High-Consistency Refining Technology for Corrugated Medium and Testliner Production

Refining Strategy for Corrugated Grades

Corrugated medium and testliner production demands a refining strategy that balances strength development against energy consumption and drainage. Unlike fine paper grades that require extensive fibrillation, corrugated grades benefit from moderate refining at higher consistency of 3.5 to 4.5 percent, targeting a freeness reduction of 80 to 120 mL CSF with specific edge load (SEL) of 1.5 to 2.5 W-s/m for OCC-based furnishes.

Disc Refiner Specifications and Performance

Double disc refiners with disc diameters of 660 mm, 910 mm, or 1,100 mm serve the full capacity range from 100 to 600 TPD. The 910 mm refiner, driven by a 450 to 900 kW motor at 1,480 rpm, delivers a no-load power of 18 to 22 percent of installed capacity. This represents an improvement of 10 to 15 percentage points over older single-disc designs. Refiner plate patterns are selected based on furnish characteristics: fine-bar patterns of 2.0 to 2.5 mm bar width and 3.0 to 3.5 mm groove width for OCC, and medium-bar patterns for mixed waste.

Energy Benchmarking and Savings Potential

Typical refining energy for corrugated grades ranges from 60 to 100 kWh per ton, with the refiner accounting for 60 to 70 percent of total pulping department energy consumption. Modern double disc refiners achieve 15 to 20 percent energy reduction compared to conventional designs through optimized plate geometry and reduced hydraulic losses. For a 400 TPD line, this translates to annual energy cost savings of approximately 25,000 to 35,000 USD.

Process Control and Automation

Automatic refiner control systems adjust plate gap based on net specific energy in kWh per ton and freeness targets. Load-sensing hydraulics maintain consistent plate gap within plus or minus 0.02 mm, preventing plate clash during furnish variations. Online freeness transmitters provide feedback every 15 to 30 seconds, enabling tight control of refined stock quality before the paper machine approach system.

Plate Life and Maintenance Intervals

Refiner plate life depends primarily on furnish contamination levels and applied specific edge load. Under normal OCC processing conditions, plate sets last 1,200 to 1,800 operating hours. Plate wear is monitored by tracking the plate gap at constant power. A 0.5 mm increase at the same power level indicates plate change is due within 100 hours. Bearing temperature monitoring provides early warning of impending failure, with alarm thresholds typically set at 75 degrees Celsius.

For refiner selection, energy optimization, and technical support, contact the engineering team.

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