Relationship between extremely low temperatures and the temperature of the lean amine liquid in the regeneration tower
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Hello, everyone! I would like to ask whether the difference between the temperature at the top of the extremely cold tower and the temperature of the lean amine solution at the top of the regeneration tower is related to the SO2 emissions in the exhaust gases Currently, the vapor phase temperature at the top of the cryogenic tower is 34°C, and the temperature of the lean amine liquid at the top of the regeneration tower is 35°C.
This post was last edited by ylb913 on 2015-7-17 10:28; it is about the exhaust gas quench tower and the exhaust gas absorption tower. I feel that it is only when the temperature of the lean amine solution exceeds 38.5 degrees that it begins to affect the efficiency of exhaust gas absorption. Of course, the temperature of the gas is also a bit lower, around 34 degrees, which is similar to ours.
The temperature of the process gas at the exit of the quench tower differs from the temperature of the lean liquid by 3–4°C, and the tail gas absorption tower achieves the best absorption efficiency. If the temperature of the process gas at the outlet of the quench tower is too high, the amount of saturated water in the process gas increases. This leads to a decrease in the concentration of the amine solution upon entry into the exhaust gas absorption tower, and it also results in losses of amine solution, as it is carried away with the process gas to the tail furnace ； Excessively high amine solution temperature is detrimental to the absorption of hydrogen sulfide, leading to an increase in sulfur dioxide levels in the flue gas.
The temperature at the outlet of the quench tower is generally lower than that of the lean liquid, around 33 degrees; this prevents the amine solution from containing water, resulting in better absorption efficiency. The temperature of the amine solution is usually maintained at around 35 degrees.
Thank you all for your attention; I understand.
If the temperature of the amine solution is too low, the absorption efficiency is poor, and this is related to the solubility of hydrogen sulfide in the amine solution
The solubility of CO2 is higher than that of H2S; if the temperature is too low, more CO2 will be absorbed, which means less H2S will be absorbed. Is that what it means? Are there any other implications?
Isn’t it true that the absorption efficiency is best when the temperature of the lean amine solution is around 39°C? For the exhaust gas coming out of the quench tower, of course, the lower the temperature, the better, as it leads to an improved absorption effect.
One is through gas-phase absorption, and the other is through liquid-phase absorption; CO2 reacts instantly with the amine solution to produce ammonia.
It might also be related to the amine solutions produced by different manufacturers; as long as we allow the temperature of the amine solution entering the absorption tower to exceed 37 degrees, the sulfur dioxide levels in the exhaust gas will rise sharply.
40°C is a theoretical value; in actual production, it is sufficient to maintain the temperature of the amine solution at the level specified by your company. The temperature difference is not large, and it is also easy to keep the concentration of the amine solution stable.