During the actual operation of sulfur recovery units, catalyst activity is the core factor ensuring stable and efficient operation and high sulfur recovery rate. Accurate judgment of catalyst deactivation helps cut operating costs, avoid production fluctuations and maintain qualified sulfur recovery efficiency. In industrial practice, working parameters including unit sulfur recovery rate, reactor bed pressure drop and bed temperature difference can be combined to identify catalyst deactivation types and activity levels.
1. Distinguish Deactivation Types via Sulfur Recovery Rate and Bed Pressure Drop
The sulfur recovery rate is the most intuitive and critical indicator for evaluating catalyst activity, and catalyst activity decline will directly reduce the unit's sulfur recovery efficiency. Combined with changes in reactor bed pressure drop, temporary and permanent catalyst deactivation can be clearly differentiated.
Temporary catalyst deactivation is mainly caused by reversible short-term factors such as sulfur deposition, carbon accumulation and impurity blockage inside the catalyst bed. Its typical operating feature is a sharp rise in reactor bed pressure drop accompanied by continuous reduction of sulfur recovery rate. If the sulfur recovery rate drops while the bed pressure drop remains stable, permanent catalyst deactivation can be confirmed after eliminating external disturbances from equipment and process operation. Permanent deactivation stems from irreversible causes including active component loss, catalyst sintering and irreversible poisoning, which is more complicated and harder to diagnose than temporary deactivation.
2. Evaluate Catalyst Activity by Bed Temperature Difference
The standard bed height of reactors in sulfur recovery units is about 900 mm. When catalysts perform well, the Claus reaction proceeds at a fast speed and reaches equilibrium within the top 150 mm of the catalyst bed, forming a concentrated effective reaction zone.
Operators can comprehensively analyze the inlet-outlet temperature difference of each reactor and overall bed temperature difference to judge catalyst performance. Intact catalysts trigger intense reactions and concentrated heat release at the upper bed with obvious temperature differences. If catalysts suffer permanent deactivation and weakened activity, the reaction efficiency drops sharply, the reaction zone extends downward and heat disperses evenly. Abnormal variations in reactor inlet-outlet and bed temperature differences can accurately reflect the severity of catalyst deactivation.