THERMAL SCIENCE

International Scientific Journal

Xuebin Wang

,

Gaofeng Dai

,

Gregory S. Yablonsk

,

Milan Vujanović

,

Richard L. Axelbaum

A KINETIC EVALUATION ON NO2 FORMATION IN THE POST-FLAME REGION OF PRESSURIZED OXY-COMBUSTION PROCESS

ABSTRACT
Pressurized oxy-combustion is a promising technology that can significantly re-duce the energy penalty associated with first generation oxy-combustion for CO2 capture in coal-fired power plants. However, higher pressure enhances the production of strong acid gases, including NO2 and SO3, aggravating the corrosion threat during flue gas re-circulation. In the flame region, high temperature NOx exists mainly as NO, while conversion from NO to NO2 happened in post-flame region. In this study, the conversion of NO → NO2 has been kinetically evaluated under representative post-flame conditions of pressurized oxy-combustion after validating the mechanism (80 species and 464 reactions), which includes nitrogen and sulfur chemistry based on GRI-MECH 3.0. The effects of residence time, temperature, pressure, major species (O2/H2O), and minor or trace species (CO/SOx) on NO2 formation are studied. The calculation results show that when pressure is increased from 1 to 15 bar, NO2 is increased from 1 to 60 ppm, and the acid dew point increases by over 80°C. Higher pressure and temperature greatly reduce the time required to reach equilibrium. With increasing pressure and decreasing temperature, O plays a much more important role than HO2 in the oxidation of NO. A higher water vapor content accelerates NO2 formation in all cases by providing more O and HO2 radicals. The addition of CO or SO2 also promotes the formation of NO2. The NO2 formation in a pressurized oxy-combustion furnace can be over 10 times that of an atmospheric air-combustion furnace.
KEYWORDS
NO2, pressurized oxy-combustion, detailed mechanism, post-flame region
PAPER SUBMITTED: 2020-04-15
PAPER REVISED: 2020-07-31
PAPER ACCEPTED: 2020-08-02
PUBLISHED ONLINE: 2020-09-06
DOI REFERENCE: https://doi.org/10.2298/TSCI200415236W
CITATION EXPORT: view in browser or download as text file
THERMAL SCIENCE YEAR 2021, VOLUME 25, ISSUE Issue 4, PAGES [2609 - 2620]
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A kinetic evaluation on NO2 formation in the post-flame region of pressurized oxy-combustion process

2025 Society of Thermal Engineers of Serbia. Published by the Vinča Institute of Nuclear Sciences, National Institute of the Republic of Serbia, Belgrade, Serbia. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International licence