(31e) Operating Experience and Enhanced Acetylene Reactor Performance

The two key parameters to consider for superior acetylene converter performance in an olefins cracker are selecting the right acetylene hydrogenation technology and maintaining stable operation. Since some operational upsets and system perturbations will inevitably occur, the converter catalyst utilized must be robust enough to manage these changes without degradation to the catalyst's performance and the unit's profitability.

Presented in this paper is operational data detailing the superior acetylene hydrogenation reactor performance of Chevron Phillips Chemical Company's Unit 24 olefin cracker located in Sweeny, Texas. Unit 24, a 1.5 billon pound per year rated E/P cracker with front-end DeEthanizer reactor configuration, operated the acetylene converter through two turnarounds for an unprecedented 12 years without regeneration. The history of this operation from catalyst loading through an analysis of the spent catalyst is presented.

The Unit 24 acetylene converter was loaded with E-Series catalyst in 1995 and successfully operated for the next 12 years through operational challenges including unplanned shutdowns from power outages, poisons introduced in the feed, and changes in feed composition. The catalyst maintained excellent activity and ethylene selectivity throughout the 12 year run. The E-Series catalyst easily handled episodes of thermal instability caused by swings in CO and endured many unit upsets without suffering long term performance degradation.

Unit 24 Engineers had at their disposal a proprietary kinetic and thermodynamic model based on first principles of thermodynamics and reaction mechanisms used to optimize reactor performance and predict impact and changes required to manage CO swings. The reactor model was also utilized to improve startups and to track the deactivation of the catalyst and predict the end of run.

In 2007, the catalyst was removed and analyzed. The catalyst was then regenerated by calcining it in air. The regenerated catalyst from Unit 24 displayed excellent activity and positive selectivity. The catalyst was subsequently installed into another ethylene cracker in the Sweeny Complex.