After more than fifty years of development the thermal cracking or pyrolysis of hydrocarbons has matured into the single most important process to produce ethylene. It is carried out inside tubular coils that are installed vertically in large fired heaters where the heat for the endothermic cracking reaction is supplied by a large number of hearth burners and/or wall burners. High heat fluxes are required to supply the heat for the endothermic reaction. Furthermore, the coils need to be operated at very high temperature to obtain reasonable conversions. Expensive Cr-Ni alloys have been developed that allow for metal temperatures over 1100℃. Historically, heaters have been designed using detailed process yield models with uniform temperature firebox models or simplified zonal firebox models. It was assumed that the burners themselves did not have a major impact upon the performance calculations and simply provided the heat.
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