5 replies to this topic

[CheGuy]

i am modeling a multicomponent tower with liquid sidestream in Aspen plus. i keep getting an error saying the stages from the liquid side stream to the feed are dried up. does anyone know how to troubleshoot that?

[Zauberberg]

It is possible that tower material/heat balance cannot be closed with the specifications and/or feed parameters that you have as model inputs. From your statement, internal reflux is practically = zero, at points below the side-cut location.

Reducing the sidestream draw-off rate might be of some help in further troubleshooting.

[AA Mishra]

Aspen is not good at modelling multicomponent towers.

Regards

[CheGuy]

Aspen is not good at modelling multicomponent towers.

Regards

can you suggest what is good?

[Zauberberg]

For C1+ hydrocarbon towers, HYSYS (now under "UniSim Design" name) is the best tool I have ever had a chance to work with. It is very intuitive and user-oriented flowsheeter, combining both excellent thermodynamics options and flexibility of simulation.

Do not have experience with Pro/II.

[wnovaes]

CheGuy,

This kind of trouble occurs when it’s fixed reboiler heat duty and it’s so high. So, verify your calculation for reboiler heat duty estimation or try heat duty decreasing in small steps up to ASPEN error warning message disappearing. The last option seems not a polite way. However, an advantage of using simulators packages software is minimize engineering time effort for recalculating by using a try-and-error approach, of course, since problem and process are well understand.

Best Regards,
WSN.