• 한국자동차공학회논문집
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• 제11권3호
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• pp.71-76
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• 2003

A numerical simulation of selective catalytic reduction (SCR) for NO with $NH_3$ is conducted over the $V_2O_5/TiO_2$ and $WO_3-V_2O_5/TiO_2$ catalysts. The governing $NH_3$ and NO transport equations are considered by using the time-dependent FCT (Flux-Corrected Transport) algorithm. After a validating simulation for $NH_3$ step feed and shut-off experiments is analyzed, transient behavior of $NH_3$ and NO concentration in a SCR catalyst is investigated by changing such parameters as inflow $NH_3$ concentration, temperature of the catalyst, and $NH_3$/NOx ratios.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2008년도 추계학술대회B
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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.

• 한국마린엔지니어링학회:학술대회논문집
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• 한국마린엔지니어링학회 2002년도 춘계학술대회논문집
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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.

• 한국대기환경학회지
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• 제33권6호
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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.

• 대한기계학회논문집A
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• 제24권11호
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• pp.2762-2770
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• 2000

The refuse incineration plant has an important role in saving the combustion energy for local heating system. But harmful combustion gas(NOx etc.) leads to some serious environmental problem. To reduce the gas, a SCR(Selective Catalytic Reduction)system is installed and it is controlled by adjusting the flow of ammonia gas(NH3) . In this paper, we apply a repetitive control method to reduce NOx by adjusting the flow of ammonia gas for SCR system in a refuse incineration plant which is located in Haeundae, Pusan, Firstly, we analyze the inlet NOx period by FFt method, and verify its periodic variations. Secondly, we design a repetitive control system by using state space model method. Lastly, the effectiveness of repetitive control system is shown by comparing to a conventional PID control in simulation and experimental results.

• 한국자동차공학회논문집
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• 제14권3호
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• pp.125-132
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• 2006

Transient kinetics of $NH_3$ adsorption/desorption and of SCR(selective catalytic reduction) of NO with $NH_3$ were studied over vanadium based catalysts, such as $V_2O_5/TiO_2$ and $V_2O_5-WO_3/TiO_2$. In the present catalytic reaction process, NO adsorption is neglected while $NH_3$ is strongly chemisorbed on the catalytic surface. Accordingly, it is ruled out the possibility of a reaction between strongly adsorbed $NH_3$ and NO species in line with the hypothesis of an Eley-Rideal mechanism. The present kinetic model assumes; (1) non-activated $NH_3$ adsorption, (2) Temkin-type $NH_3$ coverage dependence of the desorption energy, (3) non-linear dependence of the SCR reaction rate on the $NH_3$ surface coverage. Thus, the surface heterogeneity for adsorption/desorption of $NH_3$ is taken into account in this model. The present study extends the pure chemical kinetic model based on a powdered-phase catalytic system to the chemico-physical one applicable to a realistic monolith reactor.

• 공업화학
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• 제17권4호
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• pp.414-419
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• 2006

연소 배기가스 중의 수분, 탄화수소 및 CO가 저온 플라즈마 및 $NH_{3}$ SCR (Selective Catalytic Reduction)공정이 복합된 탈질공정에 미치는 영향에 대한 연구가 수행되었다. 실험결과 일반적인 SCR 반응에 비해 매우 빠른 반응속도를 갖는 fast SCR 반응은 $150{\sim}200^{\circ}C$의 저온조건에서 탈질율의 상승을 가져다주지만, 처리가스 중에 탄화수소가 있는 경우 fast SCR 반응의 역할이 상당히 감소되는 것을 확인할 수 있었다. 이는 저온 플라즈마 반응기에서 부분산화반응을 통해 탄화수소 중 일부가 알데히드로 전환되며, 알데히드는 fast SCR 반응에 있어 중요한 변수인 $NO_{2}/NO_{x}$ 비율에 영향을 주기 때문인 것으로 설명되었다. 한편, 수분 및 CO가 fast SCR 반응에 미치는 영향은 탄화수소에 비해 상대적으로 적음을 확인할 수 있었다.

• 공업화학
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• 제24권6호
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• pp.599-604
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• 2013

본 연구는 공침법으로 Ti가 첨가된 Mn-Cu 혼합산화물을 이용하여 $200^{\circ}C$ 이하의 저온 영역에서의 $NH_3$-SCR 반응특성에 관한 것이다. 제조된 촉매들은 BET, XRD, XPS, TPD를 이용하여 각각의 물리/화학적 특성을 분석하였다. Mn-Cu 혼합산화물은 매우 큰 비표면적과 저온에서의 높은 SCR 효율을 나타내었으며, Ti가 첨가된 경우 상대적으로 높은 SCR 효율과 $N_2$ 선택도를 나타내었다. 이러한 결과는 Ti가 첨가됨에 따라 화학 흡착된 산소종($Me-O_{ads}$)이 증가하여 NO가 $NO_2$로의 산화가 촉진되고, $Mn^{3+}$와 같은 $NH_3$의 흡착점의 수가 증가되었기 때문이다.

• 한국자동차공학회논문집
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• 제20권1호
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• pp.95-105
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• 2012

The selective catalytic reduction (SCR) system is a highly-effective aftertreatment device for NOx reduction of diesel engines. Generally, the ammonia ($NH_3$) was generated from reaction mechanism of SCR in the SCR system using the liquid urea as the reluctant. Therefore, the precise urea dosing control is a very important key for NOx and $NH_3$ slip reduction in the SCR system. This paper investigated NOx and $NH_3$ emission characteristics of urea-SCR dosing system based on model-based control algorithm in order to reduce NOx. In the map-based control algorithm, target amount of urea solution was determined by mass flow rate of exhaust gas obtained from engine rpm, torque and $O_2$ for feed-back control NOx concentration should be measured by NOx sensor. Moreover, this algorithm can not estimate $NH_3$ absorbed on the catalyst. Hence, the urea injection can be too rich or too lean. In this study, the model-based control algorithm was developed and evaluated on the numerical model describing physical and chemical phenomena in SCR system. One channel thermo-fluid model coupled with finely tuned chemical reaction model was applied to this control algorithm. The vehicle test was carried out by using map-based and model-based control algorithms in the NEDC mode in order to evaluate the performance of the model based control algorithm.

• 대한환경공학회지
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• 제33권5호
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• pp.368-377
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• 2011

소규모의 대기오염 배출원으로부터 질소산화물을 저감하는 방법으로 제안된 패키지형 SCR (selective catalytic reduction) 시스템 내에서 암모니아 농도제어에 관한 연구가 시행되었다. SCR 시스템의 효율은 촉매층의 효율적인 활용에 좌우되며 촉매층의 효율적인 사용은 시스템에 유입되는 배기가스의 유동균일도와 암모니아 농도의 균일도에 의해 좌우된다. 본 연구에서는 주어진 최적의 유동조건에서 SCR 시스템 내에 배치된 AIG 형상과 분사 유량 조정에 따른 암모니아 농도분포를 평가하였다. 기본 유동조건에서 분사구의 각도에 따른 전산해석 결과, 배가스 유동에 대해 동류방향($0^{\circ}$)으로 암모니아를 분사한 경우의 농도분포의 RMS(%) 수치는 약 95.3%, 대향방향인 $120^{\circ}$의 각도를 가지는 경우 90.1%로 파악되어 대향방향으로의 분사가 더 효율적인 것으로 파악되었다. 유동박리영역에서 벗어나도록 분사구의 위치를 변경하고 기초계산에서의 속도분포와 농도분포를 기준으로 환원제 유량을 조정한 결과 RMS(%) 수치를 최대 62.8%까지 하강시키는 효과를 가져왔다. AIG 형상 및 배치구조에 혼합증진의 효과를 정리하였다.