Gamma scanning evaluation for random packed columns

In the present study, the liquid (water) holdup distribution was measured in a packed column (7.62 cm diameter) filled with 0.9 cm glass Rashig rings using noninvasive gamma ray technique. Three different radioactive sources: 11.1 MBq ⁶⁰Co (1133 keV), 74 GBq ¹³¹I (380 keV), and 740 GBq ^99mTc (140 keV) with a CsI(Tl) detector coupled to a photodiode were used to scan the column. The primary objective is to detect spatial patterns and statistical information on liquid distribution in packed distillation columns. Vertical scans, at different positions of the packed bed, were made for different liquid and gas flow rates. A mathematical relation based in the transmission radioactive by materials was used to calculate the spatial variation of liquid hold-up along the column. It was found that the liquid holdup distribution was not uniform and that the liquid distributor design had a significant effect on the holdup distribution. The system proved to be very useful in monitoring the condition of the process of packed column showing liquid distributions. The better results were found using a ^99mTc source. Flooded sections in the column can easily be identified using this technique