Factors affecting the quality of lean liquid
Thread Content
I read in some materials that excessive regeneration slurry reflux and low tower top temperature can result in liquid of substandard quality; I don’t quite understand this. Could an expert please explain the principle? Thank you, bonus points appreciated
It doesn’t seem logical to me; if there is a large reflux rate and the steam at the bottom of the tower can keep up, it should improve the quality of the lean liquid. The explanation you gave might be that the tower wasn’t operated properly, resulting in insufficient temperature at the bottom of the tower.
What he meant is that the backflow is high, which causes the top temperature to drop; as a result, the temperature of the regeneration tower decreases overall, leading to poor desorption efficiency. However, in practice, a slightly larger backflow does not have a particularly significant impact on the analysis results.
The data indicates that excessive backflow can affect the temperature at the top of the tower; when this temperature is low, the hydrogen sulfide in the feed is affected and moves downward along with the cold stream, based on my understanding. However, in actual production, the most important factor affecting the quality of the lean liquid is the steam supply to the reboiler at the bottom of the tower. As long as the temperature at the bottom is sufficient and operations are carried out properly, there will be no issues with the quality.
My personal understanding is that, generally speaking, regenerative towers are designed with full reflux in mind; it’s not common for the reflux level to be too high, unless amine liquid brings a large amount of water vapor into the system and concentration is needed. Typically, the reflux at the top of the tower is sufficient to keep the upper three trays from becoming dry, thereby improving mass transfer efficiency and preventing water vapor from carrying away the amine liquid. However, when the reflux level is too high, the liquid load on those upper three trays becomes excessive, and the temperature at the top of the tower drops, which in turn reduces the mass transfer efficiency in the lower trays. It depends on just how high the reflux level is and which trays are affected; in other words, after the rich liquid enters the tower, the separation that originally occurred on the 4th tray moves downward, which will have some impact, depending again on the extent of the high reflux level.
Stabilize the temperature at the bottom of the tower by increasing the steam supply to the reboiler
Steady-state backflow is high； High temperature ； The lean liquid is good. You guess it’s in an unstable state ； Backflow is high ； Low tower top temperature ； Hydrogen sulfide was not detected ； It can easily lead to substandard lean liquid.