Clean up of ethanolamine to improve performance and control corrosion of ethanolamine units

DETAILED DESCRIPTION OF THE DRAWING Referring to FIG.
1, the crude gas 1 containing CO.
sub.
2 and/or H.
sub.
2 S is passed upwardly through the ethanolamine absorber column 5, where the crude gas is countercurrently contacted with lean ethanolamine solution 3.
The lean ethanolamine solution 3 absorbs the CO.
sub.
2 and H.
sub.
2 S, thereby purifying the gas.
The purified gas stream 2 exits the top of the ethanolamine absorber column 5.
Upon absorption of CO.
sub.
2 and H.
sub.
2 S, the lean ethanolamine solution 3 becomes a rich ethanolamine solution 4.
The rich ethanolamine 4 is charged to the top of a stripper tower 7 and is stripped with steam 8 at about 240.
degree.
F.
to remove the CO.
sub.
2 and H.
sub.
2 S 21.
Upon stripping, the rich ethanolamine 4 becomes lean ethanolamine 9.
The lean ethanolamine 9 exits the bottom of the steam stripper tower 7 and is returned to the absorber 5 to start another cycle of absorption/stripping.
However, a fraction of the lean ethanolamine 10 is passed through a filter medium 11 to remove the solid suspension.
The filtere stream 12 is fed to a second vessel 13 containing strongly basic anionic resins to remove anionic species, such as SO.
sub.
4.
sup.
= and Cl.
sup.
-.
The effluent stream 14 then flows to a vessel containing cationic resins 15 to remove cations such as Na.
sup.
+, K.
sup.
+, Fe.
sup.
++, etc.
This cleaned lean ethanolamine solution 16 is combined with lean ethanolamine 17 to become the lean ethanolamine feed stream 3 for the ethanolamine absorber 5.
In a separate operation, the ion exchange resins are regenerated from time to time for reuse.
Turning now to FIG.
2, the regeneration solution comprising an aqueous solution of (NH.
sub.
4).
sub.
2 CO.
sub.
3, NH.
sub.
4 HCO.
sub.
3, NH.
sub.
4 OH or a mixture thereof 18 is fed to the anionic IX ion-exchange vessel 13.
The effluent 19 is fed to the cationic IX ion-exchange vessel 15.
The effluent liquid 20 may then be disposed of or stripped with steam for reuse.
The fraction of lean ethanolamine which should be cleaned through the ion exchange varies with the extent of contamination