Insight into the intrinsic reaction of brown coal oxidation at low temperature: Differential scanning calorimetry study

Li, Zhengfeng; Zhang, Yulong; Jing, Xiaoxia; Zhang, Yanli; Chang, Liping

doi:10.1016/j.fuproc.2015.07.030

Cited by 54 publications

(16 citation statements)

References 28 publications

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“…This was an exothermic process and the exothermic effect gradually increased when higher heating rates occurred. The DSC curve at 20 K/min in the air atmosphere was stronger than the exothermic effect at 40 K/min, which may be due to experimental errors due to high heating rates [38]. In the air atmosphere, two peaks can be observed in the DSC curve and the more severe peak appeared above 300 °C corresponding to the process of volatile pyrolysis in the DTG curve.…”

Section: Dsc Analysesmentioning

confidence: 89%

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Comparison of Combustion and Pyrolysis Behavior of the Peanut Shells in Air and N2: Kinetics, Thermodynamics and Gas Emissions

Xiao

Fang

et al. 2020

Sustainability

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The influences of four heating rates on the combustion and pyrolysis behavior in the N2 and air atmosphere were investigated by the Fourier transform infrared spectrometry (FTIR) and thermogravimetric (TG) analysis. the distributed activation energy model (DEAM) and Flynn-Wall-Ozawa (FWO) were used to estimate Ea and A, ΔH, ΔG and ΔS. Experimental results showed that the similar thermal behavior emerged, but the temperatures in the air and N2 atmospheres representing the end of the reaction were about 500 °C and 550 °C, respectively. The results of FTIR showed the peak positions were basically the same, but the concentrations of aromatics, aldehydes and ketones produced by pyrolysis in the N2 atmosphere were higher. When the heating rate was 20 K/min, the comprehensive combustion parameters were 56.442 and 6.871 × 10−7%2/(min2• K3) in the air and N2 atmospheres, respectively, indicating that the peanut shells had great potential to become bioenergy.

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Section: Dsc Analysesmentioning

confidence: 89%

Section: Dsc Analysesmentioning

confidence: 90%

Comparison of Combustion and Pyrolysis Behavior of the Peanut Shells in Air and N2: Kinetics, Thermodynamics and Gas Emissions

Xiao

Fang

et al. 2020

Sustainability

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show abstract

“…( 17)), which is not able to describe the different characteristics of the biological reaction and chemical oxidation, especially their different active temperature ranges and the transition mechanism: the heat generated from biological reaction accumulates and then triggers chemical oxidation, which eventually leads to the smouldering fires. This is a two-stage process, where the low temperature reaction serves as the step to the high temperature reaction (Li et al 2016;Yuan et al 2020b).To demonstrate the multi-step effect during self-heating ignition of peat wildfires and justify the application of the scheme at field-scale scenarios, the comparison between the multi-step scheme and 1-step scheme are given in the latter sections.…”

Section: Chemical Kineticsmentioning

confidence: 99%

Spontaneous ignition of soils: a multi-step reaction scheme to simulate self-heating ignition of smouldering peat fires

Han

Restuccia

Rein

2021

Int. J. Wildland Fire

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As organic porous soil, peat is prone to self-heating ignition, a type of spontaneous initiation of fire that can take place at ambient temperatures without an external source. Despite the urgency to tackle peat fires, the understanding of the self-heating ignition of peat is insufficient. In this study, a computational model that integrates the mechanisms of heat transfer, mass transfer and chemistry is incorporated with a three-step reaction scheme that includes drying, biological reaction and oxidative oxidation to simulate the self-heating ignition of smouldering peat. The model is first validated against 13 laboratory-scale experiments from literature. For critical ignition temperature (Tig), the model gives accurate predictions for all experiments with a maximum error of 5°C. The validated model is then upscaled to predict Tig for field-size peat soil layers and compared with the predictions using a one-step scheme. The three-step scheme is shown to give more reliable predictions of Tig than the one-step scheme. According to the simulation results, for a 1.5-m-deep peat layer, self-heating ignition can occur at an average ambient temperature above 40°C. This is the first time that a multi-step scheme is used to simulate the self-heating ignition of peat, aiming to help in the prevention and mitigation of these wildfires.

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“…Moreover, when the coal temperature was just greater than 70 • C, the increase of the coal mass became slow. With a further increase in coal temperature, the increase rate of the coal mass rapidly increased [29,30].…”

Section: Investigation Of the Mechanistic Actionmentioning

confidence: 99%

Study on the Effect of Extraneous Moisture on the Spontaneous Combustion of Coal and Its Mechanism of Action

Wang

Zhang

et al. 2020

Energies

Self Cite

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It is imperative to have an in-depth understanding of the effect of extraneous moisture on the spontaneous combustion of coal not only for the control and prevention of coal spontaneous combustion in the coal mining industry, but also for the optimization design and application of the technological process. In this study, the type of moisture in a coal body has been redefined for the first time from the perspective of disaster prevention and control, i.e., original occurrence of moisture in the coal matrix and the extraneous moisture from the technological process. A suit of coal bodies with different extraneous moisture was prepared by soaking long-flame coal with a low water content. Using a temperature-programmed oxidation test, the effects of extraneous moisture on the temperature increase rate of coal bodies and the emission characteristics of gaseous products during coal spontaneous combustion were studied. Moreover, combined with the characterization of thermal analysis and of pore structure test, the action the mechanism of extraneous moisture on the coal spontaneous combustion process was also explored. The experimental results indicated that the effect of the extraneous moisture content varied with the development of coal spontaneous combustion. In the slow oxidation stage, extraneous moisture played a physical inhibition role in the coal oxidation. In the accelerated oxidation stage, extraneous moisture exhibited a catalytic effect on the coal–oxygen reaction or directly participated in the reaction. After entering the rapid oxidation stage, a delayed effect appeared. When the coal temperature exceeded 180 °C, the spontaneous combustion characteristics of coals with different initial moisture contents gradually tended to achieved balance.

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Insight into the intrinsic reaction of brown coal oxidation at low temperature: Differential scanning calorimetry study

Cited by 54 publications

References 28 publications

Comparison of Combustion and Pyrolysis Behavior of the Peanut Shells in Air and N2: Kinetics, Thermodynamics and Gas Emissions

Comparison of Combustion and Pyrolysis Behavior of the Peanut Shells in Air and N2: Kinetics, Thermodynamics and Gas Emissions

Spontaneous ignition of soils: a multi-step reaction scheme to simulate self-heating ignition of smouldering peat fires

Study on the Effect of Extraneous Moisture on the Spontaneous Combustion of Coal and Its Mechanism of Action

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