Computational Modeling of Walking Beam Type Reheat Furnace for the Prediction of Slab Heating and Scale Formation

Abstract

Computational modeling using the high-viscosity laminar flow approach was applied to study the effect of slab crossing time on slab heating and scale growth. Simulation of an existing industrial walking beam reheating furnace with four zones, outer refractory body, skid, slab, and fluid zone is considered. The fuel used was a mixture of coke oven and blast furnace gas. Preheated air is supplied co-axially with the fuel mixture. The combustion simulation is performed using the constrained equilibrium mixture fraction model. From the results, it has been observed that with an increase in slab residence time, the slab temperature and scale growth increase across the slab. For the system considered, with a fuel mass flowrate of 70,000 kg/h, 150–180 min of slab crossing time is appropriate to obtain desired slab temperature at the discharge end. The overall equivalence ratio is taken as Φ = 1 (fuel/air ratio is the same as stoichiometric ratio). The maximum slab scale thickness is evaluated as 2.4 mm at the discharged end for 180 min of slab crossing time.