Changes of oxygen-containing groups during thermal treatment and their influences on moisture readsorption of lignite

Jing, Xiaoxia; Liu, Zhiqiang; Chang, Liping

doi:10.1080/07373937.2015.1072548

Cited by 12 publications

(4 citation statements)

References 34 publications

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“…The content of phenolic hydroxyl group was obtained in accordance with the difference in the values of the total acid (summation of phenolic and carboxylic acids) and carboxylic acid contents. The content of total acid (summation of phenolic and carboxylic acids) could be determined by the method mentioned above, which could be found in our previous study …”

Section: Methodsmentioning

confidence: 99%

“…The content of total acid (summation of phenolic and carboxylic acids) could be determined by the method mentioned above, which could be found in our previous study. 16 The static N 2 adsorption instrument (JW-BK122W) was carried out to measure the specific surface area and the pore volume of the coal samples. About 1.5 g coal sample was weighted into a sample tube to be degassed at 70 °C for 24 h for all samples.…”

Section: Methodsmentioning

confidence: 99%

“…One of the most important aspects is to use suitable dewatering ways to obtain dewatered coals that have different physicochemical structures with each other. From literature, it could be concluded that hydrothermal dewatering, fixed-bed drying, and microwave drying under different conditions would exert different effects on the physicochemical coal structures. − Hydrothermal dewatering could remove some organic and inorganic substances and obviously change coal structures; fixed-bed drying technology is relatively mature in which the device costs are low. The direction of heat and mass transfer is reverse, which would not change the coal structures so dramatically; microwave drying possesses the characteristics of immediacy, integrity, high efficiency, and selectivity, and the direction of heat and mass transfer is same, which would change the coal structures in a different way .…”

Section: Introductionmentioning

confidence: 99%

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Evolution of Physical and Chemical Structures in Lignite during Dewatering Process and Their Effects on Combustion Reactivity

Yang

Liao

et al. 2019

Energy Fuels

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The Inner Mongolia lignite was selected as the feedstock and dewatered by hydrothermal, fixed-bed, and microwave upgrading techniques. The physicochemical structures of the raw coal and dewatered coal samples were determined by N 2 adsorption, Fourier transform infrared, and chemical titration methods. The combustion behavior of coals was investigated by thermogravimetric analyzer, and the results demonstrated that the combustion reactivity of the dewatered coals was enhanced. The apparent activation energies of the coal samples were obtained from nonisothermal single heating rate method, and the results illuminated that the combustion process of these coals could be divided into three stages according to the variations of their apparent activation energies. Those variations were used as the medium to investigate the correlations between combustion reactivity parameters and physicochemical structures. It was found that at stage I of the combustion process, the ignition temperature of the coal was mainly affected by intrinsic chemical reactivity; at stage II, the maximum combustion reaction rate of the coal was affected by intrinsic chemical reactivity and specific area diffusion, and the temperature corresponding to the maximum combustion reaction rate was mainly affected by intrinsic chemical reactivity; and at stage III, the burnout temperature was affected by intrinsic chemical reactivity, and the overall reaction rate was controlled by gas diffusion rate.

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Evolution of Physical and Chemical Structures in Lignite during Dewatering Process and Their Effects on Combustion Reactivity

Yang

Liao

et al. 2019

Energy Fuels

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“…Choi and his coworkers investigated moisture re-adsorption behavior of upgraded low rank coal produced by a coal-oil slurry dewatering process [19] . The moisture re-adsorption behavior of coal samples dried at different temperatures was studied, and Jing found that the equilibrium moisture content decreased with increasing of drying temperature [20] .…”

Section: Introductionmentioning

confidence: 99%

Removal behaviors of moisture in raw lignite and moisturized coal and their dewatering kinetics analysis

et al. 2016

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In order to investigate the dewatering kinetics and mechanism of low rank coal, the dewatering behaviors of a Chinese lignite and its moisturized sample (prepared from dewatered coal moisturized under relative humidity of 75% at 303 K for 48 h) in nitrogen and the temperature range of 333-433 K were tested. Physical structure changes of raw coal, moisturized coal before and after drying were determined. The results indicate that drying process of lignite could be divided into four stages, which are increasing rate stage, constant rate stage, relatively fast decreasing rate stage and relatively slow decreasing rate stage. Jander model and First order kinetics model are favorite to describe the relatively fast decreasing rate stage and relatively slow decreasing rate stage, respectively, and the corresponding dewatering mechanism equations are y= 1/3 2 [1-(1-α)] and y= -ln(1-α) . The effective diffusion coefficients and diffusion activation energy were calculated by Fick's second law. The diffusion activation energy of the dewatering stages, related to the relatively fast and slow decreasing rate stages, were 35.80 kJ/mol, 40.75 kJ/mol for raw coal and 27.80 kJ/mol, 37.34 kJ/mol for moisturized coal, respectively. The effective Downloaded by [University of Cambridge] at 17:16 04 June 20162 diffusion coefficient was significantly affected by drying temperature through the pore structure change of coal when other drying operation parameters were fixed. These prove that the forms of re-adsorbed water are not entirely the same as that in raw lignite, in which the former is relatively simple and the latter is more complex.

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Experimental study on the effects of drying methods on the stabilities of lignite

Zhang

Dong

Guo

et al. 2018

Chinese Journal of Chemical Engineering

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Changes of oxygen-containing groups during thermal treatment and their influences on moisture readsorption of lignite

Cited by 12 publications

References 34 publications

Evolution of Physical and Chemical Structures in Lignite during Dewatering Process and Their Effects on Combustion Reactivity

Evolution of Physical and Chemical Structures in Lignite during Dewatering Process and Their Effects on Combustion Reactivity

Removal behaviors of moisture in raw lignite and moisturized coal and their dewatering kinetics analysis

Experimental study on the effects of drying methods on the stabilities of lignite

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