HW 3 - p 4.46 - Analysis of Extraction Using a Ternary Phase Diagram- 6 pts
Forty-five kilograms of a solution containing 30wt% ethylene glycol in water is to be extracted with furfural. Using Figures 4,14a and 4,14e, calculate:
(a) The minimum quantity of solvent.
(b) The maximum quantity of solvent.
(c) The weights of solvent-free extract and raffinate for 45 kg solvent, and the percent glycol extracted.
(d) The maximum possible purity of glycol in the finished extract and the maximum purity of water in the raffinate for one equilibrium stage.
(a) The minimum quantity of solvent.
(b) The maximum quantity of solvent.
(c) The weights of solvent-free extract and raffinate for 45 kg solvent, and the percent glycol extracted.
(d) The maximum possible purity of glycol in the finished extract and the maximum purity of water in the raffinate for one equilibrium stage.
posted by Dr. B at 2:29 PM
4 Comments:
the chart you give is different than the one they say to use in the book (fig 4.14a), the tie lines are sloped in the opposite direction. should we use the one in the book?
link 7:03 PM:
Wow. Good question !
One of the two diagrams has the water and furfural switched, but I am not sure which one.
I checked another source which agreed with the diagram that I gave to you as a pdf to download.
I found this original citation for the data:
"Ternary System Furfural-Ethylene Glycol-Water"
Conway, J.B., Norton, J.J., I&EC June 1951, p1433
Maybe you can look it up from a UW computer on Knovel.
Anyway, I want you to use my pdf diagram and NOT figure 4.14a. I did not use 4.14 e either.
you mentioned something in class about a method in the book for drawing new tie lines when M is not on an existing line. we couldnt find anything in the book about this, where is this located? we found something about the inverse lever arm rule, but that seems to be for determining more exact concentration readings from the graphs...
dazed but... 2:05 PM:
Sorry, bud, I did not realize that this technique was not introduced in Ch 4.
The use of conjugate curves to interpolate tie-lines on triangular phase diagrams is discussed on page 312.
Since we are not there yet, you can either read page 312 and use a conjugate curve, or you can just do an "eyeball" interpolation. Move about the same % up the extract curve as up the raffinate curve.
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