• Title/Summary/Keyword: selective non-catalytic reduction (SNCR)

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Release of Ammonia Odor from AAFA (Ammonia Adsorbed Fly Ash) by Installation of NOx Reduction System

  • Kim, Jae-kwan;Park, Seok-un;Lee, Hyun-dong;Chi, Jun-wha
    • KEPCO Journal on Electric Power and Energy
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    • v.2 no.3
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    • pp.437-445
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    • 2016
  • This paper discussed the effect of ammonia concentration adsorbed on fly ash for the ammonia emission as AAFA (Ammonia Adsorbed Fly Ash) produced from coal fired plants due to operation of NOx reduction technologies was landfilled with distilled or sea water at closed and open systems, respectively. Ammonia bisulfate and sulfates adsorbed on fly ash is highly water soluble. The pH of ammonium bisulfate and sulfate solution had significant effect on ammonia odor emission. The effect of temperature on ammonia odor emission from mixture was less than pH, the rate of ammonia emission increased with increased temperature when the pH conditions were kept at constant. Since AAFA increases the pH of solution substantially, $NH_3$ in the ash can release the ammonia order unless it is present at low concentration. $NH_4{^+}$ ion is unstable in fly ash and water mixtures of high pH at open system, which is changed to nitrite or nitrate and then released as ammonia gas. The proper conditions for < 20 ppm of ammonia concentration released from the AAFAs landfilled in ash pond were explored using an open system with sea water. It was therefore proposed that optimal operation to collect AAFA of less than 168 ppm ammonia at the electrostatic precipitator were controlled to ammonia slip with less than 5 ppm at SCR/SNCR installations, and, ammonia odor released from mixture of fly ash of 168 ppm ammonia with sea water under open system has about 20 ppm.

Improvement of DeNOx efficiency of SNCR Process with Chemical Additives in Urea Soution (환원제로 우레아를 사용하는 SNCR 공정에서 첨가제 적용에 따른 탈질효율 향상 연구)

  • Yoo, Kyung Seun;Park, Sung Woo
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.18 no.10
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    • pp.663-668
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    • 2017
  • Dye waste water generated in the dye industry is categorized as hazardous waste water that requires appropriate treatment. The pilot scale experimental trials were carried out using dye waste water as an effective additive for the selective non-catalytic reduction (SNCR) of NOx in combustion flue gases. The additives were waste liquor obtained from the dye industry and several purification steps were taken to make a standardized reagents. The dye waste water was shown to possess valuable SNCR qualities (at least 87% NOx reduction efficiency) considering its availability as a waste product, which has to be strictly treated, and have little effects on CO removal. The results indicated that the NO removal efficiency increased first and then decreased with increasing temperature within $750-1150^{\circ}C$. The maximum NO reduction efficiency was approximately 87% at the optimal reaction temperature. A more than 10% increase in NO reduction was achieved in the presence of 1000 ppm Na-additives (dye waste water) compared to that without additives. The Na-based additives have also a significant promoting effect on $N_2O$ reduction and within the SNCR temperature window.

NH3-based SNCR of NOx : Experimental and Simulation (NH3 SNCR을 이용한 NOx 제거 : 실험 및 모사)

  • Cha, Jin Sun;Park, Sung Hoon;Jeon, Jong-Ki;Park, Young-Kwon
    • Applied Chemistry for Engineering
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    • v.22 no.4
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    • pp.433-438
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    • 2011
  • In this study, effects of temperature, NSR, and oxygen concentration on the $NO_x$ removal efficiency of an SNCR process were investigated experimentally as well as numerically using CHEMKIN-II program. The NO removal efficiency increased with the reactor temperature under oxygen-free condition, whereas when the oxygen concentration was 4%, the NO removal efficiency showed a maximum value at $900{\sim}950^{\circ}C$. The pressure of oxygen was shown to enhance the NO removal at low temperature. Regardless of the oxygen concentration, the NO removal efficiency increased with NSR. The temperature and NSR-dependencies of the NO removal efficiency predicted by CHEMKIN-II simulations were similar to that of the experimental results.

Study of Additive Effects on Nitrogen Oxides Reduction for Combustion Emission Gas (소각시설에서 질소산화물 환원처리를 위한 반응제의 영향 연구)

  • 동종인;박정희;장주호;강경희;이종길
    • Proceedings of the Korea Air Pollution Research Association Conference
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    • 2003.11a
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    • pp.145-146
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    • 2003
  • 질소산화물은 천연가스, 석유, 석탄과 같은 화석연료 연소 시에 배출되는 대표적 오염물질로 산성비를 유발시키며, 오존, PAN, aldehyde와 같은 광화학 산화물을 형성하여 광화학 스모그를 유발한다. 따라서 NOx 제어의 필요성은 더욱 강조되고 있다. NOx 처리 공정 중 대표적인 SNCR(Selective Non-Catalytic Reduction)공정은 N-계열 시약(환원제)을 노내의 온도가 90$0^{\circ}C$에서 110$0^{\circ}C$인 구역으로 주입하여 NOx가 복잡한 단위반응들을 거쳐서 N2와 $H_2O$로 분해되는 저감기술의 하나로서 초기 설치비가 저렴하고 단기간에 쉽게 설치 가능한 기술이지만, 대부분 외국기술의 도입에 의존하고 있는 실정이므로 국내개발을 필요로 한다. (중략)

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NOx Reduction in Flue Gas Using Ammonia and Urea solution (암모니아와 요소용액을 이용한 배출가스내 질소산화물 저감 비교 평가)

  • 임영일;이정빈;유경선;김상돈
    • Proceedings of the Korea Society for Energy Engineering kosee Conference
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    • 1995.05a
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    • pp.236-239
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    • 1995
  • 50 kW$_{th}$ 용량의 기체연료버너에서 암모니아 기체와 요소용액을 이용한 선택적 무촉매 환원법 (SNCR;Selective Non-catalytic Reduction) 으로 질소산화물 (NOx) 저감에 관하여 연구하였다. 암모니아는 요소요액보다 더 낮은 반응온도에서 더 높은 효율을 보여주지만 경제성과 암모니아의 부식성 및 맹독성으로 인하여 취급하기에 곤란한 점이 있다. 반면에 요소용액은 적절한 액상첨가제와 기상첨가제를 사용하여 넓은 반응온도범위에서 높은 효율을 얻을 수 있으며 공정상의 조업비를 절감할 수 있다. 본 실험에서는 액상 첨가제인 $CH_3$OH 와 $C_2$H$_{5}$OH 을 사용하여 5$0^{\circ}C$ 정도의 최적반응온도 감소를 얻었으며 LPG 와 합성가스(CH$_4$:CO:H$_2$:$CO_2$=1:4:4:2) 틀 기상 첨가제로 사용하여 높은 질소산화물 저감 효율을 관찰하였다.

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The Effect of Hybrid Reburning on NOx Reduction in Oxygen-Enriched LPG Flame (산소부화 LPG 화염에서 혼합형 재연소 방법에 의한 NOx 저감 효과)

  • Lee, Chang-Yeop;Baek, Seung-Wook
    • Journal of the Korean Society of Combustion
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    • v.12 no.4
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    • pp.14-21
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    • 2007
  • In order to enhance combustion efficiency, oxygen-enriched combustion is used by increasing the oxygen ratio in the oxidizer. However, since the flame temperature increases, NOx formation in the furnace seriously increases for low oxygen enrichment ratio. In this case, reburning is a useful technology for reducing nitric oxide. In this research, experimental studies have been conducted to evaluate the hybrid effects of reburning/selective non-catalytic reaction (SNCR) and reburning/air staging on NOx formation and also to examine heat transfer characteristics in various oxygen-enriched LPG flames. Experiments were performed in flames stabilized by a co-flow swirl burner, which were mounted at the bottom of the furnace. Tests were conducted using LPG gas as main fuel and also as reburn fuel. The paper reported data on flue gas emissions, temperature distribution in furnace and various heat fluxes at the wall for a wide range of experimental conditions. Overall temperature in the furnace, heat fluxes to the wall and NOx generation were observed to increase by low level oxygen-enriched combustion, but due to its hybrid effects of reburning, SNCR and Air staging, NOx concentration in the exhaust have decreased considerably.

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Numerical Analysis of Urea Injection Conditions in the Selective Non-Catalytic Reduction(SNCR) Process (SNCR 공정에서 요소수 분무 조건에 관한 수치 해석)

  • Jung, Yu-Jin;Jeong, Moon-Heon;Park, Ki-Woo;Hong, Sung-Gil;Jung, Jong-Hyeon;Shon, Byung-Hyun
    • Proceedings of the KAIS Fall Conference
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    • 2012.05a
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    • pp.356-359
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    • 2012
  • SNCR 기술은 SCR에 비해 탈질 효율은 떨어지지만 촉매없이 고온 배출가스에 NH3 또는 요소수를 직접 분사하여 질소와 물로 환원시키는 방법이므로 초기 투자비 및 운영비가 적어 최근 국내 대다수의 소각장, 산업용 보일러 등에 널리 적용되고 있다. 단, SNCR 기술은 급격한 온도 강하나 접근의 불용이성, 불균일한 혼합, 액적의 증발시간 지연, 불균일한 운전 조건 등의 영향을 크게 받으며, 특히 반응 온도가 가장 중요한 변수로서 최적 반응 온도 영역대가 약 800~$1,000^{\circ}C$라는 점에서 이상적인 반응 온도 조건을 찾아서 환원제를 분무하는 것이 매우 중요하다. 이에 본 연구에서는 열유동 전산해석을 통해 스토커식 소각로의 폐기물 성상별 화염 온도 분포를 예측하고 적정 반응 온도 영역을 확인하여 요소수 주입 고도를 선정, 폐기물 성상별 분무 조건을 확립하고자 수치 해석적 연구를 수행하였다. 폐기물 성상(고질/중질/저질 폐기물)별로 화염 온도를 예측한 결과, 최적 반응 온도 영역대가 약 800~$1,000^{\circ}C$, 폐기물 성상의 심한 변화 때문에 소각로의 효율적인 연소 조건 제어에 어려움 등을 고려하여 약 700~$1,000^{\circ}C$ 온도 영역대를 환원제 분무 온도로 선정하였다. 폐기물별로 발열량에 따른 화염 온도가 모두 다르기 때문에 환원제 분무 위치를 3지점으로 선정하여 각 지점별로 분무 운전 조건을 확립하였다.

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Effects of Organic and Inorganic Additives on Selective Non Catalytic Reduction Reaction of NOx in a Pilot Scale Flow Reactor (파일럿 규모의 흐름반응기에서 유기 및 무기 첨가제가 질소산화물의 선택적 무촉매 환원반응에 미치는 영향)

  • Park, Soo Youp;Yoo, Kyung Seun;Lee, Joong Kee;Park, Young Kwon
    • Korean Chemical Engineering Research
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    • v.44 no.5
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    • pp.540-546
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    • 2006
  • Effects of organic and inorganic additives on the SNCR reaction of NOx were investigated in a pilot scale flow reactor with a variation of operating parameters. NOx reduction efficiency increased with the increase of a residence time and an initial NOx concentration. NOx reduction reaction by urea solution started to appear about 850 and then reached to maximum value around $970^{\circ}C$. NOx reduction efficiency also increased with the increase of NSR (Normalized Stoichiometric Ratio) up to 2.0. Addition of ethanol and phenol as an organic additives shifted the optimum temperature window to lower region with decreasing the maximum NOx reduction efficiency. This might be due to the side reaction of hydrocarbon in ethanol structure. NaOH addition widened the temperature window and enhanced the NOx reduction efficiency about 10% due to the chain reaction of NaOH and the reduction of $N_2O$.

A Study on Reduction of Nitrogen Oxide (NOx) and Stability of Incineration Facility by the Food Wastewater Incineration (음식물류 폐수 소각처리에 따른 질소산화물 저감 및 소각설비의 안정성 평가에 관한 연구)

  • Hwang, Seung-Min;Chung, Jin-Do;Song, Jang-Heon
    • Journal of Korean Society of Environmental Engineers
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    • v.31 no.10
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    • pp.901-908
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    • 2009
  • We examine the processing method of the food wastewater to direct spray at living waste incinerator. The demoscale stoker system is used as a incineration facility. The results show that it brings effect on the reduction of nitrogen oxide ($NO_x$) concentration as well as the ammonia ($NH_3$) amount in SNCR (selective non-catalytic reduction) by the incineration of food wastewater which is containing a plentiful ammoniac nitrogen ($NH_3$-N). Furthermore, the stability of incineration facility and the extension of operation period is actualized as a improvement of clogging phenomenon on outer wall of water pipe as the 870~$950^{\circ}C$ maintain of exit temperature in a second combustor by spray of the food wastewater. The 26 items of air pollution matter of nitrogen oxide ($NO_x$), sulfur oxide ($SO_x$) and dioxin etc. are measured. The results show that it is under the value of allowable exhaust standard.

Simultaneous Removal of NO and SO2 using Microbubble and Reducing Agent (마이크로버블과 환원제를 이용한 습식 NO 및 SO2의 동시제거)

  • Song, Dong Hun;Kang, Jo Hong;Park, Hyun Sic;Song, Hojun;Chung, Yongchul G.
    • Clean Technology
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    • v.27 no.4
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    • pp.341-349
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    • 2021
  • In combustion facilities, the nitrogen and sulfur in fossil fuels react with oxygen to generate air pollutants such as nitrogen oxides (NOX) and sulfur oxides (SOX), which are harmful to the human body and cause environmental pollution. There are regulations worldwide to reduce NOX and SOX, and various technologies are being applied to meet these regulations. There are commercialized methods to reduce NOX and SOX emissions such as selective catalytic reduction (SCR), selective non-catalytic reduction (SNCR) and wet flue gas desulfurization (WFGD), but due to the disadvantages of these methods, many studies have been conducted to simultaneously remove NOX and SOX. However, even in the NOX and SOX simultaneous removal methods, there are problems with wastewater generation due to oxidants and absorbents, costs incurred due to the use of catalysts and electrolysis to activate specific oxidants, and the harmfulness of gas oxidants themselves. Therefore, in this research, microbubbles generated in a high-pressure disperser and reducing agents were used to reduce costs and facilitate wastewater treatment in order to compensate for the shortcomings of the NOX, SOX simultaneous treatment method. It was confirmed through image processing and ESR (electron spin resonance) analysis that the disperser generates real microbubbles. NOX and SOX removal tests according to temperature were also conducted using only microbubbles. In addition, the removal efficiencies of NOX and SOX are about 75% and 99% using a reducing agent and microbubbles to reduce wastewater. When a small amount of oxidizing agent was added to this microbubble system, both NOX and SOX removal rates achieved 99% or more. Based on these findings, it is expected that this suggested method will contribute to solving the cost and environmental problems associated with the wet oxidation removal method.