Using LIBS Measurements for Coal Quality Monitoring and Upgraded Power Plant Control
Laser-induced breakdown spectroscopy (LIBS) has been developed and applied to measure key inorganic components in coal ash such as Si, Al, Fe, Na, Ca, Mg, and K – , which contribute to the slagging and fouling behavior of pulverized coal. A coal inventory was assembled from fuels used at utility boilers with a range of slagging/fouling characteristics. These coals included Eastern US bituminous and sub-bituminous coals and some foreign fuels. These coals were tested in a custom-built LIBS analyzer for ash metal composition and major element concentration (i.e. O, S, N). Detection limits are on the order of 0.01 percent, with variations depending on the particular element and type of coal. Measurement repeatability and accuracy are typically within 10 percent (relative). The elemental analyses were used in concert with a neural network algorithm to calculate a slagging and fouling index for the prediction of deposition behavior. The values of the predicted indices are very similar to the resulting indices from standard coal analysis procedure. A future on-line version of the LIBS system will be installed at a 650 MW coal-fired unit and equipped with expert system-based software to demonstrate the real-time capabilities of this technology to monitor coal ash composition, slagging/fouling prediction and recommend actions to the operators for boiler operation modifications for slagging/fouling mitigation.