Maintaining the selective removal of H2 S from a variably flowing gas stream containing H2 S and CO2

Claim 1

A method for maintaining operative a Claus-type sulfur recovery system which recovers sulfur removed as H 2 S from an H 2 S and CO 2 containing industrial gas stream having a variable flow rate comprising (a) passing an H 2 S and CO 2 containing industrial gas stream through an absorption apparatus having a total absorption capacity dimensioned to treat the maximum gas flow, which absorption apparatus includes two absorption columns connected in parallel, each absorption column comprising at least two individual absorption sections connected in series, (b) contacting the industrial gas stream with a basic absorbent solution that absorbs H 2 S and CO 2 at different rates in the total absorption capacity of the absorption apparatus to afford a desulfurized gas stream and to produce a loaded absorbent solution, (c) regenerating the loaded absorbent solution in a desorption apparatus to desorb the H 2 S and CO 2 to yield a foul gas stream, (d) reacting the foul gas stream in a Claus-type sulfur recovery system to form elemental sulfur, (e) directing the passage of the basic absorbent solution through the absorption apparatus to bypass an individual absorption section and to eliminate said individual absorption section from the effective gas-liquid contacting process as the flow rate of the industrial gas stream decreases and before the flow rate falls to that rate at which the Claus-type sulfur recovery system becomes inoperative to afford a desulfurized gas stream and to produce a loaded absorbent solution, and (f) repeating steps (c) and (d).

Claim 2

A method for maintaining operative a Claus-type sulfur recovery system which recovers sulfur removed as H 2 S from an H 2 S and CO 2 containing industrial gas stream having a variable flow rate comprising (a) passing an H 2 S and CO 2 containing industrial gas stream through an absorption apparatus having a total absorption capacity dimensioned to treat the maximum gas flow, which absorption apparatus includes two absorption columns connected in parallel, each absorption column comprising at least two individual absorption sections connected in series, (b) contacting the industrial gas stream with a basic absorbent solution that absorbs H 2 S and CO 2 at different rates in the total absorption capacity of the absorption apparatus to afford a desulfurized gas stream and to produce a loaded absorbent solution, (c) regenerating the loaded absorbent solution in a desorption apparatus to desorb the H 2 S and CO 2 to yield a foul gas stream, (d) reacting the foul gas stream in a Claus-type sulfur recovery system to form elemental sulfur, (e) directing the passage of the basic absorbent solution through the absorption apparatus to bypass an individual absorption section and to eliminate said individual absorption section from the effective gas-liquid contacting process as the flow rate of the industrial gas stream decreases and before the flow rate falls to that rate at which the Claus-type sulfur recovery system becomes inoperative to afford a desulfurized gas stream and to produce a loaded absorbent solution, and (f) repeating steps (c) and (d).