乙醇—甲乙酮体系离子液体萃取精馏实验及计算机模拟优化

发布时间：2018-04-02 11:19

本文选题：乙醇-甲乙酮　切入点：离子液体　出处：《北京化工大学》2015年硕士论文

【摘要】：乙醇和甲乙酮是两种工业常用有机物,二者之间在常压下可以形成共沸,因而二者混合后不能用普通精馏方法进行分离。离子液体以其熔点低、饱和蒸汽压几乎为零、遇热不易分解、毒性和腐蚀性极低而被视为新型“绿色溶剂”,在萃取精馏领域有极大应用前景。离子液体作为萃取剂的萃取精馏研究能够为工业上的萃取剂选择、分离操作优化、节能环保等方面提供有效指导。本文遴选两种离子液体：1,3-二甲基咪唑二甲酯磷酸盐([MMIM]DMP)和1-辛基-3-甲基咪唑四氟硼酸盐([OMIM]BF4)分别作为分离乙醇-甲乙酮体系待选萃取剂进行萃取精馏研究。1.实验在常压(101.3kPa)下使用改进的Othmer汽液平衡釜测定了乙醇-甲乙酮二元体系及分别加入不同浓度离子液体([MMIM]DMP、 [OMIM]BF4)的三元体系等压汽液平衡数据T,x,y。实验结果显示：离子液体作用于乙醇-甲乙酮共沸体系能够造成汽液平衡曲线相对于原二元体系曲线的偏离,且偏离程度随离子液体浓度的提高而增大。离子液体可以改变组分之间的相对挥发度,在足够浓度下打破共沸。对比两种离子液体的实验结果可以发现：[MMIM]DMP的分离能力强于[OMIM]BF4。2.本文利用NRTL和eNRTL方程对实验测得的汽液平衡数据进行热力学模型研究。其中,NRTL模型关联两种含离子液体([MMIM]DMP、[OMIM]BF4)体系的活度系数平均相对偏差分别为1.94%和2.59%。eNRTL模型关联两种含离子液体([MMIM]DMP、 [OMIM]BF4)体系的活度系数平均相对偏差分别为3.08%和4.55%。NRTL模型对于该体系的准确性更高。3.进行乙醇-甲乙酮-[MMIM]DMP体系的萃取精馏实验,得到塔顶产品组成随时间变化曲线及在不同回流比R、萃取剂进料速率等操作条件下的塔顶产品组成。实验结果表明：回流比R等于3,萃取剂[MMIM]DMP在常温下进料、进料速率为8mL·min-1,塔顶甲乙酮的质量分数可以达到99.0%。4.将乙醇-甲乙酮-[MMIM]DMP的NRTL方程参数输入到Aspen Plus软件中,进行以萃取精馏模拟优化。利用灵敏度分析考察塔顶产品组成在如不同回流比R、萃取剂进料位置等操作条件下的所受影响,并对温度及汽液相组成的分布等塔内情况进行分析。模拟结果和实验接近,数据可作为日后工业化生产的参考依据。
[Abstract]:Ethanol and methyl ethyl ketone are two commonly used organic compounds in industry. The azeotrope can be formed between them at normal pressure, so they can not be separated by ordinary distillation after mixing. The ionic liquids have low melting point and almost zero saturated vapor pressure. It is regarded as a new kind of "green solvent" because of its low toxicity and low corrosion, and it has great application prospect in the field of extractive distillation. The study of extractive distillation with ionic liquid as extractant can be used as a choice of extractant in industry. Separation operation optimization, In this paper, two kinds of ionic liquids: 1: 1, 3-dimethyl imidazole dimethyl ester phosphate ([MMIM] DMP) and 1-octyl-3-methyl imidazolium tetrafluoroborate salt ([OMIM] BF4) are selected for separation of ethanol-methyl ethyl ketone system. The solvent was used to extract distillation. 1. The binary system of ethanol-methyl ethyl ketone and the ternary system with different concentrations of ionic liquids ([MMIM] DMP, [OMIM] BF4) were determined by using an improved Othmer vapor-liquid equilibrium kettle under atmospheric pressure of 101.3kPa. the isobaric vapor-liquid equilibrium data were measured. The experimental results show that ionic liquid acting on ethanol-methyl ethyl ketone azeotropic system can cause the deviation of vapor-liquid equilibrium curve from that of the original binary system. The degree of deviation increases with the increase of ionic liquid concentration. Ionic liquids can change the relative volatilization between components. It is found that the separation ability of [MMIM] DMP is stronger than that of [OMIM] BF4.2. In this paper, the thermodynamic model of Vapor-Liquid equilibrium data measured in the experiment is studied by using NRTL and eNRTL equations. The average relative deviation of activity coefficients of two ionic liquids ([MMIM] DMP, [OMIM] BF4) system is 1.94% and that of 2.59%.eNRTL model is 3.08% for two ionic liquids ([MMIM] DMPand [OMIM] BF4) respectively. The extraction distillation experiments of ethanol-methyl ethanone-[ MMIM] DMP system were carried out. The curve of the top product composition with time was obtained, and the top product composition of the tower was obtained under the operating conditions of different reflux ratio R and the feed rate of the extractant. The experimental results showed that the reflux ratio R was equal to 3, and the extraction agent [MMIM] DMP was fed at room temperature. The feed rate is 8mL min-1, and the mass fraction of methyl ethanone can reach 99.0.4.The parameters of NRTL equation of ethanol-methylacetone-[ MMIM] DMP are input into Aspen Plus software. By using sensitivity analysis, the influence of the top product composition on the operation conditions such as the different reflux ratio, the feed position of the extractant, and so on, was investigated by means of the simulation optimization of extractive distillation, and the sensitivity analysis was used to investigate the influence of the product composition. The simulation results are close to the experimental results, and the data can be used as a reference for industrial production in the future.
【学位授予单位】：北京化工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TQ028.3

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