Comprehensive Design and Optimization for Multicomponent Distillation Systems

To develop the separation strategy and optimization for a multicomponent distillation system, especially with five and more components, a comprehensive automatic process design and optimization (APDO) model was proposed. The APDO model coupled the automatic-separation-strategy-selection (A-3S) method and the nondominated sorting genetic algorithm II (NSGA-II). The A-3S method can automatically generate separation matrices based on the specified limit of split times and construct the corresponding configuration according to the provided columns and dividing walls. Furthermore, it is capable of efficiently identifying configurations with energy-saving potential. NSGA-II optimizes the selected configurations, significantly enhancing computational efficiency. This study examined the application of the APDO model in the separation of three components containing an impurity and five components containing an impurity. The results indicated that as the purity of the trace component increases to a certain level, the energy consumption rises sharply. For the separation of three alcohols containing an impurity, the optimized column reboiler duty is 80869.7 kW with a compromise ethanol purity of 64.1 mol %. Using a single dividing-wall column to separate five alcohols containing an impurity yielded 72 possible schemes. The APDO method selected the scheme with the greatest energy-saving potential for optimization. The optimized reboiler duty was 88334.9 kW, with an upper limit of 71.0 mol % for impurity products’ purity. This work with the APDO model offers a broader selection of multicomponent separation strategies and significantly improves its applicability to industrial separation processes.