Bag filter explosion !! state possible reasons ?

1. Use only inert gas for heating mill flow; Gas of less than 4% oxygen preheater gases (advisable. )
2. Bag filter bags should be selected of anti-static property and other properties like Anti-acidic and Anti-hydrostatic
3. Bag filter structure should have proper strong earthing property. Very important to do megger once in a year
4. High CO mill tripping at 2000ppm should be provided. Do not operate more than 12% oxygen at its outlet in presence of CO.
5. Left over coal inside mill or bag house of high VM value may burn spontaneously with passage of time. Better to clean up before stoppage by operating its transport.
6. Most explosion occurs at mill start up. Do not allow water to enter in bag house even from purging air.
7. Explosion doors of membrane type at right place on bag house should be there.
Also explosion door needed at gas duct after mill and before bag house
8. Check safety interlocks especially of temp. and CO interlocks.
9. All others you may find especially CO2 extinguisher purging interlock with mill and bag house
10. CO2 storage and purging system should be 100% in order