Simulation And Optimization Of CX Process Flow For 1-Hexene Copolymerization To Produce Bimodal HDPE

Polyethylene is the largest production variety of general synthetic resins.With the continuous development of the national economy,the demand for polyethylene special materials has grown rapidly.The comonomer of high-performance polyethylene products is 1-hexene abroad,but most domestic polyethylene equipment uses 1-butene as comonomer.Almost all special polyethylene materials rely on imports,and the domestic market has a bright future.Based on a plant's CX polyethylene process production device,the bimodal HDPE brand of 1-butene copolymerization was selected as the research object.Selecting the core polymerization section and solvent recovery section of the device to study whether the original production device can meet the new production requirements after the comonomer was changed to 1-hexene and the solvent was changed to n-pentane.Using Aspen Plus to establish a four-active-site polymerization reaction kinetic model based on the reaction mechanism.The model was verified according to the conversion rate,density,and molecular weight in the actual production process.The comonomer and solvent were changed based on the model built.The heat and material balance of the polymerization reactor was calculated,and the external circulation of slurry and the heat removal process of solvent evaporation were simulated.The results showed that the original equipment of the slurry external circulation system could meet the new operating requirements.The energy consumption of the first and second reactors in the solvent evaporation system was reduced by 9.83%and 16.2%.The change of the solvent and comonomer changed the recovered components.After research,it was found that the original process was not applicable for the new solvent system.Therefore,A new process for directly entering the solvent into the recovery system in the gas phase was proposed.The new solvent recovery process saved 21.2%of energy.The results show that after the comonomer and solvent are changed,the heat removal of the polymerization kettle can still be achieved and the energy consumption is reduced.The new solvent recovery process is feasible,providing a reference for the actual industrial production in the future.