Unit operation

Unit operations involve a physical change or chemical transformation such as separation, crystallization, evaporation, filtration, polymerization, isomerization, and other reactions.

A process may require many unit operations to obtain the desired product from the starting materials, or feedstocks.

Arthur Dehon Little developed the concept of "unit operations" to explain industrial chemistry processes in 1916.

There is a range of solutions, because a higher reflux ratio enables fewer plates, and vice versa.

The engineer must then find the optimal solution with respect to acceptable volume holdup, column height and cost of construction.