Kraft pulp refining

Blowline refining defibrates chips after the continuous digester at high pressure. Modern chemical pulping systems for linerboard use continuous digesters and diffusion washers with no screening systems at all. The cooking process is completed at high kappa (>100) and yields over 60%. The objective of ANDRITZ blowline refining is to defibrate the fiber bundles after high-yield cooking prior to washing. The refiner is fed at medium consistency directly through a blowline from the continuous digester.  The high pressure blowline refiner is an HC refiner with a blowline discharge.

ANDRITZ blowline refining combined with deshive refining results in low installed cost, low operational costs, and high-strength, low-shive pulp.

Deshive refining can be achieved using atmospheric HC refiners with gravity discharge or LC refiners. It can be located after a blowline refiner or follow brown-stock washing in high-yield kraft pulping or semi-chemical pulping. ANDRITZ deshive refiners significantly reduce the shive content from a higher yield cooking process, providing 70%+ shive reduction, and improve pulp strength (Concora, Ring Crush, TEA). Deshive refining can be used in batch or continuous digester systems. Low-freeness reduction is a prerequisite to achieve optimum pulp washing with minimum chemical losses.

High Tensile Energy Absorption (TEA) and good stretch at high air permeability are key quality targets for sack paper producers. ANDRITZ HC sack kraft refining technology achieves these targets through:

ANDRITZ sack paper refining results in better pulp quality – higher TEA, stretch, and air permeability – at low freeness reduction. This allows increased production at the paper machine due to better pulp drainability and superior strength.