integrated process for purification of waste water of refinery, principally containing ammonia and hydrogen sulfide, and acid gas containing mainly hydrogen sulfide.

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).