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- 2017
Urea-SCR系统尿素结晶现象分析及解决方案
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Abstract:
摘要： 通过利用热重-红外联用(thermo-gravimeter-fourier transform infrared spectroscopy, TG-FTIR)技术检测尿素沉积物成分及利用计算流体动力学(computational fluid dynamics, CFD)技术模拟排气系统中气流运动,分析尿素选择性催化还原(urea selective catalytic reduction, urea-SCR)系统中的尿素结晶现象。针对尿素喷雾碰壁问题及雾化不良问题,根据CFD仿真结果提出一体式喷嘴座结构和集成式喷嘴座封装结构,然后利用柴油机台架试验优化尿素启喷温度和喷射速率。试验结果表明:当尿素启喷温度为272 ℃或喷射速率为5 g/min时,两种优化结构中均无尿素沉积物生成,解决尿素结晶结石问题,为柴油机SCR系统优化设计提供依据。
Abstract: Urea crystallization in the urea selective catalytic reduction(urea-SCR)system was analyzed by detecting the components of the deposits with thermo-gravimeter-fourier transform infrared spectroscopy(TG-FTIR)technology and simulating the air motion in the exhaust system with computational fluid dynamics(CFD)technology. To solve the problem of urea solution hitting the wall and poor atomization, the integral nozzle mountings structure and integrated nozzle seat package structure were put forward based on the CFD results, and the exhaust temperature when it started to spray and the injection rate of urea solution were optimized with engine bench tests. The results indicated that there were no urea deposits in the optimized structures when the exhaust temperature reached 272 ℃ or the injection rate of urea solution reached 5 g/min, thus solved the urea crystallization problem, which could provide effective methods for design and optimization of SCR systems for diesel engines
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