Chemical Engineering - Mass Transfer - Discussion

Discussion Forum : Mass Transfer - Section 1 (Q.No. 9)
9.
Fenske's equation for determining the minimum number of theoretical stages in distillation column holds good, when the
relative volatility is reasonably constant.
mixture (to be separated) shows negative deviation from ideality.
mixture (to be separated) shows positive deviation from ideality.
multicomponent distillation is involved.
Answer: Option
Explanation:
No answer description is available. Let's discuss.
Discussion:
4 comments Page 1 of 1.

Kumar. said:   5 years ago
Tell me about multiple component distillation application & when it's required.

Roooo said:   10 years ago
Relative volatility is inversely to no.of stages.

Raj musale said:   1 decade ago
Fenske equation for minimum no of theoretical stages is:

Nm+1 = log(Xd(1-Xw)/Xw(1-Xd))/log (average relative volatility).

This equation suits best when relative volatility is constant; if relative volatility is not constant then avg relative volatility = (At Ab)^0.5.

Where At and Ab = Relative volatility of light key over heavy key at top and bottom of column respectively.
(3)

Piyush donda said:   1 decade ago
If the relative volatility of the light key to the heavy key is constant from the column top to the column bottom, then \alpha_{avg.} is simply \alpha.

If the relative volatility is not constant from top to bottom of the column, and in equation we doing relative volatility is constant though out column.

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