Increase In Dust Concentration Research Articles

Microbiological assessment of bioaerosols in the residential areas of Dhaka City, Bangladesh

This study looked at particulate matter (PM10) in terms of its microbiological features and how bacterial populations are related to PM10. It also tested the antibiotic resistance of different types of microbes that live in PM10. We conducted the study in six different locations (Badda, Chittagong Road, Basabo, Jurain, Mirpur, and Gulshan) of Dhaka city, taking into account residential and commercially important areas, traffic congestion, and infrastructure development. The microbiological study revealed that Bacillus spp. and Staphylococcus spp. were primarily present in PM10. The study also revealed that the total bacterial count (46585±1226.8 CFU/m3) of the Badda zone is higher than in another area. Similar findings were also observed in the case of Bacillus spp. (15625±5729 CFU/m3), Staphylococcus spp. (18518±5730 CFU/m3), and total fungal count (726852± 98209 CFU/m3). Moreover, a positive correlation was observed among Bacillus spp. and Staphylococcus spp. vs. mean PM10 concentration, which implies that airborne microbes in Dhaka city are likely to propagate with the increase of dust concentration. The antibiotic sensitivity assay of Bacillus spp. and Staphylococcus spp. revealed that all the Bacillus spp. (n=16) and Staphylococcus spp. (n=3) were resistant to Ceftazidime (30 µg), Oxacillin (1 µg) and Cefixime (5 µg). So, the research findings highlighted the increased levels of Bacillus spp. and Staphylococcus spp. than the international standard in PM10 of Dhaka city, suggesting potential health risks and indicating antibiotic resistance among these bacterial strains.

Spatial and temporal distribution characteristics of dust concentration based on satellite in mining area.

The spatial and temporal distribution patterns of dust concentration in the Pingshuo mining area and urban area were analyzed utilizing satellite data. The results indicate that the correlation coefficients of the average PM2.5 and PM10 concentration retrieved by satellite in Shuozhou City are 0.88 and 0.63, respectively, and the satellite inversion data demonstrate high reliability. The spatial distribution of dust concentration in the Pingshuo Mine area is elevated during winter and spring, with significant dust accumulation in winter. The pollution phenomenon in the Pingshuo mining area was pronounced from January to March, and the air quality deteriorated significantly. The correlation analysis of dust concentration between the city and the mining area reveals a marked spatial discontinuity at the boundary between the city and the mining area, indicating that the mining area is not the primary cause of the increase of dust concentration in the urban area, and changes in dust concentration within the mining area exert no significant impact on the urban area. The research results possess significant implications for dust control in both the mining and urban areas.

Study on the deposition rates of inhaled dust in respiratory tract by anchor excavation driver during coal mining

The external flow field of roadheader in Daliuta Coal Mine is numerically simulated, and breathing process of drivers is experimented in this paper. The airflow field of the whole tunnel is divided into three parts. The wind speed in the breathing area is determined to be 1.8 m/s. The relationship between dust concentration and time in respiration area is y = -0.0357x2 + 8.5541x-1.2298. The condition concentration of dust capture test is 81–508 mg/m3. The experimental results show that the D90 and D50 of environmental and bionic throat dust particles decrease with the increase of dust concentration. The increase of environmental dust concentration has a greater impact on dust with particle size larger than 6.5 μm. Dust concentration (ppm) inhaled by the driver = 0.057* Dust concentration in the environment (mg/m3). This study is expected to provide theoretical support for the prevention and control of dust occupational hazards.

Investigating the Occurrence of Dust Storms and its Zoning Using GIS During 2018-2021: A Case Study in Ahvaz, Iran

Background: A dust storm is a critical environmental issue and natural hazard in arid and semiarid regions worldwide. Particulate matters including PM10 and PM2.5 are of the primary air pollutants, which can adversely affect human health. This research aimed to determine the fine dust concentration spatiotemporally and estimate the suspended particulate matter (PM10 and PM2.5) during 2018-2021 in Ahvaz. Methods: An analytical- descriptive method and the data from synoptic weather stations in the studied area were used in this study. The zoning of dust was done using the kriging method by ArcGIS software. Results: The results indicated that the year 2021 experienced the highest frequency of dusty days, with 54 occurrences, while the year 2019 exhibited the lowest frequency, with only 28 dusty days. Notably, Ahvaz city recorded the highest dust concentration in 2020, reaching an average of 4667 mg/m3 . Based on the findings of PM concentration over the four-year period, it is evident that 2021 recorded the highest PM10 concentration (326.14 mg/m3 ), while 2020 exhibited the highest PM2.5 concentration (148.26 mg/m3 ). Conclusion: The results revealed that there was an increase in dust concentration in the east and north. This is probably attributed to the proximity to dust centers.

Pressure and Flame Propagation Characteristics of Suspended Coal Dust Explosions Induced by Gas Explosions.

In order to explore the pressure and flame propagation characteristics of gas-coal dust composite explosions, a semiclosed pipeline explosion test platform was built. The shock wave overpressure and explosion flame propagation law of different concentrations of suspended coal dust participating in gas explosions were studied in depth through experiments, and the coal dust motion law was simulated and analyzed based on Fluent software. The experimental results show that the peak pressure of gas-coal dust composite explosion is significantly higher than that of single-phase gas explosion, and the pressure peak increase ratio at the pipeline outlet is the highest; as the suspended coal dust concentration increases, the pressure rise rate at point 3 gradually decreases. Under the condition of 600 g/m3 coal dust participating in the explosion, the explosion pressure increase speed reduction ratio is 25.65%, the pressure wave secondary peak decreases, and the fluctuation frequency increases. When the explosion flame front passes through the suspended coal dust area, the flame shape changes from 'v' shape to 'finger' shape and propagates forward. The gas-coal dust composite explosion flame propagation speed shows a secondary acceleration phenomenon, after the flame front passes through the coal dust suspension area. As the coal dust concentration increases, the explosion core area moves away from the flame front. The coal dust cloud moves to the right, showing a concave rectangle; the larger the coal dust concentration, the smaller the moving speed. The experimental results and analysis provide an experimental basis for further exploring the mechanism and dynamic mechanism of gas-coal dust coupling explosion.

Insight into energy release characteristics of TiH2 dust explosion through ignition experiments and molecular dynamic simulations

TiH2 is an efficient hydrogen storage material with high energy density and relatively stable chemical quality, which is commonly used in metal sponge production, hydrogen storage, battery technology, rocket propellants, etc. In this study, TiH2 dust explosion is systematically investigated by integrating ignition experiments with reactive force field molecular dynamics simulation. Findings show that when the TiH2 dust concentration is 750 g·m−3, both the explosion pressure and explosion pressure rise rate reach their maximum values under airtight and venting conditions. There are three stages in the whole combustion process: the combustion development stage, the stable combustion stage, and the decay stage. The flame length (L) and flame propagation velocity (v) grow with the increase of dust concentration. TiH2 dust explosion with different concentrations in macroscopic tests is approximated by simulating the combustion behaviors of the TiH2 system with different densities. The combustion reaction rate of TiH2 grows with an increase in system density, and the simulation results are consistent with experimental findings.

Prevention and suppression of coal dust explosion in underground coal mines: Role of rock dust type, particle size, proportion, concentration, and thermal properties

Rock dust inertant is commonly used for prevention and suppression of coal dust explosion in underground coal mines. The effects of rock dust type, proportion, particle size, thermal conductivity, and specific heat capacity on minimum ignition temperature (MIT) of coal-rock dust mixtures and intensity of explosion propagation under different experimental conditions were examined using Godbert-Greenwald furnace integrated with a high-speed camera. MIT of coal-rock dust mixtures significantly increased with increase in rock dust proportion. With decrease in particle size from < 850 to < 75 µm, the mean MIT increased from 616 to 657 °C and 627 to 665 °C for dolomite and limestone dust, respectively. With increase in dust concentration from 500 to 3000 g/m3, the ignition temperature (IT) of coal-rock dust mixtures decreased by 28 % and 30 % for dolomite and limestone dust, respectively. Moreover, the MIT significantly increased with increase in thermal conductivity and specific heat capacity of coal-rock dust mixtures. Limestone dust proved to be a better explosion suppressant compared to dolomite dust.

Quantitative modeling and validation of the impact of border dust on photovoltaic panels: A piecewise single diode approach

Dust accumulation at the border of photovoltaic (PV) panels significantly reduces the power, safety, and economy of PV power generation. However, no quantitative model of the power generation of PV panels with border dust exists. A piecewise single-diode model (SDM) is used to establish a PV power generation model that considers border dust accumulation. The influence of the dust concentration and dust area on the model parameters is investigated. A numerical solution based on a dynamic initial value is proposed to obtain the voltage and power of PV cells at a fixed current. An experimental platform for border dust deposition is built to verify the model performance. The influence of border dust on the power generation of PV panels is discussed. The results show that border dust accumulation significantly reduces the power generation of PV cells. The power loss is 60.13 W (63.30 W) when the border on the PV panel’s short (long) side is covered with 36 g/m2 of sandy soil. Moreover, the impact of dust on the PV power generation differs for dust in different locations. The power loss increases with an increase in the dust concentration and dust area when the dust is on the border of the PV panel’s short side. In contrast, due to bypass diode protection, when dust is on the long side of the PV panel, the power loss will increase and then stabilize as the dust concentration increases. The dust type also affects the PV power generation ability. At the same dust level and location, the power loss is the largest for cement, followed by sandy soil and red soil.

Monitoring of farmland dust during tillage and sowing operations and comparative analysis of cultivation modes in the suburban areas of Beijing

Agricultural machinery's tillage and sowing processes can generate much farmland dust, adversely affecting the surrounding environment. Clarifying the dust emissions from various agricultural machinery operations and selecting a reasonable cultivation mode is significant for reducing dust in the atmosphere and protecting the environment. However, a systematic exploration of the agricultural dust generated during agricultural machinery operations is needed. Here, we designed a dust monitoring system to monitor farmland dust (PM2.5, PM10, and TSP) and environmental parameters at different points. The system is applied to monitor the dust emission concentration caused by agricultural machinery. We found the concentration of PM2.5, PM10, and TSP from straw returning operations to be 2.06, 3.16, and 2.84 times higher than that of ploughing operations. The increase in cultivation speed will lead to an increase in dust concentration. In straw returning operations, compared with low-speed, the increase in PM2.5, PM10, and TSP concentration during medium-speed cultivation is 21.6%, 12.5%, and 16.8%, whereas high-speed cultivation is 68.2%, 38.9%, and 35.7%, respectively. Moreover, conservation tillage modes can significantly suppress dust emissions. We found that conservation tillage produced the lowest concentrations of PM2.5, PM10, and TSP during the tillage and sowing stages, which were 64.7%, 73.1%, and 72.1%, compared to traditional tillage. As the amount of straw coverage increases, the dust concentration decreases. The average PM2.5, PM10, and TSP concentration increment of NTS with LSMQ increased by 307.8%, 344.8%, and 346.8%. Our results demonstrate that adopting a conservation tillage and sowing model and increasing straw coverage can reduce dust emissions. The research results have specific guiding significance for reducing dust emissions during the spring and autumn cultivation. We anticipate evaluating further the contribution of small particulate matter generated during agricultural machinery operations to air pollution, and our research will provide a basis for future work.

Testing the operation of the developed swirling scrubber

The article presents a study on the intensification of gas purification from solid particles using the hydrodynamic effect of centrifugal forces. An effective vortex dust collector design has been developed and is being implemented in production for cleaning from harmful impurities. The results of tests conducted at the facility to determine the efficiency of dust collection in a vortex apparatus with a tangential inlet of gas and liquid flow at various operating parameters are presented. The study found that the efficiency of the device increases with an increase in dust concentration. In the vortex apparatus, the efficiency of dust collection increases significantly with an increase in the axial flow velocity, which is characterized by an increase in centrifugal force and separation factor. The optimal operating modes of the developed vortex apparatus have been established in terms of the efficiency of dust collection.

Experimental Study of the Explosion Characteristics of Energy-Containing Materials Nto’s Lead Salt Dust

ABSTRACT The explosion characteristics of NTO’s lead salt as an energy-containing material are significantly different from those of ordinary dust. In order to systematically recognize its hazards in the production, storage, and transportation processes, the lower limit of explosion concentration, explosion pressure, pressure rise rate, and minimum ignition energy were systematically studied using the self-made 5 L column-type dust explosion test system and the modified 1.2 L steel Hartmann tube, respectively. The findings demonstrate that the explosion pressure and pressure rise rate gradually increase with the dust concentration; compared with ordinary dust, there is no maximum explosion pressure; the pressure rise rate has an inflection point of 550 g/m 3 , and if the concentration is greater than 550 g/m 3 , the pressure rise rate increases sharply. The explosion pressure is only slightly influenced by the pressure of powder spraying, which is inversely related to the rate of pressure rise. Contrary to the typical tendency of ordinary dust, where the ignition energy initially reduces and then increases with increasing concentration, the ignition energy tends to decrease as the dust concentration increases. As electrode spacing grows, the ignition energy tends to rise, and as concentration rises, the influence of electrode spacing progressively declines.

Energy output characteristics and safety design of Al-AlH3 composite dust for energetic material additive

Aluminum (Al) is the most widely used metal additive in energetic materials, but its application is limited due to its oxidizable nature. However, aluminum hydride (AlH3) could disrupt the oxide film structure and improve applications of the Al additive in energetic materials by releasing hydrogen. Therefore, this paper explored the explosion characteristics of the Al-AlH3 composite dust by conducting composite dust explosion venting experiments. The influences of composite dust concentrations and mass ratios on the explosion pressure and flame were evaluated. The consequences indicated that when the composite dust concentration was constant, the explosion pressure and the reduction rate of explosion pressure gradually decreased as increasing the mass ratio, which confirmed that the explosion intensity of AlH3 was greater than that of Al. When the composite dust mass ratio was the same, the increase in dust concentration caused the explosion pressure, the pressure rise rate, the flame front propagation distance, and velocity to increase first and then attenuate. 750 g/m3 was the best dust explosion concentration. On this basis, the safety design applicability of composite dust was conducted based on the NFPA 68 explosion venting design standard, which was verified to be suitable for Al dust. Notably, the safety margin should be taken into account when carrying out a safety design for composite dust using NFPA 68. In the paper, the composite dust explosion characteristics were obtained through experiments and mechanism analysis, which provided data support for the research of Al-AlH3 composite dust for energetic material additives.

Construction of an occupational-dust hazard testing platform: An experimental study on the deposition mechanisms

This study aimed to understand the influence of dust concentrations and environmental exposure on the mechanism of dust deposition in the human body following inhalation. Using a self-developed occupational dust hazard testing platform, the particle size and mass of dust in the environment and the dust inhaled by a bionic throat were measured under different conditions. The experimental results showed that an increase in dust concentration in the experimental area resulted in an increase in the size of the dust particles, particularly the absolute value of small-sized dust particles. The range of variation of the particle size of dust inhaled by the bionic throat was less than 25%, and the mass of dust inhaled exhibited a positive linear trend. When the dust concentration was fixed, an increase in the dust exposure time resulted in a gradual decrease in the dust particle size. When the dust exposure time reached 60 s, the particle size of the dust inhaled by the bionic throat remained constant, and the mass of the dust inhaled exhibited an increasing linear trend. With an increase in altitude, the dust concentrations in the experimental area gradually increased, whereas the dust particle size gradually decreased. The mass of dust inhaled by the bionic throat was represented by a quadratic power function. The results provide effective theoretical support for the prevention and control of dust originating from coal mines.

A numerical model for the prediction of the minimum ignition temperature of dust clouds

This paper presents a numerical model for the prediction of the minimum ignition temperature (MIT) of dust clouds. First, a physical model is developed for the dust cloud ignition in the Godbert-Greenwald furnace. A numerical approach is then applied for the MIT prediction based on the physical model. The model considers heat transfer between the air and dust particles, the dust particle reaction kinetics, and the residence times of dust clouds in the furnace. In general, for the 13 dusts studied, the calculated MIT data are in agreement with the experimental values. There is also great accordance between the experimental and numerical MIT variation trends against particle size. Two different ignition modes are discovered. The first one consists in ignition near the furnace wall for bigger particles characterized by rather short residence times. In the second mode, the ignition starts from the center of the furnace by self-heating of the dust cloud for smaller particles with longer residence times. For magnesium, as dust concentration increases, the lowest ignition temperature of the dust cloud IT(conc) decreases first, then transits to increase at a certain point. The transition happens at different dust concentrations for different particle sizes. Moreover, the MIT of the magnesium dust cloud generally increases as particle size increases, but the increasing trend stagnates within a certain medium particle size range.

Investigation of lag on ignition of coal dust clouds under varied experimental conditions

• Determined LOI of coal dust clouds under varied experimental conditions. • Ignition temperature significantly influenced the LOI of coal dust clouds. • LOI of coal dust clouds showed increasing trend with thermal properties of coal dust. • Optimum dust dispersion pressure that yielded minimum LOI is found at 70 kPa. • Established empirical relations between LOI and all the influencing parameters. Lag on ignition (LOI) of coal dust cloud greatly influences the initiation and propagation of coal dust explosion. This paper investigates the effects of coal dust particle size, dust concentration, ignition temperature, and dust dispersion pressure on LOI of coal dust clouds using Godbert-Greenwald furnace along with a high-speed camera. LOI of coal dust cloud significantly decreased by 1/13 times from 959 to 77 ms with increase in the ignition temperature from 600 to 1000 °C, demonstrating greatest influence of ignition temperature on LOI. LOI increased by 60% with increase in dust concentration from 500 to 4000 g/m 3 . Optimum dust dispersion pressure at which LOI was found minimum is determined 70 kPa. Empirical relations are established between LOI of coal dust cloud and particle size, ignition temperature, dust concentration, and dispersion pressure. The results are analysed in terms of the occurring physical processes, which led to a better understanding of the variation of LOI, ignition behavior, and explosion propagation of coal dust clouds at varied experimental conditions.

Iron dust explosion characteristics with small amount of nano-sized Fe2O3 and Fe3O4 particles

Iron powder, as one of the most abundant metal fuels that can be used as recyclable carriers of clean energy, is a promising alternative to fossil fuels in a future low-carbon economy. It may pose a potential explosion hazard during the process of processing, storage, transport, and reduction/oxidation (redox). The explosion characteristics of iron dust in air were undertaken via a 20 L spherical explosion chamber with an emphasis on minimum explosion concentration (MEC) of iron dust. The alternative method of combustion duration time (tc) was used to determine MEC and compared with the standardized over pressure method. Two kinds of nano-sized iron oxides (Fe2O3 and Fe3O4) were used as inertants to determine the inhibition effect of different oxidation products. The iron dust explosion products with various shapes and sizes were found to be able to grow up 4–6 times of the iron dust for the first time. Adding small amount of Fe2O3 or Fe3O4 could reduce the explosion severity and sensitivity of iron dust. The MEC data determined by both methods were comparable. The addition of 5 % oxide has obvious inhibition effect under 1500 g/m3 concentration. With the increase of oxide concentration to 10 %, the inerting effect increases, and the MEC of iron dust increases more than 3 times. The increase of dust concentration will weaken the inerting effect. When the concentration increases from 500 g/m3 to 3000 g/m3, the weakening effect of 10 % Fe2O3 on the explosion pressure decreases from 38.45 % to 2.24 %, and 10 % Fe3O4 decreases from 46.21 % to 10.63 %. Unlike coal, biomass or aluminum dusts, the iron dust explosion was found to have a unique secondary acceleration of pressure rise rate for the first time. These results provide a fundamental basis to mitigate the iron dust explosion via solid inerting method without adding extra elements.

Influence research of electrostatic environment on dispersion and explosion characteristics of typical biomass organic dust clouds

In order to explore the explosion characteristics of dust cloud under the coupling condition of electrostatic field, flow field and particle motion field, based on the theoretical analysis of the charging mechanism of dust particles in the electrostatic field, the motion mechanism and explosion behavior of three typical biomass dust were studied by means of experiment and simulation. The research results were presented in the electrostatic field to evaluate the dispersion effect and explosion hazard of dust clouds. It was found that when the dust concentration is less than 500 g/m3, both the peak explosion overpressure and the rate of explosion overpressure rise of dust increase with the increase of dust concentration under the loading of electrostatic field. Compared with the case without electrostatic field, the maximum explosion overpressure of three typical organic dusts are increased by 2.6%, 5% and 12.1% respectively. Moreover, a multi-field coupling mathematical model of particle charge and motion was established, which not only studied the influence law of electrostatic field on particle charging and gas-dust flow characteristics, but also discussed the influence mechanism of electrostatic field on dust cloud explosion intensity from the perspectives of particle concentration distribution, particle velocity distribution and turbulence intensity parameters.

Study on the coupling migration law of airflow-respiratory dust of an 8-m high fully-mechanized mining face

8-m super-high fully mechanized mining face has been successfully applied in China, which has brought many difficulties to dust control. The main reason is that the mining height increases and the dust distribution and evolution law are quite different. Targeting the 12,513 fully-mechanized mining face in Bulianta Coal Mine of China in this paper. The spatial evolution of airflow-respiratory dust of an 8-m high fully-mechanized mining face is analyzed using numerical simulation and underground measurement methods. The results reveal that the numerical and measured results are consistent. At the working range from 15 m in front of the shearer to 30 m behind it, the wind speed increases with an average rise of 70% on the coal cutting side. The airflow diffusion at the working face is primarily longitudinal and partly transverse. Along the airflow direction, the respiratory dust concentration in the pedestrian space first increases and decreases, followed by a marginal increase and gradual decrease，and the dust concentration increased with the increase of height, the migration distance of dust particles was directly proportional to time, and the smaller dust particles were prone to transverse diffusion. In the range of 20–30 m from the downwind side of the shearer, the transverse diffusion of coal cutting dust and the dust produced by support coal falling show conversion, leading to the increase of dust concentration. Under the same dust production intensity, compared with ordinary mining height, with the increase of mining height, the influence range of dust diffusion is wider, the floating duration is longer, and the space dust concentration will be reduced, and the support coal falling dust is the main dust pollution source in pedestrian space. The results reveal that the numerical and measured results are consistent, and obtained the relationship of spatial evolutions of respiratory dust

Laboratory results of foam application testing for longwall shield dust control in a simulated environment

There were 37 longwall faces operating in mines in the United States in 2019. The average panel width for these longwalls was approximately 368.5 m (1209 ft). This translates to a range of approximately 170–240 shields per longwall, depending upon the width of shield. The movement of longwall shields is a significant contributor to respirable dust overexposures to longwall operators. Foam is expected to have the potential to reduce this shield dust generation. The foam is applied to the area on the roof between the coal face and the shield tip after the shearer passes. In this study, the longwall shield dust simulator was used to test three foam agents for their ability to control dust from longwall shield movements. Results showed that at low-velocity ventilation (≈ 3.0 m/s (600 fpm)) all foam agents were able to produce dust reduction levels of at least 45%. At high-velocity ventilation (≈ 5.1 m/s (1000 fpm)), the reductions were lower and more variable, ranging from being undeterminable for one foam agent to having 46%–63% reductions for the other two foam agents, with one instance of an increase in dust concentration. Overall, the use of foam agents can provide longwall shield dust control. Important factors are roof coverage and the ability of foam to remain on the roof for extended time periods.

Protoplanetary Disk Rings as Sites for Planetesimal Formation

Abstract Axisymmetric dust rings are a ubiquitous feature of young protoplanetary disks. These rings are likely caused by pressure bumps in the gas profile; a small bump can induce a traffic-jam-like pattern in the dust density, while a large bump may halt radial dust drift entirely. The resulting increase in dust concentration may trigger planetesimal formation by the streaming instability (SI), as the SI itself requires some initial concentration of dust. Here we present the first 3D simulations of planetesimal formation in the presence of a pressure bump modeled specifically after those seen by Atacama Large Millimeter/submillimeter Array. We place a pressure bump at the center of a large 3D shearing box, along with an initial solid-to-gas ratio of Z = 0.01, and we include both particle back-reaction and particle self-gravity. We consider millimeter-sized and centimeter-sized particles separately. For simulations with centimeter-sized particles, we find that even a small pressure bump leads to the formation of planetesimals via the SI; a pressure bump does not need to fully halt radial particle drift for the SI to become efficient. Furthermore, pure gravitational collapse via concentration in pressure bumps (such as would occur at sufficiently high concentrations and without the SI) is not responsible for planetesimal formation. For millimeter-sized particles, we find tentative evidence that planetesimal formation does not occur. If this result is confirmed at higher resolution, it could put strong constraints on where planetesimals can form. Ultimately, our results show that for centimeter-sized particles planetesimal formation in pressure bumps is extremely robust.