Solid Fuel Chemistry最新文献

The results of thermogravimetric analysis of polyacrylonitrile fiber samples after the process of oxidative thermal stabilization in air are presented. Based on a study of a commercial sample of PAN fiber, the dependences of the weight loss of the starting material on the final temperature of oxidative thermal stabilization and the heating rate are presented. A machine learning model was built using the results of the experiments in order to predict the dependence of the weight loss of the starting material on the technological parameters of the oxidative thermal stabilization process.

Biomass energy is increasingly recognized as a promising alternative to conventional energy sources, offering potential sustainability and environmental benefits. Miscanthus has emerged as a standout candidate within energy crops, with M. lutarioriparius particularly noteworthy. This research delves into the intricate relationship between the timing of harvest and the resulting biomass yield and combustion quality of M. lutarioriparius in the unique coastal wetlands surrounding China’s Dongting Lake. An extensive field experiment was meticulously executed to explore these dynamics, yielding valuable insights comprehensively. (1) First and foremost, the study unearthed a paradoxical trend: delaying the harvest of M. lutarioriparius led to an increase in the stem-to-leaf ratio. However, this apparent benefit was counterbalanced by a noticeable decrease in overall biomass yield, primarily driven by the shedding of leaves as harvest was delayed. Delving into the intricacies of biomass composition, delayed harvests had a significant impact. (2) Specifically, they resulted in marked reductions in water content, ash content, and hemicellulose levels within M. lutarioriparius biomass. The correlation analysis further underscored the importance of cellulose and lignin, with a strong positive relationship between their content and calorific value, while hemicellulose exhibited a highly significant negative correlation. (3) Additionally, the study ventured into the realm of mineral elements within the biomass. Delayed harvesting precipitated a substantial reduction in their content, with notable fluctuations observed in potassium (K) and calcium (Ca) levels. Furthermore, ash content exhibited positive correlations with potassium (K) and silicon (Si) contents, shedding light on the intricate interplay of mineral elements. A notable silver lining emerged despite the reduced biomass yield associated with delayed harvesting. In a holistic assessment, the optimal window for harvesting M. lutarioriparius to maximize fuel quality was pinpointed to span from late November to the conclusion of January in the subsequent year. This nuanced understanding of harvesting timing can play a pivotal role in optimizing the utilization of M. lutarioriparius as a valuable energy resource.

The shallow-buried close-distance coal seam group has the characteristics of large mining height, shallow burial depth and small interlayer spacing. After coal seam mining, a penetrating air leakage channel is formed on the surface and underground, which is the main cause of low oxygen in the return air corner. This paper, PFC simulation is used to study the caving law of overburden rock and the evolution process of air leakage channel during the mining process of working face. The results show that the low oxygen gas in the goaf of 12 # coal seam mainly migrates to the return corner of the lower 221014 working face. The main medium facilitating this is the interconnected inter-coal seam air leakage channel, and the primary driving force is the substantial and rapid decrease in surface gas pressure, leading to a significant gas pressure difference between the return airway corner and the goaf of the 12 # coal seam. Aiming at the low oxygen phenomenon in the return air corner. The governance measures involving even-pressure ventilation technology were proposed. Theoretical calculations determined a safe gas pressure adjustment range for the return airway corner to be between 88.328 and 88.549 Pa. The pressure equalizing ventilation technology effectively controls the pressure difference between the goaf of 12 # coal seam and 22104 working face, and reduces the air leakage. Finally, the oxygen concentration in the return air corner is increased to prevent excessive fresh air from pouring into the goaf.

The article presents the results of experimental studies on the production of fuel briquettes from carbon-containing technogenic raw materials with a certain energy potential, flotation concentrate of coal enrichment sludge and wood and plant residues with binders. The technical characteristics of fuel briquettes of experimental batches are presented. The applicability of the selected binders for obtaining high-quality fuel briquettes was demonstrated. Aspects of the formation of the structure and properties of fuel briquettes are considered.

This study investigates the mineralogical composition and elemental distribution of oil shale and its ash from Sultani deposits using X-ray diffraction (XRD) and X-ray fluorescence (XRF) analyses, respectively. The XRD analysis of the oil shale samples confirmed the presence of calcite and quartz as primary mineral phases. However, XRD analysis of the oil shale ash revealed the presence of gypsum in addition to calcite and quartz, suggesting thermal decomposition and mineral transformation during combustion. The Sequential solvent extraction procedure provides insights into the distribution of heavy metals within Sultani oil shale ash. Specifically, the water-soluble fraction (stage 1) exhibited the presence of readily mobile metals, notably sulfur and silicon. In the exchangeable fraction (stage 2), metals were identified as bound to particle surfaces and acid-soluble salts, with notable concentrations of calcium, iron, and other trace elements observed. Manganese oxide and organically bound metals emerged in the easily reduced fraction (stage 3), while metals associated with oxidizable minerals were predominant in the oxidizable fraction (stage 4). Additionally, the non-mobile fraction (stage 5) entrapped metals within mineral crystal lattices, indicating limited mobility.

This work aimed to investigate the removal of sulfur compounds from light kerosene using activated carbon (AC) that was treated with alkali agents (KOH and NaOH) to enhance its adsorption properties. The physicochemical properties of the as-received AC and AC/alkali agents were characterized using Fourier transform infrared spectroscopy (FTIR). To evaluate the effectiveness of the surface modifications on the adsorbents, various operating conditions were examined. The agitation speed varied between 200, 300, and 400 rpm, while the contact time ranged from 15 to 35 minutes. Additionally, different percentages of KOH (5, 10, 15%) and NaOH (5, 10, 15%) were used to assess their influence on the removal efficiency of sulfur compounds. Based on the given information, it appears that the treatment of activated carbon (AC) with alkali agents, specifically KOH and NaOH, has resulted in an increase in the specific surface areas of the AC. This increase in surface area could potentially enhance the adsorption capabilities of the AC. The results showed that AC/KOH achieved a sulfur removal efficiency of 69%, while AC/NaOH demonstrated a higher efficiency of 84%. The highest sulfur removal efficiency was achieved under specific conditions: a NaOH concentration of 4 M, agitation speed of 400 rpm, and contact time of 35 minutes. Overall, the treatment of activated carbon with alkali agents, particularly NaOH, led to increased specific surface areas and the presence of hydroxyl functional groups. The surface area of AC-treatment will be increased because the functional group formation new location in AC-support and increased the porosity, therefore the surface area will increase. The resulting composites, AC/KOH and AC/NaOH, demonstrated enhanced sulfur removal efficiency compared to other composites, with AC/NaOH showing the highest performance.

In order to determine the chemical composition of peat, the individual composition of lowland peat from the Bolshoi Kaltus 1 deposit (Arkhangelsk oblast) was characterized. The chemical composition of pyrolysis products of the test peat sample was determined using pyrolytic gas chromatography (GC–MS). Chromatograms of peat were obtained at temperatures from 200 to 600°C. The paper presents the results of a study of the peat pyrolysis process. The properties of products obtained on its basis by thermochemical treatment were described.

The composition, structure, and morphology of dehydrated sewage sludge, a by-product of pulp and paper production, were studied. The thermal characteristics of sewage sludge were investigated. An elemental analysis of the sewage sludge was carried out, the results of which revealed a large number of noncombustible elements (5.5%), including heavy metals (vanadium, chromium, nickel, zinc, and strontium), compared to other types of fuel. Thermogravimetric studies on the thermal decomposition of dehydrated sediment were carried out. The thermogravimetric and differential thermogravimetric curves were described, and the temperature ranges of drying, release of volatile substances, and combustion of coke residue were determined. Microscope photos showed that the particle size of the sediment varied from 0.5 and 350 nm, and amorphous flakes and crystalline inclusions were the main elements of its structure.

Exploring the optimal experimental conditions and mechanism of a novel functionalized ionic liquid 1-ethyl-3-methylimidazolium bromide ([EMIM][Br]) for enhancing the wettability of coal powder is of great significance for reducing the harm of coal dust. This study determined the critical micelle concentration of [EMIM][Br] aqueous solution through ultraviolet(UV) absorption spectroscopy, and analyzed the mechanism of the influence of [EMIM][Br] aqueous solution on the wettability of coal using characterization methods such as contact angle, scanning electron microscope(SEM), automated surface area and porosity analyzer(BET), and fourier transform infrared spectroscopy(FTIR). The results showed that the critical micelle concentration of [EMIM][Br] aqueous solution was 0.005 mol/L, and the optimal experimental conditions were reaction temperature of 40°C, soaking time of 8 hours, and ratio of 1 g to 20 ml. After the action of [EMIM][Br] aqueous solution, the coal dust stomatal layer zone was developed, wedge-shaped stomata and sheet-filled cracks appeared, and the number of mesopores was increased. The content of hydrophilic functional groups such as C–O, carboxyl(–COOH), hydroxyl ether hydrogen bonds(OH…O), and hydroxyl self-consolidating hydrogen bonds(OH…OH) in the pulverized coal was increased, and the content of hydrophobic functional groups such as aryl hydrocarbons –CH₃ and–CH₂ was decreased, which improved the wettability of the pulverized coal.

To investigate combustion thermodynamics and kinetics for different coal rank, TG-DSC test was conducted on long-flame coal (LFC), gas-fed coal (GFC), and coke coal (CC) under different heating rates. Based on the DSC curve, the combustion process of coal can be divided into five stages: dehydration and desorption stage, chemical adsorption stage, transition stage, combustion stage, and burnout stage. With the increase in heating rate, the combustion characteristic parameters and the exothermic quantity show an upward trend. Under the consistent condition of the heating rate, the coal rank is positively correlated with its characteristic temperature, and negatively correlated with the maximum exothermic quantity. The kinetics experimental results show that the differential method exhibited higher fitting coefficients compared to the integral method, indicating its greater reliability in calculating results. Moreover, the activation energy increased with the increase of the coal rank under the same heating rate. CC has the highest activation energy, followed by GFC and LFC. These findings provide data support for the combustion law of similar coal types.