U.S. patent application number 12/817872 was filed with the patent office on 2010-10-07 for system, apparatus and method for combustion of metals and other fuels.
This patent application is currently assigned to GENERAL VORTEX ENERGY, INC.. Invention is credited to Alexander Borissov, Anatoli Borissov, Michael Jirnov.
Application Number | 20100251946 12/817872 |
Document ID | / |
Family ID | 38783575 |
Filed Date | 2010-10-07 |
United States Patent
Application |
20100251946 |
Kind Code |
A1 |
Borissov; Anatoli ; et
al. |
October 7, 2010 |
System, Apparatus and Method For Combustion of Metals and Other
Fuels
Abstract
A system, apparatus and method for the combustion of metals and
other fuels are provided. The system can include a fuel combustion
apparatus including a combustor having a combustion chamber for
burning ground particles from a fuel charge, and a fuel supply
apparatus for supplying the ground particles. The fuel supply
system can include a fuel charge holder assembly to house and store
the fuel charge, a grinder assembly including a grinder configured
to pulverize the fuel charge to produce a combustible fuel, and a
fuel charge linear feed assembly including a piston in contact with
the fuel charge to selectively bias the fuel charge into the
grinder to control the consumption rate. Exhaust from the
combustion chamber can be used in the incineration of radioactive,
chemical and mixed hazardous materials, and in the propulsion of a
vehicle in both an air or water environment.
Inventors: |
Borissov; Anatoli;
(Sugarland, TX) ; Borissov; Alexander; (Calgary,
CA) ; Jirnov; Michael; (Houston, TX) |
Correspondence
Address: |
BRACEWELL & GIULIANI LLP
P.O. BOX 61389
HOUSTON
TX
77208-1389
US
|
Assignee: |
GENERAL VORTEX ENERGY, INC.
Missouri City
TX
|
Family ID: |
38783575 |
Appl. No.: |
12/817872 |
Filed: |
June 17, 2010 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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11828188 |
Jul 25, 2007 |
7739968 |
|
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12817872 |
|
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60833175 |
Jul 25, 2006 |
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Current U.S.
Class: |
110/342 ;
110/232; 110/261; 110/301 |
Current CPC
Class: |
F23B 99/00 20130101;
F23B 7/00 20130101; F23K 1/00 20130101; F23B 2900/00003
20130101 |
Class at
Publication: |
110/342 ;
110/232; 110/261; 110/301 |
International
Class: |
F23K 1/00 20060101
F23K001/00; F23K 3/02 20060101 F23K003/02; F23L 7/00 20060101
F23L007/00 |
Claims
1. A system for combustion of a fuel, the system comprising: a
combustion apparatus comprising a combustor having a combustion
chamber in which a metal fuel is combusted, the combustor
including: a closed end portion having a metal fuel inlet extending
therethrough to receive the metal fuel, an open end portion having
an open end defining a combustion chamber exhaust through which
combusted metal fuel exits, an inner tubular member having an inner
tubular member main body substantially extending between the closed
end portion and the open end portion to form the combustion chamber
in which the combustion of the metal fuel occurs, the inner tubular
member main body having a plurality of apertures extending
therethrough each defining a cooling fluid outlet positioned to
allow the cooling fluid to enter the combustion chamber to thereby
enhance inner tubular member cooling and oxidation of the metal
fuel, an outer tubular member substantially surrounding the inner
tubular member to substantially enclose the inner tubular member,
and having an outer tubular member main body extending between the
closed end portion and the open end portion to form a cooling fluid
annulus between the inner tubular member main body and the outer
tubular member main body, the outer tubular member also having an
aperture extending therethrough to define a cooling fluid inlet to
receive the cooling fluid, and an igniter located at least
partially within the inner tubular member and positioned to ignite
the metal fuel in the combustion chamber adjacent the metal fuel
inlet in the closed end portion of the combustor; and a fuel supply
apparatus positioned to communicate the metal fuel to the metal
fuel inlet of the combustor, the fuel supply apparatus including: a
metal fuel charge holder assembly including a metal fuel charge
holder body axially bounded on either end to substantially enclose
the metal fuel charge holder body to thereby contain a metal fuel
charge, a carrier gas inlet positioned to receive a carrier gas
which carries the particles of metal fuel ground from the metal
fuel charge to the metal fuel inlet of the combustor, and a carrier
gas outlet positioned to receive the carrier gas and particles of
metal fuel carried by the carrier gas, a grinder assembly including
a grinder positioned to rotatably grind an end of the metal fuel
charge to thereby generate the particles of metal fuel to be
conveyed to the combustion chamber through the carrier gas outlet,
and a metal fuel feed assembly including a piston located within
the metal fuel charge holder assembly, a linear piston rod engaging
the piston, a feed motor to selectively feed portions of the metal
fuel charge into the grinder, and a drive train connected between
the feed motor and the piston rod and positioned to translate
rotational movement associated with the feed motor to linear
movement of the piston so that when the feed motor is operating,
the feed motor actuates the piston rod and piston to bias the metal
fuel charge toward the grinder.
2. A system as defined in claim 1, wherein the plurality of cooling
fluid outlets extend along a substantial portion of the inner
tubular member; wherein the annulus carries the cooling fluid from
the cooling fluid inlet along an outer periphery of the substantial
portion of the inner tubular member; and wherein the cooling fluid
entering the cooling fluid inlet includes one of the following:
air, gaseous oxygen, seawater, or liquid water.
3. A system as defined in claim 1, wherein the grinder assembly
includes a rotatable grinder shaft and a grinder motor positioned
to rotate the grinder shaft; and wherein the grinder comprises a
mill fixedly secured to the grinder shaft to rotate therewith, the
mill having a blade positioned thereon for engaging the metal fuel
charge as the mill rotates.
4. A system for combustion of a fuel, the system comprising: a
combustion apparatus including a combustor in which ground portions
of a fuel charge are combusted, the combustor comprising: a first
end portion having a fuel inlet extending therethrough to receive
the ground portions of the fuel charge, a second end portion having
an open end defining a combustion chamber exhaust through which
combusted fuel exits, an inner tubular member having an inner
tubular member main body substantially extending between the first
end portion and the second end portion to form a combustion chamber
in which the combustion of the ground portions of the fuel charge
occurs, the inner tubular member main body having at least one
aperture extending therethrough defining a cooling fluid outlet
positioned to allow the cooling fluid to enter the combustion
chamber to thereby enhance inner tubular member cooling and
oxidation of the ground portions of the fuel charge, and an outer
tubular member substantially surrounding the inner tubular member
to substantially enclose the inner tubular member, and having an
outer tubular member main body extending between the first end
portion and the second end portion to form a cooling fluid annulus
between the inner tubular member main body and the outer tubular
member main body, the outer tubular member also having an aperture
extending therethrough to define a cooling fluid inlet to receive
the cooling fluid.
5. A system as defined in claim 4, wherein the inner tubular member
includes a plurality of cooling fluid outlets extending along a
substantial portion of the inner tubular member; wherein the
annulus carries the cooling fluid from the cooling fluid inlet
along an outer periphery of the substantial portion of the inner
tubular member and to each of the plurality of cooling fluid
outlets; and wherein the combustor further includes an igniter
located at least partially within the inner tubular member and
positioned to ignite the ground portions of the fuel charge that
enter the combustion chamber through the fuel inlet in the first
end portion of the combustor.
6. A system as defined in claim 5, further comprising the fuel
charge, the fuel charge comprising a metal fuel charge
substantially comprising pressed aluminum particles having a
particle density of at least approximately 60%.
7. A system as defined in claim 5, wherein the combustor further
includes a nozzle region formed within the inner tubular member by
inclined walls extending axially inward from the first end adjacent
the fuel inlet to thereby increase the velocity of the fuel
particles and carrier agent and density of the fuel particles prior
to reaching the igniter.
8. A system as defined in claim 4, further comprising: a fuel
supply apparatus positioned to communicate ground portions of the
fuel charge to the fuel inlet of the combustor, the fuel supply
apparatus including: a fuel charge holder assembly including a fuel
charge holder body axially bounded on either end to substantially
enclose the charge holder body to thereby contain the fuel charge,
a carrier agent inlet positioned to receive a carrier agent which
carries the particles of fuel ground from the fuel charge to the
fuel inlet of the combustor, and a carrier agent outlet positioned
to receive the carrier agent and the particles of fuel ground from
the fuel charge and carried by the carrier agent, a grinder
assembly including a grinder positioned to rotatably grind an end
of the fuel charge to thereby generate the particles of fuel to be
conveyed to the combustion chamber, and a fuel feed assembly
including a piston located within the charge holder assembly, a
linear piston rod engaging the piston, a feed motor to selectively
feed portions of the fuel charge into the grinder, and a drive
train connected between the feed motor and the piston rod and
positioned to translate rotational movement associated with the
feed motor to linear movement of the piston so that when the feed
motor is operating, the feed motor actuates the piston rod and
piston to bias the fuel charge toward the grinder.
9. A system as defined in claim 8, wherein the grinder assembly
includes a rotatable grinder shaft and a grinder motor positioned
to rotate the grinder shaft; and wherein the grinder comprises a
mill fixedly secured to the grinder shaft to rotate therewith, the
mill having a blade positioned thereon for engaging the fuel charge
as the mill rotates.
10. A combustion apparatus comprising a combustor in which ground
portions of the fuel charge is combusted, the combustor including:
a first end portion having a fuel inlet extending therethrough to
receive the ground portions of the fuel charge; a second end
portion having an open end defining a combustion chamber exhaust
through which combusted fuel exits; an inner tubular member having
an inner tubular member main body substantially extending between
the first end portion and the second end portion to form a
combustion chamber in which the combustion of the ground portions
of the fuel charge occurs, the inner tubular member main body
having at least one aperture extending therethrough defining a
cooling fluid outlet positioned to allow the cooling fluid to enter
the combustion chamber to thereby enhance inner tubular member
cooling and oxidation of the ground portions of the fuel charge;
and an outer tubular member substantially surrounding the inner
tubular member to substantially enclose the inner tubular member,
and having an outer tubular member main body extending between the
first end portion and the second end portion to form a cooling
fluid annulus between the inner tubular member main body and the
outer tubular member main body, the outer tubular member also
having an aperture extending therethrough to define a cooling fluid
inlet to receive the cooling fluid.
11. An apparatus as defined in claim 10, wherein the inner tubular
member includes a plurality of cooling fluid outlets extending
along a substantial portion of the inner tubular member; and
wherein the annulus carries the cooling fluid from the cooling
fluid inlet along an outer periphery of the substantial portion of
the inner tubular member and to each of the plurality of cooling
fluid outlets.
12. An apparatus as defined in claim 11, wherein the combustor
further includes an igniter located at least partially within the
inner tubular member and positioned to ignite the ground portions
of the fuel charge that enter the combustion chamber through the
fuel inlet in the first end portion of the combustor.
13. An apparatus as defined in claim 12, wherein the igniter is
adapted to be fueled by a combustible gas.
14. An apparatus as defined in claim 12, wherein the combustor
further includes a nozzle region formed within the inner tubular
member by inclined walls extending axially inward from the first
end adjacent the fuel inlet to thereby increase the velocity of the
fuel particles and carrier agent and density of the fuel particles
prior to reaching the igniter.
15. An apparatus as defined in claim 12, wherein the fuel charge
comprises a metal fuel charge substantially comprising pressed
aluminum particles having a particle density of at least
approximately 60%.
16. An apparatus as defined in claim 12, wherein the fuel charge
comprises a metal fuel charge substantially comprised of
magnesium.
17. An apparatus as defined in claim 12, wherein the fuel charge
substantially comprises at least one of the following types of
metals: alkali metals, alkaline earth metals, transitional metals,
actinides, lanthanides, and poor metals.
18. An apparatus as defined in claim 12, wherein the fuel charge
substantially comprises coal.
19. A system for combustion of a fuel, the system comprising a
metal fuel combustion apparatus comprising: a central chamber; a
side wall surrounding the central chamber, the distance between at
least a portion of said side wall and said central chamber
increasing from the periphery with respect to radial distance; a
working fluid inlet means to receive a combustible working fluid; a
working fluid outlet means positioned adjacent to said working
fluid inlet means to discharge combusted working fluid; a cooling
fluid inlet means to receive cooling fluid through an annulus
between said side wall and said central chamber; a cooling fluid
outlet means to discharge said cooling fluid from said annulus
between said side wall and said central chamber and mix it with
said combustible working fluid to produce a combustible fuel
mixture; and a fuel ignition means to ignite said combustible fuel
mixture to produce said heated working fluid.
20. A method for combusting a fuel, the method comprising the steps
of: introducing a metal fuel charge into a metal fuel charge holder
of a metal combustion device, the metal fuel charge biased in
direct contact with a mechanical grinding device; initiating the
mechanical grinding device to pulverize the metal fuel charge
within the metal fuel charge holder to create a metal combustible
fuel; providing a carrier gas to carry the metal combustible fuel
from the mechanical grinder device to a combustion chamber of a
combustor of the metal combustion device, the combustor comprising
an inner tubular member including an inner tubular member main body
surrounding a substantial portion of the combustion chamber and
having a plurality of cooling fluid outlets positioned to allow a
cooling fluid to enter the combustion chamber, and an outer tubular
member including an outer tubular member main body surrounding the
inner tubular member to substantially enclose the inner tubular
member to form a cooling fluid annulus between the inner tubular
member main body and the outer tubular member main body and
including an aperture to receive the cooling fluid positioned to
deliver the cooling fluid to the annulus; and providing an
oxygenated cooling fluid through the aperture of the outer tubular
member main body and through each of the plurality of cooling fluid
outlets to cool the inner tubular member main body and provide an
oxygen source for combustion within the combustion chamber.
21. A method as defined in claim 20, further comprising the steps
of: pulverizing the metal fuel charge within the metal fuel charge
holder; and forming the metal combustible fuel, the metal
combustible fuel comprising ground metal combustible fuel
particles; and wherein the step of providing a carrier gas
comprises providing a non-oxidizing medium to thereby minimize
formation of an oxide layer around ground metal combustible fuel
particles prior to combustion in the combustion chamber of the
combustor, the non-oxidizing medium comprising a neutral carrier
gas.
22. A method as defined in claim 20, further comprising the steps
of: introducing the oxygenated cooling fluid into the combustion
chamber; introducing the metal combustible fuel carried by the
carrier gas into the combustion chamber adjacent an igniter
positioned to deliver a nonmetal combustible fuel; mixing the
oxygenated cooling fluid with the metal combustible fuel to create
a combustible fuel mixture including the metal combustible fuel;
and activating the igniter to initiate a metal combustion reaction
by the combustible fuel mixture to thereby generate a combusted
working fluid.
23. A method as defined in claim 22, wherein the step of activating
the igniter includes the steps of: introducing the nonmetal
combustible fuel in the combustion chamber, and igniting the
nonmetal combustible fuel in the combustion chamber; and wherein
the method further comprises the step of sustaining the metal
combustion reaction by continued pulverization of the metal fuel
charge and by continued positioning of the metal fuel charge in
direct contact with the mechanical grinding device until the metal
fuel charge has been substantially consumed.
Description
RELATED APPLICATIONS
[0001] This patent application is a continuation of and claims
priority to in the benefit of U.S. patent application Ser. No.
11/828,188, filed on Jul. 25, 2007, titled "System, Apparatus and
Method for Combustion of Metal and Other Fuels," which claims
priority to and the benefit of U.S. Patent Application No.
60/833,175, filed on Jul. 25, 2006, titled "System, Apparatus and
Method for Combustion of Metals," each incorporated herein by
reference in its entirety.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to the combustion of
materials, specifically to the high temperature combustion of
metals or other energetic fuel.
[0004] 2. Description of Related Art
[0005] The incineration of radioactive, chemical and mixed
hazardous materials requires high temperature combustors. In
addition to high temperature, the incinerator needs to produce
clean combustion. Aluminum, for example, is a very energetic
metallic fuel and may produce an adiabatic reaction temperature of
up to 10,600.degree. C. when it reacts with oxygen. The combustion
product, aluminum oxide, is a valuable product for many industrial
applications. The exhaust gas from aluminum combustion, for
example, is clean and does not contain any unburned hydrocarbons,
nitric or carbon oxides, or volatile organic components as
pollution from the combustion of hydrocarbons. The combustion of
aluminum in a water phase environment has a high temperature
exhaust stream of aluminum oxide in gaseous and solid phases and
water vapor. The lack of pollution from an aluminum combustion
process makes an aluminum combustor ideal for the incineration of
hazardous materials. The ability to use air or water as the
oxidizer for combustion is another very attractive feature of the
combustion of aluminum. Aluminum fuel could be used in underwater
incineration and also for the propulsion of various underwater
mechanical devices such as torpedoes or submarines.
[0006] Aluminum reacts with oxygen exothermically following the
reaction:
2Al(s)+3/2O.sub.2<->Al.sub.2O.sub.3(g) (A)
[0007] The calorimetric heat of reaction at 1 Bar is
(.DELTA.H.degree. (298K)=-404 kcal/mol). There is, however, a
problem with the direct burning of pure aluminum following this
reaction. In an oxygen environment (e.g., air), a strong layer of
Al.sub.2O.sub.3 coats an aluminum particle. The particle
temperature must be raised past the Al.sub.2O.sub.3 melting point
(2027.degree. C.) to obtain ignition. The ignition delay time
includes the time needed to heat, and then melt, the
Al.sub.2O.sub.3 layer, plus the diffusion time for the O.sub.2 to
reach the aluminum surface and react. When Aluminum vaporizes,
however, the kinetics is very rapid and no longer controls the
ignition process. The sum of all these times is comparatively
large, so particles escape with the high-speed gas flow from the
combustion chamber without chemical reaction.
[0008] A reduction of the ignition delay time and a lowering of the
ignition temperature, of aluminum is possible by oxidizing aluminum
with steam in the following the reaction:
2Al(s)+3H.sub.2O<->Al.sub.2O.sub.3(g)+3H.sub.2 (B)
[0009] The calorimetric heat of reaction at 1 Bar is
(.DELTA.H.degree. (298K)=-230 kcal/mol). In a steam atmosphere, a
hydroxide layer that is less protective than aluminum oxide covers
the aluminum particles. According to reaction (B), the ignition
temperature drops to 1323.degree.-1423.degree. C. shortening the
ignition time. This reaction is most attractive for underwater
power generation and propulsion, since it does not require air. The
oxidizer, seawater, is provided directly by the environment,
dramatically reducing on-board storage requirements. The power
density of reaction (B) is less than reaction (A) since the heat of
reaction, for the same 2 moles of aluminum, is less for reaction
(B).
[0010] Due to the high temperature of reaction (B), however, part
of the water dissociates, resulting in a release of oxygen. This
oxygen is used to burn the H.sub.2 produced by reaction (B) in the
following reaction:
3H.sub.2+3/2O.sub.2(g)<->3H.sub.2O(g) (.DELTA.H.degree.
(298K) at 1 Bar=-174 kcal/mol). (C)
[0011] Reactions (B) and (C) together produce the same energy
release as (A) with less restrictive ignition constraints. Reaction
(C) does not, however, need any external ignition source, since the
H.sub.2 produced in reaction (B) will be above its auto ignition
temperature in an O.sub.2 atmosphere.
[0012] Since the destruction of the aluminum oxide layer, by
melting, is critical to aluminum combustion, the rapid heating of
the particles is especially important. Heating can be produced by
friction in a strongly turbulent stream flow or by
convective/conductive heat transfer. In addition, sufficiently
intensive friction (shear) forces or head-on collisions between
particles could crack the oxide or hydroxide layer protecting the
pure aluminum and ignite it. These have been the traditional
mechanisms of heating aluminum prior to combustion. Through
estimation of all above effects, Applicants have recognized that
neither heating nor collisions effectively destroy the aluminum
oxide layer. This indicates that combustor designs based on these
mechanisms will not work efficiently.
[0013] Accordingly, recognized is the need for a combustion system
including a fuel supply apparatus which can supply a metal fuel to
a combustion apparatus having a relatively thin oxide layer and/or
remove at least portions of the oxide layer immediately prior to
consumption by the combustion apparatus without requiring a direct
heating application. Also recognized is the need for a combustion
system including a combustion apparatus capable of receiving such
energetic metal fuel and to provide a highly efficient combustion
of such energetic metal fuel that operate efficiently in either an
air or water environment.
SUMMARY OF THE INVENTION
[0014] In view of the foregoing, embodiments of the present
invention advantageously provide a system, apparatus, and methods
of combusting materials. Embodiments of the present invention also
advantageously provide a system, apparatus, and methods of
combusting metal, specifically combusting aluminum, magnesium, or
other energetic fuels. Embodiments of the present invention further
advantageously provide a system, apparatus, and methods of
providing such energetic metals for combustion from a charge
cylinder.
[0015] Embodiments of the present invention advantageously overcome
the difficulties of combusting metals such as aluminum. The
invention uses a mechanical process to crack the strong aluminum
oxide layer covering bare aluminum and provides a device and method
for combusting aluminum fuel. Particularly, embodiments of the
system can provide an aluminum fuel source including particles
aluminum having a very thin layer of aluminum oxide surrounding
each particle. At least portions of the aluminum oxide layer are
fractured or stripped away by a fuel supply apparatus during
grinding, and are immediately sent to a combustion apparatus where
the exposed aluminum metal is quickly and nearly completely
oxidized in the presence of ignition source, providing a
significant heat source for burning other external materials, while
forming a high-grade aluminum oxide byproduct that is nearly purely
aluminum oxide, and/or alternatively or simultaneously providing a
source of propulsion, depending upon the desired
implementation.
[0016] Notably, embodiments of the present invention, however,
could be used in the combustion of any metal or other high-energy
solid fuel, which one skilled in the art would deem suitable for
combustion. Although Aluminum provides unique properties
advantageous in the incineration of hazardous materials and
produces a commercially valuable exhaust product, this invention
should not be limited to the combustion of only aluminum, but
rather is envisioned in the combustion of any metal or energetic
solid fuel.
[0017] More particularly, an embodiment of the present invention
advantageously provides a system for the combustion of a metal. The
system includes a combustor having a combustion chamber in which a
metal fuel is combusted, and a fuel supply apparatus that
communicates the metal fuel to the combustion chamber. The
combustion chamber has an outer tubular member enclosing an inner
tubular member in which the combustion of the metal fuel occurs.
The combustion chamber also has an igniter positioned within the
inner tubular member that ignites the metal fuel. The combustion
chamber has a closed end with a metal fuel inlet extending
therethrough and opening into an interior of the inner tubular
member, and an open end defining a chamber exhaust through which
combusted metal fuel exits the working chamber.
[0018] The system for the combustion of metal can also be
configured so that the outer and inner tubular members define an
annulus therebetween. The combustion chamber can also include a
cooling fluid inlet extending through a sidewall of the outer
tubular member. The combustion chamber can also include a cooling
fluid outlet extending through a sidewall of the inner tubular
member. The annulus carrying a cooling fluid from the cooling fluid
inlet along an outer periphery of the inner tubular member to the
cooling fluid outlet.
[0019] According to an embodiment of the fuel supply apparatus, the
fuel supply apparatus includes a fuel charge holder assembly and a
fuel charge feed assembly. The fuel charge holder assembly has a
fuel charge holder body along with a pair of oppositely positioned
flanges enclosing a metal fuel charge. The fuel charge holder
assembly can enclose a grinder positioned to rotatably grind an end
of the, e.g., metal, fuel charge, and thereby generate particles of
metal fuel from the fuel charge to be conveyed to the combustion
chamber of the combustor. A carrier gas/fluid carries the particles
of metal fuel to the metal fuel inlet. The carrier gas/fluid may
be, for example, air, oxygen, water vapor, or combinations thereof.
More preferably, the carrier gas/fluid is, instead, a neutral gas
such as nitrogen, carbon dioxide, a noble gas, or combinations
thereof. A piston and piston rod assembly biases the metal fuel
charge toward the grinder so that the grinder continues to grind
against an end of the fuel charge as the grinder rotates. The fuel
charge feed assembly selectively actuates the piston and piston rod
assembly within the fuel charge holder assembly.
[0020] According to an embodiment of the fuel charge feed assembly,
the feed assembly has a feed motor and a feed shaft that is
connected to the piston rod. The feed shaft is connected to a gear
that translates rotational movement associated with the feed motor
to linear movement of the feed shaft, such that when the feed motor
is operating, the feed shaft actuates the piston rod and piston
assembly to thereby bias the fuel charge toward the grinder. In an
alternative embodiment, the piston rod is housed entirely within
the fuel charge holder assembly negating the need for a separate
feed shaft.
[0021] The system for the combustion of metal can also be
configured so that the grinder has a mill fixedly secured to a
grinder shaft that is rotated by a grinder motor. The mill can have
a blade positioned thereon for engaging the metal fuel charge as
the mill rotates. The system for the combustion of metal can also
be configured so that the charge holder body has a tubular housing
with a first flange closing a first end adjacent the grinder motor,
and a second flange closing a second end adjacent the fuel charge
feed assembly. The grinder shaft can extend from the mill through
the first flange to connect to the grinder motor. A first plurality
of seals can be positioned on the first flange to sealingly engage
an outer periphery of the grinder shaft so that the carrier
gas/fluid and the particles of metal fuel do not communicate to the
grinder motor. The piston rod can extend from the piston through
the second flange to connect to the feed shaft. A second plurality
of seals can be positioned on the second flange to sealingly engage
an outer periphery of the piston rod. In an alternative embodiment,
configured so that the piston rod is housed entirely within the
fuel charge holder assembly, the grinder driveshaft extends from
the grinder motor to the grinder through a pathway extending
through the piston rod and/or a piston rod extension.
[0022] The system for the combustion of metal can also be
configured so that the fuel charge feed assembly includes a pin
extending from the feed shaft, and a limit switch positioned so
that the pin engages the limit switch when the feed shaft is in a
predetermined location. The limit switch is in electrical
communication with the feed motor so that the limit switch causes
the feed motor to cease operating when the pin engages the limit
switch. The feed motor can be a variable speed motor that can
rotate in a first direction that causes the feed shaft to push the
piston and piston rod assembly toward the grinder, and a second
direction that causes the feed shaft to pull the piston and piston
rod assembly away from the grinder. The limit switch can be a pair
of spaced-apart switches. One of the pair of switches can be
positioned to engage the pin when the piston is adjacent the
grinder. The other of the pair of switches can be positioned to
engage the pin when the piston is in position for the fuel charge
holder assembly to receive the metal fuel charge. The pair of
switches thereby reducing damage to the fuel charge holder assembly
due to the feed motor over-driving the feed shaft in when pushing
and pulling the piston rod assembly.
[0023] According to an embodiment of the present invention, the
fuel supply apparatus for supplying a metal fuel to a combustion
chamber includes a fuel charge holder assembly and a fuel charge
feed assembly. The fuel charge holder assembly has a charge holder
enclosing a metal fuel charge. The fuel charge holder assembly
encloses a grinder positioned to rotatably grind an end of the
metal fuel charge, and thereby create particles of metal fuel to be
conveyed to the combustion chamber. The fuel charge holder assembly
receives a carrier gas/fluid that is adapted to carry the particles
of metal fuel to the combustion chamber. The carrier gas/fluid may
be, for example, air, oxygen, water vapor, or combinations thereof.
More preferably, the carrier gas/fluid is a neutral gas such as
nitrogen, carbon dioxide, a noble gas, or combinations thereof. The
fuel charge holder assembly also has a piston and piston rod
assembly that biases the metal fuel charge toward the grinder so
that the grinder continues to grind against an end of the fuel
charge as the grinder rotates. The fuel charge feed assembly
selectively actuates the piston and piston rod assembly of the fuel
charge holder assembly. The feed assembly has a feed motor and a
feed shaft that is connected to the piston rod. The feed shaft is
connected to a gear that translates rotational movement associated
with the feed motor to linear movement of the feed shaft such that
when the feed motor is operating, the feed shaft actuates the
piston rod and piston assembly to thereby bias the fuel charge
toward the grinder. The fuel supply apparatus can be configured so
that the grinder has a mill fixedly secured to a grinder shaft that
is rotated by a grinder motor. The mill can have a blade positioned
thereon for engaging the metal fuel charge as the mill rotates.
[0024] The fuel supply apparatus can be configured so that the
charge holder has a tubular housing with a first flange closing a
first end adjacent the grinder motor, and a second flange closing a
second end adjacent the fuel charge feed assembly. The fuel supply
apparatus can also include that the grinder shaft extends from the
mill through the first flange to connect to the grinder motor. A
first plurality of seals can be positioned on the first flange to
sealingly engage an outer periphery of the grinder shaft so that
the carrier gas/fluid and the particles of metal fuel do not
communicate to the grinder motor. The fuel supply apparatus can
include that the piston rod extends from the piston through the
second flange to connect to the feed shaft. A second plurality of
seals can be positioned on the second flange to sealingly engage an
outer periphery of the piston rod.
[0025] The fuel supply apparatus can be configured so that the fuel
charge feed assembly also has a pin extending from the feed shaft
and a limit switch. The limit switch can be positioned so that the
pin engages the limit switch when the feed shaft is in a
predetermined location. The limit switch can be in electrical
communication with the feed motor so that the limit switch causes
the feed motor to cease operating when the pin engages the limit
switch. The feed motor can be a variable speed motor that can
rotate in a first direction that causes the feed shaft to push the
piston and piston rod assembly toward the grinder, and a second
direction that causes the feed shaft to pull the piston and piston
rod assembly away from the grinder. The limit switch can include a
pair of spaced-apart switches. One of the pair of switches can be
positioned to engage the pin when the piston is adjacent the
grinder. The other of the pair of switches can be positioned to
engage the pin when the piston is adjacent the second flange and is
in position for the fuel charge holder assembly to receive the
metal fuel charge. The limit pin and switches thereby reducing
damage to the fuel charge holder assembly due to the feed motor
over-driving the feed shaft, when pushing and pulling the piston
rod assembly.
[0026] An embodiment of the present invention also advantageously
provides a fuel charge holder assembly that prepares metal fuel for
conveyance to a combustion chamber. The fuel charge holding
assembly includes a charge holder enclosing a metal fuel charge. A
grinder is positioned to rotatably grind an end of the metal fuel
charge and thereby create particles of metal fuel to be conveyed to
the combustion chamber. A carrier gas/fluid is adapted to carry the
particles of metal fuel to the combustion chamber. The carrier
gas/fluid may be, for example, air, oxygen, water vapor, or
combinations thereof. More preferably, the carrier gas/fluid is a
neutral gas such as nitrogen, carbon dioxide, a noble gas, or
combinations thereof. A piston and piston rod assembly biases the
metal fuel charge toward the grinder, so that the grinder continues
to grind against an end of the fuel charge as the grinder
rotates.
[0027] The fuel charge holder can include that the grinder has a
mill fixedly secured to a grinder shaft that is rotated by a
grinder motor. The mill can have a blade positioned thereon for
engaging the metal fuel charge as the mill rotates. The charge
holder can also have a tubular housing with a first flange closing
a first end adjacent the grinder motor, and a second flange closing
a second end adjacent the piston and piston rod assembly. The
grinder shaft can extend from the mill through the first flange to
connect to the grinder motor. A first plurality of seals can be
positioned on the first flange to sealingly engage an outer
periphery of the grinder shaft so that the carrier gas/fluid and
the particles of metal fuel do not communicate to the grinder
motor. The piston rod can extend from the piston through the second
flange. A second plurality of seals can be positioned on the second
flange to sealingly engage an outer periphery of the piston
rod.
[0028] Embodiments of the present invention also provide a method
for combusting an, e.g., metal fuel source comprising a fuel
charge. For example, according to an embodiment of a method, the
method can include the steps of introducing a metal charge into a
metal fuel charge holder assembly biased in direct contact with a
mechanical grinding device, initiating the mechanical grinding
device to pulverize the metal charge within the metal fuel charge
holder assembly and create a metal combustible fuel, providing a
carrier gas/fluid to carry the metal combustible fuel from the
mechanical grinding device to a combustion chamber of a combustor,
both introducing an oxygenated cooling fluid into the combustion
chamber, introducing the metal combustible fuel carried by the
carrier gas/fluid into the combustion chamber adjacent an ignitor,
e.g., burning a non-metal combustible fuel, and mixing the
oxygenated cooling fluid with the metal combustible fuel, to create
a combustible fuel mixture including the metal combustible fuel and
to initiate a metal combustion reaction with the combustible fuel
mixture to thereby generate a combusted working fluid. The method
also includes a step of sustaining the metal combustion reaction by
continued positioning of the metal charge in direct contact with
the mechanical grinding device and by continued pulverization of
the metal charge until the metal charge has been consumed.
BRIEF DESCRIPTION OF THE DRAWINGS
[0029] 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.
[0030] FIG. 1 is a schematic sectional view of a system for
combustion of a fuel including a fuel supply apparatus and a
combustion apparatus according to an embodiment of the present
invention;
[0031] FIG. 2 is a perspective view of the fuel supply apparatus
shown in FIG. 1 according to an embodiment of the present
invention;
[0032] FIG. 3 is sectional view of a portion of a grinder assembly
of the fuel supply apparatus shown in FIG. 1 according to an
embodiment of the present invention;
[0033] FIG. 4 is a sectional view of a grinder of the grinder
assembly taken along the 4-4 line of FIG. 3 according to an
embodiment of the present invention;
[0034] FIG. 5 is a schematic sectional view of a system for
combustion of a fuel including a fuel supply apparatus and a
combustion apparatus according to an embodiment of the present
invention;
[0035] FIG. 6 is a side schematic sectional view of a fuel
combustion apparatus according to an embodiment of the present
invention;
[0036] FIG. 7 is a schematic sectional view of the fuel combustion
apparatus taken along line 7-7 line in FIG. 6 according to an
embodiment of the present invention; and
[0037] FIG. 8 is a schematic sectional view of the fuel combustion
apparatus of FIG. 7 illustrating operation thereof according to an
embodiment of the present invention.
DETAILED DESCRIPTION
[0038] 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.
[0039] FIGS. 1-8 illustrate a system 30 for burning a high-energy
fuel. The system 30 includes two major components: a fuel
combustion apparatus 31 including a combustor 33 for burning ground
particles from a fuel charge 35; and a fuel supply apparatus 41 for
supplying fuel to the combustor 33, which includes a fuel charge
holder assembly 43 to house and store fuel charge 35, a grinder
assembly 45 including a grinder 47 typically housed within the
charge holder assembly 43 and configured to grind the fuel charge
35, and a fuel charge linear feed assembly 49 including a piston 50
in contact with the fuel charge 35 within the charge holder
assembly 43 to selectively bias the fuel charge 35 into the grinder
47.
[0040] More specifically, as illustrated in FIGS. 1-5, a fuel
supply apparatus 41 stores and crushes an, e.g., metal, fuel charge
35 for supplying fuel to a fuel combustion apparatus 31. As perhaps
best shown in FIG. 1, in an embodiment of the fuel supply apparatus
41, the supply apparatus 41 includes a charge holder assembly 43
which houses a grinder assembly 45 including a grinder 47 which
crushes or grinds/pulverizes the fuel charge 35 at a desired rate,
and to a desired particle size. The fuel charge 35, generally
formed of compressed metal particles, is used as combustible fuel.
In an embodiment of the fuel charge 35, the fuel charge 35 is
pre-pressed metallic particles formed into a barrel shape with an
axial length of about 150 mm, an outer diameter of e.g., about 100
mm, and includes an inner bore having an inner diameter of, e.g.,
about 30 mm to either provide a working fluid conduit or to provide
a driveshaft passageway, as described in more detail later. In an
embodiment of the fuel charge 35, the fuel charge 35 can also have
one or more axially oriented lock grooves 51 along the external
edge of the fuel charge 35 (8.times.5 mm) which, in combination
with one or more lock pins 53 positioned within the lock grooves
51, function to prevent rotation of the fuel charge 35 within an,
e.g., annular shaped, charge holder body 61 of the charge holder
assembly 43. Note, according to a preferred configuration, the fuel
charge 35 has between a 1:1 to 1.5:1 length-diameter ratio.
Although alternative length-diameter ratios are within the scope of
the present invention, when longer, e.g., metal, fuel charges are
to be built, considerable scatter of the volume content of solid
metal fuel particles is likely to occur along the length of the
fuel charge.
[0041] As perhaps best shown in FIG. 1, and as identified above,
the fuel charge 35 is arranged within the charge holder assembly 43
of supply apparatus 41. According to an embodiment of the charge
holder assembly 43, the charge holder assembly 43 includes an
elongate fuel charge holder body 61, for example, in the form of a
cylinder/tube, axially bounded on either end by a pair of axially
oppositely positioned flanges 63, 65, positioned to enclose the
charge holder body 61 to thereby contain the fuel charge 35. In the
illustrated embodiments, the charge holder body 61 has a
substantially tubular shape with an inner diameter of, e.g., 100
mm, and a length of, e.g., 175 mm, to accommodate one or more fuel
charges 35 and a supply apparatus piston 50, described in more
detail later. The charge holder body 61 can also have a wall width
of, e.g., 7 mm, to ensure sufficient safety in operating the unit
at working fluid pressures of up to approximately 4 MPa.
[0042] The length of the working zone of the charge holder body 61
can equal, e.g., about 150 mm, to accommodate, for example, a fuel
charge 35 having up to approximately 1200 grams of magnesium and/or
aluminum with, e.g., approximately a 60%-70% particle volume
content, and having a diameter of up to, e.g., approximately 100
mm, and an axial length of up to, e.g., approximately 150 mm. In
the exemplary embodiment of the charge holder body 61, the charge
holder body 61 is rated for a working fluid pressure of 12 MPa.
[0043] Note, although illustrated in the form of a circular
(annular) cylinder, the fuel charge 35 and the charge holder body
61 can each have other geometric shapes such as, for example, that
of a triangle, a star, a square, or others known to those skilled
in the art. Note also, although described as including magnesium
and/or aluminum, the fuel charge 35 can include various other
metals, individually, or in combination, which provide an energetic
metallic fuel source, such as, for example, various alkaline
metals, alkaline earth metals, transitional metals, actinides,
lanthanides, poor metals, and others known to those skilled in the
art. In an alternative embodiment of the present invention, the
fuel charge 35 can be replaced with and/or include other energetic
fuel sources, such as, for example, coke, coal, or coal billets.
Note further, although described as a single unit, the fuel charge
35 can include a plurality of fuel charges 35 axially stacked
within the charge holder body 61.
[0044] As perhaps best shown in FIG. 1, the supply apparatus 41
also can include an adjustable fuel charge linear feed assembly 49
located adjacent to and/or partially within one end of the charge
holder assembly 43. The adjustable fuel charge linear feed assembly
49 includes piston 50 positioned within the confines of the charge
holder body 61. In the embodiment illustrated in FIGS. 1-2, the
piston 50 is attached to a linear feed piston rod 71, extending,
for example, through a rod receiving aperture 73 in the flange 63,
which forms the proximal end of the charge holder assembly 43. The
flange 63 can include an insulated packing seal assembly 75, which
includes at least one, but preferably a plurality of annular
recesses extending along an outer diameter of the rod receiving
aperture 75 to receive a corresponding plurality of annular packing
seals 77.
[0045] The linear feed assembly 49 also includes, for example, a
DC, electric motor 81 or other suitable drive motor, kinematically
associated with, for example, a worm gear 83, which rotates an
associated worm nut (not shown) to thereby bring about the linear
motion of a feed shaft 85, which can be rigidly attached to rod 71
of piston 50. To prevent piston 50 and piston rod 71 from cranking
over, i.e., inadvertently over-extending piston 50 distally through
the charge holder body 61 and into the fuel charge grinder assembly
45, described later, an embodiment of the supply apparatus 41
includes a pin 91 that is fixed on or otherwise connected to rod 71
so that the pin 91 moves along a groove 93 extending axially along
a portion of the power frame 95 of the supply apparatus 41. In a
preferred configuration, pin 91 actuates one or more limit switches
97, 99, positioned along the power frame 95 to restrain the linear
motion of the rod 71 by turning off the power supply to electric
motor 81, when in contact therewith.
[0046] In a preferred configuration, the power frame 95 carries a
metal ruler 100, located on the side surface of groove 93, and
positioned such that pin 91 serves as a moving pointer which
functions to help the user to visually determine the position of
the piston 50 and rod 71, to thereby determine the position and/or
quantity remaining of the fuel charge 35 within the charge holder
body 61.
[0047] The proximal-most flange 63 of the charge holder assembly 43
can include at least one, but preferably, a plurality of channels
interfaced on an external surface with a corresponding number of
connection fittings 101, 102, 103, 104. In a preferred
configuration, there are at least four channels, with the channel
111 interfaced with fitting 101 supplying a carrying gas agent
(which may be a non-oxidizing neutral gas) which travels through
cavity 121, then through pathway 123, then through fuel charge
inner bore 125, and to the proximal side of grinder 47, to carry
ground fuel charge particles ground from the fuel charge 35 by
grinder 47 through conduit 127 to the combustor 33. The channel
interfaced with fitting 102, if so configured, can supply a neutral
gas in order to create a non-oxidizing medium in the working volume
of charge holder body 61. The fitting 103 can provide a receptacle
to hook up a bypass line connecting the combustion apparatus 31
with the charge holder assembly 43 in order to dampen an
overpressure, which may occur at the time of starting up the
combustor 33. The fitting 104 and associated channel can be used to
access an internal pressure associated with portions of the supply
apparatus 41 to allow a user to take pressure measurements
thereof.
[0048] As perhaps best shown in FIGS. 3 and 4, the fuel supply
apparatus 41 can include a mechanical fuel charge grinder assembly
45 enclosed by or otherwise interfaced with the fuel charge holder
assembly 43 to grind the fuel charge 35 contained within the charge
holder body 61. According to the exemplary embodiment of the
present invention, the mechanical fuel charge grinder assembly 45
includes a mechanical mill drive motor assembly (mill drive) 131
interfaced with a mechanical fuel charge grinder 47 positioned
adjacent the distal end of the charge holder body 61 to receive and
grind portions of the fuel charge 35 extended into the grinder 47
by the fuel charge linear feed assembly 49. As perhaps best shown
in FIG. 4, the mechanical fuel charge grinder 47 can include a
three-bladed face mill 133 carried by a portion of shaft 135
extending through a shaft receiving aperture 137 in the flange 65.
The flange 65 can include an insulated packing seal assembly 141,
which include at least one, but preferably a plurality of, annular
recesses extending along an outer diameter of the shaft receiving
aperture 137 to receive a corresponding plurality of packing seals
143. The packing seals 143 seal off the portion 145 of the mill
drive 161 adjacent the grinding chamber 147 enclosing the mill 133
and receiving shaft 135 and the portion 149 of the mill drive 131
so that ground fuel does not exit the grinding chamber 147 or
charge holder body 61 into motor 151 through the front cover 153.
Note, in the illustrated configuration, flange 65 is integrated
with the front cover 153 of the electric motor 151 positioned along
an axial extent of the mechanical fuel charge grinder assembly
45.
[0049] As shown in FIG. 5, in another configuration, the drive
motor 151' is offset and a drive belt 161, drive chain, or other
transmission device known to those skilled in the art, is used to
drive the drive shaft 135', and thus, mill 133'.
[0050] In both the fuel supply apparatus 41 configured as shown in
FIG. 1 and in the fuel supply apparatus 41' as shown in FIG. 5,
grinding of the fuel charge 35 is performed by the cutting blades
163 (FIG. 4) of mill 133 within the grinding chamber 147 (FIG. 3)
connected by channel 111, 111' with the carrier agent hook up
fitting 101, 101', and/or a separate neutral gas hook up fitting
102 connected to its associated channel, to thereby provide a
pressurized delivery of ground, e.g., metal, fuel to the combustor
33. That is, fine solid fuel particles coming off the end of the
fuel charge 35 are carried out by the flow of the carrier agent, or
carrier gas/fluid, from the grinding chamber 147 via fittings 171,
172, 173 as shown in FIG. 4, or directly through conduits/annulus
175 as shown in FIG. 5. The carrier gas/fluid may be, for example,
air, oxygen, water vapor, or combinations thereof. More preferably,
the carrier gas/fluid is a neutral gas such as nitrogen, carbon
dioxide, a noble gas, or combinations thereof, or others known to
those skilled in the art, which will function to minimize the
formation of an oxide layer around the ground particles prior to
combustion in the combustor 33.
[0051] In the embodiment illustrated an FIGS. 1-4, having, e.g.,
three fittings 171, 172, 173, the apparatus 41 can supply fuel to
one or several metal combustors 33 which can be hooked up via
connection fittings 171, 172, 173, by branch pipes with, e.g., an
inner diameter of 8 to 10 mm and, e.g., connection thread M
16.times.1.5. That is, a separate supply line 127 (FIGS. 1 and 2)
can be connected to each of the fittings 171, 172, 173, to supply
ground fuel particles to up to three clients or combustors 33.
Note, when servicing several clients or several combustors 33, it
is generally preferred to maintain equal flow resistance of supply
lines 127. When the supply apparatus 41 is to serve only one client
or supply fuel to only one combustor 33, fittings 172 and 173 are
normally plugged. Alternatively, when the supply apparatus is to
serve only one client or supply fuel to only one combustor 33, the
ground fuel from one or more of the fittings 171, 172, 173, can be
channeled through an conduit/annulus 175 between the fuel charge
holder body 61 and the proximal drive shaft support 177, as shown
in FIG. 5. The drive shaft support 177 can include at least one
annular recess extending along an outer diameter of the drive shaft
support 177 to receive an annular seal 178 positioned to dampen
vibrations between the drive shaft support 177 and the fuel charge
holder body 61.
[0052] In the embodiment of the charge holder assembly 43
illustrated in FIG. 1, the flanges 63, 65, and charge holder body
61 are tightened by fasteners (e.g., pins) 181 (see, e.g. FIG. 2)
to enhance the integrity of the fuel charge holder assembly 43.
Further, as noted previously, a plurality of lock pins 53 can be
arranged along the inner surface of the charge holder body 61
immediately adjacent to the flange 65 in order to lock fuel charge
35 within the charge holder body 61. Note, in the embodiment of the
fuel charge holder assembly 43' shown in FIG. 5, lock pins 53 can
be arranged along the inner surface of the charge holder body 61
immediately adjacent to the proximal shaft support 177 in order to
lock fuel charge 35 within the charge holder body 61. In this
embodiment of the fuel supply apparatus 41', shaft 135' extends
through flange assembly 65', which can be configured similar to
that described with respect to FIG. 3.
[0053] The supply apparatus 41, 41', are designed for storing and
crushing the metal or other fuel charges 35 that have been, for
example, pre-pressed from, e.g., powdered fuel of the required
chemical composition, having a pre-assigned or selected particle
size and packing density, with subsequent conveyance of the
particles by a gas carrier into the combustor 33. In embodiments of
the fuel supply apparatus 41, 41', the supply apparatus typically
has the following technical specifications:
TABLE-US-00001 metal fuel charge diameter 100 mm; metal fuel charge
length, max. 150 mm; gas carrier allowable pressure, max. 4 MPa;
gas carrier flow rate (% of solid fuel per 15-20% second
consumption) linear charge travel speed in the fuel tank 1-5 mm/s
weight, max. 30 kg dimensions 1000 .times. 250 .times. 250 mm mean
time between failures, min. 6 hours specified life, min. 15
hours
[0054] The consumption rate of the fuel charge 35 can be adjusted
by way of adjusting the linear speed of charge motion of the fuel
charge 35 in the charge holder body 61. Changing the linear speed
of piston 50, and thus, the linear motion (speed) of fuel charge 35
can be through use of the principle of adjusting revolutions of the
electric motor 81, via the worm gear 83 (see, e.g., FIG. 1), which
moves the feed shaft 85 which, in a preferred configuration, is
rigidly attached to the displacement (linear feed) piston rod 71,
or through one or more gears 83' (see, e.g., FIG. 5), which can
directly move linear feed piston rod 71'. The motor 81 can have a
nominal rotational speed of, e.g., n=3000 rpm. According to the
exemplary configuration, the gear 83, 83', have a reduction ratio
of, e.g., k=32. Also according to the exemplary configuration, the
linear speed of fuel charge 35 in the charge holder body 61 is
maintained within, for example, 1 to 5 mm/s, according to fuel
consumption requirements.
[0055] In embodiments of the grinder 47, the three-blade face mill
133 that grinds the fuel charge 35 is driven with motor 151, 151',
which, according to a preferred configuration, is a 600 W
three-phase induction motor with a nominal rotational speed of
n=3000 rpm. Note, however, other types of AC or DC motors are
within the scope of the present invention. Additionally, according
to a preferred configuration, the rotational direction of the shaft
135, 135', is clockwise (when viewed from the cutter side).
[0056] As will be readily appreciated by those skilled in the art,
the per-second consumption of the fuel charge 35 depends on the
physical parameters of the fuel charge 35 being used; particularly
on the specific weight of the particles and on the dispersion fuel
particles fuel charge fill-in coefficient; and has a linear
dependency upon the linear speed of the feed piston 50.
[0057] As perhaps best illustrated in FIGS. 6-8, the fuel
combustion apparatus 31 includes a combustor 33 having an outer
sidewall or outer tubular member 201. The outer tubular member 201
substantially encloses an inner sidewall or inner tubular member
203, thereby defining an annulus 205 therebetween. The inner
surface of the inner tubular member 203, in turn, describes a
working or combustion chamber 223 in which the combustion of the
metal fuel occurs. A working fluid or fuel inlet 207 extends
through a closed first end of the combustor 33 to receive a working
fluid generally composed of the ground (pulverized) metal fuel
(typically ground from a fuel charge 35), along with the carrier
gas/fluid agent used to carry the particles to the inlet 207.
Correspondingly, a working fluid outlet or exhaust 209 is located
at an open end of the combustor 33. The ground fuel particles and
the carrier gas/fluid agent from the fuel supply apparatus 41, 41',
enter the combustion chamber 223 through fuel inlet 207 for
combustion.
[0058] According to the exemplary embodiment of the fuel combustion
apparatus 31, a nozzle region 211 is formed within the inner
tubular member 203 by inclined walls 208 extending axially away
from the closed first end, and both radially and axially inward. In
an alternative embodiment of an injector nozzle, a separate fitting
(not shown) having a cylindrical-conical shape can be positioned
within inner tubular member 203 as would be understood by those
skilled in the art.
[0059] An igniter 213 is positioned axially downstream from nozzle
region 211, within inner tubular member 203 for igniting the ground
fuel particles received from the supply apparatus 41, 41' and
carried by the carrier fluid. Igniter 213 may be a propane torch or
other appropriate source of ignition as understood by those skilled
in the art, such as, for example, an electrode providing an
electrical arc or spark. Regardless of the configuration, the
igniter 213 can include a temperature sensitive retraction
mechanism as would be understood by those skilled in the art
configured to substantially retract major portions of the igniter
from within the combustion chamber 223 once the temperature within
the chamber reaches a preselected temperature.
[0060] As will be readily appreciated by those skilled in the art,
the nozzle region 211 can focus the flow of the ground fuel
particles and the carrier gas/fluid agent through the inner tubular
member 203, such that the velocity of the fuel particles and
carrier gas/fluid increases and is more compact when reaching
igniter 213. The combusted fuel particles and carrier gas/fluid
exit combustion chamber 223 through exhaust 209 after combustion
within the inner tubular member 203.
[0061] As perhaps best shown in FIGS. 7-8, one or more Cooling
fluid inlets 215, adapted to be connected to a supply line 217 or
fluid capturing dam (not shown), is formed through the outer
tubular member 201, which opens into annulus 205. In a
configuration of the cooling fluid inlet 215, the size of the
cooling fluid inlet 215 can be adjusted to control cooling fluid
pressure, and thus, cooling fluid mass flow rate. In addition to
adjusting the size of the orifice of the inlet 215, pressure in the
supply line 217 can be controlled, for example, by a controller
(not shown) as would be understood by one skilled in the art. Note,
although cooling inlet 215 is shown positioned near exhaust 209,
such cooling inlet can be positioned in alternative locations along
the length of outer tube 201.
[0062] Annulus 205 carries a cooling fluid from the cooling fluid
inlet 215 along the outer periphery of the inner tubular member 203
to at least one cooling fluid outlet 221 extending through inner
tubular member 203, to allow the injection of the cooling fluid
from within the annulus 205 and then within the inner tubular
member 203. Beneficially, the cooling fluid has multiple functions.
In the annulus 205, the cooling fluid enhances cooling of the inner
tube 203. In the combustion chamber 223, it both enhances cooling
the inner tube 203, particularly during passage therethrough, and
provides an oxidizing source to support combustion of the
combustible fuel particles. Note, additionally or alternatively,
cooling fans or ribs (not shown) extending from inner tube 203 can
extend into annulus 205 to enhance sinking heat from the inner tube
203.
[0063] In a preferred configuration of the combustor 33, a
plurality of cooling fluid outlets 221 extend through inner tubular
member 203 to inject the cooling fluid into the flow of the fuel
particles and carrier gas/fluid being combusted/to be combusted
within combustion chamber 223. As noted above, besides cooling
inner tubular member 203, the cooling fluid can act as an oxidizer
that supports combustion of the fuel particles within combustion
chamber 223. Correspondingly, the cooling/oxidizing fluid may be,
for example, air, oxygen, water vapor, seawater, or other suitable
fluids. In the case of water vapor, water may be introduced through
cooling fluid inlet 215 as liquid water or steam, which would
become dissociated water vapor when exposed to high temperatures
within combustion chamber 223.
[0064] In operation, as perhaps best shown in FIGS. 1 and 5, a fuel
charge 35 is positioned within a fuel charge holder body 61 and is
engaged by a piston 50. A drive motor 151, 151', is powered to
begin rotating grinder 47 via rotatable driveshaft 135, 135'. A
motor 81 is selectively powered at a selected speed to begin a
linear advancement of the piston 50, and thus, linear advancement
of the fuel charge 35 into blades 163 of mill 133 of grinder 47.
Further, as the fuel charge 35 is being ground (pulverized) by
grinder 47, i.e., returned to art form, a carrier agent is supplied
under pressure to grinder chamber 147 (FIG. 3) via channel 111,
111', to thereby carry fuel particles ground from the fuel charge
35 through a conduit such as, for example, tube/supply line 127 or
conduit/annulus 175 to the inlet 207 of one or more combustor 33.
Beneficially, using aluminum as an example metal fuel, the fuel
charge 35 can comprise pulverized aluminum particles compressed to
form the fuel charge 35 to have a particle density of upwards of
60%-70%. Also beneficially, the aluminum particles can have a
relatively thin coating of aluminum oxide analogies to that of an
eggshell surrounding an egg. As the grinder 47 grinds the fuel
charge 35, at least portions of the aluminum oxide layer/coating
are fractured/remove, exposing the aluminum particle core
(non-oxidized aluminum). I.e., removal of the aluminum oxide layer
allows for direct access by an oxidizer to the aluminum formerly
encased by the aluminum oxide layer. Hence, in the preferred
configuration, the carrying agent is a neutral fluid which inhibits
oxidation until the time when the aluminum particles are delivered
inside the combustion chamber 223 where the cooling fluid provides
for oxidation of the aluminum, under ignition conditions having a
much lower heat requirement that was required by the state of the
art to melt the aluminum oxide.
[0065] As also shown in FIG. 8, after being ground, the carrier
agent then carries the ground aluminum particles out of the
grinding chamber 147 and into the combustion chamber 223, through
inlet 207 of the combustor 33 and through nozzle region 211 where
the particles are concentrated and ignited by the igniter 213 in
the presence of the oxygen carrying cooling fluid. Note, during
testing, utilizing a 7.5 g/s flowrate of aluminum particles, using
propane as the ignition source of igniter 213, and using air as the
cooling fluid, a cooling air flow rate of 15-20% of that of the
aluminum flow rate was found to be adequate. Note also, during such
testing, the reaction zone resulting from the combustion within the
combustion chamber 223 included a length extending in excess of 20
calibers in the axial direction past the end of the combustor
exhaust 209 with a width of the reaction zone being about 10
calibers, and a temperature approaching approximately
10,000.degree. C. The reaction zone was also found to be both
stable to flow and temperature disturbances.
[0066] Beneficially, such reaction zone can be readily utilized,
for example, for the thermal destruction of hazardous materials or
other uses known to those skilled in the art, including propulsion,
for example. Further, for the destruction of a large volume of
hazardous material or for other heating or propulsion requirements,
multiple combustors can be supplied fuel either by a single fuel
supply apparatus or by multiple fuel supply apparatus each
servicing one or more combustor 33.
[0067] Also beneficially, due to the small size of the aluminum
particles and the ready access by the oxidizer, e.g., oxygen, in
the cooling fluid, the resulting exhaust stream not only provides
necessary operational characteristics, e.g., propulsion and/or
heat, but a potentially commercially valuable exhaust
product--high-grade aluminum oxide.
[0068] This patent application is related to U.S. patent
application Ser. No. 11/828,188, filed on Jul. 25, 2007, titled
"System, Apparatus and Method for Combustion of Metal and Other
Fuels," and U.S. Patent Application No. 60/833,175, filed on Jul.
25, 2006, titled "System, Apparatus and Method for Combustion of
Metals," each incorporated herein by reference in its entirety.
[0069] 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.
For example, although the description primarily focuses on metal
fuel charges containing pulverized metal fuel particles, as noted
previously, other non-metal fuels can be utilized in both the fuel
supply apparatus and the combustion apparatus, separately, or in
combination. Also, for example, the combustor can include a
stationery or divertible exhaust nozzle to provide acceleration and
directional control of exhausted fuel to enhance propulsion, when
so employed. Further, for example, the system can include a
controller for controlling grinding speed of the grinder, the
strength of the ignition source, and/or the amount of cooling fluid
entering the annulus between the inner and outer combustor
tubes.
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