What is the purpose of packing/fill?

• A. Increased surface area
• B. Increased flow rate
• C. Higher pressure drop
• D. Structural support

Answer: (A)

Packing/fill mainly provides a large contact surface for gas and liquid inside a column. By creating a vast interior surface area, the liquid spreads into many thin films and the vapor flows through numerous tiny channels, giving many opportunities for mass transfer to occur. This makes the separation process more efficient, so you can achieve the desired results with less height or fewer stages. While packing can influence pressure drop and does offer mechanical support to the internals, those are secondary effects. The central idea is that the huge interfacial area enables better gas–liquid contact and mass transfer.