Economical And Effective Biogas Process To Purify Alternative Fuels For Power Generation

ABSTRACT
Energy recovery from biogas is becoming more common, but the processes are hampered with the presence of hydrogen sulfide (H2S). Biogas is a mixture of methane and carbon dioxide (CO2) and is often contaminated with toxic quantities of H2S. Sources of biogas are: municipal landfills that produce landfill gas (LFG); wastewater treatment plants; industrial plants; and large scale livestock farms. The H2S levels can range between 200-5000 ppmv from municipal facilities to over 30,000 ppmv from industrial facilities.

H2S has an offensive "rotten egg" odor at concentrations as low as 5 ppbv, and is an acute toxic hazard at concentrations above 100 ppmv. H2S is a health, safety, and environmental hazard, and when combined with CO2 and water vapor, it can corrode boilers, piping, and other equipment. Reducing H2S in biogas reduces sulfur dioxide emissions, equipment corrosion, and fouling. H2S reduction also offers cost savings through lower maintenance requirements, and results in greater energy recovery for increased power generation.

This paper describes a biogas scrubbing process for the removal of H2S and particulate matter from biogas as it is produced. Using a patented, high efficiency gas-liquid contacting process, H 2S is absorbed and the gas is purified for use in power generation facilities, cogeneration facilities, boiler units, and other heating applications. A case history of the scrubbing technology will be presented.