5 replies to this topic

[Damararose]

Hello,

 

I am trying to build a stripper model in which the overhead vapour will be used as heat source. I will be using reboiler at the bottom of the column without any reflux at the top; however some of the liquid knocked out from the overhead vapour will be returned to the column to replace the reflux function. I am currently using the reboiler absorber column palette available in HYSYS, but I have problem with convergence especially when the knocked out liquid is introduced into the column using recycle and side stream ops.

 

p.s: I could reach convergence after increasing the solver tolerance to 5E-3; but this is surely not the most accurate result.

 

Please advise if I am doing the right method? What did I miss?

 

Greatly appreciate your help

 

Regards,

Damara Rose

[Bobby Strain]

A screen capture(s) might help. Why would you use a side stream operation? Is water present in the feed?

 

Bobby

[Damararose]

Hi Bobby,

 

Yes there are water present in the feed (80% mole fraction). Here is the screen capture of the amine regenerator system I am trying to simulate.

 

Thanks in advance.

 

Regards

Attached Files

•  overhead vapor compression.png   208.65KB   2 downloads

[Bobby Strain]

Use a distillation operation instead of the reboiled absorber. And be sure to use the Amine package. This, you will find, is a very expensive heat source.

 

Bobby

[Damararose]

Hi Bobby,

 

Thank you for your response. I have tried using distillation column as you suggested and it did give me better convergence. Since I do not want any reflux, I specified the reflux ratio as low as possible. But then I have issue on maintaining the lean amine loading as it becomes really low compare to the value I had set previously. In consequence, the CO2 removal rate gets higher than 100%.

 

I am trying to build a model very similar to the attached picture below. I'm using acid gas package instead of amine package.

 

Your advice would be very appreciable

 

Thank you,

Damara Rose

 

Attached Files

•  overhead vapor compression1.png   34.64KB   4 downloads

[Bobby Strain]

The flowsheet is helpful. But I need to see your HYSYS PFD showing the operations and streams. Also, the distillation column should have a few trays above the feed point with the reflux returning to the top tray. Try this, then attach the PFD.

 

Bobby