The conventional control method for circulating fluidized bed boilers was presented.The flue gas system's original control strategy using the conventional air volume calculation method made the combustion unstable in variable working conditions.To solve this problem

a self-adaptive total air volume calculation method was designed in the air and flue gas system optimization scheme

which could ensure the combustion stability of the CFB boiler.Moreover

according to the bed temperature and oxygen volume fraction

the primary air and secondary air control methods were designed.Finally

through instance analysis

this methods was proved to be efficient in improving the moderating effect of flue gas system by its simple and versatility logic

it can be extensively applied to the CFB boilers.