| Flow, heat transfer and reaction of local denser clusters are different from isolated particle in circulating fluidized bed boiler. The combustion process of carbon particle cluster directly affects carbon burnout, and the desulphurizing process of limestone particle cluster affects the desulphur efficiency. The experimental or theoretical study of distribution of temperature and reaction production in cluster has not been done due to the complexity of cluster reactions.Gas passing through an isolated particle cluster has been numerically simulated. It is found that the ratio of gas flux passing through a cluster increases with the increase of porosity and jetting velocity. The total forces on particles are different from each other in the cluster, and that on an isolated particle is higher than on any particle in the cluster. The ratio of cluster drag coefficient to isolated particle drag coefficient increases with the increase of porosity.The burning properties of an isolated char particle cluster were numerically studied in the stream. Results indicated that the burnout carbon of cluster increases with the increase of porosity, jetting velocity and gas temperature. The burnout carbons of particles are different from each other in the cluster, and that of isolated particle is higher than any of particle in the cluster. The formation of NO and N2O are restrained due to particle clustering.The desulphurizing properties of an isolated calcium oxide particle cluster were numerically studied in the stream. Results showed that the captured sulfuric dioxide of cluster increases with the increase of porosity and jetting velocity. With the increase of temperature the captured sulfuric dioxide firstly increased, reach a maximum, and then decreased. The amounts of sulfuric dioxide captured by particles in the cluster are different from each other, and that captured by isolated particle is higher than any particle in the cluster. The agglomeration of limestone particle can decrease the output of NO.
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