The diagram of the 600MW supercritical CFB boiler with an
annular furnace can be found in . Compared with the traditional
furnace, more tubes can be arranged on the inner ring sidewall of
the proposed boiler to ensure adequate heat absorption, which
reduces the available furnace height, and consequently,
economizes boiler cost. Considering the low heat load in an annular
furnace, a smooth tube with a low mass flux is used in the water
wall design. Low mass flux technology (G < 1000 kg m2 s1) is
extensively applied in boiler design to ensure sufficient heat
absorption of the water wall and to reduce furnace height. In addition,
this technology can significantly reduce flow resistance and
improve the economic benefits of a power plant. Applying low
mass flux, particularly in smooth tubes, is a key issue in maintaining
water wall temperature within a permissible range to ensure
the safe operation of the boiler.