Rapport (alle typer) - Danish Gas Technology Centre

DGC-report 125 Gas quality and measurementDifferent issues regarding gas quality and measurements must be addressedas regards a system with a number of biogas producers connected to a numberof consumers by a gas grid.Manure based biogas has a relatively high content of H 2 S, typically between1000 and 4000 ppm in raw biogas. H 2 S both smells and is very corrosive.As the biogas leaves the biogas reactor it has a relatively high temperature(37-52 °C) and it is saturated with water vapor. This leads to formation of anacid condensate as the temperature decreases. All components in the gassystem, which are not made from plastic based materials or stainless steel,might corrode. Furthermore, the high moisture and sulphur content of biogasmeans that it is not simple to measure the amount of biogas produced orconsumed.5.1.1 Experience with a biogas gridFrom 1990 to 2005 around 60 private households were supplied from a biogasgrid in Revninge on Funen. After this period the grid, the meters and thesupplied boilers were examined. It was found that the biogas had made noharm to the biogas grid, but boilers and meters were damaged due to corrosion.5.1.2 Application of biogasBiogas can be applied in different ways. Today, the most common ways areas fuel for gas engines and upgrading to natural gas quality.During upgrading the CO 2 content of the biogas is removed in order to increasemethane concentration and thereby the heating value of the gas.Manufacturers of modern high-efficient gas boilers for households werecontacted and it was found that these boilers are not suited for biogas due tolow and varying heating value and density of biogas.In Denmark, practically the whole biogas production is used for combustionengines without being upgraded. This technology allows high efficienciesand it has the advantage that the engines are only slightly sensitive to variationsin gas quality. The biogas can be applied as fuel for existing natural-