Anaerobic microbial degradation of organic substances in biogas facilities produces not only the principal components methane (CH4) and carbon dioxide (CO2), but also hydrogen sulfide (H2S).
Among other things, the hydrogen sulfide concentration in the biogas is dependent on the substrates used, and can range from a few ppm in facilities processing renewable resources to several thousand ppm when fermenting liquid manure, biological waste and food remains.
H2S this is a highly corrosive gas. Sulfur dioxide causes rapid overacidification of the engine oils during combustion in the gas engine. This results in increased wear, frequent bearing damage, higher consumable costs and longer plant downtimes.Moreover, being a catalyst poison, hydrogen sulfide leads to the inactivation of oxidation catalysts. Sulfur contained in the combustion offgas is bound in the catalyst, thus blocking the reactions that should actually take place.
For reliable and trouble free operation CHP unit, it is necessary to do desulfurization. For this purpose, activated carbon system is ideal.
BIOGAS-CONSULT company is a partner of the German company Donau Carbon - a world leader with more than 100 years of history, specializing in the production of activated carbon for the purification of gases, air, odorization, wastewater, liquids, solvent extraction, etc. Activated carbons Donau Carbon are widely used in the production of gold, food and chemical industries.
Donau Carbon has in its arsenal a specialized activated carbon production line - Desorex for the purification of biogas from:- hydrogen sulfide (activated carbon brand Desorex G 50, which is capable of adsorbing up to 45% hydrogen sulfide by weight);- siloxanes (activated carbon brand Desorex K 47, which is capable of adsorbing at least 15% of organosilicon compounds by weight).
Our company is ready to provide customers with the necessary special vessels for filling with activated carbon. This facilitates the replacement of the filler and reduces the downtime of the production process, and also optimizes the maintenance of the desulfurization and desiloxanization sites.
Bioactivated carbon - is a filter material for external desulfurization, which made from organic material - cellulose fibers. Bioactivated carbon demonstrates its high adsorption capacity for hydrogen sulfide due to the impregnation with iron-containing components.
Benefits:- Deep cleaning of biogas from hydrogen sulfide, regardless of peak loads in terms of sulfur and gas flow rate;- Low maintenance;- Bioactivated carbon is able to effectively remove sulfur from biogas saturated with water vapor (100% relative humidity);- Reusable use (simple regeneration in contact with atmospheric oxygen);- It not necessary must be disposed of after reacting with hydrogen sulfide, bekause it is a good fertilizer;- Does not cause corrosive processes.
Dosing of iron compounds
Adding iron compounds to the inside of the bioreactor leads to the deposition of hydrogen sulfide (H2S) as iron sulfide (FeS) in the substrate!
Process technology:FeO + H2S → FeS + H20
Fe2O3 + 3H2S → 2FeS + S + 3H2O
2Fe(OH)3 + 3H2S → Fe2S3 + 6H2O
2FeCl3 + 3H2S → 6 HCl + Fe2S3
Benefits:- Iron compounds are dosed inside bioreactors - there is no need to build additional external communications and additional equipment;- Dissolved hydrogen sulfide binds to iron compounds, precipitates in the form of iron sulfides and is excreted together with the digestate as bio-fertilizer;- High effect of desulfurization; - Low operating costs;- Easy to use method.