Based on the experiences of some German manufacturers, the numbers of coal-feeding points can be considered from the following aspects: First of all, the numbers of feeding points of coal and limestone  should not be less than 2 points; Second, in view of bed cross-sectional area that single coal feeding-point is responsible, for the circulating bed, each coal-feeding point is responsible for 8 ~ 35 ㎡ bed surface; Third, depending on the nature of the fuel, the numbers of coal-feeding points are also different, such as the high volatile coal,  the coal feeding-point generally is placed under the dense phase in the bed height direction, and is determined with the system pressure balance.