Spraying and Mixing Characteristics of Urea in a Static Mixer Applied Marine SCR System

Jaehwan Jang, Sangkyung Na, Heehwan Roh, Seongyool Ahn and Gyungmin Choi
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Jaehwan Jang: School of Mechanical Engineering, Pusan National University, Busandaehak-ro 63beon-gil 2, Geumjeong-gu, Busan 46241, Korea
Sangkyung Na: School of Mechanical Engineering, Pusan National University, Busandaehak-ro 63beon-gil 2, Geumjeong-gu, Busan 46241, Korea
Heehwan Roh: STX Engine Co., Ltd., Gongdan-ro 474 36 beon-gil, Seongsan-gu Changwon, Gyengsangnamdo 51574, Korea
Seongyool Ahn: Consortium for Research Engineer Education for Next Generation Smart Appliance, Pusan National University, Busandaehak-ro 63beon-gil 2, Geumjeong-gu, Busan 46241, Korea
Gyungmin Choi: School of Mechanical Engineering, Pusan National University, Busandaehak-ro 63beon-gil 2, Geumjeong-gu, Busan 46241, Korea

Energies, 2021, vol. 14, issue 18, 1-12

Abstract: The most effective de-NOx technology in marine diesel applications is the urea-based selective catalytic reduction (SCR) system. The urea-SCR system works by injecting a urea solution into exhaust gas and converting this to NH 3 and CO 2 . The injection, mixing, and NH 3 conversion reaction behavior of the urea-water solution all have a decisive effect on the performance of the system. To improve de-NOx efficiency, it is important to provide enough time and distance for NH 3 conversion and uniform distribution prior to the solution entering the catalyst. In this study, therefore, the characteristics of gas flow, NH 3 conversion, and its distribution are investigated with a static mixer by means of numerical methods, providing a special advantage to ship manufacturing companies through the optimization of the urea-SCR system. The results show that the inclusion of the mixer induces strong turbulence and promotes the NH 3 conversion reaction across a wider region compared to the case without the mixer. The mean temperature is 10 °C lower due to the activated endothermic urea-NH 3 conversion reaction and the NH 3 concentration is 80 PPM higher at 1D than those without the mixer. Moreover, the uniformity of NH 3 distribution improved by 25% with the mixer, meaning that the de-NOx reaction can take place across all aspects of the catalyst thus maximizing performance. In other words, ship manufacturing companies have degrees of freedom in designing post-processing solutions for emissions by minimizing the use of the reduction agent or the size of the SCR system.

Keywords: marine urea-SCR system; static mixer; numerical simulation; NH 3 conversion ratio; uniformity of NH 3 (search for similar items in EconPapers)
JEL-codes: Q Q0 Q4 Q40 Q41 Q42 Q43 Q47 Q48 Q49 (search for similar items in EconPapers)
Date: 2021
References: View references in EconPapers View complete reference list from CitEc
Citations: View citations in EconPapers (1)

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