Flowsheet Simulation For Bulk Propylene Polymerization Based On Polymers Plus

To develop a flowsheet simulation for industrial polymerization process,which can reflect the polymerization mechanism in essence and combine the unit operation closely,is not only helpful to master the inherence of the polymerization process,but also an important access to improve the plant's performance and profit.The Hypol technology of polypropylene process was taken as background flowsheet,whose components and operational conditions are carefully studied, indicating the use of PC-SAFT equation of state as the primary thermodynamic and physical model;then,taking the computational characteristic of Polymers Plus into consideration,the target process has been simplified and modularized using fundamental chemical engineering principles.Herein,the polymerization reactors are the heart to the Hypol technology,and through the conservation analysis of mass and energy,the detection of non-equilibrium behavior for the liquid-phase reactor leads to a novel reactor model,wherein the vapor-liquid equilibrium behavior was separated from polymerization behavior creatively.According to the mechanism of propylene polymerization,the traditional Ziegler-Natta polymerization system was incorporated from single-site to multi-site model by fitting the actual data sourced from open reports and certain plant data in the light of the GPC(Ge1 Permeation Chromatography) deconvolution of polypropylene sample.Hereby,the steady-state flowsheet model was exported from Polymer Plus into Aspen Dynamics,and by adding the complementary dynamic configurations and control scheme modules;the dynamic flowsheet simulation was finally set up.The flowsheet model was fully verified and applied to analyze plant performance. The results showed that the model had a good agreement with the plant data, demonstrating the prediction capabilities of capacity enlargement,operational optimization et al.Several cases have been studied to explore the use of this flowsheet model steadily and dynamically,including the polymer grade transition.