【作者】 冯惠生；

【导师】 余国琮；

【作者基本信息】 天津大学 ， 化学工程， 2010， 博士

【摘要】 本文回顾了间歇萃取精馏分离技术和进展,并从萃取精馏的萃取溶剂(简称溶剂,下同)选择、萃取精馏塔设计和操作参数以及设备结构对分离过程的影响,间歇精馏过程模拟,变压精馏技术等几个方面指出了间歇萃取精馏分离过程还存在的不足和需要改进的问题。萃取溶剂的选择是萃取精馏技术的关键。利用气液平衡实验装置,对萃取精馏分离苯-环己烷,正己烷-乙酸乙酯以及乙醇-乙酸乙酯等近沸点体系的溶剂选择进行了系统的实验研究,研究结果表明:二元混合溶剂和三元混合溶剂的分离性能均优于单一溶剂;三元混合溶剂在一定组成范围内的分离效果也超出了二元混合溶剂;二元和三元混合溶剂能够很好地解决单一溶剂选择性和溶解性相矛盾的问题,提高了溶剂的综合性能,致使溶剂的选择范围进一步扩大。综合考虑分子之间静电力、诱导力、色散力、氢键及缔合的作用,对MDUNIFAC模型进行修正,并对上述三个体系的实验数据进行了关联,建立了修正UNIFAC模型预测法,从而为萃取溶剂的选择提供了较为准确可靠的数学模型,研究结果表明,修正MDUNIFAC模型和实验法相结合是一种快速有效的萃取精馏溶剂选择方法。建立了用于近沸点或共沸物物系分离的减压间歇萃取精馏过程的恒摩尔持液模型,运用两点隐含法求解了描述该过程的一组刚性较强的方程组,并通过实验对所建模型进行了验证,模拟计算结果与实验结果吻合较好。利用所建立的数学模型,探讨了回流比、理论塔板数、操作压力以及溶剂加入速率等操作参数对分离过程的影响。结果表明,随着操作回流比、溶剂加入速率和单板液体持液量的增加或随着操作压力的下降,塔顶产品摩尔含量逐渐提高。还建立了一用于间歇精馏过程最小过渡馏分量问题讨论的数学模型,运用四阶龙格库塔法对该模型进行了求解。更多还原

【Abstract】 In this paper, the progress of batch extractive distillation were summaried. Selection and design of extractive solvents(named solvent,the same as follow), different configuration for extractive distillation column, operation policies and effect of operating parameters on separation were presented.Then the advance in the simulation of batch extractive distillation and batch extractive distillation were also described. The current disadvantages and the problems to be solved for the batch extractive distillation were pointed out.The selection of extractive solvent is the key problem for extractive distillation. A number of extractive solvents for separation of benzene-cyclohexane, n-hexane - ethyl acetate and ethyl acetate-ethanol were examined respectively in a VLE experiment apparatus. The integrated properties of sing solvent and mixed solvent were investigated , The expermental results showed that the binary mixed solvents and the ternary mixed solvents are better than the single solvent,and they are have a good solution to the contradictory problem of selectivity and solubility of the single solvent, so that the choice of the extractive would increased .Considering molecular electrostatic force, the inductive capacity, the dispersion force, the hydrogen bond and the association, the experimental data were correlated with the modified MDUNIFAC model. It was found that the prediction by modified MDUNIFAC model conformed by experiments is a rapid, accurate approach for selection for extractive distillation.Vacuum batch extractive distillation process for separating close boiling and azeotropic mixtures was simulated, the mathematical model is a group of stiff equations and resolved by two point implicit method.The experimental results agree well with the simulation.The effect of operating parameters such as reflux ratio , theoretical plates, operation pressure and solvent feed rate on the separation process were analogged by the constant molar holdup model. All these features were illustrated by the increase of the reflux ratio and flow rate of the solvents or decreasing of operation pressure, and resulting the increase of the concentration of product at the top of the column. A model for discussing minimum amount of intermediate cut was set up and solved with the four order Runge Kuta method.更多还原