Multichordal Gamma Scans with Quantitative Analysis for Diagnosing Tray Maldistribution

MULTICHORDAL GAMMA SCANS WITH QUANTITATIVE ANALYSIS: KEY TO DIAGNOSING TRAY MALDISTRIBUTION

Henry Z. Kister, Fluor Corp., Aliso Viejo, CA

Large-diameter olefins towers like primary fractionators and C3 Splitters occasionally experience liquid and/or vapor maldistribution in either conventional or high-capacity trays. Such maldistribution often leads to tray efficiencies much lower than design, forcing an increase in reflux and reboil in the tower, and limiting tower capacity. When such maldistribution occurs, it may be difficult to diagnose using conventional troubleshooting techniques such as vendor software, delta P measurement, and conventional single-chord qualitative gamma scanning. Judicious multichordal gamma scanning with quantitative analysis is a very useful tool for diagnosing maldistribution on trays. This paper discusses this technique and describes its application in a couple of case studies.