Urea: One Question per Week Special Thread
Thread Content
This post was last edited by qiwu9981 on 2009-10-20 at 20:40. Here, we come up with some practice questions related to our job duties every week in order to improve our professional skills, and there are also exams at the end of each month. I wonder if something similar exists where you are. Now I’m applying it to Haichuan; I hope everyone will participate actively. Those who give good answers will receive generous rewards. Now I present the questions for the first issue: the answers will be announced on Sunday. 1. After short-term parking and resuming operation, no liquid level was observed in Tower 1 after two hours of feeding. State the possible reasons and solutions. (Urea production by full circulation of aqueous solution) This post was last edited by qiwu9981 on 2009-3-4 19:29]
“After parking the vehicle for a short period and starting it up again, no liquid level was detected in Tower 1 after two hours of feeding. 1. What was the load at that time? 2. How is the condition of the absorption tower? 3. What are the temperature and steam consumption levels? 4. What is the pressure in the synthesis tower while driving? 5.Is the P4 valve opening normal?
What was said on the 2nd floor is correct – without detailed data, analysis is not possible. Such questions can be used to train workers in the workshop, but more data should be provided here in order to enable proper analysis.
It might be that the steam heating in one tower is set too high, and urine is being poured into one of the absorption towers. Solution: Reduce the steam supply or turn it down to a lower level.
What’s the condition of the synthesis tower? The liquid level of the absorption tower? The pressure of the medium-pressure system?
Evaporation, flash evaporation – is there a liquid level indicator at the site? Is there liquid present?
Let me tell you the possible answers; they may not be entirely accurate, so please take a look. Possible reasons: blockage in the liquid discharge pipe below the pre-separator, with urine leaking from the gas phase of the separator into one of the absorption towers, resulting in high liquid levels in that tower and preventing proper drainage. This type of situation occurs when the discharge pipe of the synthesis tower is not cleaned or is not cleaned thoroughly after shutdown. Solution: Reduce it to the minimum amount, wash the outlet pipe using high-pressure flushing water, and open the flushing port at the inlet of the fractionating column’s \"U\"-shape section for backwashing in order to remove any accumulated liquid; then purge the liquid-conducting pipes using condensate and steam. When one absorption tower can no longer function, the system stops operating, and the feed pipe is purged. I’m presenting the questions for the second phase: The pressure in the secondary tower is high, while the pressure in the secondary condenser is below the specified level. What could be the possible causes and how should they be addressed? This post was last edited by qiwu9981 on 2008-10-25 12:54.]
It is also possible that the instrument readings are faulty; the opening degrees of the main and auxiliary valves in the double-tower system are too large; or the system volume is low.
““The liquid outlet pipe of the pre-separator is blocked, and urine leaks from the gas phase of the separator into Section 1 of the absorption tower” – this is impossible; a careful analysis of the structure of the separator and the associated heater shows that such an assertion is not valid. The liquid outlet pipe of the pre-separator becomes blocked, preventing urine from entering the heater; as a result, the liquid level in the pre-separation section rises. Once this level reaches above the top of the vapor outlet, urine flows from the vapor outlet into the lower separation section. In other words, a liquid level is then detected inside the first column, but it is urine that has not passed through the first heater. Don’t you think so, OP? This post was last edited by qiwu9981 on 2009-3-4 19:30.]
The pressure in the secondary distillation tower is high, while the pressure in the secondary circulation second condenser is below the specified value. Possible reasons: 1. There is a blockage in the gas phase pipeline of the secondary distillation tower (the demister screen has been displaced, material crystallization, etc.) or a gas flow obstruction. 2. There is a blockage or gas flow obstruction in the gas phase of the secondary circulation first cooler
It’s normal for there to be emissions from the absorption tower when the vehicle is first started. I also think the answer given by the original poster is incorrect; I agree with the analysis provided by user number 9