Modelling and simulation of polymerisation processes

Abstract

In order to model the effects of uneven spatial distribution of components and temperature a computational fluid dynamics (CFD) model has been developed for a living polymerisation reaction in a tubular reactor. The low moments of the molecular weight distribution(MWD) and the dispersity index of the product as well as the more usual spatial concentration of species and temperature have been calculated. The modelling and simulation work was carried out using the CFD codePHOENICS version 2.1 on Pentium PCs. Additionally, a novel algorithm is describedwhich makes the design of reactor control strategiesmore tractable by providing a very rapid route to a qualitative approximation of the MWD of productsfrom living polymerisation processes. Numerically simulated data generated using this new procedure are compared with slower but more rigorous approaches to the same problem. The examples-cover living polymerisations in an isothermal batch reactor, a steady-state continuous stirred tank reactor (CSTR) and feed-perturbed CSTR. It is demonstrated that, although the novel algorithm comprises only four differential equations, it provides the essential information concerning the position and relative intensity of the peak(s) in a MWD plot needed for the design of reactor control strategies for the productionof tailored MWDs. © 1999 Elsevier Science Ltd.