Research On Test Method Of SCR System For Large Diesel Engine

Diesel engine with high power,low fuel consumption,has been widely used in ships.With the increasing attention to the environmental protection,the pollution problem caused by the marine diesel engine is becoming more and more serious.IMO has become more and more strict to the standard of NOx emission from marine diesel engine.As one of the main measures to reduce NOx emissions,SCR technology has been applied to the field of marine diesel engine.How to test the effect of NOx emission reduction of SCR system has been tested to meet the requirements of Tier ?,which is the common concern of SCR manufacturers,classification societies and maritime bureau.According to the "Chinese Society published by selective catalytic reduction(SCR)system approval and inspection guide" and "the selective catalytic reduction(SCR)system default B test scheme of A test plan and guide" is put forward,and on this basis,put forward C new emission test scheme for geometric zoom test of diesel engine SCR reactor the.In order to verify the feasibility of the scheme of C,by using the commercial computational fluid dynamics software FLUENT reduction effect on internal selective SCR reactor for catalytic simulation,and based on the geometric dimensions of the reactor to obtain geometric zoom,zoom model and relation model,correction and related parameter deviation on zoom model.In the chemical reaction of SCR reactor in the simulation process,in order to simplify the reaction process,using only the standard reaction speed and flow field of the reactor,the concentration distribution of NOx,NOx and the state of emission reduction rate and the eddy current reaction rate and problem analysis.The establishment of the original model between the original model and the zoom model NOx conversion rate and the relationship between the geometric model of zoom conversion rate of NOx,??=?· k·???,k=k1,k2.The correction coefficient k1 and the correction coefficient of the parameter deviation caused by temperature,load and velocity are modified respectively k2.It is found that the scaling factor of the SCR reactor should be larger than the original size of the 1/10 in order to avoid the influence of scaling on the NOx reduction rate of the SCR reactor.There is a two order polynomial relationship between the uniformity index of reducing agent concentration and NOx emission reduction rate at the inlet section of SCR reactor.