Removal of hydrogen sulphide, ammonia from acid water in stripping unit

Refinery acid water is formed in atmospheric and vacuum distillation units, hydrogenation units, hydrocracker, steam and catalytic crackers. Besides hydrogen sulphide the acid water may contain ammonia, carbon dioxide, phenol and cyanides. Such water has to be decontaminated prior to its re-using or drainage. Stripping process is used for this purpose whose substance is to remove dissolved H₂S and NH₃ from water by supplying steam into stripper bottom.

Acid gas (containing hydrogen sulphide, ammonia, steam and other stripped components) is routed from the stripper top to thermal stage of sulphur recovery unit; and stripped water containing less then 50 ppm (by weight) of contaminants is fed for re-using or purification