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Hunter-Nash Method For Liquid-Liquid Extraction

lle hunter nash extraction ternary diagram

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#1 crasfonts

crasfonts

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Posted 19 May 2015 - 05:19 PM

Hi there!

So I've been trying to solve the next problem:

93 kg/h of a mixture with ethylene glycol (EG) 35% and water (W) 65% is to be trated in a counter-current multistage setup with 30 kg/h of pure furfural to extract EG. The final raffinate R_N should contain no more than 2% EG. Determine number of stages required and composition of final extract.

 

I'm trying to solve the system with a ternary diagram ( http://imgur.com/bnAbfuh ). You see, I plotted Feed F, Solvent S, Pseudo-Mixture point M (0.265 EG, 0.491 W, 0.244 F) and R_N (0.02 EG, in the side of the curve that is rich on water).

 

Then I connected R_N with M, something that is supposed to give me E1, right? However, you will clearly see that E1 is on the side of the "raffinates" (i.e. right side), so that honestly seems weird. But I keep going and obtain R1 with the tie-lines. I found this to be weird, as it is a fraction rich in furfural: even richer than E1.

 

However, when I connect R1 with the operating point to obtain E2, it's clear to me that something doesn't check out: the intersection in the binodal curve surely can't be E2!! It's clearly on the "raffinate side" and it's rich in water.

 

What am I doing wrong? Any help would be greatly appreciated :)

 

 



#2 breizh

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Posted 19 May 2015 - 06:13 PM

http://cosmolearning...action-example/

It may help you ! Google should be your ultimate support :key words "Hunter -Nash Method"

Good luck

Breizh

#3 crasfonts

crasfonts

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Posted 20 May 2015 - 06:40 AM

Yup: in fact, I learnt how to solve these kind of problems via the LearnChemE videos. You see, if you skip to minute 5 (https://youtu.be/e0Yt5RMkyj4?t=300 ), you can see that the line R_N,M intersects with both S,F and indicates E1 where it crosses the binodal curve.

 

In that problem, M is not given, but in my case it is. Imagine that in the video, M is given and it has a really high concentration of IPA and ether. When you connect M with R_N, it will intersect the binodal curve on the "raffinate" side, which seems strange.

 

Perhaps this image could be useful to prove my point:http://i.imgur.com/WmJdWjE.jpg?1






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