The FluxMax approach: Simultaneous flux optimization and heat integration by discretization of thermodynamic state space illustrated on methanol synthesis process

Abstract

Resource efficiency is a key driver in the chemical industry for both economic and ecological reasons. However, often the design of chemical processes or units and the corresponding heat integration, is divided into two design phases: a flow optimization to identify an optimal design and the subsequent evaluation of the heat integration potential. This procedure cannot guarantee the identification of the global resource optimum, which increases the need for a method that can do both simultaneously. This is the aim of the FluxMax approach that discretizes the thermodynamic state space. The introduction of nodes corresponding to mixtures, elementary processes and utilities allows the representation of any chemical process as a directed graph, which decouples effectively process-based nonlinearities from the optimization problem. Heat integration is considered by additional constraints. Using the methanol synthesis process as example, energy-optimal process configurations are identified that outperform configurations identified in a sequential procedure.