Patent ID: 6044980
Filing Date: 2000-04-04
Classification: B01D,B30B

Abstract:
An apparatus for extracting liquids from a slurry formed of liquids and fibers, the apparatus comprising:(a) a rotatable drum having a main longitudinal axis and an outer surface covered with a resilient layer;(b) a first draining roll having a first axis parallel to the main axis of the drum, said first draining roll being pressed against the drum in order to define therewith a first nip in which the slurry passes and is squeezed, said first draining roll comprising:a first hollow cylindrical shell having a substantially uniform distribution of first openings extending radially with respect to the first axis; anda first perforated filter screen externally fixed onto the first hollow cylindrical shell, said first filter screen having first perforations evenly distributed therein so that one part of said first perforations lies over the first openings of the first cylindrical shell while another part of said first perforations lies over part of the first cylindrical shell free of said first openings, said first perforations being smaller in size than said first openings;(c) a second draining roll having a second axis parallel to the main axis of the drum, said second draining roll extending below the first draining roll and being pressed against the drum in order to define therewith a second nip downstream the first nip in which the already squeezed slurry passes and is squeezed again, said second draining roll comprising:a second hollow cylindrical shell having a substantially uniform distribution of second openings extending radially with respect to the second axis, said second openings being smaller in size than the first openings of the first cylindrical shell; anda second perforated filter screen fixed externally onto the second hollow cylindrical shell, said second filter screen having second perforations evenly distributed therein so that one part of said second perforations lies over the second openings of the second cylindrical shell while another part of said second perforations lies over part of the second cylindrical shell free of said second openings,(d) first wiping means mounted under the first draining roll below the first nip and above the second draining roll for, on the one hand, wiping the squeezed slurry having passed through said first nip out of said first draining roll and directing said squeezed slurry towards the second nip and on the other hand, guiding the liquids collected from the slurry through the first draining roll towards a liquids outlet in order to avoid spillage of the second draining roll; and(e) second wiping means mounted over the second draining roll below the second nip for wiping the squeezed slurry having passed through said second nip out of the second draining roll and directing the so-separated slurry which consists mainly of said fibers, towards solids outlet.