Experimental and theoretical study on kinetic behaviour of coal gangue and raw coal using model reconstruction
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Experimental and theoretical study on kinetic behaviour of coal gangue and raw coal using model reconstruction Bei Li1 · Gang Liu1 · Weili Sun2 · Lili Ye1 · Mingshu Bi1 · Wei Gao1 Received: 4 August 2020 / Accepted: 6 October 2020 © Akadémiai Kiadó, Budapest, Hungary 2020
Abstract Coal gangue (CG) and raw coal (RC) can catch fire due to spontaneous combustion. The combustion characteristics, functional groups, and kinetic behaviour of CG and RC were investigated to assess their thermal stability characteristics using thermogravimetric/Fourier transform infrared techniques (TG/FTIR) at heating rates of 10, 20, and 30 °C m in−1. More types of aliphatic hydrocarbons and naphthenic bands found in CG than RC from FTIR analysis results contributed to more gaseous products including CO, CO2, and CH4 after 400 °C. A decomposition mechanism consisting of three stages for both samples was identified based on the characteristic temperatures obtained from TG data. The kinetic data of each sample were determined using different methods. The apparent activation energy varied in values for CG and RC due to the difference in combustible component content, but owned similar variation trend according to results of Vyazovkin method. The value of Eα calculated from Starink and Kissinger–Akahira–Sunose methods exhibited good coincidence compared to Vyazovkin method. Reconstruction models without consideration the value of the heating rates were developed using the differential evolution algorithm to simulate the oxidation processes of each of the CG and RC samples, which was experimentally validated. Keywords Coal gangue · Spontaneous combustion · Combustion characteristic · Apparent activation energy · Reconstruction model List of symbols A Pre-exponential factor (s−1) αm Accommodation function Eα Apparent activation energy (kJ mol−1) g(α) Integral reaction model based on conversion k(T) Reaction rate mi, mt, and mf Mass at specific times (%) p(μ) Temperature integral R2 Correlation coefficient T1, T2, T3, T4, and T5 Characteristic temperature (°C) An Avrami–Eroféev model c Adjusted coefficient * Bei Li [email protected] 1
School of Chemical Engineering, Dalian University of Technology, Dalian 116024, Liaoning, People’s Republic of China
State Key Laboratory of Coal Mine Safety Technology, China Coal Technology & Engineering Group Shenyang Research Institute, Fushun 113122, Liaoning, People’s Republic of China
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f(α) Reaction model based on conversion I(μ) Temperature integral lnA The napierian logarithm of preexponential factor (s−1) 1/n Kinetic exponents in the AvramiEroféev model R Universal gas constant (J mol−1 K−1) T Absolute temperature (K) Greek symbols α Conversion degree μ Variable parameter β The heating rate (°C min−1) 𝛺(Eα ) Objective function Subscripts i Initial time f Final time t The instantaneous time Abbreviations CG Coal gangue daf Dry ash-free basis
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Vol.:(0123456789)
FWO Flynn–Wall–Ozawa RC Raw coal SEM Scanning electron microscope XRD X-ray diffrac
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