Improving on-machine efficiency and sheet quality through controllable drainage on a highspeed machine

摘要

In today's competitive scenario, papermakers are facing challenges to improve the cost performance of their paper machines. They are exposed to a number of changes in market dynamics that force them to respond quickly in order to remain competitive. Ever rising cost of raw material, energy, water, steam and competitive pricing in emerging markets (e.g. Brazil, Russia, India and China) have put additional pressure on their margins thereby making this challenge more difficult. So the possible implications of these additional challenges have made this imperative for these papermakers to look for ways to improve their "On-Machine-Efficiency" also known as OME through various Mechanical, Operations & Chemical (MOC) means. Retention and drainage programs, which have used an inorganic microparticle component, such as colloidal silica and bentonite, have been widely practiced by papermakers across the globe to improve the drainage which helps them to speed up the machine thereby improves the on machine efficiency. The need for increased drainage at higher retention levels in paper grades has led to the development of microparticle-based retention programs. However, one has to have trade-offs between retention and drainage to optimize the performance of any Retention & Drainage program. For optimal performance, one should always strive for improving the drainage but in a controllable manner, as the amount of water drained is crucial to achieve enhanced sheet quality at highest possible speed. In high-speed machines such as gap formers, this controllable drainage becomes more challenging due to high shear forces and often requires a trade off with retention. Furthermore, controllable drainage is also essential for the quality of the sheet, as too much drainage especially on high-speed machines may negatively impact formation and also other sheet properties largely decided by formation and z-direction distribution of fibbers, fines & fillers. It is this balance of drainage and retention that has challenged several companies over the years to modify their microparticle retention programs to come up with right product combination to manage drainage on highspeed machines and sheet quality. This article will focus on the implementation of Nalco's ELLIPSIS? Cationic Micropolymer Technology as part of a comprehensive retention and drainage program as a viable solution for papermakers operating modern, high speed machines (e.g. gap and hybrid formers) to have at their disposal to get more drainage in a controllable way to improve their on machine efficiency and sheet quality.