Simulation And Optimization Of Nylon 66 Continuous Polymerization Process

Nylon 66 is polyhexamethylene adipamide,which is commonly produced by nylon 66 salt through a continuous polycondensation process with a long pipe reactor and a finisher reactor.Polycondensation reaction of nylon 66 is a typical reversible equilibrium reaction deeply coupled with the mass transfer process of byproduct water.In this work,the polycondensation reaction kinetics were researched through nylon 66 salt polycondensation reaction experiments with the temperature ranging from 200 ? to 260 ? and the initial water content ranging from 5 wt%to 40 wt%.A nylon 66 polycondensation reaction kinetics model considering temperature and water content factors has been established,and the kinetics parameters of the model were fitted based on the experimental data accordingly.Then,the gas-liquid equilibrium behavior of nylon 66-water system was researched,considering the influence of temperature and composition on balance pressure.The equilibrium model of nylon 66-water system was consequently set up based on PolyNRTL thermodynamics method,and the binary interaction parameters were estimated by the simulation of batch reaction process by Aspen Plus.After that,a comprehensive model had been established for the pipe reactor and the finisher reactor in the continuous polycondensation process of Nylon 66 by using the polycondensation reaction kinetics models,the gas-liquid equilibrium and the mass transfer equations.The simulation results agree well with the industrial production,indicating the accuracy of the process model.After detailed model analysis,simulation investigates the influence of various process parameters on the polymer molecular weight,finding that reducing HAc content and the finisher pressure,improving the reactor and finisher temperature can effectively increase the polymer molecular weight.The simulation results of the optimized process parameters showed improved production and polymer molecular weight.