Landfill Gas Recovery

What is landfill gas?

Landfill Gas is colorless and flammable. It's produced by the action of methane-creating bacteria on biodegradable materials in an anaerobic (air-less) environment. This type of environment occurs naturally in a covered landfill. The typical landfill gas composition is: 50%-70% Methane, 30%-40% Carbon Dioxide, 5%-10% Hydrogen, 1%-2% Nitrogen with traces of Water vapor, and H2S.

Uses for landfill gas include…

Landfill gas can be used in place of natural gas and propane used for motor fuel, home heating, microturbine power generating stations, or fuel cells once properly treated. The user can flare the gas or release it to the atmosphere.

Compressor application…

A Landfill Gas Recovery system consists of extraction wells or horizontal trenches carefully placed throughout the landfill site. The landfill gas is collected from the extraction wells or horizontal trenches dug into the landfill site. As the gas is recovered, it is pulled through a liquid knockout trap using a reciprocating gas compressor and distributed to a main collection header where it is treated for use downstream or flared.

A reciprocating gas compressor is the best option…

Corken’s Reciprocating Compressors, placed on pre-engineered mountings are used for collecting the landfill gas from the gas connection of the landfill and increasing the pressure of the gas to a usable amount based on the customer’s needs. Rotary vane and lobe style compressors can be used on low differential pressure applications. Most users need discharge pressures range from 50 to 75 psig when used for microturbines to 4,000 psig in motor fuel applications. Vane and lobe style units cannot produce the higher discharge pressures needed by most users since the gas is collected at very low pressure. The gas should be scrubbed or filtered before use, especially if there is H2S present.

Materials of construction include…

Ductile iron construction with PTFE elastomers and aluminum gaskets is common. Most applications start with a D-Style (double packed) Oil-free Compressor; however, a T-Style triple packed oil-free compressor is recommended when H2S is present in the gas mix. A MC1002 corrosion and wear-resistant coating may be needed if there is corrosive gas in the mixture. Individual users may have specific requirements indigenous to their application.