Nonlinear Wave Modeling of Internally Heat-Integrated Air Separation Columns via Local Mechanism-Based Optimization

Compared with conventional air separation columns, the internally heat-integrated air separation column (HIASC) offers superior energy efficiency. However, its structural complexity poses significant challenges for model-based online optimization and control. This study proposes a nonlinear wave model based on a model updating strategy, which substantially reduces modeling complexity. First, wave propagation theory is employed to characterize the concentration distribution profiles and their propagation velocities within the HIASC. Subsequently, a localized analytical method based on the distributed wave velocity is developed from local mechanistic insights to evaluate waveform distortion. Furthermore, a model updating strategy is introduced, which determines the optimal updating frequency according to the degree of waveform deformation, thereby mitigating computational redundancy caused by excessive updates. Finally, the proposed strategy is integrated into the nonlinear wave model to achieve an optimal balance between accuracy and computational efficiency. Simulation results validate the effectiveness and robustness of the proposed modeling approach.