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

A 3-D computational fluid-dynamics model containing equations for mass, hea t and momentum transfer and using a k-epsilon closure model, was used to ca lculate the 3-D flue-gas flow pattern and the corresponding 3-D temperature field for a pyrolysis furnace. The computational fluid dynamics model is c ombined with a reactor model for the cracking tubes and a radiation model f or the radiative heat transfer in the furnace box. Detailed reaction kineti cs for the naphtha cracking reactions in the tubes and a five-step reaction mechanism for the combustion of methane in the flames were used. This comp lete model reveals asymmetric flow patterns in a naphtha-cracking furnace w ith 4/2/1 split-coil reactors and fired with long-flame burners.