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Abstract

A convection diffuser and charge support system for an annealing furnace utilizes a diffuser base assembly that includes a vane-carrying center casting which underlies a charge support plate, and which is perimetrically surrounded by a pair of outer and inner cooling rings. The components of the diffuser base assembly cooperate to define an array of horizontally extending gas circulation passages that are shielded from above by the charge support plate. The horizontal passages extend among a plurality of upstanding heat exchange fins that are carried by the inner cooling ring, and terminate in upwardly extending outer end regions that are defined by grooves formed in the outer cooling ring. A centrifugal fan draws hot gases through a central opening in the charge support plate and conveys the gases radially outwardly through the horizontally extending gas flow passages. The gases flow outwardly through the horizontal passages, among the fins of the inner cooling ring, and are diverted upwardly by the grooves of the outer cooling ring for movement along generally helical flow paths about a charge of material being annealed. The outer cooling ring is provided with a depending, perimetrically extending skirt. In an annealing process, cooling of the hot gases within the furnace enclosure is carried out in a two stage procedure that is initiated sufficiently gradually to avoid collapse of the positive pressure atmosphere within the furnace enclosure.

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First Claim