Steel slag packed bed filter for iron and steel industry applications: Experimental study on pressure drop, filtration mechanics, and regeneration mechanics

Waste heat utilization offers significant potential to enhance process efficiency in the Iron and Steel industry. In electric arc furnace processes, packed-bed thermal energy storage enables temporal decoupling of volatile waste heat sources. High temperatures and high dust concentrations in the off-gas necessitate the development and investigation of filtration systems suitable for these conditions at low investment cost. This work experimentally investigates a slag-packed bed filter. The filtration efficiency, axial pressure drop distribution, and dust deposition are examined. Furthermore, characteristic filtration mechanisms are derived for increasing dust loading. To evaluate suitability for industry applications, regeneration capabilities are analyzed by measuring the pressure drop after filtration and the residual pressure drop after regeneration. A maximum pressure drop of 160 Pa to 320 Pa is measured. This range is one order of magnitude smaller than typical industrial limits. Filtration efficiencies are close to 99 %. The reported pressure drop and filtration efficiency underline the suitability of the proposed system. The pressure drop increase and dust deposition are concentrated in the first packed bed layer, which accounts for approximately 75 % of the total bed pressure drop at maximum dust loading. Depth filtration, pore blocking, and surface filtration are identified as the three characteristic filtration phases. Backflow regeneration reduces the first layer’s maximum pressure drop of 210 Pa to a residual pressure drop of 30 Pa. Vacuum regeneration further reduces the pressure drop to approximately 5 Pa.