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Show 1 J Improvement of reducing-flame burner with oxygen enrichment. SEIJI OKADA YUTAKA SUZUKI Corporate Research & Development Laboratories, Sumitomo Metal Industries LTD. MOTOFUMI KAMINAKA Department of Engineering, Sumikin Management Co., Inc. Abstract: Recently, in the non-oxidizing furnace (NOF) of the continuous annealing process, steel sheet is heated by reducing and direct fired heating with reducing-flame burner instead of by the radiant tube heating. Firstly we investigated the reductive performance of the burner, and tried to improve the reductive efficiency with preheated and oxygen enriched combustion air. Secondly we attempted to specify the main reductive species by numerical simulation of the laminar coke oven gas (COG) pre-mixed flame. The conclusions are summarized as follows. The oxidized layer on a steel sheet of several mircrons thickness, could be reduced in ten seconds when steel sheet was heated from room temperature to 800°C in a furnace. The reducing flame burner with oxygen enriched combustion air could lead to 1200°C non-oxidizing heating in the open air. As a result of computation, the concentration of H, which is the reductive radical in the reducing flame, was increased by using high temperature flame. 1.Introduction The steel heating processes in the iron and steel works are divided roughly into the indirect heating and the direct fired heating. The indirect heating is represented by radiant tube heating, and used for non-oxidizing heating or uniform heating, etc. On the other hand, the direct- fired heating method is represented by the edge heater of the slab, and used for local heating or rapid heating by direct blowing against steel products. The radiant-tube burner heating (indirect heating) in a reducing atmosphere, H2 and N2 gas, was conventionally applied in the continuous annealing furnace. In recent years, the direct-fired heating has been applied to the non-oxidizing heating of the steel sheets with reducing flame.1) The "reducing flame" refers to the flame that burns excess fuel compared to the state where complete combustion occurs, and causes the chemical reduction of steel. The reducing flame is applied mainly to the direct-fired heating zone in |