Talk:Fenske equation

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Revision as of 18:30, 21 October 2009 by imported>Milton Beychok (→‎Equation explanation: Initial response to David Volk. More later.)
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 Definition An equation for calculating the minimum number of theoretical plates needed to separate a binary feed stream by a fractionation column operated at total reflux (i.e., meaning that no overhead product is being withdrawn from the column). [d] [e]
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Wikipedia has similar article

Wikipedia also has an article on the Fenske equation and I contributed to that article very extensively. I created this CZ article essentially by rewriting the WP article, reformatting it and expanding it. I did the rewrite in my CZ sandbox before creating this article. This CZ article is now much better than the one in Wikipedia.

The diagram in this article is not the same as the one in Wikipedia. I drew this article's diagram and uploadeded it into CZ. I also drew the diagram in the Wikipedia article. - Milton Beychok 13:05, 17 February 2008 (CST)


Equation explanation

It would appear that the equation explanation may be a bit off:

Does this part:

Xd = mole fraction of more volatile component in the overhead distillate Xb = mole fraction of more volatile component in the bottoms product

mean what it says, ie the mole fraction of the same compound, at two locations, or is this a typo from cut and paste? One of the references listed suggests that Xd and Xb are the mole fraction targets (desired level of purify) of the more volatile and the less volatile chemicals, respectively.

Also, I simple graph showing how N varies as Xd (and/or Xb) changes from values near to 1.0 and approaching 0.0 might be a nice graphic for discussion in the article. Or, at what mole fraction is N a minimum? (I suppose 1.0, neat product) David E. Volk 19:59, 21 October 2009 (UTC)

Also, doesn't the mole fraction of the feedstock come into play somehow for # of theoretical plates needed?

David, thanks for your interest in this article. Let me first say that the Fenske equation as now written is correct and Xd and Xb are indeed the mole fractions of the same component (the more volatile component or the one with the lower boiling point) in the distillate (overhead) and bottoms product.
It will take me a bit of time to explain in more detail and I will do that as soon as I can. However, for the time being I noticed that reference 3 (a lecture at Queens University) is no longer online ...so I am replacing it with a reference from a book instead which is also available online in Google books. Milton Beychok 23:30, 21 October 2009 (UTC)