3 replies to this topic

[purvamehta_5]

Hello all,

 

Can someone kindly explain me why does the temperature profile of the column drop when there are more light ends in the feed. IF more light ends it implies that the feed vapor pressure is higher. The column operating pressure should be the vapor pressure of the liquid. If vapor pressure/operating pressure goes high, since in equilibrium the temperature should go high as well.

 

Please explain.

 

Thanks 

[Bobby Strain]

You seem to know nothing about distillation. You should find a good book or article.

 

Bobby

[Pilesar]

Operators of distillation columns normally control the pressure. The temperature then varies with composition.

[Padmakar Katre]

Hello all,

 

Can someone kindly explain me why does the temperature profile of the column drop when there are more light ends in the feed. IF more light ends it implies that the feed vapor pressure is higher. The column operating pressure should be the vapor pressure of the liquid. If vapor pressure/operating pressure goes high, since in equilibrium the temperature should go high as well.

 

Please explain.

 

Thanks 

Hi,

Can you tell us your background? Are you a student or a process engineer?. Is it just a generic doubt you have or you are experiencing such problem in an operating column.

 

Column pressure is always set to a certain value and doesn't change much with feed rate or composition subject to change in composition is not significant. Now when there are more lighters in feed, the overhead product yield will be more (a liquid distillate or a vapor product), the column pressure is slightly adjusted to increase the dew point to the extent the cold utility and condenser surface can condense the required liquid distillate. At the same time column bottom temperature will also go up due to higher pressure and needs to check if heating medium at reboiler is adequate to deal with this situation. 

 

This is just a brief answer.