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HYSYS and UniSim


HYSYS is powerful software that was created by Hyprotech for simulation of chemical plants and oil refineries.  It includes tools for estimation of physical properties and liquid-vapor phase equilibria, heat and material balances, and simulation of many types of chemical engineering equipment. 


Since its creation, HYSYS has been acquired and modified somewhat by Aspen and by Honeywell, where it is known as UniSim Design.  Hopefully, the advice below is equally applicable to both of these products.  If not, please let me know.


Although user friendly, considerable effort must be expended to master this software.   Following is advice to assist you on your way.  Where “HYSYS” is used, please understand that this is meant to indicate both Aspen HYSYS and Honeywell’s UniSim Design.  Cases created in Aspen HYSYS can be opened and run in UniSim.  It is not known if the reverse is true.  UniSim will not open files created in Aspen Plus.


A good way to begin learning HYSYS or UniSim is to do the first and third tutorials included with the documentation, called “gas processing” and “chemicals.”  For Aspen Plus this is probably located at C:\Program Files\AspenTech\Documentation 2004.2\Aspen Engineering Suite 2004.2\Aspen HYSYS.  For UniSim it is on the installation CD at Documentation/USD/UniSim.  See also the excellent step-by-step procedures in “Getting Started with ...” in the help contents. 


UniSim Tutorials online

·       Honeywell UniSim Design tutorials & applications (the gas processing and chemicals tutorials are recommended for beginners)

·       Queen’s University UniSim tutorials:

·       First

·       Second


Warning: HYSYS will allow you to have impossible things in your pfd, such as water flowing below its freezing point and the pressure increasing through a plug-flow reactor or heat exchanger. 


·        Exellent introduction (although becoming dated; from Rice University)

·        Aspen support site (includes HYSYS) Register to obtain ID and password.

·        For help on the particular form you are working on, press F1.

·        Uses and limitations: Excellent paper: Part 1    Part 2

·        More unit operations:  Note that the equipment palette in HYSYS shows only some of the equipment that HYSYS can model.  Click on Flowsheet, Add Operation (or press F12) to see a complete list, part of which is shown to the right.

·        Thermodynamics and properties estimation

·        Reactors

·        Distillation, absorption and stripping

·        Heat Exchangers

·        Pressure changes, pumps, compressors and piping systems

·        Mixers and splitters

·        Vessels:  flash drums, surge tanks and accumulators

·        Process flow diagram

HYSYS may not produce a satisfactory pfd, e.g. because of its representation of merging streams or inclusion of fictitious units (such as mixers and splitters) in a simulation.  You can create a beautiful flow diagram using Microsoft Visio, which is on Clarkson’s computers in CAMP.  Select Process Engineering PFD.  Show feed streams entering at the left and product streams exiting at the right, with the names of each prominently displayed so the viewer can readily see them.  If possible, as in Turton, put a stream table on the same page showing pressure, temperature, fraction vapor, total molar flow, component molar flows and any other vital information.

·        Personalizing HYSYS printouts

1.     Open the workbook, either by clicking on the workbook logo or on Tools/Workbook.  This opens a new item in the top toolbar for the Workbook.

2.     Click on the Materials Streams tab.

3.     Select from the top toolbar Workbook/Setup/Materials Streams.

4.     Delete variables not wanted and add variables desired.  The following are recommended: Temperature, Pressure, Vapor fraction, Mass flow, Molar flow, and component molar flows.  For the latter, click on Add and select Master Comp Molar Flow, All available components.  Alternately, Phase Component Molar Flows can be selected.

5.     If desired, change the name of an item by clicking on the left side of the cell with that name.

6.     Format the significant figures and put the variables in the order desired.

7.     Return to the Workbook and right-click on the top blue bar of the Workbook window.  Select Print Datasheet and Preview to make certain this page will appear as desired when printed.   

Improved safety of a LNG terminal by dynamics modeling using HYSYS

Disclaimer: The material on these pages is intended for instructional purposes by Clarkson University students only.  Neither Clarkson University nor Professor Wilcox is responsible for problems caused by using this information.


Last updated December 17, 2012.  Comments,  corrections and suggestions should be sent to Professor William R. Wilcox


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