Assessment of energy saving potential of an industrial ethylene cracking furnace using advanced exergy analysis

Steam cracking furnace is a high energy-consuming equipment in the ethylene plant. Reducing the exergy destruction and losses associated with the steam cracking furnace can increase the thermodynamic efficiency of the system and thereby reducing energy penalties. This paper aims to quantitatively evaluate thermodynamic performance of an industrial steam cracking furnace through conventional and advanced exergy analysis in order to assess its energy saving potential. A steady state simulation of an industrial steam cracking furnace with a total feed capacity of 12 t/h was carried out. The simulation was validated by comparing the model prediction results with the industrial data. The conventional exergy analysis shows that the overall exergy efficiency of the steam cracking furnace is found to be 43.43% and the combustion process in the radiation section exhibits the largest exergy destruction followed by the tube reactors in the radiation section. The advanced exergy analysis shows that the combustion process has the highest unavoidable exergy destruction. Moreover, the tube reactors in the radiation section has the highest avoidable exergy destruction, followed by the combustion process and the feed-steam mixture superheater in the convection section. Therefore, there is high energy saving potential in the tube reactors, combustion process and feed-steam mixture superheater. The advanced exergy analysis also indicates that efforts on improving the radiation and convection sections should be dedicated to themselves while the thermodynamic performance of the quench system should be improved by reducing the exergy destruction of other interacting components.