DISTRIBUTION OF REDUCING GAS DELIVERED INTO BLAST-FURNACE STACK

The extent to which the blast furnace stack is used for reduction by gases injected through special tuyeres is considered on the basis, mainly, of cold model experiments. A 1/30 scale model of a 1719 m3 blast furnace was used to determine the influence of tuyere diameter, tuyere overhang, and the flowrate of reducing gas on the depth to which it penetrates the furnace stack with different charging programmes. Maximum utilisation of the stack volume was achieved with an overhang 0.1 times greater than the stack radius at the injection level, the most important factor being the gas consumption/t hot metal. A formula is given for calculating the optimum injection tuyere diameter in relation to the average size of charge pieces.