The Study On Separation Process Design Of Tetrahydrofuran-Ethanol-Water

As an important organic and fine chemical raw material,tetrahydrofuran has important application value in resin solvent,reaction solvent,chemical intermediates,chromatographic solvent,etc.At present,the market demand for high purity tetrahydrofuran products is increasing.The waste liquid of a plant mainly contains tetrahydrofuran,but it is accompanied by many impurities such as ethanol,water and mixed tri-toluene.In the past,waste liquid was directly sent outside the factory for treatment.In order to improve the production efficiency,the factory decided to use the waste liquid as raw material,expand a set of separation device,carry out separation and purification,and produce tetrahydrofuran products that meet the market requirements.There are two-element azeotropes in the raw liquid,such as ethanol and water,tetrahydrofuran and water,tetrahydrofuran and ethanol,and complex ternary azeotropes,such as tetrahydrofuran-ethanol-water.Therefore,if the common distillation method is used in the separation operation,it may be difficult to separate.Therefore,the separation method chosen by researchers is the special distillation method.It is clear from the research and analysis of the existing research data that few researchers study and analyze the separation of tetrahydrofuran-water-ethanol ternary azeotropic system,and most researchers are mainly devoted to the research of tetrahydrofuran-water,tetrahydrofuran-ethanol and other systems.On the basis of investigating relevant literature,this paper analyzes and references two paths,one is tetrahydrofuran-ethanol system,the other is tetrahydrofuran-water system,and based on this,the research was carried out.In this paper,using Aspen Plus process simulation tool,UNIFAC method and raw material parameters as initial parameters,two schemes of extractive distillation(scheme ?)and pressure swing distillation(scheme ?)were simulated.The theoretical plate number,feed position,molar reflux ratio and other aspects were optimized for extractive distillation: the theoretical plate number of the extraction column was 16,the feed position was the ninth column plate,and the molar reflux ratio was 1.1.By optimizing the number of theoretical stages in the pressure swing distillation,the final number of stages in the four columns is 30,20,21 and 5 respectively.Both of the results of the two schemes meet the requirements.This paper has carried out the economic analysis to two kinds of schemes.From the perspective of equipment economy,two towers are required in scheme ?,and the number of trays of the two towers is 16 and 8 respectively.In scheme ?,four distillation towers are required,with 30,20,21 and 5 plates respectively,and two high-pressure towers,which need to be made of high-pressure resistant materials.From the perspective of energy,the consumption of cold utilities and hot utilities in scheme ? is-59.3kw and 82.9kw respectively.While the consumption of cold utilities in scheme ? is-132.1kw,and the consumption of hot utilities is 137.6kw.Finally,the extractive distillation scheme is determined to be the optimal scheme,and the primary design of the main equipment is carried out,which may provide guidance for the actual plant expansion.