Continuous polymerization of methyl methacrylate in a taylor-couette reactor. I. Influence of fluid dynamics on monomer conversion

A Taylor-Couette reactor offers certain advantages for continuous polymerization over other reactor types. These advantages are its rather narrow residence time distribution (series of vortices) and its good heat transfer characteristics. Hydrodynamics in this type of reactor can be controlled by its geometry (diameter, gap, width, length) and its operational parameters (rotational speed, mean residence time, viscosity). In this article, a model is presented which is suited to answer the question of how hydrodynamics influences the productivity of a continuously operated Taylor-Couette polymerization reactor. To this end, productivity is quantified by the rate of monomer conversion. The model is specified and experimentally validated for the free radical polymerization of methyl methacrylate with the solvent xylene and 2,2-azoisobutyronitrile as the initiator. The model considers the following four phenomena: (i) Macromixing between the vortex cells is accounted for by an axial dispersion model. (ii) The dependence of viscosity on monomer conversion along the reactor is described by a viscosity model. (iii) Polymerization kinetics and its dependence on hydrodynamics are correlated from experimental data. (iv) The dependence of segregation index Is on the local energy dissipation is used to characterize micromixing within the vortices. POLYM. ENG. SCI., 2013. (c) 2012 Society of Plastics Engineers