Design and control of fraction cutting for the separation of mixed alcohols from the Fischer-Tropsch aqueous by-products  

作　　者：Renren Zhang Yang Huang Kaitian Zheng Chunjian Xu 

机构地区：[1]School of Chemical Engineering and Technology,State Key Laboratory of Chemical Engineering,Chemical Engineering Research Center,Tianjin University,Tianjin 300072,China

出　　处：《Chinese Journal of Chemical Engineering》2022年第10期143-154,共12页中国化学工程学报（英文版）

摘　　要：Since the minimum-boiling azeotropes of C2-C8 alcohols with water and high-water content(up to 95%(mass))in the Fischer-Tropsch aqueous by-products,the separation is energy-intensive and challenging.The energy-saving strategy for the complete separation of the Fischer-Tropsch aqueous by-products has received massive attention in recent decades.In this study,a stripper-sidestream decanter process is proposed by exploiting homogeneous azeotropes(C2-C3 alcohols-water)and heterogeneous azeotropes(C4-C8 alcohols-water).The introduction of the stripping column for pre-dehydration avoids the revaporization of the mixture,and energy carried by the overhead vapor is conserved instead of being removed in a condenser.The precise fraction cutting of C1-C3 alcohol-water mixture,C4-C8 alcohols,and water is realized by the sidestream distillation column.The C4-C8 alcohols rich mixture withdrawn from the sidestream flows into the decanter to break the distillation boundary,where the organic phase returns to the sidestream distillation column to obtain the dehydrated C4-C8 alcohols,and the aqueous phase enters the stripping column.Steady-state optimization based on total annual cost(TAC)minimization shows that the stripper-sidestream decanter process reduces TAC by 17.00%and saves energy by 21.27%compared with the conventional three-column distillation process.Further,a control structure of the process is established,and dynamic simulations show that the control structure combining a differential controller with a low-selector exhibits robust co ntrol.This study provides a novel design scheme and deepens the insights into the efficient separation of aqueous by-products of the Fischer-Tropsch synthesis.

关 键 词：Fischer–Tropsch synthesis Mixed alcohols AZEOTROPE SEPARATION Simulation Control 

分 类 号：TQ529.2[化学工程—煤化学工程] TQ028.31