(179a) Monitor Fouling in Distillation Towers with Gamma Scanning

Henry Kister reports that plugging or fouling is the Number 1 malfunction in distillation/separation towers¹.  There are several types of fouling mechanisms though coking is more prevalent in refinery operations while scale formation or polymer fouling prevails in chemical plants.

In the case of any type of fouling inside a tower gamma scans can be very effective at pinpointing the location and severity of the problem in both trayed and packed towers. 

Baseline scans while the tower is clean provides a benchmark that serves as a reference for comparing with future fouling conditions.  Subsequent scans become much more meaningful for diagnosing and monitoring the fouling accumulations.  In the last few years some plant operators have begun to proactively monitor and mitigate their fouling problems by using gamma scans to routinely measure the presence and extent of this problem.

Three case studies are presented showing advantages of monitoring fouling tendencies with gamma scans.  These include a trayed tower showing where flooding starts due to fouling and how it progresses up the tower over time, a packed tower showing how fouling in the bottom of a packed bed builds and increases liquid retention over time and tomography monitoring for coke buildup in a refinery vacuum tower packed bed.

¹ Kister, Henry Z., Distillation Troubleshooting, Hoboken NJ, J. Wiley & Sons, Inc., 2006.