Thermodynamic Analysis And Structural Optimization Of Reactor For Hydrogen Production By Dimethyl Ether

As we know,hydrogen is a clean energy and ideal alternative energy to fossil fuels.It has many advantages such as high energy density and without pollution of reaction products and so on.There are some problems about hydrogen that is difficult to produce,store and transport.Dimethyl ether is an ideal fuel for hydrogen production,and it has some advantages about high energy density,low cost and convenient storage.Hydrogen is produced by dimethyl ether reforming reaction and using it as hydrogen source for proton exchange membrane fuel cell.It has great significance of manufacturing of fuel cell electric vehicles and solving the problem with energy shortage.Based on the Gibbs minimum energy principle and Arrhenius equation,the thermodynamic and kinetic model of hydrogen production by dimethyl ether reforming was established.The correctness of the model was verified by comparison with the experimental data.At last,the structural parameters of reactor for hydrogen production by dimethyl ether steam reforming reaction were optimized by the kinetic model.Firstly,the thermodynamic model of steam reforming reaction of dimethyl ether was established by using Gibbs minimum free energy principle and the flow simulation software Aspen Plus.Based on the established model,the hydrogen yield rate,Molar content of components and energy efficiency of the hydrogen production reaction were investigated by adjusting different reaction parameters such as molar ratio of steam to dimethyl ether（1.0-6.0）,reaction temperature（200℃-600℃）and reaction system pressure（1atm-6atm）The conversion of dimethyl ether was positively correlated with the molar ratio of ether to ether.The increas ing of reaction temperature can promote the conversion rate of dimethyl ether,but it will make the water vapor reaction（H₂+CO₂=H₂O+CO）move towards the formation of CO if the temperature is too high,and also can reduce the selectivity of carbon dioxide.The pressure of the reaction system should not be too high,because high pressure will reduce the rate of hydrogen production and increase the energy consumption of reaction.The validity of the thermodynamic model was verified by compared the experimental data.Secondly,according to the equation of Arrhenius rate constant equation,the kinetic rate equation of dimethyl ether steam reforming reaction for was solved by data fitting method.And the kinetic model of hydrogen production system was established by using（RPLUG）module in Aspen Plus software.The results were compared with the experimental data to verify that whether the fitting of the kinetic model reached the requirement.The effects of different reaction parameters on the conversion of dimethyl ether,rate of hydrogen yield and carbon dioxide selectivity were investigated according to the kinetic model of dimethyl ether steam reforming system for hydrogen production while temperature is 250-300℃,the molar ratio of steam to dimethyl ether is 3.0-5.0.And based on controlling the conversion rate of dimethyl ether（70%）and the hydrogen content（50%）in the kinetic model,the structural parameters of the dimethyl ether reactor for hydrogen production were optimized,and the axial length of the reactor was controlled within400mm,the radial diameter was controlled at 10mm-20mm.Finally,the results of this paper can provide theoretical reference for thermodynamic trend analysis and structure optimization of reactor of hydrogen production by dimethyl ether steam reforming reaction.