Experimental Research On Marine Diesel Engine NO_x Emission Control Based On Electrolysis Principle

With the rapid development of the shipping industry, the number of ships has increased year by year. As consequences, the pollution on atmosphere by ships becomes more and more serious, which has been caused much more concern worldwide. International maritime organization (IMO) issued MARPOL convention annex VI aims to reduce the air pollution caused by ships. IMO Tier III, a more stringent standard for NOx emission control will be enforced into accomplice from 1 Jan,2016. For implementation of the convention, national country is positively researching cheap and efficient ship exhaust emission reduction technology. The topic proposed "combination of acidic water oxidation and alkaline water absorption" to reduce NOx emission from ship exhaust. This method combined with seawater washing can realize SOx and NOx emission control. It was no need to add other raw materials except seawater. Beside, washing product could be directly discharge into the sea. And alkaline generated by electrolytic cell could greatly reduce the seawater consumption.On the theoretical research, this thesis built experiment system and carry out electrolytic experiment and simulated ship exhaust NOx emission control experiment. In the electrolytic experiment, the acidic water pH, ORP value and oxidizing substances concentration changing with the electrolytic cell operation parameters were explored. The conclusion was obtained that there is a linear relationship between the electrolyte concentration/current density and oxidizing substances concentration of acidic water. The influence of electrolyte concentration and current density on current efficiency and electrolytic power consumption was analyzed. Obtained the following conclusion:with the increase of electrolyte concentration, the current efficiency gradually increased, the electrolytic power consumption gradually reduced; With the increase of current density, the electrolytic power consumption gradually increased, the current efficiency increases at first then decreases. At the current density for 800 A/m2, the current efficiency increased up to the maximum value.In the simulated ship exhaust NOx emission control experiment, the influences of acidic water pH value and oxidizing substances concentration on NO removal efficiency were analyzed. NO removal efficiency increases with the oxidizing substances concentration increasing and exist a turning point, When acid water oxidizing substances concentration reaching 700 mg/L, NO removal efficiency not increasing at all. Furthermore, NO removal efficiency gradually reduces with acidic water pH value increasing. Finally,5S35ME-B9 diesel engine was tested as an example to analyze the economy of marine diesel engine NOx emission control based on electrolysis principle.