Abstract
The necessity of production of energy from waste treatment has increased the capability of existing a/o new establishments for the biogas production. The dangerous elements of the biogas production installation, that may be subject to the Seveso III Directive (2012/18/EU), are tanks (bio-digesters), compression stations and decompression cabins, transfer point and fixed piping. The scope of this works is clarifying how the gas mixture contained within the bio-digesters should be classified, in order to consider the main safety issues for the prevention of major accidents. The biogas is in fact classified flammable gas, with thresholds range more restrictive than thresholds range applied to upgraded biogas, also referred to as biomethane, if it has been processed in accordance with applicable standards for purified biogas. The biogas upgrading and purification process takes place downstream of the digestion tanks and therefore the gas retained by the tank covers is not to be considered purified or upgraded. The gas mixture contained within biodigesters must be classified according to the Regulation (EC) No 1272/2008 on the classification, labelling and packaging of substances and mixtures (CLP Regulation), considering the hazard characteristics of the components of the mixture, not of the methane component only and considering the total quantity of biogas present in the plant, including the hold up of equipment used to transfer the biogas. It is finally possible to indicate some elements for the possible identification of dangers and the evaluation of risk in these installations, characterized by a relative low plant complexity and standardization, based on typical technical literature of the sector.
