Mass Transfer: HW 7 - p 8.18 - TMW Extraction with Multiple Solvent Streams

Wednesday, November 15, 2006

Please post all of your questions about this problem as comments on this post. I will respond with my own comments.

Dr. B said...: More Hints:
The key here is to understand that a difference point is a construction that lets us graphically solve material balance equations. In this problem there are 3 difference point because solvent is added to each stage. P1 = E1 - F, P3 = E3 - R2 = S3 - R3 and P2 = E2 - R1.

Solve material balances on the entire system for E1, R3 and Stotal.

E1 lies on the 2-phase envelope. It also lies on the line connecting S and the solvent-free product. Once you have E1, you can find R1 using a conjugate curve to construct the appropriate tie-line. You can also locate E3 using a tie-line.

Next, evaluate P3 and use the lever rule (in mm) to locate P3 along line SR3. Once you have P3, you can locate R2 and then use a tie-line to locate E2.

Then, use material balances to solve for S1 and S2 individually.; 11/16/2006 9:07 AM