Continuous Distillation Packed Column: Liquid Level Buffer Sizing at Column Bottom
Continuous Distillation Packed Column: Liquid Level Buffer Sizing at Column Bottom
(OP)
When designing a continuous distillation column is there a design procedure / rule of thumb to select how much of a liquid level one must keep at the column bottom?
This is a vacuum column (10 mmHg abs), in the petrochemicals industry with a forced circulation reboiler. The column has structured packing and the diameter is 900 mm.
Would it be reasonable to select the level to size for (say) 15 minutes of bottom draw off? The required holdup for 15 mins is coming quite small, approx. 300 L which I can get in less than 1 m of liquid level for this column dia.
This is a vacuum column (10 mmHg abs), in the petrochemicals industry with a forced circulation reboiler. The column has structured packing and the diameter is 900 mm.
Would it be reasonable to select the level to size for (say) 15 minutes of bottom draw off? The required holdup for 15 mins is coming quite small, approx. 300 L which I can get in less than 1 m of liquid level for this column dia.





RE: Continuous Distillation Packed Column: Liquid Level Buffer Sizing at Column Bottom
RE: Continuous Distillation Packed Column: Liquid Level Buffer Sizing at Column Bottom
Shutdown in our unit probably means shut the steam inlet to reboiler & blow away any residual Steam pressure. Then drain all the column material out.
RE: Continuous Distillation Packed Column: Liquid Level Buffer Sizing at Column Bottom
Just curious: When you write "Column sump" was it just a column bottom end section (cylindrical) of same dia as rest of column but with no plates / packings? Or was it something different.
RE: Continuous Distillation Packed Column: Liquid Level Buffer Sizing at Column Bottom
Not clear what blowing away residual steam is to be built into the reboiler design.
We had a reboiler feed sump and reboiler return sump sections in the column bottom sump, separated by a vertical plate that extended to partway down to the low point in the dished end. This sump was of a larger dia than the rest of the column to enable this 30minutes holdup time.
RE: Continuous Distillation Packed Column: Liquid Level Buffer Sizing at Column Bottom
RE: Continuous Distillation Packed Column: Liquid Level Buffer Sizing at Column Bottom
RE: Continuous Distillation Packed Column: Liquid Level Buffer Sizing at Column Bottom
RE: Continuous Distillation Packed Column: Liquid Level Buffer Sizing at Column Bottom