| Selective catalytic reduction (SCR) is thought as the most effective NOx control technology of diesel engine by far. It uses NH3to get rid of NOx. At this stage,32.5%urea solution is used as a reductant to release NH3. Marine diesel engines urea selective catalytic reduction (Urea-SCR) system device is very large and reaction is very complex, which bring a huge problem to the design work. In this paper, take Man B&W6S50MC-C Marine diesel engine Urea-SCR system as the research object, set up a corresponding model to simulate Urea-SCR system physical and chemical process and design the relevant parameters. The main contents of this paper are as follows.(1)1Simulate catalytic reaction by use of single-channel model and obtain the relationship of the catalytic efficiency between reaction temperature, NH3/NOx and residence time. Optimize the reaction conditions by analyzing the influence of different conditions on the catalytic de-NOx efficiency, let SCR unit work at the optimal conditions and provide a reference to convertor structure design.(2) Design catalytic convertor for Man B&W6S50MC-C marine diesel engine Urea-SCR system by using single-channel model and three-dimensional model simulation approach.(3) Use the discrete phase model in FLUENT to simulate the process of urea injection of Urea-SCR system, compare NH3evenness index of different nozzle layout program to get the a most suitable one of Man B&W6S50MC-C marine diesel engine. |
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