Compression refining

General informations

The conventional refining generates intense shear forces, producing fine cellulosic elements, which reduce drastically the pulp drainability, and therefore the speed and production capacity of paper machines.
The compression refining can be carried out with two different technologies: mixing or compression refining. These two alternative treatments for pulp refining can also favor the compression forces and reduce the shear forces.
This new technical approach has shown that pulp mechanical properties can be developed on a large range with a low decrease in pulp drainage. This could allow reducing significantly the energy consumption of the paper machine for the vacuum generation to drain the sheet onto the paper machine wire or in the presses, and also the steam consumption in the drying section.

 
Technical Data and Achievements

Compression refiner (CREF)

• Refining consistency : 3 - 5 % depending on pulp grades
  
• Rotation speed betwenn 200 and 800 rpm
  
• Pressure : 0.5 to 6 bar
  
• Numbre of passes : variable
  
• Quantity to treat : 80 g of o.d. pulp, in batch

Mixer

• Variable pulp consistency
  
• Contact time : from 30 s to several minutes
  
• Screw profile to adjust with the pulp grade
  
• Rotation speed : between 50 and 350 rpm

Continuous feeding of the mixer.
Production rate of some 100 g per hour.

Controls

Characteristics of the pulp:

• MorFi analysis
• Drainage index, in °SR
• Water Retention Value WRV
• Fibre flexibility
• Mac Nett classification

Manufacture of handsheets to measure the mechanical properties with:

• Rapid Köthen handsheet former or,
  
• Retention sheet former or,
  
• Dynamic sheet former