Structural Dimensions Design And Performance Optimization Of MAN6S50MC-C Diesel Engine SCR Catalytic Reactor

With the rapid development of international trade, more and more serious environmental problems caused by the marine diesel engine emission, has caused widespread concern in the international community.In order to control the marine diesel engine NOx emissions effectively, some marine diesel engine companies,such as MAN,Wartsila,have already started to research the selective catalytic reduction (SCR) DeNOx systems for marine two-stroke diesel engine, but our research about this has just started, so to carry out related research of SCR system is significant.The catalytic converter is an important part of the SCR system.Its structures have significant impact on SCR performances. In this paper, the imminent implementation of the2016Tier3emission regulations as the background, using the widely recognized as the most efficient marine diesel engine NOx after-treatment technology-SCR method, by the computational fluid dynamics (CFD) software-FLUENT, taking the MAN6S50MC-C marine diesel engine as the research object, meeting the flow field, concentration field uniformity and low pressure drop requirements as the target, through installing the deflector equipment and optimizing the ammonia injection grid parameter, making the flow and concentration fields meet the uniformity requirement of the entrance of first catalyst layer, finally established the SCR reactor structure which meet the emission requirements. The main contents of this paper are as follows:(1)According to diesel fumes parameters at100%load and reactor denitrification capacity, ammonia slip rate and other requirements to design the catalyst structure size and then get the reactor structure size, completed the preliminary design the structure and size of the SCR catalytic reactor.(2)By the FLUENT software, building three-dimensional structure model of the SCR catalytic reactor to simulate the gas flow in the SCR reactor.According to the simulation results to analysis the characteristics of gas flow in the SCR catalytic reactor,to design the various parts of the deflector layer. Through installing deflector to improve the uniformity of flow distribution, designing the structure of the SCR reactor which meet the flow uniformity requirements.(3)On the basis of the primary optimized structure of the reactor, selecting the spray form of the ammonia injection grid, builing the simulation model of flue mixing effect of gas and reducing agent in the reactor, through analyzing and optimizing the structural parameters of the ammonia injection grid, designing ammonia injection grid structure and ammonia injection program which meet the concentration uniformity requirements, and then completing the structural design of the SCR reactor.