1. CHEN 4460 – Process Synthesis, Simulation and Optimization Dr. Mario Richard Eden Department of Chemical Engineering Auburn University Review of Midterm Exam October 21, 2008 Review of Midterm Exam

2. Problem I (30 points) Multicomponent Separation –Sharp splits and cost is given as total cost SeparatorSplitCost $/yr 1A / BCD254,000 2AB / CD530,000 3ABC / D94,000 4B / CD460,000 5BC / D64,000 6A / BC247,000 7AB / C500,00 8C / D32,000 9B / C420,000 10A / C190,000 First Split Second Split Third Split

3. Problem I (30 points)

4. Problem IV (30 points) SequenceTotal Cost $/yr 1-4-8746,000 1-5-9738,000 2-8-10752,000 3-6-9761,000 3-7-10784,000 1 st 2 nd Worst

5. Problem II (40 points) Feed –60 kgmol/h A, T b = 50  C –60 kgmol/h B, T b = 70  C –280 kgmol/h C, T b = 65  C Binary azeotropes –A-C: x A = 0.50 @ 45  C –B-C: x B = 0.50 @ 60  C x A = 0.15 x B = 0.15 x C = 0.70

6. Problem II (40 points) A BC 70ºC 60ºC 45ºC 65ºC 50ºC Feed Spec. II Spec. I Spec. III Specifications I and II are achievable, but specification III is infeasible as it is on the other side of the distillation boundary

7. Problem III (20 points) Binary mixtures of acetone and chloroform at 101.325 kPa x-y diagram Binary azeotrope at Acetone molefraction: x acetone = 0.35

8. Problem III (20 points) Binary mixtures of acetone and chloroform at 101.325 kPa T-x-y diagram Boiling Points: Pure Chloroform T b = 61.2  C Pure Acetone T b = 56.2  C Azeotrope T b = 64.5  C

9. Problem III (20 points) T-x-y diagram –Feed A: 80 mol% chloroform  20% acetone –Feed A: 30 mol% chloroform  70% acetone Feed A Feed B Feed A: Min x acetone = 0 @ 56.2  C Max x acetone = 0.35 @ 64.5  C Feed B: Min x acetone = 0.35 @ 64.5  C Max x acetone = 1.00 @ 56.2  C

10. Problem IV (10 points) Vinylchloride Production –Direct chlorination of ethylene –Stoichiometric feed below, i.e. molar F E /F C = 1 –Ratio is increased to F E /F C = 5 and complete recovery of unreacted ethylene is assumed. F E, recycle = 4 * F E, stoichiometric = 4 * 89,800 lb/hr F E, recycle = 359,200 lb/hr  12,800 lbmol/hr

11. Problem V (10 points) Hydrogen (H), Benzene (B) and Toluene (T) Due to presence of hydrogen in the vapor, condensation will be VERY expensive. Therefore best choice is Sequence A

12. Results Class average: 73 Average of people who took exam: 79