采用低温等离子体同步净化柴油机PM和NO_x(一):物理仿真

为了实现对柴油机尾气中PM和NOx的同步去除,将静电旋风捕集技术与等离子体协同烃类选择性催化还原技术(Plasma/HC-SCR)相结合开发了一套柴油机后处理原理性试验装置。该装置集柴油机PM的静电捕集、PM的氧化燃烧、NOx的选择性催化还原于一体,对在富氧条件下利用烃类选择还原催化和静电旋风捕集同步去除柴油机PM和NOx进行了利用可控标准气体的模拟试验研究,得到了净化效率随相关参数之间的变化规律。在单纯的等离子体环境下,NO浓度降低,NO2浓度增加,但总的NOx基本保持不变;使用催化剂的同时辅助等离子体可以使NO的峰值转化率所对应的温度向低温区偏移50℃左右;催化剂、等离子体、还原HC对于降低炭烟的起燃温度都有影响,同时使用可以使炭烟的起燃温度最低降低到280℃。此装置实现了柴油机PM和NOx的同步去除。

Research on Removing PM and NOx Pollutants Simultaneously with Non-thermal Plasma: Physical Simulation

In order to remove the PM and NOx pollutants simultaneously,the principle experimental instrument of aftertreatment was developed by combining electrostatic centrifugal precipitating technology with non-thermal plasma cooperating with hydrocarbon selective catalytic reduction(Plasma/HC-SCR) technology,which had the function of PM electrostatic centrifugal precipitating,PM oxidation combustion and NOx selective catalytic reduction.The simulation experiments of removing the PM and NOx pollutants simultaneously with hydrocarbon selective catalytic reduction and electrostatic centrifugal precipitating technology were carried out with controllable standard gas instead of engine exhaust under the conditions of rich oxygen and the relation between the efficiency of reducing PM and NOx pollutants and the relative parameters was acquired.The non-thermal plasma made the decrease of NO concentration and the increase of NO2 concentration,which made the NOx concentration unchanged.With the catalyst assisted with non-thermal plasma,the corresponding temperature of maximum NO conversion rate decreased by about 50 ℃.The catalyst,non-thermal plasma and HC reduction affected the light-off temperature of soot and their simultaneous working would decrease the light-off temperature to 280 ℃.Accordingly,the PM and NOx pollutants could be removed simultaneously with the device.