U.S. patent application number 12/432568 was filed with the patent office on 2009-12-03 for systems and methods relating to fireplaces comprising modular feed and combustion systems for biomass solid particulate fuels.
Invention is credited to Timothy Randall Carlson.
Application Number | 20090293860 12/432568 |
Document ID | / |
Family ID | 41255761 |
Filed Date | 2009-12-03 |
United States Patent
Application |
20090293860 |
Kind Code |
A1 |
Carlson; Timothy Randall |
December 3, 2009 |
SYSTEMS AND METHODS RELATING TO FIREPLACES COMPRISING MODULAR FEED
AND COMBUSTION SYSTEMS FOR BIOMASS SOLID PARTICULATE FUELS
Abstract
Fireplaces suitable for outdoor patio and built-in fireplaces,
fire pits and the like that burn biomass solid particulate fuels
wherein such fireplaces comprise at least one feed system that is
modular which can feed from at least one feed bin onto one or more
burn grates. This allows for greater control over aspects such as
heat output, energy generation, mixing different varieties of fuels
such as flavored pellets or chips when used in a barbecue grill or
smoker or other food preparation device, and if desired a wider,
more full flame for example where aesthetic considerations are
important.
Inventors: |
Carlson; Timothy Randall;
(Snohomish, WA) |
Correspondence
Address: |
GRAYBEAL JACKSON LLP
155 - 108TH AVENUE NE, SUITE 350
BELLEVUE
WA
98004-5973
US
|
Family ID: |
41255761 |
Appl. No.: |
12/432568 |
Filed: |
April 29, 2009 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61048646 |
Apr 29, 2008 |
|
|
|
Current U.S.
Class: |
126/501 ;
126/516; 432/1 |
Current CPC
Class: |
F23B 40/08 20130101;
F23K 2203/202 20130101; F23B 50/12 20130101; F24B 13/04 20130101;
F23K 2203/104 20130101; F23L 1/02 20130101; F23N 2239/02
20200101 |
Class at
Publication: |
126/501 ;
126/516; 432/1 |
International
Class: |
F24B 1/199 20060101
F24B001/199; F24B 1/189 20060101 F24B001/189; F24B 13/00 20060101
F24B013/00 |
Claims
1. A fireplace fuel feed system comprising: at least one fuel
hopper configured to hold and dispense a supply of at least one
bio-mass solid particulate fuel, the hopper communicating via at
least one discharge opening with a fireplace combustion chamber
comprising at least one burn pot and at least one combustion grate,
the system further comprising at least one fuel feed mechanism that
conveys the fuel from the hopper to the combustion grate of the
burn pot in the fireplace, the hopper, fuel feed mechanism and burn
pot configured to cooperatively evenly feed and evenly combust the
bio-mass solid particulate fuel in the burn pot, and at least one
control operatively connected to the fuel feed mechanism and
configured to control at least the amount and timing of transfer of
the bio-mass solid particulate from the hopper to the burn pot.
2. The system of claim 1 wherein the fuel feed mechanism is a
multi-directional fuel feed mechanism and the multi-directional
fuel feed mechanism and the hopper are cooperatively configured to
move the fuel in multiple directions to the at least one discharge
opening.
3. The system of claim 1 wherein at least one of the control, the
hopper or the fuel feed mechanism is configured to automatically
intermittently, periodically convey a uniform amount of the fuel to
the burn pot.
4. The system of claim 1 wherein at least one of the control, the
hopper or the fuel feed mechanism is configured to automatically
continuously convey a uniform amount of the fuel to the burn
pot.
5. The system of claim 1 wherein the fuel feed mechanism is an
auger comprising flightings along a shaft.
6. The system of claim 1 wherein the fuel feed mechanism is at
least one of a continuous loop device or a non-turning agitating
device.
7. The system of claim 1 wherein the hopper is a multi-chamber fuel
hopper.
8. The system of claim 1 wherein the system further comprises at
least one discharge chute configured to carry the fuel between the
hopper and the combustion chamber.
9. The system of claim 1 wherein the fuel feed mechanism has a
single fuel entry point and at least two discharge openings.
10. The system of claim 1 wherein the fuel feed mechanism has at
least two fuel entry points and a single discharge opening
communicating with the combustion chamber.
11. The system of claim 1 wherein the combustion chamber is sized
and configured for a residential or commercial heat or energy
generation fireplace.
12. The system of claim 1 wherein the system further comprises a
regulatable, variable source of increased combustion air.
13. The system of claim 12 wherein the regulatable, variable source
of increased combustion air is an air fan.
14. The system of claim 12 wherein the regulatable, variable source
of increased combustion air is a compressed air source.
15. The system of claim 1 wherein the effective direction of the
fuel feed mechanism can be reversed.
16. A fireplace comprising a fireplace fuel feed system according
to claim 1.
17. A method of burning a bio-mass solid particulate fuel in a
fireplace, the method comprising: providing a fireplace comprising
at least one fuel hopper configured to hold and dispense a supply
of at the least one bio-mass solid particulate fuel, the hopper
communicating via at least one discharge opening with a fireplace
combustion chamber comprising at least one burn pot and at least
one combustion grate, the system further comprising at least one
fuel feed mechanism that conveys the fuel from the hopper to the
combustion grate of the burn pot in the fireplace; controllably
engaging the fuel feed mechanism to evenly feed the bio-mass solid
particulate fuel to the combustion chamber; and evenly combusting
the bio-mass solid particulate fuel in the fireplace combustion
chamber.
18. The method of claim 17 wherein the fuel feed mechanism is a
multi-directional fuel feed mechanism and the method further
comprises moving the fuel in multiple directions to the at least
one discharge opening.
19. The method of claim 17 wherein the method further comprises
automatically intermittently, periodically conveying a uniform
amount of the fuel to the burn pot.
20. The method of claim 17 wherein the method further comprises
automatically continuously conveying a uniform amount of the fuel
to the burn pot.
21. The method of claim 17 wherein the fuel feed mechanism is an
auger and the method further comprises moving the fuel to the
discharge opening using flightings along a shaft of the auger.
22. The method of claim 17 wherein the fuel feed mechanism has a
single fuel entry point and at least two discharge openings and the
method further comprises moving the fuel in multiple directions
from the single entry point toward the at least two discharge
openings.
23. The method of claim 17 wherein the fuel feed mechanism has at
least two fuel entry points and a single discharge opening
communicating with the combustion chamber and the method further
comprises moving the fuel in multiple directions from the at least
two fuel entry points toward the single discharge opening.
24. The method of claim 17 wherein the burning takes place in a
residential or commercial heat or energy generation fireplace.
25. The method of claim 17 wherein the method further comprises
regulatably, variably providing increased combustion air to the
combustion chamber during the burning.
26. The method of claim 17 wherein the method further comprises
reversing the effective direction of the fuel feed mechanism during
the burning.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] The present application claims the benefit of copending U.S.
Provisional Patent Application Ser. No. 61/048,646, filed Apr. 29,
2008, which application is incorporated herein by reference in its
entirety.
BACKGROUND
[0002] Present known fireplace systems burn either gas or cut and
split cord wood and use manual lighting in the case of the cord
wood burning units and the running of gas lines or the presence of
propane tanks in the case of the gas units. Additionally, once lit
a cord wood unit needs to be doused with water if early fire
extinguishment is desired, while gas systems raise a concern for
gas explosions.
[0003] Further, cord wood burning systems are subject to having
non-uniform fuel disbursement in the combustion chamber. This
non-uniform fuel results in uneven combustion, which in turn
results in variable temperatures, raised pollution levels, and
excessive smoke and soot.
[0004] Thus, there has gone unmet a need for improved systems,
methods, etc., that eliminate the cost and potential danger of gas
fireplaces while providing for one or more of automatic and uniform
fuel feeding and combustion, automatic ignition, and/or easily
controllable heat output (preferably both amount of heat and
distribution of heat within the fireplace).
[0005] The present systems and methods, etc., provide these and/or
other advantages, including for example one or more of
substantially constant temperatures, lower pollution levels,
reduced smoke and soot, and enhanced aesthetic values, e.g. more
attractive flame patterns.
SUMMARY
[0006] The present systems, methods, etc., are directed to
fireplaces comprising a modular combustion system to feed and
combust one or more biomass solid particulate fuels. The fireplaces
have at least one solid fuel-fired combustion chamber, and can have
a single centrally located fuel bin opening or multiple openings
for efficient, aesthetically pleasing, no smoke and low pollution
combustion. In certain embodiments, one or more fuel bins provide
fuel to a mechanical or gravity-based fuel feed mechanism which
provides fuel at a controlled rate to the combustion chamber. In
some embodiments, at least one igniter, typically an automated
igniter, ignites the fuel and at least one oxygen source such as a
draft fan or compressed air source provides a proper air mixture to
the combustion chamber for clean combustion. For multiple
combustion chambers, multiple draft fans or compressed air sources
may be used, for example in larger sized appliances.
[0007] The biomass solid particulate fuels include but are not
limited to wood pellets, wood chips, corn, grain, briquettes, small
grain and cellulosic residues, fruit pits, etc.
[0008] The fireplaces can be configured in a variety of
configurations including decorative configurations such as patio
fireplaces, built-in fireplaces fire pits and patio heaters.
[0009] A fireplace fuel feed system comprising: at least one fuel
hopper configured to hold and dispense a supply of at least one
bio-mass solid particulate fuel, the hopper communicating via at
least one discharge opening with a fireplace combustion chamber
comprising at least one burn pot and at least one combustion grate,
the system further comprising at least one fuel feed mechanism that
conveys the fuel from the hopper to the combustion grate of the
burn pot in the fireplace, the hopper, fuel feed mechanism and burn
pot configured to cooperatively evenly feed and evenly combust the
bio-mass solid particulate fuel in the burn pot, and at least one
control operatively connected to the fuel feed mechanism and
configured to control at least the amount and timing of transfer of
the bio-mass solid particulate from the hopper to the burn pot.
[0010] In some embodiments, the fuel feed mechanism can be a
multi-directional fuel feed mechanism and the multi-directional
fuel feed mechanism and the hopper can be cooperatively configured
to move the fuel in multiple directions to the at least one
discharge opening. Further, at least one of the control, the hopper
or the fuel feed mechanism can be configured to automatically
intermittently, periodically convey a uniform amount of the fuel to
the burn pot, or to continuously convey a uniform amount of the
fuel to the burn pot.
[0011] The fuel feed mechanism can be, for example, an auger
comprising flightings along a shaft, continuous loop device or a
non-turning agitating device, and can have a single fuel entry
point and at least two discharge openings, or at least two fuel
entry points with a single discharge opening communicating with the
combustion chamber. The effective direction of the fuel feed
mechanism can be reversed. The hopper can be a multi-chamber fuel
hopper, and the system can comprise at least one discharge chute
configured to carry the fuel between the hopper and the combustion
chamber. The combustion chamber can be sized and configured for a
residential or commercial heat or energy generation fireplace. The
system further can comprise a regulatable, variable source of
increased combustion air, which can comprise an air fan or a
compressed air source.
[0012] In another aspect, the systems, etc., herein comprise a
fireplace comprising a fireplace fuel feed system as discussed
herein.
[0013] In a further aspect, the discussion herein provides methods
of burning a bio-mass solid particulate fuel in a fireplace. The
methods can comprise: providing a fireplace comprising at least one
fuel hopper configured to hold and dispense a supply of at the
least one bio-mass solid particulate fuel, the hopper communicating
via at least one discharge opening with a fireplace combustion
chamber comprising at least one burn pot and at least one
combustion grate, the system further comprising at least one fuel
feed mechanism that conveys the fuel from the hopper to the
combustion grate of the burn pot in the fireplace; controllably
engaging the fuel feed mechanism to evenly feed the bio-mass solid
particulate fuel to the combustion chamber; and, evenly combusting
the bio-mass solid particulate fuel in the fireplace combustion
chamber.
[0014] In some embodiments, the fuel feed mechanism can be a
multi-directional fuel feed mechanism and the methods further can
comprise moving the fuel in multiple directions to the at least one
discharge opening. The methods further can comprise automatically
intermittently, periodically conveying a uniform amount of the fuel
to the burn pot, or automatically continuously conveying a uniform
amount of the fuel to the burn pot.
[0015] The fuel feed mechanism can be an auger and the methods
further can comprise moving the fuel to the discharge opening using
flightings along a shaft of the auger. The fuel feed mechanism can
have a single fuel entry point and at least two discharge openings
and the methods further can comprise moving the fuel in multiple
directions from the single entry point toward the at least two
discharge openings, or the fuel feed mechanism can have at least
two fuel entry points and a single discharge opening communicating
with the combustion chamber and the methods further can comprise
moving the fuel in multiple directions from the at least two fuel
entry points toward the single discharge opening. The burning can
take place in a residential or commercial heat or energy generation
fireplace.
[0016] The methods further can comprise regulatably, variably
providing increased combustion air to the combustion chamber during
the burning, and can comprise reversing the effective direction of
the fuel feed mechanism during the burning.
[0017] These and other aspects, features and embodiments are set
forth within this application, including the following Detailed
Description and attached drawings. Unless expressly stated
otherwise, all embodiments, aspects, features, etc., can be mixed
and matched, combined and permuted in any desired manner.
BRIEF DESCRIPTION OF THE DRAWINGS
[0018] FIG. 1 depicts a perspective view of a fireplace fuel feed
and combustion system.
[0019] FIG. 2 depicts a perspective view of a fireplace fuel feed
system in a patio fireplace.
[0020] FIG. 3 depicts a perspective view of another embodiment of
the modular multi-chambered hopper and multi-discharge combustion
system, with the hopper visible in a partial cut-away portion of
the outer jacket.
[0021] FIG. 4 depicts a perspective view of a modular
multi-chambered hopper and multi-discharge combustion device
comprising a dual discharge system, with the hopper visible in a
partial cut-away portion of the outer jacket.
[0022] FIG. 5 depicts a perspective view of a further embodiment of
a combustion system herein comprising a modular multi-chambered
hopper with multi-discharge ports, with the hopper visible in a
partial cut-away portion of the outer jacket but the hopper lacking
a hopper lid.
[0023] FIG. 6 depicts a cross section of a built-in fireplace
comprising a modular multi-chambered hopper and multi-discharge
combustion system herein.
DETAILED DESCRIPTION
[0024] The present systems and methods, etc., relate to fireplaces
featuring a modular combustion system to feed and combust biomass
solid particulate fuel(s). Relative to traditional log or gas
fireplaces, such systems provide for one or more of reduced
installation costs, enhanced ease of use, reduced ash and waste,
uniformity of heat, and reduced costs of use.
[0025] The present systems and methods, etc., herein comprise a
fireplace fuel feed system comprising: at least one fuel hopper or
bin and fuel feed mechanism having both an entry point(s) and
discharge point(s) for the intake and export of the biomass solid
particulate fuel.
[0026] The fuel feed mechanism can be multi-directional, which
means that it can move the fuel within the hopper in multiple
directions to one or more discharge points of the hopper; such
multi-directional fuel feed mechanisms can also be used in cooking
burning appliances such as stoves and barbecues.
[0027] The hopper and fuel feed mechanism are operably connected to
a fireplace burn pot comprising at least one combustion grate. The
hopper, fuel feed mechanism and burn pot are configured to
cooperatively feed and evenly combust at least one biomass solid
particulate fuel in the burn pot within the fireplace. The fuel
feed mechanism comprises a fireplace conveyor comprising at least
one of a gravity slide or a mechanical fuel feed mechanism that
conveys the fuel from the hopper to the burn pot. The conveyor is
configured to substantially uniformly discharge the fuel across the
combustion grate of the burn pot in the fireplace such that the
even combustion can be achieved. Further, the system comprises at
least one control operatively connected to the hopper and burn pot
and configured to control the amount and timing of transfer of the
biomass solid particulate from the hopper to the burn pot.
[0028] The control is configured to manually or automatically
control one or more of the feed rates of the fuel to the burn pot
for higher or lower BTU outputs, control the speed of the draft
fans, and/or control the air flow to the combustion chamber, for
example by changing the positioning of automatic, mechanical or
bimetal dampers or valves.
[0029] The systems are located within fireplaces, which can be for
example in the form of a built-in fireplace, a portable patio
fireplace or a fire pit; a fireplace or fire pit as used herein
differs from a stove or barbecue, for example, in that there is no
cooking grate or surface. The gravity slide or mechanical fuel feed
mechanism can be, for example, a screw auger with flightings along
a shaft turned by a gear drive or separate motor that turns the
auger; a belt, chain, or other continuous loop conveyor; or, a
non-turning vibrating or agitating device that "shakes" the fuel
from a beginning location to the desired location such as the
discharge port of the hopper and/or the combustion grate of the
burn pot. The fuel feed mechanism can feed fuel to one or more fuel
discharge points, in one or more directions. The bin or hopper can
be singular or comprise multiple chambers or sections.
[0030] The flightings of the screw auger can be of any desired
material and conformation, for example formed steel, or fiber or
steel brush. The auger shaft can have a hollow center with short
shafts only at the outboard ends to accommodate mounting into the
bearings. The diameter of screw auger in one embodiment is about
2.5 inches, but may be virtually any size based on the size of the
preferential particulate fuel used. For example, if solid fuel of
larger diameter is employed, such as in industrial use, a
multi-directional screw auger of larger diameter may be used.
[0031] The systems can comprise one or more fuel delivery chutes
configured such that the fuel slides down onto a one or more
combustion grates within the burn pot (sometimes referred to as an
air chamber), and can comprise one or more draft fan or compressed
air sources to provide combustion air to the grates to achieve
combustion. If desired, the fireplaces can comprise decorative
elements such as decorative logs.
[0032] In operation, biomass solid particulate fuel from the hopper
spills or otherwise moves into the intake openings of the fuel feed
mechanisms or conveyors and, where the conveyors are located within
the hopper(s), are moved to the discharge openings of the hopper by
such fuel feed mechanisms. The action of the fuel feed mechanisms
moves the fuel at a controlled rate to the combustion grate causing
a desired, usually consistent and uniform, quantity of biomass
solid particulate fuel to be discharged via the discharge openings
of the fuel feed mechanisms onto the combustion grates in the burn
pot(s). If desired, the fuel feed mechanisms can be controlled to
provide a certain, usually uniform, amount of fuel to the burn pot
per fuel feed mechanism action.
[0033] In certain embodiments, the fireplaces include a decorative
outer housing, or an adjustable control for the fuel feed
mechanisms to adjust feed rate. Further, the fuel feed mechanisms
may be made of different materials and/or at different angles to
alter the feed rate to accommodate the wide variety of different
sized biomass solid particulate fuels available. When using a screw
auger, the auger may rotate with in a formed round, or multi
angular shaped tube. The interior surface of such tube can be
unpolished such as is characteristic of unfinished stock metal.
However, the material comprising surface, and specifically the
roughness of this surface, can be varied as desired.
[0034] Turning to the figures, FIG. 1 depicts a perspective view of
a fireplace fuel feed and combustion system 20 comprising a hopper
1 (the front panel of the hopper 1 has been removed to enhance the
ability to see components within hopper), a fuel feed mechanism 3
comprising one or more fuel entry points 14, a tubular discharge
chute 5 and a combustion chamber 6. In the embodiment shown, hopper
1 comprises a lid 22, hopper walls 34, and spreader fins 30 that
are helpful to direct the flow of pellets or other biomass solid
particulate fuel to the fuel feed mechanism 3 which is an auger 2
comprising multiple flightings 3a, 3b. Hopper 1 communicates with
combustion chamber 6 via at least one discharge opening 38.
[0035] Combustion chamber 6 comprises a combustion grate 6a, fuel
igniter 6b and burn pot 6c. Hopper 1 in FIG. 1 is a multichamber
hopper with the chambers divided by divider 24. Upper extended
portions 28 of hopper 1 are configured to hold a substantial amount
of fuel to be ultimately supplied to combustion chamber 6.
[0036] In the embodiment shown, the auger 2 is multi-directional,
journaled in bearings 12, and driven by an auger motor 4 that in
turn is controlled by an auger control 8 located at a control panel
10 (not shown in FIG. 1, see, e.g., FIGS. 3 and 4). The auger 2 is
contained within an auger tube 9 configured to fit the size and
shape of auger 2 including auger flightings 3a, 3b and thereby to
enhance the ability of the auger to move fuel to discharge chute 5.
In FIG. 1, the auger 2 and flightings 3a, 3b are multi-directional,
moving fuel either outwardly or inwardly depending on the direction
of rotation; single-direction augers and other conveyors, and other
configurations, are possible.
[0037] A combustion fan 7 is operably connected to combustion
chamber 6; the fan can be electrical, hand-powered or otherwise
powered as desired, and can be controlled at the same control panel
10 or any other desired location. The fan 7 provides increased
combustion air for fuel combustion, which air flow can be
regulated, manually or automatically, as desired.
[0038] The base 26 of the system 20 is maintained within a
fireplace, as shown for example in FIGS. 2 and 6. If desired, the
base can be elevated within the fireplace via legs 50.
[0039] FIG. 2 depicts a perspective view of a fireplace fuel feed
system 20 in a patio fireplace 36. Combustion chamber 6 and burn
pot 6c are among the elements of FIG. 2 depicts a perspective view
of a fireplace fuel feed system in a patio fireplace that are
visible in the burn area 48 of fireplace 36.
[0040] FIG. 3 depicts a perspective view of another embodiment of
fireplace fuel feed and combustion system 20, with certain elements
visible in a partial cut-away portion of outer jacket 52. In this
embodiment, hopper 1 lacks a divider 24 so the hopper is
effectively a single chamber. Hopper 1 retains spreader fins 30.
Fuel feed mechanism 3 in FIG. 3 is a continuous loop device, which
in this embodiment is a chain 44. Similar to FIG. 1, the chain
feeds the fuel to a centrally located discharge opening 38, but in
this instance the discharge opening 38 is located proximal to the
hopper and fuel feed mechanism 3 and feeds to an open-top discharge
chute 40 that transports the fuel to combustion chamber 6. Further,
in this embodiment additional air is provided from a pressurized
air source 46.
[0041] FIG. 4 depicts a further embodiment of fireplace fuel feed
and combustion system 20, with certain elements visible in a
partial cut-away portion of outer jacket 52. This embodiment
comprises multiple discharge openings 38 feeding multiple open-top
discharge chutes 40 feeding multiple combustion chambers 6. The
fuel feed mechanism 3 is a continuous loop conveyor 32 comprising
two belts 42, and has a single fuel entry point 16 and two
discharge openings 38. Also, the hopper 1 lacks the spreader fins
30 found in certain other embodiments.
[0042] FIG. 5 depicts a perspective view of a further embodiment of
a combustion system 20. The hopper 1 lacks the hopper lid 22 shown,
e.g., in FIG. 3, and gate 54 provides a valve function that can
mediate flow of fuel from the hopper 1 to the combustion chamber 6.
Like other variable elements herein such as combustion fan 7, gate
54 can be controlled manually or automatically, for example at
control panel 10 or at other location as desired.
[0043] FIG. 6 depicts a cross section of a built-in fireplace 56
comprising a modular fireplace fuel feed and combustion system 20
herein. Built-in fireplace 56 comprises a chimney 58 to provide a
flow-through of air and to take unwanted heat, ash, etc., from the
built-in fireplace 56. FIG. 6 shows one possible implementation of
the modular fireplace fuel feed and combustion system 20 in a
built-in fireplace 56, with hopper 1 disposed behind a separating
wall 60, which wall can also be or function as outer jacket 52
depicted in certain other figures herein.
[0044] Exemplary operation of the system will now be discussed.
Fuel is loaded into the upper expanded portions of hopper 1, which
typically are located within the same chamber as fuel feed
mechanism 3 but can either or also be located in adjacent
chamber(s) communicating with the fuel feed mechanism. The size and
shape of the fuel can be pellets such as common wood pellets
between 1/8 and 3/8 inch in diameter, but can be of any size and
shape such as sawdust, corn, small grain, fruit pits, cellulosic
pellets or sized coal.
[0045] The fuel from hopper 1 enters the fuel feed mechanism 3 such
as auger tube 9 in FIG. 1 and is moved by the rotating
multi-directional screw auger 2. Multi-directional screw auger 2
can rotate in either a clockwise or counterclockwise direction. The
rotation of the multi-directional screw auger 2 moves the fuel as
desired to the combustion chamber 6. For example, the action of
fuel feed mechanism 3 can be on a timed basis, sufficient to cause
a consistent quantity of biomass solid particulate fuel per unit,
such as one screw auger rotation, to be separated from the formed
auger tube 9 and discharged via discharge opening 38, usually via a
transport such as discharge chute 5, onto combustion grate 6a of
burn pot 6c. Once located on the combustion grate, igniter 6b acts
to light the fuel if it is not being added to already-burning fuel,
then the fuel burns at a desired, typically uniform and even, rate
within burn pot 6c and combustion chamber 6. If desired, the
rotation of the multi-directional screw auger 2 can be reversed to
move the fuel in the opposite direction.
[0046] The action of the fuel feed mechanism 3, such as revolution
of multi-directional screw auger 2, may provide almost uniform fuel
feed in various different manners. In one embodiment,
multi-directional screw auger 2 revolves intermittently based on a
signal from control 10 and/or auger control 8, with a controlled
timer, which may be of conventional design, connected to the auger
motor 4, which may be a gear motor. Auger motor 4 is thus activated
on a duty cycle for a variable or desired amount of time, such as a
desired number of seconds. In this manner, a uniform number of
pellets (for example, 5) may be fed from multi-directional screw
auger 2 into burn grate 6a and burn pot 6c with a fixed passage of
time (for example, 10 seconds) occurring before the next group of
pellets are fed. In such an embodiment, multi-directional screw
auger 2 revolves for a certain time period (for example, 3 seconds)
then does not revolve for another predetermined time period (for
example, 7 seconds) based on the period of activation of motor 4.
In this embodiment, the multi-directional screw auger may perform
one or more complete revolutions or only a partial revolution per
feed event.
[0047] In another embodiment, a uniform rate of fuel feed is
attained whereby auger motor 4 is continuously activated, but the
speed of auger motor 4 is varied. Thus, multi-directional screw
auger 2 revolves continuously and the rate of pellets fed into burn
grate 6a is a function of the revolutions per minute of
multi-directional screw auger 2, which is in turn a function of the
speed of auger motor 4.
[0048] Drive bearings 12 can be made of any suitable material, such
as a heat resistant, resilient material having a low coefficient of
friction such as polytetrafluoroethylene, available under the brand
name TEFLON. These properties create a bearing surface which can
provide relatively frictionless turning of the multi-directional
screw auger in the potentially hot environment of a fireplace.
[0049] The auger 2 is only one possible fuel feed mechanism 3. One
alternate embodiment having a drive combination different from the
flighting/shaft of auger 3 shown in FIG. 1 comprises a sprocket
attached circumferentially to multi-directional screw auger 2, and
a chain attached to both the sprocket and a sprocket drive motor,
not separately shown.
[0050] The uniformity of the biomass solid particulate fuel fed to
the combustion chamber using the devices, systems, methods, etc.,
herein, results in more thorough combustion, which in turn provides
less temperature variation, higher combustion efficiency and
cleaner combustion (less combustion pollution, such as less smoke
and soot) than conventional systems. Surprisingly, the data on
pollution levels for fireplaces comprising fireplace fuel feed and
combustion system 20 as discussed herein, indicates that rates of
emission of particulate matter of 0.89 gm/hour have been attained
using standard EPA certification testing methodology. This is much
lower than the EPA maximum allowable rate of 7.5 GPH for a
non-catalytic wood stoves and 3.5 GPH for catalytic wood stoves.
The combustion efficiency for this invention is believed to be
significantly better than heating devices having a single feed
conventional auger feed but being otherwise comparable.
[0051] All terms used herein are used in accordance with their
ordinary meanings unless the context or definition clearly
indicates otherwise. Also unless expressly indicated otherwise, the
use of "or" includes "and" and vice-versa. Non-limiting terms are
not to be construed as limiting unless expressly stated, or the
context clearly indicates, otherwise (for example, "including,"
"having," and "comprising" typically indicate "including without
limitation"). Singular forms, including in the claims, such as "a,"
"an," and "the" include the plural reference unless expressly
stated, or the context clearly indicates, otherwise.
[0052] The scope of the present devices, systems and methods, etc.,
includes both means plus function and step plus function concepts.
However, the claims are not to be interpreted as indicating a
"means plus function" relationship unless the word "means" is
specifically recited in a claim, and are to be interpreted as
indicating a "means plus function" relationship where the word
"means" is specifically recited in a claim. Similarly, the claims
are not to be interpreted as indicating a "step plus function"
relationship unless the word "step" is specifically recited in a
claim, and are to be interpreted as indicating a "step plus
function" relationship where the word "step" is specifically
recited in a claim.
[0053] From the foregoing, it will be appreciated that, although
specific embodiments have been discussed herein for purposes of
illustration, various modifications may be made without deviating
from the spirit and scope of the discussion herein. Accordingly,
the systems and methods, etc., include such modifications as well
as all permutations and combinations of the subject matter set
forth herein and are not limited except as by the appended claims
or other claim having adequate support in the discussion
herein.
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