Abstract
A by-product from the ferrosilicon process is process gas which escapes into the furnace hood were it reacts with air. The process gas mainly consists of CO with some SiO and moisture. Modeling the gas behavior inside the furnace hood is challenging due to the complex interaction between flow, reactions, radiation and turbulence. One of the issues is the selection of proper boundary conditions, especially, the boundary condition used for the charge surface through which the process gas is released, which strictly is neither a wall surface nor a mass flux boundary. Traditionally, this boundary condition is modeled as a mass flux boundary, without considering the effect of roughness due to uneven distribution of charge material. In present study, effect of accounting charge surface as a rough wall on the flow distribution is discussed. The results obtained from this study is compared with a simulation, where charge surface is modelled as a mass inlet boundary condition. Another issue is the boundary condition accounting for SiO burst. It is observed that process gas is frequently released in local bursts typically with a high concentration of SiO. This is believed to promote local hot spots, which favor NOx formation. Bursts of SiO are modeled and results show that both the strength of the burst and its location play a significant role in the NOx production.