• Journal of Korean Society of Environmental Engineers
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• v.39 no.11
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• pp.626-633
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• 2017

The present study investigated the effect of a water-washing process, which is part of the acid hydrometallurgical process for recovery of high purity of zinc, on the removal of alkali metals and chlorides (Na, K, Ca, Cl) from Electric arc furnace dust (EAFD). Two EAFD samples with different properties were characterized by particle size, XRD and element analysis, and their washing efficiencies (%) on alkali metals and chlorides were compared according to pH, washing time, liquid to solid (L/S) ratio and number of washings. The results show that the alkali metals and chlorides could be effectively removed by the washing (at L/S ration of 3 for more than 30 min., pH 10~11) while minimizing loss of zinc (<0.1%), in which the washing efficiency was Na-78%, K-76%, Cl >99%, respectively. Na and K could be removed up to 97% and 89% respectively by 3 times of repeated washings. With increased sample volume (10 times) of the mixed (1:1, w/w) sample with two types of EAFD, it was confirmed that the pH(10~11) can be used as the main process control parameter for the washing of the alkali metals regardless of EAFD properties.

• Journal of Korean Society for Atmospheric Environment
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• v.31 no.1
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• pp.54-62
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• 2015

Small scale paint overspray booths are being operated nationwidely, for repair of passenger car body parts. paint aerosols are emitted from the paint overspray booth in operations. In paint overspray booth operations without ventilation system and air pollutants collection unit, it may land on nearby equipment. In this study a removal of sticky paint aerosol for application of the small-scale overspray paint booth. it's cause the surface of filter bag from generated sticky paint aerosol. To remove adhesion of paint aerosol the agglomerating agents are injected and mixed with sticky paint aerosols prior to reach the filter bag. The paint spray rate was set as $10{\pm}5g/min$ from air-atomized spray guns in the spray booth, injection rate of agglomerating was $10{\pm}5g/min$ in the mixing chamber. The filtration velocity including air pollutants varied from 0.2 m/min to 0.4 m/min. Bag cleaning air pressure was set as $5.0kg_f/min$ for detaching dust cake from surface of filter bag. Bag cleaning interval at the filtration velocity of 0.2 m/min was around 3 times longer than that of the 0.4 m/min. The residual pressure drop maintained highest value at the highest filtration velocity. Fractional efficiency of 99.952%~99.971% was possible to maintain for the particle size of 2.5 microns. Total collection efficiency at the filtration velocity of 0.2 m/min was 99.42%. During this study we could confirm high collection efficiency and long cleaning intervals for the test with filtration velocity of 0.2 m/min indicating an optimal value for the given dimensions of the test unit and test operating conditions.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.2
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• pp.983-989
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• 2013

The current research reviewed the design conditions that would maximize the efficiency of the hybrid collector that combines in one unit "cyclone-inertial impaction-bag filter". The computational analysis for the shape of cyclone entry predicts that a design that installs the guide vane at the entry of the tangential type cyclone brings a high-rpm and powerful vortex, very effective in promoting the deflection of coarse particles from the streamline at the cyclone. As the lower part of the cyclone is venturi-shaped, however, a strong flow downward of 4 to 5 m/sec persists through the lower part of the hopper, revealing the likely reentrainment of collected dust. And the removal of the venturi at the lower part of the cyclone would solve the problem of the reentrainment of collected dust. The acceleration of the flow velocity through the adjustment of the gap of the collision baffle would increase the effect of collision, but as the interference with the dust separation is expected, the original design should be kept for the baffle.

• Journal of Korean Society for Atmospheric Environment
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• v.24 no.4
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• pp.483-491
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• 2008

The filtration characteristics of $CYBAGFILTER^{(R)}$ unit with pleated filter bags were evaluated by comparing the performance of the unit with the lower part of cyclone shape with that of the unit with conventional lower part. Results from the test were also compared with those from the previous research with the $CYBAGFILTER^{(R)}$ in which round filter bags were installed. $CYBAGFILTER^{(R)}$ is the unit which combines the centrifugal separation mechanism and the fabric filtration mechanism in a single unit for efficient removal of particulate matters. The pleated filter bags are made of pleated fabric with an extension of the filtration area about 3 times compared with the conventional round filter bags. The results from the test using pleated filter bags showed an overall collection efficiency of over 99.9% regardless of the shape of lower part installed. When the lower part of cyclone shape was installed, the filter cleaning interval was over 2 times longer compared with that when the conventional lower part was installed. At the same conditions of filtration velocity and filter pressure drop, the $CYBAGFILTER^{(R)}$ with the lower part of cyclone shape, in which the pleated filter bags are installed, can be operated with a flow rate of round 3 times higher than that with conventional round filter bags.

• Clean Technology
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• v.24 no.4
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• pp.301-306
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• 2018

Recently, due to the increase in the fine dust, regulations on PM generated from diesel cars are strengthened. There is a growing interest in diesel particulate filters (DPFs), a post-treatment device that removes exhaust gases from diesel vehicles. Therefore, one of the enhancements of the DPF efficiency is to reduce the pressure drop in the DPF, thereby increasing the efficiency of the filter and regeneration. In this study, the effect of cell density, channel shape, wall thickness, and inlet channel ratio of 5.66" SiC and Cordierite DPF on the pressure drop in DPF was investigated using ANSYS FLUENT simulator. As a result of the experiment, the pressure drop was smaller at 300 CPSI than 200 CPSI, and the anisotropy and O / S cell showed less than Isotropy by pressure drop of about 1,000 Pa. As the porosity increased by 10% the pressure drop was reduced by about 300 Pa and as the wall thickness increased by 0.05 mm, the pressure drop was increased by about 500 Pa.

• Journal of Animal Environmental Science
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• v.16 no.1
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• pp.21-28
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• 2010

The odor problem in the livestock is increasing by 7% annually. Most importantly, the livestock odor problem in swinery accounts for the maximum ratio (54%). In this study, we reviewed the possibility of deodorizing swinery using an odor reduction device that can be used with the water washing system. First, the study confirmed that the solubility of odor gas, which was hydrogen sulfide, was very low regardless of the contact time with solvent, but the solubility of methyl mercaptan was found to increase along with the increase in time. The solubility of other odor gases, such as dimethyl sulfide, dimethyl disulfide and ammonia, was considerably high. Consequently, it is considered that if the odor reduction device for the water washing system deodorization is used in a swinery, the time during which the exhaust gas is in contact with usable water must be extended, or solvent quantity must be expanded. However, it is predicted that although hydrogen sulfide is easily generated in the anaerobic condition, it is difficult to expect high odor reduction efficiency because this gas has low solubility in water, especially in case it is used in the deodorization of the water washing system. The result of the solubility experiment using the bench-scale device practically manufactured represented the higher odor reduction ratio than expected. This result was possible because the removal efficiency of dust particles could be reached up to 93%. Therefore, it is judged that also the odor gas absorbed on dust particles could be removed by removal of dust. Consequently, it is expected that the higher order reduction ratio will be possible by structural improvement for increasing contact with water and odor gas.

• Explosives and Blasting
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• v.39 no.3
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• pp.15-23
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• 2021

Ventilation shafts are pathways in mines and tunnels for the removal of dust or smoke during underground space construction and operation. In mines, blasting with long blast holes is preferred for the excavation of a ventilation shaft in the 10~20m long crown pillar section. In this case, the bottom part of the blast hole is completely drilled in order to determine the drilling error, and this causes a problem of lowering the explosive charge and blasting efficiency. It is possible to solve the problem of explosive loading and to increase the blast efficiency by covering the curb of the blasthole by using stemming material. In this study, simulations for the blasting of a ventilation shaft were performed with various stemming lengths and the blasthole diameters(45, 76mm) using AUTODYN 2D SPH(Smooth particle hydrodynamics) analysis technique. Also the optimal bottom stemming column was derived by checking the size of the boulder and burden line according to blasting. Analysis result, blasting efficiency is lessened in case of stemming length less than 30cm and the optimal length of the stemming material should be 30cm or higher to achieve high efficiency of blasting.

• Journal of Environmental Science International
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• v.17 no.10
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• pp.1121-1127
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• 2008

The free-living amoeba and Acanthamoeba sp. are widely distributed in fresh water, soil, air and dust in the world. We studied distribution of amoeba from low Nakdong River(Mulgum and Maeri) and removal efficiency in water treatment process of Busan metropolitan city. During this investigation, water quality showed pH $7.4{\sim}9.6({\pm}1.1)$, water temperature $2.0{\sim}29.0({\pm}17)^{\circ}C$, turbidity $4.8{\sim}27.4({\pm}11.0)$ NTU, chlorophyll-a $10.3{\sim}109.0({\pm}44.3)\;mg/m^{3}$, BOD $1.7\sim4.9({\pm}2.6)$ mg/L, COD $3.1\sim-6.9({\pm}5.0)$ mg/L and total coliform $17\sim920({\pm}200.5)$ MPN/100 mL. The free-living amoeba were detected highly than Acanthamoeba sp., 11 out of 22 in raw water samples were positive (50%) for Acanthamoeba sp. from February 2005 to December 2005. The seasonal characteristics of tree-living amoeba and Acanthamoeba sp. in raw water were mainly distributed through the spring to the early fall. When tree-living amoeba and Acanthamoeba sp. were passed through the water treatment of pilot-plant, approximately 80% was sure to be removed through pre-ozonation, sedimentation, send filtration. 100% was removed after post-ozonation process. All of the isolated amoebas from Nakdong River were Acanthamoeba sp. AC311 18S ribosomal RNA gene with 98% nucleotide sequence homology.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.10
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• pp.5919-5924
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• 2014

Accumulated dross adhered to the cutting support degrades the cutting accuracy and aggravates the working environment by reducing the efficiency of the dust collector. Furthermore, the cutting machine and product can be damaged by the scattering of molten metal. In this study, an attempt was made to increase the productivity of steel cutting process and improve the working environment by dross control. The dross adhesion characteristics were invested by a cutting experiment and the design concept for a dross removal machine was devised. Finally, a cutting support cleaning system and its operating algorithm were developed. The applicability of the developed system was examined and verified by a long-term field test after installation of the plasma arc cutting system of a shipyard.

• Plant Journal
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• v.18 no.1
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• pp.50-54
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• 2022

The demand for high-efficiency dust collectors is rapidly increasing to remove PM from exhaust gas emission facilities, such as thermal power plants, steel mills, and industrial cogeneration plants, as the Pmemission standards have been strengthened. In this study, the electrospray is adapted for existing electrosratic precipitator(EP) to remedy its shortcomings and to improve the performance. Electrospray has been mainly used for the purpose of generating very fine droplets, but fir the purpose of EP, the flow rate over 10 mL/min per nozzleis required, and a high flow rate condition of 65 to 200 times is required. The electrospray of high flow rate has a completely different spray shape from the low flow rate condition, and was visualized through various figures such as corona discharge photographs and shadow images.