Effect of microwave pretreatment on oxidization behaviors of bituminous coal: Experimental measurement and quantum chemistry calculation. (15th July 2023)

• Record Type: Journal Article
• Authors: Feng, Lele; Dong, Maifan; Qin, Botao
• Is Part Of: Fuel. Volume 344(2023)
• Publication Date: 2023-07-15
• Subjects: In-situ combustion -- Microwave heating -- Functional group -- Quantum chemistry calculation -- Oxidization reactivity; Fuel -- Periodicals; Coal -- Periodicals; Coal; Fuel; Periodicals; 662.6
• DOI: 10.1016/j.fuel.2023.128040
• Languages: English
• ISSNs: 0016-2361

Abstract

Highlights: Effect of microwave time on coal combustion behaviors was studied. Effect of microwave pretreatment on the functional groups was measured. Reaction of functional groups was studied with quantum chemistry calculation. Abstract: The poor heat conduction and mass transfer of coal seam causes unsatisfying performance of gas production for in situ combustion, while microwave pretreatment is a promising technology to solve this problem. In this work, microwave heating is adopted as pretreatment method to prepare coal samples at different microwave time. The low temperature oxidization and high temperature combustion behaviors of raw coal and modified coal samples were studied with programmed temperature rising method. The functional group content in coal samples were measured with Fourier transform infrared spectrometer, while the relationship between microstructure and reactivity was studied with quantum chemistry calculation. As microwave heating time extends from 0 s to 180 s, the crossing point temperature decreases, while the combustion reaction rate increases. As microwave time prolongs from 180 s to 240 s, the crossing point temperature becomes larger, while the combustion reaction rate becomes smaller. As microwave time increases from 0 s to 240 s, hydroxyl content and carbonyl content in coal samples reduce while ether content rises. The reduction of hydroxyl and increase of ether result in an enhancement of oxidization reactivity. The decrease of carbonyl is unfavorable for oxidization reactivity. Therefore, the effect of microwave heating on coal reactivity has two sides. This explains why the microwave pretreatment time has a non-monotonic effect on the coal reactivity in both low temperature and high temperature range.