Autogenerative high pressure digestion: anaerobic digestion and biogas upgrading in a single step reactor system

摘要

Conventional anaerobic digestion is a widely applied technology to produce biogas fromnorganic wastes and residues. The biogas calorific value depends on the CH4 content whichngenerally ranges between 55 and 65%. Biogas upgrading to so-called ‘green gas’, with naturalngas quality, generally proceeds with add-on technologies, applicable only for biogas flowsn>100 m3/h. In the concept of autogenerative high pressure digestion (AHPD), methanogenicnbiomass builds up pressure inside the reactor. Since CO2 has a higher solubility than CH4, it willnproportion more to the liquid phase at higher pressures. Therefore, AHPD biogas is characterisednby a high CH4 content, reaching equilibrium values between 90 and 95% at a pressure of 3–90 bar.nIn addition, also H2S and NH3 are theoretically more soluble in the bulk liquid than CO2. Moreover,nthe water content of the already compressed biogas is calculated to have a dew point