Experimental investigations of the conversion of fuel-N, volatile-N and char-N to NOx and N2O during single coal particle fluidized bed combustion

Zhou, Hao; Huang, Yan; Mo, Guiyuan; Liao, Ziyu; Cen, Kefa

doi:10.1016/j.joei.2015.10.006

Cited by 32 publications

(15 citation statements)

References 36 publications

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“…The formation and emission processes of NO x , considering the effects of temperature, atmosphere, char gasification, minerals, etc., have been studied extensively during coal mono-combustion. − Compared to coal, the nitrogen content in sludge is much higher, normally 6–8 wt % . In this case, the emission problems of NO x caused by coal and sludge cofiring should not be ignored.…”

Section: Air Pollutant Emissions During Co-combustionmentioning

confidence: 99%

Review on the Current Status of the Co-combustion Technology of Organic Solid Waste (OSW) and Coal in China

et al. 2020

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Increasing economy and population result in the rapid growth of solid waste in China, with more than 70% being carbonaceous components. The generated carbon-bearing solid waste is called as organic solid waste (OSW). In this Review, OSWs from both municipal and industrial sources are discussed and divided into municipal solid waste (MSW), organic sludge, polymer solid waste, and biomass-like solid waste, according to their variations in origins and characteristics in China. Agricultural waste (i.e., biomass) and large-scale industrial solid waste (e.g., coal waste) are not considered, because of their well-established fundamentals. Incineration is becoming the most common method of energy recovery for OSW in China, while it has to face the problems of relatively low thermal efficiency, high air pollutant emission, and the high risk of fly ash products. Compared with MSW incinerators, coal-fired power plants own efficient power generation systems and centralized air pollution control devices (APCDs). With the fact that mixed coals are widely used in existing power plants, it is of great significance to study and discuss the current status of cocombustion of OSW and coal in China. In this work, the physicochemical properties of OSW were first introduced, with a subsequent detailed summary on their co-combustion fundamentals, such as devolatilization, ignition, char reactivity, and combustion efficiency, and ash-related issues, including fouling/slagging, high-temperature corrosion, and leaching behavior of ash residue. Furthermore, pollutants emissions regarding conventional pollutant [CO, SO 2 , NO x , HCl, particulate matters (PM)], heavy metals, and hazardous organic pollutants such as polycyclic aromatic hydrocarbons (PAHs) and polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) were analyzed. Some pretreatment methods to reduce the risk of co-combustion were also discussed, including pelletization, drying, torrefaction, hydrothermal carbonization, and low-temperature pyrolysis. Lastly, discussions and perspectives on the future co-combustion technology of OSW with coal were presented. This work aimed to gain systematic knowledge on the co-combustion technology of OSW and coal, providing guidelines for further applications of OSW in power plants in China, as well as other countries in the world.

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Section: Air Pollutant Emissions During Co-combustionmentioning

confidence: 99%

Review on the Current Status of the Co-combustion Technology of Organic Solid Waste (OSW) and Coal in China

et al. 2020

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“…These kinds of active sites, which are mainly isolated unpaired electrons, could largely be produced at higher temperatures. Therefore, temperature control during coal/biomass combustion in a CFB reactor is crucial. , A small amount of oxygen can greatly promote the production of N 2 O. During oxygen-staged combustion, the control of the oxygen content in the combustion chamber downstream (where the temperature is in the N 2 O formation region) has an important influence on the control of N 2 O.…”

Section: Resultsmentioning

confidence: 99%

Quantum Chemical and Kinetic Studies of N₂O Formation during Interaction between Char(N) and NO: Influence of Oxygen, Active Sites, and Nitrogen Status

Zhao

Niu

et al. 2021

J. Phys. Chem. A

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In order to obtain a deep insight into the N 2 O formation mechanism in a fluidized bed, density functional theory was used to investigate the interaction between char(N) and NO at a molecular level. Three key influencing factors for the formation of N 2 O, namely, active sites, nitrogen status, and oxygen molecules, were taken into study. The geometric structures, electron distribution characteristics, and reaction paths were optimized and calculated. The outer orbital electron properties of char(N) and NO indicate that NO acts as an oxidizer, which tends to abstract electrons from char(N) during the char(N)−NO interaction. A stable N 2 O molecule has a singlet state and presents as a linear molecular structure. The chemisorption on the char surface will weaken the bond energy of NO from 620 to 94.1 kJ/mole, which promotes the catalytic reduction of NO. Active sites on the char surface benefit the reduction of NO to N 2 , rather than N 2 O, which indicates that excessive high temperatures will inhibit the production of N 2 O. The combination of pyridine nitrogen and NO to form N 2 O needs to overcome a much higher energy barrier of 357.4 kJ/mole. The initial chemisorption of oxygen molecules on the char surface will promote the formation of N 2 O by lowering the dissociation energy of N 2 O from the char surface as well as exposing nitrogen to the char surface.

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“…In general, the predominant form of biomass combustion is through rapid oxidation of volatiles, while coal combustion undergoes short-term volatile oxidation and longer-term char oxidation. , During the devolatilization of fuel, the volatile-N is released as HCN and NH 3 , which are the major precursors of NO formation. ,,,− Furthermore, most of the fuel nitrogen in biomass is volatilized and converted to NH 3 during combustion, while coal retains more nitrogen in char. ,,,,,,− …”

Section: Results and Discussionmentioning

confidence: 99%

“…As mentioned in Section , the volatile-N is released as HCN and NH 3 during the devolatilization of fuel. HCN is the main source of the homogeneous formation of N 2 O , through the following gas-phase reactions (reaction 6 () and reaction 7 ()), while NH 3 hardly forms N 2 O. , …”

Section: Results and Discussionmentioning

confidence: 99%

Experimental Studies on the Emission of Gaseous Pollutants in an Oxy-Fuel-Fluidized Bed with the Cofiring of Coal and Biomass Waste Fuels

Liu

Zhong

et al. 2020

Energy Fuels

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The cofiring of coal and biomass waste is an important technological direction in oxy-fuel combustion for both CO2 capture and waste disposal. The emission of pollutants during cofiring in an oxy-fuel-fluidized bed is a complex process, and practical knowledge of this process is still very limited. In this work, experimental studies on the emission of gaseous pollutants in a 10 kWth oxy-fuel-fluidized bed (combustion temperatures T1 = 800 and 850 °C and inlet O2 concentration = 30%) were carried out. The effects of the biomass blending mass ratio (M b = 0, 10, 20, 30, 50, 70, and 100%), fuel property (fuel volatility and fuel O/N, Ca/S, and K2/S molar ratios), and excess oxygen ratio (α = 1.10, 1.25, and 1.40) on gaseous pollutants CO, CH4, NO, NOx (including NO and NO2), N2O, and SO2 were systematically investigated. The results show that both CO and CH4 increase with increasing M b, and an increase in α leads to a significant decrease in CO and a slight change in CH4. The emissions of NO and NOx decrease with increasing M b because of the dilution of fuel-N and the enhancement of reduction reactions. The generation rate of N2O is much higher than that of NOx, and it decreases with increasing M b. The total conversion rate of fuel-N to nitrogen oxides is lower than 50% when cofiring coal and biomass, which is promoted by α but not by M b. In addition, the ratio of the NOx generation rate to the N2O generation rate is larger at higher fuel O/N molar ratios, and the NOx emissions per unit calorific value decrease rapidly as the fuel volatility increases. Furthermore, the SO2 emissions per unit calorific value decrease with increasing M b and Ca/S and K2/S molar ratios in fuel. An increase in α promotes the generation and emission of SO2.

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Experimental investigations of the conversion of fuel-N, volatile-N and char-N to NOx and N2O during single coal particle fluidized bed combustion

Cited by 32 publications

References 36 publications

Review on the Current Status of the Co-combustion Technology of Organic Solid Waste (OSW) and Coal in China

Review on the Current Status of the Co-combustion Technology of Organic Solid Waste (OSW) and Coal in China

Quantum Chemical and Kinetic Studies of N₂O Formation during Interaction between Char(N) and NO: Influence of Oxygen, Active Sites, and Nitrogen Status

Experimental Studies on the Emission of Gaseous Pollutants in an Oxy-Fuel-Fluidized Bed with the Cofiring of Coal and Biomass Waste Fuels

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Experimental investigations of the conversion of fuel-N, volatile-N and char-N to NOx and N2O during single coal particle fluidized bed combustion

Cited by 32 publications

References 36 publications

Review on the Current Status of the Co-combustion Technology of Organic Solid Waste (OSW) and Coal in China

Review on the Current Status of the Co-combustion Technology of Organic Solid Waste (OSW) and Coal in China

Quantum Chemical and Kinetic Studies of N2O Formation during Interaction between Char(N) and NO: Influence of Oxygen, Active Sites, and Nitrogen Status

Experimental Studies on the Emission of Gaseous Pollutants in an Oxy-Fuel-Fluidized Bed with the Cofiring of Coal and Biomass Waste Fuels

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Quantum Chemical and Kinetic Studies of N₂O Formation during Interaction between Char(N) and NO: Influence of Oxygen, Active Sites, and Nitrogen Status