How to separate a gaseous mixture ?

antzlck

Sulphur trioxide is to be separated from a gas mixture containing N2, O2, and
SO3. Propose a method for carrying out this separation and briefly outline the
procedure for calculating the composition of streams leaving your chosen
separation unit.

Could anyone provide some guidance to me here. I'm a ChemEng undergrad.

Regards

Mech_Engineer

This is obviously homework. You'll need to show at least a little effort on your part before we can ethically help you.

antzlck

Oh right haha. It's not quite homework, it's exam revision ... 'sample questions' to give us an idea of the format of the exam. It's for a synoptic exam testing our foundational engineering knowledge and skill.

Thinking about it further I said we could use cryogenic distillation (this how you would go about separating the components of air right?), but the question is asking for a bit more than just naming a method. We have covered multicomponent distillation but it's not considered foundational knowledge, only binary so you would used McCabe-Thiele plot to design the cryogenic column?

Mech_Engineer

Sulphur Trioxide's boiling point is only 113 fahrenheit; it seems to me a simple heat exchanger cooling the mixture to around room temperature would be plenty to separate the SO3 into a liquid phase that can be easily removed through scrubbing condensation out of a filter or capture tank.

http://en.wikipedia.org/wiki/Sulfur_trioxide

Topher925

I can think of an even simpler method. Sulfur, often no matter what form, tends to want to stick to anything. Think about how diesel engines and sulfur generating processes remove sulfur from exhaust streams.