EFFECTS OF IMPERFECT MIXING ON LOW-DENSITY POLYETHYLENE REACTOR DYNAMICS

Earlier work considered the effect of feed conditions and controller c onfiguration on the runaway behavior of LDPE autoclave reactors assumi ng a perfectly mixed reactor. This study provides additional insight o n the dynamics of such reactors by using an imperfectly mixed reactor model and bifurcation analysis to show the changes in the stability re gion when there is imperfect macroscale mixing. The presence of imperf ect mixing substantially increases the range of stable operation of th e reactor and makes the process much easier to control than for a perf ectly mired reactor. The results of model analysis and simulations are used to identify some of the conditions that lend to unstable reactor behavior and to suggest ways to avoid reactor runaway or reactor exti nction during grade transitions and other process operation disturbanc es.