Experimental analysis on post-explosion residues for evaluating coal dust explosion severity and flame propagation behaviors

To study the explosion characteristics of coal dust samples with different metamorphism, 19 coal samples including anthracite, bituminous coal, lignite were selected, explosion pressure distribution and flame propagation velocity were studied in an explosion pipeline with an outer diameter of 108 mm and an inner diameter of 88 mm. Coal dust particles were injected into the pipeline by eight dust nozzles controlled by solenoid valves. The explosion pressure and flame propagation profiles were obtained by PCB piezoelectric sensors and photoelectric sensors. The experimental results suggested that the explosion pressure profiles of different coal samples are all present a first increasing and then decreasing trend. However, there is a drop point at 0.875 m from the ignition end. The flame propagation velocity increases first and reaches the maximum at 0.625 m from the ignition end, and then the propagation velocity begins to decrease until the end of the pipeline, while there exist a slight enhancement at 1.105 m from the ignition end. Furthermore, the coal samples with different coal ranks have different explosion severity, coal samples with lower moisture content, and relatively higher volatile matter present a better deflagration property and cause a higher explosion severity.

Dust explosions are phenomena in which a flame propagates through a dust cloud in air with increasingly subdivided combustible solids. These events are common risks in the coal, metallurgy, chemicals, wood, food processing, explosives and other industries. In order to study the propagation characteristics of coal dust explosion flame, box graph and two-factor variance analysis were used to explore the influence of coal dust metamorphism degree and coal dust particle size on the propagation characteristics of coal dust explosion flame in this paper. Specifically, a certain coal sample was selected and the coal dust explosive identification test was carried out through the modified MeB-III intelligent coal dust explosive identification instrument. By observing box graph, the different influence rules of metamorphism and particle size on the length of coal dust explosion flame were analyzed qualitatively. The results show that, the main factor affecting the length of coal dust explosion flame is the size of coal dust.

• Flame propagation of iron–methane–air mixtures was investigated experimentally. • Flame speed decreased near stoichiometric methane due to iron particle heat loss. • Under lean methane, iron oxidation supplied extra heat and enhanced propagation. • XRD showed Fe 2 O 3 formation under lean and FeO/Fe 3 O 4 under stoichiometric condition of methane-air. • Results clarify gas–solid interactions governing hybrid flame propagation. Recently, interest in metal powders such as iron has grown due to their high energy density and carbon-free combustion, making them promising sustainable energy carriers. However, their heterogeneous combustion and low burning velocity limit standalone use, and hybridization with gaseous fuels is often required to support ignition and stable propagation. Nevertheless, the interaction between gas and solid phases during ignition and flame propagation remains insufficiently understood. In this study, the flame propagation behavior of iron–methane–air hybrid mixtures was experimentally investigated under various methane equivalence ratios. Combustion tests were performed in a 4.2 L closed chamber equipped with a schlieren visualization system and a high-speed camera. Spherical iron powders were dispersed into methane–air mixtures and ignited by spark discharge, and the resulting flame radius and propagation speed were measured and compared with those of pure methane–air flames. Results show that near the stoichiometric methane condition, the flame propagation speed of hybrid mixtures decreased to roughly half that of methane–air flames, as the heat losses outweighed the heat released from iron combustion. In contrast, under lean methane conditions, the propagation speed exceeded that of methane–air flames, indicating additional heat release and volumetric expansion from iron combustion.

Soil amendment with coal dust in different proportions may play an important role in the soil matrix. Particles spread on land in the mining areas, during transportation on road sides, and coal dust during pulverization and storage (coal stack yard). Coal dust particles, therefore, necessitate the need for knowing the impact/effect on the soil matrix and its ultimate effect on the fertility status and productivity of the soil. Amendment through soil conditioning with the use of micro-organisms within the soil matrix using natural biological activity may be an important factor in the soil matrix on the fertility status and productivity of the soil. Moreover, it will be a viable treatment option for the remediation of coal particle-contaminated soils or the use of coal-dust-amended soil for the reclamation of waste land in a cost-effective manner with a minimum threat to the soil. The mixed microbial consortium present in the soil was used to accelerate the conditioning of the soil. This culture of microbial consortia, along with nutrients, acts in various in situ conditions of coal-contaminated soil to help remove heavy metals present in coal, as well as different organic compounds in the soil, and serves as a manure for plant growth. In the present study, pot experiments were conducted for the germination of different plants by amending coal dust particles with soil. It was observed that the soil remediation with coal dust particles is extremely useful tool for improving the quality of poor wasteland soil without the use of fertilizer because of the conversion of hydrocarbons present in coal dust into manure with the help of soil micro flora which helps for the growth of plants. The soil quality was found to be improved after remediation with respect to cation exchange capacity (CEC) and organic matter content. There was no degradation found in soil quality after germination and frequent use under control conditions will help for the next crop growth. The present study reflects that the coal dust particles amended soil or wasteland soil not only helps to increase the productivity of soil but also the ultimate use of the coal dust particles in soil also creates to cleanup existing soil contamination and help to restore soil quality in a cost effective manner.

Investigation on coal dust prevention by biomimetic mineralized dust suppressant with polyacrylic acid modifier

Experimental study on pressure wave-induced explosion of different types of deposited coal dust

Effects of dust concentration, particle size, and crude oil concentration on the explosion characteristics of oil-immersed coal dust

Experimental study on the suppression of coal dust explosion by silica aerogel

BackgroundCoal dust particles (CDP), an inevitable by-product of coal mining for the environment, mainly causes coal workers’ pneumoconiosis (CWP). Long-term exposure to coal dust leads to a complex alternation of biological processes during regeneration and repair in the healing lung. However, the cellular and complete molecular changes associated with pulmonary homeostasis caused by respiratory coal dust particles remain unclear.MethodsThis study mainly investigated the pulmonary toxicity of respirable-sized CDP in mice using unbiased single-cell RNA sequencing. CDP (< 5 μm) collected from the coal mine was analyzed by Scanning Electron Microscope (SEM) and Mass Spectrometer. In addition, western blotting, Elisa, QPCR was used to detect gene expression at mRNA or protein levels. Pathological analysis including HE staining, Masson staining, immunohistochemistry, and immunofluorescence staining were performed to characterize the structure and functional alternation in the pneumoconiosis mouse and verify the reliability of single-cell sequencing results.ResultsSEM image and Mass Spectrometer analysis showed that coal dust particles generated during coal mine production have been crushed and screened with a diameter of less than 5 µm and contained less than 10% silica. Alveolar structure and pulmonary microenvironment were destroyed, inflammatory and death (apoptosis, autophagy, and necrosis) pathways were activated, leading to pneumoconiosis in post 9 months coal dust stimulation. A distinct abnormally increased alveolar type 2 epithelial cell (AT2) were classified with a highly active state but reduced the antimicrobial-related protein expression of LYZ and Chia1 after CDP exposure. Beclin1, LC3B, LAMP2, TGF-ß, and MLPH were up-regulated induced by CDP, promoting autophagy and pulmonary fibrosis. A new subset of macrophages with M2-type polarization double expressed MLPH + /CD206 + was found in mice having pneumoconiosis but markedly decreased after the Vitamin D treatment. Activated MLPH + /CD206 + M2 macrophages secreted TGF-β1 and are sensitive to Vitamin D treatment.ConclusionsThis is the first study to reconstruct the pathologic progression and transcriptome pattern of coal pneumoconiosis in mice. Coal dust had obvious toxic effects on lung epithelial cells and macrophages and eventually induced pulmonary fibrosis. CDP-induced M2-type macrophages could be inhibited by VD, which may be related to the alleviation of the pulmonary fibrosis process.

Experimental and numerical study on formation mechanism of premixed hydrogen-air squish flame in wall constrained environment

Effects of radiative loss on premixed planar flame propagation

This study focused on the inhibitory effects of dry water materials on the coal dust explosion characteristics in the coal hydrogenation process by adopting a 20 l explosion device. Additionally, the inhibitory effects of dry water material were compared with SiO2 and NH4H2PO4. The results showed that 10 wt% dry water materials notably delay the arrival time of the peak explosion pressure, significantly inhibiting the initial energy release during the explosion, resulting in the maximum rate of explosion pressure rise decreasing by 61.96%. As the dry water material adds up to 50 wt%, the maximum explosion pressure significantly reduced to 0.258 MPa and delayed by 431.1 ms. The flame propagation velocity reduced from 2.19 to 0.33 m s-1. In addition, dry water material, with its excellent heat absorption and adsorption and isolation properties, had more significant inhibitory effects than SiO2 and NH4H2PO4.

Flame-propagation behavior and a dynamic model for the thermal-radiation effects in coal-dust explosions

Application of modified eddy dissipation concept with large eddy simulation for numerical investigation of internal combustion engines

In recent years, the export volumes of Russian coal to the Asia-Pacific countries have been continuously growing. Coal dust is among of the strongest air pollutants. The article describes the study of airborne particulate matter in large transport hubs of the Primorsky Krai (Russian Far East): Nakhodka city and Posyet urban-type settlement using the method of measuring the mass and quantitative concentrations of particulate matter. It is shown that the air of these areas is polluted with particulate matter with diameter below 10 microns (PM10). The absolute dominance of 0.3 μm and 0.5 μm particles was revealed in the air of both areas. According to the Russian hygienic standard, the maximum permissible concentrations of PM were exceeded only at several sampling points. However, when compared to some international standards, the content of PM exceeded maximum permissible values at 42% of sampling points in Nakhodka city and at 43% of sampling points in Posyet settlement. It is advisable to install systems for continuous environmental monitoring of air pollution with coal dust particles near coal terminals.