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° and preferably no greater than 22° 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.

Abstract: The refiner plate of this invention has a pattern of interlocking or nested elements having a "I"s "T"s, "S"s, "L"s, "F"s, "E"s, or "H"s shape which form channels. The body of the elements forms the refiner bars which hold the fibers as they move between the refiner plates in a disk refiner. The pattern of elements retarded the flow of fibers while at the same time providing a large open area for steam to pass through the refiner disks. The segments making up the elements producing a refiner bar which is reinforced for higher strength. The shape of the elements has a increased edge length exposed to the flow of fibers.