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vertdig140-gallon (150-liter) Vertical, Screw-fed, Continuous Digester with Refiner Discharge

Capacity: up to 3 tons/day on wood; less on bulky non-woods

Construction: 316 SS


  • atmospheric pre-steaming
  • 3:1 volumetric reducing screw and plug former permit continuous feeding into the pressurized digester
  • flooded-zone impregnation box at discharge of plug former permits intense chemical impregnation; lifting screws drain material briefly before falling into vessel
  • up to 30 minutes of retention time
  • 250 psig pressure max.
  • nuclear gauge for accurate level control
  • bottom agitator ensures that material moves into discharge screw
  • 12-inch refiner in discharge line; digester cannot be run without refiner

This unit can be used for continuous production of chemical or semi-chemical pulp, as long as the process permits short retention times and some degree of refining at the discharge. On non-woods, the unit can be made to run like a screw-type digester. The unit has been run successfully on corn stalk, wheat straw, hemp, and kenaf.