Steady State Simulation of Two-Gas Phase Fluidized Bed Reactors in Series for Producing Linear Low Density Polyethylene

Farhangiyan Kashani, Ali; Abedini, Hossein; Kalaie, Mohammad Reza

doi:10.22063/jipst.2012.577

Steady State Simulation of Two-Gas Phase Fluidized Bed Reactors in Series for Producing Linear Low Density Polyethylene

Document Type : Research Paper

Authors

Ali Farhangiyan Kashani

Hossein Abedini

Mohammad Reza Kalaie

10.22063/jipst.2012.577

Abstract

A linear low density polyethylene (LLDPE) production process, including
two- fuidized bed reactors in series (FBRS) and other process equipment,
was completely simulated by Aspen Polymer Plus software. Fluidized
bed reactors were considered as continuous stirred tank reactors (CSTR consisted of polymer and gas phases). POLY-SRK and NRTL-RK equations of state were used to describe polymer and non-polymer streams, respectively. In this simulation, a kinetic model, based on a double active site heterogeneous Ziegler-Natta catalyst was used for simulation of LLDPE process consisting of two FBRS. Simulator using this model has the capability to predict a number of principal characteristics of LLDPE such as melt fow index (MFI), density, polydispersity index, numerical and weight average
molecular weights (Mn,Mw) and copolymer molar fraction (SFRAC). The results of the simulation were compared with industrial plant data and a good agreement was observed between the predicted model and plant data. The simulation results show the relative error of about 0.59% for prediction of polymer mass fow and 2.67% and 0.04% for prediction of product MFI and density, respectively.

Keywords

fluidized bed reactor

polymerization

polyethylene

Ziegler-Natta catalyst

simulation