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[IonCube]

Its going to be a long but descriptive post which entails my case study for an x3 effect CaCl2 steam evaporator. Feed of 28w.t% is concentrated to 60w.t%. Properties of CaCl2Brine (not solid) are taken from DIPPR to create an hypo.

I used extended NRTL for every case study with no BIPs info for now

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In the Case#1: no modifications were made to the setup. It was realised that Specific Mass Heat Capacity kJ/Kg/K (Cp) of aqueous mixture is predicted very high at different w.t%. In the last column (table pic attached latter) you will see Cp value ranging from 3.8 - 3.3 (from literature it should be b/w 2 - 3).

 

To rectify the over-predicted Cp issue I experimented with Tabular properties.In the Case#2: I did this & it rectified my Cp problem (I DON'T KNOW HOW?). However my Mass Density kg/m^3; got highly under predicted.

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From the SimBasis literature; I got this which indicated that physical properties can be adjusted using (what I understood) sort of a fudge factor (Mixing parameter)

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I experimented & a factor of 1.3 gave reasonable results of Mass Density (at different temps & w.t% solutions). This fudge factor will be used to correctly represent density in both Case#2 & #3

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Again from the SimBasis literature

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So in Case#3 I tried changing these parameters (instead of Liq & Gas Enthalpies as in Case#2)

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Final results...

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Questions (& observations)

1] A higher steam consumption in #1 is due to higher Cp HYSYS predicted of aqueous solutions? I think yes because each separator T & outlet w.t% are practically similar for all cases

2] Why by just checking default values of Enthalpy(L, G) in #2 reduced Cp (& corrected problem)? Some details are highly appreciable

3] #2 & #3 is one & same thing? For all practical reasons the results are similar

4] Is my labeling of Mixing Parameter a fudge is OK?

5] Is there an alternative to adjust Cp without experimenting with Tabular properties? While creating a Hypo which property highly effects Cp prediction? (by fudging that I willn't go to Tabular properties at all)

 

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PM me if you need HYSYS case files. It has company info so cannot share publicly

Edited by IonCube, 26 April 2019 - 05:14 PM.

[Bobby Strain]

Did you look for information on the AspenTech support site? Or contact AspenTech? I've always found them helpful.

 

 

Bobby