NOx Emission Reduction Technology for Marine Engine Based on Tier-III: A Review

• Published in: Journal of thermal science Vol. 29; no. 5; pp. 1242 - 1268
• Main Authors: Lu, Xiuwei, Geng, Peng, Chen, Yunyue
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01-10-2020; Springer Nature B.V
• Subjects: Chemical reduction; Classical and Continuum Physics; Combustion control; Consumption; Diesel engines; Emission standards; Emissions control; Engineering Fluid Dynamics; Engineering Thermodynamics; Engines; Exhaust gases; Fuel consumption; Heat and Mass Transfer; Low pressure; Marine engines; Marine technology; Nitrogen oxides; Optimization; Physics; Physics and Astronomy; Selective catalytic reduction; Superchargers; Wastewater; NO; selective catalytic reduction (SCR); dual-fuel; emission; Tier-III; exhaust gas recirculation (EGR); marine engine
• ISSN: 1003-2169; 1993-033X
• DOI: 10.1007/s11630-020-1342-y

The development of maritime trade has greatly promoted the development of diesel engines. However, with the increasingly serious environmental problems, more and more attention has been paid to the exhaust emissions of high-power marine diesel engines. The restrictions on SO
x
have been implemented globally, and the limitation of the NO
x
will be the next priority. This paper illustrates (a) Principle and research progress of NO
x
emissions-reduction technology of marine diesel engine; (b) Summary of advantages and disadvantages among various reduction technologies and their reduction effects; (c) The application effect of mainstream technology on board. Firstly, since exhaust gas recirculation (EGR) can achieve Tier-III directly from Tier-I without considering the increased fuel consumption. It is deemed as the most promising technology to reduce emissions by controlling combustion condition. However, EGR has shortcomings of excessive increase in fuel consumption and generation of waste water, which need to be solved immediately. Secondly, selective catalytic reduction (SCR) is the most effective and straightforward means to achieve Tier-III. Despite of the continuous optimization of SCR unit volume, the problem of scrap catalyst seriously limits its wide application. How to match the supercharger more efficiently is a key factor in choosing between high and low pressure SCR. Thirdly, nature gas (NG) engines are capable of achieving a reduction in NO
x
, but in order to meet the requirements of Tier-III, it still needs to be assisted by other technologies. The emissions of hydrocarbon (HC) and CO in NG engines are huge defects that must be solved. Lastly, technologies such as the Miller cycle, Two-stage supercharging and mixed-water combustion can also reduce emissions but were rarely used alone. These technologies can be combined with EGR, SCR and NG engines to optimize the engines’ economy and emission characteristics.