Impact of increased pressure drop in the methanation system on the ammonia synthesis system
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This post was last edited by TH373637 on 2011-7-1 10:37. Increase in pressure drop in the methanation system: from 1.5 kilograms under normal operating conditions to 3 kilograms – what is the impact on the ammonia synthesis system? Process overview: The 30/52 ICI-AMV process using natural gas as the raw material for production. Similar to the Kellogg process, the load of the first reactor is transferred to the second reactor; 20% more air is supplied to the second reactor. Processes such as Benfield decarburization, methanation, and the Casali synthesis tower (with a synthesis pressure of around 11 MPa) are employed. Additionally, there is a Lind process off-gas recovery system, along with four large-scale units. Three steam turbines and one gas turbine. Seeking help from netizens to discuss and analyze the impact of increased pressure drop in the methanation system on the entire ammonia synthesis system. Thank you; high scores will be given as reward
1. The methanation catalyst becomes deactivated, resulting in poor reaction performance (as indicated by the temperature difference); this increases the likelihood of CO/CO2 levels rising, which can lead to catalyst poisoning in the synthesis tower. 2. If the heat exchanger is clogged, and there is an ammonia cooler present, it may be possible for the temperature to drop too low, causing the process gas lines containing water to freeze. This leads to an increase in pressure difference, thereby increasing the workload on the compressor
If the pressure in the methanation system increases while the load in the previous stage remains unchanged, that is a problem; it indicates that the reaction is not proceeding properly. However, the pressure shouldn’t increase by that much. Another possibility is that there are issues within the system resulting in high resistance, which suggests that the pipes or equipment in this system are blocked. This can lead to incomplete decarburization of CO/CO2, having a significant impact on the subsequent stages, and it may also damage the synthesis catalyst
Hello! The temperature of the gas exiting our methanation reactor is relatively high; it first undergoes heat exchange with the process gas at the inlet of the methanation reactor (with a temperature of 70 degrees), so as to keep the temperature of the process gas at the methanation reactor inlet between 298 and 305 degrees. After that, it goes through heat exchange with circulating cooling water, passes through a separation tank equipped with a demisting screen, and is then sent to the synthesis system. May I ask where your company’s ammonia cooler is installed? Is it during our circulating water cooling step? Thank you, how to control the ammonia cooler?
Our methanation reactor system consists of a methanation reactor, three heat exchangers, and a separation tank. Indeed, such a large pressure drop has occurred; the catalyst was just replaced, and it is suspected that the resistance in the heat exchangers is too high – it’s a bit troublesome
You need to clean the heat exchanger; it seems that the tube side of the heat exchanger where the purified gas exchanges heat with the methanated gas is blocked. We have encountered the same problem with you before. Mainly, you have also chosen phenyldecarboxylation; the purified gas contains a small amount of potassium carbonate, which accumulates in the tube side during the methanation preheating process, forming white, hard deposits that reduce the inner diameter of the tubes. Some of these heat exchangers need to be chemically cleaned; it is recommended that they be cleaned once during the annual maintenance.
It’s very possible, but the problem is that it’s not possible to park the vehicle for repairs at the moment; we have to wait until the next maintenance cycle. Excuse me, since you’re facing this issue, what are the possible remedies? Also, cleaning is done at the end of each major maintenance cycle (which is every two years). Isn’t that a bit too frequent? After all, the cost of cleaning also needs to be taken into account. Thank you for your reply
At the moment, you haven’t affected production either; it’s just that the inlet pressure of the syngas compressor is a bit lower than before, which results in slightly more energy consumption. There is no remedy; after all, he has already blocked it. You can clean it depending on the level of obstruction, and the cost of such cleaning is not high.
Reply to 4# shfuchenko: The process is similar; we keep the inlet temperature at 280–300, and the ammonia cooler is placed after the water cooler, with the temperature kept below 15 degrees