2 replies to this topic

[ARAZA]

Dear All,

I'm designing a MEA striiper to strip off Co2 using 10 % of MEA solution. I need to calculate the boil up rate to design the overhead system such as O/H condenser and reflux pump.
I know the total amount of acid gas leaving the column, I also know the reflux ratio which is 4. My customer informed me that, ratio of moles of water vapor per mole of acid gas in the stripper overhead stream is reflux ratio which is 4. Total molar flow rate of acid gas is 0.12099 kg-mols/hr and water molar rate is 0.00912 kg-mols/hr.

Is this enough information to calculate reflux ratio and boil-up rate. can somebody tell me how to calculate the reflux??

Thanks in advance for your help

ARAZA.

[Zauberberg]

Reflux ratio is defined as:

(Molar flow of reflux water) : (Molar flow of dry acid gas), mol/mol

and is equal to about 0.60 - 1.20 for majority of amine systems. I forgot the figures for MEA, I think you can find some guidelines in GPSA Databook or "Gas Purification" by Koch/Nielsen. The minimum regeneration is dependent on:

1. Treated gas specs
2. Corrosion in lean amine circuit

I can't pull out the figures from my head, it was a long time ago when I was working on Gas sweetening unit design. I can give you the figures for aMDEA, and the recommended reflux ratio is about 0.60 - 0.70 for deep CO2 removal applications.

[Zauberberg]

Hi Araza,

Here's the document and from there onwards you follow relatively simple design procedure:

1. Choose appropriate amine solution/strength
2. Knowing the maximum RAL, calculate solvent circulation rate
3. Calculate the amount of energy required to desorb acid gas, and amount required to heat the solvent from tower inlet temperature to tower bottoms temperature
4. Use conservative figure of 1.0 mol of water per mol of acid gas, and calculate how much reflux water you need for this application.
5. Add this energy (= reflux evaporation at regenerator conditions) required to the figure calculated above (heating + desorption), and this is total reboiler duty. Add 10% margin on top of it.

Best regards,

Attached Files

•  Amine Concentration and Loadings.pdf   40.88KB   166 downloads