Water recovery, papermaking

Sheet Drying. At a water content of ca 1.2—1.9 parts of water per part of fiber, additional water removal by mechanical means is not feasible and evaporative drying must be employed. This is at best an efficient but cosdy process and often is the production botdeneck of papermaking. The dryer section most commonly consists of a series of steam-heated cylinders. Alternate sides of the wet paper are exposed to the hot surface as the sheet passes from cylinder to cylinder. In most cases, except for heavy board, the sheet is held closely against the surface of the dryers by fabrics of carefuUy controUed permeabiHty to steam and air. Heat is transferred from the hot cylinder to the wet sheet, and water evaporates. The water vapor is removed by way of elaborate air systems. Most dryer sections are covered with hoods for coUection and handling of the air, and heat recovery is practiced in cold climates. The final moisture content of the dry sheet usually is 4—10 wt %. 

The polymerization of acrylamide (AM) and the copolymerization of acrylamide-sodium acrylate in inverse microemulsions have been studied extensively by Candau [10,11,13-15], Barton [16, 17], and Capek [18-20]. One of the major uses for these inverse microlatexes is in enhanced oil recovery processes [21]. Water-soluble polymers for high molecular weights are also used as flocculants in water treatments, as thickeners in paints, and retention aids in papermaking. 

Inverse microemulsion polymerization is used for the production of water-soluble polymers of high molecular weight, with applications in enhanced oil recovery, as flocculants in water treatments, thickeners for coatings, and retention aids in papermaking. 

---