Periodic systems are widely used in separation processes and in reaction engineering. They are designed for and operated at a cyclic steady state (CSS). Identifying and optimizing the CSS has proven to be computationally challenging. A novel framework for equation-oriented simulation and optimization of cyclic processes is introduced. A two-step reformulation of the process model is proposed, comprising, (1) a full discretization of the time and spatial domains and (2) recasting the discretized model as a differential-algebraic equation system, for which theoretical stability guarantees are provided. Additionally, a mathematical, structural connection between the CSS constraints and material recycling is established, which allows us to deal with these conditions via a “tearing” procedure. These developments are integrated in a pseudo-transient design optimization framework and two extensive case studies are presented: a simulated moving bed chromatography system and a pressure swing adsorption process. © 2017 American Institute of Chemical Engineers AIChE J, 2017

中文翻译：

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周期性过程的伪瞬态优化框架：变压吸附和模拟移动床色谱

周期性系统广泛用于分离过程和反应工程中。它们专为循环稳态（CSS）设计并在其中运行。识别和优化CSS已证明在计算上具有挑战性。介绍了一种新颖的面向方程式的循环过程仿真和优化框架。提出了过程模型的两步重构，包括：（1）时域和空间域的完全离散化；（2）将离散化模型重铸为微分代数方程组，为此提供了理论上的稳定性保证。另外，在CSS约束和材料回收之间建立了数学上的结构联系，这使我们能够通过“撕裂”程序处理这些情况。这些开发成果已集成到伪瞬态设计优化框架中，并进行了两个广泛的案例研究：模拟移动床色谱系统和变压吸附过程。©2017美国化学工程师学会AIChE J，2017