HEATING ELEMENT FOR BURNING FUEL

摘要

The present invention relates to a fuel-fired heating element of the tubular kind particularly though not exclusively for use as an immersed heating tube in molten metals, salts or fluidized beds of solid particles for conductive heating or for use in an enclosed or partially enclosed chamber to provide radiant and convective heating. The element includes a tubular housing 1 having one end 2 closed and an opening to provide an outlet 4 for combustion products. A burner assembly 6 is received with an annular clearance 51 within the housing between the outlet 4 and the closed end 2 and is arranged to direct its combustion products as a stream towards the closed end 2. The tube 7 encloses with clearance three axially aligned tubes 60, 61 and 62 whose external and internal diameters decrease sequentially from the burner 6 to the end 2. The combustion products are conveyed by the ducts from the burner 6 to the closed end 2 and back again with some re-conveyed products re-entering the duct 60 while the remainder leave by way of the clearance between the burner 6 and the tube 7. Some of the products conveyed from the burner 6 to the closed end 2 are drawn into the returning stream by way of the gap between the ducts.