CLEARFLOW™ Feedwell and Bustle pipes systems for green and liquor clarifiers have been developed by McFarlen Eng using 3D fluid dynamic modeling technology to improve the removal of kinetic energy in the feedstrem to the clarifier, which allows dregs and lime mud particle to settle efficiently into the clarifier resulting in Improved clarity of green and white liquor. This leads to improve filter ability of the lime mud and reduce scaling in the digester, reducing chemical bleaching cost.

McFarlen Engineering initiated CLEARFLOW™ Feedwell design project because older industrial clarifiers’ designs were inadequate in reducing kinetic energy,reduction of turbidity in the liquor from green, white and mud washing industrial clarifiers improves the operation of the Recaust Plant.

Many pulp mills have increased the loading on their clarifiers in order to meet greater demands for liquor in the digesters. In addition, hydrodynamic modeling shows that older technology for feedwell and bustle pipe design is inadequate to sustain flows above critical levels where product clarity decreases dramatically. As a result, low turbidity may not be achieved even when injecting polymer. Furthermore, during the past three decades, design criteria have changed to satisfy the requirements for cleaner liquors and reduced dead load and energy consumption in the Recausticizing system.

Consequently, the feedwell and bustle pipe ClearFlow™ systems in many older clarifiers are not optimally designed and therefore do not perform as desired. Convection currents are introduced unnecessarily, and overflow velocities are much higher and more localized than desired, causing high turbidity levels.

An improvement, especially in green liquor turbidity, can lead to substantial savings. McFarlen Engineering Ltd. is confident that these savings can be achieved through the application of ClearFlow™ technology, which optimizes feedwell and bustle pipe hydrodynamic design to maximize dregs retention, minimize flow velocities, and eliminate short circuiting of all flow streamlines. The areas for potential cost savings are illustrated below.

For custom ClearFlow™ systems for your US or Canada business, contact McFarlen Engineering now. We strive to make the implementation process as simple as possible.

Typical Improvements by Retrofitting with ClearFlow™ Technology

Typical Improvements by Retrofitting with ClearFlow™ Technology


Industrial Clarifiers