US 4,672,946 A · Secondary combustion device for woodburning stove

Abstract

An improvement in a woodburning stove of the type including an exhaust flue opening; a combustion chamber for primary combustion, having an access door, a support for wood to be burned and a primary air inlet means for supplying primary air to support primary combustion of the wood to produce flue gases containing combustible particulate material; conduit means for directing the flue gases from the combustion chamber to the flue opening in a preselected path; and, secondary combustion means for burning the particulate material in the flue gases before the flue gases pass through the exhaust flue opening. The improvement involves the secondary combustion means for supplying many jets of secondary air into the flue gases adjacent to the combustion chamber together with a laterally elongated, secondary combustion device having a constriction effect on the flue gases and a large volume secondary combustion plenum chamber with the combustion device and plenum chamber connected in series between the combustion chamber and the exhaust flue opening. This secondary combustion device includes two closely spaced, generally parallel walls through which the flue gases and secondary air pass from the combustion chamber through an exit end of the device into the plenum chamber in a wide, narrow flow pattern and including means for thermally insulating the outermost wall of the secondary combustion device whereby it rapidly attains and retains a high temperature without absorbing substantial heat energy.

Claims54

Dependent claims

In a wood burning stove including an exhaust flue opening, a combustion chamber for primary combustion having an access door, a support for wood to be burnt and a primary air inlet means for supplying air to support primary combustion of said wood to produce flue gases containing combustible particulate material, conduit means for directing said flue gases from said combustion chamber to said flue opening in a preselected path and secondary combustion means for burning said particulate material in said flue gases before said flue gases pass through said exhaust flue opening, the improvement comprising:

said secondary combustion means including an elongated manifold extending laterally across and above said combustion chamber at a preselected position on said preselected path, a number of air openings spaced longitudinally along said manifold and facing said path of said flue gases and an air inlet means for supplying ambient, secondary combustion air to said manifold for flow from said openings into said path of said flue gases in a plurality of distinct jets, and a laterally elongated passageway above said manifold with upper and lower portions and defined at its upper portion by a sheet metal wall, and a layer of extremely low heat conducting insulation in said passageway and on said sheet metal wall whereby said layer of insulation prevents appreciable conduction of heat from said passageway into said sheet metal wall and said flue gases flow through said passageway and from said passageway in a generally wide thin flow pattern.

said secondary combustion means including means for supplying many jets of secondary air into said flue gases adjacent said combustion chamber, a laterally elongated secondary combustion device having a constriction effect on said flue gases and a large volume secondary combustion plenum chamber with said combustion device and plenum chamber connected in series between said combustion chamber and said exhaust flue opening, said secondary combustion device including two closely spaced generally parallel walls through which said flue gases and secondary air pass from said combustion chamber through an exit end of said device to said plenum chamber in a wide, narrow flow pattern and means for thermally insulating the outermost of said wall whereby it retains a high temperature without absorbing substantial heat energy.

A secondary combustion device for a wood burning stove including an exhaust flue opening, a combustion chamber for primary combustion having an access door, a support for wood to be burnt and a primary air inlet means for supplying air to support primary combustion of said wood to produce flue gases containing combustible particulate material, conduit means for directing said flue gases from said combustion chamber to said flue opening in a preselected path and secondary combustion means for burning said particulate material in said flue gases before said flue gases pass through said exhaust flue opening, said secondary combustion device comprising:

a set of secondary air jet means above said combustion chamber for introducing secondary air into said flue gases;
a first secondary burning chamber having an upper exposed wall for burning said particulate material by said secondary air into an intermediate gas mixture;
an insulation layer means on said exposed wall for preventing said wall from absorbing appreciable heat energy;
a second secondary combustion chamber means defined by said wall and a lower generally parallel closely spaced wall for causing said intermediate gas mixture to move in a wide, narrow path to a chamber outlet;
a plenum chamber means having a volume for holding said intermediate gas mixture after it passes from said chamber outlet and before it exits from said exhaust opening;
and, means for causing turbulence in said plenum chamber and adjacent said chamber outlet.

3 more elements

Dependencies are inferred from the claim text.

Secondary combustion device for woodburning stove

Life of this patent

Secondary combustion device for woodburning stove

Life of this patent

Abstract

Claims54