Abstract: The invention relates to a double disc pulp refiner (10) comprising a first refining disc (11) and a second refining disc (12), the first refining disc being arranged at a feed end of the refiner (10) where lignocellulosic material (M) is fed into the refiner (10) through inlet openings (16) in the first refining disc (11) and the second refining disc (12) being arranged coaxially, spaced apart from and opposed to the first refining disc (11), said first refining disc (11) being provided with at least one refining segment (13) for refining the lignocellulosic material (M) and a center plate (20)having a cross-sectional profile adapted such that when the center plate (20) is arranged on the first refining disc (11) in the refiner (10), the center plate (20) protrudes to a maximum height which is the same as, or higher than, a maximum height of the at least one refining segment (13) provided on the first refining disc (11), said double disc pulp refiner (10), wherein said maximum height is such that the distanc