Landfill Gas

Process

The methane gas created by the anaerobic process in a waste landfill must be vented to prevent explosions.  The gas may be safely flared off to atmosphere.

Description

This process can use one or multiple Hoffman and Lamson multistage or regenerative centrifugal exhausters.  A single exhauster could draw from twenty or fifty vent pipes; however the vent pipes must be engineered to draw an even vacuum.  Multiple exhausters can make this less of a problem.  Wide flow ranges are experienced.  Holes are bored and piping collects the potentially hazardous methane gas.  A multistage or regenerative centrifugal exhauster encourages the gas mixture, mostly methane gas and carbon dioxide, to leave the landfill and sends it to the landfill gas vent flare.

Gas Composition

Operating Conditions

The airflow varies considerably, but the vacuum required is usually 100-200 “H2O (7.4-14.8 “Hg).

New landfills have a clay base, sand and a membrane designed to prevent leach ate from reaching the groundwater.  Garbage layers are added, compacted mechanically and topped with a layer of soil until the landfill section is deemed full.  The area is then topped with special low permeability soil, a HDPE membrane, more soil and a vegetation cover. 

Hoffman™ and Lamson™ Products

Smaller Hoffman and Lamson series multistage or regenerative centrifugals are great technology solutions for this application and will use packing ring seals, whereas larger exhausters will require carbon ring seals to prevent methane leakage.  Carbon ring seals require purging, so a compressor will need to be nearby. The casing is Heresite coated, and non-sparking coupling guards are used.  Aluminum impellers are acceptable.  A stainless steel shaft is optional.

Lamson TurboTron™ regenerative exhausters can be used in some landfill gas applications with appropriate airflow and vacuum ranges, but they would require a variable frequency drive (VFD) since the TurboTron™ cannot be throttled back like a multistage centrifugal.