Issues related to corrosion in urea production using CO2 stripping
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In the urea production process using the CO2 stripping method, if the nickel content increases, for example: normally 0.20PPM. It suddenly rose to 0.26PPM. Can it be repaired by increasing the oxygen level?
This post was last edited by 1573 on 2017-7-16 at 11:51. Oxygen or hydrogen peroxide can be added, and it can have a certain effect! ! ! But the key is still to optimize the process operations and strictly follow the operating procedures! !
We increase the amount of air added; for example, the normal oxygen content is 0.6–0.8%, while we raise it to 1.0%. But sometimes the nickel content gradually decreases and returns to normal, while at other times it doesn’t decrease at all, forcing a stop to carry out passivation. How can this phenomenon be explained?
We increase the amount of air added; for example, the normal oxygen content is 0.6–0.8%, while we raise it to 1.0%. But sometimes the nickel content gradually decreases and returns to normal, while at other times it doesn’t decrease at all, forcing a stop to carry out passivation. How can this phenomenon be explained?
There is information on this topic in the collections of papers from the 15th and 16th National Annual Conferences on Urea Plants held on this forum. It is recommended to visit http://bbs.hcbbs.com/thread-317040-1-1.html for an analysis of the corrosion issues associated with the 202C urea production equipment using the CO2 stripping method, along with corresponding solutions
To improve oxygenation, first check the results; additionally, it is necessary to analyze whether hydrogen sulfide levels are above the limit An increase in nickel content is not necessarily a sign of corrosion in the synthesis system; corrosion issues can also occur in the low-pressure and hydrolysis systems. Only by conducting a thorough analysis can a decision be made regarding shutdown passivation, and it cannot be decided simply based on an increase in nickel content. What if the nickel content remains high even after shutdown passivation and the system is restarted and operates normally?
1. Of course, we will decide to increase the oxygen content only after confirming that abnormal corrosion has occurred in the high-pressure system; if the situation doesn’t improve, then the system will be shut down for passivation, and after passivation, the nickel content will return to normal. 2. We believe that the anomaly is caused by abnormal corrosion under high pressure, which increases the nickel content; when the oxygen content rises, the nickel content sometimes decreases gradually, while at other times it does not decrease
Oxygen addition is intended to help form a better passivation film; to determine whether there are any process changes, it is necessary to check whether the desulfurization in the previous stage is functioning properly
Ah, our nickel content is already at 0.36, and the manager hasn’t ordered us to stop – there’s no intention of stopping at all. One day it’s going to break down
Recently, the nickel content in our system has increased by 0.4, while the oxygen content has risen by 1.0%. It doesn’t work well.
Recently, during normal production, the nickel content suddenly increased to 0.39–0.53, while the oxygen content in the system rose from 0.8% to 1.1%. After continuous monitoring for three days, the nickel content dropped to 0.23%. The effect is pretty good. Hehehe O(∩_∩)O Hahaha~