This document provides an overview of the steps taken to implement an Aspen Polymer model of a polyethylene polymerization process. Key steps included developing the process flowsheet, defining components, selecting thermodynamic and kinetic models, inputting operating conditions, and setting up structure-property correlations. The fluidized bed reactor was modeled using a well-mixed reactor block. Component properties were obtained from databases or approximated based on similar molecules. A PCSAFT equation of state was selected to model interactions in the multi-component system operating under pressure. Typical reactions were included for the titanium-based catalyst system.

1. ASPEN POLYMER
PROJECT IMPLEMENTATION
OVERVIEW
this presentation slide is intended for internal discussion only
ASPEN Polymer Project Implementation Overview

2. MODEL DEVELOPMENT STEPS
 Process Flowsheet
 Define Component
 Polymer and catalyst characterization
 Select thermo-physical property method
 Verify pure component physical properties
 Verify phase equilibrium
 Setup polymerization kinetics
 Decide on the reaction set and enter rate constants
 Input operating conditions for unit operation model
 Enter information (T, P, flowrates/composition) for feed streams
 Setup structure-property correlations

3. MODEL FLOWSHEET OBSERVATIONS
 The fluidized bed reactor is well mixed. The
RCSTR reactor is used to represent the
fluidized bed reactor.
 The Aspen Polymers model does not include
particle size distribution.
 The cycle gas recycle loop was left open
after the compressor (location where the GC
measurements are available) to allow the
model to run faster.

4. COMPONENT OBSERVATIONS
 The components in the process have been setup in the
components form
 The physical property parameters for the standard small
molecule components are retrieved from the Aspen PURE
component
 The Catalyst and Cocatalyst (TNOA) which are present in
trace amounts are approximated to have the physical
properties of TiCl4 and TEAL
 The physical property parameters for the polymer
molecule and the corresponding segments are retrieved
from the Polymer/Segment databanks
 Segment/Polymer/Catalyst characterization information is
setup through the Polymer Characterization forms

5. THERMO-PHYSICAL PROPERTY - OBSERVATIONS
 The pressure in this process is about 20 bar and there are
supercritical components present
 The reaction mixture is made up of hydrocarbon molecules and
do not expect a high degree of interaction between the molecules
 Based on the above condition it is best to select an Equation-of-
State (EOS) model for this system
 The PCSAFT thermodynamic model has been shown to work well
for polyolefin processes and is selected as the thermodynamic
model for this process
 The PCSAFT parameters for most components were retrieved
from the POLYPCSF databank
 The PCSAFT parameters is entered for the catalyst/co-catalyst
components

6. POLYMERIZATION KINETICS - OBSERVATIONS
 Since prepolymerized catalyst is fed to the
reactor, site activation reactions have not been
included
 Catalyst CVSFRAC attribute has been set to 1
in the catalyst feed stream
 The typical reaction set for a titanium catalyst
system has been setup for the catalyst
 The hydrogenation kinetics must be tuned to
match the Ethane/Butane composition in the
cycle gas

7. TYPICAL REACTION SET FOR DIFFERENT
CATALYST
Titanium Catalyst Chromium Catalyst
Site activation by Cocatalyst Spontaneous site activation
Chain Initiation Chain Initiation
Propagation Propagation
Chain Transfer to Hydrogen
Chain Transfer to Monomer Chain Transfer to Monomer
Spontaneous chain transfer Spontaneous chain transfer
Spontaneous site deactivation Spontaneous site deactivation
Site Deactivation by Oxygen

8. OPERATING CONDITIONS FOR UNIT OPERATION
MODEL
 The different unit operation block in the flowsheet require some
operation conditions.
 Typical reactor block operating conditions
 Temperature,
 Pressure
 Total volume
 Phase volume
 Reaction sets
 Heat/Cooler Block
 Outlet temperature
 Outlet Pressure or pressure drop
 Compresssor Block
 Discharge pressure or pressure increase

9. OPERATING CONDITIONS FOR FEED STREAMS
 Typical inputs for the feed streams include
 Temperature
 Pressure
 Total flow rate and composition or component
flow rates.

10. STRUCTURE – PROPERTY CORRELATIONS FOR
GAS PHASE HDPE
 Literature
Correlations for HDPE with 1-Butene
comonomer
MI = (111525/Mw)3.472
= 0.966 – 2.386E-2 * (100*SFRAC)0.514
McAuley, K.B., J.F. MacGregor and A.E. Hamielec, AIChE J., Vol 36, No 6,
1990

11. FIT/VALIDATE STRUCTURE – PROPERTY
CORRELATIONS
 Correlation fitted to plant data
MI = A * exp(- B * MWN)
- C * Ln(MWW) + D
Need molecular structure (Mn, Mw,
copolymer composition) and product property
(MI, density) data for several grades to
develop these correlations

12. DATA COLLECTION
 The data requirements list was generated
from the base model.
 The list was reviewed and the tag names
added for the plant data
 A excel template has been setup to aid the
data collection

13. THANK YOU