On-line control of papermaking process chemistry

A new on-line instrument (Zeta Data) was developed, which automatically measures the zeta potential and drainage of fiber slurries. It out-puts data to a Distributed Control System which controls chemical feed rates. The streaming potential measurement is made by passing liquid through a pad of fibers while simultaneously measuring the potential across the pad. It is used to calculate the zeta potential of papermaking furnishes. The volume of liquid which passes through the pad during a standard measurement cycle is measured and expressed as ''drainage in milliliters''. The new instrument optimizes microparticulate process (feed of cationic polymer and an inorganic colloid) by allowing zeta potential control at the value which maximizes drainage, thereby also maximizing retention,formation and runnability at minimum cost in chemicals. The on-line instrument is available in a laboratory version and an on-line version. Results on modern papermachines have shown, that thorough and efficient mixing is necessary effective of the components of the microparticulation process and the furnish.