De-ethanizer sizing

[chaker05]

dear Friends,
I need to size a de-ethanizer column with reboiler in the bottom and without condenser.
Please help

[ammadkhan]

select light key (ethane) and heavy key (propane), use fenski equation and redwood gilliland correlation for column sizing.

regards,

[chaker05]

Thank you ammadkhan,
but in ordor to use fenski equation it's necessary to calculate the minimum reflux, and in our case we don't have any reflux ( without condenser)??????????

[ColinR33]

That is a very broad, vague question. What part of the sizing do you need help with, the actual physical column sizing or figuring out how many stages you will need? What are you using to calculate/size your deethanizer? Have you done a simulation or is it all hand calculation? This is essentially a stripping column, you only have one degree of freedom, which would be your bottom product spec (ethane in NGL's). Rule of thumb, you'll need around 10 theoretical stages in this sort of separation (which will be rather crude, a lot of C3 will go overhead due to lack of reflux), operating pressure in the 275-350 psig range depending on composition, bottom temperature will depend on composition and pressure but is usually 190-275°F, typical bottom product spec is 2% C2/C3 ratio, but that can vary from location to location. Typically this type of column is used on smaller gas processing plants (dewpoint control or low-grade lpg recovery) with the liquid feed coming from the Low Temperature Separator and being fed to the top of the column as a cold feed reflux.

Cheers,