Yankee dryer and other related drying technologies

Abstract

Our first Yankee was on our drawing board in 1891. It was a prototype which was delivered three years later. The Goteborg Mill was our first Yankee customer and the dryer was operating way into the 1980 s. Since then, more than four hundred fifty Yankee cylinders have left our factory in Karlstad, Sweeden. We have developed materials and manufacturing methods. We have made use of state-of-art computer programmes when designing the dryers. The casting process has been refined, machining takes place in computer-controlled equipment. Yankee dryers of jumbo size are found in tissue machines with a production speed of more than 2,000 m/min. Besides, in tissue machine, innovatory TAD (Through Air Drying) technology has been developed. Quality of household paper was greatly improved with the technology. On the other hand, an innovatory technology, Impingement Dryer for paper and board machines to attain much higher drying rate than conventional steam cylinder dryers was invented. It is the key drying unit of OptiDry drying section. This will help paper machines attain a machine speed over 2000 m/min in very near future. Finally, other innovatory drying technology for paperboard is described. That is Condebelt, which is a straight through type of dryer based on press drying. No size press and no calender are necessary with Condebelt. Condebelt attains high smoothness and exceptionally high sheet strength even using low grade of pulps.