Physical Model And Application Of Extraction Process

As an indispensable part of separation unit operation,extraction technology is widely used in the actual industry,with the advantages of safe operation,wide application range,suitable for large-scale treatment,high separation efficiency,good continuity and high economic benefits.It is found that when the existing thermodynamic model is applied to the extraction process simulation of some non-ideal systems,there will be a large error.Therefore,it is an important work to study the physical model of extraction process.Based on the actual production processes of aromatics extraction,benzene extraction and butadiene extraction,this study collected and determined a large number of phase equilibrium data related to actual production,which provided sufficient basic data for accurate simulation of extraction process.In the process of phase equilibrium data collection,a large number of vapor liquid and liquid liquid equilibrium data were collected by consulting literature,books and databases,including C4 and DMF systems,alkane and sulfolane systems.In the part of the experiment,the liquid-liquid equilibrium data of several ternary systems were determined by using the phase equilibrium kettle method and the gas chromatographic analysis method.The area test method and othmer-tobias equation were used to verify the quality of the vapor liquid and liquid liquid equilibrium data.The vapor-liquid equilibrium data of two binary systems,1-butene-n-butane and 1,3-butadiene-DMF,were obtained by area test,and the deviation D was 1.37%and 1.95%respectively.N-heptane-toluene-sulfolane,3-methylpentane-toluene-sulfolane,cyclopentane-toluene-sulfolane,1-octene-toluene-sulfolane four liquid liquid equilibrium data of ternary system were tested by Othmer-Tobias equation,after fitting data,the correlation coefficient R~2 were 0.991,0.997,0.991,0.993,and the data reliability is better.On the premise of ensuring the reliability of the data,the experimental data are correlated with the thermodynamic model NRTL and UNIQUAC to obtain the parameters of the thermodynamic model,and the obtained parameters are used to predict and calculate the equilibrium composition of the system.The results are compared with the experimental data to verify the practicability of the thermodynamic model.From the results,the relative error between the calculated value and the experimental value is basically controlled within 10%,and the data has a high degree consistency.The whole process simulation of aromatics extraction,benzene extraction and butadiene extraction was established by using the self-developed process simulation software.The parameters of NRTL and UNIQUAC model obtained by regression were applied to the corresponding simulation calculation of extraction process by selecting an appropriate thermodynamic model.It can be seen from the simulation results that the product quality can meet the requirements of industrial production,the calculation results of the tower equipment are close to the main process indexes in the actual industrial production,the maximum deviation between the tower temperature and the actual value is 1.1?,and the maximum relative error between the simulated value and the actual value of the contents of key components in each flow is 4.64%.The data show that the model parameters obtained from the phase equilibrium data regression can be applied to the simulation of extraction process and the model parameters have good applicability.The results of this study can be used to simulate the extraction process accurately and provide reliable scientific guidance for the actual production equipment.