Experimental study on combustion of rice hull in CFB

The combustion characteristics of agricultural wastes in circulating fluidized bed(CFB) are investigated with rice hull as the feedstock.The effects of fluidizing velocity,particle size and air distribution on the combustion behavior are discussed in detail,as well as agglomeration phenomenon in biomass combustion.Under the fluidizing air velocity at 2-6 m/s,the temperature distribution in CFB furnace is relative uniformity,together with steady combustion state.However,particle size is inversely proportional to combustion efficiency.The smaller the particle size,the shorter the time is needed to reach steady combustion,and the higher the furnace temperature.And the best ratio of secondary air in total air input is 50%-70% for steady CFB operation.In order to avoid the high temperature agglomeration in combustion process of straw materials,the operation temperature in CFB should be kept below 900℃,with relatively uniform temperature distribution obtained under 850℃.