(113b) Distillation Tower Startup Considerations in Ethylene Plants

Ethylene plant startup involved load and composition transition on distillation towers, that if not properly handle could result in un-expected constraints as rates are being increased to production target. Beside affecting unit capacity, startup mal practices may prolong unit downtime along with lost of valuable chemicals to flare. This paper discusses, through a case study focused on Demethanizer, Deethanizer and C2 Splitter, potential startup problems and describes practices enabling smooth transition of towers to steady state conditions. The discussion covers individual tower startup parameters but also includes interactions through the distillation train. Potential for cold temperature and over pressure excursions is also discussed.