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Fully-resolved simulations of volatile combustion and NOx formation from single coal particles in recycled flue gas environments

Shamooni, Ali ; Stein, Oliver T. ; Kronenburg, Andreas ; Kempf, Andreas M. ; Debiagi, Paulo ; Li, Tao ; Dreizler, Andreas ; Böhm, Benjamin ; Hasse, Christian (2022)
Fully-resolved simulations of volatile combustion and NOx formation from single coal particles in recycled flue gas environments.
In: Proceedings of the Combustion Institute, 2022
doi: 10.1016/j.proci.2022.07.034
Artikel, Bibliographie

Kurzbeschreibung (Abstract)

The interaction of coal particles and recycled/recirculated flue gas (RFG) with elevated temperatures and low levels of oxygen occurs in various pulverised coal combustion scenarios. In this work, the effect of oxygen level and temperature on single coal particle combustion characteristics and NO formation in N2 diluent is studied by means of fully-resolved particle simulations. Comprehensive gas-phase kinetics are utilised to consider the critical pathways of NO formation including tar-N. Results show that higher RFG temperatures decrease the time to reach the peaks of temperature and species profiles and increase the corresponding peak values. When decreasing O2, irrespective of the RFG temperature, the fuel release period is prolonged, the volatile combustion time increases and the combustion process becomes overall less intense. The reduction of O2 in RFG results in a significant decrease of NO production, while the reduction of the RFG temperature has a smaller effect. The analysis of the key reactions that contribute to NO production in the region around stoichiometry shows that fuel-NO is the major contributor. Both NH3 and HCN in fuel-N play a major role, while tar-N only contributes in the case with the lowest temperature and O2 concentration. The classical NO formation pathways are negligible and the initiation reaction of the Zeldovich mechanism is even reversed, i.e. is dominant and contributes to NO destruction. The destruction of NO mainly occurs in a rich region close to the particle surface where abundant tar species and their derivatives play a major role for NO destruction via the re-burn mechanism. The prompt mechanism is also active in this region and eventually contributes to NO reduction via production of HCN which is the feed to the re-burn mechanism.

Typ des Eintrags: Artikel
Erschienen: 2022
Autor(en): Shamooni, Ali ; Stein, Oliver T. ; Kronenburg, Andreas ; Kempf, Andreas M. ; Debiagi, Paulo ; Li, Tao ; Dreizler, Andreas ; Böhm, Benjamin ; Hasse, Christian
Art des Eintrags: Bibliographie
Titel: Fully-resolved simulations of volatile combustion and NOx formation from single coal particles in recycled flue gas environments
Sprache: Englisch
Publikationsjahr: 1 Oktober 2022
Verlag: Elsevier
Titel der Zeitschrift, Zeitung oder Schriftenreihe: Proceedings of the Combustion Institute
Jahrgang/Volume einer Zeitschrift: 2022
DOI: 10.1016/j.proci.2022.07.034
Kurzbeschreibung (Abstract):

The interaction of coal particles and recycled/recirculated flue gas (RFG) with elevated temperatures and low levels of oxygen occurs in various pulverised coal combustion scenarios. In this work, the effect of oxygen level and temperature on single coal particle combustion characteristics and NO formation in N2 diluent is studied by means of fully-resolved particle simulations. Comprehensive gas-phase kinetics are utilised to consider the critical pathways of NO formation including tar-N. Results show that higher RFG temperatures decrease the time to reach the peaks of temperature and species profiles and increase the corresponding peak values. When decreasing O2, irrespective of the RFG temperature, the fuel release period is prolonged, the volatile combustion time increases and the combustion process becomes overall less intense. The reduction of O2 in RFG results in a significant decrease of NO production, while the reduction of the RFG temperature has a smaller effect. The analysis of the key reactions that contribute to NO production in the region around stoichiometry shows that fuel-NO is the major contributor. Both NH3 and HCN in fuel-N play a major role, while tar-N only contributes in the case with the lowest temperature and O2 concentration. The classical NO formation pathways are negligible and the initiation reaction of the Zeldovich mechanism is even reversed, i.e. is dominant and contributes to NO destruction. The destruction of NO mainly occurs in a rich region close to the particle surface where abundant tar species and their derivatives play a major role for NO destruction via the re-burn mechanism. The prompt mechanism is also active in this region and eventually contributes to NO reduction via production of HCN which is the feed to the re-burn mechanism.

Fachbereich(e)/-gebiet(e): 16 Fachbereich Maschinenbau
16 Fachbereich Maschinenbau > Fachgebiet Simulation reaktiver Thermo-Fluid Systeme (STFS)
DFG-Sonderforschungsbereiche (inkl. Transregio)
DFG-Sonderforschungsbereiche (inkl. Transregio) > Transregios
DFG-Sonderforschungsbereiche (inkl. Transregio) > Transregios > TRR 129 Oxyflame - Entwicklung von Methoden und Modellen zur Beschreibung der Reaktion fester Brennstoffe
16 Fachbereich Maschinenbau > Fachgebiet Reaktive Strömungen und Messtechnik (RSM)
Hinterlegungsdatum: 10 Okt 2022 06:23
Letzte Änderung: 10 Okt 2022 06:23
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