SNG from biomass - Basics and challenges in process engineering. SNG aus Biomasse - Verfahrenstechnische Grundlagen und Herausforderungen

The observance of local and of technical basic conditions is one of the main subjects associated with designing a SNG (substitute natural gas) plant based on the gasification of biomass feedstock. Amongst others the local basic conditions comprise the kind of biomass to be gasified, its local and seasonal availability, the haul distance of educts and products to and from the gasification plant and above all the possibilities to use the process heat. Mainly dry lignin containing biomass like wood is the most suitable biomass for thermal gasification. For other biomasses, especially for those with a high water content, SNG production by fermentation is preferable. Furthermore, a high energy density of biomass is desirable because the collection and transportation of biomass with a low energy density is coupled with a high consumption of energy. This is one of the main reasons for choosing wood as a feedstrock because its energy density with about 6500 MJ/m3 is much higher than for example for straw with about 1000 MJ/m3. For the technical aspects of gasification the selection of the most suitable gasification process, of the process temperature and the process pressure are determined by the properties of the chosen biomass (e.g. ... mehrwater content, grain size, contents of ash, chlorine, sulphur and of other trace components). Finally all the requirements of the relevant DVGW-regulations (above all of G 260 and G 262) have to be fulfilled.