Syngas decarburization
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Methane synthesis gas contains a small amount of ammonia. During the CO2 removal process using MDEA solution, I wonder whether ammonia can remain in the MDEA solution along with CO2. Please advise, thank you:handshake
It can be done. This needs to be considered from two aspects: first, N-methyldiethanolamine is itself a basic solvent that does not absorb ammonia. Second, water itself can dissolve a large amount of ammonia, and it can form ammonium bicarbonate with the acidic gas carbon dioxide
The ammonia content is required to be less than 0.1PPM. Ammonium bicarbonate begins to decompose at temperatures above 36 degrees, while the optimal temperature for MDEA solutions is between 42 and 48 degrees. Heat is released during the absorption of CO2. If ammonium bicarbonate decomposes, will it be difficult to meet the requirements regarding ammonia levels? Thank you for your advice!
Oh, I see. There are two points to note: 1. The decomposition temperature of ammonium carbonate at 30–40 degrees Celsius is an indicator for its solid state; 2. Even so, it is difficult to maintain an ammonia content of 0.1 ppm, so alternative approaches are necessary. Before proposing a solution, there is one question first: where does the ammonia come from? Is there a carbon chemical processing section with concentrated ammonia in front of the MDEA?
The feed gas is obtained after the purification of coke oven gas, while the source of ammonia should be derived from the decomposition of coal
This is really annoying; if it isn’t absorbed, it’s harmful to subsequent processing stages, but if it is absorbed, is there any benefit? If nothing else works, then carry out pickling or use porous materials for absorption
Thank you for the advice. We currently use water wash towers for cleaning; this method meets the required standards, but it generates a lot of ammonia water that needs to be treated, which is quite troublesome
For coke oven gas, is MDEA used for removal – with or without ash? And what about coal tar? ?
The ash and coal tar have been removed at the upstream stage; what reaches us is what is known as purified gas, but it still contains CO2 and ammonia
Removal by soft water spraying, in the previous ammonia washing tower