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Activated carbon desulfurization
Activated carbon desulfurization is one of the common dry desulfurization methods and widely used in fine desulfurization.
Desulfurization Principle: The major mechanism of activated carbon desulfurization is catalytic and adsorption. When the coal gas containing H2S passing through the activated carbon bed, the exothermic reaction occurs under atmospheric pressure and being catalyzed oxidation into sulfur and water on the surface of activated carbon. Its product was adsorbed by activated carbon in order to achieve its purpose of desulfurization.
Regeneration Principle: Put the superheated steam over 400℃ into the activated carbon bed for the resolving of sulfur absorbed on the activated carbon. So that to regenerate the activated carbon for using and recycle the sulfur. But the adsorption capacity of activated carbon will generally decrease with the use of time until lose its service in course of time.
Iron oxide desulfurization
The earliest use of Iron oxide desulfurizer is marsh ore and artificial ferric oxide. In order to increase its porosity, desulfurizer is made by wood chips as filling materials, then spraying appropriate water and little amount of slaked lime and tedding repeatedly. The PH of this kind of desulfurizer is generally about 8~9, it has lower desulfurization rate and has to be regenerated outside the tower, in that case, it will be easily replaced by other desulfurizer . At present, the TF desulfurizer is not only widely used and has high desulfurization rate, but also achieves the tower regeneration.
The iron oxide desulfurization and regeneration reaction are as follows:
(1) Desulfurization Process
2Fe(OH)3+3H2S Fe2S3+6H2O
Fe(OH)3 + H2S 2Fe(OH)2+S+2H2O
Fe(OH)2 + H2S FeS+2H2O
(2) Regeneration Process
2Fe2S2+3O2+6H2O 4Fe(OH)3+6S
4FeS+3O2+6H2O 4Fe(OH)2+4S
The regeneration of Iron oxide desulfurizer is an exothermic process, if it regenerates too fast, the heat release will be intense and desulfurizer is easy to burst into flames, this phenomenon used to happened in many enterprises.
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