Question $3$

Distillation columns are used to separate light boiling components from heavier boiling

components and make up over $95\%$ of the separation systems for the chemical process

industries. A commonly used distillation column is a propylene$-$propane splitter. The overhead

product from this column is used as a feedstock for the production of polypropylene, which is

the largest quantity of plastic produced worldwide. The figure below shows a diagram of a

propylene$-$propane splitter $($C$3$ refers to propane and $C3=$ refers to propylene$).$ The steam is used

to provide energy and is not involved in the process material balance.

a$)$ Is this a batch, semi$-$batch or continuous process? Justify your answer.

b$)$ To solve the problem, you might assume steady$-$state operation. Under what conditions

is steady$-$state operation justifiable?

c$)$ Do a degree$-$of$-$freedom analysis for the process.

d$)$ Write the material balance equations needed to solve the problem.

e$)$ Find the top and bottom product flow rates. Show all calculations.

f$)$ What do you think would be needed if we wanted to have propylene in the top stream to

be more than $99\mathrm{.}7\%?$