大气污染治理详解.ppt

柴油车行驶工况与排放 1. CO总是很低, 约0.1% 2. 减速, 怠速时HC相对较高, 浓度约为400ppm 此时NOx较低, 约为30-70ppm 3. 加速, 定速时NOx高, 浓度约为: NOx: 800-2500ppm 此时HC: 90-200ppm 4. 加速时碳烟最高, 约为0.30g/m3 主要控制技术 前处理: 无铅汽油(0.013g/L), 低硫汽油和柴油(1200ppm--50ppm) 废气再循环(EGR): 20%循环, 降低NOx约60%, 但油耗增加3% 机内控制: 发动机设计 表面积/容积 越小越好; 电子控制技术; 多气门技术 机外控制技术: 热反应器, 催化反应器(氧化, 还原--三效) 改进点火系统 电控燃油 喷射系统 废气再循环(EGR) 三效催化净化技术(TWC) 同时净化3种污染物: CO, HC, NOx 只能在很窄的空燃比窗口工作: 闭环电控燃油喷射技术 三效催化净化技术(TWC) 主要使用贵金属+陶瓷载体, Pt, Rd, Pd 寿命要求80000-160000km, 防中毒很关键! * Air Pollution may be defined as any atmospheric condition in which substances are present at concentrations high enough above their normal ambient levels to produce a measurable effect on man, animals, vegetation, or materials. Air Pollution is the presence of undesirable materials in air, in quantities large enough to produce harmful effects. The undesirable materials may damage human health, vegetation, human property, or the global environment as well as create aesthetic insults in the form of brown or hazy air or unpleasant smells. * Pollutants released directly into the atmosphere in their unmodified forms and in sufficient quantities to pose a health risk * Secondary air pollutants are compounds that results from the interaction of various primary air pollutants. Photochemical smog is a mixture of pollutants resulting from the interaction of nitrogen oxides and hydrocarbons with ultraviolet light. The two most destructive components of photochemical smog are ozone(O3) and peroxyacetylnitrates(PAN，过氧乙酰硝酸酯) * Acid Deposition is the accumulation of potential acid-forming particles on a surface. Acids result from natural causes and from human activities. The acid-forming reactants are classified as wet or dry. * Molecules from natural sources, power plants, and internal combustion engines react to produce the chemicals that are the source of acid deposition * * * * * * * * * * *