Patent ID: 8646708

Claim:
A refiner for refining fibrous material, the refiner comprising: at least one first refiner element having a first refiner surface, portions of the first refiner element defining first openings extending through the first refiner surface; at least one second refiner element having a second refiner surface, portions of the second refiner element defining second openings extending through the second refiner surface, the second refiner element being arranged around the first refiner element in such a manner that the first refiner element and the second refiner element have a common middle axis; wherein there is a refining space defined between the first refiner element and the second refiner element and wherein the first refiner element or the second refiner element is arranged to rotate around said middle axis; wherein the first openings in the first refiner surface and the second openings in the second refiner surface are arranged to allow fibrous material to be refined to be fed into the refining space or to exit the refining space; and a structure selected from the group consisting of: a support structure, a wall structure, a flow guide, a channel, and a channel system, arranged with respect to the first openings or the second openings, and dividing the refiner into at least two feed regions arranged one after another along a direction defined by the middle axis through which fibrous material to be refined is feedable into the refining space at different positions along the middle axis.