Transcript CENG 221 Lecture 4. Multi-component Distillation (4.5 h) Learning Objectives:

CENG 221
Lecture 4. Multi-component Distillation (4.5 h)
Learning Objectives:
(1) Multi-component flash distillation calculation
(2) Multi-component column distillation
Fenske Equation
Underwood Equation
Gilliland Correlation
(3) Column sizing
Column diameter
Column height
(4) Introduction to packed column
Learning Guides:
(1) Lecture handouts
(2) Chapters 3.3, 7.1, 9.1-9.3, 12.1, 12.3, 13.3 of Textbook:
Equilibrium-Staged Separations
Multi-component Column Distillation
QC
Total Condenser
D, xDi
R
Q=0
F, hf
zi
(n)
Partial
Reboiler
QR
B, xBi
Multi-component Column Distillation
QC
Total Condenser
D, xDi
R
Q=0
F, hf
zi
(n)
Partial
Reboiler
QR
B, xBi
A 2000 kmole/h feed containing benzene (0.2), toluene (0.3) and
xylene (0.5) are to be separated using the distillation column shown
above. 90 percent of the toluene is to be recovered at the distillate and
98 percent of xylenes is produced at the bottom.
(a) label the key and non-key components
(b) what is the value of D and B?
(b) what is the distillate and bottom composition?
Column Distillation
QC
Total Condenser
D, xDi
R
Q=0
F, hf
zi
(n)
Partial
Reboiler
QR
B, xBi
A 100 kmole/h feed containing methanol (0.3) and water (0.7) is to be
separated using the distillation column shown above. 90 percent of the
methanol is to be recovered at the distillate and 90 percent of water is
produced at the bottom.
(a) label the key and non-key components
(b) what is the value of D and B?
(c) what is the distillate and bottom composition?
Fenske Equation (Total Reflux)
Calculates for Nmin
Nmin = Ln [(xA/xB)d/(xA/xB)b]
Ln aAB
where xA is concentration of key component A (usually LKC)
xB is concentration of key component B (usually HKC
For binary components
Nmin = Ln [(xA/1-xA)d/(xA/1-xA)b]
Ln aAB