Classification of water forms in lignite and analysis of energy consumption on the drying processes by microwave and fixed bed

Liao, Junjie; Mo, Qiong; Li, Chao; Yong, Han; Chang, Liping; Wang, Bao

doi:10.1016/j.fuel.2019.05.047

Cited by 22 publications

(7 citation statements)

References 26 publications

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“…16 Liao et al measured the change in dewatering energy consumption for removing different types of water from two different ranks of lignite and concluded that a 500−600 W microwave field is suitable for drying lignite. 17 Li et al studied the kinetic dehydration process of microwave drying lignite and found a similar law. It is recommended that microwave power higher than 550 W should be used to remove free water and capillary water and 252 W should be used to remove molecular water.…”

Section: Introductionmentioning

confidence: 82%

“…Wang et al found that the removal of moisture under microwave radiation presented uneven changes . Liao et al measured the change in dewatering energy consumption for removing different types of water from two different ranks of lignite and concluded that a 500–600 W microwave field is suitable for drying lignite . Li et al studied the kinetic dehydration process of microwave drying lignite and found a similar law.…”

Section: Introductionmentioning

confidence: 99%

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Experimental Research on Water Migration-Damage Characteristics of Lignite under Microwave Heating

et al. 2021

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Microwave has attracted much attention with respect to coal drying, especially improving the performance of lignite. In this study, the characteristics of dehydration dynamics and changes in the physical structure of lignite under microwave radiation were investigated. The results show that the change process of temperature and moisture is phased in the microwave dehydration period (0−180 °C). Moreover, the change in the moisture content of lignite is actually the coupled migration of liquid water and water vapor, and the pressure gradient and temperature gradient formed by uneven evaporation of water under high-power microwave heating not only promote the formation, development, and connection of pores and fractures but also contribute to the movement of water, especially partially liquid water which can directly migrate to the coal surface. Higher moisture content means more intense water movement under microwave heating as well as more significant lignite drying and structural damage effects. The research discussed the correlation between moisture movement and lignite structure, which can provide constructive insight into the efficient application of microwave drying and heat-driven cracking technology to coal.

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Section: Introductionmentioning

confidence: 82%

Section: Introductionmentioning

confidence: 99%

Experimental Research on Water Migration-Damage Characteristics of Lignite under Microwave Heating

et al. 2021

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“…Microwaves are electromagnetic waves with frequencies ranging from 300 MHz to 3,000 GHz. With continuous research, microwaves are widely used in industrial heating, such as microwave petroleum pyrolysis (Khelfa et al, 2020;Kumar et al, 2020;Taheri-Shakib and Kantzas, 2021;Zhu et al, 2021), auxiliary pyrolysis, coal desulfurization and drying Liao et al, 2019;Si et al, 2019;Cai et al, 2021;Lichao and Xiaoyan, 2022;Yucen et al, 2022;Zhu et al, 2022), and microwave crushing (Hassani et al, 2016;Hartlieb et al, 2018;Chen et al, 2021). The size of traditional electrically large microwave heating equipment is similar to the wavelength, which makes the electric field distribution in the cavity non-uniform.…”

Section: Introductionmentioning

confidence: 99%

Effect of metal slots on the heating uniformity of multisource cavity microwave

Yin

2023

Front. Energy Res.

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Microwave heating as a new type of heating has been widely used in numerous fields; however, microwave heating in multi-source cavity still poses several problems, including non-uniformity, low efficiency, restriction of the heating object, and “thermal runaway”, thus limiting the application of microwave energy. This study adopts a method to place a slotted layer in the cavity such that the energy can be radiated uniformly to improve the heating uniformity. The distribution of the electric field in the cavity is optimized by changing the arrangement and size of the slots in the slot layer. The effects of the slot arrangements are elucidated, and experiments are performed to study the real-life application of the slot arrangements. The results show that these metal slots are effective in improving the uniformity and efficiency of multisource cavity heating.

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“…e behavior of water in coal depends on many factors, such as intermolecular hydrogen bonding [10]. Water molecules interact with the oxygen-containing functional groups on the surface of coal by hydrogen bonds [11][12][13][14].…”

Section: Introductionmentioning

confidence: 99%

Effect of -O- on Water Molecule Adsorption and Adsorption Mechanism of Lignite and Coke

Bai

Song

Teng

et al. 2021

Journal of Chemistry

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The high moisture content of lignite restricts its extensive and efficient use. Furthermore, the reabsorption of lignite is also a factor that affects lignite spontaneous combustion. Therefore, it is of great importance to study the process and mechanism of water molecule desorption and adsorption on lignite and coke (25–950°C) to achieve the clean and efficient utilization of lignite and environmental protection. Proton nuclear magnetic resonance (1H-NMR), thermogravimetric analysis, and other techniques were used in this study to explore the water molecule absorption and desorption processes of lignite pyrolysis at different temperatures (25–950°C) and the special contributions of ether bonds to water molecule adsorption. A mechanism of lignite water molecule adsorption was proposed. The results showed that ether bonds played a special role in the water molecule adsorption by pyrolyzed lignite. The ether bond content was greater in the coal samples at 300 and 950°C, which changed the trend of lignite water molecule absorption and the distribution of water (T2) detected in the 1H-NMR experiments and delayed the escape of water molecules during moisture desorption. The total amount of adsorbed water decreased first and then increased in the coal samples as the pyrolysis temperature increased. However, the maximum adsorption interactions of each coal sample increased first and then decreased. This was the result of the interactions between the pores and the oxygen-containing functional groups. Based on the above analysis, water molecule adsorption mechanism models of lignite and coke were constructed. This study offers a new approach for investigating the water molecule adsorption and adsorption mechanisms of lignite and coke.

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Classification of water forms in lignite and analysis of energy consumption on the drying processes by microwave and fixed bed

Cited by 22 publications

References 26 publications

Experimental Research on Water Migration-Damage Characteristics of Lignite under Microwave Heating

Experimental Research on Water Migration-Damage Characteristics of Lignite under Microwave Heating

Effect of metal slots on the heating uniformity of multisource cavity microwave

Effect of -O- on Water Molecule Adsorption and Adsorption Mechanism of Lignite and Coke

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