Industrial & Engineering Chemistry Research, Vol.59, No.25, 11485-11493, 2020
Performance of Alumina-Forming Alloys under Coking-Decoking Cycles
Steam cracking reactors are continuously exposed to coking where a carbon layer is deposited on the walls and decoking where steam is introduced to remove the carbon layer. As a result of these coking-decoking cycles, the lifetime of the reactors decreases and the operational costs increase. These reactors are made from alloys that form a chromium oxide layer or, more recently, from alloys that form an aluminum oxide layer to protect against coking. This work studies the effect of coking-decoking cycle atmospheres on an alumina-forming alloy to a baseline chromia-forming alloy. After 10 coking-decoking cycles, the alumina-forming alloy had 85% less mass gained than that of the chromia-forming alloy. Additionally, microstructural and microhardness analysis show that carburization in the chromia-forming alloy was more severe. Results indicate that a higher performance and a possible reduction in coking-decoking cycles can be attained when implementing alumina-forming alloys.