Process Simulation And Optimization Of Ethylene Glycol From Coal-Based Syngas

As an important raw material and intermediate in chemical industry,ethylene glycol(EG)has great application prospects.Especially in the polyester industry,automobile industry and so on has a wide range of applications.In recent years,with the rapid development of polyester industry and automotive industry,the market demand for EG has been growing.In the face of the energy situation of relatively rich coal resources and relatively scarce oil in China,the research and development of an economic and environmental friendly EG synthesis process has attracted much attention.However,the process route of EG production from coal-based syngas has a relatively high degree of agreement with the research hotspots.Based on this process,the process was simulated and optimized by Aspen plus chemical simulation software in order to optimize the process to produce polyester grade EG.The vapor-liquid equilibrium data of MIAK(methyl isoamyl ketone,azeotrope)+1,2-BD(1,2-butanediol)and EG+1,2-BD binary system were determined by vapor-liquid double-cycle equilibrium device.The main contents of this paper are as follows:(1)The VLE data of MIAK+1,2-BD and EG+1,2-BD binary systems were determined by vapor-liquid double-cycle equilibrium device,and the composition of VLE data was analyzed by chromatography.The experimental results show that not only azeotropic phenomena exist in MIAK+1,2-BD system,but also the content of MIAK decreases with the increase of pressure at the lowest azeotropic point.The experimental VLE data meet the thermodynamic consistency requirements.Three thermodynamic models,Wilson,NRTL and UNIQUAC,were used to correlate the VLE data by Aspen software,and the corresponding model parameters were obtained.Combined with Aspen simulation calculation,the deviation between VLE data and experimental data is small.MIAK+1,2-BD and EG+1,2-BD systems are in good agreement with the three thermodynamic models.(2)The whole process of EG production from coal-based syngas was simulated and designed by Aspen plus simulation software.The process parameters of MN regeneration,CO coupling,DMO hydrogenation and EG refining were analyzed and simulated respectively.The sensitivity of the process parameters of the related tower equipment was analyzed,and the optimum operation parameters were determined.MN is synthesized by reactive distillation technology in MN regeneration section.Methanol and water are extracted from the bottom of the column and returned to the methanol recovery column as recycling material,which reduces the energy consumption of methanol and avoids the formation of ME+DMC azeotropic system.DMO with purity of about 1 is obtained in CO coupling section,and DMC with purity of 99.96% is 52.9kt/a by-product;EG with purity of 99.92%(polyester grade)is obtained in EG refining section,with purity of 290kt/a and purity of 1.2-BD is 19kt/a.(3)The azeotropic partition distillation column(ADWC)was used to separate EG+1,2-BD system,and the single column was used instead of the conventional two-column azeotropic distillation to simulate the separation of the binary system.Compared with the conventional two-column azeotropic distillation model,the azeotropic partition distillation model ensured the same purity and yield of the target product EG,while the energy consumption was reduced by 45%.