半连续恒全回流精馏操作法及其液相串联操作方式的研究

发布时间：2018-10-10 06:37

【摘要】：现有间歇精馏的操作方式大多存在分离效率不高、分离时间较长、能耗较大、不能同时得到纯度较高的轻组分和重组分产品等问题。本文依据常规间歇精馏的操作原理,通过储罐设置和进料方法的改进,提出了一种全新的精馏操作策略——半连续恒全回流精馏操作法。该操作法在间歇精馏塔的基础上设置了塔顶储罐和塔底储罐,整个精馏过程在恒全回流操作状态下进行,通过对两个储罐内液相的累积和倒罐完成采出和进料过程,可分别得到高浓度的轻组分产品和重组分产品,进行半连续操作。在半连续恒全回流精馏操作法的基础上结合间歇精馏塔的液相串联操作,论文又依次提出了半连续双塔液相交换操作方式和半连续双塔液相串联操作方式。在分离过程中,双塔各自进行恒全回流操作,互不干涉,仅仅通过各自储罐内的液相交换完成产品的采出和再进料,实现双塔串联操作。两种双塔操作方式有效减小了液相浓度差造成的塔内扰动,最大程度的减少了返混现象对分离过程造成的不良影响。在等浓度进料条件下半连续双塔液相交换操作的结果较好,而在低浓度和高浓度进料条件下,半连续双塔液相串联操作更具优势。随着后续研究的深入,论文结合两种双塔操作方式,去繁留简,提出了半连续多塔液相串联操作方式。该操作方式包括开车、塔顶轻组分采出-交换-进料和塔底重组分采出-交换-进料三个阶段。其中,开车阶段主要用于建立各储罐液相的浓度梯度,可采用塔顶-塔釜液相交换、串联液相交换和梯度进料三种开车方法实现。论文通过不同进料浓度下的精馏实验验证了以上各操作方法的可行性。根据全回流操作的数学模型对其进料浓度、进料量、储罐体积等各项操作参数分别进行了模拟实验研究,比较实验结果分析各操作方法的异同和优缺点,优化操作条件。实验结果表明,本文提出的新型操作方式具有以下优势:分离效果好,操作时间短,能耗低;可同时获得高纯度的轻重组分产品;处理量大;产品回收率高;一塔多用,操作弹性大;受外界影响较小;可用于热敏物料的分离任务。综上所述,论文提出的新型操作方式可满足各种分离任务的实际需求,为解决不同精馏问题提供了新的研究思路。
[Abstract]:Most of the existing operation methods of batch distillation have some problems such as low separation efficiency, long separation time, high energy consumption, and the high purity of light components and recombined fractions can not be obtained simultaneously. Based on the operation principle of conventional batch distillation and the improvement of tank setting and feed method, a new operation strategy of semi-continuous total reflux distillation is proposed in this paper. On the basis of batch distillation column, the tower top tank and bottom tank are set up. The whole distillation process is carried out under the condition of constant total reflux operation. The process of extraction and feeding is completed by the accumulation of liquid phase in the two tanks and the inversion of the tank. High concentration of light component product and recombination product can be obtained, and semi-continuous operation can be carried out. On the basis of semi-continuous constant total reflux distillation operation combined with liquid phase series operation of batch distillation column, the liquid phase exchange operation mode of semi-continuous two-column and the liquid-phase series operation mode of semi-continuous double-column were put forward in this paper. In the process of separation, the two towers are operated with constant total reflux and non-interference, only through the liquid phase exchange in their respective storage tanks to complete the extraction and refeed of the products, and realize the operation of the two towers in series. The two operation methods can effectively reduce the disturbance in the column caused by the liquid concentration difference and minimize the adverse effect of the backmixing phenomenon on the separation process. Under the condition of equal concentration of feed, the results of liquid exchange operation of semi-continuous double-tower are better, but the operation of semi-continuous double-tower liquid phase series is more advantageous under the condition of low concentration and high concentration of feed. With the development of further research, a semi-continuous multi-tower liquid-phase series operation is proposed in this paper. The operation includes three stages: starting up, extracting-exchanging-feeding of light components at the top of the tower and recombination of the bottom of the tower. The start-up stage is mainly used to establish the concentration gradient of the liquid phase of each tank, which can be realized by three starting methods: the liquid phase exchange between the tower and the tower, the series liquid phase exchange and the gradient feed. The feasibility of the above operation methods is verified by distillation experiments with different feed concentration in this paper. According to the mathematical model of total reflux operation, the operating parameters, such as feed concentration, feed volume and tank volume, were simulated and studied, respectively. The comparison of the experimental results was made to analyze the similarities and differences of each operation method and its advantages and disadvantages, and to optimize the operating conditions. The experimental results show that the new operation method proposed in this paper has the following advantages: good separation effect, short operating time, low energy consumption, high purity heavy and heavy component products can be obtained at the same time, large amount of treatment, high product recovery rate, one tower of multipurpose, The operation is flexible; less affected by the outside; can be used for the separation of heat sensitive materials. To sum up, the new operation mode proposed in this paper can meet the practical requirements of various separation tasks, and provide a new research idea for solving different distillation problems.
【学位授予单位】：天津大学
【学位级别】：博士
【学位授予年份】：2015
【分类号】：TQ028.31

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