Urine tower testing and management
Thread Content
Inspection and management of urine towers (1) During the inspection of urine towers, attention is often focused on the lining; while the condition of the lining is indeed an important indicator to determine whether the tower can be used, the inspection of the outer cylinder is also crucial. Therefore, during routine inspections and maintenance, it is necessary to pay more attention to checking the outer layers as well as conducting flaw detection on the welds. During startup and shutdown, the rate of temperature increase or decrease must be strictly controlled, and close attention should be paid to the temperature difference inside and on the walls of the tower, in order to prevent damage to the equipment due to inadequate control. Due to the strong corrosiveness of the urea-ammonium solution inside the tower, the innermost layer of the urea tower is an 8 mm thick corrosion-resistant stainless steel lining, with a carbon steel plate layer (for bearing pressure) right outside it. Steam or air is used for leak detection between the lining and the carbon steel cylinder through leak detection holes. Since the outer carbon steel cannot withstand the corrosion caused by urea-ammonium solution, once there is a large-area leak in the stainless steel lining, the carbon steel cylinder will eventually fail to resist the operating pressure due to corrosion and break apart. This is especially true when some of the layers in the urea tower are made of high-strength steel such as 15MnVR; in such cases, stress corrosion is more likely to occur when there are problems with the leak detection system, leading to cracks in those layers. The maintenance of the lining during operation and maintenance is crucial for the safety of urea production. (2) While ensuring the proper use of cylinder leak detection methods, it is necessary to increase the frequency of leak checks at areas such as the top flange and the top cover, so that any issues can be detected and addressed promptly. When it is found that leak detection is not functioning properly, it must be addressed promptly, and the analysis results prior to the failure should be reviewed; if the analysis results are abnormal, the system should be stopped immediately for treatment. (3) Strengthen the management of tower insulation to ensure it remains in good condition; conduct thorough inspections of connection points such as thermocouples and leak detection holes, and repair any damage promptly to prevent stress corrosion caused by large temperature differences resulting from damaged insulation.
The poster is absolutely right; it’s impossible to inspect the lining during regular checks. Moreover, we cannot see any changes that occur between the lining and the blind layer, or between the various layers themselves. We have to rely on changes in air leakage or steam leakage to detect such issues. Only when changes in the leakage patterns are detected will operations be stopped for a thorough inspection. Therefore, it is very important to monitor all the gaps in the urine tower.
Inspection and management of the urea synthesis tower are very important, as the pressure is so high. Once an accident occurs, the impact is very significant. Out of responsibility for the safety of businesses and one’s own life, it is still necessary to pay attention on a regular basis.
Inspections of synthesis towers are not just about methods; they also need to be institutionalized. And supervise the implementation!