Abstract: The analysis indicates that the abnormal phenomena of quench tower, SO2 concentration in flue gas and hydrogenation system during the commissioning of No.2 tail gas treatment system for sulfur recovery is due to the activity decline of the hydrogenation catalyst. It is found that the reason for hydrogenation activity losing is due to the bias current in catalyst bed. Effective measures are then adopted, including sealing part of the reactor entrance opening, adding porcelain ball screen mesh at the top of the catalyst bed and adjusting the operation of the reactor system. The bias current in the catalyst bed is thus controlled effectively and the hydrogenation activity improves significantly by these measures, resulting in smooth operation of the tail gas system of the sulfur recovery unit.

Key words: sulfur recovery, tail gas, hydrogenation, activity decline, bias current