U.S. patent application number 12/951248 was filed with the patent office on 2012-05-24 for system and method of managing energy utilized in a flue gas processing system.
This patent application is currently assigned to ALSTOM TECHNOLOGY LTD.. Invention is credited to Nareshkumar B. Handagama, Glen D. Jukkola, Frank M. Kluger, Rasesh R. Kotdawala, Carl H. Neuschaefer, Allen M. Pfeffer, Vikram Shabde.
Application Number | 20120125240 12/951248 |
Document ID | / |
Family ID | 45002116 |
Filed Date | 2012-05-24 |
United States Patent
Application |
20120125240 |
Kind Code |
A1 |
Handagama; Nareshkumar B. ;
et al. |
May 24, 2012 |
SYSTEM AND METHOD OF MANAGING ENERGY UTILIZED IN A FLUE GAS
PROCESSING SYSTEM
Abstract
A method is provided for managing an amount of energy utilized
by a carbon dioxide capture system. The method includes providing a
fuel and a feed stream to a combustion system. The feed stream
includes oxygen and a portion of a flue gas stream generated upon
combustion of the fuel. The method also includes subjecting the
flue gas stream to a carbon dioxide capture system to remove carbon
dioxide therefrom, measuring a concentration of oxygen present in
the feed stream, and selectively adjusting an amount of the flue
gas stream included in the feed stream based on the measured
concentration of oxygen in the feed stream. The selective
adjustment is performed such that the feed stream maintains an
oxygen concentration in a range of between about 10% to 90% by
volume and the carbon dioxide capture system operates at an energy
load between 1.4 GJ/ton of carbon dioxide and 3.0 GJ/ton of carbon
dioxide.
Inventors: |
Handagama; Nareshkumar B.;
(Knoxville, TN) ; Jukkola; Glen D.; (Glastonbury,
CT) ; Kluger; Frank M.; (Schwaebisch Gmuend, DE)
; Kotdawala; Rasesh R.; (Koxville, TN) ;
Neuschaefer; Carl H.; (Enfield, CT) ; Pfeffer; Allen
M.; (Windsor Locks, CT) ; Shabde; Vikram;
(Knoxville, TN) |
Assignee: |
ALSTOM TECHNOLOGY LTD.
Baden
CH
|
Family ID: |
45002116 |
Appl. No.: |
12/951248 |
Filed: |
November 22, 2010 |
Current U.S.
Class: |
110/206 |
Current CPC
Class: |
F25J 2240/42 20130101;
F25J 2260/80 20130101; Y02T 50/60 20130101; F23C 2202/50 20130101;
Y02E 20/322 20130101; Y02C 10/04 20130101; Y02E 20/326 20130101;
Y02T 50/677 20130101; F23L 2900/07001 20130101; F23C 2202/30
20130101; F23C 9/00 20130101; F01K 17/04 20130101; F25J 3/04533
20130101; F25J 3/04836 20130101; Y02E 20/32 20130101; F23N 3/002
20130101; F23J 2215/20 20130101; F23N 2221/12 20200101; F23C 9/003
20130101; F23J 15/02 20130101; F23N 5/003 20130101; Y02E 20/344
20130101; F23L 2900/07006 20130101; Y02E 20/328 20130101; F23N
2237/26 20200101; F23J 2217/102 20130101; F23J 2219/40 20130101;
Y02C 20/40 20200801; F23J 2215/50 20130101; F23J 15/006 20130101;
F23L 7/007 20130101; F23L 2900/07002 20130101; Y02E 20/34
20130101 |
Class at
Publication: |
110/206 |
International
Class: |
F23B 80/02 20060101
F23B080/02 |
Claims
1. A method for managing an amount of energy utilized by a carbon
dioxide capture system, the method comprising: providing a fuel and
a feed stream to a combustion system, the feed stream comprising
oxygen and including a portion of a flue gas stream generated upon
combustion of the fuel in the combustion system; subjecting the
flue gas stream to a carbon dioxide capture system to remove carbon
dioxide therefrom; measuring a concentration of oxygen present in
the feed stream; and selectively adjusting an amount of the flue
gas stream included in the feed stream based on the measured
concentration of oxygen in the feed stream such that the feed
stream maintains an oxygen concentration in a range of between
about 10% to 90% by volume and the carbon dioxide capture system
operates at an energy load between 1.4 GJ/ton of carbon dioxide and
3.0 GJ/ton of carbon dioxide.
2. A method according to claim 1, wherein the carbon dioxide
capture system operates at an energy load between 1.4 GJ/ton of
carbon dioxide and 2.5 GJ/ton of carbon dioxide.
3. A method according to claim 1, further comprising: subjecting
the flue gas stream to a desulfurization system located downstream
of the combustion system and upstream of the carbon dioxide capture
system, thereby removing sulfur oxide from the flue gas stream and
forming a treated flue gas stream.
4. A method according to claim 3, further comprising directing at
least one of a portion of the flue gas stream, a portion of the
treated flue gas stream and combinations of the portions, to the
feed stream.
5. A method according to claim 4, wherein the portion of the flue
gas stream is directed from a location upstream of the
desulfurization system, and the portion of the treated flue gas
stream is directed from a location downstream of the
desulfurization system.
6. A method according to claim 4, wherein the feed stream is
further comprised of a fresh air stream and an oxidant stream.
7. A method according to claim 6, further comprising generating the
oxidant stream in an oxygen producing unit.
8. A method according to claim 7, further comprising: measuring a
concentration of oxygen in the oxidant stream; and selectively
adjusting a feed rate of an air stream provided to the oxygen
producing unit based on the measured concentration of oxygen in the
oxidant stream.
9. A method according to claim 6, further comprising: measuring a
flow rate of the fresh air stream provided to the feed stream; and
selectively adjusting the flow rate of at least one of the portion
of the flue gas stream and the portion of the treated flue gas
stream directed to the feed stream based on the measured flow rate
of the fresh air stream provided to the feed stream.
10. A method according to claim 1, further comprising: measuring a
concentration of carbon dioxide present in the flue gas stream
exiting the combustion system; and selectively adjusting a feed
rate of the feed stream directed to the combustion system based on
the measured concentration of carbon dioxide present in the flue
gas stream such that the flue gas stream maintains a carbon dioxide
concentration in a range of between about 10% to 60% by volume.
11. A method for managing an amount of energy utilized by a carbon
dioxide capture system, the method comprising: providing a fuel and
a feed stream to a combustion system, the feed stream comprising
oxygen and including a portion of a flue gas stream generated upon
combustion of the fuel in the combustion system; subjecting the
flue gas stream to a carbon dioxide capture system to remove carbon
dioxide therefrom; measuring a concentration of carbon dioxide
present in the flue gas stream exiting the combustion system; and
selectively adjusting a feed rate of the feed stream directed to
the combustion system based on the measured concentration of carbon
dioxide present in the flue gas stream such that the flue gas
stream maintains a carbon dioxide concentration in a range of
between about 10% to 60% by volume and the carbon dioxide capture
system operates at an energy load between 1.4 GJ/ton of carbon
dioxide and 3.0 GJ/ton of carbon dioxide.
12. A method according to claim 11, wherein the carbon dioxide
capture system operates at an energy load between 1.4 GJ/ton of
carbon dioxide and 2.5 GJ/ton of carbon dioxide.
13. A method according to claim 11, further comprising: subjecting
the flue gas stream to a desulfurization system located downstream
of the combustion system and upstream of the carbon dioxide capture
system, thereby removing sulfur oxide from the flue gas stream and
forming a treated flue gas stream.
14. A method according to claim 13, further comprising directing at
least one of a portion of the treated flue gas stream from a
location downstream of the desulfurization system, a portion of the
flue gas stream from a location upstream of the desulfurization
system, and combinations of the portions to the feed stream.
15. A method according to claim 13, wherein the feed stream further
comprises an oxidant stream and a fresh air stream.
16. A method according to claim 15, further comprising: measuring a
concentration of oxygen in the oxidant stream generated by an
oxygen producing unit; and selectively adjusting a feed rate of air
provided to the oxygen producing unit based on the measured
concentration of oxygen in the oxidant stream.
17. A method according to claim 15, further comprising: measuring a
flow rate of the fresh air stream provided to the feed stream; and
selectively adjusting the flow rate of the portion of the flue gas
stream directed to the feed stream based on the measured flow rate
of the fresh air stream provided to the feed stream.
18. A method according to claim 11, further comprising: measuring a
concentration of oxygen present in the feed stream; and selectively
adjusting an amount of the flue gas stream directed to the feed
stream based on the measured concentration of oxygen in the feed
stream such that the feed stream maintains an oxygen concentration
in a range of between about 10% to 90% by volume.
19. A method for managing an amount of energy utilized by a carbon
dioxide capture system, the method comprising: providing a fuel and
a feed stream to a combustion system, the feed stream comprising
oxygen and including a portion of a flue gas stream generated upon
combustion of the fuel in the combustion system; subjecting the
flue gas stream to a carbon dioxide capture system to remove carbon
dioxide therefrom; measuring a concentration of carbon dioxide
present in the flue gas stream exiting the combustion system;
selectively adjusting a feed rate of the feed stream directed to
the combustion system based on the measured concentration of carbon
dioxide present in the flue gas stream such that the flue gas
stream maintains a carbon dioxide concentration in a range of
between about 10% to 60% by volume; measuring a concentration of
oxygen present in the feed stream; and selectively adjusting an
amount of the flue gas stream present in the feed stream based on
the measured concentration of oxygen in the feed stream such that
the feed stream maintains an oxygen concentration in a range of
between about 10% to 90% by volume and the carbon dioxide capture
system operates at an energy load between 1.4 GJ/ton of carbon
dioxide and 3.0 GJ/ton of carbon dioxide.
20. A method according to claim 19, wherein the carbon dioxide
capture system operates at an energy load between 1.4 GJ/ton of
carbon dioxide and 2.5 GJ/ton of carbon dioxide.
21. A method according to claim 19, further comprising: subjecting
the flue gas stream to a desulfurization system located downstream
of the combustion system and upstream of the carbon dioxide capture
system, thereby removing sulfur oxide from the flue gas stream and
forming a treated flue gas stream.
22. A method according to claim 21, further comprising: directing
at least one of a portion of the flue gas stream from a location
upstream of the desulfurization system, a portion of the treated
flue gas stream from a location downstream of the desulfurization
system, and combinations thereof, to the feed stream.
23. A method according to claim 21, wherein the feed stream further
comprises an oxidant stream and a fresh air stream.
24. A method according to claim 23, further comprising generating
the oxidant stream in an oxygen producing unit.
25. A method according to claim 24, further comprising: measuring a
concentration of oxygen in the oxidant stream generated by an
oxygen producing unit; and selectively adjusting a feed rate of air
provided to the oxygen producing unit based on the measured
concentration of oxygen in the oxidant stream.
26. A method according to claim 24, further comprising: measuring a
flow rate of the fresh air stream provided to the feed stream; and
selectively adjusting the flow rate of the flue gas stream directed
to the feed stream based on the measured flow rate of the fresh air
stream provided to the feed stream.
Description
BACKGROUND
[0001] 1. Field
[0002] The disclosed subject matter relates to a system and method
of managing an amount of energy utilized by a flue gas stream
processing system. More particularly, the disclosed subject matter
relates to a method of optimizing an amount of energy used in a
flue gas processing system that includes oxy-firing boiler
combustion and a carbon dioxide capture system.
[0003] 2. Description of Related Art
[0004] Combustion of fuel, particularly carbonaceous materials such
as fossil fuels and waste, results in flue gas streams that contain
impurities, such as mercury (Hg), sulfur oxides (SOx) and nitrogen
oxides (NOx), and particulates, such as fly ash, which must be
removed or reduced prior to releasing the flue gas to the
environment. In response to regulations in place in many
jurisdictions, numerous processes and apparatus have been developed
to remove or reduce the impurities and particulates in the flue
gas.
[0005] The typical method of reducing particulates, Hg, NOx, and
SOx emissions from steam generating boilers is by the use of flue
gas treatment equipment including electrostatic precipitators
(ESP), fabric filter bag houses, catalytic systems, or wet and dry
scrubbers. Additionally, carbon dioxide capture systems (also
referred to as "carbon capture systems") may be employed in a flue
gas processing system if carbon dioxide emissions are to be kept at
or below a certain level.
[0006] Flue gas treatment equipment, e.g., emission control devices
and systems, are large and expensive to purchase and operate, which
significantly increases the capital cost of the facility and
operating costs. Additionally, flue gas stream treatment equipment
typically requires a large amount of space at the plant site.
[0007] One way of reducing the costs of post combustion flue gas
stream treatment is to combine various pollutant reduction
techniques and equipment into a single operation, often referred to
as "multi-pollutant control." However, combined techniques and
equipment are not applicable or feasible in every flue gas stream
processing system. Accordingly, other processes and/or systems that
facilitate the reduction of cost or overall energy use of the flue
gas stream processing system are desired.
SUMMARY
[0008] According to aspects illustrated herein, there is provided a
method for managing an amount of energy utilized by a carbon
dioxide capture system. The method includes providing a fuel and a
feed stream to a combustion system. The feed stream includes oxygen
and a portion of a flue gas stream generated upon combustion of the
fuel in the combustion system. The method includes subjecting the
flue gas stream to a carbon dioxide capture system to remove carbon
dioxide therefrom, measuring a concentration of oxygen present in
the feed stream, and selectively adjusting an amount of the flue
gas stream included in the feed stream based on the measured
concentration of oxygen in the feed stream. The selective
adjustment is performed such that the feed stream maintains an
oxygen concentration in a range of between about 10% to 90% by
volume and the carbon dioxide capture system operates at an energy
load between 1.4 GJ/ton of carbon dioxide and 3.0 GJ/ton of carbon
dioxide.
[0009] According to an aspect illustrated herein, the method
further includes subjecting the flue gas stream to a
desulfurization system located downstream of the combustion system
and upstream of the carbon dioxide capture system. The
desulfurization system removes sulfur oxide from the flue gas
stream and forms a treated flue gas stream. The method also
includes directing at least one of a portion of the flue gas
stream, a portion of the treated flue gas stream and combinations
of the portions, to the feed stream. In one embodiment, the portion
of the flue gas stream is directed from a location upstream of the
desulfurization system, and the portion of the treated flue gas
stream is directed from a location downstream of the
desulfurization system.
[0010] In one embodiment, the feed stream is further comprised of a
fresh air stream and an oxidant stream. The method includes
generating the oxidant stream in an oxygen producing unit. The
method further includes measuring a concentration of oxygen in the
oxidant stream, and selectively adjusting a feed rate of an air
stream provided to the oxygen producing unit based on the measured
concentration of oxygen in the oxidant stream. In one embodiment,
the method includes measuring a flow rate of the fresh air stream
provided to the feed stream, and selectively adjusting the flow
rate of at least one of the portion of the flue gas stream and the
portion of the treated flue gas stream directed to the feed stream
based on the measured flow rate of the fresh air stream provided to
the feed stream. In still another embodiment, the method includes
measuring a concentration of carbon dioxide present in the flue gas
stream exiting the combustion system, and selectively adjusting a
feed rate of the feed stream directed to the combustion system
based on the measured concentration of carbon dioxide present in
the flue gas stream such that the flue gas stream maintains a
carbon dioxide concentration in a range of between about 10% to 60%
by volume.
[0011] The above described and other features are exemplified by
the following figures and detailed description.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] Referring now to the figures, which are exemplary
embodiments, and wherein the like elements are numbered alike:
[0013] FIG. 1 illustrates a flue gas stream processing system
according to one embodiment disclosed herein.
[0014] FIG. 2 illustrates a flue gas stream processing system
according to one embodiment disclosed herein.
[0015] FIG. 3 illustrates a flue gas stream processing system
according to one embodiment disclosed herein.
[0016] FIG. 4 illustrates a flue gas stream processing system
according to one embodiment disclosed herein.
[0017] FIG. 5 illustrates a flue gas stream processing system
according to one embodiment disclosed herein.
DETAILED DESCRIPTION
[0018] FIG. 1 illustrates a flue gas stream processing system 100
that includes a combustion system 120 in communication with oxygen
producing unit 130. The combustion system 120 may be any system
configured to combust a fuel 122 to produce a flue gas stream 124
at an output 121 of the combustion system 120. Examples of the
combustion system 120 include, but are not limited to, pulverized
coal (PC) combustion, oxy-firing boilers and circulating fluidized
bed combustors (CFB). In one embodiment, illustrated in FIG. 1, the
combustion system 120 is an oxy-firing boiler configured to burn
the fuel 122 provided to the combustion system 120 in the presence
of a feed stream 132 provided to the combustion system. The flue
gas stream 124 is generated upon combustion of the fuel 122 and is
provided at the output 121 of the combustion system 120.
[0019] In one embodiment, as shown in FIG. 1, the feed stream 132
is a combination of an oxidant stream 134, a fresh air stream 136
and a recycled portion 124a of the flue gas stream, which has been
subjected to treatment and/or contaminant removal, e.g., the
recycled portion 124a of a treated flue gas stream 124'. In another
embodiment, as shown in FIG. 2, the feed stream 132 includes the
oxidant stream 134, the fresh air stream 136 and a recycled portion
124b of the flue gas stream 124, which has not been treated. In a
further embodiment, as shown in FIG. 3, the feed stream 132
includes the oxidant stream 134, the fresh air stream 136, the
recycled portion 124a of the treated flue gas stream 124', and the
recycled portion 124b of the flue gas stream 124. While not
illustrated in each of FIGS. 1-3, it is contemplated that the feed
stream 132 may include one or more of the oxidant stream 134, the
fresh air stream 136, the recycled portion 124a of the treated flue
gas stream 124', and the recycled portion 124b of the untreated
flue gas stream 124. As disclosed herein, combination of the
oxidant stream 134 and the fresh air stream 136 into the feed
stream 132 assists in selectively maintaining a ratio of oxygen to
fuel for proper combustion within the combustion system 120 as well
as a feed rate of the feed stream 132 to the combustion system
120.
[0020] Referring generally to FIGS. 1-3, the oxidant stream 134 is
generated by the oxygen producing unit 130, which receives an air
stream 138. In one embodiment, the oxygen producing unit 130 is an
air separation unit (ASU). The ASU may be, for example, an ion
transport membrane (ITM), an oxygen transport membrane (OTM), or a
cryogenic air separation system, e.g., a rectification column. The
oxygen producing unit 130 is not limited in this regard, since the
oxygen producing unit may be any equipment capable of producing the
oxidant stream 134.
[0021] The oxidant stream 134 generally contains oxygen (O.sub.2),
however, other elements and/or gases may be present in the oxidant
stream as well. In one embodiment, the oxidant stream 134 is at
least 90% wt. oxygen. In another embodiment, the oxidant stream 134
is at least 95% wt. oxygen.
[0022] The oxygen producing unit 130 typically requires a
relatively large energy load to process the air stream 138 and
generate the oxidant stream 134. However, in many applications, the
amount of energy expended in generating the oxidant stream 134 is a
benefit to the overall performance of the flue gas stream
processing system 100 since a reduced volume of the flue gas stream
124 is produced by the combustion system 120 utilizing a feed
stream including oxygen as compared to systems not utilizing the
oxygen producing unit 130. For example, combining the oxidant
stream 134 (as well as the fresh air stream 136) with the feed
stream 132 and providing the combination to the combustion system
120 promotes a more complete combustion of the fuel 122 in the
combustion system 120.
[0023] In one embodiment, the fresh air stream 136 is not subjected
to any treatment prior to combination with the oxidant stream 134,
and one or more of the recycled portion 124a of the treated flue
gas stream 124' and the recycled portion 124b of the flue gas
stream 124 to form the feed stream 132. Accordingly, the fresh air
stream 136 may include a variety of elements and/or gases
including, but not limited to, oxygen, carbon dioxide, nitrogen,
water, and the like. In one embodiment, the fresh air stream 136
may be subjected to some treatment such as, for example, to remove
or minimize particulates or other contaminants, if any,
therefrom.
[0024] As shown in FIGS. 1-3, the feed stream 132 and the flue gas
stream 124 may proceed through an air preheater (APH) 126, which
facilitates an increase of temperature of the feed stream 132 by
transferring heat from the flue gas stream 124.
[0025] In one embodiment, the flue gas stream 124 may include
contaminants such as, but not limited to, sulfur oxides (SOx),
mercury (Hg), carbon dioxide (CO.sub.2), particulates, nitrous
oxide (N.sub.2O) and to a lesser extent, nitrogen oxides (NOx). The
concentration of NOx present in flue gas stream 124 is dependent
upon several factors, including, but not limited to, the nitrogen
content of the fuel 122, and the concentration of nitrogen provided
to the combustion system 120 via feed stream 132. As the percentage
of oxygen present in feed stream 132 increases, the amount of
nitrogen in the feed stream 132 provided to the combustion system
120 decreases, thereby decreasing the percentage of NOx present in
the flue gas stream 124.
[0026] Downstream of the combustion system 120 is a contaminant
control system, shown generally at 140. In one embodiment, as shown
in FIGS. 1-3, the contaminant control system 140 includes an
electrostatic precipitator (ESP) 142 and a flue gas desulfurization
(FGD) system 144. It is contemplated that the contaminant control
system 140 may include more or less devices than what is shown in
FIGS. 1-3. For example, in one embodiment, the contaminant control
system 140 may include only the flue gas desulfurization system
144. The flue gas desulfurization system 144 may either be a dry
flue gas desulfurization (DFGD) system or a wet flue gas
desulfurization (WFGD) system. While not shown in FIGS. 1-3, it is
contemplated that different devices may be included in the
contaminant control system 140, including, but not limited to, a
bag house, a venturi-type scrubber, and the like.
[0027] The flue gas stream 124 generated and outputted by the
combustion system 120 is subjected to treatment by the contaminant
control system 140. In one embodiment, the flue gas stream 124 is
subjected to treatment by the flue gas desulfurization system 144,
which facilitates the removal, or substantial elimination or
minimization, of SOx from the flue gas stream 124. After proceeding
through the contaminant control system 140, the treated flue gas
stream 124' is subjected to treatment by a carbon dioxide capture
system 150 to remove, or substantially eliminate or minimize,
carbon dioxide from the treated flue gas stream 124'. The carbon
dioxide capture system 150 may be any system capable of removing or
minimizing carbon dioxide from the treated flue gas stream 124' to
produce a carbon dioxide stream 151 and a reduced carbon dioxide
flue gas stream 152. Examples of carbon dioxide capture system 150
include, but are not limited to, systems referred to as "advanced
amine" systems, "chilled ammonia" systems such as is disclosed in
International Patent Application Publication No. WO2006/022885, as
well as gas processing units, and the like.
[0028] Still referring to FIGS. 1-3, at least a portion of the
untreated flue gas stream 124 and/or the treated flue gas stream
124' may be recycled and combined to form the feed stream 132 after
exiting the combustion system 120. The recycled portion 124a of the
treated flue gas stream 124' is directed to the feed stream 132
from a location A. As shown in FIG. 1, the location A is positioned
downstream of the flue gas desulfurization system 144. In another
embodiment, as shown in FIG. 2, the recycled portion 124b of the
flue gas stream 124 is directed to the feed stream 132 from a
location B, which is positioned upstream of the contaminant control
system 140. In yet a further embodiment, as shown in FIG. 3, the
recycled portion 124a of the treated flue gas stream 124' is
directed to the feed stream 132 from the location A and the
recycled portion 124b of the flue gas stream 124 is directed to the
feed stream 132 from the location B. As shown in FIGS. 1-3, the
recycled portions 124a and 124b may be combined with the oxidant
stream 134 and the fresh air stream 136 to form the feed stream
132. While FIGS. 1-3 illustrate at least two different locations A
and B for drawing off and recycling the treated or untreated
portions of the flue gas stream, the system 100 is not limited in
this regard as the flue gas stream may be drawn from another point
within the system 100. For example, in one embodiment, a portion of
the flue gas stream may be drawn from a location within the
contaminant control system 140 such as between the ESP 142 and the
FGD 144. It should be appreciated that locations A and B may be
varied about the flue gas processing system 100 depending on, for
example, the type or nature of the fuel 122 combusted in the
combustion system 120. For example, the flue gas stream 124 may be
recycled back to the combustion system 120 prior to treatment by
the flue gas desulfurization system 144 when the fuel 122 has a low
concentration of SO.sub.X.
[0029] The recycled portion 124a of the treated flue gas stream
124' and the recycled portion 124b of the untreated flue gas stream
124 may be selectively directed to combine with the feed stream 132
by any mechanism having the capability of doing so, including, but
not limited to, pipes, conduits, valves, and the like, as are known
in the art.
[0030] In an effort to manage an amount of energy utilized by the
flue gas stream processing system 100, and particularly the carbon
dioxide capture system 150, various parameters of the flue gas
stream processing system are monitored, measured and analyzed.
[0031] Now referring to FIG. 4, in one embodiment, a concentration
of oxygen present in the feed stream 132 is measured or sensed by,
for example, a sensor or like testing or measurement device 212,
disposed in a flow path of the feed stream 132. In one embodiment,
the measured concentration of oxygen in the feed stream 132 is
compared to a predetermined or "set-point" value programmed, stored
in or provided to an integrated flow control device 210 such as,
for example, a valve. The valve 210 selectively operates to vary a
ratio of the recycled portion 124a of the treated flue gas stream
124' provided to the feed stream 132.
[0032] The concentration of oxygen present in the feed stream 132
may be measured at any point prior to the feed stream 132 entering
the combustion system 120. In one embodiment, the concentration of
oxygen present in the feed stream 132 is measured at a location C
where the feed stream 132 includes the recycled portion 124a of the
treated flue gas 124', the oxidant stream 134 and the fresh air
stream 136. However, it is contemplated that the measurement of
oxygen concentration in the feed stream 132 may occur at another
location, e.g., prior to the combination of one or more of the
recycled portions 124a, 124b of the flue gas stream, the oxidant
stream 134, and the fresh air stream 136 with the feed stream
132.
[0033] As noted above, in one embodiment, the measured oxygen
concentration in the feed stream 132 is compared to a predetermined
set-point value. The set-point value may be determined by
parameters of the flue gas stream processing system 100, which
include, but are not limited to, the amount of contaminants, e.g.,
NOx, SOx, CO.sub.2, and the like, present in the flue gas stream
124. For example, the predetermined set-point value may be based on
an oxygen concentration. In one embodiment, the set-point value is
an oxygen concentration having a value in a range of between about
10% to about 90% by volume. In one embodiment, the set-point is
calculated by a controller 260. In one embodiment, the controller
260 receives the measured oxygen concentration in the feed stream
132 from the sensor 212 and other streams (e.g., the flue gas
stream 124, and the oxidant stream 134) at one or more inputs,
shown generally at 262. In one embodiment, the controller 260
receives oxygen concentration measurements from various points of
the flow path of the feed stream 132 at the inputs 262.
[0034] When the measured concentration of oxygen present in the
feed stream 132 is not equal to the set-point value, the recycled
portions 124a, 124b of the flue gas stream directed to the feed
stream 132 may be adjusted such that the feed stream 132 maintains
an oxygen concentration in a predetermined range, for example, in a
range of between about 10% to about 90% by volume based on the
total volume of the feed stream 132. Maintenance of the oxygen
concentration in the feed stream 132 in a range of between about
10% to about 90% by volume allows the carbon dioxide capture system
150 to operate at an energy load of, for example, below about 3.0
gigajoule per ton of carbon dioxide (GJ/ton of carbon dioxide). For
example, the energy load may be between 1.4 GJ/ton of carbon
dioxide and 3.0 GJ/ton of carbon dioxide. In another example, the
energy load may be between 1.4 GJ/ton of carbon dioxide and 2.5
GJ/ton of carbon dioxide.
[0035] In another embodiment, maintenance of the oxygen
concentration in the feed stream 132 in a range of between about
40% to about 60% allows the carbon dioxide capture system 150 to
operate at an energy load of, for example, below about 3.0 GJ/ton
of carbon dioxide. For example, the energy load may be between 1.4
GJ/ton of carbon dioxide and 3.0 GJ/ton of carbon dioxide. In
another example, the energy load may be between 1.4 GJ/ton of
carbon dioxide and 2.5 GJ/ton of carbon dioxide.
[0036] In a further embodiment, maintenance of the oxygen
concentration in the feed stream in a range of between about 40%
and about 60% by volume, based on the total volume of the feed
stream 132, allows the carbon dioxide capture stream 150 to operate
at an energy load of, for example, between about 2.1 to about 2.9
GJ/ton of carbon dioxide.
[0037] As shown in FIG. 4, adjustment of the recycled portion 124a
of the treated flue gas stream 124' directed to the feed stream 132
is performed at the valve 210 that is selectively operated based on
a set-point programmed, stored or provided to the valve 210 and/or
in response to signals S received from the controller 260.
Accordingly, when an amount of the recycled flue gas stream 124
directed to the feed stream 132 is to be increased in order to
decrease the concentration of oxygen present in the feed stream
132, the valve 210 operates to allow a greater amount of the
recycled portion 124a of the flue gas stream 124' to flow to the
feed stream 132.
[0038] In one embodiment, a flow of the fresh air stream 136 is
sensed or measured at, for example, a location D, by, for example,
a sensor or like test or measurement device 222, and compared to a
set point value stored or provided to the controller 260 by, for
example, an operator (indicated by arrow O) of the flue gas stream
processing system 100. In one embodiment, the set point value is
based on, for example, an electrical demand (e.g., load) of the
combustion system 120 and is either pre-programmed, or is entered
by the operator during operation of the processing system 100. For
example, as the electrical demand of the combustion system 120
decreases, the concentration of carbon dioxide in the feed stream
132 may be higher than what was present when the combustion system
operated at the previous electrical demand. In one embodiment, when
it is desired to increase the carbon dioxide concentration in the
feed stream 132, the amount of fresh air 136 provided to the feed
stream 132 is reduced. As shown in FIG. 4, the flow of the fresh
air stream 136 is adjusted by selectively operating a valve 220. In
one embodiment, the valve 220 is selectively adjusted in response
to one of the signals S from the controller 260. It should be
appreciated that as the flow of the fresh air stream 136 is
adjusted, the flow of the feed stream 132 to the combustion system
120 may be adjusted.
[0039] In one embodiment, as the flow of the fresh air stream 136
is adjusted by selective operation of the valve 220, a signal 51 is
provided (e.g., cascaded) to the valve 210. Upon receipt of the
signal 51, the valve 210 may selective operate to adjust the flow
of the portion 124a of the recycled treated flue gas stream 124' to
the feed stream 132. As such, the portion 124a of the recycled flue
gas stream 124' directed to the feed stream 132 may be adjusted
(increased or decreased) or otherwise controlled based on the flow
rate of the fresh air stream 136 provided to the feed stream 132.
In one embodiment, a calculation block 230 receives the signal S1.
The calculation block 230 may be implemented in a variety of ways,
including, but not limited to, a function capable of changing a
time interval (e.g., selective delay) for providing the signal S1
(multiplexed at 232 with signal S) to the valve 210. In one
embodiment, the time interval may be equal to an estimated or
measured time required for an air stream to travel from the
combustion system 120 to the carbon dioxide capture system 150.
[0040] In one embodiment, the concentration of oxygen present in
the oxidant stream 134 (e.g., purity of the oxidant stream) may be
sensed or measured at, for example, a location E by, for example, a
sensor or like testing or measurement device 242, and selectively
adjusted (increased or decreased). As shown in FIG. 4, in one
embodiment, the concentration measurement is provided to the
controller 260 to compare, calculate and/or to control adjustment
of the concentration of oxygen present in the oxidant stream 134.
In one embodiment, the controller 260 compares the measured oxygen
concentration to an oxygen flow rate set-point value stored in or
provided to the controller 260. The oxygen concentration value
stored or provided to the controller 260 determines whether the
amount of the air stream 138 provided to the oxygen producing unit
130 (e.g., the feed rate) should be selectively adjusted (e.g.,
increased or decreased) to vary the oxygen concentration in the
oxidant stream 134. For example, to increase or decrease the feed
rate of the air stream 138 provided to the air separation unit 130,
the controller 260 provides the signal S to a valve 240. In
response, the valve 240 operates to selectively adjust the feed
rate of the air stream 138 provided to the oxygen producing unit
130. In one example, if the load of the combustion system 120 is
reduced, the demand for oxygen in the feed stream 132 is reduced
and, accordingly, the feed rate of the air stream 138 to the air
separation unit 130 is reduced.
[0041] In one embodiment, the concentration of carbon dioxide
present in the flue gas stream 124 may be measured or sensed at,
for example, a location F, by, for example, any device capable of
taking such a measurement, including, but not limited to a carbon
dioxide analyzer 250. While FIG. 4 illustrates location F at a
position upstream of the contaminant control system 140, it is
contemplated that location F may be positioned downstream of the
contaminant control system or within the contaminant control
system, for example, between the electrostatic precipitator 142 and
the flue gas desulfurization system 144. In one embodiment, the
measured concentration of carbon dioxide present in the flue gas
stream 124 is provided to the controller 260. The controller 260
compares the concentration of carbon dioxide present in the flue
gas stream 124 to a predetermined set-point. When the concentration
does not, for example, match or fall within a predetermined range
of the set point valve, the controller 260 operates to adjust the
concentration. In one embodiment, the controller 260 adjusts
(increases or decreases) the concentration of carbon dioxide
present in the flue gas stream 124 by, for example, adjusting an
amount (e.g., feed rate) of the feed stream 132 directed to the
combustion system 120 such that the flue gas stream 124
subsequently output maintains a carbon dioxide concentration in a
range of between about 10% to 60% by volume. In another embodiment,
the feed rate of the feed stream 132 provided to the combustion
system 120 is adjusted such that the flue gas stream 124 maintains
a carbon dioxide concentration in a range of between about 12% to
46% by volume. In a further embodiment, the feed rate of the feed
stream 132 provided to the combustion system 120 is adjusted such
that the flue gas stream 124 maintains a carbon dioxide
concentration in a range of between about 30% to 50% by volume.
[0042] It should be appreciated that while it is described above to
maintain a predetermined carbon dioxide concentration in the flue
gas stream 124 by adjusting the feed rate of the feed stream 132,
it is within the scope of the present disclosure to maintain the
carbon dioxide concentration by, for example, selectively adjusting
the amount of the recycled portion 124a of the treated flue gas
stream 124' combined with the feed stream 132, and/or selectively
adjusting the concentration of oxygen present in the oxidant stream
134 combined with the feed stream 132.
[0043] It should also be appreciated that when the carbon dioxide
concentration present in the flue gas stream 124 is between about
10% to 60% by volume, the carbon dioxide capture system 150
operates at an energy load below about 3.0 GJ/ton of carbon dioxide
without the load of the oxygen producing unit 130, and at an energy
load of about 2.3 to 6.6 GJ/ton of carbon dioxide with the load of
the oxygen producing unit 130.
[0044] In one embodiment, the controller 260 includes a
microprocessor programmed to receive and send signals to and from
the aforementioned integrated flow control devices, sensors and
other test and measurement devices, and valves within the system
100. In one embodiment, the controller 260 receives input including
data and information from an operator of the system 100 (as
indicated by arrow O) or other portion of the system 100 (as
indicated at inputs 262). Information provided to the controller
260 includes, but is not limited to, the electrical demand of the
system 100. It is contemplated that the operator can manually
control the operations of the controller 260 and various flow
control and sensing and measuring devices as described herein by
providing input to the controller 260. Alternatively, it is
contemplated that the operator may control the system 100 by
preprogramming commands, set points and other parameters of the
system 100 and allow the system to proceed in an automated manner,
for example, by comparing various measurement signals and
controlling adjustments of feed rates and concentrations of flow
streams as described herein. For example, and as described in
detail above, the control signals S and S1 selectively operate
valves 210, 220 and 240 to vary feed rates and concentrations of
the recycled flue gas 124a and 124b, the feed stream 132, the
oxidant stream 134, the fresh air stream 136 and the air stream
138.
[0045] In another embodiment, as shown in FIG. 4, the signal S may
also be provided to an integrated flow control device 280, for
example, a valve, which selectively adjusts an amount of steam 292
generated by steam turbine 290 and provided to the carbon dioxide
capture system 150. In one embodiment, the control signal S
communicates commands to the valve 280 to regulate an amount of
steam 292 to be provided to the carbon dioxide capture system 150.
In one embodiment, the amount of steam 292 currently provided to
the carbon dioxide capture system 150 is measured by, for example,
a sensor 282 at location H, and provided to the controller 260. The
controller 260 compares the measured amount of steam to a
predetermined or provided set point and, based on the comparison,
the controller 260 operates the valve 280 to selectively adjust
(increase or decrease) the amount of steam 292 provided to the
carbon dioxide capture system 150.
[0046] In yet a further embodiment, and as shown in FIG. 5, the
controller 260 may provide the signal S to an integrated flow
control device 300 such as, for example, a valve, disposed within
the flow path of the treated flue gas stream 124' to the carbon
dioxide capture system 150. The controller 260 evaluates flow
measurements measured or sensed by, for example, a sensor or like
testing and measuring device 302. The sensor 302 is disposed at,
for example, location G in the flow path of the treated flue gas
stream 124' to the carbon dioxide capture system 150 and provides
the measurements to the controller 260. In response, the controller
260 selectively operates the valve 300 to adjust (increase or
decrease) the flow of the treated flue gas stream 124' to the
carbon dioxide capture system 150. Accordingly, the controller 260
may selectively regulate the flow of the treated flue gas stream
124' to the carbon dioxide capture system 150 in relation to load
on the processing system 100. For example, the controller 260
increases flow to the carbon dioxide capture system 150 as the
processing system 100 increases combustion of the fuel 122 and
consequently increases the amount of the output flue gas stream
124, or decreases flow to the carbon dioxide capture system 150 as
the processing system 100 decreases combustion of fuel 122 and
decreases the amount of output flue gas stream 124.
[0047] As shown in FIGS. 4 and 5, in a further embodiment, the
controller 260 provides a combination of the control signals S and
S1, which cascades to the respective valves 210, 220, 240 and 300.
However, it is contemplated that controller 260 does not provide
all of the signals within the flue gas stream processing system
100. For example, some control signals may originate from operator
input.
[0048] In addition to the functions noted above, it is contemplated
that controller 260 is programmed to contain information pertaining
to the cost of compressing the air stream 138 fed to the oxygen
producing unit 130 in order to generate the oxidant stream 134, the
reboiler duty, as well as the desired concentration of oxygen
present in the feed stream 132 provided to the combustion system
120. The controller 260 may further be programmed in a manner to
compare the parameters of the flue gas stream processing system 100
in an effort to manage the costs associated with running the flue
gas processing system 100. Additionally, it is contemplated that
the controller 260 can manage the parameters of the flue gas stream
processing system 100 in a dynamic fashion, for example, change
flow rates of flue gas stream 124 and/or the feed stream 132 to
adapt to the measured concentrations of oxygen, carbon dioxide,
and/or a combination thereof. Such dynamic control of the flue gas
stream processing system 100 allows the energy load of the
processing system 100 to be more efficiently managed.
[0049] Unless otherwise specified, all ranges disclosed herein are
inclusive and combinable at the end points and all intermediate
points therein. The terms "first," "second," and the like, herein
do not denote any order, quantity, or importance, but rather are
used to distinguish one element from another. The terms "a" and
"an" herein do not denote a limitation of quantity, but rather
denote the presence of at least one of the referenced item. All
numerals modified by "about" are inclusive of the precise numeric
value unless otherwise specified.
[0050] While the invention has been described with reference to
various exemplary embodiments, it will be understood by those
skilled in the art that various changes may be made and equivalents
may be substituted for elements thereof without departing from the
scope of the invention. In addition, many modifications may be made
to adapt a particular situation or material to the teachings of the
invention without departing from the essential scope thereof.
Therefore, it is intended that the invention not be limited to the
particular embodiment disclosed as the best mode contemplated for
carrying out this invention, but that the invention will include
all embodiments falling within the scope of the appended
claims.
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