| abstract |
An integrated biogas cleaning system is provided to clean biogas from sources such as landfills and digesters for heat and power generation systems such as boilers, engines, turbines, or fuel cells. Siloxanes, chlorine, oxygen and sulfur are removed to parts per billion levels as well as removing the majority of water and some volatile organic compounds. The biogas system cools a biogas stream to partially remove contaminants, blends in a small concentration of hydrogen gas and then combusts the remaining oxygen to heat the biogas and leave sufficient hydrogen suitable for a downstream sequence of further contaminant conversion and removal in stages using a hydrodesulfurization bed and adsorbent media beds. Heat exchange arrangements provide efficient recycling of waste heat and compensation for varying levels of oxygen in the incoming biogas waste stream, suitable for use in a wide range of biogas generating sources. The resulting biogas fuel product is suitable for use in combustion generators, fuel cell systems, greenhouse boilers, or as feedstock for further upgrading to renewable natural gas. |