Bottom Plate and Reboiler

Fig: Material balance diagram for bottom plate and reboiler (source: Unit Operation of chemical engineering; W.L McCabe )

Material balance diagram for bottom plate and reboiler is shown in above figure. The lowest point on the operating line for the column itself is the point for bottom plate (Xb, Yr) where Xb and Yr are concentrations in the liquid leaving bottom plate and vapor coming from reboiler. However, operating line can be extended to cross diagonal at point (XB, XB).

The equation of stripping operating line when written for constant molal overflow,




Partial reboiler are most widely used reboiler that vaporize only part of liquid in the column base. Here, vapor leaving reboiler is in equilibrium with liquid leaving bottom product. Then XB and Yr are coordinates of point on the equilibrium curve and reboiler acts as an ideal plate, as partial reboiler also provide ideal separation stage. In above graphical construction, reboiler is shown by ∆cde and bottom plate by ∆abc.



About Author

Name : Pratiksha Shrestha

Ms. Shrestha holds masters degree in food engineering and bioprocess technology from Asian Institute of Technology (AIT) Thailand. She is currently working for Government of Nepal at Department of Food Technology and Quality Control (DFTQC), Kathmandu. She is also a teaching faculty in College of Applied food and Dairy Technology (CAFODAT) affiliated to Purbanchal university, Nepal.