Hello All,
I am trying to optimize a design of a debutanizer to recover LPG as the ovhd and condensate as the bottoms. I have currently simulated as 30 theoretical stages with feed location on the 11th stage. Currently the cleint standard is to operate at 210 psig, which I think is high.
the product specs are: LPG: C5+ mole frac no more than 3%
condensate: RVP 12 psia
When I reduce the operating pressure in steps from 210 psig to 70 psig, obviously the reflux ratio and the reboiler duty is dropping. This is an indication of separation becoming easier at lower operating pressure.
My question is why do I not see the change in condenser duty. The temp. profile in the column is dropping from 209 F @ 210 psig to 120 F @ 70 psig. Should this reduce my condenser duty as well. can someone explain.
i am attaching a simple excel table indicating the results from HYSYS.
Thanks