Patent 7959431 was granted and assigned to Fives North American Combustion, Inc. on June, 2011 by the United States Patent and Trademark Office.
A burner fires into a radiant tube to provide a downstream flow of combustion products within the radiant tube. Staged fuel is injected upstream into the radiant tube. A recirculation conduit inside the radiant tube receives the staged fuel along with combustion products that are inspirated into the recirculation conduit by the staged fuel. The recirculation conduit has an outlet for discharging a mixture of the inspirated combustion products and staged fuel into the downstream flow of combustion products.