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Refining of Chemical Pulp

Main purpose of refining Chemical Pulp is to obtain higher yield by allowing a higher Kappa level which means more lignin and hemicellulose. This is achieved with shorter retention time in the digester. Less cooking leads to undissolved bundles of fibres, knots and shives. These must be defibrated by means of mechanical refining either Blowline or Hot Stock as first stage application.

  • The Blowline refiner, as the name of the application implies, is connected directly after the digester before the Blowtank. The stock is refined in medium consistencey the same as in the digester.
  • The Hotstock refiner is placed after the Blowtank. The stock is refined in low consistencey 3-5%. Refiner type can either be of conical or planar disc type.

Typically, as second stage application there are either a Deshive- or Reject refiner with the main purpose to reduce shives.

  • The Deshive refiner is used after a diffuser washing stage before the screening room. The stock is refined in Medium conc in an atmospheric refiner.
  • The Reject refiner is placed after the screening room and are represented by either Conical Disc refiner or DoubleDisc refiner

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