Kai Wang

Thermogravimetric Dynamics and FTIR Analysis on Oxidation Properties of Low-Rank Coal at Low and Moderate Temperatures

Oxidation properties of two coals, lignite and bituminous, at low and moderate temperatures were investigated using thermalgravimetric analysis (TGA) and Fourier transform infrared spectroscopy (FTIR) methods. The apparent kinetic parameters were determined by the first-order Coats & Redfern method based on the TGA results. The mass developments of the two coals during the experimental temperature range of 25–400°C suggest that lignite is more prone to spontaneous combustion than bituminous coal. The kinetic analysis results show that all the absolute values of the apparent activation energies of lignite are less than that of bituminous coal, indicating that it is easier for lignite oxidation. FTIR spectra show that the structure of coals changed differently during oxidation. The aliphatic hydrogen groups (mainly the -CH3 groups), associated hydroxyls, and substituent groups in aromatic structures decreased, and carbonyl species increased in bituminous coal. For lignite, both -CH2 and -CH3 groups decreased and carbonyls increase initially and then decrease corresponding to formation of a large amount of ether bonds. The substituent-aromatic structures increase slightly in lignite.

Ultrasonic-Aided Fabrication of Nanostructured Au-Ring Microelectrodes for Monitoring Transmitters Released from Single Cells

We report a novel ultrasonic-aided fast and straightforward approach to fabricate Au microelectrodes by electroless deposition of nanostructured gold films on the rigid outer surface of pulled glass capillaries. Microelectrodes with tip diameters ranging from several hundred nanometers to several micrometers were fabricated within 20 min via three sequential ultrasonication steps. The ultrasonication technique has been validated to be a very effective route in engineering the morphology of Au film surfaces and improves the fabrication efficiency of Au microelectrodes. The nanostructured surfaces of the Au microelectrodes demonstrate excellent sensing activity and antifouling for dopamine oxidation. The microelectrodes were applied for measurement of catecholamines released from exocytosis events from single chromaffin cells and exhibited faster dynamic peak parameters, compared with carbon fiber microelectrodes. This report provides a generally accessible and complementary platform for analyzing catecholamines release events, which should be useful for new electrode designs and neurochemical sensing.

Effect of Ionic Liquids on Low-Temperature Oxidation of Coal

Three 1-butyl-3-methyl imidazolium ([BMIm]+) based ionic liquids (ILs) with different anions, including tetrafluoroborate ([BF4]−), acetate ([Ac]−), and trifluoromethane sulfonate ([OTf]−), were selected to investigate the inhibition effect of ILs on low-temperature oxidation of coal by oxidizing raw coal and ILs-treated coals under air during 20–180°C. The coal structure was characterized by Raman spectroscopy and Fourier transform infrared spectroscopy (FTIR). The Raman results show that the ILs treatment can inhibit the low-temperature oxidation activity of disorder structure in coal. The FTIR results demonstrate that the ILs can break and dissolve the associated hydrogen bonds and methylene groups, so that the low-temperature oxidation activity of ILs-treated coal is inhibited. The analysis on oxygen consumption and index gases of coals by gas chromatograph further confirms the spectra results that ILs treatment can inhibit the low-temperature oxidation of coal. The inhibition effect is in the order of [BMIm][OTf] > [BMIm][BF4] > [BMIm][Ac].

A Combined Raman Spectroscopic and Thermogravimetric Analysis Study on Oxidation of Coal with Different Ranks.

Raman spectroscopy and nonisothermal thermogravimetric analysis (TGA) measurements have been reported for different rank coals (lignite, bituminous coal, and anthracite) and the relationship between the measurements was examined. It was found that the Raman spectra parameters can be used to characterize structure changes in the different rank coals, such as the band area ratios based on the curve-fitted results. Higher ranked coal was found to have higher values of I GR/I All and I (G + GR)/I All but lower values of I D/I (G+GR), I DL/I (G+GR), I (S + SL)/I (G+GR), and I (GL+GL)/I (G+GR). The oxidation properties of the coal samples were characterized by the reactivity indexes T ig, T 20%, and T max from TGA data which were found to correlate well with the band area ratios of I GR/I All, I (G + GR)/I All, and I (S + SL)/I (G+GR). Based on these correlations, the Raman band area ratios were found to correlate with the oxidation activity of coal providing additional structural information which can be used to understand the changes in the TGA measurements.

Numerical simulation and application study on a remote emergency rescue system during a belt fire in coal mines

Once initiated, coal mine belt fires can develop rapidly, and if improperly controlled, these fires could easily lead to the airflow disorders that undermine the function of the ventilation system, and the smoke plume could lead to heavy casualties. However, belt fires can be effectively prevented by establishing a fire smoke plume control system. According to the characteristics of fire smoke plume control in the ventilation network, models of ventilation systems are analyzed, and different methods of fire emergency rescue systems are designed. A mathematical model for fire smoke flow was developed based on the west-wing mining area in Long-Dong coal mine. The distributions of the smoke parameters and airflow temperature on the roadway before and after performing the smoke flow control measures were simulated by Fluent software. The results indicate that 37xa0min after the fire began, the smoke plume had invaded all of the roadways in the west-wing mining area. The average temperature of the roadway in the west mining area is 332xa0K, the O2 concentration is 14.8xa0%, the CO2 concentration is 5.1xa0% and the highest concentration of CO is 0.98xa0%. In this environment, miners in distress are unable to survive. A function to adjust the opening degree of the air-doors was designed, and the air volume control of the key branches was realized during a fire emergency rescue. A permanent refuge chamber was situated in the mining area to provide a safe shelter for miners when a disaster occurs. Many field exercises have verified the combined function of the emergency rescue system and refuge chamber to ensure the security of the miners in the underground coal mine.

Impact of Super Absorbent Polymer and Plants on Microbial Community and Petroleum Hydrocarbon Degradation in Contaminated Soil

A greenhouse pot test, in which wheat, cabbage, spinach were cultivated separately in petroleum contaminated soil with and without super absorbent polymer (SAP), was conducted to evaluated the effect of plants and SAP on soil microbiological properties. phospholipid fatty acids (PLFAs) profiles were analyzed to reveal the microbial communities. As a measure of the functional activity of soil microbial community, the ratio of degraded to total petroleum hydrocarbon (TPH) in soil was estimated. The results indicated that SAP had an important effect on the soil microbial community and its degrading TPH activities. First, the principal component analysis (PCA) of the PLFA signatures revealed marked changes between soil with SAP and without SAP. In addition, the total amount and the profile of PLFA were significantly different between the untreated and SAP-amended soils. Using PLFA patterns as a biomarker, it was found that gram-positive bacteria (G+) were more sensitive to SAP than gram-negative bacteria (G-), and the biomass of G+ was higher in soil with SAP than in that without SAP. Second, the crop could stimulate the growth of soil microorganisms; however, the differences depended clearly on the crop species. The G+ and G- biomass was increased in cabbage, spinach soil containing SAP, but was decreased in wheat soils. The population of fungi was increased in cabbage and spinach soils containing SAP, but was decreased in wheat soil with SAP. The population of actinomycetes was decreased in all soils with SAP. Third, the ratio of degraded to TPH was slightly increased in soil with SAP treatment, but a significant change depended on the crop species. In total, 12 different PLFAs were identified, including saturated, monounsaturated, branched, and polyunsaturated species. There was a clear difference in the PLFAs composition between soils with and without SAP.

A New Idea of Suppressing Coal Spontaneous Combustion in Goaf Using Environment-Friendly Ionic Liquids

In order to reduce the pollution and toxicity of current coal fire fighting materials used in underground mines, this paper proposes that the functional ionic liquid, a kind of green material, may be utilized to suppress the spontaneous fire based on coals chemistry structures. According to the Fourier Transform Infrared (FTIR) spectroscopy experiment in low-temperature oxidation of coal, we found that the aliphatics active groups, decreasing with rising temperatures, react with oxygen with stable and unstable oxygen-containing groups produced such as aromatic ketone and aldehyde. If the aliphatics active groups can be destroyed, then the oxidation of coal would be restricted and prevented essentially. According to the active structures of coal, this environment-friendly fire-fighting functional ionic liquid should be hydrophilic and stable in water, and be effective in dissolving active groups and the produced dangerous gases, inhibiting oxidation and conducting reaction heat, thus it can be possible to be applied in suppressing spontaneous combustion in the underground coal mine goaf. Using environment-friendly functional ionic liquid to fight mine spontaneous fire will provide a possible research direction for safety technologies in mining.

Quantitative Study for Drilling Process on Human Factor Risk Mitigation Capacity

In order to reduce the human factor risk in drilling process, the author analyzed the primary reason of human factor risk in drilling process, selected twelve risk control measures and toke Delphi method to quantify the human factor risk mitigation capacity resulting from the selected risk control measures. The results shows that the human risk control measures exist in three tiers of effectiveness that with each tier being separated by nearly an order of magnitude, and the types of most risk mitigation are risk codes such as injury by machine, fall from height, contact with harmful material. And the most minimally risk mitigation ones are muscle strain, fire explosion and other types. Finally these data, which will be valuable for drilling companies to strategically allocate limited resources to their safety management plan, can evaluate the expected effectiveness resulting from risk control measures.

Study on RBF Neural Network PID Control for Hydro-Viscous Drive System

To verify the applicability of RBF neural network PID control on speed regulating start control for hydro-viscous drive system, analyze the principle of RBF neural network PID control, the simulation model is established based on SIMULINK and the control characteristics are analyzed based on the AMESim/MATLAB co-simulation. The results show that RBF neural network PID control has a good self-correcting effect on speed regulating start of hydro-viscous; it can make right judgments according to the error and error rate and adjust the output speed towards opposite direction of error; meanwhile, it ensures the smoothness of output curve and avoids excessive mechanical impact. The results play a guiding role for control strategy selection of speed regulating start.

The Experiments of Coalbed Methane Penetration Law in Zhaogu Mine

Set the raw coal samples of zhaogu mine in Jiaozuo as the object of study, with a self-developed equipment for thermo-fluid-solid-stress coupling of coal containing methane, analyse the relationship between permeability of raw coal samples and the change of effective stress, resultant stress strain process of raw coal samples. Experimental results show that The permeability of coal samples have stress sensitivity, permeability represents nonlinear decreasing relationship with effective stress increasing, Possess the law of negative exponent,This is consistent with the results of previous studies. During the full stress-strain process, strain increases with the stress increasing, penetration rate changed with the strain of the coal sample Increase after reducing ,on compaction stage stage and elastic deformation stage, transfusion decreased with stress increased , on yield deformation stage, permeability of coal samples reached minimum and began to overtake, on brittle break stage and residual strength stage, permeability increased by a large margin, mainly due to the coal macroscopic fissures.