Abstract:
A systematic computer-aided framework for sustainable process design is presented. The framework integrated with various methods, tools, algorithms and databases is based on a combined process synthesis-design-intensification method. The synthesis-stage involves superstructure based optimization to identify promising networks. The design-stage involves selection and analysis of the identified networks as a base case design in terms of operational feasibility, economics, life cycle assessment factors and sustainability measures, which are employed to establish targets for improvement in the next-stage. The innovation-stage involves generation and screening of the more sustainable alternatives through a phenomena-based process intensification method. The proposed framework was applied to the CO2-based DMC production process. A superstructure of processing routes including CO2 direct synthesis and indirect syntheses via urea, ethylene carbonate and propylene carbonate, was generated and evaluated to determine the most promising processing route, which was then analyzed in detail to identify design improvement targets. Through a phenomena-based method, new more sustainable process alternatives matching the design improvement targets were identified. For the evaluation of alternatives, the measures include sustainability metrics, economic potential indicators as well as LCA factors. The urea route with reactive distillation was found to be the best alternative, offering superior performance to the conventional BAYER process.
