US 4,646,712 A · Solid fuel heating appliances

Abstract

Solid fuel heating appliance having high thermal efficiency and low levels of polluting emissions. The heating appliance includes an insulated secondary combustion chamber where a mixture of exhaust gases from the primary combustion chamber and secondary air is burned. A catalytic igniter is provided in the secondary combustion chamber to lower the ignition temperature of the unburned volatile gases from the primary combustion chamber. Regenerative feedback structure is provided in heat exchange relationship with the exhaust from the secondary combustion chamber to preheat the mixture entering the secondary combustion chamber, catalytic igniter, and the regenerative heat transfer assure substantially continuous combustion within the secondary combustion chamber even when conditions in the primary combustion chamber change. In a retrofit embodiment for existing stoves, a sheet metal partition in the secondary combustion chamber allows heat transfer from spent gases to the entering mixture of exhaust and secondary air. In a unitary stove embodiment, secondary air is heated by the spent gases which proceed to remote heat exchangers separated from the primary firebox by ventilated air spaces. To prevent room emissions, the stove door is sealed by a vented double gasket system.

Claims29

Dependent claims

A solid fuel burning heating stove with enhanced secondary combustion comprising:

a primary combustion chamber for burning a load of fuel contained therein with a primary outlet for primary exhaust laden with unburned volatiles;
an insulated secondary combustion chamber having an entrance followed by a combustion region where secondary combustion predominates and a final exhaust region of spent gases;
a passageway leading from said primary outlet to said entrance;
means for admitting secondary air to said passageway and for producing a mixture of secondary air and primary exhaust before said entrance;
igniter means spanning said entrance for encouraging ignition of said secondary air/primary exhaust mixture by lowering the temperature of the mixture required to achieve ignition;
means for admitting additional secondary air to said secondary combustion region after said igniter means;
and
regenerative feedback means in heat exchange relationship with said final exhaust for preheating said mixture before encountering said igniter means using the sensible heat of said spent gases;
whereby secondary combustion is sustanied by the availability of the igniter means to overcome fluctuations in the temperature and composition of the primary exhaust which might otherwise foil ignition, and by using the heat of spent gases rather than primary combustion to maintain the temperature of the mixture entering the secondary combustion chamber at an elevated level.

6 more elements

Dependencies are inferred from the claim text.

Solid fuel heating appliances

Life of this patent

Solid fuel heating appliances

Life of this patent

Abstract

Claims29