• Title/Summary/Keyword: SCR System

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Ammonia Flow Control for NOx Reduction in SCR(Selective Catalytic Reduction) System of Refuse Incineration Plant (소각로의 Nox제어용 SCR시스템의 암모니아 공급량 제어)

  • 김인규;여태경;김상봉
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 1997.04a
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    • pp.30-34
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    • 1997
  • This paper Describe a modelling method for SCR(selective Catalytic reduction) system in refuse incineration plant. We consider the SCR system as a single input single output system. For modelling the SCR system, an auto regressive exogeneous(ARX) modelling method is used. In this case, we should design the white noise input for modelling and put it on the system as an input (.NH/sap2/.), and taken an outlet NOx as an output. From these two relations, we design the ARX model with 45 second delay time and transform to discrete system with 0.5 sampling time. Using the obtained SCR model, we simulate the SCR system to reduce the outlet NOx content by a conventional PID control method.

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Study on Urea Spray Visualization in SCR System (SCR장치에서 우레아 분무가시화 실험에 관한 연구)

  • Baik, Doo-Sung;Lee, Jong-Sun
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.9 no.3
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    • pp.611-614
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    • 2008
  • Urea-SCR system has been known so far as one of effective after treatments for the reduction of NOx. In order to achieve better performance in SCR system, optimal geometric conditions for a urea injection system should be achieved. This research focused to visualize spray characteristics of urea injected SCR system in a heavy duty diesel engine. The experiment was conducted by varying injection pressures and flow rates of urea. The flow visualization was made by photographing techniques of CCD camera.

Characterization of SCR System for NOx Reduction of Diesel Engine (II) (디젤엔진의 질소산화물 저감을 위한 Urea SCR 시스템 특성 분석 (II))

  • Lee, Joon-Seong;Kim, Nam-Yong
    • Journal of the Korean Society for Precision Engineering
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    • v.25 no.11
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    • pp.83-89
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    • 2008
  • The Effect of Space Velocity(SV) on NOx conversion rate was performed to develop NOx reduction after-treatment system. SV is calculated from engine exhaust gas volume and SCR catalyst volume. Found the Urea injection duty of maximum efficiency for NOx conversion if increase SV, NOx Conversion rate is down. Especially, when SV is more than $110,000h^{-1}$, NOx conversion rate decrease suddenly. Same case, if SV is lower than $40,000h^{-1}$, NOx conversion rate is down. Also, the characterization of Urea-SCR system was performed. Three candidate injectors for injecting Urea were tested in terms of 속 injection rate and NOx reduction rate. The performances of SCR catalytic converter on temperature were investigated. The performance of Urea-SCR system was estimated in the NEDC test cycle with and without EGR. It was found that nozzle type injector had high NOx conversion rate. SCR catalytic converter had the highest efficiency at the temperature of $350^{\circ}C$. EGR+Urea-SCR system achieved NOx reduction efficiency of 73% through the NEDC test cycle.

A New High Pulse SCR Inverter for Utility Interactive Renewable Power Generation System (계통연계형 대체에너지 발전시스템을 위한 새로운 고펄스 SCR 인버터)

  • 정재혁;김현정;최세완;김영석;원충연
    • The Transactions of the Korean Institute of Power Electronics
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    • v.7 no.1
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    • pp.41-47
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    • 2002
  • In this paper, a new line-commutated SCR inverter for renewable power generation system is proposed. The proposed inverter system includes a 6-pulse SCR inverter and an auxiliary circuit. By the proper operation of the auxiliary circuit, the pulse number of the inverter system is increased and the output voltages and currents harmonics are significantly reduced. Analysis, control and simulation for 24-pulse operation of the proposed scheme is Presented and the experimental results from a laboratory Prototype verify the proposed theory.

Performance Evaluation of SCR System for Generator Engine on Training Ship KAYA (가야호 발전기용 SCR System의 성능 평가)

  • Jung, Suk-Ho;Jeong, Tae-Young;Hwang, Sung-Chul
    • Journal of Power System Engineering
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    • v.19 no.6
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    • pp.68-74
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    • 2015
  • NOx emission has been controlled because it is a major cause of the acid rain and effects considerably on formation and destruction of ozone. A SCR system on diesel engine is necessary to clear TierIII, because IMO(International Maritime Organization) plans on tightening regulations to TierIII at $1^{st}$ January 2016. In this study, flow analysis was accomplished with ANSYS Fluent program so that the SCR system would be retrofitted in training ship KAYA and the temperature distributions of exhaust gas in SCR sytem were investigated after it was installed. As a result, it was confirmed that pressure and velocity distributions in SCR system were depended on pipe line shapes, then it was designed as the pressure was lower. The temperature differential between 1 and 3 point was $15^{\circ}C$ because of evaporative latent heat of urea and the temperature of 4 point after catalyst was increased by $5^{\circ}C$ than 3 point because of exothermic reaction.

Nitrogen Oxides Removal Characteristics of SNCR-SCR Hybrid System (SNCR-SCR 하이브리드 시스템의 질소산화물 제거 특성)

  • Cha, Jin Sun;Park, Sung Hoon;Jeon, Jong-Ki;Park, Young-Kwon
    • Applied Chemistry for Engineering
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    • v.22 no.6
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    • pp.658-663
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    • 2011
  • The SNCR-SCR (selective non-catalytic reduction-selective catalytic reduction) hybrid system is an economical NOx removal system. In this study, the effect of the operating parameters of the SNCR-SCR hybrid system on NOx removal efficiency was investigated. When the SNCR reactor was operated at a temperature lower than the optimum temperature ($900{\sim}950^{\circ}C$), an additional NO removal is obtained basesd on the utilization of $NH_3$ slip. On the other hand, the SNCR reactor operated above the temperature resulted in no additional NO removal of SCR due to decomposition of $NH_3$. Therefore, the SNCR process should be operated at optimum temperature to obtain high NO removal efficiency and low $NH_3$ slip. Thus, it is important to adjust NSR (normalized stoichiometric ratio) so that $SR_{RES}$ can be maintained at an appropriate level.

The Effect of Additive Catalyst according to Thermal Aging of Vanadia SCR (Vanadia SCR의 열적 열화에 따른 조촉매의 영향)

  • Seo, Choong-Kil
    • Journal of Power System Engineering
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    • v.18 no.3
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    • pp.14-19
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    • 2014
  • The purpose of the study is to investigate the effect of additive catalyst according to the thermal aging of vanadia SCR catalysts. At a fresh condition, the $3V_2O_5-5WO_5-92TiO_2$ SCR showed the highest NOx conversion rate of about 30%, the performance of 5 kinds of SCR to which additive catalysts were added was not improved due to the insignificant effect of acid site control. For catalysts aged for 12h at $700^{\circ}C$, the SCR to which 3wt% Zeolite was added decreased in NOx conversion rate by 2.5% on average compared to the fresh SCR, it showed higher thermal durability than other additive catalyst. For 3Zeolite with high performance of NOx conversion rate during thermal aging, the Zeolite with stronger durability at a high temperature than other 5 kinds of SCR catalysts decreased the sintering of catalysts.

The Effects of Zeolite Structure and Ion-exchange Material on NH3-SCR Reaction (제올라이트 종류 및 이온교환 물질에 따른 NH3-SCR 촉매 반응 특성)

  • Hwang, Inhye;Lee, Junho;Kim, Hongsuk;Jeong, Youngil
    • Transactions of the Korean Society of Automotive Engineers
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    • v.22 no.1
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    • pp.135-141
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    • 2014
  • $NH_3$-SCR has high NOx removal efficiency approximately 80~90%. Recently, the copper or iron ion-exchanged zeolite catalysts are widely used as automobile SCR catalysts. In this paper, the effect of the space velocity, temperature of reaction and $NO_2$ addition on the $NH_3$-SCR reaction were studied using various zeolite SCR catalysts. The test was conducted with small sized fresh catalysts in a laboratory fixed-bed flow reactor system using simulated gases. It is found that the activity of the BEA is better than MFI. It seems that three-dimensional framework and a wide pore entrance of BEA enhances the SCR activity. It is also found that low temperature activity of Cu-zeolites was better than Fe-zeolites. Once $NO_2$ was added, the NOx conversion activity of the Cu-zeolite was slightly enhanced, whereas remarkable improvement was achieved by Fe-zeolite.

Preliminary Study on Factor Technology of Selective Catalytic Reduction System in Marine Diesel Engine (선박용 디젤엔진 SCR 시스템 요소 기술에 관한 기초 연구)

  • Park, Yoon-Yong;Song, Ha-Cheol;Ahn, Gi-Ju;Shim, Chun-Sik
    • Journal of Navigation and Port Research
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    • v.40 no.4
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    • pp.173-181
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    • 2016
  • From 2016, controls on reduction of NOx and SOx emissions from the vessels that are operated in the emission control area were tightened. The selectivity catalytic reduction system of the denitrification equipment which NOx among the above controlled materials is very effective and used commercially very much. But it has the disadvantage that CSR is activated at high temperatures. Therefore, the SCR and SCR activation instrument that can react even at low temperatures by using micro-nano bubbles so that the above problems can be minimized were developed. And the computational fluid dynamics technique was used by ANSYS-CFX package to prepare the plan that improves the SCR system's efficiency. Simulation for the viscous flow analysis of the SCR system was executed by applying the Navier-Stokes equation to it as a governing equation. For the SCR system's shape, 3D modeling was done by using CATIA V5. SCR jet nozzle's position was checked by changing it to the intervals of 1/3, 1/2, and 2/3 from the inlet of the vent pipe to compare the SCR system's efficiency. And the number of nozzles was compared and analyzed by simulating 4, 6, and 8 holes to check an effect of the number on the SCR system's efficiency. The simulation result has found that the closer nozzles are to the inlet of the vent pipe and the more nozzles are, the more efficiency is improved.

The Development and Implementation of Model-based Control Algorithm of Urea-SCR Dosing System for Improving De-NOx Performance and Reducing NH3-slip (Urea-SCR 분사시스템의 DeNOx 저감 성능 향상과 NH3 슬립저감을 위한 모델 기반 제어알고리즘 개발 및 구현)

  • Jeong, Soo-Jin;Kim, Woo-Seung;Park, Jung-Kwon;Lee, Ho-Kil;Oh, Se-Doo
    • Transactions of the Korean Society of Automotive Engineers
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    • v.20 no.1
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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.