8th International Congress on Science and Technology of Ironmaking - ICSTI 2018

A well operating hearth is a prerequisite for stable and effective blast furnace operation. On-line estimation of the liquid levels in the blast furnace hearth provides an effective means to prevent disturbances and to improve tap management. A mathematical model of the iron and slag levels in the hearth has been developed. The model is based on mass balances using information about the in- and outgoing flows, hearth geometry and dead-man state. Due to measurement errors the estimated liquid levels exhibit drift and must therefore be periodically corrected. The liquid levels also strongly depend on whether the dead man sits or floats. These aspects are considered in the model. Furthermore, regions with lower dead man permeability in the hearth are taken into account by conceptually dividing the hearth into different pools with cross-communication defined by parametric expressions. The paper first presents the model assumptions and equations, followed by some results from a study where it has been applied to data from a blast furnace. Finally an attempt is made to verify the results by using indirect measurements from the process.