Rate of coke formation of centrifugally cast austenitic chromia-forming and alumina-forming alloys in coking conditions

The coking kinetics and the long-term coking performance of an alumina-forming alloy against a traditional chromia-forming alloy was studied in a hydrogen-ethane coking atmosphere. After 1000 h of exposure, the alumina-forming alloy had 91% less mass gained compared to that of the chromia-forming alloy. Additionally, microstructural analysis showed that the carburisation attack in the chromia-forming alloy was more severe, especially at a higher temperature and at a higher exposure time. Results indicate that a better performance in coking conditions can be attained when implementing alumina-forming alloys.