基于CFD和RSM的船舶SCR脱硝装置结构优化

Structure optimization of vessel SCR based on CFD and RSM

以某船舶选择性催化还原(SCR)系统为研究对象,将计算流体力学(CFD)与响应面法(RSM)相结合,获得了催化剂尺寸、混合室位置等结构参数对于流场、脱硝效率和氨逃逸率的影响规律.在此基础上以CFD数据为样本拟合响应函数,并通过求解响应函数极值的方法实现了SCR装置结构的小型化.数值模拟结果表明,混合室的设置提高了尿素与尾气混合均匀性.同时,随着SCR反应器尺寸缩小,脱硝效率和氨逃逸量分别下降和增加.通过RSM优化后的SCR反应器可缩小15.9%~45.2%,混合室的最佳位置为SCR前1.70~2.39 m处,优化后系统脱硝效率超过90%,氨逃逸量小于5×10^-6 .

It is crucial to optimize the vessel selective catalytic reduction(SCR) structure to meet compact ship space. In the current study, a marine SCR system was studied based on computational fluid dynamics (CFD) and response surface method (RSM). The effects of the catalyst size and the distance between mixing chamber and nozzle on de-NOx efficiency, and the ammonia slip was studied in detail. CFD data were used as samples for the response function fitting, and the structure of SCR was miniaturized by determining the extreme value of the response function. Simulation results indicate that the mixing chamber can enhance the mixture of urea and exhaust gas. The denitrification efficiency and the ammonia slip increase and decrease with the decrease of SCR catalyst size. The size of the catalyst after RSM optimization can be reduced by 15.9% to 45.2%, the most suitable mixing chamber position is 1.70 to 2.39 m from the nozzle. Under this circumstance, the de-NOx efficiency is over 90%, and the ammonia slip mass is less than 5×10^-6 .