Abstract: Aimed at a walking beam reheating furnace of a steel rolling mill, a mathematical model for the gas phase flow and combustion in the furnace and the heating process of the slabs was established by Fluent software, and the user-defined function was developed to deal with the movement of the slabs. The Realizable k-ε model was adopted for modeling the gas flow in the furnace, the non-premixed combustion model was used for the combustion process, and the radiative heat transfer adopted the discrete ordinates(DO) model to calculate. Through the established mathematical model, the effects of combustion of flue and the oxidizer with oxygen volume fraction of 21%-35% on heating characteristics of the slabs were simulated. The results show that with the increase of oxygen concentration, the temperature of the flue gas in the combustion zone gradually increases, resulting in a faster heating rate of the slab. Because oxygen-enriched combustion produces a more uniform temperature field in the combustion zone, when the oxygen concentration increases to 35%, the black mark temperature difference of the slab is only 15 K, which is 20 K lower than that under the air condition. When the volume fraction of oxygen in the oxidizer increases from 21% to 35%, the radiant heat transfer of the slabs also increases, and the thermal efficiency of the heating furnace increases from 41.1% to 48.4%.

Key words: reheating furnace, oxygen-enriched combustion, slab, numerical simulation, heating characteristics