The effect of operating conditions on the nitric oxide formation in anode baking furnace through numerical modeling

More Info


Thermal nitric-oxide (NOx) formation in industrial furnaces due to local overheating is a  widely known problem. Various industries made significant investments to reduce thermal NOx by varying the operating conditions and designs of the furnace. Finding optimal operating conditions or design parameters by experimenting in the furnace, however, is difficult. Numerical modeling can provide significant information in such cases. In this paper, a three dimensional steady state finite element model for the anode baking industrial furnace is discussed. The COMSOL Multiphysics software is used for modeling the non-premixed turbulent combustion and the conjugate heat transfer to the insulation lining. The mesh generation using the cfMesh software allows to increase the spatial resolution locally at the outlet of the fuel nozzles while maintaining the overall quality of the mesh. The temperature and species mass fraction obtained from the finite element model are calibrated by adjusting the amount of artificial diffusion in the transport equations for the species. The simulated temperature agrees well with the measured data from our industrial partner in regions distant from the flames. The model underestimates the measured oxygen mass fraction. The spatial gradients in oxygen mass fraction, however, are captured well by the model. The effects of variation of the fuel mass flow rate and the fuel pipe diameter on the NOx generation are studied. The results show that by decreasing the fuel mass flow rate and increasing the fuel pipe diameter by 45%, the peak in thermal NOx ppm generated in the furnace decreases by 42%.