Coke Formation in Steam Cracking Reactors: Deciphering the Impact of Aromatic Compounds and Temperature on Fouling Dynamics

Abstract

Formation of coke poses a considerable challenge in steam cracking reactors utilized for olefin production, exerting detrimental effects on the reactor performance and productivity. To tackle this challenge, a more profound understanding of fouling phenomena and their intricate connections with feedstock composition and process conditions is imperative. While conventional wisdom suggests that all aromatics contribute to increased coke formation, our research challenges this assumption. To evaluate this assumption, an investigation was conducted to measure the coking tendency of single-ring aromatics, double-ring aromatics, and naphtheno-diaromatic compounds by introducing them to a naphtha sample. On one hand, the incorporation of single-ring aromatics, up to 9 wt %, resulted in a 12% reduction in the overall coke formation rate across the radiant and TLE sections. Conversely, the introduction of 2 wt % double-ring aromatics exhibited a marginal 4% increase in coking rates. However, the introduction of a naphtheno-diaromatic compound led to a 35% increase in coke formation rates in the radiant and TLE sections. On the other hand, temperature emerged as a more significant factor influencing coke formation within steam cracking reactions. Elevating the coil outlet temperature (COT) from 950 to 970 °C resulted in a minimum 40% rise in the asymptotic coking rates. This study underscores the importance of comprehending coke formation mechanisms in steam cracking reactors and developing effective methods to mitigate fouling.