Towards the integration of chemistry and chemical engineering for innovative process and materials synthesis
Systematic methods and tools for managing the complexity
Process Synthesis & Design - I (T4-1a)
Keywords: Process Synthesis, catalysis, multi-scale modelling
The current approach to the development and design of a chemical process is largely sequential. Specific issues such as the evaluation of catalyst performance, the design of reactors or the design of separation systems are addressed as separate steps one at a time. The overall success of the design activity is hampered by the lack of systematic support tools to assist the scientists and engineers involved in the design processes to identify innovative solutions reliably and quickly in the context of the overall design goal, i.e. to identify the best possible process system that is comprised of these subsystems. Methodological shortcomings are exemplified by the lack of coordination of kinetic model development, reactor design and process synthesis. More often than not, kinetic models are developed for operating regions that do not correspond to the optimal values identified later on in process synthesis when the experimental studies have long been concluded. The result is either a compromise design dominated by kinetic model reliability issues or a project delay caused by additional experimental investigations of the kinetics. Technological shortcomings are exemplified by current conceptual process synthesis tools: the available tools for the generation of innovative design candidates are limited to systems of very moderate complexity and quickly fail as complexity increases. Although successes of process synthesis methods have been significant even for simple systems, most industrially relevant systems are considerably more complex and cannot be addressed with existing technology. However, if reliable methods to address such systems can be developed, step changes in innovation are to be expected.
Our work aims at the development of methods that will allow systematic capitalisation on synergies across the chemical process development cycle. Initially, we have focused our interests on the basic research and development issues required to realise an integrated approach in which the key process design issues can be addressed in parallel to the investigation of the chemistry from the earliest stage to arrive at the most economically viable and sustainable design via the shortest possible route. We will report on technology developments for the integrated conceptual design and evolution of processes with heterogeneously catalysed gas-phase reactions on the basis of available kinetic information. Building upon previous efforts in process synthesis, we have developed a multi-scale approach, which starts from conceptual design to screen vast numbers of processing alternatives for optimal designs. This conceptual stage employs superstructure models embedding combinations of ideal reactor models with practical constraints on heat exchange and explosion limits that can be realized in practice and exploits trade-offs between the reaction and separation systems to identify promising process candidates and operating conditions. As practical processes for heterogeneously catalysed systems can never achieve ideal behaviour, subsequent synthesis stages enrich the reaction models to incorporate nonideal behaviour so that the process designs can be evolved into optimal schemes that can easily be reached in practice. Throughout the multiscale design cycle, information on the optimal operating envelopes is generated and can be fed back to the kinetics development team to guide additional experiments so as to ensure that kinetic models match the optimal process in which the catalyst is to be used. We will demonstrate the technology developments with industrially relevant applications including the production of acetic acid. The systems have been chosen as their highly complex reaction networks are representative for the complexities of many heterogeneously catalysed gas-phase systems. With our approach we have identified novel processing schemes with significantly improved performances as compared to conventional process designs.
Presented Monday 17, 12:11 to 12:30, in session Process Synthesis & Design - I (T4-1a).
