Dry desulfurization system

biogas

Dry chemical desulphurization is a simple, efficient and low-cost solution for removing Hydrogen Sulfide in biogas, generally suitable for low-flow biogas with low Hydrogen Sulfide content. Main principle is that H2S is oxidized by O2 to sulfur or sulfur oxide, so it is also known as dry oxidation process. The process is structured as a cylindrical container with chemical fillings inside, which are activated carbon or ferric oxide, etc. The raw biogas at low velocity goes through the filling layer, then hydrogen sulfide would be oxidized to sulfur or sulfur oxide, which remains in the filling layer. And the purified biogas flows out of tower at upper position. We call this cylindrical container as tower, material is carbon steel or stainless steel, wall thickness is 4 ~ 10 mm available, diameter varies in the range of 440 ~ 5000 mm, and height of tower is 1.0 ~ 10 meters available. It’s a kind of nonstandard equipment, actual dimension would be subject to gas flow and hydrogen sulfide content in the raw biogas. Main equipment is the steel-structure tower, filled by desulphurizer agent, equipped with observation window, pressure gauge, thermometer and other components. There are usually two towers to be used alternately, one for operation while the other for regeneration. When biogas flows through tower down-up, below chemical reactions would occur: Desulphurization agent (Ferric Oxide): First-step: Fe2O3•H2O + 3 H2S = Fe2S3 + 4 H2O （Desulphurization） Second-step: Fe2S3 + 3/2 O2 + 3 H2O = Fe2O3•H2O + 2 H2O + 3 S（Regeneration）