Menetelmä biopolttoaineen polttamiseksi fossiilista polttoainetta käyttävässä kattilassa

The invention relates to a method of co-firing biofuel in a boiler designed for burning a fossil main fuel such as coal, brown coal or peat, the method comprising the steps of first grinding the main fuel for burning, then feeding the main fuel with the help of a carrier gas into at least one burner, and burning the main fuel in the boiler combustion chamber. After the grinding of the main fuel, biofuel is mixed into the flow of the pulverized main fuel prior to the feed of the fuel mixture into the burning flame, whereby the biofuel is co-fired with the main fuel in the same flame. The biofuel may be hog wood, straw, fuel separated from community waste or other available biomass.