Solving Fiber Blinding in Paper Mill Shower Water Recirculation

2026-10-31

1. Operational Context & Technical Challenge

A mid-sized paper mill in Central Poland operates two continuous paperboard machines. The facility recycles process "white water" (450 m³/h) to feed high-pressure wire-cleaning shower nozzles.

The recycled stream carries fine cellulose fibers, sticky starch residues, and inorganic fillers ($TSS \approx 180\text{ mg/L}$). The mill previously used manual dual-basket strainers to protect the shower bars.

However, fibrous materials caused rapid "fiber stapling" across the basket mesh. When differential pressure ($\Delta P$) surged beyond 0.12 MPa, fine fibers squeezed through the screen slots and clogged the 1.2 mm shower nozzles.

This resulted in uneven wire cleaning, wet-end paper sheet tears, and forced operators to stop the machine line 3 to 4 times a week for manual nozzle clearing. Each stoppage cost approximately €3,500 in lost production.

2. Engineering Intervention

LEFILTER supplied a compact LF-BS-600 Automatic Mechanical Scraping Filter designed specifically for sticky, fibrous fluids:

• Wedge Wire Profile: Installed a 100 $\mu\text{m}$ 316L wedge wire screen. The smooth, flat face of V-slot wire prevents fibers from lodging into the apertures.

• Continuous Mechanical Scraping: Internal spring-loaded polyurethane scraper blades continuously rotate against the screen face at 14 RPM. The blades shear away fiber mats and sticky starch gel before hydraulic blinding can occur.

• Concentrated Waste Purge: The scraped solids settle into a conical bottom collection chamber. A pneumatic knife gate valve opens for 5 seconds every 20 minutes, discharging concentrated fiber slurry back into the pulp stock chest without stopping main filtration flow.

3. Verified Field Results

• Zero Shower Nozzle Blockages: Shower nozzle clogging dropped to zero, completely eliminating paper sheet web breaks caused by uneven wire washing.

• Production Downtime Savings: Recovered 14 hours of lost paper machine production time per month, yielding a direct monthly gain of ~€21,000.

• Fiber Recovery: Reclaimed ~1.2 tons of usable pulp fiber monthly from the backwash discharge stream.

• Project ROI: The total capital payback for the filter skid was achieved within 2.8 months.