REFINING PULP STOCK: CONTROLLING EFFECT OF CENTRIFUGAL FORCE ON STOCK

摘要

Method and apparatus for refining pulp stock in which the pulp material is ground in a grinding space (34, 42) defined between a pair of rotatable grinding discs (18, 20) having ridges and grooves providing opposing grinding surfaces (26, 28, 30, 32), which discs (18, 20) rotate relative to one another in an environment of a fluid medium under superatmospheric pressure and correspondingly elevated temperature in a housing (10). The grinding space includes a first grinding zone (34) extending from a central portion of the discs and a second grinding zone (42) extending angularly from the first grinding zone (34). The first grinding zone (34) is defined between the relatively rotatable discs (18, 20), while the second grinding zone (42) is defined between one of the rotatable discs (18) and a stationary grinding surface (44) on at least a portion of the surface of a stationary element (46) mounted within said housing (10) and spaced apart from the other (20) of said rotatable discs to provide a gap for preventing contact between the periphery of said disc (20) and said stationary element (46).