• 제목/요약/키워드: NOx

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Characterization of Atmospheric Dispersion Pattern from Large Sources in Chungnam, Korea (충남지역 대형사업장의 대기오염물질 확산 특성 파악)

  • Choi, Woo Yeong;Park, Min Ha;Jung, Chang Hoon;Kim, Yong Pyo;Lee, Ji Yi
    • Particle and aerosol research
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    • v.17 no.3
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    • pp.55-69
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    • 2021
  • Chungnam region accounts for the largest SOX (22.8%) emission with the second-largest NOX (10.8%) emission in Korea due to the integration of many large industrial sources including a steel mill, coal-fired power plants, and petrochemical complex. Air pollutants emitted by large industrial sources can cause harmful problems to humans and the environment. Thus, it is necessary to understand dispersion patterns of air pollutants from large industrial sources in Chungnam to characterize atmospheric contamination in Chungnam and the surrounding area. In this study, seasonal atmospheric dispersion characteristics for SOX, NOX, and PM2.5 from ten major point sources in Chungnam were evaluated using HYSPLIT 4 model, and their contributions to SO2, NO2 concentrations in the regions near the source areas were estimated. The predictions of the HYSPLIT 4 model show a seasonal different dispersion pattern, in which air pollutants were dispersed toward the southeast in winter while, northeast in summer. In summer, due to weaker wind speed, air pollutants concentrations were higher than in winter, and they were dispersed to the metropolitan area. The local emissions of air pollutants in Taean area had a greater influence on the ambient SO2 and NO2 concentrations at Taean, whereas SOX and NOX emissions from large sources located at Seosan showed relatevely little effect on the ambient ambient SO2 and NO2 concentrations at Seosan.

THERE ARE NO NUMERICAL RADIUS PEAK n-LINEAR MAPPINGS ON c0

  • Sung Guen Kim
    • Bulletin of the Korean Mathematical Society
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    • v.60 no.3
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    • pp.677-685
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    • 2023
  • For n ≥ 2 and a real Banach space E, 𝓛(nE : E) denotes the space of all continuous n-linear mappings from E to itself. Let Π (E) = {[x*, (x1, . . . , xn)] : x*(xj) = ||x*|| = ||xj|| = 1 for j = 1, . . . , n }. An element [x*, (x1, . . . , xn)] ∈ Π(E) is called a numerical radius point of T ∈ 𝓛(nE : E) if |x*(T(x1, . . . , xn))| = v(T), where the numerical radius v(T) = sup[y*,y1,...,yn]∈Π(E)|y*(T(y1, . . . , yn))|. For T ∈ 𝓛(nE : E), we define Nradius(T) = {[x*, (x1, . . . , xn)] ∈ Π(E) : [x*, (x1, . . . , xn)] is a numerical radius point of T}. T is called a numerical radius peak n-linear mapping if there is a unique [x*, (x1, . . . , xn)] ∈ Π(E) such that Nradius(T) = {±[x*, (x1, . . . , xn)]}. In this paper we present explicit formulae for the numerical radius of T for every T ∈ 𝓛(nE : E) for E = c0 or l. Using these formulae we show that there are no numerical radius peak mappings of 𝓛(nc0 : c0).

Effect of SO2 Concentration on NOx Removal Efficiency in NaOH-Based Wet Scrubbing (NaOH를 이용한 배기가스의 습식 스크러빙에서 SO2 농도에 따른 NOx 제거효율)

  • Kang, Myung Soo;Hwang, Jungho
    • Journal of Korean Society for Atmospheric Environment
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    • v.34 no.5
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    • pp.659-667
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    • 2018
  • $NO_x$ and $SO_2$ are mainly generated in the combustion of fossil fuels, and they cause secondary aerosol formation and acid rain in the atmosphere. Many studies have been conducted on the wet scrubbing process which can simultaneously reduce $NO_x$ and $SO_2$ at relatively low temperature. In this study, we conducted an experimental study on wet scrubbing by using NaOH solution. Especially, this study focuses on $NO_x$ and $SO_2$ removal characteristics by varying $NO_2/NO_x$ ratio and $SO_2$ concentration.

Removal of NOx from Graphene based Photocatalyst Ceramic Filter (그래핀 기반 광촉매 담지 세라믹필터에서 질소산화물(NOx)의 제거)

  • Kim, Yong-Seok;Kim, Young-Ho
    • Applied Chemistry for Engineering
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    • v.33 no.6
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    • pp.600-605
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    • 2022
  • In this study, nitrogen oxide (NOx) removal experiments were performed using a graphene based ceramic filter coated with a V2O5-WO3-TiO2 catalyst. Graphene oxide (GO) was prepared by Hummer's method using graphite, and the reduced graphene oxide was produced by reducing with hydrazine (N2H4). Vanadium (V), Tungsten (W), and Titanium (Ti) were coated by the sol-gel method, and then a metal oxide-supported filter was prepared through a calcination process at 350 ℃. A NOx removal efficiency test was performed for the catalytic ceramic filters with UV light in a humid condition. When graphene oxide (GO) and reduced graphene oxide (rGO) were present on the filter, the NOx removal efficiency was superior to that of the conventional ceramic filter. Most likely, this is due to an improvement in the adsorption properties of NOx molecules on graphene coated surfaces. As the concentration of graphene increased, higher NOx removal efficiency was confirmed.

Removal of NOx using electron beam process with NaOH spraying

  • Shin, Jae Kyeong;Jo, Sang-Hee;Kim, Tae-Hun;Oh, Yong-Hwan;Yu, Seungho;Son, Youn-Suk;Kim, Tak-Hyun
    • Nuclear Engineering and Technology
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    • v.54 no.2
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    • pp.486-492
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    • 2022
  • Nitrogen oxides (NOx; NO and NO2) are major air pollutants and can cause harmful effects on the human body. Electron Beam Flue Gas Treatment (EBFGT) is a technology that generates electrons with an energy of 0.5-1 MeV using electron accelerators and effectively processes exhaust gases. In this study, NOx was removed using an electron beam accelerator with spraying additives (NaOH and NH4OH). NO and NO2 were 100% and more than 94% removed, respectively, at an electron beam absorbed dose of 20 kGy and an additive concentration of 0.02 M (mol/L). In most cases, NOx was removed better with lower initial NOx concentrations and higher electron beam absorbed doses. As the irradiation strength (mA) of the electron beam increases, the probability of electron impact on the material accordingly rises, which may lead to increase removal efficiency. The results of the present study show that the continuous electron beam process using additives achieved more effective removal efficiency than either individual process (wet-scrubbing or EB irradiation only).

The Reaction Characteristics of NOx/N2O and NH3 in Crematory Facility SCR Process with Load Variation (부하변동이 큰 화장시설 SCR 공정에서 NOx/N2O 및 NH3 동시 저감 특성 연구)

  • Park, Poong Mo;Lee, Ha Young;Yeo, Sang-Gu;Yoon, Jae-Rang;Dong, Jong In
    • Journal of Korean Society for Atmospheric Environment
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    • v.33 no.6
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    • pp.605-615
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    • 2017
  • Efficient simultaneous reduction conditions for $NO_x$ and $NH_3$-slip was investigated in SCR (Selective Catalytic Reduction) process with load variation by applying dual catalysts (SCR catalyst, $NH_3$ decomposition catalyst) system. $N_2O$ formation characteristics were analyzed to look into possible undesirable reaction pathways. In the experiments of catalyst characteristics, various operational variables were tested for the combined catalytic system, such as $NH_3/NO_x$ ratio, temperature, oxygen concentration and $H_2O$. The reaction characteristics of $NO_x$, $NH_3$ and $N_2O$ were analyzed and optimal conditions could be evaluated for the combustion facility with varied load. In terms of $NO_x/NH_3$ simultaneous reduction and $N_2O$ formation suppression, optimal condition was considered NSR 1.2 and temperature $300^{\circ}C$. At this operational condition, $NO_x$ conversion was 98%, $NH_3$ reduction efficiency was 95%, generated $N_2O$ concentration 9.5 ppm with inlet $NO_x$ concentration of 100 ppm. In $NH_3-SCR$ process with $NH_3$ decomposition catalyst, $NO_x$ and $NH_3$ can be considered to be reduced simultaneously at limited conditions. The results of this study may be utilized as basic data at facilities requiring simultaneous $NO_x$ and $NH_3$ reduction for facilities with load variation.

Effect of SOx on HC-SCR Kinetics over Ag/Al2O3 Catalyst (SOx 함유 HC-SCR에서 산처리 Ag/Al2O3 촉매의 반응 특성)

  • Lee, Ju-Heon;Park, Jeong-Whan;Kim, Seong-Soo;Yoo, Seung-Joon;Kim, Jin-Gul
    • Journal of Hydrogen and New Energy
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    • v.22 no.5
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    • pp.714-720
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    • 2011
  • Ethanol was used as reducing agent to remove $NO_x$ exhaust from the stationary source. Pre-treatment with sulfuric acid over $Ag/Al_2O_3$ catalyst was dedicated to overcome the $SO_2$ poisoning effect. The $NO_x$ reduction experiment was performed under the simulated condition of power plant The increased surface area with higher CPSI devoted to increase de-$NO_x$ yield. De-$NO_x$ yield of the $NO_x$ exhaust containing 20 ppm of $SO_2$ increased after acid treatment with 0.7% $H_2SO_4$ over 4.0% $Ag/Al_2O_3$, where the increased dispersion of Ag found from the results of XRD and XPS was the dominant factor for the increased de-$NO_x$ yield. However, the reason for the decreased de-$NO_x$ yield with the acid treatment of higher concentration (1.0% and 2.0%) of $H_2SO_4$ was found to be due to the formation of $Ag_2SO_4$ crystallites found from XRD result. Acid-treated $Ag/Al_2O_3$ catalyst showed maximum de-$NO_x$ yield at higher temperature than non-treated $Ag/Al_2O_3$ catalyst did.

Characterization of NOx Reduction on Filter Bag Support System at Low Temperature using Powder Type MnOx and V2O2/TiO2 Catalysts (분말형 MnOx와 V2O2/TiO2 촉매를 이용한 저온영역의 백필터 공정에서 질소산화물 제거 특성)

  • Kim, Byung-Hwan;Kim, Jeong-Heon;Kang, Pil-Sun;Yoo, Seung-Kwan
    • Journal of Korean Society for Atmospheric Environment
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    • v.26 no.1
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    • pp.1-9
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    • 2010
  • In this study, the selective catalytic reduction of $NO_x$ with ammonia was carried out in a filter bag support reactor. The experiments were performed by powder type $MnO_x$ and $V_2O_5$/$TiO_2$ catalyst at low temperature between 130 and $250^{\circ}C$. Also, the effect of $SO_2$ and $H_2O$ on the NO conversion was investigated under our test conditions. The powder type catalysts were analyzed by X-ray photoelectron spectrum (XPS), X-ray diffraction(XRD), scanning electron microscopy (SEM) and thermal gravimetric analysis (TGA). It was observed that NO removal efficiency of the powder type $V_2O_5$/$TiO_2$ catalyst was 85% at low temperature($200^{\circ}C$) under presence of oxygen and that of $MnO_x$ was 50% at the same condition. The powder type $V_2O_5$/$TiO_2$ catalyst, in conclusion, was found to be available for SCR reaction in a filter bag support system.

Empirical Analysis on Determinants of Air Pollution in China (중국의 대기오염 배출 결정요인에 대한 경험적 분석)

  • Li, Dmitriy D.;Wang, Wen;Bae, Jeong Hwan
    • Environmental and Resource Economics Review
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    • v.29 no.1
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    • pp.23-45
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    • 2020
  • The rapid economic growth has brought tremendous pressure on the environment and caused severe air pollution in China. This study empirically examines causes of air pollution in China. Panel-corrected standard errors procedure (PCSE) was used to analyze major determinants of increasing or reducing emissions of sulfur dioxide (SO2) and nitrogen oxides (NOX) in 30 Chinese provinces. The estimation results show that SO2 emission is mitigated as per capita regional GDP increases, but the relation between emission of NOX and per capita regional GDP is found to have an inverse N-shaped curve, which implies that emission of NOX is ultimately expected to decline with economic growth. As for increasing factors of air pollutants, electricity consumption is a significant common source of SO2 and NOX emissions. Moreover, the results show that increment of coal consumption significantly affects emission of SO2 while increase of natural gas consumption reduce emission of SO2. On the other side, investment in energy industry, and investment on treatment of waste gases are determinants of mitigating emissions of SO2, but have no impact on NOX. Consumption of diesel, truck ratio and number of vehicles increase emission of NOX. Meanwhile, higher precipitation rate is a common determinant of mitigating emissions of SO2 and NOX. Policy implications are suggested in the conclusion.

Preparation of Perovskite-Type Oxide (La1-xSrxCo1-yFeyO3-δ) Coating Solution by Sol-Gel Method (Sol-Gel법에 의한 Perovskite-Type Oxide(La1-xSrxCo1-yFeyO3-δ) 코팅용액의 제조)

  • Park, Ja-Ryong;Lee, Dong-Il;Jung, Sang-Hyeok;Kim, Tae-Hwan;Sung, Jae-Suk;Song, Ki-Chang
    • Korean Chemical Engineering Research
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    • v.43 no.6
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    • pp.740-744
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    • 2005
  • Perovskite-type oxide $La_{1-x}Sr_xCo_{1-y}Fe_yO_{3-{\delta}}$ sols were prepared by sol-gel method using $La(NO_3)_3{\cdot}xH_2O$, $Sr(NO_3)_2$, $Co(NO_3)_2{\cdot}6H_2O$ and $Fe(NO_3)_3{\cdot}9H_2O$ as starting materials. The properties of the perovskite-type oxide sols were investigated by viscometer, FT-IR, TG-DTA and XRD. The prepared sols showed 1.16 cp in average viscosity, and a strong acidic condition of pH 0.5, irrespective of composition of the starting materials. The viscosity of sols at the same volume decreases, but the gelation time of sols, at which the sol viscosity increases rapidly, increases when increasing La concentration in composition of starting materials.