Calculate Proof of Sat. water/ethanol given P/T?

[seasar]

Forgive me if this is the wrong forum for this question...

If I have a saturated mixture of ethanol and water (in a fractional distillation process) could I calculate the proof of the mixture from the temperature and pressure?

The trick is the "curve fit" between the two saturation lines (water and anhydrous ethanol)...Is this equation publicly available? Any help would be appreciated.

Thanks!

 

[katmar]

seasar, if you want to be able to model this system over a range of pressures and temperatures it is much more complicated than can be addressed in a simple post like this. A good place to start to develop an appreciation of what is involved is in Perry's Chemical Engineers' Handbook. Look up the van Laar, Wilson and UNIQUAC equations.

However, in a simple binary distillation it is often accurate enough to assume constant pressure for the thermodynamic calcs. If you do that then you only have to correlate composition against boiling point. You would have to develop two correlations. Firstly, model vapor composition as a function of liquid composition and secondly model boiling point as a function of liquid composition. This modeling is easily done using the curve fitting functions in Excel.

The raw data is available from

http://infosys.korea.ac.kr/kdb/index.html

Click on the "Hydrocarbons" button in the top left corner, and then on "Binary VLE" and then search for the ethanol-water system.

Katmar Software
Engineering & Risk Analysis Software

http://katmarsoftware.com