Solid Fuel Chemistry最新文献

To study the oxidation heating process and molecular structure characteristics of coal in CO₂ atmosphere, the characteristic temperature, activation energy, and functional group evolution laws of three kinds of coal with different degrees of metamorphism were studied by thermogravimetric and Fourier infrared spectroscopy experiments, and the dynamic change process of kinetic parameters with temperature was obtained. The results showed that in the CO₂ atmosphere, the temperature range of the three coal combustion stages presents “lag”; Compared with the air atmosphere, the ignition temperature, combustion temperature and maximum weight loss temperature increase. CO₂ inhibits the process of coal combustion. In an inert atmosphere, the combustibility of coal decreases. The lower the metamorphic degree of coal, the lower the characteristic temperature, the more unstable the molecular structure, and the lower the activation energy required for oxidation. With the increase of metamorphism, the inhibition ability of CO₂ was enhanced. By contrast analysis of infrared spectrum, it is found that raw coal has more active groups and higher oxidation activity than coal under inert atmosphere. The inhibition of CO₂ on coal spontaneous combustion is revealed by the increase of combustion and activation energy and the decrease of active functional group.

In this study, the Palm and Juliflora biodiesel (PJ100) mixture is prepared in the proportion of (50% palm biodiesel by volume and 50% juliflora biodiesel by volume). The different fuel samples were prepared with PJ100 and diesel. 20% of PJ100 + 80% of diesel (B20), Partial hydrogenation of PJ100 was carried out and prepared 20% of hydrogenated PJ100+80% of diesel (HB20) and 2000 ppm of DTBP (Di-tert-butyl peroxide) additive was added with B20 (B20 + DTBP). The above fuel samples examined a single-cylinder diesel engine’s combustion and emission characteristics. An autoclave reactor was used for the hydrogenation of PJ biodiesel, and gas chromatography was used to evaluate the fatty acid composition of biodiesel. Tamson FBT equipment was used to verify the filterability characteristics of all the biodiesel blends and diesel. The FBT results show that B20 and HB20 are 1.36 and 1.4, respectively, which aligns with the ASTM standard (D2068-14). Ignition delay and combustion duration of HB20 and B20+DTBP are significantly improved than the B20 blend. The Brake thermal efficiency of HB20 is 7.7% higher than B20. Similarly, NOx emission was reduced in HB20, and B20+DTBP fuels were 8.66% and 9.74%, respectively, compared to the B20 blend. Based on the above findings, a partial hydrogenation (HB20) blend has been a better way to improve the trade-off qualities than adding DTBP with B20.

To study the inerting and cooling characteristics of liquid CO₂ in coal mine, the coal samples before and after liquid CO₂ inerting treatment were analyzed and studied. The results of temperature-programmed oxidation experiment show that the coal sample can inhibit the oxidation of coal to a certain extent after liquid CO₂ inerting. The TG-DSC experiment results show that T1 and T2 of treated coal are higher than those of raw coal, which indicates that the desorption and heat absorption of CO₂ has a more obvious effect on the early stage of coal oxidation at low temperature. The characteristic temperature T3 and T4 of L‑CO₂ coal are lower than that of raw coal, indicating that the oxidation rate of raw coal is faster. The T4 of L-CO₂ coal is higher than that of raw coal. The results showed that L-CO₂ inhibited spontaneous combustion of coal. After the coal sample was treated with liquid CO₂, the apparent activation energy of the coal increased slightly. The heat release of raw coal is 10.78% higher than that of treated coal samples. From the point of view of heat change, it shows that raw coal is more prone to spontaneous combustion. Liquid CO₂ has a good cooling and inerting effect on fire prevention.

Biodiesels are widely recognized as a leading choice among the alternative options to traditional petrodiesel fuel due to their significant technical and economic advantages. The transesterification process was utilized to prepare biodiesel from palm and prosopis juliflora oil, using NaOH as the catalyst and methanol as the alcohol in this particular experiment. Palm and juliflora biodiesel mixture was prepared as PJ0, PJ20, PJ40, PJ60, PJ80 and PJ100 by weight percentage (0, 20, 40, 60, 80, and 100%). Based on the physio-chemical properties, PJ60 (B100) was selected as a superior blend and mixed with pure diesel to create different test fuels with varying biodiesel (B0, B20, B30, B40, and B100) concentrations. The experiment examined a four-stroke, single-cylinder CI engine’s fuel filterability, performance and emission characteristics. The results indicated the filter blocking tendency value of B20 as 1.36, which is in line with ASTM standard (D2068-14), also lower pressure drop and higher soaking strength among other blends. The B20 blend increased brake-specific fuel consumption by 0.27 kg/kW-h at 3.84%, and brake thermal efficiency was 32.64%, closer to neat diesel in full load. Hydrocarbon, carbon monoxide and smoke emissions of B20 blends were decreased by 2.6, 2.5, and 9.42%, respectively. Besides, NOx emission exhibited a significant increase compared to base diesel. The above results aided the conclusion that the B20 mixture holds the potential of alternate fuel for IC engines.

To reveal the mechanism of gas displacement in coal seam by N₂, the desorption behavior of CH₄ after N₂ injection was studied by using giant canonical ensemble Monte Carlo (GCMC) and molecular dynamics (MD) methods. Through the adsorption and replacement of CH₄ by N₂ on three kinds of coal samples, the influence of different metamorphic coals on the replacement of CH₄ by N₂ was analyzed from the replacement amount and injection ratio. The results show that the average relative concentration of CH₄ in vacuum layer increases after N₂ implantation. The more N₂ injection pressure, the more gas desorption. It can be seen from the two indexes of replacement amount and replacement ratio that CH₄ replacement amount is positively correlated with coal metamorphic degree, while N₂ injection ratio is negatively correlated with coal metamorphic degree. In the same coal, CH₄ replacement amount is positively correlated with pressure, while N₂ injection ratio is negatively correlated with pressure.

To study the effect of wind velocity and discharge on gas transport after coal and gas outburst. An experimental device for gas migration during the outburst period was designed and built. The experimental results show that the gas migration in the pipeline during the outburst period is affected by the wind speed, and the oxygen concentration on the return air side decreases faster than that on the inlet air side, indicating that the gas migration to the return air side is faster after the outburst. The larger the outburst flow, the larger the migration range of the outburst gas in the shaft and the greater the degree of airflow reversal on the inlet side, and the influence on the inlet pressure decreases first and then increases. For the ventilation recovery stage, the oxygen concentration in the inlet air rises 1.5 times faster than that in the return air on average. At the same time, TF1M3D simulation software is used to analyze the gas outburst plan of the preset mine, and study the law of gas migration and spatial-temporal distribution in the mine after the outburst.

The adsorption activity of a carbon material based on lignin modified with iron salts and carbonized under the influence of microwave radiation in relation to 2,4-dichlorophenoxyacetic acid (2,4-D) from an aqueous medium was studied. The kinetic parameters of the adsorption process were determined. Based on the results obtained, the possibility of using the test material as an adsorbent of biologically active organic compounds was shown.

A comprehensive study of the chemical and group composition of organic and mineral fractions of brown coal from the Raichikhinskoe deposit was carried out. Chemical and technological parameters were determined and the textural characteristics of coal were studied. It was found that the mineral component of coal is clayey in nature and has a stable composition. The variability in the composition of the organic matter of coal indicates the facies instability of sedimentation conditions in the studied areas of coal accumulation.

The decrease of coke formation in the steam cracking of hydrocarbon raw materials was studied with the use of the following inhibitors: dimethyl disulfide (DMDS), dimethyl sulfide (DMS), and dimethyl sulfoxide (DMSO). The influence of various factors on coke formation has been established: the amount of inhibitor (0–300 ppm), process temperature (750–600°C) and the water vapor/raw material ratio (0–1 kg/kg). The kinetic parameters of the process of reducing coke formation have been calculated.

Gas hydrates have the potential for many industrial applications such as gas storage and transportation. However, the low rate of hydrate formation process is one of the main barriers to the industrialization of this technology. The effect of tetra n-butylammonium fluoride (TBAF) and sodium dodecyl sulfate (SDS) on the rate of methane uptake in the process of gas hydrate formation is investigated in this research. A stirred batch cell with an effective volume of 169 cm3 was employed to perform the experiments. The temperature of the cell was adjusted at 278.15 K at initial pressures of 6 and 8 MPa. The results of the experiments showed that the addition of 2 and 4 wt% TBAF increases the average rate of methane uptake within 50 min of the gas hydrate formation process. The utilization of SDS with a concentration of 400 ppm, remarkably, increases the rate of methane uptake, compared to pure water. Simultaneous utilization of TBAF and SDS showed a negative effect on the methane uptake, compared to the aqueous solution of SDS.