Drying Systems in Coating Board Production: Infrared, Air Float and Cylinder Configuration

Drying: The Largest Energy Consumer in Coating Board Lines

Drying accounts for 55-65% of total thermal energy in coating board production, and the drying section configuration directly determines coat weight uniformity, binder migration and surface gloss. Selecting the right combination of infrared, air float and cylinder drying for each coating station is one of the highest-impact decisions in a board machine rebuild or new line specification.

Technology Roles in the Drying Sequence

Immediately after blade or curtain application, the wet coating at 52-68% solids cannot tolerate contact. Gas or electric infrared modules provide the first 30-40% of evaporation at high intensity without touching the sheet. Air float dryers then carry the web on cushion nozzles while completing non-contact drying at 150-350 degrees C air temperature and 30-60 m/s nozzle velocity. Only after the coating reaches critical solids does the web transfer to steam-heated cylinders at 3-8 bar for final moisture profiling to 5-8%.

Performance and Consumption Data

Typical figures for a 400 TPD duplex board line with two coating stations: specific steam consumption of 1.6-2.0 t of steam per ton of paper for the full drying section, with 0.3-0.5 t/t attributable to pre-dryers after each coater. Industry comparisons show that replacing worn air dryer nozzles and sealing enclosure leaks cuts thermal losses 8-12%, roughly USD 25,000-35,000 annually at a steam cost of USD 22 per ton. Infrared zoning with 10-15 kW/m emitter density control also reduces binder migration streaks, lifting IGT surface strength readings by 15-20% on pigment-coated grades.

Maintenance Recommendations

• Clean air float nozzle plates weekly; plugged nozzles create CD moisture streaks within days
• Inspect infrared emitter output quarterly; emitter degradation beyond 15% requires bank replacement
• Check dryer fabric tension and guide roll alignment monthly to prevent web wrinkling at speed changes
• Steam joint and syphon inspection every 6 months prevents condensate flooding and uneven cylinder surface temperature

Complete Coating Lines from Leizhan

Leizhan Technology supplies coating board production equipment from stock preparation through coating kitchens and drying sections, engineered for 200-1000 TPD output. Provide grade structure and target coat weights for a drying section energy review and configuration proposal.

📧 leizhanzhang@gmail.com