This unit strips hydrogen sulphide and ammonia from the sour water to allow its reuse in the process units.
The sour water from the process units is fed to a stripping tower where heat, in the form of steam, is applied. The ammonia and hydrogen sulphide contained in the water is released by the heat and exits the top of the tower. Any excess steam is condensed by cooling the overhead stream and returning the condensate to the tower. The ammonia and hydrogen sulphide gases are directed to the Claus Units where they will be converted to sulphur and nitrogen. The stripped water from the tower bottom is returned to the process units for the reuse. The Waste Water Treatment Facility treats the stripped sour water biologically to remove phenols and other contaminants and enables the treated water to be recycled.
Diagram used with permission (© SAIT Polytechnic, MacPhail School of Energy, 2009)