Kaibel隔壁塔用于四组分精馏的模拟优化和实验研究

摘要

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(RL)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(RL)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.%隔壁精馏塔由于其特殊的结构可在单塔内实现多组分高纯度分离的目的.本文针对 Kaibel 隔壁精馏塔(KDWC)分离四组分混合物的节能工艺进行了模拟优化和实验研究.以甲醇、乙醇、正丙醇和正丁醇(MEPB)为例,通过热力学分析建立了稳态模拟的"四塔模型",并以塔内温度分布为依据对模型准确性进行了实验验证.提出了一种基于再沸器能耗的优化流程,以再沸器最小能耗为目标函数,对KDWC的液相分配比(RL)及整体结构进行了优化.分析了KDWC的节能原理并考察了中间组分含量对KDWC节能效果的影响.对比了KDWC与常规传统三塔序列的能耗并对二者的热力学效率进行了计算.结果表明:温度分布的模拟值与实验值趋于一致,且液相分配比(RL)是塔的重要操作参数;KDWC 结构相比于传统三塔序列节能的重要原因是有效降低了中间组分(乙醇和正丙醇)的返混程度,且随着中间组分含量的增加KDWC节能效果越来越明显;当中间组分摩尔分数为80%时,KDWC 可节能35.65%,可提高热力学效率26.11%.通过本文研究,为隔壁塔用于四组分精馏提供了基础实验数据并为其节能优化提供了理论指导.