OCC Pulp Quality Improvement at Simpson-Tacoma Kraft Company

摘要

Simpson Tacoma Kraft Company, an integrated producer of bleached and unbleached linerboard, has foundrnsignificant paper machine benefits from an operational change in its Old Corrugated Containers (OCC)rnrepulping system. By increasing rotor speeds in the OCC system fine screens, and using high open arearnscreen cylinders, the strength properties of the OCC increased dramatically. On average, the CanadianrnStandard Freeness (CSF) of the screened OCC going to the paper machines increased by 50 ml. Having arnhigher freeness enabled the paper machine to run faster due to better drainage while also improving thernstrength characteristics of the sheet. The higher strength OCC has permitted a reduction in thernconcentration of virgin softwood kraft pulp required in the linerboard, enabling the use of the virgin kraftrnpulp elsewhere in the mill.rnAn additional feature of the higher screen rotor speed is increased screen capacity, and lower fiber loss.rnThe throughput of the OCC system has increased by over 20% since the speed up of the screen rotors, andrnthe amount of fiber rejected by the tertiary stage screen has decreased by over 50%.