(28b) Side Reboiler Redesign Improves Alky Isostripper Operation

In 2004, the Valero Texas City Alkylate Isostripper was revamped with high capacity trays to improve the tower capacity. Results from the revamp were less than expected and the tower was revamped again in 2006.  This revamp also proved to be less than successful.

In 2007, troubleshooting was initiated in order to locate and fix the problems. It was thought that the trays were not the problem, but a detailed troubleshooting strategy was put together. Troubleshooting revealed that the tower was flooding due to design issues in the side reboiler circuit. There were several design issues with the reboiler circuit design that resulted in limitations and premature tower flooding.

Reboiler draw tray and side reboiler circuit modifications were initiated to improve the tower capacity. After almost 4 years of operation, post-revamp data indicates that the tower is meeting all expectations.  Changes increased the side reboiler duty and improved product quality, while meeting all the capacity expectations for the revamp.