Combustible particulate fuel heater

A combustible particulate fired heater, comprising:

• a combustion chamber defined by upright side walls extending between open top and bottom ends;
• an enclosure surrounding the combustion chamber;
• a retort within the combustion chamber adjacent the bottom end thereof and having a lower particulate receiving end and an upper open end;
• feed conveyor means leading through the enclosure to the retort for delivering metered quantities of combustible particulates to the lower particulate receiving end of the retort;
• primary combustion air supply means having a primary combustion air supply manifold extending at least partially about the upper open end of the retort;
• primary air control means on the primary air supply means for selectively allowing entry of combustion air from outside the enclosure into the retort;
• secondary combustion air supply means including a secondary air supply manifold within the combustion chamber above the primary combustion air supply manifold;
• secondary air control means independent of the primary air control means for selectively allowing entry of secondary air from outside the enclosure to an area within the combustion chamber above the retort;
• an exhaust duct opening into the enclosure;
• and
• vacuum means connected to the exhaust duct for producing a pressure differential between the area confined by the enclosure and the ambient atmosphere such that ambient air is drawn through at least one of the combustion air supply means to induce a high level of gasification and to support combustion at the retort and for drawing combustion exhaust gases out through the exhaust duct;
• wherein the primary combustion air supply manifold is integral with the retort at the upper end thereof;
• wherein the primary air supply manifold extends about the periphery of the upper open end of the retort and includes a primary air discharge opening formed therein facing inwardly across the upper retort end;
• and
• wherein the primary air supply manifold includes spaced horizontal top and bottom peripheral edges and wherein the primary air discharge opening is situated toward the bottom peripheral edge.