Open-loop dynamic analysis of the catalytic oxidation of vocs with heat recovery

Abstract

In this contribution, the open-loop dynamic behavior of the heat-integrated reactor for VOCs catalytic oxidation process is analyzed and the key variables that determine the stability of the system are studied. Systems with heat recovery often exhibit open-loop instability as a result of the positive heat feedback to the reactor. The results of the simulations demonstrate the existence of multiple steady states in the Reactor/FEHE/Furnace system, for the explored range of reactor inlet temperatures. There exists a close relation between the multiplicity of steady states and system stability for variables of interest such as feed fraction circulating through the FEHE and furnace duty. Under certain operating conditions, the system shows strong oscillations that can lead to physical damage to the catalyst (sintered) or undesired situations of light-off of the reactor. Particularly, sustained oscillations appear near the extinction point, an operating zone of practical interest to reduce the energy demand of the process and extend the catalyst life, since total conversion of VOCs is achieved at relatively low reactor inlet temperatures. The dynamic behavior of the reactor and heat exchanger in this steady state zones are analyzed. Finally, the effect of residence time and reactor time constant on system stability is discussed.