Three‐dimensional flow patterns in cracking furnaces with long‐flame burners

A 3‐D computational fluid‐dynamics model containing equations for mass, heat and momentum transfer and using a k‐ϵ closure model, was used to calculate the 3‐D flue‐gas flow pattern and the corresponding 3‐D temperature field for a pyrolysis furnace. The computational fluid dynamics model is combined with a reactor model for the cracking tubes and a radiation model for the radiative heat transfer in the furnace box. Detailed reaction kinetics for the naphtha cracking reactions in the tubes nnd a five‐step reaction mechanism for the combustion qf methane in the flames were used. This complete model reveals asymmetric flow patterns in a naphtha‐cracking furnace with 4/2/1 split‐coil reactors and fired with long‐flame burners.