分壁精馏塔分离芳烃的稳态及动态研究

Steady state and dynamic control of divided-wall column for separating aromatics

采用分壁精馏塔(DWC)严格稳态模型,对比苯、甲苯、二甲苯以及均三甲苯四组分混合物的常规分离和分壁精馏塔分离方法,稳态分析结果表明:直接序列分壁精馏塔流程较常规三塔分离序列可减小再沸器负荷18.9%,年度总成本TAC可降低13.0%,DWC有效避免了常规塔器分离过程中中间组分的返混现象。在Aspen Dynamic环境下对最优序列进行组分控制,结果表明组分控制可很好地应对进料流量和组分组成波动。

Divided-wall column （DWC） has many advantages over conventional columns, such as energy saving potential and low investment cost. A new DWC sequence for separating benzene, toluene,o-xylene and 1,3,5-trimethylbenzene quaternary mixture was proposed and simulated in this study. Rigorous distillation column models in Aspen Plus were employed in all simulations. Under the same targets of purity and yield, the energy consumed by DWC can be reduced by 18.9% and the total annual cost can be saved by 13.0% compared to that of conventional direct separation （DS） sequence. The reason for the energy saving is that DWC could prevent the remixing of intermediate compounds, which often happens in DS sequence. Using Aspen Dynamic, composition controlled structure for DWC is proposed, which controls the new DWC separation sequence and minimizes the energy consumption in DWC. The dynamic simulation shows that the composition controlled structure provides effective control of product purity for fluctuations of feed flow rate and composition.