US 4,380,228 A · Sustained ignition secondary combustion unit

Abstract

A sustained ignition secondary combustion apparatus in a housing of refractory insulating material includes a first level for conducting secondary air through a secondary air inlet and channel, and a second level for conducting smoke products. A partition separates the levels or zones. Openings are provided in the partition between the levels bounded by a high temperature porous or fiberlike material in the form of igniter tube elements. Secondary air and smoke products diffuse into the interstices of the porous or fiberlike material where contact and combustion maintains the igniter tubes at or above the ignition temperature. Ignition and secondary combustion of smoke products in the second level is therefore sustained and secondary air is preheated as it passes through the openings. A secondary combustion zone is defined in the region of the openings between the levels and continues down stream through the exhaust outlet. The first and second levels of the secondary combustion unit may be arranged in a variety of configurations for preheating of secondary air and primary smoke by counterflow with high temperature end products of secondary combustion. Multiple or tortuous pathways may be provided for extended preheating. Primary smoke may also be preheated by smoke preheating tubes. The invention is also applied in a downdraft furnace.

Claims32

Dependent claims

A sustained ignition secondary combustion unit for the secondary combustion of smoke products from primary fuel burning, either as a built in or retrofitted component of a furnace or stove or as a self contained separate unit comprising:

first level means for conducting secondary air comprising a secondary air inlet and channel;
second level means for conducting smoke products from primary fuel burning comprising a smoke products inlet and channel, secondary combustion zone, and exhaust outlet, said outlet defining the direction of flow of secondary combustion products;
partition means separating the levels comprising a high temperature material, said partition formed with openings communicating between the levels in the area of the secondary combustion zone;
said openings between the levels being substantially surrounded or bounded by a high temperature porous or fiber-like material having surface area portions contacting the secondary air from the first level and smoke products from the second level whereby said porous or fiber-like material may be maintained at a sufficient temperature by contact and combustion of secondary air and smoke products which diffuse into the porous or fiber-like material for sustaining ignition and secondary combustion of smoke products in the second level in the vicinity of the porous or fiber-like material, and for producing high temperature products of secondary combustion in the second level at the secondary combustion zone and downstream in the exhaust outlet direction.

1 more element

A downdraft stove or furnace for sustained ignition and secondary combustion of the smoke products from primary fuel burning comprising:

a primary combustion chamber having a primary air inlet for burning solid fuels and grate means for supporting the solid fuels and maintaining a bed of hot coals at the base of the primary combustion chamber, said grate means formed with a concave downward configuration defining an elongate tunnel below the primary combustion chamber, said grate formed with downdraft grate openings;
partition means extending along said tunnel dividing the tunnel into upper and lower channels, said upper channel comprising a secondary air channel in heat exchange relationship with the base of the primary combustion chamber but sealed from the grate downdraft openings, said secondary air channel having an inlet for receiving and preheating secondary air, said lower channel comprising a smoke products channel communicating with the primary combustion chamber through the downdraft openings of the grate, said smoke products channel having a flue outlet for establishing a draft through the smoke products channel;
said partition means formed with a plurality of openings between the secondary air channel and the smoke products channel defining in the smoke products channel a secondary combustion zone, said openings between the channels being substantially surrounded or bounded by a high temperature porous or fiber-like material having surface area portions contacting the secondary air from the upper channel and smoke products from the lower channel whereby said porous or fiber-like material may be maintained at a sufficient temperature, by contact and combustion of secondary air and smoke products in the porous or fiber-like material, for sustaining ignition and secondary combustion of smoke products in the secondary combustion zone of the lower channel in the vicinity of the porous or fiber-like material and for producing high temperature products of secondary combustion.

Dependencies are inferred from the claim text.

Sustained ignition secondary combustion unit

Life of this patent

Sustained ignition secondary combustion unit

Life of this patent

Abstract

Claims32