Integrated process for treating refinery waste water containing ammonia and hydrogen sulphide and refinery exhaust acid gas containing hydrogen sulphide

摘要

A process for treating refinery waste water mainly containing hydrogen sulphide and ammonia in addition to acid gases effluent mainly containing hydrogen sulphide said process comprising the following steps: a) stripping in the stripping tower (100) said waste water (1) at a pressure ranging from 8 to 20 bar g in order to produce a gaseous overhead stream (2) essentially containing hydrogen sulphide and water and a liquid bottom stream (4) essentially containing aqueous ammonia; b) stripping in a second stripping tower (110) the stream (4) at 1 to 3 bar g in order to produce a gaseous overhead stream (5 11) of ammonia essentially pure on dry basis and a liquid bottom stream (6) containing less than 1 ppm of hydrogen sulphide and less than 5 ppm of ammonia said water composition having the requirements to be discharged into the sewer; c) oxidation on oxidizer deficiency to nitrogen and water of the ammonia contained in the stream (11) in the thermal oxidation unit (170) to produce an outlet stream (12) containing 50 150 ppm in volume of ammonia and 80 200 ppm in volume of nitrogen oxides; d) thermal oxidation of the stream (12) in the thermal oxidiser unit (160).