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Influence of pore structure on thermal stress distribution inside coal particles during primary fragmentation
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作者 Kai Qiao Shan Zhong +5 位作者 Siyang Tang Ke Yang Hairong Yue Kui Ma Lei Song Bin Liang 《Particuology》 SCIE EI CAS CSCD 2024年第2期49-61,共13页
Thermal stress is an important reason of coal particle primary fragmentation,during which the role of pore structure is ambiguous.Thermal stress induced fragmentation experiments were conducted with low volatile coal/... Thermal stress is an important reason of coal particle primary fragmentation,during which the role of pore structure is ambiguous.Thermal stress induced fragmentation experiments were conducted with low volatile coal/char particles,and the results show that the fragmentation severity enhances with increasing porosity.Various porous thermal stress models were developed with finite element method,and the influences of the pore shape,size,position and porosity on the thermal stress were discussed.The maximum thermal stress inside particle increases with pore curvature,the pore position affects the thermal stress more significantly at the particle center and surface.The expectation of the maximum tensile thermal stress linearly increases with porosity,making the particles with higher porosity easier to fragment,contrary to the conclusion deduced from the devolatilization theory.The obtained results are valuable for the analysis of different thermal processes concerning the thermal stresses of the solid feedstocks. 展开更多
关键词 coal particle Primary fragmentation Thermal stress Pore structure POROSITY
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An experimental study on ignition of single coal particles at low oxygen concentrations 被引量:2
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作者 Wantao YANG Yang ZHANG +2 位作者 Lilin HU Junfu LYU Hai ZHANG 《Frontiers in Energy》 SCIE CSCD 2021年第1期38-45,共8页
An experimental study on the ignition of single coal particles at low oxygen concentrations (XO_(2)<21%) was conducted using a tube furnace. The surface temperature (Ts) and the center temperature (Tc) of the coal ... An experimental study on the ignition of single coal particles at low oxygen concentrations (XO_(2)<21%) was conducted using a tube furnace. The surface temperature (Ts) and the center temperature (Tc) of the coal particles were obtained from the images taken by an infrared camera and thermocouples respectively. The ignition processes were recorded by a high-speed camera at different XO_(2) values and furnace temperatures Tw. Compared with literature experimental data obtained at a high XO_(2) value, the ignition delay time τi decreases more rapidly as XO_(2) increases at the low XO_(2) region. The responses of Ts and Tc to the variation of XO_(2) are different: Ts decreases while Tc remains nearly constant with increasing XO_(2) at a low XO_(2) value. In addition, τi is less sensitive to Tw while the ignition temperature Ti is more sensitive to Tw at a low XO_(2) value than in air. Observations of the position of flame front evolution illustrate that the ignition of a coal particle may change from a homogeneous mode to a heterogeneous or combined ignition mode as XO_(2) decreases. At a low XO_(2) value, buoyancy plays a more significant role in sweeping away the released volatiles during the ignition process. 展开更多
关键词 coal particles low oxygen concentration IGNITION ignition temperature ignition modes
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Drop-weight impact fragmentation of gas-containing coal particles 被引量:1
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作者 Chengwu Li Min Hao +2 位作者 Zhengya Geng Yonghang He Shanyang Wei 《Particuology》 SCIE EI CAS CSCD 2021年第2期35-42,共8页
Research on coal fragmentation can play an important role in understanding coal and gas outbursts.The study discussed in this paper explored the fragmentation of gas-containing coal particles using the drop-weight imp... Research on coal fragmentation can play an important role in understanding coal and gas outbursts.The study discussed in this paper explored the fragmentation of gas-containing coal particles using the drop-weight impact method.The effects of equilibrium gas pressures and type of adsorbate gas on particle size distributions and fragmentation energy were investigated in detail.We found that the Fractal particle size distribution model can most effectively describe the crushed coal particle sizes.The equilibrium pressure and type of gas can influence the Fractal distribution parameter.The crushing energy is composed of energy to create new surfaces and other forms of energy that are dissipated but the equilibrium gas pressure and type of adsorption gas can affect energy consumption and crushing efficiency.This research will be of guiding significance to the intensity evaluation and mechanism understanding of coal and gas outbursts. 展开更多
关键词 Gas-containing coal particles Particle size distribution Energy consumption Impact fragmentation
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Effect of chemical conditioning on the triboelectrification of coal and mineral particles 被引量:2
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作者 WANG Haifeng CHEN Qingru +3 位作者 ZHANG Xinxi TAN Zhihai WANG Shuai ZHOU Nianxin 《Mining Science and Technology》 EI CAS 2010年第3期421-424,共4页
Chemical conditioning was used to modify the triboelectrification of coal and mineral particles.The chemicals tested included starch,lignin,kerosene,ethanol,acetic acid,salicylic acid,sodium oleate,Sodium Hexametaphos... Chemical conditioning was used to modify the triboelectrification of coal and mineral particles.The chemicals tested included starch,lignin,kerosene,ethanol,acetic acid,salicylic acid,sodium oleate,Sodium Hexametaphosphate(SH),sodium silicate, Sodium Dodecylbenzenesulfonate(SDBS),Sodium Bicarbonate(SB) and ammonia.A high-speed,dry mixing method was employed.The charge-to-mass ratio of the coal and mineral samples,both untreated and treated,was tested using a Faraday cup. Dielectric constants were determined by measuring capacitance.It is found that the selectivity of the additives toward coal or minerals is not consistent.Salicylic acid is the optimal additive to enhance the triboelectrification performance of coal samples.Starch, lignin and sodium oleate are suitable for removal of pyrite.SH,sodium silicate,SDBS,SB and ammonia are suitable additives for the removal of ash-forming minerals. 展开更多
关键词 chemical conditioning TRIBOELECTRIFICATION coal triboelectrostatic separation coal particle mineral particle
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Experimental Research on Enhanced Cyclone Separation of Acoustic Agglomerated Particles 被引量:3
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作者 刘淑艳 黄虹宾 阎为革 《Journal of Beijing Institute of Technology》 EI CAS 2000年第1期61-65,共5页
To test the particles solidity and to verify the separating efficiency at normal atmospheric temperature, the experimental research was made on the enhanced cyclone separation of acoustic agglomerated fly ash particl... To test the particles solidity and to verify the separating efficiency at normal atmospheric temperature, the experimental research was made on the enhanced cyclone separation of acoustic agglomerated fly ash particles. The separating efficiency has increased by 3%-4% in a sound field with 150 dB pressure level compared with that obtained without acoustic wave processing. The enhanced cyclone separation test study for acoustic agglomerated particles has provided a technical basis for pressurized fluid bed combustion(PFBC) application. 展开更多
关键词 acoustic agglomeration coal fly ash particle cyclone separation
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Detonation initiated disintegration of coal particle due to the maxi- mum strain energy theory 被引量:1
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作者 Patadiya D M Jaisankar S Sheshadri T S 《Journal of Coal Science & Engineering(China)》 2013年第4期435-440,共6页
Fragmentation behaviour of coal particles subjected to detonation wave is being studied. Detonation wave is initiated by a plasma cartridge at one end of a detonation tube. Coal particles are subjected to a shock whos... Fragmentation behaviour of coal particles subjected to detonation wave is being studied. Detonation wave is initiated by a plasma cartridge at one end of a detonation tube. Coal particles are subjected to a shock whose temperature depends on the Mach number of the detonation wave. Temperature shock is found to generate thermal stresses which may fragment the coal particles. A non-dimensional mathematical model for the heat transfer process in the coal particle is proposed. Thermal stresses are calculated at various times and radii while maximum strain energy theory is used to understand the failure behavior viz., the time, temperature and location of fracture. A physical model for coal particle fragmentation when subjected to detonation wave is also proposed. The study suggests that detonation combustion of coal is qualitatively different from conventional method. 展开更多
关键词 coal particle detonation wave spontaneous fragmentation
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Top coal flows in an excavation disturbed zone of high section top coal caving of an extremely steep and thick seam 被引量:8
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作者 Miao Shengjun Lai Xingping Cui Feng 《Mining Science and Technology》 EI CAS 2011年第1期99-105,共7页
Compared with gentle dip long-wall caving,the length of a working face in fully-mechanized top-coal caving for extremely steep and thick seams is short,while its horizontal section is high with increasing production.B... Compared with gentle dip long-wall caving,the length of a working face in fully-mechanized top-coal caving for extremely steep and thick seams is short,while its horizontal section is high with increasing production.But the caving ratio is low,which might result in some disasters,such as roof falls,induced by local and large area collapse of the top coal in a working face and dangers induced by gas accumulation. After the development of cracks and weakening of the coal body,the tall,broken section of the top coal(a granular medium)of an extremely steep seam(over 60°)shows clear characteristics of nonlinear movement.We have thoroughly analyzed the geological environment and mining conditions of an excavation disturbed zone.Based on the results from a physical experiment of large-scale 3D modeling and coupling simulation of top coal-water-gas,we conclude that the weakened top coal can be regarded as a non-continuous medium.We used a particle flow code program to compare and analyze migration processes and the movements of a 30 m high section top coal over time before and after weakening of an extremely steep seam in the Weihuliang coal mine.The results of our simulation, experiment and monitoring show that pre-injection of water and pre-splitting blasting improve caving ability and symmetrical caving,relieve space for large area dynamic collapse of top coal,prolong migration time of noxious gases and release them from the mined out area and so achieve safety in mining. 展开更多
关键词 Top coal flowsExtremely steep and thick coal seamHigh section top coal caving (HSTCC)Particle flow
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Conversions of fuel-N, volatile-N, and char-N to NO and N_2O during combustion of a single coal particle in O_2/N_2 and O_2/H_2O at low temperature
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作者 Yuan Li Hao Zhou +2 位作者 Ning Li Runchao Qiu Kefa Cen 《Chinese Journal of Chemical Engineering》 SCIE EI CAS CSCD 2018年第9期1967-1977,共11页
Oxy-steam combustion is a promising next-generation combustion technology.Conversions of fuel-N,volatile-N,and char-N to NO and N2O during combustion of a single coal particle in O2/N2and O2/H2O were studied in a tube... Oxy-steam combustion is a promising next-generation combustion technology.Conversions of fuel-N,volatile-N,and char-N to NO and N2O during combustion of a single coal particle in O2/N2and O2/H2O were studied in a tube reactor at low temperature.In O2/N2,NO reaches the maximum value in the devolatilization stage and N2O reaches the maximum value in the char combustion stage.In O2/H2O,both NO and N2O reach the maximum values in the char combustion stage.The total conversion ratios of fuel-N to NO and N2O in O2/N2are obviously higher than those in O2/H2O,due to the reduction of H2O on NO and N2O.Temperature changes the trade-off between NO and N2O.In O2/N2and O2/H2O,the conversion ratios of fuel-N,volatile-N,and char-N to NO increase with increasing temperature,and those to N2O show the opposite trends.The conversion ratios of fuel-N,volatile-N,and char-N to NO reach the maximum values at 〈O2〉=30 vol%in O2/N2.In O2/H2O,the conversion ratios of fuel-N and char-N to NO reach the maximum values at 〈O2〉=30 vol%,and the conversion ratio of volatile-N to NO shows a slightly increasing trend with increasing oxygen concentration.The conversion ratios of fuel-N,volatile-N,and char-N to N2O decrease with increasing oxygen concentration in both atmospheres.A higher coal rank has higher conversion ratios of fuel-N to NO and N2O.Anthracite coal exhibits the highest conversion ratios of fuel-N,volatile-N,and char-N to NO and N2O in both atmospheres.This work is to develop efficient ways to understand and control NO and N2O emissions for a clean and sustainable atmosphere. 展开更多
关键词 NO N2O Single coal particle O2/N2 O2/H2O Low temperature
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Investigation of thermochemical process of coal particle packed bed reactions for the development of UCG
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作者 Tata Sutardi Linwei Wang +1 位作者 Nader Karimi Manosh C.Paul 《International Journal of Coal Science & Technology》 EI 2020年第3期476-492,共17页
In this study,a packed bed reactor was developed to investigate the gasification process of coal particles.The effects of coal particle size and heater temperature of reactor were examined to identify the thermochemic... In this study,a packed bed reactor was developed to investigate the gasification process of coal particles.The effects of coal particle size and heater temperature of reactor were examined to identify the thermochemical processes through the packed bed.Three different coal samples with varying size,named as A,B,and C,are used,and the experimental results show that the packed bed with smaller coal size has higher temperature,reaching 624°C,582°C,and 569°C for coal A,B,and C,respectively.In the case of CO formation,the smaller particle size has greater products in the unit of mole fraction over the area of generation.However,the variation in the porosity of the packed bed due to different coal particle sizes affects the reactions through the oxygen access.Consequently,the CO formation is least from the coal packed bed formed by the smallest particle size A.A second test with the temperature variations shows that the higher heater temperature promotes the chemical reactions,resulting in the increased gas products.The findings indicate the important role of coal seam porosity in underground coal gasification application,as well as temperature to promote the syngas productions. 展开更多
关键词 Thermochemical process Particle packed bed coal particle gasification Gas products Underground coal gasification(UCG)
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煤粉粒度对煤粉燃烧NO_x排放特性影响的试验研究 被引量:6
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作者 金晶 李瑞阳 +2 位作者 陈占军 樊俊杰 钟海卿 《热力发电》 CAS 北大核心 2004年第9期16-18,26,共4页
利用一维热态实验炉分别对不同粒度煤粉燃烧时 ,NOx 排放特性随煤种、过量空气系数、温度的变化规律进行了研究。研究结果表明 :NOx 的排放浓度与煤粉粒度存在一个煤粉粒度临界值 ,当煤粉粒度小于临界值时 ,随煤粉粒度的减小 ,NOx 的排... 利用一维热态实验炉分别对不同粒度煤粉燃烧时 ,NOx 排放特性随煤种、过量空气系数、温度的变化规律进行了研究。研究结果表明 :NOx 的排放浓度与煤粉粒度存在一个煤粉粒度临界值 ,当煤粉粒度小于临界值时 ,随煤粉粒度的减小 ,NOx 的排放浓度减小 ;当煤粉粒度大于临界值时 ,随煤粉粒度的减小 ,NOx 的排放浓度增大 ;煤粉超细化后 ,褐煤、烟煤的NOx 的排放浓度明显减少 ,贫煤、无烟煤则变化不大。 展开更多
关键词 电站 锅炉 煤粉粒度 煤粉燃烧 氮氧化物排放 大气污染
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Experimental Study on Product Characteristics of Typical Pulverized Coal Preheated by a Self-Preheating Burner
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作者 ZHANG Jinyang OUYANG Ziqu +1 位作者 DING Hongliang SU Kun 《Journal of Thermal Science》 SCIE EI CAS CSCD 2023年第5期1912-1934,共23页
As the major primary energy source in China,coal has been proved to be capable to improve its physical and chemical characteristics by the pretreatment of the self-preheating burner.In this study,the effects of alteri... As the major primary energy source in China,coal has been proved to be capable to improve its physical and chemical characteristics by the pretreatment of the self-preheating burner.In this study,the effects of altering operating conditions including preheating temperature(T_(p))and primary air equivalence ratio(λ_(p))on preheating characteristics of three typical pulverized coal were investigated on a bench-scale test rig.The high-temperature coal gas compositions along the axis of the riser and at the outlet of the self-preheating burner were measured,and the coal char and coal tar produced in the preheating process were collected and analyzed separately.The results indicated that with the significant release of volatile and the occurrence of chemical reactions,cracks and micropores emerged on the surface of the particles,making the pore structure on the surface more developed,and T_(p)had the most significant effect on the structure of coal particles.Additionally,there were evident differences in the corresponding operating conditions when the preheating characteristics of the three typical coal reached optimally.And preheating had the strongest influence on the degree of anthracite modification.With respect to coal tar,the increase of T_(p)andλ_(p)further promoted its secondary cracking and oxidation,resulting in a decrease in production yield.In this study,for bituminous coal and lignite,a large amount of coal tar were produced during preheating and the highest production yields could reach 5.74%and 6.15%,respectively.While for anthracite,the production yield was intensely low due to its own coal properties,all below 1.02%. 展开更多
关键词 self-preheating fuel modification product characteristics coal particle structure coal tar
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Numerical study of coarse coal particle breakage in pneumatic conveying 被引量:7
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作者 Jiawei Zhou Yu Liu +2 位作者 Changlong Du Songyong Liu Jianping Li 《Particuology》 SCIE EI CAS CSCD 2018年第3期204-214,共11页
Pneumatic conveying of coarse coal particles with various pipeline configurations and swirling intensities was investigated using a coupled computational fluid dynamics and discrete element method. A particle cluster ... Pneumatic conveying of coarse coal particles with various pipeline configurations and swirling intensities was investigated using a coupled computational fluid dynamics and discrete element method. A particle cluster agglomerated by the parallel-bond method was modeled to analyze the breakage of coarse coal particles. The numerical parameters, simulation conditions, and simulation results were experimentally validated. On analyzing total energy variation in the agglomerate during the breakage process, the results showed that downward fluctuation of the total particle energy was correlated with particle and wall col- lisions, and particle breakage showed a positive correlation with the energy difference. The correlation between the total energy variation of a particle cluster and particle breakage was also analyzed. Parti- cle integrity presented a fluctuating upward trend with pipe bend radius and increased with swirling number for most bend radii. The degree of particle breakage differed with pipeline bending direction and swirling intensity: in a horizontal bend, the bend radius and swirling intensity dominated the total energy variations: these effects were not observed in a vertical bend. The total energy of the particle cluster exiting a bend was generally positively correlated with the bend radius for all conditions and was independent of bending direction. 展开更多
关键词 Computational fluid dynamics-discreteelement method Pneumatic conveying Pipeline configuration Swirling intensity Coarse coal particle BREAKAGE
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煤沥青原料性质和反应条件对中间相炭微球粒度分布和形貌的影响 被引量:6
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作者 熊杰明 陈潇 +3 位作者 孙国娟 葛明兰 黄海燕 杨靖丰 《清华大学学报(自然科学版)》 EI CAS CSCD 北大核心 2014年第3期314-319,共6页
工业应用需要粒度均匀、球形度良好的中间相炭微球(MCMB)。反应条件、原料性质对MCMB性能有很大影响。以煤软沥青为原料,采用热缩聚法制备MCMB,分别考察了反应过程温度、时间、压力等反应条件,以及原料软化点、原生喹啉不溶物(QI)等性质... 工业应用需要粒度均匀、球形度良好的中间相炭微球(MCMB)。反应条件、原料性质对MCMB性能有很大影响。以煤软沥青为原料,采用热缩聚法制备MCMB,分别考察了反应过程温度、时间、压力等反应条件,以及原料软化点、原生喹啉不溶物(QI)等性质对MCMB粒度分布、形貌的影响情况。结果表明:在一定范围内,热聚温度的升高,或聚合时间的延长,都会使炭微球粒径逐渐增大,粒度分布变窄,粒度变得均匀;过低的反应压力使轻组分逸出,体系粘度升高,得不到规则的小球;原料软化点低、体系粘度小,有利于小球的自由运动、融并、生长成粒度均匀的MCMB;原料中QI是MCMB形成和发展的核心,原生QI粒度差别太大,会导致MCMB大小不均匀,甚至两极分化;除去原料中粒径过大的QI,有利于得到粒度均匀的MCMB。 展开更多
关键词 煤沥青 原料性质 反应条件 中间相炭微球(MC—MB) 直径分布 形貌
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