Title of Invention

"A BURNER FOR A GAS TURBINE COMBUSTOR"

Abstract A burner (200) for a gas turbine combustor comprising: a burner housing (204) having axially opposed upstream and downstream end portions (212,214), the housing having at least one main fuel inlet passage (216) and at least one main air inlet passage (218) which are adapted to supply fuel and air respectively to an internal chamber (219) defined in the housing; means (210, 262, 264) disposed within the burner housing (204) for creating heat and free radicals and providing the heat and free radicals to the internal chamber (219) of the housing (204); characterized by comprising: means (206), disposed centrally along the axis of the burner housing (204), for quenching the exhausted heat and free radicals immediately prior to their entry into the internal chamber (219).
Full Text FIELD OF THE INVENTION:
The present invention relates to a burner for a gas turbine combustor.
The subject invention further relates to burners for gas turbines, and more particularly, to burners adapted to stabilize engine combustion, and still further, to burners that use a pilot combustor to provide combustion products (e.g., heat and free radicals) to stabilize the main lean premixed combustion.
Gas turbines are employed in a variety of applications including electric power generation, military and commercial aviation, pipeline transmission and marine transportation. In a gas turbine engine, fuel and air are provided to a burner chamber where they are mixed and ignited by a flame, thereby initiating combustion. The major problems associated with the combustion process in gas turbine engines, in addition to thermal efficiency and proper mixing of the fuel and air, are flame stabilization, the elimination of pulsations and noise, and the control of polluting emissions, especially nitrogen oxides (NOx).
The combustion process requires heat to be added to the fuel-air
mixture in order to initiate the reaction. Once the reaction has started, the heat
released by the combustion can be used to initiate the reaction itself and the process
becomes self-sustaining. However, some mechanism must be used to transport the
heat from the combustion back upstream to the ignition point. Alternatively, where
the reaction is not self-sustaining, heat and/or free radicals must be provided from a
separate source, such as, a heated catalytic metal surface, or a separate pilot flame.
Any combination of these methods, as well as, other methods, can also be used to
provide the necessary heat to initiate combustion.
The most common self-sustaining combustion process used in gas
turbine engines utilizes swirling air flows that recirculate the combustion products and
transport the hot gases and free radicals produced by the previously reacted fuel and
air back upstream to initiate the combustion of the freshly mixed fuel and air. A prior
art swirl-stabilized burner is illustrated in Figure 1 and is designate by reference
numeral 100. Generally, with swirl-stabilized combustion, the center main
recirculation zone is the dominant source of recirculated hot gases and free radicals
that are transported upstream to stabilize the combustion. When the combustion
process becomes very lean, and therefore, little heat is released from the combustion
and the amount of heat and free radicals that are transported back upstream is
insufficient to assure that combustion is initiated and sustained. The low temperatures
of the lean combustion products produce low equilibrium levels of free radicals. The
low temperature of the combustion products caused by the lean combustion also
results in a low free radical production rate when the recirculated combustion
products mix with the fresh un-reacted premixed fuel and air. Under these conditions
the induction time required to initiate combustion becomes excessive and the flame
blows away, or becomes unstable and fluctuates in intensity.
The basic problem with lean premixed combustion systems used to
produce low NOx emissions is that the fuel-air mixture must be so lean in order to
have the flame temperature sufficiently low to prevent NOx production that under
many operating conditions the combustion may not produce sufficient heat to be selfsustaining.
An auxiliary source of heat and free radical must be used to sustain
combustion. If an auxiliary pilot at high temperatures (close to stoichiometric) is
used, it will stabilize the lean main flame, but it will produce substantial NOx
emissions.
Purely thermally initiated combustion starts the combustion process by
pyrolyzing fuel at high temperatures to produce active free radicals. Initially this
occurs with very low fuel consumption and no measurable temperature rise. Through
chain branching reaction mechanisms the initially produced free radicals create an
exponentially increasing pool of free radicals. Eventually the radical pool becomes
sufficiently large to consume a significant amount of fuel, leading to rapid ignition
(Wamatz). The time it takes for this pool of free radicals to increase sufficiently
enough to cause the ignition is the "Ignition-Delay Time" or the "Induction Time".
When the initial temperature is increased the production rate of free radicals is
increased at an exponential rate and the induction time for initiation of combustion is
reduced. If the initial temperature is less than the auto-ignition temperature, no
ignition will occur for any time period. Free radicals, as well as, hot gases are
contained in the combustion products that are mixed with the fresh premixed fuel-air
mixture, in order to initiate combustion. These previously generated free radicals can
significantly reduce the induction time for combustion. If the entrained free radicals
are in sufficient quantity, rapid combustion initiation will occur at lower temperatures,
which would otherwise have long induction times without the entrained free radicals.
Stable combustion requires rapid initiation of combustion of the premixed fuel and air
immediately after being mixed with the hot products of the previously burnt fuel.
In view of the foregoing, a need exists for an improved burner, which
reduces NOx emissions while maintaining a stable combustion process.
SUMMARY OF THE INVENTION
The subject application is directed to burners for gas turbine engines
that use a pilot flame to assist in sustaining and stabilizing the combustion process.
An embodiment of the disclosed burners includes, inter alia, a burner housing, a pilot
combustor and a quencher.
The burner housing has axially opposed upstream and downstream end
portions. Additionally, the housing has at least one main fuel inlet passage and at
least one main air inlet passage which are adapted to supply fuel and air respectively
to an internal chamber defined in the housing.
The pilot combustor is disposed along the axis of the burner housing
and has an inlet for receiving a rich fuel and air mixture, a combustion chamber
within which the rich fuel and air mixture is combusted into combustion products, and
an outlet for exhausting the combustion products from the combustion chamber.
It is envisioned that in specific embodiments of the present invention,
the outlet of the pilot combustor has an annular cross-section and surrounds the
quencher. Still further, the outlet of the pilot combustor can include a plurality of
apertures formed in a radially outer surface thereof for directing a second source of
cooling air toward the combustion products exhausted from the pilot combustor.
5"
The quencher is disposed within the internal chamber of the burner
housing along the central axis and positioned at the outlet of the pilot combustor. The
quencher has an air inlet and a plurality of radially-oriented air outlets for directing
cooling air toward the outlet of the pilot combustor and quenching the combustion
products exhausted from the pilot combustor.
It is envisioned that some embodiments of the disclosed burners
include a flame holder disposed within the internal chamber of the burner housing.
The flame holder has a base portion that is engaged with the burner housing and an
elongated cylindrical bluff body extending in an axially downstream direction from
the base portion into the internal chamber. Preferably, the flame holder has an
axially-extending central air passage formed therein which communicates with the
quencher inlet and supplies air thereto.
It is envisioned that exemplary embodiments of the disclosed burners
can further include a quarl device disposed adjacent to the downstream end of the
burner housing. The quarl device defines an interior recirculation chamber and a
burner exit. The interior recirculation chamber is adapted for receiving
precombustion gases from the mixing chamber and for recirculating a portion of the
combustion products in an upstream direction so as to aid in stabilizing combustion.
It is further envisioned that the disclosed burners can include an igniter
positioned along the central axis for the burner housing and adapted for igniting a
main lean combustion within the internal chamber of the burner housing at a forward
stagnation point of a main recirculation zone.
The present invention is also directed to a burner for a gas turbine
combustor which includes a burner housing that defines a main internal combustion
chamber, a device for creating heat and free radicals within the housing and a
mechanism for quenching the heat and free radicals prior to proving the heat and free
radicals to the main internal combustion chamber. Preferably; the quenched heat and
free radicals are provided along the axis of the burner housing to the main internal
combustion chamber.
The burner housing has axially opposed upstream and downstream end
portions and at least one main fuel inlet passage and at least one main air inlet passage
which are adapted to supply fuel and air respectively to the internal main combustion
chamber defined in the housing.
The device for creating heat and free radicals is disposed within the
burner housing and provides the heat and free radicals to the main internal
combustion chamber of the housing. It is envisioned that the device which creates
heat and free radicals can be a pilot combustor disposed along the axis of the burner
housing. Preferably, the pilot combustor includes at least one inlet for receiving a rich
fuel and air mixture, a combustion chamber within which the rich fuel and air mixture
is combusted into heat and free radicals, and an outlet for exhausting the heat and free
radicals from the combustion chamber.
The mechanism for quenching the heat and free radicals immediately
prior to their entry into the main internal combustion chamber is also disposed within
the burner housing. It is envisioned that the means for quenching the exhausted heat
and free radicals includes a quencher disposed within the internal chamber of the
burner housing along the central axis. Preferably, the quencher is positioned at the
outlet of the pilot combustor and includes an air inlet and a plurality of radiallyoriented
air outlets for directing cooling air toward the outlet of the pilot combustor
and quenching the combustion products exhausted from the pilot combustor.
7
Embodiments of the disclosed burners can further include a flame holder disposed within the internal chamber of the burner housing. The flame holder includes a base portion engaged with the burner housing and an elongated cylindrical bluff body extending in an axially downstream direction from the base portion into the main internal combustion chamber. It is presently preferred that the flame holder has an axially-extending central air passage formed therein which communicates with the quencher inlet and supplies air thereto.
It is also envisioned that the disclosed burners can includes quarl device disposed adjacent to a downstream end portion of the burner housing. The quarl device defines an interior recirculation chamber and a burner exit. The interior recirculation chamber is adapted for receiving precombustion gases from the main internal combustion chamber and for recirculating a portion of the combustion products in an upstream direction so as to aid in stabilizing combustion.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
So that those having ordinary skill in the art to which the present application appertains will more readily understand how to make and use the same, reference may be had to the drawings wherein:
Fig. 1 is a cross-sectional view of a prior art burner which recirculates the combustion products in an attempt to create self-sustaining combustion;
Fig. 2 is a perspective view in cross-section of the swirl stabilized burner of the subject invention which includes a pilot combustor to assist in sustaining and stabilizing the combustion process; and
Fig. 3 is a cross-sectional view of the burner of Fig. 2 illustrating the
swirl flow within the burner and the anchoring of the forward stagnation point of a
main recirculation zone and the flame front by the center bluff body flame holder.
These and other features of the burner of the present application will
become more readily apparent to those having ordinary skill in the art form the
following detailed description of the preferred embodiments.
Referring now to Figs. 2 and 3, which illustrate an exemplary
embodiment of the burner of the subject application, which has been designated by
reference numeral 200. Burner 200 uses a pilot flame 202 to assist in sustaining and
stabilizing the combustion process. Burners 200 includes, inter alia, a burner housing
204, a pilot or pilot combustor 210 and a quencher 206. The burner housing 204 has
axially opposed upstream and downstream end portions 212 and 214, respectively.
Additionally, the housing 204 has several main fuel inlet passages 216 and several air
inlet passage 218 which are adapted to supply fuel and air respectively to an internal
chamber 219 defined in the housing 204.
The pilot combustor 210 is disposed along the axis X-X of the burner
housing 204 and has an inlet 260 for receiving a rich fuel and air mixture, a
combustion chamber 262 within which the rich fuel and air mixture is combusted into
combustion products, and an outlet 264 for exhausting the combustion products from
the combustion chamber. The quencher 206 is disposed within the internal chamber
219 of the burner housing 204 along the central axis X-X and positioned at the outlet
264 of the pilot combustor 210. The quencher 206 has an air inlet 266 and a plurality
of radially-oriented air outlets 268 for directing cooling air toward the quench section
222 of the pilot combustor 210 and quenching the combustion products exhausted
from the pilot combustor.
Burner 200 includes a low NOx emissions pilot 210 that "generates" free
radicals and heat that are directed at the forward stagnation point 212 and into the
shear layer of the main recirculation zone 214. Burner 200 utilizes a pilot 210 that
burns rich in order to:
• Provide a stable high temperature heat source without high NOx
emission,
• Provide high quantities of free radicals (rich combustion at high
temperature produces very high levels of free radicals), and
• Provide the widest achievable stability limits.
The rich combustion products must be quenched before mixing with the lean
premixed main fuel and air in order to prevent high temperature combustion, which
would result in the production of NOx emissions. The rich combustion produces low
NOx emissions with high carbon monoxide (CO) and unbumed hydrocarbons due to
the low oxygen levels. The unbumed hydrocarbon and CO produced by the rich pilot
210 will be burned during the lean partially premixed combustion of the "main"
premixed fuel.
Rich Quench Lean (RQL) combustion systems are intended to produce low
NOx emissions by rich combustion. The combustion process is called rich, when
more fuel is supplied or consumed during combustion process than there is air
available to react with it. Rich combustion results in low NOx emission, because the
oxygen that is available will prefer to react with the hydrogen and carbon of the fuel,
and not with nitrogen. Rich combustion is also very desirable, because it is very
stable and readily ignitable. Generally, the rich flammability limits are wider than
10
lean limits, and flame temperature does not drop as fast when made richer, compared
to lean combustion made leaner. Rich combustion also produces high power flux
densities, because of the large amount of energy released compared to the air mass
flow rate. The main disadvantages of rich combustion are: 1) not all of the fuel is
fully reacted, resulting in decreased thermal efficiency, and 2) high concentration of
unburned hydrocarbons and carbon monoxide in the exhaust. The stability of rich
combustion and the high power density make rich combustion acceptable for many
applications where emissions of unburned hydrocarbons and carbon monoxide are
less of an issue and high power per weight ratio is highly desirable. Generally, it is
not a trend to use rich combustion alone for industrial power generation, because
significantly lower emissions levels are achieved during lean operation.
The Rich Quench Lean concept is a method of burning rich to gain the
stability of rich combustion without the formation of excessive levels of NOx, and
then transitioning to lean combustion to complete the combustion process. NOx
emissions are not produced during the rich combustion, because there is insufficient
oxygen and NOx is not formed during the lean combustion because the temperature is
low. The combustion temperature is low for the lean combustion, because the extra
air cannot react, does not produce heat, but must be heated by the fuel and air that
does react. The key or critical issue associated with successful Rich-Quench-Lean
combustion is the quench process. In the transition from rich to lean the mixture must
pass through the stoichiometric ideal mixture where the flame temperature is
maximized and NOx can be produced. These reactions at stoichiometric conditions
will occur very fast because of the high temperatures and large pool of free radicals
that exist as the result of the previous rich combustion. If the quench process does not
occur very fast, high levels of NOx emissions will result from high temperature
combustion occurring during the quench process.
11
Referring again to Figs. 2 and 3, A RQL combustor or pilot 210 is used as a
pilot injector located on the centerline X-X of a swirl stabilized lean partially
premixed burner/combustor 200. The RQL combustor/pilot 210 supplies
supplemental high concentrations of free radicals and heat directly to the forward,
stagnation point 212 and shear layer where the lean premixed flow mixes with hot
gases of the main recirculation zone 214. In this invention a central bluff body flame
holder 216, at the exit 218 of the RQL combustor/pilot 210, is used to stabilize the
location of the forward stagnation point 212 of the main recirculation zone 214 which
helps to stabilize and enables continuous combustion of the main premixed fuel and
air.
The flame holder 218 also functions, in this invention, to supply the quench auto
the quench section 242 of the RQL pilot 210. From the opposite wall 244 in the
quench section 242, additional quench air can be supplied to intensify the quenching
process. These features are best illustrated in Fig. 2. The flame holder 218 in the
center of the RQL pilot 210 makes the exit 218 of the RQL pilot an annular passage.
This makes the RQL pilot flow passage in the quench section 242 narrow with a high
surface area, making the quench more effective. The high surface area allows for
many jets of air to be used in the quench process. The narrow gap of the RQL quench
flow passage 222 limits the distance that the quench jets must penetrate. The scale of
the quench process must be kept small and the velocity of the flow high in order to
limit the time period where the mixture is at stoichiometric conditions. The mixing in
the quench process must be rapid and thorough; streaks of rich or stoichiometric
mixture exiting the quench section 242 would result in high local flame temperatures.
The quench process at the exit 218 of the RQL pilot 210 must be rapid
because of the large concentration of the free radicals that emerge from the rich
combustion process. The large free radical pool makes the induction time for the
initiation of the reaction of the remaining unburned hydrocarbons very rapid when
mixed with additional oxygen from the air during the quenching process. The
dimensional scale and turbulence scale of the quench must be small when air is used
as the quench medium. This makes it difficult to use Rich-Quench-Lean combustion
as the primary form of combustion in large gas turbines that require high volumetric
flow rates.
The very large pool of free radicals that emerge from an RQL system, which
makes large scale quenching difficult, is also what makes the RQL an ideal pilot for
lean premixed combustion. The high concentration of free radicals in the RQL pilot
exhaust will support rapid and stable combustion in very lean main swirl stabilized
combustion that would otherwise be too lean and at too low of temperature to be
stable. The ability to operate very lean without engine flameout is a very useful
characteristic for engine startup and to handle rapid engine load changes without overspeeding
the engine.
In swirl stabilized combustion, the process is initiated and stabilized by means
of transporting heat and free radicals from the previously combusted fuel and air, back
upstream towards the flame front. If the combustion process is very lean, as is the
case in lean-partially premixed combustion systems, the combustion temperature is
low, resulting in very low equilibrium levels of free radicals. Complicating this issue
is that at high engine pressures the free radicals produced by the combustion process
quickly relax to the equilibrium level that corresponds to the temperature of the
combustion products. This is due to the fact that the rate of this relaxation of the free
radicals to equilibrium levels increases exponentially with increasing pressure, while
on the other hand the equilibrium level of free radicals decreases exponentially with
decreasing temperature.
The higher the level of free radicals available for initiation of combustion, the
more rapid and stable the combustion process will tend to be. At the high pressures,
13
which modern Gas Turbines operate in, the relaxation time of the free radicals can be
short compared to the "transport" time required for the free radicals to be convected
downstream, from the point where they were produced in the shear layer of the main
recirculation zone, back upstream, towards the flame front and the forward stagnation
point of the main recirculation zone. As a consequence, by the time the re-circulating
flow within the main recirculation zone has convected free radicals back towards the
flame front where they mix and initiate combustion of the incoming "fresh" premixed
lean fuel and air mixture at the forward stagnation, the free radicals could have
reached such a low equilibrium level that stable combustion is not initiated.
In this invention, the scale of the RQL pilot is kept small and most of the
combustion of fuel occurs in the lean premixed main combustor 240, and not in the
RQL pilot combustor 210. The RQL pilot 210 can be kept small, because the free
radicals are released near the forward stagnation point 212 of the main recirculation
zone214. This is generally the most efficient location to supply additional heat and
free radicals to swirl stabilized combustion. Because the free radicals and heat
produced by the RQL pilot combustor 210 are used efficiently, its size can be small
and the quenching process can be effective.
Burner 200 utilizes high non-equilibrium levels of free radicals to stabilize the
main lean combustion. Because the outlet of the RQL quench is at the forward
stagnation point 212of the recirculating flow, the time scale between quench and
utilization of free radicals is very short, not allowing free radicals to relax to low
equilibrium levels. The flame holder 216 maintains the forward stagnation point 212
at the exit of the quench section 242 of the pilot 210 or quencher to assure the
distance and time from quench to mixing of the free radicals with the premixed fuel
and air is as short and direct as possible. This is very advantageous for high-pressure
gas turbine engines, which inherently exhibit severe thermoacoustic instabilities.
Aero gas turbine engines have high-pressure ratios in order to maximize their power
to weight ratio. This invention will be most advantages to these aero engines, aero
derivative industrial engine that also operate at high pressure, as well as high-pressure
industrial engines.
This invention also allows for the ignition of the main combustion to occur at
the forward stagnation point 212 of the main recirculation zone 214. Most gas turbine
engines must use the outer recirculation zone (see Fig. 1) as the location where the
spark, or torch igniter, ignites the engine. Ignition can only occur if stable
combustion can also occur; otherwise the flame will just blow out immediately after
ignition. The inner or main recirculation zone 214 is generally more successful at
stabilizing the flame, because the recirculated gas is transported back to a point
region, instead of a ringed region about the outside of the main premixed flow. The
heat from the recirculated combustion products is focused to a small region at the
forward stagnation point 212 of the main recirculation zone 212. The combustion
also expands outward in a conic shape from this forward stagnation point, as
illustrated in Fig. 3. This conic expansion downstream allows the heat and free
radicals generated upstream to support the combustion downstream allowing the
flame front to widen as it moves downstream. The center bluff body flame holder 216
illustrated in Fig. 2, compared to swirl stabilized combustion without the center bluff
body flame holder shown in Fig. 1, shows how the flame holder 216 shapes the flame
to be more conic and less hemispheric in nature. The more conic flame front allows
for a point source of heat to initiate combustion of the whole flow field effectively.
This source of heat and free radicals can either be the recirculated hot combustion
product, the RQL pilot 210, or both in combination.
When the igniter is placed in the outer recirculation zone, the fuel/air mixture
entering this region must often be made rich in order to make the flame temperature
sufficiently hot to sustain stable combustion in this region. The flame then often
cannot be propagated to the main recirculation until the main premixed fuel and
airflow becomes sufficiently rich, hot and has a sufficient pool of free radicals, which
occurs at higher fuel flow rates. When the flame cannot propagate from the outer
recirculation zone to the inner main recirculation zone shortly after ignition, it must
propagate at higher pressure after the engine spee4 begins to increase. This transfer
of the initiation of the main flame from the outer recirculation zone pilot only after
combustor pressure begins to rise results in more rapid relaxation of the free radicals
to low equilibrium levels, which is an undesirable characteristic that is counter
productive for ignition of the flame at the forward stagnation point of the main
recirculation zone. Ignition of the main recirculation may not occur until the pilot
sufficiently raises the bulk temperature to a level where the equilibrium levels of free
radicals entrained in the main recirculation zone and the production of addition free
radicals in the premixed main fuel and air mixture are sufficient to ignite the main
recirculation zone. In the process of getting the flame to propagate from the outer to
the main recirculation zone, significant amounts of fuel exits the engine without
burning from the un-ignited main premixed fuel and air mixture. A problem occurs if
the flame transitions to the main recirculation zone in some burner before others in the
same engine, because the burners where the flame stabilized on the inside burn hotter
since all of the fuel is burnt This burner-to-burner temperature variation can damage
engine components. This invention ignites the main recirculation zone directly with
the RQL pilot 210, avoiding these problems. The RQL pilot 210 is easy to ignite
because the mixture within the RQL pilot combustor 210 can be rich upon ignition
without having to make the entire engine rich.
Those skilled in the art will readily appreciate that the inventive
aspects of this disclosure can be applied to any type of combustor or burner, such as a
solid fuel burner or furnace.







WE CLAIM
1. A burner (200) for a gas turbine combustor comprising:
a) a burner housing (204) having axially opposed upstream and downstream end portions (212,214), the housing having at least one main fuel inlet passage (216) and at least one main air inlet passage (218) which are adapted to supply fuel and air respectively to an internal chamber (219) defined in the housing;
b) means (210, 262, 264) disposed within the burner housing (204) for creating heat and free radicals and providing the heat and free radicals to the internal chamber (219) of the housing (204);
characterized by comprising:
c) means (206), disposed centrally along the axis of the burner housing
(204), for quenching the exhausted heat and free radicals immediately
prior to their entry into the internal chamber (219).
2. A burner (200) as claimed in claim 1, wherein the quenched heat and free radicals are provided along the axis of the burner housing (204) to the internal chamber (219).
3. A burner (200) as claimed in claim 1, wherein the means for creating heat and free radicals comprises a pilot combustor (210) disposed along the axis of the burner housing (204).
4. A burner (200) as claimed in claim 3, wherein the pilot combustor (210) comprises at least one inlet (260) for receiving a rich fuel and air mixture, a combustion chamber (262) within which the rich fuel and air mixture is combusted into heat and free radicals, and an outlet for exhausting the heat and free radicals from the combustion chamber (262).
5. A burner (200) as claimed in claim 4, wherein the means for quenching the exhausted heat and free radicals comprises a quencher (206) disposed within the internal chamber of the burner housing along the central axis and positioned at the outlet of the pilot combustor (210), and
wherein the quencher (206) comprises an air inlet (266) and a plurality of radically-oriented air outlets (268) for directing cooling air toward the outlet of the pilot combustor (210) and quenching the combustion products exhausted from the pilot combustor (210).
6. The burner (200) as claimed in claim 1,
wherein the means for creating and providing heat and free radicals comprise a pilot combustor (210) disposed along the axis of the burner housing (204), the pilot combustor (210) having an inlet (260) for receiving a rich fuel and air mixture, a combustion chamber (262) within which the rich fuel and air mixture is combusted into combustion products, and an outlet (264) for exhausting the combustion products from the combustion chamber (262), and
wherein the means for quenching the exhausted heat and free radicals comprise a quencher (206) disposed within the internal chamber (219) of the burner housing (204) along the central axis and positioned at the outlet (264) of the pilot combustor (210), the quencher (206) having an air inlet (266) and a plurality of radically-oriented air outlets (268) for directing cooling air toward the outlet (264) of the pilot combustor (210) and quenching the combustion products exhausted from the pilot combustor (210).
7. A burner (200) as claimed in claim 10, comprising a flame holder (216) disposed within the internal chamber (219) of the burner housing (204) and having a base portion engaged with the burner housing (204) and an elongated cylindrical bluff body extending in an axially downstream direction from the base portion into the internal chamber (219).
8. A burner (200) as claimed in claim 7, wherein the flame holder (216) has an axially-extending central air passage formed therein which communicates with the quencher inlet (266) and supplies air thereto.
9. A burner (200) as claimed in claim 1 or 6, comprising a quarl device disposed adjacent to a downstream end portion (214) of the burner housing (204), the quarl device defining an interior recirculation chamber and a burner exit, the interior recirculation chamber adapted for receiving precombustion gases from a mixing chamber and for recirculating a portion of the combustion products in an upstream direction so as to aid in stabilizing combustion.
10.A burner (200) as claimed in claim 1 or 6, comprising an igniter positioned along the central axis for the burner housing (204) and adapted for igniting a main lean combustion within the internal chamber (219) of the burner housing (204) at a forward stagnation point of a main recirculation zone (214).
11. A burner (200) as claimed in claim 1 or 6, wherein the outlet of
the pilot combustor (210) has an annular cross-section and surrounds
the quencher (206).
12. A burner (200) as claimed in claim 10, wherein the outlet of the pilot combustor (210) has a plurality of apertures formed in a radially outer surface thereof for directing a second source of cooling air toward combustion products exhausted from the pilot combustor.

Documents:

1578-DELNP-2006-Abstract-(06-03-2012).pdf

1578-DELNP-2006-Abstract-(15-04-2010).pdf

1578-delnp-2006-abstract.pdf

1578-DELNP-2006-Assignment-(07-09-2009).pdf

1578-DELNP-2006-Claims-(06-03-2012).pdf

1578-DELNP-2006-Claims-(15-04-2010).pdf

1578-DELNP-2006-Claims.pdf

1578-DELNP-2006-Correspondence Others-(06-03-2012)..pdf

1578-DELNP-2006-Correspondence Others-(06-03-2012).pdf

1578-DELNP-2006-Correspondence Others-(21-02-2012).pdf

1578-DELNP-2006-Correspondence-Others (13-11-2009).pdf

1578-DELNP-2006-Correspondence-Others-(07-09-2009).pdf

1578-delnp-2006-Correspondence-Others-(11-12-2009).pdf

1578-DELNP-2006-Correspondence-Others-(15-04-2010).pdf

1578-delnp-2006-correspondence-others-1.pdf

1578-delnp-2006-correspondence-others.pdf

1578-DELNP-2006-Description (Complete)-(06-03-2012).pdf

1578-delnp-2006-description (complete).pdf

1578-DELNP-2006-Drawings-(15-04-2010).pdf

1578-delnp-2006-drawings.pdf

1578-DELNP-2006-Form-1-(06-03-2012).pdf

1578-DELNP-2006-Form-1-(07-09-2009).pdf

1578-DELNP-2006-Form-1-(15-04-2010).pdf

1578-delnp-2006-form-1.pdf

1578-delnp-2006-form-18.pdf

1578-DELNP-2006-Form-2-(06-03-2012).pdf

1578-DELNP-2006-Form-2-(15-04-2010).pdf

1578-delnp-2006-form-2.pdf

1578-DELNP-2006-Form-26 (13-11-2009).pdf

1578-delnp-2006-form-26.pdf

1578-delnp-2006-form-3.pdf

1578-DELNP-2006-Form-5-(06-03-2012).pdf

1578-delnp-2006-form-5.pdf

1578-DELNP-2006-GPA-(06-03-2012).pdf

1578-delnp-2006-GPA-(11-12-2009).pdf

1578-DELNP-2006-GPA-(21-02-2012).pdf

1578-delnp-2006-pct-101.pdf

1578-delnp-2006-pct-210.pdf

1578-delnp-2006-pct-237.pdf

1578-delnp-2006-pct-373.pdf

1578-DELNP-2006-Petition-137-(15-04-2010).pdf


Patent Number 252009
Indian Patent Application Number 1578/DELNP/2006
PG Journal Number 17/2012
Publication Date 27-Apr-2012
Grant Date 20-Apr-2012
Date of Filing 23-Mar-2006
Name of Patentee 1.DELAVAN INC., 2.SIEMENS AKTIENGESELLSCHAFT
Applicant Address WITTELSBACHERPLATZ 2. 80333, MUNCHEN,GERMANY.
Inventors:
# Inventor's Name Inventor's Address
1 CORNWELL, MICHAEL 19916 COLORADO ROAD SOUTH, BLOOMINGTON, MINNESOTA 55438, U.S.A.
2 MILOSAVLJEVIC VLADIMIR DUSAN S-612 83 FINSPONG, SWEDEN.
PCT International Classification Number F23R 3/34
PCT International Application Number PCT/US2004/028906
PCT International Filing date 2004-09-03
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 60/500,518 2003-09-05 U.S.A.