Bio-fuel furnace

Abstract

This bio-fuel furnace includes a combustion unit and separate fuel feed unit mounted atop the combustion unit. The combustion unit includes a cylindrical burn pot, a preheat module, an expansion bowl and a primary heat exchanger supported by an inner frame and enclosed by an outer casing. The preheat module is a rectangular box having an internal spiral baffle. The burn pot is seated within a central opening in the preheat module. The expansion bowl is seated atop the preheat module and the primary heat exchanger is mounted above the expansion bowl. An inlet fan blows inlet air through the preheat module and into the burn pot and an outlet fan draws exhaust air around the primary heat exchanger from the combustion unit. The fuel feed unit has an internal storage bin and a rotating scoop arm deposits the bio fuel into the combustion unit. The rotation of the scoop arm meters the bio-fuel into the combustion unit, which falls vertically directly into the burn pot though a center passage in the primary heat exchanger and the expansion bowl.

1 . A bio-fuel burning furnace comprising:
 a bio-fuel combustion unit; and a bio-fuel feed unit mounted above the combustion unit,   the combustion unit includes a housing defining an interior therein;   a pre heat module disposed within the housing interior for preheating an inlet airflow to a temperature above the combustion temperature of the bio-fuel, the preheat module defining an enclosed interior therein and having a top opening therein,   a burn pot seated within the pre-heat module top opening and having an interior with an open top within which the bio-fuel is burned, the burn pot having a plurality of holes therein for directionally venting the pre-heated inlet air into the burn pot so as to create a combustion vortex of inlet air, combusting bio-fuel, exhaust gases and thermal energy within the burn pot interior,   a fan for blowing inlet air through the preheat module into the burn pot,   the bio-fuel feed unit includes means for depositing the bio-fuel into the combustion unit so that the bio-fuel falls vertically through the combustion vortex inside the burn pot interior.   
     
     
         2 . The furnace of  claim 1  wherein the plurality of holes in the burn pot are also spaced so as to create a curtain of swirling inlet air along the inside of the burn pot sidewall to acts as a thermal barrier between the burn pot sidewall and the combustion vortex. 
     
     
         3 . The furnace of  claim 2  wherein the burn pot has a cylindrical sidewall, the plurality of holes in the burn pot extending through the burn pot sidewall at approximately a 30 degree angle with respect to the radius of the burn pot sidewall, and spaced around the circumference of the burn pot sidewall. 
     
     
         4 . The furnace of  claim 1  wherein the preheat module includes an internal baffle spiraling around the burn pot for restrictively channeling inlet air toward the burn pot. 
     
     
         5 . The furnace of  claim 1  wherein the preheat module is constructed of a thermal conducting material. 
     
     
         6 . The furnace of  claim 1  wherein the combustion unit also includes a heat exchanger disposed within the housing interior above the preheat module and an expansion bowl disposed within the housing interior between the preheat module and the heat exchanger. 
     
     
         7 . The furnace of  claim 1  wherein the expansion bowl has an opening therethrough spaced above the burn pot and a sloped annular face around the bowl opening. 
     
     
         8 . The furnace of  claim 1  wherein the expansion bowl is constructed of a thermal insulating material. 
     
     
         9 . The furnace of  claim 7  wherein the housing and the heat exchanger have a passage way through which bio fuel is deposited from the bio-fuel feed unit into the burn pot interior. 
     
     
         10 . The furnace of  claim 6  wherein the combustion unit also includes a second fan for drawing exhaust gases around the heat exchanger and venting the exhaust gases from the combustion unit. 
     
     
         11 . A bio-fuel burning furnace comprising:
 a bio-fuel combustion unit; and a bio-fuel feed unit mounted above the combustion unit,   the combustion unit includes a housing defining an interior therein, a pre heat module disposed within the housing interior for preheating an inlet airflow to a temperature above the combustion temperature of the bio-fuel, the preheat module defining an enclosed interior therein and having a top opening therein, the preheat module includes an internal baffle spiraling around the burn pot for restrictively channeling inlet air toward the burn pot, a burn pot seated within the pre-heat module top opening and having an interior with an open top within which the bio-fuel is burned defined by a cylindrical sidewall, the burn pot having a plurality of holes extending through the burn pot sidewall at approximately a 30 degree angle with respect to the radius of the burn pot sidewall, and spaced around the circumference of the burn pot sidewall for directionally venting the pre-heated inlet air into the burn pot so as to create a combustion vortex of inlet air, combusting bio-fuel, exhaust gases and thermal energy within the burn pot interior, the plurality of holes in the burn pot also spaced so as to create a curtain of swirling inlet air along the inside of the burn pot sidewall to act as a thermal barrier between the burn pot sidewall and the combustion vortex, a heat exchanger disposed within the housing interior above the preheat module, an expansion bowl disposed within the housing interior between the preheat module and the heat exchanger, the expansion bowl has an opening therethrough spaced above the burn pot and a sloped annular face around the bowl opening, the housing and the heat exchanger have a passage way through which bio fuel is deposited from the bio-fuel feed unit into the burn pot interior, a first fan for blowing inlet air through the preheat module into the burn pot, and a second fan for drawing exhaust gases around the heat exchanger and venting the exhaust gases from the combustion unit,   the bio-fuel feed unit includes means for depositing the bio-fuel into the combustion unit so that the bio-fuel falls vertically through the combustion vortex inside the burn pot interior.   
     
     
         12 . A method of burning bio-fuel in a furnace, comprising the following steps:
 a. burning the bio fuel inside a burn pot;   b. transferring thermal energy from the combustion of bio-fuel within a burn pot into a preheat module;   c. circulating an inlet air flow through the preheat module to preheat an inlet air flow to the burn pot above the combustion point of the bio-fuel;   d. directionally venting the preheated inlet air flow from the preheat module into the burn pot so as to create a combustion vortex of preheated inlet air, combusting bio-fuel, exhaust gases and thermal energy within the burn pot;   e. depositing additional bio-fuel into the burn pot such that the bio-fuel falls vertically through the combustion vortex whereby the bio-fuel is burned within the combustion vortex.   
     
     
         13 . The method of  claim 12  and an additional step:
 f. expanding the combustion vortex across the bottom of a heat exchanger to uniformly conduct thermal energy from the combustion vortex to the heat exchanger. 
 
     
     
         14 . The method of  claim 12  wherein step d includes venting the preheated inlet air flow through a plurality of angled bores formed within the burn pot. 
     
     
         15 . The method of  claim 12  wherein the transferring of thermal energy of step b is preformed by conducting and radiating thermal energy through the burn pot into the preheat module.