萃取精馏生产高纯度环氧丙烷的工艺研究
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摘要
丙烯环氧化反应获得的粗环氧丙烷(PO)中含有乙醛、甲醇、甲酸甲酯和水等杂质,由于这些杂质与PO相对挥发度接近于1,普通精馏难以提纯PO;同时,分离过程中PO易发生水解生成1,2-丙二醇(PG),而PG又导致萃取剂萃取性能下降。据此,结合萃取精馏和液液萃取技术,同时考虑PO水解反应,开发了水洗回收PO和侧线采出共沸物脱除PG流程,在有效脱除杂质的同时,提高了PO的回收率和萃取剂的萃取效率,获得了高纯度PO产品。采用流程模拟软件Aspen Plus对上述流程进行了全流程模拟计算,借助NRTL热力学方法,分析了萃取精馏塔的溶剂比、理论塔板数、原料进料位置、溶剂进料温度等主要工艺参数对分离过程的影响。结果表明该工艺流程合理、可靠,经济性优于现有工艺,可指导工业过程设计和操作优化。
Crude propylene oxide(PO) produced from propylene epoxidation contains contaminations such as acetaldehyde, methanol, methyl formate, water and so on. It is difficult to remove them by using simple distillationbecause the relative volatilities of these components to PO are close to 1. Meanwhile, the PO is easy to react withwater and 1, 2-propanediol(PG) that will affect the extractive efficiency is then produced. Therefore, a processflowsheet combined extractive distillation and liquid-liquid extraction is proposed here to effectively remove thesecontaminations and improve PO product yield, in which the PO hydrolysis reaction(non-catalytic reactivedistillation) and the processes of water washing for PO recover and side-drawing for the removal of PG areconsidered. The whole process is then simulated by using process simulation software Aspen Plus, in which theNRTL thermodynamic model is employed to character the thermodynamic properties. The effects of major designparameters of the separation process, such as the solvent ratio, the theoretical stage number of extractive distillationcolumn, the location of feed, and the temperature of solvent, are investigated. The results show that the process is reasonable, reliable, and economical superior to existing processes, which can guide industrial process design and operation optimization.
Crude propylene oxide(PO) produced from propylene epoxidation contains contaminations such as acetaldehyde, methanol, methyl formate, water and so on. It is difficult to remove them by using simple distillationbecause the relative volatilities of these components to PO are close to 1. Meanwhile, the PO is easy to react withwater and 1, 2-propanediol(PG) that will affect the extractive efficiency is then produced. Therefore, a processflowsheet combined extractive distillation and liquid-liquid extraction is proposed here to effectively remove thesecontaminations and improve PO product yield, in which the PO hydrolysis reaction(non-catalytic reactivedistillation) and the processes of water washing for PO recover and side-drawing for the removal of PG areconsidered. The whole process is then simulated by using process simulation software Aspen Plus, in which theNRTL thermodynamic model is employed to character the thermodynamic properties. The effects of major designparameters of the separation process, such as the solvent ratio, the theoretical stage number of extractive distillationcolumn, the location of feed, and the temperature of solvent, are investigated. The results show that the process is reasonable, reliable, and economical superior to existing processes, which can guide industrial process design and operation optimization.
引文
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[12]曾琦斐.萃取精馏分离环氧丙烷与甲醇混合物的模拟与优化[J].现代化工, 2012, 32(5):114-116.Zeng Q F. Simulation and optimization of extractive distillation separation of propylene oxide and methanol[J]. Modern Chemical Industry, 2012, 32(5):114-116.
[13]辜乌根,胡松,李木金,等.萃取精馏法精制1,2-环氧丁烷的研究[J].石油化工, 2016, 45(6):834-840.Gu W G, Hu S, Li M J, et al. Purification of 1,2-butylene oxide by extractive distillation[J]. Petrochemical Technology, 2016, 45(6):834-840.
[14]胡松,杨卫胜.萃取精馏分离环氧丙烷-水-甲醇混合物的模拟[J].石油化工, 2013, 42(7):775-779.Hu S, Yang W S. Simulation of separating propylene oxide-watermethanol mixture by extractive distillation[J]. Petrochemical Technology, 2013, 42(7):775-779.
[15] Baer H, Bergamo M, Forlin A, et al. Ullmann's Encyclopedia of Industrial Chemistry:Propylene Oxide[M]. Weinheim:WileyVCH Verlag GmbH&Co. KGaA, 2012.
[16] Oku N, Nakayama T, Shinohara K. Method of purifying propylene oxide:WO2003068761A1[P]. 2003-02-07.
[17] Wickert J N, Tamplin W S, Shank R L. Phase equilibria in the system propylene oxide-water[J]. Chemical Engineering Progress,1952, 48(2):92-96.
[18] Muehlebruch M, Figurski G. The vapor-liquid equilibrium in the binary systems acetaldehyde-propylene oxide, acetaldehydemethyl formate and propylene oxide-propanol-2 at 101.325kPa[J]. Z. Phys. Chem.(Leipzig), 1989, 270(2):305-314.
[19] Hsieh C M, Sandler S I, Lin S T. Improvements of COSMO-SAC for vapor-liquid and liquid-liquid equilibrium predictions[J].Fluid Phase Equilibria, 2010, 297(1):90-97.
[2]中华人民共和国国家质量监督检验检疫总局,中国国家标准化管理委员会.工业用环氧丙烷:GB/T 14491—2015[S].北京:中国标准出版社, 2016.General Administration of Quality Supervision, Inspection and Quarantine of the People's Republic of China, Standardization Administration of the People's Republic of China. Propylene oxide for industrial use:GB/T 14491—2015[S]. Beijing:Standards Press of China, 2016.
[3] Schmidt J P. Separation of propylene oxide from other hydrocarbons:US3843488[P]. 1967-09-07.
[4] Thomas S T. Lower alkylene oxide purification:US5133839[P].1991-07-25.
[5] Meyer R A, Smith W A, Mueller M A, et al. Plural stage purification of propylene oxide:US5262017[P]. 1993-04-19.
[6] William K C III, Sheu Y H E, Pottratz D G. Staged purification of contaminated propylene oxide:US5354430[P]. 1993-10-26.
[7] Taylor M E. Plural stage drying and purification of propylene oxide:US5354431[P]. 1993-09-23.
[8] Oku N, Nakayama T, Shinohara K. Method of purifying propylene oxide:US7285187[P]. 2004-08-13.
[9] Nakayama T, Tsuji J, Oku N, et al. Method of purifying propylene oxide:US8093412[P]. 2005-06-21.
[10] Sawyer G A. Purification of propylene oxide:US20120077996[P].2010-09-28.
[11]王惠媛,许松林.常压精馏分离环氧丙烷-甲醇的工艺模拟[J].精细石油化工, 2005,(5):45-47.Wang H Y, Xu S L. Atmospheric distillation process simulation for separation of propylene oxide and methanol[J]. Speciality Petrochemicals, 2005,(5):45-47.
[12]曾琦斐.萃取精馏分离环氧丙烷与甲醇混合物的模拟与优化[J].现代化工, 2012, 32(5):114-116.Zeng Q F. Simulation and optimization of extractive distillation separation of propylene oxide and methanol[J]. Modern Chemical Industry, 2012, 32(5):114-116.
[13]辜乌根,胡松,李木金,等.萃取精馏法精制1,2-环氧丁烷的研究[J].石油化工, 2016, 45(6):834-840.Gu W G, Hu S, Li M J, et al. Purification of 1,2-butylene oxide by extractive distillation[J]. Petrochemical Technology, 2016, 45(6):834-840.
[14]胡松,杨卫胜.萃取精馏分离环氧丙烷-水-甲醇混合物的模拟[J].石油化工, 2013, 42(7):775-779.Hu S, Yang W S. Simulation of separating propylene oxide-watermethanol mixture by extractive distillation[J]. Petrochemical Technology, 2013, 42(7):775-779.
[15] Baer H, Bergamo M, Forlin A, et al. Ullmann's Encyclopedia of Industrial Chemistry:Propylene Oxide[M]. Weinheim:WileyVCH Verlag GmbH&Co. KGaA, 2012.
[16] Oku N, Nakayama T, Shinohara K. Method of purifying propylene oxide:WO2003068761A1[P]. 2003-02-07.
[17] Wickert J N, Tamplin W S, Shank R L. Phase equilibria in the system propylene oxide-water[J]. Chemical Engineering Progress,1952, 48(2):92-96.
[18] Muehlebruch M, Figurski G. The vapor-liquid equilibrium in the binary systems acetaldehyde-propylene oxide, acetaldehydemethyl formate and propylene oxide-propanol-2 at 101.325kPa[J]. Z. Phys. Chem.(Leipzig), 1989, 270(2):305-314.
[19] Hsieh C M, Sandler S I, Lin S T. Improvements of COSMO-SAC for vapor-liquid and liquid-liquid equilibrium predictions[J].Fluid Phase Equilibria, 2010, 297(1):90-97.