4 replies to this topic

[Princissa]

Hello,

 

I have mixture of water with methanol (50%, 50%) , i search to determine the critical point by using saturate curve, but i didn't find the curve which corresponds at this solution. Please, i need your help to resolve this problm by gining me the curve or to determine this point  by Hysis.

 

thank you in advance .

[Mahdi1980]

Hi,

 

The critical point or curve for such a mixture is not practical. It is too complex, due to the fact that each component have a different thermodynamic behavior at a temperature and pressure.

However there are some theoretical predictions which can be found on the net.

[serra]

there are many discussions in the forum about how to calculate phase equilibria including phase diagrams (envelope) etc.,

I agree with Mahdi that water+methanol phase equilibria is not easy to calculate,

you need to select a suitable model (from those available in your software),

with PRODE Properties I select CPA or EOS+complex mixing rules (NRTL) but VLE data regression is required for accurate results.

[spchauhan12]

Use Software such as Hysis & apply Property Packages for example - Peng-Robbinson EOS.

 

Regards,

 

SP

[serra]

I would not suggest Peng Robinson alone for Water-Methanol,

probably (not sure about accuracy on critical area) you may adopt Peng-Robinson with complex mixing rules as Huron Vidal, Michelsen-Huron-Vidal (MHV) or LCVM (combination of Michelsen and Huron Vidal) etc. or

Peng-Robinson plus association contribute (Cubic Plus Association with Peng Robinson EOS),

these models are available in Prode Properties,

you should investigate if there are equivalents in Aspen Hysys