高炉下部コークス充填層の空隙率推定を組み込んだ溶銑・スラグ液面高さのオンライン連続推定

抄録

An increase in the melt (hot metal and slag) level in the lower part of a blast furnace can trigger serious troubles, including peripheral flow enhancement and, in extreme cases, melt backflow into tuyères. Conventional mass-balance management ignores time-varying voidage of the hearth coke packed bed, while sensor-based methods often suffer from installation constraints and noise. This study develops an online model that preserves continuity with the familiar mass-balance framework while explicitly incorporating the coke-bed voidage. The lower furnace is treated as a cylindrical packed bed; the melt volume is calculated from residual masses (production minus discharge) of metal and slag and converted to liquid level using cross-sectional area and voidage. Voidage at tap end is estimated from the balance between pressure loss of slag flow through the packed bed and hydrostatic pressure associated with the inclined slag surface near the taphole. Slag viscosity and density, effective coke particle size at the lower part, discharge flow at tap end, and inclination angle are derived from operational data and auxiliary models. Tap-wise discrete estimates are time-averaged and interpolated to yield continuous trajectories. Drift correction for cumulative balances and a moving base-tap window are introduced to improve robustness in practice.