Importance

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Abstract

A refiner disc and segment for a rotary disc fiber refiner which has a plurality of radial fields each having an angular extent no greater than 30.degree. and preferably no greater than 22.degree. for reducing the amplitude and duration of load swings that take place during pumping and holdback cycles. Each field has a refining zone with a refiner groove and a refiner bar and a second zone disposed radially outwardly of the refining zone that changes the direction of flow of stock to reduce stock flow momentum and magnitude of the load swings. Each field can have a third zone radially outward of the second zone that further changes the direction of flow of stock and an infeed zone radially inwardly of the refining zone. If desired, a zone that includes a breaker bar can be disposed radially inwardly of the infeed zone. Where the disc is segmented, the segment has at least three fields. In one preferred embodiment, the segment has at least four fields which reduces the duration and magnitude of load swings by at least 40% thereby reducing refiner vibration and wear while advantageously increasing consistency of pulp quality and throughput. The disc and segment are capable of bi-directional operation without loss of efficiency, quality, and throughput.

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First Claim