Modelling, design and flexibility analysis of rotating packed beds for distillation

• The equiareal discretisation approach for discretising rotors is proposed.
• The integrated centrifugal acceleration is developed for mass transfer calculation.
• Flexibility maps are developed and applied to highly flexible distillation.
• RPBs show good suitability for highly flexible distillation processes.

Chemical production plants need to be more flexible to react on changing raw materials quality and plant capacity. The high gravity technology (HiGee) for separation of mixtures into components meets those needs since its separation efficiency can be easily adjusted by changing of rotational speed. This paper is devoted to development of a comprehensive model and integrated design method for the centrifugal distillation in rotating packed beds (RPBs). The model uses known correlation equations for hydrodynamics as well as new correlations for mass transfer. Novel concepts of equiareal discretisation and integrated centrifugal acceleration are developed and implemented. The model is the core of an integrated design method for calculation of structural and operating variables for distillation in RPBs for analysis during conceptual process design. It also predicts the power consumption, required equipment space and investment and operating costs. The integrated design method is applied to a flexibility analysis of RPBs for compensation of fluctuations in feed compositions of distillation processes by adjusting the rotational speed. Heuristic rules and flexibility indicators using flexibility maps are developed and applied. Results show the applicability of the design method and prove the suitability of RPBs for highly flexible distillation processes.

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