Pyrolysis of superfine pulverized coal. Part 3. Mechanisms of nitrogen-containing species formation

Liu, Jiaxun; Jiang, Xiumin; Shen, Jun; Zhang, Hai

doi:10.1016/j.enconman.2014.12.096

Cited by 31 publications

(6 citation statements)

References 48 publications

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“…It is generally believed that there are mainly four nitrogen-containing functional groups in coal, consisting of pyridine-N (N-6), pyrrole-N (N-5), quaternary-N (N-Q), and oxidized-N (N-X). 34 It could be seen in Figure 4 that N-5 was the main nitrogen-containing functional group in the fuel. Referring to the results of nitrogen balance calculation, the amounts of these nitrogen-containing functional groups in the fuel all decreased after the preheating, especially, instable N-X decreased most.…”

Section: Resultsmentioning

confidence: 98%

“…Furthermore, X-ray photoelectron spectroscopy (XPS) was used to analyze the distribution of nitrogen-containing functional groups in the preheated char particles. It is generally believed that there are mainly four nitrogen-containing functional groups in coal, consisting of pyridine-N (N-6), pyrrole-N (N-5), quaternary-N (N-Q), and oxidized-N (N-X) . It could be seen in Figure that N-5 was the main nitrogen-containing functional group in the fuel.…”

Section: Resultsmentioning

confidence: 99%

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Low NO_x Emissions from Pulverized Coal Moderate or Intense Low-Oxygen Dilution Combustion in O₂/CO₂ Preheated by a Circulating Fluidized Bed

et al. 2018

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This work reports a newly preheated system with pulverized coal oxy-fuel moderate or intense low-oxygen dilution (MILD) combustion for low NO x emissions. During the experiment, high-temperature fuel preheated by a circulating fluidized bed unit would burn out in a down-fired combustor. This preheating process of pulverized coal tended to form a strong reducing atmosphere and promoted the fuel temperature above the ignition temperature, which contributed to NO x reduction and MILD combustion formation. During the oxy-fuel MILD combustion process, the CO2 concentration of flue gas reached approximately 95%, the NO2 and N2O emissions were nearly zero, and the NO emissions were 107.99 mg/MJ. The combustion efficiency was 98.21%, which indicates that the combustion efficiency would not decrease in MILD combustion. Also, NO emissions were further reduced to 37.25 mg/MJ through a rational arrangement of tertiary gas positions. For pulverized coal combustion, the accurate definition of MILD combustion should consider the disappearance of flame front besides the feature of temperature distribution.

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Section: Resultsmentioning

confidence: 98%

Section: Resultsmentioning

confidence: 99%

Low NO_x Emissions from Pulverized Coal Moderate or Intense Low-Oxygen Dilution Combustion in O₂/CO₂ Preheated by a Circulating Fluidized Bed

et al. 2018

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“…The literature has explored the effect of coal particle size on pyrolysis and gasification characteristics [1,[11][12][13]. Liu et al [14][15][16][17] conducted a systematic study of coal pyrolysis characteristics including formation mechanisms of methane, carbon monoxide, nitrogen-containing species, and functionalities in chars using samples with different particle sizes. It was found that the coal particle size influenced the sulfur release behavior by Krishnamoorthy et al [18].…”

Section: Introductionmentioning

confidence: 99%

Gasification of Shenhua Bituminous Coal with CO2: Effect of Coal Particle Size on Kinetic Behavior and Ash Fusibility

Zhang¹,

Wang²,

Zhao³

et al. 2020

Energies

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Coal gasification is the process that produces valuable gaseous mixtures consisting primarily of H2 and CO, which can be used to produce liquid fuel and various kinds of chemicals. The literature shows that the effect of particle size on coal gasification and fusibility of coal ash is not clear. In this study, the gasification kinetics and ash fusibility of three coal samples with different particle size ranges were investigated. Thermogravimetric results of coal under a CO2 atmosphere showed that the whole weight loss process consisted of three stages: the loss of moisture, the release of volatile matter, and char gasification with CO2. Coal is a heterogeneous material containing impurities. Different grinding fineness leads to different liberation degrees for impurities. As for the effect of particle size on TG (thermogravimetry) curves, we found that the final solid residue amount was the largest for the coal sample with the smallest particle size. The Miura-Maki isoconversional model was proved to be appropriate to estimate the activation energy and its value experienced a slow increase when the particle size of raw coal increased. Further, we found that particle size had an important impact on ash fusion temperatures and small particle size resulted in higher ash fusion temperatures.

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“…3,4 On this hot topic, reducing nitrogen oxide (NO x ) emissions has received the most attention as a difficult part of controlling pollutant emissions. 5,6 In the conventional combustion mode, the high combustion efficiency of pulverized coal is usually attained by increasing the combustion temperature, but the amount of thermal NO increases exponentially when the combustion temperature exceeds 1,500 C, 7,8 leading to a dramatic increase in NO x emissions. Technologies that attain low-NO x emissions during conventional combustion processes include low-NO x burner technology 9,10 and staged combustion technology.…”

Section: Introductionmentioning

confidence: 99%

NO_x emissions of pulverized coal combustion in high‐temperature flue gas

Zhu

Lyu

2020

Asia-Pacific J Chem Eng

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An improved high-temperature flue gas combustion technology was developed and examined in this study. The high-temperature flue gas generator generated a flow of flue gas at a high temperature (720 C) with low oxygen content (10%), which flowed into the main combustion zone and acted as the carrier gas for pulverized bituminous coal (0-0.355 mm) in the combustion chamber. In the combustion chamber, the coal particles reached a higher combustion temperature (>1,100 C) in a short time, and the temperature difference was within 230 C, which showed that the local oxidation zone had been avoided. Furthermore, air-staging combustion technology was also adopted in combination with this technology. NO was the main nitrogen-containing compound, and the concentrations of other nitrogen-containing compounds (N 2 O, NH 3 , and HCN) were extremely low. The NO concentrations were reduced to 0 ppm twice when the volatiles released rapidly in the initial stage, and the volatiles burned violently in the intermediate stage, which are the main reasons for the significant reduction in NO x emissions. The original emissions of NO x were 187.2 mg/m 3 (@6% O 2), and the conversion ratio of fuel-nitrogen to NO x was 16.6%. High-temperature flue gas combustion technology has reached low-NO x combustion for pulverized coal.

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Pyrolysis of superfine pulverized coal. Part 3. Mechanisms of nitrogen-containing species formation

Cited by 31 publications

References 48 publications

Low NO_x Emissions from Pulverized Coal Moderate or Intense Low-Oxygen Dilution Combustion in O₂/CO₂ Preheated by a Circulating Fluidized Bed

Low NO_x Emissions from Pulverized Coal Moderate or Intense Low-Oxygen Dilution Combustion in O₂/CO₂ Preheated by a Circulating Fluidized Bed

Gasification of Shenhua Bituminous Coal with CO2: Effect of Coal Particle Size on Kinetic Behavior and Ash Fusibility

NO_x emissions of pulverized coal combustion in high‐temperature flue gas

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Pyrolysis of superfine pulverized coal. Part 3. Mechanisms of nitrogen-containing species formation

Cited by 31 publications

References 48 publications

Low NOx Emissions from Pulverized Coal Moderate or Intense Low-Oxygen Dilution Combustion in O2/CO2 Preheated by a Circulating Fluidized Bed

Low NOx Emissions from Pulverized Coal Moderate or Intense Low-Oxygen Dilution Combustion in O2/CO2 Preheated by a Circulating Fluidized Bed

Gasification of Shenhua Bituminous Coal with CO2: Effect of Coal Particle Size on Kinetic Behavior and Ash Fusibility

NOx emissions of pulverized coal combustion in high‐temperature flue gas

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Low NO_x Emissions from Pulverized Coal Moderate or Intense Low-Oxygen Dilution Combustion in O₂/CO₂ Preheated by a Circulating Fluidized Bed

Low NO_x Emissions from Pulverized Coal Moderate or Intense Low-Oxygen Dilution Combustion in O₂/CO₂ Preheated by a Circulating Fluidized Bed

NO_x emissions of pulverized coal combustion in high‐temperature flue gas