Korean Chemical Engineering Research

The Korean Institute of Chemical Engineers (한국화학공학회)
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Computational Fluid Dynamics(CFD) Simulation for a Pilot-scale Selective Non-catalytic Reduction(SNCR) Process Using Urea Solution

요소용액을 이용한 파일럿규모 SNCR 공정에 대한 CFD 모델링 및 모사

  • Nguyen, Thanh D.B. (FACS Lab., RCCT, Department of Chemical Engineering, Hankyong National Univeristy) ;
  • Kang, Tae-Ho (FACS Lab., RCCT, Department of Chemical Engineering, Hankyong National Univeristy) ;
  • Lim, Young-Il (FACS Lab., RCCT, Department of Chemical Engineering, Hankyong National Univeristy) ;
  • Kim, Seong-Joon (Department of Environmental Engineering, Kwangwoon University) ;
  • Eom, Won-Hyeon (Department of Environmental Engineering, Kwangwoon University) ;
  • Yoo, Kyung-Seun (Department of Environmental Engineering, Kwangwoon University)
  • 뉘엔타인 (한경대학교 화학공학과 화학기술연구소 FACS 연구실) ;
  • 강태호 (한경대학교 화학공학과 화학기술연구소 FACS 연구실) ;
  • 임영일 (한경대학교 화학공학과 화학기술연구소 FACS 연구실) ;
  • 김성준 (광운대학교 환경공학과) ;
  • 엄원현 (광운대학교 환경공학과) ;
  • 유경선 (광운대학교 환경공학과)
  • Received : 2008.01.28
  • Accepted : 2008.07.14
  • Published : 2008.10.31
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Abstract

The selective non-catalytic reduction(SNCR) performance is sensitive to the process parameters such as flow velocity, reaction temperature and mixing of reagent(ammonia or urea) with the flue gases. Therefore, the knowledge of the velocity field, temperature field and species concentration distribution is crucial for the design and operation of an effective SNCR injection system. In this work, a full-scale two-dimensional computational fluid dynamics(CFD)-based reacting model involving a droplet model is built and validated with the data obtained from a pilot-scale urea-based SNCR reactor installed with a 150 kW LPG burner. The kinetic mechanism with seven reactions for nitrogen oxides($NO_x$) reduction by urea-water solution is used to predict $NO_x$ reduction and ammonia slip. Using the turbulent reacting flow CFD model involving the discrete droplet phase, the CFD simulation results show maximum 20% difference from the experimental data for NO reduction. For $NH_3$ slip, the simulation results have a similar tendency with the experimental data with regard to the temperature and the normalized stoichiometric ratio(NSR).

질소산화물($NO_x$) 저감을 위한 선택적 무촉매 환원(SNCR; selective non-catalytic reduction) 공정의 성능은 유속, 반응온도 그리고 반응물간의 혼합과 같은 공정변수에 민감하다. 따라서 효율적인 SNCR 공정의 설계와 운전을 위하여 속도장, 온도장, 및 화학물질들의 농도 분포에 대한 이해가 필수적이다. 본 연구에서는 150 kW LPG 버너가 장착되고, 요소용액을 환원제로 사용하는 파일럿 규모 SNCR 공정에 대하여 액적모델과 결합된 2차원 난류반응흐름 전산유체역학(CFD; computational fluid dynamics) 모델을 개발하고, 이 모델은 실험결과를 통하여 검증된다. 난류반응 CFD 모델에서는 $NO_x$저감율과 $NH_3$-slip을 예측하기 위하여 7개 반응식으로 이루어진 요소용액과 $NO_x$와의 반응기작을 이용한다. 이러한 모델을 이용한 CFD 모사결과는 온도와 NSR(normalized stoichiometric ratio)에 따른 $NO_x$ 저감율에서 실험결과와 최대 20% 이내에서 차이를 보여주고 있으며, $NH_3$-slip에 대하여는 실험결과와 모사결과 사이에 유사한 경향성을 얻었다.

Keywords

Acknowledgement

Grant : The Eco-technopia 21 Project

Supported by : Korea Ministry of Environment

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