Gas Phase Back-Mixing in a Mimicked Fischer-Tropsch Slurry Bubble Column Using an Advanced Gaseous Tracer Technique

An advanced gaseous tracer technique and procedures were developed and executed to study for the first time the axial dispersion of the gas phase in a slurry bubble column reactor (SBCR) using air-C9C11-FT catalyst. Residence time distribution (RTD) curves were obtained by measuring the pulse-input’s response of the gaseous tracer. The gas phase axial dispersion coefficient (Dg) was obtained from minimum square error fit of the one-dimensional axial dispersion model to the measured tracer response data. The effects of solids loading on the axial dispersion of gas phase and the overall gas holdup have been studied. It was demonstrated that increasing solids loading improves the gas axial dispersion while decreasing the overall gas holdup. This work suggests that gas phase axial dispersion is significant in reactor performance evaluation of bubble columns or slurry bubble columns.

Observation of the Development of Secondary Features in a Richtmyer–Meshkov Instability Driven Flow

Richtmyer–Meshkov instability (RMI) has long been the subject of interest for analytical, numerical, and experimental studies. In comparing results of experiment with numerics, it is important to understand the limitations of experimental techniques inherent in the chosen method(s) of data acquisition. We discuss results of an experiment where a laminar, gravity-driven column of heavy gas is injected into surrounding light gas and accelerated by a planar shock. A popular and well-studied method of flow visualization (using glycol droplet tracers) does not produce a flow pattern that matches the numerical model of the same conditions, while revealing the primary feature of the flow developing after shock acceleration: the pair of counter-rotating vortex columns. However, visualization using fluorescent gaseous tracer confirms the presence of features suggested by the numerics; in particular, a central spike formed due to shock focusing in the heavy-gas column. Moreover, the streamwise growth rate of the spike appears to exhibit the same scaling with Mach number as that of the counter-rotating vortex pair (CRVP).