Solid Fuel Chemistry最新文献

A study was conducted to assess the concentrations of persistent organochlorine pollutants (POPs) in high-moor peats of the Primorsky and Mezensky districts of the Arkhangelsk oblast. Peat deposits located in the zone of potential influence of pollutants and outside it were analyzed. Based on the results of chromatographic determination, data on the concentrations of some organochlorine compounds in the studied peats, in particular, persistent toxic hexachlorobenzene (HCB), pentachlorophenol (PCP), pentachloroanisole (PCA), and chlorinated phenols and their derivatives, were obtained. Target POPs were detected in all analyzed peat samples with noticeable variability in their concentrations across the study areas HCB (0.4–3.2 ng/g), PCP (0.2–1.8 ng/g), and PCA (up to 0.4 ng/g). The CP content of the studied peats varied over a wider range from 1.2 to 571 ng/g. The identified quantities of POPs (HCB, CP, and PCA) were most likely due to the entry of pollutants by atmospheric transport from various sources in the territories of nearby regions and neighboring states. The influence of local pollution sources associated with thermal processes should also be taken into account.

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A sample of a catalytic system based on nickel and a carbon-containing material, microcellulose, was obtained using a hydrothermal synthesis method. A catalytic study of the synthesized system in the process of selective hydrogenation of carbon monoxide and carbon dioxide was carried out with calculation of the apparent activation energy. The sample was demonstrated to be highly active in the selective hydrogenation reactions of carbon oxides. A 100% conversion of carbon monoxide and carbon dioxide and selectivity for methane of 90 and 80%, respectively, were obtained.

The conveyance of coal in slurry form through pipelines has demonstrated its viability and efficacy, providing economic advantages, reliability and reduced environmental impact. As high-rank coal deposits are steadily depleting, researchers are interested in exploring ways to facilitate utilising low-rank coal to meet the global energy demand. However, the slurry prepared using low-rank coal exhibits high apparent viscosity and poor stability. In the present work, the rheological characteristics of Indian coal with an ash content of more than 50% are improved through the use of the commercial additive sodium dodecyl sulfate. The high ash coal sample’s physical, chemical, and morphological characteristics were assessed. The rheological attributes of the high ash coal slurry were investigated by altering the shear rate, solid loading, and additive concentration. The optimal sodium dodecyl sulfate proportion to obtain slurry with maximum stability and low apparent viscosity was found to be 0.5%. The observed rise in the absolute value of zeta potential from –37.82 to –52.19 mV signifies that suspension stabilization occurs via electrostatic repulsion. A statistical correlation for the prediction of slurry apparent viscosity was developed and proved to be promising and significant.

Determining the risk of spontaneous combustion of coal remains in the airspace is crucial to the safe production of mines. Therefore, to investigate the danger of spontaneous combustion in the airspace when the overlying rock layer is not sufficiently compacted, the 1304 working face of Hongyang no. 2 Mine was taken as the research object. The experimental device was developed to measure the oxygen consumption rate, and the negative exponential function model was used to analyze the change rule of the oxygen volume fraction of the coal samples. Combined with a large amount of measured data of the working face and the change of the wind speed of the inlet and return tunnel, a CFD model of the ground without subsidence of the bubbling medium of the mining airspace was established, and numerical simulation was carried out on the flow field of the working face’s airspace area by using FLUENT software to get the oxygen volume fraction distribution law of the airspace area distribution law. The results show that the continuous oxygen consumption rate of the coal sample is γ = 9.3381 × 10^–7 mol/(m³ s). Then, the oxygen volume fraction of choking (critical) under the actual temperature is 14.4%. The maximum range of the spontaneous combustion oxidation zone in the goaf is 25 to 176 m away from the working face. The work safety advancement rate is 1.86 m/d, and the actual advancement speed is 9.6 m/d, which also presents a lower risk of spontaneous combustion. The on-site test data matches well with the simulation results, which verifies the validity of the simulation and provides a basis for the prevention and control of spontaneous combustion of the coal left in the mining area to ensure the safe production of the mine.

The slow desorption rate of coal body gas is easy to cause coal and gas outburst accidents, the temperature has an important influence on the desorption process of gas, and increasing the temperature can significantly improve the gas desorption rate. Based on this law, inorganic phase-change energy storage materials with a phase change temperature of 58°C were selected to study the influence range of the phase change process of materials with different contents on the temperature of coal body by comparative experiments. At the same time, the effect of the change of temperature on the desorption amount and desorption rate of gas desorption within coal was obtained by applying the phase change material to the adsorption/desorption experimental system. It was found that after the addition of the phase change material, the gas-containing coal which had completed the desorption process restarted to desorb the gas, and the final stabilized desorption amount was 1.709 cm³/g with an increase of 0.185 cm³/g, accounting for 12.14% of the desorption amount under normal conditions, which indicates that the addition of phase change materials can improve the desorption rate of coal samples.

The influence of alkaline and acid pretreatments of Sibunit carbon support on the catalytic properties of Fe–Cr/С oxide systems was studied for the process of oxidative dehydrogenation of ethane with CO₂ in a temperature range of 650–750°C. It has been established that alkaline treatment promotes the active occurrence of the Boudoir–Bell reaction, while acid treatment slightly increases ethane conversion with greater carbonization of the catalyst surface.

In recent years, ethanol has emerged as a popular additive for biodiesel/diesel blends, to decrease the carbon footprint left by combustion products. Nanoparticles added with biodiesel/diesel have promoted greater ignition and combustion rate, lower ignition delay, and reduced exhaust emissions. This study evaluated the filter performance of prosopis juliflora biodiesel and bioethanol mixed with diesel with selected nano particles, namely graphene(G) and graphene oxide(GO) nanoparticles. Different nano additive proportions of 50, 100, 150, 200, 250, and 300 ppm were blended in diesel blends of BED20 (10% biodiesel + 10% ethanol + 80% diesel) and the filtration characteristics of these fuel blends were evaluated to determine the best nanoparticle mixture. Tamson filter blocking tendency (TFBT) apparatus was utilized to determine filter blocking tendency (FBT). The filtration performance was measured by following the ASTM standard (D2068-14) for initial pressure, fuel temperature and fuel flow rate. Results found that the FBT tends to rise with the addition of additive proportion. It was seen that FBT values of 200 ppm of grapheme (G) nanoparticles and 250 ppm graphene oxide (GO) were found to be 1.32 and 1.4 respectively which inline the acceptable range (1.41).

Air leakage between goaf and working face increases the risk of spontaneous combustion in goaf, posing a threat to production safety in the working face. The study uses CFD software to simulate the impact of wind speed and goaf depth on the distribution of air leakage, oxygen concentration, and carbon monoxide concentration. It was found that as wind speed increases, the air leakage plume and CO gas concentration move towards the return air side, and the air leakage speed at the working face boundary and tases with depth, and the range of CO distribution and the range of oxygen distribution on the intake side decrease. Based on this, a dynamic measurement method for air leakage is proposed. The error of wind resistance value comparison is within ±5%, indicating the feasibility of dynamic quantitative measurement of the air leakage flow field at the working face, which can improve the accuracy of air leakage measurement in the working face. Then the method was applied in the 509 working face of Ma Di Liang coal mine. The results show that the average air leakage volume in the goaf of the 509 working face is 152.19 m³/min, and the average air leakage velocity is 0.41 m/s.

The particle sizes of main mineral compounds in the structure of lignite were determined using physical methods (SAXS, TEM, and XRD analysis) and chemical processes of selective dissolution. It has been shown that calcium and magnesium compounds in the structure of lignite were present in the form of small nanoparticles with sizes of about 10 nm. Particles consisting of aluminum and iron compounds had larger sizes of about 20–35 nm. Silica-containing particles in the structure of lignite had sizes of 100 nm or greater.

The results of a study of rare-earth metals in dictyonema shales of the Paleozoic Baltic sedimentary basin are presented. In the territory of the studied Kaibolovo–Gostilitsy prospecting area, high up to potentially industrial rare-earth element (REE) contents were confirmed based on a large factual and analytical material. The average REE concentration was 289 g/t with maximums up to 724 g/t. REEs were found in dictyonema shales in various forms (mineral, organic, ionic, molecular, and colloidal). The occurrence of REEs in the mineral matter of dictyonema shales predominated. The fraction of heavy (and most valuable) lanthanides (15.6% on a total basis) in the test dictyonema shales was higher by a factor of 2 than that in ore deposits. This fact and the presence of large geological REE resources in the dictyonema shales of the Baltic region of Russia determine the need for their integrated development with other associated components.