Dust Separation Research Articles

Research Status of Dust Reduction Technology in Coal Handling System of Thermal Power Plant

Aiming at the dust control of coal handling system in thermal power plant, the research status of dust reduction related theory and technology was summarized. This paper introduced the research progress of dust and air separation mechanism and multiphase flow simulation technology in dust removal and suppression, as well as the features and application of dust removal technologies such as wet dust suppression, bag type dust removal, high voltage electrostatic dust removal, unpowered dust reduction and others. The technical route of dust reduction in coal handling system of thermal power plant was advised, which provides reference for dust control in coal handling system.

Online‐Partikelmessung im Reingas zu Beginn der kuchenbildenden Staubabscheidung mit Nadelfilzen in der Gasreinigung

AbstractDie Partikelabscheidung aus Gasen mit filternden Abscheidern lässt sich in zwei Gruppen einteilen: die Tiefen‐ und die Oberflächenfiltration. Ein neues, unbelegtes Filtermedium für die Oberflächenfiltration startet jedoch immer mit einer Tiefenfiltrationsphase im Filtermedium. Die Umwandlung einer Tiefenfiltration in die Oberflächenfiltration geschieht durch eine Clogging‐Phase, in der sich die Filtrationskinetik über einen gewissen Zeitraum ändert. Dieser Beitrag präsentiert theoretische Überlegungen über eine neue Definition für den Beginn der kuchenbildenden Staubabscheidung im Hinblick auf die Partikelabscheidung und eine entsprechende experimentelle Untersuchung mit Nadelfilzen zur Filtrationskinetik zu Beginn der kuchenbildenden Staubabscheidung, die im Sinne der Oberflächenfiltration grundlegende Bedeutung hat.

Mie–Raman–fluorescence lidar observations of aerosols during pollen season in the north of France

Abstract. The multiwavelength Mie–Raman–fluorescence lidar of the University of Lille has the capability to measure three aerosol backscattering coefficients, two extinction coefficients and three linear depolarization ratios, together with fluorescence backscattering at 466 nm. It was used to characterize aerosols during the pollen season in the north of France for the period March–June 2020. The results of observations demonstrate that the presence of pollen grains in aerosol mixture leads to an increase in the depolarization ratio. Moreover, the depolarization ratio exhibits a strong spectral dependence increasing with wavelength, which is expected for the mixture containing fine background aerosols with low depolarization and strongly depolarizing pollen grains. A high depolarization ratio correlates with the enhancement of the fluorescence backscattering, corroborating the presence of pollen grains. Obtained results demonstrate that simultaneous measurements of particle depolarization and fluorescence allows for the separation of dust, smoke particles and aerosol mixtures containing the pollen grains.

Characteristics of dust distributions and dust control measures around road-header drivers in mining excavation roadways

In the present study, a numerical simulation method was adopted in order to examine the characteristics of dust dispersion during continuous dust release periods (CRP) and stop dust release periods (SRP). The purpose was to analyze the dust distributions and migration actions around road-header drivers in excavation roadways, and then determine effective dust control measures for underground coal mines. This study’s simulation results showed that the dust concentrations continuously increased, and then gradually reached a stability level during the CRP. During that time, the locations of the drivers were always at the intersection of the original migration dust and the backflow dust, and the drivers were invaded by these two strands dust. However, during the SRP, the dust concentrations gradually decreased under the actions of the roadway ventilation. Besides, obvious backflow phenomena were observed around the road-header during the SRP. The locations of the drivers were still within the backflow paths of the high dust concentrations. At the present time, dust separation and extraction systems have been implemented in coal mines, including vacuuming and air knife devices, which are designed to control the dust around the road-header drivers. The field applications of these systems were conducted in the 26 mechanized excavation faces of the Zhangcun Coal Mine. The results revealed that the use of these dust removal systems could effectively reduce the dust concentrations around the road-header drivers. In the present study, the dust removal rates during the CRP and SRP were determined to reach up to 88.7% and 94.6%, respectively. Therefore, the results of this research study provided effective theoretical guidance of the characteristics of dust distributions in coal mines, and introduced effective control methods for the hazardous dust concentrations around road-header drivers during the excavation process.

Inertial Separation of Particles Escaped from Electrostatic Precipitators.

For particles that escape from electrostatic precipitators (ESPs), inertial recapture is used to improve the efficiency of dust removal. A rod-grid inertial separator was designed. The electrostatic and fluid flow particle tracking modules were selected in the model established by the COMSOL software, and the dust removal efficiency of the proposed dust separator was evaluated. When the flue gas velocity was 20 m·s–1, the diameter of the round rod was 8 mm, and the spacing of the pipes was 15 mm, the removal efficiency of PM2.5 and PM10 reached 27.8 and 84.6%, respectively. Experiments were performed under laboratory conditions and actual working conditions in a coal-fired power plant flue. Results showed that an inertial separator can achieve more than 60% efficiency in recapturing fly ashes that have escaped from ESPs. It can effectively remove fine particles and aerosol pollutants represented by PM2.5 and PM10.

Solutions to reduce dust emissions mass into urban air in aerated concrete production

Low fractional efficiency of dust separation equipment used in dust cleaning systems in the production of building materials remains one of the main causes of dust emissions with a high content of РМ10 and РМ2,5 fine particles in the atmospheric air, both on the industrial sites territory, and on the borders of sanitary protection zones. The wide range of building materials produced by the construction industry with different raw materials, requires a tailor-made approach to develop the solutions to reduce dust emissions. This approach is primarily based on the properties of dust emitted during the production process.

Asian dust impacts on heterogeneous ice formation at Wuhan based on polarization lidar measurements

We analyzed 456 thin mid-level cloud layers based on two-year polarization lidar measurements in Wuhan (30.53°N, 114.37°E), China. Dust separation algorithm based on lidar measurements was implemented to identify clouds under influences of dust and non-dust components. Through comparisons of ice-containing cloud fractions under dust and dust-free conditions, significant impacts of Asian dust on heterogeneous ice formation are found. 20% more ice-containing cloud fractions occurred under influence of Asian dust at temperature range from −25 to −10 °C. More than 90% of dust-related heterogeneous ice formation were associated with polluted dust. In order to investigate the efficiency of non-dust components to serve as ice nuclei (IN), results at two continental sites (Wuhan, East Asia and Leipzig, Central Europe) with very different aerosol loadings were compared and discussed. Weak and similar ice nucleation characteristics under dust-free conditions of different loadings of sulfate, black carbon and organic carbon, may suggest such components are all less effective INs.

Dispersion characteristics of dust pollutant in a typical coal roadway under an auxiliary ventilation system

To control dust pollutant efficiently for cleaner production, the present study investigated the dispersion characteristics of dust pollutant in a typical coal roadway under an auxiliary ventilation system. First, the dust particles with the air flow were investigated successively via the Euler-Euler and the Euler-Lagrange methods. Meanwhile, each dust particle was traced, and the particle collisions were considered via the hard-sphere model and the direct simulation Monte Carlo method. Then the bulk movements of dust particles were simulated after certain validations with the related the field measurement results, and dust distribution were explored under main influence factors, like the particle size and the initial supply air velocity. The present study indicated that the circumfluence occurs mainly with the finer and the fine dust particles (<20 μm), which also contribute in dust suspension. Approximately 50% or more of the total suspended particles are particulate matter that that less than 10 μm (PM10). The relatively bigger particles (>40–60 μm) mainly settle down on the return air side. Dust separation and the layering distribution of different sized particles are more obvious when the initial supply air velocity is higher. The sedimentary and the suspended particles presented by the quantity overtime all follow the logistic function, including PM10 and PM2.5. The present results on dust pollutant deepen the understanding of dust dispersion in the confined space and provide helpful guidance on effective dust control methods for cleaner production.

Consistent dust electrification from Arabian Gulf sea breezes

The Arabian Gulf region experiences regular thermally driven sea breeze circulations which occur all year round, penetrating hundreds of kilometres inland. As a sea breeze front moves inland, substantial electric fields are generated by separation of charged desert dust. In the first surface electric field measurements made in the United Arab Emirates (UAE), consistent and repeatable substantial electric field changes with magnitudes up to 7 kV m−1 have been detected at Al Ain (170 km from the western coast), during 80 separate sea breeze events in 2018. Every sea breeze frontal passage shows the same characteristic signature of a transient maximum peak in electric field lasting tens of minutes. Electric field changes during these events were always negative (i.e. enhancing the existing negative ‘fair weather’ electric field), in contrast to many other reported observations in dust storms in which conditions were less repeatable. The regular and substantial dust electrification found demonstrates that accurate representation of dust in climate and weather models requires electrical effects to be addressed, both in the generation process, and by considering aggregates in radiative transfer calculations as electrically aligned rather than randomly ordered. Furthermore, satellite aerosol retrievals are affected by the changed attenuation of electromagnetic radiation when dust particles are charged, for which corrections may be needed.

Fiber Waste From Cotton Process Technological Processes

This article shows the changes in fiber waste from cotton processing and how it is gradual. The dust emitted in the dry-cleaning shop is only 5-7 mg/m3 of dust, less than the air in the building where the drying machines are located. This is due to the fact that high moisture is absorbed into the dryers, which prevents the separation of fine dust from the mass. The large dispersed dust, even at high humidity, was separated and was unable to disperse in the building. In the drying units, dust that comes with an atmospheric drying agent causes trouble. This dust, even with a rough dispersion, sits in the dryer along with the gas flow to the roof of the building and the ground near the drying shop. The amount of dust released is 500-600 kg/day. In the compartment, the dust emits from the air pneumatic system, which is an indispensable dust in the air drying shop, as well as the dust generated by cleaning machines. This is a powdery fiber, which contains less mineral fractions. The small fractions are composed of mostly dirty particles. Powdered air is also isolated from aspirate systems of gin suppliers, which absorb absorbed air or polluted air from pollutants. Such suction system can be included in the aspiration of the cotton distribution screw. It is established that only one cotton gin industry produces 150-350 tons of fiber per year, industry-wide waste is 5-6 tons, and 70-90% of organic waste is non-toxic. This will serve as a feedstock for the use of animal feed in the agricultural sector. Researches have been carried out to identify the amount of emissions from the ginneries at the Karasu, Mustaqillik and Ginnery factories in the Tashkent region and the Metan cotton gin enterprises in Samarkand region.

Mass balance of mercury in a pilot scale mercury recovery plant using thermal roasting technology

A pilot scale mercury recovery plant was developed to treat Hg waste by thermal treatment. The capacity of the system was 60 kg/batch and consisted of four units carrying out thermal treatment, dust separation, condensation, and flue gas treatment. The mass balances of Hg from five different wastes in three categories were calculated from Hg recovery data. From the following selected five wastes, Hg-added product, Hg-contaminated soil, byproduct of fluorescent lamp treatment process, and waste sludge from non-ferrous metal industrial process, we recovered 97.5%, 83.61%, 93.07%, 70.25%, and 29.36% of elemental mercury, respectively. Dust interfered during the condensation process, as volatilized Hg vapor was condensed with dust. Hg concentrations in leaching extract of treatment residues from the Hg-added product, Hg-contaminated soil, and the byproduct of fluorescent lamp treatment process were 0.003 mg-Hg/L, 0.0045 mg-Hg/L, and 0.002 mg-Hg/L, respectively, which are below the Korean classification standard of hazardous waste for mercury (0.005 mg-Hg/L). Hg concentration in flue gas was lower than 15 μg-Hg/m3 after passing through the activated carbon trap. Byproducts of the pilot scale system, such as activated carbon and dust can be further treated and converted to Hg free waste.

Dust Content and Adhesion Characteristics of Five Corn Samples

HighlightsThe corn sample and centrifuge speed interactions were statistically significant predictors of dust generation.Attachment strengths of dust particles were calculated, with forces ranging from less than 4.6 × 10-10 N to 2.1 × 10-8 N.A sequential centrifuge experiment indicated a bimodal distribution of adhesion forces.Abstract. Grain dust explosions are a constant threat to the grain handling industry. Explosions occur when dust accumulates beyond the minimum explosion concentration in a confined area and is exposed to an ignition source. Handling and grain unloading conditions that generate dust, the minimum explosive dust concentration, overpressure from an explosion, and other factors that lead to grain dust explosion are well documented in the literature. The adhesion force that holds grain dust particles to the grain itself is an important factor in better understanding and mitigating dust separation from grain kernels and the resulting dust cloud generation. However, that adhesion force, how it is affected by grain quality, and how it is influenced by particle factors such as size and shape has not been adequately researched. A centrifuge separation technique was used to study the adhesion forces of grain dust. Results showed large variability in dust concentration between the five corn samples tested in this study. The dust particle attachment strength ranged from less than 4.6 × 10-10 N to 2.1 × 10-8 N. Only the sample and centrifuge speed interaction had a statistically significant effect on dust concentrations recovered at a 5% confidence limit. Under repeated centrifugations, the dust removed showed a bimodal distribution of attachment strengths, with three of four samples tested showing a local minimum at 2000 rpm, and the other at 3000 rpm. This study improves the understanding of the fundamental attachment strength behind dust separation from grain kernels. Investigating the size, shape, and surface characteristics of dust particles with varying attachment strengths is important to further understand their adhesion and separation mechanisms. Keywords: Adhesion strength, Dust explosion, Dust mitigation, Grain dust, Grain handling.

Lidar Based Separation of Polluted Dust Observed Over Warsaw (Case Study on 09 August 2013)

This paper presents preliminary results of using an extended POLIPHON method for separation of dust and non-dust aerosol backscatter coefficient, applied on a case study of 9th August 2013. That day, long-range transport of mineral dust over EARLINET-ACTRIS lidar site in Warsaw was observed with the 8-channel PollyXT-UW lidar. The dust particles were also observed by the Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) on board the CALIPSO satellite. The backward trajectories calculated using the HYSPLIT model confirmed the air-mass transport from Northern Africa. Results yield possible dust separation for the mixture of dust with other aerosol types, such as pollution, marine type, etc.

Issues of protection of atmospheric air against dust pollution in production of construction materials

To protect the atmospheric air from dust pollution in building materials’ production, systems of inertial dust control are most frequently used. The application of swirling inertial dust separators in the counter swirling flows (CSF) enables to considerably enhance the degree of purification of industrial emissions from dust especially from fine particles PM10 and PM2.5. The authors carried out a complex of research works targeted at reasons of technical decisions providing an increase in the efficiency of dust contol systems with the devices of CSF for the construction materials industry. As it was stated by the results of the research, the following decisions belong to the process: suction from the swirling dust separator bunker and supplying the dust and gas flows with various dust content to its top and bottom feeds. The article presents some results of laboratory and pilot studies the objective of which was both the validation of efficiency and practicability in application of the mentioned technical solutions and revealing operation parameters under which the least breakthrough of dust into the air is achieved in the dust control systems composed according to these solutions.

Environmental Aspects of Treatment with Lactose-containing Biological Preparations in Organic Agriculture

The paper presents data from developing a technology for production of protectingstimulating lactose-containing biological preparations to be applied in growing small grain crops. The process diagram of the biological preparation production includes 7 stages: raw feed acceptance, quality evaluation; separation of fat and casein dust; production of plant extracts; fermentation of the plant extracts with whey; sterilization; bottling and packaging; storage and sales Studies of qualitative and quantitative indicators of the biological preparation have been completed and its photometric indicators have been studied to standardize the preparation. Influence of the biological preparation onto growth-stimulating activity of winter wheat seeds variety DON-85 was studied in the laboratory. Application of the protecting-stimulating biological preparation to wheat cultivation (var. DON-95) and agricultural applicability were studied in field studies conducted on the test plots of instructional and experimental farm of Stavropol State Agricultural University. Practical recommendations for use have been developed.

Simulation and Comparative performance analysis of Modified Cyclone Dust Separator

The cyclone separator is industrial equipment that is in use for a long time. Because of its industrial importance, a lot of extensive research work has been done. This paper discusses the efficiency of cyclones by considering the pressure loss and collection efficiency (cutoff diameter). The simulation of fluid-dust flow field in a cyclone is carried out using computational studies. The gas flow rate and temperature and geometrical parameters governing the efficiency of cyclone are the focus of this study. In this paper, the influence of the geometry on flow field pattern and performance of the tangential inlet cyclone separators are analyzed using computational work. The current work is carried out in three steps. First phase is dedicated to study the Stairmand’s optimized design to appreciate the pressure and speed fluctuations. This study if followed by examining the cyclone separator by varying the inlet width and height; and the cyclone total height. Finally, mathematical study to determine the efficiency of the dust separator is done.

Deliquescence and Efflorescence of Hygroscopic Salt Particles in Dust Cakes on Surface Filters

AbstractIn the case of dust separation with surface filters, both the structure of the formed cake and the adhesive bonds on particle contacts significantly influence the operating behavior. Microscopic as well as macroscopic insights into the characteristics of deliquescence and efflorescence of salt particles in contact with non‐hygroscopic particles are presented. By means of an environmental scanning electron microscope a change to the adhesive bonds as well as a restructuring of the dust cake are observed. The change in the performance of test filters by inducing deliquescence and efflorescence of the salt particle fraction in a dust cake is investigated on a customized standard filter testing rig.

Гранулирование пылевых отходов кремниевого производства для возврата в технологический процесс

The purpose of the work is to propose a granulation technology for dust waste of metallurgical silicon production for its recycling in the process of ore-thermal reduction of silica. The technology includes the stages of magnetic separation, granulation and drying. Experimental works on iron oxide separation from cyclone dust were performed using a magnetic analyzer of the AMR type (Ukraine). Granulation was carried out using a drum granulator R-020 (Russia). The chemical composition was analyzed with the help of an optical emission spectrometer Varian 730-ES (USA). It has been determined that up to 37% of iron oxide is separated by the method of magnetic separation of silicon production cyclone dust. In the laboratory pelletization in a drum granulator the granules of 10-70 mm in size with the porosity of 40-45% were obtained. The carried out experiments have showed that there is a possibility in principle to use production wastes in the production technology of silicon of metallurgical grades as a pelletized additive to the main (lump) charge. Based on the results obtained, a line for granulating dust waste was proposed.

INFLUENCE OF THE MAIN FACTORS ON THE EFFICIENCY OF WET VORTEX DUST COLLECTORS

High efficiency of intensive work of wet scrubbers is the result of simultaneous formation of different collectors - dust collectors. Under the collectors it can understand the drops of the sprayed liquid, the bubbles generated in the conditions of intense bubbling, the liquid surface and the wet surface. All collectors are formed during the operation of the circulation unit, the features of which were considered in a previous article by the same authors. This article discusses the laboratory installation to assess the impact of various factors on the efficiency of collectors. The first device consists of three chambers in which the dust separation with a varying concentration of the suspension was analyzed independently in the drop area, under bubbling conditions, as well as upon impact on the wetted surface. To estimate the fractional effectiveness a multi-stage cascade impact mechanisms was used. A significant part of the second test bench was the dust collecting chamber, which provides a cross-flow of the suspension with respect to the dust gas acting on the surface of the liquid. A number of general efficiency tests were carried out at the stand under varying conditions of the impact of the outflow of dusty air on the surface of the liquid with constant dust dosing into the system. Dust removal efficiency was evaluated by measuring the mass of dust supplied to the system compared to the dust held by the filter on the outflow pipeline. The physical model of the phenomenon was developed on the basis of the hypothesis that the efficiency of dust particles capture by wet scrubbers depends on the absorption capacity of the liquid and, therefore, is associated with the concentration of the suspension. A high concentration of a suspension may prevent the penetration of particles in the reservoirs and not disclose them to the surface for further collisions of the dust particles.

Principles of pulse-jet filters used in the woodworking industry

Principles of pulse-jet filters used in the woodworking industry. The pulse-jet filters used to separate wood dust and factors influencing their operation were described in this paper. The analysis of the possibility of the use of pulse-jet filters for wood dust separation presented in this work was based on two basic quantitative criteria. These are the separation efficiency and the pressure drop in the filtration process performed in a dust collector. The influence of wood dust type, filtration velocity and air relative humidity the separation efficiency and the pressure were described.