Improving Process Performance of Ethylene Crackers

Ethylene production rate in a cracking process depends on the temperature distribution/heat flux profiles in the cracking tubes. Asymmetrical temperature distribution on radiant tubes can lead to high coking rates and increase frequency of the decoking cycle. It can also lead to development of high thermal stresses in the tube and reduce its lifespan. Burner configurations and geometry of the cracking tube play important role in the temperature distribution, coke formation rate and ethylene production rates in an ethylene cracker.

In this study computational fluid dynamics based models are used to study velocity & temperature distribution in the cracking furnace. Temperature distribution in the existing furnace is improved by optimizing burner configuration. Important reactions inside the radiant tubes for Ethylene formation are also modeled. CFD model is able to predict the radial temperature & concentration distribution in the tube which plug flow model fails to predict. Two reactor designs are evaluated to compare radial variation of Ethylene formation in the reactor tube.  The work presented in this paper showcases opportunities to design new radiant tube shapes and evaluate burner configurations with the goal of improving cracker performance.