新型填料塔技术在环己烯-环己烷萃取精馏塔中的应用

采用新型填料塔技术和新的工艺流程,对原环己烯分离塔系统进行改造,改造后环己烯分离塔塔顶环己烯从6．5％下降到4．0％,环己烯回收塔塔顶环己烷从3．5％—4％下降到2．5％,环己烯纯度从95％提高到97％以上．本次改造提供了一种萃取精馏塔扩能改造的新思路——更改部分工艺,提高提馏段效率。     

连续萃取精馏分离环己烯-环己烷的模拟与优化

利用化工流程模拟软件Aspen Plus V8.6,以N, N-二甲基乙酰胺为萃取剂对环己烯-环己烷体系进行萃取精馏模拟及优化。通过灵敏度分析工具确定了环己烯萃取精馏塔的最佳工艺操作参数为:全塔采用74块理论板数,萃取剂进料位置在17块理论板,原料进料位置在第40块理论板,回流比为12.8,溶剂比为7.6,此时环己烯分离塔顶环己烯质量分数≤1.5%,萃取剂N, N-二甲基乙酰胺质量分数≤0.002 1%,塔釜环己烯回收率≥99.7%,满足工艺分离要求。对现有生产工艺进行了优化,优化后系统能耗降低了约9.6%。     

萃取精馏分离环己烷-环己烯溶剂的筛选

通过一个简单的汽液平衡装置,研究了N,N-二甲基甲酰胺、N,N-二甲基乙酰胺、N-甲基吡咯烷酮、二甲基亚砜、γ-丁内酯、N-甲酰基吗啉溶剂以及混合溶剂在萃取精馏分离环己烷-环己烯过程中的分离性能。结果发现二甲基亚砜单独作为溶剂时表现出最佳的分离性能。溶解性好的溶剂往往分离性能一般,而分离性能好的溶剂又存在溶解性差的问题。进一步通过萃取精馏实验证明了溶剂的实际分离效果由溶剂的分离性能与溶解性共同决定。结果表明:二甲基亚砜和N,N-二甲基甲酰胺混合溶剂表现最佳的实际分离效果。     

萃取精馏分离苯-环己烷-环己烯的二元混合溶剂研究

采用N,N-二甲基乙酰胺(DMAC)、N-甲基吡咯烷酮(NMP)和γ-丁内酯萃取分离苯-环己烷-环己烯近沸程物系,考察了3种单一溶剂的分离性能,数据表明DMAC性能相对更优。在此基础上,研究了以DMAC为基础溶剂,NMP和γ-丁内酯为助溶剂的二元混合溶剂对苯-环己烷-环己烯物系的分离性能,结果表明:混合溶剂提高了从环己烷-环己烯中萃取分离苯的能力,但增大了从环己烷中分离环己烯的难度。当NMP和γ-丁内酯在二元混合溶剂中的质量分数分别为10%和25%时,其分离性能优于单一溶剂,整体分离效果也达到最优。     

环己烯、1,2-环氧环己烷和2-环己烯-1-酮二元和三元系的等压汽液平衡

作者采用改进的EC-2型汽液平衡釜测定了常压下(101.33kPa)环己烯、1,2-环氧环己烷、2-环己烯-1-酮3组二元系和1组三元系的等压汽液平衡(VLE)数据。对二元的等压汽液平衡实验数据作了热力学一致性检验和Wilson方程关联,求出了相应的Wilson方程配偶参数,用求得的参数推算了相应二元及三元系的VLE数据,并将其与实验值进行了比较,结果令人满意,可以满足工程上环己烯与其氧化产物分离设计的需要。     

环己烯的环氧化研究进展

综述了以环己烯环氧化为代表的烯烃的环氧化研究进展 ,并介绍了有机过氧化物体系、分子氧体系及电化学合成等工艺的优缺点     

1-硝基环己烯的合成方法改进

环己醇在以浓硫酸和磷酸组成的混合酸催化作用下,脱水得到环己烯,且当混合酸中浓硫酸和磷酸的体积比为1∶2时,环己烯的收率最高;在乙二醇(EG)作用下,亚硝酸钠和碘在乙酸乙酯和水中硝化环己烯得到标题化合物,其结构经1HNMRI、R和元素分析表征。该一锅合成法采用碘-乙二醇/亚硝酸钠替代氯化汞/亚硝酸钠硝化环己烯制备标题化合物,不涉及用碱液对中间产物的处理,也避免了高毒性有机试剂的使用且反应为均相体系,预处理简单方便,产率较高。     

双氧水氧化环己烯反应液有机相精馏分离提纯研究

针对无溶剂法双氧水氧化环己烯合成环氧环己烷的有机相反应液,本文采用常压连续精馏的方法对其进行了分离纯化,并得到了精馏回收环己烯和环氧环己烷的较佳工艺条件。实验考察了精馏过程中影响回收环己烯和环氧环己烷纯度和回收率的各种因素,优化得到了较佳的精馏操作条件。实验结果表明,在优化精馏操作条件下,环己烯和环氧环己烷的纯度都达99%以上,收率分别为90.56%和83.41%。为双氧水氧化环己烯合成环氧环己烷工业化生产分离工艺和工程设计提供实验基础。     

离子液体作为萃取剂分离苯、环己烷和环己烯的应用前景

本文介绍了离子液体的特性,并通过国外某文献中气液相平衡数据,分析了离子液体作为萃取剂分离苯、环己烷和环己烯的可行性,并得出了采用离子液体作为萃取剂分离苯、环己烷和环己烯的优缺点。     

环己烯环氧化反应催化剂研究进展

环氧环己烷作为一种重要的中间体在有机合成中具有很高的应用价值。由环己烯环氧化制备环氧环己烷极易发生烯丙基氧化、环氧环己烷开环水解、深度氧化等副反应,因此利用价廉易得的氧化剂高选择性地生产环氧环己烷仍然是一个挑战。从氧化剂类型入手,对近期环己烯环氧化反应体系中催化剂种类进行总结,提出各种催化体系面临的主要问题。分析表明催化剂上自由基激发位点、酸性位点是造成环己烯烯丙基氧化、环氧环己烷开环水解副反应产生的主要原因,为催化剂的设计开发提供研究方向。     

Control analysis of an extractive dividing-wall column used for ethanol dehydration

This paper deals with design and control of an extractive dividing-wall distillation column (EDWC) for ethanol dehydration using ethylene glycol as entrainer. An initial design, based on a section analogy procedure for a conventional extractive distillation sequence, was obtained and then used in an optimization process to minimize the total annual cost. It was shown that the EDWC can result in significant savings over the conventional process. As these savings sometimes go along with a decrease in the control properties, an investigation of two control structures for the EDWC and one for the conventional column configuration was performed next.It was observed in closed-loop simulations that the EDWC with an appropriate structure exhibited good control properties and that its closed-loop responses were similar to those obtained for the operation of a conventional extractive distillation system.     

丁二烯萃取蒸馏新工艺

巴斯夫（BASF）的丁二烯萃取蒸馏工艺是以NMP（N-甲基吡咯烷酮）为溶剂的工艺，三种普遍用于丁二烯萃取溶剂中NMP是唯一无毒的溶剂。BASF公司投入了大量的精力改进了以NMP为溶剂的丁二烯萃取蒸馏的工艺。新工艺包括萃取蒸馏区。脱气区。蒸馏区和溶剂回收区。新工艺设备减少，投资降低10%，维护费用减少15%，装置安全性得到改善。     

隔离壁精馏塔萃取精馏制无水叔丁醇研究

用隔离壁精馏塔萃取精馏制无水叔丁醇,在溶剂比为1.5,回流比为2∶1,叔丁醇原料进料速度为1.7 mL/min时,塔顶叔丁醇的质量分数达到99.6%;塔釜乙二醇的质量分数达到97.7%,可直接作萃取剂循环利用。用AspenPlus对该工艺和二塔萃取精馏工艺对比,结果与实验相一致,塔顶叔丁醇质量分数的相对误差为0.4%,塔釜乙二醇质量分数的相对误差1.3%。结果显示,该工艺比现有工艺省了1个塔、1个再沸器和1个冷凝器,节能27%,降低了能耗和设备投资。     

缩短萃取蒸馏单元的开工时间

简述了粗苯加氢精制过程中萃取蒸馏单元的工艺流程,阐述了萃取蒸馏单元停工后开工的操作以及开工过程中出现的问题,分析了影响开工时间的因素,提出了缩短开工时间的方案和工艺,改进后可节约能耗,增加利润。     

Design of extractive distillation for the separation of close-boiling mixtures: Solvent selection and column optimization

A practical methodology for the design and optimization of extractive distillation is proposed in this work. The extractive distillation is generally applied to the separation of close-boiling mixtures, which by conventional distillation is difficult to separate. The design and optimization of extractive distillation is more complex than that of the conventional distillation when considering the selection of suitable solvent to enhance the separation. Currently, the solvent selection can be effectively handled by the assistance of the computer-aided molecular design (CAMD) approach. The selection result may however be inconclusive due to the lack of accurate or missing parameters in the property model. In this work, the experimental verification and the property parameter determination were proved to be necessary as an additional step to achieve a successful and reliable design. The overall design methodology was illustrated through an industrial separation of C8-Aromatics mixture.     

Parametric and nonparametric model based control of a packed distillation column

Parametric and nonparametric model based control systems were applied to control the overhead temperature of a packed distillation column separating methanol–water mixture. Experimental and theoretical studies have been done to observe the efficiency and performance of both control systems. Generalized predictive control (GPC) system based on a parametric model has been tried to keep the overhead temperature at the desired set point. First, a parametric model which is controlled auto regressive integrated moving average (CARIMA) was developed and then the parameters of this model were identified by applying pseudo random binary sequence (PRBS) and using Bierman algorithm. After that this model was used to design the GPC system. Tuning parameters of the GPC system have been calculated using the simulation program of the packed distillation column. Using the predicted parameters, experimental and theoretical GPC systems were found very effective in controlling the overhead temperature. Dynamic matrix control (DMC) system based on a nonparametric model has been used to track the overhead temperature of the packed distillation column. For this purpose, a nonparametric model known as the dynamic matrix was determined using the reaction curve method. A step change in heat input to the reboiler was applied to the manipulated variable and the temperature of the overhead product was observed. After that, the dynamic matrix was used to design the DMC system. Several calculations have been done to define the DMC control parameters. The best values of the tuning parameter were used to realize the DMC system for controlling the overhead temperature experimentally and theoretically. In the presence of some disturbances, the DMC system gives oscillation and offset in experimental studies.     

生物燃料乙醇分壁塔萃取精馏新工艺的研究

针对生物燃料乙醇生产中的"蒸馏-脱水"过程,建立基于分壁式萃取精馏塔的三塔工艺和两塔工艺,对2种工艺进行模拟计算,比较其分离效果和过程能耗。结果显示,在满足产品质量的前提下,三塔工艺比两塔工艺节约66.6%的冷凝器热负荷和77.9%的再沸器热负荷。对三塔工艺的分壁式萃取精馏塔的工艺条件进行优化,优化结果为,主塔回流比1.5,溶剂比1.0,原料进料位置为第22块板,隔板底端位置在第28块板,气相分配比为8.4。在优化工艺条件下对三塔工艺进行全流程模拟,可得到质量分数99.96%生物燃料乙醇和99.49%的水,回收萃取剂乙二醇质量分数为99.97%。     

A systematic synthesis framework for extractive distillation processes

An effective extractive distillation process depends on the choice of the extractive agent. In this contribution, heuristic rules for entrainer selection and the design of entrainers through computer-aided molecular design are reviewed. The potential of the generated alternatives is then evaluated by their selectivity at infinite dilution and by the rectification body method (RBM). It is shown that a screening based on selectivity alone is not sufficient and could possibly lead to an unfavorable entrainer choice. The minimum entrainer flowrate and the minimum energy demand, calculated from the RBM, allow a more comprehensive evaluation of different entrainer alternatives. In a third step a rigorous mixed-integer optimization of the entire extractive flowsheet for the remaining entrainer candidates is executed to fix the remaining design degrees of freedom and to determine the best entrainer. Since a number of alternative entrainers have already been eliminated, only a few optimizations are necessary. These steps form a framework which facilitates the systematic generation and evaluation of entrainer alternatives. The suggested synthesis framework is illustrated with a case study where acetone and methanol are to be separated.     

旋转填料床间歇萃取精馏性能研究

为了寻找强化间歇萃取精馏过程的有效途径,在装填2mm×2mm三角形螺旋填料的旋转床中,以乙醇-水为实验物系,乙二醇为萃取剂,通过考察馏出液组成随时间的变化情况,产品的纯度和回收率随转速、回流比和溶剂比的变化情况,研究了旋转填料床间歇萃取精馏的性能。结果表明,旋转填料床中强大的离心力和高效填料的协同作用极大地强化了间歇萃取精馏过程,具有分离效果好、操作时间短、节能、小设备大生产能力等突出优点;存在最佳转速使产品的纯度和回收率最大;增加溶剂比和回流比均能使产品的纯度和回收率得到提高,但增加溶剂比的效果更显著。旋转填料床是强化间歇萃取精馏过程的有效途径。     

加盐萃取精馏分离邻二甲苯-苯乙烯的研究

测定了不同萃取剂和盐对邻二甲苯-苯乙烯近沸程物系相对挥发度的影响,研究了盐质量浓度、萃取剂加入速率和回流比对加盐萃取精馏的影响,并建立了反映塔顶馏出液中邻二甲苯质量分数与各因素关系的回归模型。研究结果表明,环丁砜(DMSO)-水(质量分数3%)-硫氰酸钾(KCNS,0.03 g/mL)可作为加盐萃取精馏分离邻二甲苯和苯乙烯体系的最佳加盐萃取剂。