On CO poisoning of synthetic catalysts
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A few days ago, excessive CO levels at the cold box outlet caused the catalyst in Column 1 of the synthesis tower to become temporarily inactive. After operating for some time, the temperature at that catalyst bed gradually increased. Could you tell me the CO levels at the inlet of your synthesis tower?
Former ammonia synthesis plants required that the trace amount of (CO+CO2) in the fresh synthesis gas be less than 15 ppm; if this value exceeded it, the temperature of the synthesis tower would change significantly, the synthesis catalyst would show signs of poisoning, and the system would need to operate at reduced capacity. New large-scale ammonia synthesis plants now use liquid nitrogen washing technology; what are the specifications? The original poster, please share!
Our target is 10 ppm, but this time it exceeded that level by more than half an hour; the temperature at Bed 1 dropped significantly, while it increased at Bed 2
Previously, ammonia synthesis plants required that the trace amount of (CO+CO2) in the feed gas be less than 15 ppm; however, when this level exceeded 10 ppm, the catalysts in the synthesis towers would react, which increased operational difficulties and reduced production.
Reply to 4# 654262293: I wonder if you moderators can analyze the CO of your synthesis circuits as well? It is said that interference from other components prevents accurate analysis, so it’s not possible to determine exactly how much CO is present in the circuit
This can be analyzed; it’s a normal and important type of analysis. It can also be observed through online monitoring. CO causes temporary poisoning, and the situation will improve after operating for some time. It is recommended to install protective equipment in front of the tower
CO2+CO is generally kept below 10 ppm. Analysis can be analyzed. And there are online analyzers available, which can carry out detections. Generally, after the catalyst in a synthesis tower is poisoned by CO, increasing the H level can allow it to be reduced again. But it affects the ultimate lifespan of the catalyst.
Our facility uses an older processing method, with levels generally kept below 30 ppm
Why does CO appear in the synthesis section?
The appropriate level of micro-control also depends on the sophistication of the manufacturing process; with advanced processes, it’s possible to achieve levels below 5, while in ordinary cases the level is between 10 and 15. As mentioned earlier, there are also values of 30, with the unit being PPM. Generally speaking, the lower the better, though it is determined by the manufacturing conditions. After poisoning, it affects the catalyst’s activity; it is common to need to carry out reduction in hydrogen production. For detection, it is generally at the location after methane synthesis and before compression. It might not be this unit in other places either. This sudden increase in the trace amount also represents a test of the skill level of the operators in the synthesis tower. Generally speaking, such increases do not occur all the time, and it is not easy to detect them immediately; it would be best if one could identify such situations in advance by observing a drop in temperature.