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[Kalp]

Hi All,

I am Kalpana Singh...I am a chemical engineering student and working on my Master thesis presently..

A part of my thesis is to simulate Amine absorption process in Aspen Plus using MDEA Solvent and Electrolyte NRTL model ...I am a little confused with the reaction model taken by Aspen Plus...

In the Chemistry they use the following reactions:

1. 2H2O <=> H3O+ + OH-
2. CO2 + 2H2O <=> H3O+ + HCO3-
3. HCO3- + H2O <=> H3O+ + CO3--
4. H2S + H2O <=> H3O+ + HS-
5. HS- + H2O <=> H3O+ + S--
6. MDEAH+ + H2O <=> H3O+ + MDEA

and in the Reaction they use the following reactions (which include kinetic reactions):

1. 2H2O <=> H3O+ + OH-
2. CO2 + OH- -> HCO3- (Kinetic)
3. HCO3- -> CO2 + OH- (Kinetic)
4. HCO3- + H2O <=> H3O+ + CO3--
5. H2S + H2O <=> H3O+ + HS-
6. HS- + H2O <=> H3O+ + S--
7. MDEAH+ + H2O <=> H3O+ + MDEA
8. MDEAH + H2O + CO2 -> MDEAH+ + HCO3- (Kinetic)
9. MDEAH+ + HCO3- -> MDEAH + H2O + CO2 (Kinetic)


My questions are:
1. Why there is no reaction of H2S with MDEA included in this reaction model?
2. Why the reaction number 2 of the Chemistry excluded and 4 new reactions are (2,3,8,9) added to the Reaction model.
3. What is the significance of adding these 4 reactions?

I am totally new to the amine absorption process....Please help me to find out the theory behind the reactions.....Also please let me know that the reaction model used by Aspen is Right or Wrong??