Probing the Impact of Electric Heating on the Design, Dynamics, and Operation of Integrated Chemical Processes

Abstract

We study the impact of switching from combustion heating to electric heating in integrated processes comprising high-temperature-reaction/separation/recycle sequences, where the heat supporting the reaction(s) is provided mostly or entirely by combusting a byproduct/fuel gas. A canonical process structure is defined. It is shown that the conventional integrated process design with combustion heating presents feedback interactions due to the impact of the downstream units (via the heating value of the fuel gas) on the upstream units. These interactions are absent in the electrified process, with electric heating thus having a “de-integration” effect. An asymptotic analysis is utilized to investigate the dynamic responses of the two process structures. It is demonstrated that the dynamic behavior of the two processes exhibits two time scales, with the faster one corresponding to the evolution of the temperatures of the units with high heat duty and the slow time scale capturing the variables involved in the material balance. A simplified ethylene cracking process example is used to confirm the theoretical findings and their operational implications.