Showing papers on "Spontaneous combustion published in 2016"
TL;DR: In this article, a parametric study was performed to understand the effects of pressure, temperature, equivalence ratio along with geometric factors such as orifice diameter and spark position on the ignition mechanisms and probability.
156 citations
TL;DR: China's coal gangue production growth from 1992 to 2013 show an obvious growth since 2002, which may indicate that Chinese coalgangue has become a potential source of air pollution, which should be included in emission inventories.
141 citations
TL;DR: In this paper, a self-designed temperature-programmable experimental system was developed to investigate the spontaneous combustion characteristics of partially oxidized coal and the differences between the oxidation characteristics of a fresh and a partially oxidised coal sample were studied.
133 citations
TL;DR: In this paper, a fully coupled coal-oxygen-heating model for spontaneous combustion was extended into a symbiotic model between coal gas flow and spontaneous combustion, which was achieved through the introduction of an accumulative gas release function in the set of coupled governing equations.
130 citations
TL;DR: The method of added diphenylamine can inhibit the self-oxidation of coal effectively, the action mechanism of diphenyamine was analyzed by free radical chain reaction, and this research can offer new method for the development of new flame retardant.
Abstract: Study on the mechanism of coal spontaneous combustion is significant for controlling fire disasters due to coal spontaneous combustion. The free radical reactions can explain the chemical process of coal at low-temperature oxidation. Electron spin resonance (ESR) spectroscopy was used to measure the change rules of the different sorts and different granularity of coal directly; ESR spectroscopy chart of free radicals following the changes of temperatures was compared by the coal samples applying air and blowing nitrogen, original coal samples, dry coal samples, and demineralized coal samples. The fragmentation process was the key factor of producing and initiating free radical reactions. Oxygen, moisture, and mineral accelerated the free radical reactions. Combination of the free radical reaction mechanism, the mechanical fragmentation leaded to the elevated CO concentration, fracturing of coal pillar was more prone to spontaneous combustion, and spontaneous combustion in goaf accounted for a large proportion of the fire in the mine were explained. The method of added diphenylamine can inhibit the self-oxidation of coal effectively, the action mechanism of diphenylamine was analyzed by free radical chain reaction, and this research can offer new method for the development of new flame retardant.
101 citations
01 Jan 2016
TL;DR: This chapter will describe how heating of a solid fuel leads to flaming ignition and the presence of a source of heat decoupled from the solid and fuel gasification will be assumed throughout the chapter.
Abstract: This chapter will describe how heating of a solid fuel leads to flaming ignition. The discussion will be centred on flaming ignition of solid fuels but will not address smouldering or spontaneous ignition since these subjects will be covered in Chaps. 19 and 20 respectively. Thus, the presence of a source of heat decoupled from the solid and fuel gasification will be assumed throughout the chapter.
92 citations
TL;DR: In this article, a lignite from Shengli mine in Chinese Inner Mongolia was upgraded by hydrothermal dewatering (HTD), and the effects of the HTD process on the solid product yield and the removal rate of elements, organics and inorganics in this coal were determined.
89 citations
TL;DR: In this article, in-situ coal samples from different coalfields of India were collected for proximate, ultimate, and petrographic analysis; crossing point temperature; flammability temperature; Olpinski index; wet oxidation potential analysis; and differential thermal analysis to ascertain the proneness of coal to spontaneous combustion.
86 citations
85 citations
TL;DR: In this article, a new kind of compound material composed of compound foaming agent (CFA) and high water absorbency gel (HWAG) for controlling the spontaneous combustion of coal in coal mine was researched and developed.
Abstract: A new kind of compound material—foamed gel composed of compound foaming agent (CFA) and high water absorbency gel (HWAG) and formed by physical and mechanical stirring—for controlling the spontaneous combustion of coal in coal mine was researched and developed. It makes use of the all-around properties of foam and gel to control the spontaneous combustion of coal in coal mine. The composition, preparation, and controlling mechanisms of foamed gel were analyzed. To optimize the characterizations of the foamed gel, the optimal CFA concerning foaming ability and mixed ratios of single foaming agents, mass concentration, and salt-resistance performance as well as the optimal HWAG concerning optimal synthesis parameters, Fourier transform infrared spectroscopy, thermogravimetric property, and foam stability were analyzed. Meanwhile, characterizations including microstructure and controlling spontaneous combustion of coal of foamed gel were studied. The results were best when the mass fraction of compound of modification alkyl polyglucoside (APG) and sodium dodecyl sulfate (SDS) is 0.9%, the mixed ratio of APG versus SDS is 4:1, the mass fraction of HWAG is 0.4%, and methylenebis acrylamide concentration, ammonium persulfate concentration, and mass fraction ratio of soluble starch:acrylic acid of HWAG synthesis are 0.05%, 0.5%, and 1:10, respectively. This is the ideal foamed gel. The success preparation of foamed gel and the microstructures differences between CFA and foamed gel are confirmd by the microstructures analysis results of CFA and foamed gel simultaneously. Moreover, foamed gel can effectively seal air leakages, prolong moisturizing time of coal, markedly enhance cooling effect on coal of moisture, and efficaciously reduce the rate of coal oxidation reaction and the heating rate to control the spontaneous combustion of coal in coal mine.
72 citations
TL;DR: In this paper, a model of high drill holes extraction (HDHE) is established and the methane concentration distribution and air leakage under four different drainage pressures (below atmospheric) were determined.
TL;DR: In this paper, a numerical simulation method was developed for a large-area spontaneous combustion fire in the goaf of the 12306 fully caved face at Bulianta coal mine in the Shendong mining area.
Abstract: Goaf fires are serious hazards in coal mines, especially in the closely spaced shallow coal seams of northwestern China, where spontaneous combustion of coal occurs frequently. A numerical simulation method was developed for a large-area spontaneous combustion fire in the goaf of the 12306 fully caved face at Bulianta coal mine in the Shendong mining area. Theoretical and geometrical models were developed to rapidly locate the high-temperature zone of the fire by simulating the oxygen concentrations and temperature distributions in the goaf. The effectiveness of liquid nitrogen perfusion was also assessed. Field observations showed that the results from the theoretical study were accurate and reliable. The fire was rapidly extinguished by pouring liquid nitrogen at a high flow rate into the high-temperature region of the fire. CO concentration dropped from >10,000 to 160 to about 20 °C. The 22305 face below the 12306 goaf was subsequently safely reopened and quickly returned to production.
TL;DR: In this paper, a controlled-release inhibitor is proposed for coal self-heating, which is made from the synthesis of halogen inhibitors, catechin, copolymer, solvent and surfactant.
Abstract: The existing coal self-heating inhibitors usually have the shortcomings of short effective time and low inhibition effect. This study proposed a kind of controlled-release inhibitor and analyzed their differences in inhibition effects compared with existing inhibitors on coal self-heating. The controlled-release inhibitor is made from the synthesis of halogen inhibitors, catechin, copolymer, solvent and surfactant. The controlled-release inhibitor will not break down quickly until coal temperature reaches a value about 70 °C and can continually inhibit the process of coal self-heating after a longer time. The crossing point temperature, propensity to spontaneous combustion and CO generation of coal samples processed by different inhibition methods were tested separately based on an oxidation dynamic method. The results show that the controlled-release inhibitor can inhibit the coal self-heating more effectively for a longer time than existing halogen inhibitors. This study provides a new method for more efficient prevention of coal spontaneous combustion.
TL;DR: Using simultaneous thermal analysis-Fourier transform infrared spectroscopy, Wang et al. as mentioned in this paper analyzed the oxidation and exothermic behaviors of six types of coal based on various factors, such as characteristic temperature, heat release, and gas release.
Abstract: Using simultaneous thermal analysis-Fourier transform infrared spectroscopy, we analyzed the oxidation and exothermic behaviors of six types of coal based on various factors, such as characteristic temperature, heat release, and gas release, to establish a foundation for prevention and control of spontaneous combustion in six types of coal in China. According to the experimental results, a decrease in the metamorphic grade of coal causes an increase in the amount of volatile matter, the heat release rate, and the total heat released. The apparent exothermic onset temperature and initial temperature for the release of H2O, CO2, CO, and CH4 during the nonisothermal oxidation process of coal took place earlier, indicating that the oxidation reaction occurred more easily in lower-grade coal, increasing the hazards of spontaneous combustion. Moreover, when decomposing, coal releases large amounts of CH4, which may cause gas explosions in coal mines. Therefore, technology facilitating the detection of CH4 and prevention of explosions should be developed for use in the coal industry.
TL;DR: The results show that the presence of the varying cross-section geometries can significantly promote the occurrence of spontaneous ignition at high-pressure hydrogen release via cylindrical tubes with varyingCross-section.
TL;DR: In this article, the authors investigated spontaneous ignition and subsequent flame propagation of high-pressure hydrogen release via a tube into air using pressure records, flame detection and direct high-speed photographs and found that as the burst pressure increases the likelihood of spontaneous ignition increases and the initial ignition is closer to the burst disk.
TL;DR: In this paper, a multi-dimensional model was applied to investigate the influence of combustion regimes on heat transfer losses in internal combustion engines, and the results indicated that the total heat transfer loss of conventional diesel combustion is the largest among the three combustion regimes due to direct interaction of the high-temperature flame with the piston wall.
Abstract: A multi-dimensional model was applied to investigate the influence of combustion regimes on heat transfer losses in internal combustion engines. By utilizing improved turbulence and heat transfer sub-models, the combustion and heat transfer characteristics of the engine were satisfactorily reproduced for operation under conventional diesel combustion, homogeneous charge compression ignition, and reactivity controlled compression ignition regimes. The results indicated that the total heat transfer losses of conventional diesel combustion are the largest among the three combustion regimes due to the direct interaction of the high-temperature flame with the piston wall, while the heat transfer losses of reactivity controlled compression ignition are the lowest and nearly are independent of combustion phasing because of the avoidance of high-temperature regions adjacent to the cylinder walls. Compared to conventional diesel combustion, homogeneous charge compression ignition shows more potential for the reduc...
TL;DR: In this article, an experimental study on flow characteristics and spontaneous ignition produced by pressurized hydrogen release through an Omega-shaped tube into atmosphere was conducted, where the influence of geometry of downstream tube on the shock waves and the spontaneous ignition of hydrogen release was investigated.
TL;DR: In this article, the results of combustion instability characteristics of H2/CO/CH4 synthetic gases and synthetic natural gases by testing a scale-downed industrial GE7EA gas turbine that features a partially-premixed swirl-stabilized combustion were presented.
TL;DR: In this article, a mean value control-oriented model of RCCI is developed by combining the auto-ignition model, the burn duration model, and a Wiebe function to predict combustion phasing.
Abstract: Reactivity-controlled compression ignition (RCCI) is a promising combustion strategy to achieve near-zero NOx and soot emissions and diesel-like efficiencies. Model-based control of RCCI combustion phasing requires a computationally efficient combustion model that encompasses factors such as injection timings, fuel blend composition, and reactivity. In this work, physics-based models are developed to predict the onset of auto-ignition in RCCI and to estimate the burn duration based on an approximation of the spontaneous ignition front speed. A mean value control-oriented model of RCCI is then developed by combining the auto-ignition model, the burn duration model, and a Wiebe function to predict combustion phasing. The control-oriented model is parameterized and validated using simulation data from an experimentally validated, detailed computational fluid dynamics combustion model developed using the KIVA-3V code. The validation results show that the control-oriented model can predict the start of combust...
TL;DR: In this paper, the authors assumed that rapid spontaneous combustion of coal in stockpile will start from the heat up of coal fines on the surface of the stockpile by the heat supplied from the sun and moist air, and then direct measurement of possible temperature increase by the adsorption of water vapor on coal from ambient atmosphere was undertaken by using three kinds of brown coal/lignites and a bituminous coal.
Abstract: Low rank coals are susceptible to spontaneous combustion, because oxidation rate of low rank coals are higher than that of high rank coals. Even low rank coals, however, must be heated over a critical temperature before spontaneous combustion starts. This work assumed that rapid spontaneous combustion of coal in stockpile will start from the heat up of coal fines on the surface of the stockpile by the heat supplied from the sun and moist air. Then direct measurement of possible temperature increase by the adsorption of water vapor on coal from ambient atmosphere was undertaken by using three kinds of brown coals/lignites and a bituminous coal. When about 100 mg of each brown coal pre-dried at 80 °C and cooled to 28 °C were exposed to an ambient and stationary atmosphere of 28 °C with 67–77% relative humidity, the coal temperatures increased up to 40–43 °C in a minute or so. When the brown coals pre-dried and cooled to 38 °C were exposed to a stagnant saturated air at 38 °C, the coal temperatures increased...
TL;DR: In this paper, a sustained release type of inhibitor (PS-C) prepared with poly(acrylic acid)/sodium alginate super absorbent (PS), ascorbic acid (VC), and water was developed, which exhibited a not only highly efficient but also sustained inhibition performance on spontaneous combustion of coal.
Abstract: A sustained release type of inhibitor (PS-C) prepared with poly(acrylic acid)/sodium alginate super absorbent (PS), ascorbic acid (VC), and water was developed, which exhibited a not only highly efficient but also sustained inhibition performance on the spontaneous combustion of coal. The impact of PS hydrogel on coal oxidation was examined thermodynamically by TGA–DSC tests, and the variations of functional groups on coal surface under the influence of VC were in situ monitored by an FT-IR technique. The inhibition performance was evaluated with a parameter defined as the emitted carbon monoxide concentration decay rate during coal oxidation. The results show that the PS hydrogel and VC perform distinctive inhibition characteristics by physically removing the accumulated heat and chemically interrupting the free radical chain reaction of coal oxidation, respectively. The composite PS-C is capable of combining the inhibition characteristics of PS hydrogel and VC as well as further realizing a dramatic syn...
TL;DR: In this paper, the authors modeled the coal goaf as a 3D porous medium based on stress distribution and simulated the variation of O2 distribution influenced by CO2 or N2 injection.
Abstract: To prevent coal spontaneous combustion in mines, it is paramount to understand O2 gas distribution under condition of inert gas injection into goaf. In this study, the goaf was modeled as a 3-D porous medium based on stress distribution. The variation of O2 distribution influenced by CO2 or N2 injection was simulated based on the multi-component gases transport and the Navier–Stokes equations using Fluent. The numerical results without inert gas injection were compared with field measurements to validate the simulation model. Simulations with inert gas injection show that CO2 gas mainly accumulates at the goaf floor level; however, a notable portion of N2 gas moves upward. The evolution of the spontaneous combustion risky zone with continuous inert gas injection can be classified into three phases: slow inerting phase, rapid accelerating inerting phase, and stable inerting phase. The asphyxia zone with CO2 injection is about 1.25–2.4 times larger than that with N2 injection. The efficacy of preventing and putting out mine fires is strongly related with the inert gas injecting position. Ideal injections are located in the oxidation zone or the transitional zone between oxidation zone and heat dissipation zone.
TL;DR: In this paper, the authors used piezoelectric pressure transducers and light sensors to detect spontaneous ignition inside a tube with a diameter of 15mm and length of 360mm, and a high-speed video camera was used to record the flame propagation outside the tube.
TL;DR: In this article, the authors investigate the characteristics of self-heating and self-ignition in a packed bed using XDEM as an Euler-Lagrange model and show that ignition delay increases with fuel properties such as moisture content and particle size, while it decreases with process conditions such as gas velocity and temperature.
TL;DR: In this article, the authors provide flammability and explosibility data as well as some parameters to assess the spontaneous combustion tendency of these products and to relate this thermal susceptibility with the composition.
TL;DR: In this article, an adding device was designed to facilitate the addition of a powdered gelling agent to pipeline system to form foam-gel, which successfully controlled coal spontaneous combustion occurred in the process of equipment removing.
Abstract: In China, 47.3% of state-owned coal mines are endangered by coal seam spontaneous combustion that threat to the safety of mining. A new technique using foam-gel was developed to control coal spontaneous combustion. In this study, an adding device was designed to facilitate the addition of a powdered gelling agent to pipeline system to form foam-gel. The experimental system was constructed and experiments were carried out to test the performance of the adding device in laboratory. The experimental results showed that the optimum parameters of the inlet pressure and air flow were in the range of 1.6–1.8 MPa and 40–44 m3/h respectively, and the negative pressure ranged from −0.16 MPa to −0.22 MPa accordingly. The average adding rate of powdered gelling agent was 2.06 kg/min and 2.31 kg/min, respectively in lab scale experiment and field application. The adding device was tested at a coal working area and successfully controlled the coal spontaneous combustion occurred in the process of equipment removing. The results of the application promised that the adding device is structurally simple, compact, and easy to operate, and also the foam-gel has a remarkable effect for fire prevention.
TL;DR: In this article, the authors studied the self-heating and spontaneous combustion risk of biomass and fishmeal with thermal analysis (DSC-TG) and selfheating substances test experiments.
TL;DR: In this article, the propensity for spontaneous combustion of Inner Mongolia lignite irradiated in microwave irradiation was investigated using the crossing-point method, and the pore structures of irradiated lignites were measured using N2 adsorption/desorption method.
Abstract: The propensity for spontaneous combustion of Inner Mongolia lignite irradiated in microwave irradiation was investigated. The functional groups on the lignite surface were obtained by FTIR and XPS spectra, and the pore structures of irradiated lignite were measured using N2 adsorption/desorption method. The propensity for spontaneous combustion of lignite was classified using the crossing-point method. The irradiation treatment in microwave resulted in a prominent decrease in moisture content, decomposition of oxygen-containing functional groups, breakage of long alkyl side-chains, and increase in aromatic carbons. The quality of lignite developed towards high-rank coals after microwave irradiation. Microwave irradiation showed significant effects on the pore structures of lignite; the specific surface area and total pore volume of the irradiated lignite initially increased and then significantly decreased. A short-term microwave irradiation resulted in an increase the spontaneous combustion propensity of lignite. However, when the irradiation time extended, the propensity for spontaneous combustion was reduced because of the significant change in chemical composition and drastic decomposition of the pore structures.
TL;DR: The coal of Anyuan Mine has the characteristic of easy spontaneous combustion and conventional method is difficult to predict it as mentioned in this paper, which is why it is hard to predict coal spontaneous combustion.
Abstract: The coal of Anyuan Mine has the characteristic of easy spontaneous combustion. Conventional method is difficult to predict it. Coal samples from this mine were tested in laboratory. The data obtained from laboratory determination were initialized for the value which was defined as “K”. The ratio of each index gas and value of “K”, and the ratio of combination index gases and value of “K”, were analyzed simultaneously. The research results show that for this coal mine, if there is carbon monoxide in the gas sample, the phenomenon of oxidation and temperature rising for coal exists in this mine; if there is C2H4 in the gas sample, the temperature of coal perhaps exceeds 130 °C. If the coal temperature is between 35 °C and 130 °C, prediction and forecast for coal spontaneous combustion depend on the value of Φ(CO)/K mainly; if the temperature of coal is between 130 °C and 300 °C, prediction and forecast for coal spontaneous combustion depend on the value of Φ(C2H6)/Φ(C2H2) and Φ(C2H6)/K. The research results provide experimental basis for the prediction of coal spontaneous combustion in Anyuan coal mine, and have better guidance on safe production of this coal mine.