Yankee dryer

Other types of dryers may be employed for special products or situations. For example, the Yankee dryer, a steam-heated cylinder, 3.7—6.1 m dia, dries the sheet from one side only. It is used extensively for tissues, particularly where creping is accompHshed as the sheet leaves the dryer, and to produce machine-gla2ed papers where intimate contact with the poHshed dryer surface produces a high gloss finish on the contact side. 

Yamanashi MAGLEV Test Line, 23 865 Yankee dryer, 18 122, 129 Yard wastes... 

A cylinder dryer may consist of one large cylindrical drum, such as the so-called Yankee dryer, but more often it comprises a number of... 

The size of commercial cylinder dryers covers a wide range. The individual rolls may vary in diameter from 0.6 to 1.8 m (2 to 6 ft) and up to 8.5 m (28 ft) in width. In some cases, the width of rolls decreases throughout the dryer in order to conform to the shrinkage of the sheet. A single-cylinder dryer, such as the Yankee dryer, generally has a diameter Between 2.7 and 4.6 m (9 and 15 ft). 

Convective dryers may be used as well in papermaking. In the Yankee dryer (Fig. 12-85), high-velocity hot airstreams impinging on the... 

For evaluation of a resin as a creping adhesive, a 1% solids aqueous solution of the formulated resin is sprayed onto the siuface of a Yankee Dryer along with the appropriate amount of release agent to provide a good balance of adhesion and release. This application optimizes both the productivity of the paper machine and the quality of the product produced on the machine. The solid consists of about 50% polyvinyl alcohol (PVOH) and 10-50% (polyamide-epihalohydrin resin). A cellulosic fibrous web is pressed against the drying surface to adhere the web to the surface. The dry web is then dislodged from the... 

Slot nozzles are convenient and easy to fabricate for smaller width dryers (1-2 m). For larger widths and for dryers employing elevated temperature jets, it is difficult to maintain a uniform jet width without developing excessive thermal stresses. The fabrication costs are high and are not justifiable. Most large-scale units (e.g., Yankee dryer for tissue) therefore use perforated plates to generate arrays of jets. They are easier and cheaper to fabricate. 

The types of dryers used in the paper industry can be classified by the basic means of transferring heat to the paper. For conventional steam-heated cylinders, the predominant mechanism of heat transfer is conduction convection is for air dryers, such as impingement and through-dryers radiation is used for infrared dryers and dielectric heating is used for microwave and radio frequency (RF) dryers. On the other hand, some of the dryers use more than one means of heat transfer, for example, Yankee dryers are a combination of cylinder and impingement dryers. 

FIGURE 39.14 (a) Tissue machine with a creping dryer (h) Yankee dryer in machine for MG papers. (Courtesy of JM. Voith GmbH,... 

Uses Yankee dryer coating for softer and thicker coatings, and controlled and high adhesion in high-speed Yankee dryers Unispar 40 [Unimin Spec. Mins.]... 

When using oxidants on the process side other factors comes into play. For example, oxidants can react with dyes causing an increase in dye usage. Therefore, oxidants more friendly to dye usage (e.g., PAA) may be preferred over halogenated oxidants. In some cases, oxidant effects may be so detrimental that they may not be allowed (e.g., on coating/release aids and Yankee dryer in tissue manufacturing). 

Cylinder dryer Impingement dryer Yankee dryer Infrared dryer Through-dryer... 

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