Nitrogenous Gas Emissions from Coal/Biomass Co-combustion under a High Oxygen Concentration in a Circulating Fluidized Bed

Wang, Xin; Ren, Qiangqiang; Li, Wei; Li, Haoyu; Li, Shiyuan; Qi, Lu

doi:10.1021/acs.energyfuels.6b03141

Cited by 26 publications

(15 citation statements)

References 38 publications

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“…Circulating fluidized bed (CFB) technology with high throughput and gas–solids contact efficiency has been widely applied in a large number of industrial processes, , such as coal combustion, , fluid catalytic cracking (FCC), municipal solid waste incineration, biomass treatment, and so on. − In general, these processes can be divided into two categories: gas–solids reaction processes and catalytic gas-phase reaction processes . For gas–solids reaction processes, the coal combustion is a typical industrial process, which is usually operated under the conditions of a low superficial gas velocity (5–9 m/s) and low solids circulation rate (10–100 kg/(m 2 s)) with dilute solids holdup (<1%).…”

Section: Introductionmentioning

confidence: 99%

Experimental Study of Solids Motion in an 18 m Gas–Solids Circulating Fluidized Bed with High Solids Flux

Wang

Pei

et al. 2019

Ind. Eng. Chem. Res.

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A comprehensive experimental study of solids motion is conducted in an 18 m-high circulating fluidized bed with an extremely high solids circulation rate (G s) up to 1000 kg/(m2 s), which has never been achieved in such a tall riser in previous research studies. The axial distributions of the particle velocity show exponential curves and slight changes in the fully developed zone with G s higher than 400 kg/(m2 s). The radial profiles of the particle velocity have parabolic shapes and become steeper with increasing G s. The development of the gas–solids flow structure becomes slower with increasing G s or decreasing superficial gas velocity (U g). When G s reaches 800 kg/(m2 s), the full development is achieved until reaching an axial height higher than 12 m. Better correlations between the local particle velocity and solids holdup and less downflowing particles indicate better reactor performance with the reduction of solids back-mixing and uniform residence times at an extremely high G s.

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Section: Introductionmentioning

confidence: 99%

Experimental Study of Solids Motion in an 18 m Gas–Solids Circulating Fluidized Bed with High Solids Flux

Wang

Pei

et al. 2019

Ind. Eng. Chem. Res.

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“…Wang and co-workers [18] investigated nitrogenous gas (NO, N 2 O, HCN) emissions from co-combustion of coal and biomass (corn straw and wheat straw) under oxy-fuel conditions with 50% oxygen concentration in the oxidizing medium. Tests were carried out in a 100 kW CFB combustor with blends containing 30% biomass and in atmospheres containing O 2 /CO 2 and O 2 /recycled flue gas mixtures (RFG) at temperatures 800-900 • C. As expected, the NO and N 2 O emissions increased with increasing excess oxygen in the oxidizing medium.…”

Section: Literature Reviewmentioning

confidence: 99%

Pollutant Emissions during Oxy-Fuel Combustion of Biomass in a Bench Scale CFB Combustor

2022

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Nowadays oxy-fuel combustion of coal and biomass is the most promising option for the reduction of CO2 emissions from power plants. In this paper, emissions of NOx (NO, NO2, N2O and their precursors, such as NH3 and HCN), SO2 and CO during conventional and oxy-fuel combustion of three kinds of biomass (agro, woody and energy crop) and a reference coal are presented and discussed. Combustion tests were conducted at 850 °C in the laboratory-scale circulating fluidized bed (CFB) reactor in air and O2/CO2 atmospheres. A FTIR spectrometer was used to measure instantaneous concentrations of all pollutants in the flue gas. Emissions of SO2, N2O and CO for the combustion of biomass in all atmospheres were lower than those for the combustion of reference coal. It was found that oxidation of nitrogen species released with volatile matter was responsible for high emissions of NOx during combustion of biomass fuels in air and mixtures of O2 and CO2. The lowest NO emissions for tested fuels were detected in oxy-21 atmosphere (21% O2/70% CO2). Oxy-combustion of biomass in O2/CO2 mixtures at 30% and 40% O2 caused a decrease in emissions of N2O and CO while NO and SO2 emissions increased. The results of this study show that the tested biomass fuels are ideal renewable energy resources both in conventional and oxy-fuel conditions with a minor potential for environmental pollution.

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“…Many theoretical and experimental studies have been carried out to understand the complex cofiring behaviors under oxy-fuel conditions, including basic principle experiments (e.g., thermogravimetric analysis, − fixed-bed cofiring, , tube furnace cofiring, − and fluidization reactor cofiring ,− ), fluidized bed cofiring with continuous fuel feeding, − and numerical modeling. − Important research progress was made by CanmetENERGY in Canada , and CIUDEN in Spain, , who carried out continuous cofiring tests under oxy-fuel conditions in 0.8 MW th and 30 MW th fluidized beds, respectively. In addition, KIER in South Korea and IET in China performed cofiring tests in 0.1 MW th fluidized beds. These studies verified the practical feasibility of this process and obtained useful knowledge of the basic features of oxy-fuel cofiring.…”

Section: Introductionmentioning

confidence: 99%

“…The emission of pollutants (gaseous and solids) is an important basic feature of oxy-fuel cofiring and is closely related to the combustion process (such as flue gas recycling), ,,, flue gas purification (desulfurization, denitrification, dust removal, etc. ), , and related equipment manufacturing, as well as environmental and health hazards. , However, the understanding of pollutant emissions is not comprehensive or sufficient.…”

Section: Introductionmentioning

confidence: 99%

“…Taking the relationship between the emissions of nitrogen oxides and the biomass ratio as an example, in a drop-tube laboratory furnace, Feyza Kazanc found that the NO x emission from the blending of bituminous coal and bagasse was lower than the weighted-average emissions of the two neat fuels. However, in oxy-fuel cofiring fluidized beds, some studies ,, suggested that the NO x emission increased as the biomass ratio increased, some studies ,, proposed that the NO x emissions were slightly affected by the biomass blending ratio, and some studies , found that the addition of biomass inhibited the formation of NO x . Therefore, in-depth and systematic theoretical and practical studies on the emissions of gaseous pollutants are required.…”

Section: Introductionmentioning

confidence: 99%

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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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Nitrogenous Gas Emissions from Coal/Biomass Co-combustion under a High Oxygen Concentration in a Circulating Fluidized Bed

Cited by 26 publications

References 38 publications

Experimental Study of Solids Motion in an 18 m Gas–Solids Circulating Fluidized Bed with High Solids Flux

Experimental Study of Solids Motion in an 18 m Gas–Solids Circulating Fluidized Bed with High Solids Flux

Pollutant Emissions during Oxy-Fuel Combustion of Biomass in a Bench Scale CFB Combustor

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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