Leveraging fuzzy Logic PID controllers for accelerating chemical reactor CFD

Abstract

A control technique comprising three Fuzzy Logic Proportional Integral Derivative (FLPID) controllers was evaluated to determine their ability to shorten convergence times for the computationally expensive globally unsteady model of a low-density polyethylene reactor. The numerical reactor contained millions of computational elements, a rotating stirrer shaft, intricate near-wall geometry, and highly exothermic polymerization kinetics. Catalyst feed rates were instantaneously increased by 50% to evaluate the FLPID’s performance during a hypothetical process excursion. FLPID achieved quasi-steady state (QSS) 54% faster than conventionally tuned PID controllers. Reducing the percent overshoot of the error and rise time of the controller output, the FLPID demonstrated its ability to lower computational cost. FLPID in CFD offers the potential to improve control methods on actual plant scale processes. In particular, the reduction in error overshoot could reduce the likelihood of reactor overheat events as the temperatures are kept within a tighter operational window.