Experimental study on NO emission and ash deposition during oxy-fuel combustion of high-alkali coal under oxygen-staged conditions. (15th July 2022)

• Record Type: Journal Article
• Authors: Wang, Chang'an; Zhao, Lin; Sun, Ruijin; Zhou, Lei; Jin, Liyan; Che, Defu
• Is Part Of: Energy. Volume 251(2022)
• Publication Date: 2022-07-15
• Subjects: Zhundong coal -- Oxygen-staged combustion -- NO emission -- Ash deposition -- Coupling relationship; Power resources -- Periodicals; Power (Mechanics) -- Periodicals; Energy consumption -- Periodicals; 333.7905
• DOI: 10.1016/j.energy.2022.123875
• Languages: English
• ISSNs: 0360-5442

Abstract

Abstract: The oxygen-staged combustion is an effective strategy to reduce NO emission, but its effects on ash deposition in oxy-fuel combustion of Zhundong high-alkali coal still remain unclear. This paper simultaneously focused on the NO emission and ash deposition during the oxygen-staged oxy-fuel combustion of Zhundong coal using a vertical two-stage furnace system. The air- and oxygen-staged combustion were compared and the impacts of oxygen content and stoichiometric ratio in primary zone ( SR 1 ) in oxygen-staged combustion were further evaluated. The results show that compared to air-staged combustion, the oxygen-staged case in oxy-fuel combustion leads to smaller conversion ratio of fuel-N to NO ( X NO ) and smaller mass of ash deposit. Under oxygen-staged conditions, both the X NO and deposit mass have an upward trend as the oxygen content increases (15%–50%). About 20 mg more ash could be collected for every 10% increase in oxygen content. The X NO increases when SR 1 gets elevated from 0.5 to 1.2, however, the deposit mass exhibits a downtrend at SR 1 ≤ 0.9 and becomes nearly independent of oxygen supply when the SR 1 further increases. The SR 1 of 0.9 is a reasonable choice, and some measures should be taken to alleviate the ash-related problems if smaller SR 1 is needed. Highlights: NO emission and ash deposition of high-alkali coal were simultaneously emphasized. Different oxygen-staged conditions of oxy-fuel combustion were investigated. Oxygen-staged combustion is superior to air-staged combustion in present study. Higher O2 content increases both the NO emission and ash deposition. The deeply oxygen-staged combustion reduces NO but worsens the ash deposition.