Life Cycle Sustainability Assessment of Chemical Processes: A Vector-Based Three-Dimensional Algorithm Coupled with AHP

In this study, an integrated vector-based three-dimensional (3D) methodology for the life cycle sustainability assessment (LCSA) of chemical process alternatives is proposed. In the methodology, a 3D criteria assessment system is first established by using the life cycle assessment, the life cycle costing, and the social life cycle assessment to determine the criteria from the environmental, economic, and social pillars, respectively. The methodology incorporates the analytic hierarchy process (AHP) method to convert experts’ judgments on the soft criteria into quantitative data and realize a unitary scale for both quantified soft criteria and normalized hard criteria. After assigning appropriate weights to each pillar and criterion by using the AHP method, the sustainability of the alternative processes can be prioritized by employing a novel vector-based algorithm, which combines the absolute sustainability performance and the relative sustainability deviation of the investigated processes. A case study on the sustainability assessment of three alternative ammonia production processes demonstrates that the proposed methodology is able to serve as a comprehensive and rigorous tool for the stakeholders to rank and identify the most sustainable chemical process alternatives

Design and Multiobjective Optimization of a Novel Double Extractive Dividing Wall Column with a Side Reboiler Scheme for the Recovery of Ethyl Acetate and Methanol from Wastewater

This work presents the development of two novel intensified energy-efficient extractive distillation configurations for the separation of ethyl acetate and methanol from waste effluent while prioritizing economic, environmental, and safety performances. Departing from the typical three or four column extractive distillation process, we proposed two intensified processes that offer superior performance. Specifically, we introduced the extractive dividing wall column with a side reboiler (EDWC-SR), which combines the four columns into two, and the double EDWC-SR (DEDWC-SR), which combines the four columns into a single unit. Subsequently, multiobjective optimization and multicriteria decision making were used to obtain the optimum configurations for the three processes, i.e., base case, EDWC-SR, and DEDWC-SR. Both the EDWC-SR and DEDWC-SR gave better economic and environmental performances relative to the base case with slightly lowered safety performance. The DEDWC-SR gave the lowest total annual cost and CO2 emission by 20.20 and 33.81%, respectively, and a higher safety index by 18%, relative to the base case

Sustainability Assessment Framework for Chemical Processes Selection under Uncertainties: A Vector-Based Algorithm Coupled with Multicriteria Decision-Making Approaches

This article aims to develop a generic sustainability assessment framework for helping the stakeholders/decision-makers to prioritize chemical process alternatives under uncertainties. A comprehensive evaluation system that consists of both hard and soft criteria from the environmental, economic, social–political, and technical concerns was first constructed in the framework, in which different types of uncertainties with respect to the hard and soft criteria can be properly addressed by using the interval parameter and fuzzy analytic hierarchy process method, respectively. The fuzzy decision-making trial and evaluation laboratory-based analytic network process method, which can tackle the interdependences between the evaluation criteria and the uncertainty among humans’ judgments, was employed for weighting the criteria accurately. Afterward, a novel interval vector-based algorithm was developed for rigorously prioritizing the alternative processes via the integration of both the absolute sustainability performance and relative sustainability balance of each chemical process under uncertainty. The proposed framework was illustrated by a case study to prioritize the sustainability of five ammonia production processes. The robustness of the assessment result was tested by conducting the sensitivity analysis, while the effectiveness and advantages of the proposed framework were demonstrated by comparing the results derived by this framework with those determined using other multicriteria decision-making approaches

Optimal Synthesis of Water Networks for Addressing High-Concentration Wastewater in Coal-Based Chemical Plants

This paper outlines the development of an optimization-based method for synthesizing a water network, which incorporates various treatment technologies to address the high-concentration wastewater in coal-based chemical plants. One important feature of the proposed approach is that it associates a multistep wastewater treatment design within a source–regeneration–sink superstructure. This design can enforce certain design and structural specifications to tighten the model formulation and enhance solution convergence. A mixed integer nonlinear programming problem is formulated based on the proposed superstructure, which involves unit-specific shortcut models instead of the fixed impurities removal model to describe it accurately. The proposed method for water network synthesis is demonstrated using two case studies, which determine the effect of streams composition and wastewater treatment technologies on the total network cost, freshwater consumption, and water network design. The results highlight the ability of the proposed model for the developed water network synthesis by computing quickly and realizing the goals of cost savings and discharge reduction