Kier (industrial)

A kier, keir or keeve is a large circular boiler or vat used in bleaching or scouring cotton fabric. They were also used for processing paper pulp.
In use they were continuously rotated by an engine, steam being supplied through a rotating joint in the axle. They were usually spherical, sometimes cylindrical, and some were recycled from old boiler shells.

Kier boiling

Kier, the cylindrical-shaped vessel, straight, with egg-shaped ends made of boiler may have the capacity to process one to three tons of material at a time.
Kier boiling and Boiling off is the scouring process that involves boiling the materials with the caustic solution in the Kier, which is an enclosed vessel, so that the fabric can boil under pressure. Open kiers were also used with temperatures below 100°C.