Gamma Photon Column Scanning of Prototype and Industrial Distillation Columns

Abstract

Monte Carlo simulation of gamma photon transport and interaction with the distillation column and its contents was performed in order to predict the effects of gamma photons when they interact with matter. The results of the interaction and transport of gamma photons are presented as energy deposition on the distillation column and its contents. Energy attenuation was more pronounced on the column walls and trays as compared to the region between the trays, where there is mostly vapour space. Gamma column scanning was then used to verify the Monte Carlo simulation results by scanning and investigating the integrity of two laboratory prototype distillation and industrial distillation columns. One of the prototype distillation columns was 1 m tall with four trays and the other one was 1.8 m tall consisting of six trays and a packed bed. Commonly encountered distillation column malfunctions such as collapsed tray, weeping, flooding and foaming were simulated in the two prototype distillation columns and scanned. The industrial distillation column was a 26 m tall benzole prefractionator column, consisting of 60 single pass trays and a diameter of 0.8 m. A 10 mCi 60 Co gamma radiation source and NaI(Tl) scintillation detector were used to scan the distillation columns. The results from the two prototypes showed that all the simulated malfunctions were clearly detected except for foaming. The results from industrial distillation column showed that all the trays were in their correct position although tray number 32 could be partially damaged and just below tray 41, the scan revealed that there was a loss of column wall thickness. The obtained density profile for the industrial distillation column showed some small variations from the expected density profile and this was attributed to external features on the distillation column and wind bursts that shifted the source and detector from the chosen scan line orientation.