Treatment of a water stream containing ammonium sulfide salts

Abstract

Abstract A water stream containing NH4HS is treated to produce elemental sulfur, an ammoniacal aqueous stream and a treated water stream by the steps of: (a) catalytically treating the water stream with an airstream to produce an effluent stream containing ammonium polysulfide, N2 and unreacted NH4HS; (b) separating the effluent stream from step (a) into a vent gas stream and a water stream; (c) decomposing the polysulfide contained in the water stream from step (b) to produce a vapor stream and a bottom stream containing elemental sulfur; (d) separating sulfur from the bottom stream from step (c) to form a treated water stream; (e) recovering a first portion of the treated water stream from step (d) as a product stream; (f) using a second portion of the treated water stream from step (d) to scrub the vent gas stream from step (b) in order to remove NH3 and H2S therefrom; (g) fractionating the overhead vapor stream from step (c) and the bottom stream from the scrubbing step to form an ammoniacal aqueous overhead stream and an aqueous bottom stream containing essentially all of the unreacted sulfide present in the effluent stream from the treating step; and, (h) recycling the bottom stream from step (g) to step (a). Key feature is the use of a scrubbing step on the vent gases from the treating step operated at a relatively low pressure and a relatively high-liquid gas loading, coupled with a combination scrubbing and fractionating step on the bottom stream from the scrubbing step and on the vapor stream from the polysulfide decomposition step. This combination scrubbing and fractionating step is operated at a relatively high pressure, thereby increasing the amount of H2S that can be absorbed. The principle advantages of the resulting process are significant improvements in the amount of ammonia and sulfur recovered and a substantial simplification of the overall process.

Inventors

• 👤 Robert J J Hamblin

Bibliographic Details