U.S. patent application number 13/439247 was filed with the patent office on 2013-04-18 for oxy-fuel furnace and method of heating material in an oxy-fuel furnace.
This patent application is currently assigned to AIR PRODUCTS AND CHEMICALS, INC.. The applicant listed for this patent is Gregory J. Buragino, Shailesh Pradeep Gangoli, Xiaoyi He, Aleksandar Georgi Slavejkov. Invention is credited to Gregory J. Buragino, Shailesh Pradeep Gangoli, Xiaoyi He, Aleksandar Georgi Slavejkov.
Application Number | 20130095437 13/439247 |
Document ID | / |
Family ID | 45955156 |
Filed Date | 2013-04-18 |
United States Patent
Application |
20130095437 |
Kind Code |
A1 |
Buragino; Gregory J. ; et
al. |
April 18, 2013 |
Oxy-Fuel Furnace and Method of Heating Material in an Oxy-Fuel
Furnace
Abstract
An oxy-fuel furnace and method of heating material in an
oxy-fuel furnace are disclosed. The method includes combusting
oxygen and fuel with an oxy-fuel burner arrangement in the oxy-fuel
furnace forming combustion gases, and maintaining a vortex
including the combustion gases within a central region of an
enclosure of the oxy-fuel furnace. The oxy-fuel burner arrangement
includes a plurality of high momentum oxy-fuel burners arranged at
an angle to generate the vortex, the angle being greater than 15
degrees but less than 75 degrees with respect to a furnace wall
boundary of the enclosure, an angular velocity of greater than 0.07
radians per second, or a combination thereof. The furnace includes
an oxy-fuel burner arrangement including at least two high momentum
oxy-fuel burners having high shape factor nozzle geometries, and an
enclosure. The vortex increases convective heating within the
enclosure and uniformity of heating within the enclosure.
Inventors: |
Buragino; Gregory J.;
(Macungie, PA) ; Gangoli; Shailesh Pradeep;
(Easton, PA) ; He; Xiaoyi; (Orefield, PA) ;
Slavejkov; Aleksandar Georgi; (Allentown, PA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Buragino; Gregory J.
Gangoli; Shailesh Pradeep
He; Xiaoyi
Slavejkov; Aleksandar Georgi |
Macungie
Easton
Orefield
Allentown |
PA
PA
PA
PA |
US
US
US
US |
|
|
Assignee: |
AIR PRODUCTS AND CHEMICALS,
INC.
Allentown
PA
|
Family ID: |
45955156 |
Appl. No.: |
13/439247 |
Filed: |
April 4, 2012 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61471900 |
Apr 5, 2011 |
|
|
|
Current U.S.
Class: |
431/9 ;
431/174 |
Current CPC
Class: |
F23C 3/006 20130101;
Y02E 20/34 20130101; F23L 7/007 20130101; F23C 5/32 20130101; Y02E
20/344 20130101 |
Class at
Publication: |
431/9 ;
431/174 |
International
Class: |
F23C 5/32 20060101
F23C005/32; F23L 7/00 20060101 F23L007/00 |
Claims
1. A method for heating material in an oxy-fuel furnace, the method
comprising: combusting oxygen and fuel with an oxy-fuel burner
arrangement in the oxy-fuel furnace forming combustion gases; and
maintaining a vortex including the combustion gases within a
central region of an enclosure of the oxy-fuel furnace; wherein the
oxy-fuel burner arrangement comprises a plurality of high momentum
oxy-fuel burners arranged at an angle to generate the vortex, the
angle being greater than 15 degrees but less than 75 degrees with
respect to a furnace wall boundary of the enclosure.
2. The method of claim 1, wherein at least one of the plurality of
high momentum oxy-fuel burners includes a high shape factor
nozzle.
3. The method of claim 1, wherein the plurality of high momentum
oxy-fuel burners includes staggered burners.
4. The method of claim 1, wherein the plurality of high momentum
oxy-fuel burners includes two burners.
5. The method of claim 1, wherein the plurality of high momentum
oxy-fuel burners includes four burners.
6. The method of claim 1, wherein the plurality of high momentum
oxy-fuel burners includes more than four burners.
7. The method of claim 1, wherein the vortex has an angular
velocity that is greater than a 0.07 radians per second.
8. The method of claim 1, wherein the angle is between about 30
degrees and about 60 degrees.
9. The method of claim 1, wherein the vortex induces convective
heat in an area of the enclosure, the area being between about 15%
and about 75% of the enclosure.
10. The method of claim 1, wherein the vortex induces convective
heat in an area of the enclosure, the area being between about 30%
and about 60% of the enclosure.
11. The method of claim 1, wherein the enclosure has a first
pressure within the vortex that is less than a second pressure that
is proximal to the furnace wall boundary of the enclosure.
12. The method of claim 1, further comprising heating metal within
the enclosure.
13. The method of claim 1, further comprising heating aluminum
within the enclosure.
14. The method of claim 1, wherein the vortex increases convective
heating within the enclosure.
15. The method of claim 1, wherein the vortex increases uniformity
of heating within the enclosure.
16. A method for heating material in an oxy-fuel furnace, the
method comprising: combusting oxygen and fuel with an oxy-fuel
burner arrangement in the oxy-fuel furnace forming combustion
gases; and maintaining a vortex including the combustion gases
within a central region of an enclosure of the oxy-fuel furnace;
wherein the vortex has an angular velocity of greater than 0.07
radians per second.
17. The method of claim 16, wherein at least one of the plurality
of high momentum oxy-fuel burners includes a non-circular nozzle
geometry.
18. The method of claim 16, wherein the plurality of high momentum
oxy-fuel burners includes staggered burners.
19. The method of claim 16, wherein the angle is greater than 15
degrees but less than 75 degrees with respect to a furnace wall
boundary of the enclosure.
20. An oxy-fuel furnace, comprising: an oxy-fuel burner arrangement
including at least two high momentum oxy-fuel burners having high
shape factor nozzles; and an enclosure; wherein the oxy-fuel burner
arrangement comprises a plurality of high momentum oxy-fuel burners
arranged at an angle to generate a vortex, the angle being greater
than 15 degrees but less than 75 degrees with respect to a furnace
wall boundary of the enclosure; wherein the vortex increases
convective heating within the enclosure and uniformity of heating
within the enclosure.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims priority to and benefit of U.S.
Provisional Patent Application No. 61/471,900, filed Apr. 5, 2011,
which is hereby incorporated by reference in its entirety.
BACKGROUND OF THE INVENTION
[0002] The present invention is directed to systems and methods of
heating materials. More specifically, the present invention is
directed to oxy-fuel furnaces and methods of heating material by
using oxy-fuel furnaces.
[0003] Nitrogen oxides (NOx) are among the primary air pollutants
emitted by combustion processes. Because NOx promotes the formation
of harmful atmospheric reaction products that cause smog, air
quality standards have been imposed by various government agencies
to limit the amount of NOx that can be emitted into the atmosphere.
As a result of the increasing environmental legislation in many
countries and increasing global awareness of atmospheric pollution,
modern combustion technology has been improved to reduce NOx
emissions from many types of combustion equipment.
[0004] The secondary metals industry is generally considered to be
a major source of NOx pollution and therefore is subject to
stringent regulations on NOx emissions. The reduction of NOx
production in combustion processes becomes more important in this
industry as the demand for metals increases while environmental
regulations on NOx become increasingly stringent. Full oxy-fuel
combustion theoretically can produce very low NOx emissions due to
the lack of nitrogen in the oxidant.
[0005] The secondary metals industry has had innovation that
reduces NOx emissions. Such a known system is described in U.S.
Pat. App. Pub. No. 2007/0254251, which is hereby incorporated by
reference in its entirety. The known system achieves spacious
combustion by entraining furnace gases into a flame zone. Such a
system reduces NOx emissions. However, further reductions are
desirable, especially if the further combustion NOx reductions are
balanced with heat energy consumption concerns, for example, by
balancing radiative and convective heat transfer components.
[0006] Traditional low-momentum oxy-fuel combustion is dominated by
radiative mode heat transfer but lacks a convective component of
heating. The lack of convective component is due to the low gas
volumes and can increase the potential for inconsistent or uneven
heating, hot spots, and the generation of NOx. In contrast, air
fuel combustion lacks efficiency of radiative heating because of
N.sub.2-dilution. However, air fuel combustion can have a strong
convective heat transfer component because of higher flue gas
volumes that can be useful in heating a product when combined with
radiation. However, the radiation from an air-fuel flame is much
lower than the radiation from an oxy-fuel flame.
[0007] An oxy-fuel furnace and method of heating material in an
oxy-fuel furnace that do not suffer from one or more of the above
drawbacks would be desirable in the art.
BRIEF SUMMARY OF THE INVENTION
[0008] In an exemplary embodiment, a method for heating material in
an oxy-fuel furnace includes combusting oxygen and fuel with an
oxy-fuel burner arrangement in the oxy-fuel furnace forming
combustion gases, and maintaining a vortex including the combustion
gases within a central region of an enclosure of the oxy-fuel
furnace. The oxy-fuel burner arrangement includes a plurality of
high momentum oxy-fuel burners arranged at an angle to generate the
vortex, the angle being greater than 15 degrees but less than 75
degrees with respect to a furnace wall boundary of the
enclosure.
[0009] In another exemplary embodiment, a method for heating
material in an oxy-fuel furnace includes combusting oxygen and fuel
with an oxy-fuel burner arrangement in the oxy-fuel furnace forming
combustion gases, and maintaining a vortex including the combustion
gases within a central region of an enclosure of the oxy-fuel
furnace. The vortex has an angular velocity of greater than 0.07
radians per second.
[0010] In another exemplary embodiment, an oxy-fuel furnace
includes an oxy-fuel burner arrangement including at least two high
momentum oxy-fuel burners having high shape factor nozzles, and an
enclosure. The oxy-fuel burner arrangement includes a plurality of
high momentum oxy-fuel burners arranged at an angle to generate a
vortex, the angle being greater than 15 degrees but less than 75
degrees with respect to a furnace wall boundary of the enclosure.
The vortex increases convective heating within the enclosure and
uniformity of heating within the enclosure.
[0011] Other features and advantages of the present invention will
be apparent from the following more detailed description of the
preferred embodiment, taken in conjunction with the accompanying
drawings which illustrate, by way of example, the principles of the
invention.
BRIEF DESCRIPTION OF SEVERAL VIEWS OF THE DRAWINGS
[0012] FIGS. 1 through 4 are schematic drawings of oxy-fuel
furnaces according to embodiments of the disclosure.
[0013] FIG. 5 is a three-dimensional schematic drawing of an
oxy-fuel furnace according to an embodiment of the disclosure.
[0014] FIG. 6 is a graphical comparison of an exemplary method of
heating material in an oxy-fuel furnace according to the disclosure
and other methods of heating material.
[0015] FIG. 7 is a graphical illustration of surface temperature as
a function of time for an exemplary oxy-fuel furnace according to
the disclosure.
[0016] FIG. 8 is a comparative graphical illustration of surface
temperatures of furnace walls and material due to operation of an
oxy-fuel furnace without forming a vortex.
[0017] FIG. 9 is a graphical illustration of surface temperatures
of furnace walls and material due to operation of an oxy-fuel
furnace forming a vortex according to the disclosure.
[0018] Wherever possible, the same reference numbers will be used
throughout the drawings to represent the same parts.
DETAILED DESCRIPTION OF THE INVENTION
[0019] Provided is an exemplary oxy-fuel furnace and method of
heating material in an oxy-fuel furnace. Embodiments of the present
disclosure increase the convective contribution of heat transfer in
an oxy-fuel heating process, decrease the cycle time for achieving
certain temperatures, increase efficiency, or combinations
thereof.
[0020] Referring to FIGS. 1 through 5, according to an embodiment,
an oxy-fuel furnace 100 includes at least two high-momentum
oxy-fuel burners 102 and an enclosure 104 generally defining a
combustion zone within the oxy-fuel furnace 100. The enclosure 104
is any suitable geometry and is defined by a furnace wall boundary
108. For example, in one embodiment, the enclosure 104 is a cuboid
or generally cuboid geometry. In another embodiment, the enclosure
104 is a cylindrical or generally cylindrical geometry. The
enclosure includes a central region, for example, defined by the
burner axis of each of the burners 102, the burner axis being a
line extending from the middle of the burner. The oxy-fuel furnace
100 includes other suitable features as are necessary to maintain
combustion, heating, other operational conditions, or combinations
thereof.
[0021] The enclosure 104 is configured for containing at least a
portion of a vortex 106 of combustion gases, such as a
furnace-scale vortex. The vortex 106 is formed by offset firing of
the burners 102 that entrains surrounding combustion gases into a
flame zone within the enclosure 104, thereby resulting in a
churning (or equilibration of gases) that forms the vortex 106, for
example, by transporting the combustion gases. In one embodiment,
the vortex 106 is used with spacious combustion, combustion
achieved by entrainment of furnace gases in a flame zone. In one
embodiment, the burners 102 form two different furnace gas
recirculation currents, for example, a horizontal component and a
vertical component that constrict the vortex 106 due to
differential pressure within the enclosure 104.
[0022] The burners 102 are arranged and disposed for forming the
vortex 106. The oxy-fuel furnace 100 includes two of the burners
102 (see FIGS. 1 and 2), three of the burners 102, four of the
burners 102 (see FIG. 3), or more than four of the burners 102. As
shown in FIG. 1, in one embodiment, the burners 102 are positioned
on opposite sides of the enclosure 104 on the furnace wall boundary
108, in a staggered orientation. As shown in FIG. 2, in one
embodiment, two of the burners 102 are positioned on the furnace
wall boundary 108 in an angular configuration. As shown in FIG. 3,
in one embodiment, four of the burners 102 are positioned on the
furnace wall boundary 108 in an angular configuration. Other
embodiments include combinations of these embodiments.
[0023] The burners 102 are any suitable burners capable of being
used under high-momentum conditions, such as, the burners disclosed
in U.S. Pat. App. Pub. No. 2007/0254251, which is incorporated by
reference in its entirety, and/or a high shape factor burner. As
used herein, the term "high-momentum" refers to flow of gases
through at least one channel of passageway of the burner 102 that
is greater than about 5 lb-ft/s.sup.2. In some embodiments, flow of
gases through at least one channel of passageway of the burner 102
is greater than about 10 lb-ft/s.sup.2, for example, as with
natural gas having a flow rate between about 10 lb-ft/s.sup.2 and
70 lb-ft/s.sup.2, enabling firing at higher rates, improving cycle
times, reducing localized overheating (such as overheating of
thermocouples), or combinations thereof. As used herein, the term
"high shape factor burner" refers to a burner having a nozzle
perimeter or multiple perimeters that is/are greater than a
perimeter of a circular nozzle. For example, a relative perimeter
ratio (P.sub.rel) is a ratio of the perimeter of nozzle(s) of a
high shape factor burner (such as, a non-circular burner) in
comparison to the perimeter of a circular nozzle. For nozzles
having areas of 1.0 in.sup.2, a circular nozzle has a perimeter of
3.54 inches. Thus, a high shape factor burner having a nozzle with
a 1.0 in.sup.2 has a perimeter that is greater than 3.54 inches. In
one embodiment, the high shape factor burner has a relative
perimeter ratio of 1.96.
[0024] Referring to FIGS. 4 and 5, in one embodiment, two or more
of the burners 102 form the vortex 106 by being angled at angle
.theta., with respect to the furnace wall boundary 108. The angle
.theta. corresponds with the specific configuration of the oxy-fuel
furnace 100 (for example, the geometry, the size, or combinations
thereof), the materials to be heated (for example, metal or
metallic materials, such as, ingots, sheets, cast materials, forged
materials, aluminum, iron, steel, ferrous materials, non-ferrous
materials, or combinations thereof), other suitable operational
considerations (for example, flow rates, compositions of oxy-fuel,
enclosure pressure, enclosure material, etc.), or a combination
thereof. The material heated is positioned at any suitable portion
within the enclosure 104, for example, on the bottom of the
enclosure 104. In one embodiment, the oxy-fuel includes a
composition of at least 50 mol % oxygen in the oxidizer (for
example, from an oxidizer flow of 95 mol % oxygen) and fuel (for
example, natural gas, propane, syngas, low Btu fuels, etc.).
[0025] In one embodiment, the angle .theta. is greater than 15
degrees, greater than 30 degrees, greater than 45 degrees, greater
than 60 degrees, less than 75 degrees, less than 60 degrees, less
than 45 degrees, less than 30 degrees, or any suitable range
sub-range, combination, or sub-combination thereof.
[0026] In one embodiment, the oxy-fuel furnace 100 enhances mixing
and furnace gas entrainment that reduces the peak flame temperature
and thermal NOx generation. The enhanced mixing is caused by the
burners 102 creating a lower pressure region having a first
pressure within the vortex 106 and a higher pressure region having
a second pressure that is proximal to the furnace wall boundary 108
of the enclosure 104.
[0027] The force (F.sub.inl) brought into the enclosure 104 of the
furnace 100 by the flow of combustion gases through the burner 102
can be represented as shown in Equation 1:
F.sub.inl=.rho..sub.inlQ.sub.inlu.sub.inl (Eq. 1)
[0028] As used in Equation 1, .rho..sub.inl refers to the density
of combustion flow entering the enclosure 104 (for example, as
measured in lb/ft.sup.3, dependent upon flame temperature).
u.sub.inl refers to the velocity of inlet flows entering the
enclosure 104 (for example, as measured in ft/s). Q.sub.inl refers
to the total inlet flow rate into the enclosure 104 (for example,
as measured in ft.sup.3/s).
[0029] In one embodiment, the entrainment of furnace gases into the
flame is enhanced by using nozzles in one or more of the burners
102 that have a high shape factor. The actual flow achieved by
strong interaction of the nozzles with the furnace gases can be
represented as shown in Equation 2:
F.sub.inl=.rho..sub.inl(Q.sub.inlP.sub.rel)u.sub.inl (Eq. 2)
[0030] As used in Equation 2, P.sub.rel refers to the relative
perimeter ration and Q.sub.inlP.sub.rel refers to the total actual
inlet flow rate (for example, as measured in ft.sup.3/s).
[0031] The vortex is generated by the balance of forces brought
into the furnace and viscous dissipation (F.sub.visc) of these
flows in the furnace, given by Equation 3:
F.sub.visc=.rho..sub.furnV.sub.furn(u.sub.t.sup.2/d.sub.e) (Eq.
3)
[0032] As used in Equation 3, .rho..sub.furn refers to the density
of furnace gases within the enclosure 104 (for example, as measured
in lb/ft.sup.3, dependent upon flame temperature). V.sub.furn
refers to the volume of the enclosure 104 in the oxy-fuel furnace
100 (for example, as measured in ft.sup.3). u.sub.t refers to the
tangential velocity of the Vortex at diameter d.sub.e inside the
enclosure 104 (for example, as measured in ft/s). d.sub.e refers to
a characteristic dimension of the Vortex 106 (for example, an
equivalent diameter measured in ft).
[0033] In one embodiment, the angular velocity (u.sub..omega.) of
the vortex 106 is defined using Equation 4, which is based upon
consolidation of equations 2 and 3:
u.sub..omega.=
(.rho..sub.rat((Q.sub.inlu.sub.inld.sub.e)/V.sub.furn))/.pi.d.sub.e
(Eq. 4)
[0034] As used in Equation 4, .rho..sub.rat refers to a density
ratio of inlet flows (.rho..sub.inl) to furnace gases
(.rho..sub.furn). The density ratio is between 0.8 for air-fuel
combustion and 0.6 for oxy-fuel combustion due to the difference in
flame temperature.
[0035] In one embodiment, the burners 102 enhance a convective heat
transfer component (in addition to a radiative heat transfer
component) to increase uniformity and/or efficiency of heating. For
example, in one embodiment, a vortex-induced component of the
convective heat transfer component increases uniformity and
efficiency by using the burners 102. The vortex-induced component
is achieved by arranging and/or orienting the burners 102 such that
the vortex 106 is formed and maintained within the enclosure 104.
In one embodiment, the convective heat transfer reduces or
eliminates direct impact of a flame on the material to be
heated.
[0036] In one embodiment, the vortex-induced component of the
convective heat transfer component impacts between 15% and 75% of
the (plan-view) area of the enclosure 104. In further embodiments,
the convective heat transfer component impacts between 30% and 60%,
between 30% and 45%, between 45% and 60%, about 15%, about 30%,
about 45% about 60% about 75%, or any suitable range, sub-range,
combination, or sub-combination thereof. In one embodiment, the
vortex-induced component is increased by increasing the angular
velocity (u.sub..omega.) of the vortex 106.
[0037] Referring to FIG. 6, the uniformity and efficiency of the
heating with the burners 102 forming the vortex 106 is improved in
comparison to one-sided firing and opposed (but not staggered)
burning. FIG. 6 shows profiles of heating steel ingots with the
enclosure 104 being in a pit furnace under different
configurations. A vortex-induced heating profile 602 is based upon
using the burners 102 to form the vortex 106 as described herein. A
one-sided-burner heating profile 604 is based upon using one-sided
firing, positioning the steel ingots at an end distal from a burner
and moving the steel ingots toward an end proximal to the burner.
An opposing-burner heating profile 606 is based upon having two
burners on opposing walls of a furnace. The jets collide and have
the tendency to overheat the steel ingots at the center of the pit
furnace. The opposing-burner heating profile 606 also creates large
heat flux gradients in comparison to the other configurations.
[0038] As shown in FIG. 6, the vortex-induced heating profile 602,
including the vortex-induced component, is maintained within a
temperature range of less than 25.degree. F. In further
embodiments, the vortex-induced heat profile 602 including the
vortex-induced component is maintained within a temperature range
of less than 10.degree. F., less than 5.degree. F., or is
substantially constant. In contrast, the one-sided-burner heating
profile 604 and the opposing-burner heating profile 606 exceed the
temperature range of 25.degree. F.
[0039] Referring to FIG. 7, the surface temperature of material
heated under the vortex-induced heat profile 602 and the
opposing-burner heating profile 606 described above are shown over
time. Each profile corresponds with a maximum surface face
temperature profile 702 and an average face temperature profile
704. The maximum surface face temperature profile 702 is
substantially consistent over time for the vortex-induced heat
profile 602 and the opposing-burner heating profile 606. The
average face temperature profile 704 bifurcates over time
permitting a decrease in cycle time for achieving a predetermined
average face temperature under the vortex-induced heat profile 602
in comparison to the opposing-burner heating profile 606. In one
embodiment, the decrease in cycle time is at least 10%, between 10%
and 20%, about 15%, or any suitable range, sub-range, combination,
or sub-combination thereof.
[0040] FIGS. 8 and 9 comparatively illustrate the heating of the
material within the enclosure 104 according to the vortex-induced
heat profile 602 (see FIG. 9) in contrast to the opposing-burner
heating profile 606 (see FIG. 8). Specifically, FIG. 8 illustrates
the temperature of walls within an enclosure heated by the
opposing-burner heating profile 606 and FIG. 9 illustrates the
temperature of the furnace wall boundary 108 heated by the
vortex-induced heat profile 602. FIG. 8 shows that the
opposing-burner heating profile 606 forms a hot spot 802. FIG. 9
shows that the vortex-induced heat profile 602 forms a more uniform
temperature gradient, for example, having no regions of the furnace
wall boundary 108 that exceed the temperature of the furnace wall
boundary 108 proximal to the burner 102, thereby allowing increased
amounts of energy input into the oxy-fuel furnace 100 and/or
reducing cycle times for achieving a predetermined temperature.
[0041] In one embodiment, the enclosure 104 has dimensions of 24
ft.times.9 ft.times.14 ft. In a heating process achieved in the
enclosure 104, the heating process uses an average of about 10
MMBTU/hr of air-fuel firing rate and about 6 MMBTU/hr of oxy-fuel
firing rate (assuming 45% and 75% available heat in the enclosure
104, respectively) to form the vortex 106. The angular velocity
(u.sub..omega.) of the vortex 106 is calculated, for example, based
upon Equations 1 through 4 above, and depends upon the fuel used
and the burner used. For example, air fuel combustion with a
staggered burner configuration (see FIG. 1) results in an angular
velocity (u.sub..omega.) of 0.099 rad/s and an angled burner
configuration (see FIG. 2) results in an angular velocity
(u.sub..omega.) of 0.087 rad/s. Low-momentum oxy-fuel combustion
with a staggered burner configuration (see FIG. 1) results in an
angular velocity (u.sub..omega.) of 0.035 rad/s and an angled
burner configuration (see FIG. 2) results in an angular velocity
(u.sub..omega.) of 0.031 rad/s. High-momentum oxy-fuel combustion
with a staggered burner configuration (see FIG. 1) and circular
nozzles results in an angular velocity (u.sub..omega.) of 0.079
rad/s and an angled burner configuration (see FIG. 2) results in an
angular velocity (u.sub..omega.) of 0.070 rad/s. High-momentum
oxy-fuel combustion with a staggered burner configuration (see FIG.
1) and non-circular nozzles results in an angular velocity
(u.sub..omega.) of 0.111 rad/s and an angled burner configuration
(see FIG. 2) results in an angular velocity (u.sub..omega.) of
0.097 rad/s.
[0042] In view of such differences, in one embodiment of the
disclosure, the burners 102 of the furnace 100 are arranged and
operated such that the vortex has an angular velocity that is
greater than a corresponding angular velocity for an air-fuel
combustion vortex that would be formed by air-fuel combustion, for
example, being at least 0.07 radians per second. In one embodiment,
the vortex 106 formed by combusting the oxy-fuel with the burners
102 having non-circular nozzles has an angular velocity that is 10%
greater than a vortex that would be formed by air-fuel combustion,
40% greater than the vortex 106 formed by the burners 102 having
the circular nozzles, 200% greater than a vortex that would be
formed by low-momentum oxy-fuel combustion, or a combination
thereof.
[0043] While the invention has been described with reference to a
preferred embodiment, 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.
* * * * *