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;   a secondary chamber having a bottom, at least one air intake, and at least, one air escape, said at least one air escape venting air from said secondary chamber to said burning chamber;   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 fire top of said burning chamber; and   said opening guiding flames out of said burning 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 about 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 secondary chamber further comprises a roof. 
     
     
         7 . The fire pit of  claim 6  wherein said roof overhangs at least a portion of said primary chamber. 
     
     
         8 . 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. 
     
     
         9 . 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 
 the ratio of air intake area to air escape area is about 18-41%. 
 
     
     
         10 . The fire pit of  claim 1  wherein said fire pit produces said flames using natural airflow only. 
     
     
         11 . A fire pit comprising:
 a burning chamber, said burning chamber having a floor at least partially open to the air below said burning chamber, a top at least partially open to the air above said burning chamber, 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;   said at least one wall common to said burning and secondary chambers comprising a lower half, an upper half, and 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.   
     
     
         12 . The fire pit of  claim 11  wherein said fire pit is cylindrical. 
     
     
         13 . The fire pit of  claim 11  wherein said floor is about 53% open to air below said burning chamber. 
     
     
         14 . The fire pit of  claim 11  wherein said roof covers at least a portion of said burning chamber. 
     
     
         15 . The fire pit of  claim 11  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. 
 
     
     
         16 . The fire pit of  claim 15  wherein the ratio of secondary air intake area to secondary air escape area is 18-41%. 
     
     
         17 . An apparatus comprising:
 a burning chamber, said burning chamber having a floor comprising a grate and at least one inner wall;   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;   said at least one inner wall comprising a 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; and   said air escape outlets configured to allow said secondary air to move from said secondary chamber to said burning chamber.