Filtration performance and modeling of granular bed for dust removal from coal pyrolytic vapors

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.

Design and Numerical Simulation of Dust Removal System for Sutomotive Iongitudinal Beam Plasma Cutting

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.

Effect of photovoltaic panel electric field on the wind speed required for dust removal from the panels

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.

Numerical Simulation of Dust Removal in the Cyclone Collector of a Straw Crusher Based on a Discrete Phase Model

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.

High-temperature H_2S Removal with Calcium-based Sorbent

The H2S removal characteristics of Taxada lime tinder the high temperature of 600-900℃ have been investigated. The test results indicated that this kind of sorbent almost was inert to H2S When temperature lowered down to 600℃,while its reactivity increased with increased temperature and the equilibrium conversion reached up to over 60% at temperatLlre of 900℃.However, side reactions of H2S in conjunction with high-temperature decomposition and mineral catalysis to elemental sulfur and sulfur dioxide were testified.

Reduction process and zinc removal from composite briquettes composed of dust and sludge from a steel enterprise

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.

Selective removal of As from arsenic-bearing dust rich in Pb and Sb

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.

Dust removal efficiency of high pressure atomization in underground coal mine

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.

Removal of Phosphorus from Water Using Marble Dust as Sorbent Material

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.

Experimental study of the dust-removal performance of a wet scrubber

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.

Pyrometallurgical Removal of Arsenic from Electrostatic Precipitators Dusts of Copper Smelting

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.

Structural Optimization of Dust Removal Tank of Ship Desulphurization Equipment

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.

Further Study of Electric Dust Removal with Transparent Fork Electrodes

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%.

Water film area and dust removal efficiency of string grilles:a theoretical analysis

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.

Characterization and Pyrometallurgical Removal of Arsenic from Copper Concentrate Roasting Dust

This paper describes the experimental results of removing arsenic from the dust collected in electrostatic precipitators of a fluidized bed roasting furnace (RP dust). The fluidized bed roasting process generates 600 kilotons of copper concentrate per year with 3 - 6 wt% of concentration of arsenic, producing a roasted product with a low content of arsenic below 0.3 wt%. The process generates 27 kilotons of RP dust per year with a concentration of arsenic of the order of 5 wt% and copper concentration of around 20 wt%. Subsequently, the dust collected in the electrostatic precipitators is treated by hydrometallurgical methods allowing the recovery of copper, and the disposition of arsenic as scorodite. This work proposes to use a pyrometallurgy process to the volatilization of arsenic from RP dust. The obtained material can be recirculated in copper smelting furnaces allowing the recovery of valuable metals. The set of experiments carried out in the roasting of the mixture of copper concentrate/RP dust and sulfur/RP dust used different ratios of mixtures, temperatures and roasting times. By different techniques, the characterization of the RP dust determined its size distribution, morphology, and chemical and mineralogical composition. RP dust is a composite material of small particles (<5 μm) in 50 μm agglomerates, mostly amorphous, with a complex chemical composition of sulfoxides. The results of the roasting experiments indicated that for a 75/25 weight ratio of the mixture of the copper concentrate/PR dust under 700℃, 15 minutes of roasting time with injection of air, the volatilization of arsenic reached 96% by weight. The arsenic concentration after the roasting process is less than 0.3% by weight. For a 5/95 mixture of sulfur/RP dust, at 650℃, the volatilization of arsenic reached a promissory result of 67%. Even that this study was carried out for a particular operation, the results have the potential to be extended to dust produced in the roasting of concentrates of nickel, lead-zinc, and gold.

An Automatic Dust Removal Device Based on SCM for Solar Panels

This paper introduces a set of automatic dust removal device for street lamp solar panels. The device realizes the automatic dust removal for street lamp solar panels by three steps consisting of data acquisition, automatic control and mechanical dust removal. Our scheme is as follows, according to the comparison between the actual power generation and the relatively ideal condition of power generation of solar panels, we selectively conduct dust removal operation to panels. The paper demonstrates the feasibiliW of the technology based on the example of street lamp solar panels （40w）. According to the calculation, the solar panels equipped with our device will greatly improve the power generation efficiency of solar panels, which means there will be 32 more degrees generated every year. Extension and application of the technique device will be beneficial for the improvement of solar panels power generation efficiency and the extension of the service life of the panels.

Effects of structural and operating parameters of ECP fan on dust particles removed in the transition flow regime

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.

Mechanism of micro-wetting of highly hydrophobic coal dust in underground mining and new wetting agent development

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.

Removal of sulfur in coke oven gas by mixing ZnO-based additive into coal

A new technology for recycling EAF dust and removal of sulfur from coking oven gas was investigated. The new technology does not need to set up special equipment to treat COG (coke oven gas), and it is only acquired by mixing the ZnO base additive into the coke coal. In the stage of pyrolysis of the coal volatile, ZnO of the additive combines with H 2S, CS 2, COS and C 2H 2SH of coal gas, forming ZnS in coal char. In the stage of coking of the coal char, Zn is gasified with S, then the gas Zn react with H 2S, CS 2, COS and C 2H 2SH, forming ZnS in coal gas and depositing as dust. After the collected ZnS dust was regenerated, it can be recycling as the additive again. The sulfur in coal gas can be completely removed if the mole ratio of the added Zn to the volatilized S is more than 1, and the sulfur in coke is also slightly decreased comparing with the coke without the additive. The EAF dust containing ZnO and Fe 2O 3 can be the base material of the desulfurizing additive.

The Application of Cold Banding Technology for Dust Removed From BOF Gas Using Dry Dedusting Technology

Firstly, physical and chemical properties of dust removed from BOF gas are analyzed, and then the cold banding technology of dust removed from BOF gas and its application are introduced. Tests have proved that using cooled agglomerated pellets made of the dust removed from BOF gas and small amounts of modified starch as a coolant and slagging agent in steel production can bring about considerable economic, social and environmental benefits.