Domestic urea is mainly from industrial urea purification, the main principle is:
1)at a temperature of 70-75 ℃, urea in aqueous solution occurs hydrolysis.
2) When the temperature is below 30 ℃, the urea is re-crystallized from the aqueous solution.
3) Each hydrolysis crystallization once, its purity will be greatly improved, the general use of industrial first-class urea hydrolysis crystallization once, can reach the standard requirements for automotive urea, the output ratio of 1.5:1. Automotive urea must use the electronic industry first-class ultrapure water. Because the SCR catalyst carrier is prone to metal ion poisoning resulting in the loss of catalytic effect, the automotive urea solution must use the electronic industry first class ultrapure water (resistivity ≥18mω?cm). The AdBlue will start to freeze under the -11℃, and the actual use will be fully frozen at 20 ℃.
At present, the technology is to prevent the solution solidification by adding modifier to reduce the solidification point of solution and adding heating device. Automotive Urea Solution (AdBlue) is a solution formulated with high-purity urea and pure water without any other additives, the urea content of the solution is 32.5% (mass fraction). Most of the domestic and foreign heavy duty diesel engine manufacturers adopt SCR (selective catalytic reduction) technology to meet the requirements of Euro IV and Euro Ⅴ motor vehicle emission standards.
A vehicle that chooses SCR technology must add a urea solution as a catalytic reducing agent to enable the vehicle to discharge its standards. Diesel engine exhaust treatment fluid (commonly known as: Automotive urea, car urea, automotive environmental urea), in China and Europe called AdBlue, in the Americas called Def, in Brazil called Arla32.adblue is composed of 32.5% high-purity urea and 67.5% of deionized water composed of high-purity transparent liquid, there is a faint smell of ammonia. If spilled, the water evaporates and forms a crystallization. AdBlue for cars, trucks, buses and heavy-duty off-road diesel vehicles equipped with SCR (automotive selective catalytic reduction tail gas treatment) systems are consumables that must be used in SCR technology, together with SCR catalysts to convert harmful nitrogen oxides emitted by diesel engines into harmless water vapor and nitrogen. The main components of the SCR system include catalysts, AdBlue injection devices, adblue containers and AdBlue dosage controllers. Almost all of Europe, the United States and Asia, including China's heavy vehicle manufacturers also equipped with selective catalytic reduction systems and with adblue working fluid to achieve new NOx emission standards (such as Euro IV, Euro V) AdBlue and SCR technology together to optimize engine performance and fuel consumption, Reduce diesel consumption by up to 6%, significantly reducing costs. The average consumption of AdBlue is 5% of the general diesel consumption, which consumes 1.5 litres per 100 kilometres for highway driving. The AdBlue only allows the combination of engines used to configure an SCR system, as it is neither a fuel nor a fuel additive. AdBlue complies with the standards in the iso22241,din70070 and CEFIC regulations to ensure effective operation of the SCR system.
AdBlue is not hazardous to the environment and is classified as the lowest risk transportable liquid. Suitable for diesel engines in accordance with the country's four emission standards of automobiles, trucks, buses, buses.