
669Oxy-Fuel Fluidized Bed Combustion
changed to oxy-fuel ring without having to stop the
fuel feed. The bed temperature was kept at 850°C dur-
ing air ring and the rst part of the oxy-fuel test and
was then increased to 950°C for the second period of
oxy-fuel testing. It can be seen that as the combustion
mode switched from air ring to oxy-fuel ring, the
concentration of CO
2
rapidly increased and stabilized
at about 85%. The concentration of O
2
stayed steady at
3%–5%. The concentration of CO decreased from 100
ppm at 850°C to ∼20 ppm at 950°C due to higher O
2
con-
centration, which leads to better fuel burnout. However,
NO
x
concentration stay ...