(106e) Front-End Acetylene Converter Exotherm Event due to O2 Ingress

The activity of front-end acetylene converter reactor is typically understood to be a function of inlet temperature, CO concentration, feed composition, and catalyst age. However, one factor often not considered or monitored is the presence of oxygen in the reactor feed. While oxygen should not normally be present in this stream in most olefins plant configurations, furnace operational issues or other feed stream contamination incidents can result in inadvertent air or oxygen ingress to the olefins recovery train. Oxygen can increase the acetylene converter catalyst activity by reacting with CO to form CO2, effectively reducing the CO concentration in the reactor and opening up more active sites for hydrogenation to occur. Depending on the configuration of the reactor temperature control scheme, this scenario can result in a runaway reaction.

This paper provides a case study of a front-end acetylene converter runaway event that occurred as a result of air ingress from an offline furnace. The case study will include a discussion of the root cause and preventative mitigations implemented at the site, and considerations for improving the reactor inlet temperature control scheme to provide a more robust response to oxygen contamination events.