Samples of five types of coal and oil shale from the Daqing region have been subjected to co-pyrolysis in different blending ratios with thermo-gravimetry(TG),given a heating rate of 30 °C/min to a final temperat...Samples of five types of coal and oil shale from the Daqing region have been subjected to co-pyrolysis in different blending ratios with thermo-gravimetry(TG),given a heating rate of 30 °C/min to a final temperature of 900 °C.Investigations on pyrolysis of mixing coal and oil shale in different proportions were carried out,indicating that the main scope of weight loss corresponding to hydrocarbon oil and gas release was between 350 and 550 °C.At higher temperatures,significant weight loss was attributed to coke decomposition.Characteristic pyrolysis parameters of blends from oil shale and the high ranked XZ coal varied with the blending ratio,but oil shale dominated the process.At the same blending proportions,highly volatile medium and low ranked coal of low moisture and ash content reacted well during pyrolysis and could easily create synergies with oil shale.Medium and high ranked coal with high moisture content played a negative role in co-pyrolysis.展开更多
In order to improve the dewatering rate and the effect of fine clean coal(FCC), the advanced method offine coal( 0.5 mm) dewatering and the correlated basic theory were investigated in this study. It was found that th...In order to improve the dewatering rate and the effect of fine clean coal(FCC), the advanced method offine coal( 0.5 mm) dewatering and the correlated basic theory were investigated in this study. It was found that the dewatering by sleeve type press filter was an efficient way of FCC dewatering. On the other hand, the results also proved that particle size distribution, volatile matter, ash content, pore size distribution and specific surface area of coal particles of FCC samples, as well as viscosity and density of FCC slurry, were important parameters in determining the process of efficient dewatering. Especially, wet mass to dry mass, specific resistance of average mass, compressibility factor and microstructure of filter cake explained the reasons and mechanisms of fine clean coal efficient dewatering.展开更多
Coal samples in the air for three months were characterized by Thermogravimetric Analysis (TGA). The effect of a PVA oxygen-insulating barrier on the spontaneous combustion of coal was examined. The moisture loss acti...Coal samples in the air for three months were characterized by Thermogravimetric Analysis (TGA). The effect of a PVA oxygen-insulating barrier on the spontaneous combustion of coal was examined. The moisture loss activation energy, oxidation activation energy and combustion activation energy were calculated by an integral method using the Coats-Redfen formula. The results show that the tendency for spontaneous combustion of three coal samples (judged by the activation energy) falls in the order: CYW>YJL>SW. The oxidation activation energy and combustion activation energy of coal protected by the PVA oxygen-insulating barrier increased. A significant increase in the combustion activation energy was noted, especially for the CYW coal where the in-crease was 28.53 kJ/mol. Hence, oxidation of the protected coal samples was more difficult. The PVA oxygen-insulating barrier helps to prevent spontaneous combustion of the coal.展开更多
Coal sludge slurry(CSS) is an alternative fuel and a potential competitive method for sludge reduction.Based on the researches of coal water slurry, we studied CSSs by using a wet-grinding process with different types...Coal sludge slurry(CSS) is an alternative fuel and a potential competitive method for sludge reduction.Based on the researches of coal water slurry, we studied CSSs by using a wet-grinding process with different types of regional municipal sludge(sludge) in an orthogonal experiment. The sludge type,sludge mixing proportion, dosage of dispersant, and grinding time were tested in this study. The results show that water content and its occurrence characteristics in the sludge have primary hindering influences on slurry ability. The range of fixed-viscosity concentrations with raw wet sludge is from 50.78%to 44.40%(by weight), while the range is from 53.35% to 51.51%(by weight) with dry sludge. All of the CSSs exhibit shear-thinning behaviors with different variation trends, especially the CSSs with more than 15%(by weight) raw wet sludge in it. Adding the same proportion of raw wet sludge increases the thixotropic properties of CSSs and the highest area of thixotropy loop is 3065 Pa/s, while the highest value of dry sludge is 1798 Pa/s. Hydrophilic group plays an important role in adsorbing water and building three-dimension networks with other particles, which is the main reason for CSS properties.Therefore, the mechanism can be used to find the way for making high quality CSS.展开更多
Two coal samples of similar rank were chosen from Australia and China to investigate the differences in Coal-Water Slurry (CWS) made from them. The effect of ash content and particle size gradation on these properties...Two coal samples of similar rank were chosen from Australia and China to investigate the differences in Coal-Water Slurry (CWS) made from them. The effect of ash content and particle size gradation on these properties was also studied. Different grinding times were used when grinding the two coals and particle size analysis of these ground coals was used to select samples with a ''double-peak'' particle size distribution. All the ''double-peak'' samples were used to prepare a CWS. The concentration, viscosity, fluidity, and stability of each CWS were measured. The results show that the properties of a CWS prepared from a coal sample with a ''double-peak'' size distribution are better than those CWS prepared from samples with a mono-modal particle distribution. The ash content of Australian coal is 21.72% higher than the ash content of Shenhua coal. The highest coal concentration in slurry from the Australia coal is 11.01% higher than in CWS from the Shenhua coal. The fluidity and stability of the CWS prepared from the Australian coal are both better than the fluidity and stability of slurry prepared from Shenhua coal. High ash content in the Australian coal improves the pulping results of a CWS made from it.展开更多
NiO-SnO2 composite nanofibers were synthesized via electrospinning techniques and characterized by X-ray diffraction,scanning electron microscopy,transmission electron microscopy,and X-ray photoelectron spectroscopy.T...NiO-SnO2 composite nanofibers were synthesized via electrospinning techniques and characterized by X-ray diffraction,scanning electron microscopy,transmission electron microscopy,and X-ray photoelectron spectroscopy.Three types of sensor were applied to investigate the sensing properties of these nanofibers.Sensors A were fabricated by mixing the nanofibers with deionized water,and then grinding and coating them on ceramic tubes to form indirect heated gas sensors.Microsensors B(with an area of 600 μm×200 μm) were formed by spinning nanofibers on Si substrates with Pt signal electrodes and Pt heaters.Sensors C were fabricated by spinning nanofibers on plane ceramic substrates(with a large area of 13.4 mm×7 mm) with Ag-Pd signal electrodes only.The operating temperatures of sensors A and B were controlled by adjusting heater currents,and the operating temperatures of sensors C were controlled by adjusting an external temperature control device.Experimental results show that sensors C possess the highest sensing properties,such as high response values(about 42 to 100 μL/L ethanol),quick response/recovery speeds(the response and recovery times were 4 and 7 s,respectively),and excellent consistencies.These phenomena were explained by the retained fiber morphology and suitable sensor area.The presented results can provide some useful information for the design and optimization of one-dimensional nanomaterial-based gas sensors.展开更多
基金the financial support from the National Natural Science Foundation of China (No. 51104159)the Special Found of Central Universities for Basic Scientific Research Projects (No. 2011QNB06)
文摘Samples of five types of coal and oil shale from the Daqing region have been subjected to co-pyrolysis in different blending ratios with thermo-gravimetry(TG),given a heating rate of 30 °C/min to a final temperature of 900 °C.Investigations on pyrolysis of mixing coal and oil shale in different proportions were carried out,indicating that the main scope of weight loss corresponding to hydrocarbon oil and gas release was between 350 and 550 °C.At higher temperatures,significant weight loss was attributed to coke decomposition.Characteristic pyrolysis parameters of blends from oil shale and the high ranked XZ coal varied with the blending ratio,but oil shale dominated the process.At the same blending proportions,highly volatile medium and low ranked coal of low moisture and ash content reacted well during pyrolysis and could easily create synergies with oil shale.Medium and high ranked coal with high moisture content played a negative role in co-pyrolysis.
基金the National Natural Science Foundation of China (No. 21206190)the Science Fund Project of China University of Mining & Technology (No. 2008A027)the China Coal Industry Association 2012 Annual Scientific and Technological Guidance Project (Nos. MTKJ 2012-288 and MTKJ 2012-289) for their financial support
文摘In order to improve the dewatering rate and the effect of fine clean coal(FCC), the advanced method offine coal( 0.5 mm) dewatering and the correlated basic theory were investigated in this study. It was found that the dewatering by sleeve type press filter was an efficient way of FCC dewatering. On the other hand, the results also proved that particle size distribution, volatile matter, ash content, pore size distribution and specific surface area of coal particles of FCC samples, as well as viscosity and density of FCC slurry, were important parameters in determining the process of efficient dewatering. Especially, wet mass to dry mass, specific resistance of average mass, compressibility factor and microstructure of filter cake explained the reasons and mechanisms of fine clean coal efficient dewatering.
基金support provided by the National Natural Science Foundation of China (No20807056)the Research Fund for the Doctoral Program of Higher Education of China (No20060290506)the Foundation of China University of Mining & Technology (Nos0H060097 and 0H080254)
文摘Coal samples in the air for three months were characterized by Thermogravimetric Analysis (TGA). The effect of a PVA oxygen-insulating barrier on the spontaneous combustion of coal was examined. The moisture loss activation energy, oxidation activation energy and combustion activation energy were calculated by an integral method using the Coats-Redfen formula. The results show that the tendency for spontaneous combustion of three coal samples (judged by the activation energy) falls in the order: CYW>YJL>SW. The oxidation activation energy and combustion activation energy of coal protected by the PVA oxygen-insulating barrier increased. A significant increase in the combustion activation energy was noted, especially for the CYW coal where the in-crease was 28.53 kJ/mol. Hence, oxidation of the protected coal samples was more difficult. The PVA oxygen-insulating barrier helps to prevent spontaneous combustion of the coal.
基金supported by the National Natural Science Foundation of China (Nos. 51204179, 51204182)the Natural Science Foundation of Jiangsu Province of China (No. BK20141242)the Fundamental Research Funds for the Central Universities of China (No. 2014XT05)
文摘Coal sludge slurry(CSS) is an alternative fuel and a potential competitive method for sludge reduction.Based on the researches of coal water slurry, we studied CSSs by using a wet-grinding process with different types of regional municipal sludge(sludge) in an orthogonal experiment. The sludge type,sludge mixing proportion, dosage of dispersant, and grinding time were tested in this study. The results show that water content and its occurrence characteristics in the sludge have primary hindering influences on slurry ability. The range of fixed-viscosity concentrations with raw wet sludge is from 50.78%to 44.40%(by weight), while the range is from 53.35% to 51.51%(by weight) with dry sludge. All of the CSSs exhibit shear-thinning behaviors with different variation trends, especially the CSSs with more than 15%(by weight) raw wet sludge in it. Adding the same proportion of raw wet sludge increases the thixotropic properties of CSSs and the highest area of thixotropy loop is 3065 Pa/s, while the highest value of dry sludge is 1798 Pa/s. Hydrophilic group plays an important role in adsorbing water and building three-dimension networks with other particles, which is the main reason for CSS properties.Therefore, the mechanism can be used to find the way for making high quality CSS.
基金received funding from the Australian Government as part of the Asia-Pacific Partnership on Clean Development and Climate
文摘Two coal samples of similar rank were chosen from Australia and China to investigate the differences in Coal-Water Slurry (CWS) made from them. The effect of ash content and particle size gradation on these properties was also studied. Different grinding times were used when grinding the two coals and particle size analysis of these ground coals was used to select samples with a ''double-peak'' particle size distribution. All the ''double-peak'' samples were used to prepare a CWS. The concentration, viscosity, fluidity, and stability of each CWS were measured. The results show that the properties of a CWS prepared from a coal sample with a ''double-peak'' size distribution are better than those CWS prepared from samples with a mono-modal particle distribution. The ash content of Australian coal is 21.72% higher than the ash content of Shenhua coal. The highest coal concentration in slurry from the Australia coal is 11.01% higher than in CWS from the Shenhua coal. The fluidity and stability of the CWS prepared from the Australian coal are both better than the fluidity and stability of slurry prepared from Shenhua coal. High ash content in the Australian coal improves the pulping results of a CWS made from it.
基金supported by the National High Technology Research and Development Program of China (2009AA03Z401)the Scientific Research Foundation for Doctoral Program of Liaoning Province of China (20101016)Research Fund for the Doctoral Program of Higher Education of China (20110041120045)
文摘NiO-SnO2 composite nanofibers were synthesized via electrospinning techniques and characterized by X-ray diffraction,scanning electron microscopy,transmission electron microscopy,and X-ray photoelectron spectroscopy.Three types of sensor were applied to investigate the sensing properties of these nanofibers.Sensors A were fabricated by mixing the nanofibers with deionized water,and then grinding and coating them on ceramic tubes to form indirect heated gas sensors.Microsensors B(with an area of 600 μm×200 μm) were formed by spinning nanofibers on Si substrates with Pt signal electrodes and Pt heaters.Sensors C were fabricated by spinning nanofibers on plane ceramic substrates(with a large area of 13.4 mm×7 mm) with Ag-Pd signal electrodes only.The operating temperatures of sensors A and B were controlled by adjusting heater currents,and the operating temperatures of sensors C were controlled by adjusting an external temperature control device.Experimental results show that sensors C possess the highest sensing properties,such as high response values(about 42 to 100 μL/L ethanol),quick response/recovery speeds(the response and recovery times were 4 and 7 s,respectively),and excellent consistencies.These phenomena were explained by the retained fiber morphology and suitable sensor area.The presented results can provide some useful information for the design and optimization of one-dimensional nanomaterial-based gas sensors.
