Simultaneous Optimization of Mass Exchanger Networks and Direct Reuse/Recycle Networks

Abstract

In the past two decades, various process integration methods have been proposed for the optimum synthesis of resource conservation networks, for the recovery of energy and material resources such as water, gas, and solvent. In this paper, a mathematical programming framework is proposed for simultaneous optimization of mass exchanger networks (MENs) and direct reuse/recycle networks (DRNs). Both MEN and DRN synthesis are now relatively established fields with numerous methods developed. Note however that there is a lack of work that considers both areas simultaneously. The newly proposed simultaneous optimization method in this work identifies opportunity for a DRN that allows the material waste to be recycled within the MEN, which is the main novelty of this work. The approach is demonstrated with a vinyl acetate monomer production problem. The latter consists of several mass exchange operations, in which an MEN is synthesized. Opportunity to develop an DRN is also identified, which allows its waste to be recycled without regeneration. Another novelty of the work is that, the supply and target compositions in the MEN problem are expressed in terms of mass ratios as the compositions are relatively large. Results show that the integrated network has a total annualized cost that is reduced by 24.9% as compared to the base case configuration, where both networks were solved independently. This shows the importance of considering entire process systems during process synthesis, as opposed to subsystems independently.