For example, another
prior art example is found in U.S. Pat. No. 5,582,036. This patent
describes the possibility of using a double-re-boiler type oxygen
plant for blast furnace operation. Another prior art patent is U.S.
Pat. No. 6,045,602. This patent describes the integration of the
air separation unit and the subsequent gas treatment system to
produce hydrogen gas to be used in the direct reduction of iron
ore.
[0012] These prior art examples are beneficial, however, further
advantages may be realized. For example, it would be advantageous
for steel making companies to be able to increase production of a
blast furnace without having to invest in new and/or high cost
facilities. Additionally, it would be advantageous to efficiently
utilize a blast furnace to maximize a return on investment and/or a
more complete utilization of a process gas. As well, it would be
advantageous to incorporate at least a portion of the
aforementioned improvements while not appreciably increasing a cost
of operating a blast furnace. Accordingly, the art field is in
search of methods and apparatuses that may achieve at least a
portion of these benefits.
SUMMARY OF THE INVENTION
[0013] Generally processes and apparatuses of the present invention
relate to the integration of an air separation unit and a blast
furnace. In embodiments of the present invention, at least a
portion of a blast furnace feed gas may be removed and separated in
an air separation unit, whereby an oxygen rich stream produced from
the air separation unit may be fed to the blast furnace feed gas to
enrich the oxygen content of the feed gas to the blast furnace,
thereby increasing production of the blast furnace. Additionally, a
second stream removed from the air separation unit may be expanded
for recovery of energy. Further embodiments utilize a portion of
the blast furnace off gas for the recovery of power.
[0014] This summary is not intended to be a limitation with respect
to the features of the invention as claimed and any examples are
merely intended as embodiments, and the scope and other objects can
be more readily observed and understood in the detailed description
and the claims that follow.
BRIEF DESCRIPTION OF THE DRAWINGS
[0015] FIG. 1 is an illustration of an embodiment of an integrated
air separation unit with a blast furnace.
[0016] FIG. 2 is an illustration of an alternate embodiment of an
integrated air separation unit with a blast furnace.
[0017] FIG. 3 is an alternate embodiment of an integrated air
separation unit with a blast furnace.
[0018] While the present invention will be described in connection
with presently preferred embodiments, it will be understood that it
is not intended to limit the invention to those embodiments. On the
contrary, it is intended to cover all alternatives, modifications,
and
DETAILED DESCRIPTION OF THE INVENTION
[0019] Generally, embodiments of the present invention integrate an
air separation unit and a blast furnace. In various embodiments of
the present invention, combinations of an air separation unit and a
blast furnace allow for increased production from the blast furnace
and energy recovery.
[0020] Various air separating units for accomplishing separation of
feed air exist in the prior art and are well known. Generally, in
air separating units, feed gas, such as air, is first decarbonated,
dried, cooled, and compressed by a compressor or other processes
well known in the art. The decarbonating, drying, and cooling of a
gas in an air separation unit is performed by equipment such as,
but not limited to adsorber unit(s), absorber unit(s), molecular
sieve(s), decarbonating-drying apparatuses, and/or the like. The
feed gas is then rectified for separation in a rectification column
to allow separation of the components of air. In the separation of
air, various examples of product gases include a nitrogen-rich gas
or liquid, a liquid rich in oxygen (also sometimes called liquid
rich or oxygen rich) at the bottom of the column, as well as other
constituents of air. For example, the air separation unit as
described in U.S. Pat. No. 4,717,410 may be used in various
embodiments of the present invention, and is incorporated herein by
reference.
[0021] Likewise, blast furnaces are common in the art, as is
illustrated in U.S. Pat. No. 5,244,489, incorporated herein by
reference. The present invention is not intended to be limited to
any particular type of blast furnace.
[0022] An illustration of an embodiment of an integrated air
separation unit with a blast furnace is shown in FIG. 1. Generally,
the present invention is composed of an air separation unit 1 and a
blast furnace 2. Blast furnace feed air stream 10 is fed to blast
furnace 2. A portion of feed air stream 10 is diverted and/or
removed as stream 3.
[0023] Stream 3 is then separated into at least an oxygen rich
product in air separation unit 1. In the embodiment illustrated in
FIG. 1, stream 3 is compressed in compressor 7 prior to air
separation. To increase the volume of air for air separation, if
necessary, stream 3 is mixed with additional air 9 and the
resulting mixture, stream 20, is compressed in at least one
compressor 7 to higher pressure as may be required for air
separation. Additional air 9 may be compressed in at least one
compressor 8 before mixing with stream 3. Other embodiments may mix
at least one additional air stream 9 with stream 3 and compress
stream 20 in at least one compressor 7 before air separation. Other
embodiments may utilize both a compression of additional air 9 in
at least one compressor 8 and a further compression of stream 20
with at least one compressor 7.
[0024] At least a portion of an oxygen rich product, or oxygen rich
stream 4, is mixed with a portion of stream 10 to form mixed stream
15 and fed, at sufficient pressure, to blast furnace 2 to improve
blast furnace performance. In other embodiments, oxygen rich stream
4 and feed air stream 10 are not mixed prior to being fed to blast
furnace 2.
[0025] Stream 10 is typically at a pressure of about three (3) bar
to about ten (10) bar. In an embodiment, stream 10 is about at a
pressure of five (5) bar. Compression through at least one
compressor 8 should compress additional air 9 to about the pressure
of gas stream 3. Typical operating pressures for gas stream 3 and
compressed additional air 9 may be about three (3) bar to about ten
(10) bar. Stream 20 may be further compressed to a pressure of up
to about twenty (20) bar for air separation. Compressed gas 11 may
then be fed to air separation unit 1.
[0026] In the embodiment disclosed in FIG. 1, a product stream 12,
such as a nitrogen product or a nitrogen rich product, is withdrawn
from air separation unit 1 and heated in a heater 5. Heater 5 may
be an indirect heat exchanger or a direct heat exchanger, as is
common in the art. Heated product stream 13 is then expanded in hot
expander 6 to allow for recovery of energy, such as energy for
compression of gas stream 20 and/or stream 9 before air separation.
In an embodiment, hot expander 6 and at least one compressor
associated with air separation unit 1 are mechanically linked. In
such a linked embodiment, as depicted in FIG. 1, expansion of
stream 13 rotates a shaft that turns compressor 7 and/or compressor
8, thereby recovering energy of expansion.
[0027] Now referring to FIG. 2, an illustration of an alternate
embodiment of an integrated air separation unit with a blast
furnace, a combustion chamber 32 is shown for heating, by direct
heat exchange, stream 31 from air separation unit 30. A fuel 34,
such as off gas 16 from blast furnace 2 (shown in FIG. 1) or other
hydrocarbon, is burned in combustion chamber 32 to heat stream 31
to produce a heated product stream 36 that is hot expanded in a hot
expander 35 to recover energy.
[0028] Oxygen containing stream 33 is fed to combustion chamber 32
for combustion with fuel 34. Stream 33 may be atmospheric air or
any oxygen containing product, such as an oxygen rich stream.
Various embodiments can include a bypass 39 to allow bypass of at
least a portion of stream 33 around chamber 32.
[0029] Now referring to FIG. 3, an illustration of an alternate
embodiment of an integrated air separation unit with a blast
furnace, a low pressure combustion chamber 40 is disclosed. In
embodiments of this type, fuel 49, such as off gas 16 of FIG. 1, is
fed at low pressure, and does not necessarily require further
compression, and combusted in chamber 40 to provide heat for heater
44. Heater 44 heats gas stream 43, by indirect heat exchange, which
is then hot expanded in an expander 45 to allow for recovery of
energy. In various embodiments, the exhaust gas of expander 45 can
be sent to a heat recovery exchanger to preheat stream 43 to
improve the fuel efficiency of the process.
[0030] The present invention also discloses a process of
integrating a blast furnace and an air separation unit. Embodiments
of processes of the present invention increase blast furnace
production. Generally, processes of the present invention comprise
the steps of feeding a gas to a blast furnace, usually air;
removing at least a first portion of the feed air before feeding to
the blast furnace; separating at least one oxygen rich gas and at
least a second stream from the first portion in at least one air
separation unit; heating the second stream; expanding the second
stream to recover energy; mixing the oxygen rich stream with the
blast furnace feed air; and, feeding the mixed feed gas to the
blast furnace. Further embodiments include the second stream being
heated by a combustion product; removing an off gas, such as a low
BTU off gas from the blast furnace, and combusting the off gas in a
combustion chamber; mixing another stream with the second stream
before expanding the second stream; and, heating the second stream
in a heat exchanger.
[0031] Although various embodiments of the present invention have
been shown and described, various other modifications may be made
to the present invention while keeping within the scope and content
of the claims of the present invention.
* * * * *