Performance Optimization of High-pressure SCR System in a Marine Diesel. Part II: Catalytic Reduction and Process

  • Yuanqing Zhu
  • Rongpei Zhang
  • Song Zhou
  • Chunan Huang
  • Yongming FengEmail author
  • Majed Shreka
  • Chaolei Zhang
Original Paper


The working process of high-pressure SCR (HP-SCR) system is a kind of catalytic reaction process in the high-pressure exhaust flow, which involves urea decomposition reaction, catalytic reduction reaction of NOx and oxidizing reaction of NH3. Based on existing exhaust conditions of marine low-speed diesel engines, computational fluid dynamics (CFD) coupled with the chemical reaction kinetics, the catalytic process, and the working performance of the HP-SCR system were correspondingly studied in this paper. With the optimized scheme of the HP-SCR system, concentration uniformity, linear velocity, and total pressure loss were determined. Likewise, the concentration distribution of NH3, NO, and NO2 were obtained, and the catalytic kinetics of the NOx reduction reaction was analyzed. For the optimized scheme, the concentration of NH3 and the flow uniformity of the catalyst upwind section was met with the design requirements of the HP-SCR system, and the pressure loss of the SCR catalyst layer occupied about 40% of the total pressure loss. With NO, NO2, and NH3 existing together in the exhaust, both the standard SCR reaction and fast SCR reaction are competitive, and they mostly react along the first layer of catalyst. Finally, the weighted average value of the NOx emission behind the HP-SCR system was determined using the ISO8717 test cycle E3, and the value was 2.67 g/kWh, which met with the NOx limited requirement of the IMO Tier III.


HP-SCR system Marine low-speed diesel Working process Performance evaluation NOx conversion efficiency 



We gratefully acknowledge the financial support of the National Key Research and Development Program of China (No. 2016YFC0205400), the National Natural Science Foundation of China (No. 51509050), the Natural Science Foundation of Heilongjiang Province in China (No. QC2016058) and the Provincial Funding for National Projects of Heilongjiang Province in China (No. GX17A020).


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© Springer Science+Business Media, LLC, part of Springer Nature 2018

Authors and Affiliations

  1. 1.College of Power and Energy EngineeringHarbin Engineering UniversityHarbinPeople’s Republic of China

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