COMBINED INJECTION OF PLASTIC PARTICLES AND HEAVY FUEL OIL INTO A BLAST FURNACE RACEWAY - DETAILED CFD ANALYSIS

Auxiliary reducing agents like oil, tar, pulverized coal, natural gas, coke oven gas and waste plastics are injected into the blast furnace to decrease the coke rate. CFD methods have been used to simulate the injection of plastics into the blast furnace raceway at blast furnace A at voestalpine Stahl GmbH, Linz (Austria). Based on this CFD model for plastic particle injection reported earlier an extended model is being developed. The new model makes use of the capability to predict the raceway shape based on a new porous media approach avoiding the high computational effort of a full eulerian multiphase formulation and incorporates also a simplified reaction mechanism for calculation of the high temperature conversion of the injected materials. In addition to that code to handle the injection of multicomponent droplets like heavy fuel oil and tar has been incorporated. Boundary conditions for the new model are set using process data from voestalpine Stahl in Linz (Austria). It is also necessary to provide suitable boundary conditions and physical properties for each of the involved materials. Since the availability of high temperature material data is sparse, measurements for thermal conductivity and heat capacity of the coke used at the simulated blast furnace have been carried out. Thermal conductivity was analyzed using a direct approach measuring the thermal diffusivity of a cylindrical coke bed heated at constant temperature. Heat capacity was measured using a drop calorimeter.