The effects of retention aids, drainage conditions, and pretreatment of slurry on high-vacuum dewatering: a laboratory study

After the initial drainage by gravity and foils on the paper machine wire section, water is removed by suction. A certain pressure difference across the web is reached, depending on the volume of airflow and the resistance of the wet-web wire system. Most of the resistance comes from the web. The ob...

Full description

Saved in:
Bibliographic Details
Published in:Tappi journal 1995-04, Vol.78 (4), p.140-147
Main Authors: Raisanen, K.O. (University of Technology, Espoo, Finland.), Paulapuro, H, Karrila, S.J
Format: Article
Language:English
Subjects:
ADDITIF
ADDITIVES
ADITIVOS
AGUA
Air permeability
Dispersions
Drainage
EAU
EQUIPO
INDUSTRIA DE LA PASTA Y EL PAPEL
INDUSTRIE DE PATE ET PAPIER
MATERIEL
PAPEL
PAPER MACHINES
Papermaking machinery
PAPIER
PULP AND PAPER INDUSTRY
SEPARACION
SEPARATING
SEPARATION
Shear stress
Slurries
Testing
Vacuum applications
WATER
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:After the initial drainage by gravity and foils on the paper machine wire section, water is removed by suction. A certain pressure difference across the web is reached, depending on the volume of airflow and the resistance of the wet-web wire system. Most of the resistance comes from the web. The objective of this study was to determine the importance of chemical addition and shearing conditions prior to drainage for the air permeability of the sheet. In addition, more knowledge was sought on the dynamics of vacuum-assisted water removal. The study was done with a specially designed laboratory-scale drainage tester called the moving belt drainage tester. Different chemical additions, shear forces, and shear times prior to forming were used in order to change the structure of the formed sheet. The filler content was also varied. After the initial drainage, very short, strong suction pulses were applied, and the solids content of and airflow through the sheet were measured. The effect of different suction pulse rates on water removal was examined.
ISSN:0734-1415