The Sulfur Unit, based on the Claus process, is used to recover elemental sulfur from acid gas streams rich in hydrogen sulfide (H₂S) generated by upstream acid gas removal units. In the thermal stage, a portion of the H₂S is combusted with controlled air in the thermal reactor, forming sulfur dioxide (SO₂) and initiating sulfur formation. The process gas is then cooled in a waste heat boiler and condensers, allowing molten sulfur to be recovered. The remaining H₂S and SO₂ are further converted to elemental sulfur in catalytic converter stages, followed by reheating and condensation. This multi-stage process maximizes sulfur recovery efficiency while reducing sulfur emissions before the tail gas is routed to further treatment or incineration.