6. Existing boilers were planned for a special fuel to be
burnt and the flue gas flux resulting from the fuel supply.
Compared to bituminous coal, wet agricultural residues
have a higher specific air consumption to produce the
same heat, which leads to an increase of the flue gas
flux with increasing part of the biomass burnt. The existing
design of the boiler limits therefore the part of the cocombusted
agricultural residue or alternatively a change
of the boiler may become necessary.