Patent Application
20090293860
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.
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.
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).
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.
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.
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.
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.
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.
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.
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.
In another aspect, the systems, etc., herein comprise a fireplace comprising a fireplace fuel feed system as discussed herein.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
Turning to the figures,
Combustion chamber 6 comprises a combustion grate 6a, fuel igniter 6b and burn pot 6c. Hopper 1 in
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
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.
The base 26 of the system 20 is maintained within a fireplace, as shown for example in
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 ⅛ and ⅜ inch in diameter, but can be of any size and shape such as sawdust, corn, small grain, fruit pits, cellulosic pellets or sized coal.
The fuel from hopper 1 enters the fuel feed mechanism 3 such as auger tube 9 in
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.
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.
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.
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
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.
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.
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.
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.
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.
| Number | Date | Country | |
|---|---|---|---|
| 61048646 | Apr 2008 | US |
