Internal association between combustion behavior and NOx emissions of pulverized coal MILD-oxy combustion affected by adding H2O

Zhenghong Zhao, Zewu Zhang, Xiaojian Zha, Ge Gao, Xiaoshan Li, Fan Wu, Cong Luo and Liqi Zhang

Energy, 2023, vol. 263, issue PD

Abstract: In practical pulverized coal Moderate or Intense Low-oxygen Dilution oxy-fuel combustion (MILD-oxy) process, the accumulation of steam results in the recycled flue gas consisting of highly concentrated H2O, particularly under wet flue gas recirculation. This work numerically studies the individual effect of H2O on the turbulence-chemistry interaction, aiming at revealing the internal association between combustion behavior and NOx emissions. Results show that H2O addition reduces the flame temperature by enhancing the radiative heat transfer. The extremum values of turbulent Damkӧhler number (Dat,max) and Karlovitz number (Kamin) are reduced and increased, respectively, denoting the slow-chemistry feature (Dat < 10 and Ka >> 1) in the reaction zone. With the promoted H2O level, the heterogeneous reactions on the char surface tend to be governed by kinetics due to the reduced reaction rate under low flame temperature. The gasification reaction is enhanced to produce more synthesis gas, and the burnout of char particle is prolonged. The in-furnace NO formation is inhibited under low Dat,max, while the NOx emissions are reduced directly due to the enhanced gasification reaction under low maximum surface Damkӧhler number (Das,max). The addition of H2O essentially establishes a moderate diffusion and reaction process under the kinetics-controlled regime to obtain the uniform thermal field and low-NOx emissions.

Keywords: MILD-oxy combustion; H2O addition; Damkӧhler number; Gasification reaction; NOx emissions (search for similar items in EconPapers)
Date: 2023
References: View references in EconPapers View complete reference list from CitEc
Citations: View citations in EconPapers (1)

Downloads: (external link)
http://www.sciencedirect.com/science/article/pii/S0360544222027645
Full text for ScienceDirect subscribers only

Related works:
This item may be available elsewhere in EconPapers: Search for items with the same title.

Export reference: BibTeX RIS (EndNote, ProCite, RefMan) HTML/Text

Persistent link: https://EconPapers.repec.org/RePEc:eee:energy:v:263:y:2023:i:pd:s0360544222027645

DOI: 10.1016/j.energy.2022.125878

Access Statistics for this article

Energy is currently edited by Henrik Lund and Mark J. Kaiser

More articles in Energy from Elsevier
Bibliographic data for series maintained by Catherine Liu ().