Rapid changes in landfill gas quality can damage the engines it powers. To keep watch, Viridor has installed static automatic gas analysis and reporting equipment supplied by Geotech at its Whitehead landfill site near Manchester. Every ten seconds the equipment measures concentrations of CH4, CO2 and O2 and outputs the data in three, 4-20 mA channel signals.
Control circuits receive the analyser signals and are set to shut down the landfill gas (LFG) engine before damage by a fast-changing gas mix. Gas thresholds are set at three percent maximum for O2 with three levels for methane of warning at 55 percent, maximum of 60 percent and a site-variable minimum of 30-40 percent. When reached the LFG engine is automatically shutdown and gas diverted to flare on site. Viridor Whitehead's LFG engine's protection is now totally dependent on its static gas analyser set automatically to sample, analyse and report 8640 times a day, every day. The readings are data logged and provide gas output statistics available via secure internet access for Viridor at any location where there is an Internet connection.
Describing the installation, power plant supervisor, Mark Woollams said, 'Protection of our LFG engines is now totally dependent on the static gas analyser. We ran a pilot and are confident we can depend on it totally to protect our engines from damage.' To ensure gas analyser accuracy an auto-calibration system routinely purges and calibrates the equipment. The data from each auto-calibration is also collected by the data loggers enabling a full verification audit trail for all gas analysis readings and calibrations.