An experimental study on co-pyrolysis of bituminous coal and biomass was performed in a pressured fluidized bed reactor.The blend ratio of biomass in the mixture was varied between 0 and 100 wt%,and the temperature wa...An experimental study on co-pyrolysis of bituminous coal and biomass was performed in a pressured fluidized bed reactor.The blend ratio of biomass in the mixture was varied between 0 and 100 wt%,and the temperature was over a range of 550–650℃ under 1.0 MPa pressure with different atmospheres.On the basis of the individual pyrolysis behavior of bituminous coal and biomass,the influences of the biomass blending ratio,temperature,pressure and atmosphere on the product distribution were investigated.The results indicated that there existed a synergetic effect in the co-pyrolysis of bituminous coal and biomass in this pressured fluidized bed reactor,especially when the condition of bituminous coal and biomass blend ratio of 70:30(w/w),600℃,and 0.3 MPa was applied.The addition of biomass influenced the tar and char yields and gas and tar composition during co-pyrolysis.The tar yields were higher than the calculated values from individual pyrolysis of each fuel,and consequently the char yields were lower.The experimental results showed that the composition of the gaseous products was not in accordance with those of their individual fuel.The improvement of composition in tar also indicated synergistic effect in the co-pyrolysis.展开更多
High volatile bituminous coal .was demineralized by a chemical method. The vibrations of the ＂aromatics＂ structure of graphite, crystalline or non-crystalline, were observed in the spectra at the 1600 cm-1 region. T...High volatile bituminous coal .was demineralized by a chemical method. The vibrations of the ＂aromatics＂ structure of graphite, crystalline or non-crystalline, were observed in the spectra at the 1600 cm-1 region. The band at 1477 cm-1 is assigned as VR band, the band at 1392 cm-1 as VL band and the band at 1540 cm-1 as GR band. Graphite structure remains after chemical leaching liberates oxygenated functional groups and mineral groups. The silicate bands between 1010 and 1100 cm-1 are active in the infrared （IR） spec^urn but inactive in the Raman spectrum. Absorption arising from C-H stretching in alkenes occurs in the region of 3000 to 2840 cm-~. Raman bands because of symmetric stretch of water molecules were also observed in the spectrum at 3250 cm-1 and 3450 cm-1. Scanning electron microscopy analy- sis revealed the presence of a graphite layer on the surface. Leaching of the sample with hydrofluoric acid decreases the mineral phase and increases the carbon content. The ash content is reduced by 84.5wt% with leaching from its initial value by mainly removing aluminum and silicate containing minerals.展开更多
The adsorption behavior of CO_2, CH_4 and their mixtures in bituminous coal was investigated in this study. First, a bituminous coal model was built through molecular dynamic(MD) simulations, and it was confirmed to b...The adsorption behavior of CO_2, CH_4 and their mixtures in bituminous coal was investigated in this study. First, a bituminous coal model was built through molecular dynamic(MD) simulations, and it was confirmed to be reasonable by comparing the simulated results with the experimental data. Grand Canonical Monte Carlo(GCMC)simulations were then carried out to investigate the single and binary component adsorption of CO_2 and CH_4with the built bituminous coal model. For the single component adsorption, the isosteric heat of CO_2 adsorption is greater than that of CH_4 adsorption. CO_2 also exhibits stronger electrostatic interactions with the heteroatom groups in the bituminous coal model compared with CH_4, which can account for the larger adsorption capacity of CO_2 in the bituminous coal model. In the case of binary adsorption of CO_2 and CH_4mixtures, CO_2 exhibits the preferential adsorption compared with CH_4 under the studied conditions. The adsorption selectivity of CO_2 exhibited obvious change with increasing pressure. At lower pressure, the adsorption selectivity of CO_2 shows a rapid decrease with increasing the temperature, whereas it becomes insensitive to temperature at higher pressure. Additionally, the adsorption selectivity of CO_2 decreases gradually with the increase of the bulk CO_2 mole fraction and the depth of CO_2 injection site.展开更多
A high volatile bituminous coal was subjected to a series of organic acid treatment in steps using citric acid (1 hr and 2 hr) and buffered EDTA with acetic acid (1 to 3 hr) at room temperature. Leaching was performed...A high volatile bituminous coal was subjected to a series of organic acid treatment in steps using citric acid (1 hr and 2 hr) and buffered EDTA with acetic acid (1 to 3 hr) at room temperature. Leaching was performed with acetic acid (2N) also for 1 hr. Citric acid procedure reduced the mineral matter below 1.94%. Calcites and aluminates are completely removed along with substantial quantity of silicates by citric acid leaching. The change in absorption of organic functional groups and mineral matter in coal samples were studied using Fourier transform infrared spectroscopy (FTIR). Analysis indicated that oxygen containing species were decreased in the coal structure during acetic acid and citric acid (40%) procedure and buffered EDTA 3 hours leaching. As the period of leaching with buffered EDTA increased from 1 hr to 3 hr, organic functional groups and mineral functional groups decreased its intensity. The results indicated that the described acid treatment procedures with citric acid have measurable effects on the coal structure.展开更多
Carcinogenic and mutagenic polycyclic aromatic hydrocarbons (PAHs) generated in coal combustion have caused great environmental health concern. Seventeen PAHs (16 high priority PAHs recommended by USEPA plus Benzo[e]p...Carcinogenic and mutagenic polycyclic aromatic hydrocarbons (PAHs) generated in coal combustion have caused great environmental health concern. Seventeen PAHs (16 high priority PAHs recommended by USEPA plus Benzo[e]pyrene) present in five raw bituminous coals and released during bituminous coal combustion were studied. The effects of combustion temperature, gas atmosphere, and chlorine content of raw coal on PAHs formation were investigated. Two additives (copper and cupric oxide) were added when the coal was burned. The results indicated that significant quantities of PAHs were produced from incomplete combustion of coal pyrolysis products at high temperature, and that temperature is an important causative factor of PAHs formation. PAHs concentrations decrease with the increase of chlorine content in oxygen or in nitrogen atmosphere. Copper and cupric oxide additives can promote PAHs formation (especially the multi-ring PAHs) during coal combustion.展开更多
The influence of a pre-oxidation process on the chemical properties of crushed bituminous coal and on adsorption properties of the subsequently formed char and activated carbon is discussed in this paper. Datong bitum...The influence of a pre-oxidation process on the chemical properties of crushed bituminous coal and on adsorption properties of the subsequently formed char and activated carbon is discussed in this paper. Datong bituminous coal samples sized 6 mm were oxidized at different temperatures and for different times and then carbonized and activated by steam to obtain activated carbons. A Uniform Design method was used to arrange the experiments,IR and adsorption experiments were used to characterize these oxidized coals,chars and activated carbon samples. The results show that the carboxyl group disappeared and α-CH2 groups joined to alkenes decreased dramatically but the carbonyl group clearly increased in the coal sample oxidized at 543 K; The chemical composition of coal samples oxidized at lower temperature is different from that of coal oxidized at 543 K. Oxidizing coal samples at higher temperatures for a short time or at lower temperatures for a longer time resulted in activated carbon samples that tended toward the same adsorption properties: Iodine number 1100 mg/g and Methylene blue value 252 mg/g. The yield of activated carbon obtained from the pre-oxidized coal is 10% higher than the yield from parent coal but the activated carbons have the same adsorption properties.展开更多
In order to reduce the hazard of coal spontaneous combustion,the cross-linking reaction between O-containing functional groups of coal should be inhibited.So the inhibitory effect of an ionic liquid(IL) on the cross-l...In order to reduce the hazard of coal spontaneous combustion,the cross-linking reaction between O-containing functional groups of coal should be inhibited.So the inhibitory effect of an ionic liquid(IL) on the cross-linking reaction was studied.The O-containing functional groups change the weight loss and H_2O,CO_2,CO yields of bituminous coal before and after[H0Emim][BF_4]and[Amim]Cl pre-treatment and were detected by Fourier Transform Infrared spectroscopy(FT1R) and Thermo Gravimetric(TC) analysis.The results show that | AmimjCI has a weaker ability to inhibit the cross-linking reaction of bituminous coal compared to[HOEmim][BF_4].Besides,based on Quantum Chemistry calculation,it was found that the different inhibiting effects of |H0Emim][BF_4]and[Amim]Cl are greatly related to their anions and the H linked with C2 atom on the imidazole ring.The H-donor ability of coal will be enhanced by[HOEmim][BF_4]leading to a weaker cross-linking reaction of coal.展开更多
The thermogravimetry analyzer coupled with the pyrolysis gas chromatography/time-of-flight mass spectrometry technology was used in this study to investigate the mass loss behavior and volatile release characteristics...The thermogravimetry analyzer coupled with the pyrolysis gas chromatography/time-of-flight mass spectrometry technology was used in this study to investigate the mass loss behavior and volatile release characteristics of a bituminous coal. The results showed that with an increasing heating rate, the characteristic parameters and TG/DTG curves shifted obviously to the higher temperature region. The pyrolysis of a bituminous coal at different heating rates can be divided into two stages according to the Coats-Redfern(C-R) plots. The activation energy obtained from the C-R method is 50.21—85.14 kJ/mol and 5.14—7.24 kJ/mol at a heating rate range of 8—300 °C/min for the first and second pyrolysis stages, respectively. Aromatic hydrocarbons were dominant in the volatile products during fast pyrolysis of the coal, followed by the olefins, whereas the phenols were the third major components. With the increase of pyrolysis temperature, the heavy components in the volatile species increased; meanwhile the phenol cracking reactions were intensified. The carbon number of olefins was mainly concentrated in 3—9, and the aromatics were mainly composed of the compounds of C_6—C_(13).This study can provide a basic reference for fast pyrolysis of coal and other thermal chemical conversion processes.展开更多
Through a lot of experiments, a new kind of stove using horizontal combustion tech-nique for bituminous coal briquet has been developed. Making use of this stove, studies have been made on burning process of bituminou...Through a lot of experiments, a new kind of stove using horizontal combustion tech-nique for bituminous coal briquet has been developed. Making use of this stove, studies have been made on burning process of bituminous coal briquet, distribution of temperature field in the stove, the regularities of evolution and combustion of volatile matter, the burning rate and edi-ciency of bituminous coal briquet, characteristics of fire-sealing and sulfur-retention. The results show that, with the technique, some achievements can be obtained in combustion of bituminous coal briquet, such as lower pollution that the flue gas black degree is below 0. 5R and dust con-centration is below 90 mg/m3. The stove’s combustion efficiency reaches 90%, sulfur fixing effi-ciency is 60%, and oO concentration is decreased by 40% compared with other traditional stoves. With so many advantages, the stove can be used extensively in civil stoves and smaller industrial boilers.展开更多
The formation mechanism of methane （CH4） during coal evolution has been investigated by density functional theory （DFT） of quantum chemistry. Thermogenic gas, which is generated during the thermal evolution of med...The formation mechanism of methane （CH4） during coal evolution has been investigated by density functional theory （DFT） of quantum chemistry. Thermogenic gas, which is generated during the thermal evolution of medium rank coal, is the main source of coalbed methane （CBM）. Ethylbenzene （A） and 6,7-dimethyl-5,6,7,8-tetrahydro-1-hydroxynaphthalene （B） have been used as model compounds to study the pyrolysis mechanism of highly volatile bituminous coal （R）, according to the similarity of bond orders and bond lengths. All possible paths are designed for each model. It can be concluded that the activation energies for H-assisted paths are lower than others in the process of methane formation; an H radical attacking on β-C to yield CH4 is the dominant path for the formation of CH4 from highly volatile bituminous coal. In addition, the calculated results also reveal that the positions on which H radical attacks and to which intramolecular H migrates have effects on methyl cleavage.展开更多
The internal mechanism of the high hydrophobicity of the coal samples from the Pingdingshan mining area was studied through industrial,element,and surface functional group analysis.Laboratory testing and molecular dyn...The internal mechanism of the high hydrophobicity of the coal samples from the Pingdingshan mining area was studied through industrial,element,and surface functional group analysis.Laboratory testing and molecular dynamics simulations were employed to study the impact of three types of surfactants on the surface adsorption properties and wettability of highly hydrophobic bituminous coal.The results show that the surface of highly hydrophobic bituminous coal is compact,rich in inorganic minerals,and poorly wettable and that coal molecules are dominated by hydrophobic functional groups of aromatic rings and aliphatic structures.The wetting performance of surfactants as the intermediate carrier to connect coal and water molecules is largely determined by the interaction force between surfactants and coal(Fs-c)and the interaction force between surfactants and water(Fs-w),which effectively improve the wettability of modified coal dust via modifying its surface electrical properties and surface energy.A new type of wetting agent with a dust removal rate of 89%has been developed through discovery of a compound wetting agent solution with optimal wetting and settling performance.This paper provides theoretical and technical support for removing highly hydrophobic bituminous coal dust in underground mining.展开更多
基金Supported by Hydrocarbon High-efficiency Utilization Technology Research Center of Yanchang Petroleum(Group)Co.Ltd.,China(ycsy2013ky-A-30)
文摘An experimental study on co-pyrolysis of bituminous coal and biomass was performed in a pressured fluidized bed reactor.The blend ratio of biomass in the mixture was varied between 0 and 100 wt%,and the temperature was over a range of 550–650℃ under 1.0 MPa pressure with different atmospheres.On the basis of the individual pyrolysis behavior of bituminous coal and biomass,the influences of the biomass blending ratio,temperature,pressure and atmosphere on the product distribution were investigated.The results indicated that there existed a synergetic effect in the co-pyrolysis of bituminous coal and biomass in this pressured fluidized bed reactor,especially when the condition of bituminous coal and biomass blend ratio of 70:30(w/w),600℃,and 0.3 MPa was applied.The addition of biomass influenced the tar and char yields and gas and tar composition during co-pyrolysis.The tar yields were higher than the calculated values from individual pyrolysis of each fuel,and consequently the char yields were lower.The experimental results showed that the composition of the gaseous products was not in accordance with those of their individual fuel.The improvement of composition in tar also indicated synergistic effect in the co-pyrolysis.
文摘High volatile bituminous coal .was demineralized by a chemical method. The vibrations of the ＂aromatics＂ structure of graphite, crystalline or non-crystalline, were observed in the spectra at the 1600 cm-1 region. The band at 1477 cm-1 is assigned as VR band, the band at 1392 cm-1 as VL band and the band at 1540 cm-1 as GR band. Graphite structure remains after chemical leaching liberates oxygenated functional groups and mineral groups. The silicate bands between 1010 and 1100 cm-1 are active in the infrared （IR） spec^urn but inactive in the Raman spectrum. Absorption arising from C-H stretching in alkenes occurs in the region of 3000 to 2840 cm-~. Raman bands because of symmetric stretch of water molecules were also observed in the spectrum at 3250 cm-1 and 3450 cm-1. Scanning electron microscopy analy- sis revealed the presence of a graphite layer on the surface. Leaching of the sample with hydrofluoric acid decreases the mineral phase and increases the carbon content. The ash content is reduced by 84.5wt% with leaching from its initial value by mainly removing aluminum and silicate containing minerals.
基金Supported by the CNPC Huabei Oilfield Science and Technology Development Project(HBYT-CYY-2014-JS-378,HBYT-CYY-2015-JS-47)
文摘The adsorption behavior of CO_2, CH_4 and their mixtures in bituminous coal was investigated in this study. First, a bituminous coal model was built through molecular dynamic(MD) simulations, and it was confirmed to be reasonable by comparing the simulated results with the experimental data. Grand Canonical Monte Carlo(GCMC)simulations were then carried out to investigate the single and binary component adsorption of CO_2 and CH_4with the built bituminous coal model. For the single component adsorption, the isosteric heat of CO_2 adsorption is greater than that of CH_4 adsorption. CO_2 also exhibits stronger electrostatic interactions with the heteroatom groups in the bituminous coal model compared with CH_4, which can account for the larger adsorption capacity of CO_2 in the bituminous coal model. In the case of binary adsorption of CO_2 and CH_4mixtures, CO_2 exhibits the preferential adsorption compared with CH_4 under the studied conditions. The adsorption selectivity of CO_2 exhibited obvious change with increasing pressure. At lower pressure, the adsorption selectivity of CO_2 shows a rapid decrease with increasing the temperature, whereas it becomes insensitive to temperature at higher pressure. Additionally, the adsorption selectivity of CO_2 decreases gradually with the increase of the bulk CO_2 mole fraction and the depth of CO_2 injection site.
文摘A high volatile bituminous coal was subjected to a series of organic acid treatment in steps using citric acid (1 hr and 2 hr) and buffered EDTA with acetic acid (1 to 3 hr) at room temperature. Leaching was performed with acetic acid (2N) also for 1 hr. Citric acid procedure reduced the mineral matter below 1.94%. Calcites and aluminates are completely removed along with substantial quantity of silicates by citric acid leaching. The change in absorption of organic functional groups and mineral matter in coal samples were studied using Fourier transform infrared spectroscopy (FTIR). Analysis indicated that oxygen containing species were decreased in the coal structure during acetic acid and citric acid (40%) procedure and buffered EDTA 3 hours leaching. As the period of leaching with buffered EDTA increased from 1 hr to 3 hr, organic functional groups and mineral functional groups decreased its intensity. The results indicated that the described acid treatment procedures with citric acid have measurable effects on the coal structure.
文摘Carcinogenic and mutagenic polycyclic aromatic hydrocarbons (PAHs) generated in coal combustion have caused great environmental health concern. Seventeen PAHs (16 high priority PAHs recommended by USEPA plus Benzo[e]pyrene) present in five raw bituminous coals and released during bituminous coal combustion were studied. The effects of combustion temperature, gas atmosphere, and chlorine content of raw coal on PAHs formation were investigated. Two additives (copper and cupric oxide) were added when the coal was burned. The results indicated that significant quantities of PAHs were produced from incomplete combustion of coal pyrolysis products at high temperature, and that temperature is an important causative factor of PAHs formation. PAHs concentrations decrease with the increase of chlorine content in oxygen or in nitrogen atmosphere. Copper and cupric oxide additives can promote PAHs formation (especially the multi-ring PAHs) during coal combustion.
基金Project 50204011 supported by the National Natural Science Foundation of China
文摘The influence of a pre-oxidation process on the chemical properties of crushed bituminous coal and on adsorption properties of the subsequently formed char and activated carbon is discussed in this paper. Datong bituminous coal samples sized 6 mm were oxidized at different temperatures and for different times and then carbonized and activated by steam to obtain activated carbons. A Uniform Design method was used to arrange the experiments,IR and adsorption experiments were used to characterize these oxidized coals,chars and activated carbon samples. The results show that the carboxyl group disappeared and α-CH2 groups joined to alkenes decreased dramatically but the carbonyl group clearly increased in the coal sample oxidized at 543 K; The chemical composition of coal samples oxidized at lower temperature is different from that of coal oxidized at 543 K. Oxidizing coal samples at higher temperatures for a short time or at lower temperatures for a longer time resulted in activated carbon samples that tended toward the same adsorption properties: Iodine number 1100 mg/g and Methylene blue value 252 mg/g. The yield of activated carbon obtained from the pre-oxidized coal is 10% higher than the yield from parent coal but the activated carbons have the same adsorption properties.
基金the support from the National Natural Science Foundation of China(Nos.51304073and 51304071)the Educational Commission of Henan Province(Nos.13A440324 and 12B440004)+1 种基金the Open Projects of State Key Laboratory of Coal Resources and Safe Mining,China University of Mining and Technology(No.12KF02)Henan Polytechnic University(Nos.B2012-068 and B2012-085)
文摘In order to reduce the hazard of coal spontaneous combustion,the cross-linking reaction between O-containing functional groups of coal should be inhibited.So the inhibitory effect of an ionic liquid(IL) on the cross-linking reaction was studied.The O-containing functional groups change the weight loss and H_2O,CO_2,CO yields of bituminous coal before and after[H0Emim][BF_4]and[Amim]Cl pre-treatment and were detected by Fourier Transform Infrared spectroscopy(FT1R) and Thermo Gravimetric(TC) analysis.The results show that | AmimjCI has a weaker ability to inhibit the cross-linking reaction of bituminous coal compared to[HOEmim][BF_4].Besides,based on Quantum Chemistry calculation,it was found that the different inhibiting effects of |H0Emim][BF_4]and[Amim]Cl are greatly related to their anions and the H linked with C2 atom on the imidazole ring.The H-donor ability of coal will be enhanced by[HOEmim][BF_4]leading to a weaker cross-linking reaction of coal.
基金financial support from the National Natural Science Foundation of China (Grant Nos. 21576293 and 21576294)
文摘The thermogravimetry analyzer coupled with the pyrolysis gas chromatography/time-of-flight mass spectrometry technology was used in this study to investigate the mass loss behavior and volatile release characteristics of a bituminous coal. The results showed that with an increasing heating rate, the characteristic parameters and TG/DTG curves shifted obviously to the higher temperature region. The pyrolysis of a bituminous coal at different heating rates can be divided into two stages according to the Coats-Redfern(C-R) plots. The activation energy obtained from the C-R method is 50.21—85.14 kJ/mol and 5.14—7.24 kJ/mol at a heating rate range of 8—300 °C/min for the first and second pyrolysis stages, respectively. Aromatic hydrocarbons were dominant in the volatile products during fast pyrolysis of the coal, followed by the olefins, whereas the phenols were the third major components. With the increase of pyrolysis temperature, the heavy components in the volatile species increased; meanwhile the phenol cracking reactions were intensified. The carbon number of olefins was mainly concentrated in 3—9, and the aromatics were mainly composed of the compounds of C_6—C_(13).This study can provide a basic reference for fast pyrolysis of coal and other thermal chemical conversion processes.
文摘Through a lot of experiments, a new kind of stove using horizontal combustion tech-nique for bituminous coal briquet has been developed. Making use of this stove, studies have been made on burning process of bituminous coal briquet, distribution of temperature field in the stove, the regularities of evolution and combustion of volatile matter, the burning rate and edi-ciency of bituminous coal briquet, characteristics of fire-sealing and sulfur-retention. The results show that, with the technique, some achievements can be obtained in combustion of bituminous coal briquet, such as lower pollution that the flue gas black degree is below 0. 5R and dust con-centration is below 90 mg/m3. The stove’s combustion efficiency reaches 90%, sulfur fixing effi-ciency is 60%, and oO concentration is decreased by 40% compared with other traditional stoves. With so many advantages, the stove can be used extensively in civil stoves and smaller industrial boilers.
基金supported by the Major Projects of National Science and Technology(Grant No.2011ZX05040-005-002-001)the National Natural Science Foundation of China(Grant No.21276171 and 21276003)+1 种基金the National Younger Natural Science Foundation of China(Grant No.21103120)China Postdoctoral Science Foundation(Grant No.2012M520608)
文摘The formation mechanism of methane （CH4） during coal evolution has been investigated by density functional theory （DFT） of quantum chemistry. Thermogenic gas, which is generated during the thermal evolution of medium rank coal, is the main source of coalbed methane （CBM）. Ethylbenzene （A） and 6,7-dimethyl-5,6,7,8-tetrahydro-1-hydroxynaphthalene （B） have been used as model compounds to study the pyrolysis mechanism of highly volatile bituminous coal （R）, according to the similarity of bond orders and bond lengths. All possible paths are designed for each model. It can be concluded that the activation energies for H-assisted paths are lower than others in the process of methane formation; an H radical attacking on β-C to yield CH4 is the dominant path for the formation of CH4 from highly volatile bituminous coal. In addition, the calculated results also reveal that the positions on which H radical attacks and to which intramolecular H migrates have effects on methyl cleavage.
文摘The internal mechanism of the high hydrophobicity of the coal samples from the Pingdingshan mining area was studied through industrial,element,and surface functional group analysis.Laboratory testing and molecular dynamics simulations were employed to study the impact of three types of surfactants on the surface adsorption properties and wettability of highly hydrophobic bituminous coal.The results show that the surface of highly hydrophobic bituminous coal is compact,rich in inorganic minerals,and poorly wettable and that coal molecules are dominated by hydrophobic functional groups of aromatic rings and aliphatic structures.The wetting performance of surfactants as the intermediate carrier to connect coal and water molecules is largely determined by the interaction force between surfactants and coal(Fs-c)and the interaction force between surfactants and water(Fs-w),which effectively improve the wettability of modified coal dust via modifying its surface electrical properties and surface energy.A new type of wetting agent with a dust removal rate of 89%has been developed through discovery of a compound wetting agent solution with optimal wetting and settling performance.This paper provides theoretical and technical support for removing highly hydrophobic bituminous coal dust in underground mining.
