Abstract A slurry of mixed paper making fibers of a wide range of lengths is fractionated into two fractions wherein the fibers are predominantly of lengths greater or less, respectively, than a predetermined intermediate control length, by feeding the slurry under pressure into the inlet end of a cylindrical screen member having slotted perforations of predetermined size and spacing in accordance with the control fiber length for the slurry to be fractionated, i.e. the slots are substantially less wide than the control fiber length and they are spaced to provide lands therebetween which are also less wide than the control fiber length. The supply flow is caused to circulate circumferentially of the wall of the screen member so that small fibers and other particles will pass through the slots to form the short fiber fraction, but fibers longer than the control fiber length will either flow past the slots or will fold over or ''''hair-pin'''' on the lands between slots. Periodic pulsations through the slots dislodge hair-pinned fibers for return to the supply flow and ultimate discharge from the exit end of the screen member to form the long fiber fraction.
APPARATUS FOR CLASSIFYING A SLURRY OF PAPER MAKING FIBERS OF A RANGE OF LENGTHS INTO TWO FRACTIONS WHEREIN THE CLASSIFIED FIBERS ARE PREDOMINANTLY OF LENGTHS GREATER OR LESS THAN A PREDETERMINED INTERMEDIATE CONTROL LENGTH RESPECTIVELY, COMPRISING: A. A HOUSING, B. A CYLINDERICAL SCREEN MEMBER WITHIN SAID HOUSING CHAMBER SPARATING THE INTERIOR THEREOF INTO A SCREEN CHAMBER AND A DISCHARGE CHAMBER ON OPPOSITE SIDES OF SAID SCREEN MEMBER, C. INLET MEANS FOR SUPPLYING THE SLURRY TO THE ONE END OF SAID SCREEN CHAMBER, D. SAID SCREEN MEMBER HAVING MULTIPLE SLOTS THERETHROUGH EXTENDING GENERALLY AXIALLY THEREOF AND OF SUBSTANTIALLY GREATER LENGTH THAN WIDTH, I. THE WIDTH OF EACH SAID SLOTS BEING SUBSTANTIALLY LESS THAN SAID CONTROL THE FIBER LENGTH, II. SAID SLOTS BEING SPACED CIRCUMFERENTIALLY OF SAID SCREEN MEMBER TO PROVIDE A LAND BETWEEN EACH PAIR OF ADJACENT SLOTS WHICH IS OF A WIDTH LESS THAN SAID CONTROL FIBER LENGTH, E. PRIMARY OUTLET MEANS FOR CONTINUOUSLY REMOVING FROM SAID DISCHARGE CHAMBER SLURRY CONTAINING FIBERS AND OTHERS PARTICLES WHICH HAVE PASSED THROUGH SAID SLOTS,
Claim 2
Dependent Claim
171 words
APPARATUS FOR CLASSIFYING A SLURRY OF PAPER MAKING FIBERS OF A RANGE OF LENGTHS INTO TWO FRACTIONS WHEREIN THE CLASSIFIED FIBERS ARE PREDOMINANTLY OF LENGTHS GREATER OR LESS THAN A PREDETERMINED INTERMEDIATE CONTROL LENGTH RESPECTIVELY, COMPRISING: A. A HOUSING, B. A CYLINDERICAL SCREEN MEMBER WITHIN SAID HOUSING CHAMBER SPARATING THE INTERIOR THEREOF INTO A SCREEN CHAMBER AND A DISCHARGE CHAMBER ON OPPOSITE SIDES OF SAID SCREEN MEMBER, C. INLET MEANS FOR SUPPLYING THE SLURRY TO THE ONE END OF SAID SCREEN CHAMBER, D. SAID SCREEN MEMBER HAVING MULTIPLE SLOTS THERETHROUGH EXTENDING GENERALLY AXIALLY THEREOF AND OF SUBSTANTIALLY GREATER LENGTH THAN WIDTH, I. THE WIDTH OF EACH SAID SLOTS BEING SUBSTANTIALLY LESS THAN SAID CONTROL THE FIBER LENGTH, II. SAID SLOTS BEING SPACED CIRCUMFERENTIALLY OF SAID SCREEN MEMBER TO PROVIDE A LAND BETWEEN EACH PAIR OF ADJACENT SLOTS WHICH IS OF A WIDTH LESS THAN SAID CONTROL FIBER LENGTH, E. PRIMARY OUTLET MEANS FOR CONTINUOUSLY REMOVING FROM SAID DISCHARGE CHAMBER SLURRY CONTAINING FIBERS AND OTHERS PARTICLES WHICH HAVE PASSED THROUGH SAID SLOTS,
Claim 3
Dependent Claim
37 words
Classifying apparatus as defined in claim 1 wherein the radial dimension of said slots is such that the sum of said dimension and the width of one of said lands is less than said control fiber length.
Claim 4
Dependent Claim
35 words
Apparatus as defined in claim 1 wherein said screen chamber is located on the radially inner side of said screen member and said discharge chamber is on the radially outer side of said screen member.