萃取蒸馏分离芳烃和非芳烃的过程强化技术与科学基础

Extractive distillation is commonly applied for the separation of aromatics and non-aromatics in petrochemical industry, and the separating agent (or entrainer) is the key technology of extractive distillation. But the conventional polar organic separating agents used in industry are of the disadvantages of high ratio of solvent to feed and high volatile loss. Therefore, a new kind of mixed entrainers (organic solvent + ionic liquid (IL)) was proposed for the aromatics/non-aromatics separation by extractive distillation, making full use of the advantages of ILs in separations and requiring no additional streams and equipments based on the current extractive distillation process. The project tries to identify the influence of molecular structures of ILs, as well as their compositions in the mixed separating agents, on separation performance. We also decide to establish the predictive thermodynamic models which are suitable for the systems investigated. The CFD (Computation Fluid Dynamics) model will be established to describe the gas-liquid two phases flow on the high-efficiency BH structured packings. The structural parameters of BH structured packings can be optimized. Meanwhile, at the column scale, the rigorous equilibrium (EQ) stage model is established, in which some modeling parameters come from the CFD model as well as predictive thermodynamic model. The predicted values by this mathematical model should be compared with the experimental data, confirming its reliability. On this basis, the sensitivity analysis will be done. In this project, we expect to construct the chemical engineering foundation for the separation of aromatics and non-aromatics by extractive distillation from the scientific viewpoint. It should be mentioned that the results obtained from this project can be extended to the separation of other hydrocarbons with close-boiling point or forming azeotropes in petrochemical industry.

萃取精馏是石油化工中一种重要的芳烃和非芳烃分离技术，而选取适宜的分离剂是萃取精馏的关键。目前工业上常用的极性有机溶剂具有溶剂比大和易挥发的缺点。鉴于此，项目提出了在极性有机溶剂中添加一部分离子液体组成混合分离剂的新构思，充分发挥出离子液体绿色高效的分离特点，且不改变主要工艺路线和生产设备。针对目标体系，研究混合分离剂中离子液体的分子结构及混合物配比对分离性能的影响规律，并建立适用于该体系的预测型分子热力学模型，筛选出合适的混合分离剂。同时，建立与萃取精馏操作相匹配的BH高效填料内的气液两相流CFD数学模型，优化填料结构参数，并连同预测型热力学模型一起为全塔尺度的平衡级模型输入必要的模型参数。将数学模型的计算值与热态实验结果对比，验证数学模型的准确性，并作必要的参变性能分析，期望从科学层面构建新型萃取蒸馏强化技术分离芳烃和非芳烃的化学工程基础。研究成果也可推广到石油化工中其它烃类混合物分离。

萃取精馏是石油化工中一种重要的芳烃和非芳烃分离技术，而选取适宜的分离剂是萃取精馏的关键。目前工业上常用的极性有机溶剂具有溶剂比大和易挥发的缺点。鉴于此，项目提出了在极性有机溶剂中添加一部分离子液体组成混合分离剂的新构思，充分发挥出离子液体绿色高效的分离特点，且不改变主要工艺路线和生产设备。针对目标体系（苯/环己烷、苯/噻吩），研究了混合分离剂中离子液体的分子结构及混合物配比对分离性能的影响规律，并建立了适用于该体系的预测型分子热力学模型，筛选出合适的混合分离剂。同时，建立与萃取精馏操作相匹配的BH高效填料内的气液两相流CFD数学模型，优化填料结构参数，并连同预测型热力学模型一起为全塔尺度的平衡级模型输入必要的模型参数。将数学模型的计算值与热态实验结果对比，验证数学模型的准确性，并作必要的参变性能分析，进而得到了合适的萃取蒸馏过程设计和操作参数。研究成果也可推广到石油化工中其它烃类混合物分离。2017年10月20日项目负责人向中国石油天然气股份有限公司石油化工研究院的专家、领导汇报对接本项目的执行情况。研究结果得到了他们的认可，并明确了下一步合作研究的必要性。