FIXED BED METHANATION OF BIOGENEOUS SYNGAS – IDEAS FOR THE DECENTRALIZED APPROACH

摘要

In order to develop SNG-production systems for small scale decentralized applications a methanationtest system was erected at TU-Graz. This bench scale system consists of an allothermal gasifier connected with amethanation test rig. This test-rig combines catalytic methanation with catalytic reforming of high hydrocarbons inone fixed bed reactor. For the removal of particles, alkali-metal components and sulphur impurities, separate devicesare used. A challenge for this in-situ tar reforming within the process of methanation is the reactor’s heatmanagement. With a polytrophic axial temperature control, temperature-peaks of around 500℃ can be reached. Thereason for this rise in temperature is the reaction enthalpy released by the exothermic methanation reaction. Withappropriate reactor cooling, off-gas temperatures of around 300℃ are possible. According to literature, temperaturesin the range of the peak-temperatures are sufficient for tar-reforming. The gas temperature on the reactor’s exhaustallows gas-compositions with a high methane yield. In order to achieve a high efficient SNG-production, the steaminput, necessary for gasification, must be minimized. In this context it has to be considered, that with low steamcontents carbon depositions on the methanation catalyst occur.