1.The primary air is fed from the bottom of the hearth, namely the dense-phase zone, it main function is to ensure the fluidizing of bed of materials, and meanwhile the proportion of the primary air decides the combustion portion of dense-phase zone. The temperature of dense-phase zone is controlled by the adjustment to the combustion portion, for example under the condition of invariable primary air amount, the coal quality becomes poor and the relative combustion portion is reduced, at this moment the bed temperature is in decreasing tendency and the output is reduced. We can change the combustion portion by increasing the coal feeding amount to make the bed temperature recover its original value in order to meet the load requirement. The size of combustion portion decides the boiler output. The secondary air is slantly arranged at the dilute phase zone layer by layer, it main function is to make up the insufficient primary air amount. As the variable in the operating adjustment, to strengthen the combustion at the upper part of the hearth, namely the combustion of dilute-phase zone, similarly will decides the combustion portion of the dilute-phase zone, for example, under the condition that the primary air and coal feed are constant and the secondary air is not fed, the combustion portion of dilute-phase zone will be relatively less, at this moment we put the secondary air into operation according to a certain proportion, the total combustion portion of dilute-phase zone and inside the boiler will be increased accordingly, the combustion in dilute-phase zone will be strengthened and the boiler output will be increased accordingly. When the coal with higher calorific value and stronger post-flammability is burnt, the increasing of secondary air volume and strengthening the combustion in dilute-phase zone will play a role of reducing the returns temperature.

2.Adjusting coal feed amount under the condition of air amount unchanged: If the coal quality is relative stable and does not change greatly, there shall be a certain expectation to the bed temperature. According to the tendency of bed temperature, the coal feed amount is adjusted by means of adjusting method of earlier stage. The requirement of load is met by means of changing the bed temperature and increasing/decreasing the radiative heat transferring.

3.Controlling the circulating ash amount: The circulating ash is fed in the dense-phase zone, the heat release in dense-phase zone is mainly absorbed by the circulating ash. After the circulating ash returns back to the hearth, making the bed temperature tend to be stable, thus playing a role of suppressing the bed temperature. Sometimes the insufficient circulating ash causes the bed temperature to rise and affects the boiler to operate with load, so the circulating ash amount may be increased to reduce the bed temperature; sometimes the too much circulating ash will cause the bed temperature to reduce gradually, part of the circulating ash may be discharged ( this case mostly happens when the boiler is operating under low load and the ash content in coal is larger) for controlling the bed temperature.