Surrounding rock of coal seam was one of the important factors to gas occurrence. The coal seam gas occurrence was studied by the index of roof strata thickness or sand content rate;we found that there were certain sh...Surrounding rock of coal seam was one of the important factors to gas occurrence. The coal seam gas occurrence was studied by the index of roof strata thickness or sand content rate;we found that there were certain shortcomings. In order to reasonably evaluate the influence of coal seam surrounding rock on gas occurrence in Panji mining area, we quantitatively evaluated the effect of coal seam surrounding rock on gas occurrence by influence coefficient of roof strata thickness, and built six mathematical models of the variational gas content in the mining area which is divided into six gas geological units. The results shows that the coal seam gas content is mainly influenced by 20 mroof strata in each gas geological unit, the gas content presents the tendency of increase, and with the influence coefficient of strata thickness increases, they exist a significant linear relationship.展开更多
Coal and gas outburst is a violent disaster driven by released energy from gas desorption.The initial expansion energy of released gas(IEERG)is a new method to predict coal and gas outburst.In this paper,an instrument...Coal and gas outburst is a violent disaster driven by released energy from gas desorption.The initial expansion energy of released gas(IEERG)is a new method to predict coal and gas outburst.In this paper,an instrument for IEERG measurement was developed.Compared with previous setups,the new one which is equipped with three convergent nozzles and quick-release mechanism gets improved in data acquisition and gas sealing and releasing performance.To comprehensively know the effect of gas pressure,particle size,and nozzle area on IEERG,a series of experiments were carried out with this new setup.The variable control test results indicated that the gas pressure-IEERG curves remain the linear trend and the particle size-IEERG curves maintain the negative exponential trend for nozzle areas at 1.13,2.26,and3.39 mm2,respectively.The increase in nozzle area leads to deceases in value of IEERG and absolute value of slope of fitting curves in each test.In addition,the orthogonal experiment showed that the influence of gas pressure,nozzle area,and particle size on IEERG decreases in turn.Only gas pressure had a marked impact on IEERG.This work offers great importance in improving the accuracy of prediction of coal and gas outburst.展开更多
Objective The Juhugeng mining area in Qinghai Province of northwest China has attracted wide attention among geologists for it hosts typical coal measure gases.The shale gas reservoirs were reformed by intensive struc...Objective The Juhugeng mining area in Qinghai Province of northwest China has attracted wide attention among geologists for it hosts typical coal measure gases.The shale gas reservoirs were reformed by intensive structural movements during geological periods,展开更多
The yield of tar and syngas has been investigated by catalytic pyrolysis of Pingzhuang lignite(PZL)over Ca(OH)2 catalyst in temperature range of 600℃-1000℃in a tube furnace.The results show that the yield of volatil...The yield of tar and syngas has been investigated by catalytic pyrolysis of Pingzhuang lignite(PZL)over Ca(OH)2 catalyst in temperature range of 600℃-1000℃in a tube furnace.The results show that the yield of volatile pyrolysis increases and char decreases with rising temperature for both raw and catalyzed Pingzhuang lignite.The hydrogen fraction(H2)increased from 20%to 40%for the PZL sample;but,for the PZL-Ca(OH)2 sample,H2 fraction fluctuated randomly between 35%to 42%,with the maximum H2 fraction found at 1000℃.The Gaschromatography mass-spectroscopic(GC-MS)analysis revealed that the maximum tar yield at 800℃and 700℃was obtained for PZL and PZL-Ca(OH)2,respectively.The surface morphology of PZL and PZL-Ca(OH)2 chars underwent different transformation in the presence of catalyst as illustrated by SEM/EDX,FTIR,and BET analysis.Furthermore,char sample was investigated for the carbon conversion and reactivity index using TGA analysis under N2 and CO atmosphere.展开更多
A large amount of energy is consumed in a coal and gas outburst since a mass of coal is pulverized and ejected, accompanying a great quantity of gas emitted, resulting in a major mining hazard in underground coal mini...A large amount of energy is consumed in a coal and gas outburst since a mass of coal is pulverized and ejected, accompanying a great quantity of gas emitted, resulting in a major mining hazard in underground coal mining around the world. Understanding how potential energy stored in gassy coal seams dissipates in the process of outbursting may possibly be a key to clarify the mechanisms responsible for coal and gas outburst. The present study was aimed to evaluate energy for crushing coal to various size fractions in coal and gas outbursts through theoretical and experimental investigation into the shape of fine coal particles and their equivalent diameter. Theoretical analysis indicates that the shape of a particle has a significant impact both on its equivalent diameter and hence on its outer surface area.Microscopic observations demonstrate the particle fraction with diameters less than 0.075 mm, produced from crushing coal samples, mostly takes on a spherical or ellipsoidal shape, and experimental data also show this part of particles consists of 30%–50% surface area newly generated from crushing operation,though these fine coal accounts for only less than ten percentages by weight. Further, analysis of experimental data indicates that the total surface area of this particle size fraction varies exponentially with input crushing energy, and the specific area energy is not a constant but probably in association with physical properties and textures of material.展开更多
文摘Surrounding rock of coal seam was one of the important factors to gas occurrence. The coal seam gas occurrence was studied by the index of roof strata thickness or sand content rate;we found that there were certain shortcomings. In order to reasonably evaluate the influence of coal seam surrounding rock on gas occurrence in Panji mining area, we quantitatively evaluated the effect of coal seam surrounding rock on gas occurrence by influence coefficient of roof strata thickness, and built six mathematical models of the variational gas content in the mining area which is divided into six gas geological units. The results shows that the coal seam gas content is mainly influenced by 20 mroof strata in each gas geological unit, the gas content presents the tendency of increase, and with the influence coefficient of strata thickness increases, they exist a significant linear relationship.
基金supported by the National Key Scientific Instruments and Equipment Development Projects of China(No.51427804)the National Science Foundation of Shandong Province(No.ZR2017MEE023)。
文摘Coal and gas outburst is a violent disaster driven by released energy from gas desorption.The initial expansion energy of released gas(IEERG)is a new method to predict coal and gas outburst.In this paper,an instrument for IEERG measurement was developed.Compared with previous setups,the new one which is equipped with three convergent nozzles and quick-release mechanism gets improved in data acquisition and gas sealing and releasing performance.To comprehensively know the effect of gas pressure,particle size,and nozzle area on IEERG,a series of experiments were carried out with this new setup.The variable control test results indicated that the gas pressure-IEERG curves remain the linear trend and the particle size-IEERG curves maintain the negative exponential trend for nozzle areas at 1.13,2.26,and3.39 mm2,respectively.The increase in nozzle area leads to deceases in value of IEERG and absolute value of slope of fitting curves in each test.In addition,the orthogonal experiment showed that the influence of gas pressure,nozzle area,and particle size on IEERG decreases in turn.Only gas pressure had a marked impact on IEERG.This work offers great importance in improving the accuracy of prediction of coal and gas outburst.
基金supported by the National Natural Science Foundation of China(grant No.41572141)
文摘Objective The Juhugeng mining area in Qinghai Province of northwest China has attracted wide attention among geologists for it hosts typical coal measure gases.The shale gas reservoirs were reformed by intensive structural movements during geological periods,
基金Supported by the Innovation Reasearch Groups of the National Natural Science Foundation of China(51621005)EPSRC from the UK.
文摘The yield of tar and syngas has been investigated by catalytic pyrolysis of Pingzhuang lignite(PZL)over Ca(OH)2 catalyst in temperature range of 600℃-1000℃in a tube furnace.The results show that the yield of volatile pyrolysis increases and char decreases with rising temperature for both raw and catalyzed Pingzhuang lignite.The hydrogen fraction(H2)increased from 20%to 40%for the PZL sample;but,for the PZL-Ca(OH)2 sample,H2 fraction fluctuated randomly between 35%to 42%,with the maximum H2 fraction found at 1000℃.The Gaschromatography mass-spectroscopic(GC-MS)analysis revealed that the maximum tar yield at 800℃and 700℃was obtained for PZL and PZL-Ca(OH)2,respectively.The surface morphology of PZL and PZL-Ca(OH)2 chars underwent different transformation in the presence of catalyst as illustrated by SEM/EDX,FTIR,and BET analysis.Furthermore,char sample was investigated for the carbon conversion and reactivity index using TGA analysis under N2 and CO atmosphere.
基金financially supported by Natural Science Foundation (Nos.51174241,and 51674049) of ChinaNational Basic Research Program of China (No.2011CB201203)
文摘A large amount of energy is consumed in a coal and gas outburst since a mass of coal is pulverized and ejected, accompanying a great quantity of gas emitted, resulting in a major mining hazard in underground coal mining around the world. Understanding how potential energy stored in gassy coal seams dissipates in the process of outbursting may possibly be a key to clarify the mechanisms responsible for coal and gas outburst. The present study was aimed to evaluate energy for crushing coal to various size fractions in coal and gas outbursts through theoretical and experimental investigation into the shape of fine coal particles and their equivalent diameter. Theoretical analysis indicates that the shape of a particle has a significant impact both on its equivalent diameter and hence on its outer surface area.Microscopic observations demonstrate the particle fraction with diameters less than 0.075 mm, produced from crushing coal samples, mostly takes on a spherical or ellipsoidal shape, and experimental data also show this part of particles consists of 30%–50% surface area newly generated from crushing operation,though these fine coal accounts for only less than ten percentages by weight. Further, analysis of experimental data indicates that the total surface area of this particle size fraction varies exponentially with input crushing energy, and the specific area energy is not a constant but probably in association with physical properties and textures of material.
