HW10_Sol_v3_28nov05

HW10_Sol_v3_28nov05 - Chemical Engineering 150B- Fall 2005...

Info iconThis preview shows pages 1–8. Sign up to view the full content.

View Full Document Right Arrow Icon
Chemical Engineering 150B- Fall 2005 Problem Set #10 Solutions Problem 1. (15 Points) Using the data below, construct the following graphs: (a) An equilateral ternary diagram of acetone as the solute, water as the carrier, and 1,1,2- trichloroethane as the solvent. Be sure to include the tie lines on the graph. (b) Compute the selectivity of the solute (acetone) for solvent (1,1,2-trichloroethane) at each tie line. Then, plot selectivity versus the concentration of 1,1,2-trichloroethane in the carrier (water). Acetone-Water-1,1,2-Trichloroethane Compositions on Phase Boundary: Extract, wt% Raffinate, wt% Acetone Water Trichloroethane Acetone Water Trichloroethane 60 13 27 55 35 10 50 4 46 50 43 7 40 3 57 40 57 3 30 2 68 30 68 2 20 1.5 78.5 20 79 1 10 1 89 10 89.5 0.5 Tie-line Data: Extract, wt% Acetone Raffinate, wt% Acetone 56 44 40 29 18 12 (a) See Problem 3 for description of how to make the equilateral ternary diagram. The answer for this part is below:
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
10 90 80 20 30 70 60 40 50 50 40 60 70 30 20 80 90 10 90 80 70 60 50 40 30 20 10 Acetone TCE Water (b) Define selectivity of acetone for solvent as: Selectivity = (wt% acetone in solvent rich phase / wt % acetone in carrier rich phase) / (wt% water in solvent rich phase / wt% water in carrier rich phase). At the tie lines, we can read off the compositions of both phases, and then plot: 10 pt
Background image of page 2
Tie Line compositions Acetone Water Trichloroethane 56 9 35 40 3 57 18 1 81 Read from graph Read from graph Acetone Water Trichloroethane 44 51 5 29 69 2 12 87 1 Read from graph Read from graph S ws in C in raffinate (wt%) ws in C in extract (wt%) 7.21 5 35 31.72 2 57 130.50 1 81 Raffinate, wt% Extract, wt% 0 20 40 60 80 100 120 140 0246 wt% of solvent in carrier in the RAFFINATE Selectivity of acetone 0 20 40 60 80 100 120 140 0 2 04 06 08 0 1 0 0 wt% of solvent in carrier in the EXTRACT You can see that as more solvent is in the raffinate, the selectivity of acetone for the solvent rich phase decreases. [Alternatively, more solvent in the extract increases the selectivity of acetone for the solvent rich phase.] NOTE: Credit should be given to either graph; only one is required. The exact values for S are highly dependent on the small values read on the graph, so credit will be given to values within 50% of the values above. Problem 2. (25 Points) One thousand kilograms per hour of a 45 wt% acetone-in-water solution is to be extracted at 25 o C in a continuous countercurrent system with pure 1,1,2- trichloroethane to obtain a raffinate containing 10 wt% acetone. Using equilateral ternary diagram (from Problem 1), determine the following: (a) the minimum flow rate of solvent, (b) the number of stages required for a solvent rate equal to 1.5 times the minimum, (c) the flow rate and composition of both the raffinate leaving the last stage and extract leaving the first stage, and (d) the flow rate and composition of the raffinate leaving the second stage. 5 pt
Background image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
2 pt
Background image of page 4
4 pt 2 pt
Background image of page 5

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
10 pt for correct diagram [Student should show interpolation between tie lines (conjugate curve) and stage stepping]
Background image of page 6
(d) Total mass balance around first 2 stages: 1000+E 3 = R 2 +E 1 From part (c), E 1 = 770 kg/h , which means E 3 = R 2 - 230 Find compositions of the streams from graphs entering/leaving the first 2 stages: N =1 Extract, wt%
Background image of page 7

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Image of page 8
This is the end of the preview. Sign up to access the rest of the document.

This homework help was uploaded on 04/02/2008 for the course CHEM 150b taught by Professor Bell during the Spring '08 term at Berkeley.

Page1 / 20

HW10_Sol_v3_28nov05 - Chemical Engineering 150B- Fall 2005...

This preview shows document pages 1 - 8. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online