Showing papers on "Spontaneous combustion published in 2018"
TL;DR: In this article, a multi-index experimental system for estimating various factors during coal oxidation (heating) and combustion and analyzed the characteristic temperature, index gases, and EMR signals.
166 citations
TL;DR: In this paper, a new method, DSC Inflection Point (DSCIP), was proposed to determine the coal auto-ignition temperature (CAIT), and the results demonstrated that the heat flux curve of coal spontaneous combustion can be well fitted using Gaussian mixture model.
110 citations
TL;DR: In this paper, the intrinsic properties and spontaneous combustion tests of 28 selected coal and coal-shale samples were conducted and a relationship between the two has been established, and the experimental results show that intrinsic properties of these materials complement to the spontaneous combustion liability tests results.
Abstract: Spontaneous combustion of coal is a well-known phenomena around the globe. Apart from the coal itself, burning coal-shales is becoming a problem in the South African coal mines. Serious incidents of spontaneous combustion have been reported as a result of self-heating of reactive coal-shales. The intrinsic properties and spontaneous combustion tests of 28 selected coal and coal-shale samples were conducted and a relationship between the two has been established. Intrinsic properties were obtained by using the proximate and ultimate analysis, and spontaneous combustion liability tests results were obtained by using the Wits-Ehac and Wits-CT indices. The experimental results show that intrinsic properties of these materials complement to the spontaneous combustion liability tests results. Comparative analyses of intrinsic properties and spontaneous combustion characteristics indicate similarities between the mechanism of coal oxidation and that of the oxidative processes undergone by coal-shales. For the tested samples, coal samples have a higher intrinsic spontaneous combustion reactivity rating than the coal-shales. Furthermore, an increase in carbon, moisture, hydrogen, volatile matter, nitrogen and a decrease in ash content indicate an increased proneness to self-heating. The concentration of pyrite found in the coal-shales accelerates self-heating. The event of spontaneous combustion can occur if coal-shales absorb sufficient oxygen when subjected to atmospheric conditions.
103 citations
TL;DR: In this paper, three commercial inhibitors were investigated for their suitability in preventing the spontaneous combustion of noncaking coal (NCC) and gas coal (GC), two coals of low metamorphic grades.
102 citations
TL;DR: In this article, a particle swarm optimization (PSO) was employed to optimize the parameters of support vector regression (SVR) model to predict the temperature of coal spontaneous combustion based on the gases concentration in the gob and distance from the measuring points to the working face.
97 citations
TL;DR: In this article, the authors investigate the evolutions of coal mass, heat and gaseous products during coal spontaneous combustion and conclude that the mass loss rate in combustion stage was much higher than other stages and the major coal mass consumed at this stage.
Abstract: Spontaneous combustion, if not eradicated immediately, may lead to coal ignition and even a full-blown fire. An understanding of the characteristics of coal oxidation under various environmental conditions is conducive to the reveal of the mechanism and the prevention of coal spontaneous combustion. TG/DSC–FTIR coupling technology was employed to investigate the evolutions of coal mass, heat and gaseous products during coal spontaneous combustion. The experiments conclude that the mass loss rate in Combustion Stage was much higher than other stages and the major of coal mass (over 80%) was consumed at this stage. As the oxygen concentration decreased, the combustion of coal was evidently postponed and the exothermic region shifted to a higher temperature. Correspondingly, the temperatures at which productions of CO and CO2 reached to the maximum were deferred as well. Experimental results also indicated that heating rates behaved differently before and after the ignition temperature. The mass loss rates of coal were independent of heating rates before ignition temperatures but obviously expanded and moved to higher temperatures after exceeding the ignition temperature. Additionally, with the increase of the heating rates, the exothermic region shifted to higher temperatures and the release of CO and CO2 were delayed and reached to the maximum in a longer time.
91 citations
TL;DR: In this paper, the authors conducted isothermal oxidation experiments on raw and pyrolyzed coal samples to investigate the influence of the content of oxygen-containing functional groups, pyroxene temperature, oxidation temperature, particle size, and pyrosene-oxidation times on the oxidation characteristics of coal samples.
88 citations
TL;DR: In this paper, a large-scale 2-ton experimental furnace was constructed to implement an oxidation experiment by using a Dafosi coal sample, and the aim was to simulate the spontaneous combustion of coal at low temperatures.
81 citations
TL;DR: In this paper, a numerical method for estimating a reference flame speed, sR, is proposed that is valid for laminar flame propagation at autoignitive conditions, and two isomer fuels are considered to test this method: ethanol, which in the considered conditions is a single-stage ignition fuel; and dimethyl ether, which has a temperature-dependent single- or two-stage ignited fuel and a negative temperature coefficient regime for τ.
79 citations
TL;DR: In this paper, the reaction mechanism of spontaneous coal combustion and the indicators for forecasting this risk, reaction characteristics of free radicals and functional groups during low-temperature oxidation of coal with different ranks were analyzed by electron spin resonance and Fourier transform infrared (FTIR) spectroscopy.
77 citations
TL;DR: In this paper, the relationship between oxygen consumption and gaseous product emissions during coal self-heating was studied, and an evaluation index was proposed to assess the state of coal spontaneous combustion.
TL;DR: In this paper, an investigation of the effects of igneous intrusions on the physicochemical structure and spontaneous combustion characteristics of coal is important for safe production in coal mines, and the results of XRD, XPS, SEM, N2 adsorption and mercury intrusion porosimetry were collected from Daxing Mine.
TL;DR: In this paper, a simulation of a temporal jet between n-dodecane and diluted air undergoing spontaneous ignition at conditions relevant to low-temperature diesel combustion is presented.
TL;DR: Wang et al. as discussed by the authors studied the spontaneous combustion characteristics of coal gangues in the Dangtong (DT) and Jincheng (JC) mining areas of Shanxi Province, China.
TL;DR: In this paper, an integrated experiment system for testing characteristic parameters of coal spontaneous combustion was designed and set up, and the characteristic parameters were accurately tested through the spontaneous combustion heating experiment on large-volume coal.
TL;DR: In this article, a self-designed experimental platform was used to determine the influence of spontaneous coal combustion on methane migration in the goaf, and the effect of different ventilation velocities at the mining face on the methane migration was studied.
TL;DR: Zn/Mg/Al-CO3 LDHs have excellent physical and chemical properties and are thus widely and effectively used to inhibit spontaneous coal combustion as mentioned in this paper, which can be used to prevent the occurrence of severe accidents caused by coal combustion.
TL;DR: In this paper, the influence of Hydrothermal Dewatering (HTD) on low-rank coals (LRCs) and combustion characteristics was studied. And the results indicated that the conversion of LRCs near to high-rank coal (HRCs).
TL;DR: In this article, a safer method to investigate the IL's thermal hazards was proposed to explore the overall spontaneous combustion under upset conditions, and the results demonstrate that the suitable combination of anion and cation might yield energetic ILs.
TL;DR: In this paper, a new type of apparatus for efficiently sublimating dry-ice has been developed independently, which would yield more than 205 times as much carbon dioxide as dryice under normal condition.
TL;DR: In this article, the authors used particle flow numerical simulation software PFC3D for the simulation of the collapse of overlying rock strata with the actual situation of the 3308 working face of Liangbaosi Coal Mine in China.
Abstract: The air leakage in goaf can easily lead to disasters such as spontaneous combustion process of residual coal and gas accumulation, threatening production safety in underground coal mines. In order to study and master air leakage flow field distribution in goaf, the particle flow numerical simulation software PFC3D is used for the simulation of the collapse of overlying rock strata with the actual situation of the 3308 working face of Liangbaosi Coal Mine in China taken as an example. The quantitative porosity data of goaf are extracted and imported into FLUENT to simulate the air leakage flow field in goaf. The results show that (1) the porosity in the central part and near the working face of goaf is relatively large. With the increase of the length of goaf, the porosity decreases, and with the increase of the height of goaf, the porosity in the two cross headings is first larger than that in the central part and then smaller than that in the central part. (2) The data of air flow along the dip direction of working face obtained through the CFD numerical simulation is consistent with the actual measurement results basically, which validate the simulation. (3) The main air leakage occurs in the range of 0–10 m along the dip direction of working face. In the case of relatively large air supply rate, the residual coal spontaneous combustion area in goaf is far from the working face and the spontaneous combustion area becomes relatively large, resulting in increased risk.
TL;DR: In this paper, three imidazolium-based ionic liquids (ILs) and distilled water flushing were used to treat lignite subsamples to ascertain the inhibiting effect of ILs on the spontaneous combustion characteristics.
TL;DR: In this paper, a bench-scale flame-retardant cable, consisting of the outer PVC sheath, middle XLPE insulation, and inner copper core, was heated uniformly inside a novel cylindrical heating chamber.
TL;DR: Wang et al. as discussed by the authors focused on a small abandoned coal mine in Shanxi Province, China, using surface-based radon detection, and three abnormal temperature areas (A, B, C and a potential abnormal temperature area (D)) were identified.
TL;DR: In this article, a new experimental procedure and a mathematical model were developed based on the standard R70 adiabatic oxidation method to test and quantify the effect of heat of rewetting on the propensities for spontaneous combustion of coals, especially low rank coals.
TL;DR: In this paper, thermal properties of metamorphic-grade coal were investigated using X-ray diffractometry and the results indicated that the trend in thermal diffusivity was opposite to that of crystallinity.
TL;DR: In this paper, a grey correlation analysis method was used to analyze the relationship between the samples' growth temperature and intrinsic properties, and a quasi-Newton method and general global optimization model were adopted to derive a predictive relationship for spontaneous coal combustion.
TL;DR: In this article, the impact of periodical weighting by introducing weighting intervals into the coupled model of coal self-heating in gobs was studied, and it was shown that the spontaneous combustion zone appears to be an asymmetric structure: it moves deeper on the air-intake side but closer to the working face on air-return side.
Abstract: The spontaneous combustion “three-zone” of a gob is one of the key fields in the study of the self-heating of residual coal and it is a coupled result of several factors. This paper studies the impact of periodical weighting by introducing weighting intervals into the coupled model of coal self-heating in gobs. The simulated result under field conditions matches well with the measured oxygen concentration distribution in situ. Further simulations of the validated model have been carried on under different weighting intervals, which reveals that the “three-zone” appears to be an asymmetric structure: it moves deeper on the air-intake side but closer to the working face on the air-return side, and the “three-zone” is wider in the middle and tapers when extending to the walls of the gob. The greater weighting interval makes the “three-zone” move deeper into the gob, and the spontaneous combustion zone declines in width. In addition, the highest temperature point proceeds into the depth of the gob at a decreasing speed as the weighting interval rises. This study may be a guide for the problem related to the spontaneous combustion of residual coal in gobs and for the optimization of the ventilation mode in the working face.
TL;DR: In this paper, a dimensionless parameter of tubes, defined as the ratio of the tube length to the tube diameter, was introduced to describe the effect of tube size on spontaneous ignition.