Decarbonization of synthetic ammonia MDEA solution
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Dear colleagues, I would like to ask you all that recently, the ammonia nitrogen content in the CO2 produced during the regeneration process of the MDEA decarburization reactor in our company’s ammonia synthesis plant has been relatively high. I’m not sure what the cause is, so I’m seeking your advice. Also, the purity of our CO2 often fails to meet the standards; the main reason is that the solution absorbs too much hydrogen and nitrogen. I’m not sure if there’s any way to solve this issue.
Is the pressure control in the flash tank set too high?
In our facility, the removal of hydrogen and nitrogen gas is primarily carried out through high-pressure flash tanks; therefore, the cause must be sought here, possibly in the pressure control system or in the venturi issues, among other things.
The cause of the high ammonia nitrogen level needs to be found in the previous processing stage; our flash vaporization pressure is 0.6 MPa, and the sulfur content is on the high side.
Too much entrainment; it might cause vortices
It depends on your process. Our factory also uses MDEA for decarbonization; if the ammonia nitrogen level is high, it might be due to internal leakage in the heat exchangers or a low concentration of the absorption solution……
What he meant is that the hydrogen and nitrogen levels are high, with a purity of around 98.5%; at the same time, the H2 content in CO2 is high, and the dehydrogenation temperature is high. Hydrogen and nitrogen are inert gases in the urea synthesis reaction. Our company faces the same issue as well; our flash tower is designed for a capacity of 0.6, while we operate it at around 0.48, yet the hydrogen and nitrogen content in the CO2 product remains relatively high. It's also a good idea to check the reboiler.
Consider excessive circulation rate or internal leakage in the reboiler