Aspentech’s Hysys: Fluid Package (Thermodynamics) Notes
Aspentech’s Hysys is a process simulation tool. You always have to pick a “fluid package” when you use the program: a thermodynamic method it will use to calculate properties, especially vapour-liquid equilibria. I watched an old “webinar” (presentation given through the Internet) on their property packages and took some notes.
You can combine this post with the Hysys manual, the Hysys property package wizard, Aspentech Support’s advice, and books on simulation, and put it all together to choose the best package in each case. If you are in doubt Aspentech Support can always give you personalized advice. They are really quite good at quickly suggesting the best method to use.
One trick to remember is that you can use different fluid packages and different component lists in different parts of the simulation. You can have a Peng-Robinson Package running the calculations for your hydrocarbons, and the ASME Steam Package running the steam and water calculations.
Here are my notes from the webinar:
-Hydrocarbons: normally use an Equation of State method
-Vapour pressure models are OK at low pressures
-Activity coefficient like NRTL is poor model for hydrocarbons
Equations of State:
-Peng-Robinson is most enhanced in Hysys, highest T & P range, has special treatment for key components, largest binary interaction database: good standard for hydrocarbons
-PRSV: extends PR to moderately non-ideal systems and better represents poor components and mixtures. Adds a new parameter to the equation. Slower calculation speeds than Peng-Robinson
-SRK: modified Redlich Kwong model. Similar accuracy/use as Peng Rob, but in Hysys SRK has less enhancements than PR.
-PR-Twu, SR-Twu for hydrogen solutes? In liquid hydrocarbons
-TST: hydrocarbons with non-ideal components (used in glycol package)
-GCEOS: generalized cubic EOS for user to add their own parameters. Use this to build your own model when necessary
-MBWR: a modification of the old BWR models: 32 parameters, more empirical approach, so it works very well in the range where it has data
-Lee-Kesler-Pockler: modified BWR for non-polar substances, mixtures
-BWRS: modified BWR for multicomponents, requires experimental data
-Zudkevitch Joffee: modified RK method for VLE, systems with H2
-Kabadi-Danner: modified SRK with Liquid-Liquid-Equilibrium calcs for liquid H2O-Hydrocarbon systems, especially dilute, parameters must be tuned to experimental data
-Sour PR/SRK: sour water systems with H2S, CO2, NH3 at low to moderate P
Vapour Pressure Models:
These models OK for hydrocarbons. Historically they were used since computationally they are easier. Now with modern computers EOS models are easy to run, so vapour pressure models are used less often. However, Braun K10 is still good for vacuum units.
-Modified Antonie: OK for low pressure ideal systems
-Braun K10 Model: strictly applicable to only heavy Hydrocarbons @ low pressures
-Esso K: only heavy Hydrocarbons @ low Press
-Chao-Seader: hydrocarbons if T = 0-500C, P<10,000 kPa
-Grayson-Streed: Chao-Seader extention with emphasis on hydrogen, good if heavy hydrocarbon with lots of hydrogen like hydrotreaters. Is recommended for vacuum units.
-Glycol Package: TEG circulation rates, purities of lean TEG, dew points and water content of gas stream used in natural gas dehydration. Use PR for MEG, DEG, but be careful of results outside of standard range
-Clean Fuels: Thiols and Hydrocarbon
-Amine: sour sweetening with amines
-Steam tables: ASME, NBS
Binary Interaction Permaters:
-Are many defaults, others estimated by BP & Density, most user can overwrite
-For hydrocarbons and hypocomponents use PR, SRK, or other EOS
-Vacuum unit – GS, PR, BK10
-High-hydrogen units like hydrotreaters – GS, PR, PR-Twu, or ZJ
-Sour gas sweetening – Amine
-Sour water – Sour PR/SRK
-Clean fuels for sulphur components & HC
-Utilities with water – use one of the steam tables. Steam tables are only for 100% water systems but are the best choice for these systems
2010-11-12 – Added note that multiple fluid packages can be run in the same simulation