An analysis of a distillation tower?
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In a distillation column, liquid continuously flows out from the top of the column, while liquid is discharged from the bottom of the column intermittently due to the small amount of liquid that exits there; in other words, liquid is released from the bottom only when a certain liquid level is reached. Question: How can such a distillation column be controlled so as to maintain a constant composition in the bottom of the column and minimize the amount of useful components that are carried away? Is it possible that initially the components at the bottom of the tower consist of more heavy components and fewer light components, and as material is removed intermittently, more heavy components are taken out, which in turn leads to a concentration of light components at the bottom of the tower?
The first is reflux, the second is tower pressure, and then the control of the bottom temperature of the tower
Intermittent efflux does not have a concentration-enhancing effect!
The concentration of the light components increases during reflux, and it is independent of the bottom of the tower; the composition at the bottom of the tower depends on the boiling point difference of the materials. When discharge from the bottom of the tower is required, it is recommended to keep the top extraction unchanged, reduce the feed rate, and resume feeding once the discharge is complete.
If stability must be ensured for the tower feed, the tower top discharge, and the tower top concentration?
That tower kettle can only discharge at a high liquid level, which has a slight impact on its composition. (Depends on the size of the tower bottom)
That’s right; I’ve also noticed that the components have changed, but I’m not sure why or how they changed…
{:3_50:} If the boiling points of your various components differ significantly, and you’re not concerned about coking, you can set a temperature control for the bottom of the tower. As the composition of the mixture changes, if the tower pressure remains stable, the temperature at the bottom of the tower will definitely rise. You can start discharging material when a certain temperature is reached; just implement a feedback mechanism for this purpose. You’ll need to test the discharge rate yourself, making sure that the liquid level at the bottom of the tower stays within the controlled range
{:3_60:} When you adjust the feed rate, there is less heat inside the tower, which means the distribution of the light components shifts downward; as a result, the concentration of light components at the top of the tower increases. If you don’t want this to happen, you can reduce the reflux and feed rates