Biomass Plant · 5 min read
Biomass boiler clinker formation: causes and control
By Engr. Muhammad Aalam
Manager Utilities, Ismail Resin · Industrial utilities engineer
What clinker is
Clinker is fused ash. Biomass ash contains potassium, sodium and silica that can melt at 800–1000 °C, much lower than coal ash. When the bed gets too hot, the ash softens, sticks together and blocks the grate air, which in turn creates hotter spots and more clinker.
Main causes
- Fuel with high alkali content, such as some agricultural residues
- Local over-firing from uneven fuel spreading
- Insufficient under-grate air or blocked grate holes
- Fuel moisture swings causing operators to over-correct
- Sand and soil contamination in the fuel
Control measures
Blend fuels to reduce alkali content, keep moisture consistent, maintain even fuel spreading and ensure regular de-ashing. Monitor furnace temperature and keep it below the ash softening temperature. Clean grate air holes at every planned shutdown. Many plants also use over-fire air to complete combustion above the bed rather than inside it.
This guidance is general. Always follow the equipment manufacturer's manual and your site safety procedures. See our engineering disclaimer.