Abstract:
A furnace includes a chute extending from the back of a combustion chamber to allow for the material in the combustion chamber to be pushed into the chute and ejected from the chute by the force of new fuel being pushed into the furnace. No time is lost in cleaning out the furnace as the cleaning of the furnace happens as a byproduct of fuel being loaded into the furnace. The ease and efficiency of operation, in that the cleaning happens by performing the necessary task of loading the furnace with fuel, will allow furnace operation in a more simple, convenient, and safe manner without requiring the furnace to be shut down.

Description:
BACKGROUND 
       [0001]    1. Technical Field 
         [0002]    This disclosure generally relates to furnaces, and more specifically relates to combustion furnaces that burn fuel in a combustion chamber. 
         [0003]    2. Background Art 
         [0004]    Furnaces of various different sizes and configurations have been developed for the burning of fuel, such as large bales of hay. These furnaces typically have one door, or set of doors that cover an opening to the inside of the furnace. Fuel is loaded through this opening. These furnaces can consume large amounts of hay which results in large amounts of ash. Some quantity of ash can stay in the furnace without affecting the operation of the furnace, but after a period of time there is so much ash that the ash needs to be removed from the furnace. With only one access point in the furnace, the ash has to go out of the same door where the fuel comes in. This means a person has to get into the furnace and manually shovel out the ashes through the door, or use a piece of machinery to remove the ashes. Regardless of whether ash removal is done manually or by machine, the furnace must generally be allowed to cool to allow a person or machine to enter the furnace without risk of injury to a person or damage to a machine. It takes a long time after the fire in the combustion chamber is no longer burning for a large furnace to cool. This means the need to clean out ash from the furnace may result in the furnace being out of commission for a significant period of time each time it needs to be cleaned. [0005] 
         [0005]    Whenever the furnace is out of commission, a more expensive heating system must be used in its place costing extra money. It would be very advantageous to have a way to clean out the ashes from the furnace without having to wait for the furnace to cool. 
         [0006]    In addition, removing ashes from the same door where fuel is added creates a large pile of ashes that must be removed before new fuel is added to the furnace. If the ashes are not completely removed, the fuel being added may ignite from the hot ashes before the fuel is loaded into the stove. 
         [0007]    One possible solution would be to put doors on both sides of the furnace so that you could load fuel from one side and remove ash from the other. However, from a practical standpoint, this creates a dangerous situation. If the furnace were not allowed to cool, when both doors were opened a wind tunnel would be created across the hot fuel and ash, providing a high supply of oxygen to the fuel and ash, and would literally result in a fire tunnel that would be a danger to people or property in the vicinity of the furnace. 
         [0008]    Without a way to clean out a large furnace that burns fuel such as large bales of hay in a more simple, convenient and safe manner, the use of such furnaces will continue to be subject to the disadvantages discussed above. 
       BRIEF SUMMARY 
       [0009]    A furnace includes a chute extending from the back of a combustion chamber to allow for the material in the combustion chamber to be pushed into the chute and ejected from the chute by the force of new fuel being pushed into the furnace. No time is lost in cleaning out the furnace as the cleaning of the furnace happens as a byproduct of fuel being loaded into the furnace. The ease and efficiency of operation, in that the cleaning happens by performing the necessary task of loading the furnace with fuel, will allow furnace operation in a more simple, convenient, and safe manner without requiring the furnace to be shut down. 
         [0010]    The foregoing and other features and advantages will be apparent from the following more particular description, as illustrated in the accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING(S) 
         [0011]    The disclosure will be described in conjunction with the appended drawings, where like designations denote like elements, and; 
           [0012]      FIG. 1  is a side cross-sectional view of a furnace when the furnace is empty; 
           [0013]      FIG. 2  is a side cross-sectional view of the furnace when the furnace is loaded with fuel; 
           [0014]      FIG. 3  is a side cross-sectional view of fuel being loaded into the furnace pushing material into a chute; 
           [0015]      FIG. 4  is a front cross-sectional view of the furnace in  FIG. 1  taken along the line  4 - 4 ; 
           [0016]      FIG. 5  is a front view of the furnace in  FIG. 1  taken along the line  5 - 5 ; 
           [0017]      FIG. 6  is a view of the rear of the furnace in  FIG. 1  taken along the line  6 - 6 ; 
           [0018]      FIG. 7  is a top view of a pushing tool; 
           [0019]      FIG. 8  is a front view of the pushing tool in  FIG. 7  taken along the line  8 - 8 ; and 
           [0020]      FIG. 9  is a side view of a hand crank used to open chute door  160 . 
       
    
    
     DETAILED DESCRIPTION 
       [0021]    A fuel-burning furnace  100  is shown in various views in the figures. The fuel-burning furnace  100  includes a combustion chamber  110  with a front  130  and a back  120 , one or more doors  150 , a chute  140  with a chute door  160 , a blower  170 , an exhaust system  180 , and a water chamber  190 . The bottom portion of combustion chamber  110  is preferably in the shape of a transverse substantially semi-cylindrical surface, thereby providing a curved bottom surface that approximately matches the curvature of a large round bale of hay. The combustion chamber  110  may include one or more heat exchangers preferably near the top of the combustion chamber to increase the surface area for heat transfer, thereby enhancing the transfer of heat from the combustion chamber. Doors  150  are opened to gain access to the combustion chamber  110 , such as for loading fuel and for servicing the inside of the combustion chamber  110 . The chute  140  has a receiving end coupled to the lower portion of the back of the combustion chamber  120  and a discharge end opposite the receiving end. The chute door  160  is attached to the top of the discharge end of the chute  140  by a hinging mechanism that includes, but is not limited to, hinges, and is normally biased in a closed position by the force of gravity when the combustion chamber  110  is empty. 
         [0022]    Doors  150  provide an opening to the combustion chamber  110 . Doors  150  may include one or more blowers  170  that provide air flow into the combustion chamber to aid in combustion. Blowers  170  are preferably fixed in location, but could include an oscillating portion that distributes air flow to different parts of the combustion chamber. In the alternative, the blowers  170  could be fixed while motorized louvers in the combustion chamber distribute air flow from the blowers to different parts of the combustion chamber. Exhaust system  180  provides a path for smoke to exit the combustion chamber  110 . Water chamber  190  preferably surrounds the combustion chamber  110  to provide an efficient transfer of heat from the combustion chamber  110  to water within the water chamber  190 .  FIG. 1  shows the fuel-burning furnace  100  when it is empty. 
         [0023]      FIG. 2  shows the fuel-burning furnace  100  in  FIG. 1  after it is loaded with fuel  200 . The fuel  200  shown in  FIG. 2  is large round bales of hay. Fuel may include any combustible material that is capable of pushing material  300  in the combustion chamber as the fuel  200  is loaded into the combustion chamber. Suitable examples of fuel include but are not limited to hay, straw, cornstalks, wood, coal, paper bales, cardboard, etc. Any fuel in any suitable configuration may be used if pushing the fuel into the combustion chamber  110  results in pushing material  300  into chute  140 . For example, coal could be placed in burlap sacks, and the sacks of coal could then be loaded into the combustion chamber  110  in a way that pushes material  300  into chute  140 . In the alternative, any form of biomass could be compressed into any suitable shape to provide fuel that is solid enough to push against material  300  as the fuel is pushed into the combustion chamber  110 . Material  300  includes but is not limited to ash, burning fuel, rocks, and dirt. 
         [0024]      FIG. 3  shows the fuel-burning furnace  100  and a front-end portion of a tractor  310  loading new fuel  200  into the combustion chamber  110 . The new fuel  200  pushes against material  300  and pushes material  300  into the chute  140 . The material  300  in chute  140  presses against the chute door  160 , pushing chute door  160  open and discharging a portion of material  300  through the discharge end of chute  140 . In the most preferred operation of a furnace that burns large, round bales of hay, the hay is placed partially within the combustion chamber, then is lowered to contact the bottom of the combustion chamber so the act of pushing the bale into the combustion chamber effectively sweeps the material from the bottom of the combustion chamber and pushes the material  300  into chute  140 . 
         [0025]    The chute  140  can be shaped to the shape of the type of fuel that is being used. For example, the bottom of chute  140  may have a curved shape that would be ideal for large round bales of hay. This curved shape is shown in  FIG. 6  in the outside rear view of the fuel-burning furnace  100 . In another example, large rectangular bales of hay, straw, paper, or cardboard could be used as fuel. In this case, the bottom of chute  140  could be flat and could extend the width of the combustion chamber. The disclosure and claims herein expressly extend to any suitable size and shape for chute  140 . In the most preferred implementation, the bottom of chute  140  is a continuation of the bottom of the combustion chamber  110 . 
         [0026]    A fuel-burning furnace is not normally used year round and often goes idle during the summer months. During these idle times it is often good to do a thorough cleaning of the fuel-burning furnace so that it is cleaned out before the furnace is used continuously again. A pushing tool  700  is shown in  FIGS. 7-8  that conforms to the shape of the bottom of the combustion chamber. For the preferred implementation for burning round bales of hay, the chute  140  has a curved bottom that extends the curved bottom of the combustion chamber  110 . As a result, the pushing tool  700  has a head  710  that has a curved surface that matches the curvature of the bottom of the combustion chamber  110 . The pushing tool  700  includes an elongated portion  720  that may be attached to a suitable piece of equipment, such as a front-end loader on a tractor or a forklift. The pushing tool  700  may be used to push material  300  into the chute  140 , or may be used to pull material  300  out of the combustion chamber  110 . Note also the pushing tool  700  could be used to push material  300  into the chute  140  when the furnace is still hot. The pushing tool  700  can thus provide an extension to a tractor that allows the tractor to push the material  300  into the chute  140  without the tractor tires entering the combustion chamber  110 , thereby allowing the pushing tool  700  to clean out a combustion chamber even when the furnace is hot. 
         [0027]    To prevent chute door  160  from getting stuck on material  300  after fuel  200  is loaded in combustion chamber  110 , a hand crank  910  can be used to open chute door  160 , as shown in  FIG. 9 . The hand crank  910  is coupled to a cable  920  that follows a pulley  930  and is connected to handle  162  on chute door  160 . By cranking (i.e., turning) the hand crank  920 , the chute door  160  may be raised (opened) and lowered (closed). After the chute door  160  is opened using hand crank  910 , as shown in phantom in  FIG. 9 , new fuel  200  can be inserted into the combustion chamber, discharging material  300  as shown in  FIG. 3 . After the new fuel is inserted into the combustion chamber, any material that would block the chute door  160  from closing is removed using a suitable hand tool such as a hoe or shovel before lowering the chute door  160  with hand crank  910 . 
         [0028]    Chute door  160  is merely one possibility for the material  300  to leave the chute  140 . Any arrangement of mechanisms or openings at the discharge end of the chute, that allow the material to be discharged as new fuel is being loaded into the combustion chamber, is within the scope of the disclosure and claims herein. Examples of possible arrangements include, but are not limited to a chute door, a grate on the bottom of chute  140 , and a simple opening on the bottom of chute  140  or at the end of chute  140 . However, the chute door is the preferred implementation because closing the chute door cuts off outside air from reaching the combustion chamber  110  via chute  140 . 
         [0029]    The fuel-burning furnace  100  eliminates the problem of needing to wait for the furnace to cool before removing the material, such as ash, from the combustion chamber. The fuel-burning furnace  100  can be loaded with fuel  200  as shown in  FIG. 2 , and the fuel can begin burning. The fuel-burning furnace does not need to be shut down for cleaning and the fire does not need to go out before new fuel is added. When the fuel level gets low, doors  150  are opened and new fuel  200  is pushed into the combustion chamber  110 , as shown in  FIG. 3 . This new fuel pushes the material  300  in the combustion chamber  110  into the chute  140 . Depending on the amount of material  300  in the combustion chamber  110  and the chute  140 , none or some of the material in the chute  140  may be discharged at the discharge end of the chute  140  (e.g., through the chute door  160 ). The new fuel  200  that is pushed into the combustion chamber  110  catches fire so that this cycle can continue without shutting down the furnace to clean out the combustion chamber  110 . 
         [0030]    Because material  300  being pushed into chute  140  may cause material  300  to exit the discharge end of the chute  140 , there needs to be a safe place for the material  300  to go when exiting the discharge end of the chute  140 . In one suitable implementation, a concrete pit is provided below the discharge end of the chute  140 . Because concrete is non-flammable, the hot material  300  may fall from the chute  140  into the concrete pit to cool. The pit may include a ramp that provides a tractor with a front-end loader access to clean out the pit when the pit becomes full of ash. In addition, the pit may be water-tight so a pool of water is present in the pit when material is ejected from the chute, causing the hot material to fall in the water and be instantly cooled. The presence of water in the pit will also minimize the dust generated when material is ejected from the chute. A pit that holds water preferably includes a way to drain the water, such as a piece of sheet metal similar to known irrigation gates that may be removed to allow the water to drain from the pit. 
         [0031]    Since the fuel-burning furnace  100  is loaded with new fuel while the fire in the combustion chamber is still burning, it is possible that some of the material pushed out of the chute could still be on fire, or may catch fire once exposed to the ambient air outside the furnace. For this reason, a male hose fitting  400  is attached to the water chamber  190  as shown in  FIGS. 4-6 . This allows a hose such as a standard garden hose to be attached to the male hose fitting  400  to have a source of water readily available to extinguish burning material that exits the chute  140 . 
         [0032]      FIG. 5  shows the front view of fuel-burning furnace  100 . The doors  150  are preferably equipped with one or more blowers  170 . The blowers  170  are preferably mounted to the doors to regulate the temperature of fuel-burning furnace  100 . The temperature of the furnace may be kept relatively constant by varying the amount of air delivered by blowers  170  to the combustion chamber  110 . For example, if the furnace is up to its desired temperature, less air needs to be provided to the fuel, so the blowers are shut off, appearing as if there were no openings in the doors, thereby decreasing the rate of combustion in the combustion chamber. Conversely, if the furnace is not up to its desired temperature, the blowers can be turned on to force air across the fuel causing it to burn more rapidly to increase the rate of combustion in the combustion chamber. In addition, one or more dampers may close when the furnace is up to its desired temperature and the blowers stop blowing, allowing only a minimum of air to keep the fire burning. 
         [0033]    Practical experience has shown that many fuels such as hay provide such a hot fire that normal metal doors risk warping under the stress of the extreme heat in the combustion chamber. As a result, the doors  150  preferably include a water jacket that helps to keep the doors at a temperature that keeps the metal on the doors from warping. The water jackets on the doors may communicate with the water chamber  190 , thereby allowing the heat at the doors to be transferred to water in the water chamber  190 . 
         [0034]    While the furnace  100  disclosed herein includes a water chamber  190 , the disclosure and claims herein extend to any suitable configuration for transferring heat from the combustion chamber  110  to an area to be heated, such as a farm building. 
         [0035]    One suitable use for the fuel-burning furnace  100  would be to heat water in water chamber  190 , which can then be used in connection with heat exchangers and blowers to heat a home, chicken house, barn, etc. In the configuration shown in the figures for a furnace that holds two large round bales of hay, the capacity of water chamber  190  is approximately 4,000 gallons, providing a great deal of heating capacity. Depending on the size and configuration of buildings to be heated, if the quantity of water in the water chamber  190  is insufficient to provide the desired heating, a large insulated water reservoir could be coupled to the water chamber  190  to hold water heated by the furnace  100  until it is needed. 
         [0036]    An additional benefit to fuel-burning furnace  100  is its size. Fuel-burning furnace  100  is large enough to be used on a commercial level, but is small enough to be transported. Prior art furnaces are generally built onsite and are not easily transported. Fuel-burning furnace  100  can be moved in a number of ways including, but not limited to, being put on a semi trailer or having a hitch and wheel kit to tow it behind a vehicle. 
         [0037]    Practical experience with a prototype of the furnace disclosed herein shows a significant cost savings when using the furnace. The furnace has been used to heat several chicken houses on a poultry farm. Due to the relatively low cost of suitable hay and straw in large round bales, the inventors have realized a savings of nearly two thirds of their typical energy bill when heating with the furnace compared to heating the chicken houses with propane. This significant savings in energy costs can make the furnace pay for itself in a very short period of time. 
         [0038]    The furnace provides a way for material in the furnace to be ejected from the furnace by the force of new fuel being added to the furnace. The result is a furnace that may be continuously used without having to stop the combustion in the furnace to clean out ash from the furnace. 
         [0039]    One skilled in the art will appreciate that many variations are possible within the scope of the claims. Thus, while the disclosure is particularly shown and described above, it will be understood by those skilled in the art that these and other changes in form and details may be made therein without departing from the spirit and scope of the claims. For example, while a two-bale version of the furnace is shown in the drawings and described herein, a single-bale version of the furnace is also within the scope of the disclosure and claims herein.