Different Approaches in Concentration-Temperature Cascade Control of a Fixed Bed Reactor for the Phthalic Anhydride Synthesis

Abstract

This paper presents six different approaches for concentration-temperature type cascade control of a fixed bed reactor for the production of phthalic anhydride by oxidation of o-xylene. In the cascade scheme, a primary loop is responsible for controlling the phthalic anhydride exit concentration, while a secondary loop, based on temperature measurements in key positions along the reactor, maintains an optimal temperature profile. Simulations demonstrate the adequacy of the mean value of four temperature measurements monitored in the hot spot region to define the control action for manipulation of the heat rate that should be removed by the thermal fluid.