1,040,481. Oil-fired tunnel kilns; burners. A. STEIMER. Feb. 8, 1963 [May 7, 1962], No. 5312/63. Headings F4B and F4T. In a tunnel kiln for ceramics or brickware, having oil injectors 9 firing intermittently transversely to the direction of air flow, the injectors being arranged in groups of four, and each three groups being controlled so that the entire cross-section of the kiln is supplied with fuel, the last three groups of injectors 9 have mixing tubes 8 supplied with air in approximately stoichiometric proportions so that these injectors form a flame curtain reaching to the tunnel hearth or the floor of the kiln cars within which the combustion products from the upstream zones are completely burnt. The fuel and air supply to the burners are so arranged that the fuel concentration in the air varies continuously. The mixing tube may be a straight tube with a restricted outlet end, Fig. 4 (not shown), or it may have a wider part at the injector end with an enlargement 15 to create turbulence near the outlet, Fig. 5. In another embodiment, Fig. 6 (not shown), the oil is fed with a whirl to a chamber to which air is supplied tangentially, or axially. The chamber narrows to the burner pipe which is surrounded by a sleeve to recirculate some of the combustion products. Since the flame curtain reduces the rate of air flow through the tunnel, cooling air from the passages 3, Fig. 1, may be used in the kiln without over cooling.
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