Page 160 - Gas Purification 5E

148 Gas PuriJication

Table 2-24
Operating Data for Aqueous Diethanolamine Plants Treating Natural Gas

Gas Feed Rate, MMscfd 35.5 2.92 452
Solution Flow rate, gpm 1,540 188 1061 11
Solution Composition, wt8 DEA 20 28.7 28.9
Feed Gas Analysis
HzS, ~01% 15.0 0.054 0.5
co2, YO19 10.0 1.3 7.0
COS, ppm 300 - -
Outlet Gas Analysis
HIS, gr/lOO scf 0.28 0.01 0.05
C02, ppmv 20 150 200
COS, ppmv 0 - -
Lean Solution Loading, mole/mole
H2S 0.0219 - -
coz 0.0063 - -
Total acid gas 0.0282 0.01 0.02
Rich Solution Loading, moldmole
H2S 0.423(3) - -
coz 0.274(3) - -
Total acid gas 0.697(3) 0.50 0.44
Absorber
Number of Trays 30 20 20
Pressure, psig 1,000 900 220
Lean Solution Temperature,"F - 102 95
Rich Solution Temperature,"F 124.5 109 133
Gas Inlet Temperature,"F - 72 48
Gas Outlet Temperature,"F - 108 81
Stripper
Number of Trays 20 31 20
Stripper Top Tray Pressure, psig 25 9.8 19
Reboiler Temperature,"F 272 241 24 1
Steam to Reboiler, lbkal. Solution 0.995 0.85 -
Sources: 1. Berthier (1959). 2. Butwell and Perry (1975). 3. Calculated valuesfrom Vaz et al. (1981)

C02. They also removed about 90% of the COS and a small fraction of the mercaptans pre-
sent in the feed gas. Data on the organic sulfur removal in one of these plants are given in
Table 2-26. The absorbers operate at unusually high temperatures (e.g., lean amine temper-
atures as high as 150°F). It is possible that this high temperature favors COS removal (by
increasing the rate of the hydrolysis reaction) and inhibits mercaptan removal (by reducing
equilibrium solubility).