| 摘要 |
<p>A screen section, a cylindrical screen basket, a screening device, and a method for treating comminuted cellulosic fibrous material to provide improved fractionation or debris removal and improved efficiency of operation. The screen section, screen basket, screening device, and method for treating employ a screen configuration that, among other things, minimizes reject or fractionation thickening. One aspect of the invention provides a screen element (51) having a first surface (60) having a plurality of first apertures (62) for passing fibrous material and liquid when the first surface (60) is exposed to pressure pulses generally directed in a first direction (72); a second surface (61), opposite the first surface (60), having a plurality of second apertures (68) in fluid communication with the first apertures (62) for passing liquid when the second surface (61) is exposed to pressure pulses generally directed in a second direction (76), opposite the first direction; and means for minimizing the passage of fibrous material through the first apertures (62) in the second direction (76).</p> |
