Mathematical Modelling of Blast Furnace Processes for Characterisation of the Internal State

Abstract

The blast furnace is a multi-phase, multi-species moving bed metallurgical reactor with counter-current exchange of heat and mass between gas and solid involving phase changes and complex reactions at high temperatures. Its dynamic behaviour, being typical of a non-linear, distributed parameter multiple input-multiple output (MIMO) system, defied any description and characterisation in terms of comprehensive understanding of the process dynamics for a long time. Various phenomena and performance of the blast furnace are influenced by the counter-current gas flow, chemical reactions, descent of burden materials, gas flow resistance and shape of the cohesive layer, combustion and transport behaviour in the raceway zone with or without pulverised coal injection. Based on the first principle approach, a one-dimensional simulation model has been developed, assuming axial and radial symmetry in distribution of process variables. The internal state of the furn.ace is characterised by the simulated distribution of relevant process variables along the furnace axis which include the temperatures of the gas and condensed phases, composition, volumetric flow rate, density and pressure of the gas phase, degree of iron oxide reduction, limestone decomposition and the coke solution loss reaction.The calculated longitudinal profiles of the furnace process variables show good agreement with the published data.