scf/bbl to mol/mol 3

[intel2]

Hello,

can someone help me convert scf/bbl to mol/mol ( its the loading of H2S in DEA)


Thank you

 

[katmar]

It is easiest if you split the problem into two halves - first work out how many mols of H₂S you have, and then how many mols of DEA.

At standard temperature and pressure you can assume your gas is ideal and use the ideal gas law, i.e. PV=nRT. Taking standard conditions as 60F (519.67 Rankine) and 14.7 psia and R=10.7316 you will see that the volume of one lb mol of gas at STP is 379.4 ft³/lb mol. So if you divide your scf of H₂S by 379.4 you have the number of lb mols of H₂S.

Now, looking at the DEA (assuming you mean diethanolomine) with a molecular weight of 105.14 and a density of 67.4 lb/ft³. A barrel is 5.615 ft³. This makes 1 bbl of DEA
1 x 5.615 x 67.4 /105.14 = 3.60 lb mol

From the first step you have the number of mols per bbl, so divide that answer by 3.6 and you have your answer in mol/mol. Or you could combine the two factors and just divide the value in scf/bbl by 1366 (=379.4 x 3.60) to get the answer directly.

Katmar Software
Engineering & Risk Analysis Software

http://katmarsoftware.com

 

[intel2]

you sure its not related to concentration the DEA

 

[mbeychok]

katmar:

I'm pretty sure that the original poster (intel2) is talking about scf of H2S per barrel of aqueous amine solution ... since most (if not all) amine gas treating units use a solution of amine in water.

So one must know the concentration of pure DEA in his specific aqueous solution before working out the conversion.

Milton Beychok
(Visit me at www.air-dispersion.com)
.

 

[katmar]

Yes, of course if the DEA is not pure then the concentration would have to be taken into account. Incomplete questions get incomplete answers.

Katmar Software
Engineering & Risk Analysis Software

http://katmarsoftware.com

 

[dcasto]

The GPSA data book has a quick table that answers your question. In FIG 21-3, DEA is listed as having a H2S pick up of 6.7 to 7.5 SCF/gal. The foot note reminds us that the pick up is dependent on the partial pressure and concentrations of the DEA in water.

At low pressure and therfore low partial pressures, the loading is reduced, hence DEA should not be used with pressures under 200 psi unless there is no concern about top tray equilibriums that allow more than 10 ppm of H2S in the exit gas.