MILL EXPERIENCES FROM A 72″LC REFINER AT HOLMEN PAPER BRAVIKEN MILL

摘要

Trials were made in mill scale in a modern TMP line equipped with an Impressafiner for chip pretreatment, parallel double disc first stage refiners and a prototype 72 inch TwinFlo LC refiner in the second stage. The LC refiner increased tensile index by 8 Nm/g at a gross specific refining energy of 135 kWh/adt.Fibre length was reduced by 10 % at 140 kWh/adt and specific edge load 1.00 J/m. Specific light scattering coefficient did not develop significantly over the LC refiner.The importance of equal gap in LC refiners with dual refining zones has also been demonstrated. In order to produce homogenous pulp regarding shives content and fibre length, gap seemed to be an efficient control parameter. The effects of sulphite chip pre-treatment on second stage LC refining have also been evaluated. No apparent differences in fibre length shortening and light scattering development through LC refining was noticed between treated and untreated pulps. Sulphite chip pre-treatment in combination with LC refining in second stage, yielded a pulp before screening and second stage, yielded a pulp before screening and reject refining with tensile index and shives content that were similar to untreated final pulp after screening and reject refining.