Copper cleaning solution
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Recently, our ammonia synthesis copper washing process has been experiencing liquid carryover issues. All possible factors such as gas flow rate, load, H2S content, and oil discharge have been checked; adding castor oil can help alleviate the problem to some extent, but it recurs again. I suspect that due to the influence of coal, the levels of ethylene and acetylene in the gas are relatively high, which is causing problems with the copper washing solution. I would appreciate some advice: can high levels of acetylene and ethylene lead to issues with the copper washing solution? What are the acceptable levels? How can these problems be resolved? Which components in the feed gas can cause issues with the copper washing solution?
This post was last edited by Chemical Gas Purification on 2011-4-24 at 13:42. The levels of acetylene and ethylene should be low; otherwise, copper acetylide or other impurities may form, leading to blockages that cause liquid to carry over
What process is used for decarbonization? If decarburization is carried out using carbon propylate liquid, it may be that the vapor of carbon propylate liquid entrained enters the copper melt, causing the copper melt to foam.
The copper washing solution needs to be analyzed comprehensively; the main external factors are organic sulfur contained in the gas supplied, or mist generated by the use of chemical fertilizers as additives in the carbonization process, which ends up reaching the copper washing stage. The internal reasons are mainly the composition of the copper melt: insufficient acetic acid content and poor filtration of the copper melt. An excess of impurities and precipitates in the copper melt can all lead to periodic liquid carryover. As for the increase in the content of acetylene or olefins in the off-gas, they will first react with the shift catalyst and the ammonia synthesis catalyst, resulting in catalyst poisoning. It is necessary to analyze the specific situation in order to find the root cause.
Thank you for your valuable suggestions; they have been very inspiring to me. We use a low-temperature converter to convert a small amount of carbon monoxide, remove carbon dioxide with ammonia water, and then remove carbon monoxide as well. Originally, methanol was turned on before copper washing, but now it is not turned on. The carbon monoxide entering the copper washing unit has increased from 1.5% when methanol was used to 2.8% at present, and the capacity of the copper tower has risen from 500 to 700. The quality of coal we use now is inferior to that in the past, and we suspect that ethylene and acetylene are being generated in the gas. Samples have been sent to the relevant authorities for analysis, and the results are not available yet. Well, yesterday afternoon it started leaking again; it’s really frustrating. Acetylene is removed by copper washing; it is unknown whether ethylene can be removed as well. It can be said that ethylene and acetylene have no effect on the shift catalyst; if they are present, copper washing cannot remove them, while the synthesis catalyst can reflect their presence.
Adding defoamers and separators – the issue with copper washing liquid has been a persistent problem in the old processes, and there isn’t really a good solution. It’s better to keep using methanol; currently, the price of methanol isn’t such that it would result in losses. When taking into account the costs associated with copper washing as well as the losses incurred in ammonia and urea production, it remains economically viable
May I ask which company in Hubei is the poster from?
Reply to Floor 1: Since it’s not any of those reasons, there are still the following two possibilities; the original poster might want to check them out. 1. Using a carbon-propylene NHD decarburization process can cause severe bubbling in the copper melt due to liquid remaining in the system； 2. Acetylene in the system forms copper acetylide, resulting in severe bubbling.