2 replies to this topic

[NikyleMoodley]

Hi all,

I'm working on my final year design project, which involves a distillation/stripping column (MEA-based system) operating under vacuum. For diameter sizing I've been using the standard Coulson & Richardson (Sinnott) approach — flooding correlations (Fair's method / Souders-Brown), net area, downcomer allowance, etc.

My professor has told me this won't give the correct design for a vacuum column and that I need a different design method / code. Is there a specific named method/correlation that's considered "the" standard for vacuum column diameter sizing (as opposed to atmospheric), or is it really just the same flooding correlations with a pressure-drop-driven design philosophy layered on top?

[Pilesar]

Vacuum distillation columns work best with very little internal pressure drop. Because trays keep liquid on the tray by design, the static head of this liquid adds to the pressure drop. Packing is often used since it results in a lower amount of liquid held up in the active area and therefore lower pressure drop. This is not intended to be the direct answer to your question, but is something for you to consider. 

[NikyleMoodley]

Thanks Pilesar , I'll keep this in mind and look into it . I've only designed DCs with sieve trays before so I have my work cut out for me .