Abstract:

Effects of feeding structures with solids from single or double sides and ratio of solids circulation rates from both sides on the gas-solids flow characteristics were investigated in a cold model apparatus of a novel dual-loop circulating fluidized bed, and a new definition of gas-solids contact efficiency was also proposed to evaluate the reactor. Results showed that the solids feeding methods had very little impact on the axial and radial distribution of solids concentration when the solids came down from one or two sides, and the differences mainly lay in the pre-lifting and bottom reaction zones of the riser. When two strands of solids were feeding bilaterally into the riser bottom together, the solids contribution presented a better radial distribution than that of only single strand of solids feeding, and closer solids circulating rates of the two loops would contribute to better radial uniformity and axial symmetry of solids concentration profiles with higher gas-solid contact efficiency. And higher gas-solids contact efficiency could be obtained when decreasing superficial gas velocity or increasing solids circulation rates.

Key words: dual-loop circulating fluidized bed, feeder structure, solid concentration, radial uniformity extent, axial symmetry, gas-solid contact efficiency