Yankee dryer

In industry, MG cylinders or Yankee dryers are primarily used to remove excess moisture from pulp that is about to be converted into paper.

The big dimension generates a problem with the elimination of the condensate forming inside the cylinders, therefore all yankees use a system with blow through steam which than it is re-compressed by help of a thermocompressor (ejector).

The straws are combined in racks and these go to typically 6 collectors which take the condensate-steam mixture towards the center of the cylinder from which then it is taken out into usual piping and brought to the separator.

For example, a yankee which is receiving steam while it is not rotating may be damaged by the temperature difference of the bulk to the bottom of the cylinder where the condensate is present.

Particular attention shall be taken in case of fire, as direct jets of cold water on the surface of the hot yankee may damage it.

The base coating usually also has adhesive properties and keeps the paper attached to the yankee surface until creping 2) a release agent based on mineral or vegetable oil or waxes which lubricates and improved the detaching of the paper from the surface 3)various modifiers, which may make the coating more soft or hard or improve the protective effect on the yankee The coating is sprayed together with water in the space between the creping blade and the press through a spray bar with nozzles.

Only the narrow space between this spray bar and the press is the one in which the water coming with the coating shall be evaporated and the polymer has to cure.