1. + Improved tower models SCDS Tower

2. + Quick cost estimates Tower cost, installed = $40,000

3. +

4. + Convert reboiler and condenser duties to costs Tower #1 design in red Suggested recycle range Short-cut distillation in black The tower is inexpensive relative to the operating costs.

5. + Two choices for detailed column design

6. + SCDS: non-ideal K-value chemical systems in distillation, absorption, strippers,… 2 or 3 phase systems

7. + TOWR Note: one of the least likely control methods in the field is to use mole fraction. Have you ever used a mole fraction meter? Rather, a number of variables that are easy to measure and control are the actual choices. These can be set in ChemCad, linking the solution to the control methodology. We will not address this feature in this course.

8. + It is easy to build the TOWR model on the same pdf as the short- cut column. This eases comparisons of the results. The two sheets are separable later.

9. + TOWR #1 Set-up for the MeOH/2-PrOH problem Select TOWR #1 from the ChemCad 5 list

10. + Problem design basis table Set column bottoms to 20% MeOH 10 actual stages @ 48% efficiency gives 5 theoretical stages VLE from NRTL F = 50:50 molar mixture of MeOH, 2- PrOH R = {5, 7, 10, 12, 15} Reboiler power = {0.5 kW to 1.75 kW} Feed tray @ 8 or 5; 30 mL/min feed

11. + Format – engineering units

12. + Thermophysical properties

13. + Stream 1 - feed

14. + TOWR#1 - General

15. + TOWR#1 – specifications long list of possible specifications

16. + TOWR#1 - convergence

17. + TOWR#1 – cost estimate Please choose sieve tray instead

18. + Report/Stream compositions/all streams

19. + Plot/Unit ops/Column profile

20. + Column profile Feed on stage 6

21. + Size/Distillation/Trays

22. + Sieve tray

23. + Tray 2

24. + Tray 6

25. + Tray 9

26. + Design starts … it is time to exercise the little gray cells… Sensitivity analysis Evaluate feed location from trays 2 to 9 Record reboiler duty, condenser duty, and reflux ratio Run TOWR#1 at feed stage = 2 prior to running the sensitivity analysis (gives a better chance for a clean run) Sensitivity analysis - feed tray location – let’s find an optimum location based on reboiler and condenser duties…

27. + Feed @ tray 2 – note the discontinuity in temperature profile

28. + Run/sensitivity study/feed loc/ adjusting

29. + recording

30. + Run/sensitivity/Plot results