U.S. patent application number 10/397394 was filed with the patent office on 2003-10-16 for catalytic combustor and method for substantially eliminating nitrous oxide emissions.
Invention is credited to Farhangi, Shahram, Matthews, David Robert, Moriarty, Michael Patrick, Sprouse, Kenneth Michael.
Application Number | 20030192319 10/397394 |
Document ID | / |
Family ID | 28793889 |
Filed Date | 2003-10-16 |
United States Patent
Application |
20030192319 |
Kind Code |
A1 |
Sprouse, Kenneth Michael ;
et al. |
October 16, 2003 |
Catalytic combustor and method for substantially eliminating
nitrous oxide emissions
Abstract
A combustor for a gas powered turbine which employs a heat
exchanger and a catalyst to combust a fuel without the emission of
undesired chemical species. A gas powered turbine requires
expanding gases to power the turbine blades. Fuel is combusted to
produce the required gases. A catalyst is employed to lower the
combustion temperature of the fuel. The catalyst is placed on a set
of tubes in the heat exchanger such that a portion of the thermal
energy may be transferred to the air before it engages the
catalyst. After encountering the catalyst, the combusted fuel
increases the temperature of the air to an auto-ignition
temperature so that no other ignition source is needed to combust
additional fuel.
Inventors: |
Sprouse, Kenneth Michael;
(Northridge, CA) ; Farhangi, Shahram; (Woodland
Hills, CA) ; Moriarty, Michael Patrick; (Simi Valley,
CA) ; Matthews, David Robert; (Simi Valley,
CA) |
Correspondence
Address: |
Mark D. Elchuk
Harness, Dickey & Pierce, P.L.C.
P.O. Box 828
Bloomfield Hills
MI
48303
US
|
Family ID: |
28793889 |
Appl. No.: |
10/397394 |
Filed: |
March 26, 2003 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10397394 |
Mar 26, 2003 |
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10189711 |
Jul 3, 2002 |
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10397394 |
Mar 26, 2003 |
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10120268 |
Apr 10, 2002 |
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Current U.S.
Class: |
60/777 ;
60/723 |
Current CPC
Class: |
F23R 3/40 20130101 |
Class at
Publication: |
60/777 ;
60/723 |
International
Class: |
F23R 003/40 |
Claims
What is claimed is:
1. A combustion system for use in a turbine which combusts a fuel
in the presence of air, which substantially eliminates nitrous
oxide emissions, comprising: a heat exchanger including: a catalyst
pathway extending along a first axis; a cooling pathway extending
along a second axis; wherein said catalyst pathway is in thermal
contact with said cooling pathway; wherein the air is adapted to
first flow through said cooling pathway and then through said
catalyst pathway; a catalyst, disposed within said catalyst
pathway, adapted to combust the fuel with the air; and wherein the
air is adapted to first flow past said catalyst pathway and through
said cooling pathway, thereby receiving thermal energy from said
catalyst pathway.
2. The combustion system of claim 1, wherein said catalyst pathway
comprises a plurality of catalyst members, which form a plurality
of catalyst columns each spaced apart transversally to said first
axis and which define a plurality of channels adapted for allowing
the air to flow therethrough; wherein said cooling pathway
comprises a plurality of cooling tubes, which form a plurality of
cooling tube columns each spaced apart transversally to said second
axis; and wherein said cooling tubes extend substantially adjacent
said catalyst members along said second axis for at least a portion
of the length of said catalyst members.
3. The combustion system of claim 2, wherein said catalyst members,
said cooling tubes, and said channels define a flow path for the
air such that the air is able to receive thermal energy from the
catalyst members by flowing through said channels and said cooling
tubes.
4. The combustion system of claim 1, wherein said thermal energy
allows the fuel to be combusted with said catalyst.
5. The combustion system of claim 1, wherein said catalyst
comprises a material able to combust a fuel in the air below about
1500.degree. C.
6. The combustion system of claim 1, further comprising: a heat
exchange area; a pre-mix area for mixing a first portion of the
fuel with the air; a main injector area comprising at least one
injector for said catalyst members; wherein a second portion of the
fuel is mixed with the air with said main injector; and wherein
said main injector is adapted to mix the second portion of fuel
with the air such that the temperature throughout the area of the
injector is substantially equal.
7. The combustion system of claim 1, further comprising fins
adapted to direct the flow of air around said catalyst tube.
8. The combustion system of claim 1, wherein said cooling pathway
includes a cooling fin and said catalyst pathway includes a
catalyst fin.
9. The combustion system of claim 1, wherein said first axis and
said second axis are parallel for at least a portion of said
catalyst pathway and said cooling pathway.
10. A turbine, comprising: a compressor adapted to produce
compressed atmospheric air; a combustion system for mixing and
combusting a fuel injected into the compressed atmospheric air to
produce expanding gases; a turbine which is powered by the
expanding gases: wherein said combustion system comprises: a first
fuel supply to supply fuel to the compressed atmospheric air; a
heat exchanger comprising a catalyst section including a catalyst
disposed within said catalyst section, wherein the compressed air
and the fuel flow through said catalyst section; and a second fuel
supply to supply fuel to the compressed atmospheric air after the
compressed atmospheric air has passed through said catalyst
section.
11. The turbine of claim 10, wherein said catalyst section
comprises a plurality of said catalyst members each extending along
a first axis; wherein said heat exchanger further includes a
plurality of cooling tubes each extending along a second axis
generally parallel to said first axis for at least a selected
length; wherein said catalyst members are arranged to form a
plurality of columns spaced transversally to said first axis and
defining a plurality of channels; and wherein said cooling tubes
are arranged in a plurality of columns and extend a distance along
said catalyst members and generally perpendicular to said
channels.
12. The turbine of claim 11, wherein said catalyst members, said
cooling tubes and said channels define a flow path for the
compressed atmospheric air such that the compressed atmospheric air
is adapted to receive thermal energy from said catalyst members by
flowing through said channels and said cooling tubes.
13. The turbine of claim 11, wherein thermal energy is transferred
to the compressed atmospheric air as it flows through said heat
exchanger such that the fuel from the first fuel supply is
combusted via said catalyst.
14. The turbine of claim 11, further comprising: a heat exchange
area; a pre-mix area for mixing a first portion of the fuel with
the air; a main injector area comprising at least one injector for
said catalyst tube; wherein a second portion of the fuel is mixed
with the compressed atmospheric air in said main injector; and
wherein said main injector is adapted to mix the second portion of
fuel with the compressed atmospheric air such that the temperature
throughout the area of the injector is substantially equal.
15. The turbine of claim 10, wherein said catalyst section
comprises a catalyst fin.
16. For a turbine, a method of combusting a fuel in the presence of
atmospheric air while substantially eliminating the emission of
nitrous oxide compounds, the method comprising: providing a heat
exchanger comprising a plurality of pathways; disposing a catalyst
in at least a sub-plurality of said pathways; forming a first
fuel-air mixture by mixing a first portion of the fuel and the air;
producing a auto-ignition air stream by combusting the first
fuel-air mixture by contacting the first fuel-air mixture with the
catalyst; and heating the air by transferring a portion of thermal
energy from the pathways to the air.
17. The method of claim 16, further comprising: forming a second
fuel-air mixture by adding a second portion of fuel to the
auto-ignition air stream; and producing an expanding gas by
combusting said second fuel-air mixture, said expanding gas
occurring when the fuel in the second fuel-air mixture reaches the
temperature of the auto-ignition air stream.
18. The method of claim 17, further comprising powering a turbine
with said expanding gas.
19. The method of claim 16, wherein said first fuel-air mixture has
an equivalence ratio of between about 0.10 and about 0.30.
20. The method of claim 17, wherein said second fuel-air mixture
has an equivalence ratio of between about 0.40 and about 0.60.
21. The method of claim 16, wherein said auto-ignition air stream
has a temperature between about 760.degree. C. (1400.degree. F.)
and 871.degree. C. (1600.degree. F.).
22. The method of claim 16, wherein the step of heating the air
comprises transferring a portion of the thermal energy produced in
the pathways when the catalyst forms the auto-ignition air
stream.
23. A combustion system for use in a gas powered turbine which
combusts a fuel in the presence of air while substantially
eliminating nitrous oxide emissions, comprising: a pre-heater to
heat a volume of an oxidizer to form a volume of high energy
oxidizer; an injector member to inject a fuel, including a high
temperature, into said volume of high energy oxidizer; an injector
port, defined by said injector member, to provide the fuel to said
volume of high energy oxidizer before a substantial portion of the
fuel combusts; and wherein substantially all the fuel provided
through said injector port reaches its said high temperature at
substantially the same time.
24. The combustion system of claim 23, wherein said pre-heater
includes: a catalyst pathway having a catalyst disposed therein; a
cooling pathway; and wherein said catalyst pathway and said cooling
pathway extend substantially parallel for a selected distance.
25. The combustion system of claim 24, wherein said catalyst
pathway comprises a plurality of catalyst members, that form a
plurality of catalyst columns each spaced apart transversally to
said first axis and which define a plurality of channels adapted
for allowing the oxidizer to flow therethrough; wherein said
cooling pathway comprises a plurality of cooling tubes that form a
plurality of cooling columns each spaced apart transversally to
said second axis; and wherein said cooling columns extend
substantially adjacent said catalyst columns along said second axis
for at least a portion of the length of said catalyst columns.
26. The combustion system of claim 23, further comprising: at least
a first and a second of said injector ports; a first fuel stream
produced by said first injector port; and a second fuel stream
produced by said second injector port; wherein said first fuel
stream and said second fuel stream impinge into one another to form
a fuel plume prior to intersect the high energy air.
27. The combustion system of claim 26, wherein said first fuel
stream and said second fuel stream intersect at an angle between
about 20.degree. and about 150.degree..
28. The combustion system of claim 26, further comprising: a fuel
path formed in said injector member such that the first fuel stream
and the second fuel stream provided by said first and second
injector ports intersect to produce said fuel plume.
29. The combustion system of claim 23, wherein said injector port
is substantially rectangular in shape such that a fuel stream is
flattened as said fuel stream exits said injector port.
30. A gas powered turbine, comprising: a compressor to produce
compressed atmospheric air to provide an oxidizer for the gas
powered turbine; a combustion system for mixing and combusting a
fuel injected into the compressed atmospheric air to produce an
expanding gas; a turbine fan which is powered by the expanding
gases: wherein said combustion system comprises: a pre-heat area; a
first fuel line to supply a first portion of fuel to the compressed
atmospheric air which is combusted in the pre-heat area to heat the
compressed atmospheric air to a hypergolic temperature so as to
produce hypergolic air; a second fuel line to supply a second
portion of fuel to the hypergolic air; an injector system to
provide said second portion of fuel to said hypergolic air before
any substantial portion of said second portion of fuel combusts;
and wherein substantially all of said second portion of fuel
combusts at substantially the same time such that the gas powered
turbine emits substantially no nitrous oxide compounds.
31. The turbine of claim 30, further comprising: the air before the
air enters the pre-heat area; a main injector plate comprising at
least a first and a second of said injectors; and a combustion area
wherein said second supply of fuel is combusted.
32. The turbine of claim 31, further comprising: a first fuel
stream produced by said first injector port; and a second fuel
stream produced by said second injector port; wherein said first
fuel stream and said second fuel stream impinge into one another
forming a fuel plume prior to intersecting the hypergolic air.
33. A method of combusting a fuel for a gas powered turbine in the
presence of atmospheric air while substantially eliminating the
emission of nitrous oxide compounds, the method comprising:
producing an auto-ignition air stream wherein a fuel homogeneously
combusts spontaneously upon reaching the temperature of said
auto-ignition air stream; providing a first portion of the fuel to
said auto-ignition air stream; and mixing said first portion of
fuel with said auto-ignition air stream before substantially any of
said first portion of fuel combusts to substantially eliminate
emission of nitrous oxide compounds.
34. The method of claim 33, further comprising: producing an
expanding gas by combusting said first portion of fuel in said
auto-ignition air-stream, said expanding gas occurring when said
portion of fuel in said auto-ignition air-stream combusts upon
reaching the temperature of the auto-ignition air stream.
35. The method of claim 34, further comprising powering a turbine
with said expanding gas.
36. The method of claim 33, wherein said auto-ignition air stream
has a temperature between about 760.degree. C. (1400.degree. F.)
and 871.degree. C. (1600.degree. F.).
37. The method of claim 33, wherein mixing said first portion of
fuel further comprises: impinging a first fuel stream upon a second
fuel stream to form a fuel plume.
38. The method of claim 37, wherein impinging said first fuel
stream upon said second fuel stream occurs at an angle between
about 20.degree. and about 150.degree..
39. The method of claim 38, further comprising: forming said first
fuel stream and said second fuel stream as substantially flat
streams before allowing said streams to impinge one another.
40. The method of claim 33, wherein mixing said first portion of
fuel further comprises providing a substantially flat fuel stream
to said auto-ignition air stream.
41. The method of claim 33, wherein producing an auto-ignition
air-stream further comprises: forming a fuel-air mixture by mixing
a second portion of fuel with a volume of air; and combusting said
second portion of fuel in said volume of air, wherein combusting
said second portion of fuel increases the temperature of said
volume of air to an auto-ignition temperature.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation-in-part of U.S. patent
application Ser. No. 10/189,711, entitled "INJECTOR APPARATUS AND
METHOD FOR COMBUSTING A FUEL FOR A GAS POWERED TURBINE" filed on
Jul. 3, 2002; and U.S. patent application Ser. No. 10/120,268,
entitled "A CATALYTIC COMBUSTOR AND METHOD FOR SUBSTANTIALLY
ELIMINATING NITROUS OXIDE EMISSIONS" filed on Apr. 10, 2002. The
disclosures of the above applications are incorporated herein by
reference.
FIELD OF THE INVENTION
[0002] The present invention relates generally to gas powered
turbines for generating power, and more particularly to a low
nitrous oxide emission combustion system for gas powered turbine
systems.
BACKGROUND OF THE INVENTION
[0003] It is generally known in the art to power turbines with
gases being expelled from combustion chambers. These gas powered
turbines can produce power for many applications such as
terrestrial power plants. In the gas powered turbine a fuel, such
as a hydrocarbon (for example methane or kerosene) or hydrogen, is
combusted in an oxygen rich environment. Generally, these
combustion systems have high emissions of undesirable compounds
such as nitrous oxide compounds (NOX) and carbon containing
compounds. It is generally desirable to decrease these emissions as
much as possible so that undesirable compounds do not enter the
atmosphere. In particular, it has become desirable to reduce NOX
emissions to a substantially low amount. Emissions of NOX are
generally desired to be non-existent, and are accepted to be
non-existent, if they are equal to or less than about one part per
million volume of dry weight emissions.
[0004] In a combustion chamber fuel, such as methane, is combusted
in atmospheric air where temperatures generally exceed about
1427.degree. C. (about 2600.degree. F.). When temperatures are
above 1427.degree. C., the nitrogen and oxygen compounds, both
present in atmospheric air, undergo chemical reactions which
produce nitrous oxide compounds. The energy provided by the high
temperatures allows the breakdown of dinitrogen and dioxygen,
especially in the presence of other materials such as metals, to
produce NOX compounds such as NO.sub.2 and NO.
[0005] It has been attempted to reduce NOX compounds by initially
heating the air before it enters the combustion chambers to an
auto-ignition temperature. If the air enters the combustion chamber
at an auto-ignition temperature, then no flame is necessary to
combust the fuel. Auto-ignition temperatures are usually lower than
pilot flame temperatures or the temperatures inside recirculation
flame holding zones. If no flame is required in the combustion
chamber, the combustion chamber temperature is lower, at least
locally, and decreases NOX emissions. One such method is to entrain
the fuel in the air before it reaches the combustion chamber. This
vitiated air, that is air which includes the fuel, is then ignited
in a pre-burner to raise the temperature of the air before it
reaches the main combustion chamber. This decreases NOX emissions
substantially. Nevertheless, NOX emissions still exist due to the
initial pre-burning. Therefore, it is desirable to decrease or
eliminate this pre-burning, thereby substantially eliminating all
NOX emissions.
[0006] Although the air is heated before entering the main
combustion chamber, it may still be ignited in the combustion
chamber to combust the remaining fuel. Therefore, an additional
flame or arc is used to combust remaining fuel in the main
combustion chamber. This reduces the temperature of the igniter,
but still increases the temperature of the combustion chamber. In
addition, no fuel is added to the air as it enters the combustion
chamber. Rather all the fuel has already been entrained in the air
before it enters the combustion chamber to be combusted. This
greatly reduces control over where combustion occurs and the
temperature in the combustion chamber
[0007] Other attempts to lower NOX emissions include placing
catalysts in catalytic converters on the emission side of the
turbines. This converts the NOX compounds into more desirable
compounds such as dinitrogen and dioxygen. These emission side
converters, however, are not one hundred percent efficient thereby
still allowing NOX emissions to enter the atmosphere. The emission
converters also use ammonia NH.sub.3, gas to cause the reduction of
NOX to N.sub.2. Some of this ammonia is discharged into the
atmosphere. Also, these converters are expensive and increase the
complexity of the turbine and power production systems. Therefore,
it is also desirable to eliminate the need for emission side
catalytic converters.
SUMMARY OF THE INVENTION
[0008] The present invention is directed to a combustor and a
combustion chamber for a gas powered turbine. A heat exchanger and
a catalyst combust a first portion of fuel intermixed with air
without the production of undesired chemical species. The gas
powered turbine requires expanding gases to power the turbine fans
or blades. Fuel is generally combusted to produce the required
gases. A catalyst is employed to lower the combustion temperature
of the fuel. The catalyst is placed on a set of tubes in a heat
exchanger such that a portion of the thermal energy may be
transferred to the air before it engages the catalyst. After
encountering the catalyst, the fuel that was combusted increases
the temperature of the air to an auto-ignition temperature so that
no other ignition source is needed to combust additional fuel added
later. Therefore, as the air exits the heat exchanger, it enters a
main combustion chamber, is mixed with a second portion of fuel
where it is auto-ignited and burned.
[0009] One preferred embodiment of the present invention includes a
combustion system for use in a gas powered turbine which combusts a
fuel in the presence of air while substantially eliminating nitrous
oxide emissions. The system includes a pre-heater to heat
compressed air to form a hypergolic air. An injector plate injects
a fuel into the hypergolic air. An injector port, defined by the
injector plate, provides the fuel to the hypergolic air before a
substantial portion of the fuel combusts. Substantially all the
fuel provided through the injector port reaches its hypergolic
temperature at substantially the same time.
[0010] A second preferred embodiment of the present invention
provides a gas powered turbine. The gas powered turbine includes a
compressor that produces compressed atmospheric air to provide an
oxidizer for the gas powered turbine. A combustion system mixes and
combusts a fuel injected into the compressed atmospheric air to
produce an expanding gas. A turbine fan is powered by the expanding
gases.
[0011] The combustion system of the second preferred embodiment
includes a pre-heat area, a first fuel line, a second fuel line,
and an injector system. The first fuel line supplies a first
portion of fuel to the compressed atmospheric air which is
combusted in the pre-heat area to heat the compressed atmospheric
air to a hypergolic temperature so as to produce hypergolic air.
The second fuel line supplies a second portion of fuel to the
hypergolic air. The injector system provides the second portion of
fuel to the hypergolic air before any substantial portion of the
second portion of fuel combusts. In addition, substantially all of
the second portion of fuel combusts at substantially the same time
such that the turbine emits substantially no nitrous oxide
compounds.
[0012] A third preferred embodiment includes a method of combusting
a fuel for a gas powered turbine in the presence of atmospheric air
while substantially eliminating the emission of nitrous oxide
compounds. The method includes providing a pre-heater. A first
fuel-air mixture is formed by mixing a first portion of the fuel
and the air. An auto-ignition air stream is produced by combusting
the first fuel-air mixture. A second portion of the fuel is then
added to the auto-ignition air stream. The second portion of fuel
is then mixed with the auto-ignition air stream before
substantially any of the second portion of fuel combusts.
[0013] A fourth preferred embodiment of the present invention
comprises a combustion system for use in a turbine which combusts a
fuel in the presence of air, which substantially eliminates nitrous
oxide emissions. The combustion system comprises a heat exchanger.
The heat exchanger includes at least one catalyst tube extending
along a first axis and at least one cooling tube extending along a
second axis. The axes of the catalyst tube and the cooling tube are
generally parallel. The catalyst tube is in thermal contact with
the said cooling tube. The air is adapted to first flow through the
cooling tube and then through the catalyst tube. A catalyst is
placed inside the catalyst tube. The catalyst is adapted to combust
the fuel with the air. The air is adapted to flow past the catalyst
tube and through the cooling tube, wherein the air receives thermal
energy from the catalyst tube as the air flows through the cooling
tube and past the catalyst tube.
[0014] A fifth preferred embodiment includes a turbine system
comprising a compressor adapted to produce compressed atmospheric
air; a combustion system for mixing and combusting a fuel in the
compressed atmospheric air to produce expanding gases; and a
turbine which is powered by the expanding gases. The combustion
system comprises a first fuel supply to supply fuel to the
compressed atmospheric air. The combustion system also includes a
heat exchanger comprising at least one catalyst tube comprising a
catalyst coated on the inside of the catalyst tube, wherein the
compressed air and the fuel flow through the catalyst tube. A
second fuel supply supplies fuel to the compressed atmospheric air
after the compressed atmospheric air has passed through the
catalyst tube.
[0015] A sixth preferred embodiment describes a method of operating
the present invention includes combusting a fuel in the presence of
atmospheric air while substantially eliminating the emission of
nitrous oxide compounds. The method comprises providing a heat
exchanger comprising hollow tubes; placing a catalyst on at least a
portion of the interior of the hollow tubes; forming a first
fuel-air mixture by mixing a first portion of the fuel and the air;
producing a auto-ignition air stream by combusting the first
fuel-air mixture by contacting the first fuel-air mixture with the
catalyst; and heating the air by transferring a portion of the
thermal energy from the hollow tubes to the air. Additional fuel
may be combusted in the auto-ignition air stream without the
application of an external igniter.
[0016] Further areas of applicability of the present invention will
become apparent from the detailed description provided hereinafter.
It should be understood that the detailed description while
indicating the various embodiments of the invention, are intended
for purposes of illustration only and are not intended to limit the
scope of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0017] The present invention will become more fully understood from
the detailed description and the accompanying drawings,
wherein:
[0018] FIG. 1 is a perspective view of a gas powered turbine
including a combustor in accordance with the present invention;
[0019] FIG. 2 is a partial cross-sectional perspective view of a
single combustor;
[0020] FIG. 3 is a detailed, partial cross-sectional, perspective
view of a portion of the heat exchanger;
[0021] FIG. 4 is a simplified diagrammatic view of the flow of air
through the combustion chamber according to a first embodiment of
the present invention;
[0022] FIG. 5 is a detailed, partial cross-sectional, perspective
view of a portion of the heat exchanger according to a second
embodiment;
[0023] FIG. 5a is a detailed view of a portion of the pre-mixer
according to the second embodiment;
[0024] FIG. 5b is a simplified diagrammatic view of a theoretical
airflow in the combustor according to the second embodiment;
[0025] FIG. 6 is a detailed, cross-sectional view of a portion of
the main injectors;
[0026] FIG. 7a is a detailed, elevational view of the downstream
side of the main injector plate according to a first embodiment of
the present invention;
[0027] FIG. 7b is a detailed cross-sectional view of the main
injector plate taken along line 7b in FIG. 7a;
[0028] FIG. 8a is a detailed elevational view of a downstream side
of the main injector plate according to a second embodiment of the
present invention;
[0029] FIG. 8b is a detailed cross-sectional view of the injector
plate taken along line 8b in FIG. 8a; and
[0030] FIG. 9 is a detailed, partial cross-sectional, perspective
view of a portion of the heat exchanger according to a second
embodiment.
DETAILED DESCRIPTION OF THE VARIOUS EMBODIMENTS
[0031] The following description of the various embodiments is
merely exemplary in nature and is in no way intended to limit the
invention, its application, or uses. Specifically, although the
following combustor is described in conjunction with a terrestrial
gas turbine, it may be used in other systems. Furthermore, the
mixer and heat exchanger may be used in systems other than turbine
systems.
[0032] Referring to FIG. 1, a gas powered turbine in accordance
with a preferred embodiment of the present invention is shown. The
gas powered combustion turbine 10 may use several different gaseous
fuels, such as hydrocarbons (including methane and propane) and
hydrogen, that are combusted and that expand to move portions of
the gas powered turbine 10 to produce power. An important component
of the gas powered turbine 10 is a compressor 12 which forces
atmospheric air into the gas powered turbine 10. Also, the gas
powered turbine 10 includes several combustion chambers 14 for
combusting fuel. The combusted fuel is used to drive a turbine 15
including turbine blades or fans 16 which are axially displaced in
the turbine 15. There are generally a plurality of turbine fans 16,
however, the actual number depends upon the power the gas powered
turbine 10 is to produce. Only a single turbine fan is illustrated
for clarity.
[0033] In general, the gas powered turbine 10 ingests atmospheric
air, combusts a fuel in it, which powers the turbine fans 16.
Essentially, air is pulled in and compressed with the compressor
12, which generally includes a plurality of concentric fans which
grow progressively smaller along the axial length of the compressor
12. The fans in the compressor 12 are all powered by a single axle.
The high pressure air then enters the combustion chambers 14 where
fuel is added and combusted. Once the fuel is combusted, it expands
out of the combustion chamber 14 and engages the turbine fans 16
which, due to aerodynamic and hydrodynamic forces, spins the
turbine fans 16. The gases form an annulus that spin the turbine
fans 16, which are affixed to a shaft (not shown). Generally, there
are at least two turbine fans 16. One or more of the turbine fans
16 engage the same shaft that the compressor 12 engages.
[0034] The gas powered turbine 10 is self-powered since the
spinning of the turbine fans 16 also powers the compressor 12 to
compress air for introduction into the combustion chambers 14.
Other turbine fans 16 are affixed to a second shaft 17 which
extends from the gas powered turbine 10 to power an external
device. After the gases have expanded through the turbine fans 16,
they are expelled out through an exhaust port 18. It will be
understood that the gas powered turbines are used for many
different applications such as engines for vehicles and aircraft or
for power production in a terrestrially based gas powered turbine
10.
[0035] The gases which are exhausted from the gas powered turbine
10 include many different chemical compounds that are created
during the combustion of the atmospheric air in the combustion
chambers 14. If only pure oxygen and pure hydrocarbon fuel, were
combusted, absolutely completely and stoichiometrically, then the
exhaust gases would include only carbon dioxide and water.
Atmospheric air, however, is not 100% pure oxygen and includes many
other compounds such as nitrogen and other trace compounds.
Therefore, in the high energy environment of the combustion
chambers 14, many different compounds may be produced. All of these
compounds exit the exhaust port 18.
[0036] It is generally known in the art that an equivalence ratio
is determined by dividing the actual ratio of fuel and air by a
stoichiametric ratio of fuel to air (where there is not an excess
of one starting material). Therefore, a completely efficient
combustion of pure fuel and oxygen air would equal an equivalence
ratio of one. It will be understood that although atmospheric air
in a hydrocarbon fuel may be preferred for economic reasons other
oxidizers and fuels may be provided. The air simply provides an
oxidizer for the fuel.
[0037] It will be understood that the gas powered turbine 10 may
include more than one combustion chamber 14. Any reference to only
one combustion chamber 14, herein, is for clarity of the following
discussion alone. The present invention may be used with any
oxidizer or fuel which is used to power the gas powered turbine 10.
Moreover, the combustor 14 may combine any appropriate fuel. Air is
simply an exemplary oxidizer and hydrocarbons an exemplary
fuel.
[0038] With reference to FIG. 2, an exemplary combustion chamber 14
is illustrated. The combustion chamber may comprise any appropriate
combustion chamber such as the one described in U.S. patent
application Ser. No. 10/120,268 filed Apr. 10, 2002 entitled, "A
Catalytic Combustor For Substantially Eliminating Nitrous Oxide
Emissions," incorporated herein by reference. The combustion
chamber 14 includes a premix section or area 30, a heat exchange or
pre-heat section 32, generally enclosed in a heat exchange chamber
33, and a main combustion section 34. A first or premix fuel line
36 provides fuel to the premix area 30 through a fuel manifold 37
while a second or main fuel line 38 provides fuel to the main
combustion section 34 through a main injector 52. Positioned in the
premix area 30 is a premix injector 40 which injects fuel from the
first fuel line 36 into a premix chamber or premixer 42. Air from
the compressor 12 enters the premix area 30 through a plurality of
cooling tubes 44 of a heat exchanger or pre-heater 45 (detailed in
FIG. 3). The premix chamber 42 encompasses a volume between the
premix injector 40 and the exit of the cooling tubes 44.
[0039] With further reference to FIG. 2, a plurality of catalytic
heat exchange or catalyst tubes 48 extend into the heat exchange
area 32. The heat exchange tubes 48 are spaced laterally apart. The
heat exchange tubes 48, however, are not spaced vertically apart.
This configuration creates a plurality of columns 49 formed by the
heat exchange tubes 48. Each heat exchange tube 48, and the column
49 as a whole, define a pathway for air to travel through. The
columns 49 define a plurality of channels 50. It will be understood
this is simply exemplary and the tubes may be spaced in any
configuration to form the various pathways. Extending inwardly from
the walls of the heat exchange chamber 33 may be directing fins
(not particularly shown). The directing fins direct the flow of air
to the top and the bottom of the heat exchange chamber 33 so that
air is directed to flow vertically through the channels 50 defined
by the heat exchange tubes 48.
[0040] Near the ends of the heat exchange tubes 48, where the heat
exchange tubes 48 meet the main combustion section 34, is a main
injector 52. The second fuel line 38 provides fuel to the main
injector 52 so that fuel may be injected at the end of each heat
exchange tube 48. Spaced away from the main injector 52, towards
the premix area 30, is an intra-propellant plate 54. The
intra-propellant plate 54 separates the air that is traveling
through the channels 50 and the fuel that is being fed to the fuel
manifold region 56 between the main injector face 52 and
intra-propellant plate 54. It will be understood, that the
intra-propellant plate 54 is effectively a solid plate, though not
literally so in this embodiment. The placement of the heat exchange
tubes 48 dictate that the intra-propellant plate 54 be segmented
wherein one portion of the intrapropellant plate 54 is placed in
each channel 50 between two columns 49.
[0041] Air which exits out the heat exchange tubes 48 is entrained
with fuel injected from an injector port 60 (illustrated more
clearly herein) in the main injector 52 and this fuel then combusts
in the main combustion section 34. The main combustion section 34
directs the expanding gases of the combusted fuel to engage the
turbine fans 16 so that the expanded gases may power the turbine
fans 16.
[0042] Turning reference to FIG. 3, a detailed portion of the heat
exchanger 45 is illustrated. Although, in one embodiment, the heat
exchanger 45 includes a large plurality of tubes, as generally
shown in FIG. 2, only a few of the heat exchange tubes 48 and
cooling tubes 44 are illustrated here for greater clarity. The heat
exchanger 45 is similar to that described in U.S. Pat. No.
5,309,637 entitled "Method of Manufacturing A Micro-Passage Plate
Fin Heat Exchanger", incorporated herein by reference. The heat
exchanger 45 includes a plurality of cooling tubes 44 disposed
parallel to and closely adjacent the heat exchange tubes 48. Each
of the cooling tubes 44 and the heat exchange tubes 48 have a
generally rectangular cross section and can be made of any
generally good thermally conductive material. Preferably, the heat
exchange tubes 48 and the cooling tubes 44 are formed of stainless
steel. It will be appreciated that while the cooling tubes 44 and
the heat exchange tubes 48 are shown as being substantially square,
the cross-sectional shape of the components could comprise a
variety of shapes other than squares. It is believed, however, that
the generally square shape will provide the best thermal transfer
between the tubes 44 and 48.
[0043] Both the cooling tubes 44 and the heat exchange tubes 48 may
be of any appropriate size, but preferably each are generally
square having a width and height of between about 0.04 inches and
about 1.0 inches (between about 0.1 centimeters and about 2.5
centimeters). The thickness of the walls of the cooling tubes 44
and the heat exchange tubes 48 may be any appropriate thickness.
The walls need to be strong enough to allow the fluids to flow
through them, but still allow for an efficient transfer of heat
between the inside of the heat exchange tubes 48 and the air in the
channels 50 and cooling tubes 44. The thickness may also vary by
size and material choice.
[0044] The cooling tubes 44 extend parallel to the heat exchange
tubes 48 for a portion of the length of the heat exchange tubes 48.
Generally, each of the cooling tubes 44 is brazed to one of the
heat exchange tubes 48 for the distance that they are placed
adjacent one another. Moreover, the cooling tubes 44 and the heat
exchange tubes 48 may be brazed to one another. The cooling tubes
44 extend between the columns 49 of the heat exchanger tubes 48.
According to various embodiments, brazing materials are those with
melting temperatures above about 538.degree. C. (about 1000.degree.
F.). The cooling tubes 44 extend between the columns 49 of the heat
exchanger tubes 48. The cooling tubes 44 and the heat exchange
tubes 48, when brazed together, form the heat exchanger 45 which
can provide a surface-to-surface exchange of heat. It will be
understood, however, that air traveling in the channels 50 between
the heat exchange tubes 48 will also become heated due to the heat
transferred from the heat exchange tubes 48 to the air in the
channels 50.
[0045] Referring further to FIG. 3, fuel injector ports 60 are
formed in the main injector 52. The injector ports 60 may be
provided in any appropriate number. According to various
embodiments, there is a ratio of heat exchange tubes 48 to
injectors 60 of at least one. It will be understood, however, that
any appropriate ratio of the injectors 60 to the heat exchange
tubes 48 may be provided. The fuel is provided to the manifold
region 56 which is bound by the intra-propellant plate 54, the main
injector plate 52, and a manifold plate 61. The manifold plate 61
may underlay, overlay, or surround the manifold region 56. This
provides fuel to each of the injector ports 60 without requiring an
individual fuel line to each injector port 60. Therefore, as air
exits each heat exchange tube 48, fuel is injected from the
injector port 60 to the stream of air emitted from each heat
exchange tube 48. In this way, the fuel can be very efficiently and
quickly distributed throughout the air flowing from the heat
exchanger 45, as discussed further herein.
[0046] On the interior walls of each heat exchange tube 48 is
disposed a coating of a catalyst. The catalyst may be any
appropriate catalyst that is able to combust a hydrocarbon fuel,
and may include, for example, platinum, palladium, or mixtures
thereof. The catalyst is able to combust a hydrocarbon fuel, such
as methane, without the presence of a flame or any other ignition
source. The catalyst is also able to combust the fuel without
generally involving any side reactions. Therefore, the combustion
of fuel does not produce undesired products. It will be understood
that if the fuel is not a hydrocarbon then a different, appropriate
catalyst is used. The catalyst allows combustion of the fuel
without an additional heat source.
[0047] With continuing reference to FIGS. 1-3 and further reference
to FIG. 4, a method of using the combustion chamber 14 according to
various embodiments will be described. The combustor 14 includes a
pre-mixer 42 which may be formed in any appropriate manner. The
pre-mixer 42 may include an open region, as illustrated in FIG. 4,
or may include a plurality of the cooling tubes 44, as illustrated
in FIG. 5, and described further herein. When an open region is
used as the pre-mixer 42 the flow generally follows the path
indicated by the arrows in FIG. 4. It will also be understood that
a plurality of tubes, as described above, are present in the heat
exchanger, but have been removed for clarity in the present
description of the air flow. Atmospheric air is compressed in the
compressor 12 and then introduced into the heat exchange chamber 33
at a high pressure. The air that enters the heat exchange chamber
33 is directed by the directing fins to the top and bottom of the
heat exchange chamber 33 so that the air may flow through the
channels 50. The air that enters the heat exchange chamber 33 may
be at a temperature between about 37.degree. C. and about
427.degree. C. (about 100.degree. F. and about 800.degree. F.).
Generally, however, the air enters the heat exchanger 45 at a
temperature of about 204.degree. C. to about 400.degree. C. (about
40020 F. to about 750.degree. F.).
[0048] As the air travels in the channels 50, the air increases in
temperature to become "hot" air. The hot air flows through the
pathway formed by the cooling tubes 44 and into the premix area 30.
The hot air also receives thermal energy while flowing through the
cooling tubes 44. It will be understood that the cooling tubes 44
are adjacent a portion of the heat exchange tubes 48. The
temperature of the hot air, as it enters the premix area 30, is
between about 427.degree. C. and about 538.degree. C. (about
800.degree. F. and about 1000.degree. F.). The air in the premix
area 30 makes a turn within the premix chamber 42. As the air turns
inside the premix chamber 42, the premix injector 40 injects fuel
into the air, entraining the fuel in the air. About 30% to about
60% of all the fuel used to power the gas powered turbine 10 is
entrained in this manner in the premix chamber 42.
[0049] After the air enters the premix chamber 42, it then flows
out through the pathway formed by the heat exchange tubes 48. In
the heat exchange tubes 48, the fuel in the air combusts as it
engages the catalyst which is disposed on the inside walls of the
heat exchange tubes 48. The catalyst may be disposed within the
heat exchange tube 48 in a plurality of ways such as coating by
painting or dipping or by affixing seals to the internal walls. As
the fuel combusts, the temperature of the air rises to between
about 768.degree. C. and 930.degree. C. (between about 1400.degree.
F. and about 1700.degree. F.). As the temperature of the air rises,
it becomes highly energetic to form high energy air, further the
high energy air exits the heat exchange tubes 48. The temperature
the high energy air reaches in the heat exchange tubes 48 is at
least the hypergolic or auto-ignition temperature of the fuel being
used in the gas powered turbine 10. Therefore, the high energy air
that exits the heat exchange tubes 48 is, and may also be referred
to as, hypergolic or auto ignition air. The auto-ignition
temperature of the air is the temperature that the air may be at or
above so that when more fuel is injected into the hypergolic air
the fuel ignites automatically without any other catalyst or
ignition source.
[0050] With reference to FIG. 5, a portion of the premix chamber
42, according to a second embodiment, is illustrated in greater
detail. It is more easily seen that a plurality of the cooling
tubes 44 are stacked vertically to form a cooling tube column 44a.
Each cooling tube 44 and the plurality of cooling tube columns 44a
define a cooling pathway. Therefore, air can enter the combustion
chamber 14, travel through the channels 50, adjacent the heat
exchange tubes 48, and through the cooling pathway defined by each
of the cooling tubes 44. The cooling tubes 44, therefore, include
an inlet 44b. The inlet 44b is where the air enters the cooling
tube 44 from the heat exchange channel 50. The cooling tube inlet
44b defines an inlet area A through which air may travel. The
cooling tube inlet 44b is what allows the air to enter the cooling
tube 44 as it travels to the premix chamber 42. In the premixer 42,
each of the cooling tubes 44 defines a plurality of exit orifices
or ports 46. Each of the exit orifices 46 include an exit area B.
The air traveling through the cooling tubes 44 can exit the exit
orifices 46 to enter the premix areas 42. Each exit orifice area B
is generally smaller than the inlet area A, however, the total area
of all of the exit orifice areas B may be equal to or greater than
the inlet area A. Moreover, each of the cooling tubes 44 preferably
includes a plurality of the exit orifices 46. Therefore, the total
exit orifice area B for each cooling tube 44 is greater than the
inlet area A. The specific ratio will depend upon the operating
conditions, such as temperature or fuel type, for the combustor
14.
[0051] With continuing reference to FIG. 5 and further reference to
FIG. 5A, each of the exit orifices 46 may have a different exit
diameter B. Therefore, a first exit orifice 46a may have a first
exit orifice area Ba while a second exit orifice 46b has a second
orifice area Bb. The exit orifice areas B may be altered to alter
the equivalence ratio of the air to the fuel and may also be used
to directly control the flow of the oxidizer from the cooling tubes
44 out of the exit orifices 46.
[0052] The premix injector 40 includes a plurality of premix fuel
injectors 40a. Once the air exits the exit orifices 46 into the
premix chamber 42, fuel is injected through the premix injector
ports 40a to mix with the air that exits the cooling tubes 44. The
number of premix injector ports 40a will depend upon the particular
application and the fuel chosen to be combusted. Nevertheless, the
ratio of the premix injector port 40a to cooling tubes 44 as
generally between about 0.3 and about 2.5. After the air enters the
premix chamber 42, it then flows out of the premix chamber 42
through the pathway formed by the heat exchange tubes 48.
[0053] Positioned in the pre-mixer 42, according to the second
embodiment is a combustor inhibitor or suppressor. Specifically, a
combustion suppressor is provided to limit or eliminate combustion
of the fuel in the pre-mixer 42 before the fuel reaches the
catalyst tubes 48. Appropriate combustion suppressors includes
coatings to eliminate pre-oxyl radicals from forming or a physical
structure that is at least the quenching distance for the fuel
being injected into the pre-mixer 42. Other appropriate methods may
also be used to inhibit combustion of the fuel before it reaches
the catalyst tubes 48.
[0054] Additional fuel is injected through the main injector 52 as
the air exits the heat exchange tubes 48 and enters the main
combustion section 34. The fuel injected from the main injector 52
is injected through the individual injector ports 60. Any ratio of
injector ports 60 to heat exchange tubes 48 may be used as long as
all of the air exiting the heat exchanger 45 is thoroughly mixed
with fuel. Any additional fuel to power the gas powered turbine 10
is injected at this point, such that fuel is added to the air at
the premix chamber 42 and from the injector ports 60.
[0055] As the air travels through the heat exchange tubes 48, the
fuel that was entrained in the air in the premix chamber 42 is
combusted by the catalyst. This raises the temperature of the air
from the temperature that it enters the heat exchange chamber 33.
In particular, the temperature of the air is raised to generally
between about 700.degree. C. and 880.degree. C. (between about
1300.degree. F. and about 1600.degree. F.). This temperature is
generally the hypergolic temperature so that the fuel combusts
spontaneously when added through the injector port 60. It will be
understood that different fuels have different hypergolic
temperatures. Therefore, the amount of fuel added in the premix
section 42 may be altered to determine the temperature of the air
exiting the heat exchange tubes 48.
[0056] With reference to FIG. 6, the heat exchange tubes 48 extend
from an upstream side 70 through the intra-propellant plate 54 and
terminate into the main injector 52. A face of the injector 52a is
downstream of the heat exchange tubes 48. Fuel is provided through
the main fuel line 38 to the manifold region 56 which is the area
between the intra-propellant plate 54 and the main injector 52.
Although only one main fuel line 38 is illustrated, it will be
understood that more than one main fuel line may be provided.
Formed in the main injector plate 52 are oxidizer passages or
pathways 72 which are extensions of the heat exchange tubes 48
formed in the main injector plate 52. The hypergolic air from the
heat exchange tubes 48 passes through the oxidizer pathways 72 and
exits into the main combustion area 34.
[0057] Extending back from the injector port 60 is a fuel injection
path 74. Each fuel injector port 60 includes at least one fuel
pathway 74. The fuel pathway 74 is preferably a bore formed in the
main injector plate 52 to allow access between the fuel manifold
region 56 so that the fuel which is provided to the fuel manifold
region 56 from the main fuel line 38 can reach the combustion area
34. Generally, the fuel pathways 74 are formed in the main injector
plate 52 and the spaces or lands between the oxidizer pathways 72
which extend from the heat exchange tubes 48.
[0058] The fuel exits the injector ports 60 as a fuel stream 76 in
line with the fuel pathway 74 provided in the main injector plate
52. Preferably, the fuel stream 76 has a half angle of between
about 40.degree. and about 50.degree. and preferably of about
45.degree.. Therefore as two of the fuel streams 76 intersect, in
an area of the combustion chamber 34, which is downstream of the
face 52a of the injector plate 52, the streams intersect at about
an 80.degree. to 100.degree. angle. It will be understood, however,
that the fuel streams 76 may intersect at a slightly different
angle. For example, the fuel streams may intersect at angles
ranging between about 20.degree. and about 150.degree..
[0059] With reference to FIGS. 7a and 7b, a first embodiment of the
fuel injector port 60 is illustrated. The hypergolic air, which
acts as an oxidizer, exits from the oxidizer pathways 72. As this
is happening, fuel exits from the injector ports 60 and is
transmitted along fuel streams 76. Because the two fuel streams 76
are angled, they intersect at a point downstream of the oxidizer
pathways 72 and between the oxidizer pathways 72 in a land region
77. As discussed above, preferably two fuel streams 76 intersect at
an angle of about 90.degree.. When this intersection occurs, the
two fuel streams interrupt each other and produce a fuel plume 80
which spreads into the appropriate oxidizer pathways 72. The fuel
plume 80 is a substantially and finely atomized from the fuel
streams 76 that are spreading out extremely rapidly. This allows
the fuel in the fuel streams 76 to intermix very quickly with the
hypergolic air as it exits the oxidizer pathways 72.
[0060] As discussed above, the air exits the oxidizer pathways 72
at approximately the auto-ignition or hypergolic temperature of the
fuel in the fuel streams 76. Therefore, as soon as the fuel from
the fuel streams 76 is raised to the temperature of the hypergolic
air exiting the oxidizer pathways 72, the fuel ignites. Therefore,
when the fuel mixes substantially completely with the air, as it
exits the oxidizer pathways 72, the entire amount of fuel injected
with the fuel streams 76 ignites at substantially the same time. As
this occurs, the ignition of fuel from the fuel streams 76 across
the face 52a of the injector plate 52 is substantially constant and
equal. Therefore, there are substantially no hot spots created,
thus keeping the temperature of the combustion chamber 34 to one
which allows substantially no nitrous oxide compounds to be
produced.
[0061] Because the fuel in the fuel plume 80 is spreading out so
quickly into the high energy air exiting the oxidizer pathways 72,
the fuel mixes with the hypergolic air and becomes heated to the
hypergolic temperature faster than the ignition or combustion rate
of the fuel. Therefore, substantially all of the fuel that is
injected from the injector port 60 reaches the hypergolic
temperature at the same time. Therefore, substantially all the fuel
combusts at substantially the same time, which substantially
reduces the creation of discrete hot spots.
[0062] With references to FIGS. 8a and 8b, a fuel injector port 90
according to various preferred embodiment of the present invention
is illustrated. With this embodiment, high energy air exits the
main injector 52 through the oxidizer pathways 72. Fuel streams 76
are also produced as fuel exits a plurality of injector ports 90.
The injector ports 90 are not circular, but rather are generally
rectangle in shape having a height of H which substantially greater
than a width W. The height H of the injector port 90 extends
substantially parallel to the height of the oxidizer pathways 72.
Therefore, a fuel stream or fan 92 is produced by the fuel
injectors 90 that is substantially spread out or flattened, as it
exits the injector port 90, as opposed to the fuel stream 76
described previously.
[0063] Fuel may enter the fuel pathway 74 through any appropriately
shaped port but as the pathway 74 nears the injector port 90, the
pathway becomes substantially rectangular having a height H which
is much greater than a width W. With particular reference to FIG.
8b, the upstream side of the main injector plate 52 includes an
inlet port 94, that is substantially circular in shape.
Nevertheless, the injector port 90 is substantially rectangular in
shape. The fuel stream 92 this produces is already substantially
spread out or thinned before it reaches an intersection point with
another fuel stream 92. As two fuel streams 92 intersect, they
produce a fuel plume 96 which allows the fuel provided through the
injector ports 90 to be mixed with the hypergolic air exiting the
oxidizer pathways 72 before the fuel, provided in the fuel streams
92, reaches its ignition temperature.
[0064] This allows a substantial intermixing of the fuel with the
air exiting the oxidizer pathways 72 before the fuel combusts so
that the combustion in the combustion chamber 34, across the face
of 52a of the main injector plate 52, is substantially even. This
generally does not allow hot spots in the combustion area 34 to
form, thereby substantially eliminating the production of NOX
chemicals. It will be appreciated that in this embodiment, opposing
fuel fans 92 are not necessary to provide an appropriate fuel plume
96. Because the injector port 90 produces a fuel fan 92 which is
already substantially spread out and dispersed, the impingement of
two fuel streams is not generally necessary.
[0065] As discussed above, the air that exits the heat exchanger 45
is at the auto-ignition or hypergolic temperature of the fuel used
in the gas powered turbine 10. Therefore, as soon as the fuel
reaches the temperature of the air, the fuel ignites. Since the
fuel is thoroughly mixed with the air, the combustion of the fuel
is nearly instantaneous and will not produce any localized or
discrete hot spots. Because the fuel is so well mixed with the air
exiting the heat exchanger 45, there is no one point or area which
has more fuel than any other point, which could also create hot
spots in the main combustion section 34. Therefore, the temperature
of the air coming from the main injector 52 and into the main
combustion section 34 is substantially uniform. During operation of
the gas powered turbine 10, the fuel's characteristic mixing rate
is shorter than the combustion rate of the fuel.
[0066] The temperature of the air, after the additional fuel has
been combusted from the main injector 52, is between about
1315.degree. C. and 1595.degree. C. (about 2400.degree. F. and
about 2800.degree. F.). Preferably, the temperature, however, is
not more than about 1426.degree. C. (about 2600.degree. F.).
Different fuel to air ratios may be used to control the temperature
in the main combustion section 34. The main combustion section 34
directs the expanding gases into a transition tube (not shown) so
that it engages the turbine fans 16 in the turbine area 15 at an
appropriate cross sectional flow shape.
[0067] The use of the heat exchanger 45 raises the temperature of
the air to create hot or heated air. The hot air allows the
catalyst to combust the fuel that has been entrained in the air in
the premix chamber 42 without the need for any other ignition
sources. The catalyst only interacts with the hydrocarbon fuel and
the oxygen in the air to combust the fuel without reacting or
creating other chemical species. Therefore, the products of the
combustion in the heat exchange tubes 48 are substantially only
carbon dioxide and water due to the catalyst placed therein. No
significant amounts of other chemical species are produced because
of the use of the catalyst. Also, the use of the heat exchange
tubes 48, with a catalyst disposed therein, allows the temperature
of the air to reach the auto-ignition temperature of the fuel so
that no additional ignition sources are necessary in the main
combustion section 34. Therefore, the temperature of the air does
not reach a temperature where extraneous species may be easily
produced, such as NOX chemicals. Due to this, the emissions of the
gas powered turbine 10 of the present invention has virtually no
NOX emissions. That is, that the NOX emissions of the gas powered
turbine 10 according to the present invention are generally below
about 1 part per million volume dry gas.
[0068] Also, the use of the heat exchanger 45 eliminates the need
for any other pre-burners to be used in the gas powered turbine 10.
The heat exchanger 45 provides the thermal energy to the air so
that the catalyst bed is at the proper temperature. Because of
this, there are no other areas where extraneous or undesired
chemical species may be produced. Additionally, the equivalence
ratio of the premix area is generally between about 0.20 and 0.30,
while the equivalence ratio of the main injector 52 is between
about 0.50 and about 0.60. This means that the fuel combustion will
occur as a lean mixture in both areas. Therefore, there is never an
excessive amount of fuel that is not combusted. Also, the lean
mixture helps to lower temperatures of the air to more easily
control side reactions. It will be understood that different fuel
ratios may be used to produce different temperatures. This may be
necessary for different fuels.
[0069] With reference to FIG. 9, a detail portion of the combustor
14, similar to the portion illustrated in FIG. 3, according to
various embodiments of a heat exchanger 145 is illustrated. A
premix chamber 142 allows air from the compressor to be mixed with
a first portion of fuel. Air comes from the compressor and travels
through a cooling fin 144 rather than through a plurality of
cooling tubes 44, as discussed above in relation to the first
embodiment. It will be understood that exit ports may also be
formed in the cooling fins 144 to form the premix area 142. The
cooling fin 144 is defined by two substantially parallel plates
144a and 144b. It will be understood, however, that other portions,
such as a top and a bottom will be included to enclose the cooling
fin 144. Additionally, a heat exchange or catalyst fin 148 is
provided rather than heat exchange tubes 48, as discussed above in
the first embodiment. Again, the catalyst fin 148 is defined by
side, top, and bottom walls and defines a column 149. Each catalyst
column 149, however, is defined by a single catalyst fin 148 rather
than a plurality of catalyst tubes 48, as discussed above. The
cooling fin 144 may include a plurality of cooling fins 144. Each
cooling fin 144, in the plurality, defines a cooling pathway.
Similarly, the heat exchange fin 148 may include a plurality of
heat exchange 148 fins. Each, or the plurality of, the heat
exchange fins 148 defines a heat exchange or catalyst pathway.
[0070] Channels 150 are still provided between each of the catalyst
fins 148 so that air may flow from the compressor through the
cooling fins 144 into the premix chamber 142. Air is then premixed
with a first portion of fuel and flows back through the catalyst
fins 148 to the main injector plate 152. Injection ports 160 are
provided on the main injector plate 152 to inject fuel as the air
exits the catalyst fin 148. A suitable number of injection ports
160 are provided so that the appropriate amount of fuel is mixed
with the air as it exits the catalyst fins 148. An intra-propellant
plate 54 is also provided.
[0071] Injector ports 60 or 90 are still provided on the main
injector plate 152 to provide fuel streams 76 or 92 as heated air
exits the oxidizer paths (not particularly shown) from the catalyst
fins 148. Either of the previously described injector ports 60 or
90 may be used with the second embodiment of the heat exchanger 145
to provide a substantial mixing of the fuel with the air as it
exits the catalyst fins 148. This still allows a substantial
mixture of the fuel with the air as it exits the catalyst fins 148
before the fuel is able to reach its ignition temperature.
Therefore, the temperatures across the face of the main injector
152 and in the combustion chamber 34 are still substantially
constant without any hot spots where NOX chemicals might be
produced.
[0072] It will also be understood that the cooling fins 144 may
extend into the pre-mixer 142 similar to the cooling tubes 44. In
additional ports may be formed in the portion of the cooling fins
144 extending into the pre-mixer to all the air to exit the cooling
fins and mix with a first portion of fuel. Therefore, the combustor
according to the second embodiment may include a pre-mixer 142
substantially similar to the pre-mixer illustrated in FIG. 5, save
that the ports are formed in the cooling fins 144 rather than
individual cooling tubes 44. In addition, this alternative
embodiment may include a combustion inhibitor to assist in
eliminating combustion in the pre-mixer 142.
[0073] It will be further understood that the heat exchanger,
according to the present invention, does not require the use of
individually enclosed regions or modular portions. Rather the heat
exchanger may be formed of a plurality sheets, such as corrugated
sheets. A first set of these sheets are oriented relative to one
another to form a plurality of columns. The first set of sheets
include a catalyst coated on a side facing an associated sheet,
such that the interior of the column includes the catalyst to
contact the airflow. In this way, the catalyst need not be coated
on the interior of a closed space, but rather the space is formed
after the catalyst is coated to form the catalyst pathway.
Operatively associate with the first set of sheets is a second set
of sheets, defining a second set of columns disposed at least
partially between the first set of columns. Thus, in a manner
similar the heat exchanger 145, heat exchange columns and cooling
columns are formed. These then form the catalyst pathway and the
cooling pathway in operation of the combustor.
[0074] The present invention thus provides an apparatus and method
that virtually or entirely eliminates the creation of NOX
emissions. Advantageously, this is accomplished without
significantly complicating the construction of the gas powered
turbine 10 or the combustors 14.
[0075] The description of the invention is merely exemplary in
nature and, thus, variations that do not depart from the gist of
the invention are intended to be within the scope of the invention.
Such variations are not to be regarded as a departure from the
spirit and scope of the invention.
* * * * *