Improvements in or relating to annealing furnaces or lehrs

摘要

717,254. Tunnel furnaces. VICKERS, G. M. May 1, 1953 [Feb. 1, 1952; March 31, 1952], Nos. 2792/52 and 8136/52. Classes 51 (1) and 51 (2) A tunnel furnace for baking ceramics, vitreous enamelling or for glassware conveyed through by an endless belt 10, is heated by a series of radiant tubes 1 and 2, spaced from and following the contour of the walls and roof of the tunnel, and fired by gas or oil burners 5, alternate tubes being fired from opposite sides. Waste gas ducts 7 and 8 extend longitudinally below the tunnel floor to one or more stacks at or near the discharge end, and the tubes open into these ducts at the end opposite the burners. A third longitudinal duct 9 with a separate burner at one end provides additional bottom heat. The radiant tubes are made of silicon carbide aluminous fireclay or heatresisting metal, and may be rectangular, triangular or semi-circular in cross section. The furnace atmosphere is circulated upwardly at the tunnel centre and in streams diverging outwardly across the roof, down the sides, and along the bottom to the centre again, by fans 15 located above the radiant tubes, formation of the circulating paths being assisted by placing laminar members 16 formed with central openings over the gaps between the said radiant tubes. The furnace is built on vertical pillars 13 and rollers 14 to allow for longitudinal expansion.