aspen hysys

1. JoPC (2018) 1-4 © STM Journals 2018. All Rights Reserved Page 1
Journal of Polymer & Composites
ISSN: 2321-2810 (Online), ISSN: 2321-8525 (Print)
Volume 6, Issue 3
www.stmjournals.com
Aspen HYSYS Simulation of Suspension (Slurry) Process
for the Production of Polyethylene
K. Nagamalleswara Rao1,
*, Aslam Abdullah2
1
Centre for Disaster Mitigation and Management, Vellore Institute of technology, Vellore,
Tamil Nadu, India
2
School of Chemical Engineering, Vellore Institute of technology, Vellore, Tamil Nadu, India
Abstract
This study deals with the steady state simulation of polyethylene plant using Aspen HYSYS
V10 simulation model. Looped reactor model is used to mimic the behaviour of the suspension
(slurry) polymerization process. Effect of various operating conditions like the inflow rate of
the monomer ethylene on solvent, catalyst, co-monomer and hydrogen flow rate are studied.
Model predicted that the change in monomer flow rate linearly affected the process variables.
Keywords: Catalyst, co-catalyst, co-monomer, monomer, polyethylene, solvent
*Author for Correspondence E-mail: aspenmodels@gmail.com
INTRODUCTION
In the market polyethylene is available as high
density polyethylene (HDPE), low density
polyethylene (LDPE) and linear low density
polyethylene (LLDPE). Wires, plumbing and
automotive industries are the major end users
of the polyethylene. The worldwide growth of
the infrastructure sector, low manufacturing
costs of the polyethylene and a variety of
applications of the polyethylene in the various
sectors shows a positive outlook for the
growth of the polyethylene market. This
continuous demand for polyethylene predicts
that the demand for the production of
polyethylene will reach 215 billion US dollars
by 2024 [1]. Various production processes of
polyethylene are: high pressure autoclave
process, suspension (slurry) process, gas phase
process and the solution process. In the
suspension process autoclave process, loop
reactor processes are the subcategories [2].
Environmental constraints are restraining the
growth of the polyethylene market.
Environmental regulations can be satisfied by
improving the performance of the existing
production processes. This task can be fulfilled
by using the simulation models using the
chemical process simulators. The steady state
and dynamic model for slurry high density
polyethylene [3], application of hybrid
approach to modelling [4], model for industrial
slurry reactors in series [5], model for high
pressure tubular reactor used for the
production of low density polyethylene [6] and
the fluidized bed reactor model [7] are the
some of the examples improved the
performance of the existing process models.
These models motivated the present research
of the effect of various operating variables on
the production of polyethylene.
PROCESS STUDIED
This process contains two sections. The first
section is the reactor section and the second
section is the monomer recovery section.
Reactor section contains the slurry loop
reactor. To mimic the behaviour of the slurry
reactor Aspen HYSYS V10 balance unit
operation is used. The input streams for the
reactor section are solvent, co-monomer,
monomer, co-catalyst and the catalyst
(Ziegler-Natta catalyst). Iso-Butane is used as
the solvent, 1-hexene is used as the co-
monomer, ethylene is used as the monomer,
Triealuminium is used as the co-catalyst and
for the catalyst hyprogroup is generated in the
Aspen HYSYS properties environment. Peng-
Robinson fluid package is used for the
estimation of the properties of the components
of the system. Process flow sheet for the
suspension polymerization is shown in
Figure 1.

2. Aspen HYSYS Simulation of Suspension (Slurry) Process Rao and Abdullah
JoPC (2018) 1-4 © STM Journals 2018. All Rights Reserved Page 2
Fig. 1: Aspen HYSYS Process Flow Diagram for Polyethylene Production Using the Suspension
Polymerization Technique.
Fig. 2: Effect of Monomer Flow Rate on Solvent and Co-monomer.
The slurry loop reactor (loop reactor)
conditions are: temperature 37°C, pressure 45
bar. The diluent used is isobutene. Isobutene
facilitates the flash separation, and it is the
used as the poor solvent for the polyethylene.
The chromium oxide catalyst enters in to the
reactor along with the diluent from the catalyst
slurry tank. The polymer is collected from the
flash tank. The isobutene vapours from the
flash tank are condensed and recycled.
Nitrogen gas is used to purge the residual
isobutene. Residual isobutene is represented by
stream 13. Polymer polyethylene is collected
from the bottom of the stripper (X-100).
PHASE EQUILIBRIUM
Component properties and the phase
equilibrium studies are performed using the
Peng-Robinson equation of state. Binary
interaction parameters are used to calculate the
phase equilibrium between the conventional
species and the polymer segments.
RESULTS AND DISCUSSION
Effect of monomer ethylene mass flow rate on
solvent iso-butane, catalyst, co-monomer
triealuminium and hydrogen flow rate are
studied. Effect of monomer (ethylene) inflow
rate on solvent flow rate and on co-monomer
(1-hexene) flow rate are shown in Figure 2.

3. Journal of Polymer & Composites
Volume 6, Issue 3
ISSN: 2321-2810 (Online), ISSN: 2321-8525 (Print)
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Fig. 3: Effect of Monomer Flow Rate on Catalyst, Co-catalyst and Hydrogen.
Fig. 4: Effect of Monomer Flow Rate on Polyethylene Production Rate.
From the Figure 2, it is observed that increased
monomer flow rates demanded more solvent
and the co-monomer flow rates.
Figure 3 effect of monomer flow rate on
catalyst, co-catalyst and on hydrogen flow are
shown. It is evident that the increased flow of
monomer correspondingly increased the
values of catalyst mass, co-catalyst mass and
the hydrogen flow rate. The effect of monomer
flow rate on the production of the polyethylene
product is shown in Figure 4. Figure 4 reveals
that the increased monomer flow rates
increased the production of the product
polyethylene.
The Aspen HYSYS balance model used for
the loop reactor provides heat and material
balance facility only. This model does not
calculate the effect of the pressure and
temperature on the remaining operating
variables. This is the limitation of this study.
CONCLUSIONS
This study shows the relation between the
operating parameters like independent
parameter monomer flow rate and the
dependent parameters like the flow rates of
solvent, co-monomer (1-hexene), co-catalyst
(triealuminium) and the catalyst. Results has
been reported the relation between the various

4. Aspen HYSYS Simulation of Suspension (Slurry) Process Rao and Abdullah
JoPC (2018) 1-4 © STM Journals 2018. All Rights Reserved Page 4
operating parameters. The slurry process
model used in this study for the production of
polyethylene is useful for process engineers in
evaluating the process parameters
quantitatively. The material and energy
balances given by this model are useful in
solving the time to time challenges of the
polyethylene process plant.
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Cite this Article
K. Nagamalleswara Rao, Aslam Abdullah.
Aspen HYSYS Simulation of Suspension
(Slurry) Process for the Production of
Polyethylene. Journal of Polymer &
Composites. 2018; 6(3):