GB1257320A - - Google Patents

Abstract

1,257,320. Tuyeres; burners. COMPAGNIE FRANCHISE DE RAFFINAGE, and DE WENDEL ET CIE. 12 Dec., 1968 [13 Dec., [1967; 30 April, 1968], No. 59068/68. Headings F4B and F4T A blast furnace tuyere 1, in which is effected complete combustion of a supplementary fluid fuel added in a substantially lateral direction to the axially flowing air blast, includes at least one fuel injection tube 4, or other fuel inlet orifice, which discharges fuel into or adjacent the diametral plane of a neck 3 in the tuyere wall 2a, to form a fuel/air mixture which flows towards the downstream end 2 of the tuyere, and is ignited and forms a stable flame in the turbulent wake immediately downstream of an obstacle 6 inserted into the end of the tuyere. The obstacle 6 may comprise one or more solid or hollow tapering bodies (Figs. 1 to 4, not shown) and may be fluid cooled. In modifications (Figs. 6 and 8, not shown) the obstacle may be longitudinally extended to the plane in which the supplementary fuel is injected, and by providing there a reduced tuyere crosssection eliminates the need for a neck such as 3. In such a case the upstream end of the obstacle may be provided with-the fuel inlet orifices. A wall 12 may be mounted within and spaced from the tuyere wall 2a to shield the latter from the heat developed by the fuel combustion. In another modification (Fig. 7, not shown) jets of air, steam, inert gas or vapour, or fuel/air mixture jets are introduced near the downstream end of the tuyere to provide an aerodynamic obstruction in place of the solid or hollow obstacle, in the turbulent zone of which jets the supplemental fuel/air blast mixture burns with a stable flame. An expansion chamber may be arranged at the downstream end of the tuyere (Fig. 9, not shown). Formulµ to establish the correct position of the obstacle in the tuyere to give a stable flame under various operating conditions are given In an alternative form of tuyere, Fig. 11, the obstacle is formed by a projection 35 of the water cooled inner wall at the downstream end of the tuyere. Preferably the cone angle of the conical portion of the projection is between 10 and 30 degrees, and the surface area of the base of the cylindrical portion of the projection is not greater than 30% of the total cross-sectional area of the tuyere. The fuel is added to the air stream through an upstream fuel injection tube (not shown), the projection 35 causing a recirculatory flow of the fuel air mixture in zone 40, an electrical resistor 39 initiating ignition -to give a stable flame formation. The cooling circuit for the projection may be independent of or common with that of the remainder of the tuyere. The added fuel may be petroleum oil, fuel oil, natural gas or coke oven gas.