In this work, we aimed to predict the flue gas side performance of a refining vacuum furnace with floor gas burners. The computational fluid dynamics (CFD) approach was employed to simulate the flow, combustion, heat transfer and NO emission. Detailed insights into the flue gas velocity, temperature field and NO mass concentration distribution were obtained with the aid of velocity vectors and contour snapshots. The standard k-epsilon. model was applied to turbulence simulation. The non-premixed turbulent flames and NO emission were predicted using the Laminar Flamelet model. The discrete transfer model (DTM) was applied to the radiative heat transfer simulation. Comparative simulation cases were carried out to investigate the effect of excess air amount on the flue gas temperature distribution and NO emission. Calculations were performed using the commercial packages ANSYS CFX 14.0. (C) 2014 Elsevier Lid. All rights reserved.