How OCC Pulping System Design Impacts Kraft Liner Board Quality | Leizhan
OCC Pulping System Design Directly Determines Kraft Liner Strength
The design of an OCC (Old Corrugated Containers) pulping system is the single most important factor influencing final kraft linerboard quality. A well-designed system achieves fiber length retention above 85% and contaminant removal efficiency over 95%, while a poorly designed one sacrifices fiber strength to detergency — or vice versa.
Technical Specifications — Leizhan OCC Pulping Line
| Parameter | Value |
|---|---|
| Production capacity | 200-800 TPD |
| Pulping consistency | 4-6% (D-Type Hydrapulper) |
| Screen basket slots | 0.20-0.35 mm |
| Fiber recovery rate | >95% |
| Energy consumption | 18-22 kWh/ton pulp |
| Reject rate | <10% |
Pulper Rotor Selection: The Starting Point of Fiber Quality
The D-Type hydraulic pulper with helical rotor design operates at lower RPM (180-220) compared to conventional pulpers (280-350). This gentler action preserves fiber length — a critical parameter for linerboard strength. Mills using Leizhan D-Type pulpers report 8-12% higher burst index compared to conventional drum pulpers on the same OCC furnish.
Screening Configuration: Balance Between Cleanliness and Yield
After pulping, the stock passes through coarse screening (6-8 mm holes) followed by fine screening (0.20-0.35 mm slots). The coarse screen removes large contaminants; the fine screen handles stickies and small plastics. A two-stage screening system with tailing screen recovers fibers from the coarse reject stream, pushing total fiber recovery above 95%.
FAQ
What OCC quality is suitable for kraft liner production?
Mixed OCC with a minimum 80% old corrugated containers content works well. The remaining 20% can include kraft paper bags and cartons. Avoid OCC with heavy wax coating or wet-strength additives — these require additional dispersing equipment.
How much energy does an OCC pulping system consume per ton?
A complete OCC pulping system (pulper + screening + cleaning) consumes 18-22 kWh per ton of finished pulp. The pulper alone accounts for 8-12 kWh/t. Variable frequency drives on the pulper motor can reduce start-up energy peaks by 30%.
How often should screening baskets be replaced in OCC lines?
Inspect every 6 months. Replace basket at 12-18 months for abrasive OCC furnishes. Signs of wear: increasing reject rate at constant throughput, decreasing accepts quality, and measurable slot widening.