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Coal and biomass cofiring: fundamentals and future trends 131
Secondary air
Fuel
+
Primary air
Ash
Pulverized fuel
combustor (PFC)
Figure 5.4 Pulverized fuel combustor.
combustors and circulating fluidized bed combustors (Fig. 5.5). In general, fluidized
bed boilers can substitute higher levels of coal with biomass than pulverized coal-
fired or grate-fired boilers. Fluidized bed boilers can handle biomass with higher mois-
ture content (10%e50% instead of <25%) and larger particle sizes (<72 mm instead
Secondary air Secondary air
Bed Bed
Fuel Fuel
Primary air Primary air
Ash Ash
Bubbling fluidized bed Circulating fluidized bed
combustor (BFBC)
combustor (CFBC)
Figure 5.5 Bubbling and circulating fluidized bed combustors.
