Solid fuel combustor and method of burning

A solid fuel combustor for efficient burning of fuel, comprising,

• a primary combustion chamber having means for introduction therein of primary air and a fuel entrance port for filling said chamber with solid particulate fuel,
• a support grate underlying said primary combustion chamber for carrying said fuel thereon,
• a secondary combustion chamber below said primary combustion chamber,
• means for introducing secondary air to said combustor to cause burning in said secondary combustion chamber,
• said secondary combustion chamber defining ash removal ports and screen means to screen ash from flow of gaseous combustion products,
• said screen means defining plural gas passageways from said secondary combustion chamber to a manifold area to permit gas flow in directions opposed to a direction of travel of ash removed from said gas flow,
• a heat exchanger coupled to said manifold for extracting heat from gaseous output of said manifold which is used to heat air for use in said combustor,
• said manifold area being defined by a wall surrounding said secondary combustion chamber,
• said secondary combustion chamber being substantially cylindrical and formed of a high heat deterioration resistant side wall,
• said side wall defining a plurality of slots acting as screening slots for residue products of combustion while allowing flow of gaseous products of combustion,
• conduiting means for introducing primary air to said primary combustion chamber and secondary air to said secondary combustion chamber,
• said primary air conduiting means comprises a first pipe for receiving hot air from said heat exchanger and a second pipe for receiving cold untreated air, and
• mixer means for mixing said hot and cold air and metering means for metering the proportion of hot and cold air to be mixed.

A solid fuel combustor for efficient burning of fuel, comprising,

• a primary combustion chamber having means for introduction therein of primary air and a fuel entrance port for filling said chamber with solid particulate fuel,
• a support grate underlying said primary combustion chamber for carrying said fuel thereon,
• a secondary combustion chamber below said primary combustion chamber,
• means for introducing secondary air to said combustor to cause burning in said secondary combustion chamber,
• said secondary combustion chamber defining ash removal ports and screen means to screen ash from flow of gaseous combustion products,
• said screen means defining plural gas passageways from said secondary combustion chamber to a manifold area to permit gas flow in directions opposed to a direction of travel of ash removed from said gas flow,
• a heat exchanger coupled to said manifold for extracting heat from gaseous output of said manifold which is used to heat air for use in said combustor,
• said manifold area being defined by a wall surrounding said secondary combustion chamber,
• said secondary combustion chamber being substantially cylindrical and formed of a high heat deterioration resistant side wall,
• said side wall defining a plurality of slots acting as screening slots for residue products of combustion while allowing flow of gaseous products of combustion,
• conduiting means for introducing primary air to said primary combustion chamber and secondary air to said secondary combustion chamber, and
• said secondary air conduiting means comprises a first pipe for receiving hot air from said heat exchanger and a second pipe for receiving cold untreated air, and
• mixing means for mixing said hot and cold air and metering means for metering the proportion of hot and cold air to be mixed.

A solid fuel combustor for efficient burning of fuel, comprising,

• a primary combustion chamber having means for introduction therein of primary air and a fuel entrance port for filling said chamber with solid particulate fuel,
• a support grate underlying said primary combustion chamber for carrying said fuel thereon,
• a secondary combustion chamber below said primary combustion chamber,
• means for introducing secondary air to said combustor to cause burning in said secondary combustion chamber,
• said secondary combustion chamber defining ash removal ports and screen means to screen ash from flow of gaseous combustion products,
• said screen means defining plural gas passageways from said secondary combustion chamber to a manifold area to permit gas flow in directions opposed to a direction of travel of ash removed from said gas flow,
• said grate comprises a plurality of elongated parallel tubes,
• said tubes each having a high temperature resistant ceramic casing so as to cause turbulence in gas flow through said grate,
• and secondary air passageways in said grate tubes for jetting secondary air into said gas flow through said grate means.

In a method of burning solid fuel efficiently where fuel is burned in a first chamber and the combustion products drawn downwardly through a grate, the improvement comprising,

• drawing said combustion products into a secondary combustion chamber,
• said chamber walls being formed of a high temperature resistant refractory material having gas passage slots therethrough,
• passing substantially finished products of combustion through said slots to the outside of said chamber while removing solid products thereof by impingement on said walls and gravity drop to a removal area and
• adding tertiary combustion of air about the outside of said secondary combustion chamber which tertiary air further acts to cool the outside of said secondary combustion chamber.

In a method of burning solid fuel efficiently where fuel is burned in a first chamber and the combustion products drawn downwardly through a grate, the improvement comprising,

• drawing said combustion products into a secondary combustion chamber,
• said chamber walls being formed of refractory bricks and and said slots are formed by spaces between adjacent bricks,
• passing substantially finished products of combustion through said slots to the outside of said chamber while removing solid products thereof by impingement on said walls and gravity drop to a removal area and
• adding diluent gas about the outside of said secondary combustion chamber which diluent gas further acts to cool the outside of said secondary combustion chamber.