(546a) Experimental Validation of a Novel Model for the Micromixing Intensity

Experimental
validation of a novel model for the micromixing intensity in a rotor-stator
spinning disc reactor

Frans Visscher, Xiaoping Chen, John van der Schaaf, Mart de Croon, and Jaap C. Schouten

Laboratory of Chemical Reactor
Engineering, Eindhoven University of Technology, The
Netherlands

Introduction

The
characteristic timescale for micromixing are determined for a rotor-stator
spinning disc reactor. This reactor consists of a rotating disc which is
enclosed by two stationary discs and a cylindrical housing and is shown in
Figure 1.

Figure 1. Rotor-stator spinning disc reactor configuration. Upon
rotation of the rotor, the shear forces between the rotor and the stator cause
high turbulence intensity.

Previous
research showed that intense mixing of multiphase processes can be achieved in
this reactor (Visscher, van der Schaaf et al. 2011). For a chemical process
with competing reactions, the yield and selectivity are influenced by the
mixing efficiency at micro scale in a reactor (Baldyga
and Pohorecki, 1995). The mixing at micro scale can
be characterized with the iodide-iodate reaction system (Fournier, Falk et al.
1996b;Fournier, Falk et al. 1996a). This reaction
system is based on two parallel reactions that are competing for the acidic
protons.

The Dushman
reaction (Reaction 2) is fast, in the same range of the micromixing process, but
is much slower than the pseudo-instantaneous neutralization reaction (Reaction
1). Therefore the product distribution of the reactions 1 and 2 can be used to
represent the mixing intensity at micro scale. This product distribution at the
reactor outlet can be determined by measuring the triiodide
concentration with in-line UV-VIS spectroscopy.

The product distribution is
correlated to the timescale of the micromixing process through a novel model
which is applicable for ideally mixed systems. This correlation is a function
of turbulence intensity, and operational conditions like the specific proton
donor, volumetric flow rates, concentrations, and the reactor temperature. The
trends predicted by the model are validated using the rotor stator spinning disc
reactor.

Reference List

Visscher,
F., van der Schaaf, J., de Croon, M.H.J.M., and Schouten, J.C., 2011
Liquid-liquid mass transfer in a rotor-stator spinning disc reactor. Annual AIChE meeting 2011, Minneapolis,
MN.

Baldyga, J. and Pohorecki, R., 1995. Turbulent
micromixing in chemical reactors -- a review. The Chemical Engineering
Journal and the Biochemical Engineering Journal 58, 183-195.

Fournier,
M.C., Falk, L., and Villermaux, J., 1996a. A new parallel competing reaction system for assessing micromixing
efficiency - Experimental approach. Chemical
Engineering Science 51, 5053-5064.

Fournier,
M.C., Falk, L., and Villermaux, J., 1996b. A new parallel
competing reaction system for assessing micromixing efficiency--Determination
of micromixing time by a simple mixing model. Chemical
Engineering Science 51, 5187-5192.