Figure 1 shows a simplified Shell Claus Off-gas Treatment (SCOT) tail gas treating unit (TGTU). Tail gas from the Claus sulfur recovery unit (SRU) is heated in an in-line burner before entering the hydrogenation reactor, where all sulfur species are converted to hydrogen sulfide (H2S). Hydrogenation reactor effluent is then cooled by generating low pressure (LP) steam, followed by additional cooling by cooling water exchange. Residual H2S in the cooled tail gas is removed with amine in a counter-current packed absorber. The treated tail gas from the absorber top is incinerated before being vented to the atmosphere. The rich solvent from the amine absorber is pumped to the regenerator after heat exchange against the hot lean solvent from the regenerator. Acid gases are stripped from the solvent in the trayed regenerator via a steam reboiler. The hot lean solvent from the regenerator bottom is pumped back to the absorber after being heat exchanged with rich solvent and cooling water to lower its temperature. Acid gas from TGTU amine regenerator overhead is recycled back to the Claus plant for sulfur recovery.
Syngas Clean Up