Simulation study of De-NO_x and ammonia slip with two-stage selective catalytic reduction for diesel engine

ABSTRACT

Selective catalytic reduction (SCR) technology has several benefits for reducing NO_x. It offers significant NO_x removal efficiency, often greater than 90%. Due to increasingly strict pollution rules, SCR catalysts have lately been installed in diesel engines all over the world. The dynamics and economy of the original diesel engine are examined in this work concerning the addition of various SCR catalyst after-treatment methods, including a one-stage vanadium-based SCR catalyst (V-I), a two-stage vanadium-based SCR catalyst (V/V-II), and a two-stage vanadium-based-copper-based SCR catalyst (V/Cu-II). A complete engine model of a marine diesel engine is built on this model. The findings indicate that each of the three layouts decreases diesel engine power and raises fuel consumption rates. The V/Cu-II is the best configuration for this kind of marine machine because the V-I satisfies the most recent Tier III NO_x emission limits only at 100% load, the V/V-II satisfies them at 75% to 100% load, and the V/Cu-II satisfies them at 50% to 100% load. For all three arrangements, ammonia slip reduces with increasing load, with the V/Cu-II having the lowest ammonia slip. In the end, it was determined for the V/Cu-II how different ammonia-to-nitrogen ratios affected ammonia slip and NO_x conversion. The results revealed that with an ammonia-to-nitrogen ratio of 0.7, both the ammonia slip and NO_x emission limits could be reached at 50% to 100% load, saving urea expenditures.

Highlights

1、The combined two-stage SCR has been configured.

2、The V/Cu-II SCR has the highest De-NO_xefficiency.

3、The V/Cu-II SCR meets both NO_xemission and NH₃ slip limits at 0.7 NSR.

KEYWORDS:

• Diesel engines
• selective catalytic reduction (SCR)
• two-stage catalyst
• De-NO_x
• ammonia slip

Acknowledgements

This work was supported by the State Key Laboratory of Engines at Tianjin University (Grant No. K2021-12), and Shanghai Sailing Program (Grant No. 19YF1416700). The authors would like to express their gratitude to EditSprings (https://www.editsprings.cn) for the expert linguistic services provided.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Notes on contributors

Wei Wu

Wei Wu received her BS degree of New Energy Science and Engineering (Jul. 2018) at University of Shanghai for Science and Technology. She is a master student of School of Mechanical Engineering at Shanghai Dianji University. Her research interests focus on the emission control of diesel engines.

Hui Chen

Hui Chen received her PhD degree of Thermal Power Engineering (Dec. 2017) at Tongji University. She conducted her post-doctoral research at the State Key Laboratory of Engines at Tianjin University. She is a teacher of Vehicle Engineering at the School of Mechanical Engineering at Shanghai Dianji University. Her research interests focus on the low carbon combustion of clean energy.

Liping Geng

Liping Geng received her PhD degree of School of Energy and Power Engineering at University of Shanghai for Science and Technology. She is an associate professor of School of Mechanical Engineering at Shanghai Dianji University. Her research interests focus on the flow and heat transfer.

Liwei Mao

Liwei Mao received his PhD degree of the State Key Laboratory of Engines at Tianjin University. He is a senior engineer of School of Mechanical Engineering at Shanghai Dianji University. His research interests focus on the combustion of engines.

Yuzhu Cao

Yuzhu Cao is a master student of School of Mechanical Engineering at Shanghai Dianji University. Her research interests focus on the the combustion of engines.

Yusheng Ju

Yusheng Ju received his PhD degree of the State Key Laboratory of Engines at Tianjin University. He is a professor of School of Mechanical Engineering at Shanghai Dianji University. His research interests focus on the combustion of engines and fuel injection systems.

Luan Zang

Luan Zang is a engineer of Wuxi Fuel Injection Equipment Research Institute, China FAW Group Co., LTD.. His research interests focus on the fuel injection systems.