Raschig Rings
Small thick-walled tubes, non-glazed special ceramic with its resistence against chemical influances. Mainly used in a petrochemical industry as a filling for destilations or absobtion columns.

A German engineer Frydrich Raschig in 1890 came up with a technology of fractional destilation in columns through ceramic rings.

A characteristic diameter of ceramic rings depent on diameter of the column and a number of distributive partitions

Today, this technology grows through new ideas, e.g. Pall rings of Berla rings.
The advantage of Raschig rings is its low-cost production. For its values the Raschig rings are highly used at technological processes where columns are used.