Does the ammonia synthesis process using liquid nitrogen washing still require hydrogen recovery?
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Does the ammonia synthesis process using liquid nitrogen washing still require hydrogen recovery?
Reply to 1# 654262293: It can be decided whether hydrogen recovery is necessary based on the actual hydrogen loss situation.
The methane content in the ammonia synthesis process using liquid nitrogen washing is very low, so there is no need for hydrogen recovery.
The key lies in the amount of syngas purge gas used; whether to use it or not is determined entirely from an economic perspective, considering whether the costs of investment and the savings generated are equivalent.
The last edit to this post was made by 654262293 on 2010-7-19 at 16:36. The main purpose of liquid nitrogen washing is to perform final purification of the process gas, removing the CO and CO2 components that are harmful to the ammonia synthesis catalyst. Other impurities such as CH4 and Ar are also removed at the same time. The liquid nitrogen washing process offers high purification efficiency; at low temperatures, it can completely remove gases such as CO, CO2, and CH4, resulting in a syngas composition of H2:N2=3:1. As a result, there is no off-gas in the synthesis loop, which reduces gas losses, and the compression power consumption in the ammonia synthesis loop is also lower. Therefore, there is no need for hydrogen recovery anymore.
In the ammonia synthesis process that uses liquid nitrogen washing, when the tail fluid is depressurized to 17 KGF, several hundred cubic meters of hydrogen gas evaporates; this hydrogen can be fed to the cycle gas compressor in the low-temperature methanol washing process for compression and reuse. There is no need for hydrogen recovery.
Reply to 5# 654262293: Brother, I strongly request that you change your profile picture, okay? I come here almost every day to take a look; there’s so much to see that it dazzles my eyes!
To give a practical example, for our 500,000-ton capacity of synthetic ammonia production, we use liquid nitrogen for washing, and there is no hydrogen recovery system in place
Reply to 7# guxuewen2003: Haha, of course! I’ve read many of your explanations for various issues on this; they’re great, and you have your own unique insights. I’ve also learned a lot from it. I’ll definitely ask you for advice sometime; hey, do you have an email address? A QQ number works too; I have many questions I’d like to ask you
The syngas purified by the methanol wash process results in no continuous off-gas discharge from the synthesis loop; theoretically, there is no off-gas discharge from the synthesis loop at all. So there is no need for a hydrogen recovery unit anymore.
What was said on the 5th floor is correct: using liquid nitrogen for cleaning allows CO, CO2, CH4, etc. to be completely removed at low temperatures, with no off-gases generated, and there is no need for hydrogen recovery.