Effect of and Gasifications on the Burning Behavior and NO Release Process of Pulverized Coal at Low Oxygen Concentrations during Oxy-Fuel Combustion
Publication: Journal of Energy Engineering
Volume 145, Issue 2
Abstract
Through the use of a thermogravimetric analyzer and a fixed-bed reactor, the effects of and gasifications on oxy combustion and NO emission of pulverized coal at low oxygen concentrations were investigated by comparing the burning behaviors and NO release processes in , , and mixtures (the latter two represented oxy-fuel combustion without and with steam addition, respectively). The thermogravimetric analyses show that at concentration, the burning rate of coal samples decreased in the order of , , and (molar concentration). As the oxygen concentration dropped to 2% because of the influence of and gasification, the overall reaction rate of coal samples increased in the same order at above 800°C. At 2% concentration, because of the effect of gasification the overall reaction rate of char samples in the mixture was accelerated and exceeded the burning rate in the mixture with increasing temperature. And the overall reaction rate of char samples in further increased due to the enhanced and co-gasification. The fixed-bed reactor tests showed that the NO emissions of pulverized coal in the mixture were always higher than those in the mixture, regardless of temperature and concentration. At 1,000°C and concentration, the NO emission in () was higher than that in () because the additional nitrogen precursors (HCN and ) generated by gasification were oxidized to NO easily and quickly. However, increasing oxygen concentration to 5%, because of the weakened effect of gasification, NO emission in () decreased compared to that in (). In addition, because the effect of gasification was enhanced at 1,200°C, regardless of the concentration, the NO emissions in the mixture were always higher than those in the mixture.
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Acknowledgments
This work was supported by the National Key R&D Program of China (2016YFB0600701), the Hebei Province Natural Science Foundation (E2016502094), and the Fundamental Research Funds for the Central Universities (2017MS120).
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©2019 American Society of Civil Engineers.
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Received: Jul 2, 2018
Accepted: Oct 19, 2018
Published online: Jan 29, 2019
Published in print: Apr 1, 2019
Discussion open until: Jun 29, 2019
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