Used 48 TPD Sulfur Recovery Unit (SRU) built in 2005. The SRU is designed to convert primarily H2S acid gases from the Amine Regeneration Unit, Poly Unit, and sour water stripper of a petroleum refinery to elemental sulfur. This is based on controlled combustion with air in which H2S is oxidized to form sulfur dioxide (SO2), elemental sulfur, water vapor, and heat. A catalyst is used to facilitate the continued conversion of SO2 to elemental sulfur in this process. The Tailgas Treating Unit essentially scrubs the combustion gases from the Claus process of SO2 before being emitted to the atmosphere.