The sulfur recovery unit receives feed from the amine unit and the sour water stripper and converts the hydrogen sulfide into liquid sulfur. A sketch of the process is shown below. The unit also destroys the ammonia and hydrocarbons in the feed and converts them into nitrogen, water vapor and carbon monoxide and carbon dioxide.
The amine acid gas and the sour water stripper acid gas feeds are partially combusted in the thermal reactor and some sulfur is produced. The process gas is cooled in the boiler and then in the sulfur condenser. Sulfur is condensed and removed in the sulfur condenser. The remaining process gas is then sent through three catalytic reactor stages where additional sulfur is produced. Each catalytic stage consists of a reheat exchanger, a catalytic reactor and a sulfur condenser. The sulfur produced in the catalytic reactor is condensed and removed in the sulfur condensers. The effluent from the SRU is sent to the tail gas unit for additional processing.