Abstract:

The axial average concentration and entrainment of binary mixture particles in freeboard were measured in a φ500 mm×12500 mm large scale cold model perspex experimental equipment, and according to the axial average concentration in freeboard the transport disengaging height (TDH) of binary particle could be obtained.It was indicated that TDH of binary mixture particles increased with increasing superficial velocity and mass fraction of fine particles.The increase of TDH with increasing mass fraction of fine particles was the least when mass fraction of fine particles was near 0.4.Entrainment of binary mixture particles in freeboard increased with increasing superficial velocity.When superficial velocity was less than 0.6 m•s^-1, the increase of entrainment was prominent; moreover, when superficial velocity was more than 0.6 m•s^-1, the trend of the increase of entrainment of binary particle was weak.When superficial velocity was less than 0.5 m•s^-1, the increase of entrainment of binary particle with increasing mass fraction of fine particles was not obvious; when superficial velocity was more than 0.5 m•s^-1, entrainment of binary particle increased with increasing mass fraction of fine particles.According to the analysis of experimental data, a mathematical model of TDH of binary particle was established.Calculated values were in good agreement with experimental values.