At the end of this module, you will be able to:
- Describe the purpose of blow line refining
- Describe blow line refining process theory
- Identify and describe the components of a blow line refiner
- Describe blow line refiner operation
- Explain the effects of refining on pulp properties
- Describe the safety hazards associated with blow line refining
The following key questions are answered in this module:
What is meant by ""refining"" of pulp?
The primary effect on pulp of blowline refiners is to break apart cooked chips and separate them into fibers.
What is one advantage provided by a blowline refiner?
Blowline refining reduces the load on knotting and screening systems by reducing the level of rejects.
What is the physical form of a refiner?
A typical blowline refiner consists of two large metal disks with ridged inner surfaces. One disk is rotated by a motor and one is stationary.
What in the primary operating parameter which controls of the amount of energy applied to pulp going through a refiner?
The amount of energy imparted to the pulp is related to the space between the disks, so gap control is important.
What is the effect of applying excessive energy to the pulp?
Excessive shear forces applied to the pulp will result in crushing and/or cutting of the actual fibers.
Below is a transcript of the video sample provided for this module:
Refining action is caused by passing blown digester material, the cooked wood chips, and black liquor between two large metal disks with ridged surfaces. Typically, one of the discs rotates and one is stationary causing a shearing action on the blown material as it passes through the gap between the disks. The amount of energy that goes into the pulp is controlled by the size of the gap the material passes through. Decreasing the gap increases the energy applied, and the amount of work done on the material. By applying different amounts of energy to the material, the effects on the pulp can be controlled. The gap is controlled by positioning devices that move the rotor towards or away from the stater or by a motorized screw drive.
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