Radiotracer investigation in cross flow reactor using Bromine-82 and Technetium-99m

Hydro processing is the most promising secondary refining process for treatment of heavier feed-stocks. A cross flow reactor (CFR) are most promising reactor to carry out these reaction more efficiently than conventional trickle bed reactors. However, it difficult to scale up these reactors due to complex hydrodynamics of the liquid phase in the CFR. The time spent by the process fluid in the reactor, their holdup and degree of mixing are critical parameters for designing and operation of the CFR. In this study two different radiotracers, such as, ⁸²Br (t1/2: 36h, γ: 0.55 MeV(70%), 0.776 MeV (85%)) as ammonium bromide and ^99mTc (t1/2: 6h, γ: 0.14 MeV(87.7%)) as sodium pertechnetate were used to trace the aqueous phase. Sufficient amount of the radiotracer was instantaneous injected into the column and its movement was monitored at inlet and outlet of the bed using collimated NaI(Tl) detectors. The mean residence time of the liquid phase measured by the Br-82 was found to much larger than the theoretical estimated parameters. It is due to presence of the long tail in the RTD curve in-case of ⁸²Br as compared to the ^99mTc. The long tail was due to adsorption of ⁸²Br in the inner walls of the outlet section. Hence ^99mTc was found to be an ideal tracer in the present study