(81b) Fixing a Critical 2nd Stage Pygas Hydrogenation Reactor ?P Problem
- Conference: AIChE Spring Meeting and Global Congress on Process Safety
- Year: 2017
- Proceeding: 2017 Spring Meeting and 13th Global Congress on Process Safety
- Group: The 29th Ethylene Producers' Conference
- Time: Tuesday, March 28, 2017 - 8:30am-8:55am
The typical catalyst cycle time of the 2nd stage reactor, until the reactor reached a âP limit and required full catalyst replacement, ranged from 6 to 12 monthsâ. The root cause for the rapid fouling and âP growth was the presence of a high boiling tail in the feed to the vapor phase reactor. Insufficient vaporization resulted in liquid mist carryover into the reactor that caused rapid fouling. Once this understanding was reached, the site worked a variety of operational changes to reduce the amount of heavy feed components but could not totally eliminate them. Through close collaboration the plant incorporated a new reactor catalyst loading scheme that included a catalyst grading system of high void space inert and active catalyst components at the reactor inlet. The collaboration also used comprehensive kinetic models to optimize the operation of the entire reactor system to help mitigate the liquid carryover. The combination of operational changes and the new reactor loading scheme increased the cycle time to ~28 months, far exceeding any previous cycle length. Since the initial optimization the unit has been further optimized yielding a cycle life of ~40 months.