Simulation And Study Of C8 Aromatic Isomerization Radial Reactor

Isomerization of C8 aromatics is an important technology for the production of paraxylene,and the C8 aromatic isomerization reactor model plays an important guiding role for industrial production.Due to the complexity of the aromatic isomerization reaction itself and the flow in the isomerization reactor,previous studies mainly focused on the isomerization reaction itself.No one has combined the study of isomerization reaction with the internal flow of the radial reactor,which causes the failure of radial reactor model to break through the two-dimension structure.Aiming at this circumstance,the problem of gas distribution in the radial reactor was firstly studied in this work.A semi-two-dimensional ideal model was proposed based on the cold model experiment.During the cold model experiment in the radial reactor,the distribution of the internal pressure in the scallop tube and the central tube with the height and the pressure change trend were carefully analyzed.Finally,it was found that the pressure variations with height in the scallop tube and the central tube are irregular,but the value of pressure changes intermittently and regardless of the gas flow rate,all of which results in a heterogeneous gas distribution in the scallop tube and an unstable gas residence time in the catalyst bed.After analyzing a large amount of experimental data,a concept of gas flux ratio was innovatively proposed.The reactor is divided into n stages.The gas flux ratio is defined as the gas flux in each stage divided by the value of the maximum gas flux in all stages.In the establishment of a radial reactor model,the simplest one-dimensional plug flow model was first established.By analyzing the heat balance,the reaction heat of isomerization of C8 aromatics was found to be small and the overall temperature rise was small.Considering the reactor's own heat dissipation,the thermal effect of reactor can be neglected.The pressure drop in the radial reactor and the bed pressure drop are small,compared with the total pressure,which can be ignored.Finally the radial reactor model can be established through material balance.After combining with the gas flux ratio,a quasi-two-dimensional ideal model was established.