Aspentech’s Hysys: Fluid Package (Thermodynamics)
Notes
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2009/12/04
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 H2OHydrocarbon 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:
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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
Semi-Empirical methods:
-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
-OLI: electrolyte
-Amine: sour sweetening with amines
-Steam tables: ASME, NBS
Binary Interaction Permaters:
-Are many defaults, others estimated by BP & Density, most user can overwrite
Refining:
-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
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