BINARY DISTILLATION IN PACKED TOWERS

Your objectives in studying this section are to be able to  

Understand the advantages of using packed versus trayed towers for certain distillation applications. 

Combine material-balances information from the McCabe-Thiele graphical method with interphase mass-transfer considerations to determine the packed height of the rectifying and stripping sections of a continuous-contact binary distillation tower. 

With the availability of economical and efficient packings, packed towers are finding increasing use in new distillation processes and for retrofitting existing trayed towers. They are particularly useful in applications where pressure drop must be low, as in low-pressure distillation, and where liquid holdup must be small, such as when distilling heat-sensitive materials whose exposure to high temperatures must be minimized. 

By material balance over an incremental section of packed height in the rectifying section, assuming equimolar counterdiffusion (Ng - - NA), 

---