New Application of Seawater and Electrolyzed Seawater in Air Pollution Control of Marine Diesel Engine

It is the purpose of this paper to introduce the usage of seawater and its electrolysis for the exhaust emission control in marine diesel engines. First, with using only seawater that is naturally alkaline (pH typically around 8.1), the SO_2 and SO_3 are absorbed by relatively high solubility compared to other components of exhaust pollutants, and PMs (Particulate Matter) are removed through direct contact with the sprayed seawater droplets. Besides, the electrolyzed alkaline seawater by electrolysis, which contains mainly NaOH together with alkali metal ions (i.e. Na^+, Mg^<2+>, Ca^<2+>), is used as the absorption medium of NO_x and C0_2. Conditionally, before the NO_x absorption treatment with using the alkaline seawater, nitric oxide (NO) must be adequately oxidized to nitrogen dioxide (NO_2) by the acidic seawater in order to increase NO_x absorption rate into the alkaline seawater. Because NO_x absorption is the most suited to conditions when both volume fractions (NO : NO_2 ratio) are of equal portions. Finally, this research would also plan to treat the effluent by applying electro-dialysis and electro-flotation techniques in the future. The way to reduce emissions from the marine diesel engines is to make it attractive from an operating perspective, as well as an environmental perspective.