[Urea Knowledge] Daily Question (104) 2010.04.14
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This post was last edited by Xinjiu on 2010-4-13 at 19:54. Hide the answer; no scoring will be given unless it is hidden. Specific hiding method: http://bbs.hcbbs.com/viewthread.php?tid=492556&highlight=%D2%FE%B2%D8 Fill-in-the-blank questions: 21. The main reasons for the burnout of centrifugal pump bearings are: ( ), ( ), ( ). 22. The reasons for low current in a centrifugal pump are: ( ), ( ). 23. Before starting up the system for the first time, it is necessary to thoroughly ( ) the equipment in order to remove any debris, rust, and welding slag that may remain inside the pipelines and equipment from the construction process. 24. Below ( ), urea does not undergo hydrolysis in acidic, alkaline, or neutral solutions. 25. Based on studies on the mechanism of urea formation, it is believed that at temperatures below ( ), urea is produced directly through the dehydration of methylammonium, whereas at temperatures higher than this value, urea is formed via an intermediate product ( ). Answer to the question: 21. The main reasons for the burnout of centrifugal pump bearings are: (oil emulsification and deterioration), (lack of oil), and (overload). 22. The reasons for low current in centrifugal pumps include: (low opening of the outlet valve) and (vaporization). 23. Before starting up for the first time, the system must be thoroughly rinsed or purged in order to remove any debris, rust, and welding slag that may remain in the pipelines and equipment from the construction process. 24. Below (60°C), urea does not undergo hydrolysis in acidic, alkaline, or neutral solutions. 25. Based on studies on the mechanism of urea formation, it is believed that at temperatures below 180°C, urea is produced directly through the dehydration of methylammonium, whereas at higher temperatures, urea is formed via an intermediate product (NH4CNO).
21. The main reasons for the burnout of centrifugal pump bearings are: (oil emulsification and deterioration), (lack of oil), and (overload). 22. The reasons for low current in centrifugal pumps include: (low opening of the outlet valve) and (vaporization). 23. Before starting up for the first time, the system must be thoroughly rinsed or purged in order to remove any debris, rust, and welding slag that may remain in the pipelines and equipment from the construction process. 24. Below (60°C), urea does not undergo hydrolysis in acidic, alkaline, or neutral solutions. 25. Based on studies on the mechanism of urea formation, it is believed that at temperatures below 180 °C, urea is formed directly through the dehydration of methylammonium, whereas at higher temperatures, urea is produced via an intermediate product (NH4CNO).
21. Oil emulsification and deterioration, oil deficiency, overload 22. Low opening degree of the outlet valve, vaporization 23. Flushing or purging 24. 60°C 25. 180°C, NH4CNO
21. The main reasons for the burnout of centrifugal pump bearings are: (oil emulsification and deterioration), (lack of oil), and (overload). 22. The reasons for low current in centrifugal pumps include: (low opening of the outlet valve) and (vaporization). 23. Before starting up for the first time, the system must be thoroughly rinsed or purged in order to remove any debris, rust, and welding slag that may remain in the pipelines and equipment from the construction process. 24. Below (60°C), urea does not undergo hydrolysis in acidic, alkaline, or neutral solutions. 25. Based on studies on the mechanism of urea formation, it is believed that at temperatures below 180°C, urea is produced directly through the dehydration of methylammonium, whereas at higher temperatures, urea is formed via an intermediate product (NH4CNO). 1# Heart Juice
21. Oil emulsification and deterioration, lack of oil, overload 22. Low opening degree of the outlet valve, vaporization 23. Flushing or purging 24. 60 degrees 25. 180 degrees, NH4CNO
21. The main reasons for the burnout of centrifugal pump bearings are: (insufficient oil, poor quality of lubricating oil), (excessive tightness between the bearing and the bearing housing), and (inappropriate clearance between the bearing end cover and the bearing). 22. The reasons for low current in centrifugal pumps include: (no flow, light load), and (faulty or inaccurate ammeter). 23. Before starting up the system for the first time, it is necessary to thoroughly purge it in order to remove any debris, rust, and welding slag that may remain in the pipelines and equipment from the construction process. 24. Below (60°C), urea does not undergo hydrolysis in acidic, alkaline, or neutral solutions. 25. Based on studies on the mechanism of urea formation, it is believed that at temperatures below 190°C, urea is produced directly through the dehydration of methylamine, whereas at higher temperatures, urea is formed via an intermediate product (carbamamide).
21. Oil emulsification deterioration, lack of oil, overload 22. Low opening degree of the outlet valve, vaporization 23. Flushing or purging 24. 60 degrees Celsius 25. 180 degrees Celsius NH4CNO
21. The main reasons for the burnout of centrifugal pump bearings are: (oil emulsification and deterioration), (lack of oil), and (overload). 22. The reasons for low current in centrifugal pumps include: (low opening of the outlet valve) and (vaporization). 23. Before starting up for the first time, the system must be thoroughly rinsed or purged in order to remove any debris, rust, and welding slag that may remain in the pipelines and equipment from the construction process. 24. Below (60°C), urea does not undergo hydrolysis in acidic, alkaline, or neutral solutions. 25. Based on studies on the mechanism of urea formation, it is believed that at temperatures below 180°C, urea is produced directly through the dehydration of methylammonium, whereas at higher temperatures, urea is formed via an intermediate product (NH4CNO)
21. The main reasons for the burnout of centrifugal pump bearings are: (oil emulsification and deterioration), (lack of oil), and (overload). 22. The reasons for low current in centrifugal pumps include: (low opening of the outlet valve) and (vaporization). 23. Before starting up for the first time, the system must be thoroughly rinsed or purged in order to remove any debris, rust, and welding slag that may remain in the pipelines and equipment from the construction process. 24. Below (60°C), urea does not undergo hydrolysis in acidic, alkaline, or neutral solutions. 25. Based on studies on the mechanism of urea formation, it is believed that at temperatures below 180°C, urea is produced directly through the dehydration of methylammonium, whereas at higher temperatures, urea is formed via an intermediate product (NH4CNO). 1# Heart Juice
21. The main reasons for the burnout of centrifugal pump bearings are: (lack of lubrication), (low installation accuracy), and (incorrect selection). 22. The reasons for low current in centrifugal pumps include: (low flow rate), (air locking). 23. Before starting up the system for the first time, it is necessary to thoroughly purge it in order to remove any debris, rust, and welding slag that may remain in the pipelines and equipment from the construction process. 24. Below (60°C), urea does not undergo hydrolysis in acidic, alkaline, or neutral solutions. 25. Based on studies on the mechanism of urea formation, it is believed that at temperatures below 140 degrees Celsius, urea is produced directly through the dehydration of methylammonium, whereas at higher temperatures, urea is formed via an intermediate product (dimethylurea).
21. The main reasons for the burnout of centrifugal pump bearings are: (lack of cooling water), (idle operation), and (the outlet valve not being opened). 22. The reasons for low current in a centrifugal pump are: (low flow rate), (idle operation). 23. Before starting up for the first time, the equipment must be thoroughly cleaned to remove any debris, rust, and welding slag that may remain in the pipelines and equipment from the construction process. 24. When it is less than (4 hours), urea does not undergo hydrolysis in acidic, alkaline, or neutral solutions. 25. Based on studies on the mechanism of urea formation, it is believed that at temperatures below (40), urea is produced directly through the dehydration of methylammonium, whereas at temperatures higher than this value, urea is formed via an intermediate product ( ).