Optimization Design And Policy Simulation Of Marine Diesel Engine Post-processing System

China is currently experiencing severe regional air pollution.In order to reduce the impact of ship emissions on regional and global air pollution,this paper proposes a new type of marine diesel engine exhaust aftertreatment technology.The optimization device improves the traditional denitration technology route based on SCR?Selective Catalytic Reduction?,strengthens the purification efficiency of NO_x?Nitrogen Oxide?and PM?Particulate Matter?,and reduces the cost of abatement.There are many factors affecting the NO_x conversion efficiency in the diesel engine SCR aftertreatment system,such as catalyst performance,urea injection amount,and type of urea injection pump.In this study,Through the engine bench test,the diesel engine exhaust aftertreatment system optimization device was applied to the Weichai WD615 engine to verify the actual performance of the optimized device.First,we use a self-developed catalytic oxidation particle bed device.The device has a simple structure and fundamentally solves the problem of clogging of the selective catalytic reduction method and the instability of the amount of gaseous ammonia produced.Secondly,this paper also studies the influence of the increase of urea injection volume on the NO_x conversion efficiency and the secondary pollution of NH₃ under different engine speed and torque,and analyzes the different urea injection quantity to the NO_x conversion efficiency.influences.It is found that the larger the amount of injection in the urea injection system,the better.The excessive amount will affect the NO_x conversion efficiency.The urea injection amount is too large,and the excess urea does not participate in the chemical reaction of reducing NO_x,which does not achieve the best treatment effect.It causes ammonia to escape and forms secondary pollution discharge.In practical applications,the optimal injection ratio should be selected according to various factors to achieve the best efficiency.The matched diesel urea SCR aftertreatment system can further reduce the emission concentration and reduce pollution.Thirdly,through comparison experiments with traditional aftertreatment systems,the post-processing optimization device proposed in this study can significantly reduce the concentration of PM and NO_x in diesel exhaust emissions,which are far lower than the current domestic and international emission standards,particulate matter.The measured value is between 13-24.5%of the standard limit,and the average measured value is only 19.4%of the standard limit.In terms of NO_x treatment,the measured value is between 1.25 and 2.88%of the standard limit,and the average measured value is only 1.9%of the standard limit.The dust and NO_x content after purification has been far below the standard value required for the Stage III?Phase 3A?and Beijing DB11/185-2003 emission limits?Phase??.In addtion,compared with the existing diesel exhaust gas purification device,the investment cost of the purification device and the maintenance cost are relatively reduced.The annual operation cost of the pollution control device can be greatly saved,which contributes to the sustainable development of the ship operation industry.