The dryer cylinder is the hollow cylinder made of cast iron with the covers at both ends, composing of cylinder and the cylinder head at both ends with outer diameter of mostly 1000 ~ 3000mm, during the operation, the passed steam will make the transported paper dry and ironed.
The cast iron dryer cylinder for paper machines is a key component for paper drying belonging to the Class I pressure vessels. The number of cast iron dryers is about 2/3 of the total number of pressure vessels in the paper industry. Manufacturing dryer materials are generally HT200 and HT250. In order to increase the smoothness of the paper, the outer surface of the dryer cylinder is polished and the inner surface is lighted so that the entire dryer cylinder wall is kept in a consistent thickness to ensure that the safety, balance and even heat transfer of the dryer cylinder. The role of the dryer cylinder is to dry the moisture in the paper for finishing paper.
The main components of the dryer include: roll shell, spoiler, siphon, end cap, manhole cover, bearing, shaft head, steam connector and so on.
The saturated steam, which is passed from the steam joint, is condensed inside the dryer cylinder and the released heat causes the dryer temperature to rise, thereby heating the sheet coated on the surface of the roll housing. The heat is transferred to the paper in contact with the surface of the paper and the dryer cylinder.
Evaporative heat release produces a large amount of condensed water. These condensate is attached to the inner surface of the dryer cylinder by centrifugal force due to the rotation of the dryer cylinder. In the case of high angular velocity, a water ring is formed, hindering the transfer of the heat to the dryer cylinder surface, then the siphon will be needed to drain the condensed water in time. In the lower speed, a water ring will not be formed, but there will be condensed water in the dryer cylinder splashing and accumulating.