8 replies to this topic

[mingggg11]

I'm performing an assignment with PRO/II, H2 process with amine sweetening process.

 

If I want to make amine sweetening process in Aspen HYSYS, there is an separator(absorber, ...) for amine process, and I can use these.

 

But in PRO/II, I can use only some columns (distillation, shortcut, side column), and I CANNOT find a way to express amine sweetening process with these columns.

 

In many references with amine process, all they use only distillation columns (as absorber and regenerator) to separate CO2.

 

I tried to make similar process with their input value in about hundreds times, but I could not make their process.

 

 

[pmoneysh]

PRO/II has a special package for amine treatment (very convenient). Go to miscellaneous in model palette and find AMSIM. Drop it in the flowsheet and work on it. Other than that, we can work on regular flowsheet like that in aspen hysys or any other software. Also, the distillation column in pro/ii is equivalent to that in aspen hysys. If want to use an absorber, uncheck the reboiler and condenser as you drop the column in flowsheet.

[mingggg11]

PRO/II has a special package for amine treatment (very convenient). Go to miscellaneous in model palette and find AMSIM. Drop it in the flowsheet and work on it. Other than that, we can work on regular flowsheet like that in aspen hysys or any other software. Also, the distillation column in pro/ii is equivalent to that in aspen hysys. If want to use an absorber, uncheck the reboiler and condenser as you drop the column in flowsheet.

Thanks for your answer, but I can't use the AMSIM. I think it's because I'm using license for only education, not for industry.

 

If I can't use AMSIM, is there any way to make this process only using column?

 

*I tried using "Performance specification" in distillation column setting such as (product CO2 flowrate / feed CO2 flowrate = 0.01 in absorber), but there are so many error.

Is this approach right?

[pmoneysh]

Condenser and reboiler option if unchecked, only the parameters to be specified should be pressure and feed stage locations. What parameters can we vary to meet the design (0.01)?

Edited by pmoneysh, 27 July 2021 - 08:59 PM.

[pmoneysh]

Please refer to the captured screen.

Attached Files

•  Capture.JPG   24.26KB   10 downloads

[mingggg11]

Only for absorber,

 

Setting now: distillation column with no condenser, reboiler / 50 C / 1.5 bar / feed tray 1(vapor with H2, CO2), 10(liquid with MEA) / AMIN01 thermodynamic system

 

I tried: changing tray number / setting "initial estimate" / setting "performance specification" >> so many error

 

I want: overhead vapor product with H2, no CO2 / bottom liquid product with CO2 in MEA

 

Other programs have "Absorber", but why pro2 has only distillation column?

 

Please give some tips to make amine process...

[PingPong]

It has already been said twice by pmoneysh, but here it is a third time:

an absorber is simply a distillation column without a reboiler and without a condenser.

 

As a consequence an absorber is a rather dumb piece of equipment and you cannot specify any requirements for purities or recovery or whatever.

 

You can vary the number of stages in the absorber and/or the rate of the lean amine.

 

The CO2 content of the gas leaving the absorber top is also dependent on the residual concentration of CO2 in the lean amine, but that is not a specification for the absorber but for the regenerator column which does have a reboiler.

 

 

I never used PRO II for amine sweetening, but I know there is an example file provided with PRO II.

You should also have it on your PC but in case you can't find it I have attached it here.

 

Absorber is on the left, regenerator on the right:

 

 G8_Amine_sweetening_plant_1.zip   167.46KB   56 downloads

Edited by PingPong, 07 August 2021 - 06:55 AM.

[Pilesar]

Without seeing your simulation setup and errors, it is difficult to troubleshoot. Put liquid feed to top stage and vapor feed to bottom stage. Take vapor product from the top stage and liquid product from the bottom stage. Specify the top pressure. Supply temperature estimate for top stage and bottom stage. Some troubleshooting tips:

1) Check the material balance. Are your feed flows reasonable? Are the compositions reasonable? Really check them as they may not be what you intended them to be. Mistakes in units of measure for stream flows can be hard to see without looking super closely.

2) Reduce the number of stages in the column. Use 6 instead of 10. It doesn't take many stages for this absorber and too many can cause numerical problems.

3) Add a damping factor of 0.4 to your column convergence. If your material balance is right and there exists an answer, then using a damping factor will cause the solution algorithm to take smaller steps to search for the solution. It may take more iterations, but computer calculation time is not something to scrimp on at this point of the simulation.

 

The AMIN thermo method should give good results for MEA solvent. What you should be looking for is a converged answer. After you get convergence, then you can adjust parameters like the liquid feed conditions to get the product specs you really want.

[Pilesar]

Your description of your feed setup said: "feed tray 1(vapor with H2, CO2), 10(liquid with MEA) / AMIN01 thermodynamic system"

Pro/II numbers trays from the top. So put the liquid feed to tray 1.