费托合成水相副产物混合醇分离:馏分切割工艺设计及控制  

Separation of mixed alcohols from Fischer-Tropsch aqueous by-product: design, optimization and control of fraction cutting

作　　者：黄洋 张稼骏 李家腾 夏铭 许春建[1] HUANG Yang;ZHANG Jiajun;LI Jiateng;XIA Ming;XU Chunjian(State Key Laboratory of Chemical Engineering,Chemical Engineering Research Center,School of Chemical Engineering and Technology,Tianjin University,Tianjin 300350,China;State Key Laboratory of Coal Conversion,Institute of Coal Chemistry,Chinese Academy of Sciences,Taiyuan 030001,Shanxi,China)

机构地区：[1]天津大学化工学院,化学工程研究所,化学工程联合国家重点实验室,天津300350 [2]中国科学院山西煤炭化学研究所煤转化国家重点实验室,山西太原030001

出　　处：《化工进展》2022年第10期5200-5213,共14页Chemical Industry and Engineering Progress

摘　　要：费托合成水相副产物主要为C_(1)~C_(8)醇(甲醇、乙醇、丙醇、丁醇、戊醇、己醇、庚醇和辛醇)与水的混合物,其中水的质量分数高达95%,且C_(2)~C_(8)醇与水均形成最低共沸物。此类醇水混合物的完全分离虽具重要价值,但难度大、能耗高,一直是学界和工业界的关注热点。本研究充分利用C_(2)~C_(3)醇水混合物的均相共沸物特性和C_(4)~C_(8)醇水混合物的高度非均相共沸物特性,提出两塔-侧线分相器工艺:通过侧线精馏塔实现C_(1)~C_(3)醇水、富C_(4)~C_(8)醇水和水的精准馏分切割;富C_(4)~C_(8)醇水混合物通入分相器以打破精馏边界,其中富水相返回侧线精馏塔,富醇相进入汽提塔,得到无水C_(4)~C_(8)醇混合物。基于年度总成本(total annual cost,TAC)的稳态优化表明,与常规三塔粗分流程相比,两塔-侧线分相器工艺能够降低TAC 14.79%,节约能耗15.96%。进一步,建立了两塔-侧线分相器工艺的控制结构,动态模拟表明,结合浓度控制器与前馈比例的控制结构表现出良好的控制性能。Aqueous by-product from Fischer-Tropsch process contains C_(1)-C_(8) alcohols(methanol,ethanol,1-propanol,1-butanol,1-pentanol,1-hexanol,1-heptanol and 1-octanol)and water(>95%)in which C_(2)-C_(8) alcohols form the minimum-boiling azeotropes with water.The complete separation of alcohol-water mixture is of great importance.However,the process still remains a challenge due to difficulty in separation and huge energy consumption.Therefore,it has been a topic of interest for academia and industry.Noticeably,C_(2)-C_(3) alcohols/water form homogeneous azeotropes whilst C_(4)-C_(8) alcohols/water form highly heterogeneous azeotropes.Based on these characteristics,the two columns sidestream decanter process was designed to achieve the precise separation of C_(1)-C_(3) alcohols/water mixture,dehydrated C_(4)-C_(8) alcohols mixture and water.C_(4)-C_(8) alcohols/water mixture from the sidestream entered the decanter to break the distillation boundary.Water rich phase returned to the sidestream distillation column,while alcohols rich phase entered stripper column to obtain highly dehydrated C_(4)-C_(8) alcohols mixture.Total annual cost(TAC)targeted steady-state optimization revealed that the two columns-sidestream decanter sequence has a 14.79%reduction in TAC and a 15.96%energy saving compared with the conventional three-column sequence.Furthermore,the control structure of the two columns-sidestream decanter sequence was established.The result of dynamic simulation showed that robust control was achieved with the combination of a concentration controller and a feed-forward ratio control structure.This work provides the design schemes and useful guides for the efficient separation of mixed-alcohol from Fischer-Tropsch aqueous by-product.

关 键 词：费托合成 混合醇 分离 模拟 节能 优化 

分 类 号：TQ028.4[化学工程]