Numerical model of a shaft furnace operation

Abstract

PurposeThe model of a shaft furnace operation is presented in this paper. Aim of this model is to predict concentrations of carbon monoxide and dioxide, the temperature of the lava and the heat losses.Design/methodology/approachThe mathematical model is based on 1D mass and heat balance laws for flue gas, coke and four materials used in a mineral wool production. Process parameters should be optimized for the minimal heat loss and the carbon monoxide concentration while keeping the prescribed lava temperature. The model consists of heterogeneous and homogeneous reactions for coke combustion, dolomite decomposition, rock and coke heating and a rock-melting model. The resulting system of partial differential equations is discretized by the finite volume method and solved with the explicit Euler scheme together with the point-implicit preconditioning of sources in species balance equations.FindingsNumerical results are compared with the measured data on the pilot-scale device and show good agreement. It is found that in the lower region of the furnace, the large amount of carbon monoxide is present despite high oxygen levels.Practical/implicationsBased on the numerical model, the parameters of the secondary air stream could be studied (position, volume flux, oxygen enrichment and temperature) to decrease levels of carbon monoxide emissions while keeping lava temperature at needed levels.Originality/valueThe paper includes mathematical and numerical model needed for simulation of shaft furnaces in mineral wool industry. It can be used as a valuable tool for design engineers and furnace operators during research or redesign of existing devices.