2. Internal equipment

The first distillation units appeared around 150 years ago. The Cellier-Blumenthal unit has two types of plate. The lower part of the column contains a stack of spherical cap-shaped disks whose concavities face alternately upwards and downwards; the disks with the concavities facing downwards are perforated to increase the contact area between the liquid and vapor phases. The upper part of the column is equipped with trays featuring a single cap.

At the beginning of the twentieth century, while single-cap trays were still the most common type, Savalle's rectangular tunnel trays, multi-cap trays (Egrot) and perforated trays (Siemens) began to appear.

Initially, linings were made of coke, pebbles, flint and ceramic balls. The first lining to be manufactured and widely used was the Raschig ring, a simple section of tube whose height is equal...