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AFT APPROACH FLOW » The Science of Approach Flow

The Science of Approach Flow

To maintain high stock quality and undisturbed runability on a paper machine, a well-designed approach flow system is critical.  The system must accommodate the specific requirements for bringing the stock to the headbox at the right time – with the right composition, flow pressure, temperature, freeness, and other characteristics such as airlessness, cleanliness, etc.  No simple task.

Conventional wet end systems are designed with the age-old assumption that large volumes with low flow velocities are essential for system stability. This made the conventional system very complex and complicated to handle.Common problems include:

  • Low operating efficiencies when grade changes are frequent
  • Poor attenuation of low frequency variations
  • Accelerated bacteria and scale growth (function of low flow velocity and air)
  • Process variations from entrained air

Fiber in → Science applied

Applying modern solutions leads us to an efficient approach flow system: where stock is composed just-in-time without disturbances. Integrated and simplified solutions offer the greatest payback.  Small process volumes with smooth flows enable fast reaction to disturbances or grade changes. 

Although the arrangement and operation of approach flow equipment can will vary from machine to machine, AFT has the tools available to analyze your approach flow system as a whole under the current circumstances and recommend specific components or actions to improve performance.