As a high-frequency vocabulary after the implementation of the National IV, the urea solution for vehicles began to heat up at the beginning of the year. A lot of card friends have asked, can the car urea be replaced with agricultural urea, pure water? The answer is no substitute. Vehicle urea can only purchase urea solutions that meet the relevant standards in the market.
Urea for vehicles cannot be replaced by agricultural urea or pure water
● Agricultural urea can easily cause catalyst poisoning. Can not replace the vehicle urea solution is a stable urea solution (consisting of 32.5% high-purity urea and 67.5% of deionized water), used to reduce the nitrogen oxides in car exhaust after combustion.
Ordinary fertilizer urea contains biuret, mechanical impurities, formaldehyde, and metal ions, which can cause catalyst poisoning in the SCR exhaust gas after-treatment device and cause damage to components. Moreover, we searched through the Internet and found that the value of the urea pump is 10,000 yuan less. If damage cannot be recovered, it will be a significant loss to the user.
In addition, because the fertilizer urea is easily crystallized at a low temperature and the concentration of the urea solution cannot be guaranteed, the nitrogen oxide conversion rate is low. In addition, the loss of ammonia gas can damage the SCR system and make the vehicle unable to meet the emission standards.
● Adding water to replace urea will cause serious environmental pollution - a common practice in boycotting four countries is to bypass OBD monitoring and use water instead of urea solution to ensure the normal operation of the engine. Because the engine of the Fourth National SCR route burns sufficiently, the NOx emission is relatively high.
Urea that cannot be replaced by agricultural urea or pure water instead of adding urea should be negated and resisting the nitric acid produced by the combined conversion of NOx and air is a major cause of acid rain. At the same time, NOx will produce photochemical smog pollution with other pollutants under ultraviolet light. The harm to the atmosphere is very great, and it also has a great impact on human health. Therefore, the act of adding water to replace urea should be denied and boycotted.
● Vehicle urea selection Vehicle urea solution is also known as a lot of domestic urea solution, according to the European name for the "Adblue" solution, and in North America also known as DEF diesel emissions treatment fluid, the domestic also known as diesel engine nitrogen oxides reducing agent, Vehicle denitrification agent.
Most diesel car manufacturers tend to use a 32.5% concentration of urea aqueous solution (AUS32) as a reducing agent, and the concentration of urea directly affects the reduction rate of nitrogen oxides and the crystallization point of the urea solution. Too high or too low concentration will not only improve the conversion efficiency of nitrogen oxides, but will cause secondary pollution of the remaining ammonia. The 32.5% concentration was chosen because the car urea solution had the lowest crystallization point at this concentration (freezing point -11°C).
● Attention should be paid to the details. – Anti-impurity and anti-spill urea solution must be added during the filling process. During the filling process, impurities must be avoided in the solution and the urea tank. Normal urea solution has a special tube when filling, as long as open the urea tank, plug in the filling tube just fine. However, some people do not pay much attention at the same time to bring impurities into the tank and block the urea tank urea pump. In order to prevent impurities, pure water must be used when cleaning the SCR. Tap water is not available.
The act of adding water to replace urea should be negated and resisted. The correct use of carbamide for vehicle urea is alkaline, and the corrosion to copper, cast iron, solder, and cast aluminum is significant. Improper filling of urea can contaminate tanks and vehicles.
In addition, since urea itself does not pose a significant hazard to the eyes or skin, it can also cause slight irritation to the human body. If exposed to skin, flush exposed skin with plenty of soap or water. If you come into contact with your eyes, open the upper and lower eyelids and rinse with water.
At present, the four models of the country have used urea filters to filter out urea solution impurities and protect the SCR aftertreatment system.
● Storage should be protected from light and dust – use it as soon as possible after opening to avoid overheating and low urea. During transport, light and high temperatures are required. The optimum shipping and storage temperature should be between -5°C and 25°C. In addition, car urea will crystallize at a lower temperature, and the volumetric expansion will increase to 7%. If urea is too full, it will remain below 90% of the storage volume rate. High temperatures can lead to the decomposition of urea. Generally, the storage temperature of urea is related to the storage time of urea.
The use of urea for vehicle urea vehicles should be noted that we can use the table, you can see that due to temperature, most regions of the country store urea solution, shelf life in the six months and three years. For the usual six months the product performance is stable.
Avoid dust damage during transportation If the urea is stored in a dirty dusty place, the solution is contaminated with impurities. When driving, a few barrels of urea are often added to prevent the urea solution from running out of power. In the process of carrying the card, it is necessary for the urea packaging to carry out necessary anti-shock measures so as to avoid spillage of road bumps and corrosion of vehicles.
The storage of vehicle urea is very important. After the urea solution is opened, it is easily contaminated with impurities or algae after exposure. And urea itself decomposes to produce ammonia loss, which causes the solution to volatilize and cause urea to deteriorate. According to the domestic urea solution manufacturer's proposal, if you open the package, store it as required and use it within 30 days.
We can see that the concentration of urea solution for vehicles and the presence or absence of impurities are crucial for tail gas treatment. If water, agricultural urea, purchased non-compliance "shanzhai" urea solution are used, or qualified urea solution deteriorates during storage and filling. Not only does it affect the conversion efficiency of nitrogen oxides, but it also causes the loss of ammonia gas, and even directly destroys the SCR system, which affects the normal operation of the vehicle and cannot meet the emission standards.