U.S. patent application number 14/736562 was filed with the patent office on 2015-12-17 for flame position control electrodes.
The applicant listed for this patent is ClearSign Combustion Corporation. Invention is credited to JOSEPH COLANNINO, IGOR A. KRICHTAFOVITCH.
Application Number | 20150362177 14/736562 |
Document ID | / |
Family ID | 54835838 |
Filed Date | 2015-12-17 |
United States Patent
Application |
20150362177 |
Kind Code |
A1 |
KRICHTAFOVITCH; IGOR A. ; et
al. |
December 17, 2015 |
FLAME POSITION CONTROL ELECTRODES
Abstract
A method and apparatus for stabilizing a flame in a combustion
volume is disclosed. The present method and device may include a
burner nozzle configured to support the flame, a halo electrode
configured to anchor the flame, and electrodes disposed in top and
bottom regions of the flame configured to apply voltage difference
above or below the halo electrode that may assist in anchoring of
the flame to the halo electrode while also controlling a shape and
position of the flame. Effects of different electrical
configurations within the combustion volume for stabilizing the
flame are also disclosed.
Inventors: |
KRICHTAFOVITCH; IGOR A.;
(KIRKLAND, WA) ; COLANNINO; JOSEPH; (BELLEVUE,
WA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
ClearSign Combustion Corporation |
SEATTLE |
WA |
US |
|
|
Family ID: |
54835838 |
Appl. No.: |
14/736562 |
Filed: |
June 11, 2015 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
62010931 |
Jun 11, 2014 |
|
|
|
Current U.S.
Class: |
431/8 ;
431/253 |
Current CPC
Class: |
F23D 2209/20 20130101;
F23C 99/001 20130101 |
International
Class: |
F23C 99/00 20060101
F23C099/00 |
Claims
1. A combustion system, comprising: a burner nozzle having a
longitudinal axis, positioned within a combustion volume and
configured to emit a flow stream, including a mixture of fuel and
oxidizer, that expands and slows at distances receding away from
the burner nozzle, and to support a flame via the flow stream; a
first high-voltage power supply (HVPS); and a first electrode
operatively coupled to the first HVPS, the first electrode being
configured and disposed on a diameter generally concentric with the
longitudinal axis of the burner nozzle at a first distance from the
burner nozzle, the first distance corresponding to a region in
which the flow stream has expanded and marginally slowed, the first
HVPS being configured to supply a first voltage potential to the
first electrode, sufficient to charge the flame such that the
charged flame is stably held on or near a surface of the first
electrode.
2. The combustion system of claim 1, wherein the first electrode
has a ring torus shape disposed in a plane and having a center axis
of rotation normal to the plane, wherein the center axis of
rotation is about coincident with the longitudinal axis of the
burner nozzle.
3. The combustion system of claim 2, comprising an electrically
resistive coating on the surface of the first electrode.
4. The combustion system of claim 2, further including one or more
additional electrodes, each operatively coupled to a respective
additional HVPS.
5. The combustion system of claim 4, wherein the one or more
additional electrodes include a second electrode disposed a second
distance from the burner nozzle, greater than the first distance
and corresponding to a top region of the charged flame.
6. The combustion system of claim 5, wherein the second electrode
has a ring torus shape disposed on a diameter generally concentric
with the longitudinal axis of the burner nozzle.
7. The combustion system of claim 5, wherein the second electrode
is configured to receive a second voltage potential, different from
the first voltage potential from the respective additional HVPS of
the second electrode, and thereby producing an electrical field
along a length of the charged flame between the first electrode and
the second electrode.
8. The combustion system of claim 5, wherein the one or more
additional electrodes include a third electrode disposed a third
distance from the burner nozzle, less than the first distance and
corresponding to a base region of the charged flame, the additional
respective HVPS of the third electrode being configured to provide
a third voltage potential to the third electrode, and to produce
thereby a voltage difference between the first electrode and the
third electrode.
9. The combustion system of claim 8, wherein the first, second, and
third voltage potentials are selected to produce voltage
differences between each of the first, second, and third
electrodes.
10. The combustion system of claim 5, wherein the one or more
additional electrodes comprise a second electrode disposed a second
distance from the burner nozzle, less than the first distance and
corresponding to a base region of the charged flame.
11. The combustion system of claim 6, wherein each of the first and
the one or more additional electrodes further includes a switch for
independently opening and closing electrical continuity between the
first and the one or more additional electrodes and the respective
additional HVPS.
12. The combustion system of claim 1, wherein the oxidizer is
selected from the group consisting of oxygen in ambient air, oxygen
concentrated air, oxygen, ozone, hydrogen peroxide, recycled flue
gases and combinations thereof.
13. The combustion system of claim 1, wherein the oxidizer is
oxygen from ambient air.
14. A combustion system, comprising: a burner nozzle having a
longitudinal axis and configured to emit a flow stream including a
mixture of fuel and oxidizer within a combustion volume, the burner
nozzle being electrically coupled to a circuit ground; a first
electrode disposed a first distance from the burner nozzle
corresponding to a top region of flame supported by the flow stream
emitted by the burner nozzle; a high-voltage power supply (HVPS)
operatively coupled to the first electrode and configured to supply
a first voltage potential to the first electrode; a second
electrode having a ring torus shape lying in a plane and having a
center axis of rotation normal to the plane and about coincident
with the longitudinal axis of the burner nozzle, the second
electrode being disposed a second distance, less than the first
distance, from the burner nozzle; an electrical resistance
operatively coupled between the second electrode and the burner
nozzle, a series circuit being established between the HVPS and the
circuit ground, via the first electrode, the flame, the second
electrode, the electrical resistance, and the burner nozzle, the
series circuit being configured to establish a second voltage
potential at the second electrode on the basis of a current flowing
in the circuit and the resistive value of the electrical
resistance.
15. The combustion system of claim 14, comprising a third electrode
disposed a third distance, less than the second distance, from the
burner nozzle, and wherein: the electrical resistance comprises a
first resistor operatively coupled between the second electrode and
the third electrode, and a second resistor operatively coupled
between the third electrode and the burner nozzle; and the series
circuit is configured to establish the second voltage potential at
the second electrode on the basis of the current flowing in the
circuit and a sum of the resistive values of the first and second
resistors; and the series circuit is further configured to
establish a third voltage potential at the third electrode on the
basis of the current flowing in the circuit and the resistive value
of the second resistor.
16. A method for stably positioning a flame within a combustion
volume, comprising the steps of: supporting a flame within a
combustion volume by emitting into the combustion volume a flow
stream, including a mixture of fuel and oxidizer, from a burner
nozzle; and operating a first high-voltage power supply (HVPS) to
generate a first voltage potential; and holding the flame to a
first electrode by applying the first voltage potential to the
flame and electrically attracting the flame to the first
electrode.
17. The method of claim 16, wherein the applying the first voltage
potential to the flame and electrically attracting the flame to the
first electrode comprises applying the first voltage potential to
the first electrode.
18. The method of claim 16, wherein the holding the flame to a
first electrode comprises holding the flame to a first electrode
having a ring torus shape disposed in a plane and having a center
axis of rotation normal to the plane and about coincident with an
axis of the burner nozzle.
19. The method of claim 16, wherein the applying the first voltage
potential to the flame and electrically attracting the flame to the
first electrode comprises: applying the first voltage potential to
a first electrode positioned a first distance from the nozzle; and
applying a second voltage potential, different from the first
voltage potential, to a second electrode positioned a second
distance, different than the first distance, from the burner
nozzle.
20. The method of claim 19, wherein the applying a second voltage
potential to a second electrode comprises applying the second
voltage potential to a second electrode having a ring torus shape,
disposed on a diameter generally concentric with an axis of the
burner nozzle.
21. The method of claim 19, wherein the applying a second voltage
potential to a second electrode positioned a second distance from
the burner nozzle comprises applying the second voltage potential
to the second electrode positioned a second distance, less than the
first distance, from the nozzle.
22. The method of claim 19, wherein: the applying the first voltage
potential to a first electrode comprises closing a switch
operatively coupled between a first voltage source and the first
electrode; and the applying a second voltage potential to a second
electrode comprises closing a second switch operatively coupled
between a second voltage source and the second electrode.
23. The method of claim 19, wherein the applying a second voltage
potential to a second electrode positioned a second distance from
the burner nozzle comprises applying the second voltage potential
to the second electrode positioned a second distance, greater than
the first distance, from the nozzle.
24. The method of claim 23, comprising: applying a third voltage
potential to a third electrode positioned a third distance, less
than the first distance, from the nozzle.
25. The method of claim 16, wherein the first electrode is
positioned a first distance from the nozzle, and wherein applying
the first voltage potential to the flame and electrically
attracting the flame to the first electrode comprises: applying the
first voltage potential to a second electrode positioned a second
distance, greater than the first distance, from the nozzle; passing
a first electrical current from the second electrode through the
flame to the first electrode, and from the first electrode through
an electrical resistance to a circuit ground; and holding the
burner at a ground potential.
26. The method of claim 25, comprising passing a second electrical
current from the first electrode through the flow stream to the
burner nozzle.
27. The method of claim 25, comprising establishing an electrical
field along the flow stream between the first electrode and the
burner nozzle.
28. The method of claim 27, wherein the electrical resistance
comprises first and second series resistors, the method comprising
controlling a voltage potential at a third electrode positioned
between the first electrode and the burner nozzle and electrically
coupled to a node between the first and second series resistors by
selecting relative resistance values of the first and second series
resistors.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] The present application claims priority benefit from U.S.
Provisional Patent Application No. 62/010,931, entitled "FLAME
POSITION CONTROL ELECTRODES", filed Jun. 11, 2014; which, to the
extent not inconsistent with the disclosure herein, is incorporated
by reference.
BACKGROUND
Technical Field
[0002] The present disclosure relates generally to combustion
systems, and more particularly, to electrical configurations for
stabilizing a flame position within a combustion volume.
SUMMARY
[0003] Methods and devices for stabilizing a flame provided by
combustion of a fuel and an oxidizer within a combustion volume may
include a burner nozzle supporting the flame, and one or more
electrodes configured to electrically communicate with one or more
voltage power sources. The flame may additionally be charged by
different methods for allowing interaction with electrical charges
that may be applied within the combustion volume for better flame
stabilization.
[0004] According to various embodiments, a halo electrode may
include an applied voltage potential configured to charge the halo
electrode, and include additional applied voltage potentials
configured to charge one or more electrodes disposed above or below
the charged halo electrode and may be configured to improve flame
stability by attaching or anchoring the flame to the halo electrode
and thereby maintaining the flame in a suitable shape and position.
Different electrical configurations may be employed for the
application of the voltage potentials.
[0005] According to an embodiment, a suitable voltage source, such
as a DC or an AC low-voltage power source or a DC or an AC
high-voltage power source, may apply a voltage potential to the
halo electrode to create an electric field that may interact with
the flame to attach or anchor the flame to the halo electrode.
Additionally, another voltage source may apply a voltage potential
to a top electrode disposed above the halo electrode configured to
create a voltage difference between the top electrode and the halo
electrode. Such an arrangement may create an electric current that
may assist in keeping the flame attached or anchored to the halo
electrode. Furthermore, sensors located in various parts of the
combustion volume may be configured to detect movements in the
flame and may be further configured to send signals to switches and
controllers for application of voltage potentials to either or both
electrodes, respectively, for keeping the flame in a desired
position. Other embodiments may further include combinations of one
or more electrodes disposed above and/or below the flame configured
to provide for better flame stabilization.
[0006] According to another embodiment, the top electrode again may
be positioned above the halo electrode and configured to charge the
flame. A first resistor may be operatively coupled between the halo
electrode and a bottom electrode positioned below the halo
electrode and a second resistor may be operatively coupled between
the bottom electrode and the burner nozzle, wherein the burner
nozzle is itself operatively coupled to a ground potential. When
the flame makes contact with the halo electrode, a current may flow
across the first resistor and second resistor producing voltage
drops proportional to the current being passed through the
respective resistors that may allow the flame to better attach or
anchor to the halo electrode. The halo electrode and resistor may
also be combined by coating the halo electrode with a ceramic or
otherwise electrically resistive coating applied to its surface or
otherwise at least partially in series with the electrically
conductive path.
BRIEF DESCRIPTION OF DRAWINGS
[0007] Various, non-limiting embodiments are disclosed and
described by way of example with reference to the accompanying
figures. The figures are schematic and are not intended to be drawn
to scale. Unless indicated as representing the background art, the
figures represent aspects of the disclosure.
[0008] FIGS. 1A and 1B are intended to show a velocity distribution
of a fuel stream exiting a burner nozzle and passing through a
surrounding ambient atmosphere and the respective shape of a flame
within a combustion volume, according to an embodiment.
[0009] FIG. 2 shows an application of a first voltage potential to
a halo electrode disposed above a burner nozzle, according to an
embodiment.
[0010] FIG. 3 depicts an application of a second voltage potential
to a second electrode disposed above the halo electrode of FIG. 2,
according to an embodiment.
[0011] FIG. 4 depicts an application of a voltage third potential
to a third electrode disposed below the halo electrode of FIG. 2,
according to an embodiment.
[0012] FIG. 5 depicts an application of voltage potentials to a
second electrode disposed above and a third electrode disposed
below the halo electrode of FIG. 2, according to an embodiment.
[0013] FIG. 6 shows the application of voltage potentials to the
halo electrode and the control of the flame position by connection
of resistors below the halo electrode between the halo electrode
and a third electrode and between the burner and the third
electrode, according to an embodiment.
[0014] FIG. 7 shows application of voltage potentials to the halo
electrode and to a second halo electrode disposed in and
surrounding the top portion of the flame above the first halo
electrode, according to an embodiment.
DETAILED DESCRIPTION
[0015] In the following detailed description, reference is made to
the accompanying drawings, which form a part hereof. In the
drawings, similar symbols typically identify similar components,
unless context dictates otherwise.
[0016] Other embodiments may be used and/or other changes may be
made without departing from the spirit or scope of the
disclosure.
[0017] Problems in combustion systems due to instabilities in flame
position and shape may be caused in part by high, subsonic, or even
supersonic speeds of fuel being injected into a combustion volume.
High fuel injection speeds may result in a non-uniform fuel
distribution and an unstable flame within the combustion volume,
which may cause problems such as poor combustion, increased
emissions of pollutants, flashback, poor heat transfer, reduced
component life, and system damage, amongst others.
[0018] Embodiments are disclosed that include methods and devices
for the application of voltage potentials proximate to a flame
within a combustion volume for improving flame position
stabilization. The present disclosure is described in detail with
reference to embodiments illustrated in the drawings, which form a
part hereof. In the drawings, which are not necessarily to scale or
to proportion, similar symbols typically identify similar
components, unless context dictates otherwise. Other embodiments
may be used and/or other changes may be made without departing from
the spirit or scope of the present disclosure. The illustrative
embodiments described in the detailed description are not meant to
be limiting of the subject matter presented herein.
[0019] As used herein, the following terms may have the following
definitions:
[0020] "Halo electrode" refers to a conducting material in a
circumferential shape such as a ring, a toroid, or an annulus
configured for the application of an electric charge, a voltage
potential, and/or an electric field proximate to a flame. The halo
electrode may be unbroken (continuously circumferential to the
flame with no cut) or may be embodied as one or more sections
having an air gap. The halo electrode and a resistance may
optionally be combined by means of a ceramic or otherwise
electrically resistive coating applied to the halo electrode or
otherwise partially or wholly in series with the electrically
conductive path.
[0021] "Anchoring" refers to maintaining a flame position relative
to a solid surface such as the halo electrode, in such a way that
the anchored region of the flame stays proximate to the solid
surface.
[0022] FIG. 1A is a diagram showing a fuel flow velocity V1, V2, V3
distribution and flame 106 (shown in FIG. 1B) within a combustion
volume 102, which may include a burner nozzle 104 configured to
support a flame 106 (shown in FIG. 1B), according to an embodiment.
Also shown is the distribution of fuel 108 being injected from the
burner nozzle 104 into the combustion volume 102. Accordingly, the
closer the fuel 108 is to the burner nozzle 104, the higher fuel
flow velocity is, thus flow velocity V1 may be greater than flow
velocity V2 and flow velocity V2 may be greater than flow velocity
V3 (i.e., V1>V2>V3). The combustion volume 102 may be, for
example, part of a boiler, a water tube boiler, a fire tube boiler,
a hot water tank, a furnace, an oven, a flue, a cook top, or
another system employing the combustion volume 102. Not shown is a
source of an oxidizer supporting combustion of the fuel 108. The
oxidizer may include ambient air into which the fuel stream exits
or it may include a separate flow of oxidizer materials, such as
oxygen concentrated air, oxygen, ozone, hydrogen peroxide, recycled
flue gases, or combinations thereof, injected directly into the
fuel flow stream.
[0023] FIG. 1B shows an idealized behavior of a flame 106 according
to the distribution of fuel flow velocities V1, V2, V3. Fuel flow
velocities V1, V2, V3 may range from subsonic to supersonic, making
control of the flame 106 more difficult in the areas closer to the
burner nozzle 104. Accordingly, the flame 106 may be more easily
controlled in region V3 than in region V2 and more easily
controlled in region V2 than in region V1. If no control system is
applied in the combustion volume 102, different factors such as
heat requirement variations, weather, and component wear or damage,
among others, may affect the shape and stability of flame 106.
[0024] The flame 106 may include a variety of charged and uncharged
particles and molecules. The volume of charged particles may
include electrons 110, positive ions 112, negative ions, positively
and negatively charged particles, such as charged and uncharged
fuel vapor, and charged and uncharged combustion products, unburned
fuel 108, and air. The volume of charged particles may be
distributed in various locations of combustion volume 102 at
different times during the combustion process.
[0025] Because of rapid transient behavior, the flame 106 may need
to be controlled at every instant to prevent the flame 106 from
contact with objects or components or combustion equipment within
the combustion volume 102, in order to avoid potential damages due
to thermal effects. During any of such possible events, power may
be removed or applied to electrodes in the combustion volume 102
through one or more switches and/or control circuits attached to
the power source, to repel or attract the flame 106. These
electrodes may include different shapes and types and may be
arranged in different configurations within the combustion volume
102.
[0026] A halo electrode along with the application of voltage
potentials above or below the halo electrode may improve flame
stability by anchoring the flame 106 and keeping the flame 106 in a
suitable, stable position.
[0027] FIG. 2 depicts an embodiment configured to provide an
application of a voltage potential to a halo electrode 202 within a
combustion volume 102. Accordingly, the halo electrode 202 may be
located in different areas above a burner nozzle 104, such as
proximate to V3, where fuel flow velocity may be lower and a flame
106 may be more easily controlled, as shown in FIGS. 1A and 1B. The
halo electrode 202 may exhibit a diameter D ranging from about 1 cm
to about 10 cm, depending on intended use, and have a center axis
of rotation lying on or about coincident with a longitudinal axis A
of the burner nozzle 104. The halo electrode 202 may be made of
different suitable high temperature, corrosion resistant conductive
materials, including, for example, silver, copper, gold, tungsten,
nickel, iron, platinum, tin, and alloys thereof. The halo electrode
202 may be used for anchoring the flame 106, improving flame
stability. The flame 106 may or may not touch the halo electrode
202. Additionally, the flame 106 may be charged by different
methods, such as connecting a voltage power source to the burner
nozzle 104, or connecting a voltage power source to electrodes in
different areas near the flame 106 along the flame length, or to
the halo electrode 202, e.g., a first high-voltage power supply
(HVPS1) 204. Charging the flame 106 may allow for a better
electrical control of the flame 106, allowing for modifications of
the shape and position of the flame 106.
[0028] Any suitable voltage source, such as a first DC or an AC
low-voltage power source or a first DC or an AC high-voltage power
supply such as HVPS1 204, may be configured to apply a voltage
potential to the halo electrode 202, which may create an electric
field proximate to the halo electrode 202 that may interact with
charged particles included in the flame 106. For example, if the
flame 106 carries a positive charge and the halo electrode 202
carries a negative charge, the electric field may attract positive
ions 112 of the flame 106 helping to attach or anchor the flame 106
to the halo electrode 202.
[0029] The electric field may include one or more DC electric
fields, one or more AC electric fields, one or more pulse trains,
one or more time-varying waveforms, one or more digitally
synthesized waveforms, and/or one or more analog waveforms, or
combinations thereof.
[0030] Generally, when describing embodiments employing voltage
power sources, sensors may also be included in different parts of
the combustion volume 102 and configured for detecting movement in
the flame 106 and sending signals to switches and controllers
operatively coupled to the high-voltage power sources, which may
apply voltages to one or more additional electrodes for attracting
or repelling the flame 106 in order to maintain the flame 106 at a
suitable, stable shape and position. The different voltage
potentials may also charge the flame 106. For example, sensors may
be operatively coupled to the halo electrode 202 and may then send
signals to switches and controllers for the first high-voltage
power supply HVPS1 204 to initiate or change the voltage potentials
applied to the halo electrode 202.
[0031] FIG. 3 shows another embodiment configured to control an
application of voltage potentials, through one or more switches
and/or control circuits, by first and second high-voltage power
supplies HVPS1 204 and HVPS2 304, respectively, to a halo electrode
202, and to a second electrode 302 located above a flame 106,
within a combustion volume 102.
[0032] According to various embodiments, a first voltage potential
may be applied by the first high-voltage power supply HVPS1 204 to
the halo electrode 202 and a second voltage potential may be
applied by the second high-voltage power supply HVPS2 304 to the
second electrode 302. For example, this arrangement can be
especially advantageous for creating an electrical field along the
flame 106 to maintain a suitable flame shape and position. For
example, if the halo electrode 202 is at a different (e.g., lower)
potential than the second electrode 302 (at a higher potential),
then a voltage difference (V.sub.E2-V.sub.E1) between outputs of
the first and second high-voltage power supplies HVPS1 and HVPS2
can generate a movement or a flow of charges within the flame 106
between the first and second potentials (e.g. parallel or
antiparallel to current, depending on polarity). The arrangement of
FIG. 3 may thereby drive an electric current, I, that attracts the
flame 106 for more stable anchoring on or near the halo electrode
202. Other charge combinations, levels, and polarities are possible
for attracting or repelling the flame 106, which may depend on
flame position and behavior. In experiments, the inventors found
either or both (AC) polarities can cause enhanced flame anchoring.
Some experiments implied that supplying a positive polarity on
HVPS2 (relative to HVPS1), in an otherwise electrically isolated
system, may tend to have a stronger relative anchoring effect than
the opposite polarity.
[0033] FIG. 4 depicts an additional embodiment configured to
provide an application of voltage potentials below a halo electrode
202 within a combustion volume 102, in which a second electrode 402
may be charged by a second high-voltage power supply HVPS2 404.
Accordingly, different voltage potentials may be applied through
one or more switches and/or control circuits by a first
high-voltage power supply HVPS1 204 to the halo electrode 202, and
by the second high-voltage power supply HVPS2 404 to the second
electrode 402 to create a voltage difference (V.sub.E1-V.sub.E3).
For example, if the second electrode 402 is at a lower potential
than the halo electrode 202, the voltage difference between the
first and second high-voltage power supplies HVPS1 204 and HVPS2
404, can, again, generate a charge flow in the flame 106 creating
an electric current, I, that may drag down the flame 106 and may
assist in keeping the flame 106 anchored at or slightly below the
halo electrode 202. Other charge combinations, levels, and
polarities are possible for attracting or repelling the flame 106,
which may depend on flame position and behavior.
[0034] FIG. 5 depicts another embodiment configured to provide an
application of respective selected voltage potentials above and
below a halo electrode 202 within a combustion volume 102. The halo
electrode 202 may be operatively coupled to a first high-voltage
power supply HVPS1 204, a second electrode 302 disposed above the
halo electrode 202 may be operatively coupled to a second
high-voltage power supply HVPS2 304, and a third electrode 402
disposed below the halo electrode 202 may be operatively coupled to
a third high-voltage power supply HVPS3 404. Each power source can
be controlled through one or more switches and/or control circuits.
Different voltage levels and/or polarities may be applied to the
halo electrode 202, second electrode 302, and third electrode 402
for suitable flame stabilization, flame modulation, or other
desirable effects.
[0035] FIG. 6 depicts another embodiment configured to provide an
application of voltage potentials within a combustion volume 102,
in which a second electrode 302, powered by a first high-voltage
power supply HVPS1 304 controlled through one or more switches
and/or control circuits, may charge a flame 106. A first resistor
(R1) may be operatively coupled between the halo electrode 202 and
a third electrode 402, neither of which includes a high-voltage
power supply. A second resistor (R2) may be operatively coupled
between the third electrode 402 and the burner nozzle 104, wherein
the burner nozzle 104 is operatively coupled to a circuit ground
602. The resistors, R1 and R2, may have different values. When the
flame 106 makes contact with the halo electrode 202, a current, I,
may flow across the first and second resistors R1 and R2, producing
a voltage drop equal to current times the total resistance
(V.sub.A=I(R1+R2)), establishing a first voltage potential
(V.sub.A) at the halo electrode 202, with respect to the ground
potential at the circuit ground 602. The voltage drop produced
across the first and second resistors R1 and R2 may allow the flame
106 to be more effectively anchored to the halo electrode 202.
[0036] A second voltage potential (V.sub.B) at the third electrode
402--relative to the ground potential--is equal to the voltage drop
across the second resistor R2, i.e., current times the second
resistance (V.sub.B=IR2). In accordance with very well-known
principles, the ratio of the second voltage potential V.sub.B at
the third electrode 402 to the first voltage potential V.sub.A at
the halo electrode is equal to the ratio of the second resistance
R2 to the total resistance
( V B = R 2 R 1 + R 2 V A ) . ##EQU00001##
Thus, for a given first voltage potential V.sub.A at the halo
electrode 202, the value of the second voltage potential V.sub.B at
the third electrode 402 can be varied by varying the relative
values of the first and second resistors R1, R2 provided the total
resistance R1+R2 remains the same.
[0037] As described above, a first series circuit may be
established between the high-voltage power supply HVPS1 304 and the
circuit ground 602 via the second electrode 302, the flame 106, the
halo electrode 202, and the first and second resistors R1, R2.
[0038] At the same time, however, a second series circuit may be
established between the halo electrode 202 and the circuit ground
602 via the fuel stream 108 and the burner nozzle 102. The second
series circuit is electrically parallel to the portion of the first
series circuit extending between the halo electrode 202 and the
circuit ground 602 via the first and second resistors R1, R2.
Alternatively, where there is little or no electrical current flow
in the fuel stream 108, an electrical field may be established by
the voltage difference between first voltage potential V.sub.A, at
the halo electrode 202, and ground potential, at the burner nozzle
104. Finally, in embodiments that include the third electrode 402,
a voltage distribution within an electric field established across
the fuel stream 108 can be controlled by selection of the value of
the second voltage potential V.sub.B, at the third electrode 402.
The value of the second voltage potential V.sub.B can, in turn, be
determined by selection of the relative values of the first and
second resistors R1, R2, as explained above.
[0039] FIG. 7 depicts another embodiment configured to provide an
application of voltage potentials to a first halo electrode 202 and
to a second halo electrode 702 configured to further control a
flame 106. Anchoring may result when the first halo electrode 202
is operatively coupled through one or more switches and/or control
circuits to a first high-voltage power supply HVPS1 204 while a
second halo electrode 702 is operatively coupled through one or
more switches and/or control circuits to a second high-voltage
power supply HVPS2 304 such that, if the first halo electrode 202
is at a lower potential than the second halo electrode 702, then a
voltage difference (V.sub.E2-V.sub.E1) between the first and second
high-voltage power supplies HVPS1 and HVPS2 again generates a
charge flow (current, I) toward the lower potential that may drag
down the flame 106 for more stable anchoring on the first halo
electrode 202. In other embodiments other shapes, positions, and
combinations of electrodes may be considered for an efficient
anchoring of the flame 106 within the combustion volume 102.
[0040] Ordinal numbers, e.g., first, second, third, etc., are used
in the claims according to conventional claim practice, i.e., for
the purpose of clearly distinguishing between claimed elements or
features thereof. The use of such numbers does not suggest any
other relationship, e.g., order of operation, relative position of
such elements, etc. Furthermore, an ordinal number used to refer to
an element in the claims does not necessarily correlate to a number
used in the specification to refer to an element of a disclosed
embodiment on which those claims read, nor to numbers used in
unrelated claims to designate similar elements or features.
[0041] Where a claim limitation recites a structure as a
grammatical object of the limitation, that structure itself is not
an element of the claim, but is a modifier of the subject. For
example, in a hypothetical limitation that recites "a burner nozzle
configured to emit a flow stream and to support a flame within the
flow stream," the flow stream is not an element of the claim (nor
is the flame), but instead serves to help define the scope of the
term burner nozzle. Additionally, subsequent limitations or claims
that recite or characterize additional elements relative to the
flow stream do not render the flow stream an element of the claim.
Only where the flow stream itself is recited as the grammatical
subject of a claim limitation does it become an essential element
of the claim.
[0042] The abstract of the present disclosure is provided as a
brief outline of some of the principles of the invention according
to one embodiment, and is not intended as a complete or definitive
description of any embodiment thereof, nor should it be relied upon
to define terms used in the specification or claims. The abstract
does not limit the scope of the claims.
[0043] Finally, while various aspects and embodiments have been
disclosed herein, other aspects and embodiments are contemplated.
The various aspects and embodiments disclosed herein are for
purposes of illustration and are not intended to be limiting, with
the true scope and spirit being indicated by the following
claims.
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