关键词: 精馏, Kaibel隔壁塔, 模拟, 优化, 节能

Abstract: Dividing-wall column (DWC)has a special structure leading to a high purity in a single column which is designed for separating multi-mixture. The Kaibel dividing-wall column (KDWC)energy-saving process for separating four-component mixture was simulated,optimized,experimented and investigated. KDWC was used to separate a quaternary mixture feed into four high purity product streams which included methanol,ethanol,n-propanol and n-butanol (MEPB). A rigorous simulation flowsheet called "four-column model" was established through thermodynamic analysis,and the accuracy of proposed model was verified based on the column temperature distribution. An optimization process was proposed for KDWC structure and split ratio (R_L)which regarded minimum energy consumption of reboiler as the target function. The energy-saving principle of KDWC was analyzed and the influence of intermediate composition on energy-saving was investigated. The energy consumption and thermodynamic efficiency of KDWC were compared with those of conventional three-column sequence. The results showed that the simulated values of column temperature distribution were consistent with the experiment ones and the split ratio (R_L)was an important operating parameter of the column. There were some reasons to explain why the structure of KDWC was energy-saving:KDWC did quite well in reducing intermediate composition which included ethanol and n-propanol backmixing degree,and the higher mole fraction of intermediate component was,the better energy-saving KDWC had. While the mole fraction of intermediate composition was 80%,KDWC saved 35.65% of energy consumption and the thermodynamic efficiency was improved by 26.11%. This research provided the basic experimental data for separating four-component mixture as well as theoretical guidance for structure optimization.

Key words: distillation, Kaibel dividing-wall column, simulation, optimization, energy saving