Distillation

Question 1

What are the 3 main methods of distillation?

Answer 1

-batch (heated in closed pot)
-flash (fast/flash evaporation using low pressure to reduce boiling point)
-fractional (column with trays)

Question 2

What feature is on the edge of each distillation tray and why?

Answer 2

A weir, a slight raised part at the edge
-it generates resistance and turbulence
-this slows down the liquid and maximises the gas-liquid contact time

Question 3

What letter denotes the MVC (more volatile component) and which tray is most rich in it?

Answer 3

A is the MVC
y is the fraction of A in material balances

The top tray is very rich in A

Question 4

What is the top section of the column called?

Answer 4

Rectifying section

Question 5

What is the bottom section of the column called (below the feed tray) ?

Answer 5

Stripping section

Question 6

If a feed amount isn’t given what basis should be assumed?

Answer 6

100kmol

Question 7

How does R affect the column diameter and no. of trays?

Answer 7

R low:
-> lots of trays
-> very thin tall column

R high
-> fewer plates
-> short, wide column