H2S in atmospheric and vacuum distillation
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Hello everyone. As the title suggests, where does H2S come from in atmospheric and vacuum distillation? What methods are currently used for removal? Thank you.
A small portion is present in the crude oil, while another portion is generated as a result of the decomposition of sulfides during high-temperature distillation in atmospheric or vacuum distillation columns. H2S is generally distilled off from the top of the tower during the distillation process; some of it goes into the acidic water and is sent to the sulfur recovery unit, while another portion ends up in the light hydrocarbon fractions and is used in the light hydrocarbon recovery unit for desulfurization.
It originates from crude oil; part of it is sent out as a product, part ends up in sulfur-containing wastewater, and part enters other devices or air intake cabinets via screw compressors
Sulfur corrosion: In high-sulfur crude oils with temperatures ranging from 260 to 350°C, the sulfides of active components decompose into hydrogen sulfide; this process is primarily characterized by high-temperature corrosion caused by hydrogen sulfide. High-temperature corrosion by hydrogen sulfide is difficult to occur at low sulfur contents and temperatures above 350°C. When the temperature is in the range of 350–400°C, hydrogen sulfide decomposes easily at these temperatures to form elemental sulfur, which then reacts with iron metal to produce ferrous sulfide. After electrodesalting, the residual inorganic salts in the crude oil are carried along with water to the distillation tower, where they hydrolyze into HCl at a certain temperature; H2S is produced from hydrogen sulfide present in the crude oil as well as from the decomposition of sulfides in it. The HCl and sulfides produced are thermally decomposed to yield H2S, which then enters the top of the distillation tower and the condensation cooling system along with the volatile oil gases. When in a dry state, HCl and H2S do not corrode metals; however, when they contain water and droplets of condensation form in the tower top condensing cooling system, they dissolve in the water to form hydrochloric acid.