A laser-induced breakdown spectroscopy (LIBS) technique has been applied for detection of unburned carbon in fly ash, and an automated LIBS unit has been developed and applied in a 1000-MW pulverized-coal-fired power plant for real-time measurement, specifically of unburned carbon in fly ash. Good agreement was found between measurement results from the LIBS method and those from the conventional method (Japanese Industrial Standard 8815), with a standard deviation of 0.27%. This result confirms that the measurement of unburned carbon in fly ash by use of LIBS is sufficiently accurate for boiler control. Measurements taken by this apparatus were also integrated into a boiler-control system with the objective of achieving optimal and stable combustion. By control of the rotating speed of a mill rotary separator relative to measured unburned-carbon content, it has been demonstrated that boiler control is possible in an optimized manner by use of the value of the unburned-carbon content of fly ash.
Effective prevention from the leakage of Polychlorinated Biphenyls (PCBs) requires the rapid analysis with on-line detection, but conventional methods require extensive analytical time (several days per sample) and are thus unsuitable. The objective of the research reported here was to develop the Laser Ionization / Ion Trap Storage / Time of Flight Mass Spectrometry (LI-IT-TOFMS) capable of monitoring PCBs within 1 min/sample, as applied to exhaust gas and the atmosphere of the disposal work environment. The achievable PCBs sensitivity for on-line measurement was found to be in the pptV range (< 0.01 mg/m 3 N) by means of comparison with conventional gas sampling and gas chromatographmass spectrometry (GC-MS). A satisfactory proportional relationship was confirmed between laser-based and conventional results for PCBs. We measured the exhaust gas in a PCBs treatment plant (hydrothermal decomposition and container treatment processes) by using the PCBs monitoring system, confirming that PCBs monitoring is possible without interference from either the main gas composition or minor coexisting substances. Accordingly, the LI-IT-TOFMS method is a useful method for the trace analysis of PCBs in exhaust gas.
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