Do you know anything about the MDEA lean liquid/semi-lean liquid desulfurization process?
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Do you know anything about the MDEA process for desulfurization using lean solution and semi-lean solution? What are the functions of each of these solutions? What reaction occurs if MDEA mixes with inorganic ammonia? The gas composition is as follows: CO49%, H2 33%, CO2 15%, H2S 1%, ammonia 0.01%
Semi-poor solution is in contrast to a poor solution. Typically, the hydrogen sulfide level in the lean solution is kept below 2 g/l, while the hydrogen sulfide content in the semi-lean solution is around 4–5 g/l. For example, the amine-rich liquid generated by the sulfur recovery off-gas treatment unit can be considered semi-poor liquid due to its low concentration (usually 4–6 g/l). These semi-poor liquids can be sent as poor liquids to certain upstream hydrogenation units for use.
If the MDEA-rich liquid is not regenerated in the regenerator, but instead goes directly into a flash tank and then into a reboiler for heating, will this achieve the goal of removing hydrogen sulfide?
A flash tank can only remove the hydrocarbons from it, but not hydrogen sulfide.
It can be removed, but not completely; upon returning to the absorption tower, the desulfurization effect is significantly reduced, failing to meet the required standards.
The main goal is to save energy; with heat pump technology, this problem doesn’t exist, as ammonia can be desorbed after being absorbed
At present, the bottom of the regeneration tower is overheated, and the temperature at the top of the tower cannot be increased – it’s only 85 degrees. What’s the problem?
Flash tanks are typically used to remove hydrocarbons; of course, a small amount of hydrogen sulfide may be entrained in the process. Typically, flash tanks are designed with amine-poor liquid absorption at the gas outlet to prevent hydrogen sulfide from escaping.
The semi-poor liquid comes out from the middle of the regeneration tower; it can go to the middle of the flue gas absorption tower or be used as poor liquid in the dry gas liquefied gas desulfurization tower. I think the semi-poor liquid is meant to reduce steam consumption, with little impact on the absorption efficiency. But some designers say it works, maybe they have theoretical calculations to back it up. I don’t think ammonia will react with MDEA. As for side effects, it might cause crystallization in acidic pipelines or at the pressure measurement points of instruments (in areas with low temperatures where flow is poor)
In the centralized regeneration unit, we use a flash tank for separation; it has an oil removal baffle, and when the liquid level rises, the oil is skimmed off