Scrubbing reduced sulphur compounds in noncondensible gases using white liquor

Field and laboratory studies were conducted to determine the concentrations of Total Reduce Sulphur (TRS) compounds in Noncondensible Gases (NCGs) and the efficiency of a NCG scrubber using white liquor; and to examine the mechanism that governs the effectiveness of CH3SH absorption into white liquor. Results show depending on the sources, NCGs contained 3 to 18% TRS on a dry basis. Of the TRS, CH3SH accounted for approximately 50%, H 2S and CH3SCH3 about 25% each, and CH3SSCH 3 less than 2%. H2S and CH3SH were effectively removed by the scrubber but not CH3SCH3 and CH 3SSCH3. The absorption of CH3SH into water was a mass-transfer controlled process with Ea = 22 kJ/mol. The absorption into alkaline solutions was accelerated by chemical reactions. Oxygen played an important role in CH3SSCH3 formation. These findings help improve NCG scrubber design and operation.