A few days ago, the Ministry of Environmental Protection stipulated that starting July 1, 2013, all heavy-duty vehicle compression ignition engines produced, imported, sold, and registered should be mainly referred to as diesel engines and must comply with the “National IV” emissions issued in 2005. Standard requirements.

In large cities, due to heavy-duty diesel trucks being banned from entering the center of the city during the day, people's concern about their pollution is not high. However, according to the "2012 Annual Report on Motor Vehicle Pollution Prevention and Control" issued by the Ministry of Environmental Protection at the end of last year, the number of diesel vehicles that accounted for 17.4% of the total number of motor vehicles was 3.887 million tons of nitrogen oxides and 5.9 million particles (PM). Tons, their emissions accounted for 67.4% and 99% of the total vehicle emissions. According to the China Environmental Quality Bulletin, the total amount of nitrogen oxides emitted in 2011 was 24.04 million tons, that is to say, only one nitrogen oxide, diesel vehicles accounted for about 16%.

Hu Jingnan, an associate researcher at the Chinese Academy of Environmental Sciences who has long been engaged in the study of motor vehicle pollution control, believes that due to the lack of relevant research data, the annual report did not fully incorporate particulate emissions from gasoline vehicles. Therefore, the proportion of diesel vehicle emissions has been enlarged. Even so, it is an indisputable fact that the proportion of nitrogen oxide emissions from diesel vehicles exceeds 60% and particulate emissions approach 90%.

Nitrogen oxide itself is toxic, and it is also one of the main sources of acid rain, and the nitrogen oxides emitted by automobiles can easily become precursors of PM2.5 and ozone. After a complex chemical change, the harm to human body is very great.

According to the National IV standard, the emission of nitrogen oxides will be reduced from 5.0 g/kWh at the national level to 3.5 g/kWh. The particulate emission limit will be reduced from 0.10 g/kWh to 0.02 g/kWh, which is also known as nitrogen oxides. With 30% emission reduction and 80% reduction of particulate matter, the environmental benefits are very obvious. Hu Jingnan said that if this is the case, if the new national standard can be fully implemented, only the nitrogen oxide reduction will reach about 180,000 tons/year.

In the eyes of scientific researchers, the implementation of the National IV standard is a milestone in the prevention and control of diesel vehicle pollution, not only because of the drastic reduction in pollutant emissions, but also in the leap of pollution control technology. “From State II to State III, it is from mechanical control to electronic control. From State III to State IV, we must not only have an electronic control system, but also a post-processing technology system.” Hu Jingnan introduced this post-processing system, usually Known as SCR technology, which is currently the most selective catalytic reduction technology for power plant denitrification, its application has made a qualitative leap in diesel engine emission reduction. At the same time, after the emission standards were upgraded to National IV, heavy-duty diesel vehicles could reduce fuel consumption by about 5%, and the power increase was about 10%.

Although the fourth national standard for heavy-duty diesel vehicles was implemented on July 1, the National IV standard has only been implemented in half. Due to the lack of fuel that matches the emission standards, the implementation time of the National IV emission standard for light-duty diesel vehicles has been delayed again. In the face of serious concerns about the quality of the atmospheric environment today, how to better promote the emission standards of diesel vehicles continue to advance, absolutely not slack.

Recalling the upgrading process of diesel vehicle emission standards, Hu Jingnan was very impressed. The Fourth National Standard was introduced in 2005, leaving time for the planned implementation in 2010. However, when it comes to the 2010 implementation deadline, not only can the fuel quality of vehicles be kept below the standard, but also the level of technical reserves of domestic diesel engine manufacturers is not enough. To implement the national standard, the cost of each vehicle must increase by 40,000 to 50,000 yuan. This is obviously Both manufacturers and consumers find it difficult to accept. However, due to the pressure brought about by the implementation period of the standard, at the same time, the manufacturers saw the fuel-efficient benefits of technological upgrading, the technological transformation was speeded up, and the production capacity of related equipment quickly matured. By 2012, to achieve the National 4 standard, the cost increase for each car will be reduced to around 10,000 yuan.

However, when technology and markets are ready, the standard has been postponed twice. In the final analysis, the quality of oil products has been tampered with. Since the light-duty diesel vehicle's post-processing device is sensitive to the sulfur content of the oil, the 350-ppm three-phase diesel fuel currently available on the market cannot meet its needs.

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