• Title/Summary/Keyword: 선택적 환원촉매

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Modeling of $NH_3$-SCR Diesel $NO_x$ Reduction and Effects of $NO_2/NO_x,\;NH_3$/NO Ratios on the De-$NO_x$ Efficiency ($NH_3$-SCR 방법에 의한 디젤기관의 $NO_x$ 저감과정의 모델링 및 $NO_2/NO_x,\;NH_3$/NO비에 따른 저감효율 변화 해석)

  • Jung, Seung-Chai;Yoon, Woong-Sup
    • Transactions of the Korean Society of Automotive Engineers
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    • v.16 no.3
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    • pp.179-187
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    • 2008
  • A mathematical modeling of $NO_x$ reduction in $NH_3$-SCR process is conducted. The present deterministic model solves one-dimensional conservation equations of mass and species concentrations for channel flows and the catalytic reaction. NO and NO_2$ reactions by the vanadium catalyst in the presence of $NH_3$ are calculated with the rate expressions of Langmuir-Hinshelwood scheme. The modeling was validated with extensive empirical data regarding $NO_x$ reduction efficiency. Analysis of De-$NO_x$ sensitivity conducted with regard to oxygen and water yielded highly accurate prediction over a wide range of $NO_2/NO_x$ ratios from 0 to 1 in a temperature range of $200^{\circ}C{\sim}550^{\circ}C$. The $NO_x$ reduction largely depends on $NO_2/NO_x$ ratio at temperatures lower than $300^{\circ}C$. NO reduction efficiency is significantly augmented with increasing in $NH_3$/NO ratio at higher temperatures, whereas rather insensitive to the $NH_3$/NO ratio at lower temperatures.

Change of Ammonia Consumption with Gas Turbine Output in DeNOx System for a 580 MW Combined Cycle Power Plant (580 MW급 복합발전소 탈질설비에서 가스터빈 출력에 따른 암모니아 소모량 변화)

  • Jang, Yong-Woo;Yoo, Ho-Seon
    • Plant Journal
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    • v.15 no.3
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    • pp.23-28
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    • 2019
  • In this study, ammonia consumption by gas turbine output was adjusted to find out the amount of ammonia consumption that complies with the enhanced Air Quality Preservation Act and internal regulation emission standards in SCR type DeNOx System for a 580 MW Sejong Combined Cycle Power Plant. For measurements, the gas turbine output was varied to 50, 99, 149, 198 MW and ammonia consumption was adjusted with the combustion gas and ammonia supply conditions fixed at each stage. When the emission limit were change from 10 ppm to 8 ppm, ammonia consumption was increased from 78, 93, 105, 133 kg/h to 89, 113, 132, 176 kg/h. The increase rate of ammonia consumption was 14, 22, 26, 32% per output category compared to the 10 ppm emission limit, which was shown to increase as output increased.

Effect of the De-NOx Facility Operating Condition on NOx Emission in a 125 MW Wood Pellet Power Plant (125 MW급 우드펠릿 발전소에서 탈질설비 운전조건이 질소산화물 발생량에 미치는 영향)

  • Jeon, Moonsoo;Lee, Jae-Heon
    • Plant Journal
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    • v.18 no.3
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    • pp.52-61
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    • 2022
  • This study tested the effect of de-NOx Facility operating condition on Nox emisiion in a 125 MW wood pellet power plant in Yeongdong Eco Power Plant Unit 1, which is in operation. As SNCR urea flow rate increased, NOx emission gradually decreased, but ammonia slip after SCR increased. The boiler under test has a structure that is unfavorable to SNCR operation due to the high internal temperature, and the optimum location of the nozzle will be required. SCR dilution air temperature change did not affect the amount of NOx generated. Increasing SCR ammonia flow reduced the NOx emission at SCR outlet and also increased the NOx removal efficiency. However, the ammonia flow rate of 111 kg/h, which does not exceed the ammonia slip its own reference limit, is estimated to be the maximum operating standard. The increase in SCR mixer pressure reduced NOx emission and the removal efficiency was also measured to be the most effective variable to inhibit NOx production.

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Characteristic Analysis of a SCR System using a Metal Foam in Diesel Engines (디젤 엔진에서 금속 폼을 적용한 SCR 촉매의 특성 분석)

  • Kim, Yongrae;Choi, Kyonam
    • Journal of ILASS-Korea
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    • v.18 no.4
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    • pp.196-201
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    • 2013
  • SCR(Selective Catalytic Reduction) is a major after-treatment solution to reduce NOx emission in recent diesel engines. In this study, a metal foam is applied as an alternative SCR substrate and tested in a commercial diesel engine to compared with a conventional ceramic SCR system. Basic engine test from ND-13 mode shows that a metal foam catalyst has lower NOx conversion efficiency than a ceramic catalyst especially over $350^{\circ}C$. A metal foam catalyst has characteristics of high exhaust gas pressure before a SCR catalyst and high heat transfer rate due to its material and structure. NOx conversion efficiency of a metal foam catalyst shows an increasing tendency along with the increase of exhaust gas temperature by $500^{\circ}C$. The effect of urea injection quantity variation is also remarkable only at high exhaust gas temperature.

A Study on the Urea-SCR System for NOx Reduction of a light-Duty Diesel Engine (소형 디젤엔진의 NOx 저감을 위한 Urea-SCR 시스템에 관한 연구)

  • Nam Jeong-Gil
    • Transactions of the Korean Society of Automotive Engineers
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    • v.13 no.5
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    • pp.57-63
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    • 2005
  • The effects of an urea injection at the exhaust pipe for a 4-cylinder DI(Direct Injection) diesel engine were investigated with the parameters such as urea-SCR(Selective Catalytic Reduction) and EGR system. The urea quantity was controlled by NOx quantity and MAF(Manifold Air Flow). The urea injection quantity can be controlled with the urea syringe pump, precisely. The effects of NOx reduction for the urea-SCR system were investigated with and without ECR engine, respectively. It was concluded that the SUF(Stoichiometric Urea Flow) is calculated and the NOx results are visualized with engine speed and load. Furthermore, the NOx map is made from this experimental results. It was suggested, therefore, that NOx reduction effects of the urea-SCR system without the EGR engine were better than that with the EGR engine except of low load and low speed.

A Study on the Synthesis of $\textrm{TiO}_2$for Catalyst Carrier from $\textrm{TiOSO}_4$ and $\textrm{TiO(\textrm{SO}_4)_2$Solutions ($\textrm{TiOSO}_4$$\textrm{TiO(\textrm{SO}_4)_2$용액으로부터 촉매 담체용 $\textrm{TiO}_2$합성에 관한 연구)

  • Yu, Yeon-Tae;Choe, Yeong-Yun;Kim, Byeong-Gyu;Nam, Cheol-U;An, Byeong-Guk
    • Korean Journal of Materials Research
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    • v.9 no.11
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    • pp.1062-1068
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    • 1999
  • 고정원으로부터 배출되는 질소산화물의 저감 기술 중에서 선택적 촉매 환원법(SCR법)은 가장 경제적이고 효율적인 방법으로 알려져 있다. 이 SCR 촉매의 탈질능을 향상시키기 위하여,$ TiOSO_4$ 및 Ti($SO_4$)$_2$용액으로부터 비표면적이 넓은 $TiO_2$의 비표면적 및 결정구조에 미치는 영향과 이들의 상관관계에 대하여 조사하였다. $TiOSO_4$용액으로부터 합성한 $TiO_2$의 최대 비표면적은 $382\m^2$/g이었고, Ti($SO_4$)$_2$용액으로부터 합성한 $TiO_2$의 최대 비표면적은 $335\m^2$/g이었으며, $TiO_2$는 비정질 형태의 결정구조를 보였다. 하소처리에 의해 비정질 $TiO_2$는 결정화되었고, 결정 중에 함유되어 있는 불순물은 $TiO_2$의 결정화를 억제하였다.

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The Electrochemical Studies of Non-enzymatic Glucose Sensor on the Nickel Nanoparticle-deposited ITO Electrode (ITO 전극 위에 고정된 니켈 나노 입자를 이용한 무효소 혈당센서에 관한 전기화학적인 연구)

  • Oh, In-Don;Kim, Samantha;Choi, Young-Bong
    • Journal of the Korean Electrochemical Society
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    • v.17 no.3
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    • pp.164-171
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    • 2014
  • A highly sensitive and selective non-enzymatic glucose sensor has gained great attention because of simple signal transformation, low-cost, easily handling, and confirming the blood glucose as the representative technology. Until now, glucose sensor has been developed by the immobilization of glucose oxidase (GOx) on the surface of electrodes. However although GOx is quite stable compared with other enzymes, the enzyme-based biosensors are still impacted by various environment factors such as temperature, pH value, humidity, and toxic chemicals. Non-enzymatic sensor for direct detecting glucose is an attractive alternative device to overcome the above drawbacks of enzymatic sensor. Many efforts have been tried for the development of non-enzymatic sensors using various transition metals (Pt, Au, Cu, Ni, etc.), metal alloys (Pt-Pb, Pt-Au, Ni-Pd, etc.), metal oxides, carbon nanotubes and graphene. In this paper, we show that Ni-based nano-particles (NiNPs) exhibit remarkably catalyzing capability for glucose originating from the redox couple of $Ni(OH)_2/NiOOH$ on the surface of ITO electrode in alkaline medium. But, these non-enzymatic sensors are nonselective toward oxidizable species such as ascorbic acid the physiological fluid. So, the anionic polymer was coated on NiNPs electrode preventing the interferences. The oxidation of glucose was highly catalyzed by NiNPs. The catalytically anodic currents were linearly increased in proportion to the glucose concentration over the 0~6.15 mM range at 650 mV versus Ag/AgCl.

Selective Catalytic Reduction (SCR) of NOx with NH3 on Sb-promoted VWTi Catalysts (Sb 첨가에 따른 VWTi 촉매의 암모니아 선택적 촉매 환원(SCR)을 통한 질소산화물 저감)

  • Kim, Su Bin;Choi, Gyeong Ryun;Shin, Jung Hun;Hong, Sung Chang
    • Applied Chemistry for Engineering
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    • v.32 no.1
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    • pp.35-41
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    • 2021
  • VWTi, which is used as a commercial catalyst in NH3-SCR, exhibits excellent denitrification performance at 300 to 400 ℃, but there is a problem that efficiency decreases at low temperatures below 300 ℃. Research on catalysts containing promoter to increase low-temperature denitrification efficiency is steadily progressing. However, research on the cause of the improvement in low-temperature denitrification efficiency of the catalyst and the catalyst properties is insufficient. In this study, it was confirmed that by adding Sb to VWTi, denitrification performance was improved by more than 10% in NH3-SCR reaction below 300 ℃. At this time, the space velocity and the size of the catalyst particles were controlled to exclude the influence of external/internal diffusion. In addition, the catalytic properties according to the presence or absence of Sb were investigated by performing BET, TEM/EDS, O2-TPD, H2-TPR and DRIFTs analysis. It was judged that the addition of Sb increased the adsorbed oxygen species on the surface of the catalyst, thereby enhancing the redox properties of the catalyst at low temperature and exhibiting excellent denitrification performance.

A Study of the characteristics of NOx measurement and analysis methods of the SCR system for ships (선박용 SCR 시스템 NOx 측정 및 분석 방식의 특성 연구)

  • Kim, Sung-Yoon;Lee, Young-Ho;Kim, Min;Park, Sam-Sik
    • Journal of Advanced Marine Engineering and Technology
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    • v.39 no.4
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    • pp.387-392
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    • 2015
  • A method for measuring and analyzing the $NO_x$ in ships is described in $NO_x$ Technical Code 2008. The analysis device, as required by the Code, has been to use a Chemi-luminescence detection method or Heated Chemi-luminescence detection. on the other hand, selective catalytic reduction using $NH_3$ as a reducing agent has an interference effect on the analyzer, and causes measurement error. In this study, the Chemi-luminescence detection method was examined according to how it affects the concentration of $O_2$, CO, $SO_2$, $NH_3$. Fourier transform infrared spectrometry analysis equipment and measurement methods were compared. In order to confirm the effect of the physical interference of the measuring device, it was confirmed by decomposing a measuring device. Consequently, white precipitate and moisture were generated inside the chemiluminescence detection system and I found that affecting interference. The influence of interference highlights the need to consider the minimized $NO_x$ measurement method.

A Convergence Study on the Effects of NH3/NOx Ratio and Catalyst Type on the NOx Reduction by Urea-SCR System of Diesel Engine (디젤엔진의 Urea-SCR 시스템에 의한 NH3/NOx 비율 및 촉매 방식이 NOx 저감에 미치는 영향에 관한 융합연구)

  • Yoon, Heung-Soo;Ryu, Yeon-Seung
    • Journal of the Korea Convergence Society
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    • v.10 no.4
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    • pp.131-138
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    • 2019
  • Diesel engines have important advantages over its gasoline counterpart including high thermal efficiency, high fuel economy and low emissions of CO, HC and $CO_2$. However, NOx reducing is more difficult on diesel engines because of the high $O_2$ concentration in the exhaust, marking general three way catalytic converter ineffective. Two method available technologies for continuous NOx reduction onboard diesel engines are Urea-SCR and LNT. The implementation of the Urea-SCR systems in design engines have made it possible for 2.5l and over engines to meet the tightened NOx emission standard of Euro-6. In this study, we investigate the characteristics of NOx reduction with respect to engine speed, load, types of catalyst and the $NH_3$/NOx ratio and present the conditions which maximize NOx reduction. Also we provide detailed experimental data on Urea-SCR which can be used for the preparation for standards beyond Euro-6.