Phase Envelope Critical Points 5

[Adria]

Where are the critical points for temp. and press. on a phase envelope diagram? Thanks.

 

[MortenA]

There is only one critical point.

Its position will depend on what type of diagram you are looking at (and of course which mixture).

Best regards

Morten

 

[TD2K]

On a pressure/enthalphy Mollier chart they are 'near' the top 'bulge' of the phase envelope. If you are using a process simulator to develop the phase envelope, they can also tell you the true critical properties. They will also give you 'pseudo critical' properties, do not use these. They are used for other various correlations.

 

[25362]

The critical point (CP) of a multicomponent hydrocarbon mixture rests on the upper portion of the P,T phase (isopleth) envelope where the bubble point and dew point lines meet. The CP values of P and T are usually lower than the cricondenbar and cricondentherm, respectively.

 

[DrillerNic]

The potion of the critial point on the phase diagram, and the reservoir P & T in relation to the critcal point defines the system you've got: black oil, volatile oil, wet or dry gas, condensate etc.

For some systems such as a wet gas, the critical point can be a long, long way from the 'bulge'.

 

[MortenA]

I was myself thinking trying to explain something like "near the top" but realised that its not allways true.

Try this link however to see where the critical point is in a P/T phase diagram:

http://www.chemistrycoach.com/Phase_diagram.htm

Every substanse (be it sing or multicomponent) has a critical point seen from a thermodynamic point of view. Not only hydrocan systems.

Best regards

Morten