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HYSYS Simulation of Chemical Process Equipment
Research · September 2015
DOI: 10.13140/RG.2.1.4186.9289
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HYSYS Simulation of Chemical Process Equipments
Sukanta Kumar Mondal1*, M. Rakib Uddin1, Sraboni Majumder1, Jeewan Pokhrel1
1*, 1
Department of Chemical Engineering and Polymer Science, Shah Jalal University of Science and
Technology (SUST), Sylhet-3114, Bangladesh.
E-mail: sukanta_sust@yahoo.com, mruddincep@gmail.com, sraboni007@yahoo.com,
pokh_jeewan@yahoo.com
Abstract
In this paper simulation of some process equipments were done by HYSYS 3.2. Equipment simulation is a basic
work to design a chemical process plant. HYSYS is an easy and leading powerful process engineering
simulation tool. Study shows the major advantages of the process simulator HYSYS over other simulation
softwares and the causes of it’s preference. The equipments were chosen from typical downstream oil and gas
process plants. This study involves the simulation of equipments such as heat exchangers, separators, vessels,
distillation column, pumps, compressors, heaters and absorption tower.
Keywords: Simulation, HYSYS, Heat and Material Balances, Process equipments.
1. Introduction
Aspen HYSYS is a market-leading process modeling tool for conceptual design, optimization, business
planning, asset management, and performance monitoring for oil & gas production, gas processing, petroleum
refining, and air separation industries. Aspen HYSYS is a core element of Aspen Tech's aspen ONE®
Engineering applications. It has vast importance for chemical engineers to simulate a process [1]. Aspen
HYSYS has established itself as a very intuitive and easy to use process simulator in oil and gas refining
industry. Users with little prior knowledge of Aspen HYSYS can pick up and train themselves in its modeling
capabilities. Some of the very intuitive capabilities include a highly interactive process flow diagram for
building and navigating through large simulations. It has efficient workflow for process design, equipment
sizing, and preliminary cost estimation [2].
The program also provides a very flexible and easy to use distillation column modeling environment.
Additionally the interactive nature of HYSYS enables users to build and use their models quickly and
effectively. Aspen HYSYS offers a comprehensive thermodynamics foundation for accurate calculation of
physical properties, transport properties, and phase behavior for the oil & gas and refining industries.
Comprehensive library of unit operation models including distillation, reactors, heat transfer operation, rotating
equipments, controllers and logical operations in both the steady state and dynamic environments [3].
Process simulation is used for the design, development, analysis, and optimization of technical processes and is
mainly applied to chemical plants and chemical processes, but also to power stations, and similar technical
facilities. Process simulation is a model-based representation of chemical, physical, biological, and other
technical processes and unit operations in software Basic prerequisites are a thorough knowledge of chemical
and physical properties [4]. Simulation is the imitation of the operation of a real-world process or system over
time [5]. Simulation can be used to show the eventual real effects of alternative conditions and courses of action.
Simulation is also used when the real system cannot be engaged, because it may not be accessible, or it may be
dangerous or unacceptable to engage, or it is being designed but not yet built, or it may simply not exist [6].
1.1 Modes of simulation
There are two modes of simulation- Steady state mode and Dynamic mode [8].
1.2 Steady State Mode
Initially process simulation was used to simulate steady state processes. Steady state models perform a mass and
energy balance of a stationary process (a Process in an equilibrium state) but any changes over time had to be
ignored.
1.3 Dynamics Mode
Dynamic simulation is an extension of steady-state process simulation whereby time-dependence is built into
the models via derivative terms i.e. accumulation of mass and energy. The advent of dynamic simulation means
that the time-dependent description, prediction and control of real processes in real time have become possible.
This includes the description of starting up and shutting down a plant, changes of conditions during a reaction,
holdups, thermal changes and more.
Dynamic simulations require increased calculation time and are mathematically more complex than a steady
state simulation. It can be seen as a multiply repeated steady state simulation (based on a fixed time step) with
constantly changing parameters [7, 13].
2. Equipment simulation
Due to the dangerous and expensive nature of training on heavy equipment, simulation has become a common
solution across many industries. Types of simulated equipment include process equipments, mining reclaimers
and construction equipment, among many others. Often the simulation units will include pre-built scenarios by
which to teach trainees, as well as the ability to customize new scenarios. Such equipment simulators are
intended to create a safe and cost effective alternative to training on live equipment [7]
2.1 Chemical Process Simulators
This is a short list of software used to simulate the material and energy balances of chemical processing plants.
 Aspen Plus, Aspen Hysys, Aspen Custom Modeler by Aspen Technology.
 CHEMASIM.
 CHEMCAD by Chemstations.
 ProSimulators by Sim Infosystems.
 ProSinPlus by ProSim.
 Flowtran Simulation by
 PRO/II, DYNSIM & ROMeo (process optimizer)
 UniSim Design & Shadow Plant by Honeywell
 PIPE-FLO Professional by Engineered Software, Inc. [9]
2.2 Simulation Description
In determining material and energy balances around a unit operation, most process simulators calculate the
product condition from the given feed condition [10]. Before any simulation occurs HYSYS needs to undergo
an initial setup. During an initial setup, the components and fluid packages to be used should be selected. New
simulation profile is created where simulation name and formula is entered. While making the PFD material
streams are specified and entered [3].
Fig 1: Initial declaration of the components and fluid packages.
By knowing the specific volume with the help of equation of state we can determine the size and thus cost of the
plant. Hysys offers GCEOS, Kabadi-Danner, Peng Robinson (PR), MBWR, PRSV, Soave Redlich Kwong
(SRK), Zudkevitch etc equation of state. Of these the Peng Robinson equation of state supports the widest range
of operating condition.
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a chemical process flowsheet is a conceptual representation of the transformation of raw materials into products
through a series of process unit operations connected by process streams [11].
Fig 2: HYSYS screen with various types of process equipments in a refinery process
2.3 Working with basic equipments
HYSYS incorporates the mathematical models for many process unit operations and knows which mathematical
algorithm of a process unit to use according to which variables we have specified [11]. Some of the process unit
operations like material stream, energy stream, component splitter, compressor/expander, cooler/heater, heat
exchanger, mixer, reactor, pipe segment, pump, reactor operations, separator, tank, column, tee, valve etc
supported by HYSYS are discussed as follows [11]:
2.3.1 Pump
The pump is used to increase the pressure of a liquid process stream [11]. In the simulation environment a well
defined stream is taken as the inlet feed of the pump, outlet stream and energy name is declared on the
connection tab. And in the parameter tab the calculated Delta P is declared. Depending on the information
specified, the pump calculates either an unknown temperature, pressure or pump efficiency. It calculates the
pump’s duty also.
Fig 3: Contacting Pump with streams
2.3.2 Compressor
The compressor operation is used to increase the pressure on inlet gas stream. Depending on the information
specified, the compressor calculates either a unknown temperature, pressure or compressor efficiency [12]. It
calculates the pump’s duty also.
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Fig 4: Contacting Compressor with Streams
2.3.3 Heat Exchanger
The Heat Exchanger performs two sided energy and material balance calculations. The Heat Exchanger is very
flexible and can solve for temperature, pressure, heat flows (including heat loss and heat leak), material streams.
In HYSYS Heat Exchanger model can be selected and either of the parameters or flow rates are mentioned to
obtain another. This can be done in steady state as well as in Dynamic mode of simulation. HYSYS shell and
tube heat exchanger is shown below as a model of the process.
Fig 5: Connections of Streams for heat exchanger.
The heat exchanger performs two-sided material and energy balance calculations.
2.3.4 Distillation column
Since this is a simple distillation case for a oil refinery, 4 well defined process streams are needed. Placed 4
material streams for the feed, the distillate, side product and the bottoms. And 2 energy streams for the re-boiler
and condenser. It results the converged solution.
Fig 6: Connections of a converged distillation column environment.
4
2.3.5 Vessel
in the steady state mode the vessel contents into its constituent vapor and liquid phases. The vapor and liquid in
the vessel are allowed to reach equilibrium, before they are separated.
Fig 7: Simulation of a vessel
2.3.6 Absorption tower with reboiler
The conditions and composition of the column feed stream, as well as the operating pressure, define the
resulting converged solution. The converged solution includes the conditions and composition of the vapor and
liquid product streams. The reboiler requires an energy stream to boil-up the absorbent.
Fig 8: Reboiled absorber
2.3.7 Separator
The product stream is fed into a 3-phase separator and the light liquid phase is separated from the heavy liquid
phase and vapor residual. HYSYS normally puts water in the heavy phase when there is a non-zero water
stream.
Fig 9: Three phase separator screen
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2.3.8 Heater
Heater heats a process stream (s). The heater is used to reach a high temperature in the stream (s). To simulate
the heater well defined inlet and outlet streams, heater efficiency with utility must be assigned.
Fig 10: HYSYS simulation of a fired heater.
2.3.9 Equipments together in a plant
This includes working with distillation, absorption and also separation columns in a natural gas process plant.
The needed output, available input conditions and parameters such as pressure, compositions are provided.
Simulator itself then comes out with solutions such as temperature desired to carry out the process.
Fig 11: Connections of equipments to build up a process plant
3. Applications
Hysys is mainly for oil and gas process industry but it’s expanded to various industries for simulation as:
 Petroleum Industry.
 Oil refinery.
 Heavy chemical industry.
 Petrochemical industry.
 Natural gas process plant.
 Synthesis Gas Production.
 Acid Gas Sweetening with DEA (Diethanolamine).
 Ethanol Plant.
 Biodiesel plant etc.
4. Advantages of HYSYS
 Improve engineering efficiency by up to 30%
 Improve energy efficiency by up to 30% and Reduce capital costs by 10-30%t
 Hysys provides an extremely powerful approach to steady state simulation.
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 Hysys approach to modeling maximizes return on simulation time through increased process understanding.
 Aspen Hysys offers a comprehensive thermodynamics foundation for accurate calculation of physical
properties, transport properties, and phase behavior and newer versions of Hysys have almost doubled in its
capabilities on physical properties.
 Aspen Hysys introduced the novel approach of steady state and dynamic simulations in the same platform. It
has become the defacto standard in industry, and today enjoys universal acceptance.
 Aspen Hysys let process engineers estimate the Green House Gas Emissions associated with a process.
 Refinery Reactor Technology which includes Fluidized Catalytic, Hydrocracking and Hydro-treating,
Reforming and Isomerization enable Aspen Hysys to perform single unit, multi-unit as well as refinery wide
simulations [3, 2].
5. Limitations
 Unlike Aspen, Hysys does not wait until we have entered everything before beginning calculations. It always
calculates as much as it can at all time and results are always available even during calculations. Any
changes made to the data are automatically propagated throughout the program to anywhere that entry
appears and all necessary recalculations are instantly carried out. This creates a problem when there is no
need for calculating the entire flowsheet over again every time whenever there is small change.
6. Economics
The cost of this software is approximately $45,000 for the dynamic version and $20,000 for the steady state
version. As compared to the pilot plant it is almost half of the minimum expected.
7. Conclusions
Equipments simulation is one of the basic works for designing any chemical process plant and to investigate the
process conditions. HYSYS is an effective tool for conducting a process design for an industrial system. The
goal of Hysys is to provide a capability to design an entire process completely and accurately. A process
engineer or a student first constructs a PFD showing all necessary real equipment. Recalculation of any
equipment is very easy and requires only few seconds. On the whole, using this simulation approach will be
helpful for any process plant to optimize the annual profit.
8. References
[1] Niaz Bahar Chowdhury, Zahid Hasan and A. H. M. Biplob, “HYSYS Simulation of a Sulfuric Acid Plant
and Optimization Approach of Annual Profit”, Journal of Science (JOS), Vol. 2, No. 4, 2012.
[2] Available at http://www.aspentech.com/aspen-hysys-midstream.aspx
[3] Trupti Ambar, Tyagee Chavan, Manali Kavale and S M Walke, “ Simulation of Process Equipment by using
Hysys”, International Journal of Engineering Research and Applications (IJERA) ISSN: 2248-9622, 2012
[4] Rhodes C.L., “The Process Simulation Revolution: Thermophysical Property Needs and Concerns”,
J.Chem.Eng.Data, 41, 947-950, 1996
[5] J. Banks, J. Carson, B. Nelson, D, “ Nicol Discrete-Event System Simulation”, Prentice Hall. p. 3. ISBN 013-088702-1, 2001.
[6] Sokolowski, J.A., Banks, C.M., “Principles of Modeling and Simulation”, Hoboken, NJ: Wiley. p. 6.
ISBN 978-0-470-28943-3, 2009.
[7] available at http://en.wikipedia.org/wiki/Process_simulation & http://www.globalsim.com/
[8] Availabe at Operation Guide, HYSYS 3.2, 2003
[9] Seader, J.D., Seider, W.D. and Pauls, “A.C.: Flowtran Simulation - An Introduction, 2nd Edition”, CACHE,
1977.
[10] K. Hing Pang, “A Novel Use of HYSYS to Design an Industrial Refrigeration System”, California
Polytechnic University, Pomona.
[11] Michael E Hanyak “Chemical Process Simulation and Aspen tech Hysys Software” Version 2006 ,
Bucknell university Lewisburg PA 17837 December 15 2007.
[12] Mohd.Kamaruddin Abd Hamid “Hysys: An introduction to Chemical Enginnering Simulation”.
[13] Aspen Hysys@ 2004.2 Dynamic Modeling.Issues addresses by Process Modeling (Aspen Hysys) V7.2
Cumulative patch 2, September 2010.
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