Pellet burning fire pit

Abstract

Provided is an apparatus for burning biomass fuel sources, such as a fire pit for burning wood pellets. A fire pit of the present invention may include a burning chamber having a floor and an opening at the top, and a secondary chamber having a bottom, at least one air intake, and at least one air escape. The secondary chamber may be heated by the burning chamber. The at least one air intake may be located near the bottom of the secondary chamber, while the at least one air escape may be located near the top of the burning chamber. In addition, the primary chamber opening may guide flames out of the burning chamber. The secondary chamber may also include a roof which may overhang said burning chamber.

1 . A fire pit comprising:
 a burning chamber, said burning chamber having a floor, and an opening at the top, said opening open to outside air surrounding said fire pit;   a secondary chamber having a bottom, at least one air intake, a roof, and at least one air escape, said at least one air escape venting air from said secondary chamber to said burning chamber and said roof including an overhang, said overhang covering a portion of said burning chamber above said at least one air escape;   said secondary chamber heated by said burning chamber;   said at least one air intake located near said bottom of said secondary chamber;   said at least one air escape located near the top of said burning chamber; and   said opening configured, to allow flames out of said burning chamber, said flames extending above said fire pit;   wherein said overhang is at least partially conical and has an inner edge that is continuous; and   wherein said overhang is configured to slow the rise of air from said secondary chamber.   
     
     
         2 . The fire pit of  claim 1 , wherein said floor comprises a grate. 
     
     
         3 . The fire pit of  claim 2 , wherein said grate is 53% open to the air below said burning chamber. 
     
     
         4 . The fire pit of  claim 1  wherein said burning chamber and said secondary chamber further comprise a common wall. 
     
     
         5 . The fire pit of  claim 4  wherein said common wall includes an upper half and a lower half and said at least one air escape outlet is located in said upper half. 
     
     
         6 . The fire pit of  claim 1  wherein said overhang is further configured to direct said flames upward out of said fire pit. 
     
     
         7 . The fire pit of  claim 1  wherein the shape of said fire pit is selected from the group consisting of cylindrical, oval, square, or star. 
     
     
         8 . The fire pit of  claim 1  wherein:
 said floor allows primary air to enter said burning chamber; 
 said at least one air escape allows secondary air to enter said burning chamber; and 
 a ratio of air intake area to air escape area is 18-41%. 
 
     
     
         9 . The fire pit of  claim 1  wherein said fire pit produces said flames using natural airflow only. 
     
     
         10 . A fire pit comprising:
 a floor at least partially open to the air below said fire pit and having a burning chamber air opening;   a burning chamber, said burning chamber having a top at least partially open to outside air above said fire pit, and at least one wall common to a secondary chamber;   said secondary chamber surrounding said burning chamber, said secondary chamber comprising at least one outer wall, a bottom, and a roof including an overhang, said overhang covering a portion of said burning chamber above at least one secondary air escape;   said at least one wall common to said burning and secondary chambers comprising a lower half, an upper half, and said at least one secondary air escape;   said lower half of said common wall is solid;   said at least one outer wall comprising a lower half, an upper half and at least one secondary air intake;   said upper half of said outer wall is solid;   wherein the cross section of the burning chamber air opening amounts to at least thirty percent of the surface area of the floor;   wherein said fire pit is configured to produce flames that extend above said fire pit;   wherein said fire pit is not covered by a container used for cooking;   wherein said overhang is at least partially conical and has an inner edge that is continuous; and   wherein said overhang is configured to slow the rise of air from said secondary chamber.   
     
     
         11 . The fire pit of  claim 10  wherein said fire pit is cylindrical. 
     
     
         12 . The fire pit of  claim 10  wherein said floor is 53% open to air below said burning chamber. 
     
     
         13 . The fire pit of  claim 10  wherein said roof covers at least a portion of said burning chamber. 
     
     
         14 . The fire pit of  claim 10  wherein:
 said floor allows primary air to enter said burning chamber; and 
 said at least one secondary air escape allows secondary air to enter said burning chamber. 
 
     
     
         15 . The fire pit of  claim 14  wherein a ratio of secondary air intake area to secondary air escape area is 18-41%. 
     
     
         16 . An apparatus comprising:
 a floor comprising a grate and having a burning chamber air opening;   a burning chamber, said burning chamber having at least one inner wall and an opening, said opening directly open to outside air above said apparatus;   a secondary chamber surrounding said burning chamber, said secondary chamber comprising said at least one inner wall, at least one outer wall, a floor, and a roof including an overhang partially covering said burning chamber above a plurality of secondary air escape outlets;   said at least one inner wall comprising said plurality of secondary air escape outlets located in an upper half of said inner wall;   said at least one inner wall further comprising a lower half, said lower half of said inner wall is solid;   said at least one outer wall comprising a plurality of secondary air intake inlets, said secondary air intake inlets located in a lower half of said outer wall;   said outer wall further comprising an upper half, said upper half of said outer wall is solid;   said grate allowing primary air to enter said burning chamber;   said air intake inlets configured to allow secondary air to enter said secondary chamber;   said air escape outlets configured to allow said secondary air to move from said secondary chamber to said burning chamber;   wherein the cross section of the burning chamber air opening amounts to at least sixty-nine percent of the surface area of the grate;   wherein said fire pit produces a flame that extends above said fire pit;   wherein said fire pit is not covered by a container used for cooking;   wherein said overhang is at least partially conical and has an inner edge that is continuous; and   wherein said overhang is configured to slow the rise of air from said secondary chamber and direct said flame upward out of said fire pit.