MAINTAINING THE ENVIRONMENTAL FRIENDLINESS OF SEAGOING VESSELS WHEN USING CATALYTIC REDUCTION SYSTEMS FOR MARINE DIESEL ENGINES

Abstract

Introduction. Operation of sea transport vessels is inextricably linked with the emission of harmful substances into the atmosphere, which are formed in the diesel engine cylinder during fuel combustion. One of the most dangerous of them is nitrogen oxides, the emission of which is regulated by MARPOL requirements. The most effective purification of exhaust gases from nitrogen oxides is provided by catalytic reduction systems. At the same time, due to the use of urea as a reagent in these systems, carbon dioxide emissions increase. This, due to the increase in the greenhouse effect, contributes to global warming. The purpose of the study is to determine the optimal operating modes of the ship’s catalytic reduction system for marine diesel engines. The optimal ones are understood to be those that ensure a minimal increase in carbon dioxide emissions while maintaining a high level of reduction in nitrogen oxide emissions. Results. The studies were carried out on a Gas Carrier class vessel with a displacement of 127,645 tons with two main engines 5X72DF Hyundai-WinGD and three auxiliary engines 6H35DF Hyundai-HiMSEN, the exhaust gases of which were subjected to catalytic reduction. Optimal modes have been experimentally established, in which the relative increase in carbon dioxide emissions does not exceed 2.3% for both types of diesel engines. Nitrogen oxide emissions for 5X72DF Hyundai-WinGD diesel engines do not exceed 3.3 g/(kW · h) and do not exceed 2.4 g/(kW · h) for 6H35DF Hyundai-HiMSEN diesel engines, which meets the requirements of Annex VI of MARPOL. The relative reduction in nitrogen oxide emissions in these modes is 66.7–83.4% for the 5X72DF Hyundai-WinGD diesel engine and 60.8–78.3% for the 6H35DF Hyundai-HiMSEN diesel engine. Conclusions. Catalytic reduction systems for marine diesel engines are characterized by the presence of optimal operating modes. It is in these modes that the minimum increase in carbon dioxide emissions is ensured while maintaining a high level of reduction in nitrogen oxide emissions. The coincidence of the values obtained for the low-speed diesel engine 5X72DF Hyundai-WinGD and the medium-speed diesel engine 6H35DF Hyundai- HiMSEN indicates the correctness of the research and the possibility of implementing their results on all types of diesel engines and catalytic reduction systems.