The inevitable trend of domestic diesel engine emission upgrade


Although the National III emission standards were implemented in Beijing soon, and the implementation of the National III emission standards nationwide will have to wait until next year, for the development teams of several major domestic diesel engine manufacturers, the State III is already over and they have begun to implement the EU. Preparations for IV and Euro V standards. And two years ago, we were still exploring whether the manufacturers were ready for the heavy-duty vehicle country II standard that was implemented at the end of 2004.

We have to admit that China is in a state of accelerated upgrading in terms of automobile emissions, and the gap with the international advanced level is getting smaller and smaller. However, as the gap between emission control technologies and foreign counterparts gradually narrows, some of the previously unobvious weaknesses have become more apparent. The average level of China’s economic development is still quite different from that of Europe. However, the rate of emission is much faster than that of economic development. The population density and environmental pressure are different in different regions of China, and the regional economy is unevenly developed. The key cities are large cities. With unbalanced development in vast rural areas, it is difficult to adopt the exact same policies across the country in terms of automobile emissions. Differentiating between different regions is a realistic choice for adapting to national conditions. It will also pose even greater challenges to the adaptability of engine manufacturers in technology. Therefore, in terms of vehicle emissions control, China should take a special road that meets the national conditions.

According to industry insiders, domestic diesel engine companies should come up with a unified plan for the technology upgrade route after the vehicle emissions have reached the national III standard. Emissions escalation was originally a matter for each engine factory, and it has nothing to do with others. However, in the technology development of Euro IV and even Euro V and Euro VI, there is a need for consensus among the companies.

For diesel engines, Euro IV is actually a turning point in technology. Previously, engine emissions could be reduced by internal cleaning technologies to meet relevant standards. From the beginning of Euro IV, the exhaust gas must reach the target through a post-processing device outside the engine. Which kind of technical route is chosen by the post-processing device is a practical issue for domestic engine manufacturers.

At present, two international technical routes are mainly used in diesel engines that can meet Euro IV standards internationally: EGR (exhaust gas recirculation plus post-treatment) or SCR (selective catalytic reduction).

Among them, SCR is the quickest way to realize Euro V, and it is also the necessary technical means to realize Euro VI. At the same time, engines with SCR technology can more effectively reduce the strong carcinogen nitric oxide in nitrogen oxides and have obvious energy-saving features. However, the use of SCR technology requires the construction of relevant infrastructure and the establishment of related urea solution supplement equipment at gas stations. Although SCR technology may not be used in Euro IV, it is difficult to evade the issue of SCR technology and related infrastructure construction in the future.

Lin Zhiqiang, a technical expert at Yuchai Technology Center, told the reporter: “Yuchai is not worried about this issue. The related infrastructure and the added urea solution can bring huge economic benefits and can fully drive the development of related industries. Certainly people will go. Doing this, and this matter itself is guiding the government, as long as all the diesel engine manufacturers agree that the late construction is better than early construction, the government will give corresponding support."

If you want to speed up on the road to emissions upgrades, avoid detours, or try to take shortcuts, then SCR is a short cut that we can choose.

Another important basic condition for the implementation of Euro IV or above emission standards is the corresponding low-sulphur diesel fuel, which is very different from the actual domestic situation. At present, domestic petrochemical companies have promised that the domestic fuel supply can meet the national II standard and the sulfur content is below 500ppm, while the Euro IV diesel fuel must have a sulfur content below 50ppm. This is a very big challenge for domestic oil refining companies. According to the petrochemical industry expert Wang Qiqing, the domestic petrochemical companies can meet the requirements for emission upgrades in the reserve of refining technology. However, if it is ensured that all standards are met throughout the country, then the cost of technological transformation will be excessive. A large part of this is due to the high sulfur content of oil in some parts of the country, while the imported oil is generally also not very good crude oil, and the sulphur content is also high, resulting in higher costs of producing low-sulfur fuel than in foreign countries. Many, but low-sulfur crude oil is occupied by old customers in Europe and the United States and other regions.

Therefore, after the implementation of Euro IV, only a few major cities such as Beijing and Shanghai can enjoy high-quality fuel. For a bus that travels only in the city, things are easier to handle; however, trucks and buses engaged in long-distance transportation must face compatibility issues with different oil products.

"High-sulfur fuels have little effect on the performance of the engine, and even have a certain degree of lubricating effect, but they have an impact on emissions, causing poisoning of some catalytic converters that use precious metals." Jilin University Automobile Institute is engaged in engine emissions Professor Liu Zhongchang of the study said.

In the face of national conditions, companies also hope to find solutions to the problem. Lin Zhiqiang told reporters: “When we selected the post-processing equipment, we asked foreign suppliers to request that their products be able to adapt to China's high-sulfur fuel oil.”

China's emissions standards have gone from scratch, from start to catch up, domestic engine companies have accumulated a considerable amount of experience and formed their own development system. Liu Zhongchang told the reporter: “Although the implementation of Euro IV standards, the control of emissions is very strict, but also affected by technical routes, fuel quality and other factors, but compared to the original implementation of the State I, State II standards in the absence of experience in the entire industry In fact, domestic engine companies have less difficulty in meeting the Euro IV standards."

Relevant experts believe that as long as China is gradually controlling automobile emissions, it will leave sufficient time for enterprises to prepare, and companies will come up with low-emission engines that suit their national conditions.



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