Biogas from anaerobic industrial wastewater treatment plants contains 60-85% methane and is a valuable energy source. The remaining part of the gas is made up of CO2 and H2S.
Biogas is mostly used as fuel for a factory steam boiler. Most steam boilers are operating with one fuel – light or heavy oil, or natural gas (or coal) – and can be converted into a dual fuel system, using biogas simultaneously in addition to the primary fuel. When not used for steam production the biogas energy may be recovered in an appropriate CHP unit producing electricity.

In ever fewer cases the biogas is not used for energy recovery but flared off entirely.

In case of use in a boiler the biogas may need to be desulfurized. This depends on the amount of H2S in the biogas, the type of burner and the assessment that is made on the purpose it serves or because of emission limits.

For CHP units it is in almost any case necessary to desulfurize the gas prior to use. When burnt in a gas engine hydrogen sulphide can condense with water to form sulphuric acid. Sulphuric acid is corrosive to elements of gas engines and so must be limited to prevent adverse effects on the CHP engine.
Even if the biogas is entirely flared off it may be necessary to first reduce its sulfur content to comply with emission limits.

For each case GWE can supply the appropriate solution through its SULFURIX and BIO-SULFURIX range of products that efficiently eliminate H2S in the biogas. Further biogas polishing in an activated carbon filter can be offered by GWE as well.

In addition to the sulfur content, in case the biogas is used as fuel in electrical power generators, there are limits imposed on the humidity of the biogas at the inlet of the engines (usually 70 – 80%), in order to avoid damage to the engines. For this purpose GWE developed the GASODRIX™ biogas drier package unit.

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