• Particle and aerosol research
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• v.11 no.2
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• pp.37-46
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• 2015

Dust particles, which inflow to the subway mechanical ventilation and air conditioning(MVAC) chamber, contain a fair amount of iron compounds, approximately 25.2w/w%. This work attempted to capture those iron containing dust using magnetic filters. Average magnetization value of the test MVAC dust was 0.012 emu on 5,000 Oe, which could correspond sufficiently with the magnetic interaction. External permanent magnets provided with magnetization of iron mesh screen showing high gradient magnetic field(HGM). It resulted in the capture efficiency with 84.0 ~ 99.7% and 81.2 ~ 99.8% for $PM_{10}$ and $PM_{2.5}$ respectively. Magnetic capture was found to be closely associated with the magnetic intensity, mesh opening size and flow velocity.

• 한국전산유체공학회:학술대회논문집
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• 2011.05a
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• pp.508-511
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• 2011

Dust released from the rotating timber cutting process causes various kinds of diseases as well as safety issues. Although there were lots of efforts to reduce the amount of dust by installing large-sized dust collectors or by using expensive high-quality cutters, they proved to be not so effective. In this study we want to modify and improve the design of the rotary cutter system to prevent dust from being released to the environment as possible by using computational fluid dynamics (CFD) analysis. We have developed CFD models of the conventional cutter and several design modifications. Through the CFD analysis the characteristics of the air flow was predicted, and then the behavior of dust produced during the cutting process was analyzed for different designs. The most efficient design feature to capture dust inside the cutter as much as possible was chosen based on the CFD analysis results. Finally the prototype of the ratary saw machine was constructed and tested to check the dust capturing efficiency, which result is reasonably consistent with the predicted performance through the CFD analysis.

• Safety and Health at Work
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• v.8 no.3
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• pp.296-305
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• 2017

Background: Surfactant-containing water sprays are commonly used in coal mines to collect dust. This study investigates the dust collection performance of different surfactant types for a range of coal dust particle sizes and charges. Methods: Bituminous coal dust aerosol was generated in a wind tunnel. The charge of the aerosol was either left unaltered, charge-neutralized with a neutralizer, or positively- or negatively-charged using a diffusion charger after the particles were neutralized. An anionic, cationic, or nonionic surfactant spray or a plain water spray was used to remove the particles from the air flow. Some particles were captured while passing through spray section, whereas remaining particles were charge-separated using an electrostatic classifier. Particle size and concentration of the charge-separated particles were measured using an aerodynamic particle sizer. Measurements were made with the spray on and off to calculate overall collection efficiencies (integrated across all charge levels) and efficiencies of particles with specific charge levels. Results: The diameter of the tested coal dust aerosol was $0.89{\mu}m{\pm}1.45$ [geometric $mean{\pm}geometric$ standard deviations (SD)]. Respirable particle mass was collected with $75.5{\pm}5.9%$ ($mean{\pm}SD$) efficiency overall. Collection efficiency was correlated with particle size. Surfactant type significantly impacted collection efficiency: charged particle collection by nonionic surfactant sprays was greater than or equal to collection by other sprays, especially for weakly-charged aerosols. Particle charge strength was significantly correlated with collection efficiency. Conclusion: Surfactant type affects charged particle spray collection efficiency. Nonionic surfactant sprays performed well in coal dust capture in many of the tested conditions.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.21 no.5
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• pp.40-45
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• 2022

In recent years, indoor air pollution has become a crucial environmental problem. Hence, the purification of indoor air is an important issue. Typical physical filters show relatively high dust collection efficiency at a dust particle size of more than 5.0 ㎛ but extremely low efficiency at an ultrafine size of less than 2.5 ㎛. In this study, an electric field filter was proposed to capture ultrafine dust with a size of less than 5.0 ㎛. Simulation results showed that the electric field filter effectively removed ultrafine dust. In addition, sufficient dust collection efficiency was obtained even with a simple plate-shaped filter without bending the Chevron filter.

• Journal of the Korean Society of Safety
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• v.23 no.2
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• pp.1-6
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• 2008

The present study investigates on improvement of inhalation efficiency of hood in ventilation system for elimination of industrial dust. The hood, one of local exhaust ventilation system, has an important function to inhale a pollution source such as harmful dust and industrial waste. In this study, in order to improve the inhalation efficiency of the industrial hood, a new device named "gas-guide-device" was attached to inside of hood. The thermal fluid commercial code "Phoenics ver 3.1" was used to analyze the flow velocity distribution at the hood inlet and around the hood after gas-guide-device was installed. And the flow velocity on each position inside and around the hood was actually measured using the hot wire type anemometer under the same condition as that of numerical analysis. Also, in order to identify the optimum shape of gas-guide-device, numerical analysis and experiments are performed under various conditions and their results are presented. The results of this study revealed that the hood attached with gas-guide-device was higher the inhalation efficiency than that for without one and can be possible to improve the capture velocity of the industrial dust. And the optimum shape of gas-guide-device was identified that the ratio of two sizes of gas-guide-device, X to Y, has 4 to 6 on the basis of the hood size in use and the width (b) of gas-guide-device.

• Applied Chemistry for Engineering
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• v.26 no.2
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• pp.229-233
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• 2015

In this study, we examined the removal characteristics of suspended particulate matters which are one of carcinogens to cause lung cancer. The fine dust capture by a pilot scale filtration system depends on several important variables such as humidity, initial fine dust injection volume, and flow rate. The average concentration of particulate matters in the test chamber decreased, but the ultimate collection efficiency did not change during the filtration under high humidity, compared to those of using ambient conditions The initial injection amount of fine dust did not influence the particle capturing efficiency. When the flow rate reduced from 0.6 m/s to 0.3 m/s, the dust collection time increased approximately 1.4 times. Among all variables tested, the flow rate showed the most significant effect on the removal efficiency of fine particulate matter.

• Journal of Korean Society for Atmospheric Environment
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• v.31 no.2
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• pp.118-130
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• 2015

Fine dust containing iron compounds is of current interests in metro subway as well as large scale industries including iron manufacturing and smelting works. This work attempts to find a new design of magnetic filter module for iron dust capture. It simulated the vertical rectangular duct with metal mesh which might promote electric fields in the duct space. A lab test using coal fly ash composed of 8.66% Fe with the most form of $Fe_3O_4$ and $Fe_2O_3$ showed capability of magnetic collection. It showed the capture efficiency with 80~93% for $PM_{2.5}$ depending on magnetic intensity. Ferromagnetic wire mesh contributed up to 50% of collection increment.

• Journal of Korean Society for Atmospheric Environment
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• v.15 no.2
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• pp.201-210
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• 1999

Cyclones have been extensively used in the industry for removing fine particles from the gaseous streams, based on simplicity in design and construction in association with low cost and flexibility to operate in extreme and harsh environments. However, industrial cyclones are typically not very efficient for particles smaller than 10μm. In this work, in order to improve the separation efficiency of reverse flow cyclones, a simple device named Post Cyclone(Poc) in installed on the top of an existing cyclone. Thereby the residual swirl present at the outlet (vortex finder) of a conventional cyclone has been used to capture the escaped dust from the cyclone in the PoC. The performance of PoC was closely evaluated by changing configuration of the PoC and operation condition. In addition, the dust behaviour in th PoC was investigated based on the hypothesis of residual vortex.

• Journal of the Korean Society of Marine Environment & Safety
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• v.26 no.6
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• pp.706-714
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• 2020

Currently, 90 % of the world's population breathes air with a fine dust content exceeding the World Health Organization's annual average exposure limit (10 ㎍/㎥). Global efforts have been devoted toward reducing secondary pollutants and ultra-fine dust through regulations on nitrogen oxides released over land and sea. Domestic efforts have also aimed at creating clean marine environments by reducing sulfur emissions, which are the primary cause of dust accumulation in ships, through developing and distributing environment-friendly ships. Among the technologies for reducing harmful emissions from diesel engines, electrostatic precipitator offer several advantages such as a low pressure loss, high dust collection efficiency, and NOx removal and maintenance. This study aims to increase the durability of a ship by improving equipment quality through failure mode effects analysis for the preventive maintenance of an electrostatic precipitator that was developed for reducing fine dust particles emitted from the 2,427 kW marine diesel engines in ships with a gross tonnage of 999 tons. With regard to risk priority, failure mode 241 (poor dust capture efficiency) was the highest, with an RPN of 180. It was necessary to determine the high-risk failure mode in the collecting electrode and manage it intensively. This was caused by clearance defects, owing to vibrations and consequent pin loosening. Given that pin loosening is mainly caused by vibrations generated in the hull or equipment, it is necessary to manage the position of pin loosening.

• Journal of the Korean Applied Science and Technology
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• v.31 no.1
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• pp.59-65
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• 2014

Indoor air quality including metro subway is of recent interests in large cities. Inflow air to the inside of the train and circulating air flow through MVAC of stations contain large amount of iron based fine particles. This paper evaluated the collection of such a dust by magnetic filters as comparing to conventional particle capturing mechanisms such as inertia, direct impaction and diffusion. It was found that filtration velocity, magnetic field intensity, and fiber size were the most important parameters for magnetic filtration. Application of magnetic force obviously enhances the collection efficiency particularly in fine modes smaller than 10 mm. However, its effect was found greater in 2.5 mm than submicron particles.