4-Stage Preheater Fuel Systems

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For Preheater Kilns, AFS Technology provides automated fuel feed systems that introduce Whole Tires and other Bulk Fuels to the feed shelf for staged combustion.  The fuel is gravity-fed in an environment designed to maintain negative pressure in the reducing zone and minimize the introduction of outside air to the back end of the kiln for optimal NOx reduction potential.

KILN TYPES: 4-Stage Preheaters; Precalciners

SYSTEM COMPONENTS (Full Automation): Double-Gate Airlock ValveWeigh Feed Conveyor; Zoned Accumulation Conveyor(s)Vertical ConveyorGround Systems Automation

FUEL SPECIFICATIONS: Whole scrap tires up to 48″ in diameter; chipped or shredded Tire Derived Fuel; other high-density Bulk Solid Fuels.

FUEL FEED RATE: Standard ten-second gate-release interval designed up to feed 6 tires per minute, adjustable through PLC and/or Control Room Interface.


  • 4-Stage Preheaters:  20% whole tires; 30% with Mixing Air
  • Precalciners:  5% whole tires fired on feed shelf; up to 40% when supplemented or replaced with Suspension Burning in calciner or riser duct.
  • NOx REDUCTION POTENTIAL: Up to 40% using whole tires; may exceed 50% using whole tires + Mixing Air

RETURN ON INVESTMENT: Typically under 12 months