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Filip Verplaetsen - One of the best experts on this subject based on the ideXlab platform.
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numerical investigation on the self ignition behaviour of Coal Dust accumulations the roles of oxygen diluent gas and Dust volume
Fuel, 2017Co-Authors: Dejian Wu, Filip Verplaetsen, Maarten Vanierschot, Frederik Norman, Martin Schmidt, Jan Berghmans, Eric Van Den BulckAbstract:Self-ignition of Coal Dust deposits poses a higher risk of fires in oxygen-enriched oxy-fuel combustion systems. In this work, we develop a numerical method, using the commercial software COMSOL Multiphysics, to investigate self-ignition behaviour of Coal Dust accumulations with a main emphasis on the roles of oxygen, diluent gas and Dust volume. A one-step 2nd-order reaction kinetic model considering both Coal density and oxygen density is used to estimate reaction rate using the kinetic parameters from previously conducted hot-oven tests. This model is validated to predict the transient temperature and concentration profiles of South African Coal Dusts until ignition. The computed self-ignition temperatures of Dust volumes show a good agreement with experimental results. In addition, it is found that the inhibiting effect of carbon dioxide is comparatively small and oxygen consumption increases dramatically after ignition. Parameter analysis shows that the heating value and kinetic parameters have a comparatively pronounced effect on self-ignition temperature. The model provides a satisfactory explanation for the dependence of self-ignition behaviour on gas atmospheres, thus helping to further understand the fire risk of self-ignition in oxy-fuel combustion systems.
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self ignition and smoldering characteristics of Coal Dust accumulations in o2 n2 and o2 co2 atmospheres
Proceedings of the Combustion Institute, 2017Co-Authors: Martin Schmidt, Xinyan Huang, Filip VerplaetsenAbstract:The self-ignition of Coal Dust deposits and its subsequent smoldering combustion pose a high fire hazard to oxy-fuel power systems which burn fuels using pure oxygen for the sake of carbon capture and storage. The increasing risk of explosion in the gas-phase and self-ignition in the solid-phase for an oxygen enhanced combustion environment has not been well studied yet. In this work, the heterogeneous reactions of a bituminous Coal Dust are investigated by using a novel hot-basket apparatus with an emphasis on the roles of O2 and diluent gas in chemisorption and smoldering. Experiments show that increasing O2 mole fraction accelerates both self-ignition and the following smoldering combustion. On the other hand, the presence of CO2 increases the ignition temperature and reduces the maximum smoldering temperature. However, the promotion in the fire and explosion risk by elevating O2 mole fraction is substantially stronger than the retardation effected by presence of CO2. The emission-gas measurements show that the CO to CO2 ratio increases significantly after self-ignition, and CH4 counts for 1–8% of the total carbon emission. This research may help improve the understanding of heterogeneous Coal combustion and the fire safety in oxy-fuel power systems.
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experimental study on the minimum ignition temperature of Coal Dust clouds in oxy fuel combustion atmospheres
Journal of Hazardous Materials, 2016Co-Authors: Frederik Norman, Filip Verplaetsen, Eric Van Den BulckAbstract:BAM furnace apparatus tests were conducted to investigate the minimum ignition temperature of Coal Dusts (MITC) in O2/CO2 atmospheres with an O2 mole fraction from 20 to 50%. Three Coal Dusts: Indonesian Sebuku Coal, Pittsburgh No.8 Coal and South African Coal were tested. Experimental results showed that the Dust explosion risk increases significantly with increasing O2 mole fraction by reducing the minimum ignition temperature for the three tested Coal Dust clouds dramatically (even by 100°C). Compared with conventional combustion, the inhibiting effect of CO2 was found to be comparatively large in Dust clouds, particularly for the Coal Dusts with high volatile content. The retardation effect of the moisture content on the ignition of Dust clouds was also found to be pronounced. In addition, a modified steady-state mathematical model based on heterogeneous reaction was proposed to interpret the observed experimental phenomena and to estimate the ignition mechanism of Coal Dust clouds under minimum ignition temperature conditions. The analysis revealed that heterogeneous ignition dominates the ignition mechanism for sub-/bituminous Coal Dusts under minimum ignition temperature conditions, but the decrease of Coal maturity facilitates homogeneous ignition. These results improve our understanding of the ignition behaviour and the explosion risk of Coal Dust clouds in oxy-fuel combustion atmospheres.
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experimental investigation on the self ignition behaviour of Coal Dust accumulations in oxy fuel combustion system
Fuel, 2015Co-Authors: Xinyan Huang, Filip Verplaetsen, Frederik Norman, Jan Berghmans, Eric Van Den BulckAbstract:Abstract For the oxy-Coal combustion, the accumulation of Coal Dust in the system has a fire risk of self-ignition. Therefore, understanding the ignition dynamics of Coal Dust deposits in oxygen-enriched environment is essential for the prevention of fire and Dust explosion. In this work, both hot-oven and hot-plate tests were conducted to study the self-ignition behaviour of Coal Dusts in O2/CO2 ambient with O2 mole fraction from 21% to 50%. Three Coal Dusts: Indonesian Sebuku Coal, Pittsburgh No. 8 Coal and South African Coal were tested with different sizes. Experimental results revealed that the self-ignition risk increased significantly with the increasing O2 mole fraction: reducing both the critical ignition temperature (10 °C in hot-oven test and 40 °C in hot-plate test) and the ignition delay time. Comparatively, the inhibiting effect of CO2 was found to be small for self-ignition. In addition, a modified Frank-Kamenetzkii analysis was proposed to explain all measured critical ignition temperatures, and the genetic algorithm was used to determine kinetic parameters of the one-step global reaction. The analysis showed that as the Coal maturity/rank increased, both the self-ignition risk and the sensitivity to oxidation decreased, along with the decreasing apparent activation energy and pre-exponential factor. Such trend did not change with the ambient oxygen condition for all three Coal Dusts. These results improve our understanding of the self-ignition behaviour and the fire risk of Coal Dust in the oxy-fuel combustion system.
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the Dust explosion characteristics of Coal Dust in an oxygen enriched atmosphere
Procedia Engineering, 2012Co-Authors: Frederik Norman, Jan Berghmans, Filip VerplaetsenAbstract:Abstract The ability to mix pulverised Coal with oxygen at concentrations greater than the currently applied 21% may well provide advantages for burner design in oxy/Coal fired systems. However the risk of Dust explosions increases significantly with increasing oxygen concentration and temperature. In this study the influence of enriched oxygen concentrations is researched on the Dust explosion characteristics of Indonesian (Sebuku) high volatile bituminous Coal Dust and on Pittsburgh Coal ni8. Both ignition sensitivity characteristics (minimum ignition energy and minimum ignition temperatures) and explosion severity characteristics (maximum explosion pressure, Pmax, and maximum rate of pressure rise, Kst) are investigated.
Eric Van Den Bulck - One of the best experts on this subject based on the ideXlab platform.
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experimental study on the minimum ignition temperature of Coal Dust clouds in oxy fuel combustion atmospheres
Journal of Hazardous Materials, 2016Co-Authors: Frederik Norman, Filip Verplaetsen, Eric Van Den BulckAbstract:BAM furnace apparatus tests were conducted to investigate the minimum ignition temperature of Coal Dusts (MITC) in O2/CO2 atmospheres with an O2 mole fraction from 20 to 50%. Three Coal Dusts: Indonesian Sebuku Coal, Pittsburgh No.8 Coal and South African Coal were tested. Experimental results showed that the Dust explosion risk increases significantly with increasing O2 mole fraction by reducing the minimum ignition temperature for the three tested Coal Dust clouds dramatically (even by 100°C). Compared with conventional combustion, the inhibiting effect of CO2 was found to be comparatively large in Dust clouds, particularly for the Coal Dusts with high volatile content. The retardation effect of the moisture content on the ignition of Dust clouds was also found to be pronounced. In addition, a modified steady-state mathematical model based on heterogeneous reaction was proposed to interpret the observed experimental phenomena and to estimate the ignition mechanism of Coal Dust clouds under minimum ignition temperature conditions. The analysis revealed that heterogeneous ignition dominates the ignition mechanism for sub-/bituminous Coal Dusts under minimum ignition temperature conditions, but the decrease of Coal maturity facilitates homogeneous ignition. These results improve our understanding of the ignition behaviour and the explosion risk of Coal Dust clouds in oxy-fuel combustion atmospheres.
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experimental investigation on the self ignition behaviour of Coal Dust accumulations in oxy fuel combustion system
Fuel, 2015Co-Authors: Xinyan Huang, Filip Verplaetsen, Frederik Norman, Jan Berghmans, Eric Van Den BulckAbstract:Abstract For the oxy-Coal combustion, the accumulation of Coal Dust in the system has a fire risk of self-ignition. Therefore, understanding the ignition dynamics of Coal Dust deposits in oxygen-enriched environment is essential for the prevention of fire and Dust explosion. In this work, both hot-oven and hot-plate tests were conducted to study the self-ignition behaviour of Coal Dusts in O2/CO2 ambient with O2 mole fraction from 21% to 50%. Three Coal Dusts: Indonesian Sebuku Coal, Pittsburgh No. 8 Coal and South African Coal were tested with different sizes. Experimental results revealed that the self-ignition risk increased significantly with the increasing O2 mole fraction: reducing both the critical ignition temperature (10 °C in hot-oven test and 40 °C in hot-plate test) and the ignition delay time. Comparatively, the inhibiting effect of CO2 was found to be small for self-ignition. In addition, a modified Frank-Kamenetzkii analysis was proposed to explain all measured critical ignition temperatures, and the genetic algorithm was used to determine kinetic parameters of the one-step global reaction. The analysis showed that as the Coal maturity/rank increased, both the self-ignition risk and the sensitivity to oxidation decreased, along with the decreasing apparent activation energy and pre-exponential factor. Such trend did not change with the ambient oxygen condition for all three Coal Dusts. These results improve our understanding of the self-ignition behaviour and the fire risk of Coal Dust in the oxy-fuel combustion system.
Frederik Norman - One of the best experts on this subject based on the ideXlab platform.
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numerical investigation on the self ignition behaviour of Coal Dust accumulations the roles of oxygen diluent gas and Dust volume
Fuel, 2017Co-Authors: Dejian Wu, Filip Verplaetsen, Maarten Vanierschot, Frederik Norman, Martin Schmidt, Jan Berghmans, Eric Van Den BulckAbstract:Self-ignition of Coal Dust deposits poses a higher risk of fires in oxygen-enriched oxy-fuel combustion systems. In this work, we develop a numerical method, using the commercial software COMSOL Multiphysics, to investigate self-ignition behaviour of Coal Dust accumulations with a main emphasis on the roles of oxygen, diluent gas and Dust volume. A one-step 2nd-order reaction kinetic model considering both Coal density and oxygen density is used to estimate reaction rate using the kinetic parameters from previously conducted hot-oven tests. This model is validated to predict the transient temperature and concentration profiles of South African Coal Dusts until ignition. The computed self-ignition temperatures of Dust volumes show a good agreement with experimental results. In addition, it is found that the inhibiting effect of carbon dioxide is comparatively small and oxygen consumption increases dramatically after ignition. Parameter analysis shows that the heating value and kinetic parameters have a comparatively pronounced effect on self-ignition temperature. The model provides a satisfactory explanation for the dependence of self-ignition behaviour on gas atmospheres, thus helping to further understand the fire risk of self-ignition in oxy-fuel combustion systems.
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experimental study on the minimum ignition temperature of Coal Dust clouds in oxy fuel combustion atmospheres
Journal of Hazardous Materials, 2016Co-Authors: Frederik Norman, Filip Verplaetsen, Eric Van Den BulckAbstract:BAM furnace apparatus tests were conducted to investigate the minimum ignition temperature of Coal Dusts (MITC) in O2/CO2 atmospheres with an O2 mole fraction from 20 to 50%. Three Coal Dusts: Indonesian Sebuku Coal, Pittsburgh No.8 Coal and South African Coal were tested. Experimental results showed that the Dust explosion risk increases significantly with increasing O2 mole fraction by reducing the minimum ignition temperature for the three tested Coal Dust clouds dramatically (even by 100°C). Compared with conventional combustion, the inhibiting effect of CO2 was found to be comparatively large in Dust clouds, particularly for the Coal Dusts with high volatile content. The retardation effect of the moisture content on the ignition of Dust clouds was also found to be pronounced. In addition, a modified steady-state mathematical model based on heterogeneous reaction was proposed to interpret the observed experimental phenomena and to estimate the ignition mechanism of Coal Dust clouds under minimum ignition temperature conditions. The analysis revealed that heterogeneous ignition dominates the ignition mechanism for sub-/bituminous Coal Dusts under minimum ignition temperature conditions, but the decrease of Coal maturity facilitates homogeneous ignition. These results improve our understanding of the ignition behaviour and the explosion risk of Coal Dust clouds in oxy-fuel combustion atmospheres.
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experimental investigation on the self ignition behaviour of Coal Dust accumulations in oxy fuel combustion system
Fuel, 2015Co-Authors: Xinyan Huang, Filip Verplaetsen, Frederik Norman, Jan Berghmans, Eric Van Den BulckAbstract:Abstract For the oxy-Coal combustion, the accumulation of Coal Dust in the system has a fire risk of self-ignition. Therefore, understanding the ignition dynamics of Coal Dust deposits in oxygen-enriched environment is essential for the prevention of fire and Dust explosion. In this work, both hot-oven and hot-plate tests were conducted to study the self-ignition behaviour of Coal Dusts in O2/CO2 ambient with O2 mole fraction from 21% to 50%. Three Coal Dusts: Indonesian Sebuku Coal, Pittsburgh No. 8 Coal and South African Coal were tested with different sizes. Experimental results revealed that the self-ignition risk increased significantly with the increasing O2 mole fraction: reducing both the critical ignition temperature (10 °C in hot-oven test and 40 °C in hot-plate test) and the ignition delay time. Comparatively, the inhibiting effect of CO2 was found to be small for self-ignition. In addition, a modified Frank-Kamenetzkii analysis was proposed to explain all measured critical ignition temperatures, and the genetic algorithm was used to determine kinetic parameters of the one-step global reaction. The analysis showed that as the Coal maturity/rank increased, both the self-ignition risk and the sensitivity to oxidation decreased, along with the decreasing apparent activation energy and pre-exponential factor. Such trend did not change with the ambient oxygen condition for all three Coal Dusts. These results improve our understanding of the self-ignition behaviour and the fire risk of Coal Dust in the oxy-fuel combustion system.
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the Dust explosion characteristics of Coal Dust in an oxygen enriched atmosphere
Procedia Engineering, 2012Co-Authors: Frederik Norman, Jan Berghmans, Filip VerplaetsenAbstract:Abstract The ability to mix pulverised Coal with oxygen at concentrations greater than the currently applied 21% may well provide advantages for burner design in oxy/Coal fired systems. However the risk of Dust explosions increases significantly with increasing oxygen concentration and temperature. In this study the influence of enriched oxygen concentrations is researched on the Dust explosion characteristics of Indonesian (Sebuku) high volatile bituminous Coal Dust and on Pittsburgh Coal ni8. Both ignition sensitivity characteristics (minimum ignition energy and minimum ignition temperatures) and explosion severity characteristics (maximum explosion pressure, Pmax, and maximum rate of pressure rise, Kst) are investigated.
Deming Wang - One of the best experts on this subject based on the ideXlab platform.
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experimental investigation of Coal Dust wetting ability of anionic surfactants with different structures
Process Safety and Environmental Protection, 2019Co-Authors: Deming Wang, Hetang Wang, Xiaolong Zhu, Yi Zhang, Yunfei Zhu, Fangming LiuAbstract:Abstract To better understand the Coal Dust wetting ability of anionic surfactants with different structures, sodium dodecyl sulfate (SDS), sodium dodecyl sulfonate (SDDS), and sodium dodecyl benzene sulfonate (SDBS) were selected. The surface tension, wetting time, and infrared spectra of Coal Dust were tested. The hydrophilic-lipophilic balance (HLB) values of the surfactants were calculated. Results showed that the decrease in the surface tension could shorten the wetting time at low surfactant concentrations. But the decrease in the wetting time was no longer related to the constant surface tension that was lower than 45 mN/m. The adsorption density depends on the hydrophobic interactions and electrostatic repulsions between the surfactant molecules and the Coal Dust. During the dynamic immersion process, the surfactants with high HLB values could bring the Coal Dust into the bulk solution rapidly. The wetting time of Coal Dust for SDBS with a high adsorption density and low HLB or SDS with a small adsorption density and high HLB was relatively longer. The adsorption density and HLB value of SDDS were intermediate between those of SDS and SDBS. Under the combined action of these two factors, the wetting time of SDDS was shorter than those of SDS and SDBS.
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experimental investigation on the wettability of respirable Coal Dust based on infrared spectroscopy and contact angle analysis
Advanced Powder Technology, 2017Co-Authors: Hetang Wang, Lin Zhang, Deming WangAbstract:Abstract Respirable Dust does great harm to human health. In this paper, we focused on the wetting characteristics of respirable Coal Dust, and the effect of functional groups of respirable Coal Dust on its wettability was investigated. We selected five different types of Coal samples (Lignite, Gas fat Coal, Coking Coal, 1/3 Coking Coal, and Anthracite) from some typical mining areas in China. We used a Fourier Transform Infrared Spectrometer (FT-IR) to obtain the IR spectrum of the respirable Coal Dust, and the percentage of functional groups for each respirable Coal Dust was obtained by the peak area normalization method and then analyzed. And the wettability of respirable Coal Dust was evaluated by contact angle measurement. It is found that the benzene rings, aromatic hydrocarbons with benzene rings, aliphatic hydrocarbons with methyl, methylene, and so on, which have carbon-containing macromolecular structures, are hydrophobic. While the oxygen-containing functional groups represented by hydroxyl and carboxyl groups, and silicates and carbonate minerals are hydrophilic. Besides, the results show that respirable Coal Dust of different metamorphic grade Coals has different wettability. This study has important theoretical significance for understanding the wettability of respirable Coal Dust.
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effects of chemical properties of Coal Dust on its wettability
Powder Technology, 2017Co-Authors: Deming Wang, Hetang Wang, Haihui Xin, Xiaolong Zhu, Yi Zhang, Qingguo WangAbstract:Abstract The relationship between Coal Dust chemical composition and its wettability was analyzed in detail using the Walker test method. The wetting rate of Coal Dust was also investigated. Results show that the wetting time of Coal Dust is negatively correlated with moisture content. Increased moisture content improves the wettability, while the content of ash, volatile matter and fixed carbon in the Coal Dust has no effect on wettability. Surface hydroxyl is the main factor that determines the wettability of Coal Dust. The wetting time decreases linearly (R2 = 0.81) with increasing hydroxyl functional group content. The increase of carbonyl group content improves Coal Dust wettability, but there is no obvious relationship between carboxyl group content and the wetting time. Increased quartz content leads to decreased wettability, which indicates that quartz on the Coal Dust surface associated with organic composition may be hydrophobic. Compared to bulk chemical composition, the wettability of Coal Dust is more closely related to the surface hydroxyl functional group. In addition, the wetting time increases linearly with increasing Coal Dust mass, but the wetting rate differs for different Coal Dust samples. Coal Dust with high hydroxyl content has a faster wetting rate than Dust with lower hydroxyl content.
Behdad Moghtaderi - One of the best experts on this subject based on the ideXlab platform.
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explosion severity of methane Coal Dust hybrid mixtures in a ducted spherical vessel
Powder Technology, 2018Co-Authors: Sazal Kundu, Jafar Zanganeh, Daniel Eschebach, Behdad MoghtaderiAbstract:Abstract This article reports an investigation on the explosion characteristics of methane–Coal Dust hybrid mixtures in a ducted spherical vessel. Methane–Coal Dust hybrid mixture explosion can occur in Coal mines and spread into mine tunnels. While investigating the effects of methane addition to Coal Dust–air mixtures, the violence of Coal Dust explosions was found to increase significantly in the presence of methane. The energy of ignition was found to impact on the pressure rises in the vessel and in the duct. The experimental data and scientific analysis presented can assist in addressing ducted explosions originating from hybrid mixtures in process inDustries such as Coal mines.
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experimental investigation of the minimum auto ignition temperature mait of the Coal Dust layer in a hot and humid environment
Fire Safety Journal, 2016Co-Authors: Mohammed Jabbar Ajrash, Jafar Zanganeh, Behdad MoghtaderiAbstract:Abstract Ventilation Air Methane (VAM) abatement technology is recognized as a promising and value adding technique for reducing fugitive methane emissions, however, it also increases the potential fire and explosion risks of overheated Coal Dust. To eliminate these risks from the abatement systems it is necessary to determine the critical combustion characteristics of the minimum auto ignition temperature (MAIT) for a Coal Dust layer. This study investigates the auto-ignition behavior of Coal Dust layers in a humid environment with Relative Humidity (RH) >80%. The MAIT of four different Coal Dust samples (Australian Coal) with particle sizes below 212 μm and Dust layer thicknesses of 5, 12 and 15 mm were measured using a Dust layer auto ignition temperature apparatus in accordance with the ASTM E2021 standard. It was concluded that the MAIT of the Coal Dust layer significantly decreases with decreasing particle size. The MAIT for the Coal samples with a smaller D50 size were observed to be lower in comparison with samples with a larger D50 size. The Dust layer thickness was shown to significantly impact on the MAIT. The MAIT increased proportionally with the increasing thickness of the Coal Dust layer. The effect of the Coal Dust moisture content and humidity on the MAIT for compacted Dust layers was noticeable, whereas, this effect was less important with loose Dust layers. In addition, this work investigated and compared the MAIT for a typical Coal Dust sample based on the existing ASTM and International Electrotechnical Commission (IEC) standard procedures for ignition of Coal Dust layers.
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Methane-Coal Dust hybrid fuel explosion properties in a large scale cylindrical explosion chamber
Journal of Loss Prevention in The Process Industries, 2016Co-Authors: Mohammed Jabbar Ajrash, Jafar Zanganeh, Behdad MoghtaderiAbstract:Abstract The fires and explosions caused by flammable hydrocarbon air mixtures are a major safety concern in the chemical and processing inDustries. The thermo-physical and chemical properties of the flammable fuels in a hybrid form appear to have a significant impact on the combustion process. This usually occurs due to substantial changes in the flammability concentration regimes. The aim of this study is to investigate the fire and explosive properties of hybrid fuels in the chemical and process inDustries. In addition, it examines the impact of the ignition energy and vessel geometry on the magnitude of the pressure rise and flame propagation velocity. The experimental work was conducted on a cylindrically shaped explosion chamber constructed as part of this study at The University of Newcastle, Australia. The chamber was made of mild steel and was 30 m in length and 0.5 in diameter. It included a series of high resolution pressure transducers, a pyrometer, as well as a high speed video camera. Methane and Coal Dust were used as fuels and chemical igniters with a known energy were used to ignite the fuels. The results obtained from this study showed that both the ignition energy and the diluted combustible fuel Dust have significant impacts on the Over Pressure Rise (OPR) in an explosion chamber. The significant findings included that the OPR doubled when 30 g m −3 of Coal Dust was added to a 6% methane/air mixture, and it increased by 60% when 10 kJ was used instead of a 1 kJ ignition source. The initial ignition energy was observed to considerably enhance the speed of both the pressure wave and the flame front, where the pressure wave speed doubled when using a 5 kJ instead of a 1 kJ ignition source. However, the pressure wave speed increased by five times when a 10 kJ was used instead of a 1 kJ ignition source. Additionally, the maximum flame front velocity observed for the ignition source with 5 kJ energy was twice the flame front velocity for the 1 kJ ignition source. Finally, it was observed that the time needed for the initial methane ignition was reduced by about 50% when using a 10 kJ instead of a 1 kJ ignition source.