Alkyl Ketene Dimer Wet End Hydrolysis in Alkaline Hardwood Furnish
Alkyl ketene dimer hydrolysis in alkaline hardwood stock converts active sizing wax into unreactive dialkyl ketone, raising chemical costs and felt deposits.
Total Retention
Retention Efficiency
Proportional mass balance ratios comparing retained solid materials on a papermaking forming wire to total headbox solids input define overall web formation effectiveness. Calculation of total retention measures the combined entrapment of wood fibers, fine material, and mineral fillers during initial sheet dewatering. High retention values reduce white water solids loading, lower chemical additive consumption, and maintain steady wet-end operations.
The operational domain applies to paper machine wet-end control, retention aid program evaluation, and fiber recovery system design.
Drainage Mechanism
Dewatering on the forming wire involves physical filtration of long fibers and colloidally driven flocculation of fine particles and fillers. Long fibers form an initial mat structure that mechanically traps larger particles, while chemical retention polymers bridge fine suspended materials onto fiber surfaces. Higher machine speeds increase vacuum forces and hydrodynamic shear, tending to strip unattached fillers through the wire mesh into the short loop system.
System adjustments, such as micropolymer or dual-polymer retention programs, optimize fine retention without inducing excessive fiber clumping that degrades sheet formation quality. Monitoring drainage rates along the forming table ensures high solids retention while preserving uniform sheet grammage profiles.
Retention Boundary
Retention limits are established by the mesh size of the forming fabric and the equilibrium between hydrodynamic shear forces and chemical flocculation strength.