Column packing is the process of creating hollow structures filled with packing materials to aid in the process of mixing liquids with gasses in the same container. The purpose of using packing materials inside the columns is to improve contact between the different phases of the chemical processes happening inside.
In packed columns, the liquid-gas interaction happens as a continuous process rather than in stages. The liquid flows downwards over the packing surface while the gas flows in the opposite direction. A similar principle of column packing is followed in the construction of different types of interactions in towers as discussed below.
Types of Packing Columns
Packing columns may be broadly divided into two categories – random and structured. When column packingis done without any order, it is termed as random, whereas structured packing refers to the ordered placement of the packing materials. Regarding material, the following types of packing are in use currently in various industrial applications.
This type of packing contains around 1000 tiny perforations every square inch of the metal packing pieces. As liquid pushes through them, thousands of projections are formed on the opposite sides of the metal. These, along with the holes help to keep the packing perpetually wet, increasing the efficiency of the system.
The packing material of this type consists of metal wire wound around a rectangular rod. There is a large amount of free space in Heli-Pak type of packing. Stainless steel is the most common material used in this type, but other metals like nickel or bronze are also used.
This type of column packing is inert in nature. It is used in the distillation of corrosive compounds which react to other metals. The process is slow, but useful in working with reactive compounds. Apart from the above, Raschig Rings, Teflon balls, Wire Mesh or customized packing structures are also used for specialized chemical operations.