U.S. patent application number 12/774576 was filed with the patent office on 2010-11-11 for apparatus and methods for providing uniformly volume distributed combustion of fuel.
This patent application is currently assigned to GENERAL VORTEX ENERGY, INC.. Invention is credited to Anatoli Borissov.
Application Number | 20100285413 12/774576 |
Document ID | / |
Family ID | 43050459 |
Filed Date | 2010-11-11 |
United States Patent
Application |
20100285413 |
Kind Code |
A1 |
Borissov; Anatoli |
November 11, 2010 |
Apparatus and Methods For Providing Uniformly Volume Distributed
Combustion of Fuel
Abstract
A combustor apparatus and method for the combustion of viscous
fuels are provided. The combustor apparatus can include a
precombustion chamber particularly adapted to heat and at least
partially combust a heavy primary fuel, and a main combustion
chamber adapted to combust the primary fuel uniformly through the
main combustion chamber (in flameless mode). The precombustion
chamber can include at least one air injection inlet port
positioned to induce a first stage vortex in the main body portion
of the housing of the precombustion chamber. Further, the
precombustion chamber can be interfaced with a main combustion
chamber to induce a second stage vortex within the main combustion
chamber. The main combustion chamber can have an extended axial
length in order to accommodate heavier fuels that require
additional time to sufficiently combust (oxidize) within the
combustion chamber.
Inventors: |
Borissov; Anatoli; (Sugar
Land, TX) |
Correspondence
Address: |
The Amatong Law Firm, PLLC;ALBERTO Q. AMATONG, JR.
P.O. BOX 70889
HOUSTON
TX
77270-0889
US
|
Assignee: |
GENERAL VORTEX ENERGY, INC.
Missouri City
TX
|
Family ID: |
43050459 |
Appl. No.: |
12/774576 |
Filed: |
May 5, 2010 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61176006 |
May 6, 2009 |
|
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|
Current U.S.
Class: |
431/7 ; 110/230;
431/185; 431/8 |
Current CPC
Class: |
F23C 2900/99001
20130101; F23C 5/32 20130101; F23C 6/04 20130101; Y02E 20/342
20130101; Y02E 20/34 20130101 |
Class at
Publication: |
431/7 ; 110/230;
431/185; 431/8 |
International
Class: |
F23G 5/027 20060101
F23G005/027; F23D 11/36 20060101 F23D011/36; F23D 11/10 20060101
F23D011/10; F23G 5/16 20060101 F23G005/16 |
Claims
1. An apparatus for providing flameless combustion of a viscous
fuel, the apparatus comprising: a precombustion chamber adapted to
heat and at least partially combust a primary fuel, the
precombustion chamber including: an outer housing having an
enclosed proximal end portion, an open distal end portion, and a
substantially hollow main body portion extending therebetween and
substantially enclosing a precombustion chamber cavity, at least
one air injection inlet port extending through the main body
portion of the outer housing and positioned to inject combustion
air into the precombustion chamber, the at least one air injection
inlet port further positioned to induce a first stage vortex in the
main body portion of the housing of the precombustion chamber, at
least one primary fuel nozzle positioned to inject the primary fuel
into the precombustion chamber, an igniter fuel nozzle positioned
to inject ignition fuel into the precombustion chamber, and a
hollow cylindrical combustion stabilizer positioned within the
precombustion chamber cavity to receive igniter fuel and primary
fuel and to isolate the primary fuel from a portion of the
combustion air when being heated with the igniter fuel, and having
a proximal end portion, a distal end portion, and a main body
portion extending between the proximal end portion and the distal
end portion, the combustion stabilizer main body portion comprising
a large diameter sidewall spaced radially inward from the
precombustion chamber housing to define an annulus therebetween and
having at least one air inlet aperture extending therethrough to
receive a portion of the combustion air to thereby supply oxygen to
the igniter fuel and to thereby initiate oxidation of the fuel
within the combustion stabilizer, the distal end portion in fluid
communication with the combustion stabilizer main body portion and
having a small diameter sidewall having a diameter substantially
smaller than the large diameter sidewall of the main body, the
distal end portion of the combustion stabilizer further having an
unobstructed distal end aperture for expelling heated primary fuel
into the precombustion chamber cavity adjacent to the distal end
portion of the precombustion chamber housing; and a main combustion
chamber adapted to combust the primary fuel, the main combustion
chamber including: a housing having an at least partially enclosed
proximal end portion including an exhaust aperture, an enclosed
distal end portion, and an elongate main body extending
therebetween and substantially enclosing a main combustion chamber
cavity, the main body having an inner main body diameter and having
a main body axial length extending at least approximately twice the
main body diameter, the main body axial length having a preselected
value preselected to provide a sufficient pyrolyzed fuel travel
distance within the main combustion chamber based upon one or more
fuel performance characteristics of the primary fuel to provide
substantially complete pyrolization thereof, an exhaust-inlet
located adjacent the proximal end portion of the main combustion
chamber housing and extending through the main body of the main
combustion chamber housing, and positioned to receive the at least
partially combusted primary fuel from the precombustion chamber and
to induce a second stage vortex within the main body of the main
combustion chamber housing, and a combustion exhaust tube extending
from and interfaced with the proximal end portion of the main
combustion chamber housing and extending coaxially along a same
longitudinal axis as the main combustion chamber housing, and
having an open distal end portion and an elongate main body
extending between the open distal end portion of the combustion
exhaust tube and the proximal end portion of the main combustion
chamber housing, the distal end portion of the combustion exhaust
tube extending axially within the main combustion chamber cavity to
a location between a position distally forward of an axial midpoint
position of the elongate main body of the main combustion chamber
housing and a position located axially a distance of at least one
exhaust tube main body diameter from the distal end portion of the
main combustion chamber housing.
2. An apparatus as defined in claim 1, wherein the primary fuel is
viscous at ambient supply temperature, the apparatus further
comprising a primary fuel supply system to provide the primary
viscous fuel for combustion, the primary fuel supply system
including: a compressed gas injector connected to a portion of the
primary fuel supply system to form at least a suspension to thereby
minimize a size of fuel droplets exiting the at least one primary
fuel nozzle; a temperature sensor positioned to detect an exhaust
gas temperature of the exhaust gas exiting the combustion exhaust
tube; and a logic circuit positioned to control a flow of the
igniter fuel into the precombustion chamber responsive to the
exhaust gas temperature of the exhaust gas exiting the combustion
exhaust tube.
3. An apparatus as defined in claim 1, wherein a diameter of the
second stage vortex is substantially larger than the diameter of
the first stage vortex.
4. An apparatus as defined in claim 1, wherein the pre-combustion
chamber housing has an axial length to main body cross-sectional
diameter ratio of between 2.5:1 to 4:1; and wherein the combustion
air to mass flow of the primary fuel has a ratio of between 35:1 to
45:1.
5. An apparatus as defined in claim 1, wherein the combined airflow
rate of the combustion air entering the precombustion chamber is
set based upon predetermined ratios of momentum and mass flow of
primary fuel for a given fuel flow rate defining an air-fuel flow
to thereby enhance instability of the air-fuel flow.
6. An apparatus as defined in claim 1, wherein the primary fuel is
glycerin; wherein the housing of the pre-combustion chamber is of a
substantially cylindrical shape; wherein the housing of the main
combustion chamber is of a substantially cylindrical shape; wherein
the combustion exhaust tube has a configuration comprising one or
more of the following: a cylindrical shape and a venturi shape; and
wherein the combined airflow rate of the air exiting the at least
one air inlet port and mass flow of primary fuel entering the
precombustion chamber has a ratio between 20:1 to 40:1 to thereby
enhance instability of the air-fuel flow.
7. An apparatus as defined in claim 1, wherein the primary fuel is
glycerin; and wherein a shape of the main body of the main
combustion chamber housing is configured to provide a uniform
temperature and pressure distribution inside of the main combustion
chamber cavity and to optimize a pressure drop adjacent the open
distal end portion of the combustion exhaust tube.
8. An apparatus as defined in claim 1, wherein the primary fuel is
glycerin; wherein the main combustion chamber cavity has an axial
length to main body cross-sectional diameter ratio of between 4:1
to 6:1; and wherein the combustion exhaust tube has an axial offset
distance from the distal end portion of the housing of the main
combustion chamber-to-combustion exhaust tube cross-sectional
diameter ratio of between approximately 1.5:1 to 2.5:1.
9. An apparatus as defined in claim 1, wherein the main combustion
chamber housing further includes an annulus extending between the
proximal end and distal end portions of the housing; and wherein
the distal end portion of the main combustion chamber housing
includes a passageway extending from and in communication with the
annulus and a plurality of swirl nozzles positioned to supply a
cooling fluid to a portion of the cavity of the housing adjacent
the distal end of the combustion exhaust tube, the cooling fluid
including oxygen and trapped fuel film extracted from within the
cavity adjacent the proximal end portion of the housing, the
nozzles oriented to enhance instability of the fuel flow adjacent
the distal end of the combustion exhaust tube.
10. An apparatus as defined in claim 1, wherein the main combustion
chamber further comprises a perforated liner secured to interior
surfaces of the outer housing, inner bottom wall and inner top
wall, the portion of the liner adjacent the inner bottom wall and
inner top wall having an arc configured to provide constant vortex
radial velocity conditions to thereby provide minimal hydrodynamic
losses and to thereby confine unvaporized fuel droplets in
equilibrium in an orbit of rotation of the second stage vortex
stream; wherein the apparatus further comprises: a cooling air
supply system to provide a fluid to cool inner surfaces of the main
combustion chamber housing and to provide the fluid to the
plurality of swirl nozzles to thereby enhance instability of the
fuel flow adjacent the distal end of the combustion exhaust tube,
and a recirculation passageway extending between the proximal end
and distal end portions of the housing positioned to return trapped
fuel film received from a portion of the cavity of the housing
adjacent the proximal end of the combustion exhaust tube; and
wherein the at least partially enclosed proximal end portion of the
main combustion chamber housing includes an annular raised lip ring
extending into the recirculation passageway and configured to cause
a venturi effect within the recirculation passageway.
11. An apparatus for providing flameless combustion of a fuel, the
apparatus comprising a main combustion chamber adapted to combust a
primary fuel, the main combustion chamber including: a housing
having a proximal end portion including an exhaust aperture, a
distal end portion, and an elongate main body extending
therebetween and substantially enclosing a main combustion chamber
cavity, the main body having an inner main body diameter and having
a main body axial length; and an exhaust-inlet extending through
the main body of the main combustion chamber housing at an inlet
location, and positioned to receive at least partially combusted
primary fuel from a precombustion chamber and to induce a vortex
within the main body of the main combustion chamber housing, the
main body axial length extending distally from the inlet location a
distance approximately equal to or greater than a value of the
inner main body diameter.
12. An apparatus as defined in claim 11, wherein the main body
axial length has a preselected value preselected to provide a
sufficient pyrolyzed fuel travel distance from the exhaust-inlet
within the main combustion chamber cavity based upon one or more
fuel performance characteristics of the primary fuel to provide
substantially complete pyrolization thereof.
13. An apparatus as defined in claim 11, wherein the main
combustion chamber further comprises: a combustion exhaust conduit
extending from and interfaced with the proximal end portion of the
main combustion chamber housing and extending coaxially along a
same longitudinal axis as the main combustion chamber housing, and
having an open distal end portion and an elongate main body
extending between the open distal end portion of the combustion
exhaust conduit and the proximal end portion of the main combustion
chamber housing, the distal end portion of the combustion exhaust
conduit extending within the main combustion chamber cavity to a
location between a position distally forward of an axial midpoint
position of the elongate main body of the main combustion chamber
housing and a position axially adjacent to the distal end portion
of the main combustion chamber housing, an axial spacing of the
distal end portion of the combustion exhaust conduit from an inner
surface of the distal end portion of the main combustion chamber
housing having a value approximately equal to or greater than that
of the inner diameter of the distal end portion of the exhaust
conduit main body.
14. An apparatus as defined in claim 13, wherein the exhaust-inlet
is positioned normal to an inner surface portion of the main body
of the main combustion chamber housing adjacent thereto; and
wherein an outer surface of the combustion exhaust conduit includes
a swirl enhancer comprising at least one of the following: a spiral
recess extending along a substantial portion of the longitudinal
length thereof, or a spiral protuberance extending along the
substantial portion of the longitudinal length thereof, to thereby
enhance the inducement of the vortex within the main body of the
main combustion chamber housing.
15. An apparatus as defined in claim 13, wherein the main body of
the main combustion chamber housing has an axial length to main
body cross-sectional inner diameter ratio of between approximately
4:1 to 6:1; and wherein the distal end portion of the combustion
exhaust conduit has an axial offset distance from the distal end
portion of the housing of the main combustion chamber to combustion
exhaust conduit distal end portion cross-sectional diameter ratio
of between approximately 5:1 to 2.5:1.
16. An apparatus as defined in claim 11, wherein the vortex is a
second stage vortex, the apparatus further comprising a
precombustion chamber adapted to heat and at least partially
combust the primary fuel, the precombustion chamber including: a
housing having a proximal end portion, an open distal end portion,
and a substantially hollow main body portion extending therebetween
and having a substantially cylindrical inner surface substantially
enclosing a precombustion chamber cavity; and at least one air
injection inlet port extending through the main body portion of the
precombustion chamber housing and positioned to inject combustion
air into the precombustion chamber, the at least one air injection
inlet port further positioned to induce a first stage vortex in the
main body portion of the housing of the precombustion chamber.
17. An apparatus as defined in claim 11, further comprising a
precombustion chamber adapted to heat and at least partially
combust the primary fuel, the precombustion chamber including: a
housing having a proximal end portion, an open distal end portion,
and a substantially hollow main body portion extending therebetween
and ,substantially enclosing a precombustion chamber cavity; at
least one primary fuel nozzle positioned to inject primary fuel
into the precombustion chamber; an igniter fuel nozzle positioned
to inject ignition fuel into the precombustion chamber; and a
hollow combustion stabilizer positioned within the precombustion
chamber cavity to receive the igniter fuel and the primary fuel and
to isolate the primary fuel from a portion of the combustion air
when being initially heated with the igniter fuel, and having a
proximal end portion, a distal end portion, and a main body portion
extending between the proximal end portion and the distal end
portion, the combustion stabilizer main body portion comprising a
large diameter sidewall spaced radially inward from the
precombustion chamber housing to define an annulus therebetween and
having at least one air inlet aperture extending therethrough to
receive a portion of the combustion air to thereby supply oxygen to
the igniter fuel and to thereby initiate oxidation of the fuel
within the combustion stabilizer, the distal end portion of the
combustion stabilizer in fluid communication with the combustion
stabilizer main body and having a small diameter sidewall having a
diameter substantially smaller than the large diameter sidewall of
the main body, the distal end portion further having an
unobstructed distal end aperture for expelling heated primary fuel
into the precombustion chamber cavity adjacent to the distal end
portion of the precombustion chamber housing.
18. An apparatus as defined in claim 17, wherein a diameter of the
second stage vortex is substantially larger than the diameter of
the first stage vortex.
19. An apparatus as defined in claim 17, wherein the primary fuel
is viscous at ambient supply temperature, the apparatus further
comprising a primary fuel supply system to provide the primary
viscous fuel for combustion, the primary fuel supply system
including: a compressed gas injector connected to a portion of the
primary fuel supply system to form at least a suspension to thereby
minimize a size of fuel droplets exiting the at least one primary
fuel nozzle; a temperature sensor positioned to detect an exhaust
gas temperature of the exhaust gas exiting the combustion exhaust
conduit; and a logic circuit configured to control a flow of the
igniter fuel into the precombustion chamber responsive to the
exhaust gas temperature of the exhaust gas exiting the combustion
exhaust conduit.
20. An apparatus as defined in claim 17, wherein the pre-combustion
chamber housing has an axial length to main body cross-sectional
diameter ratio of between 2.5:1 to 4:1; wherein the combustion air
to mass flow of the primary fuel has a ratio of between 30:1 to
50:1; and wherein the combined airflow rate of the combustion air
entering the precombustion chamber is set based upon predetermined
ratios of momentum and mass flow of primary fuel for a given fuel
flow rate defining an air-fuel flow to thereby enhance instability
of the air-fuel flow.
21. A method of providing flameless combustion of a viscous fuel,
the method comprising the steps of: inducing a first stage vortex
in a primary fuel-air mixture within a main body portion of a
precombustion chamber of a flameless combustor; receiving the
primary fuel-air mixture having the first stage vortex induced
state within a main body of a main combustion chamber of the
flameless combustor; and inducing a second stage vortex in the
received primary fuel-air mixture to form a complex vortex pattern
to thereby enhance flameless oxidation of the primary fuel within
the main body of the main combustion chamber, a diameter of the
first stage vortex being substantially smaller than a diameter of
the second stage vortex.
22. A method as defined in claim 21, wherein the step of inducing a
second stage vortex includes expelling the primary fuel-air mixture
tangentially into the main combustion chamber cavity through a
precombustion chamber exhaust outlet; and wherein the precombustion
chamber exhaust outlet is axially spaced apart from the combustion
exhaust conduit inlet a preselected value preselected to provide a
sufficient pyrolyzed fuel travel distance from the precombustion
chamber exhaust outlet within the main combustion chamber cavity
based upon one or more fuel performance characteristics of the
primary fuel to provide substantially complete pyrolization
thereof.
23. A method as defined in claim 22, wherein the primary fuel is a
glycerol fuel, the method further comprising the step of:
preselecting the value of the axial separation between the
precombustion chamber exhaust outlet and the combustion exhaust
conduit inlet to provide the sufficient pyrolyzed fuel travel
distance from the exhaust-inlet port within the main combustion
chamber cavity responsive to one or more fuel performance
characteristics of the glycerol fuel.
24. A method as defined in claim 21, further comprising the steps
of: interfacing a precombustion chamber with the main combustion
chamber, the precombustion chamber adapted to heat and at least
partially combust the primary fuel; igniting a secondary fuel
within the precombustion chamber adjacent a flowpath of the primary
fuel to at least partially combust the primary fuel within the
precombustion chamber of the flameless combustor; sensing a
temperature of the exhaust gas exiting the combustion exhaust
conduit of the main combustion chamber; and controlling a flow of
the secondary fuel into the precombustion chamber responsive to the
exhaust gas temperature of the exhaust gas exiting the combustion
exhaust conduit.
25. A method as defined in claim 21, further comprising the steps
of: interfacing a precombustion chamber with the main combustion
chamber, the precombustion chamber adapted to heat and at least
partially combust the primary fuel; and aerating the primary fuel
prior to entry into the precombustion chamber to minimize a size of
fuel droplets entering the precombustion chamber.
26. A method as defined in claim 21, further comprising the steps
of: providing a main vortex combustion chamber of a flameless
combustor having a main body substantially enclosing a main
combustion chamber cavity, the main combustion chamber cavity
having an axial length approximately equal to or greater than an
inner diameter of the main combustion chamber cavity; and providing
a combustion exhaust conduit within and axially coincident with the
main combustion chamber cavity, the combustion exhaust conduit
having an inlet positioned at a location between an axial position
distally forward of an axial midpoint position of the elongate main
body of the main combustion chamber housing and an axial position
within the main combustion chamber cavity adjacent the distal end
portion of the main combustion chamber housing, an axial spacing of
the distal end portion of the combustion exhaust conduit from an
inner surface of the distal end portion of the main combustion
chamber housing having a value approximately equal to or greater
than that of the inner diameter of the distal end portion of the
exhaust conduit.
27. A method of providing flameless combustion of a viscous fuel,
the method comprising the steps of: providing a main vortex
combustion chamber of a flameless combustor having a main body
substantially enclosing a main combustion chamber cavity, the main
combustion chamber cavity having an axial length approximately
equal to or greater than an inner diameter of the main combustion
chamber cavity; and inducing flameless oxidation of a primary fuel
within the main combustion chamber cavity, the step of inducing
flameless oxidation comprising the step of inducing a vortex within
the main combustion chamber cavity to enhance formation of a fuel
air mixture.
28. A method as defined in claim 27, wherein the main body (101) is
an elongate main body (101), the method further comprising the step
of providing a combustion exhaust conduit within and axially
coincident with the main combustion chamber cavity, the combustion
exhaust conduit having an inlet positioned at a location between an
axial position distally forward of an axial midpoint position of
the main body of the main combustion chamber housing and an axial
position within the main combustion chamber cavity adjacent the
distal end portion of the main combustion chamber housing, an axial
spacing of the distal end portion of the combustion exhaust conduit
from an inner surface of the distal end portion of the main
combustion chamber housing having a value approximately equal to or
greater than that of the inner diameter of distal end portion of
the exhaust conduit.
29. A method as defined in claim 27, further comprising the step
of: injecting the primary fuel into the main combustion chamber
cavity through a precombustion chamber exhaust outlet, the
precombustion chamber exhaust outlet axially spaced apart from the
combustion exhaust conduit inlet a preselected value preselected to
provide a sufficient pyrolyzed fuel travel distance from the
precombustion chamber exhaust outlet within the main combustion
chamber cavity based upon one or more fuel performance
characteristics of the primary fuel to provide substantially
complete pyrolization thereof.
30. A method as defined in claim 29, wherein the primary fuel is a
glycerol fuel, the method further comprising the step of:
preselecting the value of the axial separation between the
precombustion chamber exhaust outlet and the combustion exhaust
conduit inlet to provide the sufficient pyrolyzed fuel travel
distance from the precombustion chamber exhaust outlet within the
main combustion chamber cavity responsive to one or more fuel
performance characteristics of the glycerol fuel.
31. A method as defined in claim 27, further comprising the steps
of: interfacing a precombustion chamber with the main combustion
chamber, the precombustion chamber adapted to heat and at least
partially combust the primary fuel; igniting a secondary fuel
within the precombustion chamber adjacent a flowpath of the primary
fuel to at least partially combust the primary fuel within the
precombustion chamber of the flameless combustor; sensing a
temperature of the exhaust gas exiting the combustion exhaust
conduit of the main combustion chamber; and controlling a flow of
the igniter fuel into the precombustion chamber responsive to the
exhaust gas temperature of the exhaust gas exiting the combustion
exhaust conduit.
32. A method as defined in claim 31, wherein the induced vortex in
the main combustion chamber is the second stage vortex, the method
further comprising the step of: inducing a first stage vortex in a
precombustion chamber of a flameless combustor to form a complex
vortex pattern, a diameter of the first stage vortex being
substantially smaller than a diameter of the second stage
vortex.
33. A method as defined in claim 27, further comprising the steps
of: interfacing a precombustion chamber with the main combustion
chamber, the precombustion chamber adapted to heat and at least
partially combust the primary fuel; and aerating the primary fuel
prior to entry into the precombustion chamber to minimize a size of
fuel droplets entering the precombustion chamber.
34. A method as defined in claim 28, further comprising the step
of: selecting a shape of the main body of the main combustion
chamber that provides a substantially uniform temperature and
pressure distribution inside at least a substantial portion of the
main chamber and that substantially optimizes a pressure drop
adjacent the inlet of the combustion exhaust conduit.
Description
RELATED APPLICATIONS
[0001] This non-provisional application claims priority to and the
benefit of U.S. Patent Application No. 61/176,006, filed May 6,
2009, titled "Apparatus and Methods for Providing Uniformly Volume
Distributed Combustion of Fuel," incorporated herein by reference
in its entirety.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to fuel combustion processes
and apparatus, and specifically to apparatus for providing
uniformly volume distributed combustion and related methods.
[0004] 2. Description of Related Art
[0005] It was arguably not until the late 1970s and early 1980s, as
a result of the first and the second energy crisis, that research
and development activities began to seriously focus on improving
energy efficiency. Similarly, it has only been since until after
such time period that industry has truly recognized the need for
eliminating noxious pollutants such as nitrogen oxides, mostly due
to concerns over human health and concern for the environment. As a
result, although uniformly distributed (flameless) combustion was
discovered circa 1911, it was not until recently that uniformly
distributed combustion (flameless oxidation) has become a focus of
industrial research.
[0006] In flameless combustion, ignition occurs and progresses with
generally no visible or audible signs of a flame usually associated
with burning. As early as 1989, it was found that combustion in a
furnace could be sustained even in an extremely low concentration
of oxygen, if the combustion air was sufficiently preheated.
Particularly, during experiments with a self-recuperative burner,
it was observed that at furnace combustion temperatures of about
1000.degree. C. and an air preheat temperature of about 650.degree.
C., no flame was visible and no ultraviolet signal was detected.
Nevertheless, the fuel was substantially combusted "burnt," and the
carbon monoxide content and nitric oxide of the exhaust was found
to be extremely low.
[0007] Conventionally, to initiate flameless combustion, preheated
oxidizing air and fuel gas is fed into a combustion chamber at
relatively high injection speeds. The geometry of the combustion
chamber, as well as the injection speed of the fuel-air mixture,
create large internal recirculations of the combustion mixture.
Once the recirculations are sufficient, the combustion becomes
distributed throughout the volume of the combustion chamber and the
flame will no longer be visible. Further, as an application of such
principle, nitric oxide emission can be reduced by dilution of the
combustion air with recirculated burned gas in the furnace.
Dilution of the combustion air can reduce the oxygen content of the
oxidizer, which decreases temperature fluctuations in the
combustion chamber as well as the mean temperature, hence, a
resultantly low amount of nitric oxide emission.
[0008] Recognizing the potential benefits of flameless combustion,
the industry has attempted to develop various types of combustion
chambers that support flameless combustion. For example, U.S. Pat.
No. 6,796,789 by Gibson et al. titled Method to Facilitate
Flameless Combustion Absent Catalyst or High-Temperature Oxidant"
describes and oval-shaped combustion chamber configured to
recirculate fuel gas with flue gas and combustible air. U.S. Pat.
No. 5,340,020 by Manus et al. Titled "Method and Apparatus for
Generating Heat by Flameless Combustion of a Fuel in a Gas Flow"
describes a combustion apparatus, which utilizes a catalyst for
producing the flameless combustion.
[0009] U.S. Pat. No. 5,839,270 by Jirnov et al., titled
"Sliding-Blade Rotary Air-Heat Engine with Isothermal Compression
of Air" describes a particularly effective combustion chamber
originally configured for use with the sliding-blade rotary
air-heat engine. The Jirnov "vortex" combustion combined with a
straight-flow precombustion chamber successfully solved problems
associated with operating on multi-fuels with a high completeness
of combustion over the wide range of the coefficient of air
redundance, while producing a substantial drop in toxicity of the
exhaust gases. The combustor was also characterized by providing a
simplified combustor design and ease of fabricating, high thermal
and volumetric efficiency, while being able to employ a variety of
types of combustible hydrocarbon gas or liquid fuels. The vortex
combustor provided a vortex chamber positioned at the tube inlet
and ejectors with feedback loops positioned along the length of the
heat transfer section. This enabled the results to he increased by
inducing a swirl flow and intensive recirculation of fluid all
along the length of the heat transfer section. A precombustion
chamber was provided to form a super-rich fuel and air mixture,
ignition, partial combustion and pyrolyzation of heavy and low
grade fuels. In operation with the Jirnov engine, prior to entering
the precombustion chamber the combustion air was first preheated by
exhaust gases. Upon entry, heating coils in the precombustion
chamber then further heated the air and heated fuel also injected
into the precombustion chamber prior to entry into the main vortex
combustion chamber. The entry of the fuel-air mixture into the main
vortex combustion chamber was such that a very large swirl was
created which helped ensure proper mixture and a substantially
uniform combustion within the combustion chamber.
[0010] In recent years, due to the cost of fuel and due to concern
for the environment, there has been a high interest in the use of
biofuels. Biofuels can include solid, liquid, or gas fuel derived
from recently expired biological material. Biofuel can be produced
from theoretically any biological carbon source, the most common of
which include plants and plant-derived materials. The biofuel
industry is expanding in Europe, Asia and the Americas. The most
common use for biofuels is as liquid fuels for automotive
transport. There is also, however, a desire in industry to use
biofuel to generate steam at and/or electricity. Biodiesel is the
most common biofuel in Europe, and is becoming more popular in Asia
and America. Biodiesel can be produced from oils or fats, for
example, using transesterification of vegetable oil, and forms into
a liquid similar in composition to petroleum diesel.
[0011] Biodiesel production can result in glycerol (glycerin) as a
by-product; for example, at one part glycerol for every 10 parts
biodiesel. This has resulted in a glut in the market for glycerol.
Accordingly, rather than being able to sell the glycerol, many
companies have to pay for its disposal. Sources indicate that the
2006 levels of glycerol production were at about 350,000 tons per
annum in the USA, and 600,000 tons per annum in Europe. Sources
further indicate that such levels will only increase as biodiesel
becomes more popular as a homegrown energy source and as Europe
implements EU directive 2003/30/EC, which requires replacement of
5.75% of petroleum fuels with biofuel, across all member states by
2010. Recognized, therefore, by the inventor is the need for and
apparatus and methods of economically disposing of glycerin or
other in an environmentally friendly and energy efficient
manner.
[0012] Also recognized by the inventor is that, although considered
a waste product of biodiesel fuel production, waste fuels, such as
glycerin, have significant energy delivery potential. Glycerin,
however, along with some other forms of waste/biofuels, have
characteristics which must be overcome in order to employ them as a
fuel source. For example, various forms of glycerol remain a solid
below approximately 18.degree. C. (64.4.degree. F.), have a
flashpoint of 199.degree. C. (390.2.degree. F.), and have an
autoignition point of 412.degree. C. (773.6.degree. F.). In
contrast, petroleum diesel is a liquid at room temperature and has
a typical flashpoint of between approximately 52.degree. C.
(126.degree. F.) and 96.degree. C. (204.degree. F.) and an
autoignition point of approximately 210.degree. C. (410.degree.
F.)--nearly half that of glycerin. Recognized, therefore, by the
inventor is the need for an apparatus and methods for economically
and efficiently burning such heavily viscous waste/biofuels in a
combustion chamber to produce an exhaust which can be utilized as
an energy source. Further recognized by the inventor is the need
for such apparatus and methods which can provide flameless
combustion to thereby decrease nitric oxide emissions and increase
energy efficiency.
SUMMARY OF THE INVENTION
[0013] In view of the foregoing, various embodiments of the present
invention advantageously provide an apparatus and methods for
economically and efficiently burning viscous biofuels in a
combustion chamber to produce an exhaust which can be utilized as
an energy source. Various embodiments of the present invention also
advantageously provide an apparatus and methods which include a
vortex combustion chamber configured to provide flameless
combustion to thereby decrease nitric oxide emissions and increase
energy efficiency. Various embodiments of the present invention
provide an apparatus and methods which improve upon the Jirnov
vortex combustion chamber and precombustion chamber described in
U.S. Pat. No. 5,839,270 by Jirnov et al., titled "Sliding-Blade
Rotary Air-Heat Engine with Isothermal Compression of Air," to more
efficiently accommodate use of the more viscous fuels, such as
glycerol.
[0014] Particularly, various embodiments of the present invention
advantageously provide an apparatus for providing flameless
combustion of a viscous fuel. According to an embodiment of the
present invention, the apparatus includes a precombustion chamber
adapted to heat and at least partially combust a primary fuel and a
main combustion chamber adapted to combust the primary fuel. The
precombustion chamber can include a cylindrical housing having an
enclosed proximal end portion, an open distal end portion, and a
substantially hollow main body extending therebetween and
substantially enclosing a precombustion chamber cavity. The
precombustion chamber can include at least one air injection inlet
port extending through the body of the cylindrical outer housing
and positioned to inject or otherwise deliver combustion air into
the precombustion chamber and positioned to help induce a first
stage vortex in the main body portion of the housing of the
precombustion chamber. The precombustion chamber can also include
at least one primary fuel nozzle positioned to inject primary fuel
into the precombustion chamber, an igniter fuel nozzle positioned
to inject ignition fuel into the precombustion chamber, an igniter
positioned to ignite the igniter fuel, and a hollow cylindrical
combustion stabilizer positioned within the precombustion chamber
cavity to receive igniter fuel and primary fuel and to isolate the
primary fuel from a portion of the combustion air when being heated
with the igniter fuel.
[0015] The combustion stabilizer includes a proximal end portion, a
distal end portion, and a main body portion extending between the
proximal end portion and the distal end portion. The combustion
stabilizer main body includes a large diameter sidewall spaced
radially inward from the precombustion chamber housing to define an
annulus therebetween and includes at least one air inlet aperture
extending therethrough to receive a portion of the combustion air
to thereby supply oxygen to the igniter fuel and to thereby
initiate oxidation of the fuel within the combustion stabilizer.
The distal end portion is in fluid communication with the
combustion stabilizer main body and has a small diameter sidewall
having a diameter substantially smaller than the large diameter
sidewall of the main body. The distal end portion further includes
an unobstructed distal end aperture for expelling heated primary
fuel into the precombustion chamber cavity adjacent to the distal
end portion of the precombustion chamber housing.
[0016] The main combustion chamber includes an, e.g., cylindrical
or elliptical housing having an at least partially enclosed
proximal end portion including an exhaust aperture, an enclosed
distal end portion, and an elongate main body extending
therebetween and substantially enclosing a main combustion chamber
cavity. The main body can include an inner main body diameter and
can have a main body axial length extending at least approximately
twice the main body diameter. The main body axial length can have a
preselected value preselected to provide a sufficient pyrolyzed
fuel travel distance within the main combustion chamber based upon
one or more fuel performance characteristics of the primary fuel.
The main combustion chamber can also include a combination
precombustion chamber exhaust outlet and main combustion chamber
fuel-air mixture inlet (hereinafter "exhaust-inlet) located
adjacent the proximal end portion of the main combustion chamber
housing and extending through the main body of the main combustion
chamber housing. The exhaust-inlet is positioned to receive the at
least partially combusted primary fuel from the precombustion
chamber and positioned (e.g., tangentially) to induce a second
stage vortex within the main body of the main combustion chamber
housing.
[0017] The main combustion chamber also includes a combustion
exhaust tube or other form of conduit (e.g., Venture form)
extending from, and interfaced with, the proximal end portion of
the main combustion chamber housing, and extending coaxially along
a same longitudinal axis as the main combustion chamber housing.
The combustion exhaust tube or conduit includes an open distal end
portion and an elongate main body extending between the open distal
end portion of the combustion exhaust tube and the proximal end
portion of the main combustion chamber housing. The distal end
portion of the combustion exhaust tube extends axially within the
main combustion chamber cavity to a location between a position
distally forward of an axial midpoint position of the elongate main
body of the main combustion chamber housing and a position located
axially a distance of at least one exhaust tube main body diameter
from the distal end portion of the main combustion chamber
housing.
[0018] According to another embodiment of the present invention, an
apparatus for providing flameless combustion of a fuel includes a
main combustion chamber adapted to combust a primary fuel. The main
combustion chamber includes a housing having a proximal end portion
including an exhaust aperture, a distal end portion, and an
elongate main body extending therebetween and substantially
enclosing a main combustion chamber cavity. The main body has an
inner main body diameter and a main body axial length. An
exhaust-inlet extends through the main body of the main combustion
chamber housing at an inlet location. The exhaust-inlet is
positioned to receive at least partially combusted primary fuel
from a precombustion chamber and is positioned to help induce a
vortex within the main body of the main combustion chamber housing.
According to a preferred configuration, the main body axial length
extends distally from the inlet location a distance value
approximately equal to or greater than that of the inner main body
diameter. Particularly, the main body axial length has a
preselected value preselected to provide a sufficient pyrolyzed
fuel travel distance from the exhaust-inlet within the main
combustion chamber cavity to exit based upon one or more fuel
performance characteristics of the particular type/configuration of
the primary fuel.
[0019] The main combustion chamber can further include a combustion
exhaust conduit extending from and interfaced with the proximal end
portion of the main combustion chamber housing and extending
coaxially along a same longitudinal axis as the main combustion
chamber housing. The combustion exhaust conduit can include an open
distal end portion and an elongate main body extending between the
open distal end portion of the combustion exhaust conduit and the
proximal end portion of the main combustion chamber housing.
Specifically, the distal end portion of the combustion exhaust tube
can extend axially within the main combustion chamber cavity to a
location between a position distally forward of an axial midpoint
position of the elongate main body of the main combustion chamber
housing and a position located axially a distance of at least one
exhaust tube main body diameter from the distal end portion of the
main combustion chamber housing. According to this configuration,
the axial spacing of the distal end portion of the combustion
exhaust conduit from the distal end portion of the main combustion
chamber housing has a value approximately equal to or greater than
that of at least one exhaust conduit main body diameter inner
diameter.
[0020] Various embodiments of the present invention also provide
methods of providing flameless combustion of a viscous fuel.
According to an embodiment of the present invention, such a method
can include the steps of inducing a first stage vortex in a primary
fuel-air mixture within a main body of a precombustion chamber of a
flameless combustor, receiving within a main body of a main
combustion chamber of the flameless combustor the primary fuel-air
mixture having a first stage vortex induced state, and inducing a
second stage vortex in the received primary fuel-air mixture to
form a complex vortex pattern to thereby enhance flameless
oxidation of the primary fuel within the main body of the main
combustion chamber. According to a preferred configuration, the
step of inducing can include expelling the primary fuel-air mixture
tangentially into the main combustion chamber cavity through a
precombustion chamber exhaust outlet. According to this
configuration, the diameter of the first stage vortex is
substantially smaller than a diameter of the second stage vortex
formed within the main combustion chamber.
[0021] The method can also include the steps of interfacing with
the main combustion chamber, a precombustion chamber adapted to
heat and at least partially combust the primary fuel, igniting a
secondary fuel within the precombustion chamber adjacent a flowpath
of the primary fuel to at least partially combust the primary fuel
within the precombustion chamber, sensing a temperature of the
exhaust gas exiting the combustion exhaust conduit of the main
combustion chamber, and controlling a flow of the secondary fuel
into the precombustion chamber responsive to the exhaust gas
temperature of the exhaust gas exiting the combustion exhaust
conduit.
[0022] According to another embodiment of the present invention, a
method of providing flameless combustion of a viscous fuel can
include the steps of providing a main vortex combustion chamber of
a flameless combustor having a main body substantially enclosing a
main combustion chamber cavity having an axial length approximately
equal to or greater than an inner diameter of the main combustion
chamber cavity, and inducing a vortex within the main combustion
chamber cavity to enhance flameless oxidation of a primary fuel.
The method can also include the step of providing a combustion
exhaust conduit within and axially coincident with the main
combustion chamber cavity. The combustion exhaust conduit can have
an inlet positioned at a location between an axial position
distally forward of an axial midpoint position of the elongate main
body of the main combustion chamber housing and an axial position
within the main combustion chamber cavity adjacent the distal end
portion of the main combustion chamber housing. The axial spacing
of the distal end portion of the combustion exhaust conduit from an
inner surface of the distal end portion of the main combustion
chamber housing can further have a value approximately equal to or
greater than that of at least one exhaust conduit main body inner
diameter.
[0023] The method can further include the step of injecting the
primary fuel into the main combustion chamber cavity through a
combination precombustion chamber exhaust outlet-main combustion
chamber inlet ("exhaust-inlet"). The exhaust-inlet is axially
spaced apart from the combustion exhaust conduit inlet a
preselected value preselected to provide a sufficient pyrolyzed
fuel travel distance from the exhaust-inlet within the main
combustion chamber cavity based upon one or more fuel performance
characteristics of the primary fuel to provide substantially
complete pyrolization thereof. The method can further include the
step of preselecting the value of the axial separation between the
exhaust-inlet and the combustion exhaust conduit inlet to provide
the sufficient pyrolyzed fuel travel distance from the
exhaust-inlet within the main combustion chamber cavity responsive
to one or more fuel performance characteristics of the glycerol
fuel.
[0024] Various embodiments of the present invention also provide a
precombustion chamber, and a vortex combustion chamber which is an
improvement over the Jirnov vortex combustion chamber and
precombustion chamber. Various embodiments of the present invention
provide, for example, a vortex combustor including a main
combustion chamber connected or otherwise interfaced with a
precombustion chamber, which successfully solves problems
associated with operating on highly viscous fuels with a high
completeness of combustion over the wide range of the coefficient
of air redundance and produces a substantial reduction in toxicity
of exhaust gases. Various embodiments of the present invention
provide high thermal and volumetric efficiency, may employ a
variety of types of viscous and non-viscous combustible hydrocarbon
fuels, have reduced quantities of environmentally damaging
emissions, and have a simplified combustor design and ease of
fabricating, which is economical to manufacture in mass production
and is inexpensive to operate, service, and repair.
[0025] Various embodiments of the present invention provide a
vortex chamber positioned at the tube inlet and provide feedback
loops positioned along the length of the heat transfer section,
which enable the resulting fuel combustion efficiency to be
increased by inducing a swirl flow and intensive recirculation of
fluid along the length of the heat transfer section. Such improved
fuel efficiency can advantageously reduce environmentally damaging
emissions. Further, such apparatus may be used in converting
thermal energy into electric power, can be used in generating
steam, and/or can be utilized as part of a transportation engine
with high thermal efficiency.
BRIEF DESCRIPTION OF THE DRAWINGS
[0026] So that the manner in which the features and advantages of
the invention, as well as others which will become apparent, may be
understood in more detail, a more particular description of the
invention briefly summarized above may be had by reference to the
embodiments thereof which are illustrated in the appended drawings,
which form a part of this specification. It is to be noted,
however, that the drawings illustrate only various embodiments of
the invention and are therefore not to be considered limiting of
the invention's scope as it may include other effective embodiments
as well.
[0027] FIG. 1A is a partially perspective and partially sectional
view of a combustor for providing flameless combustion of a viscous
fuel according to an embodiment of the present invention;
[0028] FIG. 1B is a partially prospective and partially sectional
view of the combustor of FIG. 1A illustrating vortex generation
according to an embodiment of the present invention;
[0029] FIG. 2A is a sectional view of the combustor taken along the
2-2 line of FIG. 1B according to an embodiment of the present
invention;
[0030] FIG. 2B is a sectional view of the combustor of FIG. 2A
illustrating vortex generation according to an embodiment of the
present invention;
[0031] FIG. 3A is a sectional view of the main combustion chamber
of FIG. 1A according to an embodiment of the present invention;
[0032] FIG. 3B is a sectional view of an alternate embodiment of
the main combustion chamber of FIG. 1A according to an embodiment
of the present invention
[0033] FIG. 4 is a sectional view of an alternate embodiment of the
combustor illustrated in FIG. 2B according to an embodiment of the
present invention;
[0034] FIG. 5 is a sectional view of an alternate embodiment of the
combustor illustrated in FIG. 1B according to an embodiment of the
present invention;
[0035] FIG. 6A is a sectional view of an alternate embodiment of
the combustor illustrated in FIG. 2A an embodiment of the present
invention;
[0036] FIG. 6B is a sectional view of an alternate embodiment of
the combustor illustrated in FIG. 2A an embodiment of the present
invention;
[0037] FIG. 7 is a schematic block diagram of a combustion
management/fuel-gas supply system for providing flameless
combustion according to an embodiment of the present invention;
[0038] FIG. 8 is a schematic block flow diagram illustrating a
method of providing flameless combustion including steps for
forming the combustor of FIG. 1A according to an embodiment of the
present invention;
[0039] FIG. 9 is a schematic block flow diagram illustrating a
method of providing flameless combustion including steps for
operating the combustor of FIG. 1A according to an embodiment of
the present invention;
[0040] FIG. 10 is a schematic block flow diagram illustrating
substeps of the method shown in FIG. 9 according to an embodiment
of the present invention; and
[0041] FIG. 11 is a schematic block flow diagram illustrating
substeps of the method shown in FIG. 9 according to an embodiment
of the present invention.
DETAILED DESCRIPTION
[0042] The present invention will now be described more fully
hereinafter with reference to the accompanying drawings, which
illustrate embodiments of the invention. This invention may,
however, be embodied in many different forms and should not be
construed as limited to the illustrated embodiments set forth
herein. Rather, these embodiments are provided so that this
disclosure will be thorough and complete, and will fully convey the
scope of the invention to those skilled in the art. Like numbers
refer to like elements throughout.
[0043] FIGS. 1A-11 illustrate a system 30 including combustor
apparatus 31 and methods which improve upon the vortex combustion
chamber and precombustion chamber of the Jirnov engine described in
U.S. Pat. No. 5,839,270 by Jirnov et al., titled "Sliding-Blade
Rotary Air-Heat Engine with Isothermal Compression of Air," to more
efficiently accommodate use of more viscous fuels. According to
various embodiments of the present invention, the combustor
apparatus 31 can beneficially work under high pressure and high
flow rate of air. The combustor apparatus 31 can be especially
useful for burning waste fuel, such as Glycerol (Glycerin), and
emulsified heavy oil (with water) fuels, along with a number of
conventional liquid fuels, such as jet propellant (JP), Diesel,
Kerosene, Gasoline, and any of the gaseous fuels, such as Hydrogen,
CO and Carbohydrate, etc. Various embodiments of the combustor
apparatus 31 provide substantially complete combustion with very
low nitric oxide (NOx) and carbon monoxide (CO). Embodiments of the
combustor apparatus 31 further provide no flame on the exit, making
it an ideal apparatus for use in gas turbines and in heating
systems.
[0044] More specifically, as perhaps best illustrated in FIGS. 1A
and 2A, the apparatus 31 can include a vortex precombustion chamber
33 interfaced with a main vortex combustion chamber 35 as will be
described in more detail, below. The precombustion chamber 33 is
used for forming, a super-rich fuel and air mixture, ignition,
partial combustion and pyrolysisation of heavy and low grade fuels.
Note, FIGS. 3B-6A illustrate various alternative embodiments of the
apparatus 31, particularly with respect to how the vortex
precombustion chamber 33 is interfaced with the main vortex
combustion chamber 35. For simplicity, the same numbering will be
maintained for like items across the various embodiments.
[0045] As shown in FIG. 2A, according to an embodiment of the
present invention, the precombustion chamber 33 has a hollow
cylindrical housing 41 enclosing a cavity 42 at one end 43, and can
have one or more air inlets 45 extending through its sidewall (main
body) 47. A hollow cylindrical combustion stabilizer 49 is secured
within the outer housing 41 and can have a large diameter side wall
51 spaced radially inward from the outer housing 41 to define an
annulus 53 therebetween, and can have a reduced diameter neck
portion 55 at one end. At least one, but preferably a plurality of
air inlet ports 57 extend through the larger diameter sidewall 51
to provide combustion air communication with the air inlet 45 of
the outer housing 41. According to an embodiment of the
precombustion chamber 33, the air inlet ports 57 extend
tangentially through the sidewall 51.
[0046] According to an embodiment of the precombustion chamber 33,
a funnel-shaped flame tube 61 is secured to the open end of the
outer housing 41 by a radial flange 63 and has a hollow cylindrical
side wall portion 65 received within the open end of the outer
housing 41, a conical side wall portion 67, and a reduced diameter
neck portion 69 at one end. The radial flange 63 is secured between
the open end of the outer housing 41 and a conical flanged fitting
71 on the outer housing of the vortex combustion chamber 35. The
conical side wall portion 67 of the flame tube 61 is received
within the conical flanged fitting 71, and the reduced diameter
neck portion 69 is connected with a tubular channel 73 disposed
tangential to the periphery of the main vortex combustion chamber
35. The exterior of the cylindrical side wall portion 65 is spaced
radially inward from the interior of the outer housing 41 and the
conical side wall portion 67; and the reduced neck portion 69 is
spaced radially inward from the interior of the conical flanged
fitting 71 to define an annulus 75 therebetween. Further, a
plurality of passageways 77 extend through the radial flange 63 to
allow communication through the annulus 75.
[0047] According to an embodiment of the present invention, the
combustion stabilizer 49 is provided with one or more primary fuel
injectors/nozzles 81 for injecting a primary fuel, a secondary fuel
injector(s)/nozzle(s) 83 for injecting a secondary or ignition fuel
positioned to ignite the primary fuel, and a fuel igniter or spark
plug 85. The secondary fuel injector 83 can provide fuel, e.g.,
propane, etc., to pre-heat the primary fuel, particularly if a
heavy or viscous primary fuel is used or if the ambient temperature
is below that required. According to a preferred configuration, the
nozzles 81, 83, and the igniter 85 are located in the top cover
portion 87 of the precombustion chamber 33. A portion of air from
the general airflow drawn or injected through opening 45, is
further drawn or injected into the combustion stabilizer 49 through
air inlets 57 to create an air-fuel mixture near the secondary fuel
injector 83 and the spark plug 85.
[0048] According to another embodiment of the present invention, as
perhaps best illustrated in FIG. 4, rather than utilize a secondary
or ignition fuel, the combustion stabilizer 49 is instead provided
with a fuel vaporizer 91 having terminals 93 extending from the
precombustion chamber 33, which are connected with a source of
electrical current (not shown). A portion of air from the general
airflow drawn or injected through opening 45 is further drawn into
the combustion stabilizer 49 through air inlets 57 to create an
air-fuel mixture near the spark plug 85. Such fuel vaporizer 91
provides an alternative methodology of preheating the primary fuel
in cold seasons and/or if a heavy or viscous fuel is used. That is,
low-grade or waste fuels, when used, can be pre-heated/combustion
to reduce the viscosity of the fuel and to provide for an
acceptable level of atomization.
[0049] According to an embodiment of the present invention, in
operation, fuel is delivered to the precombustion chamber 33
through single or multiple primary fuel injector(s)/nozzle(s) 81
via a fuel supply system 37. When multiple nozzles 81 are utilized,
the fuel supply system 37 can beneficially allow the apparatus 31
to oxidize different types of liquid or gaseous fuels emanating
from independent sources, separately or simultaneously. The fuel
nozzle or nozzles 81 can be interfaced with a compressed air/gas
supply, either directly or indirectly via taps (not shown) in the
fuel supply lines 39, to help breakup the liquid fuel jet expelled
from the fuel nozzle(s) 81 and provide a minimal size of fuel
droplets, i.e., form an aerosol or colloid, or at least a
suspension. The resulting minimal size droplets can have a reduced
(short) time of vaporization, and thus, reduced combustion time.
This can be especially beneficial when combustion for waste fuels,
such as Glycerin, is desired.
[0050] As noted above, combustion airflow, for example, provided by
a cooling air (gas/fluid) supply system 36, is provided through the
one or more air inlets 45 extending through sidewall 47. The
required airflow rate and/or oxygen content of the combustion air
can be determined and set based on the ratios of momentum and mass
for a given liquid fuel flow rate to provide maximum instability of
the air-fuel flow and efficient precombustion. Particularly, the
combined airflow rate of the air entering/exiting the inlet(s) 45
and mass flow of primary fuel entering the precombustion chamber 33
can have a ratio between 20:1 to 40:1, with a preferred ratio of
approximately 30:1; and the combustion gas (e.g., air) to mass flow
of fuel can have a ratio of preferably between 30:1 to 50:1, with a
more preferred ratio of approximately 40:1. Such fuel injection
configuration can provide for the shortest breakup length and
breakup time inside of the precombustion chamber 33. Further, the
precombustion chamber 33 can have an axial length to sidewall/main
body cross-sectional diameter ratio of preferably between 2:1 to
4:1, with a more preferred ratio of approximately 3:1 to ensure
sufficient precombustion prior to entering the main vortex
combustion chamber 35. Consequently, according to embodiments of
the apparatus 31, the combustion process is complete and occurs
downstream inside of the main chamber 35 without flame on the exit.
The absence of a flame on exit can beneficially extend the use of
apparatus 31/vortex combustion chamber 35 for many applications
known to those skilled in the art, including for turbines, engines,
and heaters.
[0051] As perhaps best shown in FIG. 7, process control of
apparatus 31 can be provided by a combustion management/fuel-gas
supply system 200 which can include a controller 201 positioned to
sense various fuel system and combustion system parameters to
control the combustion process. The controller 201 can include a
processor/logic circuit 203 and memory 205 coupled to the processor
203 to store software and/or database records therein. The memory
205 can include volatile and nonvolatile memory known to those
skilled in the art including, for example, RAM, ROM, and magnetic
or optical disks, just to name a few.
[0052] The combustion management/fuel-gas supply system 200 can
also include various sensors, known to those skilled in the art,
including, for example, a mass flow/density/momentum meter or
meters 211 interfaced with the fuel system 37 to monitor fuel
characteristics of the primary fuel; a combustion air pressure
sensor 213 positioned to monitor air pressure of the air entering
air inlet or inlets 45; a combustion air oxygen content sensor 215
positioned to monitor the oxygen content of the combustion air; and
an exhaust gas temperature (EGT) probe 217 positioned to sense the
temperature of the exhaust gases emanating from combustion exhaust
tube or conduit 115 (see FIG. 1A), described in more detail
later.
[0053] The combustion management/fuel-gas supply system 200 can
further include various control devices including, for example, a
combustion air/gas pump, injector, or valve 221 for adjusting
combustion air pressure; a primary fuel pump or valve 223 for
managing fuel pressure of the primary fuel; a secondary fuel
control pump or valve 225 for managing the amount of secondary fuel
used to help pre-combust the primary fuel in the combustion
stabilizer 49 of the precombustion chamber 33; an ignition circuit
227 for igniting the secondary fuel; and an fuel-air pump 229 for
aerating the primary fuel. Note, it should be understood by one
skilled in the art that the above described control devices can
further include internal controllers within each device.
[0054] The combustion management/fuel-gas supply system 200 can
also include a user interface 207 as known to those skilled in the
art, to provide a user access to manipulate or access software and
database records, and combustion management program product 231
stored in memory 205 of the controller 201 to provide combustion
management. The program product 231, according to an embodiment of
the combustion management/fuel-gas supply systems 200 includes
instructions that when executed by the controller 201 cause the
controller to perform various operations to include gathering or
otherwise collecting real-time data from sensors 211, 213, 215, and
217, to perform real-time combustion management to include, for
example: adjusting fuel pressure of the primary fuel responsive to
output requirements of a supported system (e.g., turbine, engine,
etc.); adjusting combustion air pressure/rate to maximize
instability of the air-fuel flow and/or adjusting aeration of the
fuel responsive to the density or mass flow of the primary fuel to
enhance combustibility of the fuel; and applying or discontinuing
application of the secondary fuel responsive to the exhaust gas
temperature to help ensure substantially complete oxidation of the
primary fuel prior to exit from the main combustion chamber exhaust
conduit 115, just to name a few.
[0055] Note, the combustion management program product 231 can be
in the form of microcode, programs, routines, and symbolic
languages that provide a specific set for sets of ordered
operations that control the functioning of the hardware and direct
its operation, as known and understood by those skilled in the art.
Note also, the combustion management program product 231, according
to an embodiment of the present invention, need not reside in its
entirety in volatile memory, but can be selectively loaded, as
necessary, according to various methodologies as known and
understood by those skilled in the art.
[0056] As shown in FIGS. 2A-2B, for example, the main vortex
combustion chamber 35 receives through a joint precombustion
chamber exhaust outlet and main combustion chamber fuel-air inlet
(or "exhaust-inlet") 95, a super-rich mixture of fuel and air
formed in the precombustion chamber 33 along with partially burned
and pyrolyzed products for after-burning. As perhaps best shown in
FIGS. 3A-3B, according to an embodiment of the present invention,
the main combustion chamber 35 has an outer housing formed by a
main body 101, 101', enclosed at the bottom end by outer bottom end
wall 103, and at the top end by an outer top wall 105 and a
collector member 107 secured to the outer top wall 105, to form a
combustion chamber cavity 109 therein in which nameless combustion
occurs. The collector member 107 has a top flange 111 and a central
bore 113 which can be connected to or otherwise interfaced with the
inlet port of a powered/heated device, e.g., gas turbine, engine,
etc. (not shown).
[0057] According to various embodiments of the present invention,
the main body 101 of the main combustion chamber 35 preferably has
a cylindrical form (FIG. 3A), an elliptical form (see, e.g., FIG.
3B) or a funnel shaped form (not shown), although other
forms/configurations are within the scope of the present invention.
The main combustion chamber 35 also has an axial length preselected
based on the type of fuel expected to be combusted. For example,
for a heavily viscous fuel such as glycerol, the main combustion
chamber cavity 109 can have an axial length to main body
cross-sectional diameter ratio sufficient to provide uniform volume
distributed combustion for the type of fuel used. In the exemplary
configuration, the main combustion chamber cavity 109 can have an
axial length of at least half the diameter of the main combustion
chamber cavity 109, and more preferably, an axial length equivalent
to the value of at least one chamber cavity diameter, with the
overall main combustion chamber cavity 109 preferably having at
least an axial length of 1.5 or more chamber cavity diameters, and
more preferably at least a length of two or more chamber cavity
diameters. In a more preferred configuration, where glycerol is the
fuel, the main body axial length to cross-sectional diameter ratio
is preferably between 5:1 to 6:1, with a preferred ratio of
approximately 5:1.
[0058] According to embodiments of the present invention, the main
combustion chamber 35 further includes a combustion exhaust tube or
conduit 115, which serves as the outlet or exhaust pipe for the
near-axis zone of the main vortex combustion chamber 35. The
exhaust conduit 115 can be configured either as a separate unit, or
as a tubular extension of collector member 107, which extends
distally therefrom through a central opening 117 in the inner top
wall 105. The combustion exhaust conduit 115 and central opening
117 together form an annulus 119 therebetween. The combustion
exhaust conduit 115 can have various shapes to include cylindrical
(see, e.g., FIG. 3A), venturi (see, e.g., FIG. 3B) shown at 115',
or others known to those skilled in the art.
[0059] According to an embodiment of the present invention, the
combustion exhaust tube or conduit 115 is positioned and extends
within the main combustion chamber cavity 109 to a location, for
example, at least beyond the midpoint of the main body 101 of the
combustion chamber 35, but preferably adjacent the bottom end wall
103 spaced apart therefrom at an axial distance equivalent to at
least the value of the inner diameter of a distal/inlet portion
11.6 of the combustion exhaust conduit 115. When heavily viscous
fuel such as glycerol is used, which requires additional time to
oxidize, the combustion exhaust tube or conduit 115 can have a
axial offset distance from the inner surface of the bottom end wall
103 to combustion exhaust tube cross-sectional inner diameter ratio
of between 1:1 to 3:1, with a preferred ratio of approximately 2:1.
As perhaps best shown in FIG. 3A, according to a preferred
embodiment of the present invention, the exhaust conduit 115 can
extend axially approximately 75% of the main body 101 (e.g.,
cylindrical part) of the vortex combustion chamber 35, making the
axial offset distance approximately 25% of the axial length of the
main body 101.
[0060] Accordingly, for the main combustion chamber 35
configuration having a main combustion chamber cavity 109,
combustion exhaust conduit 115, and precombustion chamber 33
positioned, for example, as shown in FIG. 1B, the pyrolyzed gases
entering the main combustion chamber cavity 109 from precombustion
chamber 33 must travel at least twice the distance through the
vortex combustion chamber 35 as that of the Jirnov vortex
combustion chamber before it can initiate escape through the
combustor exhaust conduit 115. Further, any remaining fuel inside
the combustor exhaust conduit 115 also must travel at least
approximately twice the distance before exiting the combustor
exhaust conduit 115 as that of the Jirnov vortex combustor to
further allow any remaining fuel to oxidize before exit through the
exhaust port 113. As such, the pyrolyzed gases entering the main
combustion chamber cavity 109 from precombustion chamber 33 must
ultimately travel four or five times the total distance to exit
through the exhaust orifice or port 113. Even in an embodiment of
the present invention such as, for example, that shown in FIG. 5
having the joint precombustion chamber exhaust outlet-main
combustion chamber inlet 95 positioned, for example, at a midpoint
or some other medial position, the ultimate travel distance is at
least two or more times the total distance to exit through the
exhaust orifice or port 113.
[0061] According to an embodiment of the present invention, an
inner bottom wall 121 and an inner top wall 123 are secured within
the outer bottom wall 103 and outer top wall 105, respectively, in
a spaced apart relation to define a flow passageway 125
therebetween. One or more swirl nozzles 127 are connected to or
otherwise interfaced with the passageway 125 between the outer
bottom wall 103 and inner bottom wall 121. A plurality of
passageways 129 extend longitudinally through the side wall of the
cylindrical main body 101 of the combustion chamber housing to
allow communication with the flow passageways 131. The passageways
125, 129, and 131, form an isolated fuel-air recirculation channel
which passes around the interior of the main combustion chamber
35.
[0062] According to an embodiment of the present invention, a
bypass conduit 133 connects the radial passageways 131 to a
compressed airflow entering the recirculation system of combustion
chamber 35 via an external supply conduit 135. According to a
preferred configuration, the recirculation system via bypass
conduit 133 and external supply conduit 135 receives both cooling
air and another cooling fluid (e.g., water) to enhance cooling the
main combustion chamber 35.
[0063] As perhaps best shown in FIGS. 2A and 3A, the main
combustion chamber 35 can include a perforated liner 141 having
openings 143. The liner 141 can be secured to the interior surfaces
of the main body (sidewall) 101, inner bottom wall 121, and inner
top wall 123 of the combustion chamber 35. The vertically opposed
interior surfaces of the liner 141 and the inner top wall 123 and
inner bottom wall 121 have opposite facing, outwardly concave,
curved surfaces with the axial distance between the curved surfaces
increasing inversely from their periphery with respect to the
radial distance. According to an embodiment of the combustion
chamber 35, the vertically opposed interior surfaces of the liner
141 are curved or contoured according to the Navier-Stocks'
equation with the constraint to provide substantially constant
vortex radial velocity conditions to ensure minimal hydrodynamic
losses.
[0064] The liner 141 includes a cylindrical side wall 145 joined
tangentially to the tubular channel 73 (see, e.g., FIG. 2A) and
serves as a cylindrical heat tube between the precombustion chamber
33 and the main combustion chamber 35. An annulus/gap 147 between
the inner surface of the main body 101 of the combustion chamber 35
and cylindrical side wall 145 of the liner 141, and between the
inner surface of the inner bottom wall 121 and inner surface of the
inner top wall 123 and the perforated liner 141, serves as a
cooling jacket. The annulus/gap 147 is in communication with the
annulus 75 (see, e.g., FIG. 2A). According to an embodiment of the
main combustion chamber 35, the juncture of the combustor exhaust
conduit 115 and the top flange 111 is contoured and has an annular
raised lip ring 151 which extends angularly upwardly therefrom for
a distance into the passageway 125 between the inner top wall 123
and outer top wall of the main combustion chamber 35.
[0065] The cool and moist air (identified above) can be directed
through the bypass conduit 133 and the radial passageways 131, and
onto the annular raised lip ring 151, which serves as a fuel-air
ejector ring, and which causes a Ventura effect to return trapped
fuel film through the recirculation channel 125, 129, 131 and swirl
nozzle(s) 127 back into the chamber combustion zone. The swirl
nozzle(s) 127 are configured to swirl the recirculated
fuel-air-water mixture flowing through the recirculation channels
125, 129, 131, as it enters the interior of the main combustion
chamber 35. Because the swirl nozzle or nozzles 127 are located in
the near-axis zone of the vortex combustion chamber 35 where the
lowest pressure tends to occur, the fuel-air ejector ring 151 is
subjected to a substantial pressure drop and its operation is thus
intensified.
[0066] To initiate combustion of a primary fuel (e.g., glycerin),
in the embodiment shown in FIG. 2A, secondary or ignition fuel
(e.g., propane, etc.) is introduced next to secondary fuel nozzle
83, and the igniter/sparkplug 93 is momentarily activated to ignite
the ignition fuel. Combustion air/gas is drawn or pumped into the
precombustion chamber 33 through air/gas inlet(s) 45. The primary
fuel is then introduced into the combustion stabilizer 49 through
the primary fuel injector(s) 81, along with a portion of the
combustion air/gas from the general air/gas flow and into the
combustion stabilizer 49 through air openings/inlets 57, to create
an air-fuel mixture near the secondary fuel nozzle 83, for
ignition.
[0067] Similarly, in the embodiment shown in FIG. 4, the primary
fuel is introduced into the combustion stabilizer 49 through the
primary fuel injector(s) 81 and a portion of air from the general
air flow is drawn into the stabilizer 49 through the
openings/inlets 57 to create an air-fuel mixture near the spark
plug 93, and the plug is activated to ignite the mixture. In this
configuration, a fuel vaporizer 91 may used to heat the fuel,
particularly if a heavy fuel is used in cold weather that does not
require ignition by a more readily combustible secondary fuel.
[0068] As perhaps best shown in FIG. 2B, the ignited and partly
pyrolyzed fuel-air mixture formed in the combustion stabilizer 49
then passes through the interior of the funnel-shaped flame tube
143, where it begins to swirl due to the orientation of the general
air/gas flow and/or orientation of the primary and/or secondary
fuel nozzles (first stage vortex 161 formation). The ignited and
partially pyrolyzed fuel then passes through the channel 73, for
example, tangentially through exhaust-inlet 95 and into the vortex
combustion chamber 35 for after-burning (see FIGS. 1B, 2B and 4).
Note, in an alternate embodiment of the present invention, perhaps
best shown in FIG. 6A-6B, the precombustion chamber 33 can be
instead interfaced with the combustion chamber 35 at exhaust-inlet
95' in a more normal orientation. Other orientations, however, are
also within the scope of the present invention.
[0069] The air received through air/gas inlet(s) 45 can also flow
through the annulus 53, 75, and passageways 77 between the flame
tube 61 and the housing 41 of the precombustion chamber 33 and
conical flanged fitting 71 of the vortex combustion chamber 35 and
the annulus 147 surrounding the perforated liner 141, to thereby
cool the flame tube 61, perforated liner 141 and cylindrical side
wall 145. According to an embodiment of the present invention
illustrated in FIGS. 1A-2B, the combustion products of partially
burned and pyrolyzed fuel from the precombustion chamber 33,
already in a swirling state, are caused to swirl (to form a second
stage vortex 163) as they enter the vortex combustion chamber
cavity 109 through the tangential channel 73, thereby forming a
two-stage complex vortex pattern. Note, in an alternate embodiment
of the present invention, perhaps best shown in FIG. 6A-6B, whereby
the precombustion chamber 33 is instead interfaced with the
combustion chamber 35 in a more normal orientation, the combustion
exhaust tube or conduit 115 can include a swirl enhancer 171, e.g.,
spiral, grooves or protuberances oriented to induce the swirling
state within the combustion chamber cavity 109.
[0070] It is perhaps best shown in FIG. 3A, the inwardly contoured
walls 121, 123, and liner 141 of the main combustion chamber cavity
109, and the equinoctial condition of the centrifugal and
aerodynamic forces acting on the condensed particles in the vortex
stream of air in the main combustion chamber cavity 109 allow
unvaporized fuel droplets to be confined in equilibrium in the
orbit of rotation for a sufficient length of time such that fuel
droplet migration to a small radius will only occur when the
droplet diameters become sufficiently small during the combustion
process. This feature can enhance stabilizing combustion and
providing a high degree of completeness of combustion.
[0071] In the combustion process, a portion of the fuel, not
participating in mixing and combustion, moistens the inner walls of
the liner 141 in the vortex combustion chamber 35, and in the form
of a migrating film of unmixed and uncombusted fuel, migrates to
the lower portion of the chamber 35, at least in part, due to
gravity, and is captured at the inward side of the annular raised
lip ejector ring 151. A portion of the preferably cool and moist
air is directed through the conduit 135, the bypass conduit 133,
and the radial passageways 131, onto the outward side of the
annular raised lip ejector ring 151, which causes a venturi effect,
which further functions to return the trapped unmixed and
uncombusted fuel as a fuel-air mixture through the recirculation
channels 125, 129, and swirl nozzle 127 back into the chamber
combustion zone. The swirl nozzle 127 swirls the recirculated
fuel-air mixture flowing through the recirculation channels 125,
129, as it enters the cavity 109 of the vortex combustion chamber
35.
[0072] Efficient and reliable cooling of the combustion chamber 35
can be provided by air flows through the annulus 75 and 147 and by
the flowing of part of the cooling air (preferably with a certain
amount of water) through recirculation channels 125, 129. As noted
previously, because the swirl nozzle or nozzles 127 are located in
the near-axis zone of the vortex combustion chamber where
re-refraction occurs, in such configuration, the fuel-air ejector
ring 151 is subjected to a substantial pressure drop, and its
operation is intensified. The combined total amount of air arriving
at the main vortex chamber combustion zone through air inlet ports
57, tubular channel 73, annulus 75, and bypass conduit 133, form a
lean fuel-air mixture for after-burning.
[0073] Beneficially, the various combinations of the structural and
operational features of embodiments of the main vortex combustion
chamber 35 provide a small combustion chamber capable of burning a
variety of fuels with high energy efficiency and low toxicity of
the products, including low amounts of NOx. According to various
embodiments of the present invention, the process of combustion,
managed by controlling the supply of a super-rich air-fuel mixture
in the precombustion chamber 31, supply of a lean mixture in the
vortex chamber cavity 109, and the introduction of a certain amount
of water into the combustion zone, can help ensure a sufficiently
low temperature of combustion, which is typically the significant,
if not dominant, factor in decreasing the NOx content in exhaust
gases, but that is also sufficiently high enough to prevent escape
of other unwanted or toxic exhaust gases.
[0074] Embodiments of the present invention also include methods
for providing flameless combustion of a fuel, in general, and for a
heavy viscous waste fuel, such as glycerol, in particular.
According to an embodiment of the present invention, such a method
can include forming a combustor apparatus 31 including a
precombustion chamber 33 and a main combustion chamber 35 (see,
e.g., FIG. 8), and controlling combustion (oxidation) of the fuel
to produce heat and/or to dispose of a waste fuel (see, e.g., FIG.
9), which can include controlling aeration of the primary fuel,
controlling the flow of the secondary fuel into the precombustion
chamber 33 (see, e.g., FIG. 10), and controlling primary combustion
airflow and primary combustion fuel flow (see, e.g., FIG. 11).
[0075] As perhaps best shown in FIG. 8, the combustor apparatus 31
can be formed by performing the steps of providing a main vortex
combustion chamber 35 having a main body 101 substantially
enclosing a main combustion chamber cavity 109 (block 301), and
interfacing a precombustion chamber 33 adapted to heat and at least
partially combust the primary fuel with the main combustion chamber
(block 303). The step of providing a main vortex combustion chamber
35 can include the substeps of: preselecting the value of an axial
length of a main combustion chamber cavity (block 305);
preselecting the value of an axial separation between a primary
fuel inlet 95 and the distal inner surface of the main combustion
chamber cavity 109 (block 307); preselecting the value of an axial
separation between a primary fuel inlet and a combustion exhaust
conduit inlet (block 309); and preselecting the value of an axial
separation between the inlet of a combustion exhaust conduit 115
and the distal inner surface of the main combustion chamber cavity
109 (block 311), in response to or otherwise based upon an amount
of time necessary to sufficiently combust the primary fuel, which
is further based upon fuel characteristics including viscosity,
mass flow, density, and in the end temperature of the primary fuel
expected to be utilized (combusted) in the combustor apparatus
31.
[0076] As perhaps best shown in FIG. 9, the combustion/oxidation of
the primary fuel can be controlled by inducing a first stage vortex
161 in a primary fuel-air mixture within the main body 47 of
precombustion chamber 33 (block 321); receiving the primary fuel
having the first stage vortex induced state within the main body
101 of the main combustion chamber 35 (block 323); inducing a
second stage vortex 163 in the received primary fuel-air mixture to
form a complex vortex pattern (block 325) which can include
expelling the partially combusted fuel in the primary fuel-air
mixture into the main combustion chamber cavity 109 through a
combination precombustion chamber exhaust outlet and main
combustion chamber fuel-air inlet 95, 95' (block 327); and
combusting (oxidizing) the primary fuel to produce heat and/or to
dispose of a "waste" primary fuel.
[0077] As perhaps best shown in FIG. 10, the step of inducing a
first stage vortex 161 can include the substeps of: aerating the
primary fuel prior to entry into the precombustion chamber 33 to
minimize a size of fuel droplets entering the precombustion chamber
(block 331); igniting a preferably gas-type secondary fuel within
the precombustion chamber 33 adjacent a flowpath of the primary
fuel to at least partially combust the primary fuel within the
precombustion chamber 33 (block 333); sensing a temperature of the
exhaust gas exiting the combustion exhaust conduit of the main
combustion chamber (block 335); and controlling the flow of the
secondary fuel into the precombustion chamber 33 responsive to the
exhaust gas temperature of the exhaust gas exiting the combustion
exhaust conduit 115 (block 337). Further, as perhaps best shown in
FIG. 11, the step of inducing the first stage vortex 161 can
further include the substeps of sensing massflow, density, and/or
momentum of the primary fuel (block 341), and controlling the
primary combustion fuel flow rate and/or pressure, and
correspondingly, the combustion airflow rate and/or pressure (block
343).
[0078] This patent application is related to U.S. Provisional
Application No. 61/052,076 by Anatoli Borissov, filed May 9, 2008,
titled "Apparatus And Methods For Providing Uniformly Volume
Distributed Combustion of Fuel and U.S. Pat. No. 5,839,270 by
Jirnov et al., titled "Sliding-Blade Rotary Air-Heat Engine with
Isothermal Compression of Air," incorporated by reference in its
entirety.
[0079] In the drawings and specification, there have been disclosed
a typical preferred embodiment of the invention, and although
specific terms are employed, the terms are used in a descriptive
sense only and not for purposes of limitation. The invention has
been described in considerable detail with specific reference to
these illustrated embodiments. It will be apparent, however, that
various modifications and changes can be made within the spirit and
scope of the invention as described in the foregoing
specification.
* * * * *