Experimental investigation of combustion characteristics and NOx formation of coal particles using laser induced breakdown spectroscopy |
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Affiliation: | 1. Mount Holyoke College, Dept. of Astronomy, South Hadley, MA 01075, United States;2. Planetary Science Institute, Tucson, AZ 85719, United States;3. School of Computer Science, University of Massachusetts Amherst, Amherst, MA 01003, United States;1. Department of Mathematics, University of Florida, Gainesville, FL 32611, USA;2. BAM Federal Institute for Materials Research and Testing, Richard-Willstätter-Strasse 11, 12489 Berlin, Germany;1. School of Electric Power of South China University of Technology, Guangzhou 510640, China;2. Guangdong Province Engineering Research Center of High Efficient and Low Pollution Energy Conversion, Guangzhou 510640, China |
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Abstract: | To study the mechanism of coal combustion and NOx formation, the combustion of coal particles in different atmospheres (O2/N2, O2/CO2) with different O2 concentrations was investigated using the CO2 laser as a heat source. The spatial distribution of atoms and groups (e.g., H at 656.2 nm, O at 777.3 nm, CN at 388.3 nm) relating to the combustion flame were measured simultaneously using laser induced breakdown spectroscopy (LIBS). The residual energy was measured during the collection of LIBS spectra in the combustion process, which could be characterized the temperature profiles of combustion flame due to the positive correlation with temperature. The combustion stage could be clearly discriminated by the emission of H and CN, along with the flame temperature. The residual energy obtained in different atmospheres indicated that the impact of combustion atmosphere on flame temperature is greater in the char combustion stage rather than volatile combustion stage. It was determined from the temporal and spatial distribution of residual energy and CN intensity that a higher flame temperature leads to a higher concentration of CN. The correlation between the generation of CN and the NOx formation was also investigated to show that the formation approaches of NOx are similar in the O2/CO2 and O2/N2 atmospheres, while the fuel-N conversion paths are different between volatile combustion and char combustion stages. The measurement of temporal and spatial distributions of LIBS spectra with varying flame temperatures is significant in revealing the mechanism of coal-particle combustion and NOx formation. |
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Keywords: | Coal particles LIBS Flame temperature |
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