| The independent research and development of marine exhaust gas aftertreatment device is extremely urgent,along with the implementation deadline of strict emission standards of IMO,European Union,China,the United States and other international organizations approaching.Although there are a number of technologies for reducing sulfur oxide emissions on vessels,the exhaust gas desulfurization technology is mainly the wet washing desulfurization technology which is currently suitable to vessels and shows good economical performance.Compared with the other wet desulfurization technologies,the exhaust gas washing desulfurization technique has been selected as the research object based on sodium alkaline method in this thesis.And the engineering prototype is designed to the MAN 6S35MC marine diesel engine by using natrium-alkali method.Then the thesis provides the economical analysis of EGC system in the application of ship.In the thesis,the following research works have been carried out:(1)The model that NaOH solution absorbs SO2 was established.The absorption rate equations for SO2 in water and NaOH solution were derived respectively on account of the mass transfer rate equation of gas and liquid phases and the chemical reaction equation.The measures of improving SO2 absorption rate were also proposed.(2)The scrubbing solution,types of scrubber and packing in the test were selected for the objective diesel engine according to the desulfurization requirements and ships characteristics.And the specific size of the scrubber and attached parts were devised in the light of operating condition on test.(3)The real machine test of scrubber was conducted according to equal gas flow principle using 5S50ME two-stroke marine diesel engine.The scrubbing effect of SO2,NOx and CO2 was studied on all the operating loads.The key factors that affects desulfurization efficiency and operation cost were studied based on the experiment,and the effects of scrubbing system on engine back pressure and fuel economy performance were also studied in all loads.The experiment and study indicated that:?The desulfurization efficiencies were high above 99%.? However,no CO2 was absorbed by scrubbing liquid.The value of SO2(ppm)/CO2(%)(v/v)was 1.29 at the most,and far below IMO limit value of 4.3.?little of NOx was removed by the desulfurization system in waste gas.?The nitrate content of treated waste water was 0.4 mg/L and absolutely conformed to IMO emissions guidelines about water discharge standards.?The pH value was the key factor affecting the desulfurization efficiency?When system running,the pH value of scrubbing liquid should be maintained in a reasonable range.?At 100%load,the maximum differential pressure was 350 Pa.So that the system running resistance was small and there was little influence on diesel engine back pressure.?There was little effect on diesel engine fuel consumption rate from exhaust gas cleaning system and the maximum fuel consumption increased was 0.78 g/kWh.(4)Finally,the thesis provides the economical analysis of EGC system in the application of ship.According to the specific sailing time and mode,contrastive analysising the running costs of EGC ssrubber and using alternative fuel,it is concluded that installing scrubber has significant cost advantage.The research results obtained from this thesis could provide the reference for the design,research and application of two-stroke marine diesel engine scrubbing desulfurization system. |
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