Dalian low temperature methanol washing problem?
Thread Content
What is the purpose of adding a small stream of lean methanol to the methanol water washing tower in Dalian low-temperature methanol washing? I've seen others add a stream of desalted water. Is there any difference between the two? Which effect will be better? Expert guidance. . . . . .
The purpose of adding a small stream of lean methanol is to control the temperature of the methanol vapor in the methanol-water separation tower, that is, the purity of the methanol vapor. (This methanol is in the upper part of the methanol-water separation tower.) Others add a stream of desalted water. This water is in the middle of the methanol-water separation tower and is mainly used for cleaning the trays. The feed to the methanol-water separation tower is also in the middle. The functions of these two materials are different.
Haha, adding a stream of lean methanol seems to be used for reflux. When the water content in the right chamber at the bottom of T4 increases, this lean methanol can be used to ensure the purity of the methanol vapor entering T4 from T5. That water should be used to rinse the tray! [Please ask the poster to explain the location of these two materials so that we can analyze it more accurately]
The most basic reflux of the distillation column. That water flushing the tray? Personally, I think it remains to be determined. The optimal concentration for the operation of the methanol-water separation tower is 38-55%, and the concentration of water-containing methanol coming from the system is much greater than this concentration. Therefore, adding desalted water is conducive to the separation of water and methanol.
In fact, the main function of this is to directly inject methanol when the water content at the top of the tower exceeds the standard, so that the water content at the top of the tower can be reduced to the required value at a faster speed.
The purpose of sending this methanol to the methanol-water separation tower is to reduce the water content of the system and maintain the water content in the system within the target range. This can reduce the impact of water on absorption and corrosion of equipment. As for desalted water, it should be the purpose of cleaning the tray... But I also think it has the function of maintaining the liquid level.
I think there is no optimal feed composition. It mainly depends on the feed concentration determined when your distillation column was originally designed!
It can also be said that it has the function of maintaining the liquid level, but if you look at the position of the pipeline, it may be possible if it is at the bottom of the tower, but it is absolutely impossible if it is at the top of the tower!
1. Regenerated methanol must be added to the top of the tower, and desalted water is added to the middle and lower parts of the tower below the feed. The added desalted water not only washes the trays, but also stabilizes the liquid level and provides heat to the entire tower as a heavy component.
"What do you understand by "providing heat to the entire tower as a heavy component"? Could desalinated water also provide thermal pressure?
The heavy component is the carrier of heat. It absorbs heat from the reboiler and vaporizes into steam, bringing heat to the entire tower during the rising process! It is a carrier of heat!
In the methanol-water separation tower, generally the light components form rising steam, and the heavy components usually go down to the column kettle after being added to the feed plate. The heavy components can only absorb heat in the column kettle, and even if they generate rising steam, it is not much. Personal opinion. . .
The main function is to improve the purity of methanol steam