Dust Flow Research Articles

Dust transport behaviour in the Nanwenhe extra-large stepped underground metal mine stope

This paper is aimed at studying the dust behaviour of a super-large stepped stope, which is essential in reducing the dust hazards and setting up effective dust control facilities. In this paper, a three-dimensional model is established for the super-large stepped stope of Nanwenhe. Based on the theory of gas-solid two-phase flow, the Fluent software was applied to carry out a numerical simulation of the air flow distribution in the stope and the dust concentration distribution from multiple dust sources. The simulation results reveal that air flow is affected by the roof fault, resulting in it being diverted to the connecting roadway of the return air roadway, the roof of the lower stope and the interior of the stope. A part of the air flow flows back to the upper stope operation area at a speed of 0.3–0.6 m/s. The dust produced by the shovelling and dumping operations forms a high concentration dust belt with a length of 41 m, a width of 3.6 m and an average concentration of over 260 mg/m³. A portion of the dust flows back to the operation area by bypassing the ore pillar, with a concentration of 60–80 mg/m³. The reliability of our simulation method was verified by field measurements of the air flow velocity and dust concentration. Finally, a new intelligent wind-fog combined dust removal system was designed according to the dust concentration distribution, which achieved an overall dust removal efficiency of 76.9%. These research results provide certain references for the study of dust migration law in underground metal mines and the development of dust removal equipments.

ИЗУЧЕНИЕ ВЛИЯНИЯ СКОРОСТИ ВХОДЯЩЕГО ПОТОКА НА ЭФФЕКТИВНОСТЬ ЦИКЛОНОВ

A study into the influence of the speed of the incoming dust flow and a size of the inlet of a cyclone on its performance. The structure of the flow field has been investigated by calculations made using the Reynolds Stress Turbulence Model (MTNR) for a cyclone separator. The findings show that the maximum tangential velocity in the cyclone decreases when the entry size to the cyclone increases. No acceleration occurs within the cyclone body (maximum tangential velocity is almost constant throughout the cyclone). Increased size of the cyclone inlet reduces the drop of pressure. The cyclone's cutoff diameter increases with the cyclone's inlet size (therefore, the overall efficiency of the cyclone decreases due to a low vortex strength). The effect of altering the entry’s width is more significant than its height, especially for the cut-off diameter. The influence of simulations of velocity fluctuation on prediction of collection efficiency of cyclone separators has been numerically investigated using MTNR and large eddy simulation (MBV). The Euler-Lagrange modeling approach was used by Solidworks Flow Simulation to simulate 3D non-stationary turbulent gas and solid flows in the high-efficiency Starmand cyclone. The simulation results have been compared with available reference data. An analysis of the findings shows that the MTNR and MBV could adequately predict the mean flow field. The study shows that the (MBV) performs well in predicting fluctuating flow field and capture efficiency for each particle size. The results show that prediction of collection efficiency, especially for fine particles, is greatly influenced by simulation of velocity fluctuations in cyclones.

Система мониторинга продуктов горения угольных котлов по сигналам акустической эмиссии для предотвращения опасных аварийных ситуаций

The system for monitoring combustion products in the coal-fired boilers is considered to prevent accidents during their operation. The method is based on the processing of the acoustic signal coming from the sensor, followed by the analysis of the obtained data. Acoustic signal from the moving dust cloud contains excess information about the flow dustiness. It can be used for determining the sources of an audio signal, the ways for emitting it, and the physical mechanisms of generation. Using the discrete fast Fourier transformation, two mathematical models for the analysis of dispersed dust were compiled — energy and amplitude-phase. The proposed spectral-timbre mathematical model for the time-series decomposition into a Fourier spectrum allows to obtain spectra consisting of the main and multiple timbre harmonics. Block diagram of the adaptive system for determining the concentration and disperse composition of the coal dust flow is presented (in the form of an algorithm). Concentration of the coal dust corresponding to one or another class of maximum permissible concentrations is determined by the pattern recognition method. Coefficients of the separating functions are calculated in accordance with the developed program of differential diagnostics. This problem is solved by the method of potential functions from the theory of pattern recognition. Training experiment was conducted on a closed circulation stand using the developed measuring complex. Obtained graphic map (acoustic diagram) visualizes the dust concentration zones depending on the frequencies and amplitudes of the Fourier spectral harmonics. This allows to clearly interpret the roles of the main and timbre harmonics of the spectrum. It also provides the possibility of a simple comparison of the concentrations of complex dust mixtures for the additive components of the spectrum of the analyzed acoustic signal.

A statistical approach for identification of dust-AOD hotspots climatology and clustering of dust regimes over Southwest Asia and the Arabian Sea

Daily atmospheric composition and meteorological data from MACC and ERA-5 reanalysis, were combined to analyse the spatiotemporal variability of dust-aerosol optical depth (DAOD) and to identify the prevailing dust regimes using Empirical Orthogonal Functions (EOFs) and Principal Component Analysis (PCA), respectively, over southwest Asia and the Arabian Sea from 2003 to 2012. The analysis reveals four DAOD regimes influenced by the relative positions of the monsoon low, persistent high-pressure systems and thermal lows and the associated wind regimes. The Southeast (SE) Arabia regime, is detected over the eastern Rub-Al Khali and Oman Deserts and is associated with cyclonic flows and low-pressure systems over the southeast Arabian Peninsula, while the highest DAOD are observed over the convergence zone of Shamal and monsoon winds. The Arabian Sea regime is associated with high dust presence over the marine environment originated from arid/desert lands in Saudi Arabia, Iran and Pakistan, and the concurrent action of monsoon, Shamal and Levar winds. The Thar regime is characterized by a deep thermal low over Pakistan and strong monsoon winds acting as density currents over the desert area, resulting in highest DAOD over NW India. The Aden Gulf regime, is characterized by a ridge stretched through Sudan to Bab al-Mandab Strait and a surface high-pressure system prevailed over the eastern Mediterranean and west Arabian Peninsula, resulting in anticyclonic pathway of dust plumes from the Arabian deserts and westerly dust flows from sources in Eritrea and Sudan that accumulate dust over the Gulf of Aden.

Gas temperature meter

Purpose: of the article is to develop a digital portable gas temperature meter in the range of -50…+600°C. To measure the temperature of dusty gas flows in the air pollution sources with the least significant digit of the digital device 1°C. Design/methodology/approach: The microprocessor measuring unit, probe and software is proposed. It leads to build a high-precision temperature meter based on a thin film sensor HM220 type "pt100". Findings: The calculation of the electrical schematic diagram parameters for signal conditioning of the sensor relative to the input range of the analog-to-digital converter. The experimental measuring unit and the probe of the gas temperature meter are assembled. The principle of the gas temperature meter calibration with the help of a precision resistance box MSR-60M is considered. The experimental gas temperature meter has a total standard uncertainty determined by type B for a maximum value of the measurement range of 1.94°C. The error of the sensor "pt100" makes the largest contribution to the total standard uncertainty, so the error increases in proportion to the value of the measured temperature. Research limitations/implications: On the basis of the proposed design of gas temperature meter it is possible to construct devices with various lengths of probes. Practical implications: The proposed meter is designed for environmental laboratories that measure the velocity, flow and sampling of dust and gas emissions from sources of air pollution. Originality/value: The device design differs due to the use of thermostable wire made of constantan as extending conductors of the temperature sensor, which is included in the unbalanced Wheatstone bridge. This solution allows the use of unipolar power supply 3.3 V for both analog and digital part of the meter. Temperature meter based on a thin film resistance thermometer is characterized by relative ease of manufacture, low material consumption, cost and high reliability.

Dust entrainment in magnetically and thermally driven disk winds

Context.Magnetically and thermally driven disk winds have gained popularity in the light of the current paradigm of low viscosities in protoplanetary disks that nevertheless present large accretion rates even in the presence of inner cavities. The possibility of dust entrainment in these winds may explain recent scattered light observations and constitutes a way of dust transport towards outer regions of the disk.Aims.We aim to study the dust dynamics in these winds and explore the differences between photoevaporation and magnetically driven disk winds in this regard. We quantify maximum entrainable grain sizes, the flow angle, and the general detectability of such dusty winds.Methods.We used the FARGO3D code to perform global, 2.5D axisymmetric, nonideal MHD simulations including ohmic and ambipolar diffusion. Dust was treated as a pressureless fluid. Synthetic observations were created with the radiative transfer code RADMC-3D.Results.We find a significant difference in the dust entrainment efficiency of warm, ionized winds such as photoevaporation and magnetic winds including X-ray and extreme ultraviolet heating compared to cold magnetic winds. The maximum entrainable grain size varies from 3 μm−6 μm for ionized winds to 1 μm for cold magnetic winds. The dust flow angle decreases rapidly with increasing grain size. Dust grains in cold magnetic winds tend to flow along a shallower angle compared to the warm, ionized winds. With increasing distance to the central star, the dust entrainment efficiency decreases. Larger values of the turbulent viscosity increase the maximum grain size radius of possible dust entrainment. Our simulations indicate that diminishing dust content in the outer regions of the wind can be mainly attributed to the dust settling in the disk. The Stokes number along the wind launching front stays constant in the outer region. In the synthetic images, the dusty wind appears as a faint, conical emission region which is brighter for a cold magnetic wind.

Calculation Scheme of Purification of Industrial Emissions in Separators of Nozzle Type

The article discusses a model of motion of a four-phase continuum that simulates the flow of dusty gas in a nozzle separator. The main design features of such separators are considered, in particular The rebound of solid particles from the walls of the nozzle is taken into account and their influence on the efficiency of cleaning gas and dust flows in separators of this type is investigated. It is shown that, at high mass contents of the dispersed phase in the inlet section of the nozzle of the first stage, the distribution of the parameters of the dispersed flow in the flow part of the separator has a nonmonotonic character.

DETERMINATION OF THE PATTERN OF DUST AND AIR FLOW MOVEMENT IN VORTEX MECHANISM

At present, the problem of air pollution is a serious environmental problem that negatively affects the living conditions and health of people. The composition of atmospheric air in large industrial and urban agglomerations depends on the type of production and the level of its technology. A promising method of improving dust collectors is the creation of dust collectors, where the principles of operation of several devices are implemented.

Интегрированная система управления безопасностью производств, связанных с обращением горючей пыли

Purpose. For chemical, food, woodworking, pharmaceutical and some other industries, the main fire hazard factor is the circulation of explosive dust and gas flows containing combustible dust. For their disposal and removal from the volumes of equipment and premises, production aspiration systems (PAS) are used, their effective functioning is the key to production safety, so the given work is aimed at developing an automated PAS control system that ensures fire safety, as well integrating PAS control system into ACS of the production. To achieve this goal, the tasks of identifying the main hazards, developing an information environment for the system, developing mechanisms for the interaction of PAS accident triggers with the information environment and other subsystems of the automated control system, and, ultimately, creating the concept of a single system – an integrated production safety management system (IPSMS) are considered. Methods. The task is carried out by systematizing information related to the specifics of developing and operating industrial aspiration systems and evaluating information using logical functions, as well as developing the model based on the graph theory, namely, describing the system operation using Petri nets. Findings. To achieve the goal, the concept of an integrated production safety management system is proposed. The concept takes into account the peculiarities of the technological process and integrating with the subsystems of the production automated control system to neutralize both local accidents and accidents that develop into large-scale emergencies. The system considers the specifics of the main technological equipment and hardware solutions for dust collection in PAS, the degree of production automation, the categories of premises according to explosion and fire hazard. Based on the information analysis, a sequence of actions has been developed to eliminate the accident or minimize its consequences. To implement the tasks of IPSMS, a mathematical model based on the Petri net has been developed. Research application field. The results obtained can be used to design and improve automated systems for preventing accidents, fires and explosions in industries associated with the handling of combustible dust. Conclusions. The use of IPSMS will simplify the decisionmaking process linked with the analysis of a large amount of highly specific information related to the operation of industrial aspiration systems. The proposed methods and models are reliable tools\for the system of intelligent decision making support in stressful situations.

Evaluating the Meteorological Conditions Associated With Dusty Atmospheric Rivers

AbstractTrans‐Pacific dust has been shown to influence the micro‐physical characteristics of atmospheric rivers that make landfall along the U.S. west coast. Atmospheric Rivers (AR) reaching North America provide valuable water resources, but also can produce damaging floods. While substantial research has been devoted to understanding the structure and meteorological drivers of atmospheric rivers, far less is known about the conditions that lead to the presence of dust within and around these storms. Here, we utilize an 18‐year record of the dust content of AR surroundings combined with satellite, reanalysis, and observational meteorological data to understand the drivers of ARs embedded within dusty environments, or “dusty ARs,” as compared to ARs in more pristine environments. We find that dusty ARs are associated with transport of dust from the east Asian coast to North America. Dusty ARs are characterized by conditions that are especially conducive to transport of dust across the Pacific; namely, enhanced mid‐ to upper‐tropospheric westerly winds over Asian dust source regions and over the Pacific. In contrast, ARs in more pristine environments are associated with a persistent ridge over the central Pacific, which blocks zonal westerly flow, as well as continental dust. We also show that while trans‐Pacific dust is largely confined to the 600–200 hPa levels, this dust flows downward along post‐cold frontal isentropic surfaces into the AR environment in the lower troposphere.

Aspects Regarding Polluting Emissions to the Stack of Clincher Ovens in Romanian Cement Factories

The paper presents an analysis of the flow of flue gases and dust in the area of the clinker kiln and in the area of the flour mill, as well as emission data for the last three consecutive years at the flour mill stack - clinker kiln, from some cement factories in Romania. In general, both emissions of dust (total powders) and pollutant gases (SOx, NOx, CO, dioxins and furans, VOC, heavy metals, etc.) were within the permissible limits set out in the Integrated Environmental Permit of the individual plants.

Simulation-based sensitivity analysis and optimization of narrow strip electrostatic sensor

Aiming at the problems of low sensitivity and large interference to the dust flow field when the rod electrostatic sensor detects pipe dust, the narrow strip electrostatic sensor is proposed in this paper. Firstly, the high fidelity 3D finite element model of narrow strip electrostatic sensor, pipe and dust particles is established by COMSOL software. By gridding the model, the electrostatic field distribution in the pipeline under the action of charged dust is simulated. Then the spatial sensitivity distribution of the narrow strip electrostatic sensor in the dust pipe is analyzed. Finally, the influence of the length, width and thickness of the strip electrostatic sensor on the spatial sensitivity of the narrow strip electrostatic sensor is analyzed, which provides a basis for the structural design of the high sensitivity narrow strip electrostatic sensor.

On the similarity of dust flows in the inner coma of comets

The atmosphere of a comet is formed by the sublimation, due to solar illumination, of its volatile component and the dust particles ejected from its nucleus and entrained by the gas flow. Contemporary dusty-gas coma models take into account numerous physical processes occurring in the coma and a complex geometry of the nucleus. For the description of the dusty-gas flow in the coma, such models introduce a large number of governing parameters characterizing physical properties and processes. The relative role of these processes is not easy to ascribe therefore a relevant inter-comparison of model results becomes difficult.The present work introduces a set of universal, dimensionless parameters, which characterize the dust motion in the inner cometary coma. This approach allows one to: (i) reduce the number of parameters for analysis; (ii) reveal dust flows similarities; (iii) rescale the available numerical solutions. The present work demonstrates application of this approach to a realistic coma model.Description of dust motion with dimensionless parameters allows us to make a parametric study for a broad range of conditions and to find simple analytic approximations (via a polynomial function) of the numerical results suitable for rough estimations of dust density in the coma.

Improvement of Interstellar Material and Energy Flows

Objectives
 A novel approach is suggested to utilize the inherent forces of the universe for the benefit of mankind, by applying the model for Efficient Use of Resources for Optimal Production Economy (EUROPE) to improve the major flows of gas, dust, material and energy between stars and galaxies. This endeavour is regarded as promoting the altruism and benevolence by increasing life-forms’ chances to survive.
 Methods
 It is shown how the torus-shaped flows of gas, dust material and energy between stellar bodies in cosmos can be improved with the EUROPE model in order to preserve universe and secure its existence by allocating shadow costs to waste-like flows and unwanted radiation in this torus. The fewer shadow costs being allocated to the stellar residuals, the more efficient the cosmic torus flows, expressed in equivalents of antimatter released, by inducing incentives to improve the conditions for all inhabitants.
 Results
 The methodology promotes the economy when travelling in space, advances the technology used and improves the environment, when outer space in the future is explored and exploited. A single key factor enables monitoring, managing and evaluating the development of universe and the flows of gas, dust, material and energy between various stellar objects, such as the distant stars and whole galaxies.
 Conclusions
 I recommend using the EUROPE model to monitor, manage and evaluate the wastes and spillages of all material and energy phenomena throughout the known universe, to uphold its very existence.

Mars: Abundant Recurring Slope Lineae (RSL) Following the Planet‐Encircling Dust Event (PEDE) of 2018

AbstractRecurring slope lineae (RSL) are dark linear markings on Mars that regrow annually and likely originate from the flow of either liquid water or granular material. Following the great dust storm (or planet‐encircling dust event, PEDE) of Mars year (MY) 34, Mars Reconnaissance Orbiter/High Resolution Imaging Science Experiment has seen many more candidate RSL than in typical Mars years. They have been imaged at more than 285 unique locations from August 2018 (when the atmosphere was clearing as the PEDE decayed) to August 2019, about half (157) of which are locations where RSL have not been documented previously. In MY34, 150 active RSL sites were identified in the southern middle latitudes (SML, ‐60° to ‐30°), whereas an average of 36 active sites were observed in each previous year (MY28–33). Post‐PEDE RSL are also present during southern summer over a wider range of latitude, slope aspect, andLs(areocentric longitude of the sun) than in prior years. These RSL sites usually show evidence for recent dust deposition: obscuration of relatively dark areas, an overall brighter and redder surface than in prior years, and dust devil tracks, which indicate dust lifting by several mechanisms. We speculate that dust‐lifting processes may initiate and sustain RSL activity. The RSL may form from flows of dust (perhaps clumped) and/or sand that is destabilized by dust movement or directly mobilized by dust devils. If this is the case, then the otherwise puzzling recurrence and year‐to‐year variability of RSL activity can be at least partly explained. The dust replenishment varies from year to year, which could explain interannual variations in RSL activity.

Numerical study of the processes of co-combustion of pulverized coal and gas fuel based on nonstationary methods of turbulence modeling

In this work, a numerical study of the combustion of pulverized coal in a gas flame is carried out on the basis of the proposed mathematical model of combustion processes, using a nonstationary method for modeling turbulence, complex heat transfer and a reduced mechanism for chemical kinetics. The calculation results show acceptable agreement with the experimental data on the main characteristics of the flame, make it possible to qualitatively correctly determine the structure of the dust and gas flow and derive such parameters as the gas composition, the temperature of particles and gas, the degree of carbon burnout, etc.

Система акустического мониторинга в промышленных и экологических технологиях

The task is considered related to the creation of monitoring systems in the industrial and environmental technologies that allow to conduct continuous analysis of dust in the industrial premises and quality control of the products made of powders, charges, and other dispersed and composite materials. The proposed methodology is based on the acoustic spectral-timbre control. It allows to make an operational analysis of the physical and chemical properties of the dispersed systems. Using a spectrum analyzer, the acoustic signal is decomposed into a Fourier spectrum consisting of the fundamental and timbre harmonics. The higher harmonics of the spectrum provide for more complete information about the amplitude-frequency parameters of the dispersed system and allow to distinguish by classes of the dispersed composition. The graphical representation of the division of the information space into classes with optimal characteristics allows to interpolate and visually evaluate the belonging of the analyzed spectra to the family with the parameters corresponding to these dispersed systems. When dividing the information space into standard classes, the boundaries between them are approximated by Hermite polynomials with the preservation of the first terms. This makes it possible to divide the modes of dust flows into concentration classes, as well as formally separate them from each other by constructing separating boundaries. After calculating the coefficients of the separating functions, the separating boundaries are determined, which, by virtue of the accepted agreement on the basis functions, will be piecewise linear. The coefficients of the separating functions are calculated according to the developed program of differential diagnostics by the method of potential functions, which implements this method from the theory of pattern recognition. Patterns to be recognized and classified using an automatic recognition system must have a set of measuring statistical characteristics of the spectrum of acoustic emission signals of the dust flow. Pattern recognition systems allow to configure the measurement system to recognize the required concentration classes based on the collected information.

Model and Experiment on Resistance Loss of Wet Chordal Grid with Spray Pressure and Structural Parameters

To reduce the dedusting resistance of wet vibrating string grille precipitators during dedusting in mine ventilation roadways, we investigated the dedusting resistance characteristics of water fog and water film coupling and determined the relationship between dedusting resistance and spray pressure, vibrating grid filling rate, and wind speed. A mathematical resistance coefficient model is established using hydrodynamics theory and capillary mechanics. The theoretical relationship of dedusting resistance is deduced. The results show that when wind speed is constant, the spray pressure and dedusting resistance are higher and the resistance is smaller with a high filling rate compared with a low filling rate. Constant spray pressure allows faster wind speeds and reverse pressure gradient forces to increase when dust flows around the wet vibrating wire, which makes the pressure distribution asymmetrical around the steel wire and increases resistance. Dust removal resistance of the resonance chord with a high filling rate is substantially lower than that with a low filling rate under the same working conditions. On the basis of satisfying the dedusting efficiency, the resonance chord dedusting system does not affect normal production and resistance is low. The spray pressure is controlled at 0.3–0.7 MPa and the optimal wind speed is 3–4 m/s. According to the theoretical calculation and experimental data, the optimal filling rate of a vibrating string grid plate is 77.8%, spray pressure is 0.7 MPa, and wind speed is 3.5 m/s. Dust removal with low resistance and improved economic benefit can thus be obtained.

To the problem of determination the aerodynamic resistance coefficient value to the swirled dust and gas flow in the air ducts of engineering and environmental systems

The experimental studies‘ results of the aerodynamic drag of a swirling dust and gas flow passing through a network of air ducts of engineering and environmental systems are presented. The limits of the method applicability for determining the aerodynamic resistance coefficient of a gas-dust swirling flow passing in a round aspiration duct, without taking into account the solid phase presence in it, have been determined.

Determining Optimum Productivity of a Ball Drum Mill When Milling Brown Coals

Ball drum mills (BDM) are one of the main types of coal-grinding equipment in Russia. A significant drawback of BDM is high power consumption (a significant part of the TPP’s own needs). With a huge scale of production, reducing these costs even by a few percent gives a significant economic effect. The problem of minimizing the specific energy consumption for grinding and transporting Azean coal in an ShK-32 ball drum mill is considered. For moist brown coals, the efficiency of grinding and transport of coal dust is usually achieved in the mode of equality of the grinding and drying capacities of the mill. The implementation of this regime is a necessary but insufficient condition. A system of equations is obtained that describe the processes of grinding and transport of coal dust. The analysis of the equations shows that the specific energy consumption for grinding is inversely proportional to the air consumption, and the specific costs for the transport of the dust and gas flow are proportional to the square of the air consumption. This fact ensures the presence of a minimum specific energy consumption for pulverization. A comparison is made of the estimated consumption of specific energy for pulverizing in an ShK-32 ball drum mill with experimental results obtained during routine commissioning tests of the dust system of the Irkutsk CHPP-9. The average deviations of the calculation results from the experimental data are in the range of ±10%. Comparison of the calculated and experimental data indicates that the mathematical model of the mode of equality of the grinding and drying capacities of the BDM adequately describes the processes occurring during the preparation of fuel for combustion. It is shown that an increase in the efficiency of dust systems with BDM can be achieved only after a detailed study of the transport of coal dust. In the proposed method for determining the optimal performance of the ball mill, the effect of the polydispersity of coal dust on the aerodynamic resistance of the mill is consistently taken into account.