Method And System For Treating A Fibrous Suspension

Abstract

Methods for treating a fibrous suspension are disclosed, including cleaning the fibrous suspension in a screening room with a plurality of cleaning stages and including a final cleaning stage, and in which the cleaning takes place at a low fiber concentration, and recycling at least a partial flow of the accept from the last cleaning stage to a position before or in the screening room after it passes through a thickener, where the concentration of the accept is increased to a concentration which minimizes dilution of the concentration of the fiber suspension, to which the accept is supplied.

1 - 5 . (canceled) 
     
     
         6 . A method of treating a fibrous suspension comprising cleaning said fibrous suspension in a screening room including a plurality of cleaning stages including a final cleaning stage, carrying out said cleaning of said fibrous suspension in said final cleaning stage at a low fiber concentration so as to produce an accept portion and a reject portion of said fibrous suspension, passing at least a portion of said accept portion of said fibrous suspension from said final cleaning stage to a thickener to produce a thickened flow of said fibrous suspension, and recycling said thickened flow of said fibrous suspension to at least one cleaning stage prior to said final cleaning stage, whereby the dilution of said fibrous suspension in said screening room is minimized. 
     
     
         7 . The method of  claim 6  wherein said plurality of cleaning stages includes a plurality of cleaning stages prior to said final cleaning stage. 
     
     
         8 . The method of  claim 6  wherein said thickened flow of said fibrous suspension is recycled to a mixing tank prior to said screening room. 
     
     
         9 . The method of  claim 6  including passing at least another portion of said accept portion from said final cleaning stage in a bypass line past said thickener. 
     
     
         10 . The method of  claim 6  wherein said final cleaning stage comprises apparatus selected from the group consisting of a final stage screen, a knot washer, a vortex cleaner, and a cyclone. 
     
     
         11 . The method of  claim 6  wherein said low fiber concentration comprises a fiber concentration of about 1% or less.