Advances in reduction of NO  and N2O1 emission formation in an oxy-fired fluidized bed boiler

Sheikh, Khalid El; Khan, Mohammad Jakir Hossain; Hamid, Mahar Diana; Shrestha, Siddhartha; Ali, Brahim Si; Ryabov, G. A.; Dolgushin, Lya A.; Hussain, Mohd Azlan; Бухаркина, Т. В.; Gorelova, Elena A.

doi:10.1016/j.cjche.2018.06.033

Cited by 24 publications

(10 citation statements)

References 135 publications

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“…During combustion of solid fuels in a fluidized bed (whether air or oxy-fuel combustion), nitrogen oxides, mainly NO x and N 2 O, are generally considered, of which NO x is mostly NO with a small amount of NO 2 . , The operating temperature of the fluidized bed is relatively low, so nitrogen oxides mainly come from the oxidation of fuel-N compounds, while thermal NO and prompt NO formation mechanisms are usually negligible. , …”

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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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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“…Oxy-fuel combustion also offers a number of additional advantages including the fact that the NO x emissions are smaller for a given thermal input of fuel. Due to its advantages, oxy-fuel combustion is one of the most promising technology for CCS [1][2][3][4][5][6], moreover the possibility of carrying out cocombustion with biomass, may also offer the possibility of negative CO 2 emissions via the so called bio-energy with carbon capture and storage (BECCS) approach [7,8]. Biomass is assumed to be "CO 2 neutral" because it uses CO 2 in the atmosphere as a carbon source during its growth and if CO 2 released by the combustion of biomass is captured, then the CO 2 is permanently removed from the atmosphere and hence BECCS technology can achieve negative CO 2 emissions [9].…”

Section: Introductionmentioning

confidence: 99%

The effect of H2O on the sulfation of Havelock limestone under oxy-fuel conditions in a thermogravimetric analyser

Varol¹,

Anthony²,

Macchi³

2021

Turk J Chem

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A gas mixture representing oxy-fuel combustion conditions was employed in a thermogravimetric analyser to determine the effect of water vapor and SO 2 concentration on limestone sulfation kinetics over the temperature range of 800 to 920 °C . Here, experiments used small samples of particles (4 mg), with small particle sizes (d p < 38 µm) and large gas flow rates (120 mL/min@ NTP) in order to minimize mass transfer interferences. The gas mixture contained 5000 ppm v SO 2 , 2% O 2 , and the H 2 O content was changed from 0% to 25% with the balance CO 2 . When water vapor was added to the gas mixture at lower temperatures (800-870 °C ), the limestone SO 2 capture efficiency increased. However, as the temperature became higher, the enhancement in total conversion values decreased. As expected, Havelock limestone at higher temperatures (890 °C , 920 °C , and 950 °C ) experienced indirect sulfation and reacted at a faster rate than for lower temperatures (800-870 °C ) for direct sulfation over the first five minutes of reaction time. However, the total conversion of Havelock limestone for direct sulfation was generally greater than for indirect sulfation.

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“…The discussed research and modelling do not take into account the amount of air in-leakages into the combustion system (Zanganeh and Shafeen 2007;Jin et al 2015;El Sheikh et al 2019;Liu et al 2019;Hu et al 2020;Gopan et al 2020). The modelling of the combustion and formation of NO x and SO 2 does not take into account nitrogen, which can get through leaks of the oxygen supply system or the combustion system.…”

Section: Introductionmentioning

confidence: 99%

Emission of typical pollutants (NOX, SO2) in the oxygen combustion process with air in-leakages

Moroń

Ferens

Wach

2021

Environ Sci Pollut Res

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Oxygen combustion, being an alternative to air combustion, is distinguished in a variety of modern coal management technologies by quick and easy removal of CO2 from the combustion process, which is the key merit of this oxy-fuel technology. The laboratory work conducted so far has not directly addressed the issue of air in-leakages in the oxy-fuel system. The previous studies showed that air in-leakages in the combustion system (both under the air and oxygen regime) occur and affect the combustion process. However, there are no direct research studies on the volume of air in-leakages and their impact on the individual stages of combustion, including the emission of gaseous pollutants. This article focuses on the assessment of the impact of air in-leakages on NOx and SO2 emissions for a single-stage coal-dust combustion system. Moreover, these studies were supplemented with measurements on the rate of devolatilisation of volatile matters and, in particular, on the rate of nitrogen compounds released from fuel. The obtained results of combustion in the oxy-fuel atmosphere with the following air in-leakage levels: 10, 15 and 20% were compared to combustion conditions in the air. Air in-leakages in the oxygen combustion system create an additional flow of oxygen and nitrogen appearing in the combustion area, which affects the course of pollutants and their emission. The conducted studies have shown that when adequate tightness of the combustion system is provided, it contributes to the reduced emission of nitrogen compounds.

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Advances in reduction of NO and N2O1 emission formation in an oxy-fired fluidized bed boiler

Cited by 24 publications

References 135 publications

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

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

The effect of H2O on the sulfation of Havelock limestone under oxy-fuel conditions in a thermogravimetric analyser

Emission of typical pollutants (NOX, SO2) in the oxygen combustion process with air in-leakages

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