• Title, Summary, Keyword: De-NOx

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An Experimental Study on dte Performance of Plasma-DeNOx Catalyst widt Supplying Hydrocarbon Reductant (탄화수소 환원제 공급에 따른 플라즈마-DeNOx 촉매의 성능에 관한 실험적 연구)

  • Hur, Dong-Han;Min, Kyoung-Doug
    • Transactions of the Korean Society of Automotive Engineers
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    • v.16 no.1
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    • pp.93-99
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    • 2008
  • To improve the performance of plasma-DeNOx catalyst, a research on active system was performed experimentally. Two hydrocarbons, propane and diesel, were used as a reductant in this study. First, using propane, basic performances of plasma-DeNOx catalyst such as the effects of plasma and C/N ratio were measured at the various engine operating conditions. NOx conversion of catalyst was improved as plasma power or C/N ratio was increased. Next, diesel was injected in the exhaust gas flow as a reductant. The first test using diesel as a reductant is spray visualization in a high temperature flow and spray images were utilized for analysis of posterior test results. To evaluate the effect of an injection direction, it was compared with 6 installation methods of diesel injector due to THC concentrations at the inlet of plasma. From the results, injector was installed toward downstream direction below the pipe. Then, basic performances of plasma-DeNOx catalyst with various injection quantities were measured. As an injection quantity was increased, $NO_2$ conversion of plasma reactor was increased but NOx conversion of catalyst was nearly zero. This was because NOx conversion of catalyst had slowed as time goes by due to black particles which had been adhered to the catalyst.

Numerical Modeling of Vanadia-based Commercial Urea-SCR plus DOC Systems for Heavy-duty Diesel Exhaust Aftertreatment Systems (바나듐 기반의 Urea-SCR과 DOC가 결합된 Heavy-Duty 디젤 배출가스 후처리 시스템의 SCR De-NOx 성능 향상에 관한 수치해석 연구)

  • Yun, Byoung-Kyu;Kim, Chong-Min;Kim, Man-Young;Cho, Gyu-Baek;Kim, Hong-Suk;Jeong, Young-Il
    • Transactions of the Korean Society of Automotive Engineers
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    • v.18 no.2
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    • pp.24-30
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    • 2010
  • In this study, numerical experiments were carried out to estimate the SCR De-NOx performance in DOC plus SCR systems. The SCR De-NOx phenomena are described by Langmuir-Hinshelwood reaction scheme. After validating the present approach by comparing the present results with the experimental results, such various parameters as space velocity, $H_2O$ concentration, $NO_2$/NOx ratio and relative volume of DOC are explored to increase the SCR De-NOx performance. The results indicate that SCR De-NOx performance largely depends on space velocity and $NO_2$/NOx ratio, especially below $200^{\circ}C$. SCR De-NOx performance is seriously affected by relative volume of DOC with SCR due to increasing in $NO_2$/NOx ratio at below $250^{\circ}C$.

The Role of Lattice Oxygen in the Selective Catalytic Reduction of NOx on V2O5/TiO2 Catalysts (V2O5/TiO2 촉매의 선택적 환원촉매반응에서 격자산소의 역할)

  • Ha, Heon-Phil;Choi, Hee-Lack
    • Korean Journal of Materials Research
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    • v.16 no.5
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    • pp.323-328
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    • 2006
  • In situ electrical conductivity measurements on $V_2O_5WO_3/TiO_2$ catalysts were carried out at between 100 and $300^{\circ}C$ under pure oxygen, NO and $NH_3$ to investigate the reaction mechanism for ammonia SCR (selective catalytic reduction) de NOX. The electrical conductivity of catalysts changed irregularly with supply of NO. It was, however, found that the electrical conductivity change with ammonia supply was regular and the increase of electrical conductivity was mainly caused by reduction of the labile surface oxygen. The electrical conductivity change of catalysts showed close relationship with the conversion rate of NOx. Variation of conversion rate in atmosphere without gaseous oxygen also showed that labile lattice oxygen is indispensable in the initial stage of the de NOx reaction. These results suggest that liable lattice oxygen acts decisive role in the de NOx mechanism. They also support that de NOx reaction occurs through the Eley?Rideal type mechanism. The amount of labile oxygen can be estimated from the measurement of electrical conductivity change for catalysts with ammonia supply. This suggests that measurement of the change can be used as a measure of the de NOx performance.

Effect of Additives on Catalytic Activity in Thermal Catalytic De-NOx Process (Thermal catalytic de-NOX 공정에서 첨가제가 촉매의 활성에 미치는 영향에 관한 연구)

  • 이진구;김태원;최재순;김정호;이재수;장경욱;박해경
    • Journal of Korean Society for Atmospheric Environment
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    • v.15 no.3
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    • pp.249-255
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    • 1999
  • We sdudied effect of additives on catalytic activity in thermal catalytic de-NOx process which was composed of thermal reduction, catalytic reduction and catalytic oxidation stage. Pd-Pt/${\gamma}$-$Al_2O_3$ catalysts with the addition of transition metals(Co, Cu, Fe, Ni, W, Zn, Zr) and rare earth metals(Ce, Sr) were prepared by the conventional washcoating method. Those catalysts were characterized by CO pulse chemisorption, ICP, $N_2$ adsorption, SEM and XRD. The effect of catalyst additives on NOx removal for diesel emission was studied in thermal catalytic de-NOx process at reduction temperature(350~50$0^{\circ}C$), space velocity(5,000~20,000 $hr^{-1}$) and the engine load(0~120kW). The concentraton of CO, $CO_2$, NO and $NO_2$ in the exhaust gas increased with the engine load. On the other hand the concentration of $O_2$ decreased. The de-NOx activityof all prepared catalysts increased with respect to high CO and low $O_2$ level in the thermal reduction stage of the process. Insertion of Ce to Pt-Pd/${\gamma}$-$Al_2O_3$ catalyst showed the best activity of all the catalysts under these experimental conditions. De-NOx catalysts are effective to remove CO in addition to NOx in the catalytic reduction stage.

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Spray Characteristics of Injector Used for HC-DeNOx Catalyst System (HC-DeNOx 촉매용 인젝터의 분무 특성 연구)

  • Lee, Dong-Hoon;Jung, Hae-Young;Lee, Ki-Hyung;Lee, Jin-Ha;Yeo, Kwon-Gu
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.31 no.2
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    • pp.167-172
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    • 2007
  • A new method that optimizes a control of hydrocarbon (HC) addition to diesel exhaust gas for HC type DeNOx catalyst system has been developed. These catalysts are called the HC-DeHOx catalyst in this paper. The system using HC-DeNOx catalyst requires a resonable quantity of hydrocarbons addition in the inlet gas of the catalyst, because the HC concentration in a diesel engine is so low that the HC is not sufficient for NOx conversion. It is expected that this study offers a robust data developing HC injection system.

A Study on Degradation Characteristic and Flow Behavior in De-NOx Catalyst (탈질촉매 내 열화특성과 유동상태에 관한 연구)

  • Hwang, Seung-Min
    • Journal of Environmental Science International
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    • v.19 no.9
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    • pp.1093-1101
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    • 2010
  • In this study, the indirect correlation of degradation characteristic and flow behavior in the de-NOx catalyst is investigated experimentally. The inner flow behavior in the de-NOx catalyst is varied from turbulent flow to laminar flow and the degradation of the de-NOx catalyst is remarkably affected by the inner flow. The degradation of the catalyst is increased in the upstream region near the inlet because injected turbulent flow enhances the adhesion of ash particle on the catalyst surface. The degradation of the catalyst near the inlet also governs the overall efficiency of the catalyst. The amount of adhered ash particles on the catalyst surface decreases as they progress downstream. This is due to the inner flow transition from turbulent flow to laminar flow.

Effect of $NH_3$/NOx ratio and Catalyst Temperature on DeNOx Performance in the $NH_3$-SCR reactor ($NH_3$-SCR 반응기 내에서의 $NH_3$/NOx 및 SCR 촉매 온도가 DeNOx 성능에 미치는 영향)

  • Hong, Kil-Hwa;Gong, Ho-Jeong;Hwang, In-Goo;Park, Sim-Soo
    • Proceedings of the KSME Conference
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    • pp.3096-3101
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    • 2008
  • Selective Catalytic Reduction (SCR) technology is well-known to be effective for the reduction of NOx emission. So car manufacturers has adopted Ures-SCR system to be satisfied with emission regulation. This paper discusses the effective of $NH_3/NOx$ ratio and SCR catalyst temperature in the $NH_3$-SCR reactor on DeNOx performance. So it is shown the characteristic of NOx conversion and ammonia slip using the $NH_3$ instead of Urea-Solution. From the result of this study, it is found to optimize $NH_3/NOx$ ratio to have the best case of high NOx conversion and low ammonia slip at variable SCR catalyst temperatures. Lastly, it is also found the characteristics of NOx conversion and ammonia slip with compared with Urea.

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Characteristics of NOx Reduction on NSR(NOx Storage and Reduction) Catalyst Supported by Ni, Ru-ZSM-5 Additives (Ni, Ru-ZSM-5를 첨가한 NSR 촉매의 NOx 정화 특성)

  • Choi, Byung-Chul;Lee, Choon-Hee;Jeong, Jong-Woo
    • Transactions of the Korean Society of Automotive Engineers
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    • v.15 no.5
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    • pp.105-111
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    • 2007
  • In this study, we investigated the conversion performance of de-NOx catalyst for lean-burn natural gas engine. As a de-NOx catalyst, NOx storage reduction catalyst was composed of Pt, Pd and Rh with washcoat including Ba and Ni, Ru-ZSM-5. Ni, Ru-ZSM-5, which was regarded as a NOx direct decomposition catalyst, was made up of ion exchanged ZSM-5 by 5wt.% Ni or Ru. The performance of de-NOx catalyst was evaluated by NOx storage capacity and catalytic reduction in air/fuel, $\lambda=1.6$. The catalytic reaction was also observed when the added fuel was supplied to fuel rich atmosphere by fuel spike period of 5 seconds. The NOx conversion of the catalysts with Ni-ZSM-5 or Ru-ZSM-5 was mainly caused by the effect of NOx adsorption of Ba rather than the catalytic reduction of Ni, Ru-ZSM-5. Ni, Ru-ZSM-5 catalysts can not use for the NSR catalyst because they have quick process in thermal deactivation.

SNCR Application to Diesel Engine DeNOx under Combustion-driven Flow Reactor Conditions

  • Nam, Chang-Mo;Gibbs, Bernard M.
    • Journal of Environmental Science International
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    • v.21 no.7
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    • pp.769-778
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    • 2012
  • Diesel DeNOx experiments using the SNCR process were performed by directly injecting NH3 into a simulated engine cylinder (966 $cm^3$) for which a diesel fuelled combustion-driven flow reactor was designed by simulating diesel engine geometry, temperature profiles, aerodynamics and combustion products. A wide range of air/fuel mixtures (A/F=20~45) were combusted for oxidizing diesel flue gas conditions where an initial NOx levels were 250~900 ppm and molar ratios (${\beta}=NH_3/NOx$) ranged from 0.5~2.0 for NOx reduction tests. Effective NOx reduction occurred over a temperature range of 1100~1350 K at cylinder injections where about 34% NOx reduction was achieved with ${\beta}$=1.5 and cylinder cooling at optimum flow conditions. The effects of simulated engine cylinder and exhaust parts, initial NOx levels, molar ratios and engine speeds on NOx reduction potential are discussed following temperature gradients and diesel engine environments. A staged injection by $NH_3$ and diesel fuel additive is tested for further NOx reduction, and more discussed for practical implication.

A development of reactor design software for De-NOx system using the selective catalytic reduction method (선택적 촉매 환원법을 이용한 De-NOx 시스템의 반응로 설계 전산프로그램 개발)

  • 정경열;오상훈;동은석;이수태;류길수
    • Proceedings of the Korean Society of Marine Engineers Conference
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    • pp.187-191
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    • 2002
  • The exhaust gas from electric power stations, incinerators and industrial boilers contains considerable amount of harmful nitric oxide which causes air pollution. Selective catalytic reduction system with ammonia as a reductant(NH$_{3}$ SCR) have been applied to remove NOx since 1970. it is widely accepted that the NH$_{3}$ SCR process is the best method for the removal of NOx. In this paper the design of SCR reactor based on the NOx displacement is considered and the design program of SCR reactor is developed. The newly developed design program for de-NOx system maybe used in practice.

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