R. Vyse et al., Advances in wet end steam shower design and performance - Smaller zone sizes has resulted in improved CD moisture profile control, PULP PAPER, 101(4), 2000, pp. 38-43
Increasing wet end sheet temperature using steam showers or other sources o
f heat, has long proven effective in improving water removal in the forming
and pressing sections. Increasing sheet temperature assists in mechanical
water removal by lowering water viscosity and reducing water surface tensio
n. Steam showers have been successfully used at the wet end for many years
for profile control, to increase machine speed and to enhance paper propert
ies. In recent years, a number of improvements in their design have resulte
d in increased performance and improved maintainability of the equipment. T
his paper considers the trends to smaller zone sizes for improved cross-dir
ection (CD) moisture profile control. In addition, the use of in-situ therm
owells for optimizing steam temperature and resulting steambox performance
is discussed. The use of removable screen plates for enhanced maintainabili
ty is reviewed as is the use of wet end scanners for control. The benefits
of using multiple steam boxes are also reviewed.