METHOD AND APPARATUS FOR HEAT TREATING ARTICLES IN A RECIRCULATING TYPE FURNACE

摘要

A method and apparatus for heat treating articles in a recirculating type furnace in which hot gases and returned reheated products of combustion are injected into the furnace chamber from a pressurized feed system external to the furnace walls, through injection nozzles spaced along the walls which provide a velocity sufficient to create adequate forced recirculation to provide not only uniform heat distribution within the chamber, but rapid equalization of temperature. The invention is applicable to batch type and continuous heat treating or annealing processes and can be also applied to radiant tube fired furnaces such as protective, reductant, carburizing and the like atmosphere radiant tube fired batch or continuous heat treat furnaces or box annealers.