Drying furnace for use in coating drying

A drying furnace for drying a coating on an article while the article is being moved therethrough,

• said furnace comprising:
• left and right sidewall and ceiling means defining a tunnel-like furnace main body of U-shaped plan figure having two laterally-opposite legs, and including, in series, an inlet zone including an inlet to said furnace main body, an effective drying zone, and an exit zone including an exit from said furnace main body, said inlet zone and said exit zone being disposed laterally adjacent one another;
• said sidewall and ceiling means enclosing a path for movement of an article having a coating to be dried, so that said article may be successively moved into said furnace main body through said inlet of said inlet zone, along said inlet zone, along said effective drying zone, along said exit zone and out of said furnace main body through said exit;
• said furnace main body being provided internally thereof on said ceiling-means in said inlet zone and said exit zone with a respective resin deposition prevention duct through which hot gas may be circulated for maintaining a high temperature in said inlet zone despite proximity of said inlet and for maintaining a high temperature in said exit zone despite proximity of said exit;
• said furnace main body being provided internally thereof on said sidewall means in said effective drying zone with coating-drying hot gas recirculating duct means for radiating heat to said article as said article is being moved along said path in said effective drying zone;
• burner means including blower means associated therewith, said blower means having a pressure side and a suction side;
• supply duct means communicating said burner means with said resin deposition prevention ducts and with said hot gas recirculating duct means, so that gas may be heated by said furnace, blown through said hot gas recirculating duct means and said resin deposition prevention ducts and at least partially recycled to said burner means for reheating.