Abstract: A biogas cleaning method for purifying a biogas waste stream to form a combustible clean biofuel uses a biogas cleaning system that includes a gas control system, a deoxidizer catalyst bed, a hydrosulfurization catalyst bed, a hydrogen sulfide adsorption bed and a thermal sensor controller. The biogas cleaning method includes using a biogas source to introduce a biogas waste stream into the biogas cleaning system, blending hydrogen with the biogas waste stream, combusting the blended hydrogen and biogas stream to remove oxygen, hydrogenating the heated biogas waste stream to convert sulfur species to hydrogen sulfide and adsorbing the hydrogen sulfide from the biogas stream. In some embodiments, a biogas cleaning system also includes a sulfur polisher adsorption bed, a chlorine removal adsorption bed, a siloxane removal adsorption bed, a heat exchanger loop and a biogas precooler.
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.