(18e) Radial Variation of Local Gas Holdup In a Bubble Column Reactor With Heat Exchanging Internals Using Four Point Optical Probe

Slurry bubble column reactors have been demonstrated to be the reactors of choice for the clean utilization and conversion of syngas and commercialization of the Fischer-Tropsch (F-T) synthesis due to their advantages over other multiphase flow reactors. The local spatial variation of the gas holdup is one of the key parameters of the gas holdup since it gives rise to pressure variations radially and axially leading to varied strengths in the large scale and small scale liquid re-circulations which are important aspects for both mass and heat transfer in bubble and slurry bubble columns. The radial variations of the local gas holdup have been studied in the past mainly in bubble columns without the heat exchanging internals. Therefore, the focus of this study is to investigate how the local gas holdup varies radially in bubble column equipped with dense mimicked heat exchanging internals. The experimental work was carried out in 0.14 m diameter Plexiglas column using a non-reactive system of air as the gas phase and filtered tap-water as the liquid phase at ambient conditions of temperature and pressure. The superficial gas velocities were varied from 0.08 to 0.45 m/s covering both the transition flow regime and the churn-turbulent flow regime. The internals used were vertical Plexigas rods of 0.013 m in diameter occupying 25 % of the column cross-sectional area. The four points fiber optical probe technique was used with a suitable algorithm to measure the local gas holdup at different radial locations. The distance of the probe from the column center was varied for every 0.0015 m. The experimental results obtained suggest that there is irregular variation of the local gas hold up in presence of dense internals which is a contrast to the regular variation observed in a bubble column without internals. The irregular variation is likely to affect the performance of the bubble column reactor. Detailed results and findings will be discussed in the presentation.