Study on thermochemical kinetic characteristics and interaction during low temperature oxidation of blended coals

Chen, Gang; Ma, Xiaoqian; Lin, Musong; Lin, Yousheng; Yu, Zhaosheng

doi:10.1016/j.joei.2014.09.007

Cited by 50 publications

(15 citation statements)

References 23 publications

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“…The weight loss characteristic of bitumite is similar to oil shale, while the temperature is lower than 550°C. The TG curves of blends samples of oil shale and bitumite (OS3:BT7) and oil shale and lignite (OS3:IG7) in Figure 2 are all laid between the individual sample curves as a symbol of no significant changes in blended samples' pyrolysis in weight loss, but the synergistic effect still remains unrevealed [8].…”

Section: Temperature Programmed Pyrolysis (The First Stage)mentioning

confidence: 99%

“…In the present investigation, thermo‐gravimetric analysis was introduced to reveal the co‐pyrolysis characteristics of coal and oil shale, providing a theoretical foundation for further development and utilization of oil shale . Some data indicate that a mixture of oil shale with coal can be successfully converted into liquids using co‐pyrolysis techniques .…”

Section: Introductionmentioning

confidence: 99%

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CO₂ gasification characteristics of nascent pyrolyzed particles from coals and oil shale

2017

Int. J. Energy Res.

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Summary In this work, the co‐pyrolysis characteristics of oil shale with two typical coals, bitumite and lignite, and the co‐gasification characteristics of the mixture pyrolyzed fuels were studied via thermo‐gravimetric analysis. The individual fuels and mixture fuels were first pyrolysis in N2 atmosphere to specified temperature (450, 550, and 620 °C) at the heating rate of 20, 30 and 40 °C/min, respectively, and then maintained at the given temperature for 20 min before converted to CO2 ambient to conduct the CO2 gasification tests. The kinetic behavior and effects of both fuel types and pyrolysis temperature were investigated. The shoulder peak at around 550 °C observed in the derivative of weight loss derivative thermogravimetry analysis (DTG) curve during the pyrolysis of oil shale has confirmed the existence of specific reactions of oil shale at around 550 °C that leads to a sharp trough in the differential curves of co‐pyrolysis with coals and the unusual change in activation energies of gasification. In isothermal pyrolysis stage, oil shale lost its vast majority of organic matters at the temperature lower than 550 °C. The escape of pyrolysis gas and liquids in the coals is much harder than that in oil shale. The interaction between oil shale and bitumite was too weak to discriminate both in the pyrolysis and CO2 gasification process. The variation of the particle surface structure caused by the releasing of volatile gases is strongly affected by the reaction rate and temperature. Quick volatile decomposition and gas releasing lead to the increase of surface area, decrease of the average pore diameter as well as the uniformization of the pore structure, while the higher temperature results in the blockade and merging of fine pores. The two factors lead to the greatest mass loss rate in the pyrolyzed particles obtained at 550 °C in temperature programmed CO2 gasification stage. Two model‐free methods, Friedman method and Flynn–Wall–Ozawa method, were used to extract kinetic parameters from the experimentally determined pyrolyzed fuel conversions. The volatile contend has a significant influence on the fixed carbon conversion during the partially pyrolyzed particles' CO2 gasification. In this study, significant interactions existed in co‐thermal utilization, both pyrolysis and CO2 gasification, of oil shale and lignite. It is therefore surmised that co‐gasification of pyrolyzed lignite and oil shale may represent a feasible, practical route to high‐efficiency utilization of these fuels. Copyright © 2017 John Wiley & Sons, Ltd.

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Section: Temperature Programmed Pyrolysis (The First Stage)mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

CO₂ gasification characteristics of nascent pyrolyzed particles from coals and oil shale

2017

Int. J. Energy Res.

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“…Correlation coefficient (dimensionless) O daf O content of air-dried basis (%) S daf S content of air-dried basis (%) T Thermokinetic temperature (K) T 1 First characteristic temperature, critical temperature (°C) T 2 Second characteristic temperature, active temperature (°C) T 3 Third characteristic temperature, pyrolysis temperature (°C) T 4 Fourth characteristic temperature, ignition temperature (°C) T 5 Fifth characteristic temperature, burned-out temperature (°C)…”

Section: List Of Symbolsmentioning

confidence: 99%

“…Coal is an indispensable resource not only in China but also worldwide [1,2]. China is the largest coal-producing country [3,4], and the problem of coal spontaneous combustion [5][6][7] is gaining increasing attention.…”

Section: Introductionmentioning

confidence: 99%

Thermal behavior and microcharacterization analysis of second-oxidized coal

Deng

Zhao

Huang

et al. 2016

J Therm Anal Calorim

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Among coal-producing countries, China has witnessed the highest frequency and severity of coal fires. During mining in the re-mining face and the lower part of the thick coal seam (or coal seam group), second or multiple oxidations of the residual coal can readily occur in mined-out areas, severely increasing the risk of coal fires. The study of multiple oxidations of coal aids in the early detection of spontaneous combustion of remaining coal in the mined-out areas. The characteristics of coal fires are demonstrated using fresh coal samples (first-oxidized coal) and oxidized coal samples (second-oxidized coal) from four different ranks of coals. Proximate and elemental analysis, Fourier transform spectroscopy, and thermogravimetry-differential scanning calorimetry were adopted to investigate the quality, microcharacteristics, characteristic temperatures, and apparent activation energy of second-oxidized coal. In addition, the effect of spontaneous combustion at heating rates of 5.0, 10.0, and 15.0°C min -1 was studied. Compared with the four samples of first-oxidized coal, those of second-oxidized coals cause fire easily under the same conditions. List of symbolsA, A k Pre-exponential factor (s -1 ) A ad Ash content in air-dried basis (%) bHeating rate (°C min -1 ) C daf C content of air-dried basis (%) da/dt Conversion rate (s -1 ) E a , E k Apparent activation energy (kJ mol -1 ) f(a)Function of degree of conversion (dimensionless) H daf H content of air-dried basis (%) M ad Moisture in air-dried basis (%) N daf N content of air-dried basis (%) R Universal gas constant (8.314 J mol -1 K -1 ) r Correlation coefficient (dimensionless) O daf O content of air-dried basis (%) S daf S content of air-dried basis (%) T Thermokinetic temperature (K) T 1 First characteristic temperature, critical temperature (°C) T 2 Second characteristic temperature, active temperature (°C) T 3 Third characteristic temperature, pyrolysis temperature (°C) T 4 Fourth characteristic temperature, ignition temperature (°C) T 5 Fifth characteristic temperature, burned-out temperature (°C)

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“…As the reaction proceeds, the intensity of the coal oxidation strengthens, thus resulting in the gradually increase of heat release (Shi et al, 2021a). When the heat release is greater than the heat loss, the heat gradually gathers and further cause spontaneous combustion (Chen et al, 2015). As one of the thermophysical parameters characterizing the heat transfer ability of a research object (Deng et al, 2017a), the TC can well explain the heat transfer law in the process of spontaneous combustion of residual coal in goaf.…”

Section: Introductionmentioning

confidence: 99%

Effective thermal conductivity of loose residual coal in goaf: Comparative analysis of experiment and model

Zhang

Shen

Wan

2022

Energy Exploration & Exploitation

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The effective thermal conductivity (ETC) model of loose residual coal in goaf is a method to study the heat transfer law of spontaneous combustion in goaf. In order to study the effect of coal particle size and ambient temperature on heat transfer, coal samples of different sizes were taken from the FuSheng (FS) mine, and the void fraction, the thermal conductivity (TC) of the residual coal under different ambient temperature were tested. Additionally, four types of ETC models of loose residual coal in goaf were obtained and the average relative errors of the TC were analyzed. The results showed that the void fraction, the coal particle size and ambient temperature have different effects on the spontaneous combustion of the residual coal. The effect of coal sample size on the heat transfer is 100 times that of the ambient temperature. The changes in the ETC and average relative error of the different models were consistent. The heat transfer in the spontaneous combustion of residual coal has a direct relationship with the spatial distribution and heat transfer modes of the loose residual coal in the goaf.

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Study on thermochemical kinetic characteristics and interaction during low temperature oxidation of blended coals

Cited by 50 publications

References 23 publications

CO₂ gasification characteristics of nascent pyrolyzed particles from coals and oil shale

CO₂ gasification characteristics of nascent pyrolyzed particles from coals and oil shale

Thermal behavior and microcharacterization analysis of second-oxidized coal

Effective thermal conductivity of loose residual coal in goaf: Comparative analysis of experiment and model

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Study on thermochemical kinetic characteristics and interaction during low temperature oxidation of blended coals

Cited by 50 publications

References 23 publications

CO2 gasification characteristics of nascent pyrolyzed particles from coals and oil shale

CO2 gasification characteristics of nascent pyrolyzed particles from coals and oil shale

Thermal behavior and microcharacterization analysis of second-oxidized coal

Effective thermal conductivity of loose residual coal in goaf: Comparative analysis of experiment and model

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CO₂ gasification characteristics of nascent pyrolyzed particles from coals and oil shale

CO₂ gasification characteristics of nascent pyrolyzed particles from coals and oil shale