Thermal properties of coal during low temperature oxidation using a grey correlation method. (15th January 2020)

• Record Type: Journal Article
• Authors: Ren, Shuai-Jing; Wang, Cai-Ping; Xiao, Yang; Deng, Jun; Tian, Yuan; Song, Jia-Jia; Cheng, Xiao-Jiao; Sun, Guo-Feng
• Is Part Of: Fuel. Volume 260(2020)
• Publication Date: 2020-01-15
• Subjects: Heat transfer -- Coal spontaneous combustion -- Moisture -- Thermal conductivity -- Grey correlation; Fuel -- Periodicals; Coal -- Periodicals; Coal; Fuel; Periodicals; 662.6
• DOI: 10.1016/j.fuel.2019.116287
• Languages: English
• ISSNs: 0016-2361

Abstract

Highlights: Volatiles variations were inversely related with changes of fixed carbon. A factor analysis method combining qualitative and quantitative was proposed. Heat transfer mechanism of coal low temperature oxidation process was investigated. Correlation between thermal properties and proximate analysis was approached. Abstract: The low temperature oxidation of coal is a contradictory and unified dynamic process of coexisting mass and heat transfer. The thermophysical properties are crucial during coal spontaneous combustion. In the current paper, the variations of moisture, ash, volatiles, fixed carbon and thermophysical properties (thermal diffusivity, specific heat and thermal conductivity) of three coal samples from 30 °C to 300 °C were studied, and their grey correlation was analyzed. The results indicated that with the increase of temperature, the free moisture of Coals A and B decreased first but then increased, while the free moisture of Coal C kept decreasing without a later increase. The variation of surface moisture was consistent with that of free moisture. The trend of volatiles and fixed carbon was completely the opposite, showing a significant negative correlation. Ash was less affected by temperature. Along with the rise of temperature, the thermal diffusivity of three coal samples decreased first but later increased, and the specific heat was always in a state of increasing. The change in thermal conductivity was mainly affected by specific heat. By calculating the grey correlation degree, the major factors affecting the thermophysical properties were obtained.