Biomass fuels feature low ignition point, generally 270~300℃, fast burning speed, high volatile matter, and easy deflagration. Therefore, fuel supply shall be continuous and uniform, especially low-moisture, fine-grained biomass fuels.

Biomass fuel feeding equipment shall take consideration of the fuel size, fuel density and moisture content.

  • Biomass fuel with moisture less than 20% and size less than 15mm shall select screw feeder or belt conveyor.
  • Biomass fuel with moisture more than 20% and size 15~100mm shall select scraper conveyor or shaftless screw conveyor.
  • Biomass fuel with moisture less than 15% and size less than 5mm shall select screw feeder, belt conveyor or pneumatic conveyor.
  • Besides pellet fuel, biomass fuel can also be stored in the silo in original or crushed state. The silo shall be in taper size with big bottom and small upper part.

Feeding to the furnace shall take the volatile matter and size of biomass fuel into account. The feeding mode and equipment selection shall match the combustion mode, which shall prevent catching fire outside the furnace. The fuel feeding shall be smooth, continuous, uniform and adjustable.

  • Biomass fuels with high volatile matter and size less than 3*5mm shall select air blowing and spreading. This is beneficial to fuel preheating, drying, catching fire and burnout.
  • Biomass fuels with low volatile matter and size less than 50mm shall select planet feeder or screw feeder. Biomass fuel with size 50~150mm may select scraper feeder or chain belt feeder. Longer prehensile fuel shall select anti-twist screw feeder.
  • Lower moisture, finer particle size and faster burning rate promotes catching fire outside the furnace (or backfire). Such biomass fuel shall adopt air blowing and spreading. To avoid backfire, the blowing speed shall be more than the suspended wind speed and flame propagation speed. The flame speed shall be determined by tests.
  • For block and piece type biomass fuel with small density, take two-stage feeder electric interlock control to prevent back fire.