Blade element for refiner

A blade element for a refiner for refining fibrous material, the blade element comprising:

• a blade element body having a refining surface;
• a plurality of blade bars and blade grooves therebetween, the blade bars and the blade grooves forming the refining surface of the blade element body;
• wherein adjacent blade grooves are two of said blade grooves which have only a single one of said blade bars therebetween;
• wherein adjacent blade bars are two of said blade bars which have only a single one of said blade grooves therebetween;
• wherein the blade grooves extend in a longitudinal direction along the refining surface, and wherein the blade grooves have bottoms which extend along the blade grooves in the longitudinal direction;
• wherein each blade groove bottom has a variable depth profile as it extends along its associated groove in the longitudinal direction, said profile having alternating high points and low points;
• wherein there is a phase shift between the high points and the low points of the variable depth profile of the groove bottoms of adjacent blade grooves;
• wherein a blade bar angle of each blade bar is arranged to vary continuously in the longitudinal direction of each blade bar so that the blade bar extends in a wave shaped manner in a plane of the refining surface and that there is a phase shift between two adjacent blade bars.