6 replies to this topic

[ConfusedChemEng]

Hi all,

 

I have been asked to calculate this at work, however I'm at a bit of a loss as to how to calculate this...

 

I am trying to find the max pressure reached in a condenser drum if the upstream condenser duty is reduced to only 20% of it's original duty. The condenser would be on the overheads stream of a distillation column, that is assumed to be operating normally at this point (reboiler still in service and feed coming in).

 

Is this something I'd model on HYSYS etc., or is there some literature that has the equations I'd need?

 

Any help is appreciated. Happy to answer any questions as well.

 

Thank you.

[latexman]

Are you sure about the wording? Usually it’s something like, what’s the maximum pressure with normal flow or at capacity and the condenser capacity is reduced to 20% of capacity. So, 100% flow and 20% cooling. The 80% of the vapor feed to the condenser has gotta go somewhere, right?

[Bobby Strain]

Now I am confused, too.

 

Bobby

[ConfusedChemEng]

Are you sure about the wording? Usually it’s something like, what’s the maximum pressure with normal flow or at capacity and the condenser capacity is reduced to 20% of capacity. So, 100% flow and 20% cooling. The 80% of the vapor feed to the condenser has gotta go somewhere, right?

Yes, this wording captures what I mean.

 

I'm unsure how to find the maximum pressure at normal flow, when the condenser capacity is reduced to only 20%. 

Edited by ConfusedChemEng, 24 January 2022 - 07:17 PM.

[latexman]

If 80% of the feed goes out the normal vent, what’s the backpressure at the condenser drum?

At a minimum, you’ll need to do a pressure drop calculation.

If all that flow cannot pass through the normal vent system, then vapor will accumulate and pressure will rise until it will all flow through the normal vent or a PSV or RD activates.

[Bobby Strain]

I'm even more confused.

 

Bobby

[breizh]

Hi,

Sorry to ask but... why do you operate your column at 100% when your condenser cannot operate at more than 20% of its capacity ?

Where will you release the material ?  

 

Breizh