US20140144385A1 - Biomass Fuel Furnance System And Related Methods - Google Patents

Abstract

A furnace system for heating a poultry brooder house includes a firebox for burning biomass fuel, and a grate within the firebox for burning the biomass fuel thereon. A distributor assembly may positioned within the firebox and is located directly above the grate. The distributor assembly includes a distributor plate having a plurality of apertures therethrough, and a distributor arm above the distributor plate that is movable relative to the distributor plate to cause biomass fuel supported on the plate to pass through the apertures and fall onto the grate. The furnace system may include a hopper assembly that defines a well for receiving a volume of biomass fuel for delivery to the grate or to the distributor plate.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS
• This application is a divisional of U.S. patent application Ser. No. 12/541,628 filed Aug. 14, 2009 (Pending), which claims priority to U.S. Provisional Patent Application Ser. No. 61/089,267 filed Aug. 15, 2008 (Expired), the disclosures of which are incorporated by reference herein in their entirety.
TECHNICAL FIELD
• This invention relates generally to the conversion of energy and, more particularly, to the conversion of biomass fuel from livestock into useful heat.
BACKGROUND
• Commercial livestock operations, such as poultry operations, are known and may include, for example, relatively large buildings that house foul, such as turkeys and chickens, until these reach a desired weight. In these operations, the buildings must be heated to maintain the temperature within a desirable range, and the litter (or droppings) produced by the birds must be removed from the buildings. In conventional commercial poultry operations, heaters are used to provide heat to the buildings housing the birds, with known heaters being fueled by propane or natural gas, for example. The cost to operate these types of heaters, however, is increasingly more expensive due to high fuel costs. Since the profitability of a poultry operation is directly related to the costs associated with the buildings' operating costs, the profitability of the poultry operation decreases with rising heating costs unless the revenue received by the poultry operator (e.g., farmer) also increases. This may translate into higher prices for the consumer.
• Removal of litter (or droppings) from the large buildings housing the birds may include placing clean litter on the floor of a poultry house before the birds are delivered. Known litter materials include organic materials such as sawdust, wood chips, and rice hull; inorganic materials such as sand; and processed materials such as shredded newspaper, for example. In operations of this type, the birds leave their droppings on the litter, which in turn absorbs most of the liquid content of the litter and adheres to the solid litter. Once the birds are removed from the poultry house, the clumped or caked portion of the soiled litter may then be removed from the poultry house and has generally been spread on farm land as a fertilizer, while the rest of the soiled litter may be left in the poultry house to be available for the next flock.
• A problem associated with the processing of soiled litter arises when the litter is mixed with water, as a result of cleaning out of the poultry house, and/or from use of the soiled litter as a fertilizer. Specifically, the water exposed to the litter may become contaminated and become a threat to streams, lakes, or underground water supplies, and may ultimately contaminate the drinking supply. Government agencies in areas of the United States having significant poultry operations have recognized the dangers to the clean water supply. It has become recognized, for example, that soiled litter entering streams and lakes results in growth of organisms that attack and destroy fish in the streams and which may even attack other animals and/or humans, causing severe illness.
• Soiled litter, in this type of operation, therefore often represents an expense and pollution liability rather than a marketable fertilizer product. For growers that are unable to simply pile up poultry litter, the only option is to transport the litter to an acceptable location for dumping or other type of disposal. This, of course, incurs additional handling and transportation costs that may affect the commercial viability of the poultry operation.
• There is a need, therefore, for an apparatus and related methods that address the problems discussed above.
SUMMARY
• In one embodiment, a furnace system is provided for heating a poultry brooder house. The furnace system includes a firebox for burning biomass fuel, and a grate within the firebox for burning the biomass fuel thereon. A distributor assembly is positioned within the firebox and is located directly above the grate. The distributor assembly includes a distributor plate having a plurality of apertures therethrough, and a distributor arm that is spaced above the distributor plate and which is movable relative to the distributor plate to cause biomass fuel supported on the plate to pass through the apertures and fall onto the grate.
• The furnace system may include a hopper assembly that defines a well for receiving a volume of biomass fuel for delivery to the distributor plate. The well includes an inlet for receiving biomass fuel from a supply, and an outlet that communicates with an interior of the firebox and which is positioned above the distributor plate assembly. An agitator is disposed within the well and is movable to urge biomass fuel in the well through the outlet and onto the distributor plate.
• The agitator may be sized and arranged to conform closely to the dimensions of the well, and the agitator may cooperate with the biomass fuel in the well to limit heat loss from combustion of biomass fuel in the firebox through the hopper assembly. The agitator may have first and second spaced apart agitator arms, wherein the first and second agitator arms are operatively coupled to a shaft at their respective proximal ends and are movable within the well to agitate biomass fuel in the well. At least one elongate member extends between the first arm and the second arm to facilitate agitation of the biomass fuel within the well.
• In a specific embodiment, the furnace system has an actuator that is operatively coupled to the agitator, and a controller that communicates with the actuator and which controls operation of the actuator to move the agitator within the well such that biomass fuel within the well is urged through the outlet. At least one sensor is adapted to sense a volume of biomass fuel in the well, with the sensor communicating with the controller and generating a signal related to the sensed volume of biomass fuel in the well. The controller directs the actuator to move the agitator in response to the signal generated by the sensor. The furnace system may, alternatively or additionally, include a storage bin for receiving and storing a volume of biomass fuel for use in the furnace, and a conveyor that is associated with the storage bin and which is configured to deliver biomass fuel from the storage bin to the hopper assembly. A shredder may be located intermediate the storage bin and the hopper assembly for breaking up the biomass fuel into a size suitable for processing through the distributor assembly. The shredder may include a plurality of blades that are spaced from one another by a pre-determined distance, with this distance being substantially the same as a dimension of one or more of the apertures of the distributor plate.
• In another specific embodiment, the furnace includes an actuator that is operatively coupled to the distributor arm, and a controller that communicates with the actuator and which controls operation of the actuator to move the distributor arm relative to the distributor plate. At least one sensor is adapted to sense a temperature within the firebox, with the sensor communicating with the controller and generating a signal related to the sensed temperature. The controller directs the actuator to move the distributor arm in response to the signal generated by the sensor. The controller may, for example, direct the actuator to move the distributor arm in an intermittent manner.
• In a specific embodiment, the grate includes a first grate plate configured to receive biomass fuel thereon, with the first grate plate having a plurality of first apertures therethrough, and a second grate plate beneath the first grate plate and having a plurality of second apertures therethrough. The first grate plate is movable relative to the second grate plate, and the furnace system includes an actuator that is operatively coupled to the first grate plate and which is configured to move the first grate plate relative to the second grate plate to thereby effect removal of ash from the grate through the first and second apertures. At least some of the first or second apertures through the respective first and second grate plates may include slots having a transverse width of about 0.5 inch.
• In a specific embodiment, the firebox of the furnace system includes a first chamber containing the grate and the distribution assembly for primary combustion of the biomass fuel, and a second chamber. The second chamber is in communication with the first chamber and receives gaseous products from the primary combustion of the biomass fuel for secondary combustion of the gaseous products combined with air. The furnace system may include a conduit communicating with the firebox and directing air into the firebox for mixing with the gaseous products to facilitate the secondary combustion. Additionally or alternatively, the furnace system may include a heat exchanger proximate an exit of the second chamber and which is in fluid communication with the poultry brooder house, with the heat exchanger being configured to heat air with heat produced by the second combustion for heating of the poultry brooder house. The furnace system may, additionally or alternatively, include an igniting apparatus, such as a gas burner or a propane heater, for example, proximate the grate, with the igniting apparatus providing initial ignition of biomass fuel received on the grate.
• In yet another embodiment, a method is provided for heating a poultry brooder house. The method includes supporting biomass fuel on a grate within a firebox and burning the biomass fuel on the grate. The method includes sensing a temperature within the firebox. Biomass fuel is then supplied to the grate in response to the sensed temperature. The heat generated from combustion of the biomass fuel is used to heat the poultry brooder house. The method may include feeding biomass fuel into the firebox so as to maintain the height of the biomass fuel on the grate in the range of about 0.5 inch to about 4 inches. In another embodiment, biomass fuel is fed into the firebox to maintain the height of the biomass fuel at about 0.5 inch. Alternatively or additionally, the firebox includes an inlet for feeding the biomass fuel into the firebox, and the method includes maintaining a pre-determined amount of biomass fuel at the inlet so as to substantially block heat loss therethrough. In a specific embodiment, a pre-determined temperature is maintained in the firebox so as to permit self-ignition of the biomass fuel supplied onto the grate.
BRIEF DESCRIPTION OF THE DRAWINGS
• FIG. 1 is a perspective view of a furnace system for heating a poultry brooder house, in accordance with an embodiment of the present invention.
• FIG. 2 is an enlarged perspective view of the furnace of the system ofFIG. 1.
• FIG. 2A is an enlarged broken view of a chipper of the system ofFIG. 1.
• FIG. 3 is a cross-sectional view taken generally along line3-3 ofFIG. 2.
• FIG. 3A is an enlarged cross-sectional view of a firebox of the furnace ofFIG. 3.
• FIG. 4 is a cross-sectional view taken generally along line4-4 ofFIG. 2.
• FIG. 4A is an enlarged view of the furnace ofFIG. 4.
• FIG. 5 is a perspective view of an interior portion of the firebox ofFIG. 3A.
• FIG. 6 is a top view of a grate within the firebox ofFIG. 3A.
• FIG. 7 is a top view of a distributor assembly within the firebox ofFIG. 3A.
DETAILED DESCRIPTION
• With reference to the figures, and particularly toFIGS. 1-2, a furnace system10 is provided for heating apoultry house12, using biomass fuel such as, and without limitation, soiledlitter14 removed from thepoultry house12. System10 includes afurnace18 that processes thelitter14 to produce heat which, in turn, heats air (arrows22,24) that is directed toward thepoultry house12 throughducts26. Astorage bin30 of the system10 receives thelitter14 from thepoultry house12, for example, through conveyors (not shown), manual processes, or any other suitable method. Thestorage bin30, which may, for example, be a silage loader, deliverslitter14 to thefurnace18 without any additional processing such as dewatering, for example. Thestorage bin30 receives and accumulates thelitter14, and supplies thelitter14 to an inlet of thefurnace18 in the form of ahopper assembly32. In this exemplary embodiment, thelitter14 is fed from thestorage bin30 to thehopper assembly32 through aconveyor36. The system10 may additionally or alternatively include a shredder orchipper45 located intermediate thestorage bin30 and thehopper assembly32 and which breaks up thelitter14 into a size that is suitable for processing through components of thefurnace18 described in further detail below.
• In the embodiment shown, furnace system10 includes a firebox50 located below thehopper assembly32, from which it receiveslitter14, and an air-to-air heat exchanger54 that is used to heat the air (arrows22) flowing through theheat exchanger54 and toward thepoultry house12.Firebox50 includes a housing defined by one or more sidewalls103 and atop wall104.Doors56, secured in a closed position by alatch57, provide access to an interior58 of the firebox50 to facilitate, for example, cleaning and/or maintaining the components in the interior offirebox50. As discussed in further detail below, a first air inlet60 (FIG. 2) disposed at thebase63, and a second air inlet61 (FIGS. 3,3A) though a sidewall103 of the firebox50 provide combustion air, through respective blowers into the interior of the firebox50 (only blower61aassociated with second air inlet61 is shown). In particular,air entering firebox50 throughair inlets60,61 facilitates primary and secondary combustion processes, withinfirebox50, for producing heat, as discussed more fully below. Theheat exchanger54 of furnace system10 is in fluid communication with anexit68 of the firebox50 through a duct66 (FIG. 4) and receives heat generated within thefirebox50 for heating incoming air (arrows22) that is then directed (arrows24) to thepoultry house12, as explained in further detail below.Ducts26 also direct a portion of the incoming air generally around thefirebox50 to facilitate cooling thefirebox50. After being heated by the exterior surfaces of thefirebox50, this portion of the air is rejoined with the air passing through theheat exchanger54 and is directed to thepoultry house12.
• With reference toFIGS. 3 and 3A, the interior portions ofhopper assembly32 andfirebox50 are now described in further detail. The interior ofhopper assembly32 defines a well70 that receiveslitter14 and feeds it into the interior58 offirebox50. Anagitator78 is mounted at the upper end ofhopper assembly32, onto aframe80, and includeshelical flightings82 that facilitate feeding thelitter14 through anoutlet86 at the bottom end ofhopper assembly32. In the embodiment shown, an actuator in the form of amotor88 is supported byframe80, and drives ashaft90 that in turn supports thehelical flightings82. Rotation of the shaft90 (arrows93) by action ofmotor88 rotates thehelical flightings82 to thereby feed thelitter14 toward the bottom i.e., toward outlet86 (arrows94). Theagitator78 may further include one or more upper arms87 proximate the upper end of well70, and one or more lower arms89 proximate the start of thehelical flightings82. In the embodiment shown, pairs of upper arms87 and lower arms89 are disposed on opposite sides of theshaft90, however, it will be appreciated that various other arrangements are possible.Elongate members95, such as cables or rods, extend between the distal ends of associated upper and lower arms87,89 and generally proximate the sidewalls of well70 to facilitate agitation of thelitter14 and to prevent clumping oflitter14 within thewell70.
• Actuation ofmotor88 to turnshaft90 is selectively controlled by acontroller96, such as a PLC, for example. In the embodiment shown, thehopper assembly32 includes asensor97apositioned within well70 at a location to sense a volume oflitter14 within the well. Signals fromsensor97arelated to the volume oflitter14 in well70 are communicated tocontroller96 for use in controlling the operation ofmotor88 to feedlitter14 towardoutlet86, and for controlling the operation ofstorage bin30 andconveyor36 to replenishlitter14 when the volume within well70 is low. In one embodiment,controller96 may keep track of the number of revolutions ofshaft90 and control operation ofstorage bin30 andconveyor36 to replenish well70 after a predetermined number of revolutions. Operation ofstorage bin30 andconveyor36 may continue until a signal fromsensor97ais received at thecontroller96, indicating that a desired volume oflitter14 within well70 has been attained. In another embodiment,hopper assembly32 may further include asecond sensor97bpositioned within well70 to sense the presence oflitter14 and to generate a signal related to a low volume oflitter14 within well70. Signals generated bysecond sensor97bmay be communicated tocontroller96 to facilitate operation ofmotor88 and/orstorage bin30 andconveyor36 to maintain a desired volume oflitter14 within well70.
• Thehopper assembly32 in this embodiment is thus configured to maintain a pre-selected volume oflitter14 in well70, for example, to facilitate feeding oflitter14 throughoutlet86 into thefirebox50. Alternatively or additionally, thehopper assembly32 may be configured to maintain a pre-selected volume oflitter14 in well70 so as to limit the loss of heat and/or gases from firebox50 throughhopper assembly32. More specifically, in this embodiment, the configuration of the helical flighting82 and upper and lower arms87,89 relative to the interior walls of well70 and abottom section32aof thehopper assembly32 may be selected such that thelitter14 in well70 and/orsection32ais effective to plugsection32ato thereby limit the escape of gases and/or heat from the interior offirebox50.
• With continued reference toFIGS. 3 and 3A,litter14 fed throughoutlet86 ofhopper assembly32 may be deposited onto adistributor plate98 of anoptional distributor assembly100 located inside afirst chamber50aoffirebox50.Distributor plate98 is supported, in this exemplary embodiment, bysupport frame members102 secured to thetop wall104 offirebox50, although this is intended to be exemplary rather than limiting. Thedistributor assembly100 is configured to temporarily hold thelitter14 and controllably feed thelitter14 onto agrate110 located within thefirst chamber50aand generally below thedistributor plate98. To this end, thedistributor assembly100 includes adistributor arm112 mounted, in this embodiment, toshaft90, and rotatable relative to thedistributor plate98 by action ofmotor88.Distributor arm112 may be operable to rotate in one or both directions of rotation (i.e., clockwise and counter-clockwise), with rotation of thearm112 being continuous or intermittent. In this regard, intermittent rotation ofarm112 may, in one embodiment, be such thatdistributor arm112 periodically rotates less than a full revolution, stopping between rotations for a predetermined length of time, such as about15 seconds, for example. In one embodiment, movement ofdistributor arm112 is controlled bycontroller96 to providelitter14 to grate110 at a desired rate.
• Distributor arm112 is spaced close todistributor plate98 such that rotation ofdistributor arm112 evenly distributeslitter14 across thedistributor plate98 and thegrate110 below. As noted above, thedistributor arm112, in this embodiment, is mounted toshaft90, such that rotation ofshaft90 results in rotation of thedistributor arm112 and rotation of theagitator arms82 ofhopper assembly32. Those of ordinary skill in the art will readily appreciate, however, thatdistributor arm112 may alternatively be rotatable independently from theagitator arms82, and may be controlled, for example, by a driving mechanism separate frommotor88 andshaft90.
• With continued reference toFIGS. 3 and 3A, and with further reference toFIGS. 2A,4,4A,5, and7, rotation ofdistributor arm112 causeslitter14 supported on theplate98 to pass through (arrows116) a plurality ofapertures118 of theplate98. In this embodiment, and with particular reference toFIGS. 5 and 7, one or more of theapertures118 may have a dimension (e.g., transverse width “d”) that is substantially the same as a spacing “s” betweenblades45aof shredder45 (FIG. 4A), such that thelitter14 processed through theshredder45 is of a size suitable to pass through theapertures118.
• Litter14 passing through theapertures118 ofplate98 falls ontograte110 for burning thereon. As discussed above, the movement ofdistributor arm112 may be intermittent or continuous. Thegrate110 of this exemplary embodiment includes first and second generallycircular grate plates122,124 (FIGS. 3A,4A,5, and6), each having respective sets offirst apertures122a,124aand second apertures122b,124b, at least some of which may be in the form of slots having, for example, a transverse width of about 0.5 inch. Each of the first andsecond apertures122a,124a,122b,124bof this exemplary embodiment are in the form of slots of at least two different lengths. The first andsecond apertures122a,124a,122b,124bfacilitate the passage of ash “A” therethrough when aligned in registration with one another.
• A pair of upwardly extending, concentric rims120a,120bpositioned radially outwardly fromgrate110 are sized and arranged to receive a plurality of fire bricks126 arranged in a side-by-side configuration to help retain thelitter14 ongrate110.
• An optional leveling arm125 (FIGS. 3,3A) may be coupled to theshaft90, or to some other component, so as to be selectively movable relative to grate110. Specifically, the levelingarm125 may be configured to selectively rotate relative to grate110 so as to maintain a uniform layer oflitter14 across thegrate110. The levelingarm125 may further include a plurality of fingers125aextending downwardly towardgrate110 and arranged to rake through thelitter14 and ash “A” ongrate110 as levelingarm125 is rotated. The raking action of fingers125areduces or eliminates the formation of hot spots in the ash that will tend to solidify, thereby maintaining the ash “A” at a size that will pass throughgrate110.
• In another exemplary embodiment,furnace18 may be provided without theoptional distributor assembly100 for receivinglitter14 fromhopper assembly32. In such an embodiment, levelingarm125 may be utilized to maintain a uniform layer oflitter14 acrossgrate110, as discussed above.
• Thegrate plates122,124 are movable relative to one another such that, when the respective sets ofapertures122a,124a,122b,124bare in registration with one another, ash “A” (FIG. 3A) produced by the burning oflitter14 on thegrate110 is allowed to pass through both sets ofapertures122a,124a,122b,124band toward an ash-removing apparatus, discussed more fully below.
• In the exemplary embodiment of theFIG. 6, relative rotation of the first andsecond grate plates122,124 is facilitated by an actuator in the form of aair cylinder138 operatively coupled to a source ofpressurized air140. Adrive rod138aofair cylinder138 is operatively coupled to aprotruding arm141, extending radially outwardly from a main portion of thefirst grate plate122, to cause selective rotation thereof (arrows143 ofFIG. 6). When actuated,drive rod138aextends or retracts relative to ahousing138b, causing rotation ofarm141 and rotation of the entirefirst grate plate122. This rotation selectively moves thefirst grate plate122 relative to thesecond grate plate124, from a first position wherein the first andsecond apertures122a,122bthrough thefirst grate plate122 are not in registration with the first andsecond apertures124a,124bof thesecond grate plate124, to a second position wherein the first andsecond apertures122a,122bthrough thefirst grate plate122 are aligned in registration with the first andsecond apertures124a,124bof thesecond grate plate124. Thefirst grate plate122 is maintained in the first position during normal operation of thefurnace18 to burnlitter14 ongrate110. The first grate plate is periodically moved to the second position by theair cylinder138, under the control ofcontroller96, to align theapertures122a,124a,122b,124bof the first andsecond grate plates122,124 so that ash “A” can pass therethrough onto an ash-removing apparatus.
• Those of ordinary skill in the art will readily appreciate, however, that movement of the first andsecond grate plates122,124 relative to one another may take various other forms, which may or may not include relative rotation of thegrate plates122,124. For example, and without limitation, an alternative configuration may include rotation of both grateplates122,124, or linear, rather than rotational, movement of one or bothgrate plates122,124.
• In exemplary embodiment shown in the figures, the ash-removing apparatus includes a generally V-shapedplate127 and anauger128, driven by amotor130, that removes ash “A” supported onplate127. Rotation ofauger128 advances the ash “A” through an ash exit outlet132 (FIGS. 4 and 5) away from thebase63 offirebox50, for further disposition. To facilitate moving ash “A” towardauger128,furnace18 may further include a second, generally V-shaped plate129 positioned within V-shapedplate127. The second V-shaped plate129 is movable relative to V-shapedplate127 by an actuator134, such as a pneumatic cylinder or any other suitable device (FIG. 4A). In the embodiment shown, an opening is formed in the second V-shaped plate129 for receiving theauger128 therein. Accordingly, as second V-shaped plate129 is moved by actuator134, ash “A” is moved in a direction towardauger128 for removal throughexit outlet132.
• The V-shapedplate127 of this embodiment also facilitates the uniform distribution of combustion air (arrows60a) received throughair inlet60. Specifically, combustion air (arrows60a) passes through a plurality ofapertures127aof V-shapedplate127 into the ash-receivingregion127babove V-shapedplate127. Air then passes through combustion air apertures124cin thesecond grate plate124, which are aligned in registration with the first andsecond apertures122a,122bof thefirst grate plate122 when the first grate plate is in the first position described above.
• With particular reference toFIGS. 3A,4,4A and5, burning of thelitter14 ongrate110 is facilitated by combustion air received from outside of the firebox50 through the first air inlet60 (FIGS. 2,3A,5, and6). Initial ignition of thelitter14 ongrate110 may be facilitated by an ignitingapparatus150 located beneathgrate110. Ignitingapparatus150 may, for example, be in the form of a gas burner or any other type of burner or heater. In the embodiment shown, ignitingapparatus150 is a power gas burner, Model No. HSG 400 available from Wayne Combustion Systems of Fort Wayne, Ind., received in aconduit62 extending beneath grate110 (FIGS. 4,4A,6). Ignitingapparatus150 may be controlled bycontroller96 to selectively provide ignition of thelitter14 ongrate110 until combustion of thelitter14 is self-sustaining and/or until the temperature withinfirst chamber50areaches a predetermined level. For example, in an exemplary embodiment, the ignitingapparatus150 may be kept energized until the temperature withinfirst chamber50areaches about 500° F.
• In operation, the frequency of actuation of the ignitingapparatus150 is minimized, in this embodiment, by maintaining the height of thelitter14 ongrate110 at a predetermined level. This predetermined level is such that combustion oflitter14 received ongrate110 from thedistributor assembly100 is self-sustaining by virtue of the relatively high temperature within thefirebox50 and by providing a proper amount of combustion air using a variable speed blower, for example. In this regard, for example, it has been found that maintaining the volume oflitter14 ongrate110 to have a height between about 0.5 inch and about 4 inches minimizes the required frequency of actuation of ignitingapparatus150 and eliminates or at least reduces the amount of smoke generated by combustion oflitter14 ongrate110. In another exemplary embodiment, a volume oflitter14 ongrate110 is maintained corresponding to a height between about 0.5 inch to about 2 inches. In yet another exemplary embodiment, a volume oflitter14 ongrate110 is maintained corresponding to a height of about 0.5 inch to about 1 inch. In yet another exemplary embodiment, a volume oflitter14 ongrate110 is maintained corresponding to a height of about 0.5 inch.
• In this embodiment, maintenance of a predetermined volume oflitter14 ongrate110, and a predetermined temperature withinfirst chamber50a, may be accomplished by supplyinglitter14 to grate110 at a rate selected to maintain the desired volume and temperature during combustion of the litter as described above. This operation is facilitated by one or more sensors162 (one shown in the figures) that sense a temperature withinfirebox50. Signals fromsensor162 are communicated tocontroller96, which may adjust the operation ofagitator78,supply bin30, andconveyor36 to increase or decrease the rate at which litter14 is provided to grate110.Controller96 may also vary the speed of variable speed blowers that provide the primary and secondary combustion air tofirebox50. For example,controller96 may vary the speed of the blowers based on signals received fromsensor162, the rate at which litter14 is provided to grate110, or any other factors or combinations of factors.
• Signals fromsensor162 may be utilized bycontroller96 to control operation of the ignitingapparatus150, although this is intended to be exemplary rather than limiting. While asingle controller96 has been shown and described herein, it will be appreciated that operation of the furnace system10, as generally described herein, may be controlled by more than one controller, as may be desired.
• In another exemplary embodiment, the height oflitter14 ongrate110 is sensed by an optional sensor163 (shown in phantom inFIG. 3A) positioned proximate thegrate110. Sensor163 may be a contact-type sensor, a non-contact-type sensor, or any other type of sensor suitable to sense a height of thelitter14 ongrate110. Signals from sensor163 may be communicated tocontroller96 and used bycontroller96 to control the operations of thestorage bin30,conveyor36,hopper assembly32,grate110, combustion air blowers, or various other components of furnace system10. In such an embodiment,furnace18 may or may not additionally includesensor162 for sensing a temperature insidefirebox50.
• With continued particular reference toFIGS. 3A,4,4A, and5, burning (i.e., combustion) oflitter14 ongrate110 produces combustion gases (arrows168) that circulate withinfirst chamber50a. Combustion gases (arrows168) leave thefirst chamber50aand enter asecond chamber50boffirebox50 through anopening170 for secondary combustion. In the embodiment shown,second chamber50bis at least partially defined by a generally vertical wall174 located infirebox50 and extending downwardly fromtop wall104 towardbase63 In this embodiment, secondary combustion air is provided through one ormore conduits186 extending horizontally across the interior offirebox50 andproximate opening170. A variable speed blower61acontrolled bycontroller96 is operatively coupled toconduits186 to provide the secondary combustion air at a desired rate, and the secondary combustion air exits the conduits via a plurality of spaced apart apertures187 disposed therealong. As the combustion gases movepast conduit186 and enter opening170, the secondary combustion air exiting apertures187 turbulently mixes with the combustion gases and secondary combustion is achieved due to the relatively high temperatures within thefirebox50. If complete combustion is not achieved at theopening170,additional conduits186 may be provided within thesecond chamber50bto provided additional secondary combustion air for subsequent combustion withinsecond chamber50b.
• In one embodiment, an optional second ignitingapparatus176 may be in communication with thesecond chamber50bto facilitate combustion of the mixture of combustion gases and secondary combustion air therein. In the exemplary embodiment of the figures, the high temperature withinfirebox50 is sufficient to ignite the mixture of combustion gases (arrows168) and secondary combustion air (arrows172), thus obviating the need for second ignitingapparatus176. In this exemplary embodiment, supply of the secondary combustion air, as well as supply of the primary combustion air may be facilitated by one or more blowers, such as variable speed blowers, for example, controlled by a dedicated controller, such ascontroller96, as discussed above.
• With particular reference toFIG. 4, heat produced by combustion within thesecond chamber50btravels (arrows190) throughfirebox exit68 and through a plurality oftubes54aof theheat exchanger54. Exhaust gases (arrows188) from the combustion insecond chamber50bleavefurnace18 through anoutlet189. Air, such as forcedair22, travels in cross-flow fashion past thetubes54aand is convection-heated by contact with thetubes54a. The resultingheated air24 then flows, through ducts26 (FIG. 2), topoultry house12 to heat same.
• While the above embodiments describe the burning oflitter14 from birds housed withinpoultry house12, it is contemplated that the above-described system and methods may additionally or alternatively include the burning of other types of biomass fuels that may or may not be supplied by the birds or other animals housed in a building heated by the combustion of the biomass fuel. In this regard, it is therefore contemplated that the furnace system may burn biomass fuels other than the exemplary bird litter and still fall within the scope of the present disclosure.
• While the present invention has been illustrated by a description of various preferred embodiments and while these embodiments have been described in some detail, it is not the intention of the Applicant to restrict or in any way limit the scope of the appended claims to such detail. Additional advantages and modifications will readily appear to those skilled in the art. Thus, the various features of the invention may be used alone or in numerous combinations depending on the needs and preferences of the user.

Claims (8)

What is claimed is:

1. A method for heating a poultry brooder house, the method comprising:

supporting biomass fuel on a grate within a firebox;

burning the biomass fuel on the grate;

sensing one of a temperature within the firebox or a height of the biomass fuel on the grate;

feeding biomass fuel into the firebox in response to the sensed temperature or sensed height; and

using heat generated from combustion of the biomass fuel to heat the poultry brooder house.

2. The method ofclaim 1, further comprising:

providing combustion air to the firebox; and

varying the rate of providing combustion air based on the sensed temperature or sensed height.

3. The method ofclaim 1, further comprising:

feeding biomass fuel into the firebox so as to maintain the height of the biomass fuel on the grate in the range of about 0.5 inch to about 4 inches.

4. The method ofclaim 1, further comprising:

feeding biomass fuel into the firebox so as to maintain the height of the biomass fuel on the grate in the range of about 0.5 inch to about 1 inch.

5. The method ofclaim 1, wherein the firebox includes an inlet for feeding the biomass fuel into the firebox, the method further comprising:

maintaining a predetermined amount of biomass fuel at the inlet so as to substantially block heat loss therethrough.

6. The method ofclaim 1, further comprising:

maintaining a predetermined temperature in the firebox so as to permit self-ignition of the biomass fuel supplied onto the grate.

7. A furnace system for heating a poultry brooder house, the furnace comprising:

a firebox for burning biomass fuel;

a grate within said firebox for burning the biomass fuel thereon; and

a leveling arm above said grate and being movable relative to said grate to spread biomass fuel supported on said grate into a substantially uniform layer over said grate.

8. The furnace system ofclaim 7, further comprising:

a plurality of fingers extending from said leveling arm and toward said grate, said fingers spaced and arranged to rake through biomass fuel supported on said grate as said leveling arm is moved relative to said grate.

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