Amine solution temperature issue

The amine solution is ultimately cooled by circulating water, so its temperature is around 40 degrees, similar to that of the circulating water.

It is generally necessary to keep the temperature about 5-10 degrees higher than that of the raw materials, in order to prevent hydrocarbons from condensing. A too high temperature is not conducive to absorption and also increases the loss of amine in the gas phase.

Lower temperatures affect the absorption efficiency (the rate); there must be an optimal value, right?

The optimal temperature for absorption is 40 degrees. It’s best to keep the amine solution at around 40 degrees as well

The lower the temperature, the more favorable it is for absorbing H2S, but it also increases the amount of hydrocarbons absorbed. Furthermore, to reduce the amine solution to below 40°C, a large amount of cooling capacity is also required.

Could it be considered that the temperature of the exhaust gas should be the same as the temperature of the amine solution entering the absorption tower? Prevent high water content in the amine solution :) :)

It can be said that lower temperatures are more conducive to the absorption of hydrogen sulfide. In our standard operations, the optimal absorption temperature for the amine solution is around 40 degrees Celsius, and the amine solution is cooled through several stages before being cooled further by circulating water, resulting in a temperature of approximately 40 degrees Celsius. Currently, some sulfur plants have begun to attempt operation at lower absorption temperatures, with fairly good results.

The absorption of H2S by amine solution is a process of chemical absorption. High pressure and low temperature are favorable for this absorption, but it’s not the case that the lower the absorption temperature, the better. Low temperatures increase the viscosity of the amine solution, which affects the mass transfer rate and results in an increased sulfur content in the exhaust gases； High temperatures affect the conversion rate of the chemical absorption equilibrium, leading to an increase in the sulfur content in the exhaust gases. The optimal lean liquid temperature is 38 degrees. Additionally, the pressure difference in the tower can accurately reflect the absorption efficiency of the absorber; generally, this pressure difference should be kept within 20 kPa. A high pressure difference indicates that there may be liquid accumulation in the tower or that the tower is blocked. In such cases, it is necessary to prevent tower flooding accidents, reduce the operating load, and decrease the amount of lean amine solution used.

The principle of absorption is low temperature and high pressure. Is there any theoretical basis for the 38 degrees and 20 KPA mentioned above? Thank you~