Vertical pressure type pulp screen

Claim 1

A PULP SCREENING MACHINE OF THE VERTICAL PRESSURE OPERATED TYPE, THE SAID MACHINE INCLUDING A VERTICALLY DISPOSED CASING HAVING TOP AND BOTTOM CLOSURE PLATES, A PULP FEED INLET TO THE CASING ADJACENT ITS TOP END AND A PULP DISCHARGE OUTLET TO THE CASING ADJACENT ITS LOWER END, AN ANNULAR PERFORATED SCREEN PLATE WITHIN SAID CASING SUPPORTED ON THE SAID BOTTOM CLOSURE PLATE, MEANS TO SUPPORT THE TOP END OF THE SAID SCREEN PLATE AT A POINT ADJACENT THE LOWERMOST EDGE OF THE SAID PULP FEED INLET AND DEFINING A PULP FEED CHAMBER ABOVE SAID SCREEN PLATE, A ROTARY IMPELLER AXIALLY MOUNTED WITHIN SAID SCREEN PLATE, THE SAID IMPELLER COMPRISING A CORE MEMBER WHOSE LOWER END IS LOCATED IN THE HORIZONTAL PLANE OF THE LOWER END OF SAID SCREEN PLATE, THE SAID CORE MEMBER EFFECTING A PROGRESSIVE REDUCTION IN AREA OF THE SCREENING CHAMBER IN A DOWNWARD DIRECTION AND A SERIES OF VERTICALLY DISPOSED BLADES SECURED TO THE SURFACE OF SAID CORE MEMBER AND RADIATING OUTWARDS THEREFROM TOWARDS SAID SCREEN PLATE, THE LOWER ENDS OF SAID CORE MEMBER AND SAID SCREEN PLATE DEFINING A FIRST ANNULAR REJECT DISCHARGE OUTLET, A STATIONARY