To improve the poor efficiency of the dust removal system in the plasma cutting station of automotive longitudinal beams,and reduce the cutting surface quality degradation due to dust,a bottom-side suction dust remova...To improve the poor efficiency of the dust removal system in the plasma cutting station of automotive longitudinal beams,and reduce the cutting surface quality degradation due to dust,a bottom-side suction dust removal system is designed,and the dust removal effect is optimized through the setting of the following dampers and diversion plates.The result of numerical simulation indicates that the particle collection rate can reach 99.44%,and the field test also proves the effectiveness of the dust removal system,which is of guiding significance for the transformation of other similar dust removal systems.展开更多
Dust removal from pyrolytic vapors at high temperatures is an obstacle to the industrialization of the coal pyrolysis process.In this work,a granular bed with expanded perlites as filtration media was designed and int...Dust removal from pyrolytic vapors at high temperatures is an obstacle to the industrialization of the coal pyrolysis process.In this work,a granular bed with expanded perlites as filtration media was designed and integrated into a 10 t·d^(–1)coal pyrolysis facility.The testing results showed that around 97.56%dust collection efficiency was achieved.As a result,dust content in tar was significantly lowered.The pressure drop of the granular bed maintained in the range of 356 Pa to 489 Pa.The dust size in the effluent after filtration exhibited a bimodal distribution,which was attributed to the heterogeneity of the dust components.The effects of filtration bed on pyrolytic product yields were also discussed.A modified filtration model based on the macroscopic phenomenological theory was proposed to describe the performance of the granular bed.The computation results were well agreed with the experimental data.展开更多
Methods to remove dust deposits by high-speed airflow have significant potential applications,with optimal design of flow velocity being the core technology.In this paper,we discuss the wind speed required for particl...Methods to remove dust deposits by high-speed airflow have significant potential applications,with optimal design of flow velocity being the core technology.In this paper,we discuss the wind speed required for particle removal from photovoltaic(PV)panels by compressed air by analyzing the force exerted on the dust deposited on inclined photovoltaic panels,which also included different electrification mechanisms of dust while it is in contact with the PV panel.The results show that the effect of the particle charging mechanism in the electric field generated by the PV panel is greatly smaller than the effect of the Van der Waals force and gravity,but the effect of the particle charged by the contact electrification mechanism in the electrostatic field is very pronounced.The wind speed required for dust removal from the PV panel increases linearly with the PV panel electric field,so we suggest that the nighttime,when the PV electric field is relatively small,would be more appropriate time for dust removal.The above results are of great scientific importance for accurately grasping the dust distribution law and for achieving scientific removal of dust on PV panels.展开更多
The cyclone dust collector is an important subsystem of straw crushers used in agriculture.In the present study,a new type of dust collector with involute morphology is proposed to obtain better dust removal efficienc...The cyclone dust collector is an important subsystem of straw crushers used in agriculture.In the present study,a new type of dust collector with involute morphology is proposed to obtain better dust removal efficiency with respect to that of classical tangential and spiral dust collectors.A discrete phase model(DPM)method is used in synergy with a turbulence model,and the SIMPLE algorithm to simulate the flow field inside the dust collector and the related particle dynamics.It is shown that the internal flow field features a primary swirl,a secondary swirl and blockage effects.Moreover,for the involute dust collector,the tangential velocity in the initial stage and the pressure in the high-pressure area are larger than those obtained for the classical types.The dust removal efficiency is 37.11%,25.3%,and 16.37%for the involute type dust collector,the tangential type and the spiral type,respectively.展开更多
A variety of dust control methods are often applied in coal mines,among which the application of wet scrubbers has proven to be an efficient technology for the removal of dust in airstreams,rather than diluting or con...A variety of dust control methods are often applied in coal mines,among which the application of wet scrubbers has proven to be an efficient technology for the removal of dust in airstreams,rather than diluting or confining the dust.In this paper,a wet scrubber design was developed.Based on a self-designed experimental test platform,the total dust concentration,respirable dust concentration,air volume,and average pressure drops of wet scrubbers with 12,16,20,and 24 blades were measured under different water intake conditions.The results show that the different water intake levels have only minimal effects on the air volume of the wet scrubbers.However,increased water intake had improved the dust removal efficiency of the wet scrubbers with the same number of blades.The wet scrubber with 16 blades was found to have the best dust removal efficiency at a water intake level of 1.35 m^(3)/h.Its total dust and respirable dust removal efficiency reached 96.81%and 95.59%,respectively.The air volume was 200.4 m^(3)/min,and the average pressure drop was determined to be 169.4 Pa.In addition,when the wet scrubber with 16 blades was applied in a coal preparation plant in China's Shanxi Province,it was observed that the total dust concentration had fallen below 8.1 mg/m^(3),and the respirable dust concentration had fallen below 5.9 mg/m^(3).Therefore,the results obtained in this research investigation provide important references for the use of wet scrubbers to improve coal production environmental conditions.展开更多
This study is a continuation of our previous work. In this experiment, transparent tin-doped indium oxide (ITO) fork electrodes with different width and spacing were coated on the glass substrates. The used dust parti...This study is a continuation of our previous work. In this experiment, transparent tin-doped indium oxide (ITO) fork electrodes with different width and spacing were coated on the glass substrates. The used dust particle size was smaller than 180 mesh. The effects of the electrode width, the electrode spacing, voltage, frequency, waveform, and the duty ratio on the dust removal efficiency were studied. The obtained optimum conditions of dust removal were as follows: voltage was 1500 V, frequency was 15 Hz, square wave, 10% duty ratio, the electrode width was 0.5 mm, electrodes spacing was 1.3 mm. Our previous experimental results show that the dust removal efficiency would be up to 95%. But in this experiment, under the optimum conditions, the dust removal efficiency could be up to 99%.展开更多
Based onmultiphase flowtheory and capillary mechanics,the dimensionless bond number expression of the influence of string grille wire spacing on droplet spreading is derived.Taking a liquid film formed by spreading dr...Based onmultiphase flowtheory and capillary mechanics,the dimensionless bond number expression of the influence of string grille wire spacing on droplet spreading is derived.Taking a liquid film formed by spreading droplets based on Kelvin correlation,the Young-Laplace equation,and the Hagen-Poiseuille law,an equation for calculating the thickness and height of the liquid film is established with temperature,relative humidity and molar volume of liquid phase as independent variables.According to the theory of string grille filtration and dust removal,a dust removal efficiency calculation model covering the wet string grille wire group is constructed based on the liquid film thickness,height,wire diameter,water film area,and vortex shedding frequency.Finally,a theoretical analysis of the influence of water film area on the efficiency of wet string grille dust removal is carried out based on the spray pressure and the ratio of string grille wire distance to wire diameter.It is found that the effect of spray pressure on water film area and dust removal efficiency is more significant than the string grille wire distance diameter ratio.Moreover,the optimized combination of wet string grille wire distance diameter ratio 0.84,wind speed 3m/s and spray pressure 0.8 MPa is found,which could provide an important reference for engineering applications.展开更多
Background: Previously described methods for removal of tattoos are chemical, mechanical, surgical, termal and laser assited methods. Invention of the Q-switch mode, advanced the laser method, to be one of the most ef...Background: Previously described methods for removal of tattoos are chemical, mechanical, surgical, termal and laser assited methods. Invention of the Q-switch mode, advanced the laser method, to be one of the most effective methods of tattoo removal. Objective: Comparing the tattoo removal and rate of lymphatic elimination of 3 different wavelengths of Q-switched Nd-YAG laser (532nm, 1064nm, combination 532 + 1064). Methods: In this study we examined lymphatic elimination and the effect of 532 nm, 1064 nm, and the combination (532 + 1064 nm) wavelength of laser pulse for the possible lymphatic cleansing mechanism of black pigmented tattoos. This study was performed on 18 New-Zealand rabbits, black pigmented tattoos were engraved on the back and the four extremities of the animals. 532 nm wavelength of Q switched Nd: YAG laser beam was applied on the left upper and bilateral lower extremities of the rabbits. During this period, excisional skin biopsies and lymph node biopsies were performed on days 7, 14 and 21. Results: Day 21 lymph node biopsies revealed mixed type of reactive hyperplasia and intracellular pigments were markedly seen in the laser treatment group and no intracellular tattoo pigment was seen in the control group. Conclusion: The findingd of this study indicate that lymphatic elimination may be one of the significant mechanisms of tattoo removal and the application of different wavelengths of Q-switched Nd-YAG laser do not show statistically significant differences in tattoo removal.展开更多
The internal mechanism of the high hydrophobicity of the coal samples from the Pingdingshan mining area was studied through industrial,element,and surface functional group analysis.Laboratory testing and molecular dyn...The internal mechanism of the high hydrophobicity of the coal samples from the Pingdingshan mining area was studied through industrial,element,and surface functional group analysis.Laboratory testing and molecular dynamics simulations were employed to study the impact of three types of surfactants on the surface adsorption properties and wettability of highly hydrophobic bituminous coal.The results show that the surface of highly hydrophobic bituminous coal is compact,rich in inorganic minerals,and poorly wettable and that coal molecules are dominated by hydrophobic functional groups of aromatic rings and aliphatic structures.The wetting performance of surfactants as the intermediate carrier to connect coal and water molecules is largely determined by the interaction force between surfactants and coal(Fs-c)and the interaction force between surfactants and water(Fs-w),which effectively improve the wettability of modified coal dust via modifying its surface electrical properties and surface energy.A new type of wetting agent with a dust removal rate of 89%has been developed through discovery of a compound wetting agent solution with optimal wetting and settling performance.This paper provides theoretical and technical support for removing highly hydrophobic bituminous coal dust in underground mining.展开更多
In this study, composite briquettes were prepared using gravity dust and converter sludge as the main materials; these briquettes were subsequently reduced in a tube furnace at 1000-1300℃ for 5-30 min under a nitroge...In this study, composite briquettes were prepared using gravity dust and converter sludge as the main materials; these briquettes were subsequently reduced in a tube furnace at 1000-1300℃ for 5-30 min under a nitrogen atmosphere. The effects of reaction temperature, reaction time, and carbon content on the metallization and dezincification ratios of the composite briquettes were studied. The reduced com- posite briquettes were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy-dispersive spectroscopy (EDS). The results show that the gravity dust and converter sludge are combined into the composite briquettes and a reasonable combination not only improves the performance of the composite briquettes, but also leads to the reduction with no or little reductant and flux. As the re- action temperature is increased and the reaction time is extended, the metallization and dezincification ratios of the composite briquettes in- crease gradually. When the composite briquettes are roasted at 1300℃ for 30 rain, the metallization ratio and dezineification ratio reaches 91.35% and 99.25%, respectively, indicating that most of the iron oxide is reduced and the zinc is almost completely removed. The carbon content is observed to exert a lesser effect on the reduction process; as the C/O molar ratio increases, the metallization and dezincification ra- tios first increase and then decrease.展开更多
The selective removal of arsenic from arsenic-bearing dust containing Pb and Sb in alkaline solution was studied. The influence of Na OH concentration, temperature, leaching time, liquid to solid ratio, and the presen...The selective removal of arsenic from arsenic-bearing dust containing Pb and Sb in alkaline solution was studied. The influence of Na OH concentration, temperature, leaching time, liquid to solid ratio, and the presence of elemental sulfur on the dissolution of As, Sb and Pb in Na OH solution was investigated. The results indicate that the presence of elemental sulfur can effectively prevent leaching of lead and antimony from arsenic. The Sb2O3, As2O3 and Pb5(AsO4)3 OH in the raw material convert to NaSb(OH)6 and PbS in the leaching residue, while arsenic is leached out as As(Ⅲ) or As(Ⅴ) ions in the leaching solution. Arsenic leaching efficiency of 99.84% can be achieved under the optimized conditions, while 97.82% of Sb and 99.97% of Pb remain in the leach residue with the arsenic concentration of less than 0.1%. A novel route is presented for the selective removal of arsenic and potential recycle of lead and antimony from the arsenic-bearing dust leached by Na OH solutions with the addition of elemental sulfur.展开更多
To master theoretical calculation for dust removal efficiency of high pressure atomization in an underground coal mine, the corresponding atomization characteristics and dust removal efficiency were both comprehensive...To master theoretical calculation for dust removal efficiency of high pressure atomization in an underground coal mine, the corresponding atomization characteristics and dust removal efficiency were both comprehensively studied in theory by virtue of related theories of hydromechanics and aerosol.According to actual measurements of flow coefficients and atomization angles of X-type swirl nozzle,computational formula was derived for atomized particle sizes of such a nozzle in conjunction with relevant empirical equation. Moreover, a mathematical model for applying high pressure atomization to dust removal in underground coal mine was also established to deduce theoretical computation formula of fractional efficiency. Then, Matlab was adopted to portray the relation curve between fractional efficiency and influence factors. In addition, a theoretical formula was also set up for removal efficiency of respirable dust and total coal dust based on dust size and frequency distribution equations. In the end,impacts of dust characteristic parameters on various dust removal efficiencies were analyzed.展开更多
In order to meet engineering needs of Chinese underground coal mines,a new dust-collecting fan,a device of dust separated by centrifugal force in driven cyclone passageway(DCCP)was designed.In centrifugal dust removal...In order to meet engineering needs of Chinese underground coal mines,a new dust-collecting fan,a device of dust separated by centrifugal force in driven cyclone passageway(DCCP)was designed.In centrifugal dust removal section(CDRS)of DCCP,a general equation is derived from the principle of force equilibrium.According to CDRS structure parameters and fan running parameters,the general equation is simplified,and the simplest equation is calculated numerically by MATLAB.The calculation results illustrate that increasing quantity of air current is against dust removal,but it is beneficial to dust removal by increasing the radius of driven spiral blade and increasing the particle diameter of coal dust.The conclusions show that the dust-collecting structure parameters coupled with the fan running parameters is a novel optimization approach to dust-collection fan for working and heading faces,which is especially suitable for Chinese underground mines.展开更多
The removal of phosphorus from water using marble dust as sorbent material was studied by conducting batch tests, kinetic sorption model and isotherm model. The kinetic sorption model based on a pseudo equation was ap...The removal of phosphorus from water using marble dust as sorbent material was studied by conducting batch tests, kinetic sorption model and isotherm model. The kinetic sorption model based on a pseudo equation was applied to predict the rate constant of sorption. Thorough investigations to understand the mechanism of phosphorus sorption onto the marble dust using kinetic sorption models, pseudo first order and pseudo second order kinetic sorption models showed that the kinetic sorption is consistent with the second order model, from which it can be inferred that the mechanism of sorption is chemisorption. The Langmuir and Freundlich isotherm models were applied to describe the equilibrium isotherms. The results of isotherm models showed that the Langmuir isotherm agrees very well with the experimental data compare with Freundlich isotherm. Batch tests and kinetic sorption models results showed that using the marble dust as sorbent material could be remove more than 94.3% of phosphorus from water.展开更多
An enclosed cyclone passageway(ECP)dust-collecting fan is discussed.The ECP fan separates dust by centrifugal force originating from a driven spiral airflow,and its design takes the constraints of Chinese underground ...An enclosed cyclone passageway(ECP)dust-collecting fan is discussed.The ECP fan separates dust by centrifugal force originating from a driven spiral airflow,and its design takes the constraints of Chinese underground coal mines into consideration.Using the force equilibrium law,a general equation for dust removal in the centrifugal dust removal section(CDRS)of the ECP fan is deduced.This general equation is simplified using the CDRS structure and the fan operating parameters and is analysed numerically.The attractive results show that increases in the airflow rate of the fan,the structural ratio of the ECPs and the radius of the extended axis can improve the dust removal performance of the CDRS.Furthermore,the effects of the structural ratio and the radius on dust removal dominate over that of the flow rate,and the effect of the structural ratio is more significant than that of the radius.展开更多
With the rapid industrialization and urbanization,the demand for air quality management is more and more urgent.High temperature dust filtration is one important environmental management technology.Porous ceramics are...With the rapid industrialization and urbanization,the demand for air quality management is more and more urgent.High temperature dust filtration is one important environmental management technology.Porous ceramics are used as filter materials in the field of high-temperature dust filtration because of their unique advantages such as high filtration efficiency,as well as high temperature stability,particle loss resistance,corrosion resistance and durability.This paper mainly introduced several common preparation techniques of porous ceramics,including the traditional organic foam impregnation method,foaming method,in-situ combustion method,pore-forming method and other new methods such as the template method,gel injection molding method,freeze-drying method,multi-component co-precipitation method and hydrogel method.The principle,advantages and disadvantages of these preparation technologies and their research status were described.The application of these technologies in the field of high temperature dust filtration was briefly reviewed.Finally,the application prospect of the porous ceramics in the field of high temperature dust filtration was prospected.展开更多
This work describes the experimental results of pyrometallurgical removing of arsenic from the dust collected in the electrostatic copper precipitators within the gas cleaning system of a Copper Flash Smelting Furnace...This work describes the experimental results of pyrometallurgical removing of arsenic from the dust collected in the electrostatic copper precipitators within the gas cleaning system of a Copper Flash Smelting Furnace. The generation of dust in the copper smelting worldwide ranges from 2 - 15 wt% per ton of a copper concentrate. In Chile, copper smelters produce approximately 110 kt/y of dust with a concentration of arsenic between 1 and 15 wt%. The dust is a complex of metals oxides and sulfurs with copper concentrations greater than 10 wt% and relatively high silver concentrations. Since its high arsenic concentration, it is difficult to recover valuable metals through hydrometallurgical processes or by direct recirculation of the dust in a smelting furnace. Thus, the development of pyrometallurgical processes aimed at reducing the concentration of arsenic in the dust (<0.5 wt%) is the main objective of this study, giving particular attention to the production of a suitable material to be recirculated in operations of copper smelting. The work provides a detailed characterization of the dust including the Quantitative Evaluation of Minerals by Scanning Electron Microscopy (QEMSCAN), Scanning Electron Microscope-Energy Dispersive X-ray Analysis (SEM/EDS), X-Ray Diffraction (XRD), the elemental chemical analysis using Atomic Adsorption (AAS), and X-Ray Fluorescence (X-RF). By considering that arsenic volatilization requires a process of sulfidation-decomposition-oxidation, this work seeks to explore the roasting of mixtures of copper concentrate/dust, sulfur/dust, and pyrrhotite/dust. By the elemental chemical analysis of the mixture after and before the roasting process, the degree of arsenic volatilization was determined. The results indicated the effects of parameters such as roasting temperature, gas flow, gas composition, and the ratio of mixtures (concentrate/dust, sulfur/dust, or pyrrhotite/dust) on the volatilization of arsenic. According to the findings, the concentration of arsenic in the roasted Flash Smelting dust can be reduced to a relatively low level (<0.5 wt%), which allows its recirculation into an smelting process.展开更多
Switched-capacitor(SC)DC-DC converter[1]is an impor-tant alternative to inductive DC-DC converter,in terms of removing the bulky power inductor.Hence,it is widely used in low-profile,low-power applications,such as the...Switched-capacitor(SC)DC-DC converter[1]is an impor-tant alternative to inductive DC-DC converter,in terms of removing the bulky power inductor.Hence,it is widely used in low-profile,low-power applications,such as the internet of things(IoT)sensor nodes and energy harvesting[2].Mean-while,considering that capacitor has a much higher energy density than inductor,high-power applications.展开更多
With the improvement of the international community s environmental requirements, ship emissions standards are more stringent. In order to complete the exhaust gas purification work, Dafa 6DL-26 diesel engine set is u...With the improvement of the international community s environmental requirements, ship emissions standards are more stringent. In order to complete the exhaust gas purification work, Dafa 6DL-26 diesel engine set is used for simulation. Finite element multi-phase flow model and DPM model are used for numerical simulation and structural optimization of the position of dust removal tank at the desulfurization pretreatment part (Venturi segment). The results show that it can effectively optimize the flow field and reduce the power consumption of the marine diesel engine when the rightmost axis of the dust removal tank coincides with the axis of the Venturi center.展开更多
Based on the analysis results of the dust size distribution of flue gas from Baosteel's short-flow (BSSF) slag processing system and the mechanism of the wet scrubber,a wet scrubber system was designed and installe...Based on the analysis results of the dust size distribution of flue gas from Baosteel's short-flow (BSSF) slag processing system and the mechanism of the wet scrubber,a wet scrubber system was designed and installed in the No. 1 BSSF slag processing system at Baosteel. The results show that the dust removal efficiency of the previous system that had conventional water nozzles was only 69% with a liquid-gas ratio of 0.79 L/m^3 ,while the dust removal efficiency reached 94% when three sets of high-efficiency dual phase spray guns were installed inside both the flue and the chimney. For the latter system,the liquid-gas ratio was 0. 84 L/m^3 ,and the dust concentration in the cleaned emissions reduced to less than 40 mg/m^3.展开更多
基金Changchun Science and Technology Development Plan Project,Automobile Rolling Line Longitudinal Beam Cutting Process Under the Extraction and Dust Removal Process Test and Research,Project Approval No.21ST04。
文摘To improve the poor efficiency of the dust removal system in the plasma cutting station of automotive longitudinal beams,and reduce the cutting surface quality degradation due to dust,a bottom-side suction dust removal system is designed,and the dust removal effect is optimized through the setting of the following dampers and diversion plates.The result of numerical simulation indicates that the particle collection rate can reach 99.44%,and the field test also proves the effectiveness of the dust removal system,which is of guiding significance for the transformation of other similar dust removal systems.
基金financial support from the National Key Research and Development Program of China(2018YFB0605003).
文摘Dust removal from pyrolytic vapors at high temperatures is an obstacle to the industrialization of the coal pyrolysis process.In this work,a granular bed with expanded perlites as filtration media was designed and integrated into a 10 t·d^(–1)coal pyrolysis facility.The testing results showed that around 97.56%dust collection efficiency was achieved.As a result,dust content in tar was significantly lowered.The pressure drop of the granular bed maintained in the range of 356 Pa to 489 Pa.The dust size in the effluent after filtration exhibited a bimodal distribution,which was attributed to the heterogeneity of the dust components.The effects of filtration bed on pyrolytic product yields were also discussed.A modified filtration model based on the macroscopic phenomenological theory was proposed to describe the performance of the granular bed.The computation results were well agreed with the experimental data.
基金Project supported by the National Natural Science Foundation of China(Grant No.12064034)the Leading Talents Project of Science and Technology Innovation in Ningxia Hui Autonomous Region,China(Grant No.2020GKLRLX08)+1 种基金the Natural Science Foundation of Ningxia Hui Autonomous Region,China(Grant Nos.2022AAC03643 and2022AAC03117)the Major Science and Technology Project of Ningxia Hui Autonomous Region,China(Grant No.2022BDE03006)。
文摘Methods to remove dust deposits by high-speed airflow have significant potential applications,with optimal design of flow velocity being the core technology.In this paper,we discuss the wind speed required for particle removal from photovoltaic(PV)panels by compressed air by analyzing the force exerted on the dust deposited on inclined photovoltaic panels,which also included different electrification mechanisms of dust while it is in contact with the PV panel.The results show that the effect of the particle charging mechanism in the electric field generated by the PV panel is greatly smaller than the effect of the Van der Waals force and gravity,but the effect of the particle charged by the contact electrification mechanism in the electrostatic field is very pronounced.The wind speed required for dust removal from the PV panel increases linearly with the PV panel electric field,so we suggest that the nighttime,when the PV electric field is relatively small,would be more appropriate time for dust removal.The above results are of great scientific importance for accurately grasping the dust distribution law and for achieving scientific removal of dust on PV panels.
基金supported by the Independent Research Fund of the State Key Laboratory of Mining Response and Disaster Prevention and Control in Deep Coal Mines(No.SKLMRDPC20ZZ06)and the Program in the Youth Elite Support Plan in Universities of Anhui Province(No.gxyq2020013).
文摘The cyclone dust collector is an important subsystem of straw crushers used in agriculture.In the present study,a new type of dust collector with involute morphology is proposed to obtain better dust removal efficiency with respect to that of classical tangential and spiral dust collectors.A discrete phase model(DPM)method is used in synergy with a turbulence model,and the SIMPLE algorithm to simulate the flow field inside the dust collector and the related particle dynamics.It is shown that the internal flow field features a primary swirl,a secondary swirl and blockage effects.Moreover,for the involute dust collector,the tangential velocity in the initial stage and the pressure in the high-pressure area are larger than those obtained for the classical types.The dust removal efficiency is 37.11%,25.3%,and 16.37%for the involute type dust collector,the tangential type and the spiral type,respectively.
基金supported by the Shanxi Province Colleges and Universities Science and Technology Achievement Transformation and Cultivation Project(2020CG008).
文摘A variety of dust control methods are often applied in coal mines,among which the application of wet scrubbers has proven to be an efficient technology for the removal of dust in airstreams,rather than diluting or confining the dust.In this paper,a wet scrubber design was developed.Based on a self-designed experimental test platform,the total dust concentration,respirable dust concentration,air volume,and average pressure drops of wet scrubbers with 12,16,20,and 24 blades were measured under different water intake conditions.The results show that the different water intake levels have only minimal effects on the air volume of the wet scrubbers.However,increased water intake had improved the dust removal efficiency of the wet scrubbers with the same number of blades.The wet scrubber with 16 blades was found to have the best dust removal efficiency at a water intake level of 1.35 m^(3)/h.Its total dust and respirable dust removal efficiency reached 96.81%and 95.59%,respectively.The air volume was 200.4 m^(3)/min,and the average pressure drop was determined to be 169.4 Pa.In addition,when the wet scrubber with 16 blades was applied in a coal preparation plant in China's Shanxi Province,it was observed that the total dust concentration had fallen below 8.1 mg/m^(3),and the respirable dust concentration had fallen below 5.9 mg/m^(3).Therefore,the results obtained in this research investigation provide important references for the use of wet scrubbers to improve coal production environmental conditions.
文摘This study is a continuation of our previous work. In this experiment, transparent tin-doped indium oxide (ITO) fork electrodes with different width and spacing were coated on the glass substrates. The used dust particle size was smaller than 180 mesh. The effects of the electrode width, the electrode spacing, voltage, frequency, waveform, and the duty ratio on the dust removal efficiency were studied. The obtained optimum conditions of dust removal were as follows: voltage was 1500 V, frequency was 15 Hz, square wave, 10% duty ratio, the electrode width was 0.5 mm, electrodes spacing was 1.3 mm. Our previous experimental results show that the dust removal efficiency would be up to 95%. But in this experiment, under the optimum conditions, the dust removal efficiency could be up to 99%.
基金We thank Esther Posner,PhD,from Edanz Group China(www.liwenbianji.cn/ac)for English language editing on an earlier draft of this manuscript.This work was supported by the 2017 Hunan Provincial Graduate Research Innovation Project of China(No.CX2017B649)the National Natural Science Foundation of China(No.51774134)+2 种基金the Excellent Youth Project of Hunan Provincial Department of Education(No.19B223)the Hunan Provincial Natural Science Foundation of China(No.2019JJ60044)the Hunan Provincial Natural Science Foundation of China(No.2018JJ64028).
文摘Based onmultiphase flowtheory and capillary mechanics,the dimensionless bond number expression of the influence of string grille wire spacing on droplet spreading is derived.Taking a liquid film formed by spreading droplets based on Kelvin correlation,the Young-Laplace equation,and the Hagen-Poiseuille law,an equation for calculating the thickness and height of the liquid film is established with temperature,relative humidity and molar volume of liquid phase as independent variables.According to the theory of string grille filtration and dust removal,a dust removal efficiency calculation model covering the wet string grille wire group is constructed based on the liquid film thickness,height,wire diameter,water film area,and vortex shedding frequency.Finally,a theoretical analysis of the influence of water film area on the efficiency of wet string grille dust removal is carried out based on the spray pressure and the ratio of string grille wire distance to wire diameter.It is found that the effect of spray pressure on water film area and dust removal efficiency is more significant than the string grille wire distance diameter ratio.Moreover,the optimized combination of wet string grille wire distance diameter ratio 0.84,wind speed 3m/s and spray pressure 0.8 MPa is found,which could provide an important reference for engineering applications.
文摘Background: Previously described methods for removal of tattoos are chemical, mechanical, surgical, termal and laser assited methods. Invention of the Q-switch mode, advanced the laser method, to be one of the most effective methods of tattoo removal. Objective: Comparing the tattoo removal and rate of lymphatic elimination of 3 different wavelengths of Q-switched Nd-YAG laser (532nm, 1064nm, combination 532 + 1064). Methods: In this study we examined lymphatic elimination and the effect of 532 nm, 1064 nm, and the combination (532 + 1064 nm) wavelength of laser pulse for the possible lymphatic cleansing mechanism of black pigmented tattoos. This study was performed on 18 New-Zealand rabbits, black pigmented tattoos were engraved on the back and the four extremities of the animals. 532 nm wavelength of Q switched Nd: YAG laser beam was applied on the left upper and bilateral lower extremities of the rabbits. During this period, excisional skin biopsies and lymph node biopsies were performed on days 7, 14 and 21. Results: Day 21 lymph node biopsies revealed mixed type of reactive hyperplasia and intracellular pigments were markedly seen in the laser treatment group and no intracellular tattoo pigment was seen in the control group. Conclusion: The findingd of this study indicate that lymphatic elimination may be one of the significant mechanisms of tattoo removal and the application of different wavelengths of Q-switched Nd-YAG laser do not show statistically significant differences in tattoo removal.
文摘The internal mechanism of the high hydrophobicity of the coal samples from the Pingdingshan mining area was studied through industrial,element,and surface functional group analysis.Laboratory testing and molecular dynamics simulations were employed to study the impact of three types of surfactants on the surface adsorption properties and wettability of highly hydrophobic bituminous coal.The results show that the surface of highly hydrophobic bituminous coal is compact,rich in inorganic minerals,and poorly wettable and that coal molecules are dominated by hydrophobic functional groups of aromatic rings and aliphatic structures.The wetting performance of surfactants as the intermediate carrier to connect coal and water molecules is largely determined by the interaction force between surfactants and coal(Fs-c)and the interaction force between surfactants and water(Fs-w),which effectively improve the wettability of modified coal dust via modifying its surface electrical properties and surface energy.A new type of wetting agent with a dust removal rate of 89%has been developed through discovery of a compound wetting agent solution with optimal wetting and settling performance.This paper provides theoretical and technical support for removing highly hydrophobic bituminous coal dust in underground mining.
基金financially supported by the National Natural Science Foundation of China(No.U1260202)the National Basic Research Priorities Program of China(No.2012CB720401)the State Key Laboratory of Solid Waste Reuse for Building Materials
文摘In this study, composite briquettes were prepared using gravity dust and converter sludge as the main materials; these briquettes were subsequently reduced in a tube furnace at 1000-1300℃ for 5-30 min under a nitrogen atmosphere. The effects of reaction temperature, reaction time, and carbon content on the metallization and dezincification ratios of the composite briquettes were studied. The reduced com- posite briquettes were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy-dispersive spectroscopy (EDS). The results show that the gravity dust and converter sludge are combined into the composite briquettes and a reasonable combination not only improves the performance of the composite briquettes, but also leads to the reduction with no or little reductant and flux. As the re- action temperature is increased and the reaction time is extended, the metallization and dezincification ratios of the composite briquettes in- crease gradually. When the composite briquettes are roasted at 1300℃ for 30 rain, the metallization ratio and dezineification ratio reaches 91.35% and 99.25%, respectively, indicating that most of the iron oxide is reduced and the zinc is almost completely removed. The carbon content is observed to exert a lesser effect on the reduction process; as the C/O molar ratio increases, the metallization and dezincification ra- tios first increase and then decrease.
基金Project(51604303) supported by the National Natural Science Foundation of ChinaProject(2019JJ20031) supported by the Hunan Natural Science Fund for Distinguished Young Scholar,China
文摘The selective removal of arsenic from arsenic-bearing dust containing Pb and Sb in alkaline solution was studied. The influence of Na OH concentration, temperature, leaching time, liquid to solid ratio, and the presence of elemental sulfur on the dissolution of As, Sb and Pb in Na OH solution was investigated. The results indicate that the presence of elemental sulfur can effectively prevent leaching of lead and antimony from arsenic. The Sb2O3, As2O3 and Pb5(AsO4)3 OH in the raw material convert to NaSb(OH)6 and PbS in the leaching residue, while arsenic is leached out as As(Ⅲ) or As(Ⅴ) ions in the leaching solution. Arsenic leaching efficiency of 99.84% can be achieved under the optimized conditions, while 97.82% of Sb and 99.97% of Pb remain in the leach residue with the arsenic concentration of less than 0.1%. A novel route is presented for the selective removal of arsenic and potential recycle of lead and antimony from the arsenic-bearing dust leached by Na OH solutions with the addition of elemental sulfur.
基金Financial provided by the National Natural Science Foundation of China (Nos. 51574123 and U1361118)the China Postdoctoral Science Foundation (No. 2015M 582118)
文摘To master theoretical calculation for dust removal efficiency of high pressure atomization in an underground coal mine, the corresponding atomization characteristics and dust removal efficiency were both comprehensively studied in theory by virtue of related theories of hydromechanics and aerosol.According to actual measurements of flow coefficients and atomization angles of X-type swirl nozzle,computational formula was derived for atomized particle sizes of such a nozzle in conjunction with relevant empirical equation. Moreover, a mathematical model for applying high pressure atomization to dust removal in underground coal mine was also established to deduce theoretical computation formula of fractional efficiency. Then, Matlab was adopted to portray the relation curve between fractional efficiency and influence factors. In addition, a theoretical formula was also set up for removal efficiency of respirable dust and total coal dust based on dust size and frequency distribution equations. In the end,impacts of dust characteristic parameters on various dust removal efficiencies were analyzed.
基金supported by the National Natural Science Foundation of China and Shenhua Group Corpo-ration Limited(U1361118)the Hunan Provincial Natural Science Foundation of China(13JJ8016)+2 种基金the State Key Laboratory for GeoMechanics and Deep Underground Engineering(SKLG-DUEK1018)the Open Research Fund Program of Hunan Province Key Laboratory of Safe Mining Techniques of Coal Mines(Hunan University of Science and Technology)(201105)the Project of Outstanding(Postgraduate)Dissertation Growth Foundation of HNUST(SNY005).
文摘In order to meet engineering needs of Chinese underground coal mines,a new dust-collecting fan,a device of dust separated by centrifugal force in driven cyclone passageway(DCCP)was designed.In centrifugal dust removal section(CDRS)of DCCP,a general equation is derived from the principle of force equilibrium.According to CDRS structure parameters and fan running parameters,the general equation is simplified,and the simplest equation is calculated numerically by MATLAB.The calculation results illustrate that increasing quantity of air current is against dust removal,but it is beneficial to dust removal by increasing the radius of driven spiral blade and increasing the particle diameter of coal dust.The conclusions show that the dust-collecting structure parameters coupled with the fan running parameters is a novel optimization approach to dust-collection fan for working and heading faces,which is especially suitable for Chinese underground mines.
文摘The removal of phosphorus from water using marble dust as sorbent material was studied by conducting batch tests, kinetic sorption model and isotherm model. The kinetic sorption model based on a pseudo equation was applied to predict the rate constant of sorption. Thorough investigations to understand the mechanism of phosphorus sorption onto the marble dust using kinetic sorption models, pseudo first order and pseudo second order kinetic sorption models showed that the kinetic sorption is consistent with the second order model, from which it can be inferred that the mechanism of sorption is chemisorption. The Langmuir and Freundlich isotherm models were applied to describe the equilibrium isotherms. The results of isotherm models showed that the Langmuir isotherm agrees very well with the experimental data compare with Freundlich isotherm. Batch tests and kinetic sorption models results showed that using the marble dust as sorbent material could be remove more than 94.3% of phosphorus from water.
基金supported by the Natural Science Foundation of China and Shenhua Group Corporation Limited(U1361118)the Hunan Provincial Natural Science Foundation of China(13JJ8016,2015JJ2061)+1 种基金the State Key Laboratory for Geomechanics and Deep Underground Engineering(SKLGDUEK1018)the Project of Scientific Research Fund of Hunan Provincial Education Department(Nos.12C1099,14C0425).
文摘An enclosed cyclone passageway(ECP)dust-collecting fan is discussed.The ECP fan separates dust by centrifugal force originating from a driven spiral airflow,and its design takes the constraints of Chinese underground coal mines into consideration.Using the force equilibrium law,a general equation for dust removal in the centrifugal dust removal section(CDRS)of the ECP fan is deduced.This general equation is simplified using the CDRS structure and the fan operating parameters and is analysed numerically.The attractive results show that increases in the airflow rate of the fan,the structural ratio of the ECPs and the radius of the extended axis can improve the dust removal performance of the CDRS.Furthermore,the effects of the structural ratio and the radius on dust removal dominate over that of the flow rate,and the effect of the structural ratio is more significant than that of the radius.
文摘With the rapid industrialization and urbanization,the demand for air quality management is more and more urgent.High temperature dust filtration is one important environmental management technology.Porous ceramics are used as filter materials in the field of high-temperature dust filtration because of their unique advantages such as high filtration efficiency,as well as high temperature stability,particle loss resistance,corrosion resistance and durability.This paper mainly introduced several common preparation techniques of porous ceramics,including the traditional organic foam impregnation method,foaming method,in-situ combustion method,pore-forming method and other new methods such as the template method,gel injection molding method,freeze-drying method,multi-component co-precipitation method and hydrogel method.The principle,advantages and disadvantages of these preparation technologies and their research status were described.The application of these technologies in the field of high temperature dust filtration was briefly reviewed.Finally,the application prospect of the porous ceramics in the field of high temperature dust filtration was prospected.
文摘This work describes the experimental results of pyrometallurgical removing of arsenic from the dust collected in the electrostatic copper precipitators within the gas cleaning system of a Copper Flash Smelting Furnace. The generation of dust in the copper smelting worldwide ranges from 2 - 15 wt% per ton of a copper concentrate. In Chile, copper smelters produce approximately 110 kt/y of dust with a concentration of arsenic between 1 and 15 wt%. The dust is a complex of metals oxides and sulfurs with copper concentrations greater than 10 wt% and relatively high silver concentrations. Since its high arsenic concentration, it is difficult to recover valuable metals through hydrometallurgical processes or by direct recirculation of the dust in a smelting furnace. Thus, the development of pyrometallurgical processes aimed at reducing the concentration of arsenic in the dust (<0.5 wt%) is the main objective of this study, giving particular attention to the production of a suitable material to be recirculated in operations of copper smelting. The work provides a detailed characterization of the dust including the Quantitative Evaluation of Minerals by Scanning Electron Microscopy (QEMSCAN), Scanning Electron Microscope-Energy Dispersive X-ray Analysis (SEM/EDS), X-Ray Diffraction (XRD), the elemental chemical analysis using Atomic Adsorption (AAS), and X-Ray Fluorescence (X-RF). By considering that arsenic volatilization requires a process of sulfidation-decomposition-oxidation, this work seeks to explore the roasting of mixtures of copper concentrate/dust, sulfur/dust, and pyrrhotite/dust. By the elemental chemical analysis of the mixture after and before the roasting process, the degree of arsenic volatilization was determined. The results indicated the effects of parameters such as roasting temperature, gas flow, gas composition, and the ratio of mixtures (concentrate/dust, sulfur/dust, or pyrrhotite/dust) on the volatilization of arsenic. According to the findings, the concentration of arsenic in the roasted Flash Smelting dust can be reduced to a relatively low level (<0.5 wt%), which allows its recirculation into an smelting process.
基金This work is supported by the Macao Science and Technology Development Fund(FDCT)under Grant 0041/2022/A1by the Research Committee of University of Macao under Grant MYRG2022-00004-IME.
文摘Switched-capacitor(SC)DC-DC converter[1]is an impor-tant alternative to inductive DC-DC converter,in terms of removing the bulky power inductor.Hence,it is widely used in low-profile,low-power applications,such as the internet of things(IoT)sensor nodes and energy harvesting[2].Mean-while,considering that capacitor has a much higher energy density than inductor,high-power applications.
文摘With the improvement of the international community s environmental requirements, ship emissions standards are more stringent. In order to complete the exhaust gas purification work, Dafa 6DL-26 diesel engine set is used for simulation. Finite element multi-phase flow model and DPM model are used for numerical simulation and structural optimization of the position of dust removal tank at the desulfurization pretreatment part (Venturi segment). The results show that it can effectively optimize the flow field and reduce the power consumption of the marine diesel engine when the rightmost axis of the dust removal tank coincides with the axis of the Venturi center.
文摘Based on the analysis results of the dust size distribution of flue gas from Baosteel's short-flow (BSSF) slag processing system and the mechanism of the wet scrubber,a wet scrubber system was designed and installed in the No. 1 BSSF slag processing system at Baosteel. The results show that the dust removal efficiency of the previous system that had conventional water nozzles was only 69% with a liquid-gas ratio of 0.79 L/m^3 ,while the dust removal efficiency reached 94% when three sets of high-efficiency dual phase spray guns were installed inside both the flue and the chimney. For the latter system,the liquid-gas ratio was 0. 84 L/m^3 ,and the dust concentration in the cleaned emissions reduced to less than 40 mg/m^3.