A pinch analysis approach to environmental risk management in industrial solvent selection

The problem of solvent selection in an industrial process has been examined in a number of different approaches, often including single- and multi-criteria optimization techniques. Traditionally, it has been addressed using techno-economic analyses and mathematical modeling techniques usually aiming at optimizing certain economic objectives such as maximizing profitability, minimizing cost and solvent usage. The proposed methodology offers an insightful environmental risk management framework for determining the optimal solvent profiles that can effectively match process requirements and at the same time ensure safe process performance. Through this approach, the risk aspects of utilizing a number of available solvents and their mixtures for particular process tasks were first examined and targets for the selection based on solvents’ safety characteristics, such as the permissible exposure limit, were established. This approach, when considered in conjunction with economic performance assessment, can be substantially useful, because it enables prioritization of solvent selection options based on insightfully tracking the degree of environmental risk performance in systems with complex chemical characteristics. A pinch analysis methodology enables the direct targeting of minimum solvent(s) utilization and optimal allocation of the appropriate solvents to process sinks based on their degree of environmental risk. The methodology can also provide solvent selection and design insights for enhanced usage in any industrial process system while highlighting appropriate sustainable solutions. A case study is finally presented to illustrate the applicability of the proposed methodology.

Graphical representation of the solvent selection and allocation problem addressed using the risk-based pinch analysis approach (where R_i is the risk index of solvent i, W_i, F_fr, G_j are the flowrates of sources, fresh and required flowrates of the sinks, respectively).