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The implementation of national four emission is an irreversible trend. Due to China's national conditions, oil products and other factors, the fourth upgrading country adopts SCR route, and the most important thing of SCR route is the use of vehicle urea. Xiaobian collects some information about vehicle urea and shares it with you. It mainly includes the basic knowledge, price, use cost, index, filling and other aspects of vehicle urea.
● basic knowledge of vehicle urea
Vehicle urea solution is a colorless, transparent and clear liquid with a concentration of 31.8% - 33.2%, which is used to reduce nitrogen oxides. The currently used vehicle urea solution is generally composed of 32.5% high-purity urea and 67.5% deionized water. Vehicle urea solution was first used in Europe, known as AdBlue, in North America as def (diesel exhaust fluid), and in China as vehicle urea solution or "vehicle denitration agent".
The shelf life of vehicle urea changes with temperature
车用尿素的储存 | |
储存温度（℃） | 安全存放时间（月） |
≤10 | 36 |
11-25 | 18 |
26-30 | 12 |
31-35 | 6 |
＞35 | 使用前检测 |
Vehicle urea must be stored between - 5 ° C and 25 ° C. Moreover, the shelf life is also different with different storage temperatures. When the temperature exceeds 35 ℃, vehicle urea must be tested before use.
The role of vehicle urea in reducing NOx emissions
China's route to upgrade country 4 is SCR route, that is, the use of selective catalytic reduction technology. The operation process is as shown in the figure. Roughly, the tail gas enters the exhaust pipe after coming out of the turbine. The exhaust pipe is equipped with a urea metering and injection device to inject urea aqueous solution. The urea solution and nitrogen oxides in the tail gas undergo redox reaction in the SCR reaction tank to generate nitrogen and water for discharge.
Nitrogen oxides in automobile exhaust are not only one of the causes of acid rain, but also have direct harm to human body. The function of urea solution is to chemically react with nitrogen and oxygen compounds in automobile exhaust to generate non-toxic nitrogen and water, so as to reduce the emission of toxic gases in automobile exhaust and reduce pollution.
There are two forms of urea tank layout
You may have seen it at the auto show or online. Compared with the third car, the fourth car has a small liquid storage tank, which is the urea tank. As shown in the figure above, domestic urea tanks are basically placed independently on the side of the frame.
The arrangement of urea tanks abroad can be divided into independent type and integrated type. Independent is similar to that in China. The above figure shows the integrated layout of foreign urea tanks. The urea tank and oil tank are side by side. From the outside, it seems to be placed in the oil tank. This layout may be for overall beauty and space saving.
There are many common brands and manufacturers
The technical threshold of vehicle urea solution is low, and many domestic manufacturers have production capacity. Under the influence of the Fourth National Congress, many enterprises are also making plans one after another to take a share in the automotive urea market. At present, there are several large companies, Yara, kelansu, Meifeng chemical and obilan.
● vehicle urea index and price
It is said that the national fourth car is more expensive than the national third car. How much is it? At the same time, how much will the use cost be increased by using vehicle urea? Let's make a rough estimate.
The cost of car purchase increases, and it is estimated that the heavy truck will cost 20000-30000 yuan
It is not clear how much the price of the fourth car is higher than that of the third car. Xiaobian consulted several dealers from different manufacturers. According to them, according to the manufacturer's information, the national four heavy truck is 40000-50000 more expensive than the national three heavy truck, and the light truck is about 20000. According to one of the dealers, this price is only the guidance price given by the manufacturer in the early stage. Finally, when it is listed in large quantities, the price will certainly decline. It is expected that heavy trucks are about 20000-30000 expensive and light trucks are about 10000 expensive.
We can also estimate that due to the small changes in other aspects of vehicles using SCR technology route, the increased cost is mainly a set of SCR post-treatment system. Here we can calculate the price of SCR system.
The whole SCR system includes urea aqueous solution storage tank, conveying device, metering device, injection device, catalyst, temperature and exhaust sensor, etc. It is divided into imported, joint venture and domestic products. Imports mainly include Bosch, Cummins, Daimler purem, Iveco, Renault, etc; The joint venture is mainly Shanghai Huake; Domestic products include Wuxi Weifu Lida, etc.
At present, the price of the whole set of imported SCR system is 30000-40000 / set, of which the price of metering pump is about 10000 and the price of exhaust processor is about 20000-30000. The price of domestic weifulida products is 10000-15000 / set.
Combined with the dealer's statement and the price of SCR system, the final increase in vehicle purchase cost may be as disclosed by a dealer. Heavy trucks are expected to cost 20000-30000 and light trucks about 10000.
The use cost of vehicle urea is about 16.2 yuan per hundred kilometers
Another increased cost comes from vehicle urea itself. To calculate the use cost of vehicle urea, we first look at the use volume and price.
The consumption of vehicle urea solution is 3% - 5% of diesel, that is, 3-5l vehicle urea solution is required for 100L diesel. For the price of vehicle urea, we learned from the imported manufacturers that the price of 10L is 850 yuan, that is, 8.5 yuan / L.
In our simple calculation, the consumption of urea solution is 5% of diesel oil, and the price is 8.5 yuan / L. So the consumption of 100L diesel requires 8.5x5 = 42.5 yuan of urea solution. Assuming that the fuel consumption of 55T standard semi-trailer is 38L, it will cost about 16.2 yuan to buy vehicle urea for driving 100km. If a heavy vehicle travels 100000 kilometers a year, it will cost about 16200 yuan to buy vehicle urea solution, which is still a large expense. Since the consumption is the highest value and the price will gradually decrease with the increase of urea consumption, it will be lower than this value in actual use.
The use of national four vehicles has increased a lot of costs, especially the use cost of urea in the later stage. Since urea is so expensive, can ordinary urea be used to replace vehicle urea? What is the difference between vehicle urea and ordinary urea?
No, the requirements for general vehicle urea are more stringent.
车用尿素和工业尿素成分比较 | ||
项目 | 车用尿素国标规定 | 国内工业用优等品尿素 |
碱度/% | ≤0.2 | ≤0.01 |
缩二脲/% | ≤0.3 | ≤0.5 |
不溶物/（mg/kg） | ≤20 | ≤500 |
铁/（mg/kg） | ≤0.5 | ≤5 |
硫化物 | 0 | ≤5 |
氯化物 | 0 | 无要求 |
The above is a comparison made by the small series with reference to the indicators of vehicle urea and industrial urea. Almost all composition indexes of industrial urea are higher than those of vehicle urea - especially biuret and insoluble matter; In addition, vehicle urea is not allowed to contain sulfide and chloride, while industrial urea is relatively loose. Therefore, ordinary urea can not be used to replace vehicle urea.
The national standard came late, and China learned from foreign countries
The standards at home and abroad are basically the same
Foreign standards were formulated relatively early, while in China, only two local governments in Beijing and Shenzhen formulated relevant standards in the early stage, and China's national standard for vehicle urea was just implemented on July 1, 2013. There is little difference between domestic standards and foreign standards.
1. Domestic standards
The earliest domestic standard for vehicle urea was DB11 / 552-2008 standard formulated by Beijing in 2008. In 2010, Shenzhen formulated the special zone technical specification for vehicle urea solution (aus32). The national standard of vehicle urea solution in China is the nitrogen oxide reducing agent for diesel engine - urea aqueous solution (aus32) just implemented on July 1, 2013.
2. Foreign standards
Foreign standards include ISO 22241-1 formulated by the international organization for Standardization in 2006, German standard DIN 70070 and Japanese Standard JIS K 2247-1.
Impurities and metal ions affect the catalytic reduction efficiency
Alkalinity, impurities and metal ions in urea all affect the quality of urea, thus affecting the catalytic reduction efficiency and even blocking the nozzle. Xiaobian found some information for your reference.
1. The alkalinity of vehicle urea shall not be greater than 0.2%
Alkalinity is related to the purity of urea. Too high alkalinity indicates that part of urea is impure or has been decomposed.
2. Impurity
Impurities such as biuret, aldehydes and insoluble substances may lead to blockage of urea infusion pipe and nozzle of SCR system. The phosphate in urea will poison and disable the catalyst of SCR system.
3. Metal ions
The metal ions contained in urea are not only impurities, but also toxic to the catalyst of SCR system and affect the conversion efficiency of transcatalytic reduction.
The crystallization point of 32.5% vehicle urea was the lowest
Relationship between urea solution and crystallization point
The concentration of urea directly affects the reduction rate of nitrogen oxides and the crystallization point of urea solution. Too high or too low concentration can not improve the conversion efficiency of nitrogen oxides, but will cause the residual ammonia to form secondary pollution.
At present, most countries using SCR system tend to use 32.5% urea solution, and because the crystallization point of urea solution with this concentration is the lowest, it will crystallize when it is lower than - 11 ℃.
Some manufacturers have added heating devices in urea tanks
This leads to another concern. Automotive urea is easy to crystallize in winter. From the products displayed at the previous auto show, some manufacturers add a heating device in the urea tank, which solves the problem that urea is easy to crystallize.
Appendix:
Quality index of industrial and agricultural urea
● vehicle urea filling and use
Where to buy car urea and how to fill it. At present, there is little use of vehicle urea in China. Let's take a look at the filling methods in Europe.
Europe developed earlier and combined the three filling methods
1. Main filling methods of urea pump station
Almost all gas stations in Europe can fill urea. The filling machine is installed in the gas station. This fixed filling method is the most important urea filling method in Europe, which is very convenient.
2. Selection of large fleet of self built supply station
In Europe, large fleets will also build their own urea supply stations as needed, which can save the filling station, which is not only convenient, but also reduce the cost.
3. Bulk carrying emergency plan
Common small package urea solution
In addition, for emergency, many drivers will carry small packages of urea solution with the vehicle to prevent the normal driving from being affected by the use of urea. This small package solution is generally divided into 5L, 10L, 20L and other specifications.
In 2007, the European urea filling network was already very intensive
Europe has implemented Euro 4 emission standard since 2005, and they also use SCR route and need to add urea. It is said that in the early stage, the layout development of their vehicle urea was also very slow. By 2007, the layout of European urea sales network was very dense. At present, the injection mode of urea in Europe is mainly urea pump station.
China is at the initial stage, and the layout of urea filling points is not perfect
Due to the small demand for urea in China, the sales network of urea is not very sound. At present, only Beijing, Shanghai and other places where the fourth national plan was implemented in the early stage have the layout of filling stations, and mainly urban bus filling. For the truck driving route, there is no layout of urea filling points on expressways and service stations.
What if the car runs out of urea? Can the car run? As China is now in its infancy, let's take a look at some situations abroad.
Europe and America: limit the number of engine starts
There is a urea quantity indication on the truck instrument panel
European and American countries implemented this earlier. Their usual practice is to set a warning value for the amount of urea in advance. When the urea solution is lower than the warning value, the system will set the number of engine restarts until urea is added; In addition, the vehicle can be limited to start when refueling. When urea is lower than the warning value, the vehicle will not start after refueling.
Their vehicles realize this function because they are equipped with automatic vehicle diagnosis system (OBD). OBD is the abbreviation of on board diagnostics in English and translated into "on board automatic diagnosis system" in Chinese. One of its functions is to detect the engine exhaust emission. When the exhaust exceeds the standard, it will give an alarm and transmit the information to the ECU of the engine. The ECU limits the start of the engine through the preset program.
Hong Kong has now implemented Euro 5 emission standards, which is similar to that in Europe and the United States. The forum also has some discussions on this topic. The following reply is more interesting: "the European four trucks in Hongkong can not be flameout without urea. A stalled engine can not start, and it needs to be dragged back to the service station to decode. They call the European four car" diabetes "car, to fight insulin.
Extension: too few urea filling points
At present, there is almost no filling point layout in China, and there are few trucks in the fourth country. In the early implementation of the fourth country, the buses were mainly filled with urea through self built urea supply stations. It is said that through unconventional means, the on-board diagnostic system can not detect the exhaust emission, so that the vehicle can run normally without adding urea.
The implementation of the national four emission standards is an effective measure to reduce emissions, reduce pollution and protect the environment. In China, if we want to restore vehicle exhaust through SCR system, on the one hand, we need to improve the oil quality, on the other hand, we need to improve the urea sales network, and at the same time, we also need the majority of drivers to improve their consciousness.
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