Sticky Line Indication Systems

Optimizing dryer performance with Sitcky Line Indictator Systems (SLI Systems)

Managing Sticky Powders

Milk powders with high lactose content (e.g., NDM, SMP, WPC 34) can become “sticky,” causing dryers, cyclones, and bag houses to plug. This stickiness depends on the glass transition of lactose:

  • Glassy state → rigid, non-sticky
  • Rubbery state → pliable, sticky

Temperature and humidity drive the transition. Low humidity reduces stickiness but also lowers dryer capacity.

Optimizing Dryer Performance

The SLI System continuously monitors key factors affecting humidity inside the dryer:

  • Ambient air temperature & humidity
  • Combustion moisture
  • Inlet air flow & temperature
  • Feed composition, solids & temperature
  • Secondary drying air flow & temperature

Real-time data is processed through algorithms in the dryer PLC, which calculates an Operating Point. This is compared to the product’s sticky line (safe vs unsafe zone) and displayed on an HMI screen. Operators can then push performance close to the sticky line — maximizing capacity while avoiding plugging.

When SLI Is Most Valuable

  • Switching between products with different lactose levels (e.g., NDM vs SMP)
  • Seasonal weather shifts (dry winters vs humid summers)
  • Daily weather swings (cool mornings vs humid afternoons)
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