Effects of operation parameters on NO emission in an oxy-fired CFB combustor

NO emission during co-firing coal and biomass in an oxy-fuel circulating fluidized bed combustor

“…For biomass, RH has the biggest NO emissions in both air and oxy-fuel combustion due to the highest nitrogen content in it, while WC has the lowest NO emissions because it has only 0.39% nitrogen. Both coal and biomass have lower NO emissions in oxy-fuel combustion compared with their emissions in air combustion, which is consistent with the former studies on coal [10,18]. The probable reason is that CO 2 changes the fuel nitrogen transformation routine during the pyrolysis process [16,19], as well as the enhanced NO reduction by the potential high CO emission [18] in the dense bed.…”

“…Both coal and biomass have lower NO emissions in oxy-fuel combustion compared with their emissions in air combustion, which is consistent with the former studies on coal [10,18]. The probable reason is that CO 2 changes the fuel nitrogen transformation routine during the pyrolysis process [16,19], as well as the enhanced NO reduction by the potential high CO emission [18] in the dense bed. Li and Tan [13,16] has found that CO 2 substituting Ar can suppress HCN and NH 3 formation by consuming the N-sites or H radicals on the char surface, whereas HCN and NH 3 are the main NO precursors during combustion process.…”

“…The adding of coal into biomass provides the nascent char in dense bed and results in higher CO concentration due to the slower burnout characteristic of coal. The char and CO, as reducing agent, will reduce the NO via the char/NO/CO heterogeneous reaction, as we previously found [18]. In oxy-fuel combustion, the interactive effect seems more obvious than in air combustion, again due to the high concentration of CO, which has been demonstrated by Wang et al [21] in a lab scale quartz reactor.…”

“…Li and Tan [13,16] has found that CO 2 substituting Ar can suppress HCN and NH 3 formation by consuming the N-sites or H radicals on the char surface, whereas HCN and NH 3 are the main NO precursors during combustion process. At the same time, taking consideration of the fact [18] that high CO 2 concentration in the primary zone retards the coal combustion as well as the potential occurrence of the CO 2 -char gasification, higher production of CO will occur in oxyfuel combustion, which promotes the char/NO/CO heterogeneous reaction for NO reduction.…”

Sulfur fate during bituminous coal combustion in an oxy-fired circulating fluidized bed combustor

“…9) measurements and has facilities that make it possible to vary parameters independently and in a wide range. The detailed description of the setup can be found elsewhere [19].…”