Atmospheric Circulating Fluidized Bed Combustion Boilers (CFBC)
In a circulating system
the bed parameters are so maintained as to promote solids elutriation
from the bed. They are lifted in a relatively dilute phase in a solids
riser, and a down-comer with a cyclone provides a return path for the
solids. There are no steam generation tubes immersed in the bed.
Generation and super heating of steam takes place in the convection
section, water walls, at the exit of the riser.
CFBC boilers are
generally more economical than AFBC boilers for industrial application
requiring more than 75 – 100 T/hr of steam. For large units, the taller
furnace characteristics of CFBC boilers offers better space utilization,
greater fuel particle and sorbent residence time for efficient
combustion and SO2 capture, and easier application of staged combustion
techniques for NOx control than AFBC steam generators.
