Modern-Day CanariesMarch 28, 2007 By: Melanie Martella, Sensors Sensors
THE CHALLENGE: Spot methane in a landfill-gas generating plant
When garbage in landfills decays, it produces methane. This is handy if you're interested in tapping it and using it to generate electricity, but it's not so great if it builds up in the areas where people work.
A landfill-gas generating plant in suburban Minneapolis uses wellholes bored into the garbage and laced together into a gas-collection network to transport methane to generators, which, in turn, feed electricity to the regional power grids.
Rather like miners using canaries to check for firedamp, the plant uses IR hydrocarbon detectors from Sensor Electronics Inc. to check for the presence of methane in the engine and control rooms. Each detector incorporates two sensors; one tuned to an IR frequency to detect methane and the other tuned to a different IR frequency to act as a reference. Continually comparing the two signals allows the detector to show the actual percentage of methane present. As an added bonus, the device has self-correcting circuitry and internal diagnostics to keep it happy and healthy and compensates for moisture by automatically shifting the IR signal to one not affected by vapor or condensation.
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