Page 92 - Gas Purification 5E

82 Gas PurLjcation

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Table 2-9
Sources of Solubility Data for CO, and H2S in Aqueous MDEA Solutions

MDEA Concentration
Reference kmoum3 (WtYO) Acid Gas
Jou et al., 1982 1.0,2.0,4.28 C02 and H2S
Bhairi et al., 1984 1.0, 1.75,2.0 C02 and H2S
Chakma and Meisen, 1987 1.69,4.28 co2
Maddox et al., 1987 1.0,2.0 (and 20%) COZ and H2S
Ho and Eguren, 1988 (23,49%) mixtures
MacGregor and Mather, 199 1 2.0 CO, and H2S
Shen and Li, 1992 2.6 co2
Jou et al., 1993 (35%) mixtures
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Note:
The MDEA concentrations are generally stated in the same units as the reference, except that
kmolhn-' is used instead of normality. For MDEA (molecular weight 119.1 7) the conversions for I, 2.
and 4.28 h0Um3 are approximately 11.8,23.5, and 50 wtK

Data on the solubility of acid gases in 4.28N MDEA at various temperatures are given
in Figures 2-44 and 2-45 for C02 and H2S respectively. The solubility of H2S in 1.ON
MDEA is described by Figure 2-46 (Jou et al., 1982). The effects of H2S on the solubility
of C02 and of C02 on the solubility of H2S are shown in Figures 2-47 and 2-48, respec-
tively. Limited data on the solubility of C02 and H2S in TEA solution are given in Figures
2-49 and 2-50.
Mixed Amines

The commercial use of mixed amines for gas treating is a very recent development, and
only limited data have been published to date. Li and Shen (1992) and Shen and Li (1992)
give experimental data on the solubility of C02 in several MDEA-MEA mixtures containing
30 wt% total amine. Austgen et al. (1991) provide some solubility data for C02 in aqueous
mixtures of MDEA with MEA and DEA. Jou et al. (1994) report on the distribution of C02
between the aqueous and vapor phases for mixtures of MDEA and MEA at temperatures of
25,40,80, and 120°C, and COz partial pressures ranging from 0.001 to 19,930 Wa.
Figure 251 (from Jou et al., 1994) presents a comparison of their data with those of Li
and Shen (1992). The Jou et al. data are believed to be more accurate because the Li and
Shen results do not agree with earlier Jou et al. (1982) results for MDEA nor with the data of
Austgen et al. (1991). Figure 2-52, which is also from Jou et al. (1994), shows the effect of
changing the amine mixture from pure MDEA to pure MEA (at a constant total amine con-
centration of 30 wt% and a constant C02/amine mole ratio of 0.1) on the partial pressure of
C02 at several temperatures.

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