Extended Impregnation Cooking of Norway Spruce : Effects on Pulping Uniformity and Pulp Strength Properties

• Extended impregnation kraft cooking is a demonstrated improvement of the kraft pulping process and offers a way to use softwood more efficiently. We demonstrate the possibility of producing Norway spruce (Picea abies) kraft pulp using a new cooking concept, producing a pulp that can be defibrated without inline refining at kappa numbers of approximately 90. The cooking concept uses the differences in reaction rate between the diffusion and consumption of hydroxide ions in the prolonged impregnation step. Lowering the impregnation temperature will favour the diffusion of cooking chemicals over neutralization reactions, thereby improving chemical distribution throughout the chips. Impregnation conditions in combination with cooking temperatures lower than those of conventional kraft pulping are demonstrated to produce pulp with a narrower kappa number distribution and comparable strength properties at a considerably higher yield.

Ämnesord

TEKNIK OCH TEKNOLOGIER  -- Materialteknik -- Pappers-, massa- och fiberteknik (hsv//swe)

ENGINEERING AND TECHNOLOGY  -- Materials Engineering -- Paper, Pulp and Fiber Technology (hsv//eng)

Nyckelord

Uniform delignification

kappa number distribution

high-kappa-number pulp

reject

yield

tensile index

tensile stiffness index

SCT

starch multilayers

Cellulose and paper engineering

Cellulosa- och pappersteknik

Publikations- och innehållstyp

vet (ämneskategori)

ovr (ämneskategori)