too high lean amine loading

[toggi]

I built an amine Hysys simulation model and want to have 0.001 lean amine loading. However, my lean amine loading is around 0.06 which is 60 times higher than my desired value.

I was told that Hysys simulation software has some limitations so it cannot simulate that low loading.
Is that correct?

If not or if so, how can I get the desired amine loading with Hysys simulation?

I used amine package.

 

[EmmanuelTop]

1. Make sure that you use Kent-Eisenberg model
2. Confirm regenerator reboiler temperature and operating pressure
3. How different is your rich amine loading in the model compared with true rich amine loading in the plant?

 

[maddocks]

I'm not sure if you can do this in Hysys, but you could try adding a small amount of an organic acid (I know this seems crazy), but this will help to shift the chemical reaction in favour of lower lean loadings.

 

[toggi]

Hello, EmmanuelTop

Thank you for your reply. I have some questions for you.
1. How can I use Kent-Eisenberg model in my Hysys simulation model?
2. My rich amine loading in the model is pretty much close to the true rich amine loading in the plant.
Only lean amine loading after regenerator is too high. I also found that design lean DEA loading is 5 times higher than the true lean DEA loading in the plant.

Thank you,

 

[toggi]

Hi, maddocks

Composition data of rich DEA is given already, so I can't add any other component. But thank you for your advice.

 

[dcasto]

.001 lean is not economical, the reboiler and reflux rates are high. I'd expect to see a 10 to 1 reflux ratio. Why do you need such low values?

 

[toggi]

Hi, dcasto
That's the requirement. I should build a model with .001 lean amine loading. Operating reflux rate is around 100USGPM which is low I think. Thanks!

 

[Jason5000]

I agree with maddocks. If you model your system with a specified, completely "clean" amine system you'll have a hard time matching reality in your regenerator. A little organic acid should help to simulate the affect of heat stable amine salts on your regenerator operation, but I'm not quite sure if it will work in Hysys with amines.

Any chance TSWEET is available to you?

Good luck.

 

[dcasto]

I've tried evrything, the close st in a vacuum tower at 100 to 1 reflux. I used Deshmukh-Mather (DESH) and Kent-Eisenberg (KENT).

 

[maddocks]

I think you may need to evaluate why the 0.001 loading is so critical. Is it to match plant data or lab data? If so, how confident are you in the lean amine results? You may wish to retest.

The only reason you need ultra-low lean loadings is to achieve an extremely low residual outlet gas H2S/CO2/mercaptan spec. Maybe you should try and match the outlet contaminant % and let the loading end up where it wants. Or, try matching the reboiler heat duty or reflux flow to see what happens. The other approach is to try and match the temperature of the vapours going to the amine reflux condenser - that is a better measure of reboiler performance. Can you do a regen stripper temperature survey?

Trying to match a preset lean loading is a little bit sketchy - it's more important to match the resulting effect.

 

[dcasto]

I got the reflux ration down, but the energy stays nearly the same. It the rich loading is lowered to 10%.

Back to original and
maddock question, why so low. If they insist, just tell them that is going to take more energy. If they need ultra low CO2 removal, look at mole sieves for polishing.

 

[lt5q5p]

I have found that it is possible to simulate an amine contactor in Hysys but minor variations will throw your results off dramatically. I have had better luck using Promax the updated version of T-sweet.

 

[dcasto]

winsim solved nicely too

 

[toggi]

Thank you for all who replied to my question.
My senior engineer and I agreed that Hysys doesn't simulate that low loading as dcasto, It5q5p, Jason5000 mentioned. I'll try with other simulation software.

Thank you again.

 

[dcasto]

If you really need some sage advice too, Huntsman will provide simulations using their products. I always run my own and then during bidding for the amine, each vendor (beside huntsman also)submits their in house runs and if their is a problem, it is caught before you put the agents into the system.