Interactions between free radicals during co-pyrolysis of lignite and biomass

He, Wenjing; Yin, Guojun; Zhao, Yibo; Zhang, Lanjun; Xu, Shuyue; Huang, Tingting; Chang, Lu; Lu, Hanxiao

doi:10.1016/j.fuel.2021.121098

Cited by 33 publications

(13 citation statements)

References 57 publications

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“…This is because during the pre-combustion stage when biomass volatiles are precipitated, the fuel will undergo pyrolysis and generate tar and light hydrocarbon compounds. The tar and light hydrocarbon compounds 44 will subsequently undergo a second pyrolysis under high temperature conditions and generate H-based free radicals. The chemical reaction between the H radical and char sample breaks the chemical bond between the carbon base and the alkali metal, resulting in the precipitation of the alkali metal element during the pyrolysis process.…”

Section: Resultsmentioning

confidence: 99%

Reduced Pollutant Emissions and Slagging Rate of Biomass Pellet Combustion by Optimizing the Multilayer Distribution of Secondary Air

Liu

Wang

et al. 2022

ACS Omega

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The utilization of coal and other fossil fuels is becoming increasingly restricted. Biomass, as a clean and renewable energy, plays a significant role in achieving zero carbon emissions. However, biomass is prone to slagging in the combustion process due to its high alkali metal content. The ash slagging rate and pollutant emission level of flue gas can be reduced by optimizing the air distribution, in order to decrease the fuel layer temperature in the combustion chamber. The results reveal opposite change trends of CO and NO x concentrations in the flue gas. The NO x emissions of corn stalk combustion under the multilayer secondary air distribution are obvious compared with those of rice husk combustion. The slagging rate of corn stalks is highly correlated with temperature T 1 of the fuel bed. The silica ratio ( G ), alkali/acid ratio ( B / A ), Na content index (Na (index)), and alkaline index (Al c ) cannot accurately predict the slagging tendency when temperature T 1 changes. Therefore, the modified predictive index ( G t ) was proposed to predict the slagging tendency of corn stalks with the combustion zone temperature T 1 effectively. The experimental results can contribute to the efficient combustion and low pollutant emissions of biomass.

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Section: Resultsmentioning

confidence: 99%

Reduced Pollutant Emissions and Slagging Rate of Biomass Pellet Combustion by Optimizing the Multilayer Distribution of Secondary Air

Liu

Wang

et al. 2022

ACS Omega

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“…An increase in free radical concentration always means the generation of free radicals caused by the breakage of the covalent bond. 27 However, typically, covalent bond cleavage is not considered during solvent extraction. Therefore, it is difficult to understand the reason for the increase in the radical concentration during solvent extraction; the same will be discussed later.…”

Section: Resultsmentioning

confidence: 99%

“…An increase in free radical concentration always means the generation of free radicals caused by the breakage of the covalent bond . However, typically, covalent bond cleavage is not considered during solvent extraction.…”

Section: Resultsmentioning

confidence: 99%

Interactions between Coal and Solvent during the Solvent Extraction of Coal in View of Free Radicals

Liu

et al. 2021

ACS Omega

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In this study, variations in the free radical concentration, degree of swelling (Q), and extraction yield of Buertai coal (C%, 80.4%) in 11 solvents with different characteristics were determined to investigate the interaction between the coal and solvent, as well as the bond cleavage during solvent extraction. Derivative thermogravimetry (DTG) results for the residues and raw coal were compared to confirm whether the covalent bond breaks during solvent extraction. The free radical concentration decreases in certain solvents but increases in a few others. The relative free radical concentration, Q, and extraction yield are positively correlated. The charge-transfer capability of the solvent, and in particular its electron-donating capability, plays an essential role in influencing the interaction between the coal and solvent. The increase in the free radical concentration during solvent extraction can be attributed to (1) the formation or decomposition of charge-transfer complexes, (2) dissociation of charge-transfer complexes into radical ions, and (3) breakage of weak covalent bonds. DTG results show the occurrence of weak covalent bonds breakage at temperatures of 133.9−320.1 °C during solvent extraction due to the reduction of the bond energy caused by the formation of radical ions.

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“…The studies focus on thermogravimetric analysis (TGA) reactors, the tube furnace, fixed bed reactors, agitated bed pyrolysis reactors, the pyrolysis furnace design and in some cases, semi-industrial scale pyrolysis units. One study co-pyrolyzing coal and walnut shells revealed the experimental results for char yield to be higher than the calculated values showing excellent potential for application [ 26 ]. Another specific study focused on co-pyrolysis of sewage sludge (SS) with bamboo sawdust, exhausted tea, and rice husk, all giving chars with good yields greater than 50% and a surface area greater than 14 m 2 /g in all cases showing promising potential for activation and further use as an adsorbent [ 27 ].…”

Section: Co-pyrolysis and Potential Chars For Water Treatmentmentioning

confidence: 99%

A review of prospects and current scenarios of biomass co-pyrolysis for water treatment

Zuhara

Mackey

Al‐Ansari

et al. 2022

Biomass Conv. Bioref.

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With ever-growing population comes an increase in waste and wastewater generated. There is ongoing research to not only reduce the waste but also to increase its value commercially. One method is pyrolysis, a process that converts wastes, at temperatures usually above 300 °C in a pyrolysis unit, to carbon-rich biochars among with other useful products. These chars are known to be beneficial as they can be used for water treatment applications; certain studies also reveal improvements in the biochar quality especially on the surface area and pore volume by imparting thermal and chemical activation methods, which eventually improves the uptake of pollutants during the removal of inorganic and organic contaminants in water. Research based on single waste valorisation into biochar applications for water treatment has been extended and applied to the pyrolysis of two or more feedstocks, termed co-pyrolysis, and its implementation for water treatment. The co-pyrolysis research mainly covers activation, applications, predictive calculations, and modelling studies, including isotherm, kinetic, and thermodynamic adsorption analyses. This paper focuses on the copyrolysis biochar production studies for activated adsorbents, adsorption mechanisms, pollutant removal capacities, regeneration, and real water treatment studies to understand the implementation of these co-pyrolyzed chars in water treatment applications. Finally, some prospects to identify the future progress and opportunities in this area of research are also described. This review provides a way to manage solid waste in a sustainable manner, while developing materials that can be utilized for water treatment, providing a double target approach to pollution management.

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Interactions between free radicals during co-pyrolysis of lignite and biomass

Cited by 33 publications

References 57 publications

Reduced Pollutant Emissions and Slagging Rate of Biomass Pellet Combustion by Optimizing the Multilayer Distribution of Secondary Air

Reduced Pollutant Emissions and Slagging Rate of Biomass Pellet Combustion by Optimizing the Multilayer Distribution of Secondary Air

Interactions between Coal and Solvent during the Solvent Extraction of Coal in View of Free Radicals

A review of prospects and current scenarios of biomass co-pyrolysis for water treatment

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