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Detection Of Smoldering Combustion Of Coal With An Odor Meter

A commercially available odor meter was e valuated as a detector of smoldering coal combustion, and compared with incipient carbon monoxide (CO) and hydrogen sulfide (H /sub 2/S) detection and a commercially available ionization-type smoke detector. Ten smoldering coal combustion experiments were conducted. For eight of the experiments, Pittsburgh seam coal with an average particle diameter of approximately 5 cm was heated by embedded electrical strip heaters. For two of the experiments mine size Pittsburgh seam coal was heated. Heating rates of 0.5, 0.8, and 1.1 kw were selected to provide experimental conditions characteristic of very slow and moderately fast heating for coal sample mass between 3 and 10 kg. It was found that the odor meter and smoke detector alarm had a good correlation, with the odor meter alarm occurring prior to the smoke alarm in four of the ten experiments. The odor meter gave an increase in its output signal above ambient equivalent to detecting I ppm of H/sub 2/S (ten times the odor threshold of H/sub 2/5) as an alarm value. This observed odor meter response occurred prior to the electrochemical detection of H/sub 2/S for five of the six experiments for which it was evaluated. In all six experiments for which the smoke optical density was evaluated, it was less than 0.023 m/sup -1/ prior to the odor meter reaching alarm. In each of the eight experiments with 5 cm diameter coal particles the CO exceeded 5 ppm at odor meter alarm, while for the two experiments with mine size coal the CO was less than 3 ppm at odor meter alarm. The odor meter, as tested, is not a significant improvement over smoke and CO detectors. Because the odor meter responds to a variety of chemical compounds, with suitable modification and increased sensitivity it may be useful for detection of mine fires and thereby enhance mine safety.