Investigation of the Hydrodynamics of Fixed Bed Reactor: Co-current Upflow

Themain objective of this projectis to investigate the hydrodynamic characteristics of
co-current upflow of gas and liquid in a fixed bed reactor. This is an experimental
based project utilizing the packed bed reactor for residence time distribution (RTD)
studies. In this project, the RTD of a bench-scale multiphase was studied using air as
a gaseous phase andwater as a liquid phase. The ranges of air and water velocities are
kept at such levels as to simulate the hydrogen/oil ratios of typical bench-scale
hydroprocessing units. Theexperiments are conducted in upflow mode of operation in
the reactor, with increasing gas/liquid ratio. The effects of gas and liquid velocities on
different hydrodynamic parameters such as pressure drop and operating liquidholdup
are investigated. Operating the fixed bed reactor in upflow mode showed increase in
pressure drop, and decrease in operating liquid holdup. Three moments analysis,
which are mean residence time, variance, and skewness, are evaluated in order to
characterize the RTD. These three moments analysis revealed an increase in mean
residence time, and also increases in variance and skewness with increasing gas/liquid
ratio. Other parameters such as bed Pecletnumber of liquidand stagnant zonevolume
were also investigated with variation of gas and liquid velocities as to measure the
efficiency of the reactor. Decreasing Peclet number and stagnant zone volume
suggested the decreasing efficiency of the reactor, with increasing gas/liquid ratio.
The discrepancies in experimental results suggested that there are conditions to be
altered in order to eliminate the inconsistency.