Solid Fuel Chemistry最新文献

To investigate the influence of acidification duration on the pore structure and spontaneous combustion characteristics of anthracite, anthracite from the Yixin mining area was selected as the research subject. Hydrofluoric acid was employed for acidification treatments over different time intervals (3, 6, 9, 12 h). Techniques such as X-ray diffraction, temperature-programmed heating, thermogravimetry, and infrared spectroscopy were utilized. The alterations in the microcrystalline structure, gaseous products, thermo-dynamic characteristics, and microstructure of anthracite before and after different acidification durations were compared and analyzed. Moreover, the mechanism by which these changes affect the spontaneous combustion of coal was discussed. The results indicate that after acidification, the interlayer spacing of coal samples gradually increases, while the stacking height and the number of stacking layers generally decrease. As the acidification duration increases, the amount of gaseous products rises, the activation energy declines, and the combustion characteristics improve. Specifically, the activation energies of coal samples A-3, A-6, A-9, and A-12 have decreased by 4.26, 638.86, 222.38, and 249.23 kJ/mol, respectively. During the acidification process, the maximum change in the aliphatic structure of the tested coal sample occurs at 6 h. The content of oxygen-containing functional groups and hydrogen bonds is consistently higher than that in the raw coal. The research findings offer theoretical guidance for the prediction and prevention of spontaneous combustion of pickled coal.

To investigate the influence of moisture content on gas desorption behavior in coal, this study designed and utilized a high-temperature steam adsorption system to prepare coal samples with varying moisture contents. Gas desorption experiments were conducted under an adsorption equilibrium pressure of 1.5 MPa to explore the effect of moisture on desorption performance. The results indicate that the coal samples from Liyuan Coal Mine exhibit strong desorption capability in the initial stage, with approximately 90% of the total desorption amount released within the first 100 min. As the moisture content increases, the desorption capacity significantly declines. At the desorption equilibrium state, the gas desorption amount of the coal sample with a moisture content of M_ad = 0.37% was 19.11284  mL/g, which is approximately 2.5 times that of the coal sample with a moisture content of M_ad = 3.97%, whose desorption amount was 8.3995  mL/g. A mathematical model was developed to calculate the gas diffusion coefficients under different moisture conditions, and the diffusion characteristics were systematically analyzed. The results show that, at the same moisture content, the diffusion coefficient reaches a peak during the initial characteristic time segment (t₂), then gradually decreases over time. Across different moisture contents, the diffusion coefficient decreases linearly with increasing moisture. At high moisture levels, the suppression effect is more pronounced, with the diffusion coefficient reduced by up to an order of magnitude. At the characteristic time t₂, the diffusion coefficient decreased from 44.03 × 10^–4  to 25.12 × 10^–4 m²/s; at t₁, it decreased from 8.42 × 10^–4  to 1.53 × 10^–4 m²/s; and at t₀, it decreased from 2.50 × 10^–6 to 0.78 × 10^–6 m²/s. This is primarily because water molecules occupy pore spaces and frequently collide with gas molecules, shortening diffusion paths and reducing effective diffusion areas, thereby inhibiting gas diffusion. In conclusion, appropriately reducing moisture content in coal can improve gas desorption efficiency and diffusion performance, providing theoretical and technical support for efficient gas extraction.

The increasing accumulation of electronic waste (e-waste) presents both environmental and energy challenges, necessitating innovative strategies for resource recovery and sustainable fuel production. This study investigates the catalytic pyrolysis of e-waste plastics to produce pyrolysis oil (PPO) and evaluates its potential as an alternative to diesel fuel. The pyrolysis process demonstrated a high conversion efficiency of 99%, yielding 88.12% PPO, 11.23% non-condensable gases, and 0.645% solid residue, showcasing its effectiveness in extracting valuable fuel from e-waste plastics. The fuel properties of PPO, including density (1080–1070 kg/m³), calorific value (39 861–43 154 kJ/kg), flash point (35–50°C), and cetane number (50 for raw PPO), were analyzed and compared with diesel. Fourier Transform Infrared Spectroscopy (FTIR) confirmed the presence of alkanes, alkenes, and oxygenated compounds, influencing fuel behavior. While PPO exhibited higher energy content, challenges such as lower cetane number, higher sulfur content (0.35%), and low flash points necessitate further refinement for broader diesel engine applications. To evaluate its real-world performance, PPO-diesel blends (25 to 100%) were tested in a four-cylinder turbocharged diesel engine under varying loads. Combustion analysis revealed extended ignition delays and higher peak pressures for blends with increased PPOcontent due to its higher aromatic concentration. Heat release rates (HRR) were significantly elevated, enhancing fuel-air mixing but causing combustion instability at low loads. At full engine load (100%), PPO exhibited a delayed but stable combustion process, achieving a brake thermal efficiency (BTE) of 34%, close to diesel’s 38% efficiency. However, at low engine loads, blends above 90% PPO exhibited incomplete combustion and operational inefficiencies. Emission analysis indicated a significant increase in NOx emissions with rising PPO content due to higher in-cylinder temperatures and prolonged premixed combustion phases. Additionally, carbon monoxide (CO) and unburned hydrocarbons (UHC) emissions were higher at low engine loads, while carbon dioxide (CO₂) emissions increased linearly due to PPO higher carbon-to-hydrogen ratio. Despite higher NOx emissions, PPO blends showed reduced particulate matter (PM) emissions due to lower soot formation. Despite these challenges, PPO blends containing 60–70% PPO at 80–90% engine loads demonstrated optimal performance, making them suitable for selective applications. Further research should focus on cetane number enhancement, desulfurization techniques, and fuel injection optimization to improve low-load stability and emissions control. This study highlights the potential of e-waste plastics as a renewable energy source, contributing to sustainable waste management, circular economy initiatives, and energy security while reducing reliance on fossil fuels.

In order to more accurately describe the change process of air flow and gas in the ventilation network system during the period of mine reverse ventilation, the asynchronous reverse wind problem of multiple wind Wells in the mine was studied by using TF1M3D simulation. The FDt(k) of all the air Wells is combined into a numerical code DF according to a certain algorithm to judge the working state of the fan of multiple air Wells,three possible working states of the ventilator, including shutdown, non-operation, single-machine operation and dual-machine operation, are defined, and corresponding codes representing these three states are given as the basis for judging whether the working state of the ventilator in TF1M3D is updated.Three possible working states of the ventilator, including shutdown, non-operation, single-machine operation and dual-machine operation, are defined, and corresponding codes representing these three states are given as the basis for judging whether the working state of the ventilator in TF1M3D is updated. Combined with the field example of the eighth mine in Hebi mining area, the simulation analysis is carried out by using TF1M3D simulation software. The reverse ventilation starts, the fan stops, and in a short pause, the mine relies on natural wind pressure ventilation, the airflow velocity is low, the air volume is small, and the gas accumulation occurs for a short time. Then, with the change of ventilation direction of the fan, the air flow changes accordingly. TF1M3D gives the corresponding changes of ventilation and working conditions. At the same time, the gas migration state changes, and the gas peak overlimit phenomenon appears on the working face. With the advance of the reverse ventilation work, the concentration of migrating gas showed a gradual decrease. The simulation of asynchronous reverse ventilation in multiple air shafts of mine accurately describes the corresponding changes of gas components in the mine system when the wind is stopped in the reverse ventilation operation, and improves the calculation accuracy of ventilation simulation during the disaster period.

In order to meet the air volume demand of the south wing of Menkeqing mine during the successive mining period and ensure the safe and efficient production of the mine. On the basis of air volume survey, analysis of main ventilator performance parameters and measurement of mine ventilation resistance in the whole mine, the mine ventilation system was simulated and analyzed by using TF1M3D, a mine ventilation physical simulation platform, and the mine ventilation system was simulated and predicted in the difficult mining period of panel working in the south wing, and the ventilation system optimization and transformation schemes were proposed to meet the mining period of panel working in the south wing. The results showed that the air supply capacity of the main ventilator of the mine had reached the limit at this stage, and the zoned ventilation of the south wing air shaft and 1# air shaft can meet the air supply demand of each working face in the boundary area of the south wing of Menkeqing mine.

In this study, biochar was prepared by slow pyrolysis of palm kernel seeds at 350°C for 2 h. Characterization of the raw material (palm kernel seeds) and biochar was carried out by elemental analysis, FTIR, BET and SEM analyses. The results showed that the pyrolysis process transformed the palm kernel seeds, resulting in an increase in the carbon content and decrease in the hydrogen and oxygen contents of the biochar. The transformation was also obvious in the FTIR spectra, with the biochar showing peaks with less intensity than the raw material. The SEM images further confirmed the changes as the oily morphology of the raw material was not observed in the biochar, while the BET analysis showed an increase in the surface area from 3.03 m²/g in the raw material to 45.15 m²/g in the biochar. The results of the solid fuel properties showed that the higher heating value (HHV) increased from 24.04 MJ/kg in the raw material to 27.15 MJ/kg in the biochar, while the energy densification ratio was 1.13 in the biochar. The energy properties of the prepared biochar are consistent with previous studies, indicating that the biochar has the potential for development as solid fuel. Consequently, pyrolysis could be an attractive technique for converting this waste material into high value-added product.

Liquid nitrogen, characterized by its extremely low temperature and high vaporization expansion ratio, plays a crucial role in fire prevention and suppression in mining goafs. However, the seepage characteristics of liquid nitrogen in loose media have not been sufficiently studied. To improve the fire prevention and extinguishing efficiency of liquid nitrogen, it is essential to gain a deeper understanding of its seepage behavior in loose media. To this end, an experimental setup for liquid nitrogen seepage was designed to quantitatively study its horizontal seepage behavior in loose media. By analyzing the changes in the temperature and pressure fields during the seepage process, the effects of angle of inclination and particle size on the seepage process were explored. Based on the Forchheimer equation, a mathematical model for the horizontal seepage of liquid nitrogen in loose media was established. The results showed that when the particle size increased from 1–2 to 3–4 cm, the permeability increased by 4.2 to 4.5 times, and the non-Darcy factor decreased by 2.8 to 4.3 times. Under the same particle size conditions, as the angle of inclination increased from 0° to 13°, the permeability increased by 1.97 to 2.06 times, and the non-Darcy factor decreased by 1.37 to 2.11 times. This study provides a theoretical basis for the application of liquid nitrogen in fire prevention and extinguishing in mine goafs.

This paper presents the results of a comprehensive study of four types of spent coffee grounds (SCG) obtained using different coffee brewing methods. Thermogravimetric analysis (TGA) was performed to study the thermal behavior of the samples, and elemental and technical analysis was performed to assess their calorific value. The main gaseous components released during the pyrolysis of the samples were identified using Fourier transform infrared (FTIR) spectrometry. The data obtained allowed us to characterize the composition and properties of SCG as a potential raw material for energy processing.

The wettability of anthracite is crucial for effective dust control in industrial dust removal processes. This study investigates the key effects of surfactants on the wettability of anthracite by compounding anionic surfactants, specifically fatty acid methyl ester ethoxylate sulfonate (FMES), with nonionic surfactants, such as coconut oil fatty acid diethanolamide (CDEA). The research analyzes the surface chemical properties and agglomeration behavior of the treated anthracite. The processed coal samples were characterized using various techniques, including infrared spectroscopy (FTIR), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and X-ray photoelectron spectroscopy (XPS). The experimental results indicate that the anionic-nonionic composite surfactant exhibits a significant synergistic effect in enhancing the wettability of anthracite coal. SEM and EDS analyses revealed that the coal samples treated with surfactants formed liquid bridges through hydrogen bonding, which facilitated the rapid agglomeration of fine particles. The agglomeration effect of the composite surfactant system was found to be superior to that of a single surfactant. XPS testing demonstrated a reduction in carbon content, which decreased to 79.43%, while oxygen content increased to 18.15% due to the treatment with the compound surfactant. Furthermore, FTIR analysis indicated that the complex surfactant system significantly increased the hydroxyl content of the coal samples, thereby enhancing the surface adsorption effect. In summary, the synergistic effect generated by the anionic-nonionic complex surfactants can markedly improve the hydrophilicity of anthracite, providing an effective approach for optimizing its wettability.

This paper presents the results of a study of the energy potential of nondesign fuels using pyrolytic gas chromatography with mass spectrometric detection (GC–MS). The test materials were samples of sewage sludge (SWS) and hydrolytic lignin (HL) collected in the Arkhangelsk oblast. The initial samples were characterized by their key physicochemical parameters. Attention was paid to an analysis of the chromatograms of pyrolysis products obtained under various temperature conditions. Key temperature ranges of maximum heat release were determined for each type of feedstock. For sewage sludge, the highest yield of high-calorific components determining peak heat release was observed in a range of 400–500°C. For hydrolytic lignin, a similar peak energy release was recorded at a significantly lower temperature of approximately 300°C due to its specific composition. A detailed identification and qualitative assessment of the main components in the pyrolysis products of both fuels was performed using GC–MS and HPLC analysis. The results of this work allowed us to evaluate the suitability of SWS and HL as feedstock for the subsequent energy utilization.