A refiner plate segment including a plurality of bars and grooves for refining lignocellulosic materials, where the grooves between adjacent bars includes a plurality of teeth having a wave-like profile with alternating high and low points. The wave-like profile of the teeth within the grooves increases turbulence in the refining process to tumble the fibers and push them toward the refining gap to reduce energy and improve the efficiency of the fiber reduction process.

The present invention discloses a method for designing a refiner plate with equidistant curved bars, comprising following steps of: designing a central bar are of center curved bar and defining the bar angle for the equidistant curved bar; designing circle arcs for curved bars on two sides of center curved bar of equidistant curved bar segment; when the whole refining segment is full of circle arcs, trimming lines of outer circle arcs of the refining segment to complete the design of equidistant circle arcs on the two sides; and if required, dividing the bars into zones. In the present invention, by the definition of the bar angle for the curved bars and the parametric design of the equidistant curved bars by using circle are equations, it is ensured that the flexibility in designing an equidistant curved bar refiner plate is improved.

The present invention discloses a method for designing a refiner plate with equidistant curved bars, comprising following steps of: designing a central bar are of center curved bar and defining the bar angle for the equidistant curved bar; designing circle arcs for curved bars on two sides of center curved bar of equidistant curved bar segment; when the whole refining segment is full of circle arcs, trimming lines of outer circle arcs of the refining segment to complete the design of equidistant circle arcs on the two sides; and if required, dividing the bars into zones. In the present invention, by the definition of the bar angle for the curved bars and the parametric design of the equidistant curved bars by using circle are equations, it is ensured that the flexibility in designing an equidistant curved bar refiner plate is improved.

The present disclosure provides a refiner segment (1) for refining of lignocellulosic material. The refiner segment (1) have a surface comprising a plurality of bars (10.sub.j) extending along a direction between an inner periphery (17b) of the refining segment and an outer periphery (17b) of the refining segment (17b), and a plurality of dams (11.sub.i). Each of the dams extend between a corresponding pair of adjacent bars (10.sub.k, 10.sub.k+1). The refiner segment (10) comprises at least one dam (11.sub.p) that comprises a curved side (11c) facing the inner periphery (17b) of the refiner segment (1). The curved side (11c) have a concave curvature with regard to the inner periphery (17b) to thereby form a rounded section in an area (20) defined by the dam (11.sub.p) and the corresponding pair of adjacent bars (10.sub.k, 10.sub.k+1). The at least one dam (11.sub.p) is moreover a three dimensionally extending body. The rounded section created by the concave curvature gives a more robust refining segment. The present disclosure also provides a refiner disc that comprises such a refiner segment. The present disclosure additionally provides a refiner having at least one such refiner disc.

The present disclosure provides a refiner segment (1) for refining of lignocellulosic material. The refiner segment (1) have a surface comprising a plurality of bars (10.sub.j) extending along a direction between an inner periphery (17b) of the refining segment and an outer periphery (17b) of the refining segment (17b), and a plurality of dams (11.sub.i). Each of the dams extend between a corresponding pair of adjacent bars (10.sub.k, 10.sub.k+1). The refiner segment (10) comprises at least one dam (11.sub.p) that comprises a curved side (11c) facing the inner periphery (17b) of the refiner segment (1). The curved side (11c) have a concave curvature with regard to the inner periphery (17b) to thereby form a rounded section in an area (20) defined by the dam (11.sub.p) and the corresponding pair of adjacent bars (10.sub.k, 10.sub.k+1). The at least one dam (11.sub.p) is moreover a three dimensionally extending body. The rounded section created by the concave curvature gives a more robust refining segment. The present disclosure also provides a refiner disc that comprises such a refiner segment. The present disclosure additionally provides a refiner having at least one such refiner disc.

The invention relates to a center ring arrangeable on a refining disc of a defibrator for refining of fibrous material, wherein said center ring comprises a circumferential outer surface, a circumferential inner surface and a centrally located through-hole adapted to receive fibrous material fed from a feeding device, wherein said outer surface is provided with a circumferentially running groove opening up on the outer surface and being adapted to collect steam produced during operation of said defibrator, and wherein the center ring further comprises a plurality of wings provided on said inner surface and a number of channels extending from said groove to the positions on said inner surface where said wings are provided.

The present invention relates to a blade for a disc refiner intended for refining lignocellulosic material, the blade (10) comprising a surface (1) delimited by an inner circumference (11) and an outer circumference (12), a refiner zone (2) on the surface (1) for refining lignocellulosic material, a blank zone (3) on the surface (1), wherein the refiner zone (2) is arranged closer to the inner circumference (11) than the blank zone (3), the blade (10) further comprising a separation groove (4) that is arranged between the refiner zone (2) and the blank zone (3), and at least one connecting groove (5) that connects the separation groove (4) to the outer circumference (12) of the blade (10) across the blank zone (3).

The invention also relates to a blade pair and to a refiner comprising at least one blade.

The present invention relates to a blade for a disc refiner intended for refining lignocellulosic material, the blade (10) comprising a surface (1) delimited by an inner circumference (11) and an outer circumference (12), a refiner zone (2) on the surface (1) for refining lignocellulosic material, a blank zone (3) on the surface (1), wherein the refiner zone (2) is arranged closer to the inner circumference (11) than the blank zone (3), the blade (10) further comprising a separation groove (4) that is arranged between the refiner zone (2) and the blank zone (3), and at least one connecting groove (5) that connects the separation groove (4) to the outer circumference (12) of the blade (10) across the blank zone (3).

The invention also relates to a blade pair and to a refiner comprising at least one blade.

The present invention relates to a blade for a disc refiner intended for refining lignocellulosic material, the blade (10) comprising a surface (1) delimited by an inner circumference (11) and an outer circumference (12), a refiner zone (2) on the surface (1) for refining lignocellulosic material, a blank zone (3) on the surface (1), wherein the refiner zone (2) is arranged closer to the inner circumference (11) than the blank zone (3), the blade (10) further comprising a separation groove (4) that is arranged between the refiner zone (2) and the blank zone (3), and at least one connecting groove (5) that connects the separation groove (4) to the outer circumference (12) of the blade (10) across the blank zone (3).

The invention also relates to a blade pair and to a refiner comprising at least one blade.

A method and an arrangement (1) for producing nanofibrillar cellulose, wherein lignocellulose-containing fibre material is refined to separate nanofibrils. The method comprises refining the lignocellulose-containing fibre material in at least one refining zone (20) in one or more refiners (5) to separate nanofibrils, supplying the fibre material to be refined into the at least one refining zone of at least one refiner through at least one opening (12, 19) in the refining surface (11, 18) of at least one refining element (7, 13) and/or discharging the fibre material already refined in the at least one refining zone of at least one refiner out of the at least one refining zone through at least one opening (12, 19) in the refining surface (11, 18) of at least one refining element (7, 13), and operating the said at least one refiner to produce a specific edge load (SEL) of less than three J/m in the refining.