Economical, safe, unsupervised method for in-vessel regeneration of iron- oxide sponge used in wastewater-treatment-plant digester-gas scrubbers

摘要

In wastewater treatment plants it is conventional to use gas "scrubbers" to remove hydrogen-sulfide gas from digester gas. The reactive scrubbing medium in such digester-gas scrubber vessels is generally iron-oxide "sponge," which is exhausted in use and which is both difficult and dangerous to regenerate. In accordance with the present invention, the spent iron-oxide sponge is immersed in liquid--by filling the scrubber vessel with the liquid--and a regenerating gas is then bubbled through the liquid and the iron-oxide sponge together. The liquid may be water, and the regenerating gas may be air or pure oxygen. The liquid absorbs heat from the regeneration reaction and conducts it out of the iron-oxide medium, eliminating the danger of combustion or explosion without impeding the progress of the reaction. The regenerating gas is applied through a diffuser structure from below. When regeneration is complete the liquid is drained from the vessel, but the flow of gas may be continued until the iron-oxide medium is dry. Scrubber operation may then resume.