DEF, short for Diesel Exhaust Fluid, is a chemical solution that is used to reduce the amount of harmful emissions produced by diesel engines. The production process of DEF involves several steps that are critical to ensuring the quality and purity of the final product .
Manufacturing steps :
1. Urea purification : Due to the high purity requirements of DEF, industrial urea (with a lower magazine content than agricultural urea) is generally used for purification. At 70-75 degrees Celsius, urea hydrolyzes in the aqueous solution, and below 30 degrees Celsius, urea is recrystallized from the aqueous solution. One step of hydrolysis crystallization can significantly improve the purity of urea. Generally, industrial grade 1 urea can meet the standard for automotive urea by one step of hydrolysis crystallization.
2. Water treatment : DEF has strict requirements for impurity control. During the production of ordinary tap water, due to disinfection and other reasons, it contains chloride, which is difficult to treat. Therefore, deep groundwater is generally used to remove calcium and magnesium ions and reduce the hardness of the water to obtain soft water for use in the preparation of DEF solutions.
3. Preparation of DEF : The urea content in the DEF solution is 31.8% - 33.2%. The final step in DEF production is to mix and dissolve the soft water and purified urea before filling.
4. Quality control : After the production of DEF, the final step is quality control. This involves testing the DEF to ensure that it meets the required purity and quality standards. The testing process involves several checks, including measuring the urea concentration, checking for any contaminants, and verifying the pH levels.
DEF reaction principle
Due to the fact that ammonia and NOx can only react under a catalyst, and the effectiveness of the catalyst is closely related to the metal content. If there are many metals and other impurities, the catalyst will be deactivated, leading to the failure of the entire unit. Therefore, the key to the production of DEF is mainly reflected in the purity of urea.
FAQ
What is DEF, and what is its purpose?
DEF, or Diesel Exhaust Fluid, is a non-toxic solution composed of purified water and automotive-grade urea (32.5%). It is used in diesel vehicles equipped with SCR systems to break down harmful nitrogen oxides (NOx) emissions into harmless nitrogen and water vapor, thus reducing air pollution.
How is DEF manufactured?
The DEF manufacturing process involves precise blending of high-purity urea and deionized water. The two components are mixed in specific ratios to ensure the DEF's quality and compliance with industry standards, such as ISO 22241.
What are the main ingredients in DEF?
DEF consists of two main ingredients: high-purity urea (32.5%) and deionized water (67.5%). Both components are critical to the effectiveness and quality of DEF.
What are the purity requirements for DEF?
DEF must meet strict purity requirements to maintain its effectiveness in reducing NOx emissions. The urea used in DEF manufacturing must be automotive-grade, with minimal impurities. Similarly, the deionized water must meet high purity standards to ensure the DEF's quality.
Is DEF a hazardous material?
No, DEF is not considered a hazardous material. It is non-toxic, non-flammable, and safe to handle when following standard safety guidelines.
What quality standards govern DEF production?
DEF manufacturing is governed by international quality standards, such as ISO 22241, which specify the requirements for DEF purity, composition, and handling procedures.
Can DEF freeze, and what happens if it does?
Yes, DEF can freeze at temperatures below 12°F (-11°C). However, this does not affect its quality. Once thawed, DEF retains its original properties and effectiveness.
How is DEF transported and stored?
DEF is transported and stored in dedicated containers and tanks made of materials compatible with the fluid. It is essential to protect DEF from contamination, extreme temperatures, and direct sunlight during storage and transportation.
What is the shelf life of DEF?
The shelf life of DEF depends on various factors, including temperature and exposure to sunlight and contaminants. Generally, DEF has a shelf life of about one year when stored correctly. It is recommended to use the oldest stock first (FIFO - First In, First Out) to ensure freshness.
Can DEF be mixed with other substances or additives?
No, it is essential not to mix DEF with any other substances or additives. Doing so can compromise its quality and effectiveness in reducing emissions.
Is DEF compatible with all diesel engines?
DEF is compatible with most modern diesel engines equipped with SCR systems. However, it is crucial to ensure that the vehicle's engine is designed to use DEF and that it complies with the manufacturer's recommendations regarding DEF usage.
Conclusion
The manufacturing process of DEF is a critical step in reducing harmful emissions produced by diesel engines. The manufacturing steps ensure that the final product is of high quality and purity, making it an effective solution for reducing emissions. It is essential to follow the production process carefully to ensure that the DEF solution meets the required specifications and is effective in reducing emissions.
