HIGH-PRESSURE POLYMERIZATION OF ETHYLENE - AN IMPROVED MATHEMATICAL-MODEL FOR INDUSTRIAL TUBULAR REACTORS

This work presents an exhaustive mathematical model for the high press ure polymerization of ethylene in tubular reactors of configuration si milar to that encountered in the industry. Multiple injection of monom er, mixtures of initiators and chain transfer agents are considered to gether with realistic flux configurations. Typical heat transfer coeff icients are estimated from industrial plant data, The effects of press ure pulse on the reactor behavior are also analyzed. Instantaneous tem perature profiles produced by such pressure pulse were recovered from stationary simulations showing a very good agreement with the correspo nding experimental data. The model features are demonstrated by predic tions of temperature, concentrations of reactants and products and mol ecular properties as a function of reactor length. Also, appropriate p redictive capabilities are disclosed by comparison of model simulation results and experimental data. The generation of a high temperature i nitiator, derived from oxygen, is assessed by comparison of temperatur e profiles corresponding to runs with and without oxygen.