从低碳醇烃混合物中分离丁醇的实验与模拟研究

发布时间：2018-03-23 00:34

本文选题：费托合成产物　切入点：丁醇　出处：《浙江大学》2017年硕士论文　论文类型：学位论文

【摘要】：在费托合成产物中,会出现大量正构烷烃和伯醇的混合物,正构烷烃和伯醇之间存在二元共沸现象,因此很难用普通的分离方法分离,在费托合成产物低沸段,即低碳醇烃混合物中,甲醇、乙醇、丙醇可通过用水萃取的方法进行分离,但丁醇和水互溶度小,无法通过上述方法进行分离。本文以费托合成产物的低沸段,即己烷、庚烷、辛烷、壬烷、乙醇、丙醇、丁醇、戊醇八元醇烃混合物为代表,以年产2万吨丁醇为例,通过实验与模拟,对醇烃混合物的分离进行研究与优化,为工业化生产提供依据。论文首先用不同的热力学模型计算得到的丁醇-辛烷二元气液平衡数据与文献值对比,发现Wilson热力学模型的模拟值与实验值一致性较好,随后选择Wilson模型对八元醇烃混合物的精馏分段分离过程进行模拟。结果表明,精馏过程可以实现醇和醇之间的清晰分割,并在每一股出料中获得一个伯醇和两个正构烷烃组成的混合物,本文选取其中的丁醇-辛烷-壬烷混合物进行进一步的分离。论文选取乙醇水溶液作为萃取剂对丁醇-辛烷-壬烷混合物进行分离,首先通过实验获取乙醇-丁醇-辛烷-水和乙醇-丁醇-壬烷-水两组四元液液平衡数据,使用这两组四元体系的液液平衡数据回归得到NRTL热力学模型的二元交互作用参数,然后分别用回归得到的二元交互作用参数以及AspenPlus内置默认参数预测乙醇-丁醇-辛烷-壬烷-水五元体系的液液平衡数据并将计算值与五元液液平衡实验数据进行对比,结果表明,使用乙醇-丁醇-辛烷-水和乙醇-丁醇-壬烷-水两组四元液液平衡数据回归得到的NRTL二元交互作用参数预测五元液液平衡数据误差更小,表明回归得到的二元交互作用参数可以进一步用于模拟以乙醇水溶液为萃取剂将丁醇从丁醇-辛烷-壬烷中分离出来的萃取过程。研究还发现,在溶剂比为3时,随着乙醇水溶液质量分数的升高,丁醇和烷烃的分配系数随之升高,丁醇的选择性系数随之先升高后降低,并在乙醇水溶液质量分数40%左右可以达到最高值691,表明40%质量分数的乙醇水溶液是较优的萃取剂。论文提出了从丁醇-辛烷-壬烷混合物中分离出丁醇产品的工艺流程,并使用本文回归得到的二元交互作用参数对萃取塔进行了模拟计算,同时对整个流程进行了模拟与优化,得到了较优的操作参数,实现了质量流速2.74t/hr,质量分数99.83%,回收率99.45%,年产2万吨左右的丁醇分离目标。论文还使用Aspen Energy Analyzer进行了换热网络分析和优化,优化前工艺流程所需冷却量9.90MW,加热量9.74MW,优化后冷却量和加热量均节省1.01MW,总计节省能耗 10.29%。
[Abstract]:A large number of mixtures of n-alkanes and primary alcohols appear in the products of Fischer synthesis, and there is a binary azeotropic phenomenon between n-alkanes and primary alcohols, so it is difficult to separate them by ordinary separation methods. In other words, methanol, ethanol and propanol can be separated by water extraction method, but butanol and water can not be separated by these methods. Octane, nonane, ethanol, propanol, butanol, pentanol octadecanol hydrocarbon mixture as the representative, taking the annual production of 20,000 tons of butanol as an example, the separation of alcohol-hydrocarbon mixture was studied and optimized by experiment and simulation. In this paper, the binary gas-liquid equilibrium data of butanol-octane obtained by different thermodynamic models are compared with those of literature, and it is found that the simulation value of Wilson thermodynamic model is in good agreement with the experimental value. Then the Wilson model was selected to simulate the distillation separation process of octyl alcohol-hydrocarbon mixtures. The results show that the distillation process can achieve a clear separation between alcohols and alcohols. A mixture of one primary alcohol and two n-alkanes is obtained from each strand of material, In this paper, the butanol-octane-nonane mixture is selected for further separation. The butanol-octane-nonane mixture is separated by ethanol aqueous solution as the extractant. Firstly, two groups of quaternary liquid-liquid equilibrium data of ethanol-butanol-octane water and ethanol-butanol-nonane water were obtained. The binary interaction parameters of the NRTL thermodynamic model were obtained by using the liquid-liquid equilibrium data of the two groups of quaternions. Then the binary interaction parameters obtained by regression and the default parameters of AspenPlus were used to predict the liquid-liquid equilibrium data of ethanol-butanol-octane-nonane water quaternary system, and the calculated values were compared with the experimental data of five-element liquid-liquid equilibrium. The results show that the binary interaction parameters of NRTL obtained from the regression of the data of ethanol butanol-octane-water and ethanol-butanol-nonane water have smaller error in predicting the five-component liquid-liquid equilibrium data. It is shown that the binary interaction parameters obtained by regression can be further used to simulate the extraction process of butanol separated from butanol-octane nonane with ethanol aqueous solution as extractant. It is also found that when the solvent ratio is 3, The partition coefficients of butanol and alkanes increased with the increase of the mass fraction of ethanol aqueous solution, and the selectivity coefficient of butanol first increased and then decreased. The highest value of 691 can be reached when the mass fraction of ethanol aqueous solution is about 40%, which indicates that the ethanol aqueous solution with 40% mass fraction is the best extractant. In this paper, the process of separating butanol from butanol-octane nonane mixture is proposed. The binary interaction parameters obtained in this paper are used to simulate and calculate the extraction column, and the whole process is simulated and optimized, and the optimal operating parameters are obtained. The mass flow rate of 2.74 t / h, the mass fraction of 99.83, the recovery rate of 99.45 and the annual output of about 20,000 tons of butanol separation were achieved. The heat transfer network was also analyzed and optimized by Aspen Energy Analyzer. Before optimization, the cooling capacity and heat added amount needed for the process were 9.90 MW and 9.74 MW respectively. After optimization, the cooling capacity and heat addition were saved by 1.01MW, and the energy consumption was saved by 10.29 MW in total.
【学位授予单位】：浙江大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TQ223.124;TQ028.3

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