Hysys - Dew/Bubble point 1

[wimple]

Hi

I am cheking a gas composition (almost Hydrogen, some water vapor and trace of heavy C5+ and C6+) to see wether I am inside the bell or at the right of the bell considering my operating temperature and pressure. I used Peng Robinson as basis EOS.
I get in Hysys only one Dew point curve and I dont see the bubble curve. What does it mean?
Can somehelp
This is urgent thanks in advance
Regards

Wimple

 

[khaoula]

The same curve containes buble and dew points
the right side(after the critical point) is buble side and the left side is the dew side.
i hope that it was helpful.

 

[wimple]

So this means that liquid and vapor cannot coexist together?
Why in some gas composotion we have a well shaped bell and here only one curve?

Thanks for your feedback
Rgds
Wimple

 

[wimple]

Should I need to perform a flash calculation to see the bell??!
thks

 

[EmmanuelTop]

wimple,

I've seen similar things happen in HYSYS (dew point curve without bubble point curve) when there are hypothetical components present in the material stream. Try to exclude these components and replace them with original components (n-paraffins available in HYSYS library). The properties of hypothetical component cut (C5+) can be tuned by varying mole fractions of original C5+ components.

Good luck,

 

[wimple]

EmmanuelTop

Thanks for your reply. So definitively it is not normal to see only one curve, thats confort me!
I will try to change the mol% of C5+ try to get some results

Rgds
Wimple

 

[CJKruger]

wimple, do a complete phase envelope curve and see what happens.

A mixture of H2 and heavy hydrocarbon is a strange system, and a single liquid phase may not be feasible under any reasonable operating conditions. This happens because H2 solubility decreases with decreasing temperature.

 

[EmmanuelTop]

Good point by CJ Kruger.

Sometimes, you will see in such systems the appearance of second liquid phase (two hydrocarbon liquid phases), due to specific nature of hydrogen.

CJ Kruger, a star for you. That is very important issue.

 

[dcasto]

here is vertually no bubble point because

STREAM CRITICAL TEMPERATURE (KAY'S RULE) F -338.77
STREAM CRITICAL PRESSURE (PRAUSNITZ-GUNN) PSIA 305.91

 

[lomli]

hi every body

try to set the graph cotrol and to enlarge the temperature and pressure axis until the tow curves appeare.

 

[khaoula]

sorry for the answer i misunderstood your question.