The continuous measurement of thinstock consistency is a tool for papermakers to make informed changes in machine settings to achieve the desired wet end conditions. It will provide an immediate feedback of wet end conditions for operators at start-up or during a grade change. The measurement can also highlight process instability which effects the final consistency on the wire.
A continuous trend of retention will provide the following information:
Shows up approach flow instability
Faster adjustment of Thinstock Cs during start-up and grade changes
Process follow-up of most effective operating levels.
Process disturbance indication for immediate correction
Thinstock %Cs. Target
In the this example the slice gap is adjusted. Closing the slice reduces the whitewater flow and increases the thinstock consistency. Opening the slice gap has the opposite effect.
A cyclical hydraulic disturbance can be seen in the trend plot. This is corrected by the total head controller within the QCSystem to stabilise the M.D. weight. Ultimately this will affect the ability of the quality control system to maintain the basis weight close to target.
Thinstock %Cs. can be maximised within formation constraints to aid wet end retention. Often on machines with a wide grade range the thinstock %Cs is set low to aid formation.
Product - Thinstock %Cs.
