Experimental study on rice hull combustion in circulating fluidized bed

Rice hull was chosen as feedstock to conduct experiments, and the thermogravimetric analyzer was used to analyze its pyrolysis characteristics.The combustion process research was carried out in circulating fluid bed(CFB) in order to find important combustion parameters. When the ratio of secondary air output and first air output lies in the range of 1.0～1.2, and the ratio of air to material is 4.2 m³/kg, the temperature in firebox can be controlled in the range of 800～850℃. Temperature was relatively uniform with little fluctuant range only when normal coke circulating appeared. The ash melting point of rice hull is 1230℃, but it are easy to sinter at 1000℃ and agglomerate within 700～800℃. Two methods can be helpful to avoid the agglomeration in straw combustion process in CFB. The first is to input quartzite sand when the temperature in firebox was high with high circulating wind rate. The second is to choose 1 m/s as fluidized rate when ignition starts.