요소수를 이용하는 SNCR과 SCR의 탈질 특성 비교 연구

최경구(Gyung-Goo Choi),길상인(Sang-In Keel),이정규(Jung-Kyu Lee),허필우(Pil-Woo Heo),윤진한(Jin-Han Yun) 한국에너지기후변화학회 2018 에너지기후변화학회지 Vol.13 No.2

This research examined the reduction of NO by applying SCR(selective catalytic reduction) and SNCR(selective non-catalytic reduction) methods in oxy-fuel circulating fluidized bed combustion. The SO₂ reduction was also investigated by applying the FGC(flue gas condenser) for the dry flue gas recirculation. Especially, the effects of furnace (~803–951°C) and SCR reactor (~250–351°C) temperatures on the NO reduction were observed. The SNCR method could reduce the NO concentration in flue gas from ~168–172 to ~18–51 ppm, and the optimal combustion temperature was ~854°C. As the combustion temperature was ~803°C, the NH₃ slip was occured to the SCR reactor and further reduction of NO in SCR reactor was appeared. Through this phenomenon, the possibility was confirmed that the induced NH₃ slip at SNCR method can be used in SCR reactor for NO reduction. So, the simultaneous application of the SNCR and SCR method can accomplish the reduction agent saving for NO<SUB>x</SUB> reduction. On the other hand, the FGC using only water showed excellent performance for SO₂ reduction. It could reduce the SO₂ concentration in flue gas from ~253–276 to ~0 ppm. The SCR method was able to reduce the NO concentration in flue gas from ~169–174 to ~25–38 ppm and the optimal SCR reactor temperature was ~302°C. The SCR method achived better NO reduction performance than SNCR method. At the condition that urea solution injected as NH₃/NO ratio of ~2, NO reduction effieicy of SCR method was calculated to ~20% better than SNCR method.

시멘트 산업에서의 질소산화물 저감 기술 동향

서준형,김영진,조계홍,조진상,한경호,윤도영 한국자원리싸이클링학회 2020 資源 리싸이클링 Vol.29 No.6

In the cement industry, NOx emission is recognized as an important problem, and NOx reduction technologies can be divided into process change, staged combustion, low NOx burner, selective non-catalytic reduction and selective catalytic reduction method. The operation of the selective non-catalytic reduction method, which is the most used in the cement industry, is expected to make it difficult to meet the emission standards to be strengthened in the future, and it is necessary to improve equipment such as SCR and secure technologies. Recently, we are developing technologies for simultaneous application of SNCR and SCR, dust and denitrification filter technology, and removal technology using NO oxidation. 시멘트 산업에서 질소산화물 배출은 중요한 문제로 인식되고 있으며 이를 저감하는 기술은 공정변경, 단계적 연소, 저 NOx 버너, SNCR, SCR로 나눌 수 있다. 이중 시멘트 산업에서 가장 많이 사용되고 있는 SNCR 운영만으로는 향후 강화될 배출허용기준을 만족시키기 어려울 것이 예상되며 SCR 등의 추가적인 장비 개선 및 기술 확보가 필요한 상황이다. 이에 따라 최근에는 국외를 중심으로 SNCR 및SCR 동시 적용 기술, 분진 및 탈질 필터 기술과 NO 산화를 이용한 제거기술 등을 개발하고 있다.

SNCR 시스템 내부의 물질 반응에 관한 전산해석적 연구

구성모,유경선,장혁상 한국청정기술학회 2019 청정기술 Vol.25 No.1

Numerical analysis was done to evaluate the chemical reaction and the reduction rate inside of selective non-catalyticreduction to denitrification in combustion process. The NOX reduction in selective non-catalytic reduction is converted to notonly nitrogen but also nitrous oxide. Simultaneous NOX reduction and nitrous oxide generation suppressing is required inselective non-catalytic reduction because nitrous oxide influences the global warming as a greenhouse gas. The current study wasperformed compare the computational analysis in the same temperature and amount of NaOH, and in comparison with theprevious research experiments and confirmed the reliability of the computational fluid dynamics. Additionally, controlling theaddition amount of NaOH to predict the NOX reduction efficiency and nitrous oxide production. Numerical analysis was done tocheck the mass fraction of each material in the measurement point at the end of selective non-catalytic reduction. ExperimentalValue and simulation value by numerical analysis showed an error of up to 18.9% was confirmed that a generally well predicted. and it was confirmed that the widened temperature range of more than 70% NOX removal rate is increased when the additionamount of NaOH. So, large and frequent changes of the reaction temperature waste incineration facilities are expected to be effective. 연소공정 내에서 질소산화물 배출을 저감하는 선택적 무촉매 환원장치 내부의 화학반응 및 저감효율에 대한 수치해석이 실행되었다. 선택적 무촉매 환원장치에서 저감된 질소산화물은 질소뿐만 아니라 아산화질소로도 전환된다. 아산화질소는 온실가스로써 지구온난화에 영향을 끼치기 때문에 선택적 무촉매 환원장치 내의 질소산화물 제어와 동시에 아산화질소 생성제어가 요구되어진다. 본 연구에서는 선행연구에서 실행된 실험과 온도조건과 가성소다의 첨가량이 동일한 선택적 무촉매환원장치 내의 전산해석을 실시하고 비교하여 전산해석의 신뢰성을 확인하고, 가성소다 첨가량을 추가적으로 조절하여 질소산화물의 저감 효율과 아산화질소 생성량을 예측하였다. 전산해석은 후단의 측정점을 설정하여 각 물질의 질량분율을 확인하였다. 세부적으로는 측정점에서 유동방향에 수직한 면을 설정하여 온도 조건과 가성소다 첨가량에 따른 각 물질의 평균 질량분율을 비교하였다. 실험값과 전산해석에 의한 모사값은 최대 18.9%의 오차를 보이며 대체적으로 잘 예측됨을 확인하였으며 가성소다 첨가량을 증가시켰을 땐 70% 이상의 제거율의 온도 범위가 넓어지는 것을 확인하였다. 따라서 반응온도의 낙차가 크고 잦은 폐기물 소각시설 등에서 효과적일 것으로 예상된다.

미세먼지 저감 시멘트 공정 중 화합물 대체연료에 의한 발생분진 속 수용성 질산 이온 저감효과

김상현,이현석 한국물리학회 2021 새물리 Vol.71 No.2

Fossil fuels in the cement manufacturing process generate dust including water-soluble salts during heating process. The nitrate and the sulfate components in the dust enter into the selective non-catalytic reduction facility and react with water containing urea, resulting in the formation of by-products such as sulfuric and nitric acids which may cause corrosion of the facility. Although wastes replace some parts of fossil fuels in the process, the risks from alternative fuels have yet to be systematically reported. Here, we investigate the correlation between alternative fuels in the heating process and the synthesized water-soluble components of dust. After three aromatic compounds are burned together with a cement mixture, the collected dust is made into aqueous solutions. Using ion chromatography, investigate the nitrate and sulfate ions in the aqueous solutions. As a result, the concentration of water-soluble nitrate ions in the dust is found to be lower for all aromatic compounds. We, thus, conclude that alternative fuels based on aromatic wastes can be effectively used in fine-dust-reduction cement processes. 시멘트 제조 공정 내 화석연료는 가열 시 수용성 염을 포함한 분진을 생성한다. 분진의 질산염과황산염 성분은 선택적 비촉매 환원 설비에 유입 후 요소수와 반응하여 황산 및 질산으로 바뀌어설비의 부식을 초래할 수 있다. 비록 공정 중 폐기물이 화석연료 일부를 대체하지만 대체 연료에의한 위해 요소는 구체적으로 보고된 바가 없다. 본 연구에서는 이러한 가열공정에 투입된 대체연료와 발생분진의 수용성 성분에 미치는 상관관계를 조사하였다. 3가지의 방향족 화합물을 시멘트혼합물과 함께 연소시킨 후 발생하는 분진을 포집하여 수용액으로 만든 후, 이온 크로마토그래피분석법을 이용하여 수용액 속 질산이온 및 황산이온을 검출하였다. 그 결과 3가지 방향족 화합물모두에서 분진 속 수용성 질산이온 함량이 감소하는 효과를 보였다. 이를 통해 방향족 화합물에 기반한 폐기물 대체 연료가 미세먼지 저감을 위한 시멘트 공정에 효과적으로 사용될 수 있다는 결론을 도출할 수 있다.

생활폐기물 소각장 2차 연소로에서 요소용액을 이용한 선택적무촉매환원 공정에 대한 전산유체역학 모사 및 현장 검증

강태호 ( Tae Ho Kang ),뉘엔타인 ( Thanh D. B. Nguyen ),임영일 ( Young Il Lim ),김성준 ( Seong Joon Kim ),엄원현 ( Won Hyeon Eom ),유경선 ( Kyung Seun Yoo ) 한국화학공학회 2009 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.47 No.5

보문 : 공정시스템,이동현상,화학공정안전 ; 요소용액을 이용한 파일럿규모 SNCR 공정에 대한 CFD 모델링 및 모사

뉘엔타인 ( Thanh D. B. Nguyen ),강태호 ( Tae Ho Kang ),임영일 ( Young Il Lim ),김성준 ( Seong Joon Kim ),엄원현 ( Won Hyeon Eom ),유경선 ( Kyung Seun Yoo ) 한국화학공학회 2008 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.46 No.5

IMPROVEMENT OF NOX REDUCTION RATE OF UREA SCR SYSTEM APPLIED FOR AN NON-ROAD DIESEL ENGINE

Joonsoo Han,Taemin Kim,Haksup Jung,Sukang Pyo,조규백,Youngtaig Oh,김홍석 한국자동차공학회 2019 International journal of automotive technology Vol.20 No.6

Urea SCR technology has been widely used to reduce NOx emissions of diesel engines. Despite remarkable development for decades, more advanced control and optimization of urea SCR systems are still required as global NOx emissions standards are expected to become more stringent. This study investigated several influential parameters of urea SCR system to improve NOx reduction efficiency. This study uses a commercialized UWS (Urea Water Solution) supply system and a SCR catalyst which was installed in the exhaust line of a non-road CRDI (Common Rail Direct Injection) diesel engine. From this study, it was found that the low space velocity of SCR catalyst is essential for high NOx reduction efficiency, especially at low temperatures. Early injection of UWS enhances the overall NOx reduction efficiency if UWS injection was carefully controlled to avoid urea deposits. Rich injection of UWS with AOC is a good strategy for high NOx reduction efficiency. However, NOx reproduction in the AOC, which has an adverse effect on the overall NOx reduction rate, occurs at high exhaust gas temperatures. System insulation also can improve the NOx reduction efficiency by a few percentage points.

연소 배기가스 탈질용 하이브리드공정 및 촉매필터의 연구동향

박노국(No-Kuk Park),권병찬(Byung Chan Kwon),이승우(Seung Woo Lee),강도형(Dohyung Kang),이장훈(Jang Hun Lee),황상연(Sang Yeon Hwang),서명조(Myung Jo Seo) 한국에너지기후변화학회 2020 에너지기후변화학회지 Vol.15 No.1

This study has reviewed the current state of knowledge for upgrading the denitrification process to remove nitrogen oxides in the exhaust gas, which is known as a source of ultra-fine dust. In order to upgrade the denitrification process, the hybrid-type denitrification has been considered where the selective non-catalytic reduction (SNCR) is combined with the selective catalytic reduction (SCR) process at a high temperature. Although SCR technology is a mature technology with high denitrification efficiency, it is difficult to be applied to a small-scale process when considering the capital and operating costs for reducing ultra-fine dust. Therefore, it is necessary to minimize the operating cost by applying denitrification technology to the dust collection process, and the development of technology to use a catalyst in the filter bag is required. However, in order to activate the denitrification catalyst in the filter bag, there are some technical problems to be solved: the optimization of the catalyst composition that can be operated at low temperature and the prevention of fall-off of the catalyst in the removing step of collected dust on the filter by high-pressure backwashing. If these technical issues are solved, the hybrid denitrification process can be applied to the industry for the advancement of denitrification technology.

생활폐기물 소각시 운전 조건에 따른 배출가스 저감 특성

최석주 ( Seok-ju Choe ),윤형선 ( Hyung-sun Yoon ),서성규 ( Seong-gyu Seo ) 한국환경기술학회 2018 한국환경기술학회지 Vol.19 No.3

본 연구에서는 열분해 소각시설에 대하여 운전 조건에 따른 배출가스 특성을 파악하였다. 소각대상은 생활폐기물로써 폐기물의 삼성분은 수분 33.8 %, 가연분 55.6 %, 회분 10.6 %이며, 소각온도는 약 1,000 ℃, 산소 농도는 약 12 %에서 최적의 연소 조건으로 나타났다. 선택적비촉매환원법(SNCR)의 요소수 분사 공정에서 NOx의 경우 1,000 ℃에서 최대 효율을 나타내었고 1,100℃ 이상에서 Thermal NOx의 발생으로 농도가 급격하게 증가하였다. 최적 연소 조건(1,000 ℃, 12 %)에서 대기오염 방지시설 전·후의 배출 농도 분석 결과, 제거효율은 Dust(96.4 %), NOx(60.1 %), SOx(67.3 %), CO(38.8 %), NH₃(46.7 %), HCl(66.7 %)로 나타났다. This study, the characteristics of emission gas according to the operating conditions of pyrolysis incinerator were analyzed. The incinerator was the municipal waste. The wastes were 33.8 % moisture, 55.6 % combustible and 10.6 % ash, and the incineration temperature was about 1,000 ℃ and the oxygen concentration was about 12 %. In the urea water injection process of the SNCR(Selective Non-Catalytic Reduction) process, NOx showed maximum efficiency at 1,000 ℃, and the concentration increased rapidly due to the generation of thermal NOx at above 1,100 ℃. The removal efficiencies of Dust (96.4 %), NOx (60.1 %), SOx (67.3 %) and CO (38.8 %) were measured before and after the air pollution prevention facilities in the optimal combustion condition (1,000 ℃, 12 % NH3 (46.7 %) and HCl (66.7 %).

순산소 순환유동층에서 로내 탈황 및 탈질법 적용에 따른 오염물질 거동특성

최경구(Gyung-Goo Choi),나건수(Geon-Soo Na),신지훈(Ji-Hoon Shin),길상인(Sang-In Keel),이정규(Jung-Kyu Lee),허필우(Pil-Woo Heo),윤진한(Jin-Han Yun) 한국청정기술학회 2018 청정기술 Vol.24 No.3

순산소 연소기술은 화력발전에 적용 가능한 유망한 온실가스 감축 기술로 평가되고 있다. 본 연구는 환경적 관점에서 순환유동층을 활용한 순산소 연소조건에 로 내 탈황 및 탈질법을 적용하여 NO 및 SO₂의 거동을 살펴보는 한편, SO₃, NH₃, 그리고 N2O의 발생 경향도 관측하였다. 이를 위해, 연소로 내 석회석 및 요소수를 투입하였다. 로 내 탈황법은 연소가스 내 SO₂ 농도를 ~403에서 ~41 ppm까지 저감하였다. 또한 SO₃ 형성의 주원료인 SO₂가 저감되면서 연소가스 내 SO₃ 농도도 ~3.9에서~1.4 ppm까지 감소되었다. 그러나 석회석 내 CaCO₃가 NO의 발생을 촉진하는 현상도 관측되었다. 연소가스 내 NO 농도는로 내 탈질법을 적용하여 ~26 - 34 ppm까지 저감되었다. 요소수 투입량 증가에 따라 연소가스 내 NH₃ 농도가 증가하여 최대~1.8 ppm으로 나타났으며, N₂O의 농도도 ~61에서 ~156 ppm까지 증가하였다. N₂O 발생량 증가 현상은 요소수의 열분해 과정에서 생성된 HNCO가 N₂O로 전환되어 나타난다. 본 연구의 결과를 통해 로 내 연소가스 세정법을 적용할 경우 NOx 및 SOx의 저감뿐만 아니라, 다른 오염물질의 발생에 대한 주의가 필요할 것으로 보인다. Oxy-fuel combustion is considered as a promising greenhouse gas reduction technology in power plant. In this study, the behaviors of NO and SO₂ were investigated under the condition that in-furnace deNOx and deSOx methods are applied in oxy-fuel circulating fluidized bed combustion condition. In addition, the generation trends of SO₃, NH₃ and N2O were observed. For the purpose, limestone and urea solution were directly injected into the circulating fluidized bed combustor. The in-furnace deSOx method using limestone could reduce the SO₂ concentration in exhaust gas from ~403 to ~41 ppm. At the same experimental condition, the SO₃ concentration in exhaust gas was also reduced from ~3.9 to ~1.4 ppm. This trend is mainly due to the reduction of SO₂. The SO₂ is the main source of the formation of SO₃. The negative effect of CaCO₃ in limestone, however, was also appeared that it promotes the NO generation. The NO concentration in exhaust gas reduced to ~26 - 34 ppm by appling selective non-catalytic reduction method using urea solution. The NH₃ concentration in exhaust gas was appeared up to ~1.8 ppm during injection of urea solution. At the same time, the N₂O generation also increased with increase of urea solution injection. It seems that the HNCO generated from pyrolysis of urea converted into N₂O in combustion atmosphere. From the results in this study, the generation of other pollutants should be checked as the in-furnace deNOx and deSOx methods are applied.