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This work introduces a multiobjective optimization approach to integrate the design and control of multicomponent distillation sequences. The evaluation of the control properties and the design of the distillation systems were evaluated through the calculation of the condition number and the total annual cost of each design, respectively. Three distillation systems, including the direct sequence, the indirect sequence, and the dividing wall column along with three mixtures with representative ease of separation index (ESI) values and three different feed compositions, were studied. In addition, in a posterior stage to the optimization process, the Eco-indicator 99 for each design was estimated to quantify the environmental impact of the distillation systems. The results offer the trade-offs between the control properties and the design, which is shown through Pareto optimal solutions that enable selection of the solutions that establish the proper balances between both objectives.

Currently furfural production has increased the interest because of it is a bio-based chemical able to compete with fossil-based chemicals. Furfural is characterized by flammability, explosion and toxicity properties. Improper handling and process design can lead to catastrophic accidents. Hence it is of utmost importance to use inherent safety concepts during the design stage. This work is the first to present several new downstream separation processes for furfural purification, which are designed using an optimization approach that simultaneously considers safety criteria in addition to the total annual cost and the eco-indicator 99. The proposed schemes include: thermally coupled configuration, thermodynamic equivalent configuration, dividingwall column, and a heat integrated configuration. These are compared with the traditional separation process of furfural known as Quaker Oats Process. The results show that due to a large amount of water present in the feed, similar values are obtained for total annual cost and eco-indicator 99 in all cases. Moreover, the topology of the processes has an important role in the safety criteria, the thermodynamic equivalent configuration resulted as the safest alternative with a 40% of reduction of the inherent risk with respect to the Quaker Oats Process and thus it is the safest option to purify furfural.

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BACKGROUND: Ethyl levulinate (EL) is an important chemical that can be used as a bio-based replacement of fuel additives such as methyl tert-butyl ether (MTBE) and tert-amyl methyl ether (TAME). EL production from lactic acid and ethanol is a viable option, as both precursors can be obtained from biomass. However, the problem of EL production by esterification is that this reaction is hindered by the chemical equilibrium limitations and the boiling points ranking, which is not the most favorable. RESULTS:This study provides novel optimally designed reactive distillation (RD) processes for the production of EL, taking into account costs, environmental impact and safety. The thermally coupled RD process is the most appealing, with the lowest energy use (1.667 MJ kg −1 EL), minimal investment cost, major energy savings (up to 54.3% lower than other RD processes), reduced environmental impact (up to 51% lower ECO99 index value) and similar safety as other RD processes considered (less than 2% differences in the individual risk (IR) indicator). CONCLUSION:The multi-objective optimization approach used here showed its robustness, practicality and flexibility to provide multiple optimal designs of intensified processes that are economically attractive, environmentally friendly and inherently safe. The first separation column (RC-1) performs the separation of water by-product as distillate from the main product (EL) and the unreacted LA. The second separation column (RC-2) wileyonlinelibrary.com/jctb Process optimizationThis study uses a multi-objective meta-heuristic optimization algorithm based on differential evolution and tabu list (MODE-TL), further details of which can be found elsewhere. 34 This algorithm allows the comparison of multiple solutions of optimized designs in the terms of multiple objective functions, described hereafter.

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