The reduction of recycled-NOx in coal combustion with O2/recycled flue gas under low recycling ratio

Hu, Yujin; Kobayashi, Nobusuke; Hasatani, Masanobu

doi:10.1016/s0016-2361(01)00048-5

Cited by 82 publications

(37 citation statements)

References 11 publications

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“…They observed that NO X emissions decreased with recycled flue gas flow rate, but this was only a slight effect. This trend is opposite to that reported by Hu et al (2001) from experiments at much lower recycling ratio. These two results indicate that there may be an optimum level of recycling (or oxygen concentration) for minimum NO X .…”

Section: Review Of No X Formation In Oxy-combustioncontrasting

confidence: 99%

“…Hu et al (2001) studied the reduction of recycled NO and NO 2 in a high-volatile bituminous coal flame under low recycling ratio (high O 2 concentration in the oxidizer). Less recycled NO was reduced when oxygen concentrations were higher which according to their discussion may be due to consumption of CH fragments by the high O 2 concentration leaving less CH fragments for NO reduction.…”

Section: Review Of No X Formation In Oxy-combustionmentioning

confidence: 99%

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A Mechanistic Investigation of Nitrogen Evolution and Corrosion with Oxy-Combustion

Tree

Mackrory²,

Fletcher³

2008

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A premixed, staged, down-fired, pulverized coal reactor and a flat flame burner were used to study the evolution of nitrogen in coal contrasting differences in air and oxy-combustion. In the premixed reactor, the oxidizer was staged to produce a fuel rich zone followed by a burnout zone. The initial nominal fuel rich zone stoichiometric ratio (S.R.) of 0.85 selected produced higher NO reductions in the fuel rich region under oxy-combustion conditions. Air was found to be capable of similar NO reductions when the fuel rich zone was at a much lower S.R. of 0.65. At a S.R. of 0.85, oxy-combustion was measured to have higher CO, unburned hydrocarbons, HCN and NH 3 in the fuel rich region than air at the same S.R. There was no measured difference in the initial formation of NO. The data suggest devolatilization and initial NO formation is similar for the two oxidizers when flame temperatures are the same, but the higher CO 2 leads to higher concentrations of CO and nitrogen reducing intermediates at a given equivalence ratio which increases the ability of the gas phase to reduce NO. These results are supported by flat flame burner experiments which show devolatilization of nitrogen from the coal and char to be similar for air and oxy-flame conditions at a given temperature. A model of premixed combustion containing devolatilization, char oxidation and detailed kinetics captures most of the trends seen in the data. The model suggests CO is high in oxy-combustion because of dissociation of CO 2 . The model also predicts a fraction (up to 20%, dependent on S.R.) of NO in air combustion can be formed via thermal processes with the source being nitrogen from the air while in oxy-combustion equilibrium drives a reduction in NO of similar magnitude. The data confirm oxy-combustion is a superior oxidizer to air for NO control because NO reduction can be achieved at higher S.R. producing better char burnout in addition to NO from recirculated flue gas being reduced as it passes back through the flame.4

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Section: Review Of No X Formation In Oxy-combustioncontrasting

confidence: 99%

Section: Review Of No X Formation In Oxy-combustionmentioning

confidence: 99%

A Mechanistic Investigation of Nitrogen Evolution and Corrosion with Oxy-Combustion

Tree

Mackrory²,

Fletcher³

2008

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“…This could conceivably have implications for the oxidation of fuel-nitrogen to NO or N 2 in solid fuel combustion. Results for NO x in oxy-fuel combustion reported in literature [1,[5][6][7] were obtained in semi-industrial scale, with coal as fuel. These results indicate that oxy-fuel combustion leads to an overall reduction in NO x , compared to conventional combustion.…”

Section: Introductionmentioning

confidence: 99%

Ammonia chemistry in oxy-fuel combustion of methane

Mendiara

Glarborg

2009

Combustion and Flame

379

223

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“…The values of R NH3 , R H2 and R CO are 5.7wt%, 9.4wt% and 15.8wt%, respectively. The NO x reduction ratio in the coke combustion with recycling flue gas is about 16wt%, which approaches to the denitrification ratio in coal combustion with recycling flue gas [19]. The NO x reduction ratio in the coupling combustion with recycling flue gas is higher than that in the coupling combustion and in coke combustion with recycling flue gas.…”

Section: No X Reduction Ratio In Rccrfmentioning

confidence: 81%

NO x reduction by coupling combustion with recycling flue gas in iron ore sintering process

Chen

Guo

2011

Int J Miner Metall Mater

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A new process called 'NO x reduction by coupling combustion with recycling flue gas (RCCRF)' was proposed to decrease NO x emission during the iron ore sintering process. The simulation test of NO x reduction was performed over sintered ore and in the process of coke combustion. Experimentally, NO x reduction was also carried out by sintering pot test. For sintered ore, the amount of NO x emission is reduced by 15wt%-25wt% at 400-550ºC using 2.0vol% H 2 or 2.0vol% CO, or reduced by 10wt%-30wt% at 560-720ºC using 0.15vol% NH 3 . NO x reduction is around 10wt% by coupling combustion of pyrolysis gas and coke, or around 16wt% by recycling flue gas into coke combustion. By RCCRF, the maximum NO x reduction ratio is about 23wt% in coke combustion experiment and over 40wt% in sintering pot test.

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The reduction of recycled-NOx in coal combustion with O2/recycled flue gas under low recycling ratio

Cited by 82 publications

References 11 publications

A Mechanistic Investigation of Nitrogen Evolution and Corrosion with Oxy-Combustion

A Mechanistic Investigation of Nitrogen Evolution and Corrosion with Oxy-Combustion

Ammonia chemistry in oxy-fuel combustion of methane

NO x reduction by coupling combustion with recycling flue gas in iron ore sintering process

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