Comparison of plate and conical fillings in refining of bleached softwood and hardwood pulps

Kari Koskenhely, Kaarlo Nieminen, Eero Hiltunen, Hannu Paulapuro

    Research output: Contribution to journalArticleScientificpeer-review

    7 Citations (Scopus)

    Abstract

    The purpose of this study was to compare
    plate and conical refiner fillings in laboratory
    refining of softwood and hardwood pulp
    fibers. A better dewatering-tensile strength
    combination was achieved when SWK was
    refined with conical fillings, and the development
    of strength was found to be insensitive
    to variations in refining intensity in
    the range of 1.3-4.0 J/m. A bar microprofile
    was measured with the aid of a profilometer.
    The leading edges of conical filling bars were
    found to be rounder. A possible reason for
    the better tensile strength of pulp refined
    with conical fillings is that the round edge
    helps large SW fiber flocs to enter the space
    between the bars, resulting in less heterogeneous
    or more efficient treatment of fibers.
    The recorded gap closure values supported
    the above interpretation. The gap between
    conical fillings was found to become wider
    when pulp consistency and thus the tendency
    for fiber flocculation increased, whereas
    increased pulp consistency decreased the
    gap between plate fillings, which was further
    reflected as increased fiber cutting. The reduction
    in fiber length appears proportional
    to the increase in gap closure, supporting
    the earlier theory that fibers are squeezed
    and crushed between the bars. More attention
    should be paid to the wear of filling
    materials when refining long-fiber pulp. A
    filling material which wears so that the bar
    edges are rounded would seem to promote
    high tensile strength and high average fiber
    length.
    Original languageEnglish
    Pages (from-to)458-463
    Number of pages6
    JournalPAPERI JA PUU-PAPER AND TIMBER
    Volume87
    Issue number7
    Publication statusPublished - 2005
    MoE publication typeA1 Journal article-refereed

    Keywords

    • laboratory refining
    • intensity
    • softwood
    • hardwood
    • energy swelling
    • bar profile

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