Distribution of suspended particles in a Taylor–Poiseuille vortex flow reactor

Abstract

Vortex flow reactors (VFRs) are specially suited to work with shear-sensitive particles, due to the gentle and efficient stirring characteristics of Taylor vortices. For heterogeneous VFRs, the distribution of the solid phase must be accounted for in detail. This work presents residence-time distributions (RTDs) of agarose gel particles ( φ av =214 μm ), suspended in different liquid solutions. Reactor porosity was 90%. The mass transfer coefficients of a lumped-parameter model of the reactor are estimated from residence time distributions of a tracer. The VFR has radius ratio η=0.664 and aspect ratio Γ=14.9. Axial flow rates were selected to provide a mean residence time of 1850 s, adequate for many applications. Minimum rotation rates of the inner cylinder were imposed by suspended particles’ homogeneity criteria. The VFR operational region was: 0.0645< Re ax<0.592 and 98< Re θ <3820, corresponding to very high values of the ratio Re θ / Re ax (between 5293 and 6236). Under these conditions, the vortices were stationary, and circumvented by a by-pass stream. Our results indicate that the gel particles are unevenly distributed in the vortex core and by-pass regions. Mean residence times for the particles are substantially greater than for the liquid. The mathematical model presented here can accommodate this behavior, using a partition coefficient for the solid phase.