Proven FT-NIR application for digester optimization



Digester Challenges
Alkali measurements are used to determine chemical consumption during the various Kraft cooking phases in the digester. These measurements are widely accepted as standard monitoring information, as they provide a solid basis for cooking management and digester optimization.  Traditional measurement methods, such as conductivity and autotitration, tend to foul and drift while only inferring actual values.

FITNIR Solution
FITNIR’s FT-NIR technology offers the most comprehensive and accurate measurements of true pulp liquor properties measurements necessary for an optimal digester environment, devoid of fouling or drifting issues. Our analyzers reliably and accurately provide white liquor EA (Effective Alkali) and sulphidity, as well as black liquor REA (Residual Effective Alkali) at the various cooking zones. Control strategies using reliable data from our analyzers can significantly reduce kappa variation, overcooking and rejects while increasing pulp quality.

Properties Measured

FITNIR’s Digester analyzer application measures black liquor compositions:

  • REA
  • Organic Solids*
  • Inorganic Solids*

  • Total Solids*
  • Lignin
  • Density

*FITNIR Online measurement only


^ Click on Diagram to Enlarge

Key Benefits

  • $1 – 2M savings/year
  • 3 – 6 months average ROI
  • Improved digester control
  • Reduced kappa variability
  • Decreased bleaching cost



  • Reduced off-grade pulp
  • Reduced overcooking and rejects for improved pulp quality
  • More efficient white liquor consumption
  • Fewer lab tests required
  • Improved yield


Project Highlights

Weyerhaeuser, Grande Prairie Mill

Grande Prairie, AB, Canada

FITNIR Benchtop

CANFOR Pulp, Northwood Pulp Mill

Prince George, BC, Canada


Mill in Eastern Canada

Eastern Canada


Catalyst Paper

Crofton, BC, Canada


Get in Touch

Contact FITNIR Analyzers Inc. and we can work together to optimize your digester operations.


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