| Mixing is an important unit operation in chemical,pharmaceutical and food industries.Stirred tank reactors have been widely used in many industries.Power consumption is an important parameter in the design and scale-up of stirred tank reactors.And the cohesiveness between particles can cause great influence on power consumption in the process of mixing.The effects of relative liquid volume,rotational speed,and fill level on power consumption were experimentally investigated in a cylindrical stirred tank with 3-4 mm silica gel particles.Meanwhile,the influences of moisture content,rotational speed and fill level on the power consumption of cohesionless particles were compared with adhesive particles.The discrete element method(DEM)and Hertz-Mindlin with JKR model were used to investigate the effects of the adhesion of particles with different relative liquid volumes on the power consumption.The results show that for the saturated particles with adhesion,the power consumption first increases and then decreases with the increase of the relative liquid volume,and reaches a maximum when the relative liquid volume of 0.0162.The power consumption of cohesionless particles increases linearly with the increase of moisture content.With the increase of the rotational speed,the power consumption increases faster,but the rotational speed influence index on the power consumption decreases first and then increases with the increase of the relative liquid volume.The power consumption of cohesionless particles increases faster and faster with the increase of rotational speed.The maximum power consumption is 1.8 times of the power consumption with saturated particles.However,the power consumption of cohesionless particles increases linearly with the increase of fill level.A new method for indirect measurement of cohesion between particles was proposed,and a linear relationship between power consumption and cohesion was obtained. |
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