Patent ID: 7846294
Filing Date: 2010-12-07
Classification: B02C,D21B,D21D

Abstract:
1. A method for thermomechanical refining of wood chips comprising: exposing the chips to an environment of steam to soften the chips; destructuring and partially defibrating the softened chips in a compression device; feeding the destructured and partially defibrated chips to a rotating disc primary refiner, wherein opposed discs each have an inner ring pattern of bars and grooves and an outer ring pattern of bars and grooves; and substantially completing fiberization of the chips in the inner ring and fibrillating the resulting fibers in the outer ring, wherein each ring has an inner feeding region and an outer working region; the working region of the inner ring is defined by a first pattern of alternating bars and grooves, and the feeding region of the outer ring is defined by a second pattern of alternating bars and grooves; said first pattern on the working region on the inner ring has relatively narrower grooves than the grooves of said second pattern on the feeding region on the outer ring; said fiberization of the chips is substantially completed in the working region of the inner ring with low intensity refining; and said fibrillation of the fibers is performed in the working region of the outer ring with high intensity refining.