Experimental Study On Treatment Of Marine Diesel Engine Exhaust Emissions By Ozonizer And SCR Reactor

Selective catalytic reduction（SCR）technology has become one of the most promising technologies for NOx emission control of marine diesel engines.But diesel engine has low efficiency of NOx conversion rate at low load.In order to improve NOx conversion rate of SCR reactor under low load of diesel engine,the feasibility of ozone synergistic SCR reactor is explored through experiments.The main research work of this article includes:（1）Based on the experimental platform of TBD234 V6 Marine engine,the establishment of the experimental platform for the ozone generator was carried out.According to the site layout of the test platform of the diesel engine,the specific injection position and injection mode of the ozone were designed,and the experimental design was carried out in combination with the experimental target.（2）Ozone was injected from the intake pipe of diesel engine,and its influence on combustion and emission performance of diesel engine was studied.It was known from the experimental results,from the aspect of combustion performance,fuel consumption rate has not been improved obviously,the effect of fuel saving is not obvious.But the detonation pressure has increased,and the maximum increase has reached 17.8%;From the aspect of emission performance,it has obvious utility in reducing smoke（K）,CO and HC emissions,and the maximum decrease is 29.7%,33.4%and 18.9%respectively.However,after injection of ozone,the concentration of NOx in the exhaust is greatly improved.Therefore,the improvement of the diesel engine’s economy by the injection of ozone is not obvious.Although it has the purification effect on most of the pollutants in the exhaust,but the production of the main harmful substance NOx is increased.（3）Low load under the 40%load rate of the diesel engine,Ozone was injected into the exhaust pipe of diesel engine,and partial NO was oxidized to NO₂ by ozone injection,this have increased the ratio of NO₂/NO.And achieved the purpose of reducing the K value and HC emissions of diesel engine.The emissions decreased by 51%and 19.1%compared with that before ozone injection.（4）According to the exhaust characteristics of diesel engine,according to the ammonia nitrogen ratio of 1:1,the theoretical urea injection amount corresponding to each experimental operating point of diesel engine was calculated.At the low load condition of the diesel engine under the 30%load rate,when ozone is coordinated with the SCR reactor,the conversion rate of NOx is increased compared with that before ozone,and the maximum increase is 32.1%.And after the ozone was injected,the amount of K was reduced,but a small amount of HC was added.Therefore,ozone cooperation with SCR reactor greatly improved the conversion efficiency of NOx.The experimental results show that the NOx operation of ozone generator combined with SCR reactor is feasible under the condition of low load of diesel engine.