Amine Sweetening - ProMax

[C26M13]

Dear Friends,

I am currently doing a simulation on CO2 removal unit using ProMax program. I have some issues in simulating my stripper column.

I have simulated the absorber column, but when it goes to stripper column it's unsolved

below is the message I got from ProMax:

ProMaxroMax!Project!Flowsheets!Flowsheet1!Blocks!DTWR-101
Error: The outer loop failed due to an error in the Kb parameters
Failed blocks:
ProMaxroMax!Project!Flowsheets!Flowsheet1!Blocks!DTWR-101

I tried to go though the model but I have got the clue to it. Could anyone help me out with this problem?

Regards,

Mitu

 

[maddocks]

Honestly this is a new one. I've been running this software for decades and haven't seen this error - you need to contact their helpdesk to see what's going on.

 

[Aggie03]

It's a numerical failure in the Boston-Sullivan Kb method. First, double check your inputs. Incorrect inputs or unrealistic scenarios are the most common causes of convergence failure. Example: setting up a system in a way that the purity of the bottoms product (lean amine in this case) is less than the feed.

If you believe that your inputs are correct, the column pressure, reboiler duty, rich amine quality, etc. are good, then try changing convergence methods. Switch from Boston-Sullivan to Composition-Dependent. See if that helps.

Ammonia accumulation in the regenerator can also cause convergence issues.

If all else fails, as maddocks said, contact BR&E support.

 

[C26M13]

Thanks a lot for all your great comments and suggestions. I have worked it out, the model already running good. Just need to try to match the temperature of the absorber mid bed temperature with the current Temp.

Cheers,

 

[C26M13]

Hi All,

can anyone advice me how to match the mid bed temperature on the absorber.
currently on my simulation I have, the temperature profile for the absorber doesn't look really match with what I require.

I have attached the Temp. profile, I want to move up the temp. of 60 deg C to the middle stage (between stage 6 and 7) of the absorber. I tried to ply around with the variables on the simulation but, I haven't got any good profile for this.

Could you please give me some clues to adjust the temp. of the absorber? Thanks.

Regards

 

[maddocks]

Matching tower temperatures in amine absorbers can be very challenging. it's a function of reaction chemistry, kinetics, interface, tray residence time, tray efficiency, foaming/froth, etc. You need to input the correct number of actual trays and then start adjusting efficiency values until the temperatures start to line up but I'm not sure the value of this - if your rich loading matches reality and your sweet gas CO2 content matches reality, then I wouldn't get too stressed about internal column temperatures lining up. You could also try using ProTreat - they have a different kinetic model that may provide closer results.