Gamma Scan Data Analysis using Segmented FFT Method to Verify Liquid Maldistribution in Distillation Column of VDU



Gamma scanning of the VDU was performed, to verify proper liquid distribution in the column section near Bed number 3. Gamma scanning was carried out in four chords and across two diameters 90 degrees apart. The recorded detector response (count-rate) data of each scan had analyzed using graphs, by co-relating it with column internals and also by comparing with each other. It was concluded that due to a faulty liquid distributor, the liquid is distributed unevenly in Bed number 3 of the column. This work has been published in 2016. From the graphs, it was not easy to derive the conclusions quickly. Also, the analysis done using graphs is qualitative in nature. The paper describes the study carried out to analyze the same data using the new segmented FFT method, without using graphs. In the study, the data was transformed into the frequency domain and then analyzed to interpret liquid maldistribution in the column. The results of the proposed segmented FFT analysis method are encouraging. It is concluded that the segmented FFT method of data analysis is better than the conventional chart-based method. Also, it is simple, fast, and quantitative.


segmented FFT, Gamma scanning, discrete Fourier transform

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