combining two property packages within one

[Stephan]

We use Chemsep property packages within Cofe for process simulation.

Is there any way to use enthalpy and entropy calculations from one property package setting/model
and all other calculations from another property package setting/model?

That way we would try to combine the "best of two worlds" within the same stream in Cofe.

[jasper]

TEA supports this. You can set up a TEA package that uses an external phase equilibrium calculator (ChemSep) and one or more external property caculations (ChemSep).

[Stephan]

I couldn't find documentation on how to specify for example enthalpy to be calculated from Uniquac (Chemsep) and dewpoint to be calculated from PSRK (Chemsep).

[jasper]

In TEA?

- Add an external routine. Pick ChemSep, pick the property package, give it a name
- Select the external routine where desired.

[Stephan]

I want to use two different instances of Chemsep within TEA.
One Chemsep-Instance I would set to EOS: Haydon O'Connel, K-value: Prausnitz, Activity Coeff: Uniquac, Enthalpy: Ideal+Excess

From that instance I would like to calculate enthalpy and entropy for both liquid and gas.

The other Chemsep-instance would be P-SRK for everything.
That one I would use to calculate every property except enthalpy and entropy (P-SRK VLE and dewpoint calculations are very accurate in my application,
enthalpy and entropy are more accurate with the above ).

It seems like Tea refuses to add two different Chemsep-property Packs in external calculations.

[hkooijman]

an interesting idea. I guess this should be fixed at the PME level? I mean CS/copp makes a whole set of properties available like the K values, enthalpies and entropies, as well as physical properties but it is the PME that should offer the choice to not all use a cocktail of propeties i.e. K values from CS/copp, H and S from simple polynomials, and physical properties from TEA or as entered by the user as constant values. Can you be more clear as to what you want to combine and as to why?

Harry

[jasper]

Not clear on 'TEA refuses...' - does it provide an error message?

[Stephan]

Yes, it provides an error message:
"A calculation routine with the same CLSID is already loaded."

I tried to overcome this by using a combination of TEA and Chemsep.
I tried to use Hayden OCOnnel as GAS-EOS and calculate Gas-enthalpy via EOS.
I configured that within TEA.

I put a Chemsep prop pack into external routines, where PSRK is selected
for enthalpy and VLE-calculations.

Within TEA I set Chemsep for liquid enthalpy, fugacity and log fugacity.
For activity coefficient I would like to choose Chemsep external routine, however, this option doesn't exist in TEA.
Therefore I chose Uniquac for activity coefficient.

This setting worked well for pure substance enthalpies.

However, when combining two liquids it failed to calculate VLE-equilibrium.
Error message is in the appended file.
Flowsheet and TEA-setting is in appended file called Testfile, proppack "test18" contains the TEA setting.
Chemsep setting of the external Chemsep routine is attached as well.

What I try to do is to calculate gas enthalpy via EOS Hayden OConnel and everything else via PSRK from Chemsep.

[jasper]

[Stephan]

Thanks for updating.

fsd file is in the previous post already.