Modeling and experimental investigation of a Wurster type fluidized bed reactor (W-FBR) coupled with an air Atmospheric Pressure Plasma Jet (APPJ) for the treament of PolyPropylene (PP) powders
Abstract
PolyPropylene (PP) powders are used for various purposes. However, its good
mechanical properties are accompanied by a poor wettability. The PP powder was
therefore modified by a pulsed arc air blown atmospheric pressure plasma jet (APPJ) in a
home-made Wurster fluidized bed reactor (Wurster-FBR). The physical and chemical
modifications of the treated PP powders as compared to the nontreated ones were
determined by water contact angle (WCA) measurements, X-ray photoelectron
spectroscopy (XPS), and SEM for morphology observations.
The average diameter of our PP powders being determined to be 700 μm, they can be
classified as particles of category B according to Geldart classification which can be
easily fluidized. PP powders are basically hydrophobic but after plasma treatment in the
plasma enhanced fluidized bed they became strongly hydrophilic, because of the oxygen
uptake of the surface of the particles determined by XPS. The plasma torch was
introduced into a transparent glass reactor with 118mm inside diameter, placed in the
middle of a bronze gas distributor. An internal Wurster tube was added to control the
residence time of the particles in the plasma jet, and therefore the homogeneity of the
treatments.
A 2D axisymmetric non-isothermal model was developed using Comsol Multiphysics 5.3
along with this experimental study to characterize the air-flow hydrodynamics and
temperature profile. These investigations are very important since PP is a thermally
sensitive material and to avoid its thermal degradation. The k-e turbulent model in
computational fluid dynamic (CFD) was applied to simulate the mean flow characteristics
for turbulent flow.