According to the needs of boiler load, to increase coal supply amount can improve the bed temperature, on the contrary, the bed temperature is reduced; To decrease primary air amount can improve the bed temperature, on the contrary, the bed temperature is reduced; To decrease the returns amount can improve the bed temperature, on the contrary, the bed temperature is reduced; To increase the amount of limestone can decrease the bed temperature, on the contrary, the bed temperature rises high.  (lsh)