离子液体萃取精馏分离甲醇-甲乙酮共沸物的模拟及优化

采用模拟软件Aspen Plus,以离子液体[HMIM][NTf_2]为萃取剂,对甲醇-甲乙酮共沸物的萃取精馏进行了模拟优化。确定了离子液体作为甲醇-甲乙酮萃取精馏萃取剂的可行性,分析考察了萃取精馏塔的塔板数、萃取剂流量、闪蒸罐压力等因素对年总费用TAC的影响,并对流程进行了热集成分析,结果表明,与常规萃取精馏相比,热集成流程的TAC下降了18.7%。     

基于机械蒸汽再压缩和有机朗肯循环技术的双溶剂协同萃取精馏分离乙酸甲酯-甲醇-水节能工艺

针对双溶剂协同萃取精馏分离乙酸甲酯-甲醇-水三塔分离工艺特性及高能耗特点,把机械蒸汽再压缩(MVR)和有机朗肯循环(ORC)余热发电技术应用于该三塔的优化,提出了带中间再沸器的MVR热泵和ORC耦合MVR热泵两种节能精馏工艺。以年总费用(TAC)为精馏工艺评价指标,净输出功为ORC系统评价指标,采用Aspen Plus软件对提出的节能工艺进行模拟与优化。研究结果表明,就乙酸甲酯回收塔和甲醇回收塔而言,带中间再沸器的MVR热泵精馏工艺较常规双溶剂协同萃取精馏工艺能耗分别减少了57.38%和9.66%;TAC分别节省了31.34%和11.69%。而对于溶剂回收塔,带中间预分塔的ORC耦合MVR热泵精馏工艺较常规双溶剂协同萃取精馏工艺能耗减少了50.16%,TAC节省了36.13%。就整个萃取精馏系统而言,优化后的精馏工艺比原有双溶剂协同萃取精馏工艺能耗减少了45.48%,TAC节省了31.33%。     

萃取精馏分离丙酮-四氢呋喃的研究

为了分离丙酮-四氢呋喃共沸混合物,研究了萃取精馏在丙酮-四氢呋喃物系中的应用。通过溶剂选择原理初选出乙苯作为萃取精馏分离此共沸物系的溶剂,同时采用NRTL模型对常压下丙酮-四氢呋喃物系和加入溶剂乙苯后的汽液平衡进行模拟和实验验证,模拟结果与实验数据吻合较好。然后进行了间歇萃取精馏分离此共沸物的实验研究来进一步考察所选萃取剂的效果。结果表明:乙苯能够消除丙酮-四氢呋喃共沸物系的共沸点,采用有40块理论板的填料塔,回流比为5,溶剂摩尔比为2.5∶1时塔顶可以得到质量分数为99.34%的丙酮产品,说明采用乙苯作萃取剂分离丙酮-四氢呋喃共沸物是可行的。最后又对连续和间歇萃取精馏分离丙酮-四氢呋喃共沸物的流程进行了模拟,得到的工艺参数将为进一步的工业应用提供了理论依据。     

变压精馏分离乙酸甲酯和甲醇共沸物

乙酸甲酯和甲醇共沸物对压力变化敏感,因此采用变压精馏工艺对共沸物进行高效分离。低压塔和高压塔压力分别设置为101.325 kPa和810.600 kPa。基于相图分析,确定了精馏序列和工艺流程。以年度总费用(TAC)最小为原则,优化了进料位置、回流比、塔板数等设计变量,确定了最佳工艺参数。工艺优化完成后,通过调节双塔的回流比,对高压塔的冷凝器和低压塔的再沸器进行了完全热集成。由结果可知:在低压塔回流比为0.9,高压塔回流比为2.07时,完全热集成变压精馏工艺的TAC最小。相比无热集成的变压精馏工艺,完全热集成工艺的设备投资和能耗费用均明显降低,最终TAC费用节约31.40%,在经济上更合理,也为类似的共沸物分离工艺提供了一定的技术参考。     

1,4-丁二醇分离乙酸甲酯-甲醇二元恒沸物的研究

利用1,4-丁二醇与乙酸甲酯-甲醇二元恒沸物形成三元恒沸物,研究了乙酸甲酯与甲醇恒沸物的分离工艺。实验采用精馏、常压蒸馏、减压蒸馏及冷冻的方法,主要研究了各种方法对甲醇分离的影响,并获得了较佳的工艺条件。研究得出常压蒸馏法可行,乙酸甲酯纯度达到99.7%,收率98.1%,甲醇纯度96.1%,收率95.2%。     

[Emim]AC萃取精馏分离乙酸甲酯和甲醇工艺模拟

以离子液体1-乙基-3-甲基咪唑醋酸盐([Emim]AC)为萃取剂,萃取精馏分离乙酸甲酯和甲醇共沸体系。采用Aspen Plus流程模拟软件,对萃取精馏工艺进行了模拟和优化。考察了溶剂比、全塔理论塔板数、原料进料位置、萃取剂进料位置和回流比等工艺参数对分离效果的影响。萃取精馏塔的最佳工艺参数为:全塔理论板数30,原料和萃取剂进料位置分别为第23块和第2块理论板,回流比为1.0,溶剂比为0.7。闪蒸罐操作温度和压力分别为85℃和20 kPa。在最优工艺条件下,产品乙酸甲酯的质量分数达到99.95%,甲醇的质量分数达到99.54%,均满足分离要求。说明采用离子液体[Emim]AC作为萃取剂分离乙酸甲酯和甲醇共沸物具有工业应用前景。     

萃取精馏分离甲醇-四氢呋喃共沸体系的流程模拟

应用化工过程模拟软件Aspen Plus V7.3对甲醇-四氢呋喃最低共沸物系的连续萃取精馏过程进行了模拟与优化。通过Aspen物性分析,筛选出合适的萃取剂为二甲基亚砜。确定了双塔连续萃取精馏的工艺流程,并利用灵敏度分析工具考察了萃取精馏塔的理论塔数、原料进料位置、萃取剂进料位置、回流比、溶剂比(萃取剂对原料的物质的量比)对分离效果的影响。确定的最佳工艺方案为:全塔理论板数为32,原料和萃取剂分别在第26块和第4块理论板进料,回流比为3,溶剂比为1.9。在此工艺条件下:萃取精馏塔塔顶四氢呋喃的分离效果达99.98%,萃取剂回收塔塔顶甲醇的纯度达到99.96%;萃取剂二甲基亚砜的循环补充量为8.58 mol/h。模拟与优化结果为甲醇-四氢呋喃共沸物连续萃取精馏分离过程的设计和操作提供了参考。     

DMC-甲醇-水三元混合物的萃取精馏分离工艺

运用Aspen Plus软件回归文献数据校正了碳酸二甲酯（DMC）-水（H₂O）混合物的UNIQUAC热力学模型参数,并以该模型为基础分析了水作为萃取剂萃取精馏分离DMC-甲醇（CH₃OH）-水三元混合物的分离原理,结合混合组分的三角相图和物料组成设计了反向萃取精馏工艺,发现选用水为萃取剂可以利用DMC-水的部分互溶特性,通过三塔精馏即可分离DMC-甲醇-水三元混合物,沸点较高的DMC和少量水由塔顶馏出,而沸点较低的甲醇和大部分水由塔底采出,避免了DMC-甲醇二元共沸物的形成。同时,在相同分离要求下设计了变压精馏工艺,通过对两个精馏工艺参数模拟优化,发现萃取精馏工艺的总冷凝负荷和总加热负荷分别为888.7kW和898.2kW,其总能耗较变压精馏工艺节约了47.2%,萃取精馏工艺的年总费用（TAC）比变压精馏工艺下降了48.8%。     

变压精馏和萃取精馏分离四氢呋喃-水模拟及节能

基于四氢呋喃/水共沸体系的特性,研究了变压精馏和萃取精馏2种工艺分离四氢呋喃和水的方法,进一步考察了2种工艺的可行性及节能情况。物性计算方法采用NRTL活度系数方程,其二元相互作用参数通过汽液相平衡实验数据回归获得,采用Aspen Plus对上述2种工艺进行模拟及优化,获得了2种工艺较优的工艺参数,并对比能耗。结果表明:采用双塔热集成变压精馏工艺或双塔萃取精馏工艺均可有效地分离四氢呋喃-水二元共沸体系,四氢呋喃产品符合《GB/T 24772—2009工业用四氢呋喃》优等品规格,但热集成变压精馏工艺更为节能,节省循环水11. 0%、节省蒸汽20. 3%,且不引入第三组分,更适合四氢呋喃-水体系的分离,为该共沸体系分离的设计与节能提供依据。     

乙酸甲酯-甲醇-水的热集成萃取精馏工艺

首先在50 kPa下用水萃取精馏分离乙酸甲酯、甲醇和水的混合物,得到了高质量分数的乙酸甲酯,之后利用普通精馏分离甲醇和水。使用热集成技术改造该工艺流程,将甲醇单塔精馏改造为并流双效精馏,两塔压力分别为101.325、500.000k Pa。同时采用高温水对萃取精馏塔两股进料预热,以降低萃取精馏塔塔釜的能耗。在操作参数单因素灵敏度分析的基础上,以系统塔釜总能耗及乙酸甲酯质量分数为目标函数,采用响应面方法优化操作参数。结果表明,热集成工艺较之前工艺节能23.43%。     

Simulated annealing-based optimal design of energy efficient ternary extractive dividing wall distillation process for separating benzene-isopropanol-water mixtures

This article investigates the performances of different extractive distillation processes intensified with dividing-wall column for separating benzene-isopropanol-water ternary mixtures. All the processes with ethylene glycol as solvent are optimized with the minimal total annual cost (TAC) as target. In order to get the global optimal solution intelligently, an improved simulated annealing algorithm is adopted, which is programmed in MATLAB and linked to Aspen Plus. The results show that the extractive dividing wall column-solvent (EDWC-S) process consisting of an extractive dividing wall column and a solvent recovery column is the best scheme. It can reduce the TAC by 28.65％and CO2 emissions by 32.84％com-pared to the conventional triple-column extractive distillation process.     

Optimal design of extractive distillation columns—A systematic procedure using a process simulator

The separation of binary mixtures which form azeotropes is not possible through conventional distillation and they are usually separated by extractive or azeotropic distillation. The optimization of extractive distillation columns is usually performed using a process simulator; however, normally, the result is only obtained after several simulations and the simultaneous analysis of several graphs. This paper sets out to present a systematic procedure, using a process simulator (Aspen Plus^®), in order to obtain the optimum condition for extractive distillation columns. The optimization achieved is characterized by the fact that it is not necessary to perform various simulations, and it also avoids the simultaneous analysis of dozens of curves. The dehydration of aqueous mixtures of ethanol using ethylene glycol as solvent was the system chosen as a case study.     

Effect of thermodynamic parameters on prediction of phase behavior and process design of extractive distillation

Extractive distillation was investigated for separation of the minimum azeotrope of n-propanol/water,via the Aspen Plus simulation platform.Experimental data of n-propanol/water,which could pass the thermodynamic consistency test,were regressed to get suitable binary interaction parameters (BIPs) by the UNIQUAC thermodynamic model.The azeotrope system was heterogeneous in the simulation with built-in BIPs,which was contrary to the experimental data.The study focused on the effect of thermodynamic parameters on the prediction of phase behavior,and process design of extractive distillation.N-methyl-2-pyrrolidone (NMP) and ethylene glycol were used as solvents to implement the separation.Processes with built-in and regressed BIPs were explored,based on the minimum total annual cost (TAC).There were significant differences in the phase behavior simulation using different thermodynamic parameters,which showed the importance of BIPs in the design and optimization of extractive distillation.     

外部热耦合技术在BTX分离中的应用

外部热耦合式复合精馏塔将热量从高压塔的精馏段传向低压塔的提馏段,降低了分离操作的不可逆性,从而提高系统的热力学效率,降低系统所需的能耗。目前国内苯/甲苯/二甲苯（BTX）的分离技术仍然与国外先进水平相差很远,主要表现在系统的能耗高、工艺落后等方面。本文将外部热耦合技术应用到苯/甲苯/二甲苯的分离过程中,并用M athem atica软件对系统的设备投资和操作费用进行了仿真计算。结果表明,使用外部热耦合结构,系统节能幅度可达到37.94%,年度总费用降低达18.84%。     

Economic evaluation of energy saving alternatives in extractive distillation process

Until now, there has not been consensus about the superiority of thermally coupled sequence over the conventional sequence in the extractive distillation process. In this sense, the main goal of this paper is to analyze three approaches for saving energy in the extractive distillation process: optimization, thermal integration and thermal coupling. Three azeotropic mixtures were investigated: ethanol and water (M1); tetrahydrofuran and water (M2); and acetone and methanol (M3). The solvents were ethylene glycol for M1 and M2, and water for M3. The results are shown in terms of the total annual cost (TAC) and specific energy consumption (SEC), and revealed that a thermally coupled extractive distillation sequence with a side rectifier did not always present the best results. Taking the case studies from literature as a starting point (without thermal integration), the optimization procedure used in this work found that TACs are always lower. The inclusion of thermal integration in configurations led to reducing TAC for all mixtures under investigation when compared to the sequences without this integration. When comparing two modifications in the layout of extractive distillation, it can be seen that it is more advantageous to use the preheating of the azeotropic feed with the recycle stream from the recovery column of the conventional sequence than using a thermally coupled sequence.     

酯交换法制备碳酸二甲酯过程模拟与系统火用分析

针对酯交换制备过程中甲醇?碳酸二甲酯共沸体系难分离的问题,分别选择变压精馏、碳酸乙烯酯(EC)萃取精馏与乙二醇(EG)萃取精馏3种分离过程进行模拟与能量集成,对比了3种工艺流程的分离能耗,采用有效能(?)分析方法分析了能耗最低的变压分离过程的有效能(?)损失. 结果表明,3种工艺流程的能耗EG萃取精馏>EC萃取精馏>变压精馏,碳酸二甲酯生产过程中内部循环物流能量是输入总能量的1.55倍,变压共沸分离过程的?损失为7.9%。     

萃取精馏分离苯/环己烷共沸体系模拟与优化

以糠醛作为萃取剂分别使用常规萃取精馏、隔壁塔萃取精馏和差压热集成萃取精馏对苯和环己烷体系进行分离研究,使用流程模拟软件Aspen Plus V8.4进行模拟分析,对初步设计的三稳态流程,分别进行灵敏度分析,使用多目标遗传算法对过程进行整体优化以获得最优结构参数。结果表明,隔壁塔萃取精馏和差压热集成萃取精馏相对于常规萃取精馏所需再沸器热负荷可分别减小21.5%和15.7%。对三工艺流程进行经济性分析,发现与常规流程相比,隔壁塔萃取精馏的年总费用下降了6.0%,而差压热集成萃取精馏年总费用增加了50.8%,为萃取精馏分离苯/环己烷共沸体系工业化设计提供了理论依据和设计参考。     

Energy Evaluation of Ethanol Dehydration with Glycol Mixture as Entrainer

Extractive distillation of ethanol dehydration using glycols as entrainers is proposed. Specifically, ethanol dehydration of an azeotropic mixture in the presence of ethylene glycol + glycerol mixture is evaluated. Simulation is performed and the vapor‐liquid equilibrium of ethanol + water + ethylene glycol + glycerol is predicted with the NRTL model. Minimization of energy consumption in both extractive and regeneration columns is attempted. Optimal operating parameters of the process including glycol concentration in the solvent mixture, main feed, and entrainer feed trays, total number of theoretical trays, and heat supplied to the reboiler are determined in order to achieve a specified distillate purity of 99.9 mol % ethanol.     

萃取精馏及进展

萃取精馏是一种特殊精馏方法 ,适用于近沸点物系和共沸物的分离。萃取精馏按操作方式可分为连续萃取精馏和间歇萃取精馏 ,间歇萃取精馏是近年发展起来的新的萃取精馏方法。萃取精馏的关键是溶剂的选择 ,以往萃取精馏采用的溶剂是单一溶剂 ,近年来人们开始研究使用混合溶剂 ,取得了良好效果