As a modern means of transportation, automobiles bring convenience to people's production and life, but their exhaust emissions cause serious pollution to the air environment. A city in China has made a preliminary investigation on the degree of motor vehicle exhaust pollution in the city: the city currently has 130 thousand motor vehicles and increases at an annual rate of 15%. The annual emission of carbon monoxide for motor vehicles is 44 thousand tons, which is equivalent to 46 times the carbon monoxide emission of industrial enterprises in this city. The carbon monoxide of the main traffic roads in the urban area is over 2 times above 65%, and at the peak of the traffic volume, the carbon monoxide concentration at some monitoring points is as high as 70mg per cubic meter, exceeding the standard 6 times. In the railway station with concentrated traffic flow, the mean value of the nitrogen and oxygen compounds is 0.059mg per cubic meter, and the super standard is 0.18 times. These data indicate that the city motor vehicle exhaust pollution has become the major air pollution, and smoke pollution and the past to change sulfur dioxide soot pollution mainly for carbon monoxide and nitrogen oxide of the vehicle exhaust pollution and sulfur dioxide pattern. To this end, some urban governments, in conjunction with the relevant departments, have formulated corresponding regulations. The Guangzhou municipal government promulgated the "notice on the use of leaded gasoline for the basic sale" and "Regulations for the prevention and control of motor vehicle exhaust pollution in Guangzhou". Beijing municipal government issued "on urgent measures to control air pollution in Beijing, the" notice "on the further implementation of air pollution control measures, to improve the quality of the environment and the organization" resolution ", the Municipal Environmental Protection Bureau of Beijing City, the implementation of light automobile emission standards". These local regulations mainly control the pollution of the motor vehicle exhaust to the atmosphere, and give the public a clean air living space.
1 harmful components and harm of automobile exhaust
The rest of the exhaust gas discharged from the car, except the nitrogen and oxygen in the air, the CO2 of the burning product and the steam as the harmless ingredients, are all harmful ingredients. A part of the toxic substance of exhaust gas emitted by an automobile engine is caused by incomplete combustion of fuel or low gas temperature. Especially in the sequence starting, the injector of the injector and the overload operation. Fuel can not burn well with oxidation, which must produce a large number of CO, HC and soot. Another toxic substance is nitrogen oxides NOx (NOx and NO and NO2), which are formed by high temperature and high pressure in the combustion chamber.
However, the above CO is a colorless, tasteless and poisonous gas, it is not easy to react with other substances, and become a relatively stable component of atmospheric components. It can stay for 2~3 years. When people inhaling too much CO, CO can bind to heme in the blood and prevent the blood from absorbing oxygen and transporting oxygen and poisoning death. The pollution caused by it is called the first exhaust pollution of automobile exhaust.
CH compounds, especially alkenes, react with nitric oxide to produce ozone, aldehydes and other smog like substances in the atmosphere under ultraviolet light. It stimulates people's mucous membranes such as larynx, eye and nose. It not only harms people and animals, but also destroys the ecological environment, and seriously affects the growth of crops. It makes the agriculture yield reduction and also has carcinogenic effect. It has become the second public hazard of automobile exhaust.
MOx is the general name of NO and NO2, in which the binding ability of NO to heme in the blood is stronger than that of CO. It is easy to cause people to be poisoned and die. NO2 is a poisonous Brown gas with a special smell of irritation and damage to the eyes and lungs. It is the main reason for producing acid rain and causing climate change and producing smoke. The emission of automobile exhaust is a public hazard.
The particulate matter of automobile exhaust is usually made up of porous carbon particles with a diameter of 0.1 to 40 m. It can adhere to SO2 and pyrene toxic substances, and has bad smell, which is extremely harmful to people's respiratory tract.
In addition, lead compounds, sulfur compounds and so on are harmful components.
To sum up, the pollutants discharged from automobile exhaust have brought serious pollution to the atmosphere environment that human depends on. In the densely populated areas such as the traffic trunk, the height of the exhaust is close to the body's respiratory zone, causing serious harm to the health of the human body. Therefore, it is necessary to take effective measures to reduce or eliminate the emission of automobile exhaust, which is an important subject that is studied and discussed in this paper.
2 purification treatment technology for automobile exhaust
Because of the serious dispersity and fluidity of the car, it also brings some restrictions to the purification treatment technology. In addition to the development of the internal purification technology, we must vigorously develop the technology of external purification. This paper from two aspects: one is the control technology, mainly to improve the combustion rate of the fuel oil to install anti pollution treatment equipment and take the development of the new engine; two is the administrative means, take the scrap update, the elimination of old vehicles, the development of new cars (non motor vehicle pollutant emission), from the control standard of fuel.
2.1 conversion of automobile fuel
The use of unleaded gasoline to replace leaded gasoline, can reduce emissions of gasoline emissions of toxic substances.
First of all, the use of automobile oil should be changed. With unleaded gasoline instead of tetraethyl lead gasoline. This is the methyl butyl ether gasoline with tree as infiltration mixture, it not only does not lead, and automobile exhaust emissions of carbon monoxide, nitrogen oxides, hydrocarbons will decrease. At present, in order to reduce vehicle emission and improve the atmospheric environment quality in China, the state stipulates that the lead-free gasoline is basically used nationwide in July 1, 1999. Since July 1, 2000, the market was basically sold with leaded gasoline. Because of lead in gasoline, it adds a ANTIKNOCKS -- tetraethyllead, it has high volatile, even at 0 degrees Celsius and began to evaporate, a volatile lead powder, with steam and smoke in the air start. But the level of lead pollution is closely related to the traffic density (the number of vehicles per hour) and the content of lead in the gasoline.
Although the traffic density of the cities in our country is lower than that of the developed countries, the pollution degree of lead caused by the burning of leaded gasoline can not be ignored. Lead is an accumulative poison that enters the body through human breathing, drinking water, food and other ways. The toxic effects on the human body are the erosion of the hematopoietic system, the nervous system and the sages. Toxic effects such as vascular system, reproductive system and cancer teratogenicity may also occur.
The incorporation of additives, changes in fuel composition.
Gasoline blending with less than 15% of methanol fuel or using 10% water water gasoline fuel can reduce or eliminate the pollution effect of CO, NOx, HC and lead dust to a certain extent.
If "methanol fuel" is used, the fuel made of methanol and other alcohols is mixed with gasoline. When the proportion of methanol is 30% to 40%, the pollutants discharged from automobile exhaust can be basically eliminated.
The selection of lubricant additives - mechanical friction improver right.
Add a certain amount in the oil (ratio of 3% - 5%) of graphite, MoS2, PTFE powder and other solid additives added to the oil tank engine, engine fuel savings of about 5%. In addition, the use of the above solid lubricants can greatly improve the sealing performance of the motor cylinder, increase the cylinder pressure and complete the combustion. In the exhaust emission, the content of CO and hydrocarbon will decrease, which can reduce the pollution to the atmosphere.
The use of green fuel can also reduce automobile exhaust emissions of toxic gases.
According to a Ohio Institute in the United States, soya bean oil is mixed with methanol and caustic soda, and then the glycerol is removed to get "some soy oil". "Soybean Diesel" is added to ordinary diesel in a proportion of 3 to 7, which can be used for diesel vehicles. It can greatly reduce the emission of sulfides, hydrocarbons, carbon monoxide and smoke in the operation of the engine. Therefore, it is known as the green fuel.
It uses a variety of fuel as automotive fuel sources. L-carnitine to fine line eye cream list of antioxidant skin care products
With the development of science and technology and the wide application of computers, we must ensure the implementation of environmental protection regulations and energy saving measures. New formula gasoline, electric power, compressed natural gas, solar energy and battery of ecological fuel can be widely used in automobiles. However, in this kind of car, the computer is installed on the computer to make the best performance of the car. A computer controlled ignition system is used to make quick response to different engine conditions, which can achieve the best fuel economy and engine power performance, and reduce the pollution of tail gas to the atmosphere.
It can save energy, favorable environment, vigorously promote the use of ethanol gasoline vehicle.
According to the experts pointed out that the development of ethanol instead of gasoline, which saves energy, but also harmful gas from digestion, to reduce automobile exhaust, is a new task to protect the environment and resources.
If the ratio of ethanol to gasoline is 1 to 9, 200 thousand tons of ethanol can be used to produce about 2 million tons of ethanol gasoline, and 2 million tons of ethanol will only consume 700 thousand tons of grain. Therefore, the development and development of special ethanol gasoline can solve the problem of grain storage transformation, and to a certain extent, instead of gasoline, to ease the tension of China's crude oil supply. And because alcohol is denatured fuel ethanol and gasoline for wheat, corn and other raw materials production mixed with a certain proportion of vehicle fuel, has been included in the "fifteen" development plan, compared with pure gasoline, carbon monoxide in the automobile exhaust can reduce the amount of 1 / 3, hydrocarbons decreased 13.4%. The promotion and use of the plan will play an important role in improving urban air pollution and ensuring the health of the people.
2.2 the internal test of automobile engine can reduce the emission of exhaust pollutants.
To reduce the fuel injection advance angle. Reducing the injection advance angle can reduce the maximum temperature (1500 degrees centigrade) of the engine, and reduce the production of NOx.
How to improve the quality of fuel injector, combustion control conditions (fuel ratio, combustion temperature, combustion time), can make the fuel burn completely, which can reduce the CO, HC and soot.
The amount of oil to adjust the fuel injection pump, can reduce the power of the engine, the fuel atomization has enough oxygen for complete combustion, which can also reduce the generation of CO, CH and soot.
2.3 engine external tail gas purification measures