The Simulation of a Controlled Tubular Reactor with Counter-current Heat Transfer

Abstract

The results of complete simulation of a plug flow reactor and a cascade of five continuous flow stirred tank reactors (CSTR) on a digital computer under transient open loop and controlled conditions are compared with the experimental results of the same system partially simulated as a cascade of five CSTR's. The forcing function was a 50% change in throughput rate. The partial simulation used an analogue computer for the reaction kinetics and the mass balance while all of the thermal features existed in real plant with continuous interaction between the computer and plant items. In particular the computer had flowrate and temperature input signals from the plant as necessary information for continuous calculation of the mass balance. The computer generated output signals corresponding to reaction heat release for each of the five stages in the cascade and caused this heat to be released by electrical immersion heaters situated in the plant and controlled by thyristors. The control systems investigated were feedback using a conventional controller, feedforward using the analogue computer as on-line controller and combined feedback and feedforward. The comparison between complete simulation and partial simulation shows limitations in each. Thus the complete simulation results, although obtained rapidly, were only as good as the model, whereas the partial simulation contained actual non-linear elements but required considerable analogue resources.