Pseudo-transient models for multiscale, multiresolution simulation and optimization of intensified reaction/separation/recycle processes: Framework and a dimethyl ether production case study

•Multiscale models of intensified unit operations included in process design.•Pseudo-transient model reformulation ensures reliable simulation and optimization.•Demonstrated on intensified DME synthesis process with DWC, detailed reactor model.

Including detailed models of processing equipment in the process flowsheet model is required in the case of “non-standard” unit operations, including, e.g., intensified equipment and unconventional reactor designs. We provide a unified multiscale framework for including such models in equation-oriented process flowsheet modeling, simulation and optimization. Relying on the reaction/separation/recycle process prototype, we propose a multiresolution paradigm, whereby detailed, distributed-parameter representations of reacting systems and rigorous models of (intensified) separation units are embedded in process flowsheet models. We develop an equation-oriented modeling approach based on a pseudo-transient reformulation of the balance equations, enabling the reliable and robust simulation of the process flowsheet. We also describe a companion design optimization routine. We illustrate these concepts with an extensive case study on dimethyl ether production using an intensified process featuring a dividing-wall distillation column and an adiabatic packed bed reactor with intermediate quenching.